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Home My WebLink AboutFAITH FAMILY HOSPITALITY TRANSITIONAL HOUSE - PDP - PDP160044 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDRAINAGE REPORT FOR Faith Family 317-321 Sherwood Street Fort Collins, CO 80521 Prepared for: Kenny Lee Architecture Group Inc. 209 E 4th Street Loveland, CO 80537 Prepared by: www.quality-engineering.com 2637 Midpoint Drive, Suite E Fort Collins, Colorado 80524 (970) 416-7891 QE Project No: 7040-007 Date: November 14, 2016 Faith Family FINAL DRAINAGE REPORT ENGINEER’S CERTIFICATION I hereby certify that this Final Drainage Report for the design of stormwater management facilities for the Faith Family Project was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards for the owners thereof. Cody Geisendorfer, P.E. Registered Professional Engineer State of Colorado No. 41326 I. Table of Contents I. GENERAL LOCATION AND DESCRIPTION ......................................... 1 A. Location .................................................................................................................... 1 B. Description of Property ........................................................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS .................................................. 2 A. Major Basin Description ......................................................................................... 2 B. Sub-Basin Description ............................................................................................. 2 III. DRAINAGE CRITERIA ............................................................................... 2 A. Regulations ............................................................................................................... 2 B. Implementation of the “Four Step Process” .......................................................... 3 C. Development Criteria Reference and Constraints ................................................ 3 D. Hydrological Criteria............................................................................................... 4 E. Hydraulic Criteria ................................................................................................... 4 F. Modifications of Criteria ......................................................................................... 5 IV. DRAINAGE FACILITY DESIGN ............................................................... 5 A. General Concept....................................................................................................... 5 B. Specific Details ......................................................................................................... 5 V. CONCLUSIONS ............................................................................................. 6 A. Compliance with Standards .................................................................................... 6 B. Drainage Concept..................................................................................................... 6 VI. REFERENCES ............................................................................................... 6 VII. APPENDICES A. Hydrologic Computations Vicinity Map Fort Collins Flood Map USGS Soil Map Fort Collins Rainfall Intensity Curve Fort Collins Rainfall Intensity Table Table RO-3 Recommended Percentage Imperviousness Values Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows B. Map Pocket Drainage Plan I. GENERAL LOCATION AND DESCRIPTION A. Location The proposed site is located in the southeast quarter (NE ¼) of Section 11, Township 7 North, Range 69 West of the 6th P.M. in Larimer County, Colorado. Specifically, the property is located on Sherwood Street between Magnolia Street and Olive Street. The property address is 317-321 Sherwood Street, Fort Collins, Colorado, 80521. (Please see the vicinity map located in the Appendix A). B. Description of Property The property’s parcel number are 9711420904 and 9711420903. The site is located on Lots 3 and 4, Block 73 Fort Collins Subdivision and is currently 0.436 acres of residential land surrounded by the residential lots to the north and south, an alley to the west, and Sherwood Street to the east. The site can be accessed from