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HomeMy WebLinkAboutStormwaterDrainagePlan_06-29-21Stormwater Drainage Plan Bozeman Cohousing Bozeman, MT 109 E. Main St. Suite B, Bozeman, MT 59715 I OFFICE 406.728.4611 I EMAIL wgm@wgmgroup.com REPORT DATE: June 29, 2021 AUTHOR: Mace Mangold, PE, LEED AP Senior Project Engineer WGM Group, Inc. WGM PROJECT: 20-02-03 BOZEMAN COHOUSING Stormwater Drainage Plan CONTENTS 1.0 LOCATION AND DESCRIPTION ........................... 1 1.1 LOCATION ....................................................................................................... 1 1.2 DESCRIPTION OF PROPERTY ............................................................... 2 1.3 GENERAL PROJECT DESCRIPTION .................................................... 2 1.4 CONSTRUCTION SCHEDULE ................................................................ 2 2.0 EXISTING DRAINAGE ............................................ 3 2.1 EXISTING DRAINAGE PATTERNS ........................................................ 3 3.0 STORMWATER DESIGN CRITERIA ................... 3 3.1 REGULATIONS............................................................................................. 3 3.2 GENERAL CRITERIA ................................................................................. 4 3.3 HYDROLOGY ............................................................................................... 4 3.4 SOILS INFORMATION .............................................................................. 5 4.0 PROPOSED DESIGN .............................................. 6 4.1 PRE-DEVELOPED RUNOFF RATES .................................................... 6 4.2 PROPOSED DRAINAGE SYSTEM ........................................................ 7 4.3 LOW IMPACT DEVELOPMENT ............................................................ 8 4.4 WATER QUALITY TREATMENT .......................................................... 11 4.5 HYDRAULIC DESIGN………………………………………………………………………11 5.0 CONCLUSIONS ....................................................... 12 5.1 HYDRAULIC DESIGN ................................................................................ 12 5.2 RELEASE RATES ....................................................................................... 12 5.3 COMPLIANCE WITH STANDARDS .................................................... 12 6.0 REFERENCES .......................................................... 13 APPENDICES A – DRAINAGE AREA MAPS B – NRCS SOIL INFORMATION C – SOILS INVESTIGATION REPORT D – STORAGE-INFILTRATION ANALYSIS E – STORMWATER PLAN SHEETS F – LID CONCEPT SITE PLAN RENDERING G – HYDRAULIC CONVEYANCE ANALYSIS H – STORMWATER SYSTEM OPERATION AND MAINTENANCE PLAN 1 BOZEMAN COHOUSING Stormwater Drainage Plan 1.0 LOCATION AND DESCRIPTION 1.1 LOCATION The Bozeman Cohousing development site is located at 3120 Wagon Wheel Road approximately 2 miles south of downtown Bozeman. The site is located on the east side of Wagon Wheel Road in the NW ¼ of SW ¼ of Section 19, Township 2S, Range 6E. The development will be comprised of 10 fourplex units, 3 accessory dwelling units, a common house, garages, storage sheds, parking areas, gardens, orchards and open space. FIGURE 1. VICINITY MAP 2 BOZEMAN COHOUSING Stormwater Drainage Plan FIGURE 2. PROJECT LOCATION 1.2 DESCRIPTION OF PROPERTY The property is approximately 5.3-acres in total size and is comprised of two legal parcels. The site is bounded on the west by Wagon Wheel Road. The site is bounded on the north, east, and south sides by several private properties. Mathew Bird Creek flows through the east edge of the property. Existing conditions on the site are as shown in the aerial photo in Figure 2. Existing development includes a home, storage shed, driveway, garden, corrals, and fields for grazing. 1.3 GENERAL PROJECT DESCRIPTION The new site development will be comprised of 10 fourplex units, 3 accessory dwelling units, a common house, garages, storage sheds, paved parking areas, gardens, orchards, open space, paved roadways, soft and paved woonerfs, paved and fines pedestrian paths, water and sewer extensions, and a stormwater management system. The stormwater management system is comprised of dispersed treatment-conveyance-infiltration features including bioswales, rain gardens, cobble infiltration galleries, and dry streambeds, along with standard closed storm drain conduits and inlets. 1.4 CONSTRUCTION SCHEDULE Project construction is anticipated to begin in spring of 2021. 3 BOZEMAN COHOUSING Stormwater Drainage Plan 2.0 EXISTING DRAINAGE 2.1 EXISTING DRAINAGE PATTERNS The site is located on a relatively flat terrace adjacent to Mathew Bird Creek. The majority of the site is gently sloped toward the center of the northern property boundary. The eastern quarter of the property is sloped toward Mathew Bird Creek. The hillside adjacent to the stream is steep with 30-40 percent slopes. The site may receive a small amount of offsite drainage from the Woodridge Addition to the south. Appendix A contains a pre- development drainage area exhibit. As shown on Sheet 1 of Appendix A, there are two major existing sub-basins for the site, and most drainage currently flows northward towards the center of the northern property line. 3.0 STORMWATER DESIGN CRITERIA 3.1 REGULATIONS The stormwater drainage plan for this project has been developed to exceed stormwater drainage design criteria required by the City of Bozeman Design Standards and Specifications Policy (City Standards), dated March 2004. Minimum design criteria per the design standards included:  Stormwater runoff from the development site shall be limited to the pre- development runoff rates. Adequate on-site stormwater detention shall be provided for design storm runoff exceeding the pre-development rate.  Stormwater storage and treatment facilities shall be designed to remove pollutants.  Storm sewer facilities shall be designed to handle a 25-year storm event.  The drainage plan shall include, to the greatest extent feasible, low impact development practices that infiltrate, evapotranspire, or capture for reuse the runoff generated from the first 0.5 inches of rainfall from a 24-hour storm preceded by 48 hours of no measurable precipitation. The Design Standards reference a modified Rational Method to calculate detention storage for the 10-year, 2-hour storm event and the standard Rational Method to calculate peak runoff of the 25-year storm event. 3.2 PROJECT DESIGN CRITERIA The Bozeman Cohousing design team has elected to implement a stormwater management system that substantially exceeds City of Bozeman minimum design criteria. The overarching project design goal is to fully infiltrate the 100-year, 6-hour storm event. This translates to approximately seventy (70) percent greater rainfall depth (e.g. 0.81 inches vs. 1.35 inches) in which to base stormwater storage and infiltration design in comparison to City Standards. 4 BOZEMAN COHOUSING Stormwater Drainage Plan Stormwater conveyance infrastructure is designed based on the 25-year event as calculated using the Rational Method per City Standards. The conveyance design conservatively assumes that the storage and infiltration infrastructures do not attenuate peak flow rates. The proposed design substantially complies or exceeds the City’s objective that “the drainage plan shall include, to the greatest extent feasible, low impact development practices that infiltrate, evapotranspire, or capture for reuse the runoff generated from the first 0.5 inches of rainfall from a 24-hour storm preceded by 48 hours of no measurable precipitation.” For project design purposes and to promote infrastructure longevity, the “0.5 inches of rainfall from a 24-hour storm” is used as a metric for pre-treatment in advance of stormwater runoff entering cobble infiltration galleries that serve as the primary feature for infiltrating large storm events. 3.3 HYDROLOGY The design storms investigated for this site include the 2-year, 5-year, 10-year, 25-year, and the 100-year recurrence intervals to document that post-development runoff rates do not exceed that of pre-development conditions. The Soils Conservation Service (SCS) hydrologic method is used for evaluating storage, infiltration and discharge rates as it provides a more technically sound methodology for hydrograph generation in comparison to the Rational Method. The Rational Method is used to evaluate peak runoff rates to document adequate 25-year conveyance capacity. SCS hydrologic modeling was performed in Hydraflow Hydrographs Extension Version 2020. The 6-hour duration SCS storm was used for hydrograph generation with rainfall depths input based on precipitation data from the Montana Department of Transportation (MDT) Hydraulics Manual, Chapter 7, Appendix B-2017 (see Table 2). The 6-hour return interval is considered conservative relative to City Standards. TABLE 2. MDT PRECIPITATION DEPTHS FOR BOZEMAN PRECIPITATION DEPTHS & FREQUENCY FREQUENCY 2-HOUR RAINFALL (inches) 6-HOUR RAINFALL (inches) 24-HOUR RAINFALL (inches) Water Quality 0.5 0.5 0.5 2-YEAR .49 .71 1.18 5-YEAR .68 0.88 1.49 10-YEAR .81* 0.99 1.70** 25-YEAR .98 1.14 2.96 100-YEAR 1.22 1.35** 2.34 * Approximately equivalent to City Standard for minimum design storm ** Design objective is to fully infiltrate the 100-yr, 6-hr event and the 10-yr, 24-hr event. The SCS method uses a combination of soil conditions and land-use to assign a runoff factor to an area. These runoff factors, called runoff curve numbers (CN), indicate the runoff potential. The CN is a basin parameter with a range of 0 to 100. The value of CN depends on the hydrologic soil group, the soil cover type, the percentage of impervious areas in the 5 BOZEMAN COHOUSING Stormwater Drainage Plan watershed, and the antecedent moisture conditions of the soil. Higher CN values result in higher runoff volumes and rates. 3.4 SOILS INFORMATION The CN values selected for the project were based upon soils information from both the Natural Resources Conservation Service (NRCS) Web Soil Survey and review of geotechnical test pit data. There are three NRCS soil map units on the property: 1) 350B – Blackmore silt loam (HSG “C”), 2) 512B – Enbar-Nythar loams (HSG “C”), and 3) 542A – Blossberg loam (HSG “B/D”). The majority of the proposed development is within the Blackmore silt loam. The NRCS hydrologic soil group designation was taken into account during selection of CN’s for both pre-development and post-development hydrologic conditions. A NRCS Web Soil Survey report can be found in Appendix B. A CN value of 74 is used for pervious areas and 98 for impervious areas. Soil test pits were dug on March 27th, 2020 by C&H Engineering as documented in the Soils Investigation Report (see Appendix C). Groundwater was not encountered in any of the test pits and no evidence of seasonally high groundwater was observed. Test pits generally identified a Silty Clay Organic layer in the 0- to 2-feet below ground surface (bgs) range, a Sandy Silt layer in the 1- to 10-feet bgs range, and a Poorly Graded Gravel with Sand and Cobbles starting to appear around 8-feet bgs and regularly observed at depths greater than 10-feet bgs. Soil infiltration testing was not performed due to frozen ground conditions. Field testing will be conducted during construction to confirm infiltration rates used for design. For design purposes, saturated hydraulic conductivity (Ksat) values per Circular DEQ-8, Appendix C (see Table 3) are used and anticipated to be conservative. A Ksat value 0.7 inches per hour (in/hr) is assumed for rain gardens and cobble streambed galleries based on the “fine sandy loam, loam” soil classification with no pretreatment. A Ksat value 3.9 in/hr is assumed for cobble recharge galleries and drywells based on hydraulic connection provided to the deeper gravel-sand substrate. This number is calculated based on the table classification of “gravel, gravelly sand, or very coarse sand” and a 50 percent allowable increase based on upgradient rain gardens and cobble streambed galleries serving as pretreatment to protect the long-term porosity of the infiltrative footprint (i.e. 2.6 in/hr x 1.5 = 3.9 in/hr). TABLE 3. DESIGN INFILTRATION RATES PER DEQ-8 6 BOZEMAN COHOUSING Stormwater Drainage Plan 4.0 PROPOSED DESIGN 4.1 PRE-DEVELOPED RUNOFF RATES Stormwater runoff from the development site is required to be limited to the pre- development runoff rates. Pre-development condition is assumed to be native good standing vegetation (i.e. existing buildings and gravel road is conservatively discounted). As shown on Sheet 1 of Appendix A, there are two existing sub-basins for the site, and most drainage currently flows northward towards the center of the northern property line. Smaller periphery portions of the site are not specifically assessed for pre- vs post- developed runoff comparison as these areas remain relatively unchanged such that flow rate alterations are negligible. Furthermore, the project’s design objective to fully infiltrate the 100-year design storm will reliably offset any minor periphery flow increases that may occur. TABLE 4. PRE-DEVELOPED HYDROLOGIC SUMMARY DRAINAGE ID STORM FREQUENCY PRE-DEVELOPED FLOW (cfs) E1 2YR 0.000 5YR 0.021 10YR 0.037 25YR 0.062 100YR 0.114 E2 2YR 0.050 5YR 0.237 10YR 0.430 25YR 0.744 100YR 1.318 4.2 PROPOSED DRAINAGE SYSTEM The stormwater management system is comprised of dispersed treatment-conveyance- infiltration features including bioswales, rain gardens, cobble infiltration galleries, and dry streambeds, along with standard closed storm drain conduits and inlets. The features were designed to fully infiltrate approximately the 25-year design storm from each individual drainage area and the 100-year design storm when evaluated in series. Figure 3 presents graphical illustration showing hydraulic routing of the 100-year design storm for Drainage Area 2 (DA2). The stormwater management feature for DA2 consists of a rain garden that infiltrates small frequent storms in the 0” to 0.5” range, while large storm events result in the rain garden filling to a level where it directly engages the subsurface cobble gallery. Hydraulic routing analysis results show zero discharge of the 100-year design storm as depicted by the red line in Figure 3 and a total infiltration volume of 2500+/- cubic feet. This discharge is fully infiltrated via downgradient infiltration features. 