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Home My WebLink AboutDrainage Plan Sept. 2019DRAINAGE PLAN FOR CATTLE CREEK COMMERCIAL CENTER BUILDINGS "Q" THROUGH "V" September 2019 Prepared by: Zancanella & Associates, Inc. 1011 Grand Avenue Glenwood Springs, CO 81601 (970) 945-5700 ZANCANELLA & ASSOCIATES JOB NUMBER 97004.01 TABLE OF CONTENTS SECTION PAGE INTRODUCTION OFF -SITE BASINS HYDROLOGY DRAINAGE PLAN SUMMARY APPENDIX A: Calculations APPENDIX B: Soils and Supplemental Information DRAWINGS: Project Location Map 8 1/2" x 11" Drainage Basins Map 11" x 17" 1 1 1 2 3 1 INTRODUCTION The proposed buildings are located near the intersection of Cattle Creek Road and Highway 82 in Garfield County, Colorado, on an area known as the southwest bench portion of the existing development. See the Project Location Map at the end of this text. DRAINAGE BASINS The only major drainage basin near the site is the Cattle Creek Basin. However, the site is far above the floodplain level of Cattle Creek. Therefore, the only off -site basins that could affect this site lie within the steep hills adjacent to the east. These basins are shown on the Drainage Basin map at the end of this text. All of the off -site basins are quite small, the largest being only about 3/4 of an acre. Therefore, the related flows affecting the proposed buildings are also small. The flow and routing calculations are shown in the Appendix. Even though the off -site basins are small, during larger storm there would be a chance of some smaller mud/debris flows. Therefore, it is recommended that use be made of an existing bench that was previously cut for a utility path, but subsequently not used. This bench could be modified to detain and divert small flows from the basin areas above it. A cross section detail for this is shown on the (added) sheet 4 of the plans submitted. The development area itself mainly consists of a bare, dry bench that has previously been used for storage of construction and trucking related items. The row of trees on the west side were previously planted to provide screening. There are no defined drainage channels or ravines on the bench area. The existing drainage basins will remain unchanged except for minor grading on the bench and adjacent to the proposed buildings. 2 HYDROLOGY The hydrologic methods for the minor basins in this study are as outlined in the Soil Conservation Service publication "Procedures for Determining Peak Flows in Colorado". Peak flows in this area will be primarily rainfall derived since the whole site is well below 8000 feet in elevation. Therefore, the storm drainage system will be more than adequate to handle spring snowmelt runoff. The precipitation amounts for the 2 and 25 year, 24 hour storms used by the WinTR55 program (Garfield_2 MSE2), were compared with the data taken from the NOAA Atlas 14, Volume 8, Version 2, "GLENWOOD SPGS #2", on line version, and found to be essentially the same. The pertinent page is included in the Appendix. Runoff calculations for the Basins are included in the Appendix. The hydrologic soil characteristics were obtained from the NRCS Soil Survey for Portions of Eagle, Garfield and Pitkin Counties. The soil type was consistent and was rated a Hydrologic Group of "B". The vegetative ground cover is poor and was rated at only 10% ground cover