Sherwood Street and the existing alley. Two gravel patches provide on-site parking and the site can be accessed from the alley. The existing property is a residential building with no occupants that drains west to Sherwood Street through a drainage channel along the north property line. Sherwood Street drains south to the existing inlet, where it is conveyed to the Poudre River. Runoff from the alley flows south to West Magnolia Street, where is flows east to an existing storm inlet. There are generally no offsite flows that drain toward the property. The entire site is located within the city flood fringe. The city floodway encompasses all of Sherwood Street and West Magnolia Street and extends to the back of the sidewalk. (see City Flood Risk Map in Appendix A). According to the NRCS soils map survey, the native soils consist of Fort Collins Loam, which is a Type “C” soils. These soils 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. There are no irrigation facilities located within the proposed site area. The proposed development will consist of the construction of an off-street permeable paver parking lot that will act as a parking for the residents and employees of Faith Family. The permeable paver parking lot will have an underdrain network of 4” perforated that drains into a bottomless dry well. The existing gravel alley will also be paved with asphalt from the northern property line to Magnolia Street. II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description The proposed site is located within the Old Town Basin. The Old Town Drainage Basin is located in north-central Fort Collins. The basin has a drainage area of approximately 2,120 acres, including approximately 400 acres of the Colorado State University campus. The entire basin is urbanized, with some development dating back to the late 1800s. Generally, the basin drains from west to east. The Old Town Basin receives some runoff water from the Canal Importation Basin directly west of Old Town. Most of the water from Old Town drains to the Poudre River, just to the east. B. Sub-Basin Description Historically, most of the site drains east to Sherwood Street. The developed site is delineated into two sub-basins, with underground detention designed to provide the required water quality capture volume. Sub-basin B1, (0.064 acres), consists of an existing shed and gravel parking lots. Rainfall travels via overland flow from east to west, into the existing alley. Once the flow enters the alley, it is conveyed to the flowline of Magnolia Street. The flow from the site eventually drains into the Poudre River. Sub-basin B2, (0.372 acres), consists of an existing building, landscaped area, and concrete walkways. Rainfall travels via overland flow from west to east, where it will concentrate in a concrete drainage channel. Once the flow is concentrated into the channel, it is conveyed to the flowline Sherwood Street. The flow from the site eventually drains into the Poudre River. Currently, offsite flows do not enter the site property. This will not change after the site has been developed. III. DRAINAGE CRITERIA A. Regulations Drainage design criteria specified in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual (FCSDCM) and the Urban Storm Drainage Criteria Manual, Volume 3 by the Urban Drainage and Flood Control District (UDFCD) have been referenced in the preparation of this study. B. Implementation of the “Four Step Process” The overall stormwater management strategy employed with this parking lot and alley improvements 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. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By selecting a site with historically undetained runoff, the burden of development will be significantly less with underground detention. Also, permeable pavers are used to reduce the area of impervious surfaces, reducing the effects of imperviousness. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release. Demolishing the building, adding landscaped areas, and constructing permeable pavers will cause stormwater runoff to decrease from the site. The runoff will be released through the bottom of a dry well. The primary water quality will occur in the permeable pavers and dry well. Refer to the map pocket for permeable paver details and cross-sections. The permeable pavers will increase water quality and promote infiltration. Water quality treatment for 50% of the site is provided for in the Udall Natural Area water treatment facility. Step 3 – Stabilize Drainageways. The Poudre River is the governing drainageway for the proposed site. The proposed project indirectly helps achieve a better stabilized drainageway nonetheless. By improving the water quality and increasing infiltration, the likelihood of bed and bank erosion from this site is greatly reduced. Step 4 – Implement Site Specific and Other Source Control BMPs. The Family Faith site contains a plethora of source control BMPs. Permeable Pavement Systems: Flow from the parking lot will directly flow into the void area of the pavers avoiding any extra pollutant-flow contact time. Dry Well: Flow entering the dry well will slowly infiltrate into the soil, filtering out any pollutants. C. Development Criteria Reference and Constraints The criteria used as the basis for analysis and design of stormwater management improvements for this site are those found in the references cited. To the knowledge of the author, there are no other capital drainage improvements planned for this portion of the site; aside from those referred to above, that would constrain or otherwise influence the design of the stormwater improvements for this site. D. Hydrological Criteria Stormwater runoff from the respective sub-basins of the site is analyzed for storms with 2- year and 100-year return frequencies. Due to the relatively small aggregate area of the tributary drainage sub-basins, the Rational Method was chosen for use in the design of the stormwater management improvements. The Rational Method provides that: Q = CIA, where: Q = Design flow in cubic feet per second (cfs) C = Coefficient of runoff for the area under consideration I = Rainfall intensity for the design storm duration (in/hr) A = Area of the drainage sub-basin under consideration (ac) Peak flows were calculated using the Rational Method for the 2-year and 100-year storm events. This software uses the local 1-hour rainfall depth and Fort Collins rainfall intensities developed calculate rainfall intensities as a function of the time of concentration. These values were obtained by the City of Fort Collins Rainfall Intensity-Duration- Frequency (IDF) curve/table; Figure 3-1 and Table 3-1a, and can be found in the Appendix. Additionally, per City of Fort Collins, the coefficients have been multiplied by the appropriate storm factors. Percent imperviousness values were taken from Table RO-3, Recommended Percentage Imperviousness Values, UDCM (See Appendix). Soils of hydrologic soil type “C” dominate the site. Onsite runoff was calculated to determine the runoff differential between existing and developed conditions for use in sizing the WQCV as required by the FCSDM. The hydrologic basin parameters and runoff rates are included in the Appendices and include quantification of the allowable volume reduction. The USDFCD software UD-BMP v3.03 was used to calculate the required detention. The design worksheets included in the Appendices to this Final Drainage Report present documentation of the hydrologic calculations for the on-site storm drainage systems. E. Hydraulic Criteria Within this development, all runoff will be conveyed on the surface, initially as sheet flow and subsequently as concentrated flow in shallow pans and gutters. The assessment of required capacity and the sizing of the respective components of the drainage system are based on the anticipated runoff from the 100-year storm event. F. Modifications of Criteria There are no modifications or variances requested in connection with the design of the stormwater management for the Faith Family site development. IV. DRAINAGE FACILITY DESIGN A. General Concept The storm drainage system is designed to safely convey developed storm flows by sheet flow, concentrated pan, and gutter flow to the street flowlines. The design worksheets included in the Appendices to this Final Drainage Report present details of the hydrologic and hydraulic calculations pertinent to the design of the on-site storm drainage