Freeport NIP(7.6)-CS000411 04-1~-00~07: 12 RCVD
April 11, 2000
PK No.: 20§2-00.061
Mr. Michael Martin, P.E.
CITY OF COPPELL
255 Parkway Boulevard
Coppell, Texas 75019
~1~ Re: 140 Acres
Coppell, Texas
Dear Mr. Martin:
Transmitted herewith, via courier service delivery, please find enclosed the following
prints for your approval:
No. Date Description
1 02/15/00 ALTA/ACSM Land Title Survey
1 04/11/00 Storm Water Design Criteria Letter
If the enclosures are not as noted above, please contact this office immediately.
If you have any questions regarding the enclosed items or need any additional
information, please call me at your convenience.
Sincerely,
C. Jack Evans
CJE/Ib
2052-27
eric.
cc: Paul Brown - Duke-Weeks
April 11, 2000
PK No.: 2052-00.061
Mr. Michael A. Martin, P.E.
CITY OF COPPELL
255 Parkway Boulevard
Coppell, Texas 75019
Re: 140 ACRE SITE
Coppell, Texas
Dear Mike:
As you are aware, our client, Duke-Weeks, is anticipating developing a 140 acre
commercial site located at the northwest comer of Coppell Road and Bethel Road. It is
our understanding that due to existing facilities downstream of the site, that proposed
drainage discharge from the site will not be allowed to increase from existing discharges.
To make this possible, we are proposing on-site storm water detention.
Based on discussions with your office, we understand the following criteria will be
implemented during the design of our on-site drainage system:
1) Existing drainage shall be calculated utilizing a runoff coefficient of 0.3 and a
travel time based on overland flow slopes of approximately 0.3%.
2) Proposed discharges will be based on a C-factor of 0.9 and City of Coppell
drainage criteria.
3) The site to the west which drains across our site will be detained on that site to
discharge at existing rates.
4) Detention requirements and outflow structures will be calculated-based on 2, 5,
and 100-year storm events.
5) Pipe flows will be routed using a hydrograph method designed procedure.
6) Detention will be allowed in non-required parking or truck loading areas with the
following criteria:
(' · maximum depth is 1foot
~ · maximum depth in a fire lane is 4 inches
5j, v ~.L~lf · maximum depth at emergency exits is 1 inch with a 1 inch maximum depth
,,.. "walkway" to non-detention areas on 200-foot intervals
This outlines our general understanding of the City of Coppell's design requirements for
on-site detention for the 140 acre tract. Obviously, as the design of these improvements
proceed, more detailed deSign requirements will need to be established in order to
guarantee that discharge from the site is maintained at existing rates.
Mr. Michael A. Martin, P.E.
April 11, 2000
Page 2
If you have any questions of need any additional information, please do not hesitate to call.
erely,
ch, Jr., P.E.
JAK/as
2052-25
cc: Paul Brown - Duke-Weeks Corporation
Zach Jekot - Corgan Associates