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HomeMy WebLinkAbout008 Water Sewer & Storm Design ReportInfrastructure Design Report (Water, Sanitary Sewer & Storm Sewer) TRS Management Dance Studio Lot 4, Block 2, Glen Lake Commerce Subdivision Located in the SW 1/4 of Section 31, T. 1S., R. 6E., P.M.M. City of Bozeman, Gallatin County, Montana Prepared By: May 2025 SANITARY SEWER Sanitary sewer service for the project will be provided by extending the existing 4” service stub that was provided to Lot 4 with the original subdivision infrastructure. The TRS Studio project proposes one new structure to contain a 2,075 square foot dance studio. The estimated average daily sewer flow for the proposed residential portion of the TRS Studio is calculated using typical wastewater flows from the City of Bozeman Design Standards. Average daily flows from the dance studio were estimated based on number of employees and average daily patrons. Estimated Average Daily Sewer Flow from TRS Studios: Dance Studio Flows 2 employees @ 13 gallons/day/employee = 26 gallons/day 30 customers/day @ 3 gallons/day/customer = 90 gallons/day Infiltration Assumed Infiltration = 150 gallons/day/acre Lot Area = 0.173 Acres Total Infiltration = 25.95 gallons/day Total Average Daily Wastewater Flow = 116.00 gallons/day (0.0002 cfs) Peaking Factor = (P = Population in thousands) Peaking Factor = (.) (.) = 4.35 Maximum Daily Flow Max Daily Flow = (Avg Daily Flow x Peaking Factor) + Infiltration = (116 gpd x 4.35) + 26 gpd Max Daily Flow = 530.55 gallons/day (0.0008 cfs) WATER SYSTEM Water service for the project will be provided by extending the existing 1-inch water service line provided to the lot with the original subdivision infrastructure. Attached in Appendix A is a copy of the City of Bozeman Water Service Calculation Worksheet showing that the 3/4-inch meter and 1” service are adequately sized to supply the proposed structure. Also, attached in Appendix A is the Water and Sewer Design Report prepared for Glen Lake Commerce Subdivision. Estimated Average Daily Water Flow from TRS Studios: Dance Studio Flows 2 employees @ 15 gallons/day/employee = 30 gallons/day 30 customers/day @ 5 gallons/day/customer = 150 gallons/day Total Average Daily Water Flow = 180.00 gallons/day (0.13 gpm) Peaking Factors (from City of Bozeman Design Standards, dated July 2017): Maximum Day Demand (Peaking Factor = 2.31) Maximum Hour Demand (Peaking Factor = 3.00) Max & Peak Demands: Maximum Day Demand = 180.00 gpd x 2.31 = 415.80 gpd (0.29 gpm) Peak Hour Demand = 180.00 gpd x 3.00 = 540.00 gpd (0.38 gpm) A detailed water system design report was completed with the infrastructure design for Glen Lake Subdivision to ensure that sufficient water pressure is available (20 psi min.) within the system during a fire event (hydrants flowing @ 1,500 gpm). Static pressures within the water system were measured at 140 psi. Residual pressures were measured at 128 psi while discharging 1,695 gpm from an adjacent fire hydrant. These numbers signify that the existing water system is robust with sufficient pressure and flow capacity. STORM WATER MANAGEMENT Storm water runoff from the full development of Lot 4 was accounted for in the sizing of the Glen Lake Commerce Subdivision storm water infrastructure. The storm water infrastructure installed with the subdivision includes roadway asphalt, curb and gutter, French drain retention, and one underground storm water retention chamber system at the northern edge of the subdivision. Attached in Appendix B is the Storm Water Design Report prepared for Glen Lake Commerce Subdivision. The project site is located within Drainage Basin A. The peak flow calculations for Basin A indicate a composite C coefficient of 0.65 was assumed for the post development runoff coefficient for the site. The proposed site development includes a higher impervious area than that which was assumed with the original Glen Lake infrastructure design report. The proposed development also includes expansion of the proposed parking area onto the neighboring property that was not included within the Glen Lake Subdivision storm water drainage area. This expansion is allowed due to a long-term lease agreement that has been established with the neighboring property owner. The proposed development of Lot 4, and adjacent lease area are divided into 2 drainage areas. The following are the calculations for these 2 drainage areas. Drainage Area # 1 Roof Area (C=0.85) = 2,280 sq ft Landscaping (C=0.20) = 650 sq ft The Composite C coefficient for the proposed developed area is: C = (0.85(2,280) + 0.20(650)) / 