Connell Skaggs-CS 870415GINN, INC.
RECEIVED APR 1
CONSULTING ENGINEERS
April 15, 1987
Ms. Shohre Daneshmand
P.O. Box 478
Coppell, TX 75019
Re:
Connell Skaggs Addition Lots 1, 2, & 3
NW Corner Denton Tap/Sandy Lake
Dear Ms. Daneshmand:
Pursuant to our recent telephone conversations, latest submittals
from the engineers, and your stated concerns regarding the above
referenced subject, we offer the following comments for you
consideration.
1. Since we were not involved in discussions, decisions,
agreements, etc., between the "preliminary" submittal and the
present "final" submittals, we are at a disadvantage. Any
written documentation between the City and owners, the City
Engineer (at that time, Mr. Ed Powell), and the engineers for the
project (Powell and Powell), would provide helpful insight as to
decisions made and/or accepted.
2. Because the property upstream of the Connell tract is
presently being submitted for approval and parts of Lot 3 are
being developed with drives and parking, we would suggest
advising the developers to provide the design and construction of
the proper drainage facilities to adequately convey all runoff
from the site and that which the present ditch handles plus
upstream development.
3. Since Lot 3 is included in this "final" plat submittal, the
agreement between Conneii and city stipulates =hat "... a letter
of credit be provided or monies escrowed for construction of the
box culvert from Sandy Lake Road to Willow Lane, at some later
time, ~uch time to be determined at the ~ole discretion of the
city Council, based upon recommendation of the City Engineer."
It is our recommendation that the box culvert be constructed at
this point in time.
4. If, due to previous agreements or commitments, Connell does
not have to construct the box culvert at this time, we suggest
that the existing ditch on the west end of the Connell tract be
improved, as required, to adequately handle the anticipated
flows. Allowing the open channel is in direct conflict with the
subdivision ordinance, which states no open channels allowed;
and, will have to have a variance approved.
17103 Preston Road · Suite 100 · LB 118 · Dallas, Texas 75248 · Phone 214/248-4900
· 5. The plat should designate an adequate drainage easement for
construction of the box culvert and should be located entirely on
the Connell tract. On the 20' drainage and utility easement on
the Shadydale Acres tract, it would be difficult to construct a
box culvert due to encumbrances, 48" oaks throughout, and the
mere fact that just because a plat indicates a drainage easement
does not mean that adjoining lands have no obligation to provide
drainage upon their own site, where a natural existing drainage
flow occurs.
6. The screening wall should be constructed at this point in
time and not at a later date. This again is part of Coppell
ordinances and any deviation will have to have a variance
requested. The entire tract should be considered as one,
regarding screening. Whether the buildings are constructed on
Lots 1, 2, or 3 should not have any affect on the visual
screening of the residents of Shadydale Acres tract.
7. Regarding "sheet" flow of drainage across the site from east
to west, with no provisions for detention or collection, it is
our opinion that during a 100-year storm event (Q = 72 c.f.s.,
d = .68', V = 4.4 f.p.s.) or even the 10-year storm event (Q = 49
c.f.s., d = .59', V = 4 f.p.s.), the runoff could conceivably
present a problem to motorists and pedestrians using the parking
area on this site regarding safety.
8. We acknowledge that the design storm event should pass
quickly; and, allowing the runoff to be conveyed in a wide path
vs. concentrated discharge points would cause less erosion. But,
if the box culvert were constructed and a storm sewer collection
system provided, it would alleviate some of the potential fears
and problems that may occur.
9. If the engineers are determined to sheet flow across the
site, then the City should stand firm in its desire to have the
box culverts constructed at this time. Also, the maximum
allowable "sheet flow" we should accept should be 20 c.f.s. When
the flow exceeds this 20 c.f.s., it will have to be collected and
transported by other means, i.e. underground piping.
if you have any additional concerns, please contact us.
Sincerely,
Gabe Favre
/ss
cc: Alan Ratliff
Wayne Ginn