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Home My WebLink About98 - Master Plan - Wastewater Facility Plan 1 WMTEWATTER.... N = �lrirw CVYiGv.JCY.-.f BozEMAN, MONTANA AUGUST 1998 1 1 - " ENGINEERING 1 BOZEMAN WASTEWATER FACILITY PLAN TABLE OF CONTENTS PAGE 1.0 EXECUTIVE SUMMARY ................................................................... ........ 1 2.0 INTRODUCTION..................................................................................... 10 2.1 GENERAL .................................................................................... 10 2.2 SCOPE OF WORK .......................................................................... 10 3.0 PLANNING AREA ................................................................................... 12 4.0 EXISTING CONDITIONS........................................................................... 14 4.1 POPULATION ............................................................................... 14 4.2- ZONING AND POPULATION DENSITY ............................................. 15 4.3 WASTEWATER FLOWS AND LOADS................................................ 17 4.4 WASTEWATER COLLECTION SYSTEM............................................. 21 4.4.1 System Description.................................................................. 21 4.5 INFILTRATION AND INFLOW......................................................... 24 4.5.1 General................................................................................ 24 4.5.2 System-Wide Analysis................................................................ 25 4.5.2.1 Dry Weather Flows ....................................................... 25 4.5.2.2 Wet Weather Flows....................................................... 31 4.5.3 Drainage Area Analysis ............................................................ 40 4.5.4 Groundwater Infiltration............................................................ 42 4.5.5 Rainfall-Dependent Inflow/Infiltration........................................... 44 4.6 HYDRAULIC ANALYSIS OF EXISTING COLLECTION SYSTEM ............ 50 4.6.1 General................................................................................ 50 4.6.2 Analysis Results ..................................................................... 52 4.6.3 Physical Condition .................................................................. 58 4.7 WASTEWATER TREATMENT SYSTEM ............................................. 61 4.7.1 Existing Effluent Quality........................................................... 61 4.7.2 Plant Description .................................................................... 61 4.7.3 Treatment Plant Evaluation ........................................................ 64 4.7.4 Sludge Disposal Requirements .................................................... 80 - i - TABLE OF CONTENTS (Continued) Page 5.0 FUTURE CONDITIONS............................................................................. 88 5.1 POPULATION PROJECTIONS........................................................... 88 5.2 WASTEWATER FLOW AND LOAD PROJECTIONS .............................. 89 5.3 DRAINAGE AREAS WITHIN 20 YEAR PLANNING AREA ..................... 92 5.4 WASTEWATER COLLECTION SYSTEM.................................. . 94 5.4.1 Improvements Required for Expansion ................... 94 5.4.2 Existing System Improvements................................................... 114 5.5 FUTURE WASTEWATER TREATMENT SYSTEM IMPROVEMENT NEEDS ....................................................... 118 6.0 RECOMMENDATIONS ............................................................................ 124 6.1 INTRODUCTION........................................................................... 124 6.2 COLLECTION SYSTEM.................................................................. 124 6.2.1 Infiltration and Inflow ............................................................. 124 6.2.2 Collection System Improvements................................................ 127 6.3 WASTEWATER TREATMENT PLANT IMPROVEMENTS ..................... 133 6.4 PROJECT SCHEDULING ................................................................ 134 REFERENCES ................................................................................................. 136 - ii - TABLE OF CONTENTS (Continued) Page LIST OF TABLES 1.0-1 Summary-Zone Characteristics at Full Development ..................................... 8 1.0-2 Recommended Collection System Improvements to Correct Existing Deficiencies..9 1.0-3 Recommended Improvements at the Wastewater Treatment Plant......................9 4.1-1 Population Trends ............................................................................ 14 4.2-1 Residential Zoning Densities........................ 4.3.1-1 Average Monthly Flow (MGD) ............................................................ 17 4.3.1-2 Influent Organic Loading.................................................................... 20 4.3.1-3 Influent BOD5 Concentrations (MG/L).................................................... 21 4.4.1-1 Characteristics of Drainage Zones ......................................................... 23 4.5.2-1 Rainfall Dependent I/I Flow Components ................................................ 34 4.5.2-2 Volumes of Flow Components During Storm Events................................... 39 4.5.2-3 Summary of Dry and Wet Weather Flows (MGD) ..................................... 40 4.5.4-1 Groundwater Infiltration (GWI) ........................................................... 4.5.5-1 Rainfall Dependent Infiltration/Inflow Observed During Storms . ................... 44 4.5.5-2 Rainfall Dependent Infiltration/Inflow from July 3 and 4, 1993 ...................... 46 4.6.1-1 Model Input Zoning Characteristics ....................................................... 51 4.6.2-1 Zone 1 Existing System Model Characteristics .......................................... 52 4.6.2-2 Zone 2 Existing System Model Characteristics .......................................... 53 4.6.2-3 Zone 3 Existing System Model Characteristics .......................................... 54 4.6.2-4 Zone 4 Existing System Model Characteristics .......................................... 55 4.6.2-5 Zone 5 Existing System Model Characteristics .......................................... 56 4.6.2-6 Zone 6 Existing System Model Characteristics .......................................... 57 4.6.3-1 Lines Requiring Routine Maintenance..................................................... 60 4.7.1-1 Plant Effluent Quality ....................................................................... 61 4.7.2-1 Existing Plant Design Criteria and Existing Conditions ................................ 62 4.7.3-1 Capacities and Condition of Treatment Plant Components............................. 66 4.7.3-2 Permissible Versus Actual Loading on the Aeration Basins ........................... 71 4.7.4-1 Ceiling Concentrations for Sludge Disposal.............................................. 82 4.7.4-2 Cumulative and Annual Sludge Pollutant Loading Rates............................... 83 5.2-1 Projected Flows and Loads (Year 2014).................................................. 91 5.4.1-1 Zone 1 Estimated Improvement Costs..................................................... 97 5.4.1-2 Zone 2 Estimated Improvement Costs..................................................... 99 5.4.1-4 Zone 4 Estimated Improvement Costs.................................................... 104 5.4.1-5 Zone 5 Estimated Improvement Costs.................................................... 107 5.4.1-6 Zone 6 Estimated Improvement Costs.................................................... 109 5.4.1-7 Zone 7 Estimated Improvement Costs.................................................... Ill 5.4.1-8 Zone 8 Estimated Improvement Costs.................................................... 113 5.4.1-9 Summary Zone Characteristics at Full Development .................................. 113 6.1-1 Recommended Priority for TV Inspection............................................... 126 6.1-2 I/1 Related Treatment and Transportation Costs ........................................ 127 6.2-1 Recommended Collection System Improvements to Correct Existing Deficiencies ......................................................................... 128 - iii - TABLE OF CONTENTS (Continued) Page 6.2-2 Recommended Collection System Improvements for Future Development........................................................................ 129 6.4-1 Prioritized System Improvements ......................................................... 135 - iv - TABLE OF CONTENTS (Continued) Page LIST OF FIGURES 3.0-1 Planning Area Boundaries................................................................... 13 4.2-1 City Zoning Boundaries...................................................................... 18 4.5.2-1 Seasonal Flow Variation..................................................................... 26 4.5.2-2 Summer Dry Weather Hydrograph ........................................................ 29 4.5.2-3 Winter Dry Weather Hydrograph.......................................................... 30 4.5.2-4 WWTP Flow and Precipitation Data...................................................... 32 4.5.2-5 Precipitation and Wastewater Flows (June 6-13, 1993) ................................ 35 4.5.2-6 Precipitation and Wastewater Flows (June 13-20, 1993)............................... 36 4.5.2-7 Precipitation and Wastewater Flows (June 20-27, 1993)............................... 37 4.5.2-8 Precipitation and Wastewater Flows (July 3-10, 1993)................................. 38 4.5.5-1 Flow in 15-inch Main at Durston/17th.................................................... 47 4.5.5-2 Flow in 15-inch Main at Durston/18th.................................................... 48 4.5.5-3 Flow in 15-inch Main at Durston/16th.................................................... 49 4.7.2-1 Process Flow Schematic..................................................................... 63 4.7.3.1 Bozeman Wastewater Plant Component Capacities ..................................... 69 5.1-1 City of Bozeman Projected Population.................................................... 90 5.4.1-1 Zone 1 - Drainage Area Improvements ................................................... 95 5.4.1-2 Zone 2 - Drainage Area Improvements .................................................. 100 5.4.1-3 Zone 3 - Drainage Area Improvements .................................................. 102 5.4.1-4 Zone 4 - Drainage Area Improvements .................................................. 105 5.4.1-5 Zone 5 - Drainage Area Improvements .................................................. 106 5.4.1-6 Zone 6 - Drainage Area Improvements ................................................._ 108 5.4.1-7 Zone 7 - Drainage Area Improvements .................................................. 110 5.4.1-8 Zone 8 - Drainage Area Improvements .................................................. 112 LIST OF APPENDICES A Census Data and Population Density B Montana Pollutant Discharge Elimination System Permit C Flow Monitoring Data D Comprehensive Performance Evaluations, 1987 and 1994 E Data for I/I Model Input Data F EPA 503 Sludge Regulation Information G Model Results LIST OF PLATES 4.4.1-1 Existing Wastewater Collection System 5.3-1 Drainage Areas and Future Improvement Within Planning Area - v - LIST OF ABBREVIATIONS BG - block groups related to census data BNA - Block numbering areas for census data BOD5 - 5 day biochemical oxygen demand BTU - British thermal units D.U. - dwelling unit EPA - Environmental Protection Agency F/M - food to microorganism ratio gpd/in. dia.-mile - gallons per day per inch diameter mile GPD - gallons per day gpm - gallons per minute GW - groundwater GWI - groundwater infiltration I/P - infiltration/percolation I/I - infiltration and inflow mg/kg - milligrams per kilogram mg/l - milligrams per liter MG - million gallons MGD - million gallons per day MH - manhole MLSS - mixed liquor suspended solids MPDES - Montana Pollutant Discharge Elimination System MPN - most probable number N. - north psig - pounds per square inch gage pressure PFRP - process to further reduce pathogens PSRP - process to significantly reduce pathogens PVC - polyvinyl chloride pipe RDI - rainfall dependent infiltration RDI/I - rainfall dependent inflow and infiltration SUM standard cubic feet per minute SWI - stormwater inflow TKN - total kjeldahl nitrogen TSS - total suspended solids VSS - volatile suspended solids WQB - Water Quality Bureau WWTP - wastewater treatment plant - vi - 1.0 EXECUTIVE SUMMARY The wastewater collection and treatment system for Bozeman currently serves a population of approximately 22,660 persons (1990 census). With population growth and expansion of the service area, the population within the 20-year planning period is projected to be 32,551 persons in the year 2014. The existing collection system consists of approximately 98 miles of gravity sewer line, ranging in size from 6-inch to 30-inch. The original collection system was constructed in the early 1900's. Many of the old lines are still in service. Infiltration and inflow (I/I) into the collection system is a major problem that is contributing a substantial load on the collection and treatment system. In 1993 the average daily flow at the wastewater treatment plant was 5.03 million gallons per day (MGD). For a population of 22,660 persons, the expected flow would be in the range of 2.3 to 2.7 MGD. During rainfall and snowmelt events, the flows increase dramatically when compared to winter time dry weather flows. These flow increases affect available capacity of the collection system and the hydraulic functions of the wastewater treatment plant. During dry weather conditions, the flow from groundwater infiltration ranges from 1.67 MGD during the winter to 3.32 MGD during the summer. Substantial flow increases can also be observed during wet weather conditions. Following a heavy rainfall on July 3-4, 1993 the average daily flow increased to 8.68 MGD. During wet weather conditions it is estimated that infiltration and inflow constitutes approximately 62 to 74 percent of the total flow. From the data collected, it is also apparent that infiltration constitutes a larger portion of the I/I than inflow. The low stormwater inflow volumes indicate that direct connections of roof drains, area drains, or cross connections with storm sewer lines are not a major problem. The following areas were identified as having excessive amounts of groundwater infiltration. - 1 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM • Stream crossing on North Rouse Ave., South of Peach • Area southwest of manhole at Garfield and Bozeman Avenue • Area draining into 8-inch main on Babcock, between 15th and 19th Avenues • MSU campus; extension to married student housing on 15th south of Koch Street • Stream crossing at Dell Place A television inspection of the sewer lines in these areas should be done to verify the type and extent of the infiltration sources. Once the exact nature of the cause of the leakage is determined, the most cost effective method of repair can be determined. A total of 68,320 feet of line has been identified as a recommended priority for television inspection. The cost to conduct the TV inspection is estimated to be$88,820.00. In order to provide sewer service to an expanded service area, several new sewer collectors and interceptor lines were sized and located within the planning area. Plate 5.3-1 bound in the back of the report shows the layout for the recommended lines. Lines were sized to serve the expanded service area based on an overall equivalent population density of 12.6 persons per acre and a flow of 72 gallons per capita per day. The equivalent population density includes an allowance of 4.8 persons per acre for commercial and industrial flows. A hydraulic analysis of the existing collection system was completed to identify lines with inadequate capacity for the existing or future flows. The existing collection system was divided into 6 drainage zones. Two additional drainage zones (7&8) were analyzed for future expansion of the collection system to the northwest and the north. The evaluation of each drainage zone is summarized below. Plate 5.3-1, bound in the back of this report, shows the drainage areas. - 2 - \\HKM\PROJEC RDATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM ZONE 1 At current flows, all pipes in this drainage zone have adequate capacity. However, there are several lines that are running at 75 to 90 percent of capacity. As growth occurs east of the City, the existing 14-inch line that ties into the trunk line on North Rouse at Tamarack will have to be replaced with a 24-inch line. In addition, the capacity of the existing lift station, in the vicinity of the east interstate exit, will be exceeded as growth occurs to the east. The long range masterplan will eliminate the lift station by constructing a new trunk line on the north side of the interstate. The cost of improvements required for Zone 1 at full development is estimated at $4,482,000. ZONE 2 Currently, Zone 2 consists primarily of the Valley Unit Subdivision. At the existing level of development, the majority of lines are flowing at less than 50 percent of capacity. In the master plan, Zone 2 is expanded significantly and will comprise the majority of land south of US 191 and west of South 19th in addition to land northeast of the Valley Unit Subdivision. There is significant construction activity currently in the Zone 2 area near the Valley Unit Subdivision. There has also been interest shown in developing land west of Ferguson Road and connecting to the Far West trunk. In the master plan developed in this report, the land west of Ferguson Road will eventually be included in Zone 7 which will be served by a new trunk line running in Davis Lane. However, until the new trunk line for Zone 7 is constructed, the land in Zone 7 west of Ferguson Road will be served by the Far West trunk line. When completed, the improvements for Zone 2 are estimated to cost $7,618,000. - 3 - \\H KM\PROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM ZONE 3 Zone 3 is a fairly large zone that drains the west side of the city. The area drains into a collector line on Durston Road. The 15-inch and 18-inch collector on Durston is currently undersized and will surcharge at peak hour flows. Additional "fill-in" growth within Zone 3 will increase the possibility of surcharging the collector line. In order to alleviate the surcharged condition, the master plan recommends diverting flow from Zone 3 into Zone 2. Flow would be diverted from the 12-inch "Main Mall Line" at Durston into the 20-inch "Far West Trunk". The cost of the diversion line is estimated at $175,000 and is included in the zone 2 improvement costs. Flow monitoring indicates groundwater infiltration in Zone 3 is approximately 320 gallons per minute during the summer. This is a significant flow and additional TV inspections should be completed to isolate the problem areas. ZONE 4 The drainage lines have adequate capacity at the existing and projected peak hour flows with the exception of a short segment of 12-inch line and a short segment of 30-inch line. The 12-inch line from the intersection of Hoffman Drive and Tracey Avenue to South Willson appears to be at approximately 90 percent of capacity at peak hour flows. In the master plan, the 12-inch line would, be replaced with a 15-inch line. The estimated cost of replacing the 12-inch line is $124,000. The trunk line that flows through Zone 4 carries flows from Zones 2, 3, and Zone 4. Flow from Zone 7 will also flow into the existing 30-inch trunk line near the interstate. At full development of Zones 2, 3, 4 and 7 the 30-inch line will need to be replaced with a 36-inch line. Many of the lines in zone 4 were installed in the early 1900's and are clay tile lines. The lines require frequent cleaning due to plugging and solids deposition. It is recommended that all lines in - 4 - 1U1 KM\P R O J E C T\D A TA\061M 2291241C M C 03717.D O C 08/16/98 @ 10:17 AM zone 4 be inspected with a TV camera to further isolate problem areas and to identify possible areas of infiltration. ZONE 5 Zone 5 is currently a rather small zone that drains the area along South Church. The area appears to have a substantial amount of groundwater infiltration. Flow monitoring at Cottonwood and Church and Cottonwood and Rouse indicate groundwater infiltration of approximately 185 gallons per minute. The major source of infiltration appears to come from a line identified as being repaired during the 1980;s as part of the EPA rehabilitation program. It is suspected that the grout used in the repair has deteriorated to the point it is no longer effective. The 8-inch line that flows through Bogert Park to Lamme Street (manhole E0506 to manhole F0439) is undersized for the current flows. As discussed below, the line could be replaced as part of new trunk line which would serve the area south of the City. In the master plan, Zone 5 would be expanded to include 4,057 acres south of the_existing city limits. Flows from future growth in this area would require the construction of 21-inch and 24-inch trunk lines flowing to the north. Two potential routes have been identified for the trunk line. One route would follow the line along North Rouse and the existing sewer alignment through Bogert Park. The alternative alignment would follow Sourdough Road. The exact routing for the 21-inch and 24-inch trunk line will require a detailed survey and cost analysis to determine the most cost effective route. Deep excavations along the Sourdough Road and high groundwater conditions along Bozeman Creek could significantly effect the cost for the trunk line. The cost of Zone 5 improvements is estimated to be$6,318,000.00. - 5 - \\H KM\P R OJ E CT\DATA\06\M229124\CMC03717.D OC 08/16/98 @ 10:17 AM ZONE 6 The majority of lines in this drainage zone are adequate at current flow rates. The hydraulic model indicates that a small section of 20-inch main on North Rouse between Birch Street and the interstate overpass will surcharge during peak hour flows. However, it is also estimated that the 20-inch main on North Rouse is carrying approximately 400 gpm of infiltration. It is recommended the City make a concerted effort to reduce the I/'I in this zone before replacing the line segment. The capacity of the outfall line from Zone 6 is limited by the single 20-inch line that begins at Manley Road and continues to a tie with a 30-inch line. The capacity of the 20-inch line is 5.69 MGD while the estimated current peak flow is 5.96 MGD. The Zone 6 outfall line will also collect flows from Zones 1 and 5. As flows from these zones increase, the capacity of the existing 20-inch trunk line on North Rouse will be exceeded. The master plan recommends a 33-inch line on North Rouse. From North Rouse the outfall line drains to the west to the treatment plant. The outfall line consists of 20-inch and 30-inch lines. At current peak hour flow rates, the outfall line is at approximately 60 percent of capacity. When the line capacity is reached, the outfall line should be replaced with a 42-inch diameter line. The cost of improvements requires to serve all of Zone 6 is estimated to be $3,896,000. Zone 6 also has several lines that require routine maintenance due to solids deposition or plugging. The problem lines are primarily old 6-inch lines that were installed in the early 1900's. The majority of the Zone 6 lines are also in an area identified by the City crews as an area where root intrusion is a problem. TV inspections should be completed on the Zone 6 lines to further identify where root growth and possible infiltration is occurring. - 6 - \\HKM\P R OJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM ZONE 7 Zone 7 consists of the drainage area on the western edge of the service area north of US 191. Zone 7 will serve an area that currently does not have sewer service. Initially, Zone 7 will drain into the "Far West Trunk" north of Durston at Oak Street extended. As the "Far West Trunk" reaches capacity, the Zone 7 trunk line down Davis Lane will be required. The estimated cost to construct the main sewer lines in Zone 7 is $2,339,000. TREATMENT PLANT The evaluation of the wastewater treatment plant showed that all the components have adequate capacity. With the recent expansion of the sludge storage basins, the immediate need at the treatment plant is the replacement of the aging sludge injection equipment. The replacement cost for a new injection truck is estimated at $185,000. The purchase of a new 6000-gallon nurse truck is also recommended at an estimated cost of$110,000. The operators ability to monitor the sludge process is also limited by the lack of flow meters on the plant sludge lines: It is recommended that flow meters be installed at the following locations: • Sludge line from gravity thickener to the digester • Sludge line from the flotation thickener to the digester • Sludge line from the digester to the storage basin. The heat exchanger used to heat the digesters is approximately 24 years old and does not appear to be functioning efficiently. Scale deposits on the heat exchanger tubes may be limiting the heat transfer capacity of the exchanger. Parts for the exchanger are no longer available. The city should include the replacement of the exchanger in the plant budget. The estimated cost to replace the heat exchanger is $10,000 to $15,000. - 7 - \\H KM\P R OJ ECT\DATA\06\M229124\C MC03717.D O C 08/16/98 @ 10:17 AM The high infiltration volumes in the Bozeman system add a substantial hydraulic load on the wastewater plant. During peak I/I conditions the existing bar screens are at capacity, and the primary and secondary clarifiers are near the maximum recommended overflow rates. In spite of the high I/I flows, the treatment plant has consistently provided a high level of treatment, with effluent concentrations well below the limits of the discharge permit. SUMMARY Table 1.0-1 summarizes the cost of improvements for each drainage zone that will be required to expand the zones for future development outside the existing service area. The costs shown represent the estimated current cost to install the major collector and trunk lines. The flow shown represents the flow expected when each zone is fully developed. Since it is not expected that each zone will be fully developed within the planning period of this study, the total average day flow of 22.23 MGD exceeds the projected average day flow of 5.64 MGD in the year 2014. However, as the major collector and trunk lines can be expected to last 75 to 100 years it is prudent to size the lines for the maximum expected growth within each drainage zone. TABLE 1.0-1 SUMMARY-ZONE CHARACTERISTICS AT FULL DEVELOPMENT ZONE A TOTAL AREA AVERAGE DAY PEAK HOUR ESTIMATED ESTIMATED COST OF SERVED ACRES FLOW-MGD FLOW-MGD III FLOW-MGD IMPROVEMENTS 1 3,067 3.78 9.86 0.372 $4,482,000.00 2 5,210 4.84 5.96 0.769 $7,618,000.00 3 1,070 0.77 1.92 0.239 $ 0.00 4 1,842 2.04 2.74 0.407 $ 224,000.00 5 4,351 4.86 9.75 0.898 $6,318,000.00 6 3,535 3.21 5.87 0.81 $3,896,000.00 7 1,856 2.70 9.99 0.278 $2,339,000.00 8 764 0.81 2.16 0.177 $ 974,000.00 TOTAL 21,695 23.01 37.52'' 3.95 $25,851,000.00 1. The 37.52 MGD represents the peak hour flow for the entire system. The projected peak hour flows for the individual zones will not equal the total system peak hour flow because a different peaking factor is applied to the individual zones when they are considered as a separate system. - 8 - H:\DATA\06 W I229124\C M C 03717.D O C 08/20/98 @ 11:41 AM Table 1.0-2 shows the improvements proposed to correct deficiencies within the existing collection system. TABLE 1.0-2 RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS TO CORRECT EXISTING DEFICIENCIES LINE ZONE SIZE LENGTH TOTAL PRIORITY DESIGNATION NUMBER DESCRIPTION INCHES FT COST$ 1 W1 2 Diversion of flow at 15 2500 $175,000 manhole J0410 to Zone 2 2 W3 4 Intersection of Hoffman & 15 1,150 $124,000 Tracy to S. Willson 3 A8 5 Rouse from Tamarack to 24 8,000 1,139,000 Ice Pond Road 4 E8 I Tamarack St. from N. 21 &24 4,700 $468,000 Rouse to Front and Front St. to Lamme St. extended TOTAL $1.906,000 *Table does not include areas or lines that may be identified through the TV ins tion (Table 6.1-1 as needing repair). Table 1.0-3 lists the recommended improvements and projected costs for the wastewater treatment plant. TABLE 1.0-3 RECOMMENDED IMPROVEMENTS AT THE WASTEWATER TREATMENT PLANT DESCRIPTION ESTIMATED COST New Sludge Injection Truck $185,000 New 6000 gallon Sludge Transport Truck $110,000 Sludge Metering Equipment $15,000 Replace the Digester Heat Exchanger $15,000 TOTAL $325,000 - 9 - H:\DATA\06\M229124\C MC03717.DOC 08/20/98 @ 11:43 AM R .i w, r r; 2.0 INTRODUCTION 2. 1 GENERAL Bozeman is an incorporated city located in the central part of Gallatin County. The 1990 census reported a population of 22,660 persons. Currently, the city is experiencing development pressure with several subdivisions being planned in the area. Recognizing the need to evaluate its existing water and wastewater system and plan for future growth,, the city retained HKM Associates in November 1993 to prepare a water and wastewater master plan. This report contains the wastewater master plan. The water system master plan is published in a separate document. 