system. A drainage plan, showing the proposed development of the site and developed drainage patterns is included in the map pocket following the Appendices. B. Specific Details There are a number of collection and conveyance scenarios within the drainage regime associated with this development. The respective scenarios are described below. Sub-basin B1, (0.064 acres), consists of a permeable parking lot and landscaped areas. The runoff created by a 100-Year event is reduced from 0.45 cfs to 0.14 cfs with the proposed improvements to the parking lot. Runoff will infiltrate through the permeable pavers to a network of 4” perforated PVC pipes and drains east into a proposed dry well. Sub-basin B2, (0.372 acres), consists of an existing building, landscaped area, and concrete walkways. Rainfall travels via overland flow from west to east, where it will concentrate in a concrete drainage channel. Once the flow is concentrated into the channel, it is conveyed to the flowline Sherwood Street. The flow from the site eventually drains into the Poudre River. There is no change in sub-basin B2 from the existing condition. V. CONCLUSIONS A. Compliance with Standards The drainage design for the Faith Family site is in compliance with the requirements of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual as well as the City’s floodplain regulations. The criteria and recommendations of the Urban Storm Drainage Criteria Manual are also reflected in the design of the drainage systems. B. Drainage Concept The drainage design for the Faith Family will be adequate to safely convey onsite flows through the development. Development of the site, as proposed, should have a beneficial impact on water quality in downstream drainage facilities and drainage ways by reducing and delaying the initial discharge of runoff from the site such that sediments and other potential pollutants typically carried by this first flush are removed from the flow. VI. REFERENCES “City of Fort Collins Stormwater Criteria Manual”, City of Fort Collins, Adopted December 2011 “City of Fort Collins Municipal Code”, Chapter 10 – Flood Protection and Prevention City of Fort Collins, 1987 Urban Storm Drainage Criteria Manual, Volumes 1, 2, and 3, Urban Drainage and Flood Control District, April 2008 APPENDIX A: Hydrologic Computations Vicinity Map Fort Collins Flood Map USGS Soil Map Fort Collins Rainfall Intensity Curve Fort Collins Rainfall Intensity Table Table RO-3 Recommended Percentage Imperviousness Values Rational Method Calculated Runoff Coefficients Rational Method Calculated Imperviousness Rational Method Calculated Flows Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/13/2016 Page 1 of 3 4492470 4492480 4492490 4492500 4492510 4492520 4492530 4492540 4492550 4492560 4492570 4492470 4492480 4492490 4492500 4492510 4492520 4492530 4492540 4492550 4492560 4492570 492750 492760 492770 492780 492790 492800 492810 492820 492830 492840 492850 492860 492870 492880 492890 492900 492750 492760 492770 492780 492790 492800 492810 492820 492830 492840 492850 492860 492870 492880 492890 492900 40° 35' 2'' N 105° 5' 8'' W 40° 35' 2'' N 105° 5' 1'' W 40° 34' 58'' N 105° 5' 8'' W 40° 34' 58'' N 105° 5' 1'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 35 70 140 210 Feet 0 10 20 40 60 Meters Map Scale: 1:720 if printed on A landscape (11" x 8.5") sheet. Warning: Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: 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 35 Fort Collins loam, 0 to 3 percent slopes 0.5 100.0% Totals for Area of Interest 0.5 100.0% Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/13/2016 Page 3 of 3 DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF Table RO-3—Recommended Percentage Imperviousness Values Land Use or Surface Characteristics Percentage Imperviousness Business: Commercial areas 95 Neighborhood areas 85 Residential: Single-family * Multi-unit (detached) 60 Multi-unit (attached) 75 Half-acre lot or larger * Apartments 80 Industrial: Light areas 80 Heavy areas 90 Parks, cemeteries 5 Playgrounds 10 Schools 50 Railroad yard areas 15 Undeveloped Areas: Historic flow analysis 2 Greenbelts, agricultural 2 Off-site flow analysis (when land use not defined) 45 Streets: Paved 100 Gravel (packed) 40 Drive and walks 90 Roofs 90 Lawns, sandy soil 0 Lawns, clayey soil 0 * See Figures RO-3 through RO-5 for percentage imperviousness. C K 1 . 