7 BOZEMAN COHOUSING Stormwater Drainage Plan FIGURE 3. DA2 STORAGE-INFILTRATION-DISCHARGE SUMMARY The final stormwater management feature is a rain garden at the northern perimeter of the property. This feature functions to store and infiltrate runoff from DA5 along with residual overflow from upgradient features. Figure 4 illustrates the cumulative runoff and zero discharge from the 100-year design storm. FIGURE 4. FINAL RAIN GARDEN STORAGE-INFILTRATION-DISCHARGE SUMMARY INFLOW INFILTRATION ZERO DISCHARGE INFLOW INFILTRATION ZERO DISCHARGE 8 BOZEMAN COHOUSING Stormwater Drainage Plan A plan-profile view of the “stormwater management corridor” is provided in Appendix A to aid in visualizing downstream progression of each feature. Detailed calculations for all drainage areas and stormwater management features are provided in Appendix D. Stormwater design plan sheets are provided in Appendix E. 4.3 LOW IMPACT DEVELOPMENT (LID) City Standards specify that “the drainage plan shall include, to the greatest extent feasible, low impact development practices that infiltrate, evapotranspire, or capture for reuse the runoff generated from the first 0.5 inches of rainfall from a 24-hour storm preceded by 48 hours of no measurable precipitation.” The Cohousing design team has developed a site plan that accommodates notable density with substantially less impervious area compared to traditional development and provides approximately 3x the required runoff reduction volume. The design provides greater than 60% pervious area through LID principals that include shared parking, a woonerf style site traffic circulation model to allow narrower streets, and Grasspave2 ™ porous pavement technology to further reduce hardscape. To optimize stormwater infiltration and associated environmental benefits, the site grading, drainage and landscape plan was comprehensively designed to infiltrate runoff through features dispersed throughout the development. A summary of each feature’s design and performance is provided below. Storage-infiltration analysis for each feature is included in Appendix D. A conceptual illustrative rendering from early in design process is included in Appendix F and Figure 5 below to communicate general components of the LID approach. DA1 – Dry Streambed Infiltration Gallery The first feature in the system is a dry channel located in drainage area (DA) #1. The dry channel will have a 5-foot wide by 1-foot deep cobble gallery; a portion of which will be covered by vegetated streambanks to create an aesthetic stream-like feature. Storage- infiltration analysis indicates that the 25-year design storm will be fully infiltrated. Excess runoff from larger storm events will be conveyed to DA2. DA2 – Rain Garden w/ Cobble Infiltration Gallery DA2 will have a bioswale in the parking lot island that drains to a raingarden with an 8-feet deep cobble infiltration gallery sited directly below. This will result in the bottom of the gallery being in- and on-top of the native gravel-sand substrate layer to maximize infiltration. The bioswale and rain garden will function as pretreatment to protect the long- term infiltrative capacity of the subsurface cobble gallery. Design elevations are such that small, frequent storms will fully infiltrate through the bottom of the bioswale-rain garden footprint. Larger events will result in the rain garden filling to approximately 1-foot and overflow into the subsurface gallery via direct hydraulic connection through the cobble side slope of the rain garden. Storage-infiltration analysis indicates that the 100-year design storm will be fully infiltrated, including upgradient inflow from DA1. The above grade water storage depth is anticipated to range from 12” to 18” during the 10- to 100-year events. Excess runoff from larger storm events will be conveyed to DA3 through the parking lot curb-cut and overflow to the inlet immediately to the east. 9 BOZEMAN COHOUSING Stormwater Drainage Plan FIGURE 5. CONCEPTUAL ILLUSTRATIVE RENDERING FOR LID APPROACH (SEE APPENDIX F FOR FULL-SIZE) 10 BOZEMAN COHOUSING Stormwater Drainage Plan DA3 – Dry Stream Bed to Culvert Crossing Cobble Gallery DA3 will utilize another dry stream bed channel that leads to a culvert crossing below the road and connecting to a drywell. Over-excavation will be conducted during culvert and drywell installation to expose the gravel-sand substrate located approximately 8- to 10-feet below existing grade. The excavation will be backfilled with porous cobble to provide additional subsurface storage capacity in which to hold runoff and increase the infiltration period. The dry stream bed and drywell will be hydraulically connected to the cobble storage gallery to ensure that the infiltration gallery is engaged while also providing notable pretreatment to protect long-term infiltration capacity. Storage-infiltration analysis indicates that the 100-year design storm will be fully infiltrated. Excess runoff from larger storm events will be conveyed through the drywell outlet pipe to the final rain garden that collects DA5. DA4 – Rain Garden DA4 is roughly 50% pervious with grades that result in broad sheet flow runoff. As such, this area is not anticipated to contribute substantial runoff or pollutant loading. A standard rain garden (no subsurface gallery) is proposed to treat, store and infiltrate runoff. The discharge pipe includes a hydraulic control to provide approximately 1-foot of storage volume prior to discharging to the DA5 rain garden. Storage-infiltration analysis indicates that the 25-year design storm will be fully infiltrated. Excess runoff from larger storm events will be conveyed to DA5 through an overflow inlet and buried storm drain pipe. DA5 – Rain Garden DA5 contains the final feature in the stormwater management system. A minimum 900 cubic feet rain garden with a drywell structure provides adequate storage volume to fully infiltrate runoff for DA5 along with residual runoff from upgradient drainage areas. Storage- infiltration analysis indicates that the 100-year design storm will be fully infiltrated. DA6 – Depressional Areas The eastern periphery of the project includes limited increase in impervious area such that only marginal increase of runoff is anticipated. The grading plan results in depressional areas at the top of the slope above Mathew Bird Creek. These areas will store and infiltrate runoff such that post-development runoff rates are less than that of pre-development. These features will also reduce the frequency of sheet flow runoff that is causing shallow rill erosion on the existing slope such that vegetative cover will improve post-construction, further decreasing runoff and reducing sediment loading to the creek. Grasspave Pervious Road The development design includes reduced impervious area by incorporating a porous roadway material for a large portion of the drivable surface. This measure will reduce runoff by promoting broad infiltration. Note that the runoff reduction provided by this measure was not included in the hydrologic analysis such that the runoff analysis is expected to be conservative. 11 BOZEMAN COHOUSING Stormwater Drainage Plan 4.4 WATER QUALITY TREATMENT The LID design results in full infiltration of the 100-year event, equating to 1.35”. This exceeds the required 0.5”. 4.5 HYDRAULIC DESIGN Inlets, ditches and culverts are sized to handle the 25-year storm as calculated using the Rational Method per City Standards. Conveyance calculations conservatively assume that no peak flow attenuation is provided by upgradient storage-infiltration features. Hydraulic calculations are documented in the Madison Engineering report included as Appendix G. 12 BOZEMAN COHOUSING Stormwater Drainage Plan 5.0 CONCLUSIONS 5.1 HYDRAULIC DESIGN All open channel systems are adequately sized to convey the runoff from the 25-year storm event assuming no storage or infiltration. Based on the results of the hydrograph routing analysis described in sections 4.2 and 4.3, the stormwater management system is expected to reliably attenuate and convey runoff up to the 100-year event. 5.2 RELEASE RATES Runoff release rates from the project site during proposed conditions do not exceed pre- developed rates in receiving conveyances for all design storms evaluated up to the 100- year frequency. Table 5 provides a summary of pre-developed vs. post-developed peak runoff rates from the site for the two primary existing condition drainage areas. Table 5 shows that the post-development peak flow rates are equal to or less than the pre- developed rates for all analysis points. TABLE 5. SUMMARY OF PRE-DEVELOPED AND POST-DEVELOPED FLOWS AT THE ANALYSIS POINTS DISCHARGE POINT STORM FREQUENCY PRE-DEVELOPED (ALLOWABLE) FLOW (cfs) POST-DEVELOPED FLOW (cfs) E1 2YR 0.0 0 5YR 0.02 0 10YR 0.04 0 25YR 0.06 0 100YR 0.11 0 E2 2YR 0.05 <0.05 5YR 0.24 <0.2 10YR 0.43 <0.4 25YR 0.74 <0.7 100YR 1.32 <1.3   5.3 COMPLIANCE WITH STANDARDS The constructed project will improve site drainage through runoff reduction, implementation of a designed stormwater management system, and treatment for pollutant removal. The proposed site improvements are detailed in the construction plan sheets developed for this site. To the best of our knowledge the Storm Drainage Plan has been assembled per the requirements defined within the City of Bozeman Design Standards and Specifications Policy. 13 BOZEMAN COHOUSING Stormwater Drainage Plan 6.0 REFERENCES City of Bozeman, 2004. Design Standards and Specifications Policy. City Engineering Department. March 2004. Adopted April 5, 2004, Ordinance 1611. Montana Department of Environmental Quality, 2017. Montana Standards for Subdivision Storm Water Drainage, Circular DEQ-8. Montana Department of Transportation, 1995. Hydraulics Manual. Adopted from AASHTO Model Drainage Manual. BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX A DRAINAGE AREA MAPS   E13.80 ACRESE21.22 ACRESWGMGROUPWWW.WGMGROUP.COMEXISTING DRAINAGE AREAS BOZEMAN COHOUSING BOZEMAN, MONTANAMARCH 202101PRELIMINARYPLOTTED:SAVED:3/4/213/4/21NTc FLOW PATHSHEET FLOW = 300-FT @ 1.7%SHALLOW CONC. = 167-FT @ 1.2%CONENCTRATED = 130-FT @ 1.5%300 ft 163 ft130 ft 100-YEAR, 6-HRTc FLOW PATHSHEET FLOW = 100-FT @ 2.0%SHALLOW CONC. = 100-FT @ 25%1 0 0 f t 100 ft100-YEAR, 6-HR DA#1DA#2DA#3DA#4DA#5DA#6WGMGROUPWWW.WGMGROUP.COMSTORMWATER MANAGEMENT CORRIDOR BOZEMAN COHOUSING BOZEMAN, MONTANAMARCH 202102PRELIMINARYPLOTTED:SAVED:6/29/216/29/21N DA#1DA#2DA#3DA#4DA#5DA#6WGMGROUPWWW.WGMGROUP.COMSTORMWATER MANAGEMENT CORRIDOR BOZEMAN COHOUSING BOZEMAN, MONTANAJUNE 202103PRELIMINARYPLOTTED:SAVED:6/24/213/8/21N BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX B NRCS SOIL INFORMATION   Hydrologic Soil Group—Gallatin County Area, Montana (Bozeman Cohousing) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/20/2021 Page 1 of 4505490050549205054940505496050549805055000505502050550405055060505490050549205054940505496050549805055000505502050550405055060496730496750496770496790496810496830496850496870496890496910496930496950496970496990 496730 496750 496770 496790 496810 496830 496850 496870 496890 496910 496930 496950 496970 496990 45° 38' 56'' N 111° 2' 31'' W45° 38' 56'' N111° 2' 18'' W45° 38' 51'' N 111° 2' 31'' W45° 38' 51'' N 111° 2' 18'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 50 100 200 300Feet 0 15 30 60 90Meters Map Scale: 1:1,210 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 Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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 24, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 3, 2009—Sep 1, 2016 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. Hydrologic Soil Group—Gallatin County Area, Montana (Bozeman Cohousing) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/20/2021 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 350B Blackmore silt loam, 0 to 4 percent slopes C 4.2 80.4% 512B Enbar-Nythar loams, 0 to 4 percent slopes C 0.1 1.5% 542A Blossberg loam, 0 to 2 percent slopes B/D 1.0 18.1% Totals for Area of Interest 5.3 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Hydrologic Soil Group—Gallatin County Area, Montana Bozeman Cohousing Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/20/2021 Page 3 of 4 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, Montana Bozeman Cohousing Natural Resources Conservation Service January 20, 2021 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.) 