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HomeMy WebLinkAboutELEVATIONS CREDIT UNION - FDP - FDP160042 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE REPORT Elevations Credit Union Fort Collins, Colorado October 25, 2016 Prepared for: Elevations Credit Union 1526 E. Harmony Road, Unit 130 Fort Collins, Colorado 80525 Prepared by: 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 207-016  This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double-sided printing. October 25, 2016 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Elevations Credit Union Dear Staff: Northern Engineering is pleased to submit this Final Drainage Report for your review. This report accompanies the Conceptual Review submittal for the proposed Elevations Credit Union. This report has been prepared in accordance with the City of Fort Collins Stormwater Criteria Manual (FCSCM) and the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual and serves to document the stormwater impacts associated with the proposed Elevations Credit Union project. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE Blaine Mathisen Project Manager Project Engineer Elevations Credit Union Final Drainage Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1 A. Location ............................................................................................................................................. 1 B. Description of Property ..................................................................................................................... 2 C. Floodplain.......................................................................................................................................... 3 II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 5 A. Major Basin Description .................................................................................................................... 5 B. Sub-Basin Description ....................................................................................................................... 5 III. DRAINAGE DESIGN CRITERIA ................................................................................... 6 A. Regulations........................................................................................................................................ 6 B. Four Step Process .............................................................................................................................. 6 C. Development Criteria Reference and Constraints ............................................................................ 7 D. Hydrological Criteria ......................................................................................................................... 7 E. Hydraulic Criteria .............................................................................................................................. 7 F. Floodplain Regulations Compliance .................................................................................................. 7 G. Modifications of Criteria ................................................................................................................... 8 IV. DRAINAGE FACILITY DESIGN .................................................................................... 8 A. General Concept ............................................................................................................................... 8 B. Specific Details ................................................................................................................................ 10 V. CONCLUSIONS ...................................................................................................... 12 A. Compliance with Standards ............................................................................................................ 12 B. Drainage Concept ............................................................................................................................ 12 References ....................................................................................................................... 13 APPENDICES: APPENDIX A – Hydrologic Computations APPENDIX B – Hydraulic Computations B.1 – Storm Sewers (For Future Use) B.2 – Inlets B.3 – Detention Facilities APPENDIX C – Water Quality Design Computations APPENDIX D – Erosion Control Report APPENDIX E – Soils Resource Report Elevations Credit Union Final Drainage Report LIST OF TABLES AND FIGURES: Figure 1 Vicinity Map .......................................................................................................... 1 Figure 2 Aerial Photograph ................................................................................................... 2 Figure 3 Proposed Site Plan ................................................................................................. 3 Figure 4 FEMA Map ............................................................................................................ 4 Figure 5 City Floodplain Mapping .......................................................................................... 4 MAP POCKET: C7.00 – Proposed Drainage Exhibit C7.01 – Historic Drainage Exhibit Elevations Credit Union Final Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map Figure 1 Vicinity Map 2. Elevations Credit Union project site is located in the east half of the southeast quarter of the northeast quarter of Section 23, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located at 2025 College Avenue at northwest corner of the intersection of College Avenue and Arthur Drive. 4. The project site lies within the Spring Creek Basin. The site drains via overland flow and curb and gutter north towards Spring Creek, and it ultimately discharges into the Cache La Poudre River. The proposed impervious area for the site is 23,862 square feet (0.548 ac.) and detention is required. The site still must provide current City Low Impact Design (LID) requirements and water quality treatment. Water quality treatment methods are described in further detail below. 5. As this is an in-fill site, the area surrounding the site is fully developed. Elevations Credit Union Final Drainage Report 2 6. Offsite flows from Arthur Drive from the south, crosses the southwest corner the site staying within the asphalt, curb, and gutter for Arthur Drive. No offsite flows from the north, east or west enters the site. B. Description of Property 1. Elevations Credit Union project is approximately 0.72 net acres. Figure 2 Aerial Photograph 2. The subject property is currently composed of an abandoned gas station, asphalt, concrete, and landscaping along College Avenue and the west end of the site. Existing ground slopes are mild (i.e. 1 – 4%±) through the eastern two-thirds of the property. A large retaining wall divides the upper two-thirds from Spring Court to the west. Existing slopes for the wester third range from 5:1 to 3%±. General topography slopes from south to north. