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HomeMy WebLinkAbout010 - Stormwater ReportSTORMWATER DRAINAGE REPORT Whitefish Credit Union – Bozeman Branch Planning Application # PLNAPP-18466 Lot 2A -1 of Minor Subdivision 503C Bozeman, MT 59715 Prepared For: Whitefish Credit Union 300 Baver Avenue Whitefish, MT 59937 Prepared By: Cushing Terrell 411 East Main Street, Suite 101 Bozeman, MT 59715 406.922.7111 www.cushingterrell.com Cushing Terrell Project No. WFCU_BOZ April 30, 2026 Adam Schlegel, PE Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell i TABLE OF CONTENTS 1.0 INTRODUCTION ............................................................................................................................... 3 1.1 Description of Property............................................................................................................. 3 1.1.1 Location ................................................................................................................................... 3 1.1.2 Existing Land Use and Ground Cover ........................................................................... 3 1.1.3 Topographic Features and Slopes.................................................................................. 4 1.1.4 FEMA Floodplain Classification ....................................................................................... 4 1.1.5 Natural Watercourse, Major Drainage Ways and Receiving Channels ............. 4 1.1.6 Existing Drainage Facilities ............................................................................................... 4 1.1.7 Wetlands.................................................................................................................................. 4 1.1.8 Geologic Features and Geotechnical Data .................................................................. 4 1.1.8.1 Soils ........................................................................................................................................... 4 1.1.8.2 Groundwater .......................................................................................................................... 4 1.2 Previous Drainage Study .......................................................................................................... 5 2.0 STORM DRAINAGE DESIGN ......................................................................................................... 5 2.1 Hydrology & Hydrogeology ................................................................................................... 5 2.1.1 Design Storm Rainfall ......................................................................................................... 5 2.1.2 Geotechnical Evaluation .................................................................................................... 5 2.2 Methodology ................................................................................................................................ 6 2.3 Pre-Development Conditions ................................................................................................. 6 2.4 Post-Development Conditions ............................................................................................... 7 2.5 Post-Development Conveyance ............................................................................................ 7 2.6 Post-Development Water Quality Design .......................................................................... 7 2.7 Post-Development Stormwater Management ................................................................. 8 2.8 Drain-down time ......................................................................................................................... 8 2.9 Depth to Groundwater……..……………..…………………………………………………………………8 3.0 CONCLUSION ................................................................................................................................... 9 LIST OF TABLES Table 2.1: Pre-Development Basin .......................................................................................................... 6 Table 2.2: Pre-Development Total Runoff Volume (10-yr/2-hr Storm) ..................................... 6 Table 2.3: Post-Development Basins ...................................................................................................... 7 Table 2.4: Post-Development Total Runoff Volume (10-yr/2-hr Storm) ................................... 7 Table 2.4: Water Quality Volume Calculations ................................................................................... 7 Table 2.6: Storm Facility Data ................................................................................................................... 8 Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell ii APPENDICES APPENDIX A: Geotechnical Engineering Report APPENDIX B: Storm Drainage Exhibits APPENDIX C: Post Development Calculations APPENDIX D: FEMA Flood Map APPENDIX E: NRCS Soils APPENDIX F: Subdivision Storm Information Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 3 1.0 INTRODUCTION The purpose of this report is to address the proposed stormwater facilities for the Whitefish Credit Union Bozeman project consisting of a new building (approximately 6,500 square feet footprint), drive-thru, landscaping, and parking area (approximately 1.262 acres total). There are no existing buildings on site and the site is vacant with the exception of an existing shared access along the west side of the property, an irrigation well in an existing island, and shared parking on the south of the property. Common street address has not yet been determined. 1.1 Description of Property 1.1.1 Location This property is located at the following legal address: Lots 2A-1 of Minor Subdivision 503C This property, located with the limits of the City of Bozeman, is zoned B-2 Community Business. Figure 1: Location Map 1.1.2 Existing Land Use and Ground Cover Existing ground cover and vegetation consists of native grasses with minimal topsoil with gravel trail along the east side. The west and south side of the site is bound by existing curb and pavement. Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 4 1.1.3 Topographic Features and Slopes The natural grade of the existing site is generally from south to north/northeast at approximately 1.2% slope. The elevation change across the entire site is 4’±. 1.1.4 FEMA Floodplain Classification The project boundary is within Zone X as shown on FEMA Flood Panel 30031C0812D 1.1.5 Natural Watercourse, Major Drainage Ways and Receiving Channels There are no natural watercourses, major drainage ways or receiving channels on this site. 1.1.6 Existing Drainage Facilities University Crossings Minor Subdivision 503 has an existing detention pond which manages the stormwater runoff from the existing shared access and pavement on the site, as well as all the runoff from the property to the south. However, this pond does not have capacity for the developed parcel in its entirety. Therefore, the proposed site development will be required to manage stormwater on-site. 1.1.7 Wetlands Wetlands are not anticipated within or adjacent to the property. 1.1.8 Geologic Features and Geotechnical Data A geotechnical site investigation was performed as part of this project and has been included in Appendix A of this report. 1.1.8.1 Soils 4 soil borings were conducted throughout the subject property, and the soil profile was relatively consistent throughout. The soils observed include an approximately 3’ layer of topsoil over with “lean clay with varying amounts of gravel in all borings” which was found to a depth of approximately 3 to 5 feet below the ground surface, underlain with clayey gravel with sand. 1.1.8.2 Groundwater Groundwater was observed in all of the soil boring locations between approximately 10 to 13 feet below the ground surface. Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 5 1.2 Previous Drainage Study The University Crossings Minor Subdivision 503 prepared a Stormwater Management Design Report prepared by C&H Engineering and Surveying Inc. dated April 2022. 2.0 STORM DRAINAGE DESIGN Storm drainage was designed in accordance with the City of Bozeman Design and Construction Standards October 2024 (COBDSC). In general, the proposed developed site will incorporate 1 infiltration facilities for stormwater management. 2.1 Hydrology & Hydrogeology 2.1.1 Design Storm Rainfall The 10-year, and 100-year storm events were used in the evaluations along with the water quality rainfall event (0.5” using 5-min time to concentration). The table below was extracted from COBDCS Table 6.5.2. Precipitation Intensity - Duration Duration (min) 10-year 100-year 5 3.87 6.09 10 2.83 4.45 15 2.29 3.68 20 1.84 2.89 25 1.56 2.46 30 1.38 2.18 35 1.22 1.92 40 0.99 1.72 45 1 1.57 50 0.91 1.44 55 0.84 1.33 60 0.79 1.24 120 0.41 0.61 180 0.29 0.41 360 0.17 0.22 720 0.1 0.14 1440 0.071 0.098 2.1.2 Geotechnical Evaluation See Appendix A for Geotechnical Evaluation. Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 6 2.2 Methodology • Estimation of Runoff Rates: The rational method is used to calculate peak runoff rates for the sizing of storm retention and conveyance facilities. Table 6.6.4 of the COBDCS was utilized for the selection of runoff coefficients. o Open Land: C=0.22 o Paved or other hard surface: C=0.95 • Time of concentration is calculated per the COBDCS and is limited to a minimum of five minutes. • Conveyance: Storm conveyance channels are sized for the 25-year event in accordance with the COBDCS. Additionally, water quality volumes are calculated using the methodology set forth in Sections 3.2 and 3.3 of the Montana Post-Construction Storm Water BMP Design Guidance Manual (MPCSW). 2.3 Pre-Development Conditions See exhibit D.1 in Appendix B for existing stormwater drainage conditions. The developed portions of the site, as well as the parcel to the south, currently drain from south to north towards the existing stormwater detention, designed to the Water Quality Design Volume of 1277cf per the University Crossing Minor Subdivision Stormwater Design Manual in Appendix F. The remainder of the site infiltrates the storm runoff. Table 2.1: Pre-Development Basin HISTORIC BASINS Basin Landscape/ Undeveloped (sf) (C=0.22) Impervious (sf) (C=.95) Total (sf) Total (ac) Weighted Coefficent % Impervious HIST-01 34094 0 34094 0.78 0.22 0% HIST-02 6355 31927 38282 0.88 0.83 83% Table 2.2: Pre-Development Total Runoff Volume (10-yr/2-hr Storm) Total Runoff Volume (10-yr/2-hr storm) BASIN C Area (ac) 2-hr (i) in/hr Q cfs V (cf) HIST-01 0.22 0.78 0.41 0.07 508 HIST-02 0.83 0.88 0.41 0.30 2150 Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 7 2.4 Post-Development Conditions See exhibit D.2 in Appendix B for developed conditions. In general, post-development conditions consist of a proposed building, concrete and asphalt paving, parking lot landscaping, and stormwater management facilities. Table 2.3: Post-Development Basins POST-DEVELOPMENT BASINS Basin Pervious (Landscape/ Undeveloped) (sf) (C=0.22) Impervious (Roof/ Paving) (sf) (C=0.95) Total (sf) Total (ac) Weighted Coefficient % Impervious DEV-01 8706 33919 42626 0.98 0.80 80% DEV-02 5115 29112 34227 0.79 0.84 85% Total: 13822 63031 76853 1.76 0.82 82% 2.5 Post-Development Conveyance Surface drainage, storm inlets, and storm drain piping will be utilized to drain the parking lot and landscaped areas toward the stormwater infiltration facility (see Appendix C for conveyance calculations). Table 2.4: Post-Development Total Runoff Volume (10-yr/2-hr Storm) Total Runoff Volume (10-yr/2-hr storm) BASIN C Area (ac) 2-hr (i) in/hr Q cfs V (cf) DEV-01 0.80 0.98 0.41 0.32 2301 DEV-02 0.84 0.79 0.41 0.27 1940 Total: 0.82 1.76 0.41 0.59 4242 2.6 Post-Development Water Quality Design Stormwater will first be directed toward the treatment row of the subsurface storm chamber system and will serve as the stormwater treatment for first flush and the WQV (0.5”, 24-hour). Table 2.5: Water Quality Volume Calculations Water Quality Volume (WQV) * BASIN Area (ac) P (in) Imperv. Rv WQV (cf) DEV-01 0.98 0.50 0.80 0.77 1361 DEV-02 0.79 0.50 0.85 0.82 1163 * Calculation uses 5-min time of concentration Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 8 2.7 Post-Development Stormwater Management Stormwater in Basin Dev-01 will be infiltrated in a subsurface storm chamber system (see exhibit in Appendix B for location). This system has been sized to manage the Major Storm event (100 year) in accordance with COBDCS. The sizing of the infiltration facilities is based on the geotechnical recommended infiltration rates for the site (4 inches per hour). Isolated areas around the perimeter that consists of landscaping will infiltrate. Stormwater in Basin Dev-02 will infiltrate into the existing stormwater pond northwest of the site through a curb cut. This pond was originally designed for the University Crossing Minor Subdivision Stormwater Design Manual (see Appendix F for basin map) with a Water Quality Design Volume of 1,277 cubic feet. Basin Dev-02 has a water quality design volume of 1,163 cubic feet, which is under the designed capacity of the existing stormwater pond. 2.8 Drain-down time The drain down time for the proposed stormwater infiltration basin is a function of the design infiltration rate and the overall height of the stormwater facility. The designed stormwater infiltration system is comprised of the ADS StormTech Chamber (MC-3500), which has a height of 5.5’ or 66” from top of the cover stone above the chamber to bottom of the drainage rock below the chamber. Using this along with the design infiltration rate results in a drain down time of 16.5 hours after the end of the storm event, meeting the 72-hour maximum drain-down time requirement. 2.9 Depth to Groundwater The proposed storm system elevations have been set such that they are above the expected groundwater elevation. The values in the table below reflect the highest groundwater elevation observed in the locations of the storm facilities. We anticipate that the 2’ minimum groundwater separation requirement will be satisfied. Table 2.6: Storm Facility Data Storm Facility Data Facility Name Required Detention Volume (CF) (see Appendix C) Provided Storage Volume (CF) System Height (in) Drain-down time (hr) Bottom of System Elevation Groundwater Elevation Groundwater Separation (ft) ADS System 3,913 4,392 66 17 4,911.7 4,908.7 3.1 Stormwater Drainage Report Whitefish Credit Union – Bozeman Branch Project No. WFCU_BOZ Cushing Terrell 9 3.0 CONCLUSION In conclusion, with the implementation of stormwater conveyance and infiltration facilities, the proposed developed project site will not increase peak runoff rates and volumes based on the Major Storm event per COBDCS. APPENDIX A: GEOTECHNICAL ENGINEERING REPORT MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA JOB NO. B25-067-001 January 2026 REPORT OF GEOTECHNICAL INVESTIGATION CLIENT ENGINEER Whitefish Credit Union 300 Baker Avenue Whitefish, MT 59937 Craig Nadeau, PE craig.nadeau@tdhengineering.com REPORT OF GEOTECHNICAL INVESTIGATION PROJECT LOCATION WHITEFISH CREDIT UNION – KAGY & SOUTH 19TH BOZEMAN, MONTANA 406.586.0277 tdhengineering.com 234 E. Babcock, Suite 3 Bozeman, MT 59715 WFCU Kagy & South 19th Table of Contents Bozeman, Montana i Table of Contents 1.0 EXECUTIVE SUMMARY ......................................................................................................... 1 2.0 INTRODUCTION ..................................................................................................................... 2 2.1 Purpose and Scope .......................................................................................................... 2 2.2 Project Description ........................................................................................................... 2 3.0 SITE CONDITIONS ................................................................................................................. 3 3.1 Geology and Physiography .............................................................................................. 3 3.1.1 Siesmic Site Class Determination ........................................................................... 4 3.2 Surface Conditions ........................................................................................................... 6 3.3 Subsurface Conditions ..................................................................................................... 6 3.3.1 Soils ......................................................................................................................... 6 3.3.2 Ground Water ......................................................................................................... 7 4.0 ENGINEERING ANALYSIS .................................................................................................... 9 4.1 Introduction ....................................................................................................................... 9 4.2 Site Grading and Excavations.......................................................................................... 9 4.3 Conventional Shallow Foundations ............................................................................... 10 4.4 Foundation and Retaining Walls .................................................................................... 10 4.5 Interior Floor Slabs ......................................................................................................... 11 4.6 Exterior Flatwork ............................................................................................................ 11 4.7 Pavements ..................................................................................................................... 11 4.8 Infiltration Testing Summary .......................................................................................... 12 5.0 RECOMMENDATIONS ......................................................................................................... 13 5.1 Site Grading and Excavations........................................................................................ 13 5.2 Conventional Shallow Foundations ............................................................................... 14 5.3 Foundation Walls............................................................................................................ 15 5.4 Interior Floor Slabs ......................................................................................................... 16 5.5 Exterior Flatwork ............................................................................................................ 17 5.6 Pavements ..................................................................................................................... 17 5.7 Continuing Services ....................................................................................................... 19 6.0 SUMMARY OF FIELD AND LABORATORY STUDIES ....................................................... 21 6.1 Field Explorations ........................................................................................................... 21 6.2 Laboratory Testing ......................................................................................................... 21 7.0 LIMITATIONS ........................................................................................................................ 23 WFCU Kagy & South 19th Appendix Bozeman, Montana ii APPENDIX ♦ Boring Location Map (Figure 1) ♦ Logs of Exploratory Borings (Figures 2 through 5) ♦ Laboratory Test Data (Figures 6 through 11) ♦ Infiltration Test Result (Figure 12) ♦ ASCE Hazards Report (ASCE 7-16, Site Class C) ♦ LTTPBind Online PG Asphalt Binder Analysis Summary ♦ Construction Standard No. 02801-06C ♦ Soil Classification and Sampling Terminology for Engineering Purposes ♦ Classification of Soils for Engineering Purposes WFCU Kagy & South 19th Executive Summary Bozeman, Montana Page 1 GEOTECHNICAL REPORT WHITEFISH CREDIT UNION – KAGY & SOUTH 19TH BOZEMAN, MONTANA 1.0 EXECUTIVE SUMMARY The proposed project is to be located on the southwest corner of the intersection of South 19th Avenue and Kagy Boulevard in Bozeman, Montana. The project includes a three-story branch facility of the Whitefish Credit Union with a footprint of approximately 6,500 square feet and a gross floor area of approximately 15,000 square feet combined over the three floors. The project is anticipated to include subsurface ground water detention systems, asphalt parking lots, and exterior concrete flatwork as part of the overall site development. Construction is anticipated to encounter limited depths of surficial topsoil, fill, and lean clay soils overlying dense native clayey gravel with sand. Similar gravels extend to depths of at least 21.5 feet, the maximum depth investigated. Ground water was observed in all four borings at depths ranging from 11.0 to 13.7 feet below the ground surface at the time of our investigation in October 2025. Installation of ground water monitoring equipment for evaluation of seasonal ground water changes was not included in the scope of work for this project. Geotechnically the site conditions encountered pose no substantial concern for the planned construction. The native gravels encountered on site will be superior bearing strata for foundations, with high allowable capacities and low settlement risk. However, these native gravels contain occasional large cobbles and boulders, which can create stress concentrations on foundations; thus, the inclusion of a cushion gravel course between foundations and the native gravels should be anticipated. Footings bearing on dense native gravel or structural fill extending to native gravel, if warranted, may be designed using a maximum recommended allowable bearing pressure of 4,000 psf and may consider a one-third increase in this design pressure for use in dynamic load cases provided the recommendations included in this report are followed. Detailed recommendations and preparations for shallow foundations are provided in this report. The surface soils above the native gravels exhibited increased variability, with relatively thick topsoil, fill, and moderate to high plasticity clay soils. The primary materials of concern are the existing fill and topsoil materials which are not suitable to remain beneath the structure. The underlying native clays are not considered expansive; thus, these materials may remain in place beneath conventional slab systems provided the minimum base course thickness is used and all existing topsoil or fill materials are removed. However, complete removal of the surface soils down to native gravels should be anticipated for any area intending to utilize thickened slab sections to support wall or column loads. WFCU Kagy & South 19th Introduction Bozeman, Montana Page 2 2.0 INTRODUCTION 2.1 Purpose and Scope This report presents the results of our geotechnical study for the proposed Whitefish Credit Union facility planned for construction on the southwest corner of the intersection of South 19th Avenue and Kagy Boulevard in Bozeman, Montana. The purpose of the geotechnical study is to determine the general surface and subsurface conditions at the proposed site and to develop geotechnical engineering recommendations for support of the proposed structure and design of related facilities. This report describes the field work and laboratory analyses conducted for this project, the surface and subsurface conditions encountered, and presents our recommendations for the proposed foundations and related site development. Our field work included drilling four soil borings within the approximate footprint of the anticipated structure and performing a single percolation test within the anticipated location of the subsurface detention system. Samples were obtained from the borings and returned to our Great Falls laboratory for testing. Laboratory testing was performed on selected soil samples to determine engineering properties of the subsurface materials. The information obtained during our field investigations and laboratory analyses was used to develop recommendations for the design of the proposed foundation system. 