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HomeMy WebLinkAbout587-04 Stormwater Design Report - Combined (1) 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 1 October 2025 TABLE OF CONTENTS Introduction .................................................................................................................................... 2 Hydrology and Hydrogeology .......................................................................................................... 2 Existing Stormwater Drainage Conditions ...................................................................................... 5 Proposed Stormwater Drainage System .......................................................................................... 6 Evaluation of Major Storm Flood Risks ............................................................................................ 7 APPENDIX Appendix A ...................................................................................................... Drainage Basin Maps Appendix B ............................................................................................. Drainage Basin Calculations Appendix C ................................................................................................ Groundwater Monitoring Appendix D .............................................................................................................. NRCS Soil Survey Appendix E .................................................... Stormwater Facilities Operation & Maintenance Plan 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 2 October 2025 INTRODUCTION The purpose of this report is to detail the stormwater management design for proposed site improvements for Lots 1-4 of Block 34, Capitol Hill Addition. The lot is located in Section 13, Township 02 South, Range 5 East, City of Bozeman, Gallatin County, Montana. The property is located on the Northeast corner of Garfield and South 4th Ave. The 0.386-acre site is currently zoned R-2, and consists of a parking lot, stormwater pond, and surrounding landscaping. It is fronted by public streets on the north and east sides, while the south and west property lines boarder R-2 zoned residential lots. Location Exhibit The proposed development on the property includes a 4,600 square foot residential structure, a parking lot, sidewalk, and landscaping that will be installed around the structure. Stormwater generated from the impervious improvements from this development will be stored on site. HYDROLOGY AND HYDROGEOLOGY STORMWATER DESIGN CRITERIA In accordance with the City of Bozeman Design and Construction Standards (COB DCS), stormwater runoff for the proposed project was analyzed for both the minor and major storm events. City standards require that stormwater conveyance and treatment facilities be sized to convey and store runoff from the minor storm event. The standards also require that the major storm be analyzed to evaluate the risk of flooding. The minor storm that was analyzed was the 10-year storm, while the major storm was analyzed as the 100-year, 24-hour storm event. SUBJECT PROPERTY 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 3 October 2025 For this particular project, the Rational Method was chosen for the runoff calculation method. Since the Rational Method was being used, rainfall intensities for both storm events were determined from the following table (Table 6.5.2) from Chapter 6 of the COB DCS. The storm intensities were pulled from Table 6.5.2 and interpolated based off the time of concentration for each subbasin. Conveyance facilities were sized to operate in an open channel flow condition during the minor storm event (10-yr) and to maintain a minimum velocity of 2.5 fps. Time of concentration for each subbasin was calculated per the Section 4.2.2.3 of the HEC manual using the equations listed below. If the total time of concentration for a subbasin was less than 5 minutes, a TOC of 5 minutes was used. Equation 1. (Sheet Flow) tt = Sheet flow travel time (min) n= roughness coefficient L= Flow length (ft) P2= 2-year, 24-hour rainfall depth (inch) S= Slope of Basin, (ft/ft) Ku= Unit conversion constant, 0.42 in CU Equation 2. (Shallow Concentrated Flow) V= Velocity (ft/sec) Ku= Unit conversion constant, 3.28 in CU k= Intercept Coefficient (Table 4.3, FHWA 2002) Sp= Slope, (%) .√ . . 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 4 October 2025 Equation 3. (Open Channel/Pipe Flow) V= Velocity (ft/sec) n= Mannings roughness coefficient R - Hydraulic Radius(ft) S= Slope of Basin, (ft/ft) Runoff coefficients for the various cover types on site were derived from Table 6.6.4 (COB DCS). The rational method was used to compute the runoff volume from each contributing subbasin. This method can be used for storm durations equal to or greater than the time of concentration. Runoff rates for storm durations greater than the time of concentration are less than the runoff rate at the time of concentration because average storm intensities decrease as duration increases. Therefore, this method assumes that the peak runoff flow rate for a given storm event occurs at the time of concentration. The peak flow was determined using the equation below: Equation 4. (Runoff Flow Rate) Where Q = Runoff Rate (cfs) Cf= Correction Factor C = Weighted C Factor I = Intensity (in/hr) A= Area (acres) The rational method uses peak flow rates for a given storm duration to determine volume. The required retention volume is calculated by multiplying the peak runoff by storm duration. However, since the time 1.486 . ! 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 5 October 2025 of concentration for the proposed subbasins in this project are relatively short (5mins), using the time of concentration for storm duration results in small runoff volumes. Therefore, the storm systems for the project were sized based on the 2-hour storm duration for the minor 10-year storm and the 2-hour & 24- hour durations for the major 100-year storm. Retention volume is determined using the following equation for each storm event: Equation 5. (Runoff Volume) Where V = Volume (cf) D= Storm Duration (hr) Q = Flow Rate (cfs) GROUNDWATER Groundwater monitoring of the existing site was performed during the spring of 2025. One perforated PVC pipe was installed as a monitoring well, located in the middle of the existing stormwater pond. The wells were monitored for several months during the spring when high groundwater typically peaks in the city (May – June). The monitoring well was dry throughout the monitoring period so the groundwater elevation was assumed conservatively to be equal the elevation of the bottom of the monitoring well (approx. 4894.0). Groundwater Monitoring Results are attached in Appendix C. There was no geotechnical investigation done on the subject property. The previous site improvements which include the construction of the existing parking lot and stormwater pond were designed and submitted to the city by C&H Engineering & Surveying. A NRCS Soil study for the subject property is attached in Appendix D. There was not substantial soil information on the subject property, however for the purposes of the stormwater design it is assumed the underlying soil profile consists of a section of organic topsoil followed by several feet of inorganic silty clay above a poorly graded native gravel. The report classified the soil type as 305B for surrounding properties. EXISTING STORMWATER DRAINAGE CONDITIONS Overall, the existing site slopes from south to north at 3%. The existing parking lot slopes at approximately 3% to an existing stormwater pond located East of the parking lot. Appendix A includes a pre-development drainage basin map that details the existing drainage patterns and facilities on the subject property. The runoff generated by the existing site was estimated using the rational method outlined in the COB DCS for both the 10-year 2-hour minor and the 100-year 24-hour major storm event. The property was assigned runoff coefficients based on the cover type. The existing site was broken into 2 pre-development drainage basins based on current site conditions. Drainage Basin PRE 1 conveys runoff to existing stormwater facilities on site while the rest of the site (Drainage Basin PRE 2) drains to the ROW for Garfield and South 4th