City of Fort Collins. Spring Creek Place (2105 South College Avenue) Preliminary Drainage Report

Transcription

1 City of Fort Collins Spring Creek Place (2105 South College Avenue) Preliminary Drainage Report OCTOBER 2016 VERSION 3 Prepared By: 4582 South Ulster Street, Suite 1500 Denver, CO Daniel L. Skeehan, P.E. Registered Professional Engineer State of Colorado No

2 INTRODUCTION The proposed 2105 South College Avenue Project is located within the Northeast Quarter of Section 23, Township 7 North, Range 69 West of the Sixth Principal Meridian, City of Fort Collins, County of Larimer, Colorado. The site is bound by an existing self-storage business and undeveloped land to the north, an existing drive aisle and retail development to the east, an existing parking lot and retail development to the south and the MAX Spring Creek Bus Station to the west. A vicinity map is provided below. PROPOSED DEVELOPMENT This project will be developed on a platted tract located in the northeast quarter of Section 23, Township 7 North, Range 69 West of the 6 th PM. The site is approximately 2.22 acres and contains two existing buildings with associated surface parking. The site is divided topographically with half of the site sloping to the northeast and the other half sloping to the northwest at 1% to 5%. The soil on the site is 73% Nunn loam (73), which is classified as Hydrologic Soil Group C; and 27% Altvan-Satanta loams (4), which is classified as Hydrologic Soil Group B. The soil Classification Map can be found in Appendix A. The site is currently zoned C-G (General Commercial). The proposed land uses for this site will consist of standard multi-family residential housing and structured parking. 2

3 Preliminary Drainage Report 2105 S. College Ave Fort Collins, Colorado HISTORIC DRAINAGE The existing Site drains to the northwest and northeast at slopes of 1% to 5%. There are currently no existing on-site water quality or detention improvements. The Site and the surrounding area are considered part of the Spring Creek Drainage Basin and ultimately outfall to the Poudre River to the northeast of the site. The majority of existing flows for this site are conveyed into an existing inlet at the northwest corner of the site which flows into a vegetated swale until it is intercepted by Spring Creek. This system was installed as part of the MAX BRT system, and select portion of the associated drainage report are included in Appendix C. Additional flows either surface flow into an existing irrigation ditch or surface flow to an existing curb inlet in S. College Avenue. Flows captured within S. College Avenue travel through an existing underground storm drainage system and ultimately discharge into Spring Creek. The site is located within City of Fort Collins Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map Number 08069C0987G, revised May 2, 2012 and is designated as an area outside of the 500-year floodplain. The FEMA Firmette is included in Appendix A. DESIGN CRITERIA The City of Fort Collins Amendments to the Urban Drainage and Flood Control District Criteria Manual, (Criteria Manual) and the Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volumes 1, 2, and 3 (Drainage Manual), with latest revisions, were used to prepare the storm calculations. Weighted impervious values were calculated and used for the site area in accordance with the Criteria Manual and Drainage Manual. Hydrologic Criteria The existing and proposed imperviousness of the site was determined in order to evaluate the Project s potential impacts on stormwater runoff. A topographic survey and knowledge of the Site was utilized for this analysis. The existing and proposed imperviousness of the Site were determined to be 93% and 84% respectively. This analysis is included in Appendix B. A drainage area map representing the existing conditions has been included in Appendix D, and the proposed conditions has been included in Appendix C. The 2-year and 100-year storm events were used in determining rainfall and runoff for the proposed site. Table RA-7 of the Criteria Manual was used to determine rainfall data for the storm events and has been included in Appendix B. The 5-minute rainfall intensities used for the calculations at the site were 2.85 inches per hour and 9.95 inches per hour for the 2 and 100-year events, respectively. Table RO-10 from the Criteria Manual was utilized to obtain the runoff coefficients based upon the character of surface, resulting coefficient values of 0.85 and 0.90 for the 2 and 100-year events, respectively. As the imperviousness of the Site is decreasing with redevelopment, on-site detention is not required. However, due to limited available capacity in the receiving off-site storm conveyance systems, detention may be required to mitigate flows to any receiving off-site storm conveyance system that exceed capacity. The proposed development contemplates increasing the discharge to the west, requiring on-site detention to mitigate the increased discharge. Detention for the proposed development will be provided by an onsite underground detention facility to be located in the northwest corner of the site. Required volumes for the detention facility were determined using the Modified Rational Formula-based FAA Method as outlined 3

