Park West CC(15.1)-CS 940627PEARCE AND ASSOCIATES, INC.
Consulting Engineers
June 27, 1994
O.N. 94-002
Kenneth Griffin, P.E., City Engineer
City of Coppell
P.O. Box 478
Coppell, TX 75019
RE:
Lone Star Plyuood site
~irline Drive, Coppell
Dear Mr. Griffin:
Ue hereby request a variance in the storm sewer design criteria
regulations to allow the use of rainfall intensity curves based
on National Ueather Service rainfall frequency data presented in
Technical Memorandum NUS HYDRO-SS, dated June, 1977, in lieu of
Technical Paper No. 40., dated May, 19Sl.
The lO0-year intensity which we intend to use, based on an
initial time of concentration of IS-minutes, is ?.? inches per
hour, and, in accordance with your instructions, the runoff
coefficient for this development will be 0.95 inches per inch.
Please let us know if this meets with your approval.
Sincerely,
PEgRCE ~ND gSSOCI~TES, INC.
Robert L. Pearce, P.E., President
3321 TOWERWOOD DR. · SUITE 100 . FARMERS BRANCH, TX75234 . 214/247-1353 · FAX214/247-2680