2,930 C = 0.71 To avoid unplanned impacts to the existing subdivision storm water infrastructure, we are proposing to construct an underground retention area (French drain) to retain the storm water from Drainage Area #1. This area is identified on the “Drainage Area Exhibit” attached within Appendix C. Attached in Appendix C is a “Storm Water Design Calculations” spreadsheet comparing the 10-year storm water volumes for the assumed site runoff (C=0.65) and the proposed site runoff for Drainage Area #1 (C=0.71). The calculations show that a minimum on- site retention volume of 12 cubic feet is required to limit the off-site flows to the original projection. The proposed underground storm water retention system will provide a volume of 141 cubic feet which is more than adequate to handle the minimum of 12 cubic feet required for the project and the calculated 140 cubic feet required to handle all of Drainage Area #1. Although Drainage Area #1 is less than 1-acre and this standard is not required to be met, we will also check that the proposed underground storm water retention system is sized to capture the runoff generated from the first 0.50 inches of rainfall from a 24-hour storm. A half inch of rain falling on Drainage Area #1 (2,930 square feet) with a runoff coefficient of 0.71 equates to a total rain volume of 86 cubic feet of water. The 141 cubic feet of storage available within the proposed underground storm water retention structure is more than adequate to capture this volume. Drainage Area # 2 Concrete/Asphalt Area (C=0.90) = 5,289 sq ft Landscaping (C=0.20) = 1,420 sq ft The Composite C coefficient for the proposed developed area is: C = 0.90(5,289) + 0.20(1,420)) / 6,708 C = 0.75 To avoid unplanned impacts to the existing subdivision storm water infrastructure, we are proposing to construct an underground retention area (SC-800 Stormtech Chambers) to retain the storm water from Drainage Area #2. This area is identified on the “Drainage Area Exhibit” attached within Appendix C. Attached in Appendix C is a “Storm Water Design Calculations” spreadsheet comparing the 10-year storm water volumes for the assumed site runoff (C=0.65) and the proposed site runoff for Drainage Area #2 (C=0.75). The calculations show that a minimum on- site retention volume of 169 cubic feet is required to limit the off-site flows to the original projection. The proposed underground storm water retention system will provide a volume of 355 cubic feet which is more than adequate to handle the minimum of 169 cubic feet required for the project and the calculated 342 cubic feet required to handle all of Drainage Area #2. Although Drainage Area #2 is less than 1-acre and this standard is not required to be met, we will also check that the proposed underground storm water retention system is sized to capture the runoff generated from the first 0.50 inches of rainfall from a 24-hour storm. A half inch of rain falling on Drainage Area #2 (6,708 square feet) with a runoff coefficient of 0.75 equates to a total rain volume of 210 cubic feet of water. The 355 cubic feet of storage available within the proposed underground storm water retention structure is more than adequate to capture this volume. The proposed on-site storm water facilities are to be maintained by the Lot 4 owners. Attached in Appendix C is a copy of the “Storm Water Maintenance Plan” outlining the owners maintenance responsibilities for the on-site storm water conveyance and retention facilities. The existing off-site storm water conveyance and retention facilities are to continue to be maintained by the Glen Lake Commerce Subdivision property owner’s association. The owner’s association maintenance responsibilities are spelled out in the subdivision covenants and homeowners association documents. Appendix A • City of Bozeman Water Service Calculation Worksheets • Glen Lake Commerce Subdivision Water & Sewer Design Report 2.5 X X ¾” 20 19 17 14 11 ¾” 39 36 33 28 23 1” 1” 39 39 36 30 25 ¾” 1¼” 39 39 39 39 39 1” 78 76 67 52 44 1½” 1¼” 78 78 78 66 52 1” 1½”/2” 85 85 85 85 85 1½” 151 151 151 128 105 2” 151 151 151 150 117 1½” 370 340 318 272 240 2” 1½” 370 370 370 368 318 1” ¾” 2” 2” 1½” 1¼” UPC Table 610.3 Standard Design Water Supply Fixture Units Fixture Units # of Fixtures Total 4.0 X ________ = ________ 10.0 X ________ = ________ 2.0 X ________ = ________ 4.0 X ________ = ________ 1.5 X ________ = ________ 2.5 X ________ = ________ 1.0 X ________ = ________ 0.5 X ________ = ________ 3.0 X ________ = ________ 1.0 X ________ = ________ 1.5 X ________ = ________ 1.5 X ________ = ________ Appliances