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HomeMy WebLinkAbout2001-03-22-LYMAN CREEK RESERVOIR IMPROVEMENTS EXECUTIVE MEMORANDUM & TECHNICAL MEMORANDUMS 1-6 Lyman Creek Reservoir Improvements Executive Memorandum Technical Memorandums 1 -6 ry R'�315 Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 March 22, 2001 Prepared By: HKM Engineering Inc. 601 Nikles Drive, Suite 2 • Bozeman,Montana 59715 406-586-8834 IV f Lyman Creek Reservoir Improvements Report Contents Executive Summary Memorandum No. I Memorandum No. 2 Memorandum No. 3 Memorandum No.'s 4 & 6 Memorandum No. 5 *Please Note all Appendices for the attached Memorandums are in a separate report. Lyman Creek Reservoir Improvements Executive g ^•"1 �r. v 'taw.`.—.......�...... Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 March 22, 2001 Prepared By: HKM Engineering Inc. 601 Nikles Drive, Suite 2 • Bozeman,Montana 59715 • 406-586-8834 Lyman Creek Reservoir Improvements Executive Summary Table of Contents 1.0 Introduction ......................................................................................... 1.1 Facility Background/History...................................................................I 1.1.1 Lyman Creek Reservoir.............................................................1 1.1.2 Booster Station.......................................................................2 2.0 Summary of Findings and Recommendations........................................................3 2.1 Lyman Creek Reservoir........................................................................4 2.1.1 Rehabilitation of Concrete Panels................................... .............4 2.1.2 Reservoir Cover.....................................................................4 2.1.3 Reservoir Baffle.....................................................................5 2.1.4 Chlorination System...............................................................5 2.1.5 Fluoride System......................... ...........................................5 2.1.6 Building Modifications.............................. .............................6 2.1.7 Outlet Piping Control Building/Vault..........................................6 11.8 Control Systems.....................................................................6 2.1.9 Electrical Service............................................... ...................6 2.1.10 Service Backup Power.............................................................6 2.1.11 Telemetry............................................................................7 2.1.12 Lightning/ Surge Suppression....................................................7 2.2 Lyman Creek Reservoir Embankment Stabiltiy............................................7 2.2.1 Earthen Berm........................ .............:....,*,,--—*''*****-**...—7 2.2.2 De-Watering with Respect to Reservoir Repairs...............................7 2.3 Booster Station..................................................................................8 2.3.1 Lyman Creek Reservoir Operational Strategy..................................8 2.3.2 Booster Station Operational Strategy.............................................8 2.3.3 Pressure Reducing Valves.........................................................9 2.3.4 Booster Station Repairs...................................................... .....9 2.3.5 Booster Station Automation/Controls............................. ............9 23.6 Telemetry................................................................. .........10 2.3.7 Line Voltage Service............................................................-10 2.3.8 Service Backup Power............................................................10 2.3.9 Lightning/ Surge Protection.....................................................10 2.4 Spring Collection Gallery Recommendations.............................................10 3.0 Engineers Opinion of Cost............................................................................10 Table of Contents Continued Tables: Table 1 Master Engineer's Estimate.......................................................................11 Figures: Figure1.1.......................................................................................................1 Figure1.2.......................................................................................................2 Figure1.3.......................................................................................................3 Lyman Creek Reservoir Improvements Project Executive Summary March 22, 2001 1.0 Introduction In the fall of 1999 the City of Bozeman (City) awarded the Lyman Creek Reservoir Improvements Project to HKM Engineering. The project included the evaluation of alternatives for improvements to the Lyman Creek Reservoir, water booster station, collection gallery and the long range planning use of the reservoir and booster station. To facilitate the preparation and review of the study it has been broken into a series of technical memorandums evaluating separate aspects of the project. Following this executive summary is a complete set of the finalized technical memorandums. 1.1 Facility Background/History Figure 1.1 Lyman Creek Reservoir; Existing Cover and Support System 1.1.1 Lyman Creek Reservoir Lyman Creek Reservoir was the original water storage basin for the City of Bozeman constructed in the late 1800's. In 1909, and then again in the early 1970's, the basin was enlarged to provide additional storage. The reservoir is a below grade trapezoidal shaped section constructed of concrete slabs cast against earth. The reservoir has a 54' x 73' flat bottom, side walls that slope at 1.5 : 1 (H : V) extending angularly 28 feet to a vertical wall that extends another 4 feet for a total depth of 32 feet. The top of the reservoir is 241' x 157' for a total approximate volume of 5.4 million gallons to the top of the concrete. Executive Summary March 22, 2001 I w Figure 1.2 Drained Reservoir In 1989 because of more stringent drinking water standards a high-density Polyethylene (HDPE) cover and baffle system was installed at the reservoir. The cover was designed to float on the reservoir and was supported by a cable and pulley system around the perimeter to allow for water level fluctuation. The baffle was supported from the cover and weighted to the bottom to minimize the short-circuit flow of water between the inlet and outlet pipes of the basin. In the fall of 1998 the HDPE cover had deteriorated to such a degree that it could longer be maintained. At that time the City took the reservoir off line from the City water system, but continued to route chlorinated water through the basin at approximately 500 gpm. 1.1.2 Booster Station In approximately 1955 a water booster station was constructed on Pear Street just south of the current alignment of Interstate Highway I-90 to boost water from the North Pressure Zone to the South Pressure Zone of the Bozeman Water System. 2 Executive Summary March 22, 2001 t -- Figure 1.3 Booster Station In 1986 the booster station was upgraded adding pressure sustaining valves and pump control valves. The pressure sustaining valves (8" and 2") were added to maintain pressure within the North Zone. The pump control valves were intended to provide a soft start to the three existing pumps and reduce water hammer within the system. Prior to the installation of the pump control valves, portions of the South Zone had been damaged when the booster pumps were started. Since the installation of the 1986 improvements the booster station has not been operated. 1.1.3 Lyman Creek Spring Collection Gallery In 1986 and 1990 because of more stringent drinking water standards the old system of diverting Lyman Creek surface water directly to the Lyman Creek Reservoir was abandoned. In place of the surface water diversions, two spring collection galleries (boxes) were installed at the Lyman Creek Spring. The intent of these collection galleries was to capture the spring water before it flowed out of the ground surface- therefore, creating a drinking water source that is not under the influence of the open atmosphere. This essentially converted the Lyman Creek Drinking Water Supply System from surface water into groundwater source. From the spring boxes, the water flows through a 10,000 foot long 16"to 18" diameter pipeline where it is delivered to the Lyman Creek Reservoir. Over this distance, the pipeline drops approximately 530 feet in elevation. To reduce line pressure, two Pressure Reducing Valve (PRV's) stations are installed along the pipeline, each station consists of 2 regulating valves that reduce upstream pressure by 70-100 PSI. The net capacity of the pipeline is approximately 2.7 to 3.8 MGD which approximately matches the decreed water rights of the springs. 2.0 Summary of Findings and Recommendations In the process of preparing the attached technical memorandums B KM Engineering has completed comprehensive facility evaluations of the reservoir, booster station and spring collection gallery. These evaluations involved on-site structural, civil and electrical inspections, 3 Executive Summary March 22, 2001 evaluation of improvement alternatives, updating the City Water Model, computer modeling numerous utilization scenarios for the current and 20-year planning window, and the preparation of detailed engineer's opinion of cost for construction and life cycle costs. The following is a summary of the principal findings and recommended improvements to the Lyman Creek Reservoir, Booster Station and Spring Collection Gallery. Detailed findings and recommendations are provided in the following sections of this study. 2.1 Lyman Creek Reservoir The following recommendations are for improvements to the Lyman Creek Reservoir basin, cover, control building, chorine and fluoride systems and control equipment. 2.1.1 Rehabilitation of Concrete Panels: The concrete panels that line the reservoir are in reasonable condition but are nearing the end of their design life and need restoration if they are to continue to function. If left unattended the deterioration of the panels will accelerate and potentially jeopardize the stability of the earthen embankment at the southwest end of the reservoir. Of the three options evaluated, it is our recommendation to use a HDPE or Polypropylene Reservoir Lining to restore and protect the function of the reservoir. By lining the reservoir with a poly-liner, a long-term positive seal will be achieved. This seal will eliminate leakage into the adjacent soil and isolate the concrete panels from the water. By removing the water contact, freeze-thaw action should be minimized on the concrete panels substantially extending the service life of the panels. In conjunction with the liner installation the existing concrete panels should be thoroughly cleaned and re-mortared to provide a consistent surface free of defects that may potentially puncture the liner. In addition an under-drain system should be installed between the liner and the concrete panels to prevent the potential "floating" of the liner when drained. 2.1.2 Reservoir Cover: A critical element in preserving the function of Lyman Creek Reservoir will be to provide an adequate roof or cover over the repaired or lined concrete panels. The majority of concrete panel deterioration to date can be directly related to weathering and freeze-thaw action. A proper roof or cover will substantially reduce these environmental elements, extending the service life of the facility. We recommend that a structural roof, not a floating cover, be used to cover the reservoir. This recommendation is based on potential impact of the proposed EPA Radon rule. The proposed rule will require that groundwater sources such as Lyman Creek be treated for radon. A structural roof system is well suited to provide the required aeration and ventilation for radon removal and may not require any additional treatment to meet the proposed rule. Where as a 4 Executive Summary March 22, 2001 floating cover system would require a separate high performance Packed Tower Aeration, Multi- Stage Bubble Aeration and other suitable diffused bubble aeration technology for radon removal. Of the structural roof systems evaluated, a Pre-Cast, Pre-Stressed Concrete Roof appears best suited for the application from both a functional and economic perspective. A Pre-Cast roof system will have a high initial construction cost but will more than make up for the cost difference compared to other options with minimal life cycle maintenance costs. A pre-cast roof will only require minimal inspection and grout patching, and will not require costly repainting that would take the reservoir off line. A structural roof system such as a pre-cast system will provide added benefit protecting a poly-liner from UV and other environmental elements potentially lengthening the service life of the liner. For the ventilation of the cover, we recommend a variable volume ventilation system to be utilized. The reductions in fan energy between a constant and variable system will payback the difference within two years. 2.1.3 Reservoir Baffle: The preferred baffle system is dependent on the roof and/or cover system selected. If a rigid structural roof is used a curtain baffle system that is suspended between the columns is recommended. This will provide a passive system that will maximize chlorine contact time and minimize potential circulation dead spots within the reservoir. If a floating cover is used a diffuser baffle system on the outlet and inlet pipes is recommended. This also will provide a passive system that will maximize chlorine contact time and minimize potential circulation dead spots within the reservoir. 2.1.4 Chlorination System: It is our recommendation that the existing chlorine gas system be replaced with a liquid chlorine system. A liquid system would minimize the risk of exposure of both the operators and the public to chlorine gas. The liquid feed system would require less equipment, and the operational requirements would actually be less demanding than the existing gas feed system. Annual chemical costs would be higher due to the high unit cost of the sodium hypochlorite solution but a reasonable tradeoff for the simplicity of the feed system and the elimination of the major safety concerns of chlorine gas. 2.1.5 Fluoride System: It is our recommendation that the existing fluoride system be replaced with a liquid fluoride system. The existing Batch mixing systems for combining crystalline forms of fluoride and water to form a fluoride solution are considerably more complicated, operator intensive, and difficult to regulate. With the liquid form of fluoride now readily available, a liquid feed system is the most practical and simple system available. Operator contact with fluoride dust is eliminated, and the 5 Executive Summary March 22, 2001 feed equipment is very simple and affordable. The overall operating cost would likely decrease with labor and power costs taken into account. 2.1.6 Building Modifications: It is our recommendation that the existing masonry block control building at the reservoir be demolished and replaced with a new 600 square foot building. The existing control building is in poor condition and is of insufficient size to accommodate the numerous control and chemical feed improvements proposed for the facility. The new structure should be located in close proximity to the existing structures and inlet pipe. 2.1.7 Outlet Piping Control Building/ Vault: To facilitate proper chlorine residual within the outlet pipe from the reservoir, we recommend an outlet pipe control vault or building be constructed near the toe of the embankment at the southwest end of the facility. The proposed vault will house a chlorine injector, meter, valves, and other appurtenances necessary to provide a flow regulated chlorine injector system. The system will monitor residual chlorine from the reservoir and modulate chlorine content as needed to meet residual goals. The operational strategy of the reservoir will be to inject liquid chlorine at the inlet to the reservoir such that under normal operating conditions the reservoir will provide chorine contact time and adequate background chlorination. The intent of the Outlet Piping Control Building is to monitor the chlorine content as the water exits the reservoir and augment the chorine content if needed prior to being released to the City water system. 2.1.8 Control Systems: It is our finding that the existing control systems at the reservoir are outdated and are at the end of their intended service lives. We recommend that the existing control system be modernized to enable remote reservoir monitoring, data acquisition, and control. 2.1.9 Electrical Service: With the proposed control improvements to the Lyman Creek Reservoir it is recommended that a new 400A single phase service be installed. This would provide sufficient power for additional heating, lighting, and pump loads for the reservoir system modifications. 2.1.10 Service Backup Power: It is recommended that a backup generation and an Uninterruptible Power Supply (UPS) system be implemented. This would provide freeze protection for liquid chemical storage and interior water piping, and enable emergency operation of the facility. 6 Executive Summary March 22, 2001 2.1.11 Telemetry: It is recommended that a radio telemetry system be installed at the reservoir Control Building. The telemetry system should provide complete remote monitoring and operation of the facility. Telemetry improvements and operation would improve the operational efficiency of the facility and reduce labor costs. 2.1.12 Lighting/Surge Suppression: Based on the location and history of lightning strikes at the existing control building a complete lightning protection system is recommended. Service equipment surge arrestors and surge suppressors should also be implemented. 2.2 Lyman Creek Reservoir Embankment Stability The following recommendations are for stabilizing the earthen berm on the northwest edge of the reservoir and de-watering the reservoir during repairs. The berm has recently experienced sloughing near the top of the fill surface. 2.2.1 Earthen Berm: The results of the stability analysis indicate that, the embankment exhibits adequate stability under the current phreatic surface conditions. Should the seepage rate increase enough to cause a higher phreatic surface to form, instability could become a concern during a seismic event. Lining of the reservoir would reduce seepage flows and consequently lower the phreatic surface within the embankment. The existing surface slough area should be repaired and minor grading performed to improve drainage along the crest of the existing embankment. The surface slough should be re-graded, seeded and covered with an erosion control mat to facilitate re-vegetation. Leakage tests should be conducted on all pipes that pass through the embankment. 2.2.2 De-Watering With Respect To Reservoir Repairs: The Reservoir should be drained for as long as possible prior to commencing leakage repair work. This will allow time for the mound of groundwater to passively drain back into the Reservoir and potentially eliminate the need for an active de-watering program. While there is no way to accurately determine the amount of time necessary for passive de-watering to completely dry up the Reservoir, it is suggested that a minimum of two months be allowed. If a liner is installed to stop leakage, and if future maintenance requires the Reservoir to be drained, then the presence of groundwater adjacent to the reservoir would cause unbalanced hydrostatic uplift forces that could potentially damage the liner. Placement of an under-drain between the new liner and the existing concrete would allow for the dissipation of hydrostatic forces. 7 Executive Summary March 22, 2001 For long term maintenance programs and monitoring of the reservoir seal, groundwater levels outside of the reservoir should be periodically measured. Particularly, prior to draining the reservoir for maintenance. If the Reservoir is sealed and leakage is stopped, groundwater levels will drop and the mound of groundwater at the Reservoir may completely dissipate. Reduction of leakage from the reservoir by lining or other methods most likely will cause the stream down gradient of the Reservoir to eventually dry up. 2.3 Booster Station This section presents a summary of our recommended Lyman Creek Reservoir and Booster Station operational strategies based on numerous flow scenarios for the current and 20-year planning windows. It also addresses our recommended improvements to the Booster Station. 2.3.1 Lyman Creek Reservoir Operational Strategy: Lyman Creek Reservoir is currently an under utilized water source and storage facility. Lyman Creek is a ground water source and therefore does not require filtration. This makes Lyman Creek water an inexpensive water supply for the City. Traditionally Lyman Creek has only served the North Zone, which has minimal water consumption. The Perkins PRV that connects the North Zone to the Northwest Zone should be calibrated such that it maximizes flow from the North Zone. This will allow for the eventual full utilization of the Lyman Creek resource by the combined consumption of the North and Northwest Zones. The Northwest Zone is currently the fastest growing area in the Bozeman Water System and will, in only a few short years fully utilize the Lyman Creek Water. Utilizing Lyman Creek Water in the Northwest Zone will also forestall the eventual expansion or replacement of the WTP. 2.3.2 Booster Station Operational Strategy: In completing the hydraulic modeling, we evaluated three potential operating strategies for the Booster Station: ✓ Emergency Operation; ✓ Peak Day; and ✓ Fire Flow augmentation. Of the three strategies only fire flow augmentation appeared to have questionable value. Fire flow was modeled for the current and 20-year system. For the current system the Booster Station did not increase fire flow. For the 20-year system, fire flow was increased by approximately 200 GPM. However, under fire flow conditions, the Booster Station did help sustain water levels in the Hilltop Tank. For the peak day and emergency operational strategies the operation of the Booster Station was beneficial. For peak day operation the Booster Station will effectively buffer the Water 8 Executive Summary March 22, 2001 Treatment Plant (WTP) from demand spikes and help maintain tank levels in the South Zone. For emergency operation the Booster Station and Lyman Creek Reservoir could supply 1-2 days of backup storage dependant on water demand. Therefore, we recommend that the Booster Station be used for emergency and peak day operation. Utilizing the Booster Station for emergency and peak day operation may severely tax the storage capacity of Lyman Creek Reservoir. To minimize the potential of completely draining the reservoir during emergency or peak flow conditions, we recommend that telemetry be supplied to the WTP to monitor the water level in the reservoir. 2.3.3 Pressure Reducing Valves: The existing PRV's connecting the South Zone to the North Zones are currently out of calibration based on City records. A detailed evaluation of the PRV's should be completed including vertical elevation survey to establish hydraulic grade line, computer modeling, and field testing to establish optimum settings. Additional modeling and field work should be conducted to determine the optimum setting to maximize the use of Lyman Creek Water and to minimize re-circulation within the system during Booster Station operation. 2.3.4 Booster Station Repairs: It is our understanding that the Booster Station has not been operated since the pump control valves were installed in 1990. One of the pumps has a damaged impeller casing and should be replaced in kind with a new pump. Prior to starting the pumps, all bearings should be thoroughly greased at the pump grease fittings. The pumps must be completely filled with water and purged of any air. The pump should also be turned several revolutions by hand to help fully fill the pump and to check that the bearings are not completely seized. As a component of the Booster Station repair, the operation of the pump control valves installed in 1990 should be closely monitored. The pump control valves were installed in 1990 to minimize water hammer and protect the aging water system directly down stream from the Booster Station. Prior to the installation of the pump control valves several pipe failures occurred during Booster Station operation. It is critical that these valves operate properly to minimize the potential for pipe failure. 2.3.5 Booster Station Automation/Controls: The existing control system at the Booster Station is outdated and of questionable operating condition from lack of use. It is recommended that a new Programmable Logic Control (PLC) based system be implemented for control and monitoring of the booster station. Such a PLC based system will allow on-site and remote operation of the facility. 9 Executive Summary March 22, 2001 2.3.6 Telemetry Options: We recommend the use of radio telemetry. Radio telemetry will have a higher initial installation cost, however it will eliminate the ongoing monthly phone service fees. 2.3.7 Line Voltage Service: We recommend the existing main electrical service be replaced. The existing service is a Federal Pacific Electric 225 amp three phase 600 volt panel. Federal Pacific Electric is no longer in business, and replacement breakers for this equipment can be difficult to locate and expensive. 2.3.8 Service Backup Power: We recommend a 150KW generator set be installed. This would provide sufficient power for starting and running all of the Booster Station pumps, provided that the motors were not started simultaneously. 2.3.9 Lightning/Surge Protection: We recommend a Lightning/Surge Protection system be installed. The probability of a direct lightning strike is low. However, the possibility of voltage surges in the power lines and communication lines resulting from local strikes still exists. For this reason, transient voltage surge suppression should be installed on the incoming power and communication lines. 2.4 Spring Collection Gallery Recommendations To determine the efficiency and reliable yield of the Lyman Creek source area spring boxes, additional flow monitoring is needed. Primarily, the stream flow of Lyman Creek downstream of the spring box collection manhole needs to be monitored. This can be achieved by installing either a manual Parshall flume or automatic gauging station in Lyman Creek. This equipment (flume and flow monitoring equipment) will need to be designed and constructed to work in freezing temperatures if year round monitoring is needed. Due to the frequency of stream flow monitoring,the man hours involved in collecting the data by hand, safety issues, and data integrity, it is recommended that a frost proof stream gauging station with automatic flow monitoring equipment be installed. This structure should be installed immediately downstream of the Spring Box Collection Manhole, 3.0 Engineers Opinion of Cost Table 1 is a summary of the estimated improvement and engineering costs for the recommended improvements to the Reservoir, Booster Station and Spring collection Gallery. 10 Lyman Creek Reservoir Improvement Project Master Engineers Estimate Table 1 Lyman Creek Reservoir Improvements Rehabilitation of Concrete Panels Poly Reservoir Lining/Re-morter/Underdrain $76,000.00 Reservoir Cover Precast Prestress Concrete roof/Ventilation $741,600.00 Reservoir Baffle Reinforced Polypropylene Baffle Walls $57,500.00 Chlorination System/Chemical Feed Building/Outlet Liquid Chlorine Feed System(Inlet Side Injection) $9,700.00 New Chemical Feed building Structure $93,200.00 Interior Piping $16,900.00 Exterior Inlet Yard Piping $15,600.00 Total $125,700.00 $125,700.00 Outlet Pipe Building/Chlorine Injection $114,100.00 Total $249,500.00 Fluoride System Liquid Fluoride Feed System(Inlet Side Injection) $7,800.00 Control/Telemetry/Electrical Systems Control Systems $47,600.00 Telemetry System Telemetry-Radio $7,400.00 Telemetry-Additional Repeater $5,200.00 Total $12,600.00 $12,600.00 Line Voltage Service Upgrade $5,200.00 Service Backup Power $17,300.00 Lightning Surge Protection $6,800.00 Total $89,500.00 Lyman Creek Reservoir Construction Cost $1,221,900.00 Contingency(15%included in above items) $0.00 Engineeering/Construction Administration $237,700.00 Lyman Creek Reservoir Total $1,459,600.00 Master Eng Est summary 3-19-01 Lyman Creek Reservoir Improvement Project Master Engineers Estimate Table 1 �kyan E _o , Lyman Creek Reservoir Embankment Stability Repaired and minor grading $1,500.00 Seeding $100.00 Erosion control mat $2,500.00 Embankment Stability Construction Cost $4,100.00 Contingency(15%included in above items) $0.00 Engineeering/Construction Administration $2,400.00 Embankment Stability Total $6,500.00 Booster Station PRV Callabration/Adjustment $0.00 Control Systems $36,120.00 Telemetry-Radio(Assumes No Repeaters Required) $7,360.00 Pump Replacement $16,000.00 Line Voltage Service Upgrade $5,520.00 Service Backup Power $48,300.00 Lightning Surge Protection $1,040.00 Booster Station Construction Cost $114,340.00 Contingency(15%included in above items) $0.00 Engineeering/(Excludes Construction Administration) $23,700.00 Booster Station Total $138,040.00 Automatic Gauging Station Pipeline, Debris Racks, 8' High Dam, Manhole Construction etc. $23,430.00 Automatic Flow Monitoring Equipment $4,405.00 Guaging Station Construction Cost $27,835.00 Contingency(15%included in above items) $0.00 Engineeering/(Excludes Construction Administration) $9,300,00 Guaging Station Total $37,135.00 Grand Total $1,641,275.00 , 4 f, Master Eng Est summary 3-19-01 Lyman Creek Reservoir Improvements Technical Memorandum No. 1 oil Ali # •.X i .yr 'r M'�t i.:. y Y y rp�;. `�4'+1r Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 August 16, 2000 Prepared By: HKM Engineering Inc. 601 Nikles Drive, Suite 2 • Bozeman,Montana 59715 • 406-586-8834 Lyman Creek Reservoir Improvements Memorandum No. 1 'fable of Contents Task 1 —Review and Compile Background Data 1.1 Introduction .................................................................................................1 1.2 Reservoir History..........................................................................................1 1.3 Cover Removal............................................................................................2 1.4 Reservoir Condition Assessment........................................................................3 1.5 Reservoir Condition Assessment Finding.......................................... ....................4 1.5.1 Structural Assessment............................................................................4 1.5.1.1 Floor Condition.................................................................................4 1.5.1.2 Wall Condition....................................... ..........................................4 1.5.2 Piping Assessment...............................................................................6 1.5.3 Reservoir Leakage...............................................................................7 1.5.4 Chlorination.......................................................................................7 1.5.5 Reservoir Control/Electrical System.........................................................8 1.5.5.1 General History and Condition...............................................................8 1.5.5.2 Water Flow and Level........................................................................12 1.5.5.3 Sample Pumps...... ..........................................................................12 1.5.5.4 Tubidity.........................................................................................13 1.5.5.5 Chlorination...................................................................................13 1.5.5.6 Fluoridation....................................................................................14 1.5.5.7 Alarms..........................................................................................14 1.5.5.8 Power............ ..............................................................................15 1.6 Northside Pump Station Condition Assessment.................................................15 1.6.1 Booster Pump Station Controls................................................................15 1.6.2 Booster Station Electrical and Control System.............................................15 1.6.2.1 General History and Condition.................. ...........................................15 1.6.2.2 Pump Control Panel..........................................................................16 1.6.2.3 Electrical System.............................................................................17 Table of Contents Continued Figures: Figure1.1.......................................................................................................1 Figure1.2.......................................................................................................3 Figure1.3.......................................................................................................5 Figure1.4.......................................................................................................6 Figure1.5.1.....................................................................................................9 Figure1.5.2................................................................................................... 