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, the site consists of Altvan-Satanta loams, which fall into Hydrologic Soil Groups B. The NRCS soils report is provided in Appendix E. 4. The proposed development is composed of a proposed building along the eastern property to include commercial and financial services. A hardscape parking lot with landscaping islands is proposed. Associated site work including water, sanitary sewer, storm sewer, rain gardens, and underground detention will be constructed with the development. Current City Low Impact Design (LID) requirements will be implemented with the project, and will consist of several LID features which are discussed in Section IV, below. Elevations Credit Union Final Drainage Report 3 Figure 3 Proposed Site Plan 5. There are no known irrigation laterals crossing the site. 6. The project site is within a General Commercial District (C-G). The proposed use is permitted within this zone district. C. Floodplain 1. The northwest corner of the project site is encroached by the FEMA designated 100- Year High Risk Flood Fringe according to FIRM Panel 08069C87G for Larimer County, dated May 2, 2012.Development will be allowed within the flood fringe which is all the occurs on the Elevations Credit Union project site. It should be noted that no structures will be constructed within the floodplain with the development of Elevations Credit Union. Elevations Credit Union Final Drainage Report 4 Figure 4 FEMA Map Figure 5 City Floodplain Mapping Elevations Credit Union Final Drainage Report 5 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. The project site lies within the Spring Creek Basin. Detention requirements for this site are to detain the difference between the 100-year developed inflow rate and the historic 2-year release rate from the landscaping areas associated with the previous onsite gas station. Historically, the site sheet flows all onsite runoff directly offsite without any detention or water quality. However, Elevations Credit Union will free release all paved areas and release the remaining portion at a rate equal to the runoff rate of the historic landscaping areas along the western and eastern property boundaries of the site. Water quality will however be provided for the all paved areas via underground Stormtech chambers and rain gardens. 2. There are no previous drainage studies for the area associated with Elevations Credit Union project site. B. Sub-Basin Description Elevations Credit Union historically drains overland from south to north. Runoff from the site has historically flowed overland north towards Spring Creek and eventually entering the Cache La Poudre. Basin E Basin E encompasses 0.20 acres from the eastern boundary to roughly 1/3 east into the property. Runoff generated in this basin has historically sheet flowed directly into College Avenue and then conveyed north via curb and gutter until it enters Spring Creek. The previous development had an impervious area of 6,083 sq. ft. associated with Basin E. Basin W Basin W encompasses 0.52 acres from the western boundary to roughly 2/3 west into the property. Runoff generated in this basin has historically sheet flowed offsite either into Arthur Drive or Spring Court. All flow that entered Arthur Drive eventually reaches Spring Court via curb and gutter and from there the runoff is conveyed north towards Spring Creek. The previous development had an impervious area of 16,163 sq. ft. associated with Basin W. The previous development had a total impervious area of 22,249 sq. ft. and Elevations Credit Union is proposing a total impervious area of 23,356 sq. ft. Therefore, the difference in impervious area is 1,107 sq. ft. bringing the proposed development 107 sq. ft. above the maximum allowable change requiring detention. Below in Section IV.B.2 a more detailed description of Elevations Credit Union detention is discussed. 1. A more detailed description of the projects proposed drainage patterns follows in Section IV.A.4., below. 2. There are no offsite flows associated with Elevations Credit Union. A full-size copy of the Historic and Proposed Drainage Exhibit can be found in the Map Pocket at the end of this report. Elevations Credit Union Final Drainage Report 6 III. DRAINAGE DESIGN CRITERIA A. Regulations There are no optional provisions outside of the FCSCM proposed with the Elevations Credit Union project. B. Four Step Process The overall stormwater management strategy employed with the Elevations Credit Union project utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use by implementing multiple Low-Impact Development (LID) strategies including: Providing as much vegetated open areas as possible along the north, east, west and south portion of the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing flows, to the extent feasible, through underground Stormtech Isolator Rows for water quality purposes. Stormwater will be routed through drain rock to increase infiltration Providing regional detention to increase time of concentration, promote infiltration and reduce loads on downstream storm infrastructure. Routing runoff from the roof directly into isolator rows Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban development of this intensity will still generate stormwater runoff that will require additional BMPs and water quality. The stormwater runoff from the site will be intercepted and treated using underground Stormtech chambers Step 3 – Stabilize Drainageways There are no major drainageways within the subject property. While this step may not seem applicable to proposed development, the project indirectly helps achieve stabilized drainageways nonetheless. By providing water quality treatment, where none previously existed, sediment with erosion potential is removed from downstream drainageway systems. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve City-wide drainageway stability. Step 4 – Implement Site Specific and Other Source Control BMPs. The proposed project includes a single story building, associated parking, retaining walls, and pedestrian sidewalk paths all of which will require the need for site specific source controls including: A localized trash enclosure placed in the parking lot. The proposed development will provide LID features within Stormtech Isolator Rows to enhance water quality. The Stormtech Isolator Row is designed to capture the first Elevations Credit Union Final Drainage Report 7 flush of a storm event; thus, eliminating sources of potential pollution previously left exposed to weathering and runoff processes. C. Development Criteria Reference and Constraints 1. There are no known drainage studies for the existing property. 2. The subject property is essentially an "in-fill" development project as the property is surrounded by currently developed properties. As such, several constraints have been identified during the course of this analysis that will impact the proposed drainage system including: Existing elevations along the north, south, east, and west property lines will be maintained. Overall drainage patterns of the existing site will be maintained. Release rates can not adversely impact existing infrastructure. D. