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Home My WebLink About5 Stormwater, Water, Sewer Report Little Spanish Preschool - 130 Flanders Mill Rd Sewer, Water, Storm Report for Site Plan Application Prepared by 714 Stoneridge Drive, Suite #3 Bozeman, MT 59718 406.586.5599 1 Little Spanish Preschool - 130 Flanders Mill Rd Sewer, Water, Storm Report for Site Plan Application Introduction This summary report outlines the impact of sewer, water, and stormwater by the proposed Little Spanish Preschool Site Plan at 130 Flanders Mill Rd. The site is located in R3 zoning, and the existing building will have dual usage: upstairs to remain residential plus a group home daycare, and the lower level to be converted into a commercial daycare facility. Although the upper and lower level daycares have different classifications, they are treated the same for sewer and water calculations. Sewer Proposed is a 4” deep sanitary sewer service line that will flow from the building into the existing 18” sanitary sewer main in Flanders Mill. Based on the calculations shown below in Table 1, the approximate flow rate (gpd) of the site is 1,458 gpd, with a peak hour flow of 3,234 gpd. Table 1: Sewer CalculaƟons Residential* R3 Zoning 2.11 persons/dwelling 89 gallons/capita/day 2.11 persons/dwelling x 89 gallons/capita/day = 188 gpd Daycare** Children 25 gpd/unit 46 children x 25 gpd/child = 1,150 gpd Employees 15 gpd/unit 8 employees x 15 gpd/employee = 120 gpd Total:1,458 gpd Peak Flow: 3,234 gpd *The data used for this estimate is based on the average flow rate of 2.11 persons/dwelling and 89 gallons/capita/day. **The data for the daycare portion of the site is taken from Table 3.1-1 MDEQ Circular 4 for Daycares. The peaking factor is calculated as: 𝑷𝒆𝒂𝒌𝒊𝒏𝒈 𝒇𝒂𝒄𝒕𝒐𝒓=𝟏𝟖+𝑷𝟎.𝟓 𝟒+𝑷𝟎.𝟓=𝟏𝟖+𝟓𝟔𝟎.𝟓 𝟒+𝟓𝟔𝟎.𝟓=𝟐.𝟐𝟐 Peak Flow = 2.22 x 1,458 gpd = 3,234 gpd In order to tie into the City sewer system, the on-site wastewater system must be abandoned, which includes cutting and capping the drainfield line and either crushing, filling, or removing the septic tank. The tank will likely be completely removed so the new water service line can be installed closer to the house. Currently a grinder pump sends the lower level plumbing sewage to the upper level, where it then flows out of the building into the existing septic system and drainfield. This pump has failed numerous times and so it is the Client’s wish to excavate and 2 remove the sump and pump, which will allow for gravity feed of the lower level into the main line that then drains to the City sewer main. Water The water service line is a proposed 2” Type K copper service that will connect to the water main in Sunstone Street. This service will be installed around the building to the south where it will connect to the existing water infrastructure. The existing well connection to the building shall be removed and only used for irrigation. The water service line and meter are proposed to be 2” based on the City of Bozeman’s commercial and residential water service calculation worksheets (included as Appendix). The approximate length of the water service. Similar to the sewer calculations, water usage is separated between the residential portion of the building and the daycares. Although the upper and lower portion daycares have separate classifications (group home daycare and commercial daycare), their water usage will be lumped together and calculated using the flow rates used for sewer from Table 3.1-1 MDEQ Circular 4. Table 2: Water CalculaƟons Residential* Residence 2.11 persons/dwelling 170 gpd 2.11 persons/dwelling x 170 gpd = 359 gpd Daycare** Children 25 gpd/unit 46 children x 25 gpd/child = 1,150 gpd Employees 15 gpd/unit 8 employees x 15 gpd/employee = 120 gpd Total: 1,629 gpd Maximum (2.3:1): 3,747 gpd; Maximum (3:1): 4,887 gpd *The data used for this estimate is based on the average flow rate of 2.11 persons/dwelling and 170 gpd. **The data for the daycare portion of the site is taken from Table 3.1-1 MDEQ Circular 4 for Daycares. Stormwater Currently this site has minimal impervious areas that include only the building and the driveway. Much of the existing driveway will remain as is, with small portions of expansion to allow for more parking and improved grading for ADA compliance. This project increases impervious area by 980 sf. Pre- and post- flows were calculated for the 10-yr, 2-hr storm using the MDEQ’s Simplified Stormwater Plan. The site is currently graded to send runoff from a portion of the building’s roof and driveway into an infiltration/retention basin between the driveway and Flanders Mill Rd. As much of the existing driveway will remain and portions of it will be expanded and re-graded, the majority of runoff will still flow towards the location of the existing retention facility. This facility is to be expanded to allow more runoff capture. Although this existing facility is within