2.2 SCOPE OF WORK The scope of this master plan includes the following: • Develop a future sewer service area • Define drainage basins within the existing and future service area • For the drainage basins delineated, identify the general location, loading, and sizing for interceptors, collectors, and relief sewer • Review wastewater flows and storm data to determine the severity of infiltration and inflow in the system • Develop a computer model of the collection system based on line length and slope data provided by the city • Identify hydraulic deficiencies for the design flows • Identify capital improvements needed to correct deficiencies in the existing service area and to expand the collection system into the future service area - 10 - \\HKM\PROJ ECT\DATA\061M229124\CMC03717.DOC 08/16/98 @ 10:17 AM • Prepare cost estimates for recommended improvements and expansions • Conduct flow monitoring on subdrainages Review wastewater treatment system components • Review the sludge holding and disposal methods - 11 - \\HKM\PROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 3.0 PLANNING AREA Figure 3.0-1 shows the three areas used in preparing the Master Plan update for the Bozeman municipal water and wastewater facilities. These areas are: • Current city limits • 20-Year Planning Area, and • Study Area Boundary The delineation of these areas was determined on February 20, 1994 by representatives of the Assistant City Manager, Director of Public Works, City engineer and engineering staff, representatives from all the public works departments of the City of Bozeman, and engineers from HKM Associates. Within the 20-year planning area specific drainage zones have been identified, lines have been sized, and construction costs have been identified. The larger study area boundary identifies the future populations and general drainage patterns for areas outside the 20-year planning boundary. - 12 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DO C 08/16/98 @ 10:17 AM �: I j � '_- ti l' � !s STUDY AREA BOUNDARY Co 3 - - 1� _ _ i N O � � 1 M N W Z I � � WN 5000 0 5000 10000 / N Iscale feet M M I a Co i w _ ij2I o CE u- D w m �F-L- uu ' ; wa EXISTING LIMITS z z I a ' CITY '- I N a I ! 20 YEAR PLANNING BOUND RY I I - - - - - - - - = - - - - - - - -- - - - STUDY AREA BOUNDARY 1 I I IM, I i J rl 1 1 , I • • -I rl 1 7 , I 1 _ • e :e i Y 1 _ I • I I ~I n � I I I�, . I I I N 4.0 EXISTING CONDITIONS 4.1 POPULATION The population of the Greater Bozeman area, which is defined by the boundaries of the Bozeman, Belgrade and Gallatin Gateway Census Divisions, has experienced continuous growth since the 1940's. The population trends of the Greater Bozeman area and the City of Bozeman are summarized in Table 4.1-1. (Peccia, 1991) r TABLE 4.1-1 POPULATION TRENDS GREATER PERCENT OF BOZEMAN PERCENT CITY OF PERCENT TOTAL POP. YEAR AREA CHANGE BOZEMAN CHANGE WITHIN CITY 1940 13,658 8,665 63.4% 1950 16,906 23.7% 11,325 30.7% 67.0% 1960 20,913 23.7% 13,361 18.0% 63.9% 1970 27,119 29.7% 18,670 39.7% 68.8% 1980 36,437 34.4% 21,645 15.9% 59.4% 1990 43,085 18.2% 22,660 4.7% 52.6% Until the 1970's, the majority of the population growth occurred within the City of Bozeman. However, the Bureau of Census information shows that since 1970 the majority of population growth has occurred outside the city limits. During the last ten years the population of the Greater Bozeman area has increased by 18.2%, while the City of Bozeman population growth during this time was just 4.7%. During the 1980's, the City of Bozeman captured only 15% of the total Greater Bozeman area growth. Although continuing development outside the city limits has decreased the population growth rate of the City of Bozeman, the possible annexation of surrounding subdivisions could significantly alter future population trends. - 14 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM The population served by the Bozeman sewer system includes permanent residents, non-residents, tourists, Montana State University employees and students. The 1990 census reported the population of the City of Bozeman as 22,660 people, which includes the majority of the 10,392 MSU students. The 1997 edition of the Rand McNally Commercial Atlas and Marketing Guide estimated the Bozeman city population as 25,800 for January 1, 1996. Many students leave the Bozeman area during the summer months. In 1996, the academic year enrollment was 11,611, the summer enrollment was 2,823, a difference of 8,788. The difference between the summer and winter tourist population is approximately 1,000 people according to information received from the Bozeman Chamber of Commerce. The 1990 Census data also reported that 8,823 housing units are connected to the city sewer and 8,774 housing units are connected to the water system. The Census Bureau defines a housing unit as a house, an apartment, a mobile home, a group of rooms, or a single room that is occupied or is intended for occupancy as a living quarters. Bozeman currently has 5,744 water and sewer accounts. The difference between the Census data and the number of sewer accounts is likely due to apartments where one meter or account serves several housing units. The basic types of users and the number of users consist of 134 flat rate, 3,717 single family, 1,102 multi-family, 49 government, 15 Montana State University services and 727 commercial accounts. 4.2 ZONING AND POPULATION DENSITY Bozeman has developed a master zoning plan to guide development within the city and the jurisdictional area. The categories of land use are residential, commercial, industrial, public and agricultural. Within the city limits there are 8 types of residential zones, 3 types of commercial zones and 3 types of industrial zones. Public lands include schools, parks and Montana State University land. Approximately 234 acres within the City limits are zoned agricultural suburban. Table 4.2-1 shows the zoning designations within Bozeman, the allowable dwelling density based on the City Zoning Codes, the actual dwelling density and the population density based on the - 15 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM actual dwelling density. Since many areas of the city have not been developed to their maximum allowable capacity, actual densities were calculated based on the 1990 census for the City of Bozeman. The actual dwelling density was determined from the 1990 census data. The 1990 census divided the city into seven block numbering areas (BNA's). Each BNA was further divided into Block Groups. A map showing the location of the BNA and Block Group is included in Appendix A. Appendix A also includes a table which shows how the actual dwelling unit (D.U.) and population densities were estimated for the various zone classifications. Population densities were estimated using the Planning Office's estimate of 2.54 people per dwelling unit. The values for the existing average dwelling units per acre are based on the total land area within the block group, i.e. the area for roads, floodplain, or other set back requirements have not been deducted from the available land area. TABLE 4.2-1 RESIDENTIAL ZONING DENSITIES EXISTING AVERAGE ALLOWABLE DWELLING POPULATION ZONE ZONING DENSITY DENSITY DENSITY (D.U./Acre) (D.U./Acre) (People/Acre) R-1 3 1.5 3.81 R-2 6 3 7.62 R-3 12 4.8 12.19 R-3A 10 4.8 12.19 R-4 15 4.8 12.19 R-0 15 4.8 12.19 R-S 1 1 2.54 l R-MIS* 8 — *Only 0.5% of the zoning within the city is Zone R-MH. The majority of mobile homes are located in R-3 and R-4 zoning areas. Census data was not available to estimate existing dwelling densities in R-MH Zoning. The commercial zone classifications are Neighborhood Business District (B-1), Community Highway Business District (B-2) and Business Park District (BP). Industrial land uses are zoned as - 16 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM Light Manufacturing (M-1), and Manufacturing and Industrial District (M-2). Figure 4.2-1 shows the city zoning boundaries. 4.3 WASTEWATER FLOWS AND LOADS Wastewater treatment plant flow and loading records from January 1988 through December 1993 were reviewed to determine the past flow and loading trends in Bozeman. Additional data from 1996 is also shown. The average monthly flow data is shown in Table 4.3.1-1. TABLE 4.3.1-1 AVERAGE MONTHLY FLOW (MGD) MONTH 1988 1989 1990 1991 1992 1993 1996 January 4.30 4.25 4.27 3.94 3.19 4.06 4.3 February 4.33 4.26 4.24 4.00 3.36 4.14 4.7 March 4.52 4.59 4.56 4.00 3.31 4.56 4.6 April 5.02 4.94 4.72 4.54 3.79 5.09 4.9 May 6.19 5.47 5.21 5.60 3.99 6.08 5.2 June 5.48 5.14 4.72 5.09 4.63 6.11 5.5 July 4.28 4.42 4.49 4.52 5.42 6.43 4.8 August 4.20 3.07 3.99 4.18 4.78 5.55 4.6 September 3.68 4.43 4.01 4.36 4.84 5.07 4.8 October 4.58 4.61 4.08 3.94 4.72 4.71 4.7 November 4.27 4.30 3.83 3.67 4.37 4.47 4.6 December 4.09 4.02 3.86 3.39 4.08 4.09 4.2 Average 4.58 4.46 4.33 4.27 4.21 5.03 4.7 PEAKING FACTORS Peak 1.35 1.23 1.20 1.31 1.29 1.28 1.17 Month/Average Month Peak Day/Annual 1.36 1.53 1.74 1.99 Average - 17 - \\H KM\P ROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM M 1 wN M1 ew. ` qi /4t_ 8$ Y ..... ,a J `, r.. r. 5554, AS f M-2 t x�� I RS RS RS "I AS s R-2A I L PL1 I IS R 3 R-3 _ F n BI ('v B-2 CL�t�O l�❑ICJ❑❑ B_2 _ ! EIL - 2 m `J iL ❑ tl M I 1 �� El w B-2 OUR 0 R-4 OO lJl7trllsl© r.s PLI BP ` PLIB-2 ss M B R_a P R-4 U.S, 191 ® r I �Me ss P.-1 U❑ BP L', e ' ' O MM n e .w. r 2 , RS BP Montana ❑� PLI L R-3A R State k LLLYYY I'LI i i R-a-3 / I _ University f S I I Imw ' e-I Yr ry - I RS ..,w._ li 9P R-S ~ R-2 J MP �w mFe Pon Rd SeM.n+4 Y f BOZEMAN WASTEWATER FACILITY PLAN CITY ZONING BOUNDARIES As the data indicates, the average annual flow has decreased slightly each year from 1988 through 1992. Then in 1993 there was a significant flow increase. It is suspected that the flow increase in 1993 was due primarily to increased infiltration and inflow (I/I) caused by the abnormally wet spring and summer. From April through August 1993, precipitation totaled 18.56 inches, compared to an average of 10.11 inches in April through August for the years 1988 through 1992. Based on the 1990 Census population of 22,660, the per capita flow ranged from 186 gpd in 1992 to 222 gpd in 1993. The 1996 population estimate of 25,800 and the average annual flow of 4.7 MGD equates to a per capita flow of 182 gpd. The total per capita flow includes domestic usage, industrial and commercial flows, and infiltration and inflow. The per capita flows are high and indicate excessive infiltration and inflow is occurring. The EPA generally considers flows of over 120 gallons per capita per day as excessive (USEPA, 1984). As discussed later in Section 4.5.2, when the groundwater infiltration component of flow is subtracted, the wastewater flow is calculated to range from 105 to 120 gallons per capita per day. The total suspended solids (TSS) and biochemical oxygen demand (BOD5) loadings to the wastewater plant were also calculated to determine if the 1993 flow increase also resulted in loading increases. The loading data was calculated based on the average monthly flow, TSS and BODS data provided by the City wastewater treatment plant personnel. Table 4.3.1-2 shows the monthly organic loading for 1990 through 1993. - 19 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM TABLE 4.3.1-2 INFLUENT ORGANIC LOADING YEAR 1990 1991 1992 1993 MONTH TSS BOD TSS BOD TSS BOD TSS BOD lbs/day lbs/day lbs/day lbs/day lbs/day lbs/day lbs/day lbs/day January 2,966 5,412 3,384 4,830 3,086 3,325 3,589 4,774 February 5,176 6,309 4,737 5,838 3,502 4,315 5,973 6,042 March 4,145 4,843 4,137 4,670 2,926 4,086 4,069 5,666 April 3,761 4,956 4,127 4,771 3,255 4,236 4,245 5,391 May 4,102 5,040 4,763 5,230 3,227 3,694 4,107 3,853 June 3,611 4,450 4,202 4,712 3,977 4,402 3,873 4,892 July 3,254 4,199 3,618 4,184 3,706 4,204 4,022 4,558 August 2,542 4,098 3,904 4,567 3,548 4,903 4,119 5,647 September 3,324 4,431 3,600 4,073 4,601 5,611 4,693 5,074 October 3,389 5,274 3,286 3,812 3,842 5,550 3,504 5,303 November 3,482 4,919 3,275 3,489 3,900 5,721 3,877 4,399 December 3,187 5,118 3,364 3,788 3,607 4,730 3,547 4,127 AVERAGE 3,578 1 4,920 3,866 4,497 1 3,598 4,565 4,134 4,976 As indicated in Table 4.3.1-2, the 1993 BOD, loading did not increase significantly over the 1990 level. The 1993 BOD5 loading shows a 6.7% increase over the average of the 1990 through 1992 loading. In comparison, the 1993 flow increased 17.8% over the average of the 1990 through 1992 flow. This disproportionate increase in flow compared to BOD5 confirms the assumption that this flow increase was largely due to increased I/I caused by an extremely wet spring and summer. Table 4.3.1-3 shows the average monthly influent BOD5 concentrations from 1990 through 1993. As the table indicates, the influent BOD5 concentrations decrease during the spring and summer. This fluctuation is an indication of I/I flow entering the system and diluting the waste stream. Typically BOD5 concentrations of approximately 200 mg/l are considered an average strength waste. (Metcalf& Eddy, 1979). The low average BOD5 concentration (Average 1990-1993 is 130 mg/1) compared to typical BOD5 concentrations again confirms that excessive amounts of I/I are entering the system. - 20 - \\H KM\PR OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM TABLE 4.3.1-3 INFLUENT BOD5 CONCENTRATIONS (MG/L) MONTH 1990 1991 1992 1993 January 152 147 125 141 February 167 175 154 175 March 136 140 148 149 April 126 126 134 127 May 119 112 111 76 June 113 111 114 96 July 112 ill 93 85 August 123 131 123 ; 122 September 133 112 139 120 October 155 116 141 ; 135 November 154 114 157 ( 118 December 159 134 139 121 Average 137 127 132 122 Using the 1990 Census population of 22,660 and the 1990 organic loading, the load per capita is calculated to average 0.16 pounds TSS/capita/day and 0.22 pounds BOD5/capita-'day. These values are in the range of typical text book design values. 4.4 WASTEWATER COLLECTION SYSTEM 4.4.1 System Description The wastewater collection system for the City of Bozeman, shown on Plate 4.4.1-1 (bound in back), consists of approximately 98 miles of gravity sewer lines, ranging in size from 6-inch to 30- inch in diameter, and 1700 manholes. A lift station serves a small area east of Bozeman between - 21 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM Interstate I-90 and U.S. Route 10. Duplex pumps in the lift station are each capable of pumping 450 gpm of raw unscreened sewage at 26 feet total dynamic head (TDH). Approximately 350 feet of 6-inch force main conveys wastewater from the lift station to the main collection system. The sewer mains are constructed of vitrified clay, asbestos concrete and PVC. The original collection system was constructed in 1901, and expanded as Bozeman grew over the years. Pipe materials, sizes and age, when known, are shown on Plate 4.4.1-1 (bound in back). Wastewater flows to the Bozeman Wastewater Treatment Plant through two main interceptors. A 24-inch line south of I-90 collects wastewater from the southern and western portions of Bozeman. A 20-inch main, which parallels U.S. 10, receives flow from the northern and eastern sections of Bozeman. For the hydraulic analysis of existing sewer lines, the collection system was divided into six drainage zones. The drainage zones were established by selecting the portions of the collection system that were independent of the remaining collection system i.e. little or no flow occurs from one zone into another zone. Typically the drainage zones will drain to one large collector main. The drainage zones are delineated in Plate 4.4.1-1 bound in the back of the report. For the I/I analysis, drainage Zone 6 was divided further into 3 drainage areas. The 8 drainage zones used in the 1/1 analysis are described in Table 4.4.1-1. Table 4.4.1-1 lists the inch-diameter-miles of pipe within each drainage zone, the total area served and the area per land use zone. The inch-diameter- mile is determined by multiplying the length of sewer line in each zone by the diameter of the pipe. This measurement provides a means to compare the I/I in a drainage zone to standards for I/1 in newly installed pipe. State standards contained in the Department of Environmental Quality Circular WQB 2-Section 33.93, specify that infiltration should not exceed 200 gallons per day per inch-diameter-mile of pipe. - 22 - \\H KM\PR OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM rn In 00 rr 00 � enS2 en On0 pN N �O M ON � i H 0 ~ cV F-' O M In 'C v In M 00 M O (� N Q� U y f/] y cC U N � c In z pW, o r — M 00 OONo � w W Q v N In z N In In M W N N ^, ,n y N Q U n N p" "D H C*0 M �O M M \p Fr N t N W 00 U 'n - rn In oc ;o b Hn vi OxC ONN O� O n .406 rier411 M � okn N OC IN In C p � O ¢ m O r�i O O z ;: zoo o ^ wxx � O z y N Q z n z Gam. .. w N N 0 �y O O y O O O M a O Q c ❑ G < c a c a o o o a ao CIO. y �0 O INM In '0 \D Z a pOj N * Y co 2 00 0 I I . �< _• . y 4.5 INFILTRATION AND INFLOW 4.5.1 General Infiltration is defined as water that enters a sewer system and service connections from the ground, through defective pipes, pipe joints, connections, manholes, or other means. Infiltration water is normally relatively clean water with low BOD5 and TSS concentrations. Infiltration is due to high groundwater levels which are generally elevated by rainfall events. The magnitude of groundwater infiltration depends on groundwater levels which fluctuate throughout the year. Rainfall-dependent infiltration (RDI) occurs when storm water either percolates through the soil above a defective sewer or via the pipe trench in which the sewer is constructed. Infiltration can be considered to have two principal components: • Ground Water Infiltration (GWI) and • Rainfall-Dependent Infiltration. (RDI) Infiltration due to groundwater (GWI) will be fairly consistent on a daily basis but seasonal variations will occur in response to changing groundwater depths. Rainfall-dependent infiltration (RDI) has a slower response time and will often lag the storm event by hours or days depending on the permeability of the soils. Inflow is defined as water that discharges into a sewer system and service connections from sources such as roof drains, cellar drains, sump pumps, yard drains, area drains, foundation drains, manhole covers, cross connections from storm sewers, catch basins, surface water or storm water runoff. Like infiltration, inflow is typically relatively clean water with low BOD5 and TSS concentrations. As inflow is characterized by a direct connection or discharge to the sewer system, inflow will result in a rapid flow increase during a storm event. Infiltration and inflow (1/I) results in increased wastewater collection and treatment costs and untreated wastewater bypasses or overflows. - 24 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM The first step in the I/I analysis for the City of Bozeman, was an analysis of wastewater flows on a system-wide basis to determine if excessive I/I exists. Following the discovery of excessive I/1, information was gathered on the individual wastewater drainage areas in order to identify specific areas within the city with high infiltration and/or inflow. Section 4.5.2 discusses the results of the system-wide analysis. Section 4.5.3 discusses the analysis of the individual drainage areas. 4.5.2 System-wide Analysis 4.5.2.1 Dry weather flows. A comparison of the wastewater flows recorded at the Bozeman Wastewater Treatment Plant shows significant seasonal variations. Figure 4.5.2-1 is a graph of the flows recorded on February 24, 1993 and on June 30, 1993. The February 24, 1993 flow exhibited the lowest nighttime flow during the winter of 1993. The flow on June 30, 1993 represents a typical dry weather day during the summer. Since rainfall had not occurred for several days, rainfall dependent I/I was not a factor in the observed flows. It is noted that the University classes are out in June and many of the students have left Bozeman at the time of the June 30, 1993 flow reading. The flow on June 30, 1993 was 5.78 MGD, an increase of 1.39 MGD from the flow of 4.39 MGD on February 24, 1993. The flow increase from winter to spring is most likely caused by groundwater infiltration due to increased water table elevations. There are several locations in Bozeman where sewer mains are below the water table, which provides a high potential for groundwater infiltration. Section 4.5.4, presented later in this report, discusses groundwater infiltration and identifies areas where the groundwater table is above the sewer lines (Table 4.5.4-1). As discussed below, an analysis of the Bozeman Wastewater Treatment Plant flow records show that groundwater infiltration is indeed significant in the sewer system. - 25 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DO C 08/16/98 @ 10:17 AM N = � Wr 0 ■ 1 I I I O W I 1 1 1 1 I I I I I I I I I I I I 1 I 1 I I I O I 1 I 1 O I I 1 I N I I I 1 I I 1 1 1 I I Z 1 I I I Q I I I g 1 g I I � LL 1 d0 1 ~ 1 I I I Z 1 1 I I O I 1 1 W 1 Q 1 I I Q 1 p LL W z 1 1 W 1 z Q I 0 1 1 1 3 I p2 I I I Q I ;4 F L I 0O I I I I J 1 1 I LLIt 0 Q 1 a z 1 I I 1 d 1 1 t Q 1 1 1 I I I I I I J 1 I I 1 p 1 1 I I g 1 I 1 1 I I 1 0 1 1 I Q I 1 I I 1 I 1 1 W I 1 I 1 CD I 1 I I I 1 I I I I I I 1 1 1 I 1 I I 1 I I I I I I o n cd v Cl) (OJW)M0,1=1 i I� r' I .�: I' The minimum nighttime wastewater flow rates, which ranged from 4.0 to 5.5 MGD on dry weather days during the spring of 1993, were very high for a community with a population of approximately 23,000. Based on a typical sewage rate of 100 gpd/person, the expected average daily flow for Bozeman would only be 2.3 MGD, which is less than the minimum recorded nighttime flow rates. Using a ratio of 0.38 for minimum to average flow rates (Joint Task Force Manual 60), the expected night time minimum flow would be about 0.87 MGD if infiltration was not present in the system. Actual minimum nighttime flows include domestic flow, industrial flows and any groundwater infiltration. The amount of groundwater infiltration can be estimated by subtracting the estimated nighttime domestic flow (0.87 MGD) and industrial flows (approximately 0.06 MGD) from the minimum nighttime flow. Figure 4.5.2-2 is a hydrograph of the wastewater flows recorded on June 30, 1993, a dry weather day. The total flow for June 30, 1993 was 5.78 million gallons. The components of the total wastewater flow are represented, which shows that a large amount of groundwater infiltration is occurring, approximately 3.32 MGD. This estimate was determined by subtracting the expected nighttime minimum flow (0.87 MGD + 0.06 MGD = 0.93 MGD) from the actual minimum nighttime flow of 4.25 MGD. When the estimated groundwater infiltration is subtracted from the total daily flow of 5.78 MG, the adjusted average wastewater flow is 2.46 MGD, or approximately 105 gpd/person, a much more reasonable value for per capita wastewater flow. It should be noted that the flow of 105 gpd/person includes commercial and industrial flows in addition to domestic flows. The same analysis was used to evaluate the magnitude of groundwater infiltration during the winter, as shown in Figure 4.5.2-3. On February 24, 1993, the maximum temperature was 25T. Snow melt was not a contributing factor to the amount of infiltration. The February 24, 1993, average daily flow rate was 4.39 MGD and the minimum flow rate was 2.6 MGD. By subtracting the estimated nighttime domestic flow and industrial flows, (a total of .93 MGD) from the minimum flow, the groundwater infiltration is estimated to be approximately 1.67 MGD. When the groundwater infiltration rate of 1.67 MGD is subtracted from the total plant flow, the per capita wastewater flow was calculated to be 120 gpd. A similar analysis on February 23, 1993 indicates a - 27 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM per capita flow of 117 gpd. As noted above, the flow of 117 gallons per person per day includes -commerce and indusiial-Wows. From 1988 through 1993 the average annual flow was 4.48 MGD. Based on a 1990 census of 22,660 persons and a per capita flow of 117 gallons per person per day the resulting domestic, commercial and industrial flow would be 2.65 MGD. Subtracting the low of 2.65 MGD from the actual flow indicates the annual average I/I flow is 1.83 MGD. - 28 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM N 9 � N MA Fi W Z ir Z r 0 I 1 I I I I I p0 LL 1 1 t 1 � t � 1 0 1 /Il 1 1 0 -00 I 1 J 1 rJ LL- W a ' N MQM I ii N � li N $ PRO� w O 1 O �y s!#?t>`it r,� < r� :?•k h �n ii uj 44 ::3•.i:<%{fit�.., `�`{ „ /e �i k O cc • I I �� [i•;:cb uj ..........:; o ............ 4t1>..I. .......Fla I I � .✓:Si<:i:i;i:i:i:i:5iii:i::i::i:i<:;> (n ao r— co In Q m N r a (aJW)MOIJ ,:.� �' .�' ,; 1 . I ■ �\•.{f ff�Y"`c...y�','•'tk,'>','�:f:::f\C'�C 4,+ytt�kk` • ■ • ■ • ■ N ■ g`•uyy QD CD � k ;, L•' co ui LL 4l � � , ti:. ., ; - f � �� I I I �. .^ �� Comparing the difference between the maximum and minimum daily flows shown in Figures 4.5.2- 2 and 4.5.2-3, it is observed that the diurnal variation is 3.5 MGD during the winter and 2.75 MGD during the summer. The smaller diurnal variation observed during the summer most likely results from the smaller student population during the summer. As discussed previously in Section 4.1, the student population decreases by approximately 8,800 students during the summer. In summary, during dry weather conditions the volume of groundwater infiltration ranges from approximately 3.32 MGD during the summer to 1.67 MGD during the winter. Assuming an average annual groundwater infiltration rate of 2.50 MGD, groundwater infiltration constituted approximately 50 percent of the total flow in 1993. 4.5.2.2 Wet Weather Flows. The flow records from the wastewater treatment plant indicate high groundwater infiltration. These records also show that rainfall-dependent inflow/infiltration (RDI/I) is a problem in the Bozeman system. In order to study the rain-dependent inflow/infiltration problem, the flow rates experienced during wet and dry weather periods were compared. The average daily flows during wet weather increased to approximately 8.0 MGD compared to summer dry weather average daily flows of 5.7-6.8 MGD. Nighttime flow rates during wet weather increase to 6.0-7.5 MGD compared to normal summer dry weather minimums of 4.2-5.0 MGD. The distinct increase in flow during and following a storm indicates that rain-dependent inflow/infiltration is dramatically occurring in the wastewater collection system. Figure 4.5.2-4 shows the wastewater flows and the precipitation recorded from June 3-July 12, 1993. - 31 - \\H KM\PR OJ ECT\DATA\O6\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM <� III�� r ' ' •� �A� Y O �� N E � 4 .� LV on M (HH/S3HON1)llV=INPda II(�� ? S r N V M (�1 r r.t r O I 1 ! 1 1 1 1 I r I I I 1 I I I i 1 I 1 I I I 1 O 1 I 1 I I I i I 1 1 1 1 1 r I 1 1 I 1 I O I I 1 1 1 1 p I I I I I 1 (D I I 1 I 1 O p I I 1 1 1 1 1 ! 1 1 1 1 I I I 1 1 1 1 n I I I I I 1 h Z 1 1 I I I I 1 p O I ( 1 1 L I 1 I I I I 1 I p I 1 1 t 1 I I p L l 1 r I I I N ^ I 1 I I I 1 L.L 1 1 1 O I i 1 1 1 W I ( I 1 1 I N 1 1 I 1 I I 1 1 1 ! I i 1 1 1 fri I z W I I 1 I 1 t N p — 1 1 t I 1 I I I I I i I I I 1 1 I i 1 1 1 01 I I t I 1 I O J A r I I I I I 1 � LL ii 1 ! I I 1 1 1 a / N I I I I I I (D a W r I I I I 1 I I I 1 I I I 1 1 1 t I I I Q M I I 1 I I I 1 1 I 1 I 1 I M I 1 I 1 1 I 1 r I 1 1 I I z 1 , 1 I I I 1 1 1 Of 1 1 I 1 I I I 1 I I I 1 0 J I I ! I I 1 I 1 I Q a I I I I 1 ry I I t 1 I I I (p 1 I I I I I 1 p p In co Ih (O Il7 'C P") N (CmIN)MOI=1 _ ., �� -x �•'.Y ,�i ;�:• , 1�,^ • . The flow and precipitation data for each storm occurring in the June 3-July 12 period were analyzed to determine the magnitude of rainfall-dependent inflow/infiltration and to separate it into storm water inflow (SWI) and rainfall-dependent infiltration (RDI) components. The results of these analyses are presented in the following discussion. There were several storms during June of similar magnitude, less than 0.15 inches per hour. These storms are very common during the spring in Montana. The storm on July 3-4, 1993 was not typical since it had much greater intensity and duration. Based on the amount of precipitation recorded during a 6 hour period (1.28 inches), the return frequency of this storm is 5 years. Based on the 2.25 inches of rainfall recorded over a 24 hour period, a storm of this magnitude would only occur every 15 years. In order to quantify the average, as well as the potential quantity of rainfall dependent infiltration/inflow (RDI/I), the wastewater flows during the typical June storms as well as the July 3-4, 1993 storm were analyzed. RDI/I is apparent when wastewater flows recorded during and after a storm are compared to a dry weather flow hydrograph. A typical dry weather flow hydrograph was generated from the wastewater flows recorded during dry periods. The comparison of the typical dry weather flow to wet weather flow was made for the storms which occurred on June 6-8, June 10-12, June 15, June 22-23 and July 3-4, 1993. The magnitude of RDI/I was determined for each storm by subtracting the base flow and groundwater infiltration from the recorded flow. The difference was then separated into SWI and RDI by analyzing the precipitation and wastewater flow records. Any excess flow observed a few hours after rainfall ceases is assumed to be caused by infiltration. Storm water inflow is defined as all flow above the base flow, groundwater infiltration, and RDI. Using these criteria, the contribution of RDI and SWI to the total RDI/I were determined for each storm. - 33 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM Figures 4.5.2-5 through 4.5.2-8 show the precipitation and the wastewater flow recorded during and after each of the storms. Table 4.5.2-1 summarizes the maximum RDI/I, SWI and RDI observed during the storms. The maximum RDI/I does not equal the sum of the maximum SWI plus the maximum RDI because these flows do not peak at the same time. TABLE 4.5.2-1 RAINFALL DEPENDENT I/I FLOW COMPONENTS Storm Date Max RDI/I Max SWI i Max RDI 6/6/93 - 6/8/93 1.75 MGD 1.0 MGD j 1.1 MGD 6/10/93 - 6/12/93 1.8 MGD 0.8 MGD 1.3 MGD 6/15/93 1.95 MGD 0.95 MGD 1.1 MGD 6/22/93 - 6/23/93 1.5 MGD 0.95 MGD 0.7 MGD 7/3/93 3.85 MGD 1.7 MGD 2.75 MGD *RDI/I - Rainfall dependent Infiltration and Inflow SWI - Storm Water Inflow RDI - Rainfall Dependent Infiltration - 34 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DO C 08/16/98 @ 10:17 AM 025 - 02 -- - - - - - - - - -- - - -- - -. _ _ .. _ _ .