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USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Gallatin County Area, Montana.......................................................................13 350B—Blackmore silt loam, 0 to 4 percent slopes......................................13 512B—Enbar-Nythar loams, 0 to 4 percent slopes.....................................14 542A—Blossberg loam, 0 to 2 percent slopes............................................16 Soil Information for All Uses...............................................................................18 Soil Properties and Qualities..............................................................................18 Soil Qualities and Features.............................................................................18 Hydrologic Soil Group (Bozeman Cohousing).............................................18 References............................................................................................................23 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 505490050549205054940505496050549805055000505502050550405055060505490050549205054940505496050549805055000505502050550405055060496730 496750 496770 496790 496810 496830 496850 496870 496890 496910 496930 496950 496970 496990 496730 496750 496770 496790 496810 496830 496850 496870 496890 496910 496930 496950 496970 496990 45° 38' 56'' N 111° 2' 31'' W45° 38' 56'' N111° 2' 18'' W45° 38' 51'' N 111° 2' 31'' W45° 38' 51'' N 111° 2' 18'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 50 100 200 300Feet 0 15 30 60 90Meters Map Scale: 1:1,210 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 24, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 3, 2009—Sep 1, 2016 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 Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 350B Blackmore silt loam, 0 to 4 percent slopes 4.2 80.4% 512B Enbar-Nythar loams, 0 to 4 percent slopes 0.1 1.5% 542A Blossberg loam, 0 to 2 percent slopes 1.0 18.1% Totals for Area of Interest 5.3 100.0% Map Unit Descriptions 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 Custom Soil Resource Report 11 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, 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 capacity: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 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:R044XS355MT - Silty (Si) 15-19" p.z. Hydric soil rating: No Blackmore Percent of map unit:3 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R043BS323MT - Silty (Si) 20"+ p.z. Hydric soil rating: No Brodyk Percent of map unit:2 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044XS357MT - Limy (Ly) 15-19" p.z. Hydric soil rating: No 512B—Enbar-Nythar loams, 0 to 4 percent slopes Map Unit Setting National map unit symbol: 56vw Elevation: 4,300 to 6,100 feet Mean annual precipitation: 15 to 19 inches Mean annual air temperature: 37 to 45 degrees F Frost-free period: 90 to 110 days Farmland classification: Farmland of local importance Map Unit Composition Enbar and similar soils:60 percent Nythar and similar soils:30 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Enbar Setting Landform:Flood plains Down-slope shape:Linear Across-slope shape:Linear Parent material:Loamy alluvium Typical profile A - 0 to 22 inches: loam Cg - 22 to 49 inches: sandy loam 2C - 49 to 60 inches: very gravelly loamy sand Properties and qualities Slope:0 to 4 percent Custom Soil Resource Report 14 Depth to restrictive feature:More than 80 inches Drainage class:Somewhat poorly drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.57 to 1.98 in/hr) Depth to water table:About 24 to 42 inches Frequency of flooding:RareNone Frequency of ponding:None Calcium carbonate, maximum content:10 percent Maximum salinity:Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water capacity:Moderate (about 8.8 inches) Interpretive groups Land capability classification (irrigated): 3w Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C Ecological site: R044BY181MT - Wet Meadow (WM) LRU 44B-Y Hydric soil rating: No Description of Nythar Setting Landform:Flood plains Down-slope shape:Linear Across-slope shape:Linear Parent material:Loamy alluvium Typical profile A - 0 to 8 inches: loam Bg - 8 to 33 inches: silt loam Cg - 33 to 60 inches: sandy loam Properties and qualities Slope:0 to 4 percent Depth to restrictive feature:More than 80 inches Drainage class:Very poorly drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.57 to 1.98 in/hr) Depth to water table:About 0 to 12 inches Frequency of flooding:RareNone Frequency of ponding:None Available water capacity:High (about 9.7 inches) Interpretive groups Land capability classification (irrigated): 5w Land capability classification (nonirrigated): 5w Hydrologic Soil Group: B/D Ecological site: R043BP801MT - Bottomland Hydric soil rating: Yes Minor Components Blossberg Percent of map unit:5 percent Landform:Flood plains Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044XS365MT - Wet Meadow (WM) 15-19" p.z. Custom Soil Resource Report 15 Hydric soil rating: Yes Straw Percent of map unit:5 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044XS355MT - Silty (Si) 15-19" p.z. Hydric soil rating: No 542A—Blossberg loam, 0 to 2 percent slopes Map Unit Setting National map unit symbol: 56wx Elevation: 4,200 to 5,550 feet Mean annual precipitation: 12 to 18 inches Mean annual air temperature: 39 to 45 degrees F Frost-free period: 90 to 110 days Farmland classification: Farmland of local importance Map Unit Composition Blossberg and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Blossberg Setting Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium Typical profile A - 0 to 15 inches: loam Bg - 15 to 24 inches: sandy clay loam 2C - 24 to 60 inches: extremely gravelly loamy coarse sand Properties and qualities Slope:0 to 2 percent Depth to restrictive feature:More than 80 inches Drainage class:Poorly drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.20 to 1.98 in/hr) Depth to water table:About 12 to 24 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:15 percent Maximum salinity:Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm) Available water capacity:Low (about 5.5 inches) Custom Soil Resource Report 16 Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 5w Hydrologic Soil Group: B/D Ecological site: R044BY181MT - Wet Meadow (WM) LRU 44B-Y Hydric soil rating: Yes Minor Components Bonebasin Percent of map unit:10 percent Landform:Terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044XS365MT - Wet Meadow (WM) 15-19" p.z. Hydric soil rating: Yes Meadowcreek Percent of map unit:5 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044XS359MT - Subirrigated (Sb) 15-19" p.z. Hydric soil rating: No Custom Soil Resource Report 17 Soil Information for All Uses Soil Properties and Qualities The Soil Properties and Qualities section includes various soil properties and qualities displayed as thematic maps with a summary table for the soil map units in the selected area of interest. A single value or rating for each map unit is generated by aggregating the interpretive ratings of individual map unit components. This aggregation process is defined for each property or quality. Soil Qualities and Features Soil qualities are behavior and performance attributes that are not directly measured, but are inferred from observations of dynamic conditions and from soil properties. Example soil qualities include natural drainage, and frost action. Soil features are attributes that are not directly part of the soil. Example soil features include slope and depth to restrictive layer. These features can greatly impact the use and management of the soil. Hydrologic Soil Group (Bozeman Cohousing) Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. 18 Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Custom Soil Resource Report 19 20 Custom Soil Resource Report Map—Hydrologic Soil Group (Bozeman Cohousing)505490050549205054940505496050549805055000505502050550405055060505490050549205054940505496050549805055000505502050550405055060496730 496750 496770 496790 496810 496830 496850 496870 496890 496910 496930 496950 496970 496990 496730 496750 496770 496790 496810 496830 496850 496870 496890 496910 496930 496950 496970 496990 45° 38' 56'' N 111° 2' 31'' W45° 38' 56'' N111° 2' 18'' W45° 38' 51'' N 111° 2' 31'' W45° 38' 51'' N 111° 2' 18'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 50 100 200 300Feet 0 15 30 60 90Meters Map Scale: 1:1,210 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 Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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 24, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 3, 2009—Sep 1, 2016 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 21 Table—Hydrologic Soil Group (Bozeman Cohousing) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 350B Blackmore silt loam, 0 to 4 percent slopes C 4.2 80.4% 512B Enbar-Nythar loams, 0 to 4 percent slopes C 0.1 1.5% 542A Blossberg loam, 0 to 2 percent slopes B/D 1.0 18.1% Totals for Area of Interest 5.3 100.0% Rating Options—Hydrologic Soil Group (Bozeman Cohousing) Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Custom Soil Resource Report 22 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 23 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 24 Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Gallatin County Area, Montana Bozeman Cohousing Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/20/2021 Page 4 of 4 BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX C SOILS INVESTIGATION REPORT   1091 Stoneridge Drive • Bozeman, Montana • Phone (406) 587-1115 • Fax (406) 587-9768 www.chengineers.com • E-Mail: info@chengineers.com May 12, 2020 Bozeman Coho, LLC Attn: Mark Owkes Email: mark.owkes@gmail.com RE: Soils Investigation Report – 3120 Wagon Wheel Road; Bozeman, Montana (200302). Dear Mr. Owkes, C&H Engineering and Surveying Inc., (C&H Engineering) has conducted a subsurface soils investigation for the above referenced property. The scope of services was to conduct a subsurface soils investigation and provide a soils investigation report. The report documents the site conditions, soil properties, and provides foundation design and general earthwork recommendations. Proposed Construction It is understood that multiple multi-family structures are planned for construction. It is understood that the structures are planned to be constructed with wither crawl space and/or basement foundations. It has been assumed that the foundation footings will not be subjected to unusual loading conditions such as eccentric loads. If any of the foundation footings will be eccentrically loaded please contact this office so we can appropriately revise our allowable bearing capacity and settlement estimates. Subsurface Soil and Conditions On March 27, 2020 a member of the staff of C&H Engineering visited the site to conduct a subsurface soils investigation. The subsurface soils investigation consisted of examining eight exploratory test pit excavations. The exploratory test pits were excavated with a backhoe provided by Val Mencas Excavation, LLC. The test pit locations were chosen based on the proposed test pit location map provided to our office via email on 3/13/2020. The soil profiles revealed by the exploratory excavations were logged and visually classified according to ASTM D 2488, which utilizes the nomenclature of the Unified Soil Classification System (USCS). The following paragraphs briefly summarize the subsurface soils and conditions observed in the eight exploratory test pits excavated for the field investigation. The soil horizons are described as they were encountered in the test pit excavations, starting with the horizon nearest the surface and proceeding with each additional horizon encountered with depth. SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 2 The first soil horizon encountered in each exploratory excavation was a Silty Clay Organic Soil of low plasticity (OL). This material was dark brown to black in color, moist, and soft. This material was encountered to depths varying from approximately 0.5 feet below grounds surface (bgs) to 2.0 feet bgs in each exploratory excavation. Organic soils are highly compressible and are not suitable for foundation support. This material must also be removed from beneath all interior and exterior concrete slabs as well as beneath all asphalt paving. This material may be stockpiled onsite and used for final site grading purposes. The second soil horizon encountered in each exploratory excavation was a Sandy Silt (ML). This material was present to depths varying from 4.0 feet bgs to 10.5 feet bgs. Penetration test performed on this material indicate that it was medium stiff. This material contained approximately 55 percent fine to coarse grained sand and approximately 45 percent silty fines. The third soil horizon encountered in all exploratory excavations except TP-2 was a Poorly Graded Gravel with Sand and Cobbles (GP). This material was present to the end of each excavation, depths varying from 10.5 feet bgs to 13.0 feet bgs. This material was medium dense to dense, and contained approximately 25 percent fine to coarse grain sand and approximately 75 percent subrounded gravels and cobbles. TP-2: The third soil horizon encountered in this exploratory excavation was a Lean Clay (CL). This material was present to a depth of 9 feet bgs. Penetration test performed on this material indicate that it was medium stiff. Following the Lean Clay, Poorly Graded Gravel was encountered to a depth of 11 feet bgs. Following the Poorly Graded Gravel with Sand, Poorly Graded Sand with Gravel was encountered to 13 feet bgs. Following the Poorly Graded Sand with Gravel, Poorly Graded Gravel with Sand was encountered, this time to the end of excavation at approximately 15 feet bgs. Based on the subsurface investigation, it is expected that the excavations for the foundations will end in varying soil types. It is likely that crawl space excavations will end within the Sandy Silt and that excavations for basements will end within Poorly Graded Gravel with Sand and Cobbles. If either excavation is found to end within the Sandy Silt, it is recommended that the excavation continue down to 12 inches below the desired bottom of footing elevation, or until Poorly Graded Gravel with Sand and Cobbles is encountered, whichever is shallower. This will allow for the placement of 12 inches of structural fill beneath the foundation footings. The purpose of the structural fill is to help mitigate any differential settlement that may occur and also to provide a buffer between the foundation footings and the moisture sensitive Silty Sand. Please note that the recommended allowable bearing capacity for foundation footings bearing on structural fill overlying the Sandy Silt is 1,500 pounds per square foot (psf) and is 3,000 psf for foundation footings bearing on Poorly Graded Gravel with Sand and Cobbles. Although we have proposed a general recommendation for all structures, the foundation SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 3 subgrade for each structure shall be inspected by C&H Engineering and Surveying, Inc. to verify our recommendations are consistent with the exposed subgrade conditions. Groundwater Groundwater was not encountered in any of the exploratory test pits, evidence of seasonally high groundwater (such as lack of