Ave. Calculations for the existing drainage conditions are included in Appendix B. 3600$ 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 6 October 2025 PROPOSED STORMWATER DRAINAGE SYSTEM With the proposed site improvements, a 4,600-sf structure will be constructed with surrounding landscaping and a parking lot. Runoff from the impervious improvements will be conveyed via downspouts, sheet flow, curb and gutter, and pipes to an underground Stormtech storage facility. A portion of the site on the north and east side of the site will sheet flow into the adjacent Garfield & S. 4th Ave. ROW. Runoff from the north side of the structure will be collected via roof gutters, downspouts, and inline drains, then routed via a pipe network to the proposed Stormtech system. Storm Sewer System: The storm sewer network for the proposed private site improvements is comprised of pre-cast concrete curb inlets and manholes, ADS Nyloplast® drain basins and inline drains, and ADS HP storm pipe that conveys runoff to the Stormtech chamber system. Chamber System: The proposed underground infiltration system will be StormTech MC-3500 chamber systems. These systems are plastic arched-shaped chambers with washed rock bedding/backfill that have been sized to provide adequate stormwater retention volume of the minor storm event. After the design storm, runoff within the chamber systems will infiltrate into the ground. The proposed underground system will be set above seasonal high groundwater with the bottom of the system sitting at an elevation of 4896.41’. Based on the Groundwater monitoring seasonal high groundwater was determined to be no higher than 4894.05’ so there is at least 2.36’ of separation between the system and high groundwater. The area underneath the chamber system will be excavated down to native gravels and backfilled with well-draining material to ensure the systems have adequate infiltration. The DEQ infiltration rate for gravel (2.6 inches per hour) from Circular DEQ 8, Appendix C, Table 2 was used for native gravels and applied to the system footprints to ensure that infiltration of the design storm events within 72 hours was possible. Appendix C of Circular DEQ-8 states that the infiltration rates provided can be increased by 50% with the use of sediment reducing pre-treatment facilities. Stormtech chamber systems are designed to divert the initial flow from any storm event to a lined Isolator® Row for pre-treatment and sediment collection prior to release to the rest of the system. This particular system consists of only an isolator row so the 2.6 in/hr infiltration rate was increased by 50% to 3.9 in/hr for the chamber infiltration calculations. This infiltration rate is still believed to be conservative since infiltration tests on native gravel in Bozeman on other projects have produced infiltration rates that are significantly higher than 3.9 in/hr. Drainage Basin Area (acres)Weighted C Time of Concentration (min) QPeak (cfs) 10-yr Q (cfs) 10- yr, 2-hr V (10yr,2hr) V (100yr,24hr)Facility PRE1 0.20 0.72 5.00 0.55 0.06 417 1494 Existing Pond PRE 2 0.19 0.23 5.00 0.17 0.02 128 459 Offsite ROW 0.39 545 1953 Pre Development Drainage Basin Summary 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 7 October 2025 DRAINAGE BASIN SUMMARIES The site was broken in to 2 drainage basins with some sub basins for conveyance analysis. Calculations for the drainage basins and facilities are included in Appendix B. Basin 1 will be collected and conveyed to the Stormtech system and Basin 2 will flow off site at a runoff rate lower than the predevelopment flow rate. A post development drainage basin map is attached in Appendix A. Drainage Basin #1 consists of the majority of the site, including the proposed structure, parking lot and surrounding sidewalk. This basin collects and conveys runoff via sheet flow, cub and gutter and pipes to the storm tech system located in the parking lot. This basin was broken into three subbasins for the purpose of conveyance calcs. DB 1 generates 796 cf of runoff in the 10 yr 2hr storm, and the Stormtech system was oversized to provide 1,117 cf of storage. Drainage Basin #2 is the remainder of the site, mostly landscape areas on the north and east property lines. Runoff from this basin sheet flows to the ROW in Garfield and 4th Ave. DB #2 generates and sends approx. 82 cf of runoff in the 10yr 2hr storm event to the ROW. This is less than the 128 cf of runoff sent to the ROW in the predevelopment conditions. The peak pre-development offsite runoff rate was 0.17 cfs, while in post development conditions DB #2 will produce offsite runoff at a rate of 0.11 cfs. EVALUATION OF MAJOR STORM FLOOD RISKS Major Storm Event As explained previously, the new COB DCS requires runoff control considerations to be made for the major (100-yr, 24-hr) storm event in addition to the 10-year 2-hr storm event. In order to determine the 100-yr runoff volume a rainfall intensity of 0.098 inches/hour was used from Table 6.5.2. Runoff volumes for this storm event were calculated for each drainage basin using spreadsheets and are provided in Appendix B. In the event of a major storm, the Stormtech system will fill up first. Once the chamber hits capacity the parking lot will begin to pond until the ponding overtops the curb inlet in the NE corner of the parking lot. Runoff will then begin to flow offsite into the ROW and be collected by the city’s public storm network. The parking lot was designed so that the building will not be inundated by the major storm event, as the parking lot overflow elevation was set 1 ft below finished floor. Once the runoff flows into the S. 4th Ave. ROW it will follow the curbline north to a valley gutter at the Garfield intersection. From here the runoff Drainage Basin Area (acres)Weighted C Time of Concentration (min) QPeak (cfs) 10-yr Q (cfs) 10- yr, 2-hr V (10yr,2hr) V (100yr,24hr)Facility 1A 0.13 0.90 5.00 0.46 0.05 1B 0.10 0.87 5.32 0.34 0.04 1C 0.05 0.95 5.00 0.18 0.02 1D 0.02 0.95 5.00 0.07 0.01 2 0.09 0.32 5.00 0.11 0.01 82 296 Offsite ROW 0.39 879 2833 Post Development Drainage Basin Summary Stormtech System 1796 2537 587-04 Delta Gamma Site Alteration - Stormwater Design Report Page 8 October 2025 flows east to a series of storm inlets at the Garfield and S. 3rd intersection. Once collected in the public storm network the runoff flows to the system outlet in Mathew Bird creek. As seen in the pre-development drainage basin summary table above, the existing site currently generates a total of 1,953 cf of runoff in the 100-year 24-hour event. Drainage Basin Pre 1 generates 1494 cf of runoff that is flowing to the existing stormwater pond. The existing pond has 705 cf of storage capacity so it is assumed 789 cf of runoff from DB PRE 1 will overflow the pond and flow into the ROW. The existing offsite runoff from Drainage Basin PRE 2 conveys 459 cf to the ROW. The total assumed offsite runoff generated between both predevelopment basins 1,249 cf. Per the post development drainage basin summary table above, the 100-year 24-hour storm event on the site produces 2,833 cf of runoff. In post development conditions DB 1 produces 2,537 cf of runoff while the storm tech system has 1,117 cf of capacity. The parking lot ponding was determined to be minimal (less than 100 cf), therefore it is conservatively assumed 1,420 cf of runoff will overtop the Stormtech system and parking lot. DB 2 generates 296 cf of runoff in addition to the 1,420 cf from DB 1 for a total of 1,716 cf of offsite runoff in post development conditions so, in a major storm event, the site will send 467 cf more runoff to the ROW than in predevelopment conditions. Appendix A Drainage Basin Maps OHP OHP OHP OHP OHP OHP PPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHP OHPOHPOHP OHP OHPOHPOHP OHP OHP OHPOHP OHPOHPOHP OHP OHP OHPOHPOHPOHPOHPPP OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPPP OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP GASGASGASGASGASGASGASGASGASGASGASGASGASGASSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWR SWR SWR SWR SWR SWR SWR SWR OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPWWWW12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''WGAS GASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGAS GAS GAS SWRSWRSWRSWRSWRSWRW V W V SS T E E E GV ST GROUNDWATER MONITORING WELL SPRINKLER CONTROLS WITH POWER WATER METER IN PUMP HOUSE S0° 01' 55"W100.11'N89° 28' 54"E 168.15' S89° 34' 00"W 168.19'N0° 03' 24"E99.86'OSW OH P OH P OH P OH P OH P OH P O H P OH P O H P STORMWATER POND GARFIELD ST FOURTH STEDGE OF ASPHALT LOT 3 4203.61 SQ FT 14' ALLEY4 8 9 9 4905 4904.0 4 9 0 3 . 