10 Figure1.5.3...................................................................................................11 Lyman Creek Reservoir Improvements Project Technical Memorandum No. 1 August 16, 2000 Task 1 —Review and Compile Background Data 1.1 Introduction On October 6, 1999 the City of Bozeman(City)awarded the Lyman Creek Reservoir Improvements Project to HKM Engineering. The project is for the evaluation of alternatives for improvements to the existing Lyman Creek Reservoir,Northside Pump Station, and the long range planning use of the reservoir and pump station. The primary purpose of this technical memorandum is to document the background information collected during the inspection of the drained reservoir in the fall of 1999. The memorandum also addresses the condition of the existing reservoir control system and Northside Pump Station. This data will be used in development and evaluation of rehabilitation alternatives 1.2 Reservoir History 5 i ;.x,FF♦ - �`T �4� .5.� - .ter........ �� a..-'._ 1 Figure 1.1 --Lyman Creek Reservoir; Existing Cover and Support System Technical Memorandum No. 1 August 16, 2000 Lyman Creek Reservoir was the original water storage basin for the City of Bozeman constructed in the late 1800's. In 1909 and then again in the early 1970's the basin was enlarged to provide additional storage. The basin as it exists at the time of the visual examination is a below grade trapezoidal shaped section consisting of concrete slabs cast against earth. The flat bottom of the basin is about 54 feet x 73 feet. The side walls slope at about 1.5 : 1 (H : V) extending vertically about 28 feet to the intersection with a vertical wall that extends another 4 feet. The total depth of the basin is 32 feet. The dimensions of the top of the basin are 241 feet x 157 feet. The basin will hold approximately 5.4 million gallons to the top of the concrete. Review of the records revealed that the flat bottom and sloping sides were part of the original construction. The vertical side walls were added in the early 1970's. In 1989 because of more stringent drinking water standards a high-density Polyethene (HDPE) cover was installed over the reservoir. The cover was designed to float on the reservoir and was supported by a cable and pulley system around the perimeter to allow for water level fluctuation. The cover was also equipped with a baffle that ran east-west up the center of the basin. The baffle was supported from the cover and weighted to the bottom intending to minimize the short-circuit flow of water between the inlet and outlet pipes of the basin. According to City Staff the HDPE cover required considerable maintenance (hole and baffle repair), and the periodic pumping of water from its surface. In the fall of 1998 the HDPE cover had deteriorated to such a degree that it could longer be maintained. At that time the City took the reservoir off line from the City water system, but continued to route chlorinated water through the basin at approximately 500 gpm. 1.3 Cover Removal The first step in the visual examination of the reservoir was removal of the cover. The existing HDPE floating cover(see Figure 1.1 above) was anchored in place by a cable system connected to support posts around the perimeter of the basin. The center baffle was anchored by weights to the bottom of the reservoir and the cover was equipped with two (2) floating hatches for access. The first step in cover removal was to cut the cover free from its anchors around the perimeter and along the bottom of the baffle and to cut the liner into four(4) manageable pieces that could be removed. This task was completed by divers from Liquid Engineers, Inc., of Billings, Montana. The divers were on site October 22 through 25, 1999 to complete this task(see Appendix A for Divers Notes). Page 2 Technical Memorandum No. 1 August 16, 2000 E Figure 1.2-- Lyman Creek Reservoir; Divers Cutting Cover Anchors The next step was to remove the fence along the south side of the reservoir to facilitate the removal of the liner pieces. Grizzly Fencing completed this work on October 25, 1999. Following the fence removal CK May Construction of Bozeman removed the 4 cover pieces from the reservoir. This was accomplished by connecting the perimeter anchor cables to railroad rails and then slowly pulling out the sections with a small bulldozer and a four-wheel drive backhoe. By October 27, 1999 the cover, baffle and hatches were removed from the reservoir. By November 18, 1999 the cover and baffle materials were hauled to Bozeman Landfill by CK May, and the chain link fence along the south side of the reservoir was replaced by Grizzly Fencing. 1.4 Reservoir Condition Assessment Subsequent to the removal of the reservoir cover, the City drained the reservoir. On November 3, 1999 with the reservoir drained F KM personnel were able to visually examine, physically inspect, and survey the reservoir basin. Gary Simonich, P.E. and Clint Litle, P.E. conducted the Structural inspection of the reservoir. The structural inspection consisted of a visual inspection of the reservoir floors and walls to verify the condition of the concrete. The inspection checked for delamination of the surface, noted any cracking that occurred, and checked for any indication of reactive aggregate in the concrete. The concrete floor and lower wall panels were sounded with weights and hammers to check for any voids under the slab. Concurrent with the structural inspection the reservoir basin was surveyed using a Topcon Total Station and mapped with AutoCAD Version 14 software. The reservoir's Page 3 Technical Memorandum No. 1 August 16, 2000 physical dimensions were surveyed, piping locations verified and defective areas identified (see Appendix `S" for mapping). In conjunction with the structural inspection and the survey, the drained reservoir basin was still photographed and video taped. Noted defects were labeled, photographed, and surveyed. Appendices `S" and "C" contain the mapping and reservoir photographs. Videotape of the drained basin is also included as a part of this submittal. 1.5 Reservoir Condition Assessment Finding 1.5.1 Structural Assessment The structural condition of the concrete reservoir basin was generally found to be in fair to good condition for the age of the facility. 1.5.1.1 Floor Condition The reservoir floor was visually inspected and sounded for voids and delamination. The floor was found to be in good condition. No voids were identified. The surface appearance of the floor was smooth and virtually free of cracks or defects. The panel joints were well sealed and appeared to be intact with exception of the interface with the sloping wall sections. The floor to sloping wall joints were in poor condition with water leaking (squirting) into the reservoir(see video tape). 1.5.1.2 Wall Condition The reservoir walls consist of two separate wall sections. The lower section, which is the original basin, begins at the floor and slopes up at a 1.5:1 grade to a height of 28 feet. The upper wall section, which was added to the reservoir approximately 30 years ago, extends the wall vertically an additional 4 feet for a total basin depth of approximately 32 feet (see appendix B for reservoir survey). The condition of the wall panels varied with depth within the reservoir. Panels that have historically been submerged were generally in satisfactory condition with minimum cracking and surface distress. However,the panels on the sloping wall section that have been exposed to freeze thaw action and ice were cracked essentially around the entire perimeter of the reservoir. Appendices B and C contain photographs and mapping of the cracks and crack locations. Page 4 Technical Memorandum No. 1 August 16, 2000 Typical Lower Panel Crack Typical Lower Panel r Joint : Figure 1.3 -- Lyman Creek Reservoir; Lower Wall Panel Cracks and Joints The joint condition of the lower wall panels was found to be poor. At numerous locations water was observed leaking (squirting) into reservoir. The leaks were found to be under higher pressure with depth in the basin. The leaks also appeared to diminish with time, indicating the ground water pressure was diminishing the longer the basin remained empty. Some of the higher joints and cracks were flowing a steady stream of water when first observed and either stopped altogether or become small seeps by the time the inspection was completed. Evidence of previous attempts to patch the joints and cracks were observed. Both flexible sealant and rigid grout materials were found. Many of the joints and cracks were leaking around the patching material or the material has spalled from the joints. The condition of the upper wall section was considerably better than the condition of the lower sloping sections. As mentioned above the upper wall section was added to the reservoir approximately 30 years ago. The panels were in good shape, generally free of cracks and defects. The upper wall panel joints were also in generally good condition with the exception of a few joints where spalling around the joint was observed. PVC water stop material was found in the vertical joints. Page 5 Technical Memorandum No. 1 August 16, 2000 — T �__.� POT , Upper Wall ` Panel Joint ' A 1 ! ♦ I I Figure 1.4 -- Lyman Creek Reservoir; Upper Wall Panel Joints Similar to the floor panels the wall panels were sounded for voids and delamination. Only one problem area was found directly around the 10" outlet at the West end of the reservoir. In sounding the concrete, it appeared that a void may be present beneath the concrete around the outlet pipe. Due to the limited area of the void it was decided not to explore the void because further work would have resulted in keeping the basin drained for a longer period of time. With cold weather approaching the basin needed to be filled with water for protection. The void area will be addressed in the repairs proposed for the basin and pipes. 1.5.2 Piping Assessment The inlet and outlet pipes exposed within reservoir were generally found to be in reasonably good condition. The 12"PVC inlet pipe appeared to be in good condition. The pipe barrel,joints and anchors all appeared sound and in good operating condition. The outlet pipes also appeared to be in good condition with exception of the 10" drainpipe. The 10" drainpipe appears to be from the original construction around the turn of the century. As mentioned previously a void may have developed behind the wall Page 6 Technical Memorandum No. 1 August 16, 2000 panel at the drainpipe penetration. In addition, the pipe is heavily rusted and is generally in poor condition. 1.5.3 Reservoir leakage City of Bozeman Water Department staff has recently been conducting reservoir leakage testing. It is our understanding that City Staff estimates leakage from the reservoir to be in the range of 250 to 350 GPM. In evaluating the City's leakage tests in conjunction with our reservoir inspection it is our opinion that the leakage is primary due to panel cracking and poor joint condition. It is our opinion that while the reservoir is full, water pressure is forcing water out of the reservoir through the cracks and joints. Once water passes through the cracks and joints it flows into the surrounding ground. The ground/formations surrounding the reservoir consist of alluvial stream-laid deposits, which are a mixture of clay, silt, sand and gravel_ These units are able to absorb, store, and transport water quiet readily. Over the years, leakage from the reservoir has saturated a portion of the ground surrounding the reservoir (both vertically and horizontally), and created an artificial mound of groundwater in the immediate area of the reservoir. This mound of groundwater was evident when the reservoir was drained. While inspecting the drained reservoir HKM observed substantial water leaking back into the basin (see videotape) at the cracks and joints. The leaks were under pressure as demonstrated by the wall/floor joint where the water was squirting back into reservoir at a height of 6— 8 inches. At that time, (when the reservoir was drained) the pressure gradient was reversed and water residing in the groundwater mound began to flow back through the panel joints and cracks. This theory is further supported by the seeps at the toe of the embankment on the west side of the reservoir where the water is day-lighting to the atmosphere. 1.5.4 Chlorination A gas chlorination system is utilized to provide disinfection in the system. The chlorine storage building sets just to the east of the control building and houses one 1-ton cylinder and one 150 pound cylinder. The 150 pound cylinder functions as backup feed system when the ton cylinder empties or is being changed. A vacuum feed system manufactured by Capital Controls is used in the system. The chlorine gas is drawn from the cylinders and is pulled through a chlorine feed control valve located in the control room. From the control valve the gas is pulled back into the storage room, where the gas is mixed with water at an ejector. From the ejector the chlorine solution flows to the valve vault where it is injected into the water supply line. The chlorination system appears to be in good shape. Page 7 Technical Memorandum No. 1 August 16, 2000 1.5.5 Reservoir Control/Electrical System 1.5.5.1 General History and Condition The Lyman Creek Reservoir is fed from two spring sources located approximately 564 feet above the reservoir. Water from the spring sources flows through approximately 7700 feet of 16-inch ductile iron pipe and 2,400 feet of 18-inch asbestos-cement pipe to the reservoir. Two pressure reducing valve stations are located along the supply line to regulate the pressure in the line. Each pressure reducing stations consists of 2 regulating valves that reduce an upstream pressure of 100-140 psi to 30-40 psi. The regulating stations reduce the flow capacity of the supply line to approximately 2.7 to 3.8 MGD which matches the estimated yield of the springs. Flow into the reservoir is controlled by a valve designated CV in Figure 1.5.1. The valve is manually set, via a switch in the control room, to establish a flow rate into the reservoir. Valve CV1 is not modulated based on the flow. A separate electric operated butterfly valve (EOV 1) located on the reservoir inlet line will close on either a high inlet turbidity reading or a low chlorine reading. With the current manual setting of the inlet flow, the reservoir level will fluctuate based on the difference in the inlet flow setting and the outlet demand. If the inlet flow is set too high, water will be wasted in the high water overflow. A pressure transducer located on the reservoir outlet line is used to monitor the reservoir level but the level is not used to control any of the inlet or outlet valves. Refer to Figures 1.5.1, 1.5.2, and 1.5.3 for an inventory and location of existing electrical control devices. The existing measurement and control equipment was installed circa 1990. Except for the following noted changes,this equipment is as originally installed. A malfunctioning Capitol Controls residual analyzer was replaced approximately 7 years ago. A new flow meter was installed circa 1998 and a new panel meter indicating flow was installed in the main reservoir control panel soon thereafter. Reservoir control is accomplished by processing signals from the discrete instruments at the reservoir as described in the additional sections below. Control and alarm indication is directed from the main reservoir control panel via a combination of manual switches on the panel face and numerous mechanical relays located inside the control panel. The lack of documentation for the internal relay logic presents a challenge for troubleshooting and repair of the existing system. The internal wiring inside the control panel is damaged due to an apparent electrical short. The localized nature of the damage suggests either a short in a relay coil or a possible loose termination. 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Gl-126.DWG Technical Memorandum No. 1 August 16, 2000 The chart recorders on the reservoir control panel exhibit occasional erratic graphical output and cause intermittent control problems. The turbidity recorder will occasionally (randomly) drift off scale regardless of actual turbidity condition. Switching the inlet chlorine residual chart recorder on and off will occasionally cause the solenoid valve for the main chlorine gas feed to shut down. Because of age of the existing system components, it can be difficult to locate replacement parts. This in turn makes it difficult for Water Department staff to maintain and repair existing equipment. 1.5.5.2 Water Flow and Level The rate of flow of water into the reservoir is measured via a flow meter located in the valve vault located outside the control room. The rate of flow is displayed on an LED panel meter located in the main reservoir control panel. Additionally, the inlet flow is recorded on a 7-day chart recorder located in the control panel. Flow rate into the reservoir is adjusted manually from the control panel via a switch that opens and closes the Clayton valve located in the valve vault. Currently, there is no automatic control of water flow rate. Also, there is no means of measuring water flow out of the reservoir. An electric butterfly valve (see Piping Sketch Figure 1.5.1) controls water inlet to the reservoir. The valve operation is controlled either automatically or manually via two switches on the reservoir control panel. In 'AUTO' mode, the valve is normally open,but will be automatically closed in the event of high turbidity or low inlet chlorine residual. In 'HAND' mode,the valve can be overridden to either the open or closed position regardless of the chlorine or turbidity status. Lights on the reservoir control panel provide visual indication as to whether the valve is open or closed. Water level is measured via a pressure sensor located at the reservoir outlet. An LED panel meter located in the main reservoir control panel displays the current reservoir water level. Additionally, there are two alarms lights on the control panel indicating low and high reservoir water level. 1.5.5.3 Sample Pumps There are two sample pumps which provide water to the control building for measurement of chlorine residual and turbidity. Two pressure sensors in the control building, one on the inlet sample water line and one on the outlet sample water line, verify the presence of sample water. If sample water is not present, a visual alarm indication is provided via a light on the reservoir control panel. The sample pumps are controlled manually via ON/OFF switches on the reservoir control panel, and visual indication of their operation is provided via lights on the control panel. Page 12 Technical Memorandum No. 1 August 16, 2000 Additionally, a water level sensor is located in the same concrete basin as the inlet sample pump. The control system will shut down the inlet sample pump if water is not present in the basin. 1.5.5.4 Turbidity Inlet turbidity is measured at the control building via a Hach#1720C Turbidimeter. A visual indication of the current inlet turbidity is provided at the turbidimeter via an LED display. Additionally, inlet turbidity is recorded on a 7- day chart recorder located in the reservoir control panel. Visual indication of a high turbidity alarm is provide via a light on the control panel. 1.5.5.5 Chlorination Reservoir water is chlorinated via a Capitol Controls gas chlorinator located in the reservoir control building. Chlorine gas is piped to the control building from the adjacent chlorine storage building. An electric solenoid valve controls the chlorine feed to the chlorinator. Additionally, a pressure switch on the chlorinator is used to detect the presence of chlorine gas. Out of chlorine gas alarm is indicated visually by a light in the control panel The chlorinator is designed to automatically adjust chlorine feed rate to maintain the desired residual level. However, according to Water Department personnel, this automatic feature does not function reliably and is currently adjusted manually. The chlorine gas is stored in one 2000 lb tank and one backup 150 lb tank located in the adjacent building. The amount of gas remaining in the tanks is determined by tank weight (hydraulic load cells) and is indicated by mechanical gauges located at the tanks in the chlorine storage building. The chlorine residual is measured at both the reservoir inlet and reservoir outlet via two Capitol Controls series 1870 Residual Analyzers. Visual indication of the current residual levels is provided at the analyzers via LCD displays. Additionally, both inlet and outlet residual are recorded on 7-day chart recorders located in the reservoir control panel. Visual indication of a low inlet or outlet residual alarm condition is provided via lights on the control panel. Chlorine leak detection is provided via a gas sensor located in the chlorine storage building which is connected to the Capitol Controls 1610 Gas Detector located in the control building. The system often reports false alarms resulting from internal combustion engine exhaust from passing traffic. (This particular model reports 16 ppm chlorine gas for every 10 ppm nitrous dioxide in combustion gases). There is no chlorine leak detection at the control building, although the hazard of a chlorine gas leak does exist. Page 13 Technical Memorandum No. 1 August 16, 2000 1.5.5.6 Fluoridation Fluoride is injected into the water system in the concrete basin where the sample pump is located. The fluoride and water are not sufficiently mixed for an accurate measurement of fluoride concentration. Consequently, fluoridation is measured manually by Water Department staff by sampling water at the reservoir outlet. The existing fluoridation system is partially automated by a pre-manufactured standalone controller, Acrison Model#050-3. Raw water and solid chemical are fed into a mixing tank and subsequently pumped to a concrete basin which is piped to the reservoir. The chemical is fed from a hopper located in a shed outside the control building. In the automatic mode, the mixer and pump to reservoir run constantly. The mixing tank has a high/low water level sensor. At low level, a solenoid valve is opened allowing raw water to fill the mixing tank At the same time, the feeder motor is switched on allowing chemical to feed into the mixing tank. The water and feeder are shut off when the high water level sensor is activated. The feed rate is manually adjustable, however there is no metering to provide an indication of how much fluoride is being added to the water supply. Currently, Water Department staff manually measure fluoridation level at the reservoir outlet and adjust the feed rate accordingly until the appropriate level is attained. This process takes approximately 3-4 days and must be repeated if the rate of water flow into the reservoir changes. 1.5.5.7 Alarms In addition to the indicator lights on the control panel discussed above, a small speaker at the control panel provides audible alarm indication. An adjacent button on the panel is used to silence the alarm speaker. A Radionics alarm panel in the reservoir control building provides remote reporting of alarm conditions over a telephone line. The panel is monitored by a private company in Minnesota, who in turn contacts Bozeman Water Department staff to inform them of the alarm condition. The following conditions are remotely reported: AC fail (loss of power) Chlorine gas leak The following are reported as a common general alarm signal Low inlet chlorine residual High turbidity No sample water(either inlet or outlet) Page 14 Technical Memorandum No. 1 August 16, 2000 1.5.5.8 Power The control building is currently served by a 240/120 volt single phase service. A 100 amp 24 circuit Siemens panel provides power for heat, lighting, and electrical control systems. Power outages require lengthy manual intervention on the part of Water Department Staff to restore proper chlorine level in the reservoir. The electrical system in the control building has in the past sustained damage from a lightning strike. There is no emergency power backup or lightning protection for the existing electrical service. 1.6 Northside Pump Station condition Assessment 1.6.1 Booster Pump Station Controls The booster pump station contains two pumps that are in operating condition. A third pump has been taken out of service. The pump station has not been used 1986. The current pumps Fairbanks-Morris split case model 5813 pumps. One pump is a 6-inch with a rated capacity of 800 gpm at 134 feet head and the second pump is a 4-inch with a rated capacity of 300 gpm at 134 feet head. In order to reduce start-up and shut-down surges, the pumps have controlled valve opening and closing on the pump discharge. The valve on each pump discharge line has a delayed opening on pump start-up and will close prior to pump shut down. As indicated in section 1.6.2 below,the pumps have a Hand- Off-Auto switch associated with each pump but it is not known what controlled the pump operation in the Auto mode. 1.6.2 Booster Station Electrical and Control System 1.6.2.1 General History and Condition The booster station is currently not in active use. The system was last tested approximately 7 years ago. During this test,the pumps were operated in manual mode. As this system is not in operation, Water Department staff are not sure how the system is supposed to function in automatic mode, or if the automatic mode even functions properly. The pump control panel was manufactured by Autocon System Controls. The internal electronics consist of discrete relays, vacuum tubes, and mercury switches. Timing and sequencing is accomplished by a linear array of mercury switches which ride on cams attached to a motorized shaft. Essentially all components are obsolete. Page 15 Technical Memorandum No. 1 August 16, 2000 Additionally, internal to the panel is a component identified as an 'Autocon Telecator Receiver'. This is most likely the means by which the control panel received status information from the reservoir. There is visual indication of system status on the pump control panel via gauges and indicator lights. There is no remote reporting of system status or data acquisition devices. 1.6.2.2 Pump Control Panel Meters and gauges There are two mechanical pressure gauges: one for Suction pressure and one for Discharge pressure. These gauges are piped to the water system and read pressure directly. These gauges appear to be working properly. Additionally, there is one mechanical meter displaying Lyman reservoir level. It is unknown how this meter originally received input from the reservoir, and currently it does not function properly. Alarms Alarm conditions are reported locally on the control panel via red indicator lights and consist of the following: - Low Suction Cutout - Lyman Reservoir Low Level - Transmission Line Failure - Common Pump Failure Pump Control Associated with each of the pumps there are two indicator lights, a Hand/OfFAuto switch, and reset button. One light indicates whether the pump is Required, and the other indicates whether the pump is Running. In the 'Hand' position, the pump is activated, and a time delay is initiated by an external timing relay to allow discharge pressure to build. After approximately five seconds, the valve on the discharge side of the pump opens allowing water to flow. When turned off, reverse pressure is applied to the valve, and a limit switch attached to the valve turns the pump off when the valve closes. Page 16 Technical Memorandum No. 1 August 16, 2000 It is not known exactly how the pumps function in the automatic mode. Most likely, pump action is initiated based upon discharge pressure via the mercury switch/cam shaft mechanism noted above. Bypass Valve Associated with the bypass valve are two lights showing valve status labeled 'Open' and 'Closed'. Additionally, there is a Hand/Off/Auto switch to change from manual to automatic control. In 'Hand' position, the valve may be opened or closed via push buttons on the control panel. It is not known how the valve is controlled in the automatic mode. 1.6.2.3 Electrical System The booster station main electrical panel is a Federal Pacific 480 volt 3 phase panel with 225A main breaker. This panel provides power for the booster station pumps. Additionally, the panel feeds a 480/240-240/120, 10 Kva transformer which provides power for lighting, control, and receptacle loads. Page 17 Lyman Creek I TechnicalImprovements Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 February 9, 2001 Prepared By: HKM Engineering Inc. 601 Nildes Drive, Suite 2 - Bozeman,Montana 59715 • 406-586-8834 Lyman Creek Reservoir Improvements Memorandum No. 2 Table of Contents Task 2—Reservoir Rehabilitation Alternatives 1.1 Introduction .............................................................. 1 1.2 Rehabilitation of Concrete Panels......................................................................1 1.2.1 Option I—Crack and Joint Sealing................................................... .........2 1.2.2 Option H—HDPE or Polypropylene Reservoir Lining.....................................3 1.2.3 Option Ell—Concrete Lining............... ...................................................4 1.3 Reservoir Cover..........................................................................................5 1.3.1 Option I—Pre-cast Pre-Stressed Concrete Roof..............................................7 1.3.2 Option H—Steel Joist and Girder System... ..............................................10 1.3.3 Option Ell—Three Layer HDPE Floating Cover..........................................11 1.3.4 Option IV—One Layer Hypalon Floating Cover..........................................13 1.3.5 Option V—Fiberglass Cover.................................................................13 1.3.6 Humidity and Radon Control within Reservoir enclosure..................... ..........14 1.4 Reservoir Water Circulation...........................................................................15 1.4.1 Option IA& IB-Baffling system for use with a structural reservoir cover............15 1.4.2 Option 11 Piping diffuser system for use with a structural reservoir cover............16 1.4.3 Option III Baffling system for use with a floating reservoir cover.....................20 1.4.4 Option IV Piping diffuser system for use with a floating reservoir cover.............20 1.5 Chlorination System....................................................................................21 1.5.1 Chlorine Gas Safety...........................................................................21 1.5.2 Chlorine Scrubbers.............................................................................22 1.5.3 Chlorine Cylinder Containment Vessels.....................................................22 1.5.4 Chlorination Process...........................................................................23 1.5.5 Liquid Chlorine Feed System................................................................24 1.6 Fluoridation System....................................................................................26 1.7 Building Modifications.................................................................................27 1.8 Outlet Piping Control Building/Vault............................................. .................27 1.9 Reservoir Electrical Control System..................................................................31 1.9.1 Control System Option I.........................................................................31 1.9.2 Control System Option 11.........................................................................32 Table of Contents Continued 1.9.3 Control System Option III................................................................. .....35 1.9.4 Telemetry Options......................................... ...... ..............................36 1.9.5 Reservoir Electrical System..................................................................36 2.0 Recommendations....................................................................................38 Tables: Table 1.8.1 Summary of Recommended Improvements Cost..........................................42 Figures: Figure1.2.......................................................................................................2 Figure1.2.1............................................................................ ........................6 Figure1.3........................ ...............................................................................7 Figure1.3.1.....................................................................................................9 Figure1.3.2...................................................................................................12 Figure1.4.1...................................................................................................17 Figure1.4.2...................................................................................................18 Figure1.4.3...................................................................................................19 Figure1.7.1..................................................................... .................. ...........28 Figure1.7.2...................................................................................................29 Figure1.7.3...................................................................................................30 Lyman Creek Reservoir Improvements Project Technical Memorandum No. 2 February 9, 2001 (Revision of October 6,2000) Task 2 —Reservoir Rehabilitation Alternatives 1.1 Introduction In the fall of 1999 the City of Bozeman (City) awarded the Lyman Creek Reservoir Improvements Project to HIM Engineering. The project is for the evaluation of alternatives for improvements to the existing Lyman Creek Reservoir, Northside Pump Station, and the long range planning use of the reservoir and pump station. The scope of the project broke the plan into a series of technical memorandums evaluating separate aspects of the project. This technical memorandum (No. 2) will specifically evaluate the following items: Rehabilitation of Concrete Panels — Methods of repairing and sealing the existing concrete panels. • Reservoir Cover—Roof and cover options for covering the reservoir. • Reservoir Baffle — Options for installation of a baffle system to minimize short circuit flow through the basin. • Chlorination/Fluoridation — Recommendation of chlorination and fluoridation system improvements. • Automation/Controls—Options for control system improvements. 1.2 Rehabilitation of Concrete Panels HKM personnel inspected the concrete panels and panel joints of the reservoir on November 3, 1999 (see memorandum No. 1 for detail). The panel and joint condition of the reservoir varied with depth within the reservoir. Panels that have historically been submerged were generally in satisfactory condition with minimum cracking and surface distress. However, the panels on the sloping wall section that have been exposed to freeze thaw action and ice were cracked essentially around the entire perimeter of the reservoir. Based on leakage tests performed by City Staff, the reservoir is leaking in the range of 250 to 350 GPM. Preliminary groundwater monitoring indicates this leakage can be directly attributed to the panel cracking and poor joint condition. The ground formations surrounding the reservoir consist of alluvial stream-laid deposits, which are a mixture of clay, silt, sand, and gravel. These units are able to absorb, store, and transport water quite readily. Over the years, leakage from the reservoir has saturated a portion of the ground surrounding the reservoir (both vertically and Technical Memorandum No. 2 February 9, 2001 horizontally), and created an artificial mound of groundwater in the immediate area of the reservoir. 9K ' • 4 Figure 1.2—Typical Upper Sidewall Panel Cracking and Joint Condition Figure 1.2 shows the condition of a typical wall panel on the upper portion of the sloped sidewall of the reservoir. To repair the panels and joints essentially three options have been evaluated: • Option I— Crack and Joint Sealing • Option 1I—FIDPE or Polypropylene Reservoir Lining • Option III—Concrete Liner A fourth option was also initially considered for the spray on application of a sealant material. A 125-mil coat of Polycoat sealant was evaluated and eliminated because of cost. Based on supplier and contractor information it was estimated that a polycoat liner would cost approximately $8 per square foot or $430,000 with contingency to line the reservoir. This is approximately 5 — 9 times greater than the other options and was therefore disregarded as a valid option. 1.2.1 Option I—Crack and Joint Sealing This option involves repairing the panel cracks and joints by working a repair mortar into the voids and then applying a strip seal over the repaired joint (polyurethane elastomeric sealant) to seal the joint. 2 Technical Memorandum No. 2 February 9, 2001 Process: The reservoir will be drained and cleaned of sediment and algae. All existing loose mortar and joint material will be removed. The cracks and joints will then be routed, pressure washed, and thoroughly cleaned. The cracks will then be filled and pre-levied with a repair mortar. A polyurethane elastomeric strip seal with hypalon backing will then be placed over the joint. Through this process the reservoir should be allowed to completely drain and dry to reduce back- flow or back-pressure against the repair mortar caused by the mounded water table beneath the reservoir. All mortar and patch materials should meet NSF/ANSI potable water standards. Advantages: • The advantage of this option is primarily in ease of installation and low up-front cost. As discussed above, the process is relatively simple, which reduces up-front labor and material costs. The estimated installation and life cycle costs are given in appendix A. All life cycle cost calculations are based on a useable life of 50 years. Disadvantages: • The disadvantage of the crack and joint sealing option is the long-term serviceability and maintenance requirements. As evident from the existing crack and joint mortar condition, mortars and sealants have a limited service life in submerged environments. During the inspection of the drained reservoir, (November 1999)joint and crack grout conditions were noted from previous attempts to seal the reservoir. In the majority of the wall locations where cracks or joints had been resealed the repair mortar had failed and groundwater was flowing back into the reservoir. • Inspection Program: This option will require a long-term inspection and maintenance and repair program. • Short Service Life: Mortar and sealant suppliers were contacted regarding service life of grouted joints. The suppliers claimed that the grout should match the life of the concrete. However, based on the performance of the earlier joint repair attempts, we estimate a more reasonable service life of 10 to 15 years prior to replacement. 1.2.2 Option II—HDPE or Polypropylene Reservoir Lining This option involves sealing the reservoir basin by installing a HDPE or Polypropylene liner system. Process: The reservoir will be drained and cleaned of sediment and algae. All existing loose grout and joint material will be removed. The cracks and joints will then be routed, pressure washed, and 3 Technical Memorandum No. 2 February 9, 2001 thoroughly cleaned in preparation for repair mortar installation. Through this process the reservoir should be allowed to completely drain and dry to reduce back-pressure against the mortar. The purpose of the mortar installation for this option is not to seal the reservoir but to fill voids and provide a smooth surface for liner installation. After the joints and cracks have been mortared an under drain system should be installed on the floor and partially up the sidewalls of the reservoir to allow for positive drainage of groundwater and to minimize the potential for "floating" the liner when the reservoir is drained (See Figure 1.2.1). The under-drain system should consist of a perforated drainpipe bedded in 3/8" minus gravel around the perimeter of the floor slab. This should be overlain with a 6 oz Geonet fabric over the entire floor slab and projecting several feet up the sidewall. The Geonet fabric will convey water away from the sidewalls and floor to the perforated perimeter drain. After the Geonet fabric has been placed a layer of 16 oz nonwoven cushion fabric should be installed on the sidewalls and just overlap the Geonet. The cushion fabric and Geonet will "cushion" or protect the liner from puncture. As an option the Geonet fabric could be placed the entire wall height if groundwater seepage is a concern for the full height of the wall. However, the use of Geonet Fabric must be weighed against cost benefit for Geonet Fabric cost 2.5 times more than a 16oz nonwoven cushion fabric (0.15/sf vs. 0.55/sf). The existing concrete panels have a rough / abrasive surface that could potentially puncture the liner compromising the liner seal. Following the installation of Geonet and cushion material a 45 mil polypropylene liner will be installed. Advantages: • The advantage of this option is that a liner will provide a long-term, low maintenance repair to the reservoir basin. • The liner will provide a positive seal effectively eliminating leakage from the reservoir and will also eliminate the potential for cross contamination of groundwater into the reservoir. Disadvantages: • The disadvantage of this option is primarily up-front cost. This option is estimated to cost approximately 50% more than Option I at the time of construction. However, this up-front cost is partially offset by reduced life cycle maintenance costs when compared to a sealant repair. 1.2.3 Option III—Concrete Lining This option involves overlying the existing concrete sloping sidewall slabs with a new concrete overlay. The existing slab would be left in place to act as a sub base for the new slab. Any "soft" spots would have to be stabilized before the new topping slab is placed. 4 Technical Memorandum No. 2 February 9, 2001 Process: The reservoir will be drained and cleaned of sediment and algae. All existing loose mortar and joint material will be removed. Any void areas under the existing slab should be grouted and stabilized before the new slab is placed. The jointing layout for the new slab will be designed to reduce cracking in the slab. The slab will also be reinforced with temperature and shrinkage reinforcement to minimize cracking in the new overlay slab. In conjunction with this option, an inspection program should be employed which drains and exposes the liner for inspection on a regular periodic basis. This schedule should be on a short time frame at the completion of the overlay. If there are no cracks developing that require maintenance,the inspection period can be extended to a longer interval. Advantages: • The advantage of this option is that the existing basin slab will provide the subgrade support for the new overlay slab. The basin slope is already established and the new overlay will act as a membrane to seal existing cracks that are leaking. With a good supporting base under the slab this option will be relatively maintenance free. Disadvantages: • The disadvantage of this option is the potential to develop new cracks over old cracks in the existing slab if the sub base is not stabilized before the overlay is placed. If new cracks do form, they will become a continual maintenance problem. 1.3 Reservoir Cover From 1989 to the fall of 1999 Lyman Creek Reservoir was covered by a floating high-density polyethene (HDPE) cover. The cover was designed to float on the reservoir and was supported by a cable and pulley system around the perimeter to allow for water level fluctuation (see figure 1.3). According to City Staff, the HDPE cover required considerable maintenance (hole and baffle repair), and the periodic pumping of water from its surface. In the fall of 1998 the HDPE cover had deteriorated to such a degree that it could no longer be maintained. At that time the City took the reservoir off line from the City water system. In the fall of 1999 the cover was removed to facilitate the inspection and restoration of the reservoir. 5 LINER NON-WOVEN CUSHION ON SIDEWALL ONLY 4"0 PERFORATED LINER DRAIN PIPE 3/8" MINUS BEDDING GEONET "'--------------------------- LYMAN CREEK RESERVOIR FIGURE 40.2.1 BOZEMAN, MONTANA RESERVOIR UNDER DRAIN LINER DETAIL E N G I N L•E R I N G . 4M229.135 I SEPT. 2000 Copyright 0 2000 HKM ENGINEERING , Inc., All Rights Reserved. LINER_DET.DWG Technical Memorandum No. 2 February 9, 2001 IN ..L_ - pi f _ i lid" :•Y....�:. .►. J Figure 1.3 — Lyman Creek Reservoir; Existing Cover and Support System To replace the reservoir cover five options have been evaluated: • Option I -- Pre-Cast Pre-Stressed Concrete Roof • Option H -- Steel Joist and Girder system • Option III— Three Layer HDPE Floating Cover • Option IV— One Layer Hypalon Floating Cover • Option V— Fiberglass Cover 1.3.1 Option I—Pre-Cast Pre-Stressed Concrete Roof This option involves covering the reservoir with concrete precast twin tee roof panels. The twin tee panels will span from new support walls at the perimeter of the reservoir to new precast beams supported along new column lines within the interior of the reservoir (refer to figure 1.3.1). The twin tees will be sloped to provide for roof drainage to the sides of the reservoir. New precast columns supported on footings poured onto the existing floor will support the precast beams at the interior of the reservoir. The twin tees will be covered with a membrane roof to prevent rain and snow from leaking into the treated water. In anticipation of the proposed EPA Radon rule, the inlet and reservoir water was tested for radon (see test results in appendix Q. The proposed radon regulation establishes the maximum level of radon allowable in community water supplies at 300 picoCuries per liter(pCi/L). The inlet 7 Technical Memorandum No. 2 February 9, 2001 water was found to contain 426 picoCuries per liter (pCi/L) and the reservoir water contained 171 pCi/L. The reduced radon content in the reservoir is due to the radon dissipating and venting to the atmosphere. According to the EPA, aeration is the best available technology for removing Radon in drinking water. This, in effect, is what is occurring with the existing open to atmosphere reservoir. A ventilation system will be required to exhaust air within the structure and prevent radon gas from concentrating in the building. Ventilation will be provided by a motorized exhaust system,which is further discussed in Section 1.3.6 of this memorandum. Maintenance of the pre-cast roof system will require periodic inspections and grout patching. To complete this maintenance work, a pontoon or platform boat will be required within the reservoir. This boat will be used to float around the reservoir beneath the cover to inspect the concrete for defects and deterioration. The boat will also act as a work platform for grout repair. A long-term or complete resurfacing of the pre-cast roof system is not anticipated for the 50-year service of the system. To provide access to the structure for maintenance requirements multiple access doors will be provided on the gable ends of the roof system. Both double and overhead doors should be provided to accommodate a variety of maintenance equipment sizes. Advantages: • The overall maintenance requirements of a concrete roof system will be minimal, essentially limited to roof membrane patching and periodic replacement. This will significantly reduce maintenance costs over the life of the roof. • The serviceability of concrete is excellent in high humidity conditions providing a good match of materials to conditions. Similar to traditional water storage tanks, concrete is the material of choice because of its durability and low maintenance requirements. • A precast concrete roof system should be relatively quick to build since precast members are ready for placement immediately upon arrival to the job site. • The open to atmosphere design will facilitate aeration and venting of the radon gas. Disadvantages: • High initial cost. A precast concrete roof system has the second highest initial construction cost of all the options (only fiberglass is higher). However, this is offset by the reduced maintenance costs through the life of the roof. • A concrete roof system has high dead loads that are of concern in a high seismic zone. This is overcome by a heavier column support system within the reservoir. • A concrete roof system would be visible from the valley, unlike a floating cover system. The roof system would be designed as a low profile structure, but it will increase the visibility of the Lyman Creek facility from the valley. 8 242' A \ PRE—CAST COLUMNS F / 18 1/2" DEEP DOUBLE TEE / IIII IIIIIIII co I IIIIIIIIIII ) IIIIIIIIIIIII / PRE—CAST / INVERTED T—BEAMS CONTINOUS FOOTING A AND/OR STEM WALL PLAN VIEW PRE—CAST 3 EQUAL SPACES DOUBLE TEE WITH 2" OVERLAY. 0 1% SLOPE 2% SLOPE 0 0 CONTLNOUS FOOLING AND/OR STEM WALL PRE—CAST 7 INVERTED T—BEAMS PRE—CAST COLUMNS 4 % EXISTING TANK T OOTINGS m N N w A-A 0 / d LYMAN CREEK RESERVOIR FIGURE #1.3.1 BOZEM Ni ANA .��-- OPTION E N G t N E E It N PRECAST/PRESTRESSED CONCRETE ROOF 4M229.135 F SEPT. 2000 Technical Memorandum No. 2 February 9, 2001 1.3.2 Option II— Steel Joist and Girder system This option consists of a steel bar joists covering the reservoir. The bar joists will span from new support walls at the perimeter of the reservoir to new steel girders at the interior of the reservoir (refer to figure 1.3.2). The bar joists on each side will slope to the sides to provide the roof slope with the center span joists fabricated with a sloping top chord member to provide the roof slope. New steel columns supported on footings poured onto the existing floor would support the girders at the interior of the reservoir. The bar joists would be covered with steel decking and a metal roof placed on the steel decking. A zinc primer and epoxy based paint system is recommended for the steel joist and girders. The painting system would consist of the following: ✓ Preparation— Sandblast to near white metal profile ✓ Shop Prime Coat—Zinc Primer, 3-5 mil ✓ I"Coat Epoxy Shop—Epoxy based, 5-6 mil ✓ Field Touch up—Commercial blast, zinc primer(3-4 mil), epoxy based (5-6 mil) ✓ 2nd Coat Epoxy Field—Epoxy based, 5-6 mil This painting system was provided by Sherwin — Williams Industrial & Marine Coatings Division. Sherwin-Williams claims this system will provide a 40-year service life between sandblasting and repainting. However, based on an industrial painting contractor comments, a 25-year service life has been assumed for this system(see appendix D for paint product detail). The maintenance of the steel joist roof system will require both periodic and long-term inspections, painting touchups and full repaint. To complete the periodic inspections and touchup painting a pontoon or platform boat will be required within the reservoir. This boat will be used to float around the reservoir beneath the joist to inspect the steel for paint defects and deterioration. The boat will also act as a work platform to repair minor paint deflects. The long-term or complete repainting of the joist system will require the draining of the reservoir and erection of a scaffold system. This process will require substantial care to prevent damage to the reservoir basin, especially if a polypropylene liner system is used to seal the reservoir basin as discussed in Section 1.2.2 of this memo. Great care will also have to be taken to thoroughly clean the reservoir of all sandblasting and painting debris prior to refilling reservoir. For the purpose of estimating life cycle costs it has been assumed that the polypropylene liner will have to be replaced with each complete repainting of the roof system (25 year cycle). To provide access to the structure for maintenance requirements multiple access doors will be provided on the gable ends of the roof system. Both double and overhead doors should be provided to accommodate a variety of maintenance equipment sizes. 10 Technical Memorandum No. 2 February 9, 2001 Advantages: • A steel joist system is the least expensive of the rigid roof systems evaluated. This, however, should be tempered with the understanding that a steel roof system will have increased painting and maintenance requirements over the other rigid systems. These increased maintenance costs will impact the life cycle costs of the system. • Similar to a precast concrete system, a steel joist system will be quick to construct since members would be prefabricated before arriving at the job site. • A steel joist roofing system is lightweight, which is an advantage in a higher seismic zone. This would allow for a reduction in support column requirements. • The open to atmosphere design will facilitate aeration and venting of the radon gas. Disadvantages: • Steel is not the best material in a humid environment and would be susceptible to deterioration(rust). • A steel joist system will require yearly inspections and maintenance to repair any areas rusting from high humidity. This annual maintenance and inspection of the roof system will increase the life cycle cost of the roof. • A steel joist roof system in the reservoirs humid conditions will have to be repainted twice during the 50-year service life. Repainting of the roof system will be a major project requiring the complete draining of the reservoir and potential replacement of the liner. • Similar to a concrete roof, a steel joist roof would be visible from the valley. The roof system would be designed as a low profile structure, but it will increase the visibility of the Lyman Creek facility from the valley. 1.3.3 Option III—Three Layer HDPE Floating Cover This floating cover system is a three-layer system using a coated fabric (XR-5) top layer, polyfoam insulation middle layer and a HDPE bottom layer. The upper fabric layer is designed to be UV resistant and has a 10-year warranty. The middle layer polyfoam insulation layer is intended for floatation and insulation. The bottom HDPE layer is the contact with the potable water surface. A sump pumping system would be required to pump rain and snow water off of the cover. Because of the polyfoam insulation middle layer, the system can be installed without the perimeter weights and cables that were used on the previous reservoir cover. As discussed in Section 1.3.1 above, the water source for Lyman Creek Reservoir is high in radon and does not meet the proposed EPA Radon rule of 300 pCi/L. Typically aeration and ventilation is used to remove radon from water. Any floating cover option is not suited to provide this type of treatment. Advantages: • This floating cover option has a lower initial cost compared to the rigid frame systems. • The coated fabric (XR-5) top layer has been successfully tested to provide good UV protection and is suitable for use with extreme winter conditions. The upper layer is easily 11 242' A W12 COLUMNS (TYP.) W30 W27 El W27 W27 W27 W30 32LH CAD 48" O.C. W30 W27 W27 W27 rn W27 W30 STEEL DECKING (TYPICAL) NEW STUB WALL A PLAN VIEW 3 EQUAL SPACES 0 s STEEL DECKING g 0 EQUAL SLOPES EQUAL SLOPES STUB WALL 714 O O FOOTING a 32LH GABLED UNDERSLUNG / W12 COLUMNS (TYP.) a N EXISTING TANK PAD FOOTINGS '1 m N N o A—A / 0 LYMAN CREEK RESERVOIR FIGURE #1.3.2 BOZEMAN, MONTANA OPTION II �� STEEL JOIST AND GIRDER SYSTEM B N G I N i 6 R I N G 4M229.135 SEPT. 2000 Technical Memorandum No. 2 February 9, 2001 repaired even when it has aged unlike many membranes that become very difficult to weld when they have aged. • A floating cover would be installed below the grade of the perimeter wall and not be visible from the valley. Disadvantages: • Based on conversation with Jim Melstad, director of the Public Water Supply of the Montana Department of Environmental Quality (MDEQ), Water Division, MDEQ is not a proponent of floating covers. MDEQ is aware of the problems that the City had with the previous cover and is concerned with potential contamination from surface water sources. • A floating cover will have a limited life and may require two replacement covers in the 50- year life cycle of the reservoir. • Based on previous experience with the old floating cover, a new floating cover will require more extensive maintenance than a rigid roofing system. • A floating cover will require a sump pumping system to remove snow and rain water from the roof. • Is not well suited for radon gas removal from the water. 1.3.4 Option IV—One Layer Hypalon Floating Cover This option is similar to the originally floating cover system that was used on the reservoir. A single layer of hypalon material with flotation and anchorage would be installed. Advantages:„ • A single layer hypalon floating cover will have the lowest initial cost of all cover options. • A floating cover will not extend above the existing walls of the reservoir eliminating aesthetic impacts. Disadvantages: • MDEQ discourages the use of floating covers on potable water storage. • The system is similar to the old floating cover and would require higher maintenance than the rigid cover options. • Low design service life. A hypalon cover would require replacement several times over the 50-year design life of the reservoir. • Will require a pumping system to remove snow melt and rain water from cover. • Requires weight and cable system to keep cover tight. • Is not well suited for radon gas removal from the water. 1.3.5 Option V—Fiberglass Cover This option would be similar to the pre-cast pre-stressed concrete roof system or the steel joist and girder system. The structural members and roof covering would be fiberglass materials. 13 Technical Memorandum No. 2 February 9, 2001 Advantages: • A fiberglass system would not be effected by high humidity conditions inside the reservoir. • Fiberglass would require minimum annual and replacement maintenance. ® Light weight roof system for high seismic zone. ® Fiberglass can be repaired relatively easily if damaged. • The open to atmosphere design will facilitate aeration and venting of the radon. Disadvantages: Initial cost, a fiberglass system is the most expense cover or roof system. 1.3.6 Humidity and Radon Control within the Reservoir Enclosure The three rigid structural cover options discussed for the reservoir enclosure will require a ventilation system for humidity control and radon gas removal from the reservoir. Radon is a naturally occurring radioactive gas in ambient air. It can also accumulate in varying amounts in enclosed buildings. Radon is estimated to cause many thousands of lung cancer deaths each year. To remove radon from a structure such as a home or school, the technique frequently used is active soil depressurization. Active soil depressurization system creates a low-pressure zone beneath the building. This low- pressure zone collects the radon prior to its entry into the structure and exhausts it to the outside air. For this project, we will use a similar approach to draw the radon out of the water. Using fans, we will create a low-pressure zone above the water, drawing the radon out of the water; then exhaust the radon into the outside air. The advantage of this system is that while creating the low-pressure zone, the system draws outside air into the building; and in our and climate, outside air typically contains little moisture. When introduced in significant quantity, dry outside air can be used to control the space relative humidity, thereby protecting the structure from condensation and associated damage (rust, ice, etc.) The ventilation required for humidity control is significantly larger than the amount required to remove the radon gas. Therefore, two choices for the ventilation system are available: Constant Volume and Variable Volume. A Constant Volume system would operate to meet the worst case situation: a warm humid day. The system controls are very simple; basically `On' or `Off'. A disadvantage to the system is additional fan energy used when the building is not at worst case. While Variable Volume would reduce energy consumption by varying the air volume to maintain space humidity as sensed by a hygrometer (humidity sensor). Variable Volume can be accomplished either by staging several fans or by using a variable speed motor on a single fan. The variable volume system will require a control system and sensor that will require calibration and service. A Variable Volume system would have a minimum rate to ensure radon removal. Even by maintaining 40% relative humidity within the enclosure building, moisture/ice will build-up on the underside of the structure during periods of extreme cold weather on the bar joist option. The roof assembly would not be insulated thereby allowing the decking material temperature to fluctuate with outside air temperature. When the outside air temperature is 0°F or 14 Technical Memorandum No. 2 February 9, 2001 below, the structure will be below the dewpoint of the air with the 60°F enclosure building. At 60°F space temperature and 40% relative humidity the dewpoint is 42°F therefore any surface below 42°F water will condense. Similar to windows in a kitchen or bathroom on a cold winter day. The precast concrete structure is a better option because of the natural insulating elements of the pre-cast concrete panels. The insulation raises the interior surface temperature versus outside air temperature. By insulating the roof structure to a minimum level of R-6 and maintaining the space temperature above the dewpoint temperature will insure no condensation on the structure during the winter months. 1.4 Reservoir Water Circulation (Baffle) As discussed in Section 1.3, the reservoir was previously covered with a floating high-density polyethene (HDPE) cover. The cover was equipped with a baffle that ran east west up the center of the basin. The baffle was supported from the cover and weighted to the bottom and was designed to minimize short-circuit flow of water between the inlet and outlet pipes of the basin. This baffle was removed in conjunction with the cover removal in the fall of 1999. The large size of the storage reservoir and the configuration of the influent and effluent piping result in poor circulation and turnover of the stored water volume. The lack of a uniform circulation pattern and resulting variable detention time create large areas of stale water in the reservoir and make it very difficult to maintain a constant chlorine residual in the effluent water. The purpose of providing a diffusing or baffling system is to provide a uniform distribution of chlorine and equivalent detention time for all of the water entering and leaving the reservoir. Though it is only necessary to chlorinate the water leaving the reservoir to provide a residual in the water delivered to the city, the practice of chlorinating the reservoir influent should be continued to minimize any biological growth that may occur in the reservoir. Though mechanical mixing is a possibility, the costs of additional maintenance and power requirements would far exceed any benefits over using a passive baffling or diffuser system for circulation of the water. Because the structural support requirements of a baffling system will depend upon the type of reservoir cover installed, the tank mixing alternatives will be discussed herein as related to the tank cover alternatives similarly provided in this report. Further,the costs associated with each alternative are provided in the appendices of this memorandum. To replace the baffle, four options have been evaluated: • Option IA& I --Baffling system for use with a structural reservoir cover • Option II—Piping diffuser system for use with a structural reservoir cover • Option III-- Baffling system for use with a floating reservoir cover • Option IV— Piping diffuser system for use with a floating reservoir 1.4.1 Option IA& IB—Baffling system for use with a structural reservoir cover The surest way to cause every particle of water that enters the reservoir to follow the same path to leave the reservoir is through a baffling system. Installing baffles in the reservoir, as shown in 15 Technical Memorandum No. 2 February 9, 2001 Figure 1.4.1 and Figure 1.4.2, would divide the reservoir into either three or four compartments, respectively. The inlet water would be piped to one end of the first chamber, and after traveling end to end across the full length of each chamber, it would exit the reservoir through the outlet piping. Either baffling configuration would provide greater equalization of the detention time of every particle of water while providing for the continuous circulation of"new"water through the reservoir. The baffling systems identified in the figures would consist of reinforced polypropylene baffle walls. Other baffle materials including hypalon, Fiberglass Reinforced Plastic and stainless metal weave are available but are not differentiated in this report. The costs are further based upon supporting the baffle walls from a plastic coated stainless steel cable stretched from one end of the reservoir to the other. The cable would be routed through stainless steel eyebolts at each of the concrete columns supporting the roof. The baffle would be double reinforced at each column and securely anchored to each column with stainless steel flat bars. The bottom of the baffle could be stabilized with either a chain or another cable stretched between the columns. This method of supporting the baffle walls would be the most cost effective. Alternative methods include installing intermediate stainless steel columns for additional lateral support or hanging the baffles from the ceiling. Multiple variations are available but the cost rises quickly with the additional stainless steel hardware required to support the baffles. With the minimal flow velocities moving through the reservoir, supporting the baffles from a cable and the concrete columns would provide an adequate support system. The low chlorine concentrations in the reservoir do not pose any risk of chemical attack to any of the materials installed with the baffling system. Further, stress placed upon the membrane material due to the weight of the water is essentially negligible considering the water depth would be the same on both sides of the baffle walls. Thus, long term stress of the baffle materials would not be considered a limiting factor of this non-structural baffling system. 