FINAL DRAINAGE REPORT FOR: LOT 1 BLOCK 1 ROLLINS SUBDIVISION FILING #5. Prepared for:

Transcription

1 215063FD J FINAL DRAINAGE REPORT FOR: LOT 1 BLOCK 1 ROLLINS SUBDIVISION FILING #5 Prepared for: Mr. Hari Sach RV America 3640 N. Chambers Road Aurora, Co Phone: hsach@rvamerica.co Prepared by: 1950 W. Littleton Blvd., Suite 109 Littleton, CO Phone: Contact: Scott A Pease, P.E. APPROVED FOR ONE YEAR FROM THIS DATE MAY 18, /7/2015 City Engineer Date 5/11/15 Aurora Water Department Date February 13,

2 ENGINEER S CERTIFICATION This report for the drainage design of Rollins Subdivision Filing No. 5 was prepared by me (or under my supervision) in accordance with the provisions of City of Aurora Drainage Design Criteria, and was designed to comply with the provisions thereof. I understand that the City of Aurora does not, and will not, assume liability for drainage facilities designed by others. Scott A Pease P.E. Colorado Registered Professional Engineer No

3 TABLE OF CONTENTS INTRODUCTION... 4 Location Proposed Development HISTORIC DRAINAGE... 5 Overall Basin Description Drainage Patterns through Property Outfalls Downstream from Property DESIGN CRITERIA References Hydrologic Criteria Hydraulic Criteria DRAINAGE PLAN General Concept Specific Details CONCLUSIONS... 8 Compliance with Standards Summary of Concepts REFERENCES... 8 APPENDIX A HYDROLOGIC COMPUTATIONS 9-15 Composite C and I Values Standard Form SF-1 2, 5, 10, 100-Year Standard Form SF-2 APPENDIX B HYDRAULIC COMPUTATIONS Required 100-YR Volume (Full Spectrum) Extended Detention Basin (EDB) WQCV Outlet Restrictor Plate StormCAD Analysis Spillway Design/Rip-Rap Calculations APPENDIX C GRAPHS AND TABLES Soils Map FIRM Urban Drainage Tables RO-3, RO-5 COA C&I Standard Table 1 APPENDIX D REFERENCED REPORTS Peterson Subdivision Vicinity Master Drainage Report 3

4 A. INTRODUCTION 1. Location a. The proposed development is located in the Northwest ¼ of section 29, Township 3 South, Range 66 West of the 6 th Principal Meridian, in the City of Aurora, County of Adams, and State of Colorado. More specifically, the site is bounded on the north by RV America, on the West by N. Chambers Rd., on the East by Helena St., and lies approximately 300 feet north of E. 35 th Ave. b. Vicinity Map: c. The site is bounded to the north by Rollins Subdivision Filing No. 4, within a portion of Lot 1, Block 1 and is currently the existing RV America sales facility. To the south the site is bounded by Chambers Road Exchange Subdivision Filing No. 1 and is an undeveloped parcel of land covered in native grasses, weeds, and light vegetation. To the east is asphalt paved Helena St. and to the west by Chambers Rd. 2. Proposed Development a. The site is currently vacated and is covered by native grasses, weeds and light vegetation. The on-site surface soil is entirely made of Ascalon sandy loam and is considered as Hydrologic Soil Type B. The soil consists of mostly silty, clayey sands, from fine to medium grained, with low swell potential and good drainage characteristics. The existing ground surface drains both to the West and Northeast at approximately a 1% slope. The project proposal is to develop 256 recreation vehicle parking storage spaces. 4