04902.04901.0 4900 4 8 9 9 . 0 4901.0 4902.0 49 0 4 . 0 4903.0 49 0 2 . 0 49054906.0 LOT 2 4203.61 SQ FT LOT 1 4203.61 SQ FT LOT 4 4203.61 SQ FT LOT 5 LOT 6 6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''WPROJECT NO: DATE: ENGINEER: REVISIONS DATENO.DESC. JG FIGURE 1 10'0 20' 1" = 10'SCALE N LEGEND DRAINAGE BASIN BOUNDARY DRAINAGE BASIN COVER TYPE - PERVIOUS STORM MANHOLE STORM INLET STORM CATCH BASIN STORM POND / SWALE SYMBOL DESCRIPTION ST DRAINAGE BASIN COVER TYPE - IMPERVIOUS DRAINAGE BASIN COVER TYPE - ROOF SHEET OF 21DELTA GAMMA SITE ALTERATIONPRE DEVELOPMENT DRAINAGE BASIN MAPBOZEMAN, MTSITE PLAN SUBMITTALDRAINAGE BASIN 2 DRAINAGE BASIN 1 TIME OF CONCENTRATION OHP OHP OHP OHP OHP OHP PPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHPOHPOHPOHP OHP OHPOHP OHPOHP OHP OHPOHP OHPOHP OHPOHP OHP OHPOHPOHPOHP OHPPP OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPPP OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP GASGASGASGASGASGASGASGASGASGASGASGASGASGASSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWR SWR SWR SWR SWR SWR SWR SWR OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPWWWW12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''WGAS GASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGAS GAS GAS SWRSWRSWRSWRSWRSWRW V W V SS T E E E GV ST OSW OH P OH P OH P OH P OH P OH P OH P OH P O H P WEST GARFIELD ST S FOURTH AVE.LOT 3 4203.61 SQ FT 14' ALLEYLOT 2 4203.61 SQ FT LOT 1 4203.61 SQ FT LOT 4 4203.61 SQ FT LOT 5 LOT 6 6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''WW SS SS SS SS GAS GAS GAS GAS GAS WWWWWWWWST ST ST S T ST ST ST ST ST ST ST ST ST ST ST ST OSW C O STST ST ST ST STSTSTSTSTSTSTSTST ST DB 1C DB 1B DB 1A DB 2 STORMTECTH FACILITY 1 MC-3500 VREQ.10-YR,2-HR= 796 CF VPRO.10-YR,2-HR= 1,117 CF INLINE DRAIN - 1 DRAIN BASIN - 1 INLINE DRAIN - 2 INLINE DRAIN - 3 DRAIN BASIN - 2 ST INLET 2 STMH 1 STMH 2 ST INLET 1 DB 1D Pipe - 1B Pipe - 1D Pipe - 1C Pipe - 1A MAJOR STORM EVENT OVERFLOW PATH PROJECT NO: DATE: ENGINEER: REVISIONS DATENO.DESC. JG FIGURE 2 10'0 20' 1" = 10'SCALE N LEGEND DRAINAGE BASIN BOUNDARY DRAINAGE BASIN COVER TYPE - PERVIOUS STORM MANHOLE STORM INLET STORM CATCH BASIN STORM POND / SWALE SYMBOL DESCRIPTION ST DRAINAGE BASIN COVER TYPE - IMPERVIOUS DRAINAGE BASIN COVER TYPE - ROOF SHEET OF 22DELTA GAMMA SITE ALTERATIONPOST DEVELOPMENT DRAINAGE BASIN MAPBOZEMAN, MTSITE PLAN SUBMITTALDRAINAGE BASIN 1 DRAINAGE BASIN 2 TIME OF CONCENTRATION MAJOR STORM OVERFLOW PATH Appendix B Stormwater Storage Facility Calculations Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious PRE 1 5912 0.14 0.95 0.1289 DB - Roof PRE 1 0 0.00 0.95 0.0000 DB - Pervious PRE 1 2657 0.06 0.20 0.0122 Totals 8,569 0.20 0.1411 Weighted C:0.72 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 95 Sb - Slope of Basin (ft/ft)0.030 Tt - Time of Conc. - Sheet Flow (min.)1.63 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 18 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.02 V - Velocity (ft/sec) 0.29 Tc - Time of Conc. - Shallow Concentrated (min.)1.04 *Channel/Pipe Flow L - Length of Channel (ft) 0 n - Manning's Coefficient 0.011 R - Hydraulic Radius(ft) 0.01 Sc - Slope of Channel (ft/ft)0.008 V - Velocity (ft/sec) 0 Tc - Time of Conc. - Channel/Pipe (min.)0.00 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.72 3.87 0.55 25 1.1 0.79 4.76 0.74 50 1.2 0.86 5.43 0.92 100 1.25 0.90 6.09 1.07 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.20 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.72 Weighted C = Cf*C= 0.72 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.06 Q (cfs) = 0.11 0.017 Req. Runoff Volume (ft3)=417 Req. Runoff Volume (ft3)=775 1,494 Conveyance Calculations PREDEVELOPMENT BASIN 1 Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. 0.90 0.72 0.20 Generated Runoff Volume - 10 year,2 hr 0.20 1.25 0.72 =.(). = = . =1.486 . Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious PRE 2 322 0.01 0.95 0.0070 DB - Roof PRE 2 0 0.00 0.95 0.0000 DB - Pervious PRE 2 7923 0.18 0.20 0.0364 Totals 8,245 0.19 0.0434 Weighted C:0.23 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 24.8 Sb - Slope of Basin (ft/ft)0.500 Tt - Time of Conc. - Sheet Flow (min.)0.18 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 0 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.025 V - Velocity (ft/sec) 0.00 Tc - Time of Conc. - Shallow Concentrated (min.)0.00 *Channel/Pipe Flow L - Length of Channel (ft) 0 n - Manning's Coefficient 0.011 R - Hydraulic Radius(ft) 0.01 Sc - Slope of Channel (ft/ft)0.008 V - Velocity (ft/sec) 0 Tc - Time of Conc. - Channel/Pipe (min.)0.00 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.23 3.87 0.17 25 1.1 0.25 4.76 0.23 50 1.2 0.28 5.43 0.28 100 1.25 0.29 6.09 0.33 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.19 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.23 Weighted C = Cf*C= 0.23 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.02 Q (cfs) = 0.03 0.005 Req. Runoff Volume (ft3)=128 Req. Runoff Volume (ft3)=238 459 0.29 0.23 0.19 Generated Runoff Volume - 10 year,2 hr 0.19 1.25 0.23 Conveyance Calculations PREDEVELOPMENT BASIN 2 Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. = =.(). = . =1.486 . Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac)Runoff Coefficient (C)A (Ac) x C DB - Impervious 1A 3833 0.09 0.95 0.0836 DB - Roof 1A 1497 0.03 0.95 0.0326 DB - Pervious 1A 400 0.01 0.20 0.0018 Totals 5,730 0.13 0.1181 Weighted C:0.90 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 51 Sb - Slope of Basin (ft/ft)0.025 Tt - Time of Conc. - Sheet Flow (min.)1.06 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 36 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.8 V - Velocity (ft/sec) 1.82 Tc - Time of Conc. - Shallow Concentrated (min.)0.33 *Channel/Pipe Flow L - Length of Channel (ft) 21.5 n - Manning's Coefficient 0.02 R - Hydraulic Radius(ft) 0.30 Sc - Slope of Channel (ft/ft)0.02 V - Velocity (ft/sec) 6.3 Tc - Time of Conc. - Channel/Pipe (min.)0.06 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.90 3.87 0.46 25 1.1 0.99 4.76 0.62 50 1.2 1.00 5.43 0.71 100 1.25 1.00 6.09 0.80 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.13 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.90 Weighted C = Cf*C= 0.90 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.05 Q (cfs) = 0.08 0.013 Req. Runoff Volume (ft3)=349 Req. Runoff Volume (ft3)=578 1,114 Pipe Pipe Size (in) Flow Depth - d (in) Slope (ft/ft) Manning's n Provided Velocity (fps)Provided Capacity (cfs)Required Capacity (cfs) PIPE 1A 12 9.00 0.02 0.015 6.30 3.98 0.63 Incoming Flow*0.18 1.00 Pipe Capacity 0.90 0.13 Generated Runoff Volume - 10 year,2 hr 0.13 1.25 0.90 Conveyance Calculations DRAINAGE BASIN 1A Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. .. . 1.486 . Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious 1B 3138 0.07 0.95 0.0684 DB - Roof 1B 820 0.02 0.95 0.0179 DB - Pervious 1B 463 0.01 0.20 0.0021 Totals 4,421 0.10 0.0884 Weighted C:0.87 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 C - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 51 Sb - Slope of Basin (ft/ft)0.014 Tt - Time of Conc. - Sheet Flow (min.)1.34 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 54 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.013 V - Velocity (ft/sec) 0.23 Tc - Time of Conc. - Shallow Concentrated (min.)3.90 *Channel/Pipe Flow L - Length of Channel (ft) 32 n - Manning's Coefficient 0.011 R - Hydraulic Radius(ft) 0.30 Sc - Slope of Channel (ft/ft)0.02 V - Velocity (ft/sec) 8.59 Tc - Time of Conc. - Channel/Pipe (min.)0.06 hr 0.09 min 5.3 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.87 3.81 0.34 25 1.1 0.96 4.68 0.46 50 1.2 1.00 5.34 0.54 100 1.25 1.00 5.99 0.61 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.10 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.87 Weighted C = Cf*C= 0.87 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.04 Q (cfs) = 0.06 0.010 Req. Runoff Volume (ft3)=261 Req. Runoff Volume (ft3)=446 859 Pipe Pipe Size (in) Flow Depth - d (in) Slope (ft/ft) Manning's n Provided Velocity (fps)Provided Capacity (cfs)Required Capacity (cfs) PIPE 1B 12 9.00 0.008 0.015 3.99 2.52 0.40 Incoming Flow*0.07 1.00 Pipe Capacity 0.87 0.10 Generated Runoff Volume - 10 year,2 hr 0.10 1.25 0.87 Conveyance Calculations DRAINAGE BASIN 1B Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. = =.