- - - - - - - - - -- - - - -- -- - - - o is 3 a z - - - - -- - - - - - - - - - - - - - - - - - - - -- - - - -- - - - - - - -- - -- � I 05/06 08107 D6108 MOD D611D D6111 D6/12 06/13 TOTAL PRECIP 0.44 0.06 1.03 0.00 DATE 0.08 0.55 0.36 0.00 INCHES/DAY 10 - - - _ _- ___- - _ __- _ _ -- _ _ _ - - 0 3 0 LL 2 OBl06 OB107 06/OD 06/10 08111 00112 OB/13 DATE PRECIPITATION AND WASTEWATER FLOWS FIGURE 4.5.2-5 KKAk ANNOC 1 AM (JUNE 6-13, 1993) BNciMMe • nARRIER• i 1� 1,- ' i .. I . � . u. � .: 016 014 - - - - - - ---- ---- -- - - - - - - - - -- - ------ - -- 0.12 - - - - - - -- -- - - - - - - - - - - - - - - - - - - - - -- -- 0.1- ------- ---- --- -- --- -- ---- -- - -- - - -- -------- -- - - - rc 3 �0.06 ------- -- ----- - ----- -- ---- -- ----------- - - - -- - - LL 0.06 ----- -- -- - - - -- - ---- -- ----- - - -- -- -------- --- - - 0.04 - - ----- -- ----- _ _ --_ __ -- _ _ _ _ 0.02 - ------ ---- --- - - - - _- _- -_ _ __ _ __ _ _ ___ ___ _ _ ___ __ 0 06113 06114 05115 06116 06117 06118 08119 06120 TOTAL PRECIP. 0.00 0.00 0.42 0.17 DATE 0.07 0.00 0.00 0.00 INCHES/DAY 10 g -- --- - --- - --- -- _ _ - _ _ - - -- - -___ - - -- __ _- -_ _ _ - _ - _ g _ _ 0 O LL 4 2 0 06113 08114 06115 06/18 08117 06118 06110 08120 DATE GYA R01 ■SWI .RASE PLOY) PRECIPITATION AND WASTEWATER FLOWS FIGURE 4.5.2-6 HKAk ANNOCIATBS (JUNE 13-20, 1993) EnGim is riAmms • , j�:: ' 1. � � r . D.25 02 - DIS - - - - - K G Z 4 � D.t - - - - - _ _ _ _ _ _ _ _ _ _ _ _ _ ______ _ __ __ __ _ _ ___ _ _ _ _ -- - _ _ - - - 005 - ` _ - _ _ __ _ _ _ _ __ _ _ __ ___ _ ____ _ _ _ _ _ _._ _ DB120 D5121 06122 08I23 D8124 08125 0812E 05127 TOTAL PRECIP. 0.00 0.00 0.44 0.14 DATE 0.01 INCHES/DAY 10 - 0 3 0 4 2 D D812D D8121 06122 08123 08124 08125 08126 DATE ■RYVI .Rol ■8W1 . MIE FLOW PRECIPITATION AND WASTEWATER FLOWS FIGURE 4.5.2-7 NKA ASSOC 1 AT 89 (JUNE 20-27, 1993) e�c��e n.ut�ees � � ,� �� . a, J e �.:, �: 1, D,3 0.24 - ----------------- ----------- ---------- --- - - - _. _ 018 - -- - - - - - - - - ------- ---- ------- - - - ---- --- -- - - - - - rc a z -a rc 0.08-- - -- - - -- - - - - - - - - - ---- --- - --- ------ o A D7/03 07104 07105 07108 O7fD7 07105 MOD D7110 TOTAL PRECIP. 2 05 0.39 0.02 0.03 DATE 0.07 0.00 0.00 0.05 INCHES/DAY 12 72 O LL 48 24 D - D7103 071D4 01105 07105 07107 07108 D71D9 07/10 DATE .6W1 .Rot .81M -BhSE FLOW PRECIPITATION AND WASTEWATER FLOWS FIGURE 4.5.2-8 N[A ASSOCIATBS (JULY 3-10, 1993) commas n.ums �'� , _ .y 7'., I � Based on Figures 4.5.2-5 through 4.5.2-8, infiltration increases to a maximum during a storm and then gradually tapers off. Storm water inflow, on the other hand, can vary considerably during a storm as the amount of precipitation changes over time, but generally tapers off rapidly with cessation of the precipitation event. The rainfall dependent infiltration (RDI) gradually decreases following each storm. This effect is noticeable by comparing the minimum daily flow rates over an extended time period as shown previously in Figure 4.5.2-4. The minimum flow rates decrease each day following a storm as the RDI ceases. As a result of the June storms, flow rates did not return to the minimums seen during dry weather until June 29. Following the severe storm on July 3-4, rainfall dependent infiltration did not cease until August 14. By comparing the volumes collected over the period of a storm, it is apparent that infiltration has a much larger contribution to the total I/I than inflow. Table 4.5.2-2 lists the volumes of the various flow components for the June and July 1993 storms. TABLE 4.5.2-2 VOLUMES OF FLOW COMPONENTS DURING STORM EVENTS Domestic Total Total Flow I/I Flow GWI RDI SWI Storm Date Duration (MG) (MG) (MG) (MG) (MG) (MG) 6/6-6/8/93 61 hrs. 6.36 10.62 16.98 8.44 1.67 .51 (2.5 MG) (62.5)* (79%)+ (16%)+ (5%)+ 6/10-6/12/93 39 hrs. 3.68 7.67 11.35 5.4 1.95 .33 (2.26 MG) (67.6)* (71%)+ (25%)+ (4%)+ 6/15/93 10 hrs. 1.07 1.92 2.99 1.38 .39 .15 (2.57 MG) (64.2)* (72%)+ (20%)+ (8%)+ 6/22-6/23/93 21 hrs. 2.2 3.61 5.81 2.91 .53 18 (2.51 MG) (62.1)* (80%)+ (15`h) (5%)+ 7/3-7/4/93 24 hrs. 2.23 6.45 8.68 3.32 2.31 .82 (2.23 MG) (74.3)* (51%)+ (36%)+ * Percent of Total Flow + Percent of Total I/I - 39 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM As shown in Table 4.5.2-2, the total I/I flow ranges from 62.1 percent to 74.3 percent of the total flow during storm events. Of the I/I components, groundwater infiltration is the most significant and can account for up to 80 percent of the I/I flow. Rainfall dependent infiltration can also contribute a substantial portion of total I/I flow; up to 36% during the July 3rd-4th, 1993 storm. While some storm water inflow can be observed the volumes are not great. The low storm water inflow volumes indicate that direct connections of roof drains, area drains, or cross connections with storm sewer lines are not a major problem. Table 4.5.2-3 provides a summary of the dry weather and wet weather flows observed during 1993. The table indicates the significant impact both groundwater infiltration and rainfall dependent infiltration have on the system flows. During the summer, the rise in the groundwater table causes the flows to increase from 4.5 MGD to 6.25 MGD. During rainfall and snowmelt events the flows are increased dramatically when compared to winter time dry weather flows. These flow increases effect available capacity of the collection system and the hydraulic functions in the wastewater treatment plant. TABLE 4.5.2-3 SUMMARY OF DRY AND WET WEATHER FLOWS (MGD) DRY WEATHER FLOWS WET WEATHER FLOW WINTER SUMMER SUMMER Average 4.5 6.25 8.0 Peak 6.5 7.5 10.0 Minimum 2.5 5.0 6.0 4.5.3 Drainage Area Analysis Flow metering devices were installed at primary and secondary sites in order to monitor flows from the various drainage zones, and thus discover specific inflow/infiltration sources. The primary monitoring sites were located on the major outfall lines and included more than one drainage area. - 40 - \\H KM\P ROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM The secondary sites were located at collection points to monitor smaller drainage areas. The monitoring sites are listed below and are shown on Plate 4.4.1-1. Continuous flow recorders were used at the primary monitoring site on 17th Avenue and at the two secondary locations on Durston Street (between 16th and 17th and between 18th and 19th Avenues). The scope of work for the flow monitoring was limited to selected manholes to estimate flows from general drainage areas. A combination of additional monitoring and TV inspection may further isolate high I/I line segments. Primaa Sites 15" main north of Durston on 17th Avenue (continuous recording) 18" main north of Durston Street 24" main north of Durston Street 21" main west of Rouse Avenue Secondary Sites 15" main on Durston between 18th and 19th Avenues (continuous recording) 15" main on Durston between 16th and 17th Avenues (continuous recording) 12" main at Olive St. and loth Avenue 12" main at Alderson St. and loth Avenue 10" main on South 3rd Avenue, south of Hill Street 15" main at Aspen Street and Grand Avenue 8" main at Cottonwood Street and Rouse Avenue 10" main at Cottonwood Street and Church Avenue 8" main opposite Dell Place 14" main at Tamarack Street and Church Avenue 12" main at Juniper Street and Church Avenue Flow monitoring was performed at these sites to determine the daily flow patterns during the spring of 1993. Since the flows were recorded in the spring during a period of high groundwater, they - 41 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM consisted of two components: dry-weather base flow plus groundwater infiltration. Further monitoring was conducted during December 1993, after the groundwater table had dropped, to determine dry-weather flow rates and calculate the magnitude of groundwater infiltration. 4.5.4 Groundwater Infiltration In an effort to discover specific areas within the Bozeman sanitary sewer system with high groundwater infiltration, flow monitoring was performed between 1 a.m. and 5 a.m., on June 8', 14', and 30", 1993 when domestic flows are at a minimum. Flows were estimated from contributing subareas at various points upstream of the metered locations using Mannings equation and by measuring the depth of flow and the slope of the line. The calculated infiltration rates for all the areas monitored, expressed in gpd/inch-diameter-mile and gpd/acre, are summarized in Table 5.4-1. Where applicable, the depths of sewer mains below the groundwater table are also noted. The change in groundwater infiltration rates from winter to summer were determined for each area by subtracting the nighttime flows measured on December 16, 1993 from the night time flows measured during June of 1993. Based on the results of the low flow monitoring some specific areas with excessive infiltration rates, above 5,000 gpd per inch-diameter-mile, were identified. These areas are delineated in Plate 4.4.1- 1 and are described below: • Stream crossing on North Rouse Ave., south of Peach St. • Subarea southwest of MH at Garfield St./Bozeman Ave. • Subarea flowing into 8-inch main on Babcock, between 15th and 19th Avenues • MSU campus: extension to married students housing from Koch St./15th Ave. • Stream crossing at Dell Place - 42 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 2 O �W O 0- m 7 W L j 0 Q fV O O G C O lA N pm � s s s o L g s s o s S s o s s s s s s 0 0 a.p fp (O ('7 M N f (n N N N N N cn fn WW N O M O 0 (O O C7 In r` N 0 w N m ir N In M 0 N O N � � N N N Q U Q C Z lyi J pp Q O (O to NO U m m L ti V) N 0 n a0 ITl2 I--' C OQ p Lu Q p � p v v o o r- 0() 0 8 o 0 0 o Ln m r- 00 0 cn J (o c, o Ln c0 o n (o o ^ 0 ^ o 0 (o LO Q p LL CO II c o C7 z w Q W LLO 0 WzpWaMW g O O O 0 0 0 Ln Ln 0 O Ln 0 0 O O 0 O O C ao r` r o o rn o (o Ln CO 0 0 H LLU L Z J U W N w w LL p — p OLL NZ z F- p Z 0 L Ln J (9 7 M v LL o o W Z C9 U L II 00 p Qw wui0 ^ �� zwLLC7 p N (0 (D U')i NN m v M 000 0 o o m o� M v o C9C7 z � O IIO LU W O - O O O O 0 O O O O O o 0 O O O Ln to O II LL LL •-- N lb (O tT (O ON f- ^ 0 rnW00. J N C 00 Of c0 CO 0 Q N pp r- N O cm r- In L/7 cO y N 7 N 7 O N O O N It O O O S * M (0 Ln Ln N m r` m r` m Ln LA N Cl) M m 7 z O O O O O O O O O O O O 0 O O O O O m Q LL LL S 2 W (� W LL 2 LL LL S W � E uJ O U OLn Ln m m (O M (0 Ln M N V m M (O N (0 C) O p N c w o � U + t o U a 2 c c E N 0 : ? m Z L w N E L U c m o N v o w N O w O N (�p ca O Y m m > o p > L=i o m O a, La L o N 0 � d L (n •s se t L m w < 2 1 w O `o w ami v w c U 2 Q Z to c o t U p z N L c o a m J m p Q O m o LYO1 N « U `O aw o 2 `o o s N (� C7 o m > c w � w w w L O le C C w Y O U O w a M m m � N U )10 W 3 3 m 2 w Q (`� c w c o c w c m w Z) 5 v m c U o L _m v w a L m m 'm t m La t 2� w m m m O w O � En o 0 0 = E m E a E = Ea E > 5 - a Ea E m (o c w � o w � w 0 a> > w o m N w � La Q U a co p U (n Ln 2 � (� N � (n x � (n w O (n N > Q x N Y O F ,�, ... ,,:: E � ., s .. I,� �� 4.5.5 Rainfall-Dependent Inflow/Infiltration Flow monitoring was performed (during the storms of June 10, June 11, June 15 and July 3, 1993) to discover areas with rainfall-dependent inflow/infiltration. The three storms occurring in June 1993 were of similar magnitude with a maximum recorded rainfall of 0.15 inches/hour. The storm which occurred on July 3, 1993 was of much greater magnitude than the previous June storms. Flow data recorded during these storms showed rainfall dependent inflow/infiltration at the locations listed in Table 4.5.5-1. TABLE 4.5.5-1 RAINFALL-DEPENDENT INFILTRATION/INFLOW OBSERVED DURING STORMS JULY 3RD JUNE STORMS STORM PRECIPITATION PRECIPITATION DRAINAGE <_0.15 in/hr >_0.15 IN/HR. ZONE MANHOLE ESTIMATED MAX. ESTIMATED DRAINAGE ZONE NO. NO. RD I/I MAX RDI/I Olive and 10th' 4 G0520 185 gpm 210 gpm N. of Durston on 17th 3 H0317 150 gpm Juniper and Church' 6 E0305 100 gpm 180 gpm 21" Main W. of Rouse 6 F0207 100 gpm 280 gpm S. of Aspen, W. of Rouse' 6 * 100 gpm 215 gpm Remainder of 24" Zone 4 50 gpm 50 gpm Aspen and Grand' 6 F0305 50 gpm 100 gpm 18" Main Off W. Durston 2 J0401 40 gpm 55 gpm Tamarack and Church' 1 E0318 40 gpm 195 gpm 17'b Ave.-Eastern Subarea 3 H0305 260 gpm South 3rd' 4 G0723 90 gpm 17'Ave. -Western Subarea 3 H0302 165 gpm Cottonwood and Church' 5 E0302 80 gpm ' These subareas feed into the 20" main on Rouse Z These subareas feed into the 24" main north of Durston ' Calculated value based on sum or difference of other measurements - 44 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM At Olive and loth, it was noted that the drainage area had relatively high levels of rainfall- dependent inflow/infiltration while no ground water infiltration was observed. The sewer lines appear to be above the ground water in this drainage area so it is expected that no ground water infiltration would be observed. However, increased flows during storm events could be caused by any of the following: • roof drains connected to the sewer system • sump pumps that arc on after storm events or • cracked or broken sewer lines that allow rainfall infiltration to enter the system The investigation of I/I on a system-wide basis indicated groundwater infiltration was responsible for the majority of excess flow. During most storms, rainfall-dependent infiltration was responsible for the majority of flow increase. Inflow was generally less than 13% of the total I/I flow. The inflow was determined by subtracting the infiltration flows and average dry weather flows from the flow recorded at the wastewater treatment plant. The flow records from the three flow monitoring sites in the vicinity of Durston and North W', Durston and North 17th, and Durston and North 18th showed a definite flow rate increase when rainfall occurred, as demonstrated by Figures 4.5.5-1, 4.5.5-2 and 4.5.5-3. A comparison of the minimum flows for each day shows that the baseline flow increased following a storm and gradually returned to its previous level over a period of several days. This indicates that rainfall- dependent infiltration is significant in this zone. Table 4.5.5-2 summarizes the rainfall-dependent infiltration/inflow rates estimated for the July 3-4, 1993 storm, expressed in gpd/inch-diameter-mile and gpd/acre. The column titled excess flow shows the increase in flow measured after the July 3 and 4, 1993 storm from the measured flow during dry weather conditions. The total excess flow measured was approximately 2.71 MGD. The total rainfall-dependent inflow/infiltration determined from the wastewater treatment plant flow records for this time period was about 3.2 MGD, a difference of 0.49 MGD. This difference - 45 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM indicates there may be additional infiltration sources between the monitoring points used in this study and the wastewater treatment plant. TABLE 4.5.5-2 RAINFALL-DEPENDENT INFILTRATION/INFLOW FROM JULY 3&4, 1993 DRY WET TOTAL WEATHER WEATHER EXCESS IN. RDI/I ZONE FLOW FLOW(7/3) FLOW DIA- AREA GPD/IN. RDLI ZONE # (GPM) (GPM) (GPM) MILES (ACRES) DIA-MTLF_S GPD/ACRE Juniper and Church 6 180 360 180 46 136 6000 1900 17th Ave.-Eastern 3 470 730 260 83 315 5000 1200 Subarea Olive and loth 4 300 510 210 55 157 5000 1900 21'West of Rouse 6 420 700 280 92 241 4000 1700 S.of Aspen,W.of Rouse 6 510 725 215 105 360 3000 900 Tamarack and Church 1 190 385 195 133 239 2000 1200 South 3rd 17th Ave.Western 4 140 230 90 55 136 2000 1000 Subarea 3 540 705 165 123 423 2000 600 Aspen and Grand Cottonwood/ 6 350 450 100 88 278 2000 500 Church 5 420 500 80 72 190 2000 600 Remainder of 24' Main Zone 4 460 510 50 78 131 1000 500 18'Main N.of Durston 2 130 185 55 72 135 1 1000 600 Rainfall dependent infiltration was shown in Table 4.5.2-2 to contribute between 16% and 36% of the total I/I flow during storm events. Table 4.5.5-2 indicates that rainfall dependent infiltration in drainage Zone 6 is approximately 775 gpm (1.12 MGD). Many of the sewer lines in Zone 6 are vitrified clay tile lines that were installed in the early 1900's. It is expected that leakage at the pipe joints and areas of root intrusion allow infiltration water to enter the collection system after heavy rains or snowmelt events. The 17th Avenue-Eastern Subarea, (manhole H0305 on Durston between 16th and 17th Avenue) also showed high rainfall dependent infiltration flows. The rainfall dependent infiltration was estimated to be 260 gpm (0.37 MGD). Additional flow monitoring and television inspection of the sewer lines in Zone 6 and the eastern area of Zone 3 should be conducted to further isolate areas contributing high rainfall dependent infiltration flows. - 46 - \\HKM\PROJECT\DATA\06W229124\CMC03717 DOC 08/16/98 @ 10:17 AM 0.14 - - - - - - - - - - - - - - - - - - - - - - - - - s z z �0.060.04 - - - - - - - - - - - - - - - - 002 �I - - - - - - - 0.00 'J 06/11 06/13 06/15 06/17 06/19 06121 06/23 06/25 06/27 06/29 06/12 06/14 06/16 06/18 06/20 06/22 06/24 06/26 06128 DATE 1400 1200- - - - - - - - -- - --- - - -- - - - -- -- - 0 LL B00 400-- - 200 - D6/l1 08113 06/15 06117 06119 D8/21 D6123 Oms 06@7 0629 OB/12 06/14 05/16 Ostia 0620 0622 06124 0626 06/28 D6t30 DATE GWI .RDI ■FWI .BASE FLOW FLOW IN 15" MAIN AT DURSTON/17TH FIGURE 4.5.5-1 Nils ASSOCIATES' JUNE 11 - 30, 1993 M.u■ERI e. 0.25 -- ........ ................................. 02 -- ......... ................... .............. -_Jj 0.15 - LL z 0.1 ------------- 0.05 ........0 07102 07/05 07/09 07113 07/17 07/21 07/25 07/29 08/02 07/03 07/07 07111 07/15 07/19 07/23 07/27 07/31 08/04 DATE 80 TOO ------ ----- - - -- ---- - - ---- - - - - - --- --- --- -- - 600 - ---- - - - - - - - - - -- -- ---- - - - - sm - - - --- 400 30D 200 100 OT101 07f03 07105 MOT DTIOD 07111 07[13 07115 OMT OVID 07/21 OT123 07125 0712? 070 07131 08102 08104 071 02 07104 01108 OTIOB 07/1D OT11 2 07/1 4 07/16 D711 B 07120 07122 OT124 07/26 07128 07130 08101 08103 DATE Rol sm -BASE FLUE': FLOW IN 15" MAIN AT DURSTON/ 18TH FIGURE 4.5.5-2 HKA ASSMIATCS" JULY 1 — AUG. 4, 1993 sucrimms MUMS i� r � � i � I 1 �� ;. � . I. 0.3 0.25 D.2 I z Q 01 -- - - - -- - - - - -- - - - -- -- - - - - - -- O.D5 -- - - - - ------ ----- - - - - - - - - - - - - 0 OT102 07/05 07/08 07111 07114 07116 07/19 07/22 07/25 07/2B OT131 O8/02 D7/04 07107 07/09 07112 07115 07118 0721 07124 0712E 07729 0ml DATE 80D 700 .... .......... .__....__._--------....._...--_.__...._.._-__-_._...__..—...—..__.._ ... 600-... _. _ .__......... _...- -.. ._ .. ....._... 500 �400 - 0 300 zoo 1DD 0 07102 07104 0710E 071DS 07110 07112 07714 0711E OT118 0712D 07122 0724 07128 0712E 07130 0WN 07103 07/05 07107 07/09 07111 07113 07115 D7/17 D7119 07121 07/23 07125 07127 07129 D7131 OB102 RATE RRI .swl .OM FLOW FLOW IN 15" MAIN AT DURSTON/ 16TH FIGURE 4.5.5-3 HK& ASSNC 1 A'MS JULY 1 — AUG. 3, 1993 esc�s�s rr.�see■ .f �1 :, � I -, i •I .� 4.6 HYDRAULIC ANALYSIS OF EXISTING COLLECTION SYSTEM 4.6.1 General A computer analysis of the collection system was completed using version 3.08 of the SANSYS Model. Input data relating to pipe sizes and slopes were obtained from the City. The model flows were developed by first overlaying a city zoning map over a map of the collection system. A drainage area and zoning classification was then assigned to each manhole in the model. The input data and map of the areas assigned to each manhole is included in appendix E. The input flow for each manhole was calculated, within the model, by multiplying the population density of the zoning classification by the drainage area and the per capita flow. As discussed in Section 4.5.2-1 the total flow per capita, excluding infiltration, was estimated to be 2.65 MGD which equates to 117 gallons per capita per day. However, it was noted that the flow of 117 gallons per capita per day included commercial and industrial flows. In the computer model, the commercial and industrial zones are assigned a flow representative of the zoning classification and therefore these flows must be subtracted from the flow of 117 gallons per capita per day. Based on the commercial and industrial areas and flows used in modeling the system, the total daily flow attributed to commercial and industrial zoning areas is 1.01 million gallons per day. Therefore, the domestic component of the flow is estimated to be 1.64 MGD, which equates 72 gallons per capita per day. A design flow of 72 gallons per capita per day was used in the computer model. Commercial and industrial areas zoned M-1, M-2, and B-2 were assigned the flows per acre shown in table 4.6.1-1. In addition to the computed domestic flows, an infiltration allowance was assigned to the drainage areas. Table 4.6.1-1 lists the zoning classifications, population density for the zone classification, and the infiltration rates used for the model. As discussed in Section 4.2, the population density for each zone represents the actual density currently within that zone. The actual population densities are normally less than the allowable density based on the zone classification. However, the population densities reflect the actual densities based on census data. As was noted in Section 4.2, the densities are based on total land area within each zone, i.e. land for roads and other public land has not been deducted. - 50 - \\HKM\PROJECT\DATA\06W229124\CMC03717 DOC 08/16/98 @ 10:17 AM TABLE 4.6.1-1 MODEL INPUT ZONING CHARACTERISTICS BUSINESS & INFILTRATION/ RESIDENTIAL MANUFACTURING INFLOW Zone Population Zone Flow Flow Classification Density Classification Gallons/Acre/Da Class Gallons/Acre/Da R-1 3.81 M-1 2020 0 21,800 R-2 7.62 M-2 2020 1 5,200 R-3 12.19 B-2 3495 2 208 R-3A 12.19 3 3,000 R-4 12.19 4 2,100 R-0 12.19 5 500 R-5 2.54 6 1,500 7 1,000 8 150 The infiltration and inflow rates were determined based on the measured infiltration rates listed previously in Table 4.5.4-1. The measured rate was distributed to manholes included in the model. Appendix E contains the information used to establish the I/I flow rates. As I/I is reduced within the city, the modeled rates should be adjusted to reflect the new conditions. Also, if additional flow monitoring is completed, the modeled I/I rates should be adjusted to reflect the additional data. The flow from commercial (B-2) areas was estimated at 3495 gpd/acre. This estimate was based on commercial water use records reported in Amended Bozeman's Water Reservation Request (HKM, 1991). The existing collection system was modeled by breaking the system into six drainage zones. The drainage zones are shown, by line color of the pipelines, in Plate 4.4.1-1 bound in the back of the report. Plate 5.3-1 ,bound in the back of the report, also shows the existing and planned drainage zones. A Mannings friction factor of 0.013 was used for all pipe in the collection system. The Ten State Standards Formula was used to calculate the peaking factor for each pipe segment. This peaking factor uses service area population and is defined as follows: - 51 - H:\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 11:45 AM Qmax _ 18+ (P = Population/thousands) QAve 4+V-P 4.6.2 Analysis Results Zone 1 Table 4.6.2-1 shows the characteristics of drainage Zone 1 as modeled in the computer model. TABLE 4.6.2-1 ZONE 1-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 4583 Total Drainage Area Served 292.6 acres Estimated Average Day Flow/Zone 251 gpm (0.361 MGD) Estimated Peak Hour Flow/Zone 924 gpm (1.33 MGD) The Zone 1 drainage area consists of the area east of the City and drains the area east of Highland Boulevard and north of Kagy Boulevard. The hospital, medical office building and softball complex are included in this drainage zone. Based on population densities, the drainage zone currently serves a population equivalent of approximately 4583 persons. The peak hour flow for Drainage Zone 1 is estimated at 924 gpm. The model indicates that at current flows all the pipes in this drainage zone have adequate capacity. A pump station is located near the interstate exist east of the City. The pump station has a capacity of 450 gallons per minute. The station currently serves a small area north of the interstate along US highway 10. When the lift station is pumping. the pipelines down gradient of the station are near their capacity. With the pump running, the flow in the 10-inch PVC line between manholes C0507 and D0502 is estimated to be running at 75 to 85 percent of capacity at peak flows. The 14- inch lines from manhole D0508 to F0330 are also shown to be approximately at 89 percent - 52 - H:\DATA\06\M229124\CMC03717.DOC 08/20/98 @ 11:46 AM capacity. Expansion of the area that drains into these lines will require improvements to the collection system as discussed in Section 5.4 of this report. Zone 2 Table 4.6.2-2 shows the characteristics of drainage Zone 2 as modeled in the computer model. TABLE 4.6.2-2 ZONE 2-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 2048 Total Drainage Area Served 218.2 acres Estimated Average Day Flow/Zone 135 gpm (0.194 MGD) Estimated Peak Hour Flow/Zone 395 gpm (0.569 MGD) The Zone 2 drainage area consists of the area west of town. The area is bounded by Huffine Lane on the south and Ferguson Road on the west. This drainage zone currently consists primarily of the Valley Unit Subdivision, which drains into the 24-inch collector on North 19th Street. The drainage area currently consists of approximately 218 acres. Zoning in the drainage area is primarily residential housing consisting of R-2, R-3, and R-4 densities. The computer model indicates that all lines in this area have adequate capacity at current flow rates. The majority of lines are at less than 50 percent of capacity. The 8-inch line that runs east and west on Babcock Street is at 50 to 70 percent of capacity during peak hour flows. The Far West Trunk line, which serves as the major trunk line draining Zone 2, is at approximately 23% of capacity in the most restricted portion of the trunk line. The Far West Trunk has adequate capacity to increase the current service area of the trunk line. Expansion of the service area as shown in plate 5.3-1 will require the construction of additional relief sewers and/or ups izing of existing lines as discussed section 5.4 of this report. - 53 - H:\DATA\O6\M229124\CMC03717.DOC 08/20/98 @ 11:47 AM Zone 3 Table 4.6.2-3 lists the characteristics of drainage Zone 3 as modeled in the computer model. TABLE 4.6.2-3 ZONE 3-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 10,277 Total Drainage Area Served 711.8 Acres Estimated Average Day Flow/Zone 826 gpm (1.19 MGD) Estimated Peak Hour Flow/Zone 1926 gpm (2.77 MGD) Zone 3 is a fairly large zone that drains the west side of the City. The zone is bounded on the south by Kagy Boulevard and on the north by Durston Road. The drainage area is approximately 712 acres. Zoning in the drainage area is primarily residential housing. Small business zones are served along West Main Street. Based on zoning densities the population equivalent served by Zone 3 is approximately 10,277 persons. The computer model developed for drainage Zone 3 indicates an average day flow of approximately 826 gallons per minute and a peak hourly flow of approximately 1,926 gallons per minutes for this zone. The area drains into a 15-inch collector line on Durston Road. The 15-inch collector increases to 18-inches north of Durston. The 18-inch collector line flows into a 24-inch main. The model indicates that the 15-inch collector on Durston from North 20th-to North 17th (western subdrainage) is undersized and will surcharge at peak hour flows. ne capacity of the 15-inch collector is approximately 1,122 gpm while the projected peak hour flow is 1,535 gallons per minute. The 18-inch collector that runs down North 17th from Durston to the 24-inch collector is also undersized and will surcharge during peak hour flows. The capacity of the 18-inch collector is 1,634 gallons per minute while the projected peak hour flow is 1925 gallons per minute. Drainage Zone 3 does appear to have a substantial flow from groundwater infiltration. Referring to Table 4.5.4-1, it is shown that the groundwater infiltration at Manhole H0302 (western subdrainage) is estimated at 120 gpm. The groundwater infiltration from the eastern drainage area - 54 - H:\DATA\06\M229124\C MC03717.DOC 08/20/98 @ 11:48 AM is estimated at 200 gpm from the measured flows at manhole H0305. The combination of measured flows of manholes H0302 and H0305 result in a total infiltration flow of 320 gallons per minute in Zone 3. Even with the elimination of 320 gpm of infiltration flow, the 15-inch line on Durston and the 18-inch line north of Durston would still be at capacity during peak hour flows. In addition to the lines that are projected to surcharge during peak hour flows there are several segments of line that are above 75 percent of full capacity. The 8-inch and 10-inch line between South 19th and South 20th from West College to Durston appears to be at approximately 80 percent of capacity during peak hour flows. Zone 4 Table 4.6.2-4 shows the characteristics of drainage Zone 4 as modeled in the computer model. TABLE 4.6.2-4 ZONE 4-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 4990 Total Drainage Area Served 610.7 Acres Estimated Average Day Flow/Zone 494 gpm (0.711MGD) Estimated Peak Hour Flow/Zone 1055 gpm (1.52 MGD) Drainage Zone 4 comprises a large drainage area that extends from the southern edge of the City, including the Westridge Subdivision, to Babcock Street. From Babcock Street, a 24-inch main extends north to the Interstate near the new North 19th Interchange. Based on zoning densities, the area serves a population equivalent of approximately 