5 The parking area will be made of gravel and a small fire access road made of asphalt. The total imperviousness of the site is 41.9%. b. The purpose of this report is to present the Final Drainage Report for the Rollins Subdivision Filing No. 5 in relation to the addition of the southerly 5.31 acres of land to Lot 1, Block 1 and to be comprised of a gravel parking lot, a fire access road, and landscaped buffers. B. HISTORIC DRAINAGE 1. Overall Basin Description a. Previously approved studies for this property include the Peterson Subdivision Vicinity Master Drainage Report, City of Aurora Engineering Control Section., March 1982 and the Peterson Subdivision Master Drainage Report, City of Aurora Engineering Design Section, July, 1986 (The Peterson Master Report C.O.A. #860268). The development in consideration is within basin B-6 and B-9 of the Peterson Master Drainage Report, which restricts the discharge from the site to 0.5 cfs/acre. b. The 5.31 acre development (South portion of Lot 1) is located in the Sand Creek Drainage Basin and according to FIRM panel 0043K, located in Appendix C, the site does not lie within a FEMA floodplain. 2. Drainage Patterns Through Property a. The site currently slopes to the West and Northeast at approximately 1%. Currently, overland flow to the west is intercepted by an existing 24 FES storm pipe located on the southwest corner of the site. The 24 FES conveys storm water North through an existing 27 storm pipe under the sidewalk of N. Chambers Rd. Overland flow to the northwest bypassing the 24 FES overtops the curb along N. Chambers Rd. and travels north in the east gutter of N. Chambers Rd to an inlet in the said gutter. Overland flow to the northeast is captured by a drainage swale on the east side of the existing RV America property and travels north to an existing inlet. 3. Outfalls Downstream from Property a. Off-site drainage comes from the undeveloped property to the south and drains to the existing 27 RCP on the southwest corner of the proposed development and travels north along N. Chamber Rd. along with all overland drainage from the proposed development. All overland flow on-site and offsite drains to a 29 x 45 HERCP where flow exits the limits of the Peterson drainage analysis. The site is ultimately tributary to Barnamor Ditch and Sand Creek. C. DESIGN CRITERIA 1. References a. October 2012 City of Aurora Storm Drainage Design and Technical Criteria Manual. b. Urban Drainage and Flood Control District Storm Drainage Criteria Manual (UDFCD). c. Peterson Subdivision Vicinity Master Drainage Report, City of Aurora Engineering Control Section., March 1982 and the Peterson Subdivision Master Drainage Report, City of Aurora Engineering Design Section, July, 1986 (The Peterson Master Report C.O.A. #860268). 5

6 2. Hydrologic Criteria a. The 1-Hour Design Point Rainfall Values from Figures RA-1 and RA-6 of the Urban Drainage Flood Control District Manuel, Volume 1 used for this report are: P1, 2 Yr = 0.96 in/hr P1, 5 Yr = 1.36 in/hr P1, 10 Yr = 1.65 in/hr P1, 100 Yr = 2.61 in/hr b. The rational method was used to calculate peak flows and runoff volumes throughout the development site. c. The Full Spectrum method was used to calculate the required storage volume. The spread sheet UD-Detention_v2.34 supplied by UDFCD was used for the computation and can be found in Appendix A. To determine the total required volume ½ the EURV is added to the 100-year detention volume and the WQCV, this method establish the required major storage volume (100-year storage) to be.520 acre-ft (22,651 cubic feet). The Full Spectrum method was utilizes because the site is greater than 5 acres. As stated above the Peterson Subdivision Master Drainage Report allows a discharge of 0.5 cfs/acre, a correction factor of 0.78 was applied to the allowable discharge to account for the site being within 2 sub basins of the Peterson study. The calculated 100-yr allowable release rate of 0.39 cfs/acre will conservatively satisfy allowable 100-yr discharge to the proposed single point of outfall, being the NW corner of the proposed 5.31 acre expansion of Lot 1. It can also be noted that the City of Aurora allows a maximum release rate of 0.85 cfs/acre for a site consisting of Type B soil during the 100-yr event. 3. Hydraulic Criteria a. On-site drainage improvement are designed for both the 2-year and 100-year storm events and in conjunction with manning s equation all drainage improvements are adequately designed. To control the flow that passes the orifice plate, a restrictor plate bolted to the 18 outlet pipe will be utilized. The restrictor plate calculation can be found in Appendix B. D. DRAINAGE PLAN 1. General Concepts a. Offsite drainage coming from the south is controlled by a 24 FES on the Southwest corner of the site. Flow captured by the 24 FES is conveyed to the existing 27 storm infrastructure analyzed with StormCAD, see Appendix B for StormCAD calculations. Drainage to the east of the site is conveyed through 1 foot drainage swale bordering the east side of the site along Helena St. The swale drains to an existing inlet approximately 145 north of the existing RV America property line. That inlet conveys storm water under the RV America parking lot with a 27 storm pipe to the existing storm infrastructure analyzed using StormCAD, see Appendix B. Ultimately all overland flow on-site and off-site drains to a 29 x 45 HERCP where flow exits the limits of the Peterson drainage analysis. b. The entire property, excluding a small portion to the South and East, drains to design point 1, Northwest corner of the property, where two 6