4 within Volume 2, Chapter 10, Section of the Criteria Manual. Standard release rates were also determined as outlined by Volume 1, Chapter 1, Section 1.6 of the Criteria Manual. Hydraulic Criteria The design will include a private storm sewer system connecting into existing public storm sewer inlet at the northwest of the site, adjacent to the MAX bus facility. The storm sewer and inlets will be designed to provide for the 100-year event. Calculations for the private storm sewer system and HGL will be completed using StormCAD and included in the Final Drainage Report. There are no major drainage ways located on the proposed site. Water Quality Treatment Criteria Applicable water quality design criteria is referenced from Volume 3, Section 3.0 of the Drainage Manual. Permanent best management practices associated with the water quality treatment design will be per the Criteria Manual and discussed in further detail in the Drainage Plan section. WQCV Watershed Inches = a*(0.91i i i) =0.8*(0.91(0.84) (0.84) (0.84)) =0.284 watershed inches WQCV other= (WQCV/0.43)*(d 6) = (0.284/0.43)*0.43 =0.284 ac-ft V = (WQCV/12)*(A) = (0.284/12)*2.22 =0.053 ac-ft (2,309 ft 3 )* i = Composite Tributary Imperviousness [%] A = Area [ac] a = Coefficient of drain time (a = 0.8 for 12-hour drain time) d 6 = depth of average runoff producing storm from Figure 3-1 from Urban Storm Drainage Criteria Manual Volume 3 *Per Volume 3, Chapter 3, Section 3.1 of the Criteria Manual 75% of any newly developed or redeveloped area must be treated using one or a combination of LID techniques. DRAINAGE PLAN GENERAL CONCEPT The site was divided into seven onsite sub-basins which are described in greater detail in the following section. BMPs were selected utilizing the four step process outlined in Volume 3, Chapter 1, Section 4 of the Drainage Manual: 4

5 Preliminary Drainage Report 2105 S. College Ave Fort Collins, Colorado 1. Employ runoff reduction practices - The redevelopment on an urban site provides limited opportunities to employ runoff reduction practices. Site has been developed to install landscaping wherever pavement (or building) is not required. 2. Implement BMPs that provide a water quality capture volume with a slow release Majority of site will be treated by two water quality BMPs; an existing mechanical separator that was installed as part of the MAX improvements located immediately downstream of the western connection point and an underground chamber/filtration system to be install as part of this development. 3. Stabilize streams Not applicable. This development is not adjacent to a stream, nor directly impact the downstream water body (Spring Creek). 4. Implement site specific and other source control BMPs Trash containers, recycling containers, and the majority of vehicular parking will be located inside the parking structure to reduce potential for contamination discharges. Runoff generated by the majority of these drainage basins will be conveyed into a proposed storm sewer system and will be treated by a WQ BMP before being detained within a proposed underground detention facility. Flows from the underground detention facility will outfall into an existing storm drain inlet located in the northwest corner of the site near the MAX Spring Creek Bus Station. A proposed drainage area map which shows the limits of these sub-basins has been provided in Appendix C. Calculations related to the preliminary sizing of the storm sewer pipes have been included in Appendix B. SPECIFIC DETAILS WQCV Device Water quality for the proposed development is currently provided by an off-site WQ BMP located at the Max Station. In addition, a Low Impact Development (LID) system is proposed and will be provided by means of a proposed underground chamber/filtration system/proprietary device which will treat ac-ft (1,742 ft 3 ) or 75% of the required ac-ft (2,309 ft 3 ) water quality volume. The proposed device is still being specified, but the ADS StormTech system is being considered. An impervious liner may be required to prevent saturation of soils adjacent to building foundation. Based on conversations with Staff, we understand this proposed system may be used to meet the City s LID requirements by treating 75% of the total WQCV (Volume 3, Section 3.1 of the Criteria Manual). The proposed underground chamber/filtration system is in addition to the existing mechanical separator located downstream of the western point of connection, at the Max Station, resulting in a redundant system. Detention Facility The underground detention facility has been sized and designed using the Modified FAA method as outlined by Volume 2, Chapter 10, Section of the Criteria Manual with City of Fort Collins precipitation data and requires acre-feet (5,010 ft 3 ) for the 1.65 acres contributing runoff area. The volume provided in the proposed water quality and underground detention facility will meet or exceed the required ac-ft volume. The proposed water quality and detention facility will discharge at a rate of 4.37 cfs and 8.79 cfs for the 2 and 100-year events respectively. These values were determined by finding the historical flow rates to the existing inlet in the northwest corner of the site (Existing basin B1 Q100 = 9.47 cfs). Proposed flows to this storm sewer structure will include a combination of overland flows and flows which will have passed through the combined Water Quality BMP and Detention Facility. To determine the proposed discharge release rates from the Detention Facility, the overland flows from sub-basin 25 (SB25 Q100 = 0.68 cfs), described below, were subtracted from the historical flows. Flows from the detention facility will be regulated using a combination of a restrictor plate and an orifice. Supporting calculations related to the 5