calcium, mottling, high moisture was not observed within the depth of excavation). Groundwater is not expected to be encountered within the excavation for the foundations. Please note that our subsurface investigation is not a detailed groundwater study, and groundwater conditions may change dramatically due to conditions that are out of our control. Our assessment of the groundwater conditions is based on the conditions observed within the exploratory test pits on the day of the excavation, our general experience in the project area, and any available literature regarding groundwater conditions in the vicinity of the subject property. If more detailed knowledge of the seasonally high groundwater elevation across the subject property is desired, it is recommended that groundwater monitoring wells be installed and checked weekly from the early spring to late summer months. Foundation Recommendations Based on the subsurface soils encountered in the eight exploratory excavations, it will be acceptable to utilize either a crawl space or basement foundation for the proposed structures. Please find the following as general recommendations for all foundation elements: • In order to keep the footing out of the active frost zone it is recommended that the bottom of all footing elevations be a minimum of 48 inches below finished grade. • Foundation footings are to bear on a minimum of 12 inches of compacted structural fill overlying the Sandy Silt. All foundation footings for this scenario shall be dimensioned for an allowable bearing capacity of 1,500 pounds per square foot (psf). • Foundation footings may also bear on the Poorly Graded Gravel with Sand and Cobbles or on compacted structural fill overlying this material. All foundation footings for this scenario shall be dimensioned for an allowable bearing capacity of 3,000 pounds per square foot (psf). • It is recommended that typical strip footings for this structure have a minimum width of 16 inches and column footings should have a minimum width of 24 inches, provided the soils allowable bearing capacity is not exceeded. Allowable Bearing Capacity & Settlement The bearing capacity of a soil is defined as the ultimate pressure per unit area by the foundation that can be supported by the soil in excess of the pressure caused by the surrounding soil at the SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 4 footing level. Bearing capacity is determined by the physical and chemical properties of the soil located beneath the proposed structures footings. The loads from the proposed structures that are transmitted to a 12-inch thick structural fill pad overlying the Sandy Silt, it is recommended that an allowable bearing capacity of 1,500 pounds per square foot be used to dimension all foundation footings. The loads from the proposed structures that are transmitted to the Poorly Graded Gravel with Sand and Cobbles or to compacted structural fill overlying this material, it is recommended that an allowable bearing capacity of 3,000 pounds per square foot be used to dimension all foundation footings. Settlement and differential settlement were estimated using conservative soil parameters and the assumption that the foundation footings bear on properly placed and compacted structural fill overlying Sandy Silt. Based on conservative soil parameter estimates, the bearing capacity recommended, and the assumption that all recommendations made in this report will be properly implemented, it is expected that total and differential settlement will be ¾-inch or less. Structures of the type proposed can generally tolerate movements of this magnitude, however, this movement should be checked by a structural engineer to determine if it is acceptable. Subgrade Preparation and Structural Fill In general, the excavation must be level and uniform and continue down to 12 inches below the desired bottom of footing elevation or to the Poorly Graded Gravel with Sand and Cobbles whichever is shallower. If any soft spots, are encountered, they will need to be removed and backfilled with structural fill. The excavation width must extend a minimum of one footing width from the outer edges of the footings or to a distance equal to ½ the height of the required structural fill, whichever is greater. For example, if 6 feet of structural fill is required, the excavation must extend out from the footing a minimum distance of 3 feet. Once the excavation is completed, the native subgrade shall be proof rolled with a large compactor to an unyielding condition, if the excavation is found to end in the Sandy Silt a layer of geotextile fabric (Mirafi 500X) must be placed, followed by placing and compacting the required structural fill. Any areas that are found to be pumping or rutting shall be sub-excavated and replaced with structural fill. Structural fill is defined as all fill that will ultimately be subjected to structural loadings, such as those imposed by footings, floor slabs, pavements, etc. Structural fill will need to be imported for this project. Imported structural fill is recommended to be a well graded gravel with sand that contains less than 15 percent of material that will pass a No. 200 sieve and that has a maximum particle size of 3 inches. Also, the fraction of material passing the No. 40 sieve shall have a liquid limit not exceeding 25 and a plasticity index not exceeding 6. The gravel and sand particles also need to be made up of durable rock materials that will not degrade when compacted; no shale or mudstone fragments should be present. Structural fill must be placed in lifts no greater than 12 inches (uncompacted thickness) and be SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 5 uniformly compacted to a minimum of 97 percent of its maximum dry density, as determined by ASTM D698. Typically, the structural fill must be moisture conditioned to within + 2 percent of the materials optimum moisture content to achieve the required density. It is recommended that the structural fill be compacted with a large vibrating smooth drum roller. Please note that if a moisture-density relationship test (commonly referred to as a proctor) needs to be performed for a proposed structural fill material to determine its maximum dry density and optimum moisture content in accordance with ASTM D698, a sample of the material must be delivered to this office a minimum of three full working days prior to beginning placement of the structural fill. At no time should surface water runoff be allowed to flow into and accumulate within the excavation for the foundation elements. If necessary, a swale or berm should be temporarily constructed to reroute all surface water runoff away from the excavation. Excavation should not proceed during large precipitation events. If any of the foundation footings are found to be located on a test pit, the area will need to be excavated down to the full depth of the test pit and structural fill be placed and compacted in lifts (as described in this report) to bring the area back up to the desired grade. Foundation Wall Backfill Approved backfill material should be placed and compacted between the foundation wall and the edge of the excavation. The soils encountered during the field investigation (except the organic soil) are suitable for use as foundation wall backfill along the exterior of the foundation, provided they are not too moist. Structural fill is recommended as foundation wall backfill in all areas that will support concrete slabs-on-grade or other paving improvements. The backfill shall be placed in uniform lifts and be compacted to a minimum of 95 percent of the material’s maximum dry density, as determined by ASTM D698. The foundation wall backfill will need to be compacted with either walk behind compaction equipment or hand operated compaction equipment in order to avoid damaging the foundation walls. If walk behind compaction equipment is used, lifts should not exceed 8-inches (loose thickness) and if hand operated compaction equipment is used lifts should not exceed 4-inches (loose thickness). Interior Slabs-on-Grade In preparation for any interior slabs-on-grade, the excavation must continue down to the Sandy Silt. Structural fill can then be placed and compacted to 6 inches below the bottom of slab elevation. For all interior concrete slabs-on-grade, preventative measures must be taken to stop moisture from migrating upwards through the slab. Moisture that migrates upwards through the concrete slab can damage floor coverings such as carpet, hardwood and vinyl, in addition to causing musty odors and mildew growth. Moisture barriers will need to be installed to prevent water vapor migration and capillary rise through the concrete slab. SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 6 In order to prevent capillary rise through the concrete slab-on-grade it is recommended that 6 inches of ¾-inch washed rock (containing less than 10 percent fines) be placed and compacted once the excavation for the slab is complete. The washed rock has large pore spaces between soil particles and will act as a capillary break, preventing groundwater from migrating upwards towards the bottom of the slab. In order to prevent the upward migration of water vapor through the slab, it is recommended that a 15-mil extruded polyolefin plastic that complies with ASTM E1745 (such as a Stego Wrap 15- mil Vapor Barrier) be installed. The vapor barrier should be pulled up at the sides and secured to the foundation wall or footing. Care must be taken during and after the installation of the vapor barrier to avoid puncturing the material, and all joints are to be sealed per the manufacture’s recommendations. Once the excavation for the interior slab-on-grade is completed as described in the first paragraph of this section, and the ¾ inch washed rock and moisture barriers have been properly installed, it will be acceptable to form and cast the steel reinforced concrete slab. It is recommended that interior concrete slabs-on-grade have a minimum thickness of 4 inches, unless the slab will be supporting vehicles, then the recommended minimum thickness if 6 inches, or as directed by a licensed structural engineer. Exterior Slabs-on-Grade For exterior areas to be paved with concrete slabs, it is recommended that, at a minimum, the topsoil be removed. The native subgrade then needs to be compacted to a minimum of 95 percent of its maximum dry density, as determined by ASTM D698. Then for non-vehicular traffic areas, a minimum of 6 inches of ¾-inch minus rock needs to be placed, and 4 inches of 4000 pounds per square inch (psi) concrete placed over the ¾-inch minus rock. For areas with vehicular traffic, a minimum of 9 inches of ¾-inch minus rock should be placed, followed by 6 inches of 4000 psi concrete, unless directed otherwise by a licensed structural engineer. Exterior slabs that will be located adjacent to the foundation walls need to slope away from the structure at a minimum grade of 2 percent and should not be physically connected to the foundation walls. If they are connected, any movement of the exterior slab will be transmitted to the foundation wall, which may result in damage to the structure. Site Grading Surface water should not be allowed to accumulate and infiltrate the soil near the foundation. Proper site grading will ensure surface water runoff is directed away from the foundation. If the subgrade soils are allowed to experience a significant increase in moisture additional settlement may occur. Please find the following as general site grading recommendations: • Finished grade must slope away from the building a minimum of 5 percent within the first 10 feet, in order to quickly drain ground surface and roof runoff away from the foundation walls. Please note that in order to maintain this slope; it is imperative that any backfill placed against the foundation walls be compacted properly. If the backfill is not SOILS INVESTIGATION REPORT #200302 – 3120 WAGON WHEEL ROAD; BOZEMAN, MONTANA 7 compacted properly, it will settle and positive drainage away from the structure will not be maintained. • Permanent sprinkler heads for lawn care should be located a sufficient distance from the structure to prevent water from draining toward the foundation or saturating the soils adjacent to the foundation. • Rain gutter down spouts are to be placed in such a manner that surface water runoff drains away from the structure. • All roads, walkways, and architectural land features must properly drain away from all structures. Special attention should be made during the design of these features to not create any drainage obstructions that may direct water towards or trap water near the foundation. Asphalt Paving Improvements For areas to be paved with asphalt, it is recommended that, as a minimum, the topsoil be removed. The native subgrade then needs to be compacted at ± 2 percent of its optimum moisture content to 95 percent of its maximum dry density, as determined by ASTM D698. Following compaction of the native subgrade, a layer of woven geotextile (such as a Mirafi 500X) shall be installed. Next a 12-inch layer of compacted 6-inch minus gravel needs to be placed, followed by a 6-inch layer of compacted 1-inch minus road mix. Both gravel courses must be compacted at ± 2 percent of their optimum moisture content to 95 percent of their maximum dry density, as determined by ASTM D698. A 3-inch thick layer of asphalt pavement can then be placed and compacted over this cross-section. Construction Administration The foundation is a vital element of a structure; it transfers all of the structures dead and live loads to the native soil. It is imperative that the recommendations made in this report are properly adhered to. A representative from C&H Engineering should observe the construction of any foundation or drainage elements recommended in this report. The recommendations made in this report are contingent upon our involvement. If the soils encountered during the excavation differ than those described in this report or any unusual conditions are encountered, our office should be