1.4.2 Option II—Piping diffuser system for use with a structural reservoir cover As an alternative to a baffling wall system for water mixing, a system of flow diffusers on both the inlet and outlet piping could be used. In place of a single inlet and outlet point, a series of diffusers would be connected to the inlet header. The inlet header pipe would span the width of the reservoir, or a portion thereof, and the diffusers would be connected to the header at selected intervals across the length of the header. The diffusers are essentially simple rubber check valves. Depending on the direction of installation, the valves would serve either as inlet valves or outlet valves. The proposed style of check valve also has a water diffusion characteristic when used as an inlet valve to a reservoir. An example of the possible layout of this diffusion system is provided in Figure 1.4.3. 16 EXISIING CHAIN LINK E (TYPICAL) O F- 0 I I I I I I I I I Q,lol RELOCAI ED 12" INFLOW I LINE o i I rrrrrrrrtr-rr-----10 B� r-ram 1 � — ' 500.7t N N N = INI--- �i 0 NEW BAFFLE WALLS r i o ��� o 0 rl��lr r-rr r-r r--�---------------� $P ♦♦ r S�0 10"ouaET P-lPE l 1 I 12"OUMOff(STEEL) 1 t . I � ♦ i I it I r ~�f..----- ----------------- ------- ---------wig* ' I I I I I I o o I I I N n c o ° O O c O O O O O m N m m PLAN VIEW OF RESERVOIR SCALE: 1"=30' 3 9 n LYMAN CREEK RESERVOIR FIGURE #1.4.1 N BOZEMAN, MONTANA N a OPTION IA BAFFLING SYSTEM — 2 BAFFLE WALLS E 14 G 1 N E B it I N10 6 0 4M22 -.135 SEPT. 2000 EXISTING CHAIN LINK FENCE (TYPICAL) o o a o 0 0 ° 0 F I i I I I I e RELOCATED 12" INFLOW LINE + •/� anc. BL 500.7t ° NEW BAFFLE WALLS jAt }.�� T0' OUTLET PfPE � 1 1 r 12'OUTFLOW? (STUD I i j �% 1', o I I I 0 0 0 0 0 0 0 0 PLAN VIEW OF RESERVOIR SCALE: 1"=30' LYMAN CREEK RESERVOIR FIGURE #1.4.2 BOZEMAN, MONTANA OPTION IB BAFFLING SYSTEM - 3 BAFFLE WALLS 4M229.135 SEPT. 2000 I "TIDEFLEX" CHECK VALVES EXISTING CHAIN LINK FENCE (T(PICAL) O O O O O O p O I I i OUTLET I i I COLLECTION MANIFOLD RELOCA�ED 12" INFLOW I LINE 1 ��� ,pry' O I � I rOB4 � 00.7t 0 N __-_- - OUTLET o COLLECTION MANIFOLD ';-'90 °� 0 OUTLET PIPE INLET DIFFUSER MANIFOLD 12'OWFLOW(STM) " Q El O I I I I I I I I I I I I i I I I I I o I I I I I I 0 o O O o 0 0 "TIDEFLEX" CHECK VALVE PLAN VIEW OF RESERVOIR SCALE: 1"=30' LYMAN RESERVOIR FIGURE #1.4.3 BOZEMAN, MONTANA INLET DIFFUSER OPTION II 4M229 MANIFOLD MANIFOLD DIFFUSER I COLLECTION SYSTEM E N G.N E E R i N G .135 SEPT. 2000 Technical Memorandum No. 2 February 9, 2001 The diffusers would be placed on the inlet header pipe such that the inlet water will be dispersed across the cross section of the reservoir on the far end from the reservoir outlet pipe. Similarly, the diffusers or outlet check valves on the outlet pipe header would be located to draw water from across the cross section of the reservoir and from both the bottom of the reservoir and from directly above the header pipe. The possible configurations of this type of flow distribution system are unlimited. The header pipe and diffusers could be located at various water depths in the reservoir and be turned in any direction to provide the best possible mixing of the water in the reservoir. The cost estimate for this alternative includes an inlet manifold with six diffusers at the far end of the reservoir. The outlet manifold would similarly consist of six outlets distributed across the cross section of the reservoir. The diffusers and inlet valves would be installed in pairs oriented at 90-degree angles to each other. One outlet valve would be directed across the reservoir while the second would be directed vertically. Three sets would be installed approximately 25 feet apart. The pipe material assumed in the cost estimate is PVC. With the low pressures and submerged application, the use of metallic pipe may not be practical. Both steel and ductile iron would require an exterior corrosion protection coating and after several years of operation, the coating would require periodic inspection and potentially require coating repairs. Either way, the piping would be expected to far outlast this style of cover. 1.4.3 Option III—Baffling system for use with a floating reservoir cover The system removed from the reservoir consisted of a floating cover with a single baffle wall suspended from the middle of the cover. A similar system could be reinstalled in basically the same configuration. Improvements to the baffling system under this configuration of a floating cover and baffles attached to the cover could consist of additional baffles placed across the shorter dimension of the reservoir. The additional baffles would improve the mixing and further reduce areas of stagnant water. Attaching baffle walls to the floating cover greatly increases the complexity of the membrane construction. An alternative to attaching the baffle walls to the cover is to float the baffle walls from buoyant supports at the top of the baffle walls. To prevent movement of the walls within the reservoir, the tops of the baffle walls would be attached to the underside of the floating cover at selected intervals along the length of the baffle wall, and the baffles would be rigidly connected to the floor. The cost basis for this option includes the use of two baffle walls installed across the long dimension of the reservoir. The baffles would be floated at the top and rigidly attached at the floor with stainless steel hardware. 1.4.4 Option IV—Piping diffuser system for use with a floating reservoir cover A diffuser system used in conjunction with a floating cover would be essentially the same as the system proposed with a structural cover. The only limitation of this system, if used in conjunction with a floating cover, may be the protection of the cover when the reservoir is drained. The cover would lie on top of the header pipe once the reservoir is empty. This would 20 Technical Memorandum No. 2 February 9, 2001 present a potential snagging and/or tearing problem with the floating cover. Further, access to the piping system would be limited to an underwater operation. 1.5 Chlorination System The existing chlorination system adequately serves the purpose of providing the residual disinfectant to the reservoir and distribution system. With respect to safety and optimal operation, however, several issues should be addressed with the proposed improvements to the overall facility. These issues include the method of chlorination used to provide the desired chlorine residual and the system for handling a major chlorine leak. 1.5.1 Chlorine Gas Safety Chlorine gas is by far the most common form of chlorine used throughout the drinking water industry as the primary disinfectant. Though the use of chlorine gas is both effective and economical, it presents certain health and safety concerns that water systems must take into account. The predominant concern in the use of chlorine gas is exposure to the gas as a result of a leak or catastrophic failure of a gas storage container. Generally, chlorine gas exposure is the result of a leaking supply line from the chlorine container, failure of feed equipment, or the container valve. Chlorine gas is heavier than air and will sink to the ground, producing a green fog. In lower concentrations, the gas is an irritant causing the eyes and throat to burn. At very high concentrations, even short-term exposure to chlorine gas can be fatal. For these reasons, Department of Environmental Quality standards require chlorine storage containers to be isolated from other areas of a facility and equipped with multiple safety features to prevent inadvertent exposure to chlorine gas. The larger problem is the issue of containment of a major chlorine gas leak from either a one-ton or 150-pound cylinder. A leaking chorine cylinder poses a risk not only to the operating personnel but also to nearby residents. The system operators should be trained to handle situations with minor leaks of storage vessels and should be equipped with emergency leak repair kits. In the event of a catastrophic failure of a chlorine storage vessel, however, the only procedure currently available in handling this situation would be to clear the area of any people until the gas has dissipated. With a 150-pound cylinder the volume of escaping gas may never reach any homes downwind of the facility and may pose little health risk to residents. On the other hand, a major leak or rupture of a one-ton vessel could result in a very significant plume of chlorine gas and potentially pose a considerable health threat to anyone in the path of the gas. 21 Technical Memorandum No. 2 February 9, 2001 1.5.2 Chlorine Scrubbers The options for providing protection from chlorine exposure as a result of this type of gas release include the use of scrubbers or total containment of the chlorine storage containers. Chlorine scrubbers are mechanical systems that "scrub" the chlorine out of the air by pulling the gas through a showering solution of sodium hydroxide (NaOH) that consumes the chlorine gas in a chemical reaction. The resulting product following scrubbing is salt and water. The chlorine room design would provide for containment of the gas to within the boundary of the room. The scrubber system would be connected to the chlorine alarm system and would automatically start up following detection of chlorine levels above a preset safety level. The scrubbing system would be installed such that it would pull the heavier chlorine gas off the floor and into the scrubbing process, and then vent the harmless product to atmosphere. Any scrubbing system does not actually prevent the leaking of chlorine gas into the room housing the chlorine storage containers. Once the gas leaks out however, the scrubbing system would start up and operate until the chlorine gas concentration in air was drawn down to safe levels or the scrubber ran out of NaOH. Thus, the opportunity for operator exposure to high levels of chlorine still exists. The toxic gas would not, however, reach the atmosphere outside the building. It is important to note, however, this system would not operate during a power outage, and any leaked chlorine is wasted. A typical chlorine scrubber system consists of a skid mounted assembly with a NaOH storage tank, three stage contactor, recirculation pump, exhaust fan, and integral control system. The scrubber would have to be sized to handle a major release from a one-ton container. Such a system requires considerably larger equipment than that required for a system utilizing only 150- pound cylinders. The systems would require periodic maintenance to maintain the strength of the NaOH solution in the storage tank. The estimated costs of a chlorine scrubber system and associated improvements are included in Appendix A. For purposes of this report, we have assumed the unit would be enclosed in a separated extension of the building. No Montana State agency currently requires the use of chlorine scrubbers. The Uniform Fire Code generally governs the use of scrubbing equipment, but the decision to use scrubbers is essentially left;to the discretion of the utility, and more specifically, the fire marshal. Each utility must weigh the potential risks with the costs and benefits of a scrubber system versus alternative methods of leak containment. 1.5.3 Chlorine Cylinder Containment Vessels The purpose of any chlorine protection system is to avoid exposure to chlorine gas. An alternative to scrubbing the chlorine gas out of the air following a major leak would be to completely contain any leak from reaching the airspace of a building. Secondary containment 22 Technical Memorandum No. 2 February 9, 2001 would consist of steel pressure vessels designed to hold an entire 150# or 1-tan chlorine cylinder that is currently in service and providing chlorine gas to the injection system. Such containment vessels would completely contain the chlorine cylinder while allowing the feed system to draw gas from the cylinder. These vessels would be used only for the cylinder in use at the facility. If a chlorine cylinder were to begin leaking, the gas would be contained within the storage vessel. The containment vessels are designed to feed the leaked gas to the injection system the same way the gas is normally delivered to the injection equipment. No chlorine would be vented to the atmosphere and no chlorine would be wasted. Once all the gas was used, the containment vessel would be opened and a new chlorine cylinder installed into the containment vessel. To maintain the same level of redundancy currently available at the existing facility, two separate containment vessels would be required. To match the existing chlorine system, a single one-ton vessel and a single 150# vessel would be required. Under this configuration, the system could operate the same as the existing system. If the one-ton cylinder empties while in service, the auto-switchover feature would automatically begin drawing gas from the 150# cylinder. The city would then remove the one-ton cylinder from the containment vessel and replace it with a full one-ton container. The existing chlorine room would not be large enough for this arrangement. Therefore, we have included a building expansion in the cost of the chlorine system modifications. The estimated costs of these improvements are included in Appendix A. 1.5.4 Chlorination Procedure The existing chlorine feed system injects chlorine into the inlet piping to the reservoir. Though the chlorinator may be automatically controlled, normal practice now consists of manual control of the chlorine feed equipment. Therefore, for each change the City makes to the water flowrate into the reservoir, the chlorine feed rate must be manually adjusted. Further, the chlorine concentration in the water entering the distribution system is unknown and no means are available for measuring and/or adjusting this concentration. To provide a uniform chlorine residual in the reservoir effluent, several items should be addressed. First of all, it is not effective to adjust the chlorine feed rate delivered to the reservoir influent based upon the chlorine concentration of the reservoir effluent because it takes too long to see a change in the residual chlorine concentration of the effluent. The lack of both circulation and consistent detention time compounds this problem. An alternative approach to providing a more consistent chlorine residual in the reservoir effluent would be to provide an additional chlorine feed point on the reservoir outlet piping. With this configuration, the first chlorine injector on the inlet piping would inject a constant dosage. The second chlorine injector would automatically adjust the chlorine dosage delivered to the reservoir effluent based upon the remaining chlorine residual. Basically, the second chlorinator would 23 Technical Memorandum No. 2 February 9, 2001 serve to provide a minor boost, if necessary, in the chlorine residual, and hold the desired residual closer to constant. The ideal method of automatic adjustment of the chlorine feed rate would include incorporation of the flow rate of the reservoir effluent. A compound loop controller would incorporate both the remaining chlorine residual in the effluent water and the flow rate leaving the reservoir and adjust the residual accordingly. This method of control would provide the fastest response time to changing flow rates or chlorine concentration. This approach to chlorination could be accomplished regardless of the form of chlorine used in the system. The equipment necessary for either a gas or liquid chlorine system would vary but the control of the equipment and the results would remain the same. This chlorination procedure and specific equipment operation is described in terms of a liquid chlorine feed system in the following paragraphs with additional detail provided in the system control sections of this report. 1.5.5 Liquid Chlorine Feed System In light of the increasing safety concerns associated with chlorine gas, many public water systems are converting their disinfection systems to liquid chemical feed systems. Liquid chlorine is available in the form of sodium hypochlorite (NaOCI). Sodium hypochlorite is the same disinfectant found in common household bleach products. Solutions used in water treatment, however, are approximately twice the strength and lacking the impurities found in the over-the-counter products. Sodium hypochlorite reacts with the water to form sodium hydroxide and hypochlorous acid, the same predominant compound formed with chlorine gas in water. In poorly buffered waters and large concentrations of chlorine, this reaction can slightly raise the pH of the water. With the low chlorine dosages used for Lyman Reservoir water, no change in pH would be expected, and no other changes in the water chemistry would be of concern. Liquid Chlorine Feed S stem A liquid chemical feed system utilizing NaOCI is a very simple system. The equipment necessary to effectively chlorinate with this solution consists of liquid chemical storage tanks, small metering pumps, and minimal electrical controls. A liquid feed system installed at the reservoir would consist of two independent injection systems. The primary chlorine feed would inject the chlorine solution into the reservoir influent pipeline. This metering pump would be flow-paced to automatically adjust the pump rate according to the water flow rate into the reservoir. The second metering pump would feed to the reservoir effluent pipeline. The feed rate for this pump would be automatically adjusted according to both the flow rate out of the reservoir and the residual measured in the reservoir effluent water. A single chlorine analyzer would be provided to regulate the residual. If the residual fell below a selected level, the second metering pump would add the appropriate amount of chlorine to boost the residual back to the selected concentration. If no adjustment was necessary, the effluent metering pump would not operate. 24 Technical Memorandum No. 2 February 9, 2001 The safety concerns associated with chlorine gas would be essentially eliminated with this alternative form of chlorine. The liquid solution would be delivered in bulk directly to a storage tank, and the pumps would pump directly out of the tank. The Department of Environmental Quality regulations would require secondary containment of the solution to protect from spills or leaks from the tanks. To accommodate this requirement, the storage tanks are commonly set inside the next larger polyethylene container with the top cut off. Any spills or leaks would be contained within the outer tank. Exposure to the chemical solution is a concern effectively handled with protective clothing including gloves and eye protection. Despite a very minor gas off of vapor from the solution, exposure to significant concentrations of gas is not a problem. The solution tanks would be fitted with a vent pipe to exhaust any vapors to the outside of the building. Storage of sodium hypochlorite must be monitored for any effects of degradation of the solution. With increasing storage time and temperature, the solution can degrade slightly and form both chlorate and chlorite, two compounds further regulated in drinking water systems. Suppliers of the bulk solution report no problems with such degradation in area systems using the product. Further, minor adjustments could be made to solution strength or storage time to minimize any potential degradation of the solution. Sodium hypochlorite is injected as a "neat" solution. The chemical is injected directly from the storage containers. The only maintenance requirements anticipated for the injectors would be monthly flushing and inspection of the injectors. Both area system users and suppliers of sodium hydroxide report no problems with plugging of the injectors or chemical feed lines. The chemical is, however, mildly corrosive and compatible materials must be carefully selected for use in piping and injecting the chemical. The recommended system would consist of a single 500-gallon tank installed inside a 1000- gallon tank with the top cut off for secondary containment. Two pumps would be used in the configuration discussed in the preceding paragraphs. One injector would provide chlorine to the influent water and the second would automatically adjust the feed rate delivered to the reservoir effluent water. No other equipment or containment facilities would be necessary. The estimated costs for incorporating this style of disinfection system are included in Appendix A The annual chemical cost for the sodium hypochlorite solution assuming an overall dosage of 2 mg/L, an average flow rate of one million gallons per day, and a delivered chemical cost of$1.80 per gallon is approximately $11,000 per year. As an alternative to receiving bulk deliveries, sodium hypochlorite can be generated on site. Generation of NaOCL on site would require special equipment designed to mechanically and electrically combine softened water, sodium chloride (salt) and electricity to produce the desired solution. The capital cost and maintenance requirements would increase with this system but the bulk delivery of expensive chemicals would be eliminated. 25 Technical Memorandum No. 2 February 9, 2001 1.6 Fluoridation System Modification of the fluoridation system should take into account the equipment requirements, the operation and maintenance requirements, and safety of the alternative forms of fluoride. Fluoride for use in municipal water treatment is available in three forms: Fluorosilicic Acid, Sodium Fluoride, and Sodium Silicofluoride. Only the fluorosilicic acid can be fed without mixing of a granular compound into a slurry for feeding into the water system. The equipment associated with batching a slurry from a crystalline form of fluoride is considerably more complex than the equipment necessary to directly feed a liquid form of fluoride. A fluoride system designed to feed Fluorosilicic acid consists of only three parts, a liquid storage container, a pump, and an injector. The fluorosilicic acid would be delivered in bulk and fed directly to the water. A simple metering pump provides all the necessary pumping and no mixing is required. The liquid feed system would eliminate the need to mix a slurry from the dry crystalline form of fluoride. This eliminates the safety concerns of breathing the dust and eliminates the more complicated feed system. Further, the liquid form of fluoride does not degrade or solidify when stored in the pure acid fluorosilicic form for extended periods of time. State DEQ standards require secondary containment of liquid water treatment chemicals. For this application, two different sized tanks could be utilized to provide the necessary spill containment. For a very simple spill containment system, a smaller container could be installed inside a larger tank with the top cut off. The smaller container would serve as the primary storage vessel while the larger tank would contain any spills, leaks or overflows of the primary holding tank. The alternative spill containment system might consist of a concrete curb poured around the storage tanks with a drain to waste. With this option, however, it would be difficult to salvage the chemical spilled while it could otherwise easily be pumped from the larger tank with the other option for spill containment. The recommended liquid chemical feed system would consist of one 300-gallon primary liquid storage container, installed inside a 500-gallon container with the top removed. At 1 MGD and 1 ppm feed rate, this supply would last approximately 80 days. Additional tanks or larger tanks could be added at the option of the city. The system should include two metering pumps, one primary pump, and a backup pump. The pump rate would be controlled automatically according to the flow rate into the reservoir. Aside from miscellaneous piping and the electrical control system, no additional equipment is necessary. The estimated costs of incorporating this style of fluoride feed system are provided in Appendix A. At one part fluoride to one million parts of water (1 ppm), four gallons of fluoride would treat one million gallons of water. Fluorosilicic acid delivered to the site would cost approximately $3.00 per gallon. Assuming an average of 1 MGD over the course of a year, the annual cost of this form of fluoride would be approximately $4,200. 26 Technical Memorandum No. 2 February 9, 2001 1.7 Building Modifications To accommodate the chemical feed system and flow control requirements for the reservoir, a new chemical feed building as shown in Figure 1.7.1 should be provided. The proposed chemical feed building would be located adjacent to and just southeast of the existing chemical feed building (see figure 1.7.2). In addition to the main building, a second building or an underground vault would be required for the outlet control equipment. The main building would be divided to separate the chemical storage and pumping equipment from the system control room. The topography of the proposed site and resulting inlet and outlet pipeline pressures would allow only the inlet piping to be routed through the main building. Included in the inlet piping would be an inlet control valve and flow meter as well as isolation valves to allow for servicing of these items. The primary chlorine injection assembly and fluoride injection assembly would also be provided on the inlet piping in this portion of the building. The building would also include all of the system telemetry and controls, and the chlorine analyzer used to monitor the outlet water. It would only be necessary to enter the chemical pumping and storage room to fill the storage tanks or perform maintenance on the pumps. Assumptions used in developing the costs for the building include construction of a masonry block building with a sloped precast concrete roof. 1.8 Outlet Piping; Control Buildin Vault The vault for the outlet piping would include a flow meter, a chlorine residual monitoring sample pump and a secondary chlorine injection assembly. Electrical conduit and multiple piping conduits would be necessary between the main control building and the vault. The sample pump would deliver a water sample to the chlorine analyzer in the main building. This arrangement would cause a short delay in reading the actual chlorine concentration in the outlet water but any effects on the operation of the system would be negligible. Based upon the residual reading, the secondary chlorine metering pump would deliver the necessary chlorine boost to the outlet piping back in the vault. An anti-siphon valve would prevent the chlorine solution from flowing by gravity into the outlet piping when the pump was not operating. 27 Z—� I � I SECONDARY CHLORINE x FEED TO RESERVOIR OUTLET. EMERGENCY SHOWER NaOCI P FI - _ j P P FLUORIDE INJECTION LINE CHLORINE INJECTION LINE 1 " g" 12" 2 RESERVOIR 8" FLOW INLET LINE 8" FLOW METER 8"x12" RED'R o CONTROL 8" GATE i VALVE b VALVE M 8"x12" RED'R a ca N ELECTRICAL PANEL s TELEMETRY AND DESK CONTROL PANEL 0 .. o u u n m PLAN VIEW 20'-0" o SCALE 1/4"e1'-0" LYMAN RESERVOIR FIGURE 1.7.1 j CHEMICAL FEED BUILDING B N G I I J E E R I N G 4M229.135 7JAN. 30, 2001 PR0T I o0 CONRpI/ CHEMICAL m FEED BUILDING `� a a __`;\� ♦I 1 4 a � lo 1'tii I r U 1 g5i i w c mw�o f a N�a 1 b Soso Z \\ r0s 1 CHLORINE SAMPLE PUMP LINE 20 0 20 40 -0 \\ 1 I I CHLORINE LINE stole feet o- ELECTRICAL CONDUIT — it tip GENERAL LEGEND `1 1 `• , `-�\`'�( , EX/ST/NG a CP-I-SPIKE "'^`. \ - lG�,� fG-500.00 EXISTING CHAIN --------- ---' �� l \ 1 : _�( �� / j EXISTING DITCH n N'000.00 LINK FENCE \ \ 1 -...- I\ \ \ / / / / -O-O-EXISTING FENCE _ E sooaoo (TYPICAL) �� ` + w Si / r / / / • EXISTING POWER POLE Imo`- 0 5.0051 C0h0R£ \%� / , < I _...� p i' \ MANH aWRO \ M 2 Q \ .H / / / / / , � �/ , / ca EXISTING GUY ANCHOE y �Q d l \`` I\ } 1 \v _�.&50¢ %/ % "\�y (% / / pp wcs EXISTING WATER CURB STOP o W.V. „� O .'`� - \ + / / EXISTING WATER VALVE TOW i (n - SOS )\ / , _!-, / �(( / Ii ', EXISTING TOP OF WALL ELEVATIONwo `'� / / ! � �At � �' ro.s EXISTING TOP OF SLOPE ELEVATION �-------- / `<` / / , _ i �j3 EXISTING MANHOLE (�Z / / 7`,r ' �� EXISTING CONCRETE �Q N! t \ O'--------- I I I \ ,�---ter i/ 01 cc I fill � '---___ 1 I lI Q,�1 i •' Ilitf ll i l I i l l it,// / i -' ,_/" a 1 11 III I //' ' ' ^ Y / '\v�� o 'titIIII TillIII ffl/ ,/,'� ' e �^\� i'/ "&D n o �-" f 1 i i f fill J,j 1 f j /////i �\ I J,i' aF g5.5.* Z II p 0 i 111 IIII il If//'�'i was 1 I.E-45112t- 1 III f lit fill I f le i i g + il! lift lilt IIII / ` - Q. 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I I I III, fill IIII I'll ll I111 111�__ 1 I fill IIII illl I ' 1 ! i i I'll IIII \` V CO fill +;it IIII \11 }\\i �� � \ `.�`�\ sat\ G r~ 'dl 00 0�s`• N 5000.00 __ \1\' \ t 1 1 i 1 t } \ E 4834.0 0 +\ ` '\ '1\11 Ott \f\}1l �` �� `� �� \ �� `� �` fD \+%% \111 IIII \t\�\ \ \\ gas``\ \� ``� �� �1 N CO rY it 0 I I \\♦ " \\ �`\` ` ` �� Day �Lu Ar .� AM W Sheet No. 1.7.2 Of AIR RELEASE PRESSURE VALVE REGULATING PRESSURE VALVE GAUGE 1212 0 I 16" 16" ®-- 8)l ----- - -1- - ---► - - - __ --- - -- FLOW =— FLOW METER CONTROL SECONDARY CHLORINE VALVE CHLORINE SAMPLE INJECTION T PUMP POINT 0 Ic s h C 20'-0" PLAN VIEW s m SCALE 1/4"-1'-0" LYMAN CREEK RESERVOIR FIGURE 1.7.3 OUTLET PIPING VAULT 4M229.135 FEB. 1, 2001 Technical Memorandum No. 2 February 9, 2001 A buried vault presents all of the maintenance considerations of a typical confined space. To minimize the safety hazards associated with this type of confined space several safety provisions are included in the estimate. The provisions include lighting, ventilation and a gas detector and alarm system. The lights and fan would be designed to operate concurrently. The gas detector would detect the availability of oxygen in the vault. If levels were below a predetermined safety level, the alarm condition would produce an audible alarm, light a panel and transfer a signal back to the telemetry cabinet where the alarm could be reported back to the water treatment plant. The gas detector could also be wired to operate only when the light and fan are operating. If possible and economical, the structure should be constructed to allow a standard door entry into the vault to eliminate the confined space designation. For purposes of this report, estimated costs for both a buried vault and a separate building are included in Appendix A. Because a standard entry would only be possible in a building susceptible to freezing temperatures inside, allowances for heating were included in the cost of the separate aboveground building. The building costs also apply to a masonry block building with a concrete roof. 1.9 Reservoir Electrical Control System Three different options will be discussed for the reservoir electrical control system. Briefly, these options are: • Minor repair and modification of existing system. • Convert existing control system to a PLC based system in a new control building. Install new control and power wiring for all new control equipment. • Add remote data acquisition and control capabilities to a PLC based system. The following discussions elaborate on these alternatives and subsequently associated costs for each option are presented. 