of the type "Sage/Grass". This results in a general Curve Number of 68 but 70 was used for convenience. The estimated runoff from the 2 and 25 year design storms prescribed by county code 7-204 C3.a were calculated and the results are shown in the Appendix. These flows are relatively minor and will be short lived. DRAINAGE PLAN The flows generated from the adjacent drainage basins will enter the site on the easterly side of the bench area. Flows will be directed around the buildings by virtue of a high point at the center back of each building. [The maximum elevation of the high point was based on the building structural plans Typical Building Section on Sheet S3.1. This section shows a maximum fill elevation of 8'-4" above the top of footing or 7'-8" above the finished floor elevation. For convenience and conservativism, the high point elevations were limited to 7 feet above the finished floor elevation.] The flows will then directed to and collected in the central drainage swale in the access/parking area. This swale is 3 directed in two directions from a high point near the northwest corner of Building Q. The majority will flow northerly to a small settling basin at the north end of the bench, the remainder will flow southerly to the ditch alongside the access road and thence northerly along the frontage road to eventually reach Cattle Creek. The general flow patterns are shown on the Site & Drainage Plan which is sheet 1 of the submitted plans. As previously noted, the calculations for flows are included in the Appendix. Note that the proposed buildings are spaced sufficiently to allow storm runoff flows to be diverted around building sites. It should also be noted that each building is proposed to have its own roof drainage system that will be added to storm drainage flows at various points. However, the roof areas were included in the overall calculations and would likely peak prior to the general site runoff so would not add to the site runoff peak. SUMMARY The Drainage Plan for the Cattle Creek Commercial Center Buildings "Q" through "V" project includes the necessary improvements to mitigate its impact on the drainage patterns of the area. LOCATION MAP N.T.S. Jae. ea, cq. co co '.""MMI��',r a r � I j\.\\I T ► ion me rig a r ■00 ■ ■/ d • -. —imolai"'my ing imi u. If * ,pis gimi eYyso • [!? 44 ■ ■ 1P ,-d ■ a� 4 f . 0 $ 1 cs cD a $ . CO v- $ o5 C 1 rn s 1 0121 Ong 1 1 1 1► 111\ 1, .0 1 1 1 1 1 1 1 0.3 DRAINAGE BASINS SCALE: 1 " = 60' APPENDIX A: CALCULATIONS HYDROLOGY SUMMARY TABLE I BASIN AREA S.F. AREA ACRES Q(2) * Q(25) cfs Q(25) Routed cfs V 28871 0.66 n/a 0.35 U 20137 0.46 n/a 0.24 T 13332 0.31 n/a 0.16 S 19775 0.45 n/a 0.23 R 32024 0.74 n/a 0.39 V-R + Parking 3.45 Detention Proposed = 1600 cubic feet Q 4588 0.11 n/a 0.06 P 40140 0.92 n/a 0.48 a-P + Parking 1.07 No Detention Proposed * amount below initial abstraction Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_lrintpage.htrnl?st=co&sta=05... NOAA Atlas 14, Volume 8, Version 2 GLENWOOD SPGS #2 Station ID: 05-3359 Location name: Glenwood Springs, Colorado, USA* Latitude: 39.5181°, Longitude: -107.3172° Elevation: Elevation (station metadata): 5880 ft** • source: ESRI Maps "source. USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Michael Yekta, Geoffery Bonnin NOAA National Weather Service, Silver Spring, Maryland