7 interconnected detention ponds are located. The two ponds have a combined detention volume of.560 acre-ft (24,394 cubic ft). At the outlet of the furthest West pond a forebay and micro pool will control excess urban runoff and sediment from leaving the property. RV America is responsible for all maintenance of the drainage facility. 2. Specific Details a. Sub-Basin A, which comprises 5.01 acres, the majority of the site, drains entirely into the detention facility at design point 1. This basin consists of the gravel parking lot, the asphalt fire lane, and the landscaping buffer having a composite imperviousness of 44.3 percent, with a 2-yr flow of 2.3 cfs and a 100-yr flow of 21.1 cfs. Sub-Basin B, comprised entirely of the landscape buffer to the south of the site covering 0.17 acres of the site having a composite imperviousness of 2 percent, being all landscaped area. This basin has a 2-yr flow of 0.08 cfs and a 100-yr flow of 0.29 cfs. All the flow leaving Sub-Basin B is captured by the 24 FES described above. Sub-Basin C, comprised entirely of a 25 foot landscape buffer to the east covers 0.14 and has a composite imperviousness of also 2 percent. This basin has a 2-yr flow of just over 0.07 cfs and a 100-yr flow of 0.24 cfs. All flow leaving Sub-Basin C enters the 1 foot drainage swale described above. b. The two interconnected detention ponds located on the North & west section of the property will capture the required volume of.520 acre-ft (22,651 cubic feet) as calculated by the Full Spectrum method. The pond to the Northeast will have a maximum depth of 2 feet and storage volume of.464 acre-ft (20,2115 cubic feet) it will drain through a 15 RCP culvert under the fire lane access road to the second pond located on the furthest Northwest corner of the site. The second pond on the Northwest corner has a maximum depth of 2 feet and a storage volume of.067 acre-ft (2,919 cubic feet). The pond also is comprised of 2 concrete trickle channels, a forebay, the UDFCD orifice plate to control sediment leaving the property, and a restrictor plate controlling the 100-yr flow. The circular forebay has a radius of 16, a wall height of 8 and a sediment storage volume of 128 cubic feet, 3 percent of the water quality control volume. The 2 trickle channels connected by the circular forebay have a width of 2 feet and a wall height of 2. The UDFCD outlet structure captures any sediment escaping the forebay and conveys all onsite runoff through a 3 x 1.25 restrictor plate from the site to existing storm infrastructure under the sidewalk of N. Chambers Rd. c. For events that exceed the 100-yr event, the east pond will overtop the fire access road and flow into the northwest pond. The northwest pond will over top the curb-and-gutter along N. Chambers Rd. 7

8 E. CONCLUSION 1. Compliance with Standards a. All proposed drainage facilities are designed in compliance with the City of Aurora Storm Drainage Criteria and the Urban Drainage and Flood Control District s Urban Storm Drainage Criteria Manual. No adverse impacts are expected to downstream drainage facilities 2. Summary of Concepts a. The drainage design included herein will control damage to existing and proposed structures. The proposed improvements do not negatively affect any upstream or downstream drainage facilities or other structures. The detention/water quality management ponds detain more than sufficient volume for Rollins Subdivision Filing No. 5 improvements and may require modifications upon future development. F. REFERENCES Storm Drainage Design and Technical Criteria Manual, October Natural Resources Conservation Service, Web soil Survey March 16, 2012 April 13, Reviewed November 6, Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, June 2001, Revised December

