Coppell Industrial-CS000628Graham A iates, Inc.
CONSULTING ENGINEERS & PLANNERS
June28,2000
Mr. Ken Griffin, P.E.
Director of Engineering and Public Works
City of Coppell
255 Parkway Boulevard
Coppell, Texas 75019
RE: V~Ooppell Industrial Addition
Bethel Road
Ken:
Since the plat and site plan for the first phase of Coppell Industrial were approved, we have met
several times with Duke-Weeks in an attempt to finalize a discharge point and elevation for the
stormwater detention pond. Though everyone seems to agree on the concept, it has been
impossible to agree on a specific location or elevation for unifying a storm drain system. Duke-
Weeks has taken the position that until they are committed to a firm development plan and know
the cost associated with the ultimate drainage scenarios at their eastern boundary, they will not
designate a discharge point due to limitations it will put on their building layouts. This has
unduly delayed Champion's ability to meet several market objectives and construction
commitments. This has furthermore forced us to evaluate alternative methods of discharging the
detained stormwater. Until such time that a connected channel or pipe system can be developed
by Duke-Weeks, we are proposing a feasible interim drainage system to simulate sheet flow
runoff along, and solely upon, the eastern boundary of Champion's property. Before we initiate
detail construction plans and specifications for this system, however, we would like to discuss
the acceptability of this scenario with you and your staff. The system involves a traditional
wetwell arrangement with three pumps set in series. The pumps would be sized and float levels
set to simulate the 2 year, 5 year and 100 year rainfall events. The discharge system is described
below with schematic sketches attached. We have successfully employed a similar system at the
Poly America manufacturing facility in Grand Prairie to distribute runoff along the property line
rather than concentrate flow into a single point source.
Irrigation Discharge System:
Discharge from the pumps would be into a series of pipe headers along the east property line.
Each header would consist of perforated PVC pipe anchored to the ground by metal or concrete
collars. Water would be discharged over several hundred feet through the pipe perforations into
a gravel bed to prevent erosion and undermining of the pipe. The water would then surface flow
easterly via the natural ground slope.
Summit Office Park
1300 Summit Ave., Suite 419
Ft. Worth, Texas 76102
(817) 332-5756
FAX (817) 336-6909
Centerpoint Two
616 Six Flags Drive, Suite 400
Arlington, Texas 76011
(817) 649-8530 * Metro (817) 640-8535
FAX (817) 633-5240
NationsBank
705 W. Ave. B, Suite 201
Garland, Texas 75040
(972) 272-4655
FAX (972) 272-4655
We would like to meet with you as soon as possible to discuss any questions, details, or concerns
you may have regarding this solution. Please call me at 817-640-8535 with a time you are
available to get together.
Sincerely,
Chuck Stark, P.E.
Vice President
CC[
Mike Martin - City of Coppell
Jim Stewart - Champion Partners
Steve Golding - Champion Partners
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