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations associated with this development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables RO-11 and RO-12 of the FCSCM. 3. The Rational Formula-based Modified Federal Aviation Administration (FAA) procedure has been utilized for detention storage calculations. 4. Two separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. 5. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. E. Hydraulic Criteria 1. As previously noted, the subject property maintains historic drainage patterns. 2. All drainage facilities proposed with the Elevations Credit Union project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual. 3. As stated in Section I.C.1, above, the subject property is encroaching a FEMA 100- Year High Risk Flood Fringe. However, the proposed project does not propose to modify any natural drainageways. F. Floodplain Regulations Compliance 1. As previously mentioned, the project site is encroaching a FEMA 100-Year High Risk Flood Fringe along the northwest corner of the property. Development will be allowed within the flood fringe which is all the occurs on the Elevations Credit Union project site. It should be noted that no structures will be constructed within the floodplain with the development of Elevations Credit Union. Elevations Credit Union Final Drainage Report 8 G. Modifications of Criteria The proposed Elevations Credit Union development is not requesting modification at this time. IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objectives of the Elevations Credit Union drainage design are to maintain existing drainage patterns and ensure no adverse impacts to any adjacent properties or existing infrastructure occurs. 2. As previously mentioned, there are no off-site flows draining onto the existing property. Additionally, onsite LID feature will be provided which will enhance downstream water quality. These measures are discussed further below. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. 4. The proposed Elevations Credit Union project is associated with six (6) major drainage basins, designated as Basins W.1, E.1, R.1, OS.1, OS.2, and OS.3. Drainage patterns for proposed drainage basins as shown in the Proposed Drainage Exhibit are described below. Basin W.1 Basin W.1 has a net area of 0.32 acres which has an associated parking lot and landscaping islands. Runoff generated in Basin W.1 will sheet flow as well as curb and gutter flow east to west until it is collected by an inlet along the west side of the parking lot. Runoff entering the inlet will be conveyed via storm sewer pipes. The storm sewer will convey the runoff into two separate isolator rows containing four (4) SC-740 cells each. The additional runoff will continue to fill the non-isolator rows. The isolator rows will be wrapped in a geotextile membrane to avoid sediment migration. Once, Basin W.1 goes through the water quality it will be released into a sidewalk chase within Spring Court. Once the runoff is in Spring Court it will then flow north as historically routed. Basin E.1 Basin E.1 is located along the eastern side of the proposed building. Basin E.1 has a net area of 0.04 acres and which is associated with concrete sidewalks and rain gardens. Runoff generated in Basin E.1 will sheet flow west to east until it enters one of the two rain gardens which are connected via a trench drain making them act hydraulically as one uniform rain garden. Once the runoff is treated within the rain garden it will enter the storm sewer and be conveyed to the Stormtech SC-740 chambers where it will bypass freely and release undetained into a sidewalk chase located within Spring Court. Any event above the water quality event will sheet flow west to east across the property until it reaches the curb and gutter within College Avenue. From there the runoff will be conveyed north as historically routed. Elevations Credit Union Final Drainage Report 9 Basin R.1 Basin R.1 has a net area of 0.12 acres and is associated exclusively with the one story building roof runoff. Runoff created in this basin will sheet flow across the roof east to west and enter one of two possible roof leaders. The roof leaders will convey the runoff into an isolator row. Then, just like Basin W.1, it will be released into a sidewalk chase located in Spring Court. Basin OS.1 Basin OS.1 has a net area of 0.06 acres and is located along the northern edge of the project site and consists solely of landscaping and a portion of retaining wall. Runoff generated in Basin OS.1 will overland flow north directly offsite undetained into College Avenue. The landscaped area will act as a water quality measure by reducing runoff via infiltration and removing excess sediment. Basin OS.2 Basin OS.2 has a net area of 0.04 acres and is located along the eastern edge of the project site. Basin OS.2 consists of a small portion of the drive entrance, pedestrian sidewalk, and landscaping. Runoff generated in Basin OS.2 will overland flow directly offsite into College Avenue undetained and untreated just like historic conditions. Once in College Avenue it will flow south to north as historically routed. Basin OS.3 Basin OS.3 has a net area of 0.15 acres is located along the western and southern borders of the project site. Just like historic patterns, Basin OS.3 will overland flow directly offsite undetained and untreated into Arthur Drive and Spring Court. Basin OS.3 consists of landscaping, drive entrance, and a portion of Arthur Drive. Design Point OS3 Design Point OS3 is associated with Basins W.1, R.1, and OS.3. These three basins all drain west towards Spring Court (same as Historic Basin W) via overland. The difference between Historic Basin W and the combined basins draining to Design Point OS3 is an increased amount of impervious area. Elevations Credit Union is proposing to add 4,456 sq. ft. of impervious area draining towards Spring Court. This area along with a release rate of 0 cfs was used to size the required detention for Elevations Credit Union so that no downstream infrastructure located in Spring Court would be impacted. Design Point OS1 Design Point OS1 is associated with Basins OS.1, and OS.2. These two basins sheet flow east into College Avenue (Same as Historic Basin E). The difference between Historic Basin E and Design Point OS1 is the amount of impervious area. Elevations Credit Union is reducing the amount impervious associated with this area by 3,346 sq. ft. Therefore, Elevations Credit Union will not be impacting any existing infrastructure located within College Avenue. Elevations Credit Union Final Drainage Report 10 B. Specific Details 1. The main drainage problems associated with this project site is the deficiency of existing stormwater infrastructure present, steep existing grades, and FEMA floodplains. Currently the site drains to the east and west, but ultimately discharges in the same location north of the site within Spring Creek. The proposed