2.2 Project Description The proposed project is to be located on the southwest corner of the intersection of South 19th Avenue and Kagy Boulevard in Bozeman, Montana. The project includes a three-story branch facility of the Whitefish Credit Union with a footprint of approximately 6,500 square feet and a gross floor area of approximately 15,000 square feet combined over the three floors. The project is anticipated to include subsurface ground water detention systems, asphalt parking lots, and exterior concrete flatwork as part of the overall site development. Preliminary foundation loads have not been provided at the time of this report for consideration by TD&H Engineering. For the purposes of our analyses, we have assumed that wall loads for the structure will not exceed 5,000 pounds per lineal foot and column loads will be 125 kips or less. If loadings, locations or conditions are significantly different from those described above, we should be notified to reevaluate the recommendations contained in this report. WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 3 3.0 SITE CONDITIONS 3.1 Geology and Physiography According to the geologic map of Montana, the site is geologically characterized as being gravels (Qgr). This formation consists of variable deposits ranging from pebble to boulder size materials which include variable amounts of sand, silt, and clay. They are typically alluvial terrace, abandoned channel and floodplain, remnant alluvial fan, and local glacial outwash deposits. Additional data provided by the geologic map of the Bozeman area suggest the formation described above is overlain by alluvial fan deposits (Qafo) of the Pleistocene epoch. In the region of the site, such materials consist of light brown, gray, and locally reddish gray gravel in a coarse sand and granule matrix. These gravels are known to be locally derived, angular and subangular, with clasts ranging from pebbles to boulders in size. The thickness of these deposits is expected to be a maximum of 150 feet. The site appears to be confined within the alluvial fan deposits; however, the surrounding geology suggests the western portions of the site nearing braid plain alluvium (Qabo) of the Pleistocene epoch. These deposits consist of cobble to boulder size clasts in a matrix of sand, silt, and clay. The rounded to well-rounded clasts are most commonly composed of Archean metamorphic rock, and dark colored volcanic rock, with subordinate Paleozoic limestone and Belt Supergroup metasedimentary rocks. A well in this unit indicates a thickness of 30 feet of alluvium overlying tertiary deposits. Similar conditions have been identified from nearby well logs which suggest gravels extending to depths of at least 60 feet. Geologic Map of Montana, Edition 1.0 (2007) Montana Bureau of Mines & Geology Approximate Site Location WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 4 Geologic Map of the Bozeman Quadrangle, Southwestern Montana (2014) Montana Bureau of Mines & Geology 3.1.1 Siesmic Site Class Determination A geophysical survey was conducted on November 13, 2025, by Craig Nadeau, PE and Colton Shaff, EI of TD&H Engineering. The survey was conducted using a Multi-Channel Analysis of Surface Waves (MASW) wherein 24 vertically polarized and calibrated 4.5-Hz geophones were used to analyze Raleigh Wave propagation across the site. For this study, the geophones were connected via a 24-channel spread cable to a DAQlink 4 MASW Seismograph. The geophones were deployed linearly north to south in the existing grass island within the existing parking lot to the east of the project site on a 7-foot spacing, for a total geophone array length of 161 feet. Each geophone was firmly seated into the soil utilizing a spike connection. Surface waves were generated with a 20-lb sledgehammer impacting a rigid plastic strike plate. The sledgehammer was instrumented and connected to the seismograph via a hammer switch and cable. The acquisition time was set to 4 seconds with a 0.5-millisecond sample interval. Shots were taken at 1, 6, and 12 receiver spacings on each side of the array as well as two intermediate locations within the array at the approximate one-third points. Stacks of 5 shots were recorded and stored for further processing. Data were processed using the ParkSEIS 3.0 Auto automated MASW processing software from Park Seismic, LLC. An overall dispersion image and extracted dispersion curve were generated as shown below. Approximate Site Location WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 5 Subsequently, a one-dimensional shear wave velocity profile was produced through an inversion analysis using the ParkSIES 3.0 software. For this analysis, layer properties were defined using the results of our geotechnical borings and the best available geologic information available. The shear wave velocity profile shown below was determined through this process with the red dots indicating measured values and the blue dots being the results of the modeled dispersion curve. As shown above, the soil profile exhibits a shear wave velocity ranging from approximately 1,000 to 4,000 feet per second within the uppermost 100 feet of the soil profile, used to define the seismic site class of the property. Per ASCE 7-16, seismic site classification is determined based on the average shear wave velocity measured from the ground surface to a depth of 100 feet and only allows the assignment of Site Class A or B to be provided based on direct measurement of shear wave velocity. As shown above, the average shear WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 6 wave velocity in the top 100 feet at this site (Vs100) is estimated to be 2,402 feet per second, as calculated according to the National Eartquake Hazard Reduction Program and ASCE standards. The property is therefore assigned a Seismic Site Classification “C” per ASCE 7-16. Site specific seismic loading and response spectra were obtained for ASCE 7-16 from the web-based Hazard Tool provided by the ASCE (https://ascehazardtool.org/) based on Risk Category III. The appropriate seismic design parameters for the site include site coefficients of 1.227 and 1.5 for Fa and Fv, respectively. The recommended design spectral response accelerations at short periods (SDs) and at 1-second period (SD1) are 0.559g and 0.215g, respectively. The summary of this analysis is included in the appendix for reference. The likelihood of seismically-induced soil liquefaction or settlement for this project is considered low and does not warrant additional evaluation. 3.2 Surface Conditions The proposed project site is located on the southwest corner of the intersection of South 19th Avenue and Kagy Boulevard in Bozeman, Montana. This particular lot is relatively undeveloped consisting of native grasses and a small gravel surfaced trail through the center portion. Sidewalks exist along South 19th Avenue and Kagy Boulevard, and there are existing parking lots to the east and south of the property associated with adjacent development. Based on background information and site observations, the site appears to be generally flat but appears to exhibit a slight downward slope toward the northwest across the property. 3.3 Subsurface Conditions 3.3.1 Soils The subsurface soil conditions appear to be generally consistent in the overall depth to primary strata; however, the presence of varying surface topsoil and fill create increased variability in the uppermost two to three feet of the soil profile across the site. The fill was primarily seen on the south end of the project site in borings B-03 and B-04 and included 0.5 to 0.9 feet at the ground surface. Topsoil was encountered from the ground surface in B-01 and B-02 and below the fill in B-03 and B-04. The topsoil is primarily lean clay containing varying amounts of gravel and high organics. The topsoil extends to depths ranging from 2.7 to 3.1 feet below the current ground level. Native lean clays were observed beneath the topsoil in each boring extending to a depth of approximately 5.0 feet in each boring. The lean clay was underlain by native clayey gravel with sand in each boring which generally extends throughout the remainder of the investigation depth of 21.5 feet. A single lens of clayey sand was encountered in B-04 from approximately 20.0 to 21.0 feet within the gravels. II WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 7 The subsurface soils are described in detail on the enclosed boring logs and are summarized below. The stratification lines shown on the logs represent approximate boundaries between soil types, and the actual in situ transition may be gradual vertically or discontinuous laterally. FILL / TOPSOIL Fill was seen in two borings (B-03 and B-04) and ranged from 0.9 to 0.5 feet in thickness at the ground surface but is anticipated to be present elsewhere, especially near the existing gravel surfaced trail within the property. The topsoil is primarily a moderately plastic lean clay containing varying amounts of gravel and relatively high organic content. It ranges from firm to stiff as indicated by SPT values which ranged from 6 to 12 blows per foot (bpf) and averaged 8 bpf. Natural moisture contents ranged from 8.3 to 19.5 percent and averaged 13.5 percent. NATIVE LEAN CLAYS Native lean clays were encountered below the fill and topsoil in each boring and extend to depths of approximately five feet. The lean clays are firm to stiff as indicated by SPT values which ranged from 6 to 9 bpf and averaged 7.5 bpf. A single sample of the native lean clay contained 10.5 percent gravel, 7.6 percent sand, and 81.9 percent fines (clay and silt). Three samples exhibited liquid limits ranging from 33 to 43 percent and plasticity indices ranging from 15 to 24 percent. The natural moisture contents varied from 10.3 to 17.4 percent and averaged 13.1 percent. CLAYEY GRAVEL WITH SAND The primary soil type encountered in our investigation was native gravels classified as clayey gravel with sand. The gravel is considered dense to very dense as indicated by penetration resistance values which ranged from 31 to more than 100 blows per foot (bpf) and averaged 77 bpf. A single sample of the material contained 51.1 percent gravel, 20.6 percent sand, and 28.3 percent fines (clay and silt). The same sample exhibited a liquid limit of 36 percent and a plasticity index of 19 percent. The natural moisture contents varied from 2.4 to 14.4 percent and averaged 9.2 percent. 3.3.2 Ground Water Ground water was encountered in all four borings at depths ranging from 11.0 to 13.7 feet below the ground surface. Based on the time of our investigation, these levels are anticipated to be near the low seasonal elevation. No well construction or ground water monitoring was included in the scope of work for this project or performed on this project site; thus, we cannot comment definitely on the magnitude of seasonal ground water fluctuations that may occur or the potential maximum ground water elevation that may be seen. However, TD&H recently completed limited ground water monitoring for a MSU project located approximately 0.5-mile northeast of this WFCU Kagy & South 19th Site Conditions Bozeman, Montana Page 8 site which exhibited seasonal fluctuations in the wells ranging from 1 to 3 feet over the course of a single monitoring season. Based on these data, the seasonal high-water level is anticipated to occur between late April and early June. Due to the limited monitoring data available in the area and the lack of site-specific ground water monitoring, we would advise that at least five feet of ground water fluctuation be considered for this project which could indicate ground water levels rising to approximately five or six feet below current ground levels. This estimation is based solely on the ground water elevations observed during our site investigation and limited monitoring data performed in the general vicinity of the site over the course of one season. We cannot ensure that these data reflect a worst-case condition, and that ground water will not rise higher than the level estimated at some point in the future. If more accurate estimations of seasonal ground water variations are necessary for this site, the installation of ground water monitoring wells in the critical locations and subsequent monitoring is warranted and should begin promptly, as monitoring through a period from February to July is most critical to capture the seasonal high level which is anticipated to be reached between late April and early June. The presence or absence of observed ground water may be directly related to the time of the subsurface investigation. Numerous factors contribute to seasonal ground water occurrences and fluctuations, and the evaluation of such factors is beyond the scope of this report. WFCU Kagy & South 19th Engineering Analysis Bozeman, Montana Page 9 4.0 ENGINEERING ANALYSIS 4.1 Introduction Geotechnically the site conditions encountered pose no substantial concern for the planned construction. The native gravels encountered will be superior bearing strata for foundations with high allowable capacities and low settlement risk. However, these native gravels may contain large cobbles and boulders which can create stress concentrations on foundations. We therefore anticipate the need for limited structural fill beneath conventional footing depths which should alleviate potential concerns these large rocks pose. For any areas which utilize deeper foundations that could bear directly on native gravels, a cushion gravel course between foundations and the native gravels should be included whenever potential stress concentrations exist. Variability in the thickness and composition of the surface topsoil and fill layers, as well as the final site grading, will result in somewhat variable conditions beneath interior slabs. The existing topsoil and fill materials, which extend to depths ranging from 2.7 to 3.1 feet below the current ground surface, are not suitable to remain beneath the proposed building footprint. Thus, the removal of up to three feet of soil from the building footprint and replacement of this zone with properly compacted structural fill beneath interior slab systems will be warranted. Additional structural fill may be needed depending on the final site grading. Similar fill and topsoil materials pose potential settlement concerns to any exterior site development features including concrete flatwork, pavements, and others which do not include the removal and replacement of these materials as part of the final construction. However, similar site development aspects of the project can typically tolerate slightly larger settlements without adversely impacting the performance of these features; thus, it is our opinion that portions of the existing materials may remain provided the Owner is willing to accept some level of risk regarding their performance. When no risk is acceptable, all existing fill and topsoil must be completely removed from the site. 4.2 Site Grading and Excavations The ground surface at the proposed site is generally considered flat to gently sloping across the majority of the property with a slight downward slope toward the northwest. Based on our field work, variable thicknesses of surficial fill / topsoil, lean clay, and clayey gravel with sand are anticipated in the majority of foundation and utility excavations to the depths anticipated. Based on the borings, ground water should be below the anticipated depths of footing and utility excavations for this project and was encountered at relatively consistent depths ranging from 11.0 to 13.7 feet. However, per Section 3.3.2 of this report, seasonal ground water fluctuations have not been definitively determined; however, based on nearby ground water monitoring performed for another project we anticipate fluctuations could be as large as three to five feet. Assuming such fluctuations are realized, it is possible that ground water may be encountered in some foundation excavations extending more than six feet below current site grades. Thus, we believe it is prudent WFCU Kagy & South 19th Engineering Analysis Bozeman, Montana Page 10 that the contractor be prepared to dewater excavations if warranted at the time of excavation. Additionally, occasional pockets of trapped or perched ground water or zones of lateral seepage associated with recent precipitation could be encountered in excavations. 4.3 Conventional Shallow Foundations Considering the subsurface conditions encountered and the nature of the proposed construction, the structure can be supported on conventional shallow foundations bearing either directly on properly compacted native gravels, or when necessary, upon compacted structural fill extending to native gravels. Significant volumes of structural fill are not anticipated beneath foundations; however, 12 to 18 inches could be required depending on the final site grading. If the bearing surface of the native gravel exhibits protruding cobbles and cannot be rolled smooth, a thin leveling course should be placed between the native gravels and the concrete to mitigate potential stress concentrations. Based on our experience, the theory of elasticity, and using an allowable bearing pressure of 4,000 psf, we estimate the total settlement for footings will be less than ¾-inch. Differential settlement within the limits of individual structures should be on the order of one-half this magnitude. For design purposes, consideration of a one-third increase in the allowable bearing pressure provided is permitted for consideration of dynamic load cases. The lateral resistance of spread footings is controlled by a combination of sliding resistance between the footing and the foundation material at the base of the footing and the passive earth pressure against the side of the footing in the direction of movement. Design parameters are given in the recommendations section of this report. 4.4 Foundation and Retaining Walls Based on our current understanding of the structure and site development for this project, we do not anticipate the need for any foundations or site grading retaining walls which would retain differential soil heights. However, these design parameters may be required for some structures such as elevator pits or other features and have been included for consideration when appropriate. Foundation walls and other soil retaining structures will be subjected to horizontal loading due to lateral earth pressures. The lateral earth pressures are a function of the natural and backfill soil types and acceptable wall movements, which affect soil strain to mobilize the shear strength of the soil. More soil movement is required to develop greater internal shear strength and lower the lateral pressure on the wall. To fully mobilize strength and reduce lateral pressures, soil strain and allowable wall rotation must be greater for clay soils than for cohesionless, granular soils. The lowest lateral earth pressure against walls for a given soil type is the active condition and develops when wall movements occur. Passive earth pressures are developed when the wall is forced into the soil, such as at the base of a wall on the side opposite the retained earth side. When WFCU Kagy & South 19th Engineering Analysis Bozeman, Montana Page 11 no soil strain is allowed by the wall, this is the "at-rest" condition, which creates pressures having magnitudes between the passive and active conditions. The distribution of the lateral earth pressures on the structure depends on soil type and wall movements or deflections. In most cases, a triangular pressure distribution is satisfactory for design and is usually represented as an equivalent fluid unit weight. 4.5 Interior Floor Slabs The natural on-site soils, exclusive of existing fill and topsoil, are suitable to support lightly to moderately loaded, interior slab-on-grade construction. The removal of the existing fill and topsoil from site will warrant stripping depths of approximately three feet which must be replaced with properly compacted structural fill beneath the interior slab-on-grade. Final structural fill thicknesses will depend on the final site grading for the project and finished floor elevation. Isolated column or wall loads to be placed on the slab, or thickened portions of the slab, should be treated as a foundation and bear either directly on compacted native gravel or compacted structural fill extending to native gravels per Section 4.3.1 above. Thus, some localized over-excavation to remove remaining clay from beneath interior footings may be required. 