PF_tabular I PF _graphical 1 Maps & aerials PF tabular 1 PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 [Duration Average recurrence interval (years) 1 2 5 10 25 50 1 100 200 500 1000 5-min 0.116 (0.092-0.150) 0.170 0.135-0.220) 0.176 (0.139-0.228) 0.268 (0.212-0.348) 0.339 0.430 (0.266.0,443)1(0.320.0,573) i(0.360-0.671) 0.494 0.553 (0.388-0.773) I(0.408-0.878) 0.607 0.670 (0.432.1.00) 0.712 (0.451-1.09) 10-min 15-min 30-min 60-min 0.258 (0.204-0.333) 0.392 (0.310-0.509)(0,390-0.648) 0.497 0.630 0.723 f (9.4684U.838)1(0.527-0-9831 0.809 (0.569-1.13) 0.889 (0.597.1.28) 0.982 (0.633-1.47) 1.04 (0.660.1.60) (0.165-02 69)(0.249--0 407) (0.378-0 621) 8 (0.4776-0.791)1(0.5716 ,02) (0.438220) 7 (0: 948.3a) 1.08 (0.728-1.56) 1.20 (0.772-1.79) 1.42 (0.916-2.12) 1.27 (0,805-1.95) 1.50 (0.950-2.31) 0.285 (0.228.0,369) 0.381 (0,303-0.493) J 0.411 (0.326.0,532) 0.604 (0.477-0.784) 0.753 (0.591.0.982). 0.940 (0.698-1.25) 1.05 (0.784-1,40) 1.07 (0.780-1,45) 1.19 (0.867-1.61) 1.31 (0.966-1,75) 1.34 (0.998-1,78) 1.19 (0.836-1.66) 1.30 (0.872-1,87} 0.510 (0A04.0.660) 0.707 (0.559.0.918) 0.860 (0.675-1.12) 1.31 (0.923-1.83) 1.43 [03,959-2,06) 1.56 (1.00-2.32) 1.64 (1.04-2,52) 2-hr 0.478 (0.384-0.608) 0.608 (0.488-0.776) 0.810 0.967 (0.648-1.04) (0,769-1.24) 1.17 f (0,881-1.53) 1.44 (1.02-1.98) 1.55 (1.06-2.21) 1.69 (1.11-2.49) 1.73 (1.14-2.53) 1.79 (1.14-2.70) 1.84 F((1.18-2.75) 3-hr 0.560 (0.454-0.707) 0.679 (0.549-0.858) 0.865 1.01 (0.697-1.10) (0.809-1.29) 1.20 (0.917-1.57) r 1.46 (1.05-2.00) 1.59 (1.09.2.24) 1.78 (1.25-2,50) 2.31 J (1.63-3.19) 6-hr 0.732 (0.600-0.609�) 0.833 (0.682-1.04) 1.00 (0.816-1.25) 1.25 (1.03-1.54) 1.14 (0.923-1.43) 1.33 (1.04-1.73) 1.48 (1.13-1.95) 1.63 (1.19-2.22) 1.99 (1,33-2.88) 2.14 (1.39-3.16) 2.82 1(1,85.4.10) 0.908 - 12-hr 1 (0,754-1.11) 1.04 (0.860-1.27) 1.43 1 1.69 (1.18-1.77) I (1.34-2.16) 1.89 (1.46-2.46) 2.10 (1,56-2.81) 2.67 (2.00.3.52) 2.60 (1.76-3.71) 24-hr 2-day 1.10 {0.924-1.32) 1.26 (1.06-1.52) 1.54 (1.29-1.87) 1.78 (1.48-2.16) 2.11 (1.78.2.52) 2.12 (1.70-2.68) 2.51 (2.04-3.12) 2.39 (1.87-3.07) 2.83 (2,24-3.58) 2.95 (2.11-4.02) 3.35 (2.29-4.70) 3.65 1(2.42-5.21) 1.32 (1.12-1.56) 1.51 (1.28-1.79) 1.83 (1.55-2.17) 3.17 (2.41-4.12) 3.52 (2.55-4.73) 4.01 (2.78-5.55) 4.40 (3.07-6.03) 4.39 (2.95-6.18) 4.81 (3.25-6.69) 3-day 1.47 (1,26-1.72) 1.68 (1.45-1.98) 2.04 2.35 (1,75-2.40) (2.00-2.78) 2.79 (2.29-3.44) 3.14 (2,51-3.93) 3.51 (2.68-4.51) 3.89 (2.83-5.15) 4-day 1.60 - (1.38-1.86) 1.83 (1.58-2,13) 2.21 (1,90-2.59) 2.54 (2.17-2.98) 3.00 (2.47-3.66) 3.37 (2.70-4.18) 3.74 (2,88-4.77) 4.13 (103-5.44) 4.66 (3.28-6,33) 5.07 (3.44-7.01) 7-day 1.92 (1.68-2.21) 2.17 (1,8D-2.49) 2.58 r(2,24.2.97) 2.92 3.41 (2.52-3.38) (2,83.4.09) 3.79 (3.06-4.63) 4.18 (3.24-5.25) 4.58 (3.38-5.94) 5.12 (3.62.5,85) 5.54 (3.79-7.55) 10-day 2.21 (1.94-2.51) 2.46 (2.17-2.80) 2.89 (2.53-3.30) 3.25 (2.83-3.73) 3.75 (3.14-4.46) 4.15 (3.38-5.02) 4.55 (3.56-5.66) 4.97 (3.69-6.38) 5.53 (3.93-7.33) 5.96 (4.10-8,05) 20-day 3.01 (2.69-3.37) 3.33 (2.97-3.73) 3.85 (3.42-4.33) 4.29 (3.79-4.84) 4.89 (4.15-5.71) 5.36 (4.43-6.36) 5.83 (4.62-7.12) 6.31 (4.75-7.95) 6.95 (4.99-9.04) 8.27 (5.98-10.6) f 7.44 1 (5.18-9.87) 30-day 3.68 (3.32-4.08) 4.08 (3.67-4.62) 4.72 (4.23-5.25) 5.25 (4.67-5.87) 5.97 (5.09-6,87) 6.51 (5:A0•7.63) 7.04 (5.61-8,49) 7.58 (5.74-9.43) 8.79 (6_16-11.5) 45-day 65.30 60-day� 4.55 (4.13-4.98) 5.07 (4.60-5.56) 5.89 (5.32-6.48) 6.54 (5.87-7.23) 7.41 (6.36-8.42) 8.05 (6,73-9.31) 8.67 (6.95-10.3) 9.27 (7.06-11.4) 10.0 (7.28-12,7) 10.6 1 (7.45-13.7) (4.84.5.78) 5.93 (5.41.8.45) 6.92 (6.29-7.55) 7.70 (6.94-8.44) 8.70 (7.50-9.79) 9.43 (7.92-10.8) 10.1 (8.14-11.9) 10.8 (8.23-13.1) 11.6 (8.42-14.5) 12.1 (8.57-15.6) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). 'Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. (Please refer to NOAA Atlas 14 document for more information. 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R 1f 11 C ara.a ■a11111C;111:1r..■rRRr1.■alra lalaar ll " :1a lrlail■ li ra�Yl rll. ■■ r w.. . mum: ra1 aRll.r.ai. ia.1R n a Cr1.r krIiiil.■Claninnnnnnnaaa i laikhaninr hiiiilaExlllliii- :::lei': TT; Wm:1:ap°:E..a:rRaieC.7air::7iI: alliamet :aa.11;"--- .RR :iv" 1.4 0 20 40 60 Figure S— 3 Ground Cover Density - percent HYDROLOGIC SOIL COVER COMPLEX a ASSOCIATED CURVE NUMBERS D C Herbaceous D C Oakaspen B Juniper- grass C Sage — grass 80 23 WinTR-55 Current Data Description --- Identification Data --- User: tpb Date: 9/16/2019 Project: CCC - SW Bench Units: English SubTitle: Areal Units: Acres State: Colorado County: Garfield_2 MSE3 Filename: Z:\97000's\97404 Rudd, Wayne\97404.01 Cattle Creek\2019\SW Bldg Plans\drainage\ex basins V-R-w pkg.w55 Name - -- Sub -Area Data --- Description Reach Area(ac) RCN Tc ✓ Outlet 0.67 70 0.100 U V 0.46 70 0.100 T U 0.31 70 0.100 S T 0.45 70 0.100 R S 0.75 70 0.100 parking Outlet 0.98 88 0.100 Total area: 3.62 (ac) - -- Storm Data -- Rainfall Depth by Rainfall Return Period 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1-Yr (in) (in) (in) (in) (in) (in) (in) 1.29 1.56 1.8 2.15 2.43 2.73 1.13 Storm Data Source: Garfield_2 MSE2 County, CO (NRCS) Rainfall Distribution Type: Type MSE2 Dimensionless Unit Hydrograph: <standard> WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Storm Data Rainfall Depth by Rainfall Return Period 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1-Yr (in) (in) (in) (in) (in) (in) (in) 1.29 1.56 1.8 2.15 2.43 2.73 1.13 Storm Data Source: Garfield_2 MSE2 County, CO (NRCS) Rainfall Distribution Type: Type MSE2 Dimensionless Unit Hydrograph: <standard> WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Watershed Peak Table Sub -Area Peak Flow by Rainfall Return Period or Reach 2-Yr 25-Yr Identifier (cfs) (cfs) SUBAREAS ✓ .00 0.35 U .00 0.24 T .00 0.16 S .00 0.23 R .00 0.39 parking 0.92 2.30 REACHES ✓ .00 0.99 Down .00 0.99 U .00 0.77 Down .00 0.77 T .00 0.62 Down .00 0.62 S .00 0.39 Down .00 0.39 OUTLET 0.92 3.45 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Hydrograph Peak/Peak Time Table Sub -Area Peak Flow and Peak Time (hr) by Rainfall Return Period or Reach 2-Yr 25-Yr Identifier (cfs) (cfs) (hr) (hr) SUBAREAS ✓ .00 0.35 n/a 12.14 U .00 0.24 n/a 12.14 T -00 0.16 n/a 12.14 S .00 0.23 n/a 12.14 R .00 0.39 n/a 12.14 parking 0.92 2.30 12.13 12.12 REACHES ✓ .00 0.99 n/a 12.16 Down .00 0.99 n/a 12.16 U T S Down Down Down . 00 0.77 n/a 12.14 .00 0.77 n/a 12.16 . 