site will mitigate these issues by instituting the following water quality & detention devices: Rain Garden along the College Avenue frontage Stormtech isolator rows to be wrapped with a geotextile membrane to collect sediment migration. The runoff collected by these chambers will then drain through open graded drainage rock. Stormtech chambers to release at a restricted rate by use of an orifice plate The release rate for the overall project site was established by quantifying the amount of additional imperviousness being proposed by this development. The existing impervious area accounted for a total 22,249 sq. ft., while the proposed project account for 23,356 sq. ft. Resulting in an overall increase in impervious area of 1,107 sq. ft. The proposed area routing runoff to the east (Basins E.1, OS.1 and OS.2) is 0.08 ac. smaller than historic basin E1 and consists of 3,346 sq. ft. less impervious area than historic. Therefore, flow being released to the east is decreased and released undetained. The proposed area routing runoff to the west (Basins W.1, R.1 and OS.3) is 0.08 ac. larger than historic basin W1 and consists of 4,456 sq. ft. more impervious area than historic. To ensure the peak runoff rate was decreased, the detention volume was based on capturing the entire storm event generated from the additional impervious area. 2. Detention Pond Calculations As previously mentioned, the area discharging to the east will be free released into College Avenue, while the area discharging to the west will be detained through underground detention chambers to account for the additional impervious area. Using the FAA Method to detain the entire storm event generated from the additional impervious area (Q = 0 cfs) yields an overall detention volume of 1,355 cu. ft. This required volume will be stored in 19 Stormtech SC-740 chambers. The underground system will discharge through a flow control manhole towards a sidewalk chase located within Spring Court. Although the detention volume was calculated using a release rate of 0 cfs that is not actually the runoff entering Spring Court from Elevations Credit Union. Using the characteristics of Basins W.1 and R.1 (Area=0.44 acres, Tc=5min, C=1.00 and a required detention of 1,355 cu. ft.) the FAA Method was used to calculate the required release and resulted in a release rate of 2.15 cfs. The 2.15 cfs runoff from Basins W.1 and R.1 along with the 0.95 cfs being free released into Spring Court from Basin OS3 results in an overall peak runoff rate of 3.10 cfs. This proposed rate is 1.76 cfs less than the historic peak runoff rate of 4.86 cfs. 3. Water Quality Results Following UDFCD criteria a 12-hour drain time was used to size all water quality amenities being proposed with Elevations Credit Union. Water quality will be provided as a portion of the underground SC-740 chambers via isolator rows for Basins W.1 and R.1. The isolator rows will be wrapped with a geotextile membrane to reduce sediment migration within the system and improving downstream water quality. Basin E.1 will have water quality provided via the rain gardens that are hydraulically connected via a 4” PVC underdrain. Elevations Credit Union Final Drainage Report 11 Basin W.1 Basin W.1’s water quality will be provided via underground Stormtech SC-740 isolator chambers. Runoff will enter the underground system through an inlet. Following UDFCD standards, a required WQCV of 390 cu. ft. must be provided for Basin W.1. In order to achieve this volume 9 SC-740 chambers must be used to capture this runoff. Basin E.1 Basin E.1 will have its own water quality provided via a rain garden. Following UDFCD BMP standards a required volume of 29.28 cu. ft. of water quality must be provided for Basin E.1. The rain garden has been designed to treat up to a volume of 123 cu. ft. of runoff. The rain garden will have a modified media section underneath the growing media to promote infiltration. Once the runoff has been treated it will bi- pass the underground detention system to the west and discharge into Spring Court. Basin R.1 Basin R.1’s water quality will be provided via underground Stormtech SC-740 isolator chambers. Runoff generated in Basin R.1 will enter the isolator rows via roof leaders. Following UDFCD criteria, a required WQCV of 138 cu. ft. must be provided for Basin R.1. In order to achieve this volume 3 SC-740 chambers must be provided. 4. The underground pond will provide enough storage for 1,355 cu. ft. of runoff by utilizing 19 SC-740 Stormtech chambers. A total of 675 cu. ft. of water quality will be provided onsite as well. A rain garden will provide treatment for up to 123 cu. ft. of runoff and the remaining 552 cu. ft. will be treated in isolator rows within the SC-740 Stormtech chambers. It requires 12 SC-740 chambers to treat 552 cu. ft. of runoff assuming a porosity of 0%. A total amount of 19 Stormtech SC-740 chambers will be utilized for the proposed Elevations Credit Union project for both detention and water quality purposes. 5. In the case that the inlet within Basin W.1 gets clogged runoff will overtop the curb and gutter, then overtop the retaining wall, and flow west into Spring Court as it has historically. Design Point Basin ID Basin Area Treatment Type LID System Area Treated by LID System Percent of Site Treated by LID System w.1 W.1 0.320 ac. StormTech Chambers Yes 0.320 ac. 44% e.1 E.1 0.040 ac. Rain Garden Yes 0.040 ac. 6% r.1 R.1 0.120 ac. StormTech Chambers Yes 0.120 ac. 17% os.1 OS.1 0.050 ac. Grass Buffer No N/A 0% os.2 OS.2 0.040 ac. Grass Buffer No N/A 0% os.3 OS.3 0.150 ac. Grass Buffer No N/A 0% Total 0.720 ac. 0.480 ac. 67% Elevations Credit Union Final Drainage Report 12 V. CONCLUSIONS A. Compliance with Standards 6. The drainage design proposed with the Elevations Credit Union project complies with the City of Fort Collins’ Stormwater Criteria Manual. 7. The drainage design proposed with the Elevations Credit Union project complies with the City of Fort Collins’ Master Drainage Plan for the Spring Creek Basin. 8. The project site is encroached by a 100-Year High Floodplain Fringe along the northwest corner of the property. However, the development will not be adversely impacting any of the downstream infrastructure, as this floodplain is caused by the obstruction of the College Avenue bridge. 9. The drainage plan and stormwater management measures proposed with the Elevations Credit Union development are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. Elevations Credit Union will detain additional impervious area being routed to the west (4,456 sq. ft.). However, the total difference in impervious area between historic and proposed conditions is only 1,107 sq. ft. which is 107 sq. ft. above the maximum threshold for detention according to the City of Fort Collins Stormwater Criteria Manual. 2. Elevations Credit Union will also be releasing at reduced runoffs from the historic condition to both College Avenue and Spring Court therefore there will be no downstream impacts from this development. 