1.9.1 Control System Option I Under this alternative, only the minimal repairs are implemented as required to address current equipment malfunctions and control deficiencies. For a complete description of the existing control system refer to the reservoir assessment report (Memo No. 1). In summary, the existing control panel provides control for water flow, serves as a data collection point, and provides visual status and alarm outputs. Water flow into the reservoir is manually adjusted via switches on the control panel, and instantaneous flow rate is indicated on an LED panel meter. Four 7- day chart recorders log the following information: inlet turbidity, inlet chlorine residual, outlet chlorine residual, and water flow rate into reservoir. Chlorine feed rate is not controlled by the system; feed rate is set manually on the chlorinator external to the control panel. One of the identified problems with the system is intermittent erratic output on the chart recorders. There is no apparent correlation between this phenomenon and any other system 31 Technical Memorandum No. 2 February 9, 2001 events. The source of intermittent problems can be difficult to pinpoint. The first step is to place the control system in all possible states to see if the problem can be reproduced. If this fails to reproduce the problem, the recommended solution is to modify the control system wiring in order to isolate the chart recorder power and signal wiring from the rest of the control system. Another problem identified with the system is that cycling power to the chart recorder for inlet chlorine residual will occasionally cause the solenoid valve for the chlorine gas feed system to close. The nature of this problem should be fairly easy to identify by field investigation of the interconnection of the solenoid wiring with the control system. Subsequently, minor modifications to the control wiring should be made. Internal to the control panel, there is control wiring with damaged insulation due to either a previous internal short or loose connection. The damaged wiring is to be replaced and appropriate fusing installed. Currently, the flow rate to the reservoir is manually set. If the reservoir water level exceeds the reservoir capacity, excess water is dumped into the valley via the overflow piping. It is recommended that the control system be modified to prevent reservoir overflow. In particular, when the reservoir water reaches a preset level, the reservoir inlet valve should close, the inlet chlorine feed system should be shut off, and the fluoride feed system should be stopped. The associated costs for the repairs and modifications for this option are listed in Appendix A. 1.9.2 Control System Option II Under this alternative, the existing control system would be replaced with a PLC based system with a color LCD touch screen graphical control interface. The primary purpose to implementing a PLC based system would be to replace obsolete system components and to provide a unified, flexible reservoir control system. The secondary purpose would be to provide the core functionality necessary to incorporate the Lyman Creek facility into a SCADA (Supervisory Control and Data Acquisition) system as discussed in Option III. A PLC (programmable logic controller) is a microprocessor based control unit designed to interface with industry standard sensors and measurement devices. Based on these PLC inputs, the custom PLC computer program can activate outputs to open/close valves, adjust valve settings, report alarm conditions, etc. Additional input and output modules can be added to the PLC if required for future control system enhancements. Implementation of the control sequence is accomplished by software, thereby minimizing external components and wiring. Also, software based control allows the flexibility of modifying or expanding the control capabilities with minimal or no additional hardware or wiring. The operator interface for the control system will consist of graphical representations for switches, status lights, and meters. The touch screen capability will allow the operator to control the system and adjust operating parameters in a manner almost identical to that in using physical 32 Technical Memorandum No. 2 February 9, 2001 switches and meters. One advantage to using an interface of this type is to eliminate the component cost, associated wiring, and maintenance associated with the use of discrete physical components. The other advantage is that the interface is customized to suit the operator's needs and can be modified via programming to provide additional functionality as required. With a few exceptions, the reservoir control system under this alternative will function the same as the current control system. Following is an outline of the control system function for this option. Reservoir Water Level The reservoir water level would be indicated with a graphical meter based on the input from a pressure sensor located at the reservoir outlet. Reservoir 'High Level' and 'Low Level' alarm states would be indicated by graphical lights on the operator interface. Upon 'High Level' alarm the inlet valve would be closed as discussed below. The high and low level parameters would be adjustable at the operator interface. Inlet Water Flow Inlet water flow would be regulated by a control valve and flow meter installed in the new chemical feed control building. The inlet water flow rate set point would be operator adjustable via a graphical pushbutton interface. The operation mode of the control valve would be set via a graphical HAND/OFF/AUTO switch. In the OFF position, no power would be applied to the valve. In the HAND position, the valve position would be manually adjustable via a graphical OPEN/CLOSE switch. In the AUTO position, based on feedback from the inlet flow meter, the control program would modulate the inlet valve as required to maintain the desired flow rate. For the following alarm conditions the control program would close the inlet control valve: 'High Outlet Chlorine Residual', 'High Turbidity', and 'High(reservoir water)Level'. A graphical meter on the user interface would indicate the instantaneous inlet flow rate. Additionally, a new chart recorder would be installed to provide a hardcopy historical log of the inlet flow rate. Outlet Water Flow Outlet water flow would be regulated by a control valve and flow meter installed in a new vault at the reservoir outlet. The outlet water flow rate set point would be operator adjustable via a graphical pushbutton interface. The operation mode of the control valve would be set via a graphical HAND/OFF/AUTO switch. In the OFF position, no power would be applied to the valve. In the HAND position, the valve position would be manually adjustable via a graphical OPEN/CLOSE switch. In the AUTO position, based on feedback from the outlet flow meter the control program would modulate the outlet valve as required to maintain the desired flow rate. 33 Technical Memorandum No. 2 February 9, 2001 In the event of a 'High Chlorine Residual' or 'Low Chlorine Residual' alarm state, the control program would close the outlet control valve. A graphical meter on the user interface would indicate the instantaneous outlet flow rate. Additionally, a new chart recorder would be installed to provide a hardcopy historical log of the outlet flow rate. Sample Pump A sample pump would be installed in the new vault at the reservoir outlet for chlorine residual monitoring. The operation mode of the pump would be set via a.graphical ON/OFF switch. A graphical status light would indicate whether the pump is running. A pressure switch would be installed on the sample water line in the new control building to indicate the presence of sample water. The control program would shut down the sample pump if sample water was not present. A graphical alarm light would indicate loss of sample water. Turbidity Inlet turbidity would be monitored by the control program to allow shutdown of the inlet control valve in event of high turbidity. A graphical meter would indicate current turbidity, and a graphical alarm light would indicate 'High Turbidity'. The high turbidity alarm setting would be operator adjustable at the graphical interface. As discussed above, a'High Turbidity' alarm would result in the inlet valve being closed. Additionally, a new chart recorder would be installed to provide a hardcopy historical log of inlet turbidity. Chlorination Inlet chlorination would be regulated by controlling the rate of a metering pump injecting a sodium hypochlorite solution into the reservoir influent. The required chlorine dosage level (mg/1) would be operator adjustable via the graphical control interface. Based on this set point and the reservoir inlet flow, the rate of the metering pump would be automatically adjusted to maintain the required dosage. Similarly, the outlet chlorination would be adjusted by an additional metering pump injecting sodium hypochlorite solution at the reservoir effluent. The required effluent chlorine residual concentration would be operator adjustable via the graphical control interface. The pump metering rate would be automatically adjusted based upon two conditions — measured outlet chlorine residual level and outlet water flow rate. Based upon these two parameters, the feed rate would be adjusted to compensate for any difference between the measured outlet residual and the residual set point. Graphical meters would be implemented at the control interface to display the following three items: Inlet Feed Rate, Outlet Feed Rate, and Outlet Chlorine Residual. Graphical alarm lights would be provided to indicate 'High Chlorine Residual' or 'Low Chlorine Residual alarm states. These alarm levels would be operator adjustable at the graphical interface. A new chart recorder would be installed to provide a hardcopy historical log of the residual chlorine concentrations. 34 Technical Memorandum No. 2 February 9, 2001 Fluoridation Inlet fluoridation would be regulated by controlling the rate of a metering pump injecting a fluorosilic acid solution into the reservoir influent. The required dosage level would be preset but operator adjustable via the graphical control interface. Based on this set point and the reservoir inlet flow, the rate of the metering pump would be automatically adjusted to maintain the desired dosage. Outlet Valve Vault In addition to the flow meter in the reservoir outlet valve vault, an oxygen gas sensor could be installed for personnel safety. A'Low Oxygen' alarm would be indicated on the graphical control panel in the new reservoir control building. Alternatively, a portable gas detection unit could be ' provided. Alarms In addition to the graphical alarms specified above, remote alarm reporting capability would be provided in the form of a telephone auto-dialer. The specified equipment would have the capability of up to 8 prerecorded announcements of up to 8 seconds each stored in nonvolatile solid state memory. Additionally, the equipment would be able to store multiple phone numbers for reporting alarms to additional backup locations. The costs associated with this control system option are presented in Appendix A. These costs include all new conduit, control wiring, power wiring, and equipment installation for a complete new control system for the new control building and new valve vault at the reservoir outlet. 1.9.3 Control System Option III With PLC based control implemented as described above, the system would be further expanded to allow for remote data acquisition, system status monitoring, and system control. This could be implemented separately or as part of a system incorporating the other City water facilities. By adding an additional communications module to the reservoir PLC rack, the control system could be interfaced with a computer located off site. The remote computer would contain a graphical software interface to allow remote operator control and status monitoring of the reservoir. The control program would run on a standard Microsoft Windows based operating system. All of the graphical control and display functions outlined in Control System Option H above would be reproduced in a control program operating on the remote computer. The only notable difference is that the program would be operated by mouse and menu selection rather than by touch screen. With the control program running on a standard desktop computer, additional data logging capabilities would be provided. The chart recorders currently used at the reservoir would no longer be required. Instead, this data would be logged to the computer hard drive. Custom graphical charts would be used to present the data on the computer screen and hardcopies of the data could be output to the local printer for permanent records. Additionally, alarm conditions would be time stamped and logged to the hard drive with the option of hardcopy printed output. 35 Technical Memorandum No. 2 February 9, 2001 For remote communications either a radio modem or leased line phone modem could be used. Refer to section below for telemetry options. The costs associated with this control system enhancement are presented in Appendix A. 1.9.4 Telemetry Options Two options were considered for telemetry—leased phone line and radio telemetry. Phone Modem Use of phone modems and leased phone lines would have the advantage of lower initial installation cost. However, there would be ongoing operating costs dependent on leasing the phone lines from the telephone service provider. An additional disadvantage would be that in event of telephone service interruption, remote control and data collection capabilities would be lost. The estimated cost for this alternative includes the installation of communications equipment at the Water Treatment Plant (WTP) and Lyman Creek facilities. The equipment at the WTP would consist of a modem pool and the required software to interface the HMI program to the modems. In addition to a phone modem, an additional PLC communications interface module would be required at the Lyman Creek facility. In Appendix A, an estimate for leased line telemetry between Lyman Creek and the Water Treatment Plant is listed. This estimate is based on current Qwest leased line fees. Radio Modem Use of radio telemetry would increase the initial installation cost. It would, however, eliminate the ongoing monthly phone service fees. In addition to the base equipment requirements, there would be an additional cost for a radio path study. Depending on the results of the path study, additional repeater stations could be required. The estimated cost for this alternative includes the installation of a radio base station and radio modem at the Water Treatment Plant and the required software to interface the HMI program to the radio equipment. At the Lyman Creek Facility, a remote transceiver station and PLC communications interface would be required. In Appendix A, an estimate for radio telemetry between Lyman Creek and the Water Treatment Plant is listed. A unit cost for additional repeaters that could be required is also listed. These costs do not include FCC licensing fees. 1.9.5 Reservoir Electrical System Line Voltage Service The Lyman Creek facility is currently served by a 100A single phase, 240/120 volt service. The following additional loads would be added as a consequence of the reservoir improvements: • Fan motors for the reservoir radon exhaust and humidity control system. 9 Metering pumps for the liquid chlorination and fluoridation systems. 36 Technical Memorandum No. 2 February 9, 2001 • Lighting, heat, and ventilation for a new control building. • Lighting and ventilation for the valve vault at the reservoir outlet. As a consequence the panelboard should be upgraded to 400A single phase. The cost for this service upgrade is presented in Appendix A. Service Backup Power In the event of extended power outages, the ability to maintain the desired residual chlorine level and heat the control/storage building would be lost. The addition of self- contained diesel backup generation system could provide temporary power to maintain reservoir operation during these outages. A 3000-watt uninterruptible power supply would be sufficient to provide temporary power for the control system in the interim period between loss of utility power and generator startup. There is only a marginal price difference for backup diesel generation systems in the 7 WA to 20 kVA output range. Thus, the cost of implementing a propane heating system would not offset the savings reduction for a smaller backup generation system. A price for a permanent 20 kVA backup generation system(including 24 hour fuel tank, transfer switch, charging and controls) and 3000W UPS is listed in Appendix A. Line Voltage Power New Control & Storage Building HVAC &Electrical Refer to Appendix A for general electrical and HVAC costs. This cost includes electric heat, ventilation, lighting, and service receptacles. New Vault at Reservoir Outlet -HVAC &Electrical Refer to Appendix A for general electrical and HVAC costs. This cost includes ventilation, lighting, and service receptacles. Chlorine Scrubber System If the chlorine scrubber system is implemented, more extensive electrical service upgrades will be required. In particular, Montana Power Company will need to upgrade the lines feeding the reservoir to provide 480 volt three phase power. A new three phase panel will be required, and an additional transformer will be required to provide 240/120 volt power for the control system. Additionally, a chlorine scrubber system, if implemented, will not function without an electrical source. A 50KVA backup generation system will provide power for both the scrubber system and reservoir power and control system. Additional electrical requirements for the scrubber system will include motor starters for the scrubber pump/fan motors and associated conduit and wiring. x 37 Technical Memorandum No. 2 February 9, 2001 These electrical costs are included in Appendix A. Chlorine Containment Vessels This option will require the installation of two new 20A circuits, control wiring for new chlorine sensor, and maintenance switches. This cost is listed in Appendix A. LightninWSurge Protection The existing control building has in the past been struck by lightning. The control building is located on a hillside and is the highest structure in the area. Although lightning strikes are hard to predict, it is possible that the building could be struck by lightning in the future. At minimum, lightning arrestors should be installed on the electrical service and surge arrestors on the control system and telephone service. Associated costs are listed in Appendix A. 2.0 Recommendations This section presents a summary of our recommended improvements based on similar project experience, specific project research and engineers estimates of cost. Rehabilitation of Concrete Panels: The concrete panels that line the reservoir are in reasonable condition but are nearing the end of their design life and need restoration if they are to continue to function. If left unattended the deterioration of the panels will accelerate and potentially jeopardize the stability of the earthen embankment at the southwest end of the reservoir. With the investment of covering the reservoir with a new roof or floating cover the long-term function of the panels must be addressed. Of the three options evaluated it is our recommendation to use Option H -- HDPE or Polypropylene Reservoir Lining to restore and protect the function of the reservoir. By lining the reservoir with a poly-liner a long-term positive seal will be achieved. This seal will eliminate leakage into the adjacent soil and isolate the concrete panels from the water. By removing the water contact, freeze-thaw action should be minimized on the concrete panels extending the service life of the panels. A concrete liner(Option III) on the sidewalls of the reservoir will achieve a similar result but at a slightly higher initial cost. The concrete liner would also be susceptible to cracking and may not provide a positive seal. A mortar and seal program (Option I) would initially seal the reservoir and provide similar results as a poly-liner for a lesser cost. However, based on the performance of previous patch attempts to the reservoir the seals would be short lived and would require continual maintenance and may not extend the service life of the existing concrete panels. i Reservoir Cover: A critical element in preserving the function of Lyman Creek Reservoir will be to provide an adequate roof or cover over the repaired or lined concrete panels. The majority of concrete panel 38 Technical Memorandum No. 2 February 9, 2001 deterioration to date can be directly related to weathering and freeze-thaw action. A proper roof or cover will substantially reduce these environment elements extending the service life of the facility. We recommend that a structural roof, not a floating cover be used to cover the reservoir. This recommendation is based on potential impact of the proposed EPA Radon rule. The proposed rule will require that groundwater sources such as Lyman Creek be treated for radon. A structural roof system is well suited to provide the required aeration and ventilation for radon removal and may not require any additional treatment to meet the proposed rule. Where as a floating cover system would require a separate high performance Packed Tower Aeration, Multi- Stage Bubble Aeration and other suitable diffused bubble aeration technology for radon removal. Of the structural roof systems evaluated, Option I—Pre-Cast Pre-Stressed Concrete Roof appears to provide the best value to the City over the 50-year service life of the facility. A Pre-Cast roof system will be expensive at the front end with one of the highest initial construction cost of the options considered. However, the minimal life cycle maintenance costs of a pre-cast roof will more than off-set the initial construction cost to make the pre-cast system the best value of the structural covers. A pre-cast roof will only require minimal inspection and grout patching and will not require costly repainting that would take the reservoir off line. A structural roof system such as a pre-cast system will provide added benefit protecting a poly-liner from UV and other environmental elements potentially lengthening the service life of the liner. For the ventilation of the cover we recommend a variable volume ventilation system be utilized. The reduction in fan energy between a constant and variable system will payback the difference within two years. Reservoir Baffle: The preferred baffle system is dependent on the roof and/or cover system selected. If a rigid structural roof is used a curtain baffle system that is suspended between the columns is recommended. This will provide a passive system that will maximize chlorine contact time and minimize potential circulation dead spots within the reservoir. If a floating cover is used a diffuser baffle system on the outlet and inlet pipes is recommended. This also will provide a passive system that will maximize chlorine contact time and minimize potential circulation dead spots within the reservoir. Chlorine: The modifications to the chemical feed system should incorporate the most practical and cost effective solution that also addresses the safety issues. With the increasing health concerns associated with the use of chlorine gas, any new system or modifications to an existing system using chlorine gas should incorporate facilities capable of safely handling a major chlorine leak. Alternatively, many systems are converting to liquid chlorine feed systems. Considering the pending capital costs of modifying the existing facility at Lyman Reservoir to minimize the risk of exposure of both the operators and the public to chlorine gas, the alternative liquid feed 39 Technical Memorandum No. 2 February 9, 2001 system would provide a very economical and effective solution. The liquid feed system would require less equipment, and the operational requirements would actually be less demanding than the existing gas feed system. Annual chemical costs would be higher due to the high unit cost of the sodium hypochlorite solution but a reasonable tradeoff for the simplicity of the feed system and the elimination of the major safety concerns of chlorine gas. If the city prefers to continue the use of the chlorine gas system we recommend the city carefully evaluate the two options presented for prevention of an accident with chlorine gas. As mentioned in the discussion, the Uniform Fire Code does not require the use of chlorine scrubbers but places the decision in the hands of the local fire marshal. Both scrubbers and the containment vessels would offer certain advantages but a few items should be mentioned again. The chlorine scrubbers would only protect in the event of a major leak, could be susceptible to false alarms and would not operate during a power failure. Alternatively, the containment vessels would only prevent exposure from leaking containers if the container was inside the containment vessel. Therefore, no other chlorine containers should be stored on site, and the ordering of chlorine would have to be closely monitored to prevent interruption of service while additional supply is in shipment. Flouride: The fluoride system is simply in need of an update. Batch mixing systems for combining crystalline forms of fluoride and water to form a fluoride solution are considerably more complicated, operator intensive, and difficult to regulate. With the liquid form of fluoride now readily available, a liquid feed system is the most practical and simple system available. Operator contact with fluoride dust is eliminated, and the feed equipment is very simple and affordable. The overall operating cost would likely decrease with labor and power costs taken into account. Building Modifications The existing control building is a small older masonry block building that is essentially at the end of its design life. This combined with the numerous control and chemical feed improvements proposed for the facility to promote the demolition and replacement of the existing control and chemical storage buildings with a new 600 square foot control / chemical building. The new structure should be located in close proximity to the existing structures and inlet pipe. Outlet Piping Control Building/Vault: To facilitate proper chlorine residual within the outlet pipe from the reservoir, we recommend an outlet pipe control vault or building be constructed. The proposed vault will house a chlorine injector, meter, valves and other appurtenances necessary to provide a flow regulated chlorine injector system. The system will monitor residual chlorine from the reservoir and modulate chlorine content as needed to meet residual goals. Control System It is recommended that Control Systems Option III be implemented. This would modernize the current control system and enable remote reservoir monitoring, data acquisition, and control. t 40 Technical Memorandum No. 2 February 9, 2001 The repairs outlined in Option I are sufficient to bring the reservoir to an operational state. However, the fact that many of the system components are obsolete will present ongoing maintenance and repair difficulties. Electrical Service It is recommended that a new 400A single phase service be installed. This would provide sufficient power for additional heating, lighting, and pump loads for the reservoir system modifications. Service Backup Power It is recommended that a backup generation and UPS system be implemented. This would provide freeze protection for liquid chemical storage and interior water piping, and enable emergency operation of the facility. Telemetry The initial cost for a radio telemetry system will be more expensive than for a leased phone line telemetry system. However, with a leased line system there will be ongoing monthly phone service fees. Each location added to the telemetry system would require an additional leased line and further increase phone service fees. Assuming one additional radio repeater station would be required, there would be a 15 year payback with implementation of radio telemetry (based on current Qwest leased line fees). With an additional leased line for, as an example, the booster station, this payback period would be reduced to 7 years. Given this payback and future ongoing savings, we recommend that a radio telemetry system be implemented. Lighting,/Surge Suppression Direct lightning strikes are impossible to predict, however, the price of a lightning protection system could pay for itself in equipment replacement and repairs if the control building were to be struck in the future. A complete lightning protection system is recommended. Service equipment surge arrestors and surge suppressors should definitely be implemented. Table 1.8.1 below provides a summary of recommended improvements costs for the up grading of Lyman Creek Reservoir. i 41 Technical Memorandum No. 2 February 9, 2001 Table 1.8.1 -- Summary of Recommended Improvement Costs Lyman Creek Reservoir Description Amount T Total Rehabilitation of Concrete Panels Option H-- Poly Reservoir Lin* $76,000.00 Reservoir Cover Option -- Precast Prestress Concrete roof $741,600.00 Reservoir Baffle OptionIB-- Reinforced Polypropylene Bale Walls $57,500.00 Chlorination System/Chemical Feed Building/Outlet Building Liquid Chlorine Feed System(Inlet Side Injection) $9,700.00 New Chemical Feed building Structure $93,200.00 Interior Piping $16,900,00 E,derior Inlet Yard Piping $15,600.00 Total $125,700.00 $125,700.00 Alternative Building 92(Outlet Pipe Chlorine Injection) $114,100.00 $249,500.00 Fluoride System Liquid Fluoride Feed System(Inlet Side Injection) $7,800.00 S i J 42 Technical Memorandum No. 2 February 9, 2001 Table 1.8.1 -- Summary of Recommended Improvement Costs Lyman Creek Reservoir Cont. Description Amount Total Control/Telemetry/Electrical Systems Control Systemes Control Systems-- Option II (Assumes New Building) $33,200.00 Control Systems-- Option III(assumes Control System Option II is already implemented) $14,400.00 Total $47,600,00 $47,600.00 Telemetry System Telemetry- Radio $7,400.00 Telemetry- Additional Repeater $5,200.00 Total $12,600.00 $12,600.00 Line Voltage Service Upgrade $5,200.00 Service Backup Power $17 300.00 i*bft*Surge Protection $6 800.00 $89,500.00 Construction Cost $1,221,900.00 Contingency(15%included in above items) $0.00 Engineering/Construction Administration(Assumes 15%) $180,000.00 Total $1 401900.00 J 43 Lyman Creek Reservoir Improvements Technical Memorandum No. 3 1' a 4-:�... + i V 1 Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 November 3,2000 Prepared By: 1 HKM Engineering Inc. j 601 Nikles Drive, Suite 2 a Bozeman,Montana 59715 a 406-586-8834 J Lyman Creek Reservoir Improvements Technical Memorandum No. 3 Table of Contents 1.1 Introduction.......................................................................................l 1.2 Geotechnical Field Work/Laboratory Testing.............................................l 1.3 Site Geology/ Soil Profiles.....................................................................7 1.3.1 Site Geology..............................................................................7 1.3.2 Soil Profiles (natural soil surrounding reservoir)...................................7 1.3.3 Soil profile(embankment fill)........................................................7 1.4 Groundwater......................................................................................8 1.4.1 Hydrogeologic Setting.................................................................8 1.4.2 Previous Investigations................................................................8 1.4.3 Current Investigation..................................................................9 1.5 Embankment Stability Assessment...........................................................16 1.5.1 Existing Embankment Conditions.................................................16 1.5.2 Stability Analysis.....................................................................16 1.6 Conclusions/Recommendations.............................................................19 1.6.1 Embankment Stability ...............................................................19 1.6.2 Groundwater Considerations with Respect to Reservoir Repairs..............19 References...........................................................................................21 Figures Figure 1 —Near By Well Locations................................................................2 Figure 2—Geotechnical Boring and Test Pit Locations.........................................3 Figure 3 —Well Completion Diagrams...........................................................I I Figure 4—Groundwater Elevation................................................................12 Figure 5 —Groundwater Contour Map............................................................13 Figure 6— Slope Stability Assessment............................................................17 Tables Table 1 —Groundwater Elevation Data..........................................................10 Table 2—Nearby Well Logs.......................................................................15 Table 3 — Soil Material Strength Parameters.......................................... ..........18 Table 4— Slope Stability Analysis Results Summary..........................................18 Lyman Creek Reservoir Improvements Project Technical Memorandum No. 3 November 3, 2000 Task 3 —Geotechnical Investigation 1.1 Introduction In the fall of 1999 the City of Bozeman(City)awarded the Lyman Creek Reservoir Improvements Project to HKM Engineering. The project is for the evaluation of alternatives for improvements to Lyman Creek Reservoir,Northside Pump Station, and the long range planning use of the reservoir and pump station. The project site is located to the northeast of Bozeman adjacent to the Bridger Mountain Range(Figure 1). The scope of the project broke the plan into a series of technical memorandums evaluating separate aspects of the project. This technical memorandum(No. 3)will summarize the geotechnical investigation findings and specifically evaluate the following items: • Assessment of groundwater conditions adjacent to the reservoir and; • Stability of the existing embankment fill located on the southwest side of the reservoir. Geotechnical recommendations for footings of structural covers will be provided after the preferred alternatives are determined. 1.2 Geotechnical Field Work/Laboratory Testing The geotechnical field investigation included excavation of test pits,a field drilling program and geologic review of the project area. A total of 5 exploration holes(B-1 through B-4 and MW-1)and 2 test pits(TP-1 and TP-2)were completed during this investigation. The locations of Borings B-1 through B4 and MW-1 are indicated on Figure 2. In addition to MW-1, monitor wells were installed in boreholes B-1,B-2 and B4 to allow monitoring of groundwater level fluctuations over time. The test pits, TP-1 and TP-2,were excavated at the toe of the embankment on September 28, 2000 utilizing a Cat 426C backhoe. The borings B-1 through B-4 and MW-1 were advanced on September 18, 19, and 20th 2000 utilizing a CME 75 truck mounted drill rig. An HKM professional engineer monitored the test pit excavations and drilling. _ l '.f{• r r r4 .�„2 ry ';r >r,p \\ i? r r 1�- l ...{{{�•� Af f tynn \ _ f '\ I •.f': tt j }� A ,1:. { ff G S\4.�1�I'' !` ._ ,r�l I �� - f�, r(•I 'ti�. \ �J( .lil �/.<• t� lTf� _•.}!fJ' �{rl t I r� J o rr . -. � -,.��f l �`"11 ,� � �.✓:' 'l '�'� � S"J�u✓-::��� ��L 4 �ij:�I; 11 - ti��.. -• Y��y� a,�4�• d�T ,rr•J .� n3 r" { , \ � F.��y, >•�J? i ,i 1 r�Jf `,r'`;f/` !� �` r ` � r ,.-°.'"� r f f ;+•--.a- r' ! � � 3� s�'f aj _f / r I t ,'ilfFr , y /'. r+r/ i /l :'1� �... � � `rJ ! _� t^ )- I` SGE)2r�T" , ` ;^�..._;�- .r'/1�-^_i�;�f11 1�'� �+'��tt;t�i�1�)}4- �� •.+. /f ,. 1 l 7 -� ..�..• � l� 6 7 rt � ^��,,,/�/J f, -.�t , 2 � i. �"i. _-�;'..1 i >�.�`{ ` (. �, I '!, .�t s r �_.r 3 r� =..5 I �., r 1 �, �f�.�d_: ��jJ � f r��, -7 .���t'•s` �''cy\,`•.`•�.`,,�_.._ F •�. r/_�_J _,~� `;''., '� J 11�rr r i r� �� ' .` r ,r �r r { � ' � JIJj I. , 1 '!° _ `� i-r , 1 .`_.1 t\`_ r✓�'� ! 