31 i 3 1 . 44 i 2 1 . 135 i 0 . 12 A A for CA 0, otherwise CA = 0 (RO-6) C K 0 . 858 i 3 0 . 786 i 2 0 . 774 i 0 . 04 CD CD (RO-7) C 2 B A CD C C 2007-01 RO-9 Urban Drainage and Flood Control District Composite C Values FAITH FAMILY Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Roofs (acres) Lawns (acres) Total Area Minor (2-YR) Major (100-YR) (C = 0.95) (C = 0.95) (C = 0.50) (C = 0.95) (C = 0.15) (acres) Composite "C" Composite "C" (Cf x C) P1 E1 0.000 0.000 0.055 0.009 0.000 0.064 0.56 0.70 P2 E2 0.000 0.051 0.000 0.143 0.178 0.372 0.57 0.71 D1 B1 0.000 0.005 0.000 0.000 0.059 0.064 0.21 0.27 D2 B2 0.000 0.051 0.000 0.143 0.178 0.372 0.57 0.71 Notes: Composite C values obtained from Table R0-11 Major Storm Runoff factored per Table R0-12 Developed Design Point Basin(s) Existing MAP Faith Family Rational Method.xlsx 11/2/2016 Impeviousness FAITH FAMILY Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Roofs (acres) Lawns (acres) Total Area Percent (I = 100) (I = 100) (I = 40) (I = 90) (I = 0) (acres) Imperviousness P1 E1 0.000 0.000 0.055 0.009 0.000 0.0640 47% P2 E2 0.000 0.051 0.000 0.143 0.178 0.3720 48% D1 B1 0.000 0.005 0.000 0.000 0.059 0.064 8% D1 B2 0.000 0.051 0.000 0.143 0.178 0.372 48% Notes: Percent Impervious Values per Table R0-3, Urban Drainage Manual Developed Design Point Basin (s) Existing CAG Faith Family Rational Method.xlsx 11/2/2016 Basin Flow Calculations FAITH FAMILY Area Minor Major (acres) Composite "C" Composite "C" Length (ft) Slope (%) Minor tov (min) a Major tov (min) a Length (ft) Slope (%) Channel Type Velocity (fps) c t t (min) Minor TC (min) Major TC (min) 2-yr 10-yr 100-yr 2-yr 10-yr 100-yr P1 E1 0.0640 0.56 0.70 17 0.84 4.39 3.24 0 0.75 PA 1.73 0.00 5.00 5.00 2.85 4.87 9.95 0.10 0.18 0.45 P2 E2 0.3720 0.57 0.71 110 1.20 9.83 7.22 86 0.75 PA 1.73 0.83 10.66 8.04 2.17 3.71 8.38 0.46 0.78 2.21 D1 B1 0.0640 0.21 0.27 40 2.00 8.33 7.83 0 0.75 PA 1.73 0.0000 8.33 7.83 2.35 4.02 8.38 0.03 0.05 0.14 D2 B2 0.3720 0.57 0.71 110 1.20 9.83 7.22 86 0.75 PA 1.73 0.8275 10.66 8.04 2.17 3.71 8.38 0.46 0.78 2.21 Notes: a b HM = Heavy Meadow, TF = Tillage/field, PL = Short pasture and lawns, BG = Nearly bare ground, GW = Grassed Waterway, PA = Paved Areas c Velocity alues from Figure 3-3/Table RO-2 Estimate of Average Flow Velocity for use with the Rational Method Design Point Developed Existing Initial/Overland Time Final TC Intensity (in/hr) Basin Flows (cfs) Basin (s) Travel Time 1 / 3 1 . 87 ( 1 . 1 ) 1 / 2 S CC D t f ov   CAG Faith Family Rational Method.xlsx 11/2/2016 APPENDIX B: Map Pocket Drainage Plan FS FS FS FS FS WOOD DECK WOOD PORCH 0.5' WIDE BRICK WALL 10" DIAMETER COLUMN (TYP) 0.5' WIDE CONCRETE WALL DRAIN CHASE DRAIN CHASE DRAIN CHASE DRAIN CHASE CONCRETE RAMP -CONCRETE- -CONCRETE- -CONCRETE- -CONCRETE- -CONCRETE- CONCRETE PAN -GRASS- -GRASS- -GRASS- -GRAVEL- -GRAVEL- -GRASS- -GRASS- -GRAVEL- SMH #1 RIM=5002.2 8" RCP (S) INV=4996.6 8" RCP (N) INV=4996.5 SS SS SS SS SS SS SS SS SS SS SS SS LID=5002.5 CONCRETE COURTYARD CONCRETE STAIRS 2 STORY RESIDENTIAL FRAME NO BASEMENT 2 STORY RESIDENTIAL FRAME & BRICK WITH BASEMENT SOUTH SHERWOOD STREET PARCEL 1 9,500 SQ.FT. 0.218 ACRES PARCEL 2 9,500 SQ.FT. 0.218 ACRES WOOD SHED LID=5000.8 BLOCK 73 ALLEY GATE (UP) (UP) (UP) (UP) EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG EG W W W W W W W W W W W W W VERTICAL CURB & GUTTER (TYP) WS WS WS WS WS WS WS WS WS WS WS WS WS WS FS FS FS FS FS FS FS 2-3/4" COPPER SERVICE 2" COPPER FIRE SERVICE 3 4" COPPER SERVICE 6" SANITARY SEWER 8" SANITARY SEWER EG SIGN "2 HOUR PARKING" 4" CAST IRON WATER LINE 325 SHERWOOD STREET 512 WEST MAGNOLIA STREET EXISTING 5' SW ALLEY HIGH POINT PROPOSED ROLL-OVER CURB PROPOSED OUTFLOW CURB C4.0 10' SCALE: 1" = 10' 0 20' FAITH FAMILY 317-321 SHERWOOD STREET FORT COLLINS, CO 80521 FOR BURIED UTILITY INFORMATION THREE (3) BUSINESS DAYS BEFORE YOU DIG CALL 811 (OR 1-800-922-1987) UTILITY NOTIFICATION CENTER OF COLORADO (UNCC) WWW.UNCC.ORG R D2 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. Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/13/2016 Page 2 of 3