Pecan Hollow Add-CS 900504dP Jerry Parch& Consulting Engineers
May 4, 1990
Ms. Mary Hicks
ABQ Development Corporation
P O box 25625
Albuquerque, NM 87125
505/242-3330
RE: JP No. 88009; Request for Drainage Easements by
Pecan Hollow; Coppell, Texas
Dear Mary:
On May 3, 1990, Mr. Doyle Cameron of Pecan Hollow Joint Venture
provided computer models of two alternatives for improvements to
the existing drainage channel which lies on the north boundary of
the Pecan Hollow development and the southerly boundary of the
Parks of Coppell. The channel improvements have been designed to
offset flood conveyance area that will be lost due to proposed
filling in Pecan Hollow.
Included with the channel improvement models were the following:
A drawing of three cross sections through the Pecan Hollow
property showing proposed channel improvements.
An exhibit showing a proposed adjustment in the alignment of
proposed Beechwood Lane in Pecan Hollow to include a 250
foot centerline radius to the southwest near A~Q's property
llne.
The alternative models of the proposed channel improvements to be
constructed by Pecan Hollow are described below.
The channel bottom and north sideslope on ABQ property are
excavated to the levels shown on the Heartz Road channel
improvement plans. The channel bottom is extended south to
the property line. A four to one excavation and fill
channel sideslope on Pecan Hollow property is included in
the model with the toe of the slope on the property line.
The top of this slope is near the 100-year flood elevation.
The channel bottom and north sideslope on ABQ property are
similar to the model described in (1) above. The channel
bottom is extended approximately 15 feet into Pecan Hollow.
At this point a vertical wall is modelled having a top
elevation at the 100-year flood elevation.
320 ~/estway Place, Suite 501 · Arlington, Texas 76018, Metro (81 ?) 46A2418 · (8171 465~0259
Ms. Mary Hicks May 4, 1990
JP No. 88009 Page 2 of 3
Our review indicates that either propoeed channel model yields
water surface levels during the 100-year flood very similar to
levels determined with channel improvements proposed in
conjunction with construction of Meartz Road. Therefore either
channel improvement scheme will comply with our request that
proposed filling not raise flood levels above levels computed for
deaign of Heartz Road drainage facilities.
A copy of Mr. Doyle's letter transmitting the aforementioned
computer models to us is enclosed. We had several questions
regarding the proposals presented in Mr. Doyle's letter. I have
discussed these in a conversation with the project engineer, Mr.
Bill Anderson, P.E. of Dan Dowdey & Associates. Our concerns and
Mr. Anderson's responses are presented below.
What channel improvements will actuall~ be constructed b~
developers of Pecan Hollow?
Mr. Anderson stated that construction plans for Pecan Hollow
will include excavation of the drainage channel on ABQ and
Pecan Hollow property as shown in the sections included in
the computer model. Filling of the south bank of the
channel above the 100-year flood elevation will be at the
option of the builder/homeowner, however, this fill must not
encroach further north than an upward extension of the
excavated sideslope on the south bank in Pecan Hollow.
The builder/homeowner may construct a vertical wall
approximately 15 feet south of the property line. However,
if he elects to do this, he must excavate the area north of
the proposed wall to the property line in accordance with
the grades included in the computer model for this
alternative.
2. The storm sewer outfalls from Pecan Hollow should include
headwalls constructed to conform to the excavated 4:1
sideslope.
Mr. Anderson agreed to design either
headwalls conforming to the sldeslope
the south channel bank.
parallel or sloping
to be constructed on
What regulations will be implemented to prevent homeowners
from filling in or constructing fences within conveyance
areas in Pecan Hollow?
I restated my request that a channel easement in the rear of
lota backing onto the drainage channel be dedicated to the
City of Coppell. This drainage easement should have
sufficient width to include the 100-year flood plain area.
Ms. Mary Hicks May 4, 1990
JP No. 88009 Page 3 of 3
Mr. Anderson stated that two instruments are being prepared
to require homeowner maintenance of the 100-year flood area
on their lots and prevent encroachments beyond design
limits: l) A Private Drainage Easement to be placed on the
plat covering the channel area and 2) requirements to be
included in the Homeowners Association documents. Whether
these regulations will be enforced by the Homeowners
Association is unknown at this time.
Technical aspects of the proposed channel improvements
demonstrated by computer models and cross sections submitted to
us by Mr. Cameron on May 3, 1990, in conjunction with developer
commitments stated by Mr. Anderson regarding channel and headwall
construction to be performed by the developer, comply with our
engineering requirements for recommending dedication of requested
drainage easements on ABQ property.
By copy of this letter, we request that Dan Dowdey & Associates
provide us two copies of the Final Plat, as revised, two copies
of the channel cross sections revised per discussion between
myself and Mr. Anderson, and a copy of construction plans for
work to be performed in the channel for our review.
By copy of this letter to your attorney, Mr. Jim Schell, we
request that he review this matter and consider legal means by
which the cross sectional area of the channel, as agreed to by
Pecan Hollow and ABQ, can be preserved. This is typically
accomplished by a drainage easement dedicated to the City,
however, Pecan Hollow has expressed reluctance to dedicate a
drainage easement and has reported that the City will not accept
a drainage easement. You may also wish to require verification
of the channel cross section following construction.
If you have any questions, please call.
Sincer~/~
~y Parche',
P.E.
JP:ch
Enclosure: Letter from Mr. Doyle Cameron dated May 2, 1990
cc: Mr. Jim Schell/Law, Snakard & Gambill
Mr. Bill Anderson, P.E./Dan Dowdey & Associates