FLOOD00275

• County: Adams
• Community: Westminster
• Title: Bruchez Farms Property - Big Dry Creek at Wadsworth Parkway
• Date: 1/1/1998
• Prepared For: Bruchez Farm
• Prepared By: Wright Water Engineers Inc
• Floodplain - Doc Type: Floodplain Report/Masterplan

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to the above reports. These Included the Bruchez correspondence me, topographic

maps, meetings with Kevin Stewart and William DeGroot of the UD&FCD and Randy

Case of the city of Westminster, and the various computer models and output devel-

oped during the 1986 study.

HYDROLOGY
Durfng a study's hydrologic phase, runoff hydrographs are developed which incor-
porate the runoff volumes and peak flow rates based on design rainfall input and
other physical variables anticipated for the ultimate development of the watershed.

Existing Hydrologic: Hodel

The hydrologic model used in this report was developed by Greiner Engineering for

their 1986 report. This model Is based on current guidelines of the UD&FCD for

rainfall and hydrograph synthesis. Hydrographs for each subbasin were developed

using the Colorado Urban Hydrograph Procedure (CUHP) of the UD&FCD. These indivi-

dual hydrographs for each subbasin were then routed through the various channels

and combined using the HEC-l Flood Hydrograph Package of the U. S. Army Corps of

Engineers (USACE).

Rllnfall. The rainfall used in the 1986 stUdy uttl1zed the current UD&FCD guide-

lines. The lOG-year rainfall event has a total depth of 3.08 Inches distributed over

a 2-hour period according to the time distribution of rainfall contained in their

Storm Drainage Manual. A depth of 2.60 Inches of rain occurs in the first hour.