and Fixtures Bathtub/Combination Tub/Shower Soaker Tub Shower (per head) Clothes washer Dishwasher Hose Bibb Additional Hose Bibb (each) Drinking Fountain Service / Mop Basin Lavatory Sink Kitchen Sink Laundry Sink Water closet (1.6 GPF) 2.5 X ________ = ________ Water closet (1.6 GPF – Flushometer tank) X ________ = ________ = ________ Water closet (flushometer valve) Urinal (flushometer valve) = ________ Table Values ________ Table Values ________ Total Number of Fixture Units ________ First identify the length in feet to the farthest fixture and applicable service. Then, cross reference the number of fixtures, based on the Total Number of Fixture Units above to determine the appropriate Meter & Service, and Supply & Branch size. UPC Table 610.4 Maximum Allowable Length in feet - 46-60 PSI Meter & Supply & 150’ 200’ Service Branches If count is over 370 fixtures, water demand does not meet table 610.4 submitted by a registered Montana mechanical engineers design, signed and stamped. March 2023 2021 UPC (Comm/Res) City of Bozeman Water Service Calculation Worksheet Project Address: ___________________________________ Property Owner: ______________________________ General Contractor: _______________________________________________________________________________ Permit Number: _______________ Proposed Water Meter Size: _______________ *As a substitute for this form you can utilize Appendix M in Uniform Plumbing Code. The calculator results, as well as all of the fixtures that will be used on this project will need to be submitted in lieu of this form. Sec . 610 .1 Sec. 6 10.1 100’ 80’ 60’ *Appendix M requires the property to be identified as a water conservation Building. Appendix B • Glen Lake Commerce Subdivision Storm Water Design Report Appendix C • Storm Water Design Calculations • Storm Water Drainage Area Map • Storm Water Maintenance Plan DA # 1 1. Calculate Area and Weighted C Factor 2. Calculate Required Retention Volume Contributing Area C Area (ft2)C * Area Q = CIA Aspahlt & Concrete 0.90 0 0 V=7200Q Roof 0.85 2,280 1,938 Gravel 0.80 - - C = Weighted C Factor 0.71 Landscape 0.20 650 130 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) Totals 2,930 2,068 A = Area (acres) 0.067 Q = runoff (cfs) 0.0195 A = Area (acres) 0.067 C = Weighted C Factor 0.71 V = REQUIRED VOL (ft3)140 V = PRO VOL (ft3)141 V = REQUIRED VOL (ft3)86 1st 0.5" of rainfall from a 24hr storm FRENCH DRAIN RETENTION VOLUME CALCULATIONS INPUTS: DIAMERTER OF LATERALS (IN) 12 1ST LATERAL LENGTH (FT) 10.00 2ND LATERAL LENGTH (FT) 0.00 3RD LATERAL LENGTH (FT) 0.00 TRENCH WIDTH (FT) 4.00 INTERNAL SUMP DIAMETER (FT) 2.00 EXTERNAL SUMP DIAMETER (FT) 2.50 INTERNAL SUMP DEPTH (FT) 7.25 BOT. OF ROCK -> CL LATERALS (FT)6.33 OUTPUTS: DIA/WIDTH (FT) LENGTH (FT) DEPTH (FT) VOL (CF)VOL30%VOID_SPACE INTERNAL SUMP STORAGE 2.00 N/A 7.25 23 N/A 1ST LATERAL STORAGE 1.00 10.00 N/A 8 N/A 2ND LATERAL STORAGE 1.00 0.00 N/A 0 N/A 3RD LATERAL STORAGE 1.00 0.00 N/A 0 N/A SUMP TRENCH VOID SPACE 2.50 N/A 7.33 81 24 1ST PIPE TRENCH VOID SPACE 4.00 10.00 7.33 285 86 2ND PIPE TRENCH VOID SPACE 4.00 0.00 7.33 0 0 3RD PIPE TRENCH VOID SPACE 4.00 0.00 7.33 0 0 TOTAL STORM WATER RETENTION (CF): 141 Retention Provided by Underlying Subdivision (C=0.65) For a 10-year storm event: Area = 2,930 ft2 Q10 =0.0178 cfs Vrqd = 128 ft3 On Site Retention Required 140 ft3 -128 ft3 12 ft3 DA # 2 1. Calculate Area and Weighted C Factor 2. Calculate Required Retention Volume Contributing Area C Area (ft2)C * Area Q = CIA Aspahlt & Concrete 0.90 5,289 4,760 V=7200Q Roof 0.85 - - Gravel 0.80 - - C = Weighted C Factor 0.75 Landscape 0.20 1,420 284 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) Totals 6,708 5,044 A = Area (acres) 0.154 Q = runoff (cfs) 0.0475 A = Area (acres) 0.154 C = Weighted C Factor 0.75 V = REQUIRED VOL (ft3)342 Min. # Chambers V = PRO VOL (ft3)355 SC-800 4 V = REQUIRED VOL (ft3)210 1st 0.5" of rainfall from a 24hr storm Retention Provided by Underlying Subdivision (C=0.65) For a 10-year storm event: Area = 3,936 ft2 Q10 =0.0240 cfs Vrqd = 172 ft3 On Site Retention Required 342 ft3 -172 ft3 169 ft3 STORM WATER MAINTENANCE PLAN TRS Management Dance Studio City of Bozeman, Montana PROPERTY OWNER'S RESPONSIBILITIES FOR ROUTINE INSPECTION AND MAINTENANCE: 1. Routine Maintenance Activities (1-3 month interval) • Remove trash, leaves, grass clippings and debris from inlets, swales & retention structures. • Remove any obstruction to flow • Establish a chemical free zone in and around the basins • Inspect for uniform ponding, and that water disappears within three days of rain events • Inspect