Vista Point II-CS040908· ·
·'" · Halff Associates, Inc.
ENGINEERS ARCHITECTS SCIENTISTS PLANNERS SURVEYORS
8616 Northwest Plaza Drive
Dallas, Texas 75225-4292
(214) 346-6200
Fax (214) 361-5573
TO:
FROM:
SUBJECT:
MEMORANDUM
The City of Coppell
Attn: Mr. Keith Marvin P.E.
DATE: 9-08-04
AVO: 22223
Clint Philpott
Emaih Cphilpott @ halff.com
PROJECT: Vista Point II
Storm Drain System
During the design of Vista Point II there were several locations where the existing storm drains were used to
remove the storm water from the site. Provided are additional plans and this letter showing what the impacts were
and how they affect the system, both up stream and down stream. Along State Highway there is a box culvert.
The box culvert has a drainage area that covers Vista Point II and part of the Vistas of Coppell subdivision.
Attached are the design plans for this box culvert. As can be seen, the culvert was designed to handle the runoff
from the site. After the development of Vistas of Coppell, part of the culverts drainage area was changed and now
enters the culvert at Station 39+80. Also on the plans we have added what the flow values will be after Vista Point
II is developed. One flow is the flow directly from Vista Point II. The other flow is the cumulative flow for the box
culvert. The final flow for the box culvert is 383.60cfs. Also attached is the Vistas of Coppell plan showing a 60"
RCP, which connects to the before mentioned box culvert. Shown is the station along the 60' RCP where Vista
Point II needs to tie an 18" RCP into, 2.9cfs. Hydraulic calculations were going to be made to check the effect of
the additional flow on the system. On Vistas of Coppell plan, the 100Yr HGL drops at Sta. 2+55.32. This
calculation seems to be wrong. We have not included any more calculations beyond this point because we are
not sure how they calculated the HGL and our calculations would not give an accurate comparison of the impact
of our additional flow. Again these additional plans were provided so that the impact of the storm drain design
within Vista Point II could be seen.
[] Attachments:
Copies: File
"', Halff Associates, Inc.
ENGINEERS ARCHITECTS SCIENTISTS PLANNERS SURVEYORS
8616 Northwest Plaza Drive
Dallas, Texas 75225-4292
(214) 346-6200
Fax (214) 361-5573
TO:
LETTER OF TRANSMITTAL
The City of Coppell
255 Parkway
Coppell, TX 75019
Attn: Mr. Keith Marvin P.E.
DATE:
AVO:
FROM: B. David Littleton, P.E. PROJECT:
Emaih dlittleton @ halff.com
September 8, 2004
22223
Vista Point II Addition
WE ARE SENDING YOU [] ATTACHED
[] Shop Drawings [] Prints [] Plans
[] Copy of letter [] Change order [] Other:
THESE ARE TRANSMITTED as checked below:
[] For approval [] Approval as submitted
[] For your use [] Approved as noted
[] As requested [] Returned for corrections
[] For review/comment [] Other:
[] Under separate cover via __
[] Drawings
[] Resubmit
[] Submit__
[] Return
the following:
[] Specifications
copies for approval
copies for distribution
corrected prints
ITEMS SENT:
2 Sets of "Grading, Utility, and Drainage" for Vista Point II
1 Strom Drain Letter
3 Storm Drain Plans
COMMENTS:
Keith, here is a plan set for grading, utility, and drainage on the Vista Point II Project (MacArth~r and 121). Please
call me or Clint Philpott if you have any questions. Thanks!
SIGNED: B. David Littleton, P.E.,
COPIES: [] FILE
[] OWNER
[] CONTRACTOR