Lakewood A-CS 920925September 25, 1992
Mr. Ken Griffin, P.E.
City Engineer
City of Coppell, Engineering Dept.
255 Parkway Boulevard
Coppell, Texas 75019
Re: Lakewood Estates
Coppell, Texas
91073-0
Dear Ken:
We have revised the Final Plat and Engineering Plans for the
referenced addition consistent with your comments found in your letter
dated September 1, 1992, and per the returned markups. Please find
below an itemized listing of those changes made to these plans as
requested by you and your staff. The changes are as follows:
1) All Sanitary Sewer curves have been changed from 750 foot
radii to 850 foot radii. It was my understanding that staff
has just recently approved 750 foot radii for sewer lines on
other projects (Chaucer Estates and others).
2) I have talked with Mr. Glidewell regarding the location of
the Fire Hydrant within the cul-de-sac of Tealwood Drive
(Southeast corner of this development). He has informed me
that the Fire Department prefers not to have the hydrant at
the very end of the cul-de-sac, but rather have them located
as shown on the Water Plan. It is our opinion that a fire
hydrant at the end of a dead end water line is preferred as
it can be used as a "blowoff valve".
3.1) All cleanouts have been replaced with manholes as requested
in your letter. However, we have used cleanouts in the past
on projects within the City of Coppell. It is our opinion
that a cleanout at the end of a sewer line with less than 10
lots being served is an appropriate design. Also, according
to your standard details, cleanouts are still allowed.
3.2) The existing 27-inch sewer line running North/South through
tract "B" of this development has been relocated out from
under building pad areas. No changes have been made to our
drawings until a resolution has been made by the Coppell MUD
#1 Board. We are also waiting for feedback from the City
Attorney regarding waiving the sewer impact fee in the
amount equal to the additional work being requested.
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Page 2
Lakewood Estates
September 25, 1992
4) Ail top of manhole elevations have been provided on sheet 5.
An additional manhole has been added to line "S-4", and
concrete encasements have been provided for those sewer
lines where utility crossings occur.
5) It is our opinion that relocating that position of the sewer
line which is not directly affected by this project is a CIP
type project and that typically sewer impact fees are
collected for such major trunk improvements.
6) The capacity of the street section measuring 28 feet from
back of curb to .back of curb has been revised per your
request.
7) All starting hydraulic grades are the 100-year water surface
in Denton Creek as shown on the floodplain exhibit located
on the Drainage Area Map (reproduced for the Albert Halff
study). This is a very conservative approach to calculating
the hydraulic grade line as a peak flood on Denton Creek
will not occur during the peak flood within the Lakewood
Estates subdivision.
8) A letter of permission is being obtained from the property
owner at the Southeast corner of this tract. A letter of
permission will not be needed for the lake outfall as the
property they discharge across is public property.
9) An erosion control plan has been provided per your request.
10) The proposed concrete channel has been designed and has been
included with this set of plans.
11) The maintenance of the lake area will be the responsibility
of the developer for a period of one year. After that time
has expired, these improvements will become the
responsibility of the Home Owners Association.
12) The detail of the proposed lake edge treatment plan has
already been shown on this exhibit. This wall is used
frequently in situations like this according to the
manufacturer. Please find attached a copy of the products
design parameters. The top of the wall will be at an
elevation equal to the 100-year water surface elevation.
The top of the wall around the existing lake within the
Lakes of Coppell development were also designed such that
the top of the wall was at the 100-year water surface
elevation. This requirement was also made by the Home
Owners Association.
13) All streets which intersect with MacArthur Boulevard or
Village Parkway will be constructed with 30 foot radii curb
returns.
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Lakewood Estates
September 25, 1992
14) Ail alley curb returns have been changed from 9.5 foot radii
to 15 foot radii as shown on your recently revised standard
details.
15) We have made several attempts to contact the School District
to ask them to revise their grading plan along the South
line of tract "A" of this addition. It is our opinion that
the only way for the streets to "make grade" within our
subdivision (hydraulically) is to raise the existing grade
adjacent to the school tract. It is our opinion that a
storm sewer could not be extended to this area because the
hydraulic gradient would be above the throat of a "Y" inlet
no matter what size pipe you used. This is a result of the
extreme flat grade between the existing lake and school
tract. We have coordinated with the schools on-site
contractors and have provided fill within their tract so
that adequate surface drainage can be provided. I am a
little bit surprised that the City was not willing to assist
us with this issue.
16) The grading plan proposed for this development has been
designed per FHA design criteria. All side yard swales will
have a minimum slope of 1.0 percent.
17) All overflow swales have been revised per your request and
have been shown on the Lot Grading Plan. All side yard
swales between lots where street sags are located will
discharge overland to the existing floodplain or lake system
adjacent to this development.
Other issues regarding this development have also been identified
subsequent to your review. These issues were raised as a result of
our in-house review as well as by the Geotechnical Engineer retained
by this developer. These issues are as follows:
18) Abandonment of the existing 27-inch sewer line will be done
by capping the upstream and downstream ends and filling the
sewer pipe with a 2,000 psi concrete slurry. A letter has
been written by an expert in this field regarding this
issue.
19) During the mass excavation of this site, the contractor
noticed large limestone boulders in the far southeast corner
of the site. The Geotechnical Engineer is recommending that
all street subgrades be 8 inches instead of 6 inches and
limed with 36 lbs/SY of lime. This was recommended in a
letter from the Geotechnical Engineer, of which a copy has
been attached.
f 20) In order to construct the alley along the north line of the
City's station, a portion of the fence surrounding the
pump
site will need to be removed and replaced. This will need
to be done in order that the proposed alley grade not fall
below 0.5 percent. This will require as much as 2 feet of
fill along the existing fence line. If there are concerns
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Lakewood Estates
September 25, 1992
by the City regarding the removal and replacement of this
fence, please let me know at your earliest convenience.
If there are any additional comments regarding this set of plans,
please feel free to call me or Craig Smiley at your earliest
convenience. The developer wishes to begin work within tract "A" as
soon as possible. Would it be possible to release this section of the
development until the relocation of the 27-inch sewer line issue is
resolved?
Sincerely,
Kevin R. Kendrick, P.E.
Project Manager · Associate
Enclosures
cc: Waymon Levell / L.C. Estates, Ltd.
Keith Jackson, P.E. / Cook-Jackson, Inc.
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