inlets, piping, swales & curbs for sediment buildup and/or evidence of erosion • Check for eroded or channelized areas. Repair immediately, find the cause and take action to prevent further erosion. • Inspect structures and retention structures for oil sheens • Inspect swales for undesirable vegetation or noxious weeds 2. Annual Maintenance Activities (Annually) • Re-establish vegetation on eroded and barren areas • Remove excess sediment build-up in inlets, piping, swales and retention structures. • Update maintenance plan and inspection log • Clear and remove accumulated winter sand in parking lots and structures • Underground retention vaults shall be thoroughly inspected o If sediment is at, or above, 3” chambers shall be cleaned using the jetvac process. o A fixed culvert cleaning nozzle with rear facing spread of 45” or more is preferred. o Apply multiple passes of jetvac until backflush water is clean. 3. Long Term Maintenance Activities (5-10 year interval) • Dredge basin if sediment buildup is greater than 6” • Re-establish vegetation • Repair or replace damaged storm water structures and/or piping • Re-grade swales to ensure proper drainage. 4. Maintenance of the site, drainage paths and storm structures shall be the responsibility of the property owner. Snow Storage: Snow is to be stored in a manner such that snow banks do not cover or block curb cuts, curb chases, stormwater inlets, manholes, chambers, or swales. Sediment Accumulation: In most cases, sediment from a retention pond does not contain toxins at levels posing a hazardous concern. However, sediments should be tested for toxicants in compliance with current disposal requirements and if land uses in the drainage area include commercial or industrial zones, or if visual or olfactory indications of pollution are noticed. Sediments containing high levels of pollutants should be disposed of in accordance with applicable regulations and the potential sources of contamination should be investigated and contamination practices terminated. Isolator®Row O&M Manual StormTech®Chamber System for Stormwater Management Save Valuable Land and Protect Water Resources Detention • Retention • Water Quality A division of 1.1 INTRODUCTION An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a patented technique to inexpensively enhance Total Suspended Solids (TSS) removal and provide easy access for inspection and maintenance. 1.2 THE ISOLATOR ROW The Isolator Row is a row of StormTech chambers, either SC-310, SC-310-3, SC-740, DC-780, MC-3500 or MC- 4500 models, that is surrounded with filter fabric and con- nected to a closely located manhole for easy access.The fabric-wrapped chambers pro vide for settling and filtra- tion of sediment as storm water rises in the Isolator Row and ultimately passes through the filter fabric. The open bottom chambers and perforated sidewalls (SC-310, SC- 310-3 and SC-740 models) allow storm water to flow both vertically and horizon tally out of the chambers. Sediments are cap tured in the Isolator Row protecting the storage areas of the adjacent stone and chambers from sediment accumulation. Two different fabrics are used for the Isolator Row. A woven geotextile fabric is placed between the stone and the Isolator Row chambers. The tough geo textile provides a media for storm water filtration and provides a durable surface for maintenance operations. It is also designed to prevent scour of the underlying stone and remain intact during high pressure jetting. A non-woven fabric is placed over the chambers to provide a filter media for flows passing through the perforations in the sidewall of the chamber. The non-woven fabric is not required over the DC-780, MC-3500 or MC-4500 models as these chambers do not have perforated side walls. 2 Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 1.0 The Isolator®Row The Isolator Row is typically designed to capture the “first flush” and offers the versatility to be sized on a vol- ume basis or flow rate basis. An upstream manhole not only provides access to the Isolator Row but typically includes a high flow weir such that storm water flowrates or volumes that exceed the capacity of the Isolator Row overtop the over flow weir and discharge through a manifold to the other chambers. The Isolator Row may also be part of a treatment train. By treating storm water prior to entry into the chamber system, the service life can be extended and pollutants such as hydrocarbons can be captured. Pre-treatment best management practices can be as simple as deep sump catch basins, oil-water separators or can be inno- vative storm water treatment devices. The design of the treatment train and selection of pretreatment devices by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, the Isolator Row is recommended by StormTech as an effective means to minimize maintenance requirements and maintenance costs. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row. ECCENTRIC HEADER MANHOLE WITH OVERFLOW WEIR STORMTECH ISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS StormTech Isolator Row with Overflow Spillway (not to scale) Looking down the Isolator Row from the manhole opening, woven geotextile is shown between the chamber and stone base. 2.0 Isolator Row Inspection/Maintenance Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 3 Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water noz- zle to propel itself down the Isolator Row while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the man- hole for vacuuming. Most sewer and pipe maintenance companies have vacuum/JetVac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for cul- verts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. Most JetVac reels have 400 feet of hose allow- ing maintenance of an Isolator Row up to 50 chambers long. The JetVac process shall only be performed on StormTech Isolator Rows that have AASHTO class 1 woven geotextile (as specified by StormTech) over their angular base stone. 2.1 INSPECTION The frequency of Inspection and Maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial, residential), anticipated pollutant load, per- cent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspec- tions. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For sub sequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to deter- mine the depth of sediment. When the average depth of sediment exceeds 3 inches throughout the length of the Isolator Row, clean-out should be performed. 2.2 MAINTENANCE The Isolator Row was designed to reduce the cost of periodic maintenance. By “isolating” sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for main- tenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entries. StormTech Isolator Row (not to scale) Examples of culvert cleaning nozzles appropriate for Isolator Row maintenance. (These are not StormTech products.) NOTE:NON-WOVEN FABRIC IS ONLY REQUIRED OVER THE INLET PIPE CONNECTION INTO THE END CAP FOR DC-780, MC-3500 AND MC-4500 CHAMBER MODELS AND IS NOT REQUIRED OVER THE ENTIRE ISOLATOR ROW. Step 1)Inspect Isolator Row for sediment A) Inspection ports (if present) i.Remove lid from floor box frame ii.Remove cap from inspection riser iii.Using a flashlight and stadia rod, measure depth of sediment and record results on maintenance log. iv.If sediment is at, or above, 3 inch depth proceed to Step 2. If not proceed to step 3. B) All Isolator Rows i.Remove cover from manhole at upstream end of Isolator Row ii.Using a flashlight, inspect down Isolator Row through outlet pipe 1.Mirrors on poles or cameras may be used to avoid a confined space entry 2.Follow OSHA regulations for confined space entry if entering manhole iii.If sediment is at or above the lower row of sidewall holes (approximately 3 inches) proceed to Step 2. If not proceed to Step 3. Step 2)Clean out Isolator Row using the JetVac process A) A fixed culvert cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required Step 3) Replace all caps, lids and covers, record observations and actions Step 4)Inspect & clean catch basins and manholes upstream of the StormTech system ADS “Terms and Conditions of Sale” are available on the ADS website, www.ads-pipe.com Advanced Drainage Systems, the ADS logo, and the green stripe are registered trademarks of Advanced Drainage Systems. Stormtech®and the Isolator®Row are registered trademarks of StormTech, Inc. Green Building Council Member logo is a registered trademark of the U.S. Green Building Council. © 2013 Advanced Drainage Systems, Inc. SO90809 02/13 3.0 Isolator Row Step By Step Maintenance Procedures 4 21) B)1) A) StormTech Isolator Row (not to scale) Stadia Rod Readings Fixed point Fixed point Sediment Date to chamber to top of Depth Observations/Actions Inspector bottom (1)sediment (2)(1) - (2) 3/15/01 6.3 ft.none New installation. Fixed point is Cl frame at grade djm 9/24/01 6.2 0.1 ft.Some grit felt sm 6/20/03 5.8 0.5 ft.Mucky feel, debris visible in manhole and in rv Isolator row, maintenance due 7/7/03 6.3 ft.0 System jetted and vacuumed djm Sample Maintenance Log 70 Inwood Road, Suite 3 Rocky Hill Connecticut 06067 860.529.8188 888.892.2694 fax 866.328.8401 www.stormtech.com Detention • Retention • Water Quality A division of