Villages C P3&4-AG 920428 (2)Page Z of Agenda Request Form (Discussion of a drainage system in DeForest Drive)
you have a headwall that allows water to only enter the system at one point. If
the water overtops the street downstream of that headwall, then tho water does
not get into the system. With the open bar ditch, no matter where the water
overtops the street, it still gets into the bar ditch and is conveyed eastward
to the creek.
My recommendation would be that the City Council allow the developer to construct
the bar ditch with a gabion wall on the adjacent property in lieu of the
.underground drainage system. However, I would request that the developer also
be required to hydromulch or sod the bar ditch area initially to reduce any
potential erosion. The plans as submitted are being routed to Public Works for
any comments that they may have concerning the bar ditch design.
Staff wall be available to answer any questions at the Council meeting.
~'ORKSHOP ONLY
AGENDA REQUEST FORM
ITEM CAPTION;
Discussion of a drainage system in DeForest Drive adjacent to Villages of Coppell
Phase III-B.
SUBMITTED BY: ~-'e STAFF REP.: Kenneth M. Griffin, P.E.
) City Engineer
OTHER REP.:
EVALUATION OF ITEM; DATE: 4-~0-9Z
At the March 10, 1992 City Council meeting, the drainage system along Deforest
Road adjacent to the Villages of Coppell Phase III-B subdivision was discussed.
The council is aware that there is an ongoing drainage problem in this general
area. The developers of the subdivision are attempting to install a systemthat
will convey water to Denton Creek because they are filling in the property south
of Deforest Drive. However, the system proposed in the construction plans will
not function hydraulically and the preliminary cost estimate for the system is
approximately $80,000. The engineer, Don Tipton with Don Tipton Engineers, met
with me requesting that the City allow some other drainage design in lieu of an
underground drainage system. This was what was presented at the City Council
meeting and authorization was granted to work with the developer and the
developer's engineer to come up with a different solution.
On April 10, 1992, a meeting was held with the developer and developer's engineer
concerning this issue. At that meeting, a drainage design that incorporated bar
ditches adjacent to Deforest Road was presented. However, there was some concern
about the maintenance of the facility in the fact that a portion of the bar ditch
was shown on the adjacent properties. Subsequent to that meeting, an alternate
plan was submitted to my office that showed the bar ditch contained entirely
within the right-of-way of Deforest Road and a gabion wall constructed on the
property adjacent to the bar ditch. The gabion wall is necessary to obtain an
acceptable side slope in the drainage ditch. The bar ditch design as now
submitted, provides the same drainage carrying capacity as the proposed storm
drainage system. One of the advantages of the bar ditch over the storm drainage
system is the way the water enters the system. With the storm drainage system,
BUDGET AMT. AMT. ESTrM.~TED
.%MT +/- BUDGET FINANCIAL REVIEW BY
COMMENTS:
LEGAL REVIEW BY: REVIEWED BY CM:
AG~uNDA ~QUF~T FORM REVISED L'gl