00 0.62 n/a 12.14 .00 0.62 n/a 12.14 .00 0.39 n/a 12.14 .00 0.39 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Hydrograph Peak/Peak Time Table (continued) Sub -Area Peak Flow and Peak Time (hr) by Rainfall Return Period or Reach 2-Yr 25-Yr Identifier (cfs) (cfs) (hr) (hr) OUTLET n/a 12.14 0.92 3.45 WinTR-55, Version 1.00.10 Page 2 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Sub -Area Summary Table Sub -Area Drainage Time of Curve Receiving Sub -Area Identifier Area Concentration Number Reach Description (ac) (hr) ✓ :67 0.100 70 Outlet U .46 0.100 70 V T .31 0.100 70 U S .45 0.100 70 T R .75 0.100 70 S parking .98 0.100 88 Outlet Total Area: 3.62 (ac) WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Reach Summary Table Receiving Reach Routing Reach Reach Length Method Identifier Identifier (ft) ✓ Outlet 70 CHANNEL U V 116 CHANNEL T U 90 CHANNEL S T 110 CHANNEL WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Sub -Area Time of Concentration Details Sub -Area Flow Mannings's End Wetted Travel Identifier/ Length Slope n Area Perimeter Velocity Time (ft) (ft/ft) (sq ft) (ft) (ft/sec) (hr) V User -provided U User -provided T User -provided S User -provided R User -provided 0.100 Time of Concentration 0.100 0.100 Time of Concentration 0.100 0.100 Time of Concentration 0.100 0.100 Time of Concentration 0.100 0.100 Time of Concentration 0.100 parking User -provided 0.100 Time of Concentration 0.100 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb Sub -Area Identifier CCC - SW Bench Garfield_2 MSE3 County, Colorado Sub -Area Land Use and Curve Number Details Land Use Hydrologic Sub -Area Curve Soil Area Number Group (ac) ✓ CN directly entered by user .67 70 Total Area / Weighted Curve Number 67 70 U CN directly entered by user - .46 70 Total Area / Weighted Curve Number .46 70 T CN directly entered by user - .31 70 Total Area / Weighted Curve Number .31 70 S CN directly entered by user - .45 70 Total Area / Weighted Curve Number .45 70 R CN directly entered by user - .75 70 Total Area / Weighted Curve Number parking CN directly entered by user Total Area / Weighted Curve Number .75 70 .98 88 .98 88 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Reach Channel Rating Details Reach Reach Reach Friction Bottom Side Identifier Length Manning's Slope Width Slope (ft) n (ft/ft) (ft) ✓ 70 0.035 0.01 1 4 :1 U 116 0.035 0.01 1 4 :1 T 90 0.035 0.025 1 4 :1 S 110 0.035 0.025 1 4 :1 Reach End Top Friction Identifier Stage Flow Area Width Slope (ft) (cfs) (sq ft) (ft) (ft/ft) V T S 0.0 0.000 0 1 0.01 0.5 2.808 1.5 5 1.0 14.090 5 9 2.0 77.894 18 17 5.0 818.173 105 41 10.0 5030.343 410 81 20.0 31419.740 1620 161 0.0 0.000 0 1 0.01 0.5 2.808 1.5 5 1.0 14.090 5 9 2.0 77.894 18 17 5.0 818.173 105 41 10.0 5030.343 410 81 20.0 31419.740 1620 161 0.0 0.000 0 1 0.025 0.5 4.440 1.5 5 1.0 22.279 5 9 2.0 123.162 18 17 5.0 1293.645 105 41 10.0 7953.671 410 81 20.0 49678.971 1620 161 0.0 0.000 0 1 0.025 0.5 4.440 1.5 5 1.0 22.279 5 9 2.0 123.162 18 17 5.0 1293.645 105 41 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:17:44 PM WinTR-55 Current Data Description --- Identification Data --- User: tpb Date: 9/16/2019 Project: CCC - SW Bench Units: English SubTitle: Areal Units: Acres State: Colorado County: Garfield_2 MSE3 Filename: Z:\97000's\97404 Rudd, Wayne\97404.01 Cattle Creek\2019\SW Bldg Plans\drainage\ex basins Q-P-w pkg.w55 --- Sub -Area Data --- Name Description Reach Area(ac) RCN Tc Q Outlet 0.11 70 0.100 P Outlet 0.92 70 0.100 parking Outlet 0.23 88 0.100 Total area: 1.26 (ac) --- Storm Data -- Rainfall Depth by Rainfall Return Period 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1-Yr (in) (in) (in) (in) (in) (in) (in) 1.29 1.56 1.8 2.15 2.43 2.73 1.13 Storm Data Source: Garfield2 MSE2 County, CO (NRCS) Rainfall Distribution Type: Type MSE2 Dimensionless Unit Hydrograph: <standard> WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Storm Data Rainfall Depth by Rainfall Return Period 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1-Yr (in) (in) (in) (in) (in) (in) (in) 1.29 1.56 1.8 2.15 2.43 2.73 1.13 Storm Data Source: Garfield_2 MSE2 County, CO (MRCS) Rainfall Distribution Type: Type MSE2 Dimensionless Unit Hydrograph: <standard> WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Watershed Peak Table Sub -Area Peak Flow by Rainfall Return Period or Reach 2-Yr 25-Yr Identifier (cfs) (cfs) SUBAREAS Q .00 0.06 P .00 0.48 parking 0.22 0.54 REACHES OUTLET 0.22 1.07 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Hydrograph Peak/Peak Time Table Sub -Area Peak Flow and Peak Time (hr) by Rainfall Return Period or Reach 2-Yr 25-Yr Identifier (cfs) (cfs) (hr) (hr) SUBAREAS Q .00 0.06 n/a 12.14 P .00 0.48 n/a 12.14 parking 0.22 0.54 12.13 12.12 REACHES OUTLET 0.22 1.07 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield_2 MSE3 County, Colorado Sub -Area Summary Table Sub -Area Drainage Time of Curve Receiving Sub -Area Identifier Area Concentration Number Reach Description (ac) (hr) Q .11 0.100 70 Outlet P .92 0.100 70 Outlet parking .23 0.100 88 Outlet Total Area: 1.26 (ac) WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Sub -Area Time of Concentration Details Sub -Area Flow Mannings's End Wetted Travel Identifier/ Length Slope n Area Perimeter Velocity Time (ft) (ft/ft) (sq ft) (ft) (ft/sec) (hr) 4 User -provided P User -provided parking User -provided 0.100 Time of Concentration 0.100 0.100 Time of Concentration 0.100 Time of Concentration 0.100 0.100 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM tpb CCC - SW Bench Garfield 2 MSE3 County, Colorado Sub -Area Land Use and Curve Number Details Sub -Area Hydrologic Sub -Area Curve Identifier Land Use Soil Area Number Group (ac) Q CN directly entered by user - .11 70 Total Area / Weighted Curve Number .11 70 P CN directly entered by user .92 70 Total Area / Weighted Curve Number .92 70 parking CN directly entered by user - .23 88 Total Area / Weighted Curve Number .23 88 WinTR-55, Version 1.00.10 Page 1 9/16/2019 1:16:30 PM CCC SW Bench - Basins V through R Q(25) to 4(100) Determination of MAJOR Detention Volume Using Modified FAA Method Design Information (Input): Catchment Drainage Imperviousness Catchment Drainage Area Predevelopment NRCS Soil Group Return Period for Detention Control Time of Concentration of Watershed Allowable Unit Release Rate One -hour Precipitation Design Rainfall IDF Formula i = C1* P1/(C2+TJ^C3 Coefficient One Coefficient Two Coefficient Three la = A= Type = T= Tc = q= P� = C1 = C2 = C3 = 10.00 3.620 B 25 8 0.41 1.05 28.50 10 0.789 percent acres A, B, C, or D years (2, 5, 10, 25, 50, or 100) minutes cfs/acre inches Determination of Average Outflow from the Basin (Calculated): Runoff Coefficient Inflow Peak Runoff Allowable Peak Outflow Rate C Qp-in = Qp-out = Mod. FAA Major Storage Volume = Mod. FAA Major Storage Volume = 0.31 3.43 cfs cfs cubic feet acre-ft 1.48 1,599 0.037 Rainfall Duration minutes (input) Rainfall Intensity inches / hr (output) Inflow