(). = . =1.486 . Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious 1C 0 0.00 0.95 0.0000 DB - Roof 1C 2107 0.05 0.95 0.0460 DB - Pervious 1C 0 0.00 0.20 0.0000 Totals 2,107 0.05 0.0460 Weighted C:0.95 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 24.8 Sb - Slope of Basin (ft/ft)0.500 Tt - Time of Conc. - Sheet Flow (min.)0.18 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 0 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.008 V - Velocity (ft/sec) 0.00000 Tc - Time of Conc. - Shallow Concentrated (min.)0.00 *Channel/Pipe Flow L - Length of Channel (ft) 121 n - Manning's Coefficient 0.011 R - Hydraulic Radius(ft) 0.15 Sc - Slope of Channel (ft/ft)0.008 V - Velocity (ft/sec) 3.42 Tc - Time of Conc. - Channel/Pipe (min.)0.59 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.95 3.87 0.18 25 1.1 1.00 4.76 0.23 50 1.2 1.00 5.43 0.26 100 1.25 1.00 6.09 0.29 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.05 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.95 Weighted C = Cf*C= 0.95 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.02 Q (cfs) = 0.03 0.005 Req. Runoff Volume (ft3)=136 Req. Runoff Volume (ft3)=212 410 Pipe Pipe Size (in) Flow Depth - d (in) Slope (ft/ft) Manning's n Provided Velocity (fps)Provided Capacity (cfs)Required Capacity (cfs) PIPE 1C 6 4.50 0.008 0.015 2.51 0.40 0.18 1.00 Pipe Capacity 0.95 0.05 Generated Runoff Volume - 10 year,2 hr 0.05 1.25 0.95 Conveyance Calculations DRAINAGE BASIN 1C Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. =.(). = = . =1.486 . Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac)Runoff Coefficient (C)A (Ac) x C DB - Impervious 1D 0 0.00 0.95 0.0000 DB - Roof 1D 795 0.02 0.95 0.0173 DB - Pervious 1D 0 0.00 0.20 0.0000 Totals 795 0.02 0.0173 Weighted C:0.95 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.011 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 27 Sb - Slope of Basin (ft/ft)0.500 Tt - Time of Conc. - Sheet Flow (min.)0.19 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 0 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.008 V - Velocity (ft/sec) 0.00000 Tc - Time of Conc. - Shallow Concentrated (min.)0.00 *Channel/Pipe Flow L - Length of Channel (ft) 111 n - Manning's Coefficient 0.015 R - Hydraulic Radius(ft) 0.15 Sc - Slope of Channel (ft/ft)0.008 V - Velocity (ft/sec) 2.51 Tc - Time of Conc. - Channel/Pipe (min.)0.74 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.95 3.87 0.07 25 1.1 1.00 4.76 0.09 50 1.2 1.00 5.43 0.10 100 1.25 1.00 6.09 0.11 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.02 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.95 Weighted C = Cf*C= 0.95 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.01 Q (cfs) = 0.01 0.002 Req. Runoff Volume (ft3)=51 Req. Runoff Volume (ft3)=80 154 Pipe Pipe Size (in) Flow Depth - d (in) Slope (ft/ft) Manning's n Provided Velocity (fps)Provided Capacity (cfs)Required Capacity (cfs) PIPE 1D 6 4.50 0.008 0.015 2.51 0.40 0.07 Generated Runoff Volume - 10 year,2 hr 0.02 1.25 0.95 1.00 Pipe Capacity DRAINAGE BASIN 1D Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. Conveyance Calculations 0.95 0.02 .. . 1.486 . Land Use Drainage Basin Number Contributing Area (sf)Contributing Area (Ac)Runoff Coefficient (C)A (Ac) x C DB - Impervious 2 620 0.01 0.95 0.0135 DB - Roof 2 0 0.00 0.95 0.0000 DB - Pervious 2 3141 0.07 0.20 0.0144 Totals 3,761 0.09 0.0279 Weighted C:0.32 Time Of Concentration (HEC-22 Manual) *Sheet Flow Ku - Unit Conversion Constant 0.42 n - Roughness Coefficient 0.17 P2 - 2yr, 24 hr Rainfall Depth (in)1.18 L- Length of Basin (ft) 57.3 Sb - Slope of Basin (ft/ft)0.100 Tt - Time of Conc. - Sheet Flow (min.)4.68 *Shallow Concentrated Flow L - Length of Concentrated Flow (ft) 0 Ku - Unit Conversion Constant 3.28 k - Intercept Coefficient 0.619 Sp - Slope (%)0.025 V - Velocity (ft/sec) 0.00 Tc - Time of Conc. - Shallow Concentrated (min.)0.00 *Channel/Pipe Flow L - Length of Channel (ft) 0 n - Manning's Coefficient 0.011 R - Hydraulic Radius(ft) 0.25 Sc - Slope of Channel (ft/ft)0.008 V - Velocity (ft/sec) 0 Tc - Time of Conc. - Channel/Pipe (min.)0.00 hr 0.08 min 5.0 Storm Event (yr) C - Runoff Coefficient Cf - Frequency Adjustment Factor C * Cf - (not to exceed 1)I - Intensity (in/hr) A - Area (acres)Q - Peak Runoff (cfs) 10 1 0.32 3.87 0.11 25 1.1 0.36 4.76 0.15 50 1.2 0.39 5.43 0.18 100 1.25 0.40 6.09 0.21 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.09 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.32 Weighted C = Cf*C= 0.32 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.01 Q (cfs) = 0.02 0.003 Req. Runoff Volume (ft3)=82 Req. Runoff Volume (ft3)=153 296 0.40 0.32 0.09 Generated Runoff Volume - 10 year,2 hr 0.09 1.25 0.32 Conveyance Calculations DRAINAGE BASIN 2 Contributing Area & Runoff Coefficient Tabulation Time of Concentration (Ttotal) - 5 Minute Min. .. . 1.486 . Design Rainfall Frequency (year): 10,100 Storage Method: Retention Rational Method Peak Runoff Equation: Q = Cf*CIA Discharge Method: N/A Q = Peak Runoff Rate (cfs) Facility Type: Stormtech C = Runoff Coefficient Facility Make/Model: N/A I = Rainfall Intensity (in/hr): 0.41,0.10 A = Drainage Basin (acres) Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious 1A 3833 0.09 0.95 0.0836 DB - Roof 1A 1497 0.03 0.95 0.0326 DB - Pervious 1A 400 0.01 0.20 0.0018 DB - Impervious 1B 3138 0.07 0.95 0.0684 DB - Roof 1B 820 0.02 0.95 0.0179 DB - Pervious 1B 463 0.01 0.20 0.0021 DB - Impervious 1C 0 0.00 0.95 0.0000 DB - Roof 1C 2107 0.05 0.95 0.0460 DB - Pervious 1C 0 0.00 0.95 0.0000 DB - Roof 1D 795 0.02 0.95 0.0173 Totals 13,053 0.30 0.2698 Weighted C:0.90 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.30 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.90 Weighted C = Cf*C= 0.90 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.098 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.11 Q (cfs) = 0.18 0.03 Req. Runoff Volume (ft3)=796 Req. Runoff Volume (ft3)=1,316 2,537 Proposed Retention Facility Volume (ft3)1,117 0.30 1.25 0.90 1.00 Storage Facility Calculations RETENTION FACILITY 1 Basis For Calculations Contributing Area & Runoff Coefficient Tabulation Generated Runoff Volume - 10 year,2 hr Storage Facility Information Design Rainfall Frequency (year): 10,100 Storage Method: Offsite Rational Method Peak Runoff Equation: Q = Cf*CIA Discharge Method: N/A Q = Peak Runoff Rate (cfs) Facility Type: N/A C = Runoff Coefficient Facility Make/Model: N/A I = Rainfall Intensity (in/hr): 0.41,0.10 A = Drainage Basin (acres) Land Use Drainage Basin Number Contributing Area (sf) Contributing Area (Ac) Runoff Coefficient (C)A (Ac) x C DB - Impervious 2 620 0.01 0.95 0.0135 DB - Roof 2 0 0.00 0.95 0.0000 DB - Pervious 2 3141 0.07 0.20 0.0144 Totals 3,761 0.09 0.0279 Weighted C:0.32 Generated Runoff Volume - 100 year 2hr 24hr Total Area (Acres) = 0.09 Total Area (Acres) = Correction Factor (Cf)= 1.00 Correction Factor (Cf)= Weighted C = 0.32 Weighted C = Cf*C= 0.32 Cf*C=Cf*C ≤ 1 Intensity (in/hr) = 0.41 Intensity (in/hr) = 0.61 0.10 Duration (hr) 2.00 Duration (hr) 2.00 24.00 Q (cfs) = 0.01 Q (cfs) = 0.02 0.00 Req. Runoff Volume (ft3)=82 Req. Runoff Volume (ft3)=153 296 Generated Runoff Volume - 10 year,2 hr 0.09 1.25 0.32 0.40 Storage Facility Calculations OFFSITE FLOW DB 2 Basis For Calculations Storage Facility Information Contributing Area & Runoff Coefficient Tabulation Appendix C Groundwater Monitoring Client:Hannah House, LLC.Project #:587-04 Project: Delta Gamma Site Alteration Location:See Site Plan Year:2025 Inspector:EV or Staff Well # 1 (Depth - ft) 21-May 10.00 2.85 7.15 DRY 28-May 10.00 2.85 7.15 DRY 5-Jun 10.00 2.85 7.15 DRY 12-Jun 10.00 2.85 7.15 DRY 19-Jun 10.00 2.85 7.15 DRY 26-Jun 10.00 2.85 7.15 DRY SGW Depth (BGS)(ft)Date Height of Pipe (AGS)(ft)COMMENTS 2025 GROUNDWATER MONITORING RESULTS Appendix D NRCS Soil Survey United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Gallatin County Area, MontanaNatural Resources Conservation