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I_�•.,r 4 4 i , 4 ! � C'ti� r,�,�- r+ ��rl t -.�'6,1�-`r "". - ,, �. � �, pull Y � "•} I i r lR77r >�� 1 � I r ♦ t" � �I r� wL >�1 r I 1 i:. �r 1 �I' f { t-� r Jr�� - �ic�ti� !V ' rf •- _J 1 0 ,I , `'�•1, "^.�. I# ,� rJ a'��,T - l a •�, l "It �`. �I1 ' 1. xfh a tlliG ' YPY � r —N— f -�J�--����•..'�. rt11� I\ �,` _ �r 'r ;1 II .._ 11�!`.;7r r r •L. �°-, °ae ,� J t�1 F -r.• �`!,..'�4��1 _-- a� ..�:.;`��yr I; n,4Ax_ t .� f;' I' --- 1 -'' ,1—`• 2000 2000 scale feet LYMAN CREEK RESERVOIR FIGURE #1 BOZEMAN, MONTANA VICINITY MAP & NEAR BY WELL LOCATIONS ENGINEER I N 04M229.135 OCT 2000 Copyright 0 2000 HKM Engineering Inc., All Rights Reserved. SITE—MAP.DWG 0 0 0 N Q- 04 C-) Q 0 w o cr D Lu 4LO c!) z �2 L4 41 C)z r_- da d m *4 Q 3 6 Zt cli C11 %-4 CL o cl ~ Z C-) 0 ........... U.J O Z _j IJJ < ILL. 0 m ---------- .......... -J CL X— r4) LAJ FAO oto . LGS CL �o�O ... ......... 5()0 ........... M Ltj .. 0 rO 0- 5� 06 0 06 cr Z Q 0 Z. to uj z an .2% to 480 cr 0 M 0 C) II LO 10 J w I I / 1 0 w IN Q w 0 0) LLJ LE Z N m U-1 f oc) to 0 0 0 0 M LLJ 0 did 0 o(q, 0+0- .......... ------ ----------- 0- 0 co C —0 Zc 0-----------—0 -------- 0 1 � � 1 1� -1 . ------ LIL ------ 500 500 'o 0�- � 0 INo C11 0 m ui Technical Memorandum No. 3 November 3,2000 The borings were advanced from depths of 40 to 45 feet. The test pits were excavated to depths of 17 feet. All borings and test pits were backfilled with excavated material or drill cuttings. The test pit backfill was placed in 10 inch lifts and compacted by tamping with the backhoe bucket. As drilling and excavating progressed soil samples were obtained and field classified according to ASTM D 2488 (Visual-Manual Procedure) select samples were submitted for laboratory testing and classification according to ASTM D 2487. Summary logs of the borings and excavations were prepared and are included on Plates 1 through 6 in Appendix A. The soil descriptions shown on the boring logs are based on field and laboratory testing in accordance with ASTM Standards D 2487 or D 2488. The stratigraphic contacts that are shown on the individual borehole and test pit logs represent the approximate boundaries between soil types. The actual transitions may be more gradual or abrupt. The soil and groundwater conditions depicted are only for the specific dates and locations reported, and therefore, are not necessarily representative of other locations and times. At each borehole location, standard penetration test(SPT)sampling was performed using a 2-inch outside diameter split-spoon sampler in accordance with ASTM D 1586. During the test, a sample was driven into the soil utilizing a series of drops of a 140 lb. weight falling 30 inches for a total penetration of 18 inches into the soil. The number of blows required for each 6 inches of penetration was recorded. The Standard Penetration Resistance("N- value")of the soil was then calculated as the number of blows required for the final 12 inches of penetration. If 50 blows were recorded within a single 6-inch interval,the test was terminated and the blow count was recorded as 50 blows for the number of inches of penetration. This resistance, or N-value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Split spoon,bulk soil samples, and undisturbed(Shelby tube) samples were obtained from the borings. These soil samples were returned to our Billings,Montana laboratory for further examination and testing. -4- Technical Memorandum No. 3 November 3,2000 Representative field samples were selected for laboratory testing after careful visual examination of the soil and consideration of the design criteria. All index and engineering soils property tests were performed by HKM, Inc. Laboratory tests included: Test Purpose of Test Natural Moisture Content To determine the natural (in situ)water content and to (ASTM D 2216) correlate the geologic history. Atterberg Limits To provide an indicator of the shear strength and (ASTM D 4318) compressibility of the soil. Particle-Size Distribution To determine the grain sizes of the soils for (ASTM D 422) classification and identification of physical characteristics. Consolidation test To determine the settlement potential of the soil and (ASTM D 3080) aid in defining the geologic depositional history Unconfined Compression Test To determine the bearing strength of a cohesive soil (ASTM D 2166) Direct Shear To determine the shear strength of the soil (ASTM D 3080) Electrical Resistivity, To determine the deleterious affects of the soils on SO4, and pH buried metals and concrete. -5 - Technical Memorandum No. 3 November 3,2000 All laboratory tests were performed in general accordance with the most recent ASTM or other procedures standard to the industry. A summary of laboratory test results is presented on the Logs of Boreholes and Test Pit Logs on Plates 1 through 10 in Appendix A. Additional data for individual tests are detailed on the summary table and figures in Appendix B. 1.3 Site Geology/Soil Profiles 1.3.1 Site geology The reservoir site is located on gently sloping alluvial fan deposits that flank the Bridger Mountain Range. The geologic formations that form the topography of the site consist of Quaternary Alluvial Deposits comprised of interbedded clay, sand and isolated gravel deposits. Hackett and others (1960) mapped these deposits and defined them as Older Alluvial Deposits. These units consist of stream-laid and fan deposits, and are derived from erosion of the Bridger Range. According to Glancy (1964) Tertiary sediments are present beneath the Older Alluvial deposits, and consist of fluvial gravels and conglomerates, tuffaceous sandstones and siltstones, and ash deposits. 1.3.2 Soil .profiles-(natural soil surrounding reservoir) Borings B-2, B-3, B-4, and MW-1 were advanced in the undisturbed soils adjacent to the reservoir. Soil profiles encountered within the borings consisted of predominately interbedded lean clay with sand lenses and clayey sand. Isolated gravel deposits were encountered within the clay and sand deposits. Sand with gravel was encountered between the depths of 36 to 45 feet in Boring B-1. Clayey and silty sand layers were typically encountered between the depths of 34 to 40 feet in all borings. The soil profiles are defined in detail on the Logs of Boreholes in Appendix A. In general, the native soils exhibit moderate strength and moderate compressibility. 1.3.3 Soil profile-(embankment fill) Boring B-1 and Test Pits TP-1 and TP-2 were advanced/excavated within the embankment fill on the southwest side of the reservoir. -7- Technical Memorandum No. 3 November 3,2000 Boring B-1 was advanced to a depth of 45 feet and extended through the fill zone into the underlying native soils. Based on the site survey, the reservoir bottom is at the relative elevation 469 (based on the site CP-I benchmark elevation of 500, see Figure 2). This elevation corresponds to a depth of 31 feet. In general, the soil profile encountered consists of material classified as borderline between sandy lean clay and clayey sand (CL/SC)throughout the depth 3 to 36 feet. Gravelly sand and sandy gravel was encountered between the depths of 36 to 45.5 feet in B-1. The soil types encountered in the upper portions of the embankment fill are characteristic of the onsite soil materials that, most likely, were excavated to facilitate the reservoir basin construction. Based upon standard penetration tests the sandy lean clay/clayey sand embankment fill is generally firm in consistency (strength). The gravelly sand ranged from medium dense to dense in consistency. Based on the results of laboratory strength tests conducted on representative samples,the embankment fill material exhibited an unconfined compressive strength of 5.9 kips per square foot (ksf), And internal angle of friction of 30 degrees and cohesion of 350 ponds per square foot. These values are relatively high values for sandy lean clay compacted fill. 8 Test Pits TP-1 and TP-2 were excavated at the toe of the embankment. Logs of the test pits are presented in Appendix A. Soils encountered in these pits ranged from lean clay to clayey sand silty gravel layers were encountered in TP-1 between the depths of 6.5 to 12.0 and in TP-2 at a depth of 15.5 feet. The consistency of the clay soils ranged from hard to firm with occasional soft layers. The gravel deposits were typically medium dense to dense in consistency. Groundwater was encountered within the gravel layer in TP-2 at a depth of 15.5 feet (elevation 461)which indicates that a pervious sand and or gravel layer may be continuos between B-1 and TP-2. 1.4. Groundwater 1.4.1 Hydrogeologic Setting The geologic setting has been previously described in section 1.3 and consists of Quaternary Age Alluvial deposits of interbedded clay sand and isolated gravel layers. 1.4.2 Previous Investigations Groundwater is present beneath the land surface surrounding the Reservoir. The presence of -8- Technical Memorandum No. 3 November 3,2000 groundwater was verified during earlier investigations (Gaston 1990) and 1999 inspections conducted by HKM Engineering Inc. According to the Subsurface Investigation Lyman Creek Reservoir (Gaston 1990) groundwater was observed in six drill holes constructed in the dike embankment of the Lyman Creek Reservoir. Depths to groundwater reported were between 16.5 and 24.5 feet below ground surface. This report and the corresponding tests conducted by City of Bozeman show that groundwater is directly connected to water stored inside of the Reservoir. Leakage tests conducted by the City of Bozeman in January 1990 showed that during a two-week period the Reservoir leaked 200 gpm initially and declined to 80 gpm toward the end of the test. During this test the total drop in the Reservoir was approximately 10 feet. In April of 1990 a second leak test was conducted. In addition to measuring the water level drop rate in the reservoir, the rate of drop in the six Gaston wells were also measured. Results of this test showed that water levels inside the reservoir dropped at nearly the same rate as determined in the January 1990 test, and that water levels in the six Gaston wells also dropped. During the 1999 inspections when the Reservoir was drained, water was observed flowing through cracks in the Reservoir floor and walls. This indicates that water is present in the ground surrounding the Reservoir. 1.4.3 Current Investigation During these investigations, (September 2000)groundwater was encountered while drilling borings B-1, B-2, B-3, B-4, and monitor well MW-1, and excavating TP-2. Monitor wells were installed in all Borings except B-3, and each well construction is presented in Figure 3. Groundwater monitoring data is presented in Table 1 and a chart of the data is in Figure 4 -9- Technical Memorandum No. 3 November 3,2000 �w'sfB 'fin `3 `�fi" '"��'�"n �.�"�• ,.+- $a' f Measuring Point Depth to Groundwater We11 ;< Date Elevation Water Elevation (ft) (ft) A 9/20/00 500.61 34.87 465.74 9/21/00 34.85 465.76 34.36 466.25 9/28/00 34.18 466.43 f" 10/4/00 B 2 9i20/00 501.63 17.98 483.65 17.73 483.9 , s 9/21/00 16.91 484.72 9/28/00 16.85 484.78 r" 10/4/00 B-3 9/20/00 500.34 18.97 481.37 k, 9/21/00 19.56 480.78 s 18.9 481.44 9/28/00 18.74 481.6 10/4/00 MW 1 ` ° 9/21/00 503.48 25.16 478,32 24.33 479.15 9/28/00 25,08 478.4 10/4/00 Figure 5 presents a contour map of the groundwater elevations recorded on 10/4/00. During this investigation, the Gaston Wells, still present (no.s 2 through 5), were monitored. At an approximate total depth of 33 feet, each Gaston well was either dry or had only a small amount of water ponded in the bottom. This correlates well with B-1 where the first water encountered while drilling was at 36.5 feet below ground surface, and the stabilized static water level is 34.18 feet. It is not known why the current groundwater levels in the dike monitoring wells are so much lower than recorded in 1990. The construction of the Gaston wells was not documented. It is possible that they were installed as open-ended piezometers with no perforation intervals. If this is the case these wells may have been reflecting the hydrostatic head but not the actual phreatic surface in the embankment. This assumption seems relevant because at a depth of 33 feet ( elevation 466) to which the wells were drilled corresponds relatively closely with the top of the sand and gravel layer that exists under the embankment fill. It is also possible that the wells have become clogged over time and therefore are not providing accurate -10- O txo o C4 Qa C4 on C4 0 4i IT C4 C4 CV ISM CD C4 0 C5 's eq 0 04 to C > 'V' v CG U W E- C.q PWAIN "cs vi vi cn U U 7a O Ei 4QJ d L O a_I o O O O M O O O O C � O R d o W o_ L - N Z� L O 3 w 0 m m c w C7 R L N � .O ® O 17 Treatment (� m d O Y LO d � N L � U c R o c c c • 0 0 o cc iv > o J co a CDN N N m W co W W W N cu c 3 -o v c c o o /A T m N m co O O a) O <n O LO O LO O O co co f-- Co CO lczr qd V- qT (4001) uoi}en013 ja}empunojE) cz 0 0 0 0 0 4j Csl (D LO 0 uj z CC ­jz o D 1w Q: CL to F-- ca 0 LL 1-4 121 (55 --4 0 Q. (Q,J I 0 0 0 cz (z 0 0 0 C.D qR PZ-- (Q �Q 14Jo v, 0 U) 4—j 1 :z (6 0 ❑ X: LAJ cot coo g) ---------- z U 0 M, rz CQ,) C) o x w �6 (5 11 LO to to Q- 5�04 50 ........... n O M LLJ x < -------------- F� !44 0 z cr_ A C. co w Z ot 1 • 480 s 00 to 77 co 00 ui cz, cr LL _j Mhl M LE LAj did" OC) col w 3 cj <0 z N� f'cb y _j _j f EL 4) Q_ 7, 3 oL� ----------- .......... % ot C L5 LAJO 0------------—0 C14 0 50 0 C*4 O M --------- ...... 71------ t. ............ .......... ------------ M LLJ Technical Memorandum No. 3 November 3,2000 readings. Another remote possibility is that there may have been a leaking water line contributing to raising the groundwater levels in the embankment in the past that has since been shut off for the past 2 years while the reservoir water has not been used. This may have allowed groundwater levels to drop to the existing elevations. The Lyman Creek Reservoir is located in a dry drainage atop a wide plane that is bordered by much deeper drainage's (Lyman Creek to the east and an unnamed drainage to the west). (See Figure 1.) These drainages (particularly Lyman Creek) have streams in their bottoms which drain the surrounding area including the area beneath the Lyman Creek Reservoir.. The drainage above the Lyman Creek Reservoir is dry (except during storm events), but begins to flow downstream of the Reservoir. The current stream flow originates from two, possibly three sources. First, since water going into the Reservoir is not being used it is flowing through the Reservoir and into the downgradient stream. Second, a portion of the stream flow is likely from Reservoir leakage. During tests conducted by the City of Bozeman in 1990 it was estimated that 200 gpm was leaking from the reservoir. This leakage is likely ending up in the stream down gradient from the Reservoir. Third, a portion of the stream flow may be due to naturally occurring (not Reservoir leakage) groundwater. While it is not known if a portion of the stream flow originates from groundwater, it is probable that much of the stream flow (approximately 200 gpm) originates from water that is leaking out of the Reservoir. This is because Reservoir leakage supplies water to the ground surrounding the Reservoir, which consequently provides water to the drainage downgradient of the Reservoir. The nearest wells to the Reservoir that are constructed in a similar hydrologic setting are between 3000 and 4000 feet away(See Figurel and Table 2.) The static water level recorded in these wells is between 58 and 65 feet below ground surface, and the completion zones are at the well bottoms (112 feet and 360 feet). This shows that adequate amounts of groundwater are located well below ground surface near the well bottoms. Therefore groundwater located near the ground surface around the Lyman Creek Reservoir is present due to Reservoir leakage. Groundwater elevations in the borings at the time of the investigation and for several weeks afterward are indicated in Table 1. Figure 5 shows a mound of ground water with the high point of the mound centered on the Reservoir. This shows that the Reservoir is the source of -14 - 0C x C O � o ° y m 4LIS U c� =� � z � x � � •.. y a3 Id �' E U JU JU JU U lu H 64 U U cn c W 3 x W G✓ P7 C-0 N O COO 'n 0 o O ' N \,D 00 N 00 O O cM �t A O O O N kn O Co�O C0 -+ .-� N d 00 O O M O M r:. M o U � U2: ad Q t kr) °,�-° f a3a � N t ti C N M v M M V1 3 o 0 r � z ww ' o Technical Memorandum No. 3 November 3,2000 all or most of the groundwater and that groundwater is flowing away from the Reservoir into the surrounding ground. Based on construction drawings a gravel drain has been constructed around the bottom perimeter of the reservoir. Details as to the outlet of this drain are not clear but it appears the drain may be hydraulically connected to underlying pervious sands and gravels that extend under the embankment fill on the southwest side of the reservoir. The groundwater gradients indicated by the water levels in the monitor wells are indicative that subsurface drainage is occurring in the southwesterly direction. This seems to confirm that the underdrain system is functioning as intended. Due to the under-drain system the majority of the water leaking from the Reservoir is flowing to the south- west toward and into the drainage downgradient of the Reservoir. 1.5 Embankment Stability Assessment 1.5.1 Existing Embankment Conditions An interpretive geologic cross section of the existing embankment is presented in Figure 6. The soil profile and conditions have been previously described in section 1.3.3. In summary, the embankment consists predominately of sandy lean clay/clayey sand with native gravelly sand and gravel layers underlying the compacted embankment. The steep gradient of the existing phreatic surface profile within the embankment is strong indication that the sand and gravel layer is continuos under the embankment and is acting as a blanket drain. These conditions are desirable for they effectively dewater the embankment and control the seepage flows from the reservoir. The sand and gravel layer may also be hydraulically connected to the probable drain gravel that, according to as built plans may exist along the perimeter of the reservoir base. No major settlement, slumps or seepage areas were observed during a visual inspection of the embankment surface. Some minor surficial sloughing is observed on the downstream face of the embankment. This may be attributed to the relative steepness (1.38 horizontal to 1 vertical) of the face. This sloughing may also have been caused by a discharge of water that was being pumped from the reservoir at one time in the past(Dave Mell 9-5- 2000). 1.5.2 Stability analysis A slope stability analysis was conducted for the embankment fill on the southwest side of -16- EXISTING PHREATIC SURFACE -�--- ESTIMATED WORST CASE PHREATIC FAILURE ARC. FACTOR OF SAFETY=20 SURFACSEISMICE FAILURE ARC ESTIMATED WORST CASE----- (SF----01 SEISMIC COEF,=0'15) PHREATIC SURFACE FAILURE ARC FACTOR OF SAFETY=1.48 520 � r 510 � I 510 soo %�i ✓.!! B-1 % :� ;' RE if01R POOL ELEVATION=497. I soo 0-4-2 wJI 1.38 �' 490 \ 490 1 / S't Ci /-CONCRETE 460 M A r,< uNER STREAM p PISS LE 180 BO OM CLAY. UNIT .=125 CF ` '` %i% UND DRAIN C=2 PSF 3O' ` GRAVEL 470 70 CL/SC FACETiNG 0 420' ' . ,- - - --- -- - ------ -- - --- - 4 ,, , ^: r;: .`` ACE- ---- ;,-_ :POORLY GRAD- SANS: 460 - - ,• <• .. - 460 .t.• - Y' L1Y A GRAVELUNIT 130 CF WITH AN :? 450 450 440 440 430 430 420 420 410 I 410 0+00 0+20 0+40 0+60 0+80 1+00 1+20 1+40 1+60 1+80 2+00 2+20 2+40 A GEOLOGICAL CROSS SECTION FIG-6 SCALE :HORIZ. - 1"=10.00' VERT. - 1"=10.00' LYMAN CREEK RESERVOIR �FIGURE #6 BOZEMAN, MONTANA SLOPE STABILITY ASSESSMENT r PQ�-i19M 0410229.135 NOV22000 opyright 0 2000 HKM Engineering Inc.. All Rights Reserved. Technical Memorandum No. 3 November 3,2000 the reservoir. For the analysis HKM utilized the UTEXAS 3 slope stability program and incorporated soil strength data obtained from tests conducted on representative samples of the embankment fill material. Both steady state seepage and pseudo static earthquake analysis were conducted. The graphical results for each analysis are presented in Figure 6. Computer printouts of the results are also presented in Appendix C. Strength parameters used for the analysis were obtained by utilizing the results from direct shear tests conducted on the embankment soils and standard penetration tests on the sand and gravel foundation soils. Table 3 presents a summary of strength parameters used for the analysis. A seismic coefficient of 0.15 was assumed for the earthquake loading conditions. For comparison purposes we have analyzed the stability using the existing phreatic surface and an assumed worst case phreatic surface within the embankment. The worst case surface was analyzed to take into consideration the groundwater conditions recorded in the Gaston wells in 1990. TABLE 3 SOIL,MATERIAL STRENGTH PARAMETERS Material Moist Unit Weight Internal Metion Angle Cohesion (Pcf) (deg) W Embanlanent 125 30 250 Foundation 130 34 0 Gravel A safety factor of 1.5 against failure was assumed as acceptable under steady state seepage. A safety factor of 1.1 against failure was assumed as acceptable under for earthquake loading conditions. Table 4 presents a summary of the stability analysis results. TABLE 4 SLOPE STABILITY ANALYSIS* RESULTS SUMMARY Method Calculated Factor of Safety Steady State Seepage existing phreatic Surface 2.00 Pseudo Static Seismic with existing phreatic surface 1.73 Steady State Seepage assumed worst case phreatic surface 1 1.48 Pseudo Static Seismic with assumed worst case phreatic surface 1.01 -18- Technical Memorandum No. 3 November 32000 1.6 Conclusions/Recommendations 1.6.1 Embankment Stability 1. The results of the stability analysis indicate that,the embankment exhibits adequate stability under the current phreatic surface conditions. Should the seepage rate increase enough to cause a higher phreatic surface to form, instability could become a concern during a seismic event. Lining of the reservoir would reduce seepage flows and consequently lower the phreatic surface within the embankment. 2. The existing surface slough area should be repaired and minor grading performed to improve drainage along the crest of the existing embankment. The surface slough should be regraded, seeded and covered with an erosion control mat to facilitate revegetation. 3. Water should not be discharged directly onto the embankment crest or over the embankment face. If discharge of water is required when dewatering facilities the discharge should be routed around the groin areas of the embankment using hoses or other such means to prevent saturation and or erosion of the embankment soils. 4. Leakage tests should be conducted on all pipes that pass through the embankment. 1.6.2 Groundwater Considerations With Respect To Reservoir Repairs 1. The reservoir will be drained to facilitate repair work. After the reservoir is drained, the quantity of groundwater that will flow through cracks back into the Reservoir or the time required for seepage flows to diminish cannot be accurately determined. Work to seal the reservoir, (crack repair, liner installation, and or both)will be optimized if there is little to no seepage flow into the Reservoir through the cracks. An indication of the amount of flow into the Reservoir through the cracks was determined during the 1999 Reservoir inspections. At that time the Reservoir was drained for approximately one week. Initially, moderate quantities of water (approximately 50 gpm) were flowing through many of the cracks in both the floor and high points on the walls. By the end of the 1999 Reservoir inspections many of the upper cracks had dried up and the flow had decreased. Cracks near or at the floor and wall connection continued to flow the entire time and did not significantly decrease. Placement of a either a geosynthetic drainage material and or gravel drain on the reservoir bottom and partially up the sides would provide a pathway for seepage flows and -19 - Technical Memorandum No. 3 November 3,2000 allow portions of the construction to commence even if seepage flows continue. 2. The Reservoir should be drained for as long as possible prior to commencing leakage repair work. This will allow time for the mound of groundwater to passively drain back into the Reservoir and potentially eliminate the need for an active dewatering program. While there is no way to accurately determine the amount of time necessary for passive dewatering to completely dry up the Reservoir, it is suggested that a minimum of two months be allowed. 3. If a liner is installed to stop leakage and if future maintenance requires the Reservoir to be drained,then the presence of groundwater adjacent to reservoir would cause unbalanced hydrostatic uplift forces that could potentially damage the liner. Placement of an underdrain between the new liner and the existing concrete would allow dissipation of hydrostatic forces. 4. For long term maintenance programs and monitoring of the reservoir seal, groundwater levels outside of the reservoir should be periodically measured. Particularly, prior to draining the reservoir for maintenance. If the Reservoir is sealed and leakage is stopped, groundwater levels will drop and the mound of groundwater at the Reservoir may completely dissipate. 5. Reduction of leakage from the reservoir by lining or other methods most likely will cause the stream downgradient of the Reservoir to eventually dry up -20- Technical Memorandum No. 3 November 3,2000 REFERENCES Gaston 1990; "Subsurface investigation Lyman Creek Reservoir, City of Bozeman," Report submitted to the city by Gaston Engineering and Surveying May 1990. Glancy, Patrick A., 1964; Cenezoic Geology of the Southwestern Part of the Gallatin Valley Montana, Masters Thesis, Montana State College, Bozeman Montana, 1964. Hackett, O.M., Visher, F.N., McMurtrey, R.G. and Steinhilber, W.L., "Geology and Ground-Water Resources of the Gallatin Valley, Gallatin County, Montana", 1960, Geological Survey Water-Supply Paper 1482, U.S. Government Printing Office, Washington. Mell, Dave 9-5-2000; Personnel conversation with Dave Mell, City of Bozeman Lyman Creek Reservoir Operator. -21 - Lyman Creek Reservoir Improvements Technical Memorandum's No. 4 & 6 Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 February 29,2001 Revision of December 6, 2000 Prepared By: HKM Engineering Inc. 601 Nikles Drive, Suite 2 • Bozeman,Montana 59715 406-586-8834 Lyman Creek Reservoir Improvements Memorandum No. 4 & 6 Table of Contents Task 4 & 6—Booster Station Rehabilitation and Planning Study 1.1 Introduction 1.2 Computer Model Update.................................................................................1 1.3 Computer Model Findings..............................................................................5 1.3.1 Existing System Modeling Summary..........................................................6 1.3.2 20 Year System Modeling Summary.........................................................8 1.3.3 Option III—Three Layer HDPE Floating Cover..........................................11 1.4 Booster Station Operational...... ....................................... .............................10 1.4.1 Peak Day Operation.............................................................................11 1.4.2 Fire Flow Backup Operation..................................................................12 1.4.3 Emergency Backup Operation...............................................................13 1.5 Booster Station Alterations................................. ..........................................13 1.6 Northside Booster Station Control Systems......................................................... 15 1.6.1 Booster Control System Option I.............................................................15 1.6.2 Booster Control System Option H...........................................................16 1.7 Recommendations.......................................................................................20 1.7.1 Lyman Creek/Booster Station Operational Strategy.....................................20 1.7.2 Pressure Reducing Valves....................................................................20 1.7.3 Lyman Creek Reservoir..................................................... ................20 1.7.4 Booster Station.................................................................................21 1.7.5 Booster Station Repairs.............................. .........................................21 1.7.6 Booster Station Automation/Controls.....................................................22 1.7.7 Telemetry Options............................................................................22 1.7.8 Booster Station Electrical System...........................................................22 Table of Contents Cont'd Tables: Table1.4.1 Fire Flow.........................................................................................42 Table 1.7.1 Recommended Booster Station Control and Electrical Improvement Cost............23 Figures: FigureI........................... ...............................................................................2 Figure2..........................................................................................................3 Figure3 & 4....................................................................................................9 Lyman Creek Reservoir Improvements Project Technical Memorandums No. 4 and 6 March 1, 2001 (Revision of December 6,2000) Task 4 and 6 —Booster Station Rehabilitation and Planning Study 1.1 Introduction In the fall of 1999 the City of Bozeman (City) awarded the Lyman Creek Reservoir Improvements Project to HKM Engineering. The project is for the evaluation of alternatives for improvements to the Lyman Creek Reservoir, water booster station, and the long range planning use of the reservoir and booster station. The scope of the project broke the plan into a series of technical memorandums evaluating separate aspects of the project. This technical memorandum (No. 4 and 6) will specifically evaluate the use and rehabilitation of the booster station. Specific items addressed include: Updating computer water model to include major system changes made since the Water Facility Plan was completed in 1997. • The future water system demands that the North and Northwest Pressure Zones will " be evaluated based on the land use zoning, population density per zoning area, and water use as identified in the Water Facility Plan. • Based on the results of the water system model, recommendations will be made on the operational strategy for the booster station and Lyman Creek Reservoir, Changes in pump sizes and/or piping configurations, if required, will be identified. • Two options will be evaluated for the pump station controls. A cost estimate for each option will be developed. The options include: ✓ Replace existing control system with a manual control system for emergency operation only. Report alarm conditions by use of a telephone auto-dialer. ✓ Convert existing control system to a custom PLC based system. Implement remote data acquisition and control capabilities with new system. 1.2 Computer Model Update The Bozeman water system has historically been divided into two pressure zones (South and North Zones), which are essentially separated by Interstate Highway I-90 (see figure 1). The two pressure zones operated independently with Lyman Creek Reservoir being the water source for the North Zone, and Bozeman Creek and Hyalite Reservoir supplying the South Zone. In approximately 1955 a water booster station was constructed on Pear Street just south of Interstate Highway I-90 to boost water from the 1 Lj O s ` I ?°• LYMAN CREEK WATER STORAGE RESERVOIR •>i it ® ;� � j� Bride 0 — Baxter BOOSTER STATION Oak St. 1 - rr► s `-- +, CITY BOUNDARY <r NH!N!�-- `n i ,� �p ¢ , ._ Tamr� Durston Rd. ? , 2 _t z!I I l ,` q T r �, g r#�l/ h�L ob i � i�'''y-i n mo 1 11-L ' ,, C- ,�,•�.—'i m�.+ �.��` ` �1 i �? lit Oc`"`�.a. ML U.S. 191 it W. i a lege 9t._ Z. ! q Glon tat ;' L $take ,, r s 1� [� i, $ jl UnlVerSJ�yi f 9 9 o f � 111 j Lincoln Rd. �•, _' u F HILLTOP) ° , ,STORAGE TA l o �agy B1 vd t `� Ib Kagy Blvd Stucky Rd. ,, _ ._ ,?