Volume cubic feet (output) Adjustment Factor (output) Average Outflow cfs (output) Outflow Volume cubic feet (output) Storage Volume cubic feet (output) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 0.00 4.21 3.73 3.36 3.06 2.82 2.61 2.44 2.29 2.16 2.04 1.94 1.85 1.77 1.70 1.63 1.57 1.51 1.46 0 567 1,005 1,356 1,648 1,896 2,110 2,298 2,466 2,616 2,753 2,878 2,993 3,100 3,199 3.291 3.378 3,460 3.537 0.00 1.00 1.00 1.00 1.00 0.90 0.83 0.79 0.75 0.72 0.70 0.68 0.67 0.65 0.64 0.63 0.63 0.62 0.61 0.00 1.48 1.48 1.48 1.48 1.34 1.24 1.17 1.11 1.07 1.04 1.01 0.99 0.97 0.95 0.94 0.93 0.92 0.91 0 178 356 534 712 801 891 980 1,069 1,158 1,247 1,336 1,425 1,514 1,603 1,692 1,781 1,870 1,959 0 389 648 822 936 1,094 1,219 1,319 1,397 1,459 ,506 ,542 ,568 ,586 ,596 ,599 ,597 ,590 ,578 UD_Detention_2.2.xls, Modified FAA 9/16/2019, 2:18 PM 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 1.41 3,610 1.37 3,680 1.32 3,746 1.29 3,809 1.25 _ 3,870 1.22 3,928 1.18 3,983 1.15 4,037 1.12 4,089 1.10 4,138 1.07 4,186 1.05 4,233 1.02 4,278 1.00 4,321 0.98 4,364 0.96 _ 4,405 0.94 1 4,444 0.92 I 4,483 0.91 4,521 0.89 4,558 0.87 _ 4,594 0.86 4,629 0.84 4,663 0.83 4,696 0.82 4,729 0.80 4,761 0.79 4,792 0.78 4,822 0.77 4,852 0.76 4,882 0.74 4,910 0.73 4,939 0.72 4,966 0.71 4,993 0.70 5,020 0.69 5,046 0.68 5,072 0.68 5,097 0.67 5,122 0.66 5,147 0.65 5,171 0.64 5,194 0.61 0.60 0.60 0.59 0.59 0.58 0.58 0.58 0.57 0.57 0.57 0.57 0.56 0.56 0.56 0.56 0.56 0.56 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.54 0.53 0.53 0.53 0.90 0.89 0.88 0.88 0.87 0.87 0.86 0.86 0.85 0.85 0.84 0.84 0.84 0.83 0.83 0.83 0.83 0.82 0.82 0.82 0.82 0.82 0.81 0.81 0.81 0.81 0.81 0.81 0.81 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.79 0.79 0.79 0.79 2,048 2,137 2,226 2,315 2,404 2,493 2,583 2,672 2,761 2,850 2,939 3,028 3,117 3,206 3,295 3,384 3,473 3,562 3,651 3,740 3,829 3,918 4,007 4,096 4,185 4,274 4,364 4,453 4,542 4,631 4,720 4,809 4,898 4,987 5,076 5,165 5,254 5,343 5,432 5,521 5,610 5, 699 1,562 1,543 1,520 1,494 1,465 1,434 1,401 1,365 1,328 1,289 1,248 1,205 1,161 1,115 1,069 1,021 971 921 870 818 764 710 655 600 543 486 428 370 311 251 191 130 68 6 -56 -119 -182 - 246 -310 - 375 -440 -505 Mod. FAA Major Storage Volume (cubic ft.) = 1,599 Mod. FAA Major Storage Volume (acre-ft.) = 0.0367 UD_Detention_2.2.xls, Modified FAA 9/16/2019, 2:18 PM APPENDIX B: SOILS AND SUPPLEMENTAL INFORMATION 3 V 3 ti °1. Soil Map —Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Map Scale: 1:3,670 if printed on A portrait (8.5" x 11") sheet rMeters 0 50 100 200 300 Feet 0 150 300 600 900 Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 3 39° 27 20" N 39° 26' 55" N i!51)‘ Natural Resources Web Soil Survey oam Conservation Service National Cooperative Soil Survey 9/4/2019 Page 1 of 3 Soil Map —Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Area of Interest (AO1) Soils MAP LEGEND Area of Interest (AOI) Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features w 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 4. gt Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation } E{ Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography MAP INFORMATION 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: Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 9, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Sep 