9 APPENDIX A HYDROLOGIC COMPUTATIONS 9

10 COMPOSITE "C" AND "I" VALUES Subdivision: Rollins Subdivision Filing No. 5 Project Name: RV America Location: City of Aurora Project No Calculated By: JRS Checked By: Date: 11/6/2014 Total Area Area Gravel Area Grass Area Roofs Area Pavement B Soil Composite Composite Composite Composite Composite Basin (acres) (acres) (acres) (acres) (acres) (acres) C 2 C 5 C 10 C 100 I A B C Overall

11 STANDARD FORM SF-1 TIME OF CONCENTRATION Subdivision Rollins Subdivision Filing No. 5 Project Name: RV America Location City of Aurora Project No NOTES: Calculated By: JRS T i = (0.395*(1.1 - C 5 )*(L)^0.5)/(S^0.33) Checked By: T t =L/60V (Velocity From Fig. RO-1) T c Check = 10+L/180 SUB-BASIN INITIAL/OVERLAND TRAVEL TIME Tc CHECK DATA (T i ) (T t ) (URBANIZED BASINS) FINAL BASIN D.A. C 5 L S T i L S VEL. T t COMP. T c TOTAL MIN. T c T c ID (AC) (FT) (%) (MIN) (FT) (%) (FPS) (MIN) (MIN) LENGTH(FT) (MIN) (MIN) A B C Date: 11/6/

12 STANDARD FORM SF-2 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) Project Name: RV America Subdivision Rollins Subdivision Filing No. 5 Project No Location City of Aurora Calculated By: JRS Design Storm 2-Year Checked By: Date: 11/6/2014 DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME INLET TYPE Design Point Area Desig. Area (Ac) Runoff Coeff. Tc (min) C*A (Ac) I (in/hr) Q (cfs) Tc (min) C*A (Ac) I (in/hr) Q (cfs) Interception (cfs) Street flow (cfs) Design Flow (cfs) Slope (%) Pipe Size (inches) Length (ft) Velocity (fps) Tt (min) Remarks UDFCD Outlet Structure 1 A Pond Inflow=2.3 cfs South B East C

13 STANDARD FORM SF-2 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) Project Name: RV America Subdivision Rollins Subdivision Filing No. 5 Project No Location City of Aurora Calculated By: JRS Design Storm 5-Year Checked By: Date: 11/6/2014 DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME INLET TYPE Design Point Area Desig. Area (Ac) Runoff Coeff. Tc (min) C*A (Ac) I (in/hr) Q (cfs) Tc (min) C*A (Ac) I (in/hr) Q (cfs) Interception (cfs) Street flow (cfs) Design Flow (cfs) Slope (%) Pipe Size (inches) Length (ft) Velocity (fps) Tt (min) Remarks UDFCD Outlet Structure 1 A Pond Inflow=4.9 cfs South B East C

14 STANDARD FORM SF-2 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) Project Name: RV America Subdivision Rollins Subdivision Filing No. 5 Project No Location City of Aurora Calculated By: JRS Design Storm 10-Year Checked By: Date: 11/6/2014 DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME INLET TYPE Design Point Area Desig. Area (Ac) Runoff Coeff. Tc (min) C*A (Ac) I (in/hr) Q (cfs) Tc (min) C*A (Ac) I (in/hr) Q (cfs) Interception (cfs) Street Flow (cfs) Design Flow (cfs) Slope (%) Pipe Size (inches) Length (ft) Velocity (fps) Tt (min) Remarks UDFCD Outlet Structure 1 A Pond Inflow=7.8 cfs South B East C