4.6 Exterior Flatwork A leveling course of granular fill directly beneath exterior concrete is recommended to provide a structural cushion, a capillary-break from the subgrade, and a drainage medium. Construction typically utilizes six inches of compacted granular fill beneath exterior concrete; however, the requirements may vary locally. The typical base course thickness is not anticipated to be sufficient to completely remove existing fill and topsoil materials identified during the field investigation. While it is our opinion that optimal performance of exterior concrete flatwork would be achieved through the complete removal of these materials, we also understand that this may not be cost-effective or practical for the project. Thus, the minimum cushion course thickness is considered sufficient, and portions of the existing topsoil may remain provided it can be properly compacted, and the Owner is willing to accept a slightly lower level of performance associated with construction over organic containing materials. When no risk of performance can be tolerated, the removal and replacement of all existing topsoil and fill (approximately three feet across the site) is warranted. 4.7 Pavements A pavement section is a layered system designed to distribute concentrated traffic loads to the subgrade. Performance of the pavement structure is directly related to the physical properties of the subgrade soils and the magnitude and frequency of traffic loadings. Pavement design procedures are based on strength properties of the subgrade and pavement materials, along with the design traffic conditions. Site specific traffic information was not available at the time of this report; however, based on the project and the anticipated use, the associated parking lots are anticipated WFCU Kagy & South 19th Engineering Analysis Bozeman, Montana Page 12 to be utilized by primarily passenger type vehicles with limited trucks associated with typical garbage collection, deliveries, etc. These type of trucks are anticipated to be single unit, rear tandem axle vehicles (FHWA Class 6 or smaller). For the development of the pavement sections within this report, we have assumed that traffic for conventional parking lots will not exceed a 20- year design equivalent single axle load (ESAL) of 50,000 and heavy traffic conditions for main truck access routes will not exceed a 20-year design ESAL of 75,000. The anticipated subgrade material is the native lean clay, which is classified as an A-7 soil in accordance with the American Association of State Highway and Transportation Officials (AASHTO) classification. AASHTO considers this soil type to be a poor subgrade due to its poor permeability, moisture sensitivity, and loss of strength when wetted. Typical California Bearing Ratio (CBR) values for this type of soil range from 2 to 5 percent when properly compacted during construction. It will be necessary to properly compact the subgrade soils prior to placing fill material associated with the new pavement section. The fill should be selected, placed, and compacted in accordance with our recommendations. A geotextile acting as a separator is not structurally required for this project; however, the incorporation of a geotextile is advised anytime similar clay subgrades are present. A separation geotextile is a lightweight non-woven product which is intended to will prevent the upward migration of fines from the clay subgrade up into the pavement section gravels and the loss of aggregate into the subgrade during wet or seasonally unstable times. The separation geotextile thereby prolongs the structural integrity and performance of the pavement section. In our experience, the benefits of including a simple separation geotextile are greater than the limited cost of this added feature. The pavement sections presented in this report is based on an assumed CBR value of two percent, assumed traffic loadings, recommended pavement section design information presented in the Asphalt Institute and AASHTO Design Manuals, and our past pavement design experience in Bozeman. 4.8 Infiltration Testing Summary As part of the geotechnical investigation, a single infiltration test was performed following the general percolation test guidelines outlined in the 2013 Edition of the Montana Department of Environmental Quality (MT DEQ) Circular 4, Appendix A. This test method was selected in lieu of the Encased Falling Head Test typical of DEQ Circular 8 due to the inability to drive a casing into the native gravels and ensure a good seal with the casing which is required of that test method. The test exhibited an infiltration rate exceeding 3 minutes per inch (mpi) during the initial soaking phase and was stopped in accordance with the percolation test procedure. Converting the results to the units typical of DEQ Circular 8, infiltration exceeded 4 inches per hour (the suggested design infiltration rate for gravelly soils per Table 3 of DEQ Circular 8). We advise that design of storm water features for this project consider the tabular value of 4 inches per hour. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 13 5.0 RECOMMENDATIONS 5.1 Site Grading and Excavations 1. Topsoil and organic material should be removed from the proposed building and pavement areas and any areas to receive site grading fill. All topsoil must be removed from the proposed building footprint and organic containing materials should not remain beneath the building slab. Portions of the material denoted as topsoil may remain beneath parking lots and exterior flatwork when the associated risk is deemed acceptable to the Owner. 2. All fill and backfill should be non-expansive, free of organics and debris and should be approved by the project geotechnical engineer. The on-site soils, exclusive of topsoil, are suitable for use as backfill and general site grading fill on this project. All fill should be placed in uniform lifts not exceeding 8 inches in thickness for fine- grained soils and not exceeding 12 inches for granular soils. All materials compacted using hand compaction methods or small walk-behind units should utilize a maximum lift thickness of 6 inches to ensure adequate compaction throughout the lift. All fill and backfill shall be moisture conditioned to near the optimum moisture content and compacted to the following percentages of the maximum dry density determined by a standard proctor test which is outlined by ASTM D698 or equivalent (e.g. ASTM D4253-D4254). a) Below Foundations or Spread Footings ...................................... 98% b) Below Interior Slabs-on-Grade .................................................... 98% c) Below Exterior Flatwork and Exterior Foundation Backfill .......... 95% d) Below Streets or Other Paved Areas .......................................... 95% e) General Landscaping or Nonstructural Areas ............................. 92% f) Utility Trench Backfill, To Within 2 Feet of Surface ...................... 95% For your consideration, verification of compaction requires laboratory proctor tests to be performed on a representative sample of the soil prior to construction. These tests can require up to one week to complete (depending on laboratory backlog) and this should be considered when coordinating the construction schedule to ensure that delays in construction or additional testing expense is not required due to laboratory processing times or rush processing fees. 3. Imported structural fill, if required, should be non-expansive, free of organics and debris, and conform to the material requirements outlined in Section 02234 of the Montana Public Works Standard Specifications (MPWSS). All gradations outlined in this standard are acceptable for use on this project. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 14 4. Develop and maintain site grades which will rapidly drain surface and roof runoff away from foundation and subgrade soils; both during and after construction. The final site grading shall conform to the grading plan, prepared by others to satisfy the minimum requirements of the applicable building codes. 5. On-site materials are not expected to contain elevated sulfate contents which would warrant the use of specialized cementitious materials. Conventional Type I or Type II cement are appropriate for use on this project. 6. When possible, it is advised that downspouts from roof drains be collected and conveyed directly to the disposal site (pond, dry well, etc.) However, at a minimum, downspouts from roof drains should discharge at least six feet away from the foundation or beyond the limits of foundation backfill, whichever is greater. All downspout discharge areas should be properly graded away from the structures to promote drainage and prevent ponding. 7. It is the responsibility of the Contractor to provide safe working conditions in connection with underground excavations. Temporary construction excavations greater than four feet in depth, which workers will enter, will be governed by OSHA guidelines given in 29 CFR, Part 1926. The contractor is responsible to provide an OSHA knowledgeable individual during all excavation activities to regularly assess the soil conditions and ensure that all necessary safety precautions are implemented and followed. 5.2 Conventional Shallow Foundations The design and construction criteria below should be observed for a spread footing foundation system. The construction details should be considered when preparing the project documents. 8. Both interior and exterior footings should bear on properly compacted native gravels or compacted structural fill (Item 3) extending to native gravels. All bearing surfaces and structural fill should be compacted to the requirements of Item 2a and confirmed via field testing prior to footing construction. Footings to be constructed as described should be designed for a maximum allowable soil bearing pressure of 4,000 psf with consideration of an acceptable one-third increase for dynamic load cases. Footings designed using these values and constructed as described are not anticipated to experience settlements exceeding ¾-inch. If over-excavation and replacement with structural fill is required, the limits of over- excavation and replacement with compacted structural fill should extend at least 24 inches beyond the outer face of the footing in all directions. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 15 9. Construction using thickened slab sections to support interior walls or columns is acceptable; however, construction of these locations must comply with Item 8 above and may warrant additional over-excavation and replacement with structural fill beyond that needed for the non-bearing slab sections. 10. Soils disturbed below the planned depths of footing excavations should either be re- compacted or be replaced with suitable compacted backfill approved by the geotechnical engineer. 11. Footings shall be sized to satisfy the minimum requirements of the applicable building codes while not exceeding the maximum allowable bearing pressure provided in Item 8 above. 12. Exterior footings and footings beneath unheated areas, which will be exposed to freezing temperatures, should bear at least 48 inches below finished exterior grade for frost protection. Interior footings within heated controlled spaces for which frost is not an issue can utilize shallower footings or thickened-slab construction conforming to the requirements of Item 8 above. 13. The bottom of the footing excavations should be free of cobbles and boulders to avoid stress concentrations acting on the base of the footings. When bearing directly on native gravels, if the native bearing surface cannot be rolled smooth due to protruding cobbles or boulders, the bearing elevation shall be lowered at least four inches, and a thin layer of compacted cushion gravel installed. Cushion gravel shall conform to the requirements of MPWSS Section 02235 and be placed and compacted to comply with Item 2a. 14. Lateral loads are resisted by sliding friction between the footing base and the supporting soil and by lateral pressure against the footing opposing movement. For design purposes, a friction coefficient of 0.45 and a lateral resistance pressure of 150 psf per foot of depth are appropriate for footings bearing on compacted native gravels or structural fill and backfilled with properly compacted lean clays. 5.3 Foundation Walls Based on our current understanding of the structure and site development for this project, we do not anticipate the need for any foundations or site grading retaining walls which would retain differential soil heights. However, these design parameters may be required for select structures such as elevator pits or other features and have been included for consideration when appropriate. 15. Foundation walls and other retaining walls which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of 80 WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 16 pcf for backfill consisting of properly compacted native lean clay. The lateral earth pressure can be reduced to 60 pcf when backfill will be specified as compacted native gravels or structural fill within a horizontal distance equal to the height of the wall. 16. If utilized, retaining structures which can deflect sufficiently to mobilize the full active earth pressure condition, at least three percent of the exposed wall height, may be designed for a lateral earth pressure computed on the basis of an active equivalent fluid unit weight of 60 pcf for backfill consisting of properly compacted native lean clay. The lateral earth pressure can be reduced to 45 pcf when backfill will be specified as compacted native gravels or structural fill within a horizontal distance equal to the height of the wall. 17. Backfill should be selected, placed, and compacted per Item 2 above. Backfill should be placed in approximately equal lift thicknesses which alternate between the interior and exterior to avoid excessive lateral forces for which the walls were not designed. Care should be taken not to over-compact the backfill since this could cause excessive lateral pressure on the walls. Only hand-operated compaction equipment should be used within 5 feet of foundation and retaining walls. 18. Exterior footing drains are only required for this project in any areas in which the interior finished floor elevation is lower than the exterior grade around the building and shall be incorporated in all areas where this condition occurs. Drains should consist of a minimum 3-inch diameter, geotextile-wrapped, flexible, slotted pipe (ADS) or perforated, SDR 35, 4-inch diameter, PVC drain tile in poorly-graded gravel with geotextile placed at or below exterior footing grade. Drains shall be covered by at least 12 inches of free-draining, open-graded, granular material. The open-graded granular material should be enveloped in a geotextile to prevent the migration of fines. Use of a single piece of geotextile with a full-width lap at the top is preferred; however, two separate pieces of fabric may be used provided a minimum overlap distance of 12 inches is maintained at all joints. Drains should be sloped to an interior sump or a storm water system. A typical perimeter foundation drain is shown on Construction Standard No. 02801-06C. 19. Foundation walls should be damp-proofed in all areas in which the interior finished floor elevation is lower than the finished exterior grade. These would be the same areas requiring foundation drains per Item 18 above. All damp proofing should be in accordance with the applicable sections of the International Building Code (IBC). 5.4 Interior Floor Slabs 20. For normally loaded, interior slab-on-grade construction, all existing topsoil and fill shall be removed and replaced with properly compacted structural fill. An average WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 17 removal depth of approximately 36 inches should be anticipated. Structural fill thickness may vary from this depth depending on final site grading. Remaining native clay may remain except beneath interior wall or column footings using thickened-edge construction per Item 9 above. 21. Concrete floor slabs should be designed using a modulus of vertical subgrade reaction no greater than 250 pci when designed and constructed as recommended above. 22. Geotechnically, an underslab vapor barrier is not required for this project. A vapor barrier is normally used to limit the migration of soil gas and moisture into occupied spaces through floor slabs. The need for a vapor barrier should be determined by the architect and/or structural engineer based on interior improvements and/or moisture and gas control requirements. 5.5 Exterior Flatwork 23. For normally loaded, exterior concrete flatwork, a typical cushion course consisting of free-draining, crushed gravel should be placed beneath the concrete and compacted to the requirements of Item 2c above. A minimum cushion course thickness of six inches is common and advised for this project. Conventional construction, as has been described, is not intended to prevent concrete movements which may be the result of secondary settlement of remaining topsoil material, surface water infiltration, frost, or other factors. In most cases, the cost to repair and/or replace exterior flatwork when excessive movements occur is far more economical than efforts to mitigate these movements. 24. Cushion course materials utilized beneath exterior slab-on-grade applications should conform to the requirements outlined in Section 02235 of the Montana Public Works Standard Specifications (MPWSS). All gradations outlined in this specification are acceptable for this application. Prior to placing the cushion course, the upper six inches of subgrade should be compacted per Item 2c. 5.6 Pavements 25. The following flexible asphalt pavement sections should be considered in accordance with the discussions in the Engineering Analysis. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 18 Pavement Component Component Thickness Light Duty Heavy Duty Asphaltic Concrete Pavement 3” 4” Crushed Base Course 6” 6” Crushed Subbase Course 9” 9” Total 18” 19” 26. The following rigid concrete pavement sections should be considered in accordance with the discussions in the Engineering Analysis. Pavement Component Component Thickness Light Duty Heavy Duty Portland Cement Concrete Pavement 5” 6” Crushed Base Course 9” 9” Total 14” 15” 27. The pavement sections provided above have not considered construction phase traffic in their development and are not intended to be utilized by construction vehicles including concrete trucks, delivery trucks, etc. Use of the pavement sections by construction phase traffic without redesign by others to account for it will result in a reduced pavement life and increased potential of inferior pavement performance during and after construction. 28. Crushed base courses shall conform to the material properties outlined in Section 02235 of the Montana Public Works Standard Specifications (MPWSS). All gradations outlined in this specification are acceptable for this application based on the local availability and contractor preference. Crushed subbase courses shall conform to material properties outlined in Section 02234 of the MPWSS. All gradations outlined in this specification are acceptable for this application based on local availability and contractor preference. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 19 29. While not structurally required, a separation geotextile is recommended between the pavement section and the prepared subgrade to prevent the migration of fines upward into the gravel and the loss of aggregate into the subgrade. A non-woven Mirafi 180N or equivalent geotextile is appropriate in this application. 30. Ideally, the asphaltic cement should be a Performance Graded (PG) binder having the following minimum high and low temperature values based on the desired pavement reliability. Reliability Min. High Temp Rating Min. Low Temp Rating 50% 35.8 -23.8 98% 39.8 -32.5 For most low volume roadway applications, a 50-percent reliability is considered sufficient and the low temperature rating controls in most Montana climates. In most areas, asphalt mixes using either a PG 58-28 or PG 64-22 are readily available, and both are covered in standard MPWSS specifications. While both products satisfy the high temperature rating for both reliability levels, only the PG 58-28 grade oil will satisfy the low temperature rating for the 50-percent reliability level. This is considered the most suitable grade oil of the locally available products. 31. The concrete utilized for rigid pavement sections should provide a minimum compressive strength of 4,000 psi and a minimum modulus of rupture of 570 psi for the section thicknesses outlined above. If the concrete materials available cannot meet these minimum requirements, the concrete pavement section warrants modification and we should be consulted to assist with determining the appropriate section for the concrete properties to be utilized on the project. A modulus of vertical subgrade reaction no greater than 150 pci is appropriate for the design of the concrete reinforcing by others. 5.7 Continuing Services Three additional elements of geotechnical engineering service are important to the successful completion of this project. 32. Consultation between the geotechnical engineer and the design professionals during the design phases is highly recommended. This is important to ensure that the intentions of our recommendations are incorporated into the design, and that any changes in the design concept consider the geotechnical limitations dictated by the on-site subsurface soil and ground water conditions. WFCU Kagy & South 19th Recommendations Bozeman, Montana Page 20 33. Observation, monitoring, and testing during construction is required to document the successful completion of all earthwork and foundation phases. A geotechnical engineer from our firm should be retained to observe the excavation, earthwork, and foundation phases of the work to determine that subsurface conditions are compatible with those used in the analysis and design. 