4,990 persons. The computer model indicated all the lines in this drainage zone have adequate capacity at the existing peak hour flows. However, the 12-inch line from the intersection of Hoffman Drive and Tracy Avenue to South Willson is at approximately 70 percent of capacity at peak hour flows. - 55 - H:\DATA\O6\M229124\CMC03717.DOC 08/20/98 @ 11:50 AM Zone 5 Table 4.6.2-5 shows the characteristics of drainage Zone 5 as modeled in the computer model. TABLE 4.6.2-5 ZONE 5-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 2984 Total Drainage Area Served 195.8 Acres Estimated Average Day Flow/Zone 346 gpm (0.498MGD) Estimated Peak Hour Flow/Zone 732 gpm (1.05 MGD) Drainage Zone 5 lies on the eastern side of the City. It runs parallel to Bozeman Creek and extends from Kagy Boulevard to Tamarack Street. The drainage area consists of approximately 158.2 acres of residential zoning and 37.6 acres of business zoning. Based on the zoning densities the area serves a population equivalent of approximately 2,984 persons. The majority of zoning in the drainage area is high-density housing consisting of R3, R3A, and R4 zoning. The area also appears to have a substantial amount of groundwater infiltration. Based on flow measurements shown previously in Table 4.5.4-1, groundwater infiltration in this drainage zone is estimated at approximately 185 gallons per minute. Results from the computer model indicate the 8-inch line from manhole E0510 to F0439 (Rouse from Olive to Lamme) is under sized at peak hour flows. Surcharging of the line is likely during peak hour flows. Even if the groundwater infiltration could be eliminated, the majority of the lines would still be undersized. To meet existing flow rates, the line from manhole E0510 to manhole F0439 should be replaced with a 10-inch line. However, in order to meet the flows projected from new growth in the southern portion of Zone 5 a new 24-inch trunk line is required. The routing for the 24-inch line will require some additional survey work to determine the best alignment, but one possible route would fall along the line from manhole E0510 to manhole F0439. - 56 - H:\DATA\O6\M229124\C MC03717.DOC 08/20/98 @ 11:50 AM Zone 6 Table 4.6.2-6 shows the characteristics of drainage Zone 6 as modeled in the computer model. TABLE 4.6.2-6 ZONE 6-EXISTING SYSTEM MODEL CHARACTERISTICS Total Population Equivalent 12.984 Total Drainage Area Served 824.4 Acres Estimated Average Day Flow/Zone 1,194 gpm (1.72MGD) Estimated Peak Hour Flow/Zone 2,276 gpm (3.28 MGD) Drainage Zone 6 consists of a large drainage area that encompasses a significant portion of the center of the City. The main outfall lines to the wastewater treatment plant are included in Zone 6. The drainage area consists of approximately 640 acres of R2, R3, R3A and R4 zoning. In addition, the area contains approximately 128 acres of M1 zoning and 33 acres of B2 zoning. Based on zoning densities the area serves a population equivalent of approximately 12,984 persons. The majority of lines in this drainage zone are adequate at current flow rates. The model does indicate that a small section of 20-inch main on North Rouse between Birch Street and the interstate overpass (manhole E0212 to F0208) will surcharge during peak hour flows. The hydraulic model indicates the line will be approximately 4% over capacity at peak hour flows. From the slope information provided, it appears a short section of the line was placed on relatively flat slope. The 20-inch main outfall line in Zone 6 flows north on North Rouse to Griffin Drive. At Griffin Drive the line splits into two parallel 20-inch lines that flow northwest toward the wastewater treatment plant. At Manley Road the two 20-inch lines converge into a single 20-inch line for approximately 2500 feet. Following the 2500 feet of single 20-inch line, a segment of 30-inch line was recently installed as part of the new railroad overpass construction on North 7th Avenue. Following the 30-inch segment of line, the line again consists of two parallel 20-inch lines. - 57 - H:\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 11:52 AM The capacity of the outfall line is limited by the single 20-inch line that begins at Manley Road (manhole G0133 to manhole 40) and continues to the tie with the 30-inch line. The capacity of the 20-inch line is 5.69 MGD (3,950 gpm) while the estimated current peak flow is 5.66 MGD (3932 gpm). This indicates the line will be at capacity with the existing peak hour conditions. Groundwater infiltration in the line is estimated to be approximately 628 gallons per minute. This indicates that even if all the groundwater infiltration could be eliminated the line would still be at 84% capacity. This would leave little capacity for additional growth. It is also unlikely that all groundwater infiltration could be removed. Two parallel 20-inch outfall lines also converge to a single 20-inch line at Reeves Road. The single 20-inch line connects to a 30-inch line south of the wastewater plant. The capacity of the 20-inch line from Reeves Road to the 30-inch line is approximately 8.04 MGD. This is adequate under current conditions but may be limiting as growth occurs in Zones 1, 5, and 6. 4.6.3 Physical Condition The physical condition of the collection system was assessed by reviewing the City's maintenance records and interviewing the system superintendent. The lines listed in Table 4.6.3-1 were identified as being problem lines that require routine monthly maintenance. Solid deposition and plugging were the main problems. Many of the areas with solids deposition occur in the upstream end of lines where the liquid flow may not be great enough to prevent solids from settling. Plate 4.4.1-1, bound in the back of this report, shows the locations of the problem lines. As indicated, the majority of the lines are in the older section of the city and are primarily 6-inch lines. Current standards require a minimum line size of 8 inches. The small line size may contribute to line plugging especially if root intrusion is also present. City personnel indicated that root intrusion is a problem in the clay uie lines located between Babcock and Grant from Tracy to North loth. This constitutes a large area of the older part of town. Many of the lines were installed in the early 1900's. A TV inspection of the lines will be - 58 - \\H KM\P R O J E C T\DATA\06\M 229124\C M C 03717.D O C 08/16/98 @ 10:17 AM needed to verify the exact locations and extent of root intrusion. Areas of root intrusion may also be areas of high groundwater infiltration. - 59 - \\H KM\P R O J ECT\DATA\06\M229124\C MC03717.D O C O8/16/98 @ 10:17 AM TABLE 4.6.3-1 LINES REQUIRING ROUTINE MAINTENANCE LOCATION LOCATION Aspen-Front to Church Main-Black to dead end east of Tracy Main-Rouse to Bozeman Lamme-Wallace to Ida Main-Grand to 5'h Mendenhall-Ida to Church Grand-Babcock to Cleveland Alley south of Main-Wallace to Manhole East of 3rd-Olive to Koch Church Main-Rouse to Church 5th-Manhole South of Cleveland to Grant Church-Main to Story and 'h Block South of Story Olive-4th to 6 h Babcock-Church to Manhole East of Rouse 6th-Olive to Story Olive-Church to Manhole East of Rouse Story-6th to 7' Bogart place-Alley-Church to Manhole West of 7th-Story to Alderson Church Story-Bozeman to Dell Place Alley South of Story-7th to Alley West Black-Curtiss to College Alley Between 7th and Sth 'h Block South of Story to Dickerson Dickerson-Black to Dead End East Alley Between 7th and 8th 'h Block South of Babcock to 'h Block North of Koch Alley-South of Babcock-9th-to 'h Block East Manhole Behind UCT Building(Old Elks Club) R/W Between 8th and 9th-Story to Dickerson Lamme from 3rd to 7h Alley Between 9th and loth-Koch to Story 300 Block S. Tracy Alley between 9th and loth on Durston to Next Manhole Durston- 15th to County Rest Home West Alley between loth and 11th-Durston to Manhole South Mendenhall -3rd to 7' Alley Between 11th and 12th-Koch to Story Mendenhall -Willson to Grand Alley Between 14th and 15th-Story to Alderson Babcock-Alley West of 20th to Highway Ah- Olive to Next Manhole South Durston-20th to 21st S. 9th to S. 7th in Alley 'h Block South of Main S. 9th to 'h Block South of Main - 60 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.D OC 08/16/98 @ 10:17 AM Y C I ',is I ' I I � I:�' I I . � � '� �� r _ �_ _,� �. 4.7 WASTEWATER TREATMENT SYSTEM 4.7.1 Existing Effluent Quality In order to determine the performance of the existing treatment plant, the plant records were reviewed. Table 4.7.1-1 shows the quality of the effluent and how it relates to Bozeman's discharge permit. The parameters are well within the limits contained in the discharge permit. Copies of Bozeman's current and draft MPDES permits are included in Appendix B. TABLE 4.7.1-1 PLANT EFFLUENT QUALITY SUSPENDED SOLIDS BOD, AMMONIA SECONDARY I/P SECONDARY UP SECONDARY UP EFFLUENT EFFLUENT EFFLUENT EFFLUENT EFFLUENT EFFLUENT mg/1 mg/I mg/1 mg/1 mg/1 mg/I AVERAGE 5.4 1 3.2 1.09 0.44 0.057 MAXIMUM 16 3 11 2 9.81 0.30 MINIMUM 1 0 1 1 0.03 0.02 PERMIT LIMITS 30 day 30 30 25 25 7 day 45 45 40 40 " *Monthly mass loading limit-refer to Appendix A 4.7.2 Plant Description The Bozeman treatment plant is a complete mix activated sludge plant with a discharge to the East Gallatin River or to infiltration ponds. The pretreatment system consists of a mechanical bar screen, grit removal, and comminutors. Following the comminutors, the wastewater flows to two 65-foot center feed primary clarifiers. Effluent from the primary clarifiers is lifted to the aeration basins by) three 66-inch diameter screw pumps. Each pump has a capacity of 7,350 gallons per minute. Secondary treatment consists of four aeration basins and three secondary clarifiers. Flow from the secondary clarifiers flows through the chlorine contact chamber for disinfection. Sulfur dioxide is added at the end of the chlorine contact chamber for dechlorination. After the chlorine contact chamber, the flow can be discharged either to infiltration/percolation (I/P) ponds for - 61 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM additional ammonia removal or to the East Gallatin River. An underdrain system collects a portion of the underdrain water from the I/P ponds for discharge into the East Gallatin River. Sludge collected in the primary clarifiers is pumped to a gravity thickener before being pumped to an anaerobic digester. Sludge generated in the secondary treatment process is pumped to a flotation thickener before being pumped to the anaerobic digesters. Sludge from the anaerobic digesters is pumped to sludge storage ponds. The sludge is land injected during the summer. Figure 4.7.2-1 shows a process flow diagram for the wastewater treatment system. Table 4.7.2-1 lists the design flows and loadings for the wastewater treatment plant (TDH, 1980). TABLE 4.7.2-1 EXISTING PLANT DESIGN CRITERIA AND EXISTING CONDITIONS DESIGN EXISTING Population 36,062 22,660 Flow Average Day - MGD 5.784 5.03 Maximum Day - MGD 7.32 10.01 BOD5 Loading Average Day-lbs./day 8,574 4,976 Maximum Day-lbs./day 16,022 11,243 TSS Loading Average Day-lbs./day 7,219 4,134 Maximum Day-lbs./day 13,280 6,940 - 62 - \\H KM\P R O J E C T\DATA\06\M 229124\C M C 03717.D O C 08/16/98 @ 10:17 AM f-Z Z Y�r d' NF-yd'� 3 Off! W J W W J> r A V J O¢� O<� 04 N �Z CE � TW W CL w x Z w <•Z„ x < D 11(� N o Z< a a c� z of vi Uvm a ui LL �W N z 3 0 2 O O J Co F- (A � W J H 3 J 0 a a w w w o acr ali ali U U U za OZ OZ JJ Z min min a w m ui I < J a a CO z Z _ O Z O Z I C Wm ui I I wui 0N < _ a a I ciao Q — o0z LL �00 — - Wa I N Na a: — — — � Q o� w �U- ON Q CO �< z� O; 5 W au i aa- oW We Z CU aY Q O w O~ Q. � k I L� / \ O ca }W }� o ~W a~ > U crO U w Z O }w �O U m _ , • � � l;. 1� �• - - r r I I ',`. .? 't. �.^ As shown in Table 4.7.2-1, the plant is operating well below the design criteria with the exception of flow. While existing organic and solids loading are below the design criteria, the existing average day flow is near the design value and the existing maximum day flow has exceeded the design value. 4.7.3 Treatment Plant Evaluation The treatment plant performance was evaluated in 1987 and in 1994 by the Montana Department of Health and Environmental Sciences. Copies of the evaluation reports are included in Appendix D. The results of the performance evaluations completed by the Department of Health and Environmental Sciences are discussed below. The 1987 study noted that the inability of the rapid infiltration basins to consistently provide fecal coliform removal was the most limiting factor in the plant's ability to meet discharge permit levels. Since 1987 the plant flow scheme was modified to allow the effluent to be chlorinated and dechlorinated before being applied to the rapid infiltration basins. Since the plant modifications, the permit levels for fecal coliforms have been met. The 1987 comprehensive performance evaluation (CPE) also noted that a solids accountability analysis indicated inconsistencies in the solids data. The data suggested that the mass of solids wasted to the thickener was significantly less than that removed from the thickener. The 1994 CPE again noted an inability to perform a solids balance based on plant data. The CPE indicated the plant would benefit from flow meters on key sludge piping, such as thickened primary sludge and the thickened waste activated sludge. The 1994 CPE noted two conditions that were classified as "B" conditions. A "B" classification was defined as a factor that has a minimal adverse effect on a routine basis or a major effcet on a periodic basis. The two conditions noted in the 1994 CPE were (1) industrial plant loading and (2) ultimate sludge storage/disposal. - 64 - \\H KMT ROJ ECT\DATA\06\M229124\C MC03717.DOC O8/16/98 @ 10:17 AM The plant experiences periodic sludge loadings of high BOD5 waste. The average BOD5 loading is approximately 5000 pounds per day, compared to peak day loadings of over 11,000 pounds per day. Potential causes of the high loadings identified in the CPE included the following: • Uncontrolled/unmonitored discharges from a local dairy • Unapproved dumping of septage • Periodic unmonitored discharges from MSU While an attempt should be made to locate and identify any illegal dumping, it should be noted that the ratio of peak day BOD5 loading to average day BOD5 loading observed at the Bozeman plant is not unusual. Based on the existing data, the ratio of peak day BOD5 loading to average day BOD5 loading is approximately 2.2 to 2.5. This value is well within normal ranges (Metcalf and Eddy). Sludge storage and disposal were also identified as potential limiting factors at the treatment plant in the 1987 and 1994 CPEs. In order to address the deficiencies noted in the CPEs the City recently completed a sludge storage project to provide additional sludge storage volume. In addition to reviewing the CPE reports, MSE-HKM completed a separate evaluation of the treatment plant. The remaining portion of this section presents the results of the evaluation. Table 4.7.3-1 summarizes the equipment characteristics, physical condition, hydraulic capacity, and deficiencies of the treatment plant components. The deficiencies of the components are identified based on state criteria contained in Circular WQB-2 or typical design values when state criteria do not cover a specific component. Following Table 4.7.3-1, a performance potential graph is presented in Figure 4.7.3-1 that graphically illustrates the existing conditions, the design conditions, and current recommended design values based on state standards contained in Circular WQB-2 Design Standards for Wastewater Treatment Facilities published by the Montana Department of Environmental Quality. - 65 - \\H KM\P ROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM TABLE 4.7.3-1 CAPACITIES AND CONDITION OF TREATMENT PLANT COMPONENTS COMPONENT EQUIPMENT PHYSICAL STATE DESCRIPTION CHARACTERISTICS CONDITION CAPACITY CRITERIA DEFICIENCIES Bar Screens 1-42 inch mechanical Good Approximately 10.0 1.Clear space for 1. Parts screen MGD manually cleaned availability 1-42 inch manual screen screen shall be no Bar Spacing: 1'%inch clear less than 1-inch. space The maximum clear opening Dual Channels should be 1-3/4 inches. 2.Dual channels shall be provided. Grit Chamber Type: Horizontal Flow Good 12.9 MGD for 65 1.Horizontal velocity: 1 Diameter: 18 ft. mesh particle removal ft/s Primary Number: 2 Good Capacity=6.64 MGD I.Minimum sidewall Clarifiers Type: Center Feed at average day depth of 7 feet. Diameter: 65 Feet 9.95 MGD for peak Sidewall Depth: 8 Feet hour flows 2.Surface overflow rate: Surface Area: 3318 1000 gpd/ft2 at ft2/clarifier average flow, 1500 to 3000 gpd/ft2 at peak hourly flow. 3.Surface overflow rates shall include side stream flows. 4.Weir loading should not exceed 30,000 gpd/ft at peak hourly flow. Screw Pumps Number: 3 Good 7,350 gpm/pump 21.1 Diameter: 66-inches MGD with 2 pumps Aeration Basins Number: 4 Basins are in Organic Loading: 1.Organic Loading; 40 1. The basins Dimensions: 55 ft x 55 ft x good 9800 pounds Ibs BOD5 per are 20.25 ft/basin condition BOD5/day day/1000 ft3 near capacity in Volume/Basin: 458,200 Average day flow: terms of gallons 7.35 MGD F/M Ratio: 0.2-0.5 lbs. hydraulic loading. Total Volume=1,832,800 BOD5/day gallons Air Supply: 3-200 HP MLSS: 1000-3000 mg/I blowers Fine bubble diffusers PVC Air Line Air lines are in marginal condition - 66 - H:\DATA\06\M229124\CMC03717.DOC O8/20/98 @ 11:53 AM ;.. i f TABLE 4.7.3-1 (Continued) CAPACITIES AND CONDITION OF TREATMENT PLANT COMPONENTS Blowers Blower Rating: 2395 SCFM Blower capacity= 1.Aeration equipment 1. High Power at 10 psig @ 100°F inlet 17,000 pounds 02 per shall be capable of Cost temperature day with 2 blowers providing 1.1 Ibs 02/lb of B005 at peak hourly load. With nitrifi-cation the nitrogen oxygen demand shall include 4.6 times the peak TKN load. 2.Blowers shall meet the maximum air demand with the largest unit out of service. Final Clarifiers Number: 3 Peak hour flow of 9.9 1.Surface Overflow Type: Centerfeed Good MGD based on Rate: 1000 gpd/ftz Diameter: 65 ft. surface overflow rate. at peak hour Sidewall Depth: 12 ft. Surface Area: 3318 ftZ/clarifier Hydraulic sludge recycle 2.Peak Solids Loading 50 Ibs/day/f:2 for conventional treatment, 35 Ibs/day/f?for single stage nitrification. 3.Weir loading shall not exceed 30,000 gpd/ft2 at peak hourly flow. Chlorine Length to Width Ratio: 81:1 Good 26.6 MGD at peak 1.Minimum contact time Contact Basin Volume: 277,100 gallons hour flow. of 15 minutes at peak hourly flow. 2.Baffling shall be provided on tasks not provided with continuous mixing. - 67 - H:\DATA\06\M229124\CMC03717.DOC 08/20/98 @ 11:54 AM '�I� �+ ' •-� . � � ` � �I `. �I' .: :; �r: �i ,: �. �' P :; 7 � � I , i TABLE 4.7.3-1 (Continued) CAPACITIES AND CONDITION OF TREATMENT PLANT COMPONENTS Infiltration/ Number: 19 Dikes in Approximately 5 MGD 1. Plugging of Percolation Infiltration Area: Approx. 49 good ponds Ponds acres condition 17 and 19 Design Flow: Max. 5.78 MGD Hydraulic condition is marginal Gravity* Number: 1 Good Solids loading of 1.Solids loading 20-30 Thickener Diameter: 35 feet 28,900 pounds/day Ibs/day/ftz Depth: 10 feet 3 inches Current loading is approximately 2461 pounds/day 2.0verflow Rate: 760 gpd/ft2 Flotation Number: 1 Good Solids loading of 1.Solids loading 5-15 Thickener Diameter: 30 ft. 10,590 pounds/day. Ibs/ft2/day Compressors: 2 Current loading is 3600 pounds/day Primary Number: 1 Good VSS loading=6,700 1.1-oading: upto 80 1. Lack of Digester Type: Anaerobic pounds pounds of VSS per insulation on Diameter: 50 ft. 1000 cubic feet. digester Volume: 418,600 gallons Hydraulic loading= results Fixed cover 27,000 gpd 2.15 day solids in excessive detention time at 35 heat loss to 55 degrees Celsius Secondary Number: 1 Good Digester Diameter: 35 ft. Volume: 205,100 gallons Sludge Storage Number: 2 Good 1. Range of 300 to 360 Basin Volume: 5 million gallons days storage Sludge Number of Trucks: 2 Good 1. See discussion on None Application Trucks: 6000 gal, each Federal regulations Equipment Number of Injection Trucks: section 1 Volume of Injection Trucks: 3500 gal. *The state has not established design criteria. Criteria shown is based on typical values used in design. Pretreatment. The pretreatment system consists of a mechanically cleaned bar rack and a horizontal flow grit chamber, followed by comminutors. A manually cleaned bar rack is also provided as a back-up unit. - 68 - H:\DATA\06\M229124\C MC03717.DOC 08/20/98 @ 11:54 AM i - --. i i ii 1� 1, r; �~ _ .._ .�. f�� ^. �� r• �� 1 fi MH . ` - . � ,� t� COMPONENT (FLOW-MGD) 4.0 4.5 5.0 6.0 7.0 6.0 9.0 10.0 NOTES (LBS BOD 5 /DAY) 4,739 5,290 6,348 7.405 8,463 9,521 10,579 EXISTING CONDITION 1. Rated to 25ft2/mgd for 65 mesh partical removal. BAR SCREEN ' 2. Firm copocity based on one pump out of service. MGD ( PEAK DAY ) 3. Based 'on 5X BOD5 removal of influent BOD in GRIT CHAMBER I primary clarifiers. The 5X removal. based o,� influent FT 2/MGD >J 1 I 4 40 *2MGD accounts for the added side stream loads. PRIMARY CLARIFIERS I 4. Based on suppling 2.0 pounds 02 per pound of BOD2 applied. Based on using 2 blowers. S.O.R. GPD/FT2 AT AVG. DAY 6 7 3 9 1,054 5. Based on a MLSS concentration of 3.000 mg/I SCREW PUMPS J 6. Based on sludge yield of 0.84 pounds solids FIRM CAPACITY MGD 1.1 D produced in aeration basin per pound of BOD AERATION BASINS I removed. Assumed constant effluent of 5 20 mg/I GODS. LOADING, CBODS/KEF/DAY J 0.5 2 6 9 40.0 7. Based on 34X removal of influent TSS in HDT - HRS 11 0 8 7 3 primary clarifiers. Thickener rated to 20 J pounds TSS/ft2/day for primary waste only. OXYGEN LBS 02/LB CBOD 5 1.87 SECONDARY CLARIFIERS I 8. Capacities based on primary digester volume. S.O.R. GPD/FT2 AT AVG. DAY 400 I 5 2 603 7 3 OU 9. Rated to 80 pounds VSS/1000 ft3. 2 �I SOLIDS LOADING LBS/DAY/FT 10.0 15.0 7. .0 22.0 10. Rated based on providing 238 days of storage 25.1 5.0 with no supemating of solids from the digesters. FLOTATION THICKENER I SOLIDS LOADING LBS/FT2/DAYJ 5.311,14 .4 8.4 10. 15.0 GRAVITY THICKENER I SOLIDS LOADING LBS/FT2/DAY7 DIGESTERS - I SOLIDS DETENTION TIME - DAYS 29 4 21 18 1 14.6 w LOADING LBS VSS/KCF J 69.3 83.2 SLUDGE STORAGE 101 I DAYS 218 238 CAP.DWG ' BOZEMAN WASTEWATER FACILITY PLAN FIGURE 4.7.3-1_j BOZEMAN WASTEWATER PLANT 11 -I41IC111 COMPONENT CAPACITIES ENGINEERING 6M229.124 AUG. 1998 � t _ • � �' I.� _ i .I ,_ The hydraulic capacity of the existing mechanical bar screen is approximately 10.0 MGD. At flows of 10.0 MGD the flow is close to overflowing into the bypass channel to the manually cleaned bar screen. While the mechanical bar screen has functioned well since it was installed in 1982, obtaining parts may be difficult as the equipment ages. The bar screen was custom fabricated for the Bozeman plant and the manufacturer is no longer in business. The grit chamber capacity depends on the desired particle size removal. Typically, grit chambers are designed to remove particles larger than 65 mesh (0.21 min. diameter). Based on this criteria the chamber has a capacity of 12.9 MGD. At higher flow rates, the removal efficiency will decrease. Primary Clarifiers. The treatment plant contains two 65-foot diameter center feed clarifiers. The clarifiers have a sidewall depth of 8 feet. Treatment plant records from 1990 through 1992 indicate the primary clarifiers remove approximately 34% of the TSS and 3% of the BOD5. The removal percentage is based on the plant influent concentration. Primary clarifiers will typically remove 50 to 70 percent of the total suspended solids and 25 to 40 percent of the BOD5. The apparent low removal rate is most likely due to side streams entering the process ahead of the primary clarifiers that are not being measured in the influent sample. Side streams ahead of the primary clarifiers include the gravity thickener supernatant and the flotation thickener subnatant. A mass balance around the primary clarifiers and gravity thickener indicates that sidestream loading from the gravity thickener overflows may be increasing the loading on the primary clarifiers by 25%. It is estimated the sidestream loading amounts to approximately 1,200 pounds of TSS per day compared to the 3,700 pounds per day measured in the influent. When the addition sidestream loading is accounted for, the TSS removal rate in the primary clarifiers is approximately 50%. '11tere are a variety of recommended overflow rates for primary clarifiers. Montana generally follows Circular WOB 2 Design Standards for Wastewater Facilities which recommends the surface settling rate should not exceed 1000 gpolfC at the average day flow or 1500 to 3000 gpd/ft' at peak hourly flows. At overflow rates above 1500 gpolfe, the BOD5 removal rate will decrease - 70 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM significantly. Using these criteria, the existing primary clarifiers have a capacity to handle average day flows of 6.64 MGD and peak hourly flows of 9.9 MGD. At the current average annual flow rate of 5.03 MGD (January-December 1993), the primary clarifiers have an overflow of 758 gpd per square foot. Aeration Basins. The treatment plant has 4 square aeration basins. Each basin has a volume of 0.454 MG at the maximum water depth of 20 feet. Fine bubbler aeration is provided by a grid of 682 ceramic diffusers located at the bottom of each basin. The diffusers are mounted on a grid of PVC air lines. Three 200 horsepower blowers are available at the plant. Two blowers are a model 100200-H manufactured by Spencer Air System. The third blower is a 200 horsepower positive displacement blower manufactured by Tuthill Corporation. The positive displacement blower was installed as an energy conservation measure. Each blower has a capacity of 2,395 standard cubic feet per minute. With the fine bubble diffusers, the system can transfer approximately 17,000 pounds of oxygen per day using two blowers. The City has reported that the PVC air lines in the bottom of the aeration basin are in marginal condition with several minor leaks evident. Table 4.7.3-2 shows the permissible loadings, based on the state criteria contained in Circular WQB 2, and the actual loadings. TABLE 4.7.3-2 PERMISSIBLE VERSUS ACTUAL LOADING ON THE AERATION BASINS STATE CRITERIA ACTUAL' Organic Loading - Pound BOD5/day/1000 fe 40 25.5 F/M Ratio - Pound BOD5/day/pound MLVSS 0.2-0.5 0.20 MISS - mg/l 1000-3000 2723 'Based on actual number of basins in operation. For the majority of 1992, three (3) basins were used. As indicated, the aeration basins are well within the state criteria for loading. - 71 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM Bozeman's MPDES Discharge Permit limits the amount of ammonia that can be discharged into Gallatin River. The plant was designed for the ammonia removal to be accomplished in the infiltration/percolation ponds. With the current plant operation, almost all the ammonia is being removed in the aeration basin. The average ammonia concentration in the secondary effluent is approximately 0.40 mg/l. With such a high level of nitrification in the aeration basin, the discharge permit levels for ammonia can be met without using the infiltration/percolation ponds. All other things being equal, it would be expected that the level of nitrification would decrease during the winter due to the lower temperature. This temperature effect is in fact observed with effluent ammonia levels increasing to approximately 1.0 to 1.8 mg/1 - NH3 during the winter from the summer levels of 0.05 mg/1 - NH3. Even the winter ammonia concentrations indicate a high level of nitrification is occurring. Blowers. Air for the aeration basins is currently supplied by three 200 horsepower blowers. The blowers each have a rated capacity of 2395 standard cubic feet per minute at 10 psig. Since nitrification is being achieved in the aeration system, the blowers must be capable of supplying both the BODS and nitrogen oxygen demand. Calculations indicate with two blowers the diffusers are capable of transferring approximately 17,000 pounds of oxygen per day to the wastewater. The current peak hour oxygen demand is estimated at 15,000 pounds per day. In addition to meeting the oxygen demands, the blowers must provide enough volume of air to meet the mixing requirements. With 3 and 4 basins in operation, the required air supply is 1820 ft3/minute and 2427 W/minute respectively. Each blower has a capacity of 2395 fe/min. Therefore, when four basins are in operation the use of a single blower is marginal in regard to mixing. An energy evaluation study completed in 1994 (Energy Resource Management, 1994) indicated that the operation of the blowers account for 65% ($66,000) of the total energy costs for the wastewater - 72 - \\H KM\P R OJ ECT\DATA\06 W1229124\CMC03717.DOC 08/16/98 @ 10:17 AM plant. The study recommended changing out one of the existing three centrifugal blowers to a rotary positive displacement blower with a variable speed drive. The cost of the modification was estimated at $87,486 and the yearly cost saving was estimated at $23,800 per year. The City implemented this recommendation. Secondary Clarifiers. The Bozeman plant has three 65 foot diameter clarifiers. The clarifiers are a center feed type clarifier with hydraulic return arms located on the bottom scrapers. A sludge hopper is located in the center of the tank floor. Waste sludge is pumped from the sludge hopper to a flotation thickener. The plant records, and a solids balance around the final clarifier, indicate a waste sludge solids concentration of approximately 1.0 percent; a typical value for this type of plant. While the clarifiers appear to be in good physical condition, the basins were not drained due to the high flows. Therefore, the condition of the submerged concrete and equipment has not been determined. The