15 STANDARD FORM SF-2 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) Project Name: RV America Subdivision Rollins Subdivision Filing No. 5 Project No Location City of Aurora Calculated By: JRS Design Storm 100-YEAR Checked By: Date: 11/6/2014 DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME INLET TYPE Design Point Area Desig. Area (Ac) Runoff Coeff. Tc (min) C*A (Ac) I (in/hr) Q (cfs) Tc (min) C*A (Ac) I (in/hr) Q (cfs) Interception (cfs) Street flow (cfs) Design Flow (cfs) Slope (%) Pipe Size (inches) Length (ft) Velocity (fps) Tt (min) Remarks UDFCD Outlet Structure 1 A Pond Inflow=21.1 cfs South B East C

16 APPENDIX B HRDRAULIC COMPUTATIONS 16

17 ACTUAL 100-YR VOLUME (Full Spectrum) Subdivision Rollins Subdivision Filing No. 5 Project Name: RV America Location Combined Ponds Project No By: JRS Volume=1/3 x Depth x (A+B+(A*B)^0.5) Checked By: A - Upper Surface Date: 2/13/2015 B - Lower Surface ACTUAL 100-YR VOLUME Elevation Surface Area A+B+(A*B)^0.5 1/3 Depth Volume Cum. Volume Cum.Volume (square feet) (feet) (cubic feet) (cubic feet) (acre-feet) ELEV'S Below Derived from combined North Pond and West pond volumes 100-YR+WQCV+1/2 EURV= 0.52 AC-FT (22,651 CU. FT.)= ELEV FT EURV=0.24 AC-FT (10,454 CU. FT.)= ELEV FT 17

18 ACTUAL 100-YR VOLUME (Full Spectrum) Subdivision Project Name: Location West Pond Project No. By: Volume=1/3 x Depth x (A+B+(A*B)^0.5) Checked By: A - Upper Surface Date: 2/13/2015 B - Lower Surface ACTUAL 100-YR VOLUME Elevation Surface Area A+B+(A*B)^0.5 1/3 Depth Volume Cum. Volume Cum.Volume (square feet) (feet) (cubic feet) (cubic feet) (acre-feet)

19 ACTUAL 100-YR VOLUME (Full Spectrum) Subdivision Project Name: Location North Pond Project No. By: Volume=1/3 x Depth x (A+B+(A*B)^0.5) Checked By: A - Upper Surface Date: 2/13/2015 B - Lower Surface ACTUAL 100-YR VOLUME Elevation Surface Area A+B+(A*B)^0.5 1/3 Depth Volume Cum. Volume Cum.Volume (square feet) (feet) (cubic feet) (cubic feet) (acre-feet)

20 Actual 100 YR Volume Cum. Volume (acre feet) Elevation (feet) 20

21 DETENTION VOLUME BY THE FULL SPECTRUM METHOD Project: Basin ID: Area of Watershed (acres) Subwatershed Imperviousness Level of Minimizing Directly Connected Impervious Area (MDCIA) Effective Imperviousness 1 Hydrologic Soil Type Type A Type B Type C or D % % Percentage of Area Area (acres) % * User input data shown in blue. Excess Urban Runoff Volume 4 Recommended Horton's Equation Parameters for CUHP Infiltration (inches per hour) Decay Initial--f i Final--fo Coefficient (watershed inches) Detention Volumes 2,5 (acre-feet) Maximum Allowable Release Rate, cfs 3 Design Oulet to Empty EURV in 72 Hours year Detention Volume Including WQCV yr Vol Type A Soil Runoff Voume - Inches yr Vol Type B, C & D Soils EURV Type A Soil EURV Type B Soil EURV Type C/D Soil 100-yr Storage Volume 0.50 EURV Storage Volume Percent Total Imperviousness Notes: 1) Effective imperviousness is based on Figure ND-1 of the Urban Storm Drainage Criteria Manual (USDCM). 2) Results shown reflect runoff reduction from Level 1 or 2 MDCIA and are plotted at the watershed's total imperviousness value; the impact of MDCIA is reflected by the results being below the curves. 3) Maximum allowable release rates for 100-year event are based on Table SO-1. Outlet for the Excess Urban Runoff Volume (EURV) to be designed to empty out the EURV in 72 hours. Outlet design is similar to one for the WQCV outlet of an extended detention basin (i.e., perforated plate with a micro-pool) and extends to top of EURV water surface elevation. 4) EURV approximates the difference between developed and pre-developed runoff volume. 5) 100-yr detention volume includes EURV. No need to add more volume for WQCV or EURV UD-Detention_v /6/2014, 10:49 AM