34. During site grading, placement of all fill and backfill should be observed and tested to confirm that the specified density has been achieved. We recommend that the Owner maintain control of the construction quality control by retaining the services of an experienced construction materials testing laboratory. The TD&H office in Bozeman is very experienced in similar construction materials testing and structural inspections and would be available to provide these services for this project. In the absence of project specific testing frequencies, TD&H recommends the following minimum testing frequencies be used: Compaction Testing Beneath Column Footings 1 Test per Footing per Lift Beneath Wall Footings 1 Test per 100 LF of Wall per Lift Beneath Slabs 1 Test per 1,500 SF per Lift Foundation Backfill 1 Test per 100 LF of Wall per Lift Parking Lots 1 Test per 2,500 SF per Lift LF = Lineal Feet SF = Square Feet WFCU Kagy & South 19th Summary of Field & Laboratory Studies Bozeman, Montana Page 21 6.0 SUMMARY OF FIELD AND LABORATORY STUDIES 6.1 Field Explorations The field exploration program was conducted on October 20, 2025. A total of four borings were drilled to depths ranging from 21.1 to 21.6 feet at the locations shown on Figures 1 to observe subsurface soil and ground water conditions. The borings were advanced through the subsurface soils using a truck-mounted Mobile B-60X drill rig equipped with 4.25-inch I.D. hollowstem augers. The subsurface exploration and sampling methods used are indicated on the attached boring logs. The borings were logged by Mr. Colton Shaff, EI of TD&H Engineering. The location of the borings were recorded using a Trimble handheld GPS unit. The locations shown are accurate to within 18 inches of the actual field location. During drilling, samples of the subsurface were taken using 1⅜-inch I.D. split spoon samplers. The samplers were driven 18 inches, when possible, into the various strata using a 140-pound drop hammer falling 30 inches onto the drill rods. For each sample, the number of blows required to advance the sampler each successive six-inch increment was recorded, and the total number of blows required to advance the sampler the final 12 inches is termed the penetration resistance (“N- value”). This test is known as the Standard Penetration Test (SPT) described by ASTM D1586. Penetration resistance values indicate the relative density of granular soils and the relative consistency of fine-grained soils. Logs of all soil borings, which include soil descriptions, sample depths, and penetration resistance values, are presented in the appendix as Figures 2 through 5. Measurements to determine the presence and depth of ground water were made in the borings, where encountered, by lowering an electronic water sounder through the auger shortly after the completion of drilling. The depths or elevations of the water levels measured, if encountered, and the date of measurement are shown on the applicable boring logs. 6.2 Laboratory Testing Samples obtained during the field exploration were returned to our materials laboratory where they were observed and visually classified in general accordance with ASTM D2487, which is based on the Unified Soil Classification System. Representative samples were selected for testing to determine the engineering and physical properties of the soils in general accordance with ASTM or other approved procedures. Tests Conducted: To determine: Natural Moisture Content Representative moisture content of soil at the time of sampling. Grain-Size Distribution Particle size distribution of soil constituents describing the percentages of clay/silt, sand and gravel. WFCU Kagy & South 19th Summary of Field & Laboratory Studies Bozeman, Montana Page 22 Atterberg Limits A method of describing the effect of varying water content on the consistency and behavior of fine-grained soils. The laboratory testing program for this project consisted of 26 moisture-visual analyses, 2 sieve (grain-size distribution) analyses, and 4 Atterberg Limits analyses. The results of the water content analyses are presented on the boring logs. The grain-size distribution curves and Atterberg limits are presented in the appendix as Figures 6 through 11. WFCU Kagy & South 19th Limitations Bozeman, Montana Page 23 7.0 LIMITATIONS This report has been prepared in accordance with generally accepted geotechnical engineering practices in this area for use by the client for design purposes. The findings, analyses, and recommendations contained in this report reflect our professional opinion regarding potential impacts the subsurface conditions may have on the proposed project and are based on site conditions encountered. Our analysis assumes that the results of the exploratory borings are representative of the subsurface conditions throughout the site, that is, that the subsurface conditions everywhere are not significantly different from those disclosed by the subsurface study. Unanticipated soil conditions are commonly encountered and cannot be fully determined by a limited number of soil borings and laboratory analyses. Such unexpected conditions frequently require that some additional expenditures be made to obtain a properly constructed project. Therefore, some contingency fund is recommended to accommodate such potential extra costs. The recommendations contained within this report are based on the subsurface conditions observed in the borings and are subject to change pending observation of the actual subsurface conditions encountered during construction. TD&H cannot assume responsibility or liability for the recommendations provided if we are not provided the opportunity to perform limited construction inspection and confirm the engineering assumptions made during our analysis. A representative of TD&H should be retained to observe all construction activities associated with subgrade preparation, foundations, and other geotechnical aspects of the project to ensure the conditions encountered are consistent with our assumptions. Unforeseen conditions or undisclosed changes to the project parameters or site conditions may warrant modification to the project recommendations. Long delays between the geotechnical investigation and the start of construction increase the potential for changes to the site and subsurface conditions which could impact the applicability of the recommendations provided. If site conditions have changed because of natural causes or construction operations at or adjacent to the site, TD&H should be retained to review the contents of this report to determine the applicability of the conclusions and recommendations provide considering the time lapse or changed conditions. Misinterpretation of the geotechnical information by other design team members is possible and can result in costly issues during construction and with the final product. Our geotechnical engineers are available upon request to review those portions of the plans and specifications which pertain to earthwork and foundations to determine if they are consistent with our recommendations and to suggest necessary modifications as warranted. This service was included in the original scope of the project and we should be notified when project plans are nearing completion to provide this review. Failure of the design team to notify our firm to complete this review will not warrant a reduction in the overall project fee. TD&H should be involved throughout the construction process to observe construction, particularly the placement and compaction of all fill, preparation of all foundations, and all other geotechnical aspects. Retaining the geotechnical engineer who prepared WFCU Kagy & South 19th Limitations Bozeman, Montana Page 24 your geotechnical report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. This report was prepared for the exclusive use of the owner and architect and/or engineer in the design of the subject facility. It should be made available to prospective contractors and/or the contractor for information on factual data only and not as a warranty of subsurface conditions such as those interpreted from the boring logs and presented in discussions of subsurface conditions included in this report. Prepared by: Reviewed by: Craig R. Nadeau PE & Principal Peter Klevberg, PE Geotechnical Manager Geotechnical Engineer TD&H ENGINEERING TD&H ENGINEERING 0 3 6 9 12 15 18 21 TOPSOIL: Clayey GRAVEL, loose, brown, slightly moist to moist Lean CLAY with Gravel, firm, brown to light brown, moist Clayey GRAVEL with Sand, very dense to dense, brown, slightly moist to wet Bottom of Boring 2.8 5.2 21.5 7-3-3 3-2-4 15-28- 32 20-17- 21 26-50/ 5.5" 21-42- 50/4" 60 50/5.5" 92/10" LEGEND LOG OF SOIL BORING B-01SPT blows per foot Atterberg Limits Field Moisture content Whitefish Credit Union - Kagy & S 19th Bozeman, MontanaGroundwater Level Grab/composite sample 1-3/8-inch I.D. split spoon Logged by:Colton Shaff, EI 2-1/2-inch I.D. split spoon Drilled by:O'Keefe Drilling Truck-mounted Mobile B-60X with 4.25-inch HSA2-1/2-inch I.D. ring sampler GNP = Granular and Nonplastic 3-inch I.D. thin-walled sampler Note: The stratification lines represent approximate boundaries between soil types. Actual boundaries may be gradual or transitional. October 20, 2025 B25-067-001 No sample recovery Figure No. 2 SheetGRAPHICLOGSOIL DESCRIPTION SURFACE:Native Grasses & Surfacing Gravels SURFACE ELEVATION:Not Measured DEPTH (FT)GROUNDWATERSPT BLOWCOUNTSSAMPLEDEPTH (FT)PENETRATION RESISTANCE/MOISTURE CONTENT 0 10 20 30 40 50 = BLOWS PER FOOT = MOISTURE CONTENT 1 of 1 0 3 6 9 12 15 18 21 TOPSOIL: Clayey GRAVEL with Sand, loose, brown, moist Lean CLAY, firm, light brown to tan, dry to slightly moist Clayey GRAVEL with Sand, dense to very dense, brown, slightly moist to wet Bottom of Boring 3.0 5.0 21.6 4-3-4 4-2-4 15-24- 24 29-31- 34 50/5.5" 25-50/ 5" 65 50/5.5" 50/5" LEGEND LOG OF SOIL BORING B-02SPT blows per foot Atterberg Limits Field Moisture content Whitefish Credit Union - Kagy & S 19th Bozeman, MontanaGroundwater Level Grab/composite sample 1-3/8-inch I.D. split spoon Logged by:Colton Shaff, EI 2-1/2-inch I.D. split spoon Drilled by:O'Keefe Drilling Truck-mounted Mobile B-60X with 4.25-inch HSA2-1/2-inch I.D. ring sampler GNP = Granular and Nonplastic 3-inch I.D. thin-walled sampler Note: The stratification lines represent approximate boundaries between soil types. Actual boundaries may be gradual or transitional. October 20, 2025 B25-067-001 No sample recovery Figure No. 3 SheetGRAPHICLOGSOIL DESCRIPTION SURFACE:Native Grasses & Surfacing Gravels SURFACE ELEVATION:Not Measured DEPTH (FT)GROUNDWATERSPT BLOWCOUNTSSAMPLEDEPTH (FT)PENETRATION RESISTANCE/MOISTURE CONTENT 0 10 20 30 40 50 = BLOWS PER FOOT = MOISTURE CONTENT 1 of 1 0 3 6 9 12 15 18 21 TOPSOIL: Gravelly Lean CLAY, firm, brown, moist, heavy organics FILL: Clayey GRAVEL with Sand, loose, brown, moist Lean CLAY, stiff, dark brown, moist, organics, original topsoil Lean CLAY, stiff, light brown to tan, slightly moist Clayey GRAVEL with Sand, very dense to dense, brown, slightly moist to wet Bottom of Boring 0.2 0.9 3.1 5.0 21.1 5-5-3 4-4-5 17-28- 50/2" 50/4" 12-14- 21 11-49- 49 42-50/ 4" 78/8" 50/4" 98 50/4" LEGEND LOG OF SOIL BORING B-03SPT blows per foot Atterberg Limits Field Moisture content Whitefish Credit Union - Kagy & S 19th Bozeman, MontanaGroundwater Level Grab/composite sample 1-3/8-inch I.D. split spoon Logged by:Colton Shaff, EI 2-1/2-inch I.D. split spoon Drilled by:O'Keefe Drilling Truck-mounted Mobile B-60X with 4.25-inch HSA2-1/2-inch I.D. ring sampler GNP = Granular and Nonplastic 3-inch I.D. thin-walled sampler Note: The stratification lines represent approximate boundaries between soil types. Actual boundaries may be gradual or transitional. October 20, 2025 B25-067-001 No sample recovery Figure No. 4 SheetGRAPHICLOGSOIL DESCRIPTION SURFACE:Native Grasses SURFACE ELEVATION:Not Measured DEPTH (FT)GROUNDWATERSPT BLOWCOUNTSSAMPLEDEPTH (FT)PENETRATION RESISTANCE/MOISTURE CONTENT 0 10 20 30 40 50 = BLOWS PER FOOT = MOISTURE CONTENT 1 of 1 0 3 6 9 12 15 18 21 FILL: Poorly-Graded GRAVEL with Sand, loose, brown, slightly moist TOPSOIL: Lean CLAY, stiff, dark brown, moist Lean CLAY with Gravel, stiff, light brown to tan, slightly moist to moist Clayey GRAVEL with Sand, very dense to dense, brown, moist to wet - Lens of clayey sand from approx. 20.0 to 21.0 feet. Bottom of Boring 0.5 2.7 5.0 21.5 5-7-5 5-5-4 26-33- 33 15-13- 18 20-24- 49 4-7-50/ 5" 66 73 57/11" LEGEND LOG OF SOIL BORING B-04SPT blows per foot Atterberg Limits Field Moisture content Whitefish Credit Union - Kagy & S 19th Bozeman, MontanaGroundwater Level Grab/composite sample 1-3/8-inch I.D. split spoon Logged by:Colton Shaff, EI 2-1/2-inch I.D. split spoon Drilled by:O'Keefe Drilling Truck-mounted Mobile B-60X with 4.25-inch HSA2-1/2-inch I.D. ring sampler GNP = Granular and Nonplastic 3-inch I.D. thin-walled sampler Note: The stratification lines represent approximate boundaries between soil types. Actual boundaries may be gradual or transitional. October 20, 2025 B25-067-001 No sample recovery Figure No. 5 SheetGRAPHICLOGSOIL DESCRIPTION SURFACE:Native Grasses & Surfacing Gravel SURFACE ELEVATION:Not Measured DEPTH (FT)GROUNDWATERSPT BLOWCOUNTSSAMPLEDEPTH (FT)PENETRATION RESISTANCE/MOISTURE CONTENT 0 10 20 30 40 50 = BLOWS PER FOOT = MOISTURE CONTENT 1 of 1 Tested By: BC Checked By: Particle Size Distribution Report ASTM C117 & C136 PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.00010.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 16.8 34.3 7.4 7.4 5.8 28.36 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM C117 & C136)Material Description Atterberg Limits Coefficients Classification Test Remarks Sample Date:Location: B-02 Sample Number: A-32662 Depth: 5.0 - 7.5 ft Client: Project: Project No: Figure Sieve Size or Diam. (mm.) Finer (%) Spec.* (%) Out of Spec. (%) Pct. of Fines Clayey GRAVEL with Sand 1.5 1 3/4" 1/2" 3/8" #4 #10 #20 #40 #60 #80 #100 #200 100.0 92.8 83.2 71.1 62.9 48.9 41.5 37.5 34.1 32.1 30.9 30.3 28.3 17 36 19 23.1568 20.1176 8.4505 5.1241 0.1374 GC A-2-6(1) Report No. A-32662-206 Report Date: 11-20-2025 F.M.=4.25 10-20-2025 Whitefish Credit Union Whitefish Credit Union - Kagy & S 19th Bozeman, Montana B25-067-001 PL= LL= PI= D90= D85= D60= D50= D30= D15= D10= Cu= Cc= USCS= AASHTO= *(no specification provided) 6 Tested By: BC Checked By: Particle Size Distribution Report ASTM C117 & C136 PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.00010.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 3.8 6.7 1.2 1.6 4.8 81.96 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM C117 & C136)Material Description Atterberg Limits Coefficients Classification Test Remarks Sample Date:Location: B-04 Sample Number: A-32677 Depth: 2.5 - 5.0 ft Client: Project: Project No: Figure Sieve Size or Diam. (mm.) Finer (%) Spec.* (%) Out of Spec. (%) Pct. of Fines Lean CLAY with Gravel 1 3/4" 1/2" 3/8" #4 #10 #20 #40 #60 #80 #100 #200 100.0 96.2 94.4 91.2 89.5 88.3 87.5 86.7 85.8 85.2 84.7 81.9 19 43 24 6.9455 0.1667 CL A-7-6(19) Report No. A-32677-206 Report Date: 11-20-2025 F.M.=0.89 10-20-2025 Whitefish Credit Union Whitefish Credit Union - Kagy & S 19th Bozeman, Montana B25-067-001 PL= LL= PI= D90= D85= D60= D50= D30= D15= D10= Cu= Cc= USCS= AASHTO= *(no specification provided) 7 Tested By: BC Checked By: LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML C L o r O L C H o r O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT32 32.4 32.8 33.2 33.6 34 34.4 34.8 35.2 35.6 36 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No. Client: Remarks: Project: Location: B-01 Sample Number: A-32654 Depth: 2.5 - 4.0 ft Figure Lean CLAY with Gravel 33 18 15 Not Tested Not Tested CL B25-067-001 Whitefish Credit Union 8 Report No. A-32654-207 Report Date: 11-25-2025Whitefish Credit Union - Kagy & S 19th Bozeman, Montana Tested By: BC Checked By: LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML C L o r O L C H o r O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT34 34.4 34.8 35.2 35.6 36 36.4 36.8 37.2 37.6 38 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No. Client: Remarks: Project: Location: B-02 Sample Number: A-32662 Depth: 5.0 - 7.5 ft Figure Clayey GRAVEL with Sand 36 17 19 34.1 28.3 GC B25-067-001 Whitefish Credit Union 9 Report No. A-32662-207 Report Date: 11-15-2025Whitefish Credit Union - Kagy & S 19th Bozeman, Montana Tested By: BC Checked By: LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML C L o r O L C H o r O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT35.4 35.8 36.2 36.6 37 37.4 37.8 38.2 38.6 39 39.4 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No. Client: Remarks: Project: Location: B-03 Sample Number: A-32668 Depth: 3.1 - 3.7 ft Figure Lean CLAY 37 19 18 Not Tested Not Tested CL B25-067-001 Whitefish Credit Union 10 Report No. A-32668-207 Report Date: 11-24-2025Whitefish Credit Union - Kagy & S 19th Bozeman, Montana Tested By: BC Checked By: LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML C L o r O L C H o r O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT40.8 41.2 41.6 42 42.4 42.8 43.2 43.6 44 44.4 44.8 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No. Client: Remarks: Project: Location: B-04 Sample Number: A-32677 Depth: 2.5 - 5.0 ft Figure Lean CLAY with Gravel 43 19 24 86.7 81.9 CL B25-067-001 Whitefish Credit Union 11 Report No. A-32677-207 Report Date: 11-25-2025Whitefish Credit Union - Kagy & S 19th Bozeman, Montana Circular DEQ 4 Page 126 of 159 2013 Edition MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY PERCOLATION TEST FORM Owner Name Project Name Lot of Tract Number Test Number Diameter of Test Hole Depth of Test Hole Date and Time Soak Period Began Ended Date Test Began Distance of the reference point above the bottom of the hole Test Results Start Time of Day End Time of Day Time Interval (minutes) Initial Distance Below Reference Point Final Distance Below Reference Point Drop in Water Level (inches) Percolation Rate (mpi) I certify that this percolation test was done by a qualified site evaluator in accordance with DEQ-4 Section 1.2.68 and Appendix A. Name (printed) Signature Date Company Whitefish Credit Union WFCU Kagy & S 19th - Bozeman, Montana PERC-1 6"3.5 ft 11-13-2025 11:52 AM 11-13-2025 12:26 PM 5.3 ft 11:52 12:06 14:00 4.3 ft 5.3 ft 12" 1.17 12:07 12:26 18:37 4.3 ft 5.3 ft 12" 1.53 Craig Nadeau 11-13-2025 TD&H Engineering FIGURE 12 ASCE Hazards Report Address: No Address at This Location Standard:ASCE/SEI 7-16 Latitude:45.659832 Risk Category:III Longitude:-111.063361 Soil Class:C - Very Dense Soil and Soft Rock Elevation:4921.8495259375 ft (NAVD 88) Page 1 of 3https://ascehazardtool.org/Mon Dec 08 2025 SS : 0.684 S1 : 0.215 Fa : 1.227 Fv : 1.5 SMS : 0.839 SM1 : 0.323 SDS : 0.559 SD1 : 0.215 TL : 6 PGA : 0.301 PGA M : 0.361 FPGA : 1.2 Ie : 1.25 Cv : 1.021 Seismic Design Category:D Design Response Spectrum S (g) vs T(s)a MCE Response SpectrumR S (g) vs T(s)a Design Vertical Response Spectrum S (g) vs T(s)a MCE Vertical Response SpectrumR S (g) vs T(s)a Seismic C - Very Dense Soil and Soft RockSite Soil Class: Results: Data Accessed: Mon Dec 08 2025 Date Source: USGS Seismic Design Maps based on ASCE/SEI 7-16 and ASCE/SEI 7-16 Table 1.5-2. Additional data for site-specific ground motion procedures in accordance with ASCE/SEI 7-16 Ch. 21 are available from USGS. Page 2 of 3https://ascehazardtool.org/Mon Dec 08 2025 QUALITY CHECK: DESIGNED BY: DRAWN BY: CAD NO. JOB NO. DATE: 02801-06C Engineering tdhengineering.com CONSTRUCTION STANDARD NO. 02801-06C PERIMETER FOUNDATION DRAIN RESIDENTIAL CONSTRUCTION RLT CRN MMJ 5/21/15 FIGURE TD&H Engineering Consultants Great Falls, Kalispell, Bozeman, MT Spokane, WA; Lewiston, ID, Watford City, ND TD&H Engineering Consultants Great Falls, Kalispell, Bozeman, MT Spokane, WA; Lewiston, ID, Watford City, ND APPENDIX B: STORM DRAINAGE EXHIBITS ss ss ss ss ss ss ssssssssssss ssbpbpbp bpbpbpbpbpbpbpbpbpbpbpbpbp bp bp bp bp bp bp bp bp bp oh oh oh oh oh oh oh oh oh oh ohgasgasg a s gasgasgasgasgasgasgasgasgasgasgasgasgasgasgasgasgasbt bt bt bt bt bt bt bt bt bt btbt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt btWSSEEEE ETTTTTFOFOFOFOTTTTTTTwm wmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwm wmTEEX XSSDstssssssSstDwmwmwmwmELot 3AMinor Subd ivision 503CCommon Open Space AMinor Subdivision 503CPublic Right-of-Way DedicationMinor Subdivision 503CKagy BoulevardWidth VariesSouth 19th Avenue Width Varies S 88°36'18" E 191.26' (R1)S 89°52'03" E 191.26' (M)S 28°49'39" E9.81' (C)S 27°33'54" E9.81' (R1)S 00°20'06" W 245.17' (M) S 01°33'21" W 245.27' (R1)S 89°44'45" W 126.63' (M)N 88°56'52" W 126.64' (R1)N 01°03'08" E 44.41' (R1) N 00°12'23" W 44.48' (M)S 89°44'40" W 81.63' (M)N 88°56'52" W 81.67' (R1)S 00°12'31" E20.80' (M)S 01°03'08" W20.83' (R1)S 89°45'28" W 33.87' (C)N 88°56'53" W 34.00' (R1)N 01°03'08" E 179.47' (R1)N 00°12'37" W 179.44' (C)S 88°56'52" E 48.50' (R1)N 89°47'23" E 48.50' (C)N 01°03'08" W 51.97' (R1)N 00°12'37" W 51.97' (C)Lot 2A-1Minor Subdivision 503CArea = 1.262 acres10' Public Utility EasementPer Minor Subdivision 50310' Public Utility Easement Per Minor Subdivision 503 30' Sewer and Water and Access EasementDocument No. 2471376 30' Easement perDocument No. 2471376Easement perDocument No. 2841657Middle Creek Ditch PROPOSED BUILDING15,057 SF4921.00 FFE©| ALL RIGHTS RESERVED®DRAWN BY |REVISIONSREVIEWED BY |DESIGNED BY |PROJ# |BOZEMAN BRANCH WHITEFISH CREDIT UNION2026SITE PLAN SUBMITTAL 04.30.2026WFCU_BOZ5/1/2026 2:42 PM | L:\WFCU_BOZ\BIMCAD\Civil\Sheets\WFCU_BOZ_D.1.dwgD.1HISTORIC DRAINAGEBASINMIRANDAMIRANDASCHLEGEL-1D.1HISTORIC DRAINAGE BASIN0102040SCALE: 1" = 20'NORTHEXISTING STORM PONDBASIN DESIGNATIONPERCENT IMPERVIOUSBASIN AREA IN ACRESDEV-###.