DR9604-CS000306/~--') The City With A Beautiful Future
~ P.O. BOX 478
COPPELL, TEXAS 75019,
Mr. Steven Jenkins P.E.
Director of Public Works
City of Carrollton
P.O. Box 110535
Carrollton, Texas 75011-0535
COPY
RO. Box 478
Coppell, Texas 75019
972462-OO22
March 6, 2000
RE: Denton Creek Study Plan / DR 96-04
Dear Mr. Jenkins:
This letter is written as a follow-up to our prior meeting and telephone conversation concerning
plans the City of Coppell have for Denton Creek and how those plans interface with the City of
Carrollton. With this letter I am providing a copy of an Upper Trinity River Basin Study Plan
prepared by the US Army Corps of Engineers, a proposed plan of reclamation and grading from
the City of Carrollton prepared by Nathan Maier, a copy of the Denton Creek Watershed
Feasibility Study Proposal from 1998, a copy of the Project Study Plan\Denton Creek Watershed
from 1996, a copy of a 1996 City of Carrollton letter from Tim Tumulty expressing some
concerns. Also in this letter I will try to explain the City of Coppell's thoughts on involving the
City of Carrollton in this project.
The City of Coppell experiences high flows and velocities that contribute to erosion along the
section of Denton Creek that runs along the eastern side of Coppell between the levee and the
confluence of Denton Creek with the Elm Fork of the Trinity River. In trying to address some of
the velocity and erosion issues with the citizens, it was the City of Coppell's opinion that the
release of water from the Corps of Engineer's controlled dam at Lake Grapevine was a
contributing factor to the problems. The control of the water by the Corps of Engineers has at
times caused rapid drops in the water surface and the rapid drops have taken substantial amounts
of soil with them. Also, as Denton Creek leaves the levee area it narrows from a very wide
channel to a natural creek. The reduction of conveyance area causes an increase in velocities. In
general, it was the City of Coppell's opinion that there should be some way to control the flow of
water in the unimproved portion of Denton Creek that would have a benefit in both velocity and
reduction of erosion. In discussing this with the Corps of Engineers, there was a concept
proposed that included allowing the water to continue in a easterly direction to a detention area
and then releasing the water out of the detention area into Denton Creek and the Elm Fork of the
Trinity River near their confluence. The concept would also allow water to continue to flow into
the unimproved section of Denton Creek. Another benefit of the concept was a study of Denton
Creek. It became quite obvious during our investigation that that had never been a detailed study
of Denton Creek in this area. It has always been assumed that this portion of Denton Creek was
controlled entirely by the backflow of the Elm Fork of the Trinity River. That might be true in a
100-year event, however, during typical rain events, Denton Creek seems to operate independent
of the Elm Fork of the Trinity River.
In reviewing the available opportunities, the City and the Corps of Engineers concentrated on the
floodplain area east of the City of Coppell (referred to as the Weaver tract & the Dallas Gun
Club). There were initial meetings held in the mid to late 1990's. As a result of those meetings,
the City of Coppell was made aware of plans by the City of Carrollton to use and enlarge the area
referred to as the Weaver tract and an area east of that for valley storage for City of Carrollton
projects including Luna Road, S.H. 190/161 connector and some additional reclamation along
I.H. 35E. However, in reviewing what the City of Carrollton was proposing, it was noted that
they had also come to a very similar conclusion concerning the Weaver tract and the area south
of the Weaver tract, i.e., the area would make a very good detention area. However, there
would have to be costly drainage structures built to release the water out of the detention area at a
controlled rate back into the Elm Fork of the Trinity River.
My initial thoughts in contacting Carrollton were based on whether both cities could utilize the
general area as detention, to both cities benefit. If the project is approved by the Corps of
Engineers, then there wouM be federal dollars available to offset at least 35 % of the cost of the
construction of the detention area and the construction of the cosily outflow drainage structures to
allow the water to flow back into the Elm Fork of the Trinity River. At the time that this was
presented, we were informed that Carrollton was quite a bit ahead of our concept plans. Several
years have now past and I am unsure of Carrollton's timetable, but the City of Coppell is still
interested in pursuing whether or not the two cities working together could construct a project to
serve the purposes of both Carrollton's needs for offset of loss of valley storage and the City of
Coppell's need for creation of a detention area. I know that timing could still be an issue,
however, the delay possibly could be easier to handle if there was financial contribution by the
federal government on the construction costs.
At this point, I have been working with this project concept since mid-1995 and have yet to make
any substantial progress on initiating the project.
The City of Coppell needs to make a decision on how to proceed and quite honestly that decision
is somewhat based on our ability to work with Carrollton in this area. Without the ability to
work with you, we are left with no options to pursue a project like this because of the lack of
available land. In my opinion, the next step should be trying to commission the Corps or Nathan
Maier to take your information along with our concept to determine if the two projects can co-
exist in the same area. Either way, after 5 years, the City of Coppell would like to move ahead
or bring to an end this concept of providing greater flood control, erosion control and velocity
control along Denton Creek.
Once you have had the opportunity to review this information, I would appreciate the opportunity
to discuss it with you in greater detail. Thank you for your consideration of this request.
Sincerely,,
Kenneth M. Griffin, P.E.
Director of Engineering/Public Works
CC:
Gene Rice, Corps of Engineers
Jack Tidwell, NCTCOG