state has established criteria for final clarifiers based on surface overflow rates and peak solids loadings. Since the Bozeman plant is accomplishing single stage nitrification, the peak hour overflow rate criteria is 1,000 gallons/day/ft . At this overflow rate the peak hour flow limit is 9.9 MGD. During storm events, the existing flows have reached 10.0 MGD. The existing solids loading rate on the clarifiers is 16.2 pounds per day per square f6ot. State criteria allows a solids loading rate of 35 pounds per day per square foot. Therefore, the clarifiers are lightly loaded with regard to solids but may be hydraulically overloaded during high flow periods. Chlorine Contact Basin. The chlorine contact basin is constructed as a six channel basin and has a total volume of 277,100 gallons. Either the first 4 channels or the last 2 channels can be taken out of service for maintenance. The configuration of the basin provides a length to width ratio of - 73 - \\H KM\PR OJ ECT\DATA\06W229124\CMC03717.DOC 08/16/98 @ 10:17 AM approximately 13.9 to 1 in each channel. This configuration promotes plug flow, which is desirable in the contact chamber. State criteria requires 15 minutes of detention time at peak hourly flows. With the full basin in use, the basin has a peak hour capacity of 26.6 MGD. At the current peak hour flow of approximately 10 MGD, the chlorine contact basin provides a detention time of approximately 40 minutes. Infiltration/Percolation Ponds. A series of infiltration/percolation ponds provide ammonia removal and final effluent polishing. The rapid infiltration system was designed to be used on a seasonal basis (June through September) primarily to remove ammonia (via nitrification) and fecal coliforms. From June to September, flow in the receiving stream is very low. Ammonia removal is needed to prevent ammonia toxicity to the fish in the receiving stream. Recently, however, the ammonia limits have been met through the aeration basins and the infiltration/percolation ponds have not been routinely used. There are 19 ponds in the system, 15 of the basins are rectangular in shape (about 250 x 450 ft.), each with an infiltration area of about 2.6 acres. A total area of approximately 44.5 acres is available for infiltration. A sketch of the infiltration pond area is provided in Appendix D. The underdrain piping is on 40-foot centers under the basins. Of the 19 basins only 16 basins provide effective infiltration. Basins 17, 19 and 11 infiltrate very slowly and are not used. All of the basins are grass covered to help sustain adequate infiltration and to avoid sealing of the infiltration surfaces with fine silt if bare soil had been used. The 1987 performance evaluation indicated the IT ponds failure to effectively remove fecal coliforms was a major limiting factor in the plant's ability to meet the discharge permit. In order to address the issue, the city modified the plant flow scheme to allow chlorination of the water before being discharged to the I/P ponds. Since the modifications were completed, the discharge from the UP ponds has met the fecal coliform discharge permit limits. - 74 - \\H KM\PR OJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM As mentioned, basins 11, 17, and 19 are virtually plugged. In 1991 a soil amendment project added gypsum to pond 17 in an attempt to increase the infiltration rate. The plant staff has indicated very little, if any, sustained improvement was observed in the infiltration rate. However, it was also noted that wind drift may have blown the majority of gypsum off-site before it could be plowed into the soil. Gravity Thickener. -Solids from the primary clarifiers are pumped to the gravity thickener before being pumped to the anaerobic digester. The primary sludge pumps transfer sludge from the primary clarifiers to the gravity thickener at a rate of approximately 250 gpm. The gravity thickener consists of a 35 foot diameter tank with a sidewall depth of 10 feet-3 inches. Typical designs for gravity thickeners are based on maximum overflow rate and solids loading. The maximum pumping rate, based on overflow rate, is 507 gpm. Therefore, the current pumping rate could be doubled before the gravity thickener would be hydraulically overloaded. The allowable solids loading is approximately 20-30 pounds per day per square foot. The current loading is approximately 2 to 3 pounds per day per square foot. The existing gravity thickener is lightly loaded and no deficiencies were found. Flotation Thickener Waste sludge, from the secondary clarifiers, is pumped to a dissolved air flotation (DAF) thickener to thicken the sludge before the sludge is pumped to the digester. The flotation thickener is 30-feet in diameter with a surface area of 707 square feet. Two air compressors are available to add air to the system. The maximum recommended loading rate for DAF thickeners is in the range of 10.6 to 24 pounds/day/ff2. The DAF at Bozeman is currently loaded at a rate of approximately 5.1 pounds per day. Therefore, the DAF has adequate capacity for the future. - 75 - \\HKM\P ROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM The final clarifier waste sludge is entering the DAF at approximately 1% solids and is being thickened to approximately 4% solids. This is within the range of expected concentrations. The plant data indicates inconsistencies in the solids balance around the flotation thickener. The data shows an average of approximately 3600 pounds of solids per day being pumped to the DAR The data also indicates approximately 17;130 gallons per day is pumped to the digesters but only 13,900 gallons per day flows out of the digester. The solids mass and volume discrepancy is most likely due to an overestimation of the solids pumped from the flotation thickener. Solids from the flotation thickener will contain a large volume of entrained air. The density of DAF solids is typically around 6 pounds per gallon. This indicates that the solids from the DAF contain approximately 28 percent entrained air. If the reported volume pumped from the DAF (12,850 gpd) is reduced by 28% the volume balances within 350 gallons per day. The volume of sludge pumped is currently estimated by multiplying the pump run time by the rated capacity. A flow meter, installed on the sludge line to the digester would provide a better estimate of the sludge volume pumped. However, even the flow meter may overestimate the volume pumped due to the entrained air. A progressive cavity (Moyno) pump was installed in 1995 to pump solids from the flotation thickener to the digesters. The progressive cavity pump replaced a diaphragm style pump. Anaerobic Di eg sters. The Bozeman plant contains a 50 foot diameter primary digester and a 35 foot diameter secondary tank. The primary digester has a fixed cover while the secondary tank has a floating gas holding cover. The primary digester has a volume of 56,000 cubic feet and the secondary digester has a volume of 27,400 cubic feet. Under current loading and operating conditions, the primary digester provides a hydraulic detention time and solids residence tirrie of approximately 30 days. A 30 day detention time is adequate to meet both state and federal requirements. Under federal regulations, a residence time of 15 days at 35°C is required for the anaerobic process to be considered as a process to significantly reduce pathogens. - 76 - \\H KMTROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM The gas production in the digesters averages approximately 48,000 cubic feet per day. This equates to a gas production rate of approximately 11 cubic feet per pound of volatile solids added, which is within the typical range of 8 to 12 cubic feet per pound. While piping is available to decant the supernatant back to the head of the plant, it is not being used in the current operation. Decanting would allow the solid residence time to be increased in the digesters but the quality of the plant effluent would likely deteriorate due to the increased solids loading. The volatile solids loading on the existing digester system is approximately 50 pounds volatile solids per day per 1000 cubic feet. State design criteria allows a loading rate of 80 pounds per day per 1000 cubic feet. Higher rates may also be allowed if justified by design conditions. Typical design values range up to 160 pounds volatile solids per 1000 cubic feet at peaking loading rates. Boilers. Two boilers are used to heat the majority of the plant buildings. The boilers can operate off of either digester gas or commercially purchased natural gas. One boiler is located in the control building and is used to heat the primary digester and several areas in the control building. The second boiler is used to heat the aeration building, the flotation thickener building and lift station 2. The total heat requirement for the systems heated by the boilers is approximately 1.7 million BTU's/hour. The heat capacity of the digester gas is approximately 1.2 million BTU's/hour. This indicates that during extremely cold conditions the digester gas will have to be supplemented by commercial gas. The digesters are not insulated which significantly increases the heating requirements during cold weather. Insulating the primary digester with 3-inches of insulation would reduce the total heating requirements by 20 percent. However, since the digester is heated with digester gas in all but extremely cold conditions it is not cost effective to insulate the digester. - 77 - \\H KM\PROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM Plant personnel indicated that during prolonged periods of cold weather (-20 - 30°F) they have had problems maintaining a temperature of 95T in the primary digester. Calculations indicate that the boiler has adequate capacity. However, the heat exchanger may not have the heat exchange capacity required. It was indicated that during cold weather the sludge temperature on the outlet side of the heat exchanger will not reach 95T. The heat exchanger is approximately 24 years old and scale deposits on the sludge and water tubes may be reducing the heat transfer capacity. Apparently, parts for the heat exchanger are no longer available. The tubes on the heat exchanger should be inspected for any scale or sludge buildup. The replacement of the heat exchanger should be included in the plant capital expenditure budget in the near future. The estimated cost to replace the heat exchanger is $10,000 to $15,000. The underground piping used to heat the aeration building apparently has a leak of approximately 2000 gallons per day. If the leak cannot be located it may be necessary to run new heating lines. The use of digester gas to fire a boiler is the most common heat source for anaerobic digesters. Depending on the quality of the digester gas, scrubbing of the gas may be necessary before it is burned. The most common scrubbing requirement is the removal of hydrogen sulfide. Digester gas, high in hydrogen sulfide (greater than 100 ppm), can result in corrosion problems in the boiler. While the composition of the digester gas at Bozeman is not routinely tested, excessive corrosion in the boiler has not been a problem. Aerobic Di eg ster. When the plant was expanded in 1982, the existing aeration basin was converted to function as an aerobic digester to digest the waste activated sludge. The basin has a depth of 19 feet, a diameter of 50 feet and a volume of 279,435 gallons. The original design concept indicates that a pumping facility was planned that would allow sludge from the aerobic digester to be pumped to the sludge storage basins. The pumping facility was not constructed and the basin has never been used. The aerobic digester has the capacity to treat a flow of approximately 4,600 gallons per day under the current Federal pathogen reduction criteria. - 78 - \\H KM\PROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM Sludge Storage Basins. From the digesters, sludge is pumped to two sludge storage basins. The City recently completed an expansion of the sludge storage basins to provide a total storage capacity of 5.0 million gallons. In the expansion project, the center levee between the old ponds was removed and the material from the levee was used to raise the bottom of the ponds 5-feet. In addition, a new 1.57 million gallon sludge storage pond was constructed. Both ponds were lined with a 45-mil reinforced polypropylene liner. On an annual basis approximately 13,900 gallons per day is pumped to the storage basins from the secondary digester. This results in a total annual sludge volume of 5.07 million gallons that must be disposed of by subsurface injection. As noted previously, the secondary digester has provisions to decant supernatant but the decant is not used due to the impact on the effluent quality. Therefore, the volume pumped into the digesters from the gravity thickener and flotation thickener equals the volume pumped to the storage basin. The amount of sludge storage required is based on the volume per day pumped to the basins and the number of storage days needed during the winter. Without decanting from the digesters, the volume pumped to the storage basin will be equal to the volume pumped into the digesters from the gravity thickener and the flotation thickener. The plant staff has indicated they can normally inject sludge from June 1st through September; a 122 day application period. With a 122 day application period, adequate sludge storage for 238 days must be available. At current loading rates the storage basins provide 360 days of storage. Land Application System. During late spring, summer, and early fall (about 5 months total), sludge is withdrawn from the storage basins and land applied. Sludge stored over the winter and sludge produced during the land application period are both land applied using subsurface injection. As indicated previously, annually a total of approximately 5.07 million gallons of sludge is produced. Currently, two landowners accept sludge on their land. On an annual basis approximately 225 acres to 275 acres is available for land injection. The current application rate is - 79 - \\H KM\P R OJ ECT\DATA\06\M229124\C M C03717.D O C 08/16/98 @ 10:17 AM approximately 1.1 to 2.5 metric tons per hecture. The land application sites are up to 12 miles from the WWTP site. Two 6,000 gallon tanker trucks are used to deliver the liquid sludge to the land application site. The sludge is loaded into an injection vehicle for subsurface injection to the agricultural land. Operators monitor the land application rates and report these loadings to the state. The sludge transport and injection equipment is aging and replacement equipment should be included the plants capital improvement budgets. The replacement costs have been estimated at $185,000 for a new injection truck and $110,000 for a new 6000-gallon transport truck. 4 7 4 Sludge Disposal Requirements Sludge generated must be disposed of in accordance with the recently adopted 503 regulations as promulgated by the Environmental Protection Agency February 19, 1993. The 503 regulation consists of general requirements, pollutant limits, management practices, operational standards, and requirements that address frequency of monitoring, record keeping and reporting. The regulations cover land application, disposal and incineration of sewage sludge. Appendix F includes additional information concerning the 503 regulations. Sewage sludge applied to land must meet limits for 10 pollutants. Ceiling and pollutant concentrations for these 10 pollutants are shown in Table 4.7.4-1. Sewage sludge cannot be land applied if any one of the pollutant levels exceed the ceiling concentrations shown. If the pollutant levels all are below the ceiling concentrations and one or more are above the pollutant concentrations, the sludge can be land applied but the cumulative concentrations must be monitored. The cumulative pollutant loading must not exceed the rates shown in Table 4.7.4-2. If the pollutant levels fall below the pollutant concentrations in Table 4.7.4-1, the sludge can be land applied without having to monitor the cumulative pollutant loadings. - 80 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM Pollutant monitoring data is also shown in Table 4.7.4-1 for Bozeman's sludge. The testing completed to date indicates that none of the ceiling concentrations have been exceeded which means that Bozeman's sludge can be land applied. The levels for molybdenum and lead were the closest to their ceiling concentrations and should be monitored closely. The pollutant limit for lead was exceeded which means that monitoring of cumulative loadings must be completed for all land application sites. The high lead and molybdenum only occurred in one monitoring sample and it is possible the high results were a result of a testing error by the contracted laboratory. - 81 - \\H KM\P R OJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM TABLE 4.7.4-1 CEILING CONCENTRATIONS FOR SLUDGE DISPOSAL CEILING BOZEMAN'S POLLUTANT CONCENTRATION SLUDGE CONCENTRATION' POLLUTANT mg/kg' mg/kg' mg/kg Arsenic 75 1.55 41 Cadmium 85 23.6 39 Chromium 3000 109 1200 Copper 4300 698 1500 Lead 840 640 300 Mercury 57 0.82 17 Molybdenum 75 63 (3) Nickel 420 134 420 Selenium 100 3.59 36 Zinc 7500 663 28W (1)Highest value report from test data taken 4/30/93,7/28/93,4/25/94,7/29/94,and 8/4/94 (2)Dry Weight Basis (3)EPA stayed the pollutant concentration for Molybdenum. In addition to the ceiling limits, sludge applied to agricultural land or forest lands must not exceed the cumulative loading rates or annual pollutant loading rates shown in Table 4.7.4-2. - 82 - \\HKM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM TABLE 4.7.4-2 CUMULATIVE AND ANNUAL SLUDGE POLLUTANT LOADING RATES CUMULATIVE LOADING RATE ANNUAL LOADING RATE POLLUTANT Pounds/Acre Pounds/Acre/Year Arsenic 36.6 1.78 Cadmium 34.8 1.69 Chromium 2,676.6 133.83 Copper 1,338.3 66.92 Lead 267.7 13.38 Mercury 15.2 0.76 Molybolenum 16.0 0.80 Nickel 374.7 18.74 Selenium 89.2 4.46 Zinc 2,498.2 124.911 The 503 regulations also specify management practices that must be followed in the land application process. The required management practices are summarized below. • Sludge shall not be applied if it is likely to adversely affect a threatened or endangered species. • Sludge shall not be applied to agricultural land, forest, a public contact site, or a reclamation site that is flooded, frozen, or snow-covered so that sludge enters a wetland or other waters of the United States. • Sludge shall not be applied to agricultural land, forest, or a reclamation site that is 10 meters or less from waters of the United States. - 83 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM • Sludge shall be applied to agricultural land, forest, a public contact site, or a reclamation site at a whole sludge application rate that is equal to or less than the agronomic rate. The 503 regulations also specify operational standards for pathogen and vector attraction reduction. When sludge is applied to land, either Class A pathogen requirements or Class B pathogen requirements must be met. The regulations list six alternatives that allow a sludge to be classified as Class A and three alternatives for a sludge to be classified as Class B. Basically, Class A sludge requires treatment to a higher level so that the density of fecal coliforms in the sewage sludge is less than 1000 Most Probable Number (MPN) per gram of total solids, or the density of Salmonella species in the sewage sludge shall be less than three MPN per four grams of total solids. (MPN - is a method of testing for fecal coliforms that gives a statistical value for the most probable number of coliforms in the sample). By meeting this Class A designation, the site restrictions identified for Class B sludges can be avoided. A Class B sewage sludge must have a fecal coliform density of less than 2,000,000 MPN per gram of total solids or 2,000,000 Colony Forming Units per gram'of total solids. A sewage sludge can also be classified as Class B if it is treated by a Process to Significantly Reduce Pathogens (PSRP). The PSRP include: 1. Aerobic digestion with a mean cell residence time and temperature between 40 days at 20 degrees Celsius and 60 days at 15 degrees Celsius. 2. Air drying for a minimum of three months. During two of the three months the ambient average daily temperature must be above zero degrees Celsius 3. Anaerobic digestion with a mean cell residence time and temperature between 15 days at 35 to 55 degrees Celsius and 60 days at 20 degrees Celsius. 4. Composting where the temperature of the sewage sludge is raised to 40 degrees Celsius or higher and remains at 40 degrees Celsius or higher for five days. For four hours during the five days, the temperature in the compost pile exceeds 55 degrees Celsius. 5. Lime addition sufficient to raise the pH of the sludge to 12 after two hours of contact. - 84 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM When the sludge is Class B with respect to pathogens, restrictions are imposed on the site where sewage is applied. Bozeman's sludge meets the Class B designation through anaerobic digestion. The existing digester provides a minimum of 15 days mean cell residence time at 35°C (one of the PSRP methods). Fecal coliform testing of the sludge confirms that the sludge meets one of the Class A requirements (51,000 MPN per gram). To meet the Class A criteria, however, the sludge must also meet one of the criteria listed below: ( See appendix F, pages 110-117 for further discussion on the six alternatives) Alternative 1 - Time and Temperature Alternative 2 - Reduce pH Alternative 3 - Reduce enteric viruses and helminth ova (low pathogen sludge) Alternative 4 - Reduce enteric viruses and helminth ova (normal sludge) Alternative 5 - Process to further reduce pathogens (PFRP) • Composting • Heat drying • Heat treatment • Thermophilic aerobic digestion • Beta Ray Irridation • Gamma Ray Irridation • Pasteurization Alternative 6 - Process to Future Reduce Pathogens (PFRP) equivalent treatment The site restrictions imposed by the 503 sludge regulations for Class B sludge are listed below: 1. Food crops with harvested parts that touch the sewage sludge/soil mixture and are totally above the land surface shall not be harvested for 14 months after application of sewage sludge. - 85 - \\H KM\P ROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM 2. Food crops with harvested parts below the surface of, the land shall not be harvested for 20 months after application of sewage sludge when the sewage sludge remains on the land surface for four months or longer prior to incorporation into the soil. 3. Food crops with harvested parts below the surface of the land shall not be harvested for 38 months after application of sewage sludge when the sewage sludge remains on the land surface for less than four months prior to incorporation into the soil. 4. Food crops, feed crops, and fiber crops shall not be harvested for 30 days after application of sewage sludge. 5. Animals shall not be allowed to gr��e on the land for 30 days after application of sewage sludge. 6. Turf grown on land where sewage sludge is applied shall not be harvested for one year after application of the sewage sludge when the harvested turf is placed on either land with a high potential for public exposure or a lawn, unless otherwise specified by the permitting authority. 7. Public access to land with a high potential for public exposure shall be restricted for one year after application of sewage sludge. 8. Public access to land with a low potential for public exposure shall be restricted for 30 days after application of sewage sludge. Typically, sludge is applied to summer fallow land and a crop is not harvested until the next year. The crops grown are normally wheat or barley. The site restrictions for class B sludge are being met. In addition to meeting the pathogen reduction requirements, one of ten vector attractor reduction requirements must be met for sludge being land applied. The possible methods for vector attraction reduction for land application include the following. 1. 38% volatile solids (VS) reduction 2. Bench test for low VS anaerobic sludge 3. Bench test for low VS aerobic sludge 4. Specific oxygen uptake rate (SOUR) <_1.5 mg OZ/hr/gr - 86 - \\H KMT ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 5. 14 days temp >40°C avg. temp>450C 6. pH > 12 for 2 hours and pH>11.5 for additional 22 hrs. 7. 75% dry solids (DS) (no primary treatment) 8. 90% DS 9. Subsurface injection* 10. Incorporation* *Cannot be used for sludges applied to lawn, home garden, sold, or given away. Subsurface injection is currently used to meet the vector attraction requirement. - 87 - \\HKM\PROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 5.0 FUTURE CONDITIONS 5.1 POPULATION PROJECTIONS Future population is the principal element in determining the amount of water used and the size of the water and sewer lines to be constructed in the service area. In addition to the total population number, the demographics of the future growth is important in locating and sizing public facilities. Areas that are outside the current city limits may be annexed into the city in the future. Annexation will generally require the extension of water and sewer service into the annexed area. In some instances water and sewer service may be provided to areas outside the city limits to promote a higher housing density. The city code requires a waiver of right-to-protest annexation prior to service outside the city limits. The future population to be served by the Bozeman facilities is projected from the trends of the recent census data. The data reflects the population growth rates within the Bozeman city limits and also the greater Bozeman area. The latter encompasses the area within the Bozeman city limits and extends beyond the city limits, roughly 4 miles. The greater Bozeman area is defined by the boundaries of the Bozeman, Belgrade and Gallatin Gateway census divisions. Because the greater Bozeman area contains a large amount of undeveloped land, whereas the area within the Bozeman city limits is a highly developed urban area, the two areas have had historically different growth rates during the past three decades. The growth rate in the greater Bozeman area has been larger than that within the Bozeman city limits during the past three decades. The population of the greater Bozeman area increased 18.2% from 1980 to 1990. This was below the historical rates of 34.4% experienced from 1970 to 1980 and 29.7% from 1960 to 1970. The growth rate of the city of Bozeman was 4.7% as shown in Table 4.1-1, during the 1980's. This was much lower than the rates of 39.7% and 15.9% in the 1960's and 1970's respectively. _ 88 _ \\H KM\PROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM The method of projecting the future population for the service area is based on the historic growth within the City of Bozeman, including areas that may be annexed in the future. Three curves for the growth are shown in Figure 5.1-1. The middle curve is used for the 20-year (from 1994) planning analysis of this study. The growth rate used the mean of a straight line projection and that of a compounded annual growth rate (CAGR) of 1.9 percent. The projected population for the City of Bozeman for the year 2014 is 32,551 persons. 5.2 WASTEWATER FLOW AND LOAD PROJECTION As discussed previously in Section 4.6.1 the domestic, commercial, and industrial components of flow are estimated to total 117 gallons per capita per day. Based on the 1990 census population of 22,660 persons this equates to a flow of 2.65 MGD. The domestic portion of flow is estimated to be 72 gallons per capita per day. When the flow of 2.65 MGD is divided by the drainage area of 2,921 acres the result is a flow of 907 gallons per acre per day, which includes domestic commercial and industrial flows. By dividing the flow of 907 gallons per acre per day by the per capita domestic flow of 72 gallons per day an overall equivalent population density of 12.6 persons per acre is obtained. Future flows within unzoned areas and undeveloped areas are based on a population density of 12.6 persons and a per capita flow of 72 gallons per capita per day. The I/I component of flow 'xas assumed to remain at 1.83 MGD. While repairs and rehabilitation work may reduce the current amount of I/I, the actual success of an I/I program is difficult to assess at this time. In addition, as the collection system expands, additional sources of I/I may be introduced into the system. Therefore, future flow projections are based on the current level of I/1 flows. - 89 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM M T L6 Tw LU LU ......... .... C) fliz ......... ......... .................... -t 2 ..... ......... ........ C-4 r 4 ..... ......... . ......... ......... ....* .... ........ ......................... 1113 LL ............................ ......... ......... ............................... LU......... ......... ............................ .... ........... ............. ......... ..... ........................ . ......... .................. ......... ......... ................... ................ .......... ......... .. ....... ......... ...... .............. ... ......... .. ................. ...... ....... ........... . ... .......... ... ............. . .. .. ...... ......... ........ ... ...... ... .... .. .... .... . .... ....... ....... ...... ......... ....... .... .... ... .... ....... ... ........ . ** .... ... .. :...... .... ....... . ...... .... ... ......... . .... ..... ... ........ ....... ........... ........... .. ... ..... ...... . ...... .............. . ...... ... ......... ..... ..... .......... ......... ...... ...... ....... ...... ............. ................. ........... . ......... ........ ......... ... ........:.......... ................ .... . ..... . ....... ...... ........... .... ..... . .....6... .................. O ........ ......... .... ...... ... ........ ... ..... ......... .......... ... ... ....... .. ..... .... O . ......... ........ . ....... ....... ... . ........... ........ .......... C) ......... ........ ......... ... ....... ... ......... .... . ......... .. ...................... ......... ............. ..................... ........ C ......... ....... ............. ...... O ....... ... I.. .... -:6:.:.:.:.:.:.:.:. . ....... ..... ............ .. . ...... ......... ......... .................. ......... . . . ......... ......... ........ C> z .... ........ O ...... ......... .................... 0 .........I................ ......... ......... ... .......... ........... ................ ..... . .............. ...... edyLu ......... ... .... .......... LIJ ........ ...... ....... ............ ........... .. ......... ......... . . ......... ... N 0 ................ . 0 dr. 0 ......... . ma. ..... ........ ....... 00 U- z 00 U ... ........... ......... ............. ....... .......... . ..... r. ..................... ................. ........... ............................ ....... r- rj ............ ... ....... o C5 .................. Ln ...................... ... ............ 0 u0........ ............ u Lf) C-) a. . ......... .............. o .......... ... . ....... ...................... ..... ..... ....... ................. ...... . .................. ..... ......... .......... . ......... ......... ........... ........ ....................... ........ ........ .......... ..... ...... ........ ....... ........ ........ .... ......... .... ... .... ......... C> C:> 0 C) C) 0 0 C) C� 0 C) C:) 0 0 0 �D 0 C) c:> 0 C) c:> 0 C> C) C> 0 C) -t cn uoilt,indod I ' I _ 1 • � I Vi Projected future flows and loadings are shown below in Table 5.2-1. TABLE 5.2-1 PLANT DESIGN PROJECTED FLOWS AND LOADS (YEAR 2014) VALUES Domestic, Commercial, and Industrial Flow = 3.81 MGD 32,551 x 117 gpcpd I/I Flow 1.83 MGD PROJECTED ANNUAL AVERAGE 5.64 MGD 5.78 PROJECTED PEAK DAY (5.64 X 1.99) 11.22 MGD 7.32 PROJECTED PEAK HOUR (5.64 x 2.44) 13.77 MGD PROJECTED LOADING BOD5 Average Day = 32,5510,22� 7,161 pounds/day 8,574 TSS Average Day = 32,551 x 0.16 5,208 pounds/day 7,219 POPULATION 32,551 persons 36,062 The total population within the 20-year planning boundary is projected to be 32,551 persons of which 27,060 persons are expected to reside within the current city limits. The remaining 5,491 persons are projected to reside between the 20 year planning boundary and the current city limits. The distribution of population outside the city limits is expected to follow the existing trend with approximately 63 percent residing in the southern section (South of U.S. 191) and 37 percent residing in the northern section (North of U.S. 191). As previously shown in Table 4.4.1-1, the current population is estimated at 22,976 persons in a drainage area of 2,921 acres. This represents an overall average density of 7.86 persons per acre. As discussed above, when the commercial and industrial flows are included as equivalent population, the overall average density is estimated to be 12.6 persons per acre. - 91 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM 5.3 DRAINAGE AREAS WITHIN 20 YEAR PLANNING AREA The topography of the planning area slopes from the southern foothills to the north. The wastewater treatment plant is located on the north side of the study area at an elevation of approximately 4630 above sea level. Areas below elevation 4630 will require lift stations to pump to the treatment plant. Areas below elevation 4630 primarily lie north of the treatment plant, in the vicinity of Riverside Country Club. While the area south of Bozeman generally slopes from the foothills to the north, smaller subdrainage areas have also been identified. Plate 5.3-1 (bound in back of report) shows the drainage areas within the 20 year planning boundary. From U.S. Geological Survey maps it is evident that a slight ridge lies to the west of South 19th Avenue. The ridge line runs approximately through the middle of Sections 23, 26 and 35 in Township 25, Range 5E. Areas west of the ridge line will drain to the northwest while areas east of the ridge line will drain to the northeast. The ridge line east of Sourdough Road also forms a natural drainage barrier. Areas west of the ridge line drain to the northwest. Development on the west side of the ridge will drain toward Sourdough Road. Areas east of the ridge will drain to the northeast to the vicinity of Haggerty Lane and then will drain to the northwest in the existing collection system. South of Durston Road and west of North 7th Avenue the drainage is basically due north toward the wastewater treatment plant. East of North 7th and south of the Interstate the drainage is to the northwest toward the wastewater treatment plant. The drainage zones were established primarily based on geographical considerations and the location of the existing sewer trunk lines. Consideration was also given to impacts future growth will have on the existing collection system. In several cases, areas could drain into two different drainage zones. In these cases the area was included in the drainage zone that could accept the additional flow with the least impact to the collection system. For example, the area immediately - 92 - \\HKMTROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM south of College St. and west of North 19th could drain into either Zone 3 or Zone 2. It was more cost effective to include the flow in Zone 2. The drainage zones are shown in Figure 5.3-1 bound in the back of this report. Drainage zones within the existing collection system were identified by determining which areas drain into the major trunk lines. The expansion of the sewer system into the future service area was modeled using Version 3.08 of the SANSYS computer model. The drainage area contributing flow to proposed new collection lines was determined based on the sewer layout and the USGS Quad Map of the area. All lines are designed for gravity flow. The proposed new lines are sized to flow at approximately 50 to 75 percent of full capacity at peak hour conditions. An overall population density of 12.6 persons per acre has been assumed for areas of new development. A population density of 12.6 persons per acre reflects the same development density as the existing City. In addition, an infiltration allowance of 150 gallons per acre per day was assumed for new development. This represents an infiltration rate of 10 percent of the average day flow generated by areas of new development. - 93 - \\HKM\PROJECT\DATA\O6\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 5.4 WASTEWATER COLLECTION SYSTEM 5.4.1 Improvements Required for Expansion Collection system additions required to allow growth outside the existing city limit boundary are shown in Plate 5.3-1 (bound in back). The majority of the future service area is unzoned. For this analysis, it is assumed the future service area will be a mixture of residential, commercial, and manufacturing zoning in the same proportions as the existing city. Zone 1. The Zone 1 area consists of approximately 2,691 acres located east of Sourdough Ridge and south of the interstate. The area is currently being developed with a mixture of residential, commercial, and medical facilities. The area south of the interstate slopes to the northeast. North of the interstate the natural drainage is to the northwest. The East Gallatin River flows along the northern edge of drainage Zone 1. South of the interstate, two natural drainages flow from the south end of Zone 1 toward the interstate. The majority of proposed new collection lines in Zone 1 will be located adjacent to the natural drainage ways. Figure 5.4.1-1 shows the locations and sizes for the main sewer lines proposed to serve Zone 1. Figure 5.4.1-1 also shows the approximately areas that will contribute flow to the line segments. The nodes shown correspond to input nodes used in the computer model of the collection system. Lines E1 and E2 will serve the eastern edge of the zone. The proposed lines will be located in Tayabeshockup Road and Canary Lane. The line segment from Nodes 1E3 to 1E4 will run along Canary lane. Line E2 will require boring under the interstate to serve the area along U.S. 10. As development occurs in the eastern part of Zone 1 and flows increase, the existing 8-inch line, that runs parallel to US 10, will have to be replaced with a 15-inch line. The existing 8-inch line in Highway 10 is currently connected to a pump station that pumps wastewater to a 10-inch line near Haggerty Lane. - 94 - H:\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 11:57 AM LI• i. W v ' /— s �+ St 18" Extend to Manhole F0209 at North Rouse g}zI n o t.a o 24" �:WW42)0 269 9 'L ; $L ACRES 21" i E4 ` b e D0512 c9, Se r° •� C0502 �a Iw SL a � •�' I E3 A0601 1 u Bogert PI e. -- �.:; r5• I Q — �-.- SIaY St DOJOS e.n 143 St .� 351 AC. EIUs � e a ACRES _ "'�c, N '90 " pnina. fi cm ° 5 C0507 ` st. •L �Ico Pond Rd o. b oeell v. 1E5 Z am Z � 1E10 Nag9artY In Z 132 ` AC. 1E9 RuDNr Ln, w E s< s173 N I '°H 1E4 Q e• s, �� aa . 1 R e'roc N.P w br. s4 '•,� .° �' -t 1E23 " $ Park.°e r 337 0 a �c, 6 376 ' Bdd ACRES cmdin AI Ino W. � �• ACRES " n le- KMY amac r _tt_t�i � K.gy Blvd. W b Box MliDddA 1E8 1E3 'E22 � i W Y m 518 0 ' 00 5 � ACRES 1E7 W Bradley 158 1E2 -N nwtn a. 1E21 w AC.& Sourdough 9 ` 610 ACRES SCALE 1"=2000' 00 1E20 °D IS 1E1 s., corarr*P»r.. or n:\data\06\M229 124\zonel.dwg BOZEMAN WASTEWATER FACLITY PLAN FIGURE 5.4.1-1 AREAN IMPROVEMENTS ENGINEERING DRAINAGE 6M229.124 F JULY 1998 i t • I J IA. .. l � t' I I ' t J l Two options were considered for connecting the eastern part of Zone 1 (lines El, E2 and E3) to the main collection system. Option 1 would involve constructing a new 18-inch line from manhole C0502 to manhole F0209. The new outfall line would eliminate the need for the existing lift station. Once the new outfall line is constructed, the lift station would be abandoned. The second option would involve replacing the existing lift station with a new lift station with a firm capacity of approximately 2500 gallons per minute. In the second option, the existing lines from manhole C0507 to F0330 and the line in North Rouse would have to be replaced with 33-inch lines. A cost analysis indicates that the lowest cost option will be to install the new 18-inch outfall line (E4) as shown in Figure 5.4.1-1. Even with the elimination of the lift station flows, the line from manhole C0507 to F0330 will eventually have to be replaced with 18, 21, and 24-inch lines. As growth occurs, the existing 8-inch line from manhole 261 to C0507 will have to be upgraded to a 15-inch line. In addition, the existing 12-inch and 14-inch collection line from manhole D0508 to manhole F0330 (at Rouse and Tamarack) will have to be replaced with 18,21 and 24 inch lines as indicated in Figure 5.4.1-1. The improvements required for the full development of Zone 1 are listed in Table 5.4.1-1. The estimated costs of the improvements are also shown in Table 5.4.1-1. Cost estimates were developed by estimating pipe installation costs, manhole costs, street restoration costs and engineering costs. All costs were combined to provide a cost per foot estimate. Costs are rounded to the nearest thousand dollars. It was assumed that construction of lines in areas that are currently undeveloped would not have street restoration costs. The costs are for comparison only and do not include costs for dewatering, relocation of utilities, deep excavations, or other unusual situations that may be encountered. Detailed costs should be developed when specific projects-are being considered. - 96 - \\H KM\P R OJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM TABLE 5.4.1-1 ZONE 1 ESTIMATED IMPROVEMENT COSTS MANHOLES LINE PIPE LENGTH DIAMETER INCHES TOTAL COSTS DESIGNATION UP DOWN FEET $ El IE1 lE2 2640 8 $143,000 El IE2 1E3 2640 8 $143,000 E2 IE3 lE4 3000 10 $171,000 E2 IE4 lE5 2700 10 $154,000 E2 IE5 A0601 800 12 $48,000 E3 A0601 C0502 4100 15 $287,000 E4 C0502 F0209 11000 18 $902,000 E7 IE6 1E7 3000 8 $162,000 E7 1E7 lE8 2300 8 $124,000 E7 IE8 lE9 3000 12 $180,000 E7 1E9 1E10 1400 12 $84,000 E7 1E10 IEll 1000 12 $60,000 E5 1E11 C0505 2000 15 $140,000 ES C0505 C0507 700 18 $57,000 E6 1E20 1E21 3000 8 $162,000 E6 1E21 1E22 2500 10 $142,000 E8 1E22 1E23 3000 12 $180,000 E8 IE23 261 1500 15 $105,000 E8 261 C0507 3400 15 $238,000 E8 COS07 D0508 3600 18 $295,000 E8 D0508 D0512 1300 18 $107,000 E8 D0512 D0420 2200 21 $204,000 E8 D0420 F0330 3900 24 $394,000 TOTAL $4,482,000.00 Zone 2. Zone 2 currently consists primarily of the Valley Unit Subdivision. The main sewer line draining the area consists of a trunk sewer extending from Durston, north to the existing 24-inch collector on North 19th Street. With future development, Zone 2 will be expanded significantly to the south of U.S. 191. Figure 5.4.1-2 shows the expanded Zone 2 service area and the proposed improvement. The areas of the subdrainage zones that will contribute flows to the line segments are also shown in Figure 5.4.1-2. In the proposed layout, the 21-inch far west trunk (lineS 11) will be extended South from Durston along the Fowler Road alignment. As Zone 2 develops and flow increases, the existing 18-inch line north of Durston between nodes J0401 and N5 will reach capacity. At that time, the 18-inch line should be replaced with a 24-inch line or a parallel line should be installed. A new overflow manhole would also be installed to divert flows at manhole 946 (the intersection of Oak Street extended and Fowler - 97 - \\H KM\PROJ ECT\DATA\06\M229124\CMC03717.D 0 C 08/16/98 @ 10:17 AM Road extended). The overflow manhole would divert flows that exceed 2500 gpm, the capacity of the remaining Valley Unit trunk sewer, to the 21-inch line (line N2) in zone 7. (Note: Manholes N5 and 946 represent a single manhole. Two different designations are used to satisfy requirements of the computer model). As discussed later in the Zone 3 evaluation, the 12-inch line west of Main Mall, currently in the Zone 3 drainage, will be transferred to Zone 2. In order to transfer flows to Zone 2, a 15- inch line will be constructed between manhole J0410 and manhole 950. Transferring this line to Zone 2 will help relieve surcharged condition in the 15-inch Durston line. An 8-inch line currently serves the technology park area at the corner of South 19'h and West College Street. The line drains into a 15-inch line on West College which in turns drains into the 12-inch line west of the Main Mall mentioned above. As flows increase with the development of the technology park area, the existing 8, 15, and 12-inch lines will no longer be adequate to carry the flow. The plan shown in Figure 5.4.1-2 would replace the existing 15-inch line in West College with an 18-inch line and the existing 12-inch line from manhole J0501 to J0410 would be replaced with a 15-inch line. On Baxter Road, the far west trunk sewer consists of a 24-inch line. The first two line segments in Baxter Road, between manholes 956 and I0101, have a flatter slope than the rest of the line. The last segment of 20-inch line, between manholes 955 and 956 also has a flat slope that limits capacity to 2800 gallons per minute. At full development, the line segments between manholes 955 and I0101 are projected to surcharge during peak hour conditions. Depending on the condition of the existing line when full development is reached, the line will either have to be replaced with a 27-inch line or a parallel 15-inch line installed. Development to the South of U.S. 191 and west of South 19`'' will require several new north/south draining lines. Line S6 will be in the South 19'h alignment and will consist of 8- inch to 15-inch lines. At Stuckey Road, line S8 (a 24 and 27-inch line) will drain to the west and will serve as a collector line for the north/south draining lines. - 98 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM i; .� i � , i 1 � � Hr. f �;.. f i�.� i .�. Table 5.4.1-2 lists the estimated costs for improvements in Zone 2. TABLE 5.4.1-2 ZONE 2-ESTIMATED IMPROVEMENT COSTS MANHOLES LINE UP DOWN PIPE LENGTH DIAMETER TOTAL DESIGNATION FEET INCHES COSTS$ S6 B21 B22 3700 8 352,000 S6 B22 B23 4300 10 421,000 S6 B23 B24 2600 12 263,000 S6 B24 B25 4200 15 454,000 S6 B25 B26 4100 15 443,000 S8 B26 B28 2700 24 383,000 S7 -- B27 3500 8 189,000 S7 B27 B28 4000 10 228,000 S8 B28 B218 2500 27 378,000 S9 10601 I0610 1200 12 118,000 S9 I0610 J0501 1500 18 183000 S9 B 34 I0601 4000 8 215,000 S10 B 32 B31 3000 8 161,000 S10 B31 J0501 2300 10 126,000 S10 J0501 J0410 5800 15 612,000 S11 ---- B219 4500 8 243,000 Sil B219 B218 3000 10 171,000 S11 B218 B217 2200 21 200,000 S14 -- B216 2400 8 130,000 S14 B216 B215 2300 10 225,000 S12 B215 B217 5400 15 378,000 S13 B214 B213 4100 12 242,000 S13 B213 K0526 1700 12 100,000 S11 B217 B212 3200 21 291,000 S11 B212 B225 2600 21 237,000 S11 B225 J0401 2500 24 252,600 S15 J0401 N5 2700 24 272,000 W1 J0410 950 2500 15 175,000 W2 955 956 400 24 40,000 W2 956 I0101 900 27 136,000 - - --- -- - - ---- .. TOTAAL - .. $7,618>000.00 - 99 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM I � - I .t '� 10" 12" all S14 10" Cottonwood Rd. cN1 (D2 6215 "Z 8216 B214 10" 1-8 B227 18" L 1111101111111 =1 12" Ferguson Rd. N4 15 S13 m FL 1161 S12 579 15" ACRES ACRES i_ N3 946 21" 12" z, INSTALL NEW OVERFLOW B213 505 Cho to Am n OVERFLOW LINE 6219 --mgher-- ow..H 5;, MANHOLE N6 ' ACRES Sil 101, 21 Sil 21" Fowler Rd. S11 24" S15 21 Fowler Rd. — 11 ��25) REPLACE N5 S8 (821�2 cVMee VdIley Dr. * J0401 NTH 24 27" REPLACE 665 11�WITH 15" 15" 24" B28 B31 J0501 12'PVC 21" 8 - -—- 12" W1 W2 20 YEAR PLANNING AREA ACRES �,) i� 10, ZL 8- 0" 6" 55 27 IF - 950 and.9 1 S9 Podam Rd. 9 REPLACE J0410 I 476 NTH 18"' Pr onal 713 11, S8 REPLACE Dr.g 9 N.25th 459 :1010�1 ACRES IOr)Oj WITH 12" 81 Pvc $ Md Dr. �j ACRES ACRES 2W 8. S9 81, * oh c N.22nd fl, S. N 821 g7 H Brownie Ln. S(; R—Ington Way 20th.8 19th N.19th 8. 1 10" S6 12- Md r 17- 8 16th 652 W W. N ACRES „tl 15th 8 SL 14th 9 SE R vz th p p- S.3rd N.111th ic Pvc� c: Z, :1fith 3 j u.., i jj gth n -1 N c() A 9th .917— (D S.3rd Ave. S.7th N.7th 0.9 aly I\." * 7 r %,, Ila* WhOW•FR &, SCALE 1"=2000' Colter t4 H l d Ct a BOZEMAN WASTEWATER FACILITY PLAN FIGURE 5.4.1-2 Spring Meadow. p ZONE 2 IIIIHM-11411CIIIIII DRAINAGE AREA IMPROVEMENTS ENGINEERING n:\dc3ta\06\M229.124\zone2.dwg 6M229.124 JULY 1998 Zone 3. Figure 5.4.1-3 shows the Zone 3 drainage area. Zone 3 currently drains into a 15-inch collector line on Durston Road. The 15-inch collector increases to 18-inches north of Durston. The computer model projects that the 15-inch and 18-inch collector lines are currently surcharged at peak hour flows. Therefore, any expansion of Zone 3 will require improvements to the collector line on Durston. A 12-inch line, west of the Main Mall, currently extends from Durston Road to West College Street. At West College a 15-inch line ties into the 12-inch line. At current peak hour flow rates, the 12-inch line is flowing at approximately 38 percent of its capacity. With the available capacity in the 12-inch line, the drainage area for the main can be expanded to include the area west of South 19th and south of West College. Inclusion of this area into Zones 3 would require improvements to the Durston line. Two options were considered to allow the additional drainage area to be collected in the 12-inch main. The first option involved installing a 21-inch line on Durston between manholes J0410 to H0301 (at North 19th). At the intersection of North 19th and Durston a diversion manhole would be installed to allow diversion of flow to a new 15-inch line down North 19th. This option is estimated to cost approximately $606,000. The second option involves diverting flow from the 12-inch "main mall line" at Durston (manhole J0410 to the 20-inch line in Zone 2 (manhole 950) at Oak Street extended. With this option, approximately 2800 feet of new 15-inch line(W1) would be installed between manholes J0410 and 950. Diversion of the flows in the 12-inch "main mall line" would eliminate surcharged conditions in the Durston line. With flows diverted at manhole J0410, under peak flow conditions the 15-inch line in Durston will be at approximately 75% of capacity. This option is estimated to cost approximately $175,000. It should be noted that at full development of the area served by the 12- inch "main mall line" (manhole J0501 to J0410), the line would have to replaced with a 15-inch line as discussed in the zone 2 discussion. - 101 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM `;. `�� . �: . . : ;� . � - ., _ � . �w t Nickles Dr. —7 950 DIVERT I Durston Rd 12' 12" W in- 1B-ACf� HIM ZONE 2 Ell Ill 1103a911� 111111111m11196,10 Cm State �I® -__�_� Lam';. • �;6f off DRAINAGE AREA IMPROVEMENTS ENGINEERING r i :' - . �- ., - i .,{ .. ,.: ,, • _ - _ ,. ., .. :t .. , - ., . ' � J•I � r 4.. ., I �: ,,; ,� � � � ,�� ,�� t' � ' �� ., `, IY� , . .- The existing 8-inch line north of West College street in North 19th and between North 19th and North 20th is projected to be over 90 percent of capacity during peak hour conditions. While replacing the line is not recommended at this time, the line should be monitored as growth occurs to verify that adequate capacity is available. If the actual housing density that develops is greater than anticipated, the line will have to be replaced with a larger line. The cost of the diversion line to Zone 2 (W1) is estimated at $175,000 as shown previously in Table 5.4.1-2. Zone 4. Figure 5.4.1-4 shows the improvements planned in Zone 4. Zone 4 is an existing zone that will not be expanded to serve new areas. Additional growth can occur in Zone 4 due to the development of currently undeveloped land within the drainage zone. It is anticipated that the most significant areas of new development will occur along North 19th near the interstate. A 24-inch trunk sewer flows through Zone 4 to the treatment plant. Near the interstate, the 24-inch trunk sewer increases to a 30-inch line. Flow from Zones 2, 3, and 4 are carried by the trunk line. Flow from Zone 7 will also flow into the 30-inch trunk sewer near the interstate. The capacity of the 30- inch line is 15,000 gallons per minute. The projected future peak hour flow is 17,800 gallons per minute. Therefore, as full development is reached in Zones 2, 3, 4 and 7 the 30-inch trunk will have to be replaced with a 36-inch line. The portion of Zone 4 south of Kagy Boulevard drains into a 14-inch line on South Willson. Prior to the 14-inch line, an existing 12-inch line running from Hoffman to South Willson is at 90-92% of capacity during peak hour flows. Flow monitoring indicates the infiltration flow carried by the 12--inch line is currently approximately 150 gallons per minute. The infiltration flow comprises roughly 22% of the available line capacity. The removal of the I/I flow will extend the life of the 12-inch line. However, as new development occurs, it is expected that the 12-inch line will again reach capacity and should be replaced with a 15-inch line. - 103 - H:\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 1:06 PM Table 5.4.1-4 lists the estimated cost of improvements in Zone 4. TABLE 5.4.1-4 ZONE 4 ESTIMATED DvIPROVEMENT COSTS LINE PIPE TOTAL DESIGNATION MANHOLES LENGTH DIAMETER COST UP DOWN FEET INCHES $ Al I0013 58 500 36 $100,000 W3__J F0715 F0608 1150 15 124 TOTAL $224,000 Zone 5. Figure 5.4.1-5 shows the improvements required to serve the expanded service area in Zone 5. Zone 5 will provide service to a large area south of the city and east of South 19th. The collector lines, draining from the south will drain into an interceptor line on Graf St(line S4),which will run from South 3rd to the natural drainage west of Sourdough Road. The interceptor will consist of 12-inch and 24-inch lines. A new 21-inch line(S5) will flow to the south along Bozeman Creek. A detailed survey will be needed to determine the exact routing of the 21-inch line and to identify possible wetland areas and stream crossing where mitigation measures would be required to avoid environmental concerns. As an alternative, the 21-inch line could be constructed in Sourdough Road. This alternative would involve extending the 24-inch interceptor to Sourdough Road. The alignment down Sourdough Road would involve deep excavations and difficult construction. A detailed survey and cost analysis will be required to determine the most cost effective routing for the 21-inch and 24-inch lines from junction node 6S8. The 21-inch line (S5) will connect to the existing collection system at manhole F0663. The existing lines below manhole F0663 are primarily 8-inch lines. These lines will need to be replaced with a new 24-inch line(A8) as shown in Figure 5.4.1.5. Currently, all the flow from Zone 5 flows into a 20-inch line in North Rouse. The 20-inch line carries flow from both Zones 5 and 6. With increased flows in Zones 5 and 6, the 20-inch line in North Rouse will have to be replaced or a parallel line installed. The required improvements to the 20-inch line in North Rouse are discussed in the following section of the report (Zone 6 discussion). - 104 - \\H KM\PROJ ECT\DATA\06\M229124\C MC03717.DOC 08/16/98 @ 10:17 AM SCALE 1"=2000' law 1071 1mIcIr= :/.�� • 'Ir�i�1�114i1�1�i•'{IC3 i • r Il�irll•I�l�l[311L4C :. �� ACRES - �ii�il�f � If ail©1Pi Via' 1f III • �®� i - •� .�� l � � � , �,� I 1 �. . T S .' J 20 YEAR PLANNING AREA A �y I � � BfON11�1 ln. "s s tgtn 672 57 ACRES S.3rd mmml� 215 ACRES S3 6519 10" S3 10" I . 6521 6S17 6S20 12" 3fd A'" 6S18 Shadow 1120 S3 ACRESp � '�, M.n°a F� F 460 6S10 6S11 6S12 6S13 6S14 ACRES 6S15 S A 10" 10" S2 12" 15" � 52 15" 15" 6S6 6S7 Hltching Post Rd 12" 10" S1 12" 12" S1 S1 8" S1 8" e 6S7 8' 5 b 6S5 6S2 716 6S3 472 6S4 ad ''� a 1F ACRES ACRES ACF So.4-gn Rd. o$ I I SCALE 1"=2000' I n:\data\06\M229124\zone5.dwg �� . .� : :�;' P _ ��;� �r�' • ��li � � _ � — _ n . I U 1�i .r - - - I � , .�� .I •AI- I �_ • • � ' '�� J - • ,r � a .� .I '' ?' - .: I� • S I,' f:�� r �I .t •1 • � v - I {i The estimated costs for improvements required to expand zone 5 are listed in Table 5.4.1-5. TABLE 5.4.1-5 ZONE 5 ESTIMATED IMPROVEMENT COST MANHOLES LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ S1 6S1 6S2 4600 10 262,000 S1 6S2 6S3 4200 12 240,000 S1 6S3 6S6 2300 12 226,000 S1 - 6S4 2300 8 218,000 S1 6S4 6S5 1800 8 171,000 S1 6S5 6S7 600 8 57,000 S1 6S6 6S7 1800 12 177,000 S1 6S7 6S8 3000 15 193,000 S5 6S8 6S9 2800 21 '266,000 S5 6S9 6S23 2100 21 200,000 S5 6S23 F0663 2100 21 200,000 A8 F0663 F0330 8000 24 1,139,000 S2 6S10 6S11 3200 10 182,000 S2 6S11 6S12 2000 10 110,000 S2 6S12 6S13 3400 12 195,000 S2 6S13 6S14 2600 15 181,000 S2 6S14 6S15 2500 15 161,000 S2 6S15 6S16 2800 15 180,000 S3 6S17 6S18 3700 10 363,000 S3 6S18 6S19 6500 10 625,000 S3 6S19 6S20 800 15 86,000 S3 6S20 6S21 2000 12 197,000 S3 6S21 6S22 3200 12 315,000 S4 6S22 6S16 1200 12 118,000 S4 6S16 6S8 1800 24 256,000 TOTAL $6.318,000.00 Zone 6. The main trunk line in Zone 6 flows north down North Rouse and then west to the treatment plant. Lines from Zone 1, Zone 4, and Zone 5 also connect to the Zone 6 trunk line. Future growth will result in flows that exceed the capacity of the existing trunk line. The improvements recommended in Zone 6 are shown in Figure 5.4.1-6. With the added flows from Zones 1 and 5, the existing 20-inch line on North Rouse will need to be replaced with a 33-inch line. Once the line turns to the west, at manhole F0109, the line slope - 107 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/16/98 @ 10:17 AM .} i ,� i i ' 1. ,+ .� = . J :� • ; -I --t-' 322 ACRES Ell 8" �, ��is��al i �� E� I►r It nil W. i•' it 11 1 i��'u a Rom��; a ;� I StMMRCNN M . - mime �n l • ' DRAINAGE AREA IMPROVEMENTSENGINEERING J . . � ;i+ i i ti • ��.� � - - - - ' l � r� � - .�� _. �� _ r i, � �I ., .,_ �., �.. ' �� r � �'.: _ W i .. ..;, r i � - .:. � � i .3� - '�' •• - .: :,._. � • I '� r�' N� y � • �II i! • � -J] � � '� � I � - ' n •�' I t� decreases and a larger line will be required. From manhole F0109 to manhole 43 a 42-inch diameter line (A4) will be required. Flows from the Hillside Lane, Big Gulch Drive areas (lines E9, E10, and Ell) and from the Bridger Creek subdivision will connect to the outfall line at manhole 43. A 42-inch line will also be required from manhole 43 to manhole 58. Although the existing Bridger Creek Subdivision lines do not include a flow allowance for the Hillside Lane or Big Gulch Drive areas, the line capacity appears adequate to serve the additional areas. The additional drainage area would consist of approximately 130 acres or an additional 495 persons at R1 zoning. The estimated cost for the improvements required in Zone 6 are listed in Table 5.4.1-6. TABLE 5.4.1-6 ZONE 6 ESTIMATED IMPROVEMENT COST MANHOLE LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ A7 F0330 F0109 4700 33 $ 868,000 A4 F0109 45 6400 42 $1,414,000 A4 45 58 2600 42 $575,000 A4 58 Plant 1200 48 $ 265,000 E9 --- --- 6500 8 $ 350,000 E 10 -- 2800 8 $ 150,000 E11 --- -- 5100 8 $ 274,000 TOTAL $3,896.000.00 Zone 7. Zone 7 consists of the drainage area on the western edge of the service area and an area north of U.S. 191. Figure 5.4.1-7 shows the drainage zone and the areas assumed to flow into each line. In Zone 7, a 21-inch interceptor line located in the extension of Oak Street will connect to the far west trunk sewer at Manhole N5. The capacity of the far west trunk sewer, downstream of Manhole N5, is 2,800 gallons per minute. As development occurs, and flows increase in Zones 2 and Zones 7, the capacity of the far west trunk will be exceeded. In order to prevent surcharging of the far west trunk, Manhole N5 should be installed with an overflow line that will function when - 109 - \\H KM\P R OJ ECT\DATA\06\M229124\CMC03717.DO C 08/16/98 @ 10:17 AM I . , -- _ � ..' { i 9 a 27" N3 Q N8 N9 LLI Q 24" 1. 