ST9902-CS171205
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Registered by the Texas Board of Professional Engineers, Firm No. F-230 Registered by the Texas Board of Professional Land Surveying, Firm No. 100116-00
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surveyors
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www.tnpinc.com
December 4, 2017
Kate Ploetzner, P.E., CFM
Kimley-Horn
13455 Noel Road
Two Galleria Office Tower, Suite 700
Dallas, TX 75240
RE: LOMR for Cottonwood Branch at Sandy Lake Road and Freeport Parkway
TNP# CPL00243-02
Ms. Ploetzner,
This letter response to comments you provided by email on September 20, 2017. Enclosed with this letter, please find a revised
copy of the LOMR for Cottonwood Branch at Sandy Lake Road and Freeport Parkway. For convenience, your comments have
been reproduced in their entirety. Our responses are bulleted below.
1. Previous Comment 20: Provide the effective water surface elevation values in MT-2 Form 2, Section B.1.
Per the provided MT-2 Form, the FEMA effective WSE at XS 12707 does not match the FEMA Flood Insurance Study
(FIS) profile at the location described (357 ft u/s of Freeport Pkwy). Per the FIS profile, this value should be around
elevation 492. Per the “Topographic Workmap – Freeport Existing/FIS Discharges” map, the as-built WSE at XS
12707 is 491.50. This is inconsistent with the proposed/revised WSE denoted on the MT-2 Form 2, Section B.1.
The MT-2 forms have been revised to reflect tie-ins at cross sections 9233 (downstream) and 12957
(upstream). The effective water surface elevations for these sections have been determined through
comparison of the FIS profiles and duplicate effective models. The Proposed elevations are based on
the modeling prepared for the LOMR. The proposed elevations are within the ±0.5 foot threshold as
allowed by FEMA.
2. Revise the FEMA effective WSEs at the tie-in locations to match the Flood Insurance Study profile, and revise the
proposed/revised WSEs to be consistent with the LOMR as-built condition hydraulic modeling output.
See response to Comment 1.
3. Ensure that the Proposed/Revised elevations tie-into the FEMA Effective elevations within 0.5 foot at the downstream
and upstream limits of revision per FEMA requirements.
See response to Comment 1.
4. Ensure the final LOMR submittal to the City of Coppell and FEMA only includes the correct as-built plans.
All necessary sheets have been included. Comment notes have been included on the sheets, as
appropriate, to define the pertinence of the sheet.
5. Ensure that all post-project topographic workmaps show all as-built improvements. It appears that some proposed
contours may be missing on the Sandy Lake workmaps.
Please see the revised workmaps which include an inset depicting the transition grading at the
gabions.
Sincerely,
tnp
teague nall & perkins
Niraj Acharya, P.E., CFM