24, 2015—Nov 2, 2015 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. USDA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/4/2019 Page 2 of 3 Soil Map —Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Map Unit Legend Map Unit Symbol Map Unit Name Acres In AOI Percent of AOI 13 Atencio-Azeltine complex, 3 to 7.6 18.3% 6 percent slopes 55 Gypsum land-Gypsiorthids complex, 12 to 65 percent slopes 24.2 58.3% 94 Showalter-Morval complex, 5 to 15 percent slopes 4.1 10.0% 96 Southace cobbly sandy loam, 1 to 6 percent slopes 1.5 3.6% 98 Southace cobbly sandy loam, 12 to 25 percent slopes 4.1 9.8% Totals for Area of Interest 41.5 100.0% USDA Natural Resources Web Soil Survey 9/4/2019 is Conservation Service National Cooperative Soil Survey Page 3 of 3 Map Unit Description: Gypsum land-Gypsiorthids complex, 12 to 65 percent slopes---Aspen- Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties 55—Gypsum land-Gypsiorthids complex, 12 to 65 percent slopes Map Unit Setting National map unit symbol: jq6f Mean annual precipitation: 10 to 15 inches Mean annual air temperature: 39 to 46 degrees F Frost -free period: 80 to 105 days Farmland classification: Not prime farmland Map Unit Composition Gypsum land: 65 percent Gypsiorthids and similar soils: 20 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Gypsum Land Typical profile H1 - 0 to 60 inches: gypsiferous material Properties and qualities Slope: 12 to 65 percent Depth to restrictive feature: 0 inches to paralithic bedrock Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): Very low (0.00 to 0.00 in/hr) Salinity, maximum in profile: Moderately saline to strongly saline (8.0 to 32.0 mmhos/cm) Available water storage in profile: Very low (about 0.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8s Hydric soil rating: No Description of Gypsiorthids Setting Landform: Mountains, drainageways, hills Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Mountainflank, side slope Down -slope shape: Linear Across -slope shape: Linear Parent material: Mixed colluvium and/or mixed residuum Typical profile H1 - 0 to 8 inches: fine sandy loam USDA Natural Resources Web Soil Survey 0+. Conservation Service National Cooperative Soil Survey 9/4/2019 Page 1 of 2 Map Unit Description: Gypsum land-Gypsiorthids complex, 12 to 65 percent slopes---Aspen- Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties H2 - 8 to 23 inches: fine sandy loam H3 - 23 to 39 inches: fine sandy loam H4 - 39 to 43 inches: weathered bedrock Properties and qualities Slope: 12 to 50 percent Depth to restrictive feature: 10 to 40 inches to paralithic bedrock Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high (0.06 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 Gypsum, maximum in profile: 12 percent Salinity, maximum in profile: Slightly saline to moderately saline (4.0 to 8.0 mmhos/cm) Available water storage in profile: Low (about 5.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8s Hydrologic Soil Group: B Hydric soil rating: No Minor Components Other soils Percent of map unit: 15 percent Hydric soil rating: No Data Source Information Soil Survey Area: Aspen -Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 9, Sep 10, 2018 USDA Natural Resources Web Soil Survey 9/4/2019 Conservation Service National Cooperative Soil Survey Page 2 of 2