10 p"Slog. qb N Z ''a Q 789 Simme l ral Trpl ACRES Depd— N2 arh ct. 4 N7 orvgle We SCALE 1"=2000' 5 Y O Rawhide Ridge CI N x 24" pptntl ct l3a.ler R. .-AG 24• Y 289 N6 N2 A CRES 21" OVERFLOW N5 LINE 1. N 1 18" " u wpo�51, a Y�•�e N4 15" R_-INSTALL NEW s' a OVERFLOW _ 15" N1 N3 MANHOLE NOT YAMCyM CO # Ste"" St. g REPLACE 15" a MY dfor sl e' 1e- N2 208 S15 WITH 24" 10" ACRES 21�� W1 s, �, A tmocc ve J0401 s D—tm M, Nl L d `S Y a N1 4 � - rpple sl, t 8 24" s 10" a ti S c e• � s` w.o�ul C. St. a 8227 3 € C6220 E3,w,.ple. M1 y e F N1 p• < Bnb— Est t p lo" n s c r 5 y a L rc n Ravalll b -r:o(h St - 570 L Ir a p r"• - ACRES 21 fi "•ru s+ � 8 � S e• ca a ca e � � 10• U.S. 191 „o +W. ptk a St.Is ore c wr b ' n:\data\06\M229124\zone7.dwg N BOZEMAN WASTEWATER FACILITY PLAN FIGURE 5.4.1-7LJ ZONE 7 11 -I�KIM ENGINEERING DRAINAGE AREA IMPROVEMENTS 6M229.124 JULY 1998 � . . . . : . . �� . �� -�� T � ,� t � r. � � � _ � � ;,,� I, .� r1 �� :_ � � � � �:�' .-y� -. _ - ,. �= � ' - F � - - � _ _� � J .. � � � � 1 i ' 1 ' �= � ��5i " - - • • _ - I �'.1 �- y .� • I .Y - I,` -- - '' .I. �' I flows exceed 2800 gpm. When the capacity of the far west trunk is exceeded, the 21,24,and 27- inch lines (N2 &N3) from Manhole N5 to Manhole N9 will have to be constructed. Several options were considered in the routing of the Zone 7 trunk line. The selected route was based on review meetings with the city staff and a cost-effective analysis. One option considered, included installing a new line in Durston with an overflow manhole at Durston and Ferguson Road that would allow overflow to flow to Manhole N3. The selected routing connects the Zone 7 trunk line to the far west trunk at Manhole N5. This connection will allow growth in the southern portion of Zone 7 without requiring the construction of the entire trunk line from Manhole N5 to N9. Table 5.4.1-7 lists the estimated costs for the Zone 7 improvements. TABLE 5.4.1-7 ZONE 7 ESTIMATED IMPROVEMENT COSTS MANHOLES LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ N1 B227 B220 2600 10 256,000 N1 B220 N1 2600 10 148,000 N1 N1 N2 1800 10 103,000 N 1 N2 N3 3100 15 200,000 N1 N3 N4 900 15 58,000 N1 N4 N5 2400 18 195,000 N2 N5 N6 1500 21 143,000 N2 N6 N7 4500 24 455,000 N2 N7 N8 3100 24 313,000 N3 N8 N9 3900 27 468,000 `�- 1 1 —— TOTAL $2,339,000 Zone 8. Zone 8 consists of the drainage area north of the East Gallatin River and includes the foothills east of McIlhattan road. Figure 5.4.1-8 shows the location of Zone 8. The Zone 8 area will drain into a 15-inch line on McIlhattan Road. A 15-inch line will also run to the west from McIlhattan Road to the wastewater plant. The location shown for the 15-inch line running to the west is shown only in the general area of the required line. Subdivision development and - \\H KM\P R O J E C T\DATA\06\M 229124\C M C 03717.D O C 08/16/98 @ 10:17 AM 1 :� ,. r I �� .* i. �9 ' a E1315" 20 YEAR PLANNING AREA 395 'S� 369 ACRES ACRES A NI a� -N �-Ao.wlarsn V,�' mock 5 a q_ �b 12' _ Da 51n+msntd SCALE 1°=2000' •'b• Doodmans Gulch C B• e & Orville Nyy a as S for U _ s b � wq r sttAuY 'P Bridge,Dr pn Cam rr r rn w AL 1id01hAl Ct' Acj`� Hillside Ln. agg, a �• s t^R Al. Ln. ri 5 z tl 1 S K tl'r Cdl i Dr. Wheat Dr. _ s'PVC -11 tl y il.,rStN Y IIKJNK °�two tfr t St. 1 ' n• smd S1 s � \ R � Oak Sl Bid Gulch Dr. - Oak St. N• 15 /_ woad Sl. �• i�nl�, 4. 1 5 oa YYplalEi J. ! ^ s' H ock Sl. u1 St Juniper t lei tl• �' z 'Pvc ••T � c In le• s• 9Mdw St. Cls' la' ''le•e _ le' Z IOA Is•^ q . 'o. ' 1 1� yC •1\.04ERRo CAPABIUW St. A.l�� Y K �rnacn Ave ra ^ K z 1• Is 1� 1a e. z a.VC - 1 ,- " z ' Dmtl 1. • J- � z a <y W.BcaB � - ,Q• f�la•�l 51, �tl'r � 9n Q, s• 1 .fi tl- b S sC ut 4 s• e- 6 r �T 0' - — e' K• i 6 K. t 0-• _�_ .— N tl' aIf tl• tl• .«)51. .@ u '/a• BOZEMAN WASTEWATER FACILITY PLAN FIGURE 5.4.1-8 ZONE 8 KIII AREA IMPROVEMENTS ENGINEERING DRAINAGE6M229.124 JULY 1998 n:\data\06\M229124\zone8.dwg • i • � �' - I, _ _�. _ _ _ • I • "� I� r � All I I � 11 !' r, �i Ir • 1� I 1 � iM I �• • 1 tit lii� • ;• � I _ � I � � _ �►7 • , ` - 7► • '� • � N O - � i c. . .� ��1 `:✓. �� .'� -� . • - � �� configurations may require shifts in the alignment. The estimated cost for the 15-inch line in Zone 8 is $974,000 as shown in Table 5.4.1-8 TABLE 5.4.1-8 ZONE 8 ESTIMATED IMPROVEMENT COSTS MANHOLES LINE PIPE LENGTH DIAMETER TOTAL DESIGNATION UP DOWN FEET INCHES COST E12 7500 15 478,000 E13 7700 15 496,000 TOTAL $974,000.00 Summary Table 5.4.1-9 shows a summary of the zone characteristics. The populations and flows are calculated based on full development of each zone. TABLE 5.4.1-9 SUMMARY ZONE CHARACTERISTICS AT FULL DEVELOPMENT ZONE# POPULATION TOTAL AREA AVERAGE DAY PEAK HOUR ESTIMATED ESTIMATED COST SERVED ACRES FLOW-MGD FLOW-MGD i/I FLOW-MGD OF DAPROVEMENTS 1 40,300 3067 3.78 9.86 0.372 $4,482,000.00 2 56,500 5210 4.84 5.96 0.769 $7,618,000.00 3 6,900 1070 0.77 1.92 0.239 $ 0.00 4 29,600 1842 2.04 2.74 0.407 $ 224,000.00 5 55,000 4351 4.86 9.5 0.898 $6,318,000.00 6 24,400 3535 �� 3.21 5.87 0.81 $3,896,000.00 7 32,900 1856 2.7 9.90 0.278 $2,339,000.00 8 9,600 464 0.81 2.16 0.177 $ 974,000.00 TOTAL 255,200 21395 23.01 37.52" 3.95 $25,851,000.00 1/ The 37.52 MGD represents the peak hour flow for the entire system. The projected peak hour flows for the indivi.diial zones will not eqi-lal the total system pnmk hour flow because a different pak_inp,, factor is applied to the individual zones when they are considers s1 as a separate system. - 113 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 1:08 PM 5.4.2 Existing System Improvements Improvements to the existing collection system can be related to either current overloaded conditions, the need to increase pipe sizes to handle future growth or the physical condition of the existing lines. Improvements required in each drainage zone are discussed below. Zone 1. As discussed previously in Section 4.6.2, the existing 12-inch and 14-inch lines from manhole D0508 to F0330 are near capacity. Flow in the 12 and 14-inch lines originates from two sources: 1) the pump station which serves areas along US 10 and 2) gravity flow from the hillcrest and hospital area. It should be noted that the operation of the pump station has a major impact on the flow in the line. The capacity of the line is approximately 1077 gpm and the pump station has a rated capacity of 476 gpm. Therefore, when the pump station is running the flow from the pump station represents approximately 44% of the line capacity. Even with infrequent operation of the pump station, the potential exists to surcharge the 12 and 14-inch lines, between manhole D0508 and F0330, if the gravity portion of the flow exceeds approximately 600 gpm. As discussed in Section 5.4.1, a cost analysis indicates it will be more cost effective to install a new 18-inch line from Manhole C0502 to Manhole F0209 than to construct a new lift station. However, if the 18,21 and 24-inch lines from Manhole D0508 to Manhole F0330 (at Rouse and Tamarack) are installed prior to the need for the new lift station, it may be possible to increase the capacity of the existing lift station by changing pump impellers and increasing the motor horsepower at minimum cost and delay the need for the 18-inch line from manhole C0502 to F0209 (E4). A detailed cost effective analysis should be completed when the existing lift station reaches capacity. Zone 2. No improvements in the existing collection system are needed to this drainage zone. The new lines required to expand zone 2 have been discussed previously in Section 5.4.1. - 114 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/20/98 @ 1:20 PM Zone 3. At current peak flow rates the 15-inch and 18-inch lines on Durston and North 17th appear to be overloaded and most likely surcharge during peak hour flows. The capacity of the 15- inch main on Durston between North 20th and North 17th is approximately 1,120 gpm. The peak hour flow is estimated to be 1,480 gpm which includes approximately 120 gallons per minute of groundwater infiltration. In order to relieve the surcharged conditions in the 15-inch main on Durston between North 20th and North 17th, it is recommended that flow in the 12-inch main west of the Main Mall be diverted into drainage Zone 2, as discussed in Section 5.4.1. Flows would be diverted at Manhole J0410. As shown in Table 4.5.4-1, Zone 3 area appears to have a substantial amount of infiltration. Additional monitoring and TV inspection should be conducted to further isolate areas of high infiltration. Once identified, the cost for repair can be compared to replacement and the most cost effective solution pursued. Zone 4. The only line in Zone 4 identified as being at or near capacity is the 12-inch line from the intersection of Hoffman Drive and Tracy Avenue to South Willson (Manhole F0714 to Manhole F0709). This line appears to be at 90 percent capacity at peak hour flows. Without system improvements, further development in the southern portion of this zone will result in surcharging of this line. Many of the older lines in Zone 4 are 6-inch clay tile lines. These lines require frequent cleaning due to plugging and solids deposition. The maintenance problems may be related to line size, flat slopes, or root intrusion. Extensive root intrusion can cause solids deposition if the root growth is enough to reduce the flow velocity. Root growth in the clay file lines was identified as a problem by the City Maintenance staff. It is rer,.ommended that all the lines in Zane 4 h Bbbcock and Kagy from 1 lth Avenue to 4th Avenue be inspected with a TV camera to further identify problem areas. - 115 - M KM\P R O J E C T\D A T A\06\M 229124\C M C 03717.D O C 08/20/98 @ 1:20 PM Many of the lines in this area were installed in the early 1900's. Therefore, it would not be unexpected to see cracked joints or bad joints where root growth and/or infiltration could occur. Based on the results of the TV inspection, the lines should be replaced as needed. When the TV inspection indicates replacement is needed, the existing 6-inch lines should be replaced with 8-inch lines to meet the state requirements for minimum line size. (Circular WQB 2-Section 33.1). Flow monitoring indicated groundwater infiltration flows are approximately 95 gpm in the 10-inch line on South 3rd and 55 gpm in the 8-inch and 10-inch line on Kagy Boulevard between Sourdough Road and Fairway Drive. A reduction in I/I flows and the construction of the southern interceptor on Graf Street (line S4, Manhole 6S22 to Manhole 6S8 in zone 5) will alleviate the current need to upsize the existing 12-inch line(Manhole F0714 to Manhole F0709). However, with additional growth in the southern portion of Zone 4, the line will eventually have to be replaced with a 15-inch line (W3) as shown previously in Figure 5.4.1-4. Zone 5. As discussed previously in Section 4.6.2, a substantial amount of groundwater infiltration is evident in Zone 5. Table 4.5.4-1 shows the groundwater infiltration at Cottonwood and Rouse is estimated to be 100 gpm and the ground water infiltration at Cottonwood and Church is estimated at 85 gpm. This indicates the total ground water infiltration in Zone 5 is approximately 185 gpm (.266 MGD). The infiltration sources add a substantial load on the sewer lines. The lines in Zone 5 should be inspected with a TV camera to isolate leaks to determine the cost effectiveness of repair. The infiltration at Cottonwood and Rouse comes from a line identified as being repaired during the early 1980's as part of the EPA rehabilitation program. It is suspected that the grouting used in the repair has deteriorated to the point it is no longer effective. The line on North Rouse from Cottonwood to Lamme Street should be inspected with a TV camera to determine the location and quantity of the infiltration. Once the defective areas of the line have been identified, a determination can be made to either repair or replace the line. - 116 - \\H KM\P R OJ ECT\DATA\06\M229124\C MC03717.DOC 08/20/98 @ 1:20 PM The 6-inch line on Church and the 8-inch line on Rouse Avenue from Story to Main Street were identified in the City's records as maintenance problems that require routine cleaning to prevent plugging. The recommended 24-inch trunk sewer (A8) for Zone 5 would replace the existing 8- inch line on Rouse. Zone 6. The future southern interceptor for Zone 5 will connect to the line on North Rouse north of Griffin Drive and will then flow west to the treatment plant. The 20-inch line on North Rouse is currently at approximately 50 to 70 percent of capacity. The line has approximately 2.1 MGD of remaining capacity above current flow rates. However, the line also is estimated to carry approximately 400 gpm of infiltration. The I/I estimate is based on the flows listed in Table 4.5.4- 1 for the following manholes: LOCATION MANHOLE NUMBER ESTIMATED I/I FLOW Cottonwood&Rouse F0328 100 gpm Juniper&Church E0305 100 gpm Cottonwood&Church E0302 85 gpm West of Rouse and Bryant on 21" F0207 130 gpm Reducing the current I/I of approximately 400 gpm would provide additional reserve capacity. A peak hour flow of 2.1 MGD equates to an additional population of approximately 5,100 persons. Therefore, there is no immediate need to increase the line capacity. If the line's physical condition necessitates the lines replacement, a 33-inch line should be constructed. The 33-inch line will provide enough capacity for the potential development south and east of the city. If a relief sewer line were installed to parallel the existing 20-inch line, a 27--inch relief line would be required. As indicated previously in Section 4.6.2, there appears to be a short section (approximately 200 feet between Birch and the interstate underpass) of 20-inch line on North Douse from manhole E121 2 to F0208 that was installed on a relatively flat slope that may surcharge during peak hour flows. The line also appears to be carrying a significant amount of infiltration (400 gpm). Rather than replace the existing section of 20-inch line now, we recommend that the City make a concerted effort to - 117 - \\H KM\PROJECT\DATA\O6\M229124\CMC03717.DOC 08/20/98 @ 1:20 PM reduce the I/I in the drainage zone. When the line does need to be replaced, a 33-inch diameter line should be installed. As discussed in Section 4.6.2, the capacity of the outfall line in Zane 6 is limited by the single 20- inch line from Manley Road to the connection with the 30-inch line(manholeG0132 to manhole 42). To meet the projected full development flows, the segment should be replaced with a 42-inch diameter line. Zone 6 also has several lines that require routine maintenance due to solids deposition or plugging. The problem lines are primarily old 6-inch lines that were installed in the early 1900's. The majority, of the Zone 6 lines are also in an area identified by the City crews as an area where root intrusion is a problem. TV inspections should be completed on the Zone 6 lines to further identify where root growth and possible infiltration is occurring. 5.5 FUTURE WASTEWATER TREATMENT SYSTEM IMPROVEMENT NEEDS This section of the report evaluates the capacity of each treatment component to meet future flows and loads shown previously in Table 5.2-1. When improvements are required, alternatives are evaluated and recommendations are presented. Pretreatment. The estimated capacity of the bar screen is 9.7 MGD. During high flow conditions, the plant has experienced flows in excess of 10.0 MGD. A portion of the flow will be diverted into the manually cleaned screen when the flow exceeds the capacity of the mechanical bar screen. This is not a problem if it only occurs on an occasional basis such as peak day flows. The mechanical bar screen has functioned well without requiring any major mechanical repairs. At this time, no upgrade or expansion of the bar screen is recommended. As the system ages, more repairs will be required and parts availability may be difficult as the screen was custom built and the manufacturer has gone out of business. When frequent repairs are needed the mechanical bar screen should be replaced. - 118 - \\H KM\P R O J E C T\DATA\06\M 229124\C M C 03717.D O C 08/20/98 @ 1:20 PM It is recommended that the manually cleaned screen remain as the back-up screen. While it would be possible to install a second mechanically cleaned screen as a back-up in lieu of the manually cleaned screen, the close bar spacing of the mechanical screens would require frequent cleaning in the event of power failures. The capacity of the grit chamber is adequate to flows of 12.9 MGD. No changes are required to the grit chamber. Primary Clarifiers. State criteria specifies two overflow rates for primary clarifiers; (1) 1000 gpmlfC at average day flows and (2) 1500 gpd/ftZ at peak hourly flows. The existing primary clarifiers are adequate up to an average day flow of 6.64 MGD and a peak hour flow of 9.9 MGD. At peak flows above 9.9 MGD, the efficiency of the clarifiers will decrease. As discussed in Section 4.7.3, the apparent low TSS and BODS removal rate is probably due to sidestream loadings from the gravity thickener and flotation thickener that are not being accounted for. It is recommended that B0135 and TSS testing be started on the gravity thickener overflow and flotation thickener underflow, on a routine basis, to verify the actual loading on the primary clarifiers. The gravity thickener supernatant may be adding a substantial soluble BOD5 load on the primary clarifiers that will not be removed through the primary clarifiers. Construction of a third primary clarifier is recommended when the annual average day flow reaches 6.64 MGD. In the year 2014 annual average flow is projected to be 5.64 MGD. Therefore, there is no immediate need to construct an additional primary clarifier. Aeration Basin. The capacity of the aeration basins can be limited either by the microbiological process or by the oxygen transfer efficiency of the blowers and diffusers. The blowers have the capacity to treat a POD5 load of approximately $.50 pounds per day. The f<athxre BOIa, load is projected to be approximately 7200 pounds per day. Therefore, the blower capacity is adequate for projected future loads. - 119 - \\H KM\PROJECT\DATA\06W229124\C MC03717.D OC 08/20/98 @ 1:20 PM The aeration basin should maintain a minimum hydraulic detention time of 4 hours. This equates to a flow of 10.9 MGD. At a flow of 10.9 MGD the microbiological process will be capable of treating a BOD5 load of approximately 15,000 pounds BOD5. The load of 15,000 pounds is approximately twice the projected future load. The blowers represent the major power use at the wastewater plant and consequently are a major operational cost. The City completed an energy evaluation study that investigated methods to reduce the power costs associated with the blowers (Energy Resource Management Inc., 1994). The energy evaluation recommended replacing one of the existing turbine blowers with a variable frequency drive (VFD) blower system. The VFD will be controlled by dissolved oxygen probes located in the aeration tank. The energy evaluation study estimates the power savings at $23,800 per year. The cost for the blower improvements has been estimated at $87,486 by Energy Resource Management Inc.. At an interest rate of 8 percent the initial investment would have a payback period of approximately 41/2 years. As a result of the energy evaluation study, the city has replaced one blower as recommended. No improvements are required for the aeration system to meet state criteria. However, as noted in Section 4.7.3 the PVC air lines are showing signs of deterioration. Final Clarifiers. The capacity of the clarifiers can be controlled either by peak hour flows or average day conditions. State criteria only addresses peak hour conditions and sets the'maximum overflow rate at 1,200 gpd/ft2. Typical design criteria also includes an average day overflow rate limit. At average day conditions, the overflow rate should not exceed 800 gpd/ft2. Based on these criteria, the final clarifiers will be adequate up to average day flows of 7.96 MGD and peak hour flows of 11.94 MGD. At the projected 20 year peak hour flow of 13.77 MGD another clarifier would be needed to meet state criteria. However the need is marginal. Even though the 20-year projected peak hour flow of 13.77 MGD is greater than the clarifier capacity, no additional improvements are recommended for the final clarifiers. If the high - 120 - \\HKM\PROJECT\DATA\06WI229124\CMC03717 DOC 08/20/98 @ 1:20 PM infiltration and inflow can be reduced, the peak hour flows may also reduced below the allowable hydraulic loading for the clarifiers. Chlorine Contact Basin. The chlorine contact basin is adequate for peak hour flows of 26.6 MGD. No improvements are needed at the contact basin. Infiltration/Percolation Basins. Since nitrification can be routinely accomplished in the aeration basins, the UP ponds are only used as a backup method of nitrification. The I/P ponds are also used as a back-up treatment system in the event of a process upset in the secondary treatment system. The capacity of the I/P ponds is adequate in their present condition for their back-up treatment functions. In the 1994 Comprehensive Performance Evaluation, the Water Quality Division requested that the plant begin using the I/P cells to the maximum extent possible even though the I/P cells are not required to meet the City's discharge permit. The Water Quality Division's request was supported by the following statements: • Utilization of the I/P cells has the capability to further polish Bozeman's effluent. Benefits to the East Gallatin River and the Canyon Ferry Reservoir could be realized by a reduction of nutrient loads. • The EPA Construction Grants Program requires funded facilities to be utilized to the greatest extent possible. • MPDES permits seek to have communities operate facilities efficiently with the goal of optimal treatment.performance, - 121 - \\HKM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/20/98 @ 1:20 PM Gravity Thickener. The gravity thickener is currently loaded at less than 10 percent of the allowable loading. The basin appears to be in good physical condition. Therefore, no improvements are needed to meet the 20-year design loads. Flotation Thickener. The flotation thickener is currently being loaded at approximately 1/3 of capacity based on typical design criteria. No improvements are needed to meet the 20-year design loads. Anaerobic Digesters. The Bozeman plant contains a 50-foot diameter primary digester and a 35- foot diameter secondary tank. In order to be classified as a process to significantly reduce pathogens under the 503 Federal regulations, sludge must be treated to maintain a mean cell residence time and temperature between 15 days at 35 degree celsius and 60 days at 20 degrees Celsius. The existing primary digester provides a solids residence time of approximately 30 days at 35' Celsius. Federal regulations require a minimum of 15 days detention time. Based on this criteria the digesters have adequate capacity until the average flow reaches 10.0 MGD State design criteria (WQB2-84.32) for anaerobic digesters limits the volatile solids loading to 80 pounds per day per thousand cubic feet of digester volume. Using this criteria, the digester capacity would be limited to an annual average flow of approximately 6.0 MGD. However, the state limit of 80 pound per day per 1,000 fe limit is extremely conservative. Typical, design volumes range up to 160 pounds per day per thousand cubic feet. The digestion capacity of the plant can be increased by utilizing the old aeration basin that was converted into an aerobic digester in the 1982 expansion. The aerobic digester is designed to handle the secondary waste activated sludge. The aerobic digester is currently not used. In order to utilize the aerobic digester a pumping facility would have to be constructed to pump the digested sludge to the storage basins. From an operational and economic aspect, it is better not to use the aerobic digester until the anaerobic digester becomes overloaded. Using the aerobic digester now would reduce the gas production in the anaerobic digester, which is needed for heating. In - 122 - M KM\P R OJ E CT\DATA\O6\M 229124\C MC03717.DO C 08/20/98 @ 1:20 PM addition, aerobic digesters require high-energy inputs to maintain mixing and dissolved oxygen levels. As discussed in Section 4.7.3, it appears the heat exchanger is inadequate to maintain a temperature of 35°F during extended periods of extremely cold weather. The heat exchanger should be inspected for possible scaling on the heat exchanger tubes. Due to the age of the heat exchanger the City should include the replacement cost in future budgets. The estimated replacement cost is $10,000 to $15,000. Insulating the outside of the digester to eliminate heat loss was considered to eliminate the need to purchase gas. However, the cost to insulate the digester was estimated at $19,500. The present worth of the annual cost savings in natural gas cost was estimated at $5,800. Therefore it is not cost effective to insulate the digesters. Sludge Storage Basins and Sludge Handling Equipment. The city recently completed an expansion of the sludge storage basins to provide a total storage volume of 5.0 million gallons. In the expansion, the existing lagoons were modified by removing the center levee. The material from the levee was used to raise the bottom of the lagoon 5-feet. In addition, a new 1.57 million gallon sludge storage basin was constructed. A 45-mil reinforced polypropylene liner was installed in both ponds. With the expansion the sludge storage basins have adequate capacity. The sludge injection truck and nurse trucks are old and in need of constant repair. A recent study of the sludge system recommended replacement of the sludge injection truck and the purchase of a new 6000 gallon nurse truck. - 123 - \\H KM\P ROJ ECT\DATA\06\M229124\C MC03717.DOC 08/20/98 @ 1:20 PM 'l,� I 1 I � I .1 ' 1' I � t� � if L• I } •r �:�: 6.0 RECOMMENDATIONS 6.1 INTRODUCTION This section presents a summary of the recommended improvements including an estimate of construction cost. The need for these improvements, as well as detailed descriptions, are included in the previous section. The recommended improvements are presented in three categories: • Collection system improvements to correct existing deficiencies • Collection system improvements to serve future growth • Wastewater treatment plant improvements The estimated costs for these improvements were completed when the Engineering nag News Record (ENR) Construction Cost Index (CCI) was 5446. These estimates also include an allowance of 10 percent for construction contingencies and 17 percent for engineering services (preliminary design, final design, and construction phase engineering services). The cost estimates include the materials and installation costs for pipe, manholes, service lines stub outs, and street restoration. The costs do not include any allowance for conditions that may be encountered such as high groundwater, utility conflicts, or deep excavations. The cost estimates are for comparison only. Detailed construction costs should be developed when specific projects are under consideration. 