ST9605-CS 961018 LICHLITER/JAMESON
Environment & Infrastructure 1420 W. Mockingbird Lane, Suite 300
Consulting Engineers, Scientists and Planners ~ Dallas, TX 75247-4906
Tel. (214) 630-8867
FAX (214) 631-8428
October 18, 1996
Mr. David Hensley, P.E.
Design Engineer
Texas Department of Transportation
2624 Prairie
Denton, TX 76201
Re: North Point Drive Extension to S.H. 121 - Coppell, Texas
Mr. Hensley:
As we discussed earlier this week, the City of Coppell Planning and Zoning Commission and the
City Council have both approved the Preliminary Plat for the referenced roadway extension. Rust
Lichliter/Jameson (RL/J) is currently working on final construction plans. The purpose of this letter
is to request your approval of our drainage plan in regard to runoff across the north bound S.H. 121
service road.
According to our calculations, approximately 18.2 acres of the subject property currently drains
across the S.H. 121 service road by sheet flow. The current land use (vacant) has a runoff coefficient
('C') of 0.3. The proposed development will result in an increase in the runoff coefficient to 0.9.
This increase in 'C' from pre-development to post-development will result in an increase in peak
runoff by approximately 300 percent.
RL/J proposes to allow the continuance of sheet flow across the service road at a rate not to exceed
the peak runoff from un-developed (existing) conditions. In order to achieve this, approximately
two-thirds (12.1 acres) of the area currently draining to the service road will be diverted east (away
from the highway) when the site is developed.
Please review the above facts and, if you are in agreement with this proposal, write a letter to me
indicating your approval. We would appreciate your response by Friday, October 25, 1996.
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Please call me at (214) 630-8867 if you have any questions.
Thanks for your assistance,
RUST Lichliter/Jameson
Stephen A. Gude, P.E.
Project Manager
cc Mr. Mike Martin - City of Coppell
Mr. Jim McElroy - T/E Freeport North Land II, LTD
Ms. Deborah Dews -T/E Freeport North Land II, LTD
Mr. Jeff Williams - Graham Associates, Inc.