FS0001-CS010307 CONSULTING ENGINEERS, INC.
March 7, 2001
Mr. Ken Griffen, P.E.
Director of Engineering and Public Works
City of Coppell
P.O. Box 478
Coppell, TX 75019
Re: CLOMR and CDC Application Review Comments
Estates of Denton Creek, Coppell, Texas
NDM Job # 98-10-102
Dear Ken:
Nathan D. Maier Consulting Engineers, Inc. (NDMCE) has reviewed the comments by
Kimley-Hom and Associates, Inc. (KHA), dated December 13, 2000, regarding the
Estates of Denton Creek FEMA CLOMR Request for the 32.09 acre Holmes Tract.
Upon review of the comments by KHA, the following changes to the FEMA CLOMR
request were made:
1. The FIRM Map (Flood Insurance Rate Map) exhibits were replaced with
readable copies in all reports.
2. The water surface elevations were plotted on the topographic maps. There
are no resultant changes due to the project. The narrative was changed to
remove comments which could be confusing.
3. The requested CLOMR is being prepared to follow with a final LOMR for
mapping changes for to the proposed project. A CLOMR-F (CLOMR
based on fill) does not change the FIRM Maps until a future panel update.
We have found that lenders like to have the map change in place for future
home owners.
4. The grading plan for the Holmes Tract is only preliminary. With the
preparation of the construction plans, the fill compaction and erosion
control issues will be addressed.
Two NorthPark ! 8080 Park Lane ] Suite 600 ] Dallas, Texas 75231 ! (214) 739-4741
5. The Holmes Tract site plan is preliminary. Access to the floodplain areas
will be addressed during the platting stage of the project.
6. The FEMA regulatory floodway has been plotted on all topographic
workmaps showing the FEMA floodplain.
7. The maintenance of the flood control structures will be the responsibility
of the community. The CDC application comment was changed to reflect
this comment.
8. The HEC-2 model for Denton Creek was changed to reflect the authorized
release from Grapevine Lake and the bank full conditions. This model
was included to calculate the velocities for future erosion control along the
project reach. The FEMA effective model for Denton Creek starts a
considerable distance upstream of the project. For this reason the FEMA
effective model was not included. Elm Fork elevations control for this
reach of the creek.
9. Digital models for the Elm Fork of the Trinity and Denton Creek have
been included with the reports on a diskette.
10. Preliminary spot elevations were placed on the proposed floodplain
workmap to place the fill a minimum of two feet above the BFE. The
grading plan is preliminary and the final elevations will be determined in
the platting stage of the project.
Upon review of the comments by KHA, the following changes were made to the CDC
application:
1. The detailed site plan, Exhibit 3, was revised to show the CDC cross-
section locations and location of the FEMA Regulatory Floodway. There
are no changes to the floodway due to the proposed development of the
Holmes Tract.
2. The CDC models for the Elm Fork of the Trinity River are based on
ultimate conditions. The FEMA effective models are based on existing
conditions.
3. Exhibit 8A was included to show the proposed swale at a scale of
1"=100'. Exhibit 8B, scale of 1"=300', shows the grid used for valley
storage calculations. The Earthworks program output was included with
the CDC Application as supporting data for the proposed swale.
The above comments and changes made to the previously submitted FEMA CLOMR
Request and CDC Application, dated November 2000 for the Estates of Denton Creek,
are intended to support a revised submittal dated January 2001. All questions and
comments by KHA have been reviewed and clarifying answers and changes have been
provided.
Please feel free to contact me if you have any additional questions or comments regarding
this submittal.
Sincerely,
Nathan D. Maier Consulting Engineers, Inc.
Michael H. Boyd, P.E.
Vice President