ST9304-CS 890216 GINN, INC. CONSULTING ENGINEERS
~. ~e~/~. Do~e,
City Engi~er I
City of ~ppell
P.O. Bo~ 478
Co~pe~, Tex:s 75019 ~0~ ~ ~"
Re. / Belt Line Road Improve~nts (~-W) from M~Arth~ Blvd--.
the West Overflow Swale of the Trinity River, Coppell,
Texas.
Dear Mr. Doyle:
We have reviewed the attached February 2, 1989 letter to you from
C. Michael Daniel, P.E. of Nathan D. Maier Consulting Engineers
as you requested. Our recommendation is that the flowline
elevation of the headwall and the upstream invert of lateral A-8
be lowered to an elevation of 437.49 which will establish it
0.37', or approximately 4.5", lower than the outfall of the
Northwest Dallas County Flood Control District's storm sewer. As
shown on the attached partial xerographic reduction of sheet GD-
2, this will change the grade on lateral A-8 to 0.5% slope. At
this slope lateral A-8 still has suitable flow capacity, under
~r~e outfal~ condition~, to handle the 100 year storm; and there
~preCi~rence between the hydraulic performance of
the original design and the revised design under the pressure
flow conditions of the 100 year flood with the backwater effects
of Grapevine Creek.
In telephone conversations with Mr. Bud Beene, P.E., of Dallas
County, he has emphasized that it is very important to have GTE
lower their cables, which are shown to be directly beneath the
apron of the headwall for lateral A-8, within the next 30 days.
Conversations with GTE indicate that the cables in question are
not very large and do not pose a great difficulty in lowering.
In summary, the anticipated lowering of the GTE cables isn't a
major affair, but it would be prudent %o initiate the lowering
process with GTE as soon as possible. For that purpose, we have
prepared a letter for your signature transmitting marked drawings
and requesting that GTE lower their facilities to avoid the
roposed revised storm sewer lateral A-8. Incidentally, GTE must
erform this at their cost in accordance with the franchise
greement with the City of Coppell since the cables are in the
City Right-Of-Way.
We have also prepared a letter of response for your signature to
Dallas County requesting that they revise their plans as shown on
the attached sheet.
17103 Preston Road · Suite 100 · LB 118 · Dallas, Texas 75248 · Phone 214/2484900
Please sign both letters and mail them as soon as possible in
order to get the ball rolling. Call me if you have any
questions.
S' r~ 1
J~hn C. Karlsruher, P.E.
Senior Engineer
enclosures
CC '
H. Wayne Ginn, P.E.
Bud Beene, P.E. - Dallas County Public Works
C. Michael Daniel, P.E. - Nathan D. Maier Consulting
Engineers