�► �p� <••� -=—,- ---! �r i C i Ri K I 'I ( � i p r' �"y u �I 9+�•a � H ji i •c rn _- -Goldensfein _P._Qt?i�Cs�[�.Rd '" � '..all •,,, a SOURDOUGH WATER _N_ ;; �; o STORAGE TANK gj TO CITY OF BOZEMAN NOT WA TER 7REA 7MENT PLANT I Ii LYMAN CREEK RESERVOIR MEMO #4 FIGURE #1 _ BOZEMAN, MONTANA NELm�' CITY PRESSURE ZONES 0@ N4M2 2 CY-t N H e R Y N G 29.135 DEC 2000 Copyright 0 2000 HKM Engineering Inc., All Rights Reserved. MEM_nGA_1.DWG Technical Memorandum No. 4 & 6 February 29, 2001 North Zone to the South Zone. The booster station was to supply the additional pressure head required to overcome the 89-ft. difference in the hydraulic grade between the North and South Zones. In 1986 the booster station was upgraded adding pressure sustaining valves and pump control valves. The pressure sustaining valves (8" and 2") were added to maintain pressure within the North Zone. The pump control valves were intended to provide a soft start to the three existing pumps,thereby reducing water hammer within the system. Prior to the installation of the pump control valves, portions of the South Zone had been damaged when the booster pumps were started. Since the installation of the 1986 improvements the booster station has not been operated. In addition to the booster station connection, a series of PRV's have also been installed connecting the zones (See Figure 2). The PRV's, conversely to the booster station step the pressure down from the South Zone into the North Zone. With the residential and commercial development of the area lying along the northwest fringe of Bozeman, a third pressure zone has been created; the Northwest Zone. The Northwest Zone includes the North 19�h Avenue commercial area, and the residential development on the northwest quadrant of Bozeman. The Northwest Zone has no independent water source and is served by both Lyman Creek Reservoir and the Water Treatment Plant through a series of PRV's connected to the North and South Pressure Zones. In association with the Water Facility Plan' completed in the fall of 1997, HKM Engineering prepared a comprehensive computer water model of the Bozeman water system. The model simulated the entire Bozeman water system for the current year and the 20 and 50 year planning windows. The model was calibrated based on fire flow tests conducted by the City Fire Department and found to be within 5% of measured flows and pressures. Utilizing this 1997 computer model as the base, major water mains and pressure reducing valves (PRV) constructed since 1997 were added to the model. The model was also updated to include major extensions recommended in the Water Facilities Plan for the 20- Year planning window. To forecast future water use, we utilized a projected growth rate of approximately 2% based on the current version of the Transportation Plane and .51 GPM / Acre as detailed in Section 5.3.4 of the Water Facilities Plan. A variety of scenarios were simulated to determine the value and efficiency of various operational strategies for both Lyman Creek Reservoir and the Booster Station ' MSE-HKM Engineering, November 24, 1997 z Robert Peccia and Associates 3 00 -N- o 1J XO l� T NOT TO SCALE x0fl �i' PRV Key �j O No. Name '► 1 Manley Rd 2 Gallatin Park 3 Perkins 4 Homp ton (dual) --� �11 �AIL 5 Oak St. 6 SID 655 Baxter Grifin f Dr_._. 7 Snapdragon -- 8 Hun ter's Way ! 9 Durston 10 NW Durston 11 Cottonwood A6 Zip A6- Oak St. i v 10 Durston Rd. Ag AL8 LOLJI 1 J I —i 'Fir�l(�� ��_!,._1� ��� it'( w--- l' Main COC Ae St i afl! . 1 _I j iIF F i If r L0z;� ,� , i dl1 11 �i W Ctille e St `�I a r f � I �. J. L _I lv7onnr� is LYMAN CREEK RESERVOIR FIGURE *2 BOZEMAN, MONTANA PRV LOCATIONS B N G I E R I N 04M279.fS135 I MARCH 2O01 Copyright 0 2001 HKM Engineering Inc., All Rights Reserved. PRV.DWO Technical Memorandum No. 4& 6 February 29, 2001 The computer modeling evaluated the following scenarios for the existing system, and 20-year planning window. Existing S sy tem Case 1 - Average Day Demand,Lyman Creek and Booster Station off—line; Case 2 - Peak Day Demand, Lyman Creek and Booster Station off—line; Case 3 - Average Day Demand, Lyman Creek Reservoir on—line; Case 4 -Peak Day Demand, Lyman Creek Reservoir on—line; Case 5 - Average Day Demand, Sourdough Tank and Treatment Plant off-line, Lyman Creek Reservoir and Booster Station on—line; Case 6 - Average Day Demand, 3,400+ GPM Fire-flow South Zone (Intersection Babcock and Grand), Lyman Creek Reservoir on-line Booster Station off-line; Case 7 - Average Day Demand, 3,400+ GPM Fire-flow South Zone (Intersection Babcock and Grand), Lyman Creek Reservoir on-line, Booster Station on-line; Case 8 -Peak Day Demand, Lyman Creek Reservoir on—line,Booster Station on- line; 20 Year Planning Window Case 9 -Average Day Demand, Lyman Creek Reservoir and Booster Station off—line; Case 10 - Peak Day Demand,Lyman Creek Reservoir and Booster Station off- line; Case 11 -Average Day Demand, Lyman Creek Reservoir on—line; Case 12 - Peak Day Demand, Lyman Creek Reservoir on—line; Case 13 - Average Day Demand, Sourdough Tank and Treatment Plant off-line, Lyman Creek Reservoir and Booster Station on—line; Case 14 - Average Day Demand, 3,400+ GPM Fire-flow South Zone (Intersection Babcock and Grand), Lyman Creek Reservoir on-line and Booster Station off-line; Case 15 - Average Day Demand, 3,400+GPM Fire-flow South Zone(Intersection Babcock and Grand),Lyman Creek Reservoir on-line and Booster Station on-line; 1.3 Computer Model Findings Upon completing the computer simulation, the base model and case simulations were evaluated. In the process of developing the case simulations it was found that the record PRV pressure settings that were added to the model' limited the flow from the Lyman Creek Reservoir. This caused the majority of the flow into the North and Northwest 3 The PRV pressure settings that were added to the original model were based on City records. 5 Technical Memorandum No. 4& 6 February 29,2001 Zones to be from the South Zone through the PRV's. One of the goals of the computer modeling was to develop an operational strategy that maximized the flow out of the Lyman Creek Reservoir. Therefore, to increase the flow from the Lyman Creek Reservoir, all PRV's were balanced to effectively work together, and a global 5-PSI pressure adjustment (5-PSI reduction) was made to the PRV's connecting the South Pressure Zone to the North and Northwest Pressure Zones. 1.3.1 Existing System Modeling Summary The following is a summary of the hydraulic modeling results for the existing system. A detailed case by case discussion of the modeling results is provided in Appendix C. Average Day Demand: The Average Day Demand assumed the following flows for each of the pressure zones: ✓ North Zone=206 GPM; ✓ Northwest Zone=400; and ✓ South Zone=2731 GPM. Lyman Creek Reservoir On- Line: On an average day the Lyman Creek Reservoir was modeled to supply 206 and 51 GPM(257 GPM total)to the North and Northwest Zones, respectively. The PRV's supplied 245 GPM to the Northwest Zone from the South Zone. The 257 GPM flow from Lyman Creek Reservoir is low and could be increased by adjusting the PRV setting connected to the South Zone. A more desirable flow from the reservoir would be in the range of 500—600 GPM to match source production. Sourdough Tank and Treatment Plant off-line, Lyman Creek Reservoir and Booster Station on—line: In this scenario,the Lyman Creek Reservoir is supplying the entire distribution system's demands—supplemented only by 1.4 MG in the Hilltop Water Tank. The existing pumps in the pump booster station supplied 2,374 GPM to the South Zone. The total demands on Lyman Creek Reservoir and Hilltop Tank were; 2,597, and 705 GPM, respectively. Theoretically, this would provide approximately 32 - 33 hours of water service to the system before the Lyman Creek Reservoir and Hilltop Tank went dry. 6 Technical Memorandum No. 4 & 6 February 29, 2001 Fire-flow South Zone, Lyman Creek Reservoir on-line, Booster Station on—line: This case simulated a fire flow during an average day with the existing system at the intersection of Grand Ave. and Babcock St., which produced a flow of 3,406 GPM. The booster station was running all three pumps, the Lyman Creek Reservoir was on-line. Pressures dropped about 10 psi in the north zone and increased slightly in the south zone with the pumps operating. The Booster Station did not increase fire flow in the South Zone. However,the Booster Station did pump approximately 2633 GPM into the South Zone reducing the flow out of the Hilltop Tank by approximately 900 GPM compared to a fire flow event with the booster station off. Peak Day Demand: The Peak Day Demand assumed a 2.5 Peaking Factor based on the Water Facilities Plan. Lyman Creek Reservoir On—Line: On a peak day Lyman Creek Reservoir was modeled to supply 657 GPM to the North(515 GPM) and Northwest (142 GPM)Zones. The PRV's supplied 858 GPM to the Northwest Zone from the South Zone. The outflow from Lyman Creek Reservoir was low at 657 GPM for a peak day and should be in the range of 1,200— 1,500 GPM. By adjusting the PRV's connecting to the South Zone the flow from Lyman Creek Reservoir could be increased to this higher flow rate which would draw Lyman Creek Reservoir down approximately 1,000,000 gallons or 20%of its total capacity on a peak day. If 1,200 GPM were contributed by Lyman Creek Reservoir to system, it would equate to 1.7 MGD or 14%of the City wide peak day demand (12.0 MGD)4 used for the modeling. Lyman Creek Reservoir on-line, Booster Station on—line; This case simulated a peak day demand with the Booster Station on-line and running all three pumps and the Lyman Creek Reservoir on-line. For this case, the Booster Station was pumping 3,558 GPM into the South Zone. This level of demand on Lyman Creek Reservoir would drain the reservoir in approximately 24 hours. This case reduced flow from the WTP by approximately 1,600 GPM and diverted flow from the system demand to fill the Sourdough Tank. This case demonstrated the potential for re-circulation of flow within the system during Booster Station operation. Comparing the PRV flows within this case and case 4 (both peak day cases) approximately 744 GPM is re-circulating back into the 4 The 1997 Water Facility Plan calculated a peak day of 10.9 MGD through 1996,a 10%factor of safety was added to the model to account for growth. 7 Technical Memorandum No. 4 & 6 February 29, 2001 North Zone from the South Zone through the Hampton PRV during Booster Station operation. This re-circulation of boosted water is inherent to this type of water system interconnected by PRV's. Adjusting the PRV's and installing check valves at key locations within the system could potentially reduce the re- circulation. The problem with re-circulation is that it substantially reduces pump efficiency, which increases pumping costs. Figures 3 and 4 on the following page schematically present the re-circulation flow. 1.3.2 20-Year System Modeling summary The following is a summary of the hydraulic modeling results for the future 20-year system. A detailed case by case discussion of the modeling results is provided in Appendix C. Average Day Demand: The Average Day Demand assumed the following flows for each of the pressure zones: ✓ North Zone= 606 GPM; ✓ Northwest Zone= 1,211; and ✓ South Zone= 3,106 GPM. Lyman Creek Reservoir on—line; This case represents the future average day demand with the Lyman Creek Reservoir on-line. For this case, Lyman Creek Reservoir was supplying 683 GPM to the North and Northwest Zones, with the PRV's supplying 1,134 GPM into the Northwest zone. The 683 GPM flow from Lyman Creek Reservoir is desirable for it matches a reasonable source production from the spring boxes. 8 FIG 3 - Case 4 Booster Station Off, Intra-Zone Flow; Yr. 2000 Peak Day Lyman Creel • Reservir E Northwest North Zone 142 m Zone 657 m 0 gpm Booster Station (off) South Zone 0 gpm WTP and Tanks FIG 4 - Case 8 Booster Station On, Intra-Zone Flow; Yr. 2000 Peak Day. Lyman Creep Reservoir m Northwest North Zone 142 m Zone 515.12T___..... M (To N.Zone) `oJa°s��oo 144 gpm Booster ............................... Station (on) South Zone .............................3,558 gpm.................' Technical Memorandum No. 4& 6 February 29, 2001 Sourdough Tank and Treatment Plant off-line, Lyman Creek Reservoir and Booster Station on—line: In this scenario,the Lyman Creek Reservoir is supplying the entire distribution system's demands—supplemented only by 1.4 MG in the Hilltop Water Tank. The existing pumps supplied 2,529 GPM to the South Zone. The total demands on Lyman Creek Reservoir and Hilltop Tank were; 2,948 and 1,970 GPM, respectively. Theoretically, this would provide approximately 12 hours of water service to the system before the Hilltop Tank went dry. There was also re- circulation of boosted water back from the South Zone into the North Zone (Hampton PRV 289 GPM). Fire-flow South Zone, Lyman Creek Reservoir on-line, Booster Station on—line; This case simulated a fire flow during an average day with the 20-yr expanded system at the intersection of Grand Ave. and Babcock St., A flow of 3,661 GPM was attained at the South Zone intersection. The booster station was running all three pumps,the Lyman Creek Reservoir was on-line. The Booster Station increased fire flow by approximately 200 GPM and reduced outflow from the Hilltop Tank by approximately 900 GPM. Peak Day Demand: The Peak Day Demand assumed a 2.5 Peaking Factor based on the Water Facilities Plan. Lyman Creek Reservoir on—line; This case represents the future peak day demand with the Lyman Creek Reservoir on line. For this case, Lyman Creek Reservoir was supplying 1,672 GPM to the North and Northwest Zones, with the PRV's supplying 2,870 GPM into the Northwest Zone. Assuming Lyman Creek Reservoir was full and filling at 500 GPM, a peak day would withdraw 2.4 MGD from the reservoir and deplete the storage by 35% of reservoir volume. 1.4 Booster Station Operational To evaluate the Booster Station operation strategy we have considered a number variables including Water Treatment Plant (WTP) capacity, growth patterns, water distribution system configuration, and hydraulic modeling of the system. We have identified three (3)basic operation strategies to evaluate: ✓ Peak Day Operation; ✓ Fire flow Backup Operation; and ✓ Emergency Backup Operation 10 Technical Memorandum No. 4 & 6 February 29, 2001 1.4.1 Peak Day Operation A peak day operation strategy would involve operating the booster station on peak flow days (10— 12 MGD)that typically occur during the peak summer irrigation months. The objective for this operational strategy would be to buffer the WTP from the peak use events that occur during this period. Based on discussions with the WTP Operators and the 1997 Water Facility Plan, it is our understanding that the WTP is slow to react to peak day demands and it often requires several days to refill the Sourdough and Hilltop Tanks after a peak use period. This is primarily due to the slow response time to adjust the raw water inflow into the WTP from Hyalite Reservoir. The City is currently designing a pre- sedimentation basin at the WTP that may help the WTP be more responsive to high use periods. However, it is most efficient to operate a treatment plant at a constant rate, minimizing short-term variations to meet peak flows. By operating the Booster Station during peak days, Lyman Creek Reservoir would become available as storage to the South Zone providing equalization storage to buffer the WTP. The call to energize the Booster Station could be either manual or automated by telemetry. By monitoring the Hilltop Tank water level, the WTP operators could evaluate a potential peak day type flow and the ability of the current production of the WTP to maintain the tank levels. If it is determined that the WTP can not keep up with the water demand, calls would be made to both energize the Booster Station and increase flow from Hyalite reservoir. The call to energize the booster station could be either by telemetry from the WTP to the Booster Station for an auto-start or a standard telephone call to the City Shop for staff to go to the station and manually start the pumps. The hydraulic modeling of the City water system found that for a current peak day(12 MGD)that Lyman Creek Reservoir provided 657 GPM with the Booster Station off, and 3,471 GPM with the Booster Station on. The Booster Station was pumping 3,558 GPM into the South Zone. Because of the PRV configuration connecting the North Zones to the South Zone some re-circulation of boosted water should be expected back into the North Zones from the South Zone. Based on the hydraulic modeling, we estimate that approximately 750 GPM of the 3,558 GPM pumped by the Booster Station is re- circulating into the North Zone through the Hampton PRV. This equals a net gain of approximately 2,800 GPM or 4 MGD into the South Zone. Figures 3 and 4 show the schematic distribution of Lyman Creek Reservoir flow within the system for peak day flow with and without operating the Booster Station. This water from the Booster Station would have significant impact on maintaining South Zone tank levels during peak days and would effectively buffer the WTP from demand spikes. This level of pumping would drain the Lyman Creek Reservoir in just one(1) day and the operation of the Booster station should be measured in hours not days for this operation strategy. The water level and recovery rate of the Lyman Creek Reservoir will be of significant importance during the operation of the Booster Station. To help insure that adequate water is available in the reservoir during Booster Station operation, water levels in the reservoir should be monitored by telemetry back to the WTP. 11 Technical Memorandum No. 4 & 6 February 29, 2001 The drawback of using the Booster Station for peak day flow is energy cost and the inefficiencies caused by the re-circulation back through the PRV's into the North Zones. Based on current electrical rates,to operate the Booster Station for a 24-hour period will cost approximately $950.00. When weighted to account for the re-circulation back into the North Zones, the cost to boost water into the South Zone equals $0.18 /HCF. The current city water rate structure charges an average of$1.15 /HCF for water use beyond the base use of 2.5 HCF/month. The re-circulation of boosted water could be partially reduced by either installing check valves at key locations or adjusting the Hampton PRV to reduce flow from the South Zone into the North Zone. 1.4.2 Fire flow Backup Operation A fire flow operation strategy would involve operating the booster station during fire flow events. The objective for this operational strategy would be to augment fire flows in the South Zone and maintain water tank levels during fire flow events. The hydraulic modeling for this operation strategy was completed under cases 6, 7, 14, and 15 for the current and 20-year planning windows, respectively. The modeling simulated a fire flow during an average day at the intersection of Grand Avenue and Babcock Street. Table 1.4.1 summarizes the modeling results. Table 1.4.1 --Fire Flows Year Pump Status Fire flow Booster Station GPM Flow 2000 Off 3405 NA 2000 On 3406 2633 2020 Off 3462 NA 2020 On 1 3661 2856 The hydraulic modeling found that the Booster Station only marginally enhanced fire flow (200 GPM),but did effect tank levels. The Booster Station pumped an average of 2,750 GPM into the South Zone. Of which approximately 200 GPM went to increase fire flow and 2,550 GPM went to domestic flow to maintain water tank levels. Assuming a two (2) hour fire flow event the booster Station would pump approximately 330,000 gallons into the South Zone to maintain tank levels. This equates to approximately 25% of the effective available volume of the Hilltop Tank(1.4 MG). Similar to the peak day operational strategy, re-circulation of boosted water was a concern during the 2020 fire flow scenario. For the 2020 fire flow the model projected a re-circulation of 427 GPM through the Hampton PRV. 12 i Technical Memorandum No. 4& 6 February 29, 2001 1.4.3 Emergency Backup Operation An emergency backup operation strategy would involve operating the booster station during emergency or scheduled maintenance events. The objective for this operational strategy would be to supply emergency flow into the South Zone if the WTP or a South Zone water tank were to go off-line. The scenario for this type of operation would most likely be a scheduled maintenance event at the WTP or a water tank. However, in a true emergency such as a long duration brownout,the Lyman Creek Reservoir and Booster Station could be vital in maintaining water service to the South Zone. The hydraulic modeling for this operation strategy was completed under cases 5 and 13 for the current and 20-year planning windows. The modeling simulated the WTP and Sourdough Tank to be off-line during an average day flow. The hydraulic modeling found that the Booster Station would supply 2,300 to 2,500 GPM to the South Zone. Assuming that Lyman Creek was full at the start of the event and that both the reservoir and Booster Station are equipped with backup power,Lyman Creek Reservoir would supply approximately Iday of additional supply to the South Zone on an average flow day. During an emergency condition, such as WTP failure,it is anticipated that public water consumption would be greatly reduced through notification of the public. This reduction of use would substantially increase the backup capabilities of the Lyman Creek Reservoir and booster Station. For an emergency backup operational strategy, the installation of backup power at Lyman Creek Reservoir and the Booster Station is mandatory. Backup power at the reservoir is required to maintain the chorine fed system. As discussed in the emergency brownout scenario given above, the combination of the reservoir and booster station will provide a minimum of one-day storage to the South Zone provided that both facilities have backup power. Without backup power during a brownout, the facilities will not function and would not have any backup value. The backup generators should be sized to provide full operation of each facility. In conjunction with the backup power it is important to regularly exercise equipment. This mainly holds for the Booster Station which may go extended periods between use. The exercising of the booster station should involve the monthly or at a minimum quarterly startup of the generator and booster pumps to insure the equipment is in proper operating condition when called upon. 1.5 Booster Station Alterations Outside of the control system modifications for the booster station, the mechanical modifications necessary to startup the station are relatively simple. Two of the three pumps in the booster station appear to be in good condition. The third pump, however, 13 Technical Memorandum No. 4 & 6 February 29, 2001 has a hole in the pump casing. A representative of the pump manufacturer has indicated this pump should be replaced because it would not be cost effective to replace only the casing. The pumps have not been operated for approximately 14 years. Because of this extended period of inactivity, several items should be considered prior to starting up these pumps. First of all, the bearing grease in both the motor and the pump itself may have dried and degraded such that it would provide little protection to the bearings if the pump were started. Further, if any moisture was present in the vicinity of bearings,there is a potential for some scaling and rust buildup on the bearings. Any imperfection in the bearings will cause the bearings to quickly fail and potentially damage the pump shaft if operated in this condition for even a short period of time. With respect to the pump impeller and casing, the only damage that may be present would be in the form of minor corrosion and rusting. This would be the case if the pump has been partially full of water or had any moisture at all inside during the extensive downtime. Unless this corrosion was excessive, minor rusting would really not cause any problems with operation of the pump. Prior to starting these pumps, all bearings should be thoroughly greased at the pump grease fittings until the old grease is displaced. This would at least provide for a fresh setting of grease for the bearings. If the bearings were damaged in any way the grease would not fix the problem. Any bearing problems would become apparent through vibration or noise during operation. Also prior to startup of the pumps,the pumps must be completely filled with water and purged of any air. The pump should also be turned several revolutions by hand to help fully fill the pump and to check that the bearings are not completely seized. Split case pumps can be rebuilt and the bearings replaced. The manufacturer's representative has indicated that the work required to pull the casing and bearing covers is time consuming and recommended replacing the bearings if ever the pump was disassembled to this extent. Therefore, if the City personnel would be more comfortable inspecting the pump bearings prior to startup,they should have the replacement bearings available at the time of dismantling the pumps. As indicated,the risk of operating the pumps with bad bearings is potentially damaging to the shaft. In this event,the shaft would have to be either replaced or repaired along with the installation of new bearings. In summary, two of the three pumps should be started as described above and monitored following startup for any vibration and potential bearing damage. The third pump should be replaced with the exact same pump or the closest updated match. Unless the replacement pump is of different dimensions, no other piping modifications would be necessary to provide for a fully functioning pump station. The list cost of the appropriate 14 Technical Memorandum No. 4& 6 February 29, 2001 new pump is $12,500.00. The estimated cost to have a general contractor provide and install the pump is $16,000. 1.6 Northside Booster Station Control systems Two different options will be discussed for the booster station electrical control system. In summary, these options are: • Replace existing control system with a manual control system for emergency operation only. Report alarm conditions by use of a telephone auto-dialer. • Convert existing control system to a custom PLC based system. Implement remote data acquisition and control capabilities with new system. 1.6.1 Booster Control System Option I Under this alternative, the existing control system will be replaced with a basic manual control system for emergency operation only. Each pump will be manually activated at the booster station according to a prescribed written procedure. System status and alarms will be indicated via panel lights and electronic meters in a new system control panel. Pump Control: The operation mode of each pump will be set with a HAND/OFF/AUTO switch. When switched from OFF to HAND,the associated pump will be brought on line as described in Technical Memorandum 1. In particular: When the pump is activated, a time delay will be initiated by an external timing relay to allow discharge pressure to build. After a preset time delay, the valve on the discharge side of the pump will open and allow water to flow. When turned off, reverse pressure will be applied to the valve, and a limit switch attached to the valve will shut the pump off after the valve closes. A status light at the control panel will be lit to indicate that the pump is running. The 'AUTO' position will be reserved for future use with a PLC based control system. The existing motor starters will be replaced with combination starter/disconnects with solid state overload relay. This will provide integral phase loss protection for the motors. A control panel status light will indicate pump overload shut down. Manual reset will be required for the pump to be restarted. Additionally, a temperature sensor/switch will be added to each motor housing. When the motor housing temperature exceeds a preset value, the pump will be shut down and locked out until manually reset. A panel light will be provided for each pump to indicate high temperature shut down. 15 Technical Memorandum No. 4 & 6 February 29, 2001 System Pressures: The existing system pressures are currently monitored by use of direct reading mechanical gauges piped directly to the water system. System pressure is monitored at two points: Suction and Discharge. Each gauge will be replaced by an electric pressure transducer in combination with a digital panel meter. If suction pressure falls below a preset limit, any running pump will be stopped and all pumps will be locked out. An indicator light on the control panel will notify operator of low suction pressure shutdown. Manual reset will be required to restart pumps. If discharge pressure exceeds a preset limit, any running pump will be stopped and all pumps will be locked out. An indicator light on the control panel will notify operator of high discharge pressure shutdown. Manual reset will be required to restart pumps. Remote Alarm Reporting_ Remote alarm reporting capability will be provided in the form of a telephone auto- dialer. The specified equipment will have the capability of up to 8 prerecorded announcements of up to 8 seconds each stored in nonvolatile solid state memory. Additionally, the equipment will be able to store multiple phone numbers for reporting alarms to additional backup locations. The following six alarm conditions would be reported: • Pump Number One Shut Down • Pump Number Two Shut Down • Pump Number Three Shut Down ® High Discharge Pressure Shut Down Low Suction Pressure Shut Down • Loss of AC Power The associated costs for this option are listed in Appendix A. 1.6.2 Booster Control System Option II Under this option, a new PLC based system will be implemented for control and monitoring of the Booster Station from a remote location. The operator interface as described in Option I above will still be used for control at the Booster Station. The manual operation of the Booster Station will still function as outlined above. Additional features will be as outlined below. Pump Operation: With the pump switch in the AUTO position, the pump can be started from a remote location via desktop computer based H1VII (Human Machine Interface) software. A 16 Technical Memorandum No. 4 & 6 February 29,2001 graphical representation of the Booster Station control panel will be displayed on the HMI program. A graphical representation of each switch will show the HAND/OFF/AUTO position. Remote control of the pump will be disabled if the physical switch at the Booster Station is in the OFF position. Additionally, the following graphical lights will be provided at the HMI interface for pump status and alarms: 0 Pump On • Pump Valve Open • Pump Start Failure • Pump High Temperature Shutdown • Pump Overload Shutdown Booster Station Suction and Discharge Pressures: In addition to the digital panel meters discussed in Option I,the suction and discharge pressure sensors will be connected to the PLC for remote data reporting. The HMI software interface will have a graphical representation for each of the Suction Pressure and Discharge Pressure meters. Additionally, the following graphical lights will be provided at the HMI interface for the following alarm conditions: • High Discharge Pressure System Shutdown • Low Suction Pressure System Shutdown Data Logging: Each of the alarm conditions presented above will be time stamped and logged to the hard drive of the remote computer hosting the HMI software. The system operating pressures will be regularly sampled and logged to hard drive. System pressure trends will be viewable on a graphical chart. The cost associated with this control system enhancement are presented in Appendix A. This cost will be in addition to the control system upgrade outlined in Option I. Note that this cost assumes that the HMI software and computer have already been implemented for Lyman Creek Reservoir Control. Pressure Reducing Valve -Flow and Pressure Telemetry Under this option, the goal is to provide a means to remotely monitor and record flow and pressure at the system PRV's. A flow meter will be installed at the PRV and a pressure sensor on the inlet and outlet side of the PRV. A PLC will be installed at the PRV to 17 Technical Memorandum No. 4 & 6 February 29, 2001 collect data from the flow and pressure sensors. This information will be displayed locally on digital panel meters. Additionally, a transceiver will be required to transmit data from the PRV to the central monitoring location. This can be either a phone modem or a radio transmitter, depending on the telemetry option selected. Additionally, power will need to be supplied to the PRV location to operate the sensors, meters, PLC, and modems. The associated cost is listed in Appendix A. This is an estimated unit cost per PRV. Telemetry Options: Two options are considered for telemetry—leased phone line and radio telemetry. Phone Modem: Use of phone modems and leased phone lines has the advantage of lower initial installation cost. However,there will be ongoing operating costs for each leased telephone line. Each facility (WTP, Booster Station, Lyman Creek and City Shop)will require a leased line at approximately $50/month. Periodically the telephone provider may reassign lines that will require re-calibration of the telemetry equipment. This re- calibration is typically completed by factory trained technicians and is at an additional cost to the City. The base cost for this alternative will be the installation of communications equipment at the central control location to interface with the remote data collection locations. This equipment will consist of a modem pool and the required software to interface the HMI program to the modems. Additionally, each remote location will require a leased phone line and communications equipment. This equipment would consist of a communications module for the PLC and an external leased line modem. The primary advantage of a phone modem telemetry system is an increased rate of data transmission and that FCC licensing is not required. Current commercial grade telephone modems for telemetry systems operate at 28.8 to 56.6 Kb/sec. Radio Modems operate at 9.8 to 14.4 Kb/sec. These advantages are offset by the fact that data transmission rates are typically not an issue for the proposed type of telemetry system. The amounted of data transmitted is minimal. In addition, it is our understanding that the City already uses radio telemetry and has a current FCC license. In Appendix A, an estimate for the base cost is listed plus a unit per-location cost for each remote site. This estimate is based on current Qwest leased line fees. 18 Technical Memorandum No. 4& 6 February 29, 2001 Radio Modem: Use of radio telemetry will increase the initial installation cost, however will eliminate the ongoing monthly phone service fees. In addition to the equipment, there may be an additional cost for a radio path study. As for the phone modem, the base cost for this alternative will be the installation of communications equipment at the central control location to interface with the remote data collection locations. At each remote location, a radio modem, antenna, and PLC interface module will be required. Also, depending on the results of the radio path study, additional repeaters and antennae may be required. In Appendix A, an estimate for the base cost is listed plus a unit per-location cost for each remote site. This cost does not include FCC licensing fees. Booster Station Electrical System Line Voltage Service: The existing main electrical service is a Federal Pacific Electric 225 amp three phase 600 volt panel. Federal Pacific Electric is no longer in business, and replacement breakers for this equipment can be difficult to locate and expensive. A cost for replacement of the service equipment is listed in Appendix A. Service Backup Power: To provide backup power in case of a utility outage, a 150KW generator set would be required. This would provide sufficient power for starting and running all of the Booster Station pumps, provided that the motors were not started simultaneously. The control system would be designed to prevent simultaneous startup of the pump motors. An installed cost for this option, including transfer switch, is presented in Appendix A. Li hg; tning/Surge Protection: Because the Booster Station is located in the valley, the probability of a direct lightning strike is much less than that for the Lyman Reservoir facility. However, the possibility of voltage surges in the power lines and communication lines resulting from local strikes still exists. For this reason,transient voltage surge suppression should be installed on the incoming power and communications lines. See Appendix A for the associated cost. 19 Technical Memorandum No. 4 & 6 February 29, 2001 1.7 Recommendations This section presents a summary of our recommended Booster Station operational strategies and improvements based on hydraulic modeling, specific project research and engineers estimates of cost. 1.7.1 Lyman Creek/Booster Station Operational Strategy: Any booster Station operational strategy will need to incorporate and consider the following elements of the Bozeman Water System: ✓ Water Treatment Plant Capacity and potential expansion requirements; ✓ PRV flows and potential re-circulation between pressure zones; ✓ Lyman Creek is a ground water source and does not require filtration; ✓ Overall shortage of storage volume within South Zone; and ✓ The North and Northwest Pressure Zones are anticipated to experience the greatest amount of growth over the twenty years. Based on the hydraulic modeling results and the above elements we recommend the following operation strategies: 1.7.2 Pressure Reducing Valves: The existing PRV's connecting the South Zone to the North Zones are currently out of calibration based on City records. A detailed evaluation of the PRV's should be completed including vertical elevation survey to establish hydraulic grade line, computer modeling, and field testing to establish optimum settings. The hydraulic modeling completed for this memorandum found that the current PRV setting would restrict flow from Lyman Creek Reservoir. The PRV's were artificially calibrated and globally reduced by 5 PSI. This significantly improved the flow from the reservoir. Additional modeling, and field work should be conducted to determine the optimum setting to maximize the use of Lyman Creek Water and to minimize re-circulation within the system during Booster Station operation. 