contacted immediately to examine the conditions, re-evaluate our recommendations and provide a written response. If construction and site grading take place during cold weather, it is recommended that approved winter construction practices be observed. All snow and ice shall be removed from cut and fill areas prior to site grading taking place. No fill should be placed on soils that are frozen or contain frozen material. No frozen soils can be used as fill under any circumstances. Additionally, Concrete should not be placed on frozen soils and should meet the temperature requirements of ASTM C 94. Any concrete placed during cold weather conditions shall be protected from freezing until the necessary compressive strength has been attained. Once the footings are placed, frost shall not be permitted to extend below the foundation footings, as this SOILS INVESTIGATION REPORT could heave and crack the foundation footings and/or foundation walls. It is the responsibility of the contractor to provide a safe working environment with regards to excavations on the site. All excavations should be sloped or shored in the interest of safety and in accordance with local and federal regulations, including the excavation and trench safety standards provided by the Occupational Safety and Health Administration (OSHA). Report Limitations The recommendations made in this report are based on limited information obtained from the exploratory test pits excavated on the subject property. It is not uncommon for variations in the subsurface conditions to occur, the nature and extent of which do not become evident until additional exploration or construction is conducted. The variations may result in additional construction costs, and it is suggested that a contingency be provided for this purpose. This report is for the exclusive use of Bozeman Coho, LLC. In the absence of our written approval, we make no representation and assume no responsibility to other parties regarding the use of this report. These recommendations are applicable to the subject property only and are not applicable to other construction sites. Under no circumstances shall a portion of this report be removed or be used independently of the rest of the document; this report is applicable as a full document only. Services performed by C&H Engineering and Surveying, Inc. for this project have been conducted with the level of care and skill ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is made. If you have any questions, or if we can assist with the future phases of your project, please contact the undersigned. Respectfully Submitted by Enc: Test Pit Logs Test Pit Location Map Reviewed by /HI lJ/'1 Michael J. Welch, P.E. G:\c&h\20\200302\Report Documents\Soils lnvestigation(200302).doc #200302 -3120 WAGON WHEEL ROAD; BOZEMAN, MONT ANA 8 OL ML GP 2.0 7.0 12.5 0 TO 2 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 2 TO 7 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 7 TO 12.5 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 12.5 feet. NOTES Monitoring Well Installed GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP 1 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJU.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION GB 2-1 MC = 21% Fines = 93% OL ML CL GP SP GP 1.5 4.0 9.0 11.0 13.0 15.0 0 TO 1.5 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 1.5 TO 4 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 4 TO 9 FEET: LEAN CLAY; (CL); tan to brown; moist; medium plasticity; medium stiff; approximately 5 percent fine to coarse grain sand; approximately 95 percent clayey fines. 9 TO 11 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. 11 TO 13 FEET: POORLY GRADED SAND WITH GRAVEL; (SP); brown; moist to very moist; medium dense; approximately 35 percent subrounded gravels; approximately 65 percent fine to coarse grain sand. 13 TO 15 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 15.0 feet. NOTES GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 12/18/19 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0 5 10 15 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP 2 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJTESTS U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION OL ML GP 1.0 9.0 13.0 0 TO 1 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 1 TO 9 FEET: SILTY SAND; (SM); brown; moist; medium stiff; approximately 55 percent fine to coarse grain sand; approximately 45 percent silty fines. 9 TO 13 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist;medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 13.0 feet. NOTES Monitoring Well Installed GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 12/18/19 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP 3 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJU.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION OL ML GP 2.0 7.0 10.0 0 TO 2 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 2 TO 7 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 7 TO 10 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 10.0 feet. NOTES Monitoring Well Installed GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-4 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJU.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION GB 5-1 MC = 22% Fines = 93% OL ML GP 0.5 8.0 10.5 0 TO 0.5 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 0.5 TO 8 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 8 TO 10.5 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 10.5 feet. NOTES GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-5 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJTESTS U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION OL ML GP 1.5 10.5 12.5 0 TO 1.5 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 1.5 TO 10.5 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 10.5 TO 12.5 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 12.5 feet. NOTES Monitoring Well Installed GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-6 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJU.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION OL ML GP 2.0 8.0 12.0 0 TO 2 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 2 TO 8 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 8 TO 12 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 12.0 feet. NOTES GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-7 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJU.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION GB 8-1 MC = 28% Fines = 90% OL ML GP 1.5 8.0 11.5 0 TO 1.5 FEET: ORGANIC SOIL; (OL); dark brown to black; moist; soft. 1.5 TO 8 FEET: SANDY SILT; (ML); brown; moist; soft to medium stiff; approximately 10 percent fine to coarse grain sand; approximately 90 percent silty fines. 8 TO 11.5 FEET: POORLY GRADED GRAVEL WITH SAND AND COBBLES; (GP); moist; medium dense to dense; approximately 75 percent subrounded gravels; approximately 25 percent fine to coarse grain sand. Bottom of test pit at 11.5 feet. NOTES GROUND ELEVATION LOGGED BY Noah J. Schaible, E.I. EXCAVATION METHOD Deere 410 C Backhoe EXCAVATION CONTRACTOR Val Mencas Excavation, LLC GROUND WATER LEVELS: DATE STARTED 3/27/20 COMPLETED 3/27/20 AT TIME OF EXCAVATION --- AFTER EXCAVATION --- AT END OF EXCAVATION ---DEPTH(ft)0.0 2.5 5.0 7.5 10.0 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-8 PROJECT NUMBER 200302 CLIENT Bozeman Coho, LLC PROJECT LOCATION 3120 Wagon Wheel Road, Bozeman, Montana PROJECT NAME Soils Investigation GENERAL BH / TP / WELL - GINT STD US.GDT - 5/12/20 14:37 - G:\C&H\20\200302\TP LOGS\200302.GPJTESTS U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX D STORAGE-INFILTRATION ANALYSIS   BOZEMAN COHOUSING Stormwater Drainage Plan   PRE-DEVELOPMENT FLOW RATES Hydrograph Return Period Recap 1 Hyd. Hydrograph Inflow Peak Outflow (cfs)Hydrograph No. type hyd(s)Description (origin)1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr 1 SCS Runoff ------ 0.064 0.153 ------- 0.238 0.297 0.381 ------- 0.503 DA #2 2 Reservoir 1 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#2 Infil. Gallery 3 SCS Runoff ------ 0.002 0.006 ------- 0.023 0.039 0.062 ------- 0.100 DA#1 4 Reservoir 3 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#1 to Cobble Stream 5 SCS Runoff ------ 0.007 0.047 ------- 0.105 0.149 0.216 ------- 0.325 DA#5 6 SCS Runoff ------ 0.006 0.028 ------- 0.092 0.142 0.219 ------- 0.343 DA#3 7 SCS Runoff ------ 0.002 0.009 ------- 0.030 0.046 0.070 ------- 0.110 DA#4 8 Reservoir(i) 6 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#3 to bioswale/Dry 9 Reservoir 7 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.014 DA#4 to Rain Garden 10 Combine 2, 4, 5, 8, 9 0.007 0.047 ------- 0.105 0.149 0.216 ------- 0.325 <no description> 11 Reservoir 10 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 Final Rain Garden 12 SCS Runoff ------ 0.000 0.000 ------- 0.021 0.037 0.062 ------- 0.114 EXISTING - E1 13 SCS Runoff ------ 0.000 0.050 ------- 0.237 0.430 0.744 ------- 1.318 EXISTING - E2 14 SCS Runoff ------ 0.000 0.001 ------- 0.004 0.006 0.011 ------- 0.036 DA#6 15 Reservoir 14 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#6 to Depressions Proj. file: Cohousing_Final Calcs_03-04-21.gpw Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 TR55 Tc Worksheet 21 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Hyd. No. 12 EXISTING - E1 Description A B C Totals Sheet Flow Manning's n-value = 0.050 0.011 0.011 Flow length (ft) = 300.0 0.0 0.0 Two-year 24-hr precip. (in) = 1.29 0.00 0.00 Land slope (%) = 1.70 0.00 0.00 Travel Time (min) = 16.47 + 0.00 + 0.00 = 16.47 Shallow Concentrated Flow Flow length (ft) = 167.00 0.00 0.00 Watercourse slope (%) = 1.20 0.00 0.00 Surface description = Unpaved Paved Paved Average velocity (ft/s) =1.77 0.00 0.00 Travel Time (min) = 1.57 + 0.00 + 0.00 = 1.57 Channel Flow X sectional flow area (sqft) = 3.00 0.00 0.00 Wetted perimeter (ft) = 3.00 0.00 0.00 Channel slope (%) = 1.50 0.00 0.00 Manning's n-value = 0.035 0.015 0.015 Velocity (ft/s) =5.21 0.00 0.00 Flow length (ft) ({0})130.0 0.0 0.0 Travel Time (min) = 0.42 + 0.00 + 0.00 = 0.42 Total Travel Time, Tc .............................................................................. 18.46 min TR55 Tc Worksheet 23 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Hyd. No. 13 EXISTING - E2 Description A B C Totals Sheet Flow Manning's n-value = 0.050 0.011 0.011 Flow length (ft) = 100.0 0.0 0.0 Two-year 24-hr precip. (in) = 1.29 0.00 0.00 Land slope (%) = 1.22 0.00 0.00 Travel Time (min) = 7.81 + 0.00 + 0.00 = 7.81 Shallow Concentrated Flow Flow length (ft) = 100.00 0.00 0.00 Watercourse slope (%) = 25.00 0.00 0.00 Surface description = Unpaved Paved Paved Average velocity (ft/s) =8.07 0.00 0.00 Travel Time (min) = 0.21 + 0.00 + 0.00 = 0.21 Channel Flow X sectional flow area (sqft) = 0.00 0.00 0.00 Wetted perimeter (ft) = 0.00 0.00 0.00 Channel slope (%) = 0.00 0.00 0.00 Manning's n-value = 0.015 0.015 0.015 Velocity (ft/s) =0.00 0.00 0.00 Flow length (ft) ({0})0.0 0.0 0.0 Travel Time (min) = 0.00 + 0.00 + 0.00 = 0.00 Total Travel Time, Tc .............................................................................. 8.00 min Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 12 EXISTING - E1 Hydrograph type = SCS Runoff Peak discharge = 0.114 cfs Storm frequency = 100 yrs Time to peak = 216 min Time interval = 2 min Hyd. volume = 1,388 cuft Drainage area = 3.800 ac Curve number = 74 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = TR55 Time of conc. (Tc) = 18.46 min Total precip. = 1.35 in Distribution = SCS 6-Hr Storm duration = 6.00 hrs Shape factor = 484 103 0 60 120 180 240 300 360 420 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) EXISTING - E1 Hyd. No. 12 -- 100 Year Hyd No. 12 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 13 EXISTING - E2 Hydrograph type = SCS Runoff Peak discharge = 1.318 cfs Storm frequency = 100 yrs Time to peak = 720 min Time interval = 2 min Hyd. volume = 3,127 cuft Drainage area = 1.220 ac Curve number = 74 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = TR55 Time of conc. (Tc) = 8.00 min Total precip. = 2.67 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 104 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) EXISTING - E2 Hyd. No. 13 -- 100 Year Hyd No. 13 BOZEMAN COHOUSING Stormwater Drainage Plan   POST-DEVELOPMENT FLOW RATES Hydrograph Return Period Recap 1 Hyd. Hydrograph Inflow Peak Outflow (cfs)Hydrograph No. type hyd(s)Description (origin)1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr 1 SCS Runoff ------ 0.064 0.153 ------- 0.238 0.297 0.381 ------- 0.503 DA #2 2 Reservoir 1 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#2 Infil. Gallery 3 SCS Runoff ------ 0.002 0.006 ------- 0.023 0.039 0.062 ------- 0.100 DA#1 4 Reservoir 3 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#1 to Cobble Stream 5 SCS Runoff ------ 0.007 0.047 ------- 0.105 0.149 0.216 ------- 0.325 DA#5 6 SCS Runoff ------ 0.006 0.028 ------- 0.092 0.142 0.219 ------- 0.343 DA#3 7 SCS Runoff ------ 0.002 0.009 ------- 0.030 0.046 0.070 ------- 0.110 DA#4 8 Reservoir(i) 6 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#3 to bioswale/Dry 9 Reservoir 7 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.014 DA#4 to Rain Garden 10 Combine 2, 4, 5, 8, 9 0.007 0.047 ------- 0.105 0.149 0.216 ------- 0.325 <no description> 11 Reservoir 10 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 Final Rain Garden 12 SCS Runoff ------ 0.000 0.000 ------- 0.021 0.037 0.062 ------- 0.114 EXISTING - E1 13 SCS Runoff ------ 0.000 0.050 ------- 0.237 0.430 0.744 ------- 1.318 EXISTING - E2 14 SCS Runoff ------ 0.000 0.001 ------- 0.004 0.006 0.011 ------- 0.036 DA#6 15 Reservoir 14 0.000 0.000 ------- 0.000 0.000 0.000 ------- 0.000 DA#6 to Depressions Proj. file: Cohousing_Final Calcs_03-04-21.gpw Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 DA2INFLOW DISCHARGE INFLOW DA5DA1DISCHARGE INFLOW DISCHARGE DA5 INFLOW DA3 DISCHARGE DA3 INFLOW DA4 DISCHARGE DA4 DA6INFLOW DISCHARGE RESIDUAL INFLOW DA5 PRE-DEVELOPMENT RUNOFF BOZEMAN COHOUSING Stormwater Drainage Plan   STAGE-DISCHARGE PARAMETERS Pond Report 8 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 2 - DA#1 Cobble Stream Gallery Pond Data Trapezoid -Bottom L x W = 200.0 x 5.0 ft, Side slope = 0.05:1, Bottom elev. = 4976.00 ft, Depth = 3.00 ft, Voids = 30.00% Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4976.00 1,000 0 00.30 4976.30 1,006 90 90 0.60 4976.60 1,012 91 181 0.90 4976.90 1,018 91 272 1.20 4977.20 1,025 92 364 1.50 4977.50 1,031 92 457 1.80 4977.80 1,037 93 550 2.10 4978.10 1,043 94 644 2.40 4978.40 1,049 94 738 2.70 4978.70 1,055 95 832 3.00 4979.00 1,062 95 928 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 12.