HomeMy WebLinkAboutDrainage Report 7607 Eastmark Drive, Ste. 252 -A <77840>
•
P.O. Box 9253, College Station, TX 77842
ME - Off /Fax (979) 764 -0704
Ply Eriineer's email: civil @rmengineer.com
July 9, 2010
City of College Station
Planning & Development Services
1101 Texas Avenue South
College Station, TX 77842
RE: West District: United Methodist Church
4201 State Highway 6 South, College Station, TX
Lot 1 & 2 — Barron Park Subdivision — Brazos County
Drainage Letter
RME No. 255 -0404
To Whom It May Concern:
The above referenced project is proposed to include a 2,300 sq.ft. office building with sidewalk
improvements and is located in the eastern corner of the property (see attached). Drainage from
this development will be conveyed overland and into the existing parking/drive facility to the
west. Runoff will then be conveyed by means of surface and underground drainage to the
detention facility, located along the western property line, which was constructed with the
Sanctuary Expansion (called Phase 3 — November, 2006).
Development conditions are anticipated to yield increased runoff of approximately 0.35 cfs
during the 100 -year rainfall event. Calculations for this runoff rate are calculated using the
Rational Method with the following assumptions. An increase of this magnitude should be
considered negligible and no detention/drainage improvements are anticipated for this size of
development.
Rational Method: Q =CIA where,
Q = runoff rate (cfs)
C = change in runoff coefficient (unitless): CEx =0.39 & CPR =0.95
I = 100 -year rainfall intensity ( in/hr): 11.63 in/hr
A = runoff area (acres): 0.053 acres
Q = 0.56 x 11.63 x 0.053 = 0.35 cfs
CD1- 255- 0404- L02.docx Page 1 of 2
7607 Eastmark Drive, Ste. 252 -A <77840>
P.O. Box 9253, College Station, TX 77842
ME Off /Fax (979) 764 -0704
r�su/-rmy En email: civil @rmengineer.com
Please call if you have any questions or require additional information.
Sincerely,
OF TF
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4111. 9 ..*
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Rabon A. Metcalf, P.E.
Texas Firm Registration No. F -4695
rabon @rmengineer.com
CD1-255-0404-L02.docx Page 2 of 2
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