6.2 COLLECTION SYSTEM 6.2.1 Infiltration and Inflow Infiltration and inflow is apparent throughout the collection system. The flow monitoring identified five areas where groundwater infiltration rates were above 5,000 gpd per inch-diameter-mile of line. The areas identified are: - 124 - H:\DATA\06\M229124\CMC03717.DOC 08/21/98 @ 10:39 AM • Stream crossing on North Rouse, south of Peach Street • Area southwest of manhole at Garfield Street and Bozeman Avenue • Area flowing into 8-inch main on Babcock between 15th and 19th Avenues • MSU campus: extension to married student housing from Koch Street/15th Avenue • Stream crossing at Dell Place (Between Manholes FO540 and EO505) A TV inspection of these areas should be done as soon as possible to further identify the cause of the high infiltration rates. It is further recommended that the city pursue a program of additional flow monitoring and TV inspection of sewer lines in Zones 4, 5, and 6. These zones are primarily older vitrified clay lines installed in the early 19O0's. It is expected that substantial leakage may occur at the pipe joints of the older lines even when the line appears to be in good condition. These zones were also identified by city personnel as areas where root growth was a problem. Root growth also indicates poor pipe condition. Newer developments such as the area along South Third, also indicate high infiltration rates. A flow monitor located on South Third at manhole G0723, just north of the intersection with Tracy Avenue, indicated groundwater flows of 95 gallons per minute. Table 6.1-1 prioritizes line segments for a TV inspection. The cost estimate shown includes cleaning and TV inspection. The flow monitoring conducted in this study was limited to selected manholes to determine I/I flows from general drainage areas. Additional flow monitoring may be able to further isolate areas for TV inspection. - 125 - \\H KM\P R OJ ECT\DATA\06W1229124\CMC03717.DOC 08/20/98 @ 1:20 PM TABLE 6.1-1 RECOMMENDED PRIORITY FOR TV INSPECTION PRIORITY DESCRIPTION LENGTH-FT. ESTIMATED MANHOLES COST UP DOWN 1 North Rouse from Tamarack to Lamme 2,700 $3,510 F0439 F0330 Stream Crossing at Dell Place 800 $1,040 F0540 F0505 2 Intersection of Bozeman and Garfield to Kagy 3,270 $4,250 F0736 F0649 3 Area South of Babcock between 15th and 19th 5,8000 $7,540 Avenue 4 Extension to MSU Campus from Koch and 15th 5,000 $6,500 H0620 H0546 (manhole H0546 to H0620 5 Zone 6-North of Tamarack between Montana& Willson 2,400 $3,120 F0443 F0326 Montana from Tamarack to Beal 5,300 $6,890 F0527 F0322 Bozeman from Tamarack to Story 2.400 $3,120 F0425 F0317 Black from Tamarack to Beal 2,400 $3,120 F0417 F0313 Tracy from Tamarack to Beal 5,600 $7,280 F0507 F0309 Willson from Cottonwood to College 6 Area that drains to Juniper and Church: North Wallace from Peach to Olive 3,100 $4,030 E0314 E0523 Plum Ave. from Avocado to Lamme 2,000 $2,600 E0313 E0419 Broadway from Avocado to Main 2,500 $3,250 E0317 E0434 Aspen St. from N.Wallace to Front 1,000 $1,300 E0321 E0323 Cottonwood St.from N. Wallace to 1,100 $1,430 E0310 E0312 Front 800 $1,040 E0410A E0416 Mendenhall from Church to Ida 7 21-inch West of Rouse: North Rouse to Oak and N.7th 4,200 $5,460 F0212 G0327 West of N.5th,Oak to Aspen 2.100 $2,730 G0334 G0328 West of N. 7th,Oak to Durston 2,650 $3,450 G0327 G0303 West of N. 10th,Durston to 1.900 $2,470 G0301 G0406 Mendenhall 2,700 $3,510 G0581 G0302 North loth, Durston to Babcock 1.200 $1,560 G0411 G0412 Between Babcock&Main from 7th to 1,700 $2,210 G0582 G0514 Ilth 1.100 $1.430 G0554 G0547 Between Babcock&Olive from 6th to 800 $1,040 G0552 G0551 IIth 1,300 $1,690 G0538 G0534 7th from Olive to Story 2,500 $3,250 G0529 G0527 West of 7th from Olive to Koch West of 8th from Olive to Story West of 9th from Olive to College TOTALS 68,320 $8&820 A detailed cost effective analysis cannot be completed until the extent of needed repairs is determined. However, the treatment and transport costs associated with the excessive I/I can be estimated. As-indicated in the discussion of the wastewatertreatment plant, several of the,treatment components are near capacity in terms of hydraulic loading. Without a reduction in the I/I flow, additions would have to be made in the headworks building and a new primary clarifier would have - 126 - \\H KM\P R OJ ECT\DATA\06WI229124\C MC03717.DOC 08/20/98 @ 1:20 PM to be constructed. Reductions in I/I flows could also delay the need to increase the size of major outfall lines on North Rouse and from Manley Road to the dual 20-inch lines. Costs related to the treatment and transport needs discussed above are estimated in Table 6.1-2. TABLE 6.1-2 I/I RELATED TREATMENT AND TRANSPORTATION COSTS COMPONENT DESCRIPTION ESTIMATED COST New Primary Clarifier $550,000 Headworks Modification $100,000 42-Inch Outfall Line,A4-(F0109-58) $1,989,000 North Rouse Improvements,A7(F0330-F0109) $868,000 TOTAL $$3,507,000.00 Assuming a cost of$1.30 to clean and TV lines and an average repair and/or replacement cost of $27.00 per foot, approximately 64,000 feet of sewer line could be rehabilitated for the cost of constructing new facilities. It is emphasized that a cost effective analysis should be done once the TV inspection is complete. 6.2.2 Collection System Improvements As the TV inspection work is finished it will be possible to evaluate the type of repairs or replacement that should be completed. In some instances localized repairs may be sufficient while total replacement may be required in other areas. If the existing lines are still structurally sound, an inplace repair such as sliplining can be considered as a cost effective repair. The recommended collection system improvements to correct existing deficiencies are summarized in Table 6.2-1. The table does not include areas, that may be identified through the TV inspection, as needing repairs. While the improvements shown in Table 6.2-1 correct existing deficiencies, the improvements also are sized to allow future growth. These improvements are also shown on Plate 5.3-1 included at the end of this report. The improvements in Table 6.2-1 have been assigned a - 127 - \\H KM\PROJ ECT\DATA\06WI229124\CMC03717.DOC 08/20/98 @ 1:20 PM priority ranking based on the extent of the existing problem and the growth patterns within the City. The priority rankings should be reviewed frequently by the city staff and revised to meet anticipated growth patterns. TABLE 6.2-1 RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS TO CORRECT EXISTING DEFICIENCIES LINE ZONE SIZE LENGTH TOTAL PRIORITY DESIGNATION NUMBER DESCRIPTION INCHES FT COST$ 1 W 1 2 Diversion of flow at 15 2500 $175,000 manhole J0410 to Zone 2 2 W3 4 Intersection of Hoffman & 15 1,150 $124,000 Tracy to S. Willson 3 A8 5 Rouse from Tamarack to 24 8,000 1,139,000 Ice Pond Road 4 E8 1 Tamarack St. from N. 21 &24 4,700 $468,0W Rouse to Front and Front St. to Lamme St. extended 1 $1,906,000 *Table does not include areas or lines that may be identified through the TV inspection able 6.1-1 as needing repair). The collection system improvements recommended to provide service to future development are summarized in Table 6.2-2. These improvements were sized to provide service to the entire area within the 20 year planning area boundary. The timing of these improvements will depend upon the timing and location of future development. These improvements are also shown on Plate 5.3-1 included at the end of this report. - 128 - \\HKM\PROJECT\DATA\0 W229124\CMC03717.DOC 08/20/98 @ 1:20 PM l: M If I 0 L• > I •y I_ TABLE 6.2.2 RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS FOR FUTURE DEVELOPMENT ZONE 1 MANHOLES LINE PIPE LENGTH DIAMETER INCHES TOTAL COSTS DESIGNATION UP DOWN FEET $ El IEl IE2 2640 8 $143,000 E1 I E2 I E3 2640 8 $143,000 E2 IE3 IE4 3000 10 $171,000 E2 l E4 1 F,5 2700 10 $154,000 E2 IE5 A0601 800 12 $48,000 E3 A0601 C0502 4100 15 $287,000 E4 C0502 F0209 11000 18 $902,000 E7 1E6 IE7 3000 8 $162,000 E7 IE7 IE8 2300 8 $124,000 E7 IE8 IE9 3000 12 $180,000 E7 IE9 1E10 1400 12 $84,000 E7 1E10 IE11 1000 12 $60,000 E5 lEll C0505 2000 15 $140,000 E5 C0505 C0507 700 18 $57,000 E6 1E20 1E21 3000 8 $162,000 E6 1E21 1E22 2500 10 $142,000 E8 1E22 1E23 3000 12 $180,000 E8 1E23 261 1500 15 $105,000 E8 261 C0507 3400 15 $238,000 E8 C0507 D0508 3600 18 $295,000 E8 D0508 DOS 12 1300 18 $107,000 E8 DO512 D0420 2200 21 $204,000 E8 D0420 F0330 3900 24 $394,000 TOTAL $4,482,000.00 - 129 - \\H KM\P R OJ ECT\DATA\06\M229124\C M C03717.D OC 08/20/98 @ 1:20 PM .. � + _ _ - - - � r-- 1 _ �• , � I. _� r. L•'., _ '�n .. ' >;. � 4 TABLE 6.2-2(Continued) RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS FOR FUTURE DEVELOPMENT ZONE 2 MANHOLES LINE UP DOWN PIPE LENGTH DIAMETER TOTAL DESIGNATION FEET INCHES COSTS$ S6 B21 B22 3700 8 352,000 S6 B22 B23 4300 10 421,000 S6 B23 B24 2600 12 263,000 S6 B24 B25 4200 15 454,000 S6 B25 B26 4100 15 443,000 S8 B26 B28 2700 24 383,000 S7 — B27 3500 8 189,000 S7 B27 B28 4000 10 228,000 S8 B28 B218 2500 27 318,000 S9 I0601 I0610 1200 12 118,000 S9 10610 J0501 1500 18 183000 S9 B 34 10601 4000 8 215,000 S10 B 32 B31 3000 8 161,000 S10 B31 J0501 2300 10 126,000 S10 J0501 J0410 5800 15 612,000 S11 ---- B219 4500 8 243,000 S11 B219 B218 3000 10 171,000 S11 B218 B217 2200 21 200,000 S14 -- B216 2400 8 130,000 S14 B216 B215 2300 10 225,000 S12 B215 B217 5400 15 378,000 S13 B214 B213 4100 12 242,000 S13 B213 K0526 1700 12 100,000 S11 B217 B212 3200 21 291,000 S11 B212 B225 2600 21 237,000 S11 B225 J0401 2500 24 252,000 S15 J0401 N5 2700 24 272,000 W1 J0410 950 2500 15 175,000 W2 955 956 400 24 40,000 W2 956 10101 900 27 136,000 TOTAL $$7,618,000 130 - \\H KM\P R OJ E CT\DATA\06\M229124\C MC03717.DO C 08/20/98 @ 1:20 PM I ' `-� _- III — P I �a +.,� .. �I , �. ,;. �� J � � , �k' ZONE 3 - None TABLE 6.2-2(Continued) RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS FOR FUTURE DEVELOPMENT ZONE 4 LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ Al I0013 58 500 36 $100,000 W3 F0715 F0608 1150 15 $124,000 TOTAL $224,000 ZONE 5 LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ S1 6S1 6S2 4600 10 262,000 S1 6S2 6S3 4200 12 240,000 S1 6S3 6S6 2300 12 226,000 S1 — 6S4 2300 8 218,000 S1 6S4 6S5 1800 8 171,000 S1 6S5 6S7 600 8 57,000 S1 6S6 6S7 1800 12 177,000 S1 6S7 6S8 3000 15 193,000 S5 6S8 6S9 2800 21 266,000 S5 6S9 6S23 2100 21 200,000 S5 6S23 F0663 2100 21 200,000 A8 F0663 F0330 8000 24 1,139,000 S2 6S10 6S11 3200 10 182,000 S2 6S11 6S12 2000 10 110,000 S2 6S12 6S13 3400 12 195,000 S2 6S13 6S14 2600 15 181,000 S2 6S14 6S15 2500 15 161,000 S2 6S15 6S16 2800 15 180,000 S3 6S17 6S18 3700 10 363,000 S3 6S18 6S19 6500 10 625,000 S3 6S19 6S20 800 15 86,000 S3 6S20 6S21 2000 12 197,000 S3 6S21 6S22 3200 12 315,000 S4 6S22 6S16 1200 12 118,000 S4 6S16 6S8 1800 24 2.56,000 TOTAL $6,318,000.00 - 131 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 1:20 PM I. .a s � `�� t � _ - - - -- - - - - - - - - - - -'1 �� :» i _ I�� i r� ♦ � I a �. .r .� I � � '� �� a I� ';l TABLE 6.2-2(Continued) RECOMMENDED COLLECTION SYSTEM IMPROVEMENTS FOR FUTURE DEVELOPMENT ZONE 6 LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ A7 F0330 F0109 4700 33 $ 868.000 A4 F0109 45 6400 42 $1.414.000 A4 45 58 2600 42 $575,000 A4 58 Plant 1200 48 $ 265.000 E9 — — 6500 8 $ 350,000 E10 — — 2800 8 $ 150,000 E11 — — 5100 8 $ 274,000 TOTAL $$3.896,000.00 ZONE 7 MANHOLES 77 LINE PIPE LENGTH DIAMETER TOTAL COST DESIGNATION UP DOWN FEET INCHES $ N1 B227 B220 2600 10 256,000 N1 B220 N1 2600 10 148,000 N1 Nl N2 1800 10 103,000 N1 N2 N3 3100 15 200,000 N1 N3 N4 900 15 58,000 N1 N4 N5 2400 18 195,000 N2 N5 N6 1500 21 143,000 N2 N6 N7 4500 24 455,000 N2 N7 N8 3100 24 313,000 N3 N8 N9 3900 27 468,000 TOTAL 2,339,000 ZONE 8 E 12 7500 15 478,000 E13 7700 15 496,000 TOTAL $97400.00 TOTAL ALL ZONES $25.851,000.00 - 132 - \\HKM\PROJECT\DATA\06\M229124\CMC03717 DOC 08/20/98 @ 1:20 PM �, - - .. � - 1 I 4' yr I 6.3 WASTEWATER TREATMENT PLANT IMPROVEMENTS The sludge storage project recently completed by the City was the most pressing problem and had been identified in past evaluation reports completed by the State Department of Environmental Quality. With the expansion of the sludge storage basins, the immediate need at the treatment plant is the replacement of the aging sludge injection and transport equipment. The replacement cost for a new injection truck is estimated at $185,000. The purchase of a new 6000-gallon nurse truck is also recommended at an estimated cost of$110,000. While the sludge storage was the most critical need at the treatment plant, minor additions to the sludge metering system will enable the operators to obtain more accurate data on the plant processes. The 1994 comprehensive performance evaluation conducted by the Montana Department of Health and Environmental Sciences noted the need for better sludge monitoring. It is recommended that flow meters be installed at the following locations: • Sludge line from the gravity thickener to the digester. • Sludge line from the flotation thickener to the digester. • Sludge line from the digester to the storage basin. In addition to the installation of the flow meters, it is recommended that the gravity thickener overflow and the flotation thickener underflow be sampled on a routine basis. The sampling of the sidestreams will allow the actual solid and BOD5 loading on the primary clarifiers to be determined. As discussed in Section 4.7.3, it appears the heat exchanger is inadequate to maintain a temperature of 35°F during extended periods of extremely cold weather. The heat exchanger should be inspected for possible scaling on the heat exchanger tubes. Due to the age of the heat exchanger the City should include the replacement cost in future budgets. The estimated replacement cost is $10,000 to $15,000. - 133 - \\H KM\PROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM 6.4 PROJECT SCHEDULING The recommended collection system and treatment improvements were prioritized based upon need and anticipated development. Table 6.4-1 shows the improvement priorities. The priority list includes the recommendation for the 10 most immediate needs. Additional projects are listed but the priorities should be assigned as needs develop. The first priority is the purchase of the sludge transport and injection equipment. The equipment is a vital component in the city's ability to dispose of sludge. An equipment failure could cause a serious delay in the disposal of the sludge, which in turn could lead to treatment and storage problems. The second priority is to complete the TV inspection of the lines listed previously in Table 6.1-1. This represents approximately 68,320 feet of line. While the repair of deficiencies identified in the TV inspection is listed as the second priority, the actual location and extent of repairs cannot be determined until after the TV inspection is completed. Likewise, cost of the repairs cannot be estimated until the TVing is completed. The cost of repair for high I/1 areas and the repair priority should be made after a TV inspection of the suspect areas. A regular program of Tying the sewer lines should be established so damaged lines can be identified and a cost analysis can be completed to determine if the repair required is cost effective. As growth occurs, the prioritized list should be reviewed and revised to reflect development trends. As development occurs, it is expected that partial segments of the identified lines will be constructed. For example, line S3 extends from Graf Street to Nash Road. Extension of this line to the south will most likely occur in several phases. The city should review development plans to ensure they are consistent with the wastewater master plan. - 134 - \\H KM\P ROJ ECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM TABLE 6.4-1 PRIORITIZED SYSTEM IMPROVEMENTS LINE ESTIMATED PRIORITY DESIGNATION DESCRIPTION COST I Purchase of sludge injection and transport trucks $295,000 21 Table 6.1-1 Tving of 68,320 ft of line per Table 6.1-1 $88,820 3 Correction of deficiencies identified by Tving 4 WI Manhole J0410 to manhole 950 175,000 5 N1 Zone 7 Line(Manhole B227 to Manhole N5) 960,000 6 W3 15-inch line at Hoffman to Willson 124,000 7 A8 Outfall from Zone 5,Manhole F0663 to F0330 1,139,000 8 S4,S5 Graf St.and Zone 5 outfall Manhole 6522 to Manhole F0663 1.040,000 9 A7 33-inch line on Rouse 868,000 10 S9,510 South of West CollegeB34-I0601,B32-10501 502,000 S13 Manhole B214 to Manhole K0526 342,000 S11,S12 Zone 2 lines 1,772,000 E8 Tamarack St. from N. Rouse to Front and Front St.from Tamarack 1,000,000 to Haggerty lane(MHF0330 to MHC0507) E9,E10, El I Bridger Drive,Hillside Lane 774,.000 E5, E7 Bozeman Trail Road(Manhole IE6 to Manhole C0507) 807,000 E6, E8 East of City(Manhole I E20 to Manhole C0507 827,000 S2 South of Graf St. 1,009,000 S1 South of Graf St. in Gardiner Park 1,544,000 S7,S6,S8 Zone 2 South of Stuckey 3,111,000 E12, E13 Mcllhattan Road&West 974,000 A4 North Rouse to treatment plant(MH F109 to plant) 2,254,000 Table 6.4-1 does not include a cost for correcting deficiencies that might be revealed in the TV inspection. Those costs cannot be estimated with any accuracy until the type of rehabilitation needed is determined. - 135 - \\H KM\PROJECT\DATA\06\M229124\CMC03717.DOC 08/16/98 @ 10:17 AM , � ,. _ � x. ': - ,. REFERENCES Energy Resource Management Inc., 1994. Detailed Energy Study of the Aeration System for the Bozeman Wastewater Treatment Plant. HKM, 1991. Amended Bozeman's Water Reservation Request. HKM, 1990. Bozeman Wastewater Treatment Sludge Storage Facility Engineering Evaluation Rep rt. Joint Task Force of the Water Environment Federation and the American Society of Civil Engineers. 1982. Gravity Sanitary Sewer Design and Construction. ASCE Manual 60. New York: American Society of Civil Engineers. Metcalf and Eddy. 1979. Wastewater Treatment/Disnosal/Reuse. New York McGraw Hill Morrison-Maierle/CSSA, 1994 Sewer Service Area Study for Golf Course Partners, Inc. Peccia, 1991 Bozeman Urban Transportation Plan 1991 Update. TDH, 1980, Design Criteria for the City of Bozeman Wastewater Treatment Plant. U.S. Census Bureau, 1990 Summary of Population and Housing, Bozeman Division, Gallatin County, MT. U.S. EPA, 1984 Construction Grants 1985. - 136 - \\HKM\P R OJ ECT\DATA\06\M229124\CMC03717.DOC 08/20/98 @ 1:25 PM ,_�' _I I .�. �' r ` �l` .� ��,� ' ' ":� I .) 1 J ► " . ,., "1 9 / Moss Bridge Rd. �9 West Lake Rd. O `ns a LEGEND ►��, p PRIMARY MONITORING POINTS Ilk ABANDONED I p SECONDARY MONITORING POINTS BOZEMAN DRAINAGE ZONE 1 10013 BOZEMAN DRAINAGE ZONE 2 010010 �- ------- BOZEMAN DRAINAGE ZONE 3 ------- BOZEMAN DRAINAGE ZONE 4 1006 ;Yn 10 � ------- BOZEMAN DRAINAGE ZONE 5 BOZEMAN DRAINAGE ZONE 6 1oo&\ �\ HIGH MAINTENANCE AREA Bannock tage ABANDoNED ESTIMATED INFILTRATION ABOVE 5000 GPD/INCH • DIAMETER • MILE 0 5 �Q(y -.-- B• � 9 I0003 10 2� — Simmental Trail ff . 10 N Deadmans Gulch Ct. 0 I `` _`I G0137 3 4 I I I 10111 o GO108 <I C0135 Orville Way'.1 I J j I G0135 500 0 500 1000 0110 MG0107 yc J ( scale feet 1 G01 G0134 > i 1 I s_ 1 C0106 o '- Rawhide Ridge Ct. ~ 0109 G01 �• 0133 Q1 i G0105 Got 0132 c (n I G0122 G01 GO •AC F01 W 0108 1 G0104 J a G01q Y/ 1 m eadow Wy. Baothlll Ct.I 0103 G01FGO11115.1' G01 G0125 0107 � lL a a G0102 m G0117 - 6 Baxter Rd. I �_. 10101 g4•AC 10102 10103 101 1010 Mandeville Ln_ J G0116 GO riffin D. 1 G02 O a heat Dr. H0205 GO . G0217 L G0222 1 G0203 UZ G0201 L G0218 r1 i G02 H0204 GO G 1 ickles Dr. eokter � H0203 Off@ I I 1 \ G02 H0202 �— G4i7216 F 201 1 P 0 08 a GO 0 09660212 G0213 GO CO214 H0201 G 10•VC CO206 I 1 Oak mSt. Oak St. I G0334 20• 4 __ H0330 H0329 ��____ — 103 35 334_ 333 H 3 331 — ——$——1.1 H326 15 15 M lewoodd�Sty( T1 GO 103 —•� 333 103p34 IOS35 I NO ACCESS Ln °p ..0 .I.H327 TO THESE [] 103 1 '~ YY MANHOLES` 03 G0333 10321 i GO 0 Bi ch St. z I1037® '10320 �z �H0326 He lock St. G03 9 32 GO 10319 NOT MAINTAINED 1 -1� I GO BY CITY pNC�\'032a 10318 Stevens O3 �^) GO 26 103 1100324 10317 1036 St I H0325 Juniper GO 3 G03 z z 10 1 Windsor H 319e•• 18• _18' P 10 10315 St.I FT63'QH0321 H0322 HO323 HO H0341 H034g8• G0311 18• G03 p /] a 2 G03 G03 03.L2 Q �/�0 H03,{j 8•\'C H0318 Iro GO `S C W`V 1� I-1 OVERFLOW CAPABILITY S 0313 Al0 I 1 u ff G03 Aspen St. AH0339 �l� I TTTTTT / H0315 1 Terrace Ave. I G03 ro G0328 v -,D Q -p 10312 O10 II_ H0317 I = attonwood St. ;U T 10311 i AIm� 10- 1 qH0338 GO G 3 0 ,.; N 1 HR7311 314 1 u l� �L Q r 1031QQ 10308 ' 302 H03 1 H030`HO30e13 •H030• H0309 H031D H03 6 G03�•yCG03O2)03 6031 ea u urstan Rd. > J0413 1•z 7510307 12• 2• 18• 1 AC _ _ — H_-Q_---_ G03 4 _.—Ko J0401103 2 4 5 11 al I 110 �• 1.; m% I 1111 m m KO p�J0409 J 11 0407 1 • 1 a Ia iW I HO J • G D K0412 1-it. K0435 KO 4 I 10 ID4 1 Ts I I H0434 GO4 6z 0 KO KO I 10403 1 I 1 1 I I a l I G04 1' I � G0431 z coa� Z SEE SHEET NO. 3 BOM"WASTEWATER FAmrry PLAN FIGURE 4.4.11-1 ECOLLECTION SYSTEM 11�•HICIII IL T 1 ENGINEERING Jf�C BM229I24 AUG.1998 ___ :: - IT 2�n/ I of i --=4�_ 3 4 I I 1'� 500 0 500 1000 I—+ scale feet LEGEND p PRIMARY MONITORING POINTS p SECONDARY MONITORING POINTS BOZEMAN DRAINAGE ZONE 1 c o BOZEMAN DRAINAGE ZONE 2 n ------- BOZEMAN DRAINAGE ZONE 3 ------- BOZEMAN DRAINAGE ZONE 4 WET WELLS UFT STATI BOZEMAN DRAINAGE ZONE 5 C. E0111rn E0112 Brid 9er Dr. BOZEMAN DRAINAGE ZONE 6 _ HIGH MAINTENANCE AREA PVT. ;= ESTIMATED INFILTRATION ABOVE F0112 Commercial Dr. Eo„on E0102 5000 GPD/INCH • DIAMETER • MILE FO ?O•A L C F0113 LH ( F0116 01 0103 E0105 •o FO F0114 F01 — 0'AC F0110 E0115 L� \ FO _ . 01 0109 • E010 20•AC t� Q O6 E0101 3 cr-- 01 s p 107 Hillside Ln. F01 108 Z F0117 Griffin Dr. F02 F02 F02 E021®•pVCE 2Ua FO 4� SEBENA N.E.TRUNK 2 NOT IN SERVICE F02o6 207 Bryant St. FO F0202 F0203 F0204 205 ,n EO E0202 1 VC FO l E0201 EO FD2 Oak St. Big Gulch Dr, FO 14• 0212 \\ .O F03 Birch St. r FO &Q Q) n 9Q, (10 n i er E0305 Q /` Ta ara I. t. F0322_ FO E03 9 0307 \ P � 0318 — 4 AC O. As e St-� E03 E0308 0321� 322---) fit. L12t I . O EO0333V p FO ' E03 0319� F03240) I I z E E0325 r E0316E0 1p E032V . Q 0308 F0310 z C U I • �- Q 0 n e• O 0443 U) Shor St. L- EO EO 0440Q 0442 T U i St. Q - �F0435 0 IFridle t F044 m 0422 39 - DO n \ SEE SHEET NO. 4 BOZEMAN WASTEWATER FACILITY PLAN FruRE 4.4.1-1 COLLECTION SYSTEM IIIISE-I-111011 SFEET Z ENGINEERING 6M229.124 I AUG.1998 SEE SHEET NO. 1 J 406a4}' I HO O N j K04s2 L u') ,v 1 Q 104X V 4 6r, H0433 434 G0456 Toole St. Q I N N 10402�I N I I t eic H04 H04 I 1 0 9 GO 2 4 G Q AJ0407 I 10405,I I H04D2 HO''". I+ I Z Z -O z ZI z1 zl z I z L I IN I L a O1 K0433 KO K0451 I I 104 104 I I GO 0 lf� G0464 > K04 K0416 N > O 104 I H0432 I Q > Q > /?b Joaos 4— 'ioale W. Beall d// 1- 1. co4so Z Z 0 J 4 Cascade S t. K0409 K0450 YJOa05 i �17 0416 Q`!��H0419 I H0431 In -0 K0415 L I 4rH0418 I GO O N � II I Co� � Mend I h1�ll St. KOa 0)1 K0449 �J0404 1 H0430 K0408 O O 1 Z gppN�A 1041 I I O K0414 0 I 104 �10414 1H0417 I z z 4 G 432 Li 1r0122. 042a-0447 I IoaO'/ OW. Main St. C0 G0415BroQdWater a 4 CL 0403 0411 HO 8 YC H0427 G04 •co4 ---GD.4.4 Q) �' l H04�&--0H042IT 5C,0. ° G041 . _____-_b424 K0446 _/ -H0420--H042g•Hp52810422 8• 1k0423 Oa a403 4 -- - ---- -051 - a20a260 ;,,�.k St. _J04,4 �,—SE 105 10 D - 3 ---- ----- N lg h �!'g• 8•VC H057a HO 91 53 G G05 a° -N 07 I• �• HOS --11�79 -$-- a�-' S�� • b562 lf� � °4 01 O +'1 I 10`5& g• %o5 D I I I n1 d� `N G0�I°0. I I V f' S t, ¢J0513 105�--� O 105� 7 HO516 HOS •H0528 � H0575--H057 HOS 3 2 37 •0510- KO51� K0521) I 6' -�-' g• K0530 I I H0525 1 o 1 3 I 1 s03 � 105�t�-� 0516 I I '� r � I • N0545 I� I Curt J St. C C a OJO512 T Ca +' � H0544 O O L N C I� 105160 105# H0515 H051� H0524 - 2 36 K 506 a- K050 K052� -� I N AI 0515 II OS H0517� Q -�-' - y- 0 0 GO Ko R Q VQ I I O I Jos11 2 1OA2 b los[b I I o54e K O L m. HI 73 'p 10514 T 1539 4 8 H051 e•K o c h S t • •H05 H 54� H0556 H094 10• - 0• 2 3 (� K0574 K0519 lI 101I0p52 C.O. I 10 I I 1 I ,Iaq RI I �GO 8• K0505 K0508 K0528 N J0•` 2 0®•-�08 -'0 5 10511 10�1�Z 5 / 10537 I I H0 HO5,0 HO H05 1� I• I I GO 4 S t o S t' OS 05 m ro IN 0 O I 1054 1 0536 "'"' ID I 5 6 7 6 577 K0507 K0518 �-1- JGS�y I °0 I� 5# H0508 I I I I I 0 0 ' GO 8-- osoa K0527 I N os I H0 I I I I I L 10520 I•N H0506 HO G •, CO CO u i !n 10�510 I 105�3 1D H0505 D k r s a rl S t. _- Fa Ian �t. 4 5 6 6 2 _ J0507 J0504 I -6 105 105� I HO �(� I I I 1 I GO I B• G05 I 25 K 24 23 / H0503 G �0505 0- 1051� C.a- 31 1 3o c.o. I HO I I I D 6 I I A d Jan St. a1 N l00 1f 1 ,p5 H053 H0 OS 4 5 8 - 7 2 I G05 ��yy$�J0503 .I I 105 • 0• I I I I I I GO I J0502 1_ 10516 ♦ +-'I HO H050 I I HO 5 5HO 6 1 1 C.O. �I _ _ HD 5_ f2 Gd t (^' II e St. I • _CO$ G015$2_ PVC -- -.--J -_- H G0�Gos YI 0650 652 6 6• �- � _--. W. College' St. 1�1� CO I � V9> � H. Huffine Ln. I FI __ _ �g_ _ L 1 10 6 / H0829 1C1rf'san t7'606 �10fi25 Grant -12r 12•VC � osos I ChQmbe,- 1 Go GO 6• G .106 I I 1 C'lev , ann d 106 I lain Dr Hob O l ofi2a cosos43- -c0643---— C Julia r G0642 Gob GO S A--Q I Hosz7 / 06o co a osaa Arth r St 1 i �^10 LDO I Martin V0 6�QD 2y3a�� •I' Dr - (( W. (;a r f i e l d S 621 621 GOeB�pbA2 -Dso6a1 0GO 638 I G0671 0823 H0615H�00661M-'0�y1 2 O6 e�a7�' 062 GO 9 r 0�32 On j �Hp611 H 6 / I1 /� y �G0`�}0 ('y Garfi Id St.l W HO13r18-�Q1fi 061T �.D I G063 /I O n t(3 1� i.. 10622 I 160'19--�618 GO 1 G06 G0637 i G0870 b� / IJ1 LU Ha St. O110621 /— co j bi$�Gos,s co69� Ia I ( W 106I l j" / c06,591 S0612 G0611 I 1 • I I 1 1�• 106 G ant t. �I I W II 1r'�tGG6,G State 1% 'tinca�p �t. HO6111060�p�6pe�'7� 7H0606` H0605___ H0603 4 r I GO) 82 �/W 106 1 - - -- -- �// Cn 11z la• H07 +A0705 1 G07sa Go F07 •I'H0711 /o 11 G07 Vv� 0 H0 2 1Ho704 H07 -- C.O. 1 �- 07 I 1 O H07 --�H0708 `J n i v e r J I t y \ �P�� 0722 G07 11� I pr07 1 I YI 6H0701 V0707 C0713 U \ G07 7/ Remington Way S I� 8•Va G0714/ 'P Kogy Blvd. G070 Kogy Blvd. �/ G07 AG0708 � / L WG0707 M G07 F07 cri e F07 GO G07 Stucky Rd. GO . -0 _ Fryslie St_ _ _ _ .._----- J _G1OI e' G GD814 1-GEB,®t (`�Ol6tting ,St I .0. 17 a, 08t�o — — Go a a / 0812 . / .61 Morrow St o I 00 — L I 4 11 Spring I O GO 0 j GO - O •1 J e Creek r.I Arnold I 1 g• I I b1 I H, ndersoItT I FOE6 I I GO Go — — G08f GO O I S t 8 'zl Q I Staudaher -St.1 2 LEGEND -'-;,•--i co61 cob I I � I �I ► I IF 1-Jt -------------- SECONDARY p PRIMARY MONITORING POINTS ml 9w 'GpT6z4 26 zfi - -_, - Q SECONDARY MONITORING POINTS `+ co 060, i 1 Z BOZEMAN DRAINAGE ZONE 1 GD raf et poc _GO I -•------- ----•-- GO - BOZEMAN DRAINAGE ZONE 2 G09 Fieldstone Dr. F0905 ..................... ...... !• ! BOZEMAN DRAINAGE ZONE 3 -PVC ------- °..B ;-- -----_ BOZEMAN DRAINAGE ZONE 4 Concord Ur. :: : . BOZEMAN DRAINAGE ZONE 5 I ' BOZEMAN DRAINAGE ZONE 6 t; j:.. . . . L3 HIGH MAINTENANCE AREA ,- --, ESTIMATED INFILTRATION ABOVE 5000 GPD/INCH • DIAMETER • MILE ! 1 500 0 500 1000 BOZEMAN WASTEWATER FACLITY PLAN FOJRE 4.4.1-1 scale feet COLLECTION SYSTEM ��N-•�•1� SHEET 3 ENGINEERING 6M229.124 I AUG.1998 SEE SHEET NO. 2 C: Vlllar ist. O I C- EO > I Y13 �1 r• \ 6 v I I �_.Uavls DO C O qo C U _ 042 EO a N. \ Be St. C� F04 I o mD04 U, U F04 F - II I -- 041 • 7 NEW M am e D0415 10� I L St. LHL D0406 Z F04 Z F Z Ifl047 I1 -g-- E0435 6 0 D0411 F -----P'-- DO D0405 D0418 \\\\ LH. 10421 0430 i 8• 8• 4 408 409 A D0417 \� 0 9• 0402 ___DO 1, . ' F0436�1' E0407 0.> o� D040Y/a�n D0418 I Q > �., _ _ DD 'Sf osv 11' E05�§�_..� Babcock St. -,] E. •L-> OCk D 4 g p�� 70'DOS 0512 --� g• E05 p OS 9 0 °DO r F05 EOs F05J4 c� Olive E -g$ Olive St. CL L VeE052g3 D0529 0 • y - rr) 0522 DO F0516 Y EO m (.,) 9• E057' D DO ' D Q) T �E05 Pll 5 7 F0521> Curtiss St. Q F0529U F0532 E05�050 DO DO E. Cu iss � > > > DO g F0515 U F052t� E0517 O� D0 DOS D0502 CO p ,�C0501 VO O LH.N E0505 Mead 80508 O Bogert PI, z ow 0502A �g• B050'S• 10 DO DO °� C0504 B0508 050 (A _F0520 _F05 0 Story St. Co 0• C0506__ � C0503 B0505 80503 _____ S . ~CFO 03 ��C+ C0508 0505 � `` B05C2 I F05_ F0514 n- 0502QE05 D0506 o99P B0504 B0501 0602 LH. FO - PVC E0512 D05 /'� \.� A0601 F0508 F0513 LH, O F0524 F05 I "-7 01) FO uis St. DO _ e F0538 EO / 12 4 0 1 00610 d D0503 B VC E0603 A DOOM S. D0607 � Fob • $-- 60 I II7 bs6 D0606 3 \�� Virginia Dr. F0607_ m _0Q F0638 I '\ r ,T 9- _ _ I� II F06 F0635 FOU -Q D 11 �� p James St. co FO6 FO6 i F0625 % I c e Pond Rd. D0605 O F0624 FO6 065.� I QoL (0 Quail Ln. F Zi II F 63 F0634 F065 i I F0663 j FOB F061 F0 1 D0604 Cn m 63 F063 I F065 F0662 / D0603 _ WII FO61 2 FD629 F I F064 FO65 I F0661 D0602 W II ¢ ,o Haggerty Ln. 01 p F0628Fpg I 1 E06 -6 Bluebird L n. WF0617 _ Q 064� F06 F0660 - F084 = I I a > o of QI ° d'^) 1 II v 2 < -0 E 0 8P FOB) F0659 I Robin Ln. F0 � p p O I � ---- W I II o m I I op\e W FO6s8 FO6011 F0668 F• 1 �^ J 0a- F0758 F07 m 0704'II'Cr2 07a i L f j 011y--_Dr. D0743 D0744 D0751 MOUrItp�h jF F0757 C) 8 3 " D0741 Mason ct. I D0745 D0750 Sp/�hd �` FO F0772 >, Ep 9•P rest 8 Ot �� f E07 4 E07 D0736 D07 p15 d D0747 A or Dr. /0707 Fo�i 0740 \ACC 01 a 35 _— b FO -07 IIF00 7 12 (d� E07/EDE O gS D071 D074y D00771409 7 F0766 O E0737 0737 . DO3 D073 D46 J F E07 06 Q FF071%" F0764 O N Ce arview D0708 30 P e_rk-in_s P E07 D07 I Dr. E O. D072810•F071M•••G E C>i G p -�---� �, I 0 E072 e ar lew 07 N \ 07 Q - / F0735--__ \\ \ F0762 E D0707 0736 i- - Ea le O F0734 075 I Vo� [ Do7zs D 728 pal 4 0 Bald _ 0 �i OG 0730 ED? 0708 -- \d1' F07 F0761 E0713 X C.OE __` ro 0729 F072 0 X E07p9 EO 21 D0721 g' D07 D07 F07 F0733 I 0780 O q4\ 07!O (,�I r e D0705 Alpine W y. F072 007y / i FO \ E07 `" p -1r F0720 �� F07 'i t� (�' .,\Sa D0700711A 0712 D07 �'•' >,) F0732 F0 ll r\o;7y ISI O EO 001716 E07 i�lPrry Dr. U F07` •E0 Vol, --- D0704 Trail E07b7 EO __..__—_ F07 �.-0W.- D0703 Kagy Blvd. Boz man Trail Rd. 0719 - TEMP. ECT10A, - -- F0731 � _ ...ABANDONED 821 -� C' 0838 weS{ri•g F0823 Dr, 0 LEGEND � _ F0818 FO 0815 0820 FO O PRIMARY MONITORING POINTS v- 0819 O SECONDARY MONITORING POINTS Q° F0817 _ a BOZEMAN DRAINAGE ZONE 1 Sprinqq Creek Dr �0835 J m —_ BOZEMAN DRAINAGE ZONE 2 mold cat. pFD634 a -------- BOZEMAN DRAINAGE ZONE 3 Q °80 U) u) ITF0833 o -------- BOZEMAN DRAINAGE ZONE 4 ' 8 I -0 U -C BOZEMAN DRAINAGE ZONE 5 a Q) Bradley gnde = _ __. _ BOZEMAN DRAINAGE ZONE 6 gnderson iE 1b 1 F0832 1 HIGH MAINTENANCE AREA c 0 0 Q E of L I ESTIMATED INFILTRATION ABOVE 0+ o Graf St. �- F0831 co I 5000 GPD/INCH • DIAMETER • MILE 14, --i -I 0' n FO830 F0829 I + J.I. .I I 0• FO F0828 I_._� J North Dr. ♦ -- 8 BVF0907 I •) -d Sourdough a �. > ----I ------------- Billion PI. Q O i J ! i I n -:.I � K F0903 \ a�\ I I 1--t`! ...... L,%Z..-"�' O Heritage Dr. o ------; F.- ", 3 :: t I —N— v ................ Silverwood Dr. ................... ...................i 500 0 500 1000 scale feet BOZEMAN WASTEWATER FACLITY PLAN FIGURE 4.4.1-1 COLLECTION SYSTEM 111�=•I�ICIII SHEET 4 ENGINEERING 6M229.124 AUG.1998 a , Wastewater - 20 YR PLANNING AREA Treatment Plant E13 15" 7\ ae. 9� Y05814.Ra. —N— K. Ab N8 10013 ~ 4qr 27" N3 N9 - s yi. 0 1/2 1 24" "eo scale mile simm."tm n \ - t. N2 o s N7 g 457 A 5 Acz'. 3 El 6"a;ae.r 24" awmni,:t aQ� $ y �z�� ' E1e 6" 27" N a g 24" k W2 Y a rim"w. N6 10101 e - F0109 N2 «r. all, OVERFLOW 21" N4 LINE N5 ��950 1 w ear � Ni ,8" " 15" p INSTALL NEW 15" N, OVERFLOW F0330 2 4''' MANHOLE Wi ,,,, ❑rm N3 REPLACE 15" N2 WITH 24" "m°.S, J0401 J0410 " m,l zi N0301 N7 v � D0420 e B220 w3 _ D0512 S O" P: ¢ WPM - MnM se,u. C0502 - o _ tE11 st. A06C ' roa e s 21" - e 15" _ D0508 U.S. 191 a . `"" w.cwi a °a s 24" 12 S C0505 "'••st' 513 8212 J0501 12., as F0663 § C0507 dg r°". ?s 12" 10" 10601 s ""e somas st Mont a 21" s u' 261 1E,0 n,yy.er•". �—I B213 " ° ! 2 L�J 8214 831 8" r S5 S11 21" B33 a 6523 S10 r State w9 1 1E9 8215 15" R University �i' x 1 s g S9 : eY b9 �e 1E23 - 8 B217 8" w N t ❑v 21" 8, s al- S14 B32 "hm s S8 27" 8 1 EB 24° w=„c"" nawoar�o " = ,E22 ,o 8218 828 5 w � 21" S5 10° 5 m o a 10" 15" & S11 �� m 1E2 w.a. S4 c 24" ,°ugh pzt S7 6522 "« anion c i n ,.," 6Si6 658 w 8219 8" 827 t2" t5" 56 15" S1 tE20 ro tE6 1E1 B25 S3 6521 , 77 6S5 8 6S7 cyan eon ea A c 5" 12" S. DRAINAGE AREAS 65,9 S2 6S6 Si 15" 12" Si ZONE 1 ssa eza sszo 6514 s ZONE 2 12" 12" 15 8" ZONE 3 10" ZONE 4 S6 6Si3 B23 653 Q Q ZONE 5 ,o" p LLI 12" LV 12" Q LUNL 6 BI S2 S' ZONE 7 Z Z Z6Si2 6S2 Z ZONE 8 Q az2 ss16 Q to" " 0" W o 6s1, W LEGEND } 8" s6 to" — FUTURE IMPROVEMENTS N kRd � ss1 Bz1 ssn N n:\data\06\M229124\sys—c2c.dwg (—PLATE 5.3-1 BOZEMAN WASTEWATER FACILITY PLAN DRAINAGE AREAS AND FUTURE IMPROVEMENTS WITHIN PLANN114G AREA I�ENGINEERING� 6M229.124 JULY 1998 00