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 4976.00 0.00 0.00 0.00 Length (ft)= 10.00 0.00 0.00 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 5.00 0.00 0.00 0.00 Crest El. (ft)= 4977.00 0.00 0.00 0.00 Weir Coeff.= 2.60 3.33 3.33 3.33 Weir Type = Broad --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.700 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 40.00 Stage (ft) 0.00 4976.00 1.00 4977.00 2.00 4978.00 3.00 4979.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report 5 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 1 - DA#2 Rain Garden Infiltration Gallery Pond Data Trapezoid -Bottom L x W = 22.0 x 22.0 ft, Side slope = 0.05:1, Bottom elev. = 4970.00 ft, Depth = 10.00 ft, Voids = 50.00% Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4970.00 484 0 01.00 4971.00 488 243 243 2.00 4972.00 493 245 488 3.00 4973.00 497 248 736 4.00 4974.00 502 250 986 5.00 4975.00 506 252 1,238 6.00 4976.00 511 254 1,492 7.00 4977.00 515 257 1,748 8.00 4978.00 520 259 2,007 9.00 4979.00 524 261 2,268 10.00 4980.00 529 263 2,532 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 12.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 4970.00 0.00 0.00 0.00 Length (ft)= 10.00 0.00 0.00 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 5.00 0.00 0.00 0.00 Crest El. (ft)= 4978.50 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = Rect --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 3.900 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 33.00 Stage (ft) 0.00 4970.00 2.00 4972.00 4.00 4974.00 6.00 4976.00 8.00 4978.00 10.00 4980.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report 13 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 4 - DA#3 Bioswale Pond Data Trapezoid -Bottom L x W = 170.0 x 5.0 ft, Side slope = 0.05:1, Bottom elev. = 4972.00 ft, Depth = 4.00 ft, Voids = 30.00% Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4972.00 850 0 00.40 4972.40 857 102 102 0.80 4972.80 864 103 206 1.20 4973.20 871 104 310 1.60 4973.60 878 105 415 2.00 4974.00 885 106 521 2.40 4974.40 892 107 627 2.80 4974.80 899 107 735 3.20 4975.20 906 108 843 3.60 4975.60 913 109 952 4.00 4976.00 920 110 1,062 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 24.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 4972.00 0.00 0.00 0.00 Length (ft)= 20.00 0.00 0.00 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 4973.00 0.00 0.00 0.00 Weir Coeff.= 1.05 3.33 3.33 3.33 Weir Type = 45 degV --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.700 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 Stage (ft) 0.00 4972.00 1.00 4973.00 2.00 4974.00 3.00 4975.00 4.00 4976.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report 14 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 5 - DA#3 Dry Well w/ Pipe Trench Gallery Pond Data Trapezoid -Bottom L x W = 32.0 x 8.0 ft, Side slope = 0.05:1, Bottom elev. = 4967.00 ft, Depth = 10.00 ft, Voids = 32.00% Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4967.00 256 0 01.00 4968.00 260 83 83 2.00 4969.00 264 84 166 3.00 4970.00 268 85 252 4.00 4971.00 272 86 338 5.00 4972.00 276 88 426 6.00 4973.00 280 89 515 7.00 4974.00 284 90 605 8.00 4975.00 289 92 697 9.00 4976.00 293 93 790 10.00 4977.00 297 94 884 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 12.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 4967.00 0.00 0.00 0.00 Length (ft)= 20.00 0.00 0.00 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 4974.00 0.00 0.00 0.00 Weir Coeff.= 1.05 3.33 3.33 3.33 Weir Type = 45 degV --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 3.900 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 Stage (ft) 0.00 4967.00 2.00 4969.00 4.00 4971.00 6.00 4973.00 8.00 4975.00 10.00 4977.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report 16 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 6 - DA#4 Rain Garden Pond Data Trapezoid -Bottom L x W = 57.0 x 1.0 ft, Side slope = 2.00:1, Bottom elev. = 4975.00 ft, Depth = 2.00 ft Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4975.00 57 0 0 0.20 4975.20 104 16 16 0.40 4975.40 152 26 42 0.60 4975.60 202 35 77 0.80 4975.80 253 45 123 1.00 4976.00 305 56 178 1.20 4976.20 358 66 245 1.40 4976.40 413 77 322 1.60 4976.60 469 88 410 1.80 4976.80 526 100 510 2.00 4977.00 585 111 621 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 12.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 4975.00 0.00 0.00 0.00 Length (ft)= 10.00 0.00 0.00 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 5.00 0.00 0.00 0.00 Crest El. (ft)= 4976.50 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = Broad --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.700 (by Wet area) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Stage (ft) 0.00 4975.00 0.20 4975.20 0.40 4975.40 0.60 4975.60 0.80 4975.80 1.00 4976.00 1.20 4976.20 1.40 4976.40 1.60 4976.60 1.80 4976.80 2.00 4977.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Tuesday, 06 / 29 / 2021 Pond No. 7 - DA#5 Rain Garden w/ Drywell Pond Data Trapezoid -Bottom L x W = 50.0 x 4.0 ft, Side slope = 0.05:1, Bottom elev. = 4964.00 ft, Depth = 11.00 ft, Voids = 50.00% Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4964.00 200 0 0 1.10 4965.10 206 112 112 2.20 4966.20 212 115 227 3.30 4967.30 218 118 345 4.40 4968.40 224 122 466 5.50 4969.50 230 125 591 6.60 4970.60 236 128 719 7.70 4971.70 242 132 851 8.80 4972.80 248 135 986 9.90 4973.90 254 138 1,124 11.00 4975.00 261 142 1,266 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 24.00 0.00 0.00 0.00 No. Barrels = 1 0 0 0 Invert El. (ft)= 4972.00 0.00 0.00 0.00 Length (ft)= 10.00 0.00 0.00 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a No No No Crest Len (ft)= 10.00 0.00 0.00 0.00 Crest El. (ft)= 4974.90 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = Rect --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 1.000 (by Wet area) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 0.50 1.00 1.50 2.00 Stage (ft) 0.00 4964.00 2.00 4966.00 4.00 4968.00 6.00 4970.00 8.00 4972.00 10.00 4974.00 12.00 4976.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Pond Report 26 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Pond No. 9 - DA#6 Depressional Areas Pond Data Trapezoid -Bottom L x W = 10.0 x 10.0 ft, Side slope = 4.00:1, Bottom elev. = 5975.00 ft, Depth = 2.00 ft Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 5975.00 100 0 0 0.20 5975.20 135 23 23 0.40 5975.40 174 31 54 0.60 5975.60 219 39 93 0.80 5975.80 269 49 142 1.00 5976.00 324 59 201 1.20 5976.20 384 71 272 1.40 5976.40 449 83 355 1.60 5976.60 520 97 452 1.80 5976.80 595 111 564 2.00 5977.00 676 127 691 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)Inactive 0.00 0.00 0.00 Span (in)= 12.00 0.00 0.00 0.00 No. Barrels = 1 000 Invert El. (ft)= 5975.00 0.00 0.00 0.00 Length (ft)= 10.00 0.00 0.00 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a NoNoNo Crest Len (ft)= 10.00 0.00 0.00 0.00 Crest El. (ft)= 5976.50 0.00 0.00 0.00 Weir Coeff.= 2.60 3.33 3.33 3.33 Weir Type = Broad --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.700 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 Stage (ft) 0.00 5975.00 0.20 5975.20 0.40 5975.40 0.60 5975.60 0.80 5975.80 1.00 5976.00 1.20 5976.20 1.40 5976.40 1.60 5976.60 1.80 5976.80 2.00 5977.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q BOZEMAN COHOUSING Stormwater Drainage Plan   STORAGE-DISCHARGE SUMMARY Hydrograph Summary Report 27 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 0.153 1 146 652 ------ ------------ DA #2 2 Reservoir 0.000 1 150 0 1 4970.91 222 DA#2 Infil. Gallery 3 SCS Runoff 0.006 1 239 69 ------ ------------ DA#1 4 Reservoir 0.000 1 266 0 3 4976.09 26.7 DA#1 to Cobble Stream 5 SCS Runoff 0.047 1 152 286 ------ ------------ DA#5 6 SCS Runoff 0.028 1 154 259 ------ ------------ DA#3 7 SCS Runoff 0.009 1 154 83 ------ ------------ DA#4 8 Reservoir(i) 0.000 1 n/a 0 6 4973.00 122 DA#3 to bioswale/Dry 9 Reservoir 0.000 1 185 0 7 4975.48 54.9 DA#4 to Rain Garden 10 Combine 0.047 1 152 286 2, 4, 5, 8, 9 ------------ <no description> 11 Reservoir 0.000 1 171 0 10 4972.83 221 Final Rain Garden 12 SCS Runoff 0.000 2 370 0 ------ ------------ EXISTING - E1 13 SCS Runoff 0.050 2 724 371 ------ ------------ EXISTING - E2 14 SCS Runoff 0.001 2 360 6 ------ ------------ DA#6 15 Reservoir 0.000 2 n/a 0 14 5975.05 6.26 DA#6 to Depressions Cohousing_Final Calcs_03-04-21.gpw Return Period: 2 Year Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 STORAGEELEVATION2-YEAR PEAKDISCHARGE Hydrograph Summary Report 43 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 0.238 1 146 981 ------ ------------ DA #2 2 Reservoir 0.000 1 140 0 1 4971.72 419 DA#2 Infil. Gallery 3 SCS Runoff 0.023 1 152 147 ------ ------------ DA#1 4 Reservoir 0.000 1 234 0 3 4976.17 50.1 DA#1 to Cobble Stream 5 SCS Runoff 0.105 1 151 524 ------ ------------ DA#5 6 SCS Runoff 0.092 1 152 522 ------ ------------ DA#3 7 SCS Runoff 0.030 1 152 168 ------ ------------ DA#4 8 Reservoir(i) 0.000 1 340 0 6 4973.85 332 DA#3 to bioswale/Dry 9 Reservoir 0.000 1 219 0 7 4975.80 122 DA#4 to Rain Garden 10 Combine 0.105 1 151 524 2, 4, 5, 8, 9 ------------ <no description> 11 Reservoir 0.000 1 262 0 10 4973.31 430 Final Rain Garden 12 SCS Runoff 0.021 2 360 117 ------ ------------ EXISTING - E1 13 SCS Runoff 0.237 2 722 825 ------ ------------ EXISTING - E2 14 SCS Runoff 0.004 2 360 37 ------ ------------ DA#6 15 Reservoir 0.000 2 280 0 14 5975.21 25.5 DA#6 to Depressions Cohousing_Final Calcs_03-04-21.gpw Return Period: 5 Year Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 STORAGEELEVATION5-YEAR PEAKDISCHARGE Hydrograph Summary Report 59 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 0.297 1 146 1,210 ------ ------------ DA #2 2 Reservoir 0.000 1 529 0 1 4972.47 604 DA#2 Infil. Gallery 3 SCS Runoff 0.039 1 152 210 ------ ------------ DA#1 4 Reservoir 0.000 1 166 0 3 4976.23 69.4 DA#1 to Cobble Stream 5 SCS Runoff 0.149 1 151 704 ------ ------------ DA#5 6 SCS Runoff 0.142 1 152 727 ------ ------------ DA#3 7 SCS Runoff 0.046 1 152 234 ------ ------------ DA#4 8 Reservoir(i) 0.000 1 262 0 6 4973.91 405 DA#3 to bioswale/Dry 9 Reservoir 0.000 1 184 0 7 4975.99 177 DA#4 to Rain Garden 10 Combine 0.149 1 151 704 2, 4, 5, 8, 9 ------------ <no description> 11 Reservoir 0.000 1 203 0 10 4973.61 592 Final Rain Garden 12 SCS Runoff 0.037 2 360 300 ------ ------------ EXISTING - E1 13 SCS Runoff 0.430 2 720 1,231 ------ ------------ EXISTING - E2 14 SCS Runoff 0.006 2 360 70 ------ ------------ DA#6 15 Reservoir 0.000 2 222 0 14 5975.36 48.4 DA#6 to Depressions Cohousing_Final Calcs_03-04-21.gpw Return Period: 10 Year Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 STORAGEELEVATION10-YEAR PEAKDISCHARGE Hydrograph Summary Report 75 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 0.381 1 145 1,536 ------ ------------ DA #2 2 Reservoir 0.000 1 647 0 1 4973.67 904 DA#2 Infil. Gallery 3 SCS Runoff 0.062 1 151 308 ------ ------------ DA#1 4 Reservoir 0.000 1 176 0 3 4976.36 108 DA#1 to Cobble Stream 5 SCS Runoff 0.216 1 147 975 ------ ------------ DA#5 6 SCS Runoff 0.219 1 151 1,045 ------ ------------ DA#3 7 SCS Runoff 0.070 1 151 336 ------ ------------ DA#4 8 Reservoir(i) 0.000 1 188 0 6 4973.97 624 DA#3 to bioswale/Dry 9 Reservoir 0.000 1 244 0 7 4976.25 264 DA#4 to Rain Garden 10 Combine 0.216 1 147 975 2, 4, 5, 8, 9 ------------ <no description> 11 Reservoir 0.000 1 363 0 10 4974.00 838 Final Rain Garden 12 SCS Runoff 0.062 2 360 668 ------ ------------ EXISTING - E1 13 SCS Runoff 0.744 2 720 1,892 ------ ------------ EXISTING - E2 14 SCS Runoff 0.011 2 154 128 ------ ------------ DA#6 15 Reservoir 0.000 2 370 0 14 5975.60 94.6 DA#6 to Depressions Cohousing_Final Calcs_03-04-21.gpw Return Period: 25 Year Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 STORAGEELEVATION25-YEAR PEAKDISCHARGE Hydrograph Summary Report 91 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 0.503 1 145 2,014 ------ ------------ DA #2 2 Reservoir 0.000 1 130 0 1 4975.48 1,359 DA#2 Infil. Gallery 3 SCS Runoff 0.100 1 151 465 ------ ------------ DA#1 4 Reservoir 0.000 1 531 0 3 4976.81 247 DA#1 to Cobble Stream 5 SCS Runoff 0.325 1 146 1,397 ------ ------------ DA#5 6 SCS Runoff 0.343 1 147 1,550 ------ ------------ DA#3 7 SCS Runoff 0.110 1 147 499 ------ ------------ DA#4 8 Reservoir(i) 0.000 1 770 0 6 4974.50 1,040 DA#3 to bioswale/Dry 9 Reservoir 0.014 1 329 39 7 4976.51 369 DA#4 to Rain Garden 10 Combine 0.325 1 146 1,544 2, 4, 5, 8, 9 ------------ <no description> 11 Reservoir 0.000 1 240 0 10 4974.67 1,370 Final Rain Garden 12 SCS Runoff 0.114 2 216 1,388 ------ ------------ EXISTING - E1 13 SCS Runoff 1.318 2 720 3,127 ------ ------------ EXISTING - E2 14 SCS Runoff 0.036 2 152 232 ------ ------------ DA#6 15 Reservoir 0.000 2 690 0 14 5975.94 183 DA#6 to Depressions Cohousing_Final Calcs_03-04-21.gpw Return Period: 100 Year Monday, 03 / 8 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 STORAGEELEVATION100-YEAR PEAKDISCHARGE BOZEMAN COHOUSING Stormwater Drainage Plan   25-YEAR STORAGE-INFILTRATION ANALYSIS Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 4 DA#1 to Cobble Stream Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 176 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 3 - DA#1 Max. Elevation = 4976.36 ft Reservoir name = DA#1 Cobble Stream Gallery Max. Storage = 108 cuft Storage Indication method used. Exfiltration extracted from Outflow. 