6 sizing of the detention facility using the Modified FAA method are available in Appendix B. Calculations and sizes for the 2 and 100-year detention outlets will be included in the Final Drainage Report. The remaining 0.34 acres (sub basin 10, Q100 = 2.89 cfs) will continue to surface drain to the east into South College Avenue. This is a decrease from the existing 1.21 acres (existing sub-basin B2, B3, B4; totaling Q100 = cfs) that drain into South College Ave. The improvements to this area are minimal and consist of utility connections, pavement replacement, and hardscape and landscape immediately adjacent to the building. Inlets There are four proposed inlets on the project site. All inlets and storm sewer will be designed to convey the 100-year storm event. The type of inlet for each is indicated in Table 1. Discussion of each inlet by sub-basin follows the table. Table 1. Inlet Types Design Point Sub-basin Structure Type CB-3 15 Sump Inlet CB-2 20 On-Grade Inlet CB-4 30 Sump Inlet CB-5 35 Sump Inlet Sub-basin 05 Sub-basin 05 is 1.43 acres and consists of building/roof area. Runoff within this sub-basin will collect at roof drains that tie into the private underground storm sewer that discharges to the Underground Detention Facility. The runoff coefficients for this sub-basin are 0.95 and 1.00 for the 2-year and 100-year storm, respectively. Sub-basin 10 Sub-basin 10 is 0.13 acres and consists of parking, sidewalk and landscaped areas. Runoff within this subbasin will enter inlet CB-6 and be conveyed to the Underground Detention Facility through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.74 and 0.79 for the 2-year and 100-year storm, respectively. 6

7 Preliminary Drainage Report 2105 S. College Ave Fort Collins, Colorado Sub-basin 15 Sub-basin 15 is 0.09 acres and consists of a paved fire lane drive aisle. Runoff within this sub-basin will enter inlet CB-3 and be conveyed to the Underground Detention Facility through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.94 and 0.99 for the 2-year and 100-year storm, respectively. If inlet CB-3 were to plug, the runoff for this basin would flow north onto an existing access drive following its historic path to the Sherwood Lateral. Sub-basin 20 Sub-basin 20 is 0.05 acres and consists of a paved fire lane drive aisle. Runoff within this sub-basin will enter inlet CB-2 and be conveyed to the Underground Detention Facility through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.95 and 1.00 for the 2-year and 100-year storm, respectively. If inlet CB-2 were to plug, the runoff for this sub-basin would flow west into the existing inlet CB-1 following its historic path. Sub-basin 25 Sub-basin 25 is 0.23 acres and consists of sidewalk and landscaped areas. Runoff within this sub-basin will enter inlet CB-1 and be conveyed off-site through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.28 and 0.32 for the 2-year and 100-year storm, respectively. If inlet CB-1 were to plug, the runoff for the basin would flow north following its historic path to Sherwood Lateral. Sub-basin 30 Sub-basin 30 is 0.05 acres and consists of sidewalk and landscaped areas. Runoff within this sub-basin will enter area inlet CB-4 and be conveyed to the Underground Detention Vault through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.67 and 0.72 for the 2-year and 100-year storm, respectively. If inlet CB-4 were to plug, the runoff for the basin would flow west and north following its historic path to the Sherwood Lateral. Sub-basin 35 Sub-basin 35 is 0.07 acres and consists of sidewalk and landscaped areas. Runoff within this sub-basin will enter inlet CB-5 and be conveyed to the Underground Detention Facility through a private underground storm sewer. The runoff coefficients for this sub-basin are 0.69 and 0.74 for the 2-year and 100-year storm, respectively. If inlet CB-5 were to plug, the runoff for the basin would flow west and north following its historic path to the Sherwood Lateral. Sub-basin 40 Sub-basin 40 is 0.21 acres and consists of parking, sidewalk and landscaped areas. Runoff within this subbasin will surface flow onto S. College Avenue following its historical drainage path. The runoff coefficients for this sub-basin are 0.92 and 0.97 for the 2-year and 100-year storm, respectively. 7

