SC-Coppell HS-CS 870408TEAGUE NALL AND PERKINS. INC.
915 Florence Street/Fort Worth, Texas 76102
817 3~5773
Metro 429.8306
April 8, 1987
C
P
Y
Mr. Wayn~ Ginn, P.E.
Ginn, Incorporated
17103 Preston Road, 9100, LB 118
Dallas, Texas 75248
Re:
New COppell High School
Drainage Improvements
Dear Mr. Ginn:
At present, our office is making revisions to the storm drain
plans per comments by your office and that of the City staff.
We are near complete in making these revisions to resubmit to
the City for final review which we anticipate will be
distributed to your office.
However, before these plans are resubmitted to your office for
final review, there is one comment which was made on Sheet 4
of 10 (the storm drain box culvert sheet). It has been
requested that a concrete or rock riprap lining be placed on
the bottom and side slopes of the proposed 245' earthen
channel which conveys water from the double 9x5 box culvert to
the existing creek. We are requesting that the proposed
channel section be left as we have shown it on our drawings
with a 15' wide grouted rock riprap blanket transitioning into
the earthen channel for the following reasons:
Ail of this area is totally within the 100-year
f~oqdplai.n, and for the most part is within the
100-year .floodway.
e
Since we are conveying offsite and upstream water
through an underground system through the school's
property to our north property line, it does not
seem cost effective (additional $30,000) to perform
this additional work for such a small length of
channel which will, in essence, be in a "natural"
floodway area at the creek.
Since this section is offsite through land not owned
by the school or currently being developed, it would
seem that something less permanent would be more
appropriate.
Mr. W~yne Glnn, P.B.
April 8, 19'87
Page Two
Finally, to address the conoeFn for
channel, we w~uld' propose that
hydro-mulched a~nd that. grass be
channel velocities for S-year and
and 5.4 fps respectively and,
should provide significant erosion
Thank you for reconsideration. We ~uld
you can make to a~dreas this ma~'ter
possible. We look forward to hearing
additional information or input is needed
please feel free to call.
Sincerely,
STR/ll
Gary Keep, SHWC., Inc.
Jim Boughton, 8HWC., Inc.
Dr. David stanfield,-Coppell
Sheree Daneshmand., City'of CQi~ll
John Na11, Teague Nall and P~kins, Inc.