Service October 8, 2025 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map (Delta Gamma)......................................................................................9 Legend................................................................................................................10 Map Unit Legend (Delta Gamma).......................................................................11 Map Unit Descriptions (Delta Gamma)...............................................................11 Gallatin County Area, Montana.......................................................................13 350B—Blackmore silt loam, 0 to 4 percent slopes......................................13 UL—Urban land...........................................................................................14 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map (Delta Gamma)505680050569005057000505710050572005057300505680050569005057000505710050572005057300496200 496300 496400 496500 496600 496700 496800 496900 497000 497100 496200 496300 496400 496500 496600 496700 496800 496900 497000 497100 45° 40' 11'' N 111° 3' 0'' W45° 40' 11'' N111° 2' 13'' W45° 39' 49'' N 111° 3' 0'' W45° 39' 49'' N 111° 2' 13'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 200 400 800 1200 Feet 0 50 100 200 300 Meters Map Scale: 1:4,620 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Gallatin County Area, Montana Survey Area Data: Version 29, Aug 30, 2025 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 18, 2022—Aug 29, 2022 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend (Delta Gamma) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 350B Blackmore silt loam, 0 to 4 percent slopes 24.8 25.3% UL Urban land 73.4 74.7% Totals for Area of Interest 98.2 100.0% Map Unit Descriptions (Delta Gamma) The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, Custom Soil Resource Report 11 onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Gallatin County Area, Montana 350B—Blackmore silt loam, 0 to 4 percent slopes Map Unit Setting National map unit symbol: 56q7 Elevation: 4,850 to 5,550 feet Mean annual precipitation: 18 to 22 inches Mean annual air temperature: 37 to 43 degrees F Frost-free period: 80 to 95 days Farmland classification: All areas are prime farmland Map Unit Composition Blackmore and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Blackmore Setting Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Parent material:Calcareous loess Typical profile A - 0 to 10 inches: silt loam Bt - 10 to 27 inches: silty clay loam Bk1 - 27 to 42 inches: silt loam Bk2 - 42 to 60 inches: silt loam Properties and qualities Slope:0 to 4 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high (0.20 to 0.57 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:30 percent Available water supply, 0 to 60 inches: High (about 11.4 inches) Interpretive groups Land capability classification (irrigated): 4e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R043BP818MT - Upland Grassland Group Hydric soil rating: No Minor Components Bowery Percent of map unit:5 percent Landform:Alluvial fans, stream terraces Down-slope shape:Linear Custom Soil Resource Report 13 Across-slope shape:Linear Ecological site:R044BC032MT - Loamy (Lo) 15-19" PZ Frigid North Hydric soil rating: No Blackmore Percent of map unit:3 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R043BP820MT - Upland Shrubland Group Hydric soil rating: No Brodyk Percent of map unit:2 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044BC030MT - Limy (Ly) 15-19" PZ Frigid North Hydric soil rating: No UL—Urban land Map Unit Composition Urban land:100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Custom Soil Resource Report 14 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 16 Appendix E Stormwater O&M Plan Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 1 August 25, 2025 STORMWATER FACILITIES OPERATION & MAINTENANCE PLAN FOR: Delta Gamma Site Alteration PROPERTY DESCRIPTION 410 W GARFIELD ST BOZEMAN, MT 59715 CAPITOL HILL ADD, S13, T02 S, R05 E, BLOCK 34, Lots 1 - 4 RESPONSIBLE PARTY Maloney Holdings LLC Bozeman, MT Sue Doss – Owners Rep 406-570-7080 STORMWATER FACILITIES DESCRIPTION Storm Sewer Network: The on-site storm sewer network is comprised of pre-cast concrete curb inlets and manholes, ADS Nyloplast drain basins and inline drains, and ADS HP storm pipe that conveys runoff to the storm chamber systems. Infiltration Chamber Systems: The proposed stormwater retention chamber systems for the project are ADS Stormtech MC-3500 Chamber Systems. The system is detailed in the site exhibit in Attachment B and are generally comprised of open-bottomed plastic arches surrounded with washed angular stone to provide storage and infiltration of runoff. Runoff enters the system through a manhole with an internal weir that directs initial runoff to the isolator row of the system. This row is lined with a woven geotextile fabric and an inspection port for easy cleaning of accumulated debris and sediment. On the other side of the weir is the invert to the pipe manifold that distributes remaining runoff into the rest of the chamber system. The ADS Isolator Row O&M Manual is included with this plan in Attachment C for reference. INSPECTION & MAINTENANCE SCHEDULE The stormwater facilities on site will be inspected and maintained based on the below schedule. Inspection and maintenance will be performed by the responsible party, the facility employees, or a contracted third party. Inspection: Routine inspection of stormwater facilities will include visual inspection to ensure the facilities are functioning properly and there is no debris accumulated in or clogging the stormwater facilities. Inspections should also be performed after major storm events producing approximately 0.5” of rainfall in a 24-hour period. These inspections shall include observations of the stormwater facilities for areas of erosion or areas of ponding, and removal of accumulated trash or debris in facilities. Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 2 August 25, 2025 Maintenance: Maintenance shall be performed as necessary based on inspections, and at regular intervals throughout the year based on the schedule below. Routine Maintenance will generally include removal of trash, overgrown vegetation, grass clippings, leaves, accumulated sediment, and obstructions in stormwater facilities. Major maintenance will be scheduled as necessary to repair or replace damaged storm structures and to revegetate areas of erosion or dead vegetation. Inspection & Maintenance Schedule BMP Inspection Frequency A=Annual, M=Monthly, S=After Major Storm, Q=Quarterly, SA=Semi Annually Maintenance Frequency Catch Basin / Storm Inlet Q 1 / year Swale M 2-3 / year Storm Chase Q 2-3 / year Storm Pond M 3-4 / year Wet Pond Q 2-3 / year Dry Well A 1 / year Underground Storage System SA 1 / year Infiltration Trenches A, S 2-3 / year Table Source: Stormwater Equipment Manufacturers Association Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 3 August 25, 2025 ATTACHMENT A Acknowledgement of Stormwater Facility Maintenance Requirements ACKNOWLEDGEMENT OF STORMWATER FACILITIES MAINTENANCE REQUIREMENTS PROJECT NAME: Delta Gamma Site Alteraon CITY OF BOZEMAN PLANNING APPLICATION NUMBER: 25091 DATE: August 25, 2025 PROPERTY OWNER: Maloney Holdings LLC NAME OF PLAN/DEVELOPMENT: Delta Gamma Site Altera on LOT/BLOCK/SUBDIVISION: CAPITOL HILL ADD, S13, T02 S, R05 E, BLOCK 34, Lots 1 – 4 Property Owner hereby acknowledges that they are required to maintain all stormwater facilies on the Property pursuant to Bozeman Municipal Code sec. 40.04.720. This requirement is binding on any successor or assign of the Property Owner listed above. The City requires stormwater facilies be construct ed and adequately maintained on the Property in order to maintain the health, safety and welfare of City residents. Adequate maintenance is defined as keeping the stormwater facilies and all components thereof in good working condion so that these stormwater facilies connue to perform in accordance with the design intent. Should the Property Owner fail to adequately maintain stormwater facilies, the City may enter upon th e Property and take such steps as are necessary to correct deficiencies. The City may assess against the Property Owner for the