3. Elevations Credit Union will provide water quality for a majority of the site (0.48 acres) with accepted LID treatments. The remaining portion of the project site will receive water quality by crossing over landscaped areas. The areas receiving water quality via landscaping were uncatchable due to steep grades along the north and west. 4. The proposed Elevations Credit Union development will not impact the Master Drainage Plan recommendations for the Spring Creek major drainage basin. Elevations Credit Union Final Drainage Report 13 References 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. APPENDIX A HYDROLOGIC COMPUTATIONS Elevations Credit Union CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Elevations Credit Union Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.. 50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..……………………………………………..0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. W 22766.0 0.523 0.161 0.185 0.026 0.000 0.000 0.15 0.75 0.75 0.93 67% E 8600.0 0.197 0.103 0.032 0.005 0.000 0.000 0.06 0.75 0.75 0.93 69% TOTAL 31366 0.720 0.263 0.217 0.031 0.000 0.000 0.21 0.72 0.72 0.90 67% DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. 10-year Cf = 1.00 July 12th, 2016 **Soil Classification of site is Clay Loam** Page 1 of 20 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Historic).xlsx\C-Values Elevations Credit Union Overland Flow, Time of Concentration: Project: Elevations Credit Union Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S½ Velocity (Swale Flow), V = 15·S½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? (C*2-Cf yr Cf=1.00) (10-C*Cf yr Cf=1.00) (100-C*Cf yr Cf=1.25) Length, L (ft) Slope, S (%) 2-Ti yr (min) 10-Ti yr (min) 100-Ti yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt 2-yr (min) Tc 10-yr (min) Tc 100-yr (min) Tc w W No 0.75 0.75 0.93 68 3.20% 3.7 3.7 1.7 N/A N/A N/A N/A N/A 5 5 5 e E No 0.75 0.75 0.93 50 5.80% 2.6 2.6 1.2 N/A N/A N/A N/A N/A 5 5 5 DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Elevations Credit Union Rational Method Equation: Project: Elevations Credit Union Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: w W 0.52 5 5 5 0.75 0.75 0.93 2.85 4.87 9.95 1.11 1.90 4.86 e E 0.20 5 5 5 0.75 0.75 0.93 2.85 4.87 9.95 0.42 0.72 1.83 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Area, A (acres) Intensity, i2 (in/hr) 100-yr Tc (min) DEVELOPED RUNOFF COMPUTATIONS C100 Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) B. Mathisen Q  C f  C  i  A  July 12th, 2016 Page 3 of 20 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Historic).xlsx\Direct-Runoff Elevations Credit Union DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr (min) Tc 100-yr (min) Tc (cfs) Q2 (Q100 cfs) w W 0.52 0.75 0.93 5.0 5.0 1.11 4.86 e E 0.20 0.75 0.93 5.0 5.0 0.42 1.83 Page 4 of 20 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Historic).xlsx\SUMMARY-TABLE Elevations Credit Union CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Elevations Credit Union Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.. 50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..……………………………………………..0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. W.1 13939.2 0.320 0.273 0.024 0.000 0.000 0.000 0.02 0.90 0.90 1.00 92% E.1 1931.3 0.044 0.000 0.028 0.000 0.000 0.000 0.02 0.69 0.69 0.87 57% R.1 5282.0 0.121 0.000 0.000 0.121 0.00 0.95 0.95 1.00 90% OS.1 2081.0 0.048 0.000 0.002 0.000 0.000 0.000 0.05 0.28 0.28 0.35 4% OS.2 1529.0 0.035 0.000 0.033 0.000 0.000 0.000 0.00 0.90 0.90 1.00 84% OS.3 6600.0 0.152 0.026 0.030 0.000 0.000 0.000 0.10 0.51 0.51 0.63 34% TOTAL 31363 0.720 0.299 0.116 0.121 0.000 0.000 0.18 0.75 0.75 0.93 71% DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. Elevations Credit Union Overland Flow, Time of Concentration: Project: Elevations Credit Union Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S½ Velocity (Swale Flow), V = 15·S½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? (C*2-Cf yr Cf=1.00) (10-C*Cf yr Cf=1.00) (100-C*Cf yr Cf=1.25) Length, L (ft) Slope, S (%) 2-Ti yr (min) 10-Ti yr (min) 100-Ti yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt 2-yr (min) Tc 10-yr (min) Tc 100-yr (min) Tc w.1 W.1 No 0.90 0.90 1.00 89 0.50% 4.5 4.5 2.2 92 3.00% 3.46 0.4 N/A N/A N/A 5 5 5 e.1 E.1 No 0.69 0.69 0.87 21 5.00% 2.0 2.0 1.2 N/A N/A N/A N/A N/A 5 5 5 r.1 R.1 No 0.95 0.95 1.00 45 1.00% 1.9 1.9 1.3 N/A N/A N/A N/A N/A 5 5 5 Elevations Credit Union Rational Method Equation: Project: Elevations Credit Union Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: w.1 W.1 0.32 5 5 5 0.90 0.90 1.00 2.85 4.87 9.95 0.82 1.40 3.18 e.1 E.1 0.04 5 5 5 0.69 0.69 0.87 2.85 4.87 9.95 0.09 0.15 0.38 r.1 R.1 0.12 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.33 0.56 1.21 os.1 OS.1 0.05 5 5 5 0.28 0.28 0.35 2.85 4.87 9.95 0.04 0.07 0.17 os.2 OS.2 0.04 5 5 5 0.90 0.90 1.00 2.85 4.87 9.95 0.09 0.15 0.35 os.3 OS.3 0.15 5 5 5 0.51 0.51 0.63 2.85 4.87 9.95 0.22 0.37 0.95 DEVELOPED RUNOFF COMPUTATIONS C100 Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) B. Mathisen July 12th,2016 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Area, A (acres) Intensity, i2 (in/hr) 100-yr Tc (min) Q  C f  C  i  A  Page 3 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\Direct-Runoff Elevations Credit Union CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Elevations Credit Union Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: July 12th,2016 Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….. 0.50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Design Point Basin IDs Basin Area (s.f.) Basin Area (ac) Area of Asphalt (sq ft) Area of Asphalt (ac) Area of Concrete (sq ft) Area of Concrete (ac) Area of Roofs (sq ft) Area of Roofs (ac) Area of Gravel (sq ft) Area of Gravel (ac) Area of Pavers (sq ft) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Elevations Credit Union Overland Flow, Time of Concentration: Project: Elevations Credit Union Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S½ Velocity (Swale Flow), V = 15·S½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? (C*2-Cf yr Cf=1.00) (10-C*Cf yr Cf=1.00) (100-C*Cf yr Cf=1.25) Length, L (ft) Slope, S (%) 2-Ti yr (min) 10-Ti yr (min) 100-Ti yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt Length, L (ft) Slope, S (%) Velocity, V (ft/s) (min) Tt 2-yr (min) Tc 10-yr (min) Tc 100-yr (min) Tc OS OS1, OS2, OS3 No 0.52 0.52 0.65 55 3.50% 5.3 5.3 4.1 N/A N/A N/A N/A 5 5 5 OS3 OS1 W1,R1 & OS3 No 0.88 0.88 1.00 65 2.10% 2.6 2.6 1.2 N/A N/A N/A N/A 5 5 5 OS1, OS2 & E1 No 1.02 1.02 1.00 95 5.20% 0.8 0.8 1.1 N/A N/A N/A N/A 5 5 5 Elevations Credit Union Rational Method Equation: Project: Elevations Credit Union Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: OS3 OS OS1, W1,R1 OS2, & OS3 OS3 0.23 5 5 5 0.52 0.52 0.65 2.85 4.87 9.95 0.3 0.6 1.5 OS1 0.59 5 5 5 0.88 0.88 1.00 2.85 4.87 9.95 1.5 2.5 5.9 OS1, OS2 & E1 0.13 5 5 5 1.02 1.02 1.00 2.85 4.87 9.95 0.4 0.6 1.3 Intensity, (in/i100 hr) COMBINED DEVELOPED RUNOFF COMPUTATIONS B. Mathisen July 12th,2016 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Design