Cambridge Phase 1-CS 941230 EXD~VF'-"V, ANDE~N AND ASSOCI/-'ES, INC.
CIVIL i:NCI N]~I~RS
162,50 DALLAS PARKWAY SUITE 100
DALLAS, TEXAS 7524~
(2~4) 931-O694 FAX (214) 931-9538
Dee~ber 30, 199~
Mr. Garreth CamDbell
Engineering DeDartment
City of Co,Dell
255 Parkway Boulevard
Coppell, Texas 75019
RE: Cambridge Manor
Outfall Weir
Dear Garreth:
Per our conversation today, I am documenting the events related to
the construction of the weir:
1. We previously designed a series of weirs, of which, several
were adequate; however, the owner had reservations on each of
the previous submittals.
2. Upon excavation of the approved design, the contractor,
Robertson Pools, adjusted the side sloDes o£ the channel to
better fit the trees and natural ground in the vicinity.
3. Ron Robertson requested to use ~unite for material in lieu of
Concrete due to the lack of accessibility to the site.
I had no Droblem with this provided a mix design was submitted
for review. The surface will be broom finished. Weed holes
will be installed.
The hydraulics of the weir flow are within an acceptable
limit. The actual controlling influence of the subdivision is
the 100-year water surface elevation on Denton Creek. The
flow is 88.3 cfs through the weir. I reviewed the Dlan using
Manning's Equation which resulted in a depth = 1.7' and I
reviewed the plan using a weir flow equation which resulted in
a deDth ~ 2.3' With a flow line elevation of 448.0, the pond
elevation wou~d result in a water surface of 448.0 + 2.3' or
450.3' The 100-year water surface, which controls the
gu~iv~s~on i~ 452.3; hence, Denton Creek controls rather than
the ' .
If you have any additional questions, Dlease contact me.
sincerely,
William A. Anderson, P.E.
WAAIsg
TOTRL P.02