Shadowridge P1-3-CS 910709The City With A Beautiful Future
July 9, 1991
Mr. Robert Delvo
201 Magnolia Court
Coppell, TX 75019
Re: Open Drainage Channel
,0. Box 478
/..~'~ ? ~:,? Coppell, Texas 75019
~'~ <~.__~-.462 - 0022
Dear Mr. Delvo:
This letter is in response to your letter dated April 15, 1991, regarding
the open channel north of your property. At first, I wish to extend my
apologies to you for such an unexpected delay in responding. Please note
that I have reviewed and analized all of your comments very carefully, and
have also coordinated with other City staff members concerning this
matter. The following comments are provided based on my findings:
1) Closed Storm System:
The open channel was originally designed and constructed as
part of Shadow Ridge Estates Development, and was intended to
accommodate ultimate off-site drainage, including portions of
Devonshire Addition.
Due to downzoning from duplex to single family, the calculated
amount of ultimate drainage outfall from Devonshire into the
open channel has been reduced.
The option of an underground storm pipe does exist, however, the
probable estimated cost of this alternative is $96,000.
2)
Open Channel/High Velocity/Steep Slope:
Prior to any work commenced by G. Development the existing
open channel with the flume may not have functioned as
intended. However, this channel is currently being
reconstructed and improved by G. Development. The cost for
such improvement is estimated at $15,000 - $20,000.
The channel's side slope is proposed not to exceed 3 to 1
(33%), which is generally considered acceptable and mowable.
The channel will also be hydromulched as an erosion control
measure, where applicable.
Letter to Mr. Delvo
July 9, 1991
Page 2
The velocity of the flow in the channel, according to the
construction plans, is 2.6 fps (±), which is considered to be
a low and non-erodable velocity.
In order to minimize steeper slopes, and thereby to minimize
erosion, G. Development has proposed to enclose the eastern end
of the open channel by placing an underground 42" RCP.
3) Regular Channel Maintenance:
4)
The concrete lined portions of the channel, such as storm
sewer pipe outfall, will be maintained by the Street Division
of Public Works. However, as you know, and as a general
policy, the responsibility of maintaining the grassed channel
remains with each homeowner and/or Homeowner's Association.
Again, in staff's opinion, this open channel will function
more efficiently as a result of improvements presently
undertaken by G. Development.
Staff recommends that some type of Homeowner's Association be
created to maintain this channel on a regular basis.
Fence Installation by G. Development and Coppell ISD:
According to the approved final plat, for Devonshire Addition
and under special conditions, it is stated that "Homeowners
adjacent to the south boundary of the existing drainage channel
may have their fences extended along the south side of the
existing drainage easement, if they desire to enter into an
agreement with G. Development ..."
It is our understanding that the Coppell 1SD will install
fences along its northern property line. This may eliminate
any potential access from the school onto the drainage easement.
Installation of a fence along the actual property line between
Shadow Ridge Estates and Devonshire is not desirable, since it
will create an isolated area with minimum access to maintain
utilities within this easement. It is my understanding that
the Devonshire Zoning Case did not require a fence to be
constructed at this location.
Letter to Mr. Delvo
July 9, 1991
Page 3
5) Underground Pipe Requested:
As noted earlier, if affected homeowners wish to pursue
enclosing this drainage system, their active participation is
recommended. An open drainage channel is, in general, an
acceptable methodof handling drainage. There was no specific
requirement for G. Development to enclose this system, however,
they have attempted to improve the condition considerably, even
though the channel was outside of their property.
If you have any questions and/or wish to discuss referenced items in more
detail, please call me at 393-1016.
Sincerely, ~ /
Actinf; City Engineer
MSD/bd
cc:
Alan D. Ratliff, City Manager
Gary L. Sieb, Director of Planning and Community serVices
Steve Goram, Director Of Public Works
Larry Davis, Construction Inspector
DELVO