####SUBSURFACE STORMCHAMBERSHIST-020.8883HIST-010.840 ss ss ss ss ss ss ssssssssssss ssbpbpbp bpbpbpbpbpbpbpbpbpbpbpbpbp bp bp bp bp bp bp bp bp bp oh oh oh oh oh oh oh oh oh oh ohgasgasg a s gasgasgasgasgasgasgasgasgasgasgasgasgasgasgasgasgasbt bt bt bt bt bt bt bt bt bt btbt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt bt btWSSEEEE ETTTTTFOFOFOFOTTTTTTTwm wmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwm wmTEEX XSSDstssssssSstDwmwmwmwmELot 3AMinor Subd ivision 503CCommon Open Space AMinor Subdivision 503CPublic Right-of-Way DedicationMinor Subdivision 503CKagy BoulevardWidth VariesSouth 19th Avenue Width Varies S 88°36'18" E 191.26' (R1)S 89°52'03" E 191.26' (M)S 28°49'39" E9.81' (C)S 27°33'54" E9.81' (R1)S 00°20'06" W 245.17' (M) S 01°33'21" W 245.27' (R1)S 89°44'45" W 126.63' (M)N 88°56'52" W 126.64' (R1)N 01°03'08" E 44.41' (R1) N 00°12'23" W 44.48' (M)S 89°44'40" W 81.63' (M)N 88°56'52" W 81.67' (R1)S 00°12'31" E20.80' (M)S 01°03'08" W20.83' (R1)S 89°45'28" W 33.87' (C)N 88°56'53" W 34.00' (R1)N 01°03'08" E 179.47' (R1)N 00°12'37" W 179.44' (C)S 88°56'52" E 48.50' (R1)N 89°47'23" E 48.50' (C)N 01°03'08" W 51.97' (R1)N 00°12'37" W 51.97' (C)Lot 2A-1Minor Subdivision 503CArea = 1.262 acres10' Public Utility EasementPer Minor Subdivision 50310' Public Utility Easement Per Minor Subdivision 503 30' Sewer and Water and Access EasementDocument No. 2471376 30' Easement perDocument No. 2471376Easement perDocument No. 2841657Middle Creek Ditch PROPOSED BUILDING15,057 SF4921.00 FFESSBP BP BPWSWSWSWSWSWSWSWSWSWSWSWSWSWSFFFFFFFFFFFFFFFFFGA S GAS GAS GAS GAS GAS GASGASHYDF491 9 492049 2 04920 492049204921 4 9 2 1 492 1 4921 49214921492149224922 49224917491749184918 4918491849194919 491949194919 49194 9 1 9 491949194919 49194919491949204920 49 2 0 4920 4920492049204920492149214921 4 9 2 14922 492249234923492449244920 4920 4921 49214922492249224922 4922 492249234923 4923 4923 492349244925 DSTSTSTDCOCOADS-0148"∅RIM:4919.67IE IN (S):4913.50 12"IE IN (N):4912.70 12"STCB-0148"∅RIM:4919.10IE OUT (N):4915.70 12"36 LF of 12" @ 3.04%33 LF o f 6" @ 1 .29%36 LF of 6" @ 1.00%63 LF of 6" @ 1.00%4 LF of 6" @ 33.29%5 LF of 3" @ 3.00%115 LF of 24" @ -1.35%STRUCTURE - (63)48"∅RIM:4921.91IE OUT (S):4917.00 24"36 LF of 3" @ 6.30%©| ALL RIGHTS RESERVED®DRAWN BY |REVISIONSREVIEWED BY |DESIGNED BY |PROJ# |BOZEMAN BRANCH WHITEFISH CREDIT UNION2026SITE PLAN SUBMITTAL 04.30.2026WFCU_BOZ5/1/2026 3:51 PM | L:\WFCU_BOZ\BIMCAD\Civil\Sheets\WFCU_BOZ_D.2.dwgD.2DEVELOPED DRAINAGEBASINMIRANDAMIRANDASCHLEGEL-1D.2DEVELOPED DRAINAGE BASIN0102040SCALE: 1" = 20'NORTHPROPOSEDCURB CUTEXISTING STORM PONDBASIN DESIGNATIONPERCENT IMPERVIOUSBASIN AREA IN ACRESDEV-###.####DEV-010.9880DEV-020.7985ADS SUBSURFACESTORM CHAMBERS APPENDIX C: POST DEVELOPMENT CALCULATIONS Basin Pervious (Landscape/ Undeveloped) (sf) (C=0.22) Impervious (Roof/ Paving) (sf) (C=0.95) Total (sf)Total (ac)Weighted Coefficient % Impervious DEV-01 8706 33919 42626 0.98 0.80 80% DEV-02 5115 29112 34227 0.79 0.84 85% Total: 13822 63031 76853 1.76 0.82 82% BASIN C Area (ac) 2-hr (i) in/hr Q cfs V (cf) DEV-01 0.80 0.98 0.41 0.32 2301 DEV-02 0.84 0.79 0.41 0.27 1940 Total: 0.82 1.76 0.41 0.59 4242 BASIN Area (ac)P (in) Imperv.Rv WQV (cf) DEV-01 0.98 0.50 0.80 0.77 1361 DEV-02 0.79 0.50 0.85 0.82 1163 Facility Name Required Detention Volume (CF) (see Appendix C) Provided Storage Volume (CF) System Height (in) Drain-down time (hr) Bottom of System Elevation Groundwater Elevation Groundwater Separation (ft) ADS System 3,913 4,392 66 24 4,911.7 4,908.7 3.1 Storm Facility Data * Calculation uses 5-min time of concentration Water Quality Volume (WQV) * POST-DEVELOPMENT BASINS Total Runoff Volume (10-yr/2-hr storm) WFCU BOZEMAN Developed Basin ID Pervious (Landscaped / Undeveloped) Impervious (Roof / Paving) Total Area (SF) Total Area (Acres) Weighted C % Impervious Cf (100-yr) C*Cf (max 1.0) DEV-01 8706 33919 42626 0.98 0.80 80%1.25 1.00 Length (ft) With (ft) Infiltration area (SF) Design Infiltration rate (in/hr) Design Infiltratio n rate (cfs) 45.83 29.77 1364.3591 4 0.13 Duration (min) Vinfil (cf) i (in/hr) Q (cfs) Vrunoff (cf) Vdetention (cf) i (in/hr) Q (cfs) Vrunoff (cf) Vdetention (cf) 5 38 3.87 3.03 910 872 6.09 5.96 1788 1750 10 76 2.83 2.22 1331 1255 4.45 4.35 2613 2537 15 114 2.29 1.79 1615 1502 3.68 3.60 3241 3127 20 152 1.84 1.44 1730 1579 2.89 2.83 3394 3242 25 189 1.56 1.22 1834 1644 2.46 2.41 3611 3421 30 227 1.38 1.08 1947 1719 2.18 2.13 3840 3612 35 265 1.22 0.96 2008 1743 1.92 1.88 3946 3680 40 303 0.99 0.78 1862 1559 1.72 1.68 4039 3736 45 341 1.00 0.78 2116 1775 1.57 1.54 4148 3807 50 379 0.91 0.71 2140 1761 1.44 1.41 4227 3848 55 417 0.84 0.66 2172 1756 1.33 1.30 4295 3878 60 455 0.79 0.62 2229 1774 1.24 1.21 4368 3913 120 910 0.41 0.32 2314 1404 0.61 0.60 4298 3388 180 1364 0.29 0.23 2455 1090 0.41 0.40 4333 2969 360 2729 0.17 0.13 2878 149 0.22 0.22 4650 1921 720 5457 0.10 0.08 3386 0 0.14 0.14 5918 461 1440 10915 0.07 0.06 4808 0 0.10 0.10 8286 0 Area (ac)P (in) Imperv.Rv WQV (cf) 0.98 0.50 0.80 0.77 1361 Cubic Feet Min Volume Reqd for 100-Yr Storm Water Quality Volume (WQV) * DEV-01 Infiltration Basin - Design Calculations Minimum Stormwater Dentention Volume 3,913 Revieving Drainage Basin Information Infiltration Basin Information Min Volume Reqd for 10-Yr Storm WFCU BOZEMAN Area (ac)P (in) Imperv.Rv WQV (cf) 0.79 0.50 0.85 0.82 1163 DEV-02 Existing Pond - Design Calculations Water Quality Volume (WQV) * APPENDIX D: FEMA FLOOD MAP National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOODHAZARD AREAS Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X Future Conditions 1% Annual Chance Flood Hazard Zone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below.The basemap shown complies with FEMA's basemapaccuracy standards The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 3/12/2026 at 7:24 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximatepoint selected by the user and does not representan authoritative property location. 1:6,000 111°4'8"W 45°39'48"N 111°3'30"W 45°39'23"N Basemap Imagery Source: USGS National Map 2023 APPENDIX E: NRCS SOILS United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Gallatin County Area, MontanaNatural Resources Conservation Service March 12, 2026 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Gallatin County Area, Montana.......................................................................13 448A—Hyalite-Beaverton complex, moderately wet, 0 to 2 percent slopes....................................................................................................13 Soil Information for All Uses...............................................................................16 Soil Reports........................................................................................................16 Soil Physical Properties..................................................................................16 Engineering Properties................................................................................16 References............................................................................................................22 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 5056220505623050562405056250505626050562705056280505629050562205056230505624050562505056260505627050562805056290494990 495000 495010 495020 495030 495040 495050 495060 495070 495080 495090 495100 494990 495000 495010 495020 495030 495040 495050 495060 495070 495080 495090 495100 45° 39' 36'' N 111° 3' 51'' W45° 39' 36'' N111° 3' 46'' W45° 39' 34'' N 111° 3' 51'' W45° 39' 34'' N 111° 3' 46'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 25 50 100 150 Feet 0 5 10 20 30 Meters Map Scale: 1:582 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Gallatin County Area, Montana Survey Area Data: Version 29, Aug 30, 2025 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 18, 2022—Aug 29, 2022 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 448A Hyalite-Beaverton complex, moderately wet, 0 to 2 percent slopes 1.6 100.0% Totals for Area of Interest 1.6 100.0% 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 landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, Custom Soil Resource Report 11 onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Gallatin County Area, Montana 448A—Hyalite-Beaverton complex, moderately wet, 0 to 2 percent slopes Map Unit Setting National map unit symbol: 56sq Elevation: 4,450 to 5,300 feet Mean annual precipitation: 15 to 19 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 Hyalite and similar soils: 70 percent Beaverton and similar soils: 20 percent Minor components: 10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hyalite Setting Landform: Alluvial fans, Stream terraces Down-slope shape: Linear Across-slope shape: Linear Parent material: Loamy alluvium Typical profile A - 0 to 5 inches: loam Bt1 - 5 to 9 inches: clay loam Bt2 - 9 to 17 inches: silty clay loam 2Bt3 - 17 to 26 inches: very cobbly sandy clay loam 3C - 26 to 60 inches: very cobbly loamy sand Properties and qualities Slope: 0 to 2 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: About 48 to 96 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 5 percent Available water supply, 0 to 60 inches: Low (about 4.4 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R043BP818MT - Upland Grassland Group Hydric soil rating: No Custom Soil Resource Report 13 Description of Beaverton Setting Landform: Alluvial fans, Stream terraces Down-slope shape: Linear Across-slope shape: Linear Parent material: Alluvium Typical profile A - 0 to 5 inches: cobbly loam Bt - 5 to 21 inches: very gravelly clay loam Bk - 21 to 25 inches: very cobbly coarse sandy loam 2Bk - 25 to 60 inches: extremely cobbly loamy coarse sand Properties and qualities Slope: 0 to 2 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 to high (0.57 to 1.98 in/hr) Depth to water table: About 48 to 96 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 15 percent Maximum salinity: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: Low (about 3.7 inches) Interpretive groups Land capability classification (irrigated): 4s Land capability classification (nonirrigated): 6s Hydrologic Soil Group: B Ecological site: R043BP818MT - Upland Grassland Group Hydric soil rating: No Minor Components Meadowcreek Percent of map unit: 5 percent Landform: Stream terraces Down-slope shape: Linear Across-slope shape: Linear Ecological site: R044BP815MT - Subirrigated Grassland Hydric soil rating: No Beaverton Percent of map unit: 5 percent Landform: Alluvial fans, Stream terraces Down-slope shape: Linear Across-slope shape: Linear Ecological site: R044BP818MT - Upland Grassland Hydric soil rating: No Custom Soil Resource Report 14 Custom Soil Resource Report 15 Soil Information for All Uses Soil Reports The Soil Reports section includes various formatted tabular and narrative reports (tables) containing data for each selected soil map unit and each component of each unit. No aggregation of data has occurred as is done in reports in the Soil Properties and Qualities and Suitabilities and Limitations sections. The reports contain soil interpretive information as well as basic soil properties and qualities. A description of each report (table) is included. Soil Physical Properties This folder contains a collection of tabular reports that present soil physical properties. The reports (tables) include all selected map units and components for each map unit. Soil physical properties are measured or inferred from direct observations in the field or laboratory. Examples of soil physical properties include percent clay, organic matter, saturated hydraulic conductivity, available water capacity, and bulk density. Engineering Properties This table gives the engineering classifications and the range of engineering properties for the layers of each soil in the survey area. Hydrologic soil group is a group of soils having similar runoff potential under similar storm and cover conditions. The criteria for determining Hydrologic soil group is found in the National Engineering Handbook, Chapter 7 issued May 2007(http:// directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17757.wba). Listing HSGs by soil map unit component and not by soil series is a new concept for the engineers. Past engineering references contained lists of HSGs by soil series. Soil series are continually being defined and redefined, and the list of soil series names changes so frequently as to make the task of maintaining a single national list virtually impossible. Therefore, the criteria is now used to calculate the HSG using the component soil properties and no such national series lists will be maintained. All such references are obsolete and their use should be discontinued. Soil properties that influence runoff potential are those that influence the minimum rate of infiltration for a bare soil after prolonged wetting and when not frozen. These properties are depth to a seasonal high water table, saturated hydraulic conductivity after prolonged wetting, and depth to a layer with a very slow water transmission 16 rate. Changes in soil properties caused by land management or climate changes also cause the hydrologic soil group to change. The influence of ground cover is treated independently. There are four hydrologic soil groups, A, B, C, and D, and three dual groups, A/D, B/D, and C/D. In the dual groups, the first letter is for drained areas and the second letter is for undrained areas. The four hydrologic soil groups are described in the following paragraphs: 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. Depth to the upper and lower boundaries of each layer is indicated. Texture is given in the standard terms used by the U.S. Department of Agriculture. These terms are defined according to percentages of sand, silt, and clay in the fraction of the soil that is less than 2 millimeters in diameter. "Loam," for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. If the content of particles coarser than sand is 15 percent or more, an appropriate modifier is added, for example, "gravelly." Classification of the soils is determined according to the Unified soil classification system (ASTM, 2005) and the system adopted by the American Association of State Highway and Transportation Officials (AASHTO, 2004). The Unified system classifies soils according to properties that affect their use as construction material. Soils are classified according to particle-size distribution of the fraction less than 3 inches in diameter and according to plasticity index, liquid limit, and organic matter content. Sandy and gravelly soils are identified as GW, GP, GM, GC, SW, SP, SM, and SC; silty and clayey soils as ML, CL, OL, MH, CH, and OH; and highly organic soils as PT. Soils exhibiting engineering properties of two groups can have a dual classification, for example, CL-ML. The AASHTO system classifies soils according to those properties that affect roadway construction and maintenance. In this system, the fraction of a mineral soil that is less than 3 inches in diameter is classified in one of seven groups from A-1 through A-7 on the basis of particle-size distribution, liquid limit, and plasticity index. Soils in group A-1 are coarse grained and low in content of fines (silt and clay). At the other extreme, soils in group A-7 are fine grained. Highly organic soils are classified in group A-8 on the basis of visual inspection. If laboratory data are available, the A-1, A-2, and A-7 groups are further classified as A-1-a, A-1-b, A-2-4, A-2-5, A-2-6, A-2-7, A-7-5, or A-7-6. As an additional refinement, the suitability of a soil as subgrade material can be indicated by a group Custom Soil Resource Report 17 index number. Group index numbers range from 0 for the best subgrade material to 20 or higher for the poorest. Percentage of rock fragments larger than 10 inches in diameter and 3 to 10 inches in diameter are indicated as a percentage of the total soil on a dry-weight basis. The percentages are estimates determined mainly by converting volume percentage in the field to weight percentage. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Percentage (of soil particles) passing designated sieves is the percentage of the soil fraction less than 3 inches in diameter based on an ovendry weight. The sieves, numbers 4, 10, 40, and 200 (USA Standard Series), have openings of 4.76, 2.00, 0.420, and 0.074 millimeters, respectively. Estimates are based on laboratory tests of soils sampled in the survey area and in nearby areas and on estimates made in the field. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Liquid limit and plasticity index (Atterberg limits) indicate the plasticity characteristics of a soil. The estimates are based on test data from the survey area or from nearby areas and on field examination. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). 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. Custom Soil Resource Report 18 Absence of an entry indicates that the data were not estimated. The asterisk '*' denotes the representative texture; other possible textures follow the dash. The criteria for determining the hydrologic soil group for individual soil components is found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/ OpenNonWebContent.aspx?content=17757.wba). Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Custom Soil Resource Report 19 Engineering Properties–Gallatin County Area, Montana Map unit symbol and soil name Pct. of map unit Hydrolo gic group Depth USDA texture Classification Pct Fragments Percentage passing sieve number—Liquid limit Plasticit y indexUnifiedAASHTO>10 inches 3-10 inches 4 10 40 200 In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H 448A—Hyalite- Beaverton complex, moderately wet, 0 to 2 percent slopes Hyalite 70 C 0-5 Loam CL-ML A-4 0- 0- 0 0- 5- 10 95-98-1 00 90-95-1 00 75-85- 95 55-65- 75 25-28 -30 5-8 -10 5-9 Clay loam, loam, silty clay loam CL A-6 0- 0- 0 0- 5- 10 90-95-1 00 85-93-1 00 75-83- 90 60-70- 80 30-33 -35 10-13-1 5 9-17 Clay loam, silty clay loam, gravelly loam CL, GC, SC A-6 0- 0- 0 0- 8- 15 65-80- 95 60-75- 90 55-68- 80 40-58- 75 30-33 -35 10-13-1 5 17-26 Very cobbly sandy clay loam, very cobbly sandy loam, extremely cobbly sandy loam GM, SM A-1, A-2 0- 0- 0 30-43- 55 35-50- 65 30-45- 60 20-35- 50 10-18- 25 20-28 -35 NP-5 -10 Custom Soil Resource Report 20 Engineering Properties–Gallatin County Area, Montana Map unit symbol and soil name Pct. of map unit Hydrolo gic group Depth USDA texture Classification Pct Fragments Percentage passing sieve number—Liquid limit Plasticit y indexUnifiedAASHTO>10 inches 3-10 inches 4 10 40 200 In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H 26-60 Very cobbly loamy sand, very cobbly sand, extremely cobbly coarse sand GP-GM, SP-SM, GM, SM A-1 0- 0- 0 30-43- 55 35-50- 65 30-45- 60 15-28- 40 5-10- 15 —NP Beaverton 20 B 0-5 Cobbly loam CL-ML, SC-SM A-4 0- 0- 0 15-23- 30 75-85- 95 70-80- 90 60-70- 80 45-55- 65 25-28 -30 5-8 -10 5-21 Very cobbly clay loam, very cobbly sandy clay loam, very gravelly clay loam GC-GM, SC-SM, GC, SC A-2, A-4, A-6 0- 0- 0 20-30- 40 45-58- 70 40-50- 60 35-45- 55 20-30- 40 25-30 -35 5-10-15 21-25 Very cobbly coarse sandy loam GP-GM, SP-SM, GM, SM A-1 0- 0- 0 25-38- 50 30-53- 75 20-43- 65 10-30- 50 5-10- 15 —NP 25-60 Extremely cobbly loamy coarse sand, extremely gravelly sand, very cobbly loamy sand GP-GM, SP-SM, GM, SM A-1 0- 0- 0 25-38- 50 30-53- 75 20-43- 65 10-30- 50 5-10- 15 —NP Custom Soil Resource Report 21 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 22 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 23 APPENDIX F: SUBDIVISION STORM INFORMATION No. REVISIONSFile Name: IMEG Project No: Date: Drawn By: Checked By: Sheet of DESCRIPTION DATECOPYRIGHTALL RIGHTS RESERVEDC24000865.00 - DA Map.dwg2024Field Book No: 1143 STONERIDGE DRIVE, SUITE 1 BOZEMAN, MT 59718 PH: 406.587.1115 www.imegcorp.com UNIVERSITY CROSSINGS BOZEMAN, MONTANA DRAINAGE AREA MAP24000865.00MJHEDG06/18/2024DA11N/A INSPECTION AND MAINTENANCE FOR STORMWATER MANAGEMENT FACILITIES University Crossing Property Owners Association shall be responsible for the maintenance of the stormwater drainage facilities included within the Lot 1A-1, Minor Subdivision No. and as identified in the attached exhibit. The facilities drain the shared drive access and a portion of the existing and proposed parking lots. Storm Water Facilities: 1. Drainage swales slope toward retention and detention ponds to collect storm water runoff and channel it to the retention or detention pond. 2. Pipe Networks convey storm water to different discharge locations underground. 3. Outlets are points where storm water exits a pipe network. 4. Retention Ponds are storm water collection facilities that collect and temporarily store runoff and allow it to infiltrate and evaporate. 5. Storm Tech Chambers are subsurface infiltration structures that temporarily store runoff and allow it to infiltrate. Post Construction Inspection: 1. Observe that drywells, and catch basins are clear of any material or obstructions in the drainage slots. Inspect these structures to insure proper drainage following a storm event. Immediately identify and remove objects responsible for clogging if not draining properly. Semi-Annual Inspection: 1. Check retention facilities three days following a storm event exceeding ¼ inch of precipitation. Failure for water to percolate within this time period indicates clogging or poor-draining soils. Clear any clogs and replace any poor-draining soils with well- draining gravely soils. 2. Check for grass clippings, litter, and debris in drainage swales, catch basins, dry wells, culverts and retention ponds. Flush and/or vacuum drywells or storm water pipes if excessive material is observed in the facilities. Standard Maintenance: 1. Remove sediment and oil/grease from retention facilities. 2. Inspect and remove debris from drainage swales, catch basins, dry wells, and retention ponds. Use a vacuum truck to clean catch basins and dry wells. 3. Monitor health of vegetation and revegetate as necessary to maintain full vegetative cover. 