8 IMPLEMENTATION AND PHASING The Project will disturb over 10,000 square feet of stabilized ground; therefore, a Stormwater Management Plan is required. Construction will be implemented in two phases due to the size of the project and types of improvements required for the Project. The Stormwater Management Plans and Details will be provided in the Project Construction Documents. CONCLUSIONS COMPLIANCE WITH STANDARDS The 2105 S. College Avenue project is in compliance with City of Fort Collins criteria for storm drainage design. The Fort Collins Amendments to the Urban Drainage and Flood Control District Criteria Manual and the Urban Drainage Flood Control District Urban Storm Drainage Criteria Manual Volumes 1, 2, and 3 have been utilized in the design of the storm sewer. The private onsite storm sewer system for this site will provide conveyance for the 100-yr storm event. SUMMARY OF CONCEPT The onsite drainage basins use private roof drains, storm inlets, and curb and gutter to collect and convey runoff generated within the project site to an existing storm sewer in the northwest corner of the site. With the exception of flow in sub-basins 10 and 25, all stormwater runoff will be collected and routed through a WQ BMP and onsite underground detention facility before entering the existing storm sewer system in the northwest corner of the site. This design will provide LID Water Quality for a minimum of 75% of the site, or all of the sub-basins except for 10 and 25, as well as limit damages due to erosion. In addition, all flows that enter the underground detention facility will be routed through an existing off-site water quality BMP. REFERENCES Fort Collins Amendments to the Urban Drainage and Flood Control District, City of Fort Collins. Urban Storm Drainage Criteria Manual, Volume 1-3, Urban Drainage and Flood Control District, Denver, CO; January 2016, with latest revisions. APPENDICES A. Firmette and NRCS Data B. Hydrology and Hydraulics C. Proposed Drainage Map D. Existing Drainage Map 8

9 APPENDIX A 9

10 105 4' 46'' W Hydrologic Soil Group Larimer County Area, Colorado (2105 S. College Ave) 105 4' 39'' W 40 33' 38'' N ' 38'' N ' 34'' N ' 34'' N 105 4' 46'' W N Map Scale: 1:847 if printed on A landscape (11" x 8.5") sheet. Meters Feet Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS ' 39'' W Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/13/2016 Page 1 of 4

11 Hydrologic Soil Group Larimer County Area, Colorado (2105 S. College Ave) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: 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. Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/13/2016 Page 2 of 4

12 Hydrologic Soil Group Larimer County Area, Colorado 2105 S. College Ave Hydrologic Soil Group Hydrologic Soil Group Summary by Map Unit Larimer County Area, Colorado (CO644) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 4 Altvan-Satanta loams, 3 to 9 percent slopes 73 Nunn clay loam, 0 to 1 percent slopes B % C % Totals for Area of Interest % Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/13/2016 Page 3 of 4

13 Hydrologic Soil Group Larimer County Area, Colorado 2105 S. College Ave Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/13/2016 Page 4 of 4

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15 APPENDIX B 10

16 (11) Section 4.0 is amended to read as follows: 4.0 Intensity-Duration-Frequency Curves for Rational Method: The one-hour rainfall Intensity-Duration-Frequency tables for use the Rational Method of runoff analysis are provided in Table RA-7 and in Table RA-8. Table RA-7 -- City of Fort Collins Rainfall Intensity-Duration-Frequency Table for Use with the Rational Method (5 minutes to 30 minutes) Duration (min) 2-Year 10-Year 100-Year Intensity (in/hr) Intensity (in/hr) Intensity (in/hr)