Point Basin(s) Area, A (acres) 2-yr (min) Tc 10-yr (min) Tc 100-yr (min) Tc Flow, (cfs) Q2 Flow, (Q10 cfs) Flow, Q100 (cfs) C2 C10 C100 Intensity, (in/i2 hr) Intensity, (in/i10 hr) Q  C f  C  i  A  Page 6 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\Comb-Direct-Runoff Elevations Credit Union DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr (min) Tc 100-yr (min) Tc (cfs) Q2 (Q100 cfs) w.1 W.1 0.32 0.90 1.00 5.0 5.0 0.82 3.18 e.1 E.1 0.04 0.69 0.87 5.0 5.0 0.09 0.38 r.1 R.1 0.12 0.95 1.00 5.0 5.0 0.33 1.21 os.1 OS.1 0.05 0.28 0.35 5.0 5.0 0.04 0.17 os.2 OS.2 0.04 0.90 1.00 5.0 5.0 0.09 0.35 os.3 OS.3 0.15 0.51 0.63 5.0 5.0 0.22 0.95 DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr (min) Tc 100-yr (min) Tc (cfs) Q2 (Q100 cfs) OS OS1, OS2, OS3 0.23 0.52 0.65 5.3 5.0 0.35 1.51 OS3 W1,R1 & OS3 0.59 0.88 1.00 5.0 5.0 1.48 5.90 OS1 OS1, OS2 & E1 0.13 1.02 1.00 5.0 5.0 0.37 1.27 Page 7 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\SUMMARY-TABLE APPENDIX B HYDRAULIC COMPUTATIONS B.1 – Storm Sewers B.2 – Detention Facilities APPENDIX B.1 STORM SEWERS APPENDIX B.2 INLETS (FOR FUTURE USE) 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 2' x 2' Curb Inlet Diagonal Grate Inlet Capacity Chart High Hood Setting (8.47" Curb Setting) Mid Hood Setting (6.47" Curb Setting) Low Hood Setting (4.47" Curb Setting) APPENDIX B.3 DETENTION FACILITIES Pond No : p1 100-yr 1.00 5.00 min 1355 ft3 0.10 acres 0.031 ac-ft Max Release Rate = 0.00 cfs Time (min) Ft Collins 100-yr Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor (Qav cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 9.950 305 1.00 0.00 0 305 10 7.720 474 0.75 0.00 0 474 15 6.520 600 0.67 0.00 0 600 20 5.600 687 0.63 0.00 0 687 25 4.980 764 0.60 0.00 0 764 30 4.520 832 0.58 0.00 0 832 35 4.080 876 0.57 0.00 0 876 40 3.740 918 0.56 0.00 0 918 45 3.460 956 0.56 0.00 0 956 50 3.230 991 0.55 0.00 0 991 55 3.030 1023 0.55 0.00 0 1023 60 2.860 1053 0.54 0.00 0 1053 65 2.720 1085 0.54 0.00 0 1085 70 2.590 1113 0.54 0.00 0 1113 75 2.480 1142 0.53 0.00 0 1142 80 2.380 1169 0.53 0.00 0 1169 85 2.290 1195 0.53 0.00 0 1195 90 2.210 1221 0.53 0.00 0 1221 95 2.130 1242 0.53 0.00 0 1242 100 2.060 1264 0.53 0.00 0 1264 105 2.000 1289 0.52 0.00 0 1289 110 1.940 1310 0.52 0.00 0 1310 115 1.890 1334 0.52 0.00 0 1334 120 1.840 1355 0.52 0.00 0 1355 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. A = Tc = Project Location : Design Point C = Design Storm DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 207-016 Pond No : p1 100-yr 1.00 5.00 min 1355 ft3 0.44 acres 0.031 ac-ft Max Release Rate = 2.15 cfs Time (min) Ft Collins 100-yr Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor (Qav cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 9.950 1313 1.00 2.15 644 669 10 7.720 2038 0.75 1.61 966 1072 15 6.520 2582 0.67 1.43 1288 1294 20 5.600 2957 0.63 1.34 1610 1347 25 4.980 3287 0.60 1.29 1932 1355 30 4.520 3580 0.58 1.25 2254 1326 35 4.080 3770 0.57 1.23 2576 1194 40 3.740 3949 0.56 1.21 2898 1052 45 3.460 4110 0.56 1.19 3220 891 50 3.230 4264 0.55 1.18 3542 722 55 3.030 4400 0.55 1.17 3864 536 60 2.860 4530 0.54 1.16 4186 345 65 2.720 4668 0.54 1.16 4508 160 70 2.590 4786 0.54 1.15 4830 -43 75 2.480 4910 0.53 1.14 5151 -241 80 2.380 5027 0.53 1.14 5473 -447 85 2.290 5139 0.53 1.14 5795 -657 90 2.210 5251 0.53 1.13 6117 -866 95 2.130 5342 0.53 1.13 6439 -1097 100 2.060 5438 0.53 1.13 6761 -1323 105 2.000 5544 0.52 1.12 7083 -1539 110 1.940 5634 0.52 1.12 7405 -1771 115 1.890 5738 0.52 1.12 7727 -1989 120 1.840 5829 0.52 1.12 8049 -2220 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 207-016 Elevations Credit Union Project Number : Project Name : Underground Pond - Release Rate A = Tc = APPENDIX C WATER QUALITY DESIGN COMPUTATIONS Project Tittle Date: Project Number Calcs By: Client Pond Designation 0.8 WQCV = Watershed inches of Runoff (inches) 92.00% a = Runoff Volume Reduction (constant) i = Total imperviouness Ratio (i = Iwq/100) 0.335 in A = 0.32 ac V = 0.01 ac-ft 390 cu. ft. V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event Elevations Credit Union September 3rd, 2016 207-016 B. Mathisen Underground Pond - Basin W.1 0.335 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq /100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) V * A 12 WQCV    Project Tittle Date: Project Number Calcs By: Client Pond Designation 0.8 WQCV = Watershed inches of Runoff (inches) 90.00% a = Runoff Volume Reduction (constant) i = Total imperviouness Ratio (i = Iwq/100) 0.321 in A = 0.12 ac V = 0.00 ac-ft 140 cu. ft. V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event Elevations Credit Union July 8th, 2016 207-016 B. Mathisen Underground Pond - Basin R.1 0.321 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq/100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV  a  0.91 i 3  1 . 19 i 2  0 . 78 i  WQCV  a  0.91 i 3  1 . 19 i 2  0 . 78 i  V 12 * A WQCV        12 hr 1355 cu. ft. SC-740 19 46 cu. ft. 530 cu. ft. 12 552 cu. ft. * 3 chambers required for Basin R.1 = 138 cu. ft. * 9 chambers required for Basin W.1 = 390 cu. ft. Number of chambers required for WQ= Total WQCV acquired= FAA Modified Required Detention = StormTech chambers used = Number of chambers required= Volume of a single chamber (assuming 0% porosity)= Required Water Quality within chambers= Project Tittle Date: Project Number Calcs By: Client Pond Designation 0.8 WQCV = Watershed inches of Runoff (inches) 57.00% a = Runoff Volume Reduction (constant) i = Total imperviouness Ratio (i = Iwq/100) 0.181 in A = 0.04 ac V = 0.00 ac-ft --> = 26.28 cu.ft. V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) Elevations Credit Union July 8th, 2016 207-016 B. Mathisen Rain Garden - Basin E.1 Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event 0.181 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq/100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV  a  0.91 i 3  1 . 19 i 2  0 . 78 i  WQCV  a  0.91 i 3  1 . 19 i 2  0 . 78 i  V 12 * A WQCV        12 hr Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 57.