4. Inspect for the following issues: differential accumulation of sediment, drain time, signs of petroleum hydrocarbon contamination (odors, oil sheen in pond water), standing water, trash and debris. Stormtech Maintenance: 1. STEP 1) INSPECT ISOLATOR ROW PLUS FOR SEDIMENT a. INSPECTION PORTS (IF PRESENT) i. REMOVE/OPEN LID ON NYLOPLAST INLINE DRAIN ii. REMOVE AND CLEAN FLEXSTORM FILTER IF INSTALLED iii. USING A FLASHLIGHT AND STADIA ROD, MEASURE DEPTH OF SEDIMENT AND RECORD ON MAINTENANCE LOG iv. LOWER A CAMERA INTO ISOLATOR ROW PLUS FOR VISUAL INSPECTION OF SEDIMENT LEVELS (OPTIONAL) v. IF SEDIMENT IS AT, OR ABOVE, 3" (80 mm) PROCEED TO STEP 2. IF NOT, PROCEED TO STEP 3. b. ALL ISOLATOR PLUS ROWS c. REMOVE COVER FROM STRUCTURE AT UPSTREAM END OF ISOLATOR ROW PLUS d. USING A FLASHLIGHT, INSPECT DOWN THE ISOLATOR ROW PLUS THROUGH OUTLET PIPE i. MIRRORS ON POLES OR CAMERAS MAY BE USED TO AVOID A CONFINED SPACE ENTRY ii. FOLLOW OSHA REGULATIONS FOR CONFINED SPACE ENTRY IF ENTERING MANHOLE e. IF SEDIMENT IS AT, OR ABOVE, 3" (80 mm) PROCEED TO STEP 2. IF NOT, PROCEED TO STEP 3. 2. STEP 2) CLEAN OUT ISOLATOR ROW PLUS USING THE JETVAC PROCESS a. FIXED CULVERT CLEANING NOZZLE WITH REAR FACING SPREAD OF 45" (1.1 m) OR MORE IS PREFERRED b. APPLY MULTIPLE PASSES OF JETVAC UNTIL BACKFLUSH WATER IS CLEAN c. VACUUM STRUCTURE SUMP AS REQUIRED 3. STEP 3) REPLACE ALL COVERS, GRATES, FILTERS, AND LIDS; RECORD OBSERVATIONS AND ACTIONS. 4. STEP 4) INSPECT AND CLEAN BASINS AND MANHOLES UPSTREAM OF THE STORMTECH SYSTEM. 5. NOTES: a. INSPECT EVERY 6-MONTHS DURING THE FIRST YEAR OF OPERATION. ADJUST THE INSPECTIN INTERVAL BASED ON PREVIOUS OBSERVATION OF SEDIMENT ACCUMULATION AND HIGH-WATER ELEVATIONS b. CONDUCT JETTING AND VACTORING ANNUALLY OR WHEN INSPECTION SHOWS THAT MAINTENANCE IS NECASSARY Sediment accumulation: In most cases, sediment from a retention pond or infiltration chambers does not contain toxins at levels posing a hazardous concern. However, sediments should be tested for toxicants in compliance with current disposal requirements and if land uses in the drainage area include commercial or industrial zones, or if visual or olfactory indications of pollution are noticed. Sediments containing high levels of pollutants should be disposed of in accordance with applicable regulations and the potential sources of contamination should be investigated and contamination practices terminated. Equipment Type/Access: Ponds and Stormtech will be cleaned using vacuum trucks or other equipment. All vacuum trucks will access the site through the proposed drive aisle and parking lot. Cost Estimate: Depending on the amount of rainfall in the given year, the cost to maintain the stormwater infrastructure will vary. It is estimated that the infiltration chamber and drywell will need to be have sediment removed once per year, with an estimated cost of $3,000 to do so. University Crossing Property Owners Association will be responsible for financing the maintenance of the stormwater infrastructure. EXHIBIT STORMWATER DRAINAGE MAP No. REVISIONSFile Name: IMEG Project No: Date: Drawn By: Checked By: Sheet of DESCRIPTION DATECOPYRIGHTALL RIGHTS RESERVEDC24000865.00 - DA Map.dwg2024Field Book No: 1143 STONERIDGE DRIVE, SUITE 1 BOZEMAN, MT 59718 PH: 406.587.1115 www.imegcorp.com UNIVERSITY CROSSINGS BOZEMAN, MONTANA DRAINAGE AREA MAP24000865.00MJHEDG06/18/2024DA11N/A G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 MEMO The stormwater design for University Crossings proposed Minor Subdivision #503 is applying for a site plan modification to City of Bozeman planning file number 21- 327 to accommodate site design changes. Drainage design continues to use the 10-year, 2-hour design storm specified by City of Bozeman Design Standards and Specifications Policy (DSSP) Section II as shown in Appendix B. Drainage Areas 5 and 6 are unchanged in area and are not included in this report, as these areas are managed by others as part of the Kagy Boulevard improvements (Modified Drainage Map, Appendix A). Originally proposed underground Chambers A, C, and D of the StormTech system are redesigned as Ponds # 3, 4 and 5 to accommodate the post-development Water Quality Volume. The analysis of pond capacity is conducted based on the contributing area’s total hardscaped (impervious) and landscape (pervious) area and the 10- year, 2-hour storm event. Drainage Areas (DA) # 1, 2.0, and 2.1 experience the most substantial boundary change; the divides are redrawn to the internal road, strategically adding ponds for surface drainage. The modifications result in a 7,754 SF gain of hardscape and a 8,477 SF loss in landscape for a total additional stormwater volume of 1157 CF. The subsequent items describe changes in contributing area and storage capacity for each stormwater structure. Pond #1 is consistent in location with the previously proposed pond and has a capacity of 391 CF. The capacity increases by 2 CF to accommodate runoff from the contributing basin, DA #4. The distribution and size of DA #4 is modified. The boundary is redrawn 86 SF smaller, and it loses 280 SF of landscaping to 194 SF of hardscape. The tables below include data comparing the original and modified structure and drainage area contributing to Pond #1. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF Pond #1 365 389 374 391 2 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#4 4,149 7,394 4,343 7,114 194 -280 To: City Reviewer From: Paloma R. Burger and Erik Garberg, PE Subject: Stormwater Management Design Modification IMEG #: 24000865.00 / C&H #210228 Project: University Crossings Minor Subdivision #503 C.O.B. Planning File Number 21- 327 Date: July 19, 2024 City Reviewer July 15, 2024 Page 2 of 6 G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Chamber B is consistent in location with the previously proposed chamber. The chamber capacity does not change from 935 CF. This structure will receive the runoff from the contributing basin, DA #3. The distribution and size of DA #3 is modified. The boundary is redrawn 30 SF smaller, and it loses 69 SF of hardscaping to 39 SF of landscape. The tables below include data comparing the original and modified structure and drainage area distribution contributing to Chamber B. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF Chamber B 852 935 849 935 0 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#3 21,421 1,895 21,352 1,934 -69 39 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Pond #2 has a capacity of 906 CF and stays consistent in location with the previously proposed Pond #2. The capacity increases by 153 CF to accommodate the runoff from the contributing basin, DA #8. The distribution and size of DA #8 changes. The boundary is redrawn 19 SF larger, and it loses 26 SF of landscape to 45 SF of hardscaping. The tables below include data comparing the original and modified structure and drainage area distribution contributing to Pond #2. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF Pond #2 570 753 573 906 153 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#8 7,787 5,316 7,832 5,290 45 -26 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Pond #3 replaces Chamber D and has a capacity of 1,367 CF. The capacity of this structure increases by 242 CF to accommodate the runoff from the contributing basin, DA #1. The distribution and size of DA #1 is modified. The boundary is redrawn 28,868 SF smaller, and it loses 10,789 SF of hardscape and 18,079 City Reviewer July 15, 2024 Page 3 of 6 G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 SF of landscaping. The tables below include data comparing the original and modified structure and drainage area distribution contributing to Pond #3. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF Pond #3/ Chamber D 1,010 1,125 1,277 1,367 242 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#1 42,716 24,434 31,927 6,355 -10,789 -18,079 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Pond #4 has a capacity of 847 CF and partially replaces Chamber A. This structure is designed to receive the runoff from the contributing basin, DA #2.1. The distribution and size of DA #2.1 is modified. The boundary is redrawn 9,774 SF larger, and it gains 6,658 SF of hardscaping and 3,116 SF of landscape. Pond #5 has a capacity of 1,070 CF and partially replaces Chamber A. This structure is designed to receive the runoff from the contributing basin, DA #2.0. The distribution and size of DA #2.0 is modified. The boundary is redrawn 18,402 SF larger, and it gains 11,649 SF of hardscaping and 6,753 SF of landscape. Pond #4 and #5 exceed the previously proposed Chamber A’s volume by 812 CF. The tables below include data comparing the original and modified structure and drainage area distribution contributing to Pond #4 and #5. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF Pond#4/ Chamber A 2,683 2,729 751 847 812 Pond#5/ Chamber A 1,055 1,070 City Reviewer July 15, 2024 Page 4 of 6 G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#2.0 12,595 3,718 24,244 10,471 11,649 6,753 DA#2.1 10,896 1,798 17,554 4,914 6,658 3,116 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Dry Well #1 has a capacity of 206 CF and is designed to receive runoff from the contributing basin, DA #7. The structure experiences a 12 CF increase in capacity from previous. The distribution and size of DA #7 is modified. The boundary is redrawn 66 SF larger, and all 66 SF is allocated to hardscape. Original (Old) Modified (New) Change in Proposed Volume Required Capacity Proposed Capacity Required Capacity Proposed Capacity CF CF DW #1 183 194 187 206 12 Original (Old) Modified (New) Change in Hardscaped Area Change in Landscaped Area Hardscape Area Landscape Area Hardscape Area Landscape Area SF SF DA#7 2,676 878 2,742 878 66 0 All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. City Reviewer July 15, 2024 Page 5 of 6 G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 Pond Summary Table: The change in pond volumes between original and modified plans is summarized in the table below: All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Original (Old) Modified (New) Required Capacity Provided Capacity Required Capacity Provided Capacity CF Pond #1 365 389 374 391 Pond #2 570 753 573 906 Chamber B 852 935 849 935 Pond #3/ Chamber D 1,010 1,125 1,277 1,367 Pond#4/ Chamber A 2,683 2,729 751 847 Pond#5/ Chamber A 1,055 1,070 DW #1 183 194 187 206 Change in Provided Volume Change in Required Volume CF Pond #1 2 9 Pond #2 153 3 Chamber B 0 -3 Pond #3/ Chamber D 242 267 Pond#4/ Chamber A 812 877 Pond#5/ Chamber A DW #1 12 4 1221 1157 Totals City Reviewer July 15, 2024 Page 6 of 6 G:\2024\24000865.00\Design\Civil\ENG DESIGN\5_DEQ8 (Storm Drainage)\24000865.00-MOD Stormwater-Memo 20241016.docx Memo July 15, 2024 Drainage Area Summary Table: The change in drainage areas between original and modified plans is summarized in the table below: Note that negative values denote loss in area and positive values denote gain in area. All values obtained from the Original and Modified Drainage Area Map in Appendix A and the Modified Storm Calculations in Appendix B. Original (Old) Modified (New) Hardscape Area Landscape Area Total Area Hardscape Area Landscape Area Total Area SF SF DA#1 42,716 24,434 67,150 31,927 6,355 38,282 DA#2.0 12,595 3,718 16,313 24,244 10,471 34,715 DA#2.1 10,896 1,798 12,694 17,554 4,914 22,468 DA#3 21,421 1,895 23,316 21,352 1,934 23,286 DA#4 4,149 7,394 11,543 4,343 7,114 11,457 DA#7 2,676 878 3,554 2,742 878 3,620 DA#8 7,787 5,316 13,103 7,832 5,290 13,122 Change in Hardscaped Area Change in Landscaped Area Change in Total Area SF DA#1 -10,789 -18,079 28,868 DA#2.0 11,649 6,753 -18,402 DA#2.1 6,658 3,116 -9,774 DA#3 -69 39 30 DA#4 194 -280 86 DA#7 66 0 -66 DA#8 45 -26 -19 7,754 -8,477 723 Totals No. REVISIONSFile Name: IMEG Project No: Date: Drawn By: Checked By: Sheet of DESCRIPTION DATECOPYRIGHTALL RIGHTS RESERVEDC24000865.00 - DA Map.dwg2024Field Book No: 1143 STONERIDGE DRIVE, SUITE 1 BOZEMAN, MT 59718 PH: 406.587.1115 www.imegcorp.com UNIVERSITY CROSSINGS BOZEMAN, MONTANA DRAINAGE AREA MAP24000865.00MJHEDG05/13/2024DA11N/A RUNOFF VOLUME FROM DA#1 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 6355 1271 Hardscape 0.95 31927 30330 Total 38281 31601 A = Area (acres)0.88 C = Weighted C Factor 0.83 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.83 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.88 Q = RUNOFF (cfs)0.30 V = REQUIRED VOL (ft3)2130 V = PROVIDED VOL (ft3)1367 PROVIDED BY POND 3 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #1 Contributing Area Area (ft2)Hardscape 31927 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.80 0.05 + 0.9*I I = Percent impervious cover (decimal)0.83 decimal A = Entire drainage area 0.88 acres RRV = Runoff Reduction Volume 0.0293 acre-ft RRV = Runoff Reduction Volume 1277 cubic feet Because the runoff volume from the 10-yr, 2-hr storm (for flood control) is greater than the runoff volume produced by the half inch rainfall (for water quality) the larger runoff volume is used (3065 cf). Check the quantity of stormwater allocated from DA 1 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 1 Tc Overland Flow Tc = 1.87 (1.1-CCf )D 1/2 /S 1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)CfC = Rational Method Runoff Coefficient 0.95 2 to 10 1Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 104 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.3 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R 2/3 S 1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 0.72% L = length of gutter (ft) 321 V = mean velocity (ft/s) 2.54 Tc Gutter Flow (minutes) =2.1 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.83 (calculated above) I = .78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.88 (calculated above) Q = Pro Flow (cfs)2.78 (assuming no carry flow) Detention Pond # 3 DA # 1 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 1 0.95 31927 30330 Landscape 1 0.20 6355 1271 Total 38281 31601 A = Area (acres) 0.88 Storm C = Weighted C Factor 0.83 Return (yrs)Cf2 to 101 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) = 60.58 Infiltration Width (ft) = 7.48 Infiltration Area (sf) = 453.1384 Total Area (acres) =0.88 acres Weighted C =0.83 Discharge Rate (cfs) =0.16 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3)60 1.00 0.64 0.46 1671 563 1108.83 61 1.02 0.63 0.46 1681 572 1109.15 62 1.03 0.63 0.45 1691 581 1109.37 63 1.05 0.62 0.45 1700 591 1109.49 64 1.07 0.61 0.45 1710 600 1109.51 65 1.08 0.61 0.44 1719 610 1109.43 66 1.10 0.60 0.44 1728 619 1109.27 67 1.12 0.60 0.43 1737 628 1109.01 68 1.13 0.59 0.43 1746 638 1108.66 69 1.15 0.58 0.42 1755 647 1108.23 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft2)Hardscape 31927 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.80 0.05 + 0.9*I I = Percent impervious cover (decimal)0.83 decimal A = Entire drainage area 0.88 acres RRV = Runoff Reduction Volume 0.0293 acre-ft RRV = Runoff Reduction Volume 1277 cubic feet PROVIDED VOLUME (ft3 ) =1,367 1/2" VOLUME REQ.(ft3 ) =1277 Contorling Volume DETENTION VOLUME REQ.(ft3)=1110 RUNOFF VOLUME FROM DA#2.0 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 10471 2094 Hardscape 0.95 24244 23031 Total 34714 25126 A = Area (acres)0.80 C = Weighted C Factor 0.72 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.72 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.80 Q = RUNOFF (cfs)0.24 V = REQUIRED VOL (ft3)1694 V = PROVIDED VOL (ft3)1040 PROVIDED BY POND 5 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #2 Contributing Area Area (ft2)Hardscape 24244 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.68 0.05 + 0.9*I I = Percent impervious cover (decimal)0.70 decimal A = Entire drainage area 0.80 acres RRV = Runoff Reduction Volume 0.0225 acre-ft RRV = Runoff Reduction Volume 981 cubic feet Because the runoff volume from the 10-yr, 2-hr storm (for flood control) is greater than the runoff volume produced by the half inch rainfall (for water quality) the proposed retention facility is sized to handle the larger volume (857 cf). Check the quantity of stormwater allocated from DA 2 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 2 Tc Overland Flow Tc = 1.87 (1.1-CCf )D 1/2 /S 1/3 Storm S = Slope of Basin (%) 1.8% Return (yrs)CfC = Rational Method Runoff Coefficient 0.95 2 to 10 1Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 108 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.6 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R 2/3 S 1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 1.68% L = length of gutter (ft) 100 V = mean velocity (ft/s) 3.89 Tc Gutter Flow (minutes) =0.4 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.72 (calculated above) I = .78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.80 (calculated above) Q = Pro Flow (cfs)2.21 (assuming no carry flow) Detention Pond # 5 DA # 2.0 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 2 0.95 24244 23031 Landscape 2 0.20 10471 2094 Total 34714 25126 A = Area (acres) 0.80 Storm C = Weighted C Factor 0.72 Return (yrs)Cf2 to 101 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) = 64.97 Infiltration Width (ft) = 3.98 Infiltration Area (sf) = 258.5806 Total Area (acres) =0.80 acres Weighted C =0.72 Discharge Rate (cfs) =0.09 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3)102 1.70 0.45 0.26 1600 546 1054.37 103 1.72 0.45 0.26 1606 551 1054.49 104 1.73 0.45 0.26 1611 557 1054.58 105 1.75 0.44 0.26 1616 562 1054.63 106 1.77 0.44 0.26 1622 567 1054.66 107 1.78 0.44 0.25 1627 573 1054.64 108 1.80 0.44 0.25 1633 578 1054.60 109 1.82 0.43 0.25 1638 583 1054.52 110 1.83 0.43 0.25 1643 589 1054.41 111 1.85 0.43 0.25 1648 594 1054.28 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft2)Hardscape 24244 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.68 0.05 + 0.9*I I = Percent impervious cover (decimal)0.70 decimal A = Entire drainage area 0.80 acres RRV = Runoff Reduction Volume 0.0225 acre-ft RRV = Runoff Reduction Volume 981 cubic feet PROVIDED VOLUME (ft3 ) =1,070 1/2" VOLUME REQ.(ft3 ) =981 DETENTION VOLUME REQ.(ft3)=1055 Contorling Volume RUNOFF VOLUME FROM DA#2.1 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 3928 786 Hardscape 0.95 18539 17612 Total 22467 18398 A = Area (acres)0.52 C = Weighted C Factor 0.82 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.82 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.52 Q = RUNOFF (cfs)0.17 V = REQUIRED VOL (ft3)1240 V = PROVIDED VOL (ft3)1251 PROVIDED BY POND 4 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #2 Contributing Area Area (ft2)Hardscape 18539 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.79 0.05 + 0.9*I I = Percent impervious cover (decimal)0.83 decimal A = Entire drainage area 0.52 acres RRV = Runoff Reduction Volume 0.0170 acre-ft RRV = Runoff Reduction Volume 742 cubic feet Because the runoff volume from the 10-yr, 2-hr storm (for flood control) is greater than the runoff volume produced by the half inch rainfall (for water quality) the proposed retention facility is sized to handle the larger volume (722 cf). Check the quantity of stormwater allocated from DA 2.1 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 2.1 Tc Overland Flow Tc = 1.87 (1.1-CCf )D 1/2 /S 1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)CfC = Rational Method Runoff Coefficient 0.95 2 to 10 1Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 90.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.2 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R 2/3 S 1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 2.00% L = length of gutter (ft) 100 V = mean velocity (ft/s) 4.24 Tc Gutter Flow (minutes) =0.4 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.82 (calculated above) I = .78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.52 (calculated above) Q = Pro Flow (cfs)1.62 (assuming no carry flow) Detention Pond # 4 DA # 2.1 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 2.1 0.95 18539 17612 Landscape 2.1 0.20 3928 786 Total 22467 18398 A = Area (acres) 0.52 Storm C = Weighted C Factor 0.82 Return (yrs)Cf2 to 101 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) = 49.99 Infiltration Width (ft) = 3.99 Infiltration Area (sf) = 199.4601 Total Area (acres) =0.52 acres Weighted C =0.82 Discharge Rate (cfs) =0.07 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3)94 1.57 0.48 0.20 1139 388 750.68 95 1.58 0.47 0.20 1143 392 750.78 96 1.60 0.47 0.20 1147 396 750.85 97 1.62 0.47 0.20 1151 400 750.89 98 1.63 0.47 0.20 1155 405 750.90 99 1.65 0.46 0.20 1160 409 750.89 100 1.67 0.46 0.19 1164 413 750.85 101 1.68 0.46 0.19 1168 417 750.78 102 1.70 0.45 0.19 1172 421 750.68 103 1.72 0.45 0.19 1176 425 750.56 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft2)Hardscape 18539 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.79 0.05 + 0.9*I I = Percent impervious cover (decimal)0.83 decimal A = Entire drainage area 0.52 acres RRV = Runoff Reduction Volume 0.0170 acre-ft RRV = Runoff Reduction Volume 742 cubic feet PROVIDED VOLUME (ft3 ) =847 1/2" VOLUME REQ.(ft3 ) =742 DETENTION VOLUME REQ.