17 Table RA-8 -- City of Fort Collins Rainfall Intensity-Duration-Frequency Table for Use with the Rational Method (31 minutes to 60 minutes) Duration (min) 2-Year 10-Year 100-Year Intensity (in/hr) Intensity (in/hr) Intensity (in/hr)

18 Table RO-10 Rational Method Minor Storm Runoff Coefficients for Zoning Classifications Description of Area or Zoning Coefficient R-F 0.3 U-E 0.3 L-M-In 0.55 R-L, N-C-L 0.6 M-M-N, N-C-M 0.65 N-C-B 0.7 Business: C-C-N, C-C-R, C-N, N-C, C-S 0.95 R-D-R, C-C, C-L 0.95 D, C 0.95 H-C 0.95 C-S 0.95 Industrial: E 0.85 I 0.95 Undeveloped: R-C, T 0.2 P-O-L 0.25 For guidance regarding zoning districts and classifications of such districts please refer to Article Four of the City Land Use Code, as amended. 40

19 SOUTH COLLEGE AVENUE 10/4/ S. College Sub-Basin Characteristics Existing Site Area (sf) Area (Ac) Basin % Landscape Roof Pavement I WEIGHTED C 2 C 100 Entire Site 96, % % Proposed Site Area (sf) Area (Ac) Basin % Landscape Roof Pavement I WEIGHTED C 2 C , % % , % % , % % , % % , % % , % % , % % , % % Total 96, % % Landuse I C 2 C 100 Landscape 2% Permeable Pavement 65% Roof 95% Drives and Walks 95% Paved Streets 95% K:\DEN_Civil\ _Fort Collins - College & Rutgers\_Project Files\Eng\Drainage\CALCS.xls

20 SOUTH COLLEGE AVENUE 10/4/ S. College Sub-Basin Characteristics - Proposed 2-Year Design Storm Runoff Calculations (Rational Method Procedure) BASIN INFORMATION DIRECT RUNOFF DRAIN AREA RUNOFF T(c) C x A I Q BASIN ac. COEFF min in/hr cfs Net Runoff: Year Design Storm Runoff Calculations (Rational Method Procedure) BASIN INFORMATION DIRECT RUNOFF DRAIN AREA RUNOFF T(c) C x A I Q BASIN ac. COEFF min in/hr cfs Net Runoff: 18.8 K:\DEN_Civil\ _Fort Collins - College & Rutgers\_Project Files\Eng\Drainage\CALCS.xls

21 SOUTH COLLEGE AVENUE 8/11/ S. College Sub-Basin Characteristics - Existing 2-Year Design Storm Runoff Calculations (Rational Method Procedure) BASIN INFORMATION DIRECT RUNOFF DRAIN AREA RUNOFF T(c) C x A I Q BASIN ac. COEFF min in/hr cfs B B B B Net Runoff: Year Design Storm Runoff Calculations (Rational Method Procedure) BASIN INFORMATION DRAIN AREA RUNOFF T(c) C x A DIRECT RUNOFF I Q BASIN ac. COEFF min in/hr cfs B B B B Net Runoff: 20.9 K:\DEN_Civil\ _Fort Collins - College & Rutgers\_Project Files\Eng\Drainage\CALCS.xls

22 Equations: A trib. To pond = 1.78 acre Q D = CiA C 100 = 0.97 V i = T*CiA = T*Q D Developed C*A = 1.73 acre V o =m*q PO *(60*T) Q PO = 8.79 cfs S = V i - V o tc = 5 min Rainfall intensity from Larimer County Area 1 IDF Curve Storm Rainfall Q D Vol. In Outflow Vol. Out Storage Storage Duration, T Intensity, i (cfs) V i Adjustment V o S S (min) (in/hr) (ft 3 ) Factor, m (ft 3 ) (ft 3 ) (ac-ft) Required Storage Volume: 5010 ft acre-ft

