FLOOD10337 ‎(2)‎

• County: Arapahoe
• Community: Greenwood Village
• Stream Name: Upper Goldsmith Gulch
• Title: Flood Hazard Area Delineation, Upper Goldsmith Gulch
• Date: 4/1/2005
• Prepared For: Urban Drainage and Flood Control District, Arapahoe County and Greenwood Village
• Prepared By: Moser and Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Peak flow profiles for Goldsmith Gulch and the West Tributary demonstrate the peak discharge at key
locations throughout the watershed. The peak flow profiles Chart A-I and Chart A-2 are provided in
Appendix A. Figure A-7 in Appendix A illustrates the characteristics of the existing detention basins.
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2-3

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SECTION 2
2.5 RESULTS
Using the physical subwatershed hydrologic parameters and rainfall information, along with the drainage
system conveyance characteristics, peak flow rates were determined. Table A-7 in Appendix A provides
peak flow rate information at each of the elements along the drainageway for the 10-, 50-, 100-, and the
500-year storm events for the existing land-use condition. Table 2-2 below compares the 100-year peak
flow at Belleview from the various past studies with the existing-condition UDSWM model. Table 2-3
compares the peak flow at various locations from the 1976 FHAD with the existing-condition model. As
you can see, the value of the existing-condition model compares well with the values used in the 1976
FHAD in defining the current floodplain.
TABLE 2-2 - Peak Flow Comparison at BeUeview

Study 100- Y ear Discha~e (cfs)
1976 FHAD 2,250
1995 FIS 2,250
2005 Outfall Systems Planning Study (Moser) 2,555

Design Location Drainage 100-Year Peak Flow (cfs)
Element Area (ac) 1976 FHAD Moser
100 Belleview Avenue 1535.3 2250 2555
110 Prentice Avenue 1279.4 2100 2232
150 Yosemite Street 1070.1 1750 1996
190 Berry Avenue 1017.6 1750 1965
211 Into Orchard Hills Park 974.1 1730 1993
400 Tributary before Goldsmith Gulch 468.5 1250 1006
410 Into Tommy Davis 440.3 1435 1026
440 Fair Avenue 284.8 1085 724
460 Into Caley Detention 233.6 900 883
510 Bridgewater Apartments 99.2 240 381
600 Goldsmith Gulch before Tributary 439.0 540 886
620 Into Silo Park 346.2 1000 1004
650 Arapahoe Lake Outfall 238.1 800 787
700 Arapahoe Lake-SW Cove 115.8 800 472
710 Caley Avenue 108.8 480 446
730 Appletree Condos 78.7 480 337
740 Peakview Avenue 54.4 300 244
770 Arapahoe Road 23.0 100 107
821 Orchard Hills 907.5 1530 1939
841 Tommy Davis Park/Orchard Road 440.3 1250 965
846 Caley Detention/Caley A venue 233.6 900 593
862 Silo Park/Orchard Road 346.2 540 756

Table 2-3 - 1976 FRAD Peak Flow Comparison

HYDROLOGIC ANALYSIS