cost of any repairs or necessary maintenance by any means provided for in the Bozeman Municipal Code. By signing below Property Owner acknowledges they have read this document and the applicable provisions of the Bozeman Municipal Code, and they agree to the maintenance requirements for all stormwater facilies on their property. Signature: ______________________________ Date: __________________ By: _________________, __________________________ Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 4 August 25, 2025 ATTACHMENT B Stormwater Facility Exhibit OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP PPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHPOHP OHP OHP OHPOHP OHP OHP OHPOHPOHP OHPOHP OHP OHPOHPOHP OHPOHP OHPOHPOHPPP OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP OHP GASGASGASGASGASGASGASGASGASGASGASGASGASGASSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWRSWR SWR SWR SWR SWR SWR SWR SWR OHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPOHPWWWW12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''W 12''WGAS GASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGASGAS GAS GAS SWRSWRSWRSWRSWRW V W V SS T E E GV ST OSWWEST GARFIELD ST S FOURTH AVE.LOT 3 4203.61 SQ FT 14' ALLEYLOT 2 4203.61 SQ FT LOT 1 4203.61 SQ FT LOT 4 4203.61 SQ FT LOT 5 LOT 6 6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''W6''WSS SS SS SS GAS GAS GAS GAS GAS WWWWWWWWST ST ST S T S T ST ST ST ST ST ST ST ST ST ST STOSW CO STST ST ST ST STSTSTSTSTSTSTSTST ST PROPOSED BUILDING FF=4904.50 STMH 1 (4.0') RIM:4903.92 INV IN:4897.53 (12")(NW) INV OUT:4897.33 (24")(E)STMH 2 (4.0') RIM:4903.77 INV IN:4897.53 (12")(NE) INV OUT:4897.33 (24")(W) ST INLET 1 (4.0') W/ SLOTTED GRATE RIM:4903.40 INV IN:4898.12 (6")(N) INV OUT:4897.96 (12")(SE) ST INLET 2 (4.0') W/ CURB INLET TBC:4903.51 RIM:4903.01 INV IN:4898.37 (6")(N) INV OUT:4898.17 (12")(SW) 31' of 12" HP PIPE @ 2.05% 21' of 12" HP PIPE @ 2.00% PROPOSED BUILDING FF=4904.50 VALLEY GUTTER 48' of 6" @ 0.80% 33' of 6" @ 0.91% DRAIN BASIN - 2 (2.0') RIM:4901.14 INV IN:4898.75 (6")(W) INV OUT:4898.75 (6")(S) INLINE DRAIN - 1 (1.2') RIM:4902.22 INV IN:4899.22 (6")(E) DRAIN BASIN - 1 (2.0') RIM:4902.00 INV IN:4898.70 (6")(E) INV OUT:4898.60 (6")(S) INV OUT:4898.70 (6")(W) INLINE DRAIN - 2 (1.2') RIM:4901.59 INV OUT:4899.05 (6")(W) INLINE DRAIN - 3 (1.2') RIM:4900.79 INV OUT:4899.05 (6")(E) 34' of 6" @ 1.03% 48' of 6" @ 1.00% 53' of 6" @ -0.98% ROOF DOWNSPOUTS TO RUN DOWN COLUMNS AND TIE INTO STORM LINE VIA BURIED 6" STORM LATERAL WITH IN LINE TEE FITTING. PROPOSED STORMTECH SYSTEM 1 STORMTECH MC-3500 BOTTOM OF STONE: 4896.41 SHGW:4894.05 PROJECT NO: DATE: ENGINEER: REVISIONS DATENO.DESC. SHEET OF 587-04 10/8/2025 JG 1 2 3 4 5 6 7 8 DELTA GAMMA SITE ALTERATIONBOZEMAN, MONTANASITE PLAN SUBMITTAL9 10'0 20' 1" = 10'SCALE N 1 OF 1 EX. 1STORMWATER EXHIBIT PROJECT NO: DATE: ENGINEER: REVISIONS DATENO.DESC. SHEET OF 587-04 8/25/2025 JG 1 2 3 4 5 6 7 8 DELTA GAMMA SITE ALTERATIONBOZEMAN, MONTANASITE PLAN SUBMITTAL9 COMBO MANHOLE & CURB INLET DETAIL SCALE: NTS3 ACCEPTABLE FILL MATERIALS: STORMTECH MC-3500 CHAMBER SYSTEMS PLEASE NOTE: 1.THE LISTED AASHTO DESIGNATIONS ARE FOR GRADATIONS ONLY. THE STONE MUST ALSO BE CLEAN, CRUSHED, ANGULAR. FOR EXAMPLE, A SPECIFICATION FOR #4 STONE WOULD STATE: "CLEAN, CRUSHED, ANGULAR NO. 4 (AASHTO M43) STONE". 2.STORMTECH COMPACTION REQUIREMENTS ARE MET FOR 'A' LOCATION MATERIALS WHEN PLACED AND COMPACTED IN 9" (230 mm) (MAX) LIFTS USING TWO FULL COVERAGES WITH A VIBRATORY COMPACTOR. 3.WHERE INFILTRATION SURFACES MAY BE COMPROMISED BY COMPACTION, FOR STANDARD DESIGN LOAD CONDITIONS, A FLAT SURFACE MAY BE ACHIEVED BY RAKING OR DRAGGING WITHOUT COMPACTION EQUIPMENT. FOR SPECIAL LOAD DESIGNS, CONTACT STORMTECH FOR COMPACTION REQUIREMENTS. 4.ONCE LAYER 'C' IS PLACED, ANY SOIL/MATERIAL CAN BE PLACED IN LAYER 'D' UP TO THE FINISHED GRADE. MOST PAVEMENT SUBBASE SOILS CAN BE USED TO REPLACE THE MATERIAL REQUIREMENTS OF LAYER 'C' OR 'D' AT THE SITE DESIGN ENGINEER'S DISCRETION. 5.WHERE RECYCLED CONCRETE AGGREGATE IS USED IN LAYERS 'A' OR 'B' THE MATERIAL SHOULD ALSO MEET THE ACCEPTABILITY CRITERIA OUTLINED IN TECHNICAL NOTE 6.20 "RECYCLED CONCRETE STRUCTURAL BACKFILL". NOTES: 1.CHAMBERS SHALL MEET THE REQUIREMENTS OF ASTM F2418, "STANDARD SPECIFICATION FOR POLYPROPYLENE (PP) CORRUGATED WALL STORMWATER COLLECTION CHAMBERS" CHAMBER CLASSIFICATION 45x76 DESIGNATION SS. 2.MC-3500 CHAMBERS SHALL BE DESIGNED IN ACCORDANCE WITH ASTM F2787 "STANDARD PRACTICE FOR STRUCTURAL DESIGN OF THERMOPLASTIC CORRUGATED WALL STORMWATER COLLECTION CHAMBERS". 3.THE SITE DESIGN ENGINEER IS RESPONSIBLE FOR ASSESSING THE BEARING RESISTANCE (ALLOWABLE BEARING CAPACITY) OF THE SUBGRADE SOILS AND THE DEPTH OF FOUNDATION STONE WITH CONSIDERATION FOR THE RANGE OF EXPECTED SOIL MOISTURE CONDITIONS. REFERENCE STORMTECH DESIGN MANUAL FOR BEARING CAPACITY GUIDANCE. 4.PERIMETER STONE MUST BE EXTENDED HORIZONTALLY TO THE EXCAVATION WALL FOR BOTH VERTICAL AND SLOPED EXCAVATION WALLS. 5.REQUIREMENTS FOR HANDLING AND INSTALLATION: ·TO MAINTAIN THE WIDTH OF CHAMBERS DURING SHIPPING AND HANDLING, CHAMBERS SHALL HAVE INTEGRAL, INTERLOCKING STACKING LUGS. ·TO ENSURE A SECURE JOINT DURING INSTALLATION AND BACKFILL, THE HEIGHT OF THE CHAMBER JOINT SHALL NOT BE LESS THAN 3”. ·TO ENSURE THE INTEGRITY OF THE ARCH SHAPE DURING INSTALLATION, a) THE ARCH STIFFNESS CONSTANT SHALL BE GREATER THAN OR EQUAL TO 500 LBS/FT/%. THE ASC IS DEFINED IN SECTION 6.2.8 OF ASTM F2418. AND b) TO RESIST CHAMBER DEFORMATION DURING INSTALLATION AT ELEVATED TEMPERATURES (ABOVE 73° F / 23° C), CHAMBERS SHALL BE PRODUCED FROM REFLECTIVE GOLD OR YELLOW COLORS. MATERIAL LOCATION DESCRIPTION AASHTO MATERIAL CLASSIFICATIONS COMPACTION / DENSITY REQUIREMENT D FINAL FILL: FILL MATERIAL FOR LAYER 'D' STARTS FROM THE TOP OF THE 'C' LAYER TO THE BOTTOM OF FLEXIBLE PAVEMENT OR UNPAVED FINISHED GRADE ABOVE. NOTE THAT PAVEMENT SUBBASE MAY BE PART OF THE 'D' LAYER ANY SOIL/ROCK MATERIALS, NATIVE SOILS, OR PER ENGINEER'S PLANS. CHECK PLANS FOR PAVEMENT SUBGRADE REQUIREMENTS.N/A PREPARE PER SITE DESIGN ENGINEER'S PLANS. PAVED INSTALLATIONS MAY HAVE STRINGENT MATERIAL AND PREPARATION REQUIREMENTS. C INITIAL FILL: FILL MATERIAL FOR LAYER 'C' STARTS FROM THE TOP OF THE EMBEDMENT STONE ('B' LAYER) TO 24" (600 mm) ABOVE THE TOP OF THE CHAMBER. NOTE THAT PAVEMENT SUBBASE MAY BE A PART OF THE 'C' LAYER. GRANULAR WELL-GRADED SOIL/AGGREGATE MIXTURES, <35% FINES OR PROCESSED AGGREGATE. MOST PAVEMENT SUBBASE MATERIALS CAN BE USED IN LIEU OF THIS LAYER. AASHTO M145¹ A-1, A-2-4, A-3 OR AASHTO M43¹ 3, 357, 4, 467, 5, 56, 57, 6, 67, 68, 7, 78, 8, 89, 9, 10 BEGIN COMPACTIONS AFTER 24" (600 mm) OF MATERIAL OVER THE CHAMBERS IS REACHED. COMPACT ADDITIONAL LAYERS IN 12" (300 mm) MAX LIFTS TO A MIN. 95% PROCTOR DENSITY FOR WELL GRADED MATERIAL AND 95% RELATIVE DENSITY FOR PROCESSED AGGREGATE MATERIALS. B EMBEDMENT STONE: FILL SURROUNDING THE CHAMBERS FROM THE FOUNDATION STONE ('A' LAYER) TO THE 'C' LAYER ABOVE. CLEAN, CRUSHED, ANGULAR STONE OR RECYCLED CONCRETE5 AASHTO M43¹ 3, 357, 4, 467, 5, 56, 57 A FOUNDATION STONE: FILL BELOW CHAMBERS FROM THE SUBGRADE UP TO THE FOOT (BOTTOM) OF THE CHAMBER. CLEAN, CRUSHED, ANGULAR STONE OR RECYCLED CONCRETE5 AASHTO M43¹ 3, 357, 4, 467, 5, 56, 57 PLATE COMPACT OR ROLL TO ACHIEVE A FLAT SURFACE.2,3 45" (1140 mm) 18" (450 mm) MIN* 8' (2.4 m) MAX 12" (300 mm) MIN77" (1950 mm) 12" (300 mm) MIN 6" (150 mm) MIN 9" (230 mm) MIN (SEE NOTE 3) D C B A *TO BOTTOM OF FLEXIBLE PAVEMENT. FOR UNPAVED INSTALLATIONS WHERE RUTTING FROM VEHICLES MAY OCCUR, INCREASE COVER TO 24" (600 mm). 