DR9001-CS 900606GINN, INC.
CONSULTING ENGINEERS
June 6, 1990
Mr. Steve Goram
City of Coppell
P.O. Box 478
Coppell, TX 75019
Re: Connell/Skaggs Drainage Project
Dear Mr. Goram:
We have researched our files as requested in your May 25, 1990
memorandum regarding the Connell/Skaggs Drainage and Willow (or
Mills) Lane east of the high school site. Our research has
turned up some important documents including a copy of the signed
agreement between Connell and the City of Coppell. Copies of
these documents are attached for your use and reference. In the
interest of brevity, we have taken the liberty of highlighting
some key statements in these .~documents which support the
following answers to the question~ raised in your memorandum.
The prorata question regarding the box culvert from the
high school to Sandy Lake Road is best addressed in the
highlighted area of the agreement. It is our opinion that
prorata can be assessed under the agreement only if the box
culvert is necessary for development of the particular site
in question. The agreement and some later documentation are
included in "Exhibit A".
The issue of Willow Lane has only been addressed in our
files as a "bus lane" to be used exclusively by the high
school. We have heard the idea of a 37' street which
"loops" back south to Sandy Lake Road through Glen Hinckley
on several occasions. We have not encountered the latter
elsewhere in either written or verbal form. For your
convenience we have grouped the Willow (Mills) Lane issues
in "Exhibit B".
AS of this date we have not received any correspondence,
plans, speclfi~ations or literature regarding the alternate
construction method proposed. If it is your intent that we
perform a formal technical review of the proposed alternate
culvert, please indicate such in writing and we will obtain
the design/construction information and begin our review
post haste. Otherwise, I believe that the developer's
engineer should be able to substantiate the effectiveness of
the proposed alternate.
17103 Preston Road · Suite 100 · LB 118 · Dallas, Texas 75248 · Phone 214/248-4900
There was a side issue regarding the Hinckley Tract Drainage
which we feel needs a brief explanation. As you will recall, we
mentioned that our field observation indicated that most, if not
all of the Hinckley Tract drains to Denton Tap Road. Our
preliminary storm sewer design on Denton Tap Road included about
1/2 of the Hinckley Tract in our drainage area. In October of
1987 we were requested by the city to investigate the Willow
Lane R.O.W. issues regarding Mr. Dunn's fence encroaching public
R.O.W. It was during this period that we noticed the drainage
characteristics of the adjacent Hinckley Tract were somewhat
different than the aerial topography used in the preliminary
design of Denton Tap Road.
We checked the proposed storm sewer to determine if it had
sufficient capacity to handle the additional runoff and
determined that it does. We revised the Denton Tap Road
Improvements final plans to provide a 30" storm sewer stubout at
the low point along the Hinckley Tract for that purpose. In the
heavy rains experienced during May, June and July of 1989, our
revised drainage assumptions were confirmed by actual field
observation of the stormwater runoff at the Hinckley Tract.
We have not done any detailed evaluation of the Boorhem Tract,
but we think that part of the Boorhem Tract may be served by the
proposed box culvert.
Please call me if you have any questions.
Sincerely,
John C. Karlsruher, P.E.
Senior Engineer
JCK/dsp
cc: H. Wayne Ginn, P.E.
File 90438