1.7.3 Lyman Creek Reservoir: Lyman Creek Reservoir is currently an under utilized water source and storage facility. Lyman Creek is a ground water source and therefore does not require filtration. This makes Lyman Creek Water an inexpensive water supply for the City. Traditional Lyman Creek has only served the North Zone that has minimal water consumption. The Perkins PRV that connects the North Zone to the Northwest Zone should be calibrated such that it maximizes flow from the North Zone. This will allow for the eventual full utilization of 20 Technical Memorandum No. 4& 6 February 29, 2001 the Lyman Creek resource by the combined consumption of the North and Northwest Zones. The Northwest Zone is currently the fastest growing area in the Bozeman Water System and will, in only a few short years, fully utilize the Lyman Creek Water. Utilizing Lyman Creek Water in the Northwest Zone will also forestall the eventual expansion or replacement of the WTP. 1.7.4 Booster Station: In completing the hydraulic modeling, we evaluated three potential operating strategies for the Booster Station: ✓ Emergency Operation; ✓ Peak Day; and ✓ Fire Flow augmentation. Of the three strategies only fire flow augmentation appeared to have questionable value. Fire flow was modeled for the current and 20-year system. For the current system the Booster Station did not increase fire flow. For the 20-year system fire was increased by approximately 200 GPM. However, under fire flow conditions the Booster Station did help sustain water levels in the Hilltop Tank. For the peak day and emergency operational strategies the operation of the Booster Station was beneficial. For peak day operation the Booster Station will effectively buffer the WTP from demand spikes and help maintain tank levels in the South Zone. For emergency operation the Booster Station and Lyman Creek Reservoir could supply 1-2 days of backup storage dependant on water demand. Therefore, we recommend that the Booster Station be used for emergency and peak day operation. Utilizing the Booster Station for emergency and peak day operation may severally tax the storage capacity of Lyman Creek Reservoir. To minimize the potential of completely draining the reservoir during emergency or peak flow conditions, we recommend that telemetry that monitors water level in the reservoir be supplied to the WTP. 1.7.5 Booster Station Repairs_ We recommend that the damaged pump be replaced in kind with a new pump. The estimated cost to replace the pump is $16,000.00. Prior to starting these pumps, all bearings should be thoroughly greased at the pump grease fittings until the old grease is displaced. If the bearings were damaged in any way the grease would not fix the problem. Any bearing problems would become apparent through vibration or noise during operation. The pumps must be completely filled with water and purged of any air. The pump should also be turned several revolutions by hand 21 Technical Memorandum No. 4& 6 February 29, 2001 to help fully fill the pump and to check that the bearings are not completely seized. This work can be completed by City Staff and should have minimal costs. As a component of the Booster Station repair, the operation of the pump control valves installed in 1990 should be closely monitored. It is our understanding that the Booster Station has not been operated since the pump control valves were installed in 1990 and the condition of these valves is unknown. The pump control valves were installed in 1990 to minimize water hammer and protect the aging water system directly down stream from the Booster Station. Prior to the installation of the pump control valves several pipe failures occurred during Booster Station operation. It is critical that these valves operate properly to minimize the potential for pipe failure. 1.7.6 Booster Station Automation/controls: It is recommended that Booster Control Systems Option II be implemented. Under this option, a new PLC based system will be implemented for control and monitoring of the booster station from a remote location. The operator interface as will still be used for control at the booster station. The manual operation of the booster station will still function. 1.7.7 Telemetry Options: We recommend the use of radio telemetry. Radio telemetry will have a higher initial installation cost, however it will eliminate the ongoing monthly phone service fees. In addition to the equipment,there may be an additional cost for a radio path study. 1.7.8 Booster Station Electrical System Line Voltage Service: We recommend the existing main electrical service be replaced. The existtng service is a Federal Pacific Electric 225 amp three phase 600 volt panel. Federal Pacific Electric is no longer in business, and replacement breakers for this equipment can be difficult to locate and expensive. Service Backup Power: We recommend a 150KW generator set be installed. This would provide sufficient power for starting and running all of the Booster Station pumps, provided that the motors were not started simultaneously. Li hg tnin Surge Protection: We recommend a Lightning/Surge Protection system be installed. The probability of a direct lightning strike is low. However, the possibility of voltage surges in the power 22 Technical Memorandum No. 4 & 6 February 29,2001 lines and communication lines resulting from local strikes still exists. For this reason, transient voltage surge suppression should be installed on the incoming power and communications lines. Table 1.7.1 below supplies a summary of estimated costs for the above recommended Booster Station electrical and control system improvements. Table 1.7.1 —Recommended Booster Station Control and Electrical Improvement Costs Description Icost Option H -- Control Systems $36,120 Telemetry-Radio (Assumes No Repeaters Required) $7,360 Pump Replacement $16,000 Line Voltage Service Upgrade $5,520 Service Backup Power $48,300 Lightning Surge Protection $1,040 Total $114,340 23 L- ��Flan Creek I=),zf'�ng Development c—� n a � !F]"11 a� 1`"A, ��� ii ��t CFI +9.1aa d lam N o® lot'.I' *I ` 1w Al 'i � I .� �,, 1, _ • yF tY t f 9 Prepared for: The City of Bozeman 20 East Olive P.O. Box 1230 Bozeman, MT 59771-1230 March 9,2001 (Revision of December 12, 2000) Prepared By: HKM Engineering Inc. 601 Nikles Drive, Suite 2 • Bozeman,Montana 59715 406-586-8834 Lyman Creek Reservoir Improvements Memorandum No. 5 Table of Contents 1.0 Introduction.................................................................................................... ...... 1 1.1 Lyman Creek Spring History..........................................................1 1.2 Lyman Creek Spring Development Histro........................................2 1.3 Lyman Creek Reservoir Source Water Delivery System................................2 2.0 Efficiency of the Lyman Creek Spring Collection Galleries............................3 2.1 Existing Surface Water Diversion Sources................................................. 11 2.2 Augmentation of Spring Box Water with Artesian Well Water................... 12 3.0 Recommendations.............................................................................................. 13 Figures Figure 1 - 8" Pipe Outlet below Spring Box......................................................3 Figure 2 - Spring Collection System...............................................................4 Figure 3 -Existing Spring Collection System Details...........................................5 Figure 4 - Outfall from Spring Box Collection Manhole.......................................7 Figure 5 -Manual Stream Gauging Station.......................................................9 Figure 6 - Automated Stream Gauging Station..................................................10 Figure 7 - Upper Diversion Structure............................................................11 Figure 8 - Lower Diversion Structure............................................. ...............11 Tables Table 1 Lyman Creek Flow.........................................................................2 Table 2 Lyman Creek Source Investigation ......................................................3 Table 3 Optional Stream Gauging Station Costs.................................................8 Lyman Creek AdOitional Spring Development Technical Memorandum No. 5 March 9, 2001 (Revision of December 12,2001) Task 5—Additional Spring Development 1.0 Introduction In the fall of 1999 the City of Bozeman(City)awarded the Lyman Creek Reservoir Improvements Project to IKM Engineering. The project is for the evaluation of alternatives for improvements to Lyman Creek Reservoir,Booster Station, and the long range planning use of the reservoir and pump station. The scope of the project broke the plan into a series of technical memorandums evaluating separate aspects of the project. The primary purpose of this technical memorandum(No. 5)is to provide a summary discussion of improvements required to evaluate and quantify the efficiency of the Lyman Creek Spring collection galleries. In addition this summary will discuss several alternatives for providing additional quantities of drinking water. 1.1 Lyman Creek SpringH istory The unique geologic conditions of the Lyman Creek drainage within the Bridger Range have created the Lyman Creek Spring. The Spring is at or very near the intersection of two major faults known as the Bridger Creek—Bear Canyon fault and the Lyman Creek—Baldy Mountain fault.1 The Bridger Creek—Bear Canyon fault is the Range Front fault that created the western edge of the Bridger Range. The Lyman Creek—Baldy Mountain fault trends parallel to the Lyman Creek drainage and is perpendicular to the Bridger Creek— Bear Canyon fault. Through the course of faulting,highly different rock types were placed next to each other. The first rock type is located on the northwest side of Lyman Creek. It is known as the Madison Limestone and is a much younger rock unit(Paleozoic)which consists of massive light gray to gray limestone. This unit is typically a prolific aquifer since either fractures or solution cavities will readily transmit groundwater. The Lewis and Clark Caverns are an extreme example of the open areas or voids sometimes present in the Madison Limestone. The second rock type is located on the southeast side of Lyman Creek and on the west side of the Bridger Creek—Bear Canyon fault. This unit is known as the Precambrian gneiss. Gneiss is typically a very dense crystalline rock that does not readily transmit groundwater. As a result of faulting, low groundwater transmitting rocks (Precambrian gneiss)were place downgradient of high groundwater transmitting rocks (Madison Limestone). In addition, along major fault planes(like here)the rock is ground up into smaller sizes and can become pasted or cemented together,creating a low groundwater- transmitting zone called"gouge". These differing types of rocks and gouge zones can create ' McMannis(1955) 1 Technical Memorandum No. 5 March 9,2001 a barrier to groundwater flow. As groundwater moves downgradient through the Madison Limestone, it becomes dammed up against the more dense Precambrian gneiss and fault gouge zones. As a result, groundwater rises to the ground surface and"springs"out of the ground. This is the mechanism likely to be causing the Lyman Creek Spring. 1.2 Lyman Creek Springy;Development History In 1986 and 1990 because of more stringent drinking water standards the old system of diverting Lyman Creek surface water that originated from the Lyman Creek Spring into the Lyman Creek Reservoir had to be abandoned. In place of the surface water diversions,two spring collection galleries(boxes)were installed at the point where the Lyman Creek Spring originates. The upper spring box is at approximately 5580 feet elevation and the lower spring box is at approximately 5550 feet elevation. The intent of these collection galleries is to capture the spring water before it flows out of the ground surface;therefore, creating a drinking water source that is not under the influence of the open atmosphere. This essentially converted the Lyman Creek Drinking Water Supply System from surface water into groundwater source. The water rights and estimated flow available from the Lyman Creek Spring source is shown in Table 1 below. Table 1 -- Lyman Creek Flow Flow and Use Data Acre Feet per Million Gallons per Year Gallons per Minute Day Decreed Water Rights 4,310 3.85 2,677 Reliable Flow 1,280 1.14 795 Minimum Observed Flow (1974-1988)1 1,950 1.74 1,211 Maximum Observed Flow (1974-1988)1 13,030 11.65 8,093 Metered Usage (1991-1994) 65 0.06 40 Excess (1991-1994) 1,215 1.09 755 1 Stream flow records recorded by the City of Bozeman using a Parshall flume downstream of spring area. 1.3 Lyman Creek Reservoir Source Water Delivery Systems As mentioned above the Lyman Creek flow is collected by two spring boxes. From the spring boxes,the water flows through approximately 7700 feet of 16-inch ductile iron pipe and 2,400 feet of 18-inch asbestos-cement pipe where it is delivered to the Lyman Creek Reservoir,which is at approximately 5016 feet in elevation. Over this distance, (approximately 10,000 feet)the pipeline drops approximately 530 feet in elevation. To reduce line pressure,two Pressure Reducing Valve(PRV's) stations were installed. Each pressure reducing stations consists of 2 regulating valves that reduce an upstream pressure 2 Technical Memorandum No. 5 March 9,2001 of 100-140 psi to 30-40 psi. The regulating stations reduce the flow capacity of the supply line to approximately 2.7 to 3.8 MGD which approximately matches the decreed water rights of the springs. 2.0 Efficiency of the Lyman Creek Spring Collection Galleries The Lyman Creek spring boxes were installed in 1986(lower) and 1990 (upper). As part of the spring box construction investigation,Lyman Creek stream flows were monitored 2,table 2 provides the results of this monitoring. Table 2 --Lyman Creek Source Investigation Source of Flow (Hydrometrics Nov. 1986) Acre Feet per Million Gallons per Year Gallons per Minute Day Spring Area(upper 300 feet of creek) 1,734 1.55 1,077 Lyman Creek Flow at Upper Diversion 2,528 2.26 1,570 The surface water flow of Lyman Creek originates from an 8"polyethylene drainpipe located at the toe of the filled drainage below the upper spring box. HKM measured this flow on October 18, 2000 and found approximately 150 GPM flowing from the pipe. 4V I 8"Polyethylene Drainpiue r r� i" i t r G� Figure 1 --8" Pipe Outlet below Spring Box 'Hydrometrics 3 CL CJ Q C o Q _ a ,: •X N c p O W acn t m y cr o CD0.I— a '.o .�. N 00 O, C O t!I p. ' p• . Qj o a .. / �ti.' �oQp'p ' o v t�ztn r cl o m cCL X-. �-Ovta G O p u b a - 00 m 1- to /.: :3 550 h: Gp p� u) .: :% p p / o ro (o 00 O a W ¢ WW i0 O w w m U :.�'. w Z ;X o'er O v p tl) J Cfl C N c f� ; �• 0 .O Oa N Aa v = oof O ZW iN+ o o CL O z >Zo as CN c� { 00 6" THICK BENTONITE CLAY SEAL COVERED WITH 6" NATURAL — MATERIALS (SEE NOTE) ..� 9 50 N C OI -SHEET PILE w —I 26 L.F. OF 24 DIA. Y—NATURAL GRAVEL BACKFILL o PERFORATED PIPE FABRIC N 29" RESTRAINE JOINT DIP -*- 0.2% SLOPE b 5CL o (FOR GRADE;=IIII III _ 1 illllli�llll (SEE SHT. 2) — — i1i=IIII (OF 4) IIII 1W RESTRAINED JOINT IIII 1111 CLAMP WITH ALL 5`10 BEYOND END OF PIPE THREAD 24" S8.T DIP x 24" PE PVC 165 PSI BLUE BRUTE Upper Collection Gallery o 7 0 0 6" THICK BENTONITE SEAL COVERED M¢ /-EXISTING GROUND 11-WITH 6 NATURAL MATERIALS crz O d O 0 U W o. o: 0 0 °' O' ��VARIABLE DIST cWn a 12" RESTRAINED � 0 O� '0 ()0 0,� r o —�_ NATURAL GRAVEL x W Cf- H JOINT PIPE �00 F 0.2% 9LbPE 0° 0(_) BACKFILL Y N CD w 9° m Z cu) 4,' ir B 'd1' a U F— FOR Z ( SEE SHT. 2DE rN. L, III=�= I FABRIC ¢RESTRAINEDwOF 4) III=IIII JOINT CLAMP WITH IIII SHEET ALL THREAD 5-10 BEYOND END OF PIPE PILE M 12" SLB DIP x 12" PE PVC CL 150 BLUE BRUTE I N Cl) M # � 0 z W W W Lower Collection ; N W z > Gallery W Z Technical Memorandum No. 5 March 9,2001 Approximately 200 to 250 feet downstream from the 8"pipe outlet the surface flow was again measured and found to be approximately 330 gpm. These measurements were taken between the upper and lower spring boxes;therefore, it is approximated that 330 gpm is bypassing the upper spring box(See Appendix A for flow measurement data). Potentially,this flow could be diverted into the existing lower spring box if a third or middle spring box was constructed in the upper portion of the Lyman Creek channel. This would provide the ability to gravity flow water into the existing spring box collection manhole. The ability to permit the piping, burial, and development of a section of Lyman Creek into a "Spring Box"and creating an additional groundwater collection system that is not influenced by surface water shoud be considered for this option. It is assumed that it would require the construction of a spring box similar to the existing two collection boxes that effectively isolate the flow from contact with the atmosphere. To determine the efficiency of the existing Spring Boxes and the reliable flow from the Spring Boxes,the flow at all discharge points must be measured. Currently there are three discharge points from the system. 1)Lyman Creek Reservoir via the pipeline This is the flow collected by the Spring Boxes and conveyed down the pipeline into the reservoir. An electric control valve at the reservoir controls this flow. There is an existing old style chart recorder in the reservoir control house that could potentially measure this flow. However,the accuracy of this recorder is suspect. 2) Spring Collection Manhole bypass During low demand periods a portion of the Spring Boxes flow bypasses from the Spring collection manhole back into Lyman Creek(see Figure 4). Approximately 100 gpm was estimated to be flowing from this bypass on October 20, 2000. Currently there is no measurement device on the bypass and it is not possible to make accurate measurements of flow from this bypass. It is understood that this bypass typically does not flow if there is a demand on the pipeline to the Reservoir. On October 20, 2000 when flow measurements were taken at the spring boxes and collection manhole the control valve at Lyman Creek Reservoir was set at approximately 500 GPM. It is anticipated that at a 20-year build-out of the North and Northwest zones an average day demand of 1 MGD will be placed on Lyman Creek Reservoir. This equates to a continual 700 GPM flow from Spring Boxes. This additional demand of 200 GPM is anticipated to utilize and eliminate the manhole bypass flow. 6 Technical Memorandum No. 5 March 9,2001 3) Lyman Creek surface water flow upgradient of the Lower Spring Box. Potentially, this flow of 330 GPM(as measured 10/20/00) could be captured and diverted into the Lower Spring Box. Currently there is no measuring device on this portion of the creek and it is not possible to make accurate measurements of flow from this portion of Lyman Creek. It is not known if this flow stays constant or decreases in response to demand on the pipeline. -+-- rv '�� CMP Bypass Pipe Figure 4 -- Outfall from Spring Box Collection Manhole To measure the combined flow from the manhole bypass and the section of Lyman Creek above the Lower Spring box a stream gauging station should be constructed down stream of where the manhole bypass water enters Lyman Creek. This gauging station can be constructed for either manual or automated monitoring. For manual measurements a 6"Parshall flume with a staff gauge should be installed. This flume is capable of recording between 0.6 and 5245 gpm and has a relatively wide throat (6),which will allow for passage of debris. (See Figure 5.) Typically these flumes are equipped with a wet well for automatic water level measuring equipment such as a pressure transducer,ultrasonic flow logger, or float measuring equipment connected to a data logger. This equipment could be installed at all locations, (new gauging station,Upper Lyman Creek Diversion, and Lower Lyman Creek Diversion)to monitor flow during the non- freezing months of the year. This would eliminate the need for frequent site visits for 5 to 6 months of the year. But,would not be operable during the winter months because ice and cold temperatures would freeze up the equipment and make flow measurements inaccurate. To make the automatic flow measuring equipment operable during freezing conditions the stream flow and equipment must be placed in a frost proof environment or structure. This structure would consist of a 36"diameter concrete pipe placed horizontally and parallel to the stream bottom. The pipe would then be covered with approximately eight feet of material that would dam up the stream and divert it through the pipe. Over the center of the pipe, an insulated manhole would be installed to allow access to the pipeline, and provide a 7 Technical Memorandum No. 5 March 9,2001 position to install the automatic flow monitoring equipment. With a burial depth of approximately 8 feet,the pipeline and flow monitoring equipment will be in a frost proof environment. (See Figure 6.) The automatic flow monitoring equipment recommended for flow measurments during the non-freezing months of the year consists of a battery powered data logger capable of collecting over 1 year of data without switching out the batteries or transferring the data. The data logger would be connected to a submerged probe flow sensor, which will measure the height of a column of water(0.1 to 5.0 feet deep). (See Appendix B ISCO Model 4120 .) The cost to install either a manual or automatic stream gauging station is summarized in Table 3. The automatic flow monitoring equipment recommended for the frost proof structure consists of a battery powered data logger capable of collecting over 1 year of data without switching out the batteries or transferring the data. The data logger would be connected to a velocity flow sensor,which will measure the height of a column of water (0.1 to 5.0 feet deep) and the average velocity throughout the flow stream. (See Appendix B ISCO Model 4150.) The cost to install either a manual or automatic stream gauging station is summarized in Table 3. Detailed cost estimates are shown in Appendix C. Table 3—Optional Stream Gauging Station Costs Description Cost Manual Station 6" Throat Parshall Flume $ 1,200 Parshall Flume Installation $ 4,160 Total $ 5,360 Manual Station with SEASONAL Automatic Flow Monitoring Equipment 6" Throat Parshall Flume $ 1,200 Parshall Flume Installation $4,680 Automatic Flow Monitoring Equipment (cost per unit) $ 3,505 Total $9,385 Automatic YEAR ROUND Gauging Station Pipeline, Debris Racks, 8' High Dam, Manhole Construction etc. $ 23,430 Automatic Flow Monitoring Equipment $ 4,405 Total $ 27,835 Stream flow data, (manually or automatically collected)in conjunction with the pipeline flow data can be used to determine the reliable yield for the currently Spring Box configuration, and if additional spring box development is warranted. 8 a m L I U C I", m J ( o c rn J c I'. Y ¢ ¢ I a a_ v 1:: � I ' t O v C o U- I:.. ro Q © wa. J CL ---------- ::\LAJ Z ¢ OWC Z zLi H- oa 0) g °° Q z z a � z o� o� 'z 00 ¢ o z .: > � o Wz ac ¢LLJ g I ¢ irw w m w m U) cc l � a t , z I z Z (' cn i` w I' r ( I N ( LCN I $k 0o I W ( � W � U I NIL Q Z w I " W w z ( I i v i m n (n 1 t w d 4 0 � b ` � p o < v I ww © Q Om IL a .1 cc w 02 UJ LLJ a o I ,Lil j' a z O � W 0 O© 0 it l l��� lO 11- ��' ITL .� z 1'�+ O w z 1 w aL�Ic ij 4 O M �l� �t Lr I �-� a Cl) a. I I I 1= = _ �I t9� I It � i - co LLJ J 1 Q Q U LJ V) Z o i .,• r 1 o �;lj d z - _ �-i�`j r�? I -i m Z ,ijIll J z 4 O O - �lri I�i�I,ll r� � w Q Q _ d V Z F- it IX x 1- fOP7, I 1� W C�3 OO H Z L a ICI it Wcc uj � d 7I All, O (Yh1 111� Y � w �� a � wm O r tI , I [ 1IT- Q: w ? p U Ct d O Yti. 11�1.0 Q 1- Z d W < Q XC� m 11. d O Z d — , to CLx � m 00 a UJI dW (n © �� cw 00 # o 0 LL w m � i Z U W LLL1� W Technical Memorandum No. 5 March 9.2001 2.1 Existing Surface Water Diversion Sources There are two existing stream diversion structures along Lyman Creek that were originally used to divert surface water into the reservoir pipeline. The conversion from surface to ground water required these structures be physically disconnected from the pipeline. Continual monitoring of Lyman Creek flow could be performed at these existing diversion structures. Both locations have flow measuring equipment that could be measured by hand, or augmented with automated equipment. The same equipment as discussed above is recommended for automatic flow measurements at these locations. Flow measurements during the winter and freezing temperatures would be difficult,but could still be done if properly constructed frost proof systems were installed. ;f. f c 'I a Figure 7 -- Upper Diversion Structure �5 I Figure S—Lower Diversion Structure 11 Technical Memorandum No. 5 March 9,2001 While not measured,there is a significant quantity of water flowing through both of the surface water diversions. By developing either of these surface water diversions or a new surface water diversion in combination with the spring water,the reliable yield for the combined sources would significantly increase. However,this would return the Lyman Creek Public Drinking Water System to a surface water source, and the treatment facility at the Reservoir would need to be converted for treating surface water. In addition, Lyman Creek stream flow could not be gravity fed into the existing pipeline since the pipeline is under pressure from the spring box system. To utilize the existing pipeline, surface water from the upper diversion structure would need to be piped and connected downstream of the upper PRV at a point where the hydraulic grade lines matched. As an alternative, a series of drop boxes could be installed in the existing pipeline between the collection manhole and the upper diversion structure to maintain atmospheric pressure on the pipeline. This however may cause an air entrainment problem that may adversely affect the ability to treat the water. Surface water from the lower diversion structure could not use the same pipeline as the upper water sources because of the pressure gradient differences. To utilize the Lower Diversion surface water an additional pipeline and/or pump station would need to be installed. 2.2 Augmentation of Spring Box Water with Artesian Well Water The hydrogeologic setting of the Lyman Creek Spring may permit the possible development of a well or series of wells that would provide additional quantities of groundwater to Lyman Creek Reservoir. The key to the development of additional wells will be to provide artesian type wells that will supply adequate pressure(or head)to deliver groundwater into the existing spring collection manhole. To physically pump the water may not be an economic option because power is not readily available at the Spring Boxes and would have to be brought in from several thousand feet away. A well or wells could be drilled further down slope from the Spring Box area granted they have adequate artisan pressure to outfall into the Spring Box manhole, The additional well water would also have to prove that the source(well groundwater)is not under the influence of surface water. Detailed geologic investigations of the site would be required so that the well(s)would be properly oriented. Ideally,the well would intersect groundwater at a depth(100'to 300') and that the groundwater would be under enough pressure(head)to cause the well to flow, (artesian well). In addition it may be possible to install an underground barrier or dam that would stop or reduce the loss of groundwater from the Lyman Creek Spring source area. This is done by installing a series of wells in a row, semicircle, or whatever linear arrangement necessary to intersect groundwater flow. Once these wells are installed,then a grout(many options)is pumped through the wells and into the surrounding ground. Eventually, if the grouting program is successful,the grout from each well intersects the neighboring well and a continuos grout curtain is created. This system could enhance the Spring Box flow and artesian supply wells if successful. Typically, very detailed geologic information,which 12 Technical Memorandum No. 5 March 9,2001 requires many test wells is required to determine weather or not a grouting program is even feasible. 3.0 Recommendations To determine the efficiency and reliable yield of the Lyman Creek source area spring boxes, additional flow monitoring is needed. Primarily, the stream flow of Lyman Creek downstream of the spring box collection manhole needs to be monitored. Installing either a manual Parshall flume or automatic gauging station in Lyman Creek can do this. This equipment(flume and flow monitoring equipment)will need to be designed and constructed to work in freezing temperatures if year round monitoring is needed. Due to the frequency of stream flow monitoring, the man hours involved in collecting the data by hand, safety issues, and data integrity, it is recommended that a frost proof stream gauging station with automatic flow monitoring equipment be installed. This structure should be installed immediately downstream of the Spring Box Collection Manhole. During low flow periods, (January through March) flow measurements should be taken on a daily basis to determine what the reliable flow is on a worst case basis. By utilizing automatic monitoring equipment, much higher monitoring frequencies can be programmed, which do not require daily site visits by City Staff. This in turn will reduce City manpower costs, eliminate safety concerns of sending personnel to the site during winter conditions and provide higher quality data. As shown in Table 3, the cost to install a frost proof automated stream gauging station to monitor the Spring Box efficiency is approximately $ 27,835.00 13