6" (150 mm) MIN PERIMETER STONE (SEE NOTE 4) EXCAVATION WALL (CAN BE SLOPED OR VERTICAL) MC-3500 END CAP SUBGRADE SOILS (SEE NOTE 3) PAVEMENT LAYER (DESIGNED BY SITE DESIGN ENGINEER) **THIS CROSS SECTION DETAIL REPRESENTS MINIMUM REQUIREMENTS FOR INSTALLATION. PLEASE SEE THE LAYOUT SHEET(S) FOR PROJECT SPECIFIC REQUIREMENTS. ADS GEOSYNTHETICS 601T NON-WOVEN GEOTEXTILE ALL AROUND CLEAN, CRUSHED, ANGULAR STONE IN A & B LAYERS INSPECTION & MAINTENANCE STEP 1)INSPECT ISOLATOR ROW PLUS FOR SEDIMENT A.INSPECTION PORTS (IF PRESENT) A.1.REMOVE/OPEN LID ON NYLOPLAST INLINE DRAIN A.2.REMOVE AND CLEAN FLEXSTORM FILTER IF INSTALLED A.3.USING A FLASHLIGHT AND STADIA ROD, MEASURE DEPTH OF SEDIMENT AND RECORD ON MAINTENANCE LOG A.4.LOWER A CAMERA INTO ISOLATOR ROW PLUS FOR VISUAL INSPECTION OF SEDIMENT LEVELS (OPTIONAL) A.5.IF SEDIMENT IS AT, OR ABOVE, 3" (80 mm) PROCEED TO STEP 2. IF NOT, PROCEED TO STEP 3. B.ALL ISOLATOR PLUS ROWS B.1.REMOVE COVER FROM STRUCTURE AT UPSTREAM END OF ISOLATOR ROW PLUS B.2.USING A FLASHLIGHT, INSPECT DOWN THE ISOLATOR ROW PLUS THROUGH OUTLET PIPE i)MIRRORS ON POLES OR CAMERAS MAY BE USED TO AVOID A CONFINED SPACE ENTRY ii)FOLLOW OSHA REGULATIONS FOR CONFINED SPACE ENTRY IF ENTERING MANHOLE B.3.IF SEDIMENT IS AT, OR ABOVE, 3" (80 mm) PROCEED TO STEP 2. IF NOT, PROCEED TO STEP 3. STEP 2)CLEAN OUT ISOLATOR ROW PLUS USING THE JETVAC PROCESS A.A FIXED CULVERT CLEANING NOZZLE WITH REAR FACING SPREAD OF 45" (1.1 m) OR MORE IS PREFERRED B.APPLY MULTIPLE PASSES OF JETVAC UNTIL BACKFLUSH WATER IS CLEAN C.VACUUM STRUCTURE SUMP AS REQUIRED STEP 3)REPLACE ALL COVERS, GRATES, FILTERS, AND LIDS; RECORD OBSERVATIONS AND ACTIONS. STEP 4)INSPECT AND CLEAN BASINS AND MANHOLES UPSTREAM OF THE STORMTECH SYSTEM. NOTES 1.INSPECT EVERY 6 MONTHS DURING THE FIRST YEAR OF OPERATION. ADJUST THE INSPECTION INTERVAL BASED ON PREVIOUS OBSERVATIONS OF SEDIMENT ACCUMULATION AND HIGH WATER ELEVATIONS. 2.CONDUCT JETTING AND VACTORING ANNUALLY OR WHEN INSPECTION SHOWS THAT MAINTENANCE IS NECESSARY. MC-3500 ISOLATOR ROW PLUS DETAIL NTS 24" (600 mm) HDPE ACCESS PIPE REQUIRED USE FACTORY PRE-CORED END CAP PART #: MC3500IEPP24BC OR MC3500IEPP24BW STORMTECH HIGHLY RECOMMENDS FLEXSTORM INSERTS IN ANY UPSTREAM STRUCTURES WITH OPEN GRATES COVER PIPE CONNECTION TO END CAP WITH ADS GEOSYNTHETICS 601T NON-WOVEN GEOTEXTILE MC-3500 CHAMBER OPTIONAL INSPECTION PORT MC-3500 END CAP ONE LAYER OF ADSPLUS125 WOVEN GEOTEXTILE BETWEEN FOUNDATION STONE AND CHAMBERS 8.25' (2.51 m) MIN WIDE CONTINUOUS FABRIC WITHOUT SEAMS SUMP DEPTH TBD BY SITE DESIGN ENGINEER (24" [600 mm] MIN RECOMMENDED) INSTALL FLAMP ON 24" (600 mm) ACCESS PIPE PART #: MCFLAMP MC-SERIES END CAP INSERTION DETAIL NTS NOTE: MANIFOLD STUB MUST BE LAID HORIZONTAL FOR A PROPER FIT IN END CAP OPENING. MANIFOLD HEADER MANIFOLD STUB STORMTECH END CAP MANIFOLD HEADER MANIFOLD STUB 12" (300 mm) MIN SEPARATION 12" (300 mm) MIN INSERTION 12" (300 mm) MIN SEPARATION 12" (300 mm) MIN INSERTION PART #STUB B C MC3500IEPP06T 6" (150 mm)33.21" (844 mm)--- MC3500IEPP06B ---0.66" (17 mm) MC3500IEPP08T 8" (200 mm)31.16" (791 mm)--- MC3500IEPP08B ---0.81" (21 mm) MC3500IEPP10T 10" (250 mm)29.04" (738 mm)--- MC3500IEPP10B ---0.93" (24 mm) MC3500IEPP12T 12" (300 mm)26.36" (670 mm)--- MC3500IEPP12B ---1.35" (34 mm) MC3500IEPP15T 15" (375 mm)23.39" (594 mm)--- MC3500IEPP15B ---1.50" (38 mm) MC3500IEPP18TC 18" (450 mm) 20.03" (509 mm)---MC3500IEPP18TW MC3500IEPP18BC ---1.77" (45 mm)MC3500IEPP18BW MC3500IEPP24TC 24" (600 mm) 14.48" (368 mm)---MC3500IEPP24TW MC3500IEPP24BC ---2.06" (52 mm)MC3500IEPP24BW MC3500IEPP30BC 30" (750 mm)---2.75" (70 mm) NOMINAL CHAMBER SPECIFICATIONS SIZE (W X H X INSTALLED LENGTH)77.0" X 45.0" X 86.0" (1956 mm X 1143 mm X 2184 mm) CHAMBER STORAGE 109.9 CUBIC FEET (3.11 m³) MINIMUM INSTALLED STORAGE*175.0 CUBIC FEET (4.96 m³) WEIGHT 134 lbs.(60.8 kg) NOMINAL END CAP SPECIFICATIONS SIZE (W X H X INSTALLED LENGTH)75.0" X 45.0" X 22.2" (1905 mm X 1143 mm X 564 mm) END CAP STORAGE 14.9 CUBIC FEET (0.42 m³) MINIMUM INSTALLED STORAGE*45.1 CUBIC FEET (1.28 m³) WEIGHT 49 lbs.(22.2 kg) *ASSUMES 12" (305 mm) STONE ABOVE, 9" (229 mm) STONE FOUNDATION, 6" SPACING BETWEEN CHAMBERS, 6" (152 mm) STONE PERIMETER IN FRONT OF END CAPS AND 40% STONE POROSITY MC-3500 TECHNICAL SPECIFICATION NTS 90.0" (2286 mm) ACTUAL LENGTH 86.0" (2184 mm) INSTALLED BUILD ROW IN THIS DIRECTION NOTE: ALL DIMENSIONS ARE NOMINAL LOWER JOINT CORRUGATION WEB CREST CREST STIFFENING RIB VALLEY STIFFENING RIB B C 75.0" (1905 mm) 45.0" (1143 mm) 25.7" (653 mm) FOOT 77.0" (1956 mm) 45.0" (1143 mm) STUBS AT BOTTOM OF END CAP FOR PART NUMBERS ENDING WITH "B" STUBS AT TOP OF END CAP FOR PART NUMBERS ENDING WITH "T" END CAPS WITH A WELDED CROWN PLATE END WITH "C" END CAPS WITH A PREFABRICATED WELDED STUB END WITH "W" UPPER JOINT CORRUGATION 22.2" (564 mm) INSTALLED CUSTOM PRECORED INVERTS ARE AVAILABLE UPON REQUEST. INVENTORIED MANIFOLDS INCLUDE 12-24" (300-600 mm) SIZE ON SIZE AND 15-48" (375-1200 mm) ECCENTRIC MANIFOLDS. CUSTOM INVERT LOCATIONS ON THE MC-3500 END CAP CUT IN THE FIELD ARE NOT RECOMMENDED FOR PIPE SIZES GREATER THAN 10" (250 mm). THE INVERT LOCATION IN COLUMN 'B' ARE THE HIGHEST POSSIBLE FOR THE PIPE SIZE. PART #STUB B C MC3500IEPP06T 6" (150 mm)33.21" (844 mm)--- MC3500IEPP06B ---0.66" (17 mm) MC3500IEPP08T 8" (200 mm)31.16" (791 mm)--- MC3500IEPP08B ---0.81" (21 mm) MC3500IEPP10T 10" (250 mm)29.04" (738 mm)--- MC3500IEPP10B ---0.93" (24 mm) MC3500IEPP12T 12" (300 mm)26.36" (670 mm)--- MC3500IEPP12B ---1.35" (34 mm) MC3500IEPP15T 15" (375 mm)23.39" (594 mm)--- MC3500IEPP15B ---1.50" (38 mm) MC3500IEPP18TC 18" (450 mm) 20.03" (509 mm)---MC3500IEPP18TW MC3500IEPP18BC ---1.77" (45 mm)MC3500IEPP18BW MC3500IEPP24TC 24" (600 mm) 14.48" (368 mm)---MC3500IEPP24TW MC3500IEPP24BC ---2.06" (52 mm)MC3500IEPP24BW MC3500IEPP30BC 30" (750 mm)---2.75" (70 mm) NOMINAL CHAMBER SPECIFICATIONS SIZE (W X H X INSTALLED LENGTH)77.0" X 45.0" X 86.0" (1956 mm X 1143 mm X 2184 mm) CHAMBER STORAGE 109.9 CUBIC FEET (3.11 m³) MINIMUM INSTALLED STORAGE*175.0 CUBIC FEET (4.96 m³) WEIGHT 134 lbs.(60.8 kg) NOMINAL END CAP SPECIFICATIONS SIZE (W X H X INSTALLED LENGTH)75.0" X 45.0" X 22.2" (1905 mm X 1143 mm X 564 mm) END CAP STORAGE 14.9 CUBIC FEET (0.42 m³) MINIMUM INSTALLED STORAGE*45.1 CUBIC FEET (1.28 m³) WEIGHT 49 lbs.(22.2 kg) *ASSUMES 12" (305 mm) STONE ABOVE, 9" (229 mm) STONE FOUNDATION, 6" SPACING BETWEEN CHAMBERS, 6" (152 mm) STONE PERIMETER IN FRONT OF END CAPS AND 40% STONE POROSITY MC-3500 TECHNICAL SPECIFICATION NTS 90.0" (2286 mm) ACTUAL LENGTH 86.0" (2184 mm) INSTALLED BUILD ROW IN THIS DIRECTION NOTE: ALL DIMENSIONS ARE NOMINAL LOWER JOINT CORRUGATION WEB CREST CREST STIFFENING RIB VALLEY STIFFENING RIB B C 75.0" (1905 mm) 45.0" (1143 mm) 25.7" (653 mm) FOOT 77.0" (1956 mm) 45.0" (1143 mm) STUBS AT BOTTOM OF END CAP FOR PART NUMBERS ENDING WITH "B" STUBS AT TOP OF END CAP FOR PART NUMBERS ENDING WITH "T" END CAPS WITH A WELDED CROWN PLATE END WITH "C" END CAPS WITH A PREFABRICATED WELDED STUB END WITH "W" UPPER JOINT CORRUGATION 22.2" (564 mm) INSTALLED CUSTOM PRECORED INVERTS ARE AVAILABLE UPON REQUEST. INVENTORIED MANIFOLDS INCLUDE 12-24" (300-600 mm) SIZE ON SIZE AND 15-48" (375-1200 mm) ECCENTRIC MANIFOLDS. CUSTOM INVERT LOCATIONS ON THE MC-3500 END CAP CUT IN THE FIELD ARE NOT RECOMMENDED FOR PIPE SIZES GREATER THAN 10" (250 mm). THE INVERT LOCATION IN COLUMN 'B' ARE THE HIGHEST POSSIBLE FOR THE PIPE SIZE. CONCEPTUAL ELEVATIONS MAXIMUM ALLOWABLE GRADE (TOP OF PAVEMENT/UNPAVED):12.50 MINIMUM ALLOWABLE GRADE (UNPAVED WITH TRAFFIC):6.50 MINIMUM ALLOWABLE GRADE (UNPAVED NO TRAFFIC):6.00 MINIMUM ALLOWABLE GRADE (TOP OF RIGID CONCRETE PAVEMENT):6.00 MINIMUM ALLOWABLE GRADE (BASE OF FLEXIBLE PAVEMENT):6.00 TOP OF STONE:5.50 TOP OF MC-3500 CHAMBER:4.50 24" ISOLATOR ROW PLUS INVERT:0.92 24" ISOLATOR ROW PLUS INVERT:0.92 BOTTOM OF MC-3500 CHAMBER:0.75 BOTTOM OF STONE:0.00 PROPOSED LAYOUT 5 STORMTECH MC-3500 CHAMBERS 2 STORMTECH MC-3500 END CAPS 12 STONE ABOVE (in) 9 STONE BELOW (in) 40 STONE VOID 1117 INSTALLED SYSTEM VOLUME (CF) (PERIMETER STONE INCLUDED) (COVER STONE INCLUDED) (BASE STONE INCLUDED) 350 SYSTEM AREA (SF) 99.9 SYSTEM PERIMETER (ft) MAX FLOWINVERT*DESCRIPTIONITEM ON LAYOUTPART TYPE 2.06"24" BOTTOM PRE-CORED END CAP, PART#: MC3500IEPP24BC / TYP OF ALL 24" BOTTOM CONNECTIONS AND ISOLATOR PLUS ROWSAPREFABRICATED END CAP INSTALL FLAMP ON 24" ACCESS PIPE / PART#: MCFLAMP (TYP 2 PLACES)BFLAMP (DESIGN BY ENGINEER / PROVIDED BY OTHERS)CCONCRETE STRUCTURE (DESIGN BY ENGINEER / PROVIDED BY OTHERS)DCONCRETE STRUCTURE 41.53'8.42'39.53'6.42'NOTES •THE SITE DESIGN ENGINEER MUST REVIEW ELEVATIONS AND IF NECESSARY ADJUST GRADING TO ENSURE THE CHAMBER COVER REQUIREMENTS ARE MET. •NOT FOR CONSTRUCTION: THIS LAYOUT IS FOR DIMENSIONAL PURPOSES ONLY TO PROVE CONCEPT & THE REQUIRED STORAGE VOLUME CAN BE ACHIEVED ON SITE. *INVERT ABOVE BASE OF CHAMBER BD C A ISOLATOR ROW PLUS (SEE DETAIL) NO WOVEN GEOTEXTILE BED LIMITS STORMTECH SYSTEM 1 SCALE: NTS1 COMBO MANHOLE & CURB INLET DETAIL SCALE: NTS2 COMBO MANHOLE & CURB INLET DETAIL SCALE: NTS5COMBO MANHOLE & CURB INLET DETAIL SCALE: NTS4 C6.2 