(ft3)=751 Contorling Volume DRAINAGE AREA # 3 RUNOFF VOLUME FROM DA#3 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2 ) C * Area Landscape 0.2 1933 387 Hardscape 0.95 21352 20285 Total 23285 20671 A = Area (acres)0.53 C = Weighted C Factor 0.89 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.89 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.53 Q = RUNOFF (cfs)0.19 V = REQUIRED VOL (ft3)1394 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft2)Hardscape 21352 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.88 0.05 + 0.9*I I = Percent impervious cover (decimal)0.92 decimal A = Entire drainage area 0.53 acres RRV = Runoff Reduction Volume 0.0195 acre-ft RRV = Runoff Reduction Volume 849 cubic feet Check the quantity of stormwater allocated from DA 3 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 3 Tc Overland Flow Tc = 1.87 (1.1-CCf )D 1/2 /S 1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)CfC = Rational Method Runoff Coefficient 0.95 2 to 10 1Cf = Frequency Adjustment Factor 1 11 to 25 1.1 D = Length of Basin (ft) 170 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)2.4 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R 2/3 S 1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 2.00% L = length of gutter (ft) 100 V = mean velocity (ft/s) 4.24 Tc Gutter Flow (minutes) =0.4 Tc Total = 5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.89 (calculated above) I = .78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.53 (calculated above) Q = Pro Flow (cfs)1.82 (assuming no carry flow) InputType of Grate 2'x3' Curb Inlet High FlowHead (ft) 0.3PropertiesOrifice Flow Area (in)425.88Orifice Flow Area (ft)2.96Weir Flow Perimeter (in)124.32Weir Flow Perimeter (ft)10.36SolutionCapacity (cfs)5.67Capacity (gpm)2544.13REV2.1.21 Nyloplast Inlet Capacity TableDISCLAIMER: SAFETY FACTORS ARE NOT INCLUDED IN THESE CALCULATIONS. ACTUAL CALCULATIONS SHOULD BE CARRIED OUT AND VERIFIED BY THEDESIGN ENGINEER TAKING INTO ACCOUNT ALL LOCAL CONDITIONS. NYLOPLAST RECOMMENDS USING A MINIMUM SAFETY FACTOR OF 1.25 FORPAVED AREAS AND 2.0 FOR TURF AREAS. ADS/NYLOPLAST IS NOT RESPONSIBLE FOR MISUSE OF THIS TOOL. Chamber B DA # 3 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 3 0.95 21352 20285 Landscape 3 0.20 1933 387 Total 23285 20671 A = Area (acres) 0.53 Storm C = Weighted C Factor 0.89 Return (yrs)Cf2 to 101 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) = 37 Infiltration Width (ft) = 16 Infiltration Area (sf) = 592 Total Area (acres) =0.53 acres Weighted C =0.89 Discharge Rate (cfs) =0.20 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3)17 0.28 1.45 0.69 703 208 494.91 18 0.30 1.40 0.66 717 221 496.86 19 0.32 1.35 0.64 731 233 498.32 20 0.33 1.31 0.62 744 245 499.31 21 0.35 1.27 0.60 757 257 499.88 22 0.37 1.23 0.58 770 270 500.06 23 0.38 1.19 0.57 782 282 499.87 24 0.40 1.16 0.55 793 294 499.35 25 0.42 1.13 0.54 805 306 498.52 26 0.43 1.10 0.52 816 319 497.39 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft2)Hardscape 21352 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.88 0.05 + 0.9*I I = Percent impervious cover (decimal)0.92 decimal A = Entire drainage area 0.53 acres RRV = Runoff Reduction Volume 0.0195 acre-ft RRV = Runoff Reduction Volume 849 cubic feet PROVIDED VOLUME (ft3)935 1/2" VOLUME REQ.=849 DETENTION VOLUME REQ.=499.88 RUNOFF VOLUME FROM DA#4 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 7114 1423 Hardscape 0.95 4343 4126 Total 11457 5549 A = Area (acres)0.26 C = Weighted C Factor 0.48 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.48 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.26 Q = RUNOFF (cfs)0.05 V = REQUIRED VOL (ft3)374 V = PROVIDED VOL (ft3)391 PROVIDED BY POND 1 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #4 Contributing Area Area (ft2)Hardscape 4343 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.39 0.05 + 0.9*I I = Percent impervious cover (decimal)0.38 decimal A = Entire drainage area 0.26 acres RRV = Runoff Reduction Volume 0.0043 acre-ft RRV = Runoff Reduction Volume 187 cubic feet PROVIDED VOLUME (ft3)389 1/2" VOLUME REQ.=187 RETENTION VOLUME REQ.=391.00 Check the quantity of stormwater allocated from DA 4 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 4 Tc Overland Flow Tc = 1.87 (1.1-CCf )D 1/2 /S 1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)CfC = Rational Method Runoff Coefficient 0.95 2 to 10 1Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 90.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.2 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R 2/3 S 1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 2.00% L = length of gutter (ft) 100 V = mean velocity (ft/s) 4.24 Tc Gutter Flow (minutes) =0.4 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.48 (calculated above) I = .64 Tc -0.65 (in/hr)3.22 (25-yr storm) A = area (acres) 0.26 (calculated above) Q = Pro Flow (cfs)0.41 (assuming no carry flow) RUNOFF VOLUME FROM DA#7 *just plot DW PAGE this one is redundant 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 878 176 Hardscape 0.95 2742 2605 Total 3621 2781 A = Area (acres)0.08 C = Weighted C Factor 0.77 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.77 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.08 Q = RUNOFF (cfs)0.03 V = REQUIRED VOL (ft3)187 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #7 Contributing Area Area (ft2)Hardscape 2742 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.73 0.05 + 0.9*I I = Percent impervious cover (decimal)0.76 decimal A = Entire drainage area 0.08 acres RRV = Runoff Reduction Volume 0.0025 acre-ft RRV = Runoff Reduction Volume 110 cubic feet RUNOFF VOLUME FROM DA#7 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 878 176 Hardscape 0.95 2742 2605 Total 3621 2781 A = Area (acres)0.08 C = Weighted C Factor 0.77 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.77 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.08 Q = RUNOFF (cfs)0.03 V = REQUIRED VOL (ft3)187 CURB INLET PIPE ROUTED TO DRYWELL 1 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2)C * Area LANDSCAPE 7 0.2 878 176 HARDSCAPE 7 0.95 2742 2605 Total 3621 2781 A = Area (acres) 0.08 C = Weighted C Factor 0.77 2. Calculate Tc (Time to Concentration) Tc Total = 5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.77 (calculated above) I = 0.78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.08 (calculated above) Q 25-yr Flow Rate (cfs)=0.24 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: DW 1 Pipe Location: DW 1 INPUT D= 12 inches d= 11.26 inches Mannings Formula n= 0.013 mannings =57.7 degrees Q=(1.486/n)ARh 2/3S 1/2 S= 0.009 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh 2/3S 1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.77 2.64 0.29 5.00 3.82 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values dD RUNOFF VOLUME FROM DA#8 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 5290 1058 Hardscape 0.95 7832 7440 Total 13122 8498 A = Area (acres)0.30 C = Weighted C Factor 0.65 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.65 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.30 Q = RUNOFF (cfs)0.08 V = REQUIRED VOL (ft3)573 V = PROVIDED VOL (ft3)906 PROVIDED BY POND 2 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #4 Contributing Area Area (ft2)Hardscape 7832 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv *A]/12 P = Water quality rainfall depth 0.50 inchesRv = Dimensionless runoff coefficient 0.59 0.05 + 0.9*I I = Percent impervious cover (decimal)0.60 decimal A = Entire drainage area 0.30 acres RRV = Runoff Reduction Volume 0.0074 acre-ft RRV = Runoff Reduction Volume 321 cubic feet DRAINAGE AREA # 8 ROOF DOWNSPOUT PIPE ROUTED TO RETENTION POND 2 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2)C * Area Hardscape 8 0.95 7832 7440 Total 7832 7440 A = Area (acres) 0.18 C = Weighted C Factor 0.95 2. Calculate Tc (Time to Concentration) Tc Total = 5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.95 (calculated above) I = 0.78 Tc -0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.18 (calculated above) Q 25-yr Flow Rate (cfs)=0.65 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: Pond #2 Location: Pond #2 INPUT D= 6 inches d= 5.63 inches Mannings Formula n= 0.013 mannings =57.7 degrees Q=(1.486/n)ARh 2/3S 1/2 S= 0.015 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh 2/3S 1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.19 1.32 0.15 4.02 0.77 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values dD UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 1 TABLE OF CONTENTS REPORT Introduction ..........................................................................................................................2 Existing Site & Stormwater .................................................................................................2 Stormwater Design...............................................................................................................2 Groundwater Considerations ...............................................................................................3 Falling Head Percolation Tests ............................................................................................3 Drainage Areas.....................................................................................................................4 Infiltration Chamber Design ................................................................................................7 APPENDICES Appendix A: Drainage Area Map Appendix B: Storm Sewer Facilities Calculations Appendix C: GW Monitoring Data Appendix D: Stormwater Facility Maintenance Plans UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 2 INTRODUCTION This project includes the proposed development of Lot 1A-1, a portion of Lot 2A (undeveloped) and Lot 3 (Crowley Fleck Law Office property). The proposed development includes the construction of two apartment buildings (59 total units), surrounding parking lot, a fire lane connecting to an existing parking lot, and demolition of an existing stormwater pond. The property is located within the Bozeman city limits and is currently zoned B-2 commercial. A combination of site grading, curb and gutter, storm chases, drywells, and underground infiltration chambers will be used to manage stormwater runoff on the site. EXISTING SITE The property for the proposed development (Lot 1A-1) generally slopes from south to north and is currently undeveloped. The existing retention pond is located on the north end of the property along the existing drive approach. The existing law office building (Lot 3, Drainage Area 0) drains to a drywell and the remainder of the site drains to the existing retention pond (V=4,094 ft3). The existing pond will be removed and replaced with a StormTech infiltration system to account for the lost storage volume. STORMWATER DESIGN Stormwater runoff from the proposed improvements will be conveyed via curb and gutter channel flow to a series of curb chases and storm sewer inlets. It will then be routed through storm drainage pipes to detention and retention facilities for storage. StormTech chambers A&B will act in detention along with storing adequate runoff for the half inch requirement. These chambers will release runoff through infiltration at a rate determined by the falling head percolation tests. The time of concentration for all of the drainage areas were assumed to be less than 5 mins. A post development Drainage Area Map is included in Appendix A, and calculations for pond/chamber sizing for each of the post development drainage areas (total area, weighted C factor, required and provided storage volumes, and discharge rates) are included in Appendix B. StormTech chambers C & D will retain runoff from Kagy Boulevard (Drainage Areas 5 & 6). UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 3 Storm sewer facilities were sized for the 25-yr storm using Manning’s Equation, and for each inlet, the contributing area, gutter capacity, weighted C factor, and time of concentration were calculated. These values were input into Manning’s Equation to check capacity and flow characteristics for inlets, storm drain pipes, and curb gutters. All curb gutters were designed to maintain 0.15’ freeboard per C.O.B. Design Manual Section IV.C.5. GROUNDWATER CONSIDERATIONS Three groundwater (GW) monitoring wells were installed across Lot 1A-1 and Lot 2A and have been regularly inspected this past spring to record fluctuations in the groundwater elevation during a typical peak season for groundwater. The GW monitoring results are included in Appendix C for reference. The peak GW depth from the three wells found the seasonal high ground water to be 4.59’ below ground surface (July 9, 2021). FALLING HEAD PERCOLATION TESTS In order to determine the infiltration rate of the soils underlying the project area a series of falling head percolation tests were performed across the site. Each of these tests was performed on the native gravels underlying the site, which is the proposed infiltrative surface for the proposed StormTech infiltration systems. A total of six falling head percolation tests were performed at two different locations. Attached is an aerial map showing the locations of the percolation tests. For each falling head percolation test, an excavator was used to excavate a test hole down to the native gravel elevation. Next, 4-inch Diameter PVC was embedded 6 inches into the native gravel layer in order to limit horizontal migration of the water in order to more accurately determine the vertical infiltration rate of the gravel layer. Once the PVC pipe was installed approximately 5 to 10 gallons of water was poured into the pipe and allowed to infiltrate the gravel to pre-soak the soil before taking actual measurements of the infiltration rate. Following the pre-soak, the PVC pipe was filled with water and then the time to drain was measured. This process was repeated three times at each test location. The following tables provide a summary of the testing results: UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 4 Percolation Test Location #1 Test # Depth of Water (in) Time to Drain (min) Infiltration Rate (in/min) Infiltration Rate (in/hr) 1 24 23.42 1.02 61.20 2 18 8.10 2.22 133.20 3 20 8.20 2.43 145.80 Percolation Test Location #2 Test # Depth of Water (in) Time to Drain (min) Infiltration Rate (in/min) Infiltration Rate (in/hr) 1 20 23.0 0.86 51.60 2 12 32.5 0.36 21.60 3 5 18.2 0.27 16.20 Based on the percolation test data, Test Location #1 yielded an average infiltration rate of 113.4 inches per hour and Test Location #2 yielded an average infiltration rate of 29.8 inches per hour. The first perc test failed to pass the DEQ Circular 8 testing requirements with the increasing infiltration rate between successive trials, this test was not used in determining the design infiltration rate. In order to determine the design infiltration rate, we have taken the average of the second test results and then included a factor of safety of 2 to arrive at a value of 14.9 inches per hour. DRAINAGE AREAS Drainage Area 1&2 Drainage Area 1 consists of a portion of the neighboring Lot 2A and Lot 3. The proposed realignment of the drive aisle and curb and gutter will be graded. These existing lots flow north & west along the curb & gutters to a storm chase draining to the existing retention pond. A proposed fire lane connects the proposed parking lot and the existing Crowley Fleck parking lot. This addition will alter the existing runoff volume from the neighboring lots. DA 1 includes all the areas UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 5 of the neighboring lots that will drain to the proposed StormTech infiltration system (Chamber A) located in DA 1. It was determined 1,750 cu ft of detention volume is required to meet the half inch requirement (per DSS II.A.4) for Drainage Area 1&2. Drainage Area 2 (DA 2.0 & 2.1) consists of the northern portion of Lot 1A-1, including the east half of the northern apartment building as well as the surrounding sidewalks and a portion of the parking lot. Runoff from DA 2 will drain via sheet flow, curb & gutter, curb chases, and roof downspouts to the proposed StormTech system (Chamber A). The system will be located under the proposed parking lot where the existing pond is located. To meet the half inch requirement 941 ft3 of runoff will need to be detained from Drainage Area 2. The system was sized to detain the half inch requirement volume of 2,683 ft3 from DA 1, 2.0, & 2.1. The StormTech system will have a proposed storage volume of 2,729 ft3 and an inlet to capture runoff from both drainage areas. Specific manufacturer specifications for this StormTech system are included in the detail sheets (C5.1 &C5.2 of site plan set). Drainage Area 3 Drainage Area 3 consists of the southern part of the parking lot, a portion of the south apartment building, sidewalks, and landscaping along the building. Runoff from this DA will drain via sheet flow, curb & gutter, curb chases, and roof downspouts to the proposed StormTech system Chamber B. To meet the half inch requirement, 852 ft3 of storage is required for Drainage Area 3. The proposed system is located on the west side of the parking lot and is sized to detain 935 ft3 of runoff. Specific manufacturer specifications for this StormTech system are included in in the detail sheets (C5.1 &C5.2 of site plan set). Curb inlet capacity calcs are included in Appendix B. Drainage Area 4 Drainage Area 4 consists of a portion of the lot including the west half of the north building. Also included is the landscaped area between the building and the west property line. The 10-year 2- hour storm generates 365 ft3 of runoff, and the runoff from DA 4 will flow via sheet flow and 6 in. downspouts towards Retention Pond 1 which provides 389 cf of storage. This pond was sized to UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 6 retain the 10-year 2-hr storm runoff volume. The downspouts were designed to detain the 25-year storm event. Drainage Area 5& 6 (Kagy Blvd. Expansion) As indicated in the COB Master Transportation Plan Kagy Boulevard is proposed to be widened to meet the principle arterial roadway standards. The proposed expansion of Kagy Boulevard will generate excess stormwater runoff that will need to be retained on-site. Drainage Areas 5&6 include the areas impacted by the expansion, runoff from these DAs will drain via curb & gutter to curb inlets piped to proposed StormTech systems (Chambers C&D). The chambers were sized according to City of Bozeman Design Standards to capture and retain the volume of the 10-year 2-hour storm event. DA 5 will produce 916 ft3 of runoff that will be conveyed through a 12 in. PVC pipe in Chamber C with a storage volume of 1,050 ft3. DA 6 will produce 1,010 ft3 of runoff that will be conveyed through a 12 in. PVC pipe to Chamber D with a storage volume of 1,125 ft3. The inlet pipes leading to the chambers were sized based off the 25-year storm event. Calculations for sizing the chambers & pipes are included in Appendix B. Drainage Area 7 Drainage Area 7 consists of a portion of the parking lot on the north end of the lot. Runoff from this drainage area flows via sheet flow and curb & gutter to a curb inlet piped to Drywell #1. The 10-year 2-hour storm generates 183 ft3 of runoff and the drywell was sized to retain 194 ft3 of runoff. The inlet pipe was sized to accommodate a 25-year storm event per COB standards. A 12 in. PVC pipe will adequately convey runoff to the drywell. Pipe and drywell sizing calculations are included in Appendix B. Drainage Area 8 Drainage Area 8 consists of a portion of the lot including the south half of the south building as well as the surrounding landscaped and patio areas. The 10-year 2-hour storm generates 570 ft3 of runoff, and the runoff from DA 8 will flow via sheet flow and 6 in. downspouts to Retention Pond UNIVERSITY CROSSINGS – STORMWATER DESIGN REPORT Dec 16, 2021 #210228 7 2 which provides 753 cf of storage. The pond was sized to retain the 10-year 2-hr storm runoff volume. The downspouts were designed to detain the 25-year storm event. INFILTRATION CHAMBER DESIGN The StormTech infiltration system (Chamber A) will be placed where the existing stormwater pond is located for DA 1 & DA 2. The second system (Chamber B) will be placed at the low point of the southwesterly part of the parking lot. The third system (Chamber C) will be placed at the northwest corner of Proposed Lot 1A-1. The last system (Chamber D) will be placed at the northwest corner of Lot 2A. The proposed StormTech infiltration chambers are designed to detain stormwater runoff using the arch-shaped chambers and void space in the surrounding washed rock, while the runoff infiltrates into the ground. Systems A&B are StormTech SC-310 with combination curb inlet Nyloplast drain basins. Systems C&D are StormTech SC-740 with curb inlets piped to the Nyloplast drain basins. The footprint of these chambers will be excavated down to native gravels and back-filled with a well-draining gravel to ensure infiltration. The chambers were sized by applying an infiltration rate for gravel subgrades to the footprint area of the chambers to determine the discharge (infiltrate rate) from each system. An infiltration rate of 35 in/hour was used based on the Falling Head Percolation Tests performed on the lots. These discharge rates were then compared to the proposed inflow rates from the contributing areas to the systems during the 10-year 2-hour storm event to determine the required detention volumes for each system. Calculations used to determine these system sizes can be found in Appendix B. APPENDIX A Drainage Area Map APPENDIX B Storm Sewer Facilities Calculations RUNOFF VOLUME FROM DA#1 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 24434 4887 Hardscape 0.95 42716 40580 Total 67150 45467 A = Area (acres)1.54 C = Weighted C Factor 0.68 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.68 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 1.54 Q = RUNOFF (cfs)0.43 V = REQUIRED VOL (ft3)3065 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #1 Contributing Area Area (ft 2) Hardscape 42716 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.62 0.05 + 0.9*I I = Percent impervious cover (decimal)0.64 decimal A = Entire drainage area 1.54 acres RRV = Runoff Reduction Volume 0.0400 acre-ft RRV = Runoff Reduction Volume 1742 cubic feet Because the runoff volume from the 10‐yr, 2‐hr storm (for flood control) is  greater than the runoff volume produced by the half inch rainfall (for water quality)  the larger runoff volume is used  (3065 cf). Check the quantity of stormwater allocated from DA 1 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 1 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 104 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.3 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 0.72% L = length of gutter (ft) 321 V = mean velocity (ft/s) 2.54 Tc Gutter Flow (minutes) =2.1 Tc Total = 5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.68 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 1.54 (calculated above) Q = Pro Flow (cfs) 3.99 (assuming no carry flow) RUNOFF VOLUME FROM DA#2.0 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 3718 744 Hardscape 0.95 12595 11965 Total 16313 12709 A = Area (acres)0.37 C = Weighted C Factor 0.78 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.78 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.37 Q = RUNOFF (cfs)0.12 V = REQUIRED VOL (ft3)857 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #2 Contributing Area