Cottonwood Est-SY 160208Kimley>Morn
February 8, 2016
Mr. Michael Garza, P.E.
Assistant Director of Public Works
City of Coppell
265 E. Parkway Boulevard
Coppell, TX 75019
RE: 141 Cottonwood Drive
Updated Hydraulic Analysis to Reflect New Fence
Dear Mr. Garza
Fill was placed at 141 Cottonwood Drive in accordance with the City -approved Cottonwood Branch
Floodplain Study prepared by Kimley-Horn, dated March 31, 2014. A pre-existing fence was also
replaced with a new fence as part of the building improvements at the subject tract. The new fence
was not included in the City -approved floodplain study.
Kimley-Horn has added the new fence to the hydraulic model to determine its impact on water
surface elevation, velocity, and valley storage of Cottonwood Branch. The fence consists of 6" wood
posts and was added to the HEC -RAS model as a blocked obstruction. The blocked obstruction was
included at the three cross sections that intersect the fence.
Results of the hydraulic analysis show that the fence does not adversely impact water surface
elevation, velocity, and valley storage of Cottonwood Branch. Digital modeling files in support of this
conclusion can be provided upon request.
Sincerely,
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Brad Pickering, P/E., CFM
W. PICI
102320
Al Er
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kimley horn.com