79 0 60 120 180 240 300 360 420 480 540 600 Q (cfs) 0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05 0.05 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.10 Q (cfs) Time (min) DA#1 to Cobble Stream Hyd. No. 4 -- 25 Year Hyd No. 4 Hyd No. 3 Total storage used = 108 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 2 DA#2 Infil. Gallery Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 647 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 1 - DA #2 Max. Elevation = 4973.67 ft Reservoir name = DA#2 Rain Garden Infiltration GalleryMax. Storage = 904 cuft Storage Indication method used. Exfiltration extracted from Outflow. 77 0 60 120 180 240 300 360 420 480 540 600 660 720 780 840 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) DA#2 Infil. Gallery Hyd. No. 2 -- 25 Year Hyd No. 2 Hyd No. 1 Total storage used = 904 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 8 DA#3 to bioswale/Dry Hydrograph type = Reservoir (Interconnected) Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 188 min Time interval = 1 min Hyd. volume = 0 cuft Upper Pond Lower PondPond name = DA#3 Bioswale Pond name = DA#3 Dry Well w/ Pipe T Inflow hyd. = 6 - DA#3 Other Inflow hyd. = None Max. Elevation = 4973.97 ft Max. Elevation = 4970.36 ft Max. Storage = 341 cuft Max. Storage = 283 cuft Interconnected Pond Routing. Storage Indication method used. Exfiltration extracted from Outflow. 83 0 60 120 180 240 300 360 420 480 540 600 660 720 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) DA#3 to bioswale/Dry Hyd. No. 8 -- 25 Year Hyd No. 8 Hyd No. 6 Total storage used = 624 cuft Outflow Pond 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 9 DA#4 to Rain Garden Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 244 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 7 - DA#4 Max. Elevation = 4976.25 ft Reservoir name = DA#4 Rain Garden Max. Storage = 264 cuft Storage Indication method used. Exfiltration extracted from Outflow. 84 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05 0.05 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.10 Q (cfs) Time (min) DA#4 to Rain Garden Hyd. No. 9 -- 25 Year Hyd No. 9 Hyd No. 7 Total storage used = 264 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 11 Final Rain Garden Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 363 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 10 - <no description> Max. Elevation = 4974.00 ft Reservoir name = DA#5 Rain Garden Max. Storage = 838 cuft Storage Indication method used. Exfiltration extracted from Outflow. 86 0 240 480 720 960 1200 1440 1680 1920 2160 2400 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) Final Rain Garden Hyd. No. 11 -- 25 Year Hyd No. 11 Hyd No. 10 Total storage used = 838 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 15 DA#6 to Depressions Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 25 yrs Time to peak = 370 min Time interval = 2 min Hyd. volume = 0 cuft Inflow hyd. No. = 14 - DA#6 Max. Elevation = 5975.60 ft Reservoir name = DA#6 Depressional Areas Max. Storage = 95 cuft Storage Indication method used. Exfiltration extracted from Outflow. 90 0 120 240 360 480 600 720 840 960 Q (cfs) 0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05 0.05 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.10 Q (cfs) Time (min) DA#6 to Depressions Hyd. No. 15 -- 25 Year Hyd No. 15 Hyd No. 14 Total storage used = 95 cuft BOZEMAN COHOUSING Stormwater Drainage Plan   100-YEAR STORAGE-INFILTRATION ANALYSIS Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 4 DA#1 to Cobble Stream Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 100 yrs Time to peak = 531 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 3 - DA#1 Max. Elevation = 4976.81 ft Reservoir name = DA#1 Cobble Stream Gallery Max. Storage = 247 cuft Storage Indication method used. Exfiltration extracted from Outflow. 95 0 60 120 180 240 300 360 420 480 540 600 660 720 780 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) DA#1 to Cobble Stream Hyd. No. 4 -- 100 Year Hyd No. 4 Hyd No. 3 Total storage used = 247 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 2 DA#2 Infil. Gallery Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 100 yrs Time to peak = 130 min Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 1 - DA #2 Max. Elevation = 4975.48 ft Reservoir name = DA#2 Rain Garden Infiltration GalleryMax. Storage = 1,359 cuft Storage Indication method used. Exfiltration extracted from Outflow. 93 0 120 240 360 480 600 720 840 960 1080 Q (cfs) 0.00 0.00 0.10 0.10 0.20 0.20 0.30 0.30 0.40 0.40 0.50 0.50 0.60 0.60 0.70 0.70 0.80 0.80 0.90 0.90 1.00 1.00 Q (cfs) Time (min) DA#2 Infil. Gallery Hyd. No. 2 -- 100 Year Hyd No. 2 Hyd No. 1 Total storage used = 1,359 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 8 DA#3 to bioswale/Dry Hydrograph type = Reservoir (Interconnected) Peak discharge = 0.000 cfs Storm frequency = 100 yrs Time to peak = 770 min Time interval = 1 min Hyd. volume = 0 cuft Upper Pond Lower PondPond name = DA#3 Bioswale Pond name = DA#3 Dry Well w/ Pipe T Inflow hyd. = 6 - DA#3 Other Inflow hyd. = None Max. Elevation = 4974.50 ft Max. Elevation = 4973.76 ft Max. Storage = 456 cuft Max. Storage = 584 cuft Interconnected Pond Routing. Storage Indication method used. Exfiltration extracted from Outflow. 99 0 120 240 360 480 600 720 840 960 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) DA#3 to bioswale/Dry Hyd. No. 8 -- 100 Year Hyd No. 8 Hyd No. 6 Total storage used = 1,040 cuft Outflow Pond 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 9 DA#4 to Rain Garden Hydrograph type = Reservoir Peak discharge = 0.014 cfs Storm frequency = 100 yrs Time to peak = 329 min Time interval = 1 min Hyd. volume = 39 cuft Inflow hyd. No. = 7 - DA#4 Max. Elevation = 4976.51 ft Reservoir name = DA#4 Rain Garden Max. Storage = 369 cuft Storage Indication method used. Exfiltration extracted from Outflow. 100 0 60 120 180 240 300 360 420 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) DA#4 to Rain Garden Hyd. No. 9 -- 100 Year Hyd No. 9 Hyd No. 7 Total storage used = 369 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Tuesday, 06 / 29 / 2021 Hyd. No. 11 Final Rain Garden Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 100 yrs Time to peak = 5.07 hrs Time interval = 1 min Hyd. volume = 0 cuft Inflow hyd. No. = 10 - <no description> Max. Elevation = 4974.19 ft Reservoir name = DA#5 Rain Garden w/ Drywell Max. Storage = 1,161 cuft Storage Indication method used. Exfiltration extracted from Outflow. 0 3 6 9 12 15 18 21 24 27 30 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (hrs) Final Rain Garden Hyd. No. 11 -- 100 Year Hyd No. 11 Hyd No. 10 Total storage used = 1,161 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 03 / 8 / 2021 Hyd. No. 15 DA#6 to Depressions Hydrograph type = Reservoir Peak discharge = 0.000 cfs Storm frequency = 100 yrs Time to peak = 690 min Time interval = 2 min Hyd. volume = 0 cuft Inflow hyd. No. = 14 - DA#6 Max. Elevation = 5975.94 ft Reservoir name = DA#6 Depressional Areas Max. Storage = 183 cuft Storage Indication method used. Exfiltration extracted from Outflow. 106 0 120 240 360 480 600 720 840 960 1080 1200 1320 Q (cfs) 0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05 0.05 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.10 Q (cfs) Time (min) DA#6 to Depressions Hyd. No. 15 -- 100 Year Hyd No. 15 Hyd No. 14 Total storage used = 183 cuft BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX E STORMWATER PLAN SHEETS   DNUPUP UPUP WAGON WHEEL RD WGMGROUPWWW.WGMGROUP.COMSTORMWATER COVER SHEET BOZEMAN COHOUSING BOZEMAN, MTJune 24, 2021S1.0PERMIT SET T.H.3/1.5 - AT.H.3/2 - AT.H.2/2 - AF.e.3/2F.e.2/1COMMONHOUSECOMMONAMENITIESATRIUMT.H.2/1.5 - A1 CARGARAGE1 CARGARAGEDNUPUPUPT.H.3/2T.H.3/2F.i.2/1T.H.3/2 T.H.3/2 F.i.2/1 T.H.3/2 T.H.3/2 F.i.2/1 WGMGROUPWWW.WGMGROUP.COMSTORMWATER PLAN BOZEMAN COHOUSING BOZEMAN, MTJune 24, 2021S1.1PERMIT SET····· T.H.3/1.5 - AF.e.3/2COMMONAMENITIEST.H.2/1.5 - AUPT.H.3/2F.i.2/1T.H.2/1.5T.H.3/2F.i.2/1T.H.2/1.5T.H.3/2 F.i.2/1 T.H.2/1.5 T.H.3/2 F.i.2/1 T.H.2/1.5 F.e .2/1F .e .3/2F.e.2/1F.e.3/2WGMGROUPWWW.WGMGROUP.COMSTORMWATER PLAN BOZEMAN COHOUSING BOZEMAN, MTJune 24, 2021S1.2PERMIT SET··········· WGMGROUPWWW.WGMGROUP.COMCOBBLE GALLERY DETAIL BOZEMAN COHOUSING BOZEMAN, MTJune 24, 2021S1.3PERMIT SET WGMGROUPWWW.WGMGROUP.COMSTORMWATER MANAGEMENT DETAILS BOZEMAN COHOUSING BOZEMAN, MTJune 24, 2021S1.4PERMIT SET WGMGROUPWWW.WGMGROUP.COMPLANTING DETAILS BOZEMAN COHOUSING BOZEMAN, MTMarch 4, 2021L1.4PERMIT SETPLOTTED:SAVED:3/4/213/4/21 BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX F LID CONCEPT SITE PLAN RENDERING   Bozeman CohousingConceptual Landscape PlanDecember 19, 20200 15 30 45’SCALE: 1” = 30’ @ 24x36”NORTH BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX G HYDRAULIC CONVEYANCE ANALYSIS   BOZEMAN COHOUSING Stormwater Drainage Plan   APPENDIX H STORMWATER SYSTEM OPERATION AND MAINTENANCE PLAN   1 BOZEMAN COHOUSING Stormwater System Operation and Maintenance Plan   STORMWATER OPERATION & MAINTENANCE PLAN PURPOSE Stormwater runoff is a significant source of water pollution in urbanizing areas. In addition, increasing impervious area causes increased runoff flow rates and runoff volumes discharged to receiving drainageways. The proposed stormwater facilities help mitigate negative effects by providing treatment for pollutant removal as well as storage and infiltration functions to help control release rates downstream. Properly maintained stormwater facilities are effective at removing certain pollutants and providing necessary management of stormwater volumes during larger storm events. Improperly maintained facilities can increase the discharge of pollutants downstream, increase the risk of flooding downstream, increase the instability of downstream channels, and lead to aesthetic and nuisance problems. Studies show that poor operation and maintenance is the leading cause of facility failure. Poor maintenance of the stormwater facilities can also create unpleasant odors, nuisance insects, and a generally unsightly, unkempt appearance. Failure can be caused by:  poor maintenance in relation to sediment and debris removal,  clogged inlets resulting from sediment accumulation or trash and debris,  inadequate access for routine maintenance activities. Proper maintenance and knowing the functionality of the facilities and the importance of all the system components reduces the chance of flooding and stormwater management deficiencies. STORMWATER SYSTEM OVERVIEW The stormwater features used at this site are: catch basins, stormwater conveyance pipes, cobble bed conveyance channels (ditches), culverts, rain gardens, drywell structures, and underground stormwater infiltration facilities, and outflow control structures. In combination with each other, the site’s stormwater facilities have the following general objectives:  Efficient internal conveyance of stormwater runoff to final infiltration and treatment facilities.  Treatment and infiltration of runoff to improve water quality.  Protection of the downstream (i.e. offsite) drainage system through reduction of runoff peak flow rates and volumes via storage and infiltration. Properly functioning stormwater features reduce flood damage risk, protect downstream drainageways, and enhance water quality of discharges to receiving water bodies. The stormwater facility owner must understand the importance of the designated onsite 2 BOZEMAN COHOUSING Stormwater System Operation and Maintenance Plan   stormwater facilities and the obligation to assure their continued proper function. This Stormwater System Operation and Maintenance Plan will provide the information needed to operate a fully functional stormwater treatment facility on the property. RESPOSIBILITY TO MAINTAIN Designation of a responsible party is important to assure proper operation of your stormwater detention and control features. In this instance it is a responsibility of the property owner for the correct operation and proper maintenance of the facilities. The City of Bozeman Public Works Department is not responsible for the maintenance of these facilities or their structural components, including the water quality devices, flow control structures, and outlet pipes. However, the City of Bozeman Public Works Department does have the authority to inspect and review maintenance activities to ensure the viability of your facilities. RECOMMENDED MAINTENANCE Each onsite stormwater facility will have unique requirements for maintenance activities and intervals. The facility size, type and characteristics of the tributary area, and facility location will all influence maintenance requirements. This section outlines suggested maintenance activities, intervals, and procedures for the stormwater system. The site’s maintenance program should be adjusted as necessary to keep the stormwater system functioning properly.  Regular maintenance activities should focus on the care of upstream pre-treatment facilities (i.e. catch basins and rain gardens) to protect the viability of larger downstream treatment features. This maintenance includes seasonal removal of any trash, debris, and sediment that accumulates within pipes, catch basins, curb and gutters, drywells, and rain gardens. Excessive accumulations of trash, debris, and sediment may cause clogging in the system and result in reduced lifespan of infiltration facilities, overflow and flooding, and damage risk to nearby structures.  Inlet grates should remain free of obstructions to flow from debris. Clogged inlets can lead to flooding risk and damage to onsite and offsite structures. Inlet grates are particularly prone to clogging from leaf litter in the fall and from road sanding/de- icing material in the spring.  