22 Design Procedure Form: Extended Detention Basin (EDB) Designer: Company: Date: Project: Location: November 6, 2014 Sheet 1 of 4 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, I a I a = 41.9 % B) Tributary Area's Imperviousness Ratio (i = I a / 100 ) i = C) Contributing Watershed Area Area = ac D) For Watersheds Outside of the Denver Region, Depth of Average d 6 = in Runoff Producing Storm Choose One E) Design Concept (Select EURV when also designing for flood control) Water Quality Capture Volume (WQCV) Excess Urban Runoff Volume (EURV) F) Design Volume (1.2 WQCV) Based on 40-hour Drain Time V DESIGN = ac-ft (V DESIGN = (1.0 * (0.91 * i * i * i) / 12 * Area * 1.2) G) For Watersheds Outside of the Denver Region, V DESIGN OTHER = ac-ft Water Quality Capture Volume (WQCV) Design Volume (V WQCV OTHER = (d 6 *(V DESIGN /0.43)) H) User Input of Water Quality Capture Volume (WQCV) Design Volume V DESIGN USER = ac-ft (Only if a different WQCV Design Volume is desired) Choose One I) Predominant Watershed NRCS Soil Group A J) Excess Urban Runoff Volume (EURV) Design Volume For HSG A: EURVA = (0.1878i )*Area EURV = ac-f t For HSG B: EURV B = (0.1178i )*Area For HSG C/D: EURV C/D = (0.1043i )*Area B C / D 2. Basin Shape: Length to Width Ratio L : W = : 1 (A basin length to width ratio of at least 2:1 will improve TSS reduction.) 3. Basin Side Slopes A) Basin Maximum Side Slopes Z = ft / ft (Horizontal distance per unit vertical, 4:1 or flatter preferred) 4. Inlet A) Describe means of providing energy dissipation at concentrated inflow locations: UD-BMP_v3.03, EDB 22 11/6/2014, 2:48 PM

23 STAGE-DISCHARGE SIZING OF THE WATER QUALITY CAPTURE VOLUME (WQCV) OUTLET Project: Basin ID: WQCV Design Volume (Input): Catchment Imperviousness, Ia = 41.9 percent Catchment Area, A = 5.31 acres Diameter of holes, D = inches Depth at WQCV outlet above lowest perforation, H = 2 feet Number of holes per row, N = 1 Vertical distance between rows, h = 4.00 inches OR Number of rows, NL = 5.00 Orifice discharge coefficient, Co = 0.65 Height of slot, H = inches Slope of Basin Trickle Channel, S = ft / ft Width of slot, W = inches Time to Drain the Pond = 72 hours Watershed Design Information (Input): 1.82 Percent Soil Type A = % Percent Soil Type B = 100 % Percent Soil Type C/D = % Outlet Design Information (Output): Excess Urban Runoff Volume (From 'Full-Spectrum Sheet') watershed inches X N/A 0.00 Excess Urban Runoff Volume (From 'Full-Spectrum Sheet') acre-feet Outlet area per row, Ao = 0.39 square inches Total opening area at each row based on user-input above, Ao = 0.39 square inches Total opening area at each row based on user-input above, Ao = square feet 3 Central Elevations of Rows of Holes in feet Row 1 Row 2 Row 3 Row 4 Row 5 Row 6 Row 7 Row 8 Row 9 Row 10 Row 11 Row 12 Row 13 Row 14 Row 15 Row 16 Row 17 Row 18 Row 19 Row 20 Row 21 Row 22 Row 23 Row Flow Collection Capacity for Each Row of Holes in cfs Override Area Row 1 Override Area Row 2 Override Area Row 3 Override Area Row 4 Override Area Row 5 Override Area Row 6 Override Area Row 7 Override Area Row 8 Override Area Row 9 Override Area Row 10 Override Area Row 11 Override Area Row 12 Override Area Row 13 Override Area Row 14 Override Area Row 15 Override Area Row 16 Override Area Row 17 Override Area Row 18 Override Area Row 19 Override Area Row 20 Override Area Row 21 Override Area Row 22 Override Area Row 23 Override Area Row 24 UD-Detention_v2.34, WQCV 23 2/11/2015, 5:32 PM