Area (ft 2) Hardscape 12595 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.74 0.05 + 0.9*I I = Percent impervious cover (decimal)0.77 decimal A = Entire drainage area 0.37 acres RRV = Runoff Reduction Volume 0.0116 acre-ft RRV = Runoff Reduction Volume 506 cubic feet Because the runoff volume from the 10‐yr, 2‐hr storm (for flood control) is  greater than the runoff volume produced by the half inch rainfall (for water quality)  the proposed retention facility is sized to handle the larger volume (857 cf). Check the quantity of stormwater allocated from DA 2 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 2 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 1.8% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 108 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.6 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 1.68% L = length of gutter (ft) 100 V = mean velocity (ft/s) 3.89 Tc Gutter Flow (minutes) =0.4 Tc Total = 5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.78 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.37 (calculated above) Q = Pro Flow (cfs) 1.12 (assuming no carry flow) 25- year storm runoff calc Runoff From DA 2.0 1. Summary of Drainage Areas Contributing Area DA # C Area (ft2 )C * Area Landscape 2 0.20 3718 744 Hardscape 2 0.95 12595 11965 Total 16313 12709 A = Area (acres)0.37 C = Weighted C Factor 0.78 2. Calculate Tc (Time to Concentration) Tc Total =5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.78 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres)0.37 (calculated above) Q 25-yr Flow Rate (cfs)=1.12 MANNING'S EQUATION for OPEN CHANNEL FLOW Curb Chase #1 Project:University Crossings Location: DA #2.1 By: JG Date: 12/1/2021 Chk By:DK Date: 12/1/2021 INPUT z (sideslope)= 0 Mannings Formula z (sideslope)= 0 w (btm width, ft)= 1.5 Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5 R = A/P S (slope, ft/ft) 0.015 A = cross sectional area n low =0.035 P= wetted perimeter n high =0.035 S = slope of channel V = (1.49/n)Rh2/3S1/2 n = Manning's roughness coefficient Q = V x A Depth, ft Area, sf Wetted Perimete r, ft Hydraulic Radius, ft Velocity, fps Flow, cfs Velocity, fps Flow, cfs 0.5 0.75 2.50 0.30 2.33 1.75 2.33 1.75 T = 1.50 Dm = 0.500 Sc low = 0.0444 Sc high = 0.0444 sc =critical slope ft / ft T = top width of the stream .7 Sc 1.3 Sc .7 Sc 1.3 Sc dm =a/T = mean depth of flow 0.0311 0.0577 0.0311 0.0577 Low N High N d w z 11 z T Clear Data Entry Cells RUNOFF VOLUME FROM DA#2.1 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 1798 360 Hardscape 0.95 10896 10352 Total 12694 10711 A = Area (acres)0.29 C = Weighted C Factor 0.84 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.84 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.29 Q = RUNOFF (cfs)0.10 V = REQUIRED VOL (ft3)722 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #2 Contributing Area Area (ft 2) Hardscape 10896 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.82 0.05 + 0.9*I I = Percent impervious cover (decimal)0.86 decimal A = Entire drainage area 0.29 acres RRV = Runoff Reduction Volume 0.0100 acre-ft RRV = Runoff Reduction Volume 435 cubic feet Because the runoff volume from the 10‐yr, 2‐hr storm (for flood control) is  greater than the runoff volume produced by the half inch rainfall (for water quality)  the proposed retention facility is sized to handle the larger volume (722 cf). Check the quantity of stormwater allocated from DA 2.1 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 2.1 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 90.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.2 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 2.00% L = length of gutter (ft) 100 V = mean velocity (ft/s) 4.24 Tc Gutter Flow (minutes) =0.4 Tc Total = 5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.84 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.29 (calculated above) Q = Pro Flow (cfs) 0.94 (assuming no carry flow) 25-year storm runoff calc Runoff From DA 2.0 & 2.1 1. Summary of Drainage Areas Contributing Area DA # C Area (ft2 )C * Area Landscape 2&2.1 0.20 5516 1103 Hardscape 2&2.1 0.95 23491 22316 Total 29007 23420 A = Area (acres)0.67 C = Weighted C Factor 0.81 2. Calculate Tc (Time to Concentration) Tc Total =5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.81 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres)0.67 (calculated above) Q 25-yr Flow Rate (cfs)=2.06 MANNING'S EQUATION for OPEN CHANNEL FLOW Curb Chase #2 Project:University Crossings Location: DA #2.1 By: JG Date: 12/1/2021 Chk By:DK Date: 12/1/2021 INPUT z (sideslope)= 0 Mannings Formula z (sideslope)= 0 w (btm width, ft)= 2 Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5 R = A/P S (slope, ft/ft) 0.015 A = cross sectional area n low =0.035 P= wetted perimeter n high =0.035 S = slope of channel V = (1.49/n)Rh2/3S1/2 n = Manning's roughness coefficient Q = V x A Depth, ft Area, sf Wetted Perimete r, ft Hydraulic Radius, ft Velocity, fps Flow, cfs Velocity, fps Flow, cfs 0.5 1.00 3.00 0.33 2.50 2.50 2.50 2.50 T =2.00 Dm = 0.500 Sc low = 0.0386 Sc high = 0.0386 sc =critical slope ft / ft T = top width of the stream .7 Sc 1.3 Sc .7 Sc 1.3 Sc dm =a/T = mean depth of flow 0.0270 0.0502 0.0270 0.0502 Low N High N d w z 11 z T Clear Data Entry Cells Chamber A DA #1,2.0,2.1 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 1,2,2.1 0.95 66207 62897 Landscape 1,2,2.1 0.20 29950 5990 Total 96157 68887 A = Area (acres)2.21 Storm C = Weighted C Factor 0.72 Return (yrs)Cf 2 to 10 1 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) =84.92 Infiltration Width (ft) =22.83 Infiltration Area (sf) =1938.724 Total Area (acres) =2.21 acres Weighted C =0.72 Discharge Rate (cfs) =0.67 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3) 18 0.30 1.40 2.21 2391 722 1668.52 19 0.32 1.35 2.14 2436 762 1674.07 20 0.33 1.31 2.07 2480 802 1678.08 21 0.35 1.27 2.00 2523 843 1680.69 22 0.37 1.23 1.94 2565 883 1681.99 23 0.38 1.19 1.89 2605 923 1682.08 24 0.40 1.16 1.84 2644 963 1681.05 25 0.42 1.13 1.79 2682 1003 1678.98 26 0.43 1.10 1.74 2719 1043 1675.93 27 0.45 1.08 1.70 2755 1083 1671.96 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #1&2 Contributing Area Area (ft 2) Hardscape 66207 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.67 0.05 + 0.9*I I = Percent impervious cover (decimal)0.69 decimal A = Entire drainage area 2.21 acres RRV = Runoff Reduction Volume 0.0616 acre-ft RRV = Runoff Reduction Volume 2683 cubic feet PROVIDED VOLUME (ft3)2,729 1/2" VOLUME REQ.=2683 DETENTION VOLUME REQ.=1682.08 DRAINAGE AREA # 3 RUNOFF VOLUME FROM DA#3 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 1895 379 Hardscape 0.95 21421 20350 Total 23315 20729 A = Area (acres)0.54 C = Weighted C Factor 0.89 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.89 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.54 Q = RUNOFF (cfs)0.19 V = REQUIRED VOL (ft3)1397 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft 2) Hardscape 21421 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.88 0.05 + 0.9*I I = Percent impervious cover (decimal)0.92 decimal A = Entire drainage area 0.54 acres RRV = Runoff Reduction Volume 0.0196 acre-ft RRV = Runoff Reduction Volume 852 cubic feet Check the quantity of stormwater allocated from DA 3 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 3 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 3.4% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1 11 to 25 1.1 D = Length of Basin (ft) 170 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)2.4 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 2.00% L = length of gutter (ft) 100 V = mean velocity (ft/s) 4.24 Tc Gutter Flow (minutes) =0.4 Tc Total = 5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.89 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.54 (calculated above) Q = Pro Flow (cfs) 1.82 (assuming no carry flow) Chamber B DA # 3 REQUIRED VOLUME 1. Calculate Area and Weighted C Factor (Post-Development) Contributing Area DA C Area (ft2)C * Area Hardscape 3 0.95 21421 20350 Landscape 3 0.20 1895 379 Total 23315 20729 A = Area (acres) 0.54 Storm C = Weighted C Factor 0.89 Return (yrs)Cf 2 to 10 1 2. Calculate Infiltration Rate 11 to 25 1.1 Existing Soil Condition =Gravel 26 to 50 1.2 Infiltration Rate (in/hour) =14.9 51 to 100 1.25 Infiltration Rate (ft/sec) =0.00034 Infiltration Length (ft) = 37 Infiltration Width (ft) = 16 Infiltration Area (sf) = 592 Total Area (acres) =0.54 acres Weighted C =0.89 Discharge Rate (cfs) =0.20 cfs Duration(min)Duration (hrs) Intensity (in/hr)Qin (cfs)Runoff Volume Release Volume Required Storage (ft3) 17 0.28 1.45 0.69 705 208 496.86 18 0.30 1.40 0.67 719 221 498.86 19 0.32 1.35 0.64 733 233 500.35 20 0.33 1.31 0.62 746 245 501.38 21 0.35 1.27 0.60 759 257 501.99 22 0.37 1.23 0.58 772 270 502.20 23 0.38 1.19 0.57 784 282 502.05 24 0.40 1.16 0.55 796 294 501.56 25 0.42 1.13 0.54 807 306 500.76 26 0.43 1.10 0.52 818 319 499.66 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #3 Contributing Area Area (ft 2) Hardscape 21421 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.88 0.05 + 0.9*I I = Percent impervious cover (decimal)0.92 decimal A = Entire drainage area 0.54 acres RRV = Runoff Reduction Volume 0.0196 acre-ft RRV = Runoff Reduction Volume 852 cubic feet PROVIDED VOLUME (ft3)935 1/2" VOLUME REQ.=852 DETENTION VOLUME REQ.=501.99 Input Type of Grate 2'x3' Curb Inlet High Flow Head (ft) 0.3 Properties Orifice Flow Area (in)425.88 Orifice Flow Area (ft)2.96 Weir Flow Perimeter (in)124.32 Weir Flow Perimeter (ft)10.36 Solution Capacity (cfs)5.67 Capacity (gpm)2544.13 REV 2.1.21 Nyloplast Inlet Capacity Table DISCLAIMER: SAFETY FACTORS ARE NOT INCLUDED IN THESE CALCULATIONS. ACTUAL CALCULATIONS SHOULD BE CARRIED OUT AND VERIFIED BY THE DESIGN ENGINEER TAKING INTO ACCOUNT ALL LOCAL CONDITIONS. NYLOPLAST RECOMMENDS USING A MINIMUM SAFETY FACTOR OF 1.25 FOR PAVED AREAS AND 2.0 FOR TURF AREAS.  ADS/NYLOPLAST IS NOT RESPONSIBLE FOR MISUSE OF THIS TOOL. CHAMBER A&B NYLOPLAST INLETS RUNOFF VOLUME FROM DA#4 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2)C * Area Landscape 0.2 7394 1479 Hardscape 0.95 4149 3941 Total 11543 5420 A = Area (acres)0.26 C = Weighted C Factor 0.47 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.47 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.26 Q = RUNOFF (cfs)0.05 V = REQUIRED VOL (ft3)365 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #4 Contributing Area Area (ft 2) Hardscape 4149 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.37 0.05 + 0.9*I I = Percent impervious cover (decimal)0.36 decimal A = Entire drainage area 0.26 acres RRV = Runoff Reduction Volume 0.0041 acre-ft RRV = Runoff Reduction Volume 180 cubic feet PROVIDED VOLUME (ft3)389 1/2" VOLUME REQ.=180 RETENTION VOLUME REQ.=365.38 Check the quantity of stormwater allocated from DA 4 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 4 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%)3.4% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft)90.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)1.2 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb) S = slope (%)2.00% L = length of gutter (ft)100 V = mean velocity (ft/s)4.24 Tc Gutter Flow (minutes) =0.4 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.47 (calculated above) I = .64 Tc-0.65 (in/hr)3.22 (25-yr storm) A = area (acres)0.26 (calculated above) Q = Pro Flow (cfs)0.40 (assuming no carry flow) DRAINAGE AREA # 4 ROOF DOWNSPOUT PIPE ROUTED TO RETENTION POND 1 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2 )C * Area LANDSCAPE 4 0.2 7394 1479 HARDSCAPE 4 0.95 4149 3941 Total 11543 5420 A = Area (acres) 0.26 C = Weighted C Factor 0.47 2. Calculate Tc (Time to Concentration) Tc Total = 5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.47 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.26 (calculated above) Q 25-yr Flow Rate (cfs)=0.48 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: Pond #1 Location: Pond #1 INPUT D= 6 inches d= 5.63 inches Mannings Formula n= 0.013 mannings 57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.01 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.19 1.32 0.15 3.28 0.63 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d  D RUNOFF VOLUME FROM DA#5 1. Calculate Weighted C Factor for ROW Component C Width ROW Landscape 0.2 9 ROW Hardscape 0.95 51 C = Weighted C Factor 0.84 2. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 0 0Hardscape 0.95 0 0 Composite ROW 0.84 16232 13594 Total 16232 13594 A = Area (acres)0.37 C = Weighted C Factor 0.84 3. Calculate Required VolumeQ = CIA V=7200Q C = Weighted C Factor 0.84 I = intensity (in/hr) 0.41 (10 yr, 2hr storm)A = Area (acres) 0.37 Q = RUNOFF (cfs)0.13 V = REQUIRED VOL (ft3)916 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #5 Contributing Area Area (ft2)Hardscape 16232 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.95 0.05 + 0.9*I I = Percent impervious cover (decimal)1.00 decimal A = Entire drainage area 0.37 acres RRV = Runoff Reduction Volume 0.0147 acre-ft RRV = Runoff Reduction Volume 642 cubic feet Because the runoff volume from the 10‐yr, 2‐hr storm (for flood control) is  greater than the runoff volume produced by the half inch rainfall (for water quality)  the proposed retention system is sized to handle the larger volume (916 cf). Stormtech Chamber C Volume PROVIDED VOLUME (ft3)1,050 1/2" VOLUME REQ.=642 RETENTION VOLUME REQ.=916.43 Check the quantity of stormwater allocated from DA 5 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 5 Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 3.0% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft)49 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)0.9 Tc Gutter FlowTc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (%) 0.66% L = length of gutter (ft) 243 V = mean velocity (ft/s) 2.44 Tc Gutter Flow (minutes) =1.7 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.84 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.37 (calculated above) Q = Pro Flow (cfs) 1.19 (assuming no carry flow) DRAINAGE AREA # 5 CATCH BASIN PIPE ROUTED TO INFILTRATION SYSTEM C 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2 )C * Area Composite ROW 5 0.84 16232 13594 Total 16232 13594 A = Area (acres) 0.37 C = Weighted C Factor 0.84 2. Calculate Tc (Time to Concentration) Tc Total =5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.84 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.37 (calculated above) Q 25-yr Flow Rate (cfs)=1.19 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: Chamber C Location: Chamber C INPUT D= 12 inches d= 11.26 inches Mannings Formula n= 0.013 mannings 57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.01 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.77 2.64 0.29 5.21 3.99 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d  D RUNOFF VOLUME FROM DA#6 1. Calculate Weighted C Factor for ROW Component C Width ROW Landscape 0.2 9 ROW Hardscape 0.95 51 C = Weighted C Factor 0.84 2. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 0 0Hardscape 0.95 0 0 Composite ROW 0.84 17895 14987 Total 17895 14987 A = Area (acres)0.41 C = Weighted C Factor 0.84 3. Calculate Required VolumeQ = CIA V=7200Q C = Weighted C Factor 0.84 I = intensity (in/hr) 0.41 (10 yr, 2hr storm)A = Area (acres) 0.41 Q = RUNOFF (cfs)0.14 V = REQUIRED VOL (ft3)1010 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #5 Contributing Area Area (ft2)Hardscape 17895 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.95 0.05 + 0.9*I I = Percent impervious cover (decimal)1.00 decimal A = Entire drainage area 0.41 acres RRV = Runoff Reduction Volume 0.0163 acre-ft RRV = Runoff Reduction Volume 708 cubic feet Because the runoff volume from the 10‐yr, 2‐hr storm (for flood control) is  greater than the runoff volume produced by the half inch rainfall (for water quality)  the proposed retention facility is sized to handle the larger volume (1010 cf) Stormtech Chamber D Volume PROVIDED VOLUME (ft3)1,125 1/2" VOLUME REQ.=708 RETENTION VOLUME REQ.=1010 Check the quantity of stormwater allocated from DA 6 (Tc Method) 1. Calculate Tc (Time to Concentration) of DA 6Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 2.0% Return (yrs)Cf C = Rational Method Runoff Coefficient 0.95 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft)40 26 to 50 1.251 to 100 1.25 Tc Overland Flow (minutes)0.9 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)S = slope (%) 0.66% L = length of gutter (ft) 145 V = mean velocity (ft/s) 2.44 Tc Gutter Flow (minutes) =1.0 Tc Total =5.0 (5 minute minimum) 2. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.84 (calculated above) I = .78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.41 (calculated above) Q = Pro Flow (cfs) 1.32 (assuming no carry flow) DRAINAGE AREA # 6 CATCH BASIN PIPE ROUTED TO INFILTRATION SYSTEM D 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2 )C * Area Composite ROW 6 0.84 17895 14987 Total 17895 14987 A = Area (acres) 0.41 C = Weighted C Factor 0.84 2. Calculate Tc (Time to Concentration) Tc Total =5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.84 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.41 (calculated above) Q 25-yr Flow Rate (cfs)=1.32 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: Chamber D Location: Chamber D INPUT D= 12 inches d= 11.26 inches Mannings Formula n= 0.013 mannings 57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.005 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.77 2.64 0.29 3.68 2.82 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d  D RUNOFF VOLUME FROM DA#7 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2) C * Area Landscape 0.2 878 176 Hardscape 0.95 2676 2542 Total 3554 2718 A = Area (acres)0.08 C = Weighted C Factor 0.76 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.76 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.08 Q = RUNOFF (cfs)0.03 V = REQUIRED VOL (ft3)183 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #7 Contributing Area Area (ft 2) Hardscape 2676 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.73 0.05 + 0.9*I I = Percent impervious cover (decimal)0.75 decimal A = Entire drainage area 0.08 acres RRV = Runoff Reduction Volume 0.0025 acre-ft RRV = Runoff Reduction Volume 108 cubic feet 4. Calculate Drywell Volume Void Ratio of Media 30.00% Gravel Offset Dist. From Drywell (ft) 5 (see Circular DEQ 4, Table 2.1-1) Gravel Void Volume Gravel Bed Depth (below MH) 0.00 Gravel Volume (ft3)463.23 Gravel Storage Volume (ft3)138.97 Manhole Volume Manhole Depth (ft) 3.00 *use 4' manhole (only using top 3' out of groundwater for retention calc) Manhole Volume (ft3)54.97 Provided Volume (ft3)194 CURB INLET PIPE ROUTED TO DRYWELL 1 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2 )C * Area LANDSCAPE 7 0.2 878 176 HARDSCAPE 7 0.95 2676 2542 Total 3554 2718 A = Area (acres) 0.08 C = Weighted C Factor 0.76 2. Calculate Tc (Time to Concentration) Tc Total = 5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.76 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.08 (calculated above) Q 25-yr Flow Rate (cfs)=0.24 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: DW 1 Pipe Location: DW 1 INPUT D= 12 inches d= 11.26 inches Mannings Formula n= 0.013 mannings 57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.009 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.77 2.64 0.29 5.00 3.82 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d  D RUNOFF VOLUME FROM DA#8 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2 )C * Area Landscape 0.2 5316 1063 Hardscape 0.95 7787 7398 Total 13103 8461 A = Area (acres)0.30 C = Weighted C Factor 0.65 2. Calculate Required Volume Q = CIA V=7200Q C = Weighted C Factor 0.65 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.30 Q = RUNOFF (cfs)0.08 V = REQUIRED VOL (ft3)570 Check the half inch requirement (per DSSP II.A.4) 1. Determine Area of Hardscape within Drainage Area #4 Contributing Area Area (ft 2 ) Hardscape 7787 2. Calculate 1/2" runoff volume over hardscape (aka Runoff Reduction Volume [RRV] as calculated in Montana Post- Construction Storwater BMP Manual - Equation 3-1) RRV = [P*Rv*A]/12 P = Water quality rainfall depth 0.50 inches Rv = Dimensionless runoff coefficient 0.58 0.05 + 0.9*I I = Percent impervious cover (decimal)0.59 decimal A = Entire drainage area 0.30 acres RRV = Runoff Reduction Volume 0.0073 acre-ft RRV = Runoff Reduction Volume 319 cubic feet PROVIDED VOLUME (ft3)753 1/2" VOLUME REQ.=319 RETENTION VOLUME REQ.=570.39 DRAINAGE AREA # 8 ROOF DOWNSPOUT PIPE ROUTED TO RETENTION POND 2 1. Summary of Roof Area and C Factor Contributing Area DA # C Area (ft2 )C * Area Hardscape 8 0.95 7787 7398 Total 7787 7398 A = Area (acres) 0.18 C = Weighted C Factor 0.95 2. Calculate Tc (Time to Concentration) Tc Total = 5.0 (Assume 5 minute minimum) 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.95 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm) A = area (acres) 0.18 (calculated above) Q 25-yr Flow Rate (cfs)=0.65 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: Pond #3 Location: Pond #3 INPUT D= 6 inches d= 5.63 inches Mannings Formula n= 0.013 mannings 57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.015 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.19 1.32 0.15 4.02 0.77 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d  D APPENDIX C Groundwater Monitoring Results PERC TEST PERC TEST GW-1 GW-2 #NAME? Project Engineer:Drew Kirsch Project:19TH & KAGY Well Information:bgs = below ground surface ags = above ground surface MW-1 MW-2 MW-32.33 2.43 3.50 4920.81 4923.79 4924.50 4918.48 4921.36 4921.00 Groundwater Information: MW-1 MW-2 MW-37.57 dry drydrydrydry 7.12 7.22 dry dry dry dry7.12 7.22 dry 6.48 6.52 dry 6.42 6.47 dry5.95 5.99 dry 6.15 6.26 dry dry dry dry dry 7.17 dry5.90 5.82 dry 6.01 5.99 dry 4.70 4.59 dry 5.74 5.85 dry 05/07/21 Monitor Well Data Depth to Ground Water (feet-bgs) 04/23/21 04/30/21 Project Number:210228 UNIVERSITY CROSSINGS Project Location: 05/07/21 04/30/21 Well ID Well Depth (Feet) Top of Well (Elevation)Ground Elevation Date 05/14/2105/21/2105/28/21 06/04/21 06/11/2106/18/2106/24/21 07/01/21 07/09/21 07/16/21 APPENDIX D Stormwater Facility Maintenance Plans