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.570 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.18 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 1,931 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 29.2 cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) DWQCV = 6 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 2.00 ft / ft Z < 4:1 (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin = 19 sq ft D) Actual Flat Surface Area AActual = 201 sq ft E) Area at Design Depth (Top Surface Area) ATop = 289 sq ft F) Rain Garden Total Volume VT= 123 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided? B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = 0.5 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = 29 cu ft iii) Orifice Diameter, 3/8" Minimum DO = 0.17 in MINIMUM DIAMETER = 3/8" Design Procedure Form: Rain Garden (RG) B. Mathisen Northern Engineering July 8, 2016 Elevations Credit Union Fort Collins - CO - Basin E.1 Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO RainGardens_BMP.xlsm, RG 7/8/2016, 1:47 PM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW THE LINER IF THE SUBGRADE IS ANGULAR 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) B. Mathisen Northern Engineering July 8, 2016 Elevations Credit Union Fort Collins - CO - Basin E.1 Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO RainGardens_BMP.xlsm, RG 7/8/2016, 1:47 PM APPENDIX D EROSION CONTROL REPORT Elevations Credit Union Final Erosion Control Report A with comprehensive the final construction Erosion and drawings. Sediment It should Control be Plan noted, (along however, with associated that any such details) Erosion will be and included Sediment the BMPs Control depicted, Plan and serves additional only as or a different general BMPs guide from to the those Contractor. included Staging may be and/necessary or phasing during of construction, or as required by the authorities having jurisdiction. It maintained shall be the and responsibility followed. The of the Erosion Contractor and Sediment to ensure Control erosion Plan control is intended measures to be are a properly living document, location of BMPs constantly as they adapting are installed, to site conditions removed or and modified needs. in The conjunction Contractor with shall construction update the activities. It is imperative to appropriately reflect the current site conditions at all times. The during Erosion construction, and Sediment as well Control as permanent Plan shall erosion address control both protection. temporary measures Best Management to be implemented Practices from not limited the Volume to, silt 3, fencing Chapter along 7 – the Construction disturbed perimeter, BMPs will gutter be utilized. protection Measures in the may adjacent include, roadways but are and clean-inlet up procedures, protection at designated proposed storm concrete inlets. washout Vehicle areas, tracking dumpsters, control and pads, job spill site containment restrooms shall and also be provided by the Contractor. Grading Plans at and final Erosion design will Control also Notes contain can a be full-found size Erosion on Sheet Control CS2 of Plan the as Utility well Plans. as a separate The Utility sheet dedicated Contractor to shall Erosion be aware Control of, Details. and adhere In addition to, the applicable to this report requirements and the referenced outlined in plan any sheets, existing the Development to issuance of Agreement(the Development s) of record, Construction as well Permit. as the Development Also, the Site Agreement, Contractor to for be this recorded project prior will be Public required Health to and secure Environment a Stormwater (CDPHE)Construction , Water General Quality Control Permit Division from the – Colorado Stormwater Department Program, of before shall develop commencing a comprehensive any earth disturbing StormWater activities. Management Prior to Plan securing (SWMP) said pursuant permit, to the CDPHE Site Contractor requirements inspections, and and maintenance guidelines. The of construction SWMP will BMPs. further describe and document the ongoing activities, APPENDIX E Soils Resource Report 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 Larimer County Natural Area, Colorado Resources Conservation Service July 1, 2016 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 (http:// 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 alternative means 2 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..................................................................................................................7 Soil Map................................................................................................................8 Legend..................................................................................................................9 Map Unit Legend................................................................................................10 Map Unit Descriptions........................................................................................10 Larimer County Area, Colorado......................................................................12 3—Altvan-Satanta loams, 0 to 3 percent slopes.........................................12 References............................................................................................................14 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 scientists classified and named the soils in the survey area, they compared the 5 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 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 6 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. 7 8 Custom Soil Resource Report Soil Map 4490030 4490040 4490050 4490060 4490070 4490080 4490030 4490040 4490050 4490060 4490070 4490080 493400 493410 493420 493430 493440 493450 493460 493470 493480 493400 493410 493420 493430 493440 493450 493460 493470 493480 40° 33' 41'' N 105° 4' 41'' W 40° 33' 41'' N 105° 4' 36'' W 40° 33' 39'' N 105° 4' 41'' W 40° 33' 39'' N 105° 4' 36'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:443 if printed on A landscape (11" x 8.5") sheet. 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: http://websoilsurvey.nrcs.usda.gov 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 Map Unit Legend Larimer County Area, Colorado (CO644) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 3 Altvan-Satanta loams, 0 to 3 percent slopes 0.8 100.0% Totals for Area of Interest 0.8 100.0% 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, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 10 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 11 Larimer County Area, Colorado 3—Altvan-Satanta loams, 0 to 3 percent slopes Map Unit Setting National map unit symbol: jpw2 Elevation: 5,200 to 6,200 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Altvan and similar soils: 45 percent Satanta and similar soils: 30 percent Minor components: 25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Altvan Setting Landform: Benches, terraces Landform position (three-dimensional): Side slope, tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium Typical profile H1 - 0 to 10 inches: loam H2 - 10 to 18 inches: clay loam, loam, sandy clay loam H2 - 10 to 18 inches: loam, fine sandy loam, silt loam H2 - 10 to 18 inches: gravelly sand, gravelly coarse sand, coarse sand H3 - 18 to 30 inches: H3 - 18 to 30 inches: H3 - 18 to 30 inches: H4 - 30 to 60 inches: H4 - 30 to 60 inches: H4 - 30 to 60 inches: Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 10 percent Available water storage in profile: Very high (about 13.2 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Custom Soil Resource Report 12 Hydrologic Soil Group: B Description of Satanta Setting Landform: Structural benches, terraces Landform position (three-dimensional): Side slope, tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium and/or eolian deposits Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 18 