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<br />Lower Big Dry cpreek Hydrologic Study
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<br />continue to be modeled after UDFCD's utban Storm Drainage Criteria Manual. UDFCD
<br />serves 39 Colorado towns, cities and counties in the Metro Denver area including Adams
<br />County, Arapahoe County, Boulder County, City & County of Broomfield, City & County of
<br />Denver, Douglas County, Jefferson County and the cities of Arvada, Aurora, Boulder, Bow Mar,
<br />Brighton, Centennial, Cherry Hills Village! Columbine Valley, Commerc~ City, Edgewater,
<br />Englewood, Erie, Federal Heights, Foxfield, Glendale, Golden, Qreenwood Village, Lafayette,
<br />Lakeside, Lakewood, Littleton, Lone Tree, Louisville, Morrison, Mountain View, Northglenn,
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<br />Parker, Sheridan, Superior, Thornton, Westminster and Wheat Ridge.
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<br />In keeping with UDFCD's policies, most Jf these entities require detention for tbe IOO-year
<br />event, and most "home-rule" cities also have la policy to detain the minor storm event, which may
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<br />vary from the 2-, 5- or 10-year event. Additionally, over the last 5-10 years or so, communities
<br />regulated under the Phase I or Phase II stdrmwater regulations also now typically require or
<br />encourage detention of the water quality capture volume (WQCV), which controls more
<br />frequently occurring events (Personal communication with John Doerfer, UDFCD). Smaller
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<br />urban areas (>10,000 and <1 00,000 people) have begun to require detention or treatment of the
<br />WQCV over the last several years. Thus, mbst of the urbanized areas in the metro Denver area
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<br />now provide detention for about three desib events. Other UDFCD policies were previously
<br />described in Section 5.1. I
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<br />7.1.2 Enqineerina Manuals of Practice Jnd Texts
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<br />Use of detention facilities to control peak flows associated with urbanization is a common
<br />practice recommended and discussed in virtually all engineering texts and manuals of praetice.
<br />Several of these references were revieted with regard to design considerations and
<br />recommendations for detention facilities, with a few examples of findings provided below.
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<br />. In Municipal Storm Water Management, Debo and Reese (2003) discuss stormwater
<br />ordinances and regulations, including the fact that many local governments require on-site
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<br />detention to reduce downstream run0ff peaks. Additionally, they note that some states
<br />have passed laws related to stormwatbr management to "assure that the maximum rate of
<br />storm water runoff is not greater aft~r development than prior to the development" and
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<br />Wright Water Engineers, Inc.
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<br />971-179.092
<br />June 2005
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<br />Page 50
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