23 Scenario: Base CO-9 StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

24 FlexTable: Conduit Table CO-5 CO-1 CO-4 CO-3 CO-8 CO-9 CO-10 Label Elevation Ground (Start) (ft) 5, , , , , , , Start Node CB-5 CB-2 CB-4 CB-Roof CB-6 MH-12 CB-3 Hydraulic Grade Line (In) (ft) 5, , , , , , , Stop Node CB-4 O-2 CB-Roof O-1 MH-12 O-3 MH-12 Invert (Stop) (ft) 5, , , , , , , Length (Unified) (ft) Elevation Ground (Stop) (ft) 5, , , , , , , Slope (Calculated) (ft/ft) Hydraulic Grade Line (Out) (ft) 5, , , , , , , Flow (cfs) Capacity (Full Flow) (cfs) Velocity (ft/s) Invert (Start) (ft) 5, , , , , , , StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

25 FlexTable: Catch Basin Table Label CB-5 CB-2 CB-3 CB-4 CB-Roof CB-6 Elevation (Rim) (ft) 5, , , , , , Hydraulic Grade Line (In) (ft) 5, , , , , , External CA (acres) Inlet Type Full Capture Full Capture Full Capture Full Capture Full Capture Full Capture Flow (Total Out) (cfs) Intercepted Fixed Flow (cfs) Headloss Coefficient (Standard) StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

26 Profile Report Engineering Profile - Profile - 1 (StormCAD 2016_1004.stsw) StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

27 Profile Report Engineering Profile - Profile - 1 (StormCAD 2016_1004.stsw) StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

28 Profile Report Engineering Profile - Profile - 2 (StormCAD 2016_1004.stsw) 5, CB-2 Rim: 5, ft Invert: 5, ft O-2 Rim: 5, ft Invert: 5, ft 5, CO-1: ft/ft Circle in 5, Station (ft) StormCAD 2016_1004.stsw 10/4/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

29 Profile Report Engineering Profile - Profile - South (StormCAD 2016_0811.stsw) StormCAD 2016_0811.stsw 8/11/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 4) [ ] Page 1 of 1

30 Spring Creek Place - Discharge Pipe (proposed BMP to existing inlet) Project Description Friction Method Solve For Manning Formula Discharge Input Data Roughness Coefficient Channel Slope ft/ft Normal Depth 1.50 ft Diameter 1.50 ft Results Discharge 9.66 ft³/s Flow Area 1.77 ft² Wetted Perimeter 4.71 ft Hydraulic Radius 0.38 ft Top Width 0.00 ft Critical Depth 1.20 ft Percent Full % Critical Slope ft/ft Velocity 5.46 ft/s Velocity Head 0.46 ft Specific Energy 1.96 ft Froude Number 0.00 Maximum Discharge ft³/s Discharge Full 9.66 ft³/s Slope Full ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise % Downstream Velocity Infinity ft/s Kimley-Horn and Associates, Inc. 8/11/2016 4:49:10 PM Bentley Systems, Inc. Haestad Methods Solution Bentley Center FlowMaster V8i (SELECTseries 1) [ ] 27 Siemons Company Drive Suite 200 W Watertown, CT USA Page 1 of 2

31 Spring Creek Place - Discharge Pipe (proposed BMP to existing inlet) GVF Output Data Upstream Velocity Infinity ft/s Normal Depth 1.50 ft Critical Depth 1.20 ft Channel Slope ft/ft Critical Slope ft/ft Kimley-Horn and Associates, Inc. 8/11/2016 4:49:10 PM Bentley Systems, Inc. Haestad Methods Solution Bentley Center FlowMaster V8i (SELECTseries 1) [ ] 27 Siemons Company Drive Suite 200 W Watertown, CT USA Page 2 of 2

32 APPENDIX C 11

33 C&S RR COLORADO STATE UNIVERSITY ZONE: ZONE: CSU ZONE: CG COLLEGE AVE. COLUMBIA RD. RL A BIG A SELF STORAGE (N.A.P.) VACANT LAND (N.A.P.) LEGEND N O'DEA ELEMENTARY SCHOOL SPRING CREEK STATION T WHOLE FOODS (N.A.P.) MATTRESS FIRM (N.A.P.) PROPOSED DRAINAGE AREA MAP SPRING CREEK PLACE FORT COLLINS, CO NORTH DANIEL L. SKEEHAN COLORADO PE No R

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42 APPENDIX D 12

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