DETAILS Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 5 August 25, 2025 ATTACHMENT C ADS Stormtech Isolator Row O&M Manual Isolator® Row O&M Manual 2 Looking down the Isolator Row from the manhole opening, woven geotextile Fabric is shown between the chamber and stone base. StormTech Isolator Row with Overflow Spillway (not to scale) The Isolator® Row Introduction An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a technique to inexpensively enhance Total Suspended Solids (TSS) and Total Phosphorus (TP) removal with easy access for inspection and maintenance. The Isolator RowThe Isolator Row is a row of StormTech chambers, either SC-160, SC-310, SC-310-3, SC-740, DC-780, MC-3500 or MC-7200 models, that is surrounded with filter fabric and connected to a closely located manhole for easy access. The fabric-wrapped chambers provide for sediment settling and filtration as stormwater rises in the Isolator Row and passes through the filter fabric. The open bottom chambers and perforated sidewalls (SC-310, SC- 310-3 and SC-740 models) allow stormwater to flow both vertically and horizontally out of the chambers. Sediments are captured in the Isolator Row protecting the adjacent stone and chambers storage areas from sediment accumulation. ADS geotextile fabric is placed between the stone and the Isolator Row chambers. The woven geotextile provides a media for stormwater filtration, a durable surface for maintenance, prevents scour of the underlying stone and remains intact during high pressure jetting. A non-woven fabric is placed over the chambers to provide a filter media for flows passing through the chamber’s sidewall. The non-woven fabric is not required over the SC-160, DC-780, MC-3500 or MC-7200 models as these chambers do not have perforated side walls. The Isolator Row is designed to capture the “first flush” runoff and offers the versatility to be sized on a volume basis or a flow-rate basis. An upstream manhole provides access to the Isolator Row and includes a high/low concept such that stormwater flow rates or volumes that exceed the capacity of the Isolator Row bypass through a manifold to the other chambers. This is achieved with an elevated bypass manifold or a high-flow weir. This creates a differential between the Isolator Row row of chambers and the manifold to the rest of the system, thus allowing for settlement time in the Isolator Row. After Stormwater flows through the Isolator Row and into the rest of the chamber system it is either exfiltrated into the soils below or passed at a controlled rate through an outlet manifold and outlet control structure. The Isolator Row may be part of a treatment train system. The treatment train design and pretreatment device selection by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, StormTech recommend using the Isolator Row 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. ECCENTRICHEADER MANHOLEWITHOVERFLOWWEIR STORMTECHISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS 3 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, percent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspections. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For subsequent 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 determine 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. 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 maintenance, 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. Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water nozzle 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 manhole 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 culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. JetVac reels can vary in length. For ease of maintenance, ADS recommends Isolator Row lengths up to 200" (61 m). 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. Isolator Row Inspection/Maintenance StormTech Isolator Row (not to scale) Note: Non-woven fabric is only required over the inlet pipe connection into the end cap for SC-160LP, DC-780, MC-3500 and MC-7200 chamber models and is not required over the entire Isolator Row. Isolator Row Step By Step Maintenance Procedures 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 Row 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 floor 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 The ADS logo and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. Stormtech® and the Isolator® Row are registered trademarks of StormTech, Inc. © 2022 Advanced Drainage Systems, Inc. #11011 2/22 CS  )( Sample Maintenance Log Date Stadia Rod Readings Sedi- ment Depth (1)–(2) Observations/Actions InspectorFixed point to chamber bottom (1) Fixed point to top of sediment (2) 3/15/11 6.3 ft none New installation. Fixed point is CI frame at grade DJM 9/24/11 6.2 0.1 ft Some grit felt SM 6/20/13 5.8 0.5 ft Mucky feel, debris visible in manhole and in Isolator Row, maintenance due NV 7/7/13 6.3 ft 0 System jetted and vacuumed DJM adspipe.com 800-821-6710 Delta Gamma Site Alteration – Stormwater Facilities Operation & Maintenance Plan Page 6 August 25, 2025 ATTACHMENT D Sample Inspection Form Chapter 6 - Storm Drainage Design 6-44 City of Bozeman Design and Construction Standards Stormwater Facility Inspection Form Section 1: General Information Facility ID: Facility Type: Choose an item. Date/Time: Click or tap to enter a date. Owner: Contact: Inspector’s Name, contact info: Choose an item. Location/Access info: Type of Inspection: ☐ Routine, Dry Weather ☐ Routine, Wet Weather ☐ Complaint Driven ☐ Other: __________________ Section 2: Weather and Discharge Information Most recent precipitation or melt: Temperature: Is a stormwater discharge occurring? ☐ Yes ☐ No If yes, what is the source and quality of discharge? Is an illegal discharge occurring? ☐ Yes ☐ No If yes, what is the source and quality of discharge? Section 3: Facility Maintenance Priority ☐ Low: Stormwater facility appears to be functioning as designed. Continue scheduled maintenance. ☐ Medium: Stormwater facility requires minor to moderate sediment and vegetation maintenance to mitigate the risk of flooding, waterway pollution, and infrastructure failure. ☐ High: Stormwater facility requires significant sediment dredging, vegetation removal, and/or infrastructure repairs to restore function. Notes, Findings & Recommendations: Inspector’s Signature: ________________________________ Date: ___________________ Chapter 6 - Storm Drainage Design 6-45 City of Bozeman Design and Construction Standards Section 4: Qualitative Analysis Components # Items Conditions Results Notes and Required Actions General Degraded, missing, or inadequate Yes 1.1 Accessibility maintenance access? No ☐☐ Trash, sediment, and waste within 1.2 Debris ☐Yes and around the facility? ☐ No Overgrown or dead cattails, Yes 1.3 Vegetation woody shrubs, weeds, grass, and ☐ trees? ☐ No Infrastructure Damaged inlet pipe, outlet pipe, Yes1.4 ☐ Condition outfall structure, or fencing? ☐ No Facility Condition Pretreatment Bay Clogged, obstructed, or filled 2.1 ☐ Yes or Facility pretreatment forebay or facility? ☐ No 2.2 Storage Bay Clogged or filled storage bay? ☐ Yes ☐ No Stagnant water with infiltration Groundwater or Yes 2.3 greater than 48 hours post-rain ☐ Standing Water event? ☐ No 2.4 Flow Path Clogged or obstructed flow path? ☐ Yes ☐ No Barren or exposed surfaces on Yes 2.5 Side Slopes ☐ Facility’s side slopes and bottom? ☐ No Maintenance Maintenance Plan Is there a written plan specific to ☐ Yes 3.1 or Agreement this facility? ☐ No Yes 3.2 Implementation Is there evidence of maintenance? ☐ ☐ No Chapter 6 - Storm Drainage Design 6-46 City of Bozeman Design and Construction Standards Section 5: Quantitative Analysis Vegetation Cover type % Within facility Notes Bare ground Aquatics Grasses/Herbaceou Trees >3” DBH Shrubs Total 100 Elevation Analysis Location Reading (ft) Elevation (ft) Notes SRV#CP Control Point SRV#1 Inlet SRV#2 Outlet SRV#3 Center SRV#4 North of Center SRV#5 East of Center SRV#6 South of Center SRV#7 West of center SRV#8 Berm or overflow SRV#9 Summary Chapter 6 - Storm Drainage Design 6-47 City of Bozeman Design and Construction Standards Section 6: Facility Maintenance Inspection Exhibit Chapter 6 - Storm Drainage Design 6-48 City of Bozeman Design and Construction Standards Photo 1 description Photo 2 description Section 7: Photo Log