inches: loam, clay loam, sandy clay loam H2 - 9 to 18 inches: loam, clay loam, fine sandy loam H2 - 9 to 18 inches: H3 - 18 to 60 inches: H3 - 18 to 60 inches: H3 - 18 to 60 inches: Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 10 percent Available water storage in profile: Very high (about 27.4 inches) Interpretive groups Land capability classification (irrigated): 1 Land capability classification (nonirrigated): 3c Hydrologic Soil Group: B Minor Components Nunn Percent of map unit: 10 percent Larim Percent of map unit: 10 percent Stoneham Percent of map unit: 5 percent Custom Soil Resource Report 13 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 14 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 15 MAP POCKET HISTORIC DRAINAGE EXHIBIT PROPOSED DRAINAGE EXHIBIT S S E E E E E E E X X X X X X SS SS SS SS SS SS SS SS SS SS SS SS ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST U D S G G EV E E E E E E E E E RD RD UD UD UD UD UD UD E E W.1 OS.1 E.1 OS.3 os.1 ARTHUR DRIVE SPRING COURT os.3 ISOLATOR ROW ISOLATOR ROW COMBINATION INLET RAIN GARDEN RAIN GARDEN FLOW CONTROL MANHOLE 19 SC-740 STORMTECH CHAMBERS OVERFLOW GRATE 2' CURB CHASE S S X X X X X X X X X ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST E W EXISTING SIDEWALK CHASE COLLEGE AVENUE ARTHUR DRIVE SPRING COURT EXISTING CONCRETE PAN w e EXISTING INLET 12" PVC FL=4988.38 EASEMENT FOR SIDEWALK AND ELECTRICAL ACCESS PER REC. NO. 87041080 EASEMENT FOR WATERLINE PER BOOK 988, PAGE 351 AND BOOK 1394, PAGE 760 EXISTING 100-YR FEMA FLOODPLAIN FEMA REGULATED FLOOD FRINGE FEMA REGULATED FLOOD FRINGE EASEMENT FOR WATER LINE REC. NO. 87041081 TO BE VACATED EASEMENT FOR UNDERGROUND ELECTRIC LINE PER REC. NO. 87041082 4" PVC FL=4993.69 4" PVC FL=4993.43 EASEMENT FOR SANITARY MANHOLE PER REC. NO. 87041083 TO BE VACATED EXISTING CONCRETE CHASE EXISTING 30" RCP Sheet of 16 ELEVATIONS CREDIT UNION DRAWING FILENAME: D:\Projects\207-016\Dwg\Drng\207-016_EX_DRNG.dwg LAYOUT NAME: C7.01 DATE: Oct 25, 2016 - 10:26am CAD OPERATOR: blaine LIST OF XREFS: [207-016_xTopo] [207-016_xExist] [NES-xborder] These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET ENGINEER ING N O R T H E RN 10.25.2016 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 www.northernengineering.com Phone: 970.221.4158 NORTH ( IN FEET ) 1 inch = ft. 10 0 10 Feet 10 20 30 NORTH CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R ST A2 a3 4950 4:1 79.45  HP RUNOFF SUMMARY TABLE: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION NOTES: NORTH ( IN FEET ) 1 inch = ft. 10 0 10 Feet 10 20 30 NORTH CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R C7.01 EXISTING DRAINAGE PLAN LEGEND: ST A2 a3 4950 4:1 79.45  HP RUNOFF SUMMARY TABLE: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION NOTES: DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) w W 0.52 0.75 0.93 5.0 5.0 1.11 4.86 e E 0.20 0.75 0.93 5.0 5.0 0.42 1.83 16 7:1 12:1 50:1 36:1 18:1 24:1 9:1 12:1 23:1 11:1 14:1 OUTFALL TRASH ENCLOSURE RETAINING WALL FFE=95.35 PROPOSED SIDEWALK PROPOSED SIDEWALK PROPOSED SIDEWALK PROPOSED SIDEWALK EXISTING SIDEWALK RECONSTRUCTED SIDEWALK PROPOSED SIDEWALK PROPOSED PARKING LOT R.1 2' CONCRETE CHASE 2' SIDEWALK CHASE ISOLATOR ROW 446 SQ. FT. OF DIRECT RUNOFF OVER PEDESTRIAN WALKWAY FEMA FLOODPLAIN PROPOSED RETAINING WALL FEMA REGULATED FLOOD FRINGE FEMA REGULATED FLOOD FRINGE TRENCH DRAIN 16069 - 4982.06 NAVD 88 16110 - 4982.22 NAVD 88 2' CONCRETE PAN 2' CONCRETE PAN 3.5' PAN TRENCH DRAIN TRENCH DRAIN TRENCH DRAIN TRENCH DRAIN WATER QUALITY WEIR STRUCTURE WATER QUALITY WEIR STRUCTURE OS.2 EXISTING 30" RCP Sheet of 16 ELEVATIONS CREDIT UNION DRAWING FILENAME: D:\Projects\207-016\Dwg\Drng\207-016_DRNG.dwg LAYOUT NAME: C7.00 DATE: Oct 25, 2016 - 10:26am CAD OPERATOR: blaine LIST OF XREFS: [207-016_xExist] [207-016_xSite] [207-016_xPutil] [207-016_xPgrad] [NES-xborder] [207-016_xTopo] These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET ENGINEER ING N O R T H E RN 10.25.2016 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 www.northernengineering.com Phone: 970.221.4158 NORTH ( IN FEET ) 1 inch = ft. 10 0 10 Feet 10 20 30 NORTH CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R C7.00 DRAINAGE PLAN LEGEND: ST A2 a3 4950 4:1 79.45  HP RUNOFF SUMMARY TABLE: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION NOTES: DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) w.1 W.1 0.32 0.90 1.00 5.0 5.0 0.82 3.18 e.1 E.1 0.04 0.69 0.87 5.0 5.0 0.09 0.38 r.1 R.1 0.12 0.95 1.00 5.0 5.0 0.33 1.21 os.1 OS.1 0.05 0.28 0.35 5.0 5.0 0.04 0.17 os.2 OS.2 0.04 0.90 1.00 5.0 5.0 0.09 0.35 os.3 OS.3 0.15 0.51 0.63 5.0 5.0 0.22 0.95 15 COMMERCIAL AC the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 10, Sep 22, 2015 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Apr 22, 2011—Apr 28, 2011 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 9    = 12 hr Project Location : Design Point C = Design Storm Page 1 of 1 207-016_DetentionVolume_FAAModified Method - Find Release.xls Elevations Credit Union Project Number : Project Name : Underground Pond - Detention Page 1 of 1 207-016_DetentionVolume_FAAModified Method - Zero Release.xls COMBINED DEVELOPED TIME OF CONCENTRATION COMPUTATIONS B. Mathisen July 12th,2016 Design Point Basin IDs Overland Flow Gutter/Pipe Flow Swale Flow Time of Concentration (Equation RO-4)   1 3 1 . 87 1 . 1 * S Ti   C Cf L Page 5 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\Comb-Tc-10-yr_&_100-yr Coefficient Composite % Imperv. OS OS1, OS2, OS3 10210 0.23 1113.76 0.03 2808.42 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.52 0.52 0.65 36% OS3 W1,R1 & OS3 25821 0.59 13005.26 0.30 2331.15 0.05 5282.39 0.12 0.00 0.00 0.00 0.00 0.28 0.88 0.88 1.00 77% OS1 OS1, OS2 & E1 5541 0.13 0.00 0.00 2737.52 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.28 1.02 1.02 1.00 44% COMBINED DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS **Soil Classification of site is Sandy Loam** 10-year Cf = 1.00 Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. Page 4 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\Comb-C-Values os.1 OS.1 No 0.28 0.28 0.35 29 25.20% 2.8 2.8 2.6 N/A N/A N/A N/A N/A 5 5 5 os.2 OS.2 No 0.90 0.90 1.00 32 4.90% 1.2 1.2 0.6 N/A N/A N/A N/A N/A 5 5 5 os.3 OS.3 No 0.51 0.51 0.63 43 13.80% 3.0 3.0 2.4 N/A N/A N/A N/A N/A 5 5 5 DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Gutter/Pipe Flow Swale Flow Design Point Basin Overland Flow B. Mathisen July 12th,2016 Time of Concentration (Equation RO-4)   1 3 1 . 87 1 . 1 * S Ti   C Cf L Page 2 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\Tc-10-yr_&_100-yr 10-year Cf = 1.00 July 12th,2016 **Soil Classification of site is Clay Loam** Page 1 of 23 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Proposed_final).xlsx\C-Values Gutter/Pipe Flow Swale Flow Design Point Basin Overland Flow B. Mathisen July 12th, 2016 Time of Concentration (Equation RO-4)   1 3 1 . 87 1 . 1 * S Ti   C Cf L Page 2 of 20 D:\Projects\207-016\Drainage\Hydrology\207-016_Rational-Calcs(Historic).xlsx\Tc-10-yr_&_100-yr