24 RESTRICTOR PLATE SIZING FOR CIRCULAR VERTICAL ORIFICES Project: RV America Basin ID: X 1 #1 Vertical #2 Vertical Sizing the Restrictor Plate for Circular Vertical Orifices or Pipes (Input) Orifice Orifice Water Surface Elevation at Design Depth Elev: WS = 5, feet Pipe/Vertical Orifice Entrance Invert Elevation Elev: Invert = 5, feet Required Peak Flow through Orifice at Design Depth Q = 2.07 cfs Pipe/Vertical Orifice Diameter (inches) Dia = 18.0 inches Orifice Coefficient C o = 0.65 Full-flow Capacity (Calculated) Full-flow area Af = 1.77 sq ft Half Central Angle in Radians Theta = 3.14 rad Full-flow capacity Qf = 14.3 cfs Percent of Design Flow = 691% Calculation of Orifice Flow Condition Half Central Angle (0<Theta<3.1416) Theta = 0.90 rad Flow area A o = 0.23 sq ft Top width of Orifice (inches) T o = inches Height from Invert of Orifice to Bottom of Plate (feet) Y o = 0.28 feet Elevation of Bottom of Plate Elev Plate Bottom Edge = 5, feet Resultant Peak Flow Through Orifice at Design Depth Q o = 2.1 cfs Width of Equivalent Rectangular Vertical Orifice Equivalent Width = 0.82 feet UD-Detention_v2.34.xlsm, Restrictor Plate 24 11/18/2014, 8:42 AM

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26 P-6 P-1 Scenario: 100-YR O-1 P-10 I-3 P-9 J-3 P-8 J-5 P-7 I-2 J-2 J-1 P-4 Title: Chambers Road Storm Sewer x:\ rv america\drainage\stormcad\project.stm Engineering 26 Partners, Inc. Project Engineer: Scott Pease StormCAD v5.5 [5.5005] 02/11/15 04:16:19 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT USA Page 1 of 1 I-1

27 Scenario: 100-YR Junction Report Label Rim Elevation (ft) StructureInvert In Elevation Invert 1 Out Elevation Diameter (ft) (ft) (ft) Hydraulic Grade Line In (ft) Hydraulic Grade Line Out (ft) Total System Flow (cfs) J-1 5, , , , , J-2 5, , , , , J-3 5, , , , , J-5 5, , , , , Title: Chambers Road Storm Sewer x:\ rv america\drainage\stormcad\project.stm Engineering 27 Partners, Inc. Project Engineer: Scott Pease StormCAD v5.5 [5.5005] 02/11/15 04:17:07 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT USA Page 1 of 1

28 Scenario: 100-YR Pipe Report Label UpstreamDownstream Node Node Section Size Length (ft) ConstructedUpstreamDownstream Slope (ft/ft) Invert Elevation (ft) Invert Elevation (ft) Total System Flow (cfs) Full Capacity (cfs) Hydraulic Grade Line In (ft) Hydraulic Grade Line Out (ft) Average Velocity (ft/s) P-1 J-1 J-2 27 inch , , , , P-4 I-1 J-1 27 inch , , , , P-6 J-2 J-3 27 inch , , , , P-7 I-2 J-5 18 inch , , , , P-8 J-5 J-3 18 inch , , , , P-9 J-3 I-3 36 inch , , , , P-10 I-3 O-1 36 inch , , , , Title: Chambers Road Storm Sewer x:\ rv america\drainage\stormcad\project.stm Engineering 28 Partners, Inc. Project Engineer: Scott Pease StormCAD v5.5 [5.5005] 02/11/15 04:17:40 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT USA Page 1 of 1