utility easements, there is sufficient space between existing utilities to allow for the expansion of the retention basin. The basin area will be approximately 296 sf, graded inwards at a 4:1, with a depth of approximately 0.75 foot, for an approximate volume of 124 cf. The total impervious area that is 3 directed towards the pond is 3,927 sf for a flow of 117 cf (based on the 10-yr, 2-hr storm per the City of Bozeman Standards and Specifications for residential sites). Therefore, this pond can completely capture runoff for the 10-yr, 2-hr storm. The remainder of runoff from the impervious roof and new pathways are directed towards the large grass yard that surrounds the building, which will capture and infiltrate the majority of the runoff. The majority of the rain that lands on grassed landscape area surrounding the house, which has a C-value of 0.92, will be retained and infiltrated on site. With the expanded pond and grassed landscaping to remain, this site will retain at least half of runoff originating from on site. Appendix: x MDEQ Simplified Stormwater Plan for calculating pre- and post- flows x CoB Residential Water Service Calculation Worksheet x CoB Commercial Water Service Calculation Worksheet Sudivision Name EQ# County 0.9 Location 130 Flanders Mill 0.8 Lot/Area No.0.1 Max. Slope on Lot %OK 0.2 Impervious Surfaces % OK Q=C*i*A Will Alter Off-site Pass-Through?STOP, Sumbit a DEQ-8 Plan 10-year, 2-hour, i 0.4 inches/hr Total Area/Lot Size acres = 47371 ft2 Paved/House Area 0.14 acres 6,287 ft2 V=188.61 ft3 Gravel Area 0.00 acres - ft2 V=0 ft3 Lawn/Landscaping 0.94 acres 41,084 ft2 V=136.95 ft3 Unimproved Area 0 acres 0 ft2 V=0 ft3 Total 1.09 acres 47371 ft2 VTotal=325.56 ft3 Paved/House Area 0.17 acres 7,370 ft2 V=221.1 ft3 Gravel Area 0.00 acres ft2 V=0 ft3 Lawn/Landscaping 0.92 acres 40,001 ft2 V=133.34 ft3 Unimproved Area 0.00 acres 0 ft2 V=0 ft3 Total 1.09 acres 47371 ft2 VTotal=354.44 ft3 ΔV=28.88 ft3 = input field 10-year, 2-hour i (volume) Appendix F: Simplified Storm Drainage Plan 10-year, 2-hour i (volume) Rational Method Co-Efficients (C) Paved/hard surfaces Gravel surfaces Lawn/landscaping Unimproved areas Pre-Development Characteristics Post-Development Characteristics Increase in Runoff Volume (Minimum Retention Pond Size) Little Spanish Preschool Residential (2018 IRC) for Alteration and Additions City of Bozeman Water Service Calculation Worksheet Project Address: ___________________________________ Property Owner: ________________________________ General Contractor: _______________________________________________________________________________ Permit Number: _______________ Proposed Water Meter Size: ______________ UPC Table 610.3 Standard Design Water Supply Fixture Units Appliances and Fixtures Units # of EXISTING Fixtures NEW Fixtures Total Bathtub or combo tub/shower (1/2” fill valve) 4.0 X ________ +/- ________ = ________ Bath Tub (3/4” fill valve) 10.0 X ________ +/- ________ = ________ Shower (per head) 2.0 X ________ +/- ________ = ________ Clothes washer 4.0 X ________ +/- ________ = ________ Dishwasher 1.5 X ________ +/- ________ = ________ Hose Bibb 2.5 X ________ +/- ________ = ________ Additional Hose Bibb (each) 1.0 X _______ +/- ________ = ________ Lavatory Sink 1.0 X ________ +/- ________ = ________ Kitchen Sink 1.5 X ________ +/- ________ = ________ Laundry Sink 1.5 X ________ +/- ________ = ________ Water closet [toilet] (1.6 GPF) 2.5 X ________ +/- ________ = ________ Bidet 1.0 X ________ +/- ________ = ________ Urinal (flushometer valve) Table Values* ________ +/- ________ = ________ Total Number of Fixture Units ________ Fixture Unit Tables for Determining Water Pipe & Meter Size Pressure Range – 46 - 60 PSI Circle the length in feet to the farthest fixture & applicable service, meter & branch sizes below based on the total number of fixture units detailed above. Maximum Allowable Length in feet Meter & Supply & 60’ 80’ 100’ 150’ 200’ Service Branches ¾” ¾” 20 19 17 14 11 ¾” 1” 39 36 33 28 23 1” 1” 39 39 36 30 25 ¾” 1¼” 39 39 39 39 39 1” 1¼” 78 76 67 52 44 1½” 1¼” 78 78 78 66 52 1” 1½”/2” 85 85 85 85 85 1½” 1½” 151 151 151 128 105 2” 1½” 151 151 151 150 117 1½” 2” 370 340 318 272 240 2” 2” 370 370 370 368 318 If count is over 370 fixtures, water demand does not meet table 6.10.4 and must be engineered by a registered Montana mechanical engineers design, signed and stamped 04.29.20 130 Flanders Mill Rd, Bozeman, MT 59715 Little Spanish Preschool - Vivianna Helvik n/a 0 n/a 0 1 0 1 0 1 0 1 0 1 0 2 0 1 0 1 0 2 0 0 0 0 0 0 0 4 10 2 4 1.5 2 1.5 1.5 5 0 0 31.5 2.5 ; ; 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 ________ )LUVWLGHQWLI\WKHOHQJWKLQIHHWWRWKHIDUWKHVWIL[WXUHDQGDSSOLFDEOHVHUYLFH.7KHQFURVVUHIHUHQFHWKHQXPEHURI IL[WXUHVEDVHGRQWKH7RWDO1XPEHURI)L[WXUH8QLWVDERYHWRGHWHUPLQHWKHDSSURSULDWH0HWHU 6HUYLFHDQG 6XSSO\ %UDQFKVL]H. 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