Keeping underground infiltration facilities and drywells clear of accumulating sediment and debris is critical for their proper function and lifespan. If the underlying gravel pack and soils become clogged with fine sediments, the cobble galleries and drywells will not function as designed and may require complete replacement. Drywells should be inspected frequently and cleaned as necessary via hydraulic vacuum truck. Routine Maintenance (seasonally to bi-annually): 1) Inspections: Scheduled inspections with a specified checklist should be performed during the year. Inspections after major rainfall events are also recommended to check for obstructions or damage and to remove debris/trash. Example inspection checklists are included as an attachment to this plan for reference purposes that 3 BOZEMAN COHOUSING Stormwater System Operation and Maintenance Plan   can be customized to project specific infrastructure. DO NOT ENTER confined spaces such as manholes and underground infiltration facilities for inspections. These facilities should be inspected from the surface. 2) Vegetation Management: When mowing, collect grass clippings and all other clippings/trimmings and take offsite for disposal or dispose in trash on site. Do not leave clippings in an area that will clog catch basin inlet grates and French drains. This includes removing clippings from roadside ditches that are throughout the development. Removing clippings, leaf litter, and sediment from the cobble drainage channels is necessary to sustain infiltration capabilities. Channel cobble should be open to the surface and should never be covered with mulch or sod. Limit the use of fertilizers and pesticides around channels and rain gardens to minimize entry into subsequent downstream waters. 3) Trash, Debris and Litter Removal: Removal of any trash, etc. causing any obstructions to the stormwater facilities during periodic inspections and especially after every significant runoff event. In general, pick up trash, etc. in and around the facilities during all inspections. Inspect all catch basins and drywell structures and clean floating debris as necessary. 4) Parking Lot Sweeping: Each parking lot is recommended to be swept on an annual basis in the spring to reduce the winter traction sands, de-icing materials, and sediment that would otherwise be washed into the stormwater system during runoff events. Sweeping via vacuum broom truck is the preferred alternative so that fine sediments are fully removed from the site. 5) Structural Component Check: Perform structural inspection of catch basins, drywells, inlets, grates, pipes, and culverts on a regular basis for potential additions to the Non-routine Maintenance list. Non-Routine Maintenance includes (annually to 5 years): 1) Sediment Removal: Accumulated sediment in the bottom of catch basins, drywells, and rain gardens may need to be removed as frequently as once annually. Sediment removal in the drywell should be performed at frequencies of approximately once every three to five years, or as necessary, to ensure that sediment depth or debris accumulation in the bottom at any location does not exceed twelve inches. Sediment removal in the rain garden bioretention areas may be required every 3 to 5 years to ensure that vegetation is not ‘smothered’ and underlying soils are not clogged with fine sediments. 2) Structural Repair/Replacement: Eventually structural components may need to be repaired or replaced to ensure proper function. Monitor metal structures for excessive rust and corrosion. Monitor concrete structures for large cracking and/or spalling. Repair and replace as necessary. BOZEMAN COHOUSING Stormwater System Operation and Maintenance Plan   EXAMPLE INSPECTION CHECKLISTS Closed Detention & Infiltration Systems Date Inspected _________ (Tanks/Vaults/Drywells) Drainage  System  Feature  Potential  Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is  Performed Or Not Needed   Plugged Air  Vents  One‐half of the cross section of a vent is  blocked at any point or the vent is  damaged.  Vents open and functioning.   Accumulated sediment depth exceeds 10%  of the diameter of the storage area for 1/2  length of storage vault or any point depth  exceeds 15% of diameter.     Debris and  Sediment (Example: 72‐inch storage tank would  require cleaning when sediment reaches  depth of seven inches for more than 1/2  length of tank).  Remove all sediment and debris from  storage area.    Any openings or voids allowing material to  be transported into facility. Joints Between  Tank/Pipe  Section (Will require engineering analysis to  determine structural stability).  Seal all joint between tank/pipe sections.   Tank Pipe Bent  Out of Shape  Any part of tank/pipe is bent out of shape  more than 10% of its design shape. (Review  required by engineer to determine  structural stability).  Repair tank/pipe or replace to design.   Cracks wider than 1/2‐inch and any  evidence of soil particles entering the  structure through the cracks, or  maintenance/inspection personnel  determines that the vault is not structurally  sound.  Replace vault or repair to design  specifications and is structurally sound.   Storage  Area  Vault Structure  Includes Cracks  in Wall,  Bottom,  Damage to  Frame and/or  Top Slab  Cracks wider than 1/2‐inch at the joint of  any inlet/outlet pipe or any evidence of soil  particles entering the vault through the  walls.  No cracks more than 1/4 inch wide at the  joint of the inlet/outlet pipe.   Cover Not in  Place  Cover is missing or only partially in place.  Any open manhole requires maintenance. Manhole is closed.   Locking  Mechanism Not  Working  Mechanism cannot be opened by one  maintenance person with proper tools.  Bolts into frame have less than 1/2 inch of  thread (may not apply to self‐locking lids).   Mechanism opens with proper tools.   Cover Difficult  to Remove  One maintenance person cannot remove  lid after applying normal lifting pressure.  Intent is to keep cover from sealing off  access to maintenance.  Cover can be removed and reinstalled by  one maintenance person.   Manhole  Ladder Rungs  Unsafe  Ladder is unsafe due to missing rungs,  misalignment, not securely attached to  structure wall, rust, or cracks.  Ladder meets design standards. Allows  maintenance person safe access.   General Trash and  Debris   Trash or debris which is located  immediately in front of the catch basin  opening or is blocking inletting capacity of  the basin by more than 10%.  No trash or debris located immediately in  front of catch basin or on grate opening.  Drainage  System  Feature  Potential  Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is  Performed Or Not Needed   Trash or debris (in the basin) that exceeds  60% of the sump depth as measured from  the bottom of basin to invert of the lowest  pipe into or out of the basin, but in no case  less than a minimum of six inches clearance  from the debris surface to the invert of the  lowest pipe.  No trash or debris in the catch basin.   Trash or debris in any inlet or outlet pipe  blocking more than 1/3 of its height.  Inlet and outlet pipes free of trash or  debris.   Trash and  Debris  Dead animals or vegetation that could  generate odors that could cause  complaints or dangerous gases (e.g.,  methane).  No dead animals or vegetation present  within the catch basin.   Sediment  Sediment (in the basin) that exceeds 60%  of the sump depth as measured from the  bottom of basin to invert of the lowest pipe  into or out of the basin, but in no case less  than a minimum of six inches of clearance  from the sediment surface to the invert of  the lowest pipe.  No sediment in the catch basin.   Top slab has holes larger than two square  inches or cracks wider than 1/4 inch (Intent  is to make sure no material is running into  basin).  Top slab is free of holes and cracks.  Structure  Damage to  Frame and/or  Top Slab  Frame not sitting flush on top slab, i.e.,  separation of more than 3/4 inch of the  frame from the top slab. Frame not  securely attached.  Frame is sitting flush on the riser rings or  top slab and firmly attached.   Maintenance person judges that structure  is unsound.  Basin replaced or repaired to design  standards.   Fractures or  Cracks in Basin  Walls/ Bottom  Grout fillet has separated or cracked wider  than 1/2 inch and longer than one foot at  the joint of any inlet/outlet pipe or any  evidence of soil particles entering catch  basin through cracks.  Pipe is regrouted and secure at basin wall.   Settlement/  Misalignment  If failure of basin has created a safety,  function, or design problem.  Basin replaced or repaired to design  standards.   Vegetation growing across and blocking  more than 10% of the basin opening. No vegetation blocking opening to basin.   Vegetation Vegetation growing in inlet/outlet pipe  joints that is more than six inches tall and  less than six inches apart.  No vegetation or root growth present.   General  Contaminants  and Pollution  Any evidence of oil, gasoline, contaminants  or other pollutants (Coordinate  removal/cleanup with local water quality  response agency).   No contaminants or pollutants present.   Catch Basins Date Inspected_________ Drainage  System  Feature  Potential  Defect  Conditions When Maintenance Is  Needed  Results Expected When Maintenance Is  Performed Or Not Needed   Trash or debris which is located immediately  in front of the catch basin opening or is  blocking inletting capacity of the basin by  more than 10%.  No trash or debris located immediately in  front of catch basin or on grate opening.  Trash or debris (in the basin) that exceeds 60%  of the sump depth as measured from the  bottom of basin to invert of the lowest pipe  into or out of the basin, but in no case less  than a minimum of six inches clearance from  the debris surface to the invert of the lowest  pipe.  No trash or debris in the catch basin.  Trash or debris in any inlet or outlet pipe  blocking more than 1/3 of its height. Inlet and outlet pipes free of trash or debris.  Trash and Debris   Dead animals or vegetation that could  generate odors that could cause complaints or  dangerous gases (e.g., methane).  No dead animals or vegetation present within  the catch basin.  Sediment  Sediment (in the basin) that exceeds 60% of  the sump depth as measured from the bottom  of basin to invert of the lowest pipe into or out  of the basin, but in no case less than a  minimum of six inches of clearance from the  sediment surface to the invert of the lowest  pipe.  No sediment in the catch basin.  Top slab has holes larger than two square  inches or cracks wider than 1/4 inch     (Intent is to make sure no material is running  into basin).  Top slab is free of holes and cracks.  Structure  Damage to  Frame and/or  Top Slab Frame not sitting flush on top slab, i.e.,  separation of more than 3/4 inch of the frame  from the top slab. Frame not securely  attached.  Frame is sitting flush on the riser rings or top  slab and firmly attached.  Maintenance person judges that structure is  unsound. Replace basin or repair to design standards.  Fractures or  Cracks in Basin  Walls/ Bottom  Grout fillet has separated or cracked wider  than 1/2 inch and longer than one foot at the  joint of any inlet/outlet pipe or any evidence  of soil particles entering catch basin through  cracks.  Regrout pipe and secure at basin wall.  Settlement/  Misalignment  If failure of basin has created a safety,  function, or design problem.  Replace basin or repair to design standards.  Vegetation growing across and blocking more  than 10% of the basin opening. No vegetation blocking opening to basin.  Vegetation Vegetation growing in inlet/outlet pipe joints  that is more than six inches tall and less than  six inches apart.  No vegetation or root growth present.  General  Contaminants  and Pollution  Any evidence of oil, gasoline, contaminants or  other pollutants (Coordinate removal/cleanup  with local water quality response agency).  No contaminants or pollutants present.   Drainage  System  Feature  Potential  Defect  Conditions When Maintenance Is  Needed  Results Expected When Maintenance Is  Performed Or Not Needed   Cover Not in  Place  Cover is missing or only partially in place. Any  open catch basin requires maintenance. Catch basin cover is closed.  Locking  Mechanism Not  Working  Mechanism cannot be opened by one  maintenance person with proper tools. Bolts  into frame have less than 1/2 inch of thread.  Mechanism opens with proper tools.  Catch  Basin  Cover  Cover Difficult to  Remove  One maintenance person cannot remove lid  after applying normal lifting pressure (Intent is  to keep cover from sealing off access to  maintenance).  Cover can be removed by one maintenance  person.  Ladder Ladder Rungs  Unsafe  Ladder is unsafe due to missing rungs, not  securely attached to basin wall, misalignment,  rust, cracks, or sharp edges.  Ladder meets design standards and allows  maintenance person safe access.  Grate Opening  Unsafe Grate with opening wider than 7/8 inch. Grate opening meets design standards.  Trash and Debris Trash and debris that is blocking more than  20% of grate surface inletting capacity. Grate free of trash and debris.  Metal  Grates (If  Applicable)  Damaged or  Missing  Grate missing or broken member(s) of the  grate. Grate is in place and meets design standards.  Conveyance Storm Pipe Date Inspected_________ Drainage  System  Feature  Potential  Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is  Performed Or Not Needed   Obstructions,  Including Roots Root enters or deforms pipe, reducing flow. Use mechanical methods to remove root.  Do not put root‐dissolving chemicals in  storm sewer pipes. If necessary, remove  the vegetation over the line.    Pipe Dented or  Broken  Inlet/outlet piping damaged or broken and  in need of repair. Pipe repaired and/or replaced.   Pipe Rusted or  Deteriorated   Any part of the piping that is crushed or  deformed more than 20% or any other  failure to the piping.  Pipe repaired and/or replaced.   Sediment &  Debris  Sediment depth is greater than 20% of pipe  diameter.  Install upstream debris traps (where  applicable) then clean pipe and remove  material.    General  Debris barrier or  Trash Rack  Missing  Stormwater pipes > than 18 inches need  debris barrier.  Debris barrier present on all stormwater  pipes 18 inches and greater. 