29 Scenario: 100-YR Inlet Report Label Rim Elevation (ft) Invert Out Elevation (ft) Total System Flow (cfs) Hydraulic Grade Line In (ft) Hydraulic Grade Line Out (ft) I-1 5, , , , I-2 5, , , , I-3 5, , , , Title: Chambers Road Storm Sewer x:\ rv america\drainage\stormcad\project.stm Engineering 29 Partners, Inc. Project Engineer: Scott Pease StormCAD v5.5 [5.5005] 02/11/15 04:16:49 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT USA Page 1 of 1

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32 APPENDIX C GRAPHS AND TABLES 32

33 104 48' 37'' W Custom Soil Resource Report Map Hydrologic Soil Group ' 25'' W ' 3'' N 39 45' 57'' N ' 3'' N 39 45' 57'' N ' 37'' W N Map Scale: 1:1,310 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 ' 25'' W

34 Custom Soil Resource Report 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 1:20,000. 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: Adams County Area, Parts of Adams and Denver Counties, Colorado Survey Area Data: Version 11, Sep 23, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 16, 2012 Apr 13, 2012 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

35 Custom Soil Resource Report Table Hydrologic Soil Group Hydrologic Soil Group Summary by Map Unit Adams County Area, Parts of Adams and Denver Counties, Colorado (CO001) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI AsB Ascalon sandy loam, 0 to 3 percent slopes B % Totals for Area of Interest % Rating Options Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher 18 35

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37 DRAINAGE CRITERIA MANUAL (V. 1) RAINFALL Figure RA-1 Rainfall Depth-Duration-Frequency: 2-Year, 1-Hour Rainfall Rev. 01/2004 Urban Drainage and Flood Control District 37 RA-13

38 RAINFALL DRAINAGE CRITERIA MANUAL (V. 1) Figure RA-2 Rainfall Depth-Duration-Frequency: 5-Year, 1-Hour Rainfall RA-14 01/2004 Urban Drainage and Flood Control District 38

39 DRAINAGE CRITERIA MANUAL (V. 1) RAINFALL Figure RA-3 Rainfall Depth-Duration-Frequency: 10-Year, 1-Hour Rainfall Rev. 01/2004 Urban Drainage and Flood Control District 39 RA-15

40 RAINFALL DRAINAGE CRITERIA MANUAL (V. 1) Figure RA-6 Rainfall Depth-Duration-Frequency: 100-Year, 1-Hour Rainfall RA-18 01/2004 Urban Drainage and Flood Control District 40

41 TABLE 1 RUNOFF COEFFICIENTS AND PERCENTS IMPERVIOUS LAND USE OR SURFACE CHARACTERISTICS Business: Commercial Areas Neighborhood Areas Residential: Single-Family (**) Multi-Unit (detached) Multi-Unit (attached) 1/2 Acre Lot or Larger Apartments Industrial: Light Areas Heavy Areas PERCENT IMPERVIOUS (*) (*) 80 FREQUENCY Parks, Cemeteries Playgrounds Schools Railroad Yard Areas Undeveloped Areas: Historic Flow Analysis, Greenbelts, Agricultural 2 (See "Lawns") Off-Site Flow Analysis (when land use not defined)

42 TABLE 1 (continued) RUNOFF COEFFICIENTS AND PERCENTS IMPERVIOUS LAND USE OR SURFACE CHARACTERISTICS PERCENT IMPERVIOUS FREQUENCY Streets: Paved Gravel Concrete Drive and Walks Roofs Lawns, Sandy Soil (A and B Soils): 2 2% Slope 2-7% Slope >7% Slope Lawns, Clay Soil (C and D Soils): 2% Slope 2-7% Slope >7% Slope NOTE: These Rational Formula coefficients may not be valid for large basins (*)See Figures RO-3 through RO-5 of USDCM Volume 1 for percent impervious. (**)Up to 5 units per acre. Single-family with more than 5 units per acre, use values for multiunit/detached

43 APPENDIX D REFERENCED REPORTS 43

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