ST9304-CS 951002I tAI,FF ASSO(r"\TES. INC.
8616 NORTHWEST PLAZA DRIVE · DALLAS TEXAS 75225
214 739-0094 · FAX 214,739-0095
Dallas County Public Works
411 Elm Street
Dallas. Texas 75202
;OUNTY DIRECTOR OF PUBLIC WORKS
October 2, 1995 AVO 14111
RE:
Ms. Jill M. Schneberger, P.E.
Project Engineer
Beltline Road. from Denton Tap Road
in Coppell to MacArthur Boule`"ard
Project 490-403.1/91-829
ENGINEERING
Dear Nls. Schneberger:
Enclosed please find three (3) copies of our revised Preliminar-,- Paving Plag.;Pro~le submittal
tbr the retbrenced project. I have also enclosed the original marked set of plans. We have made the
revisions discussed in our meeting of September 8, 1995 and as outlined in your letter of the same
date. ' -
Additionall>,. we oilier the following discussions and responses regarding comments
contained in the review set of plans and >'our letter: ~ ~
PAVING COMMENTS
We have addressed the City of Coppell's concern regarding the 100-year water surface
elevation and the apparent overtopping of the railroad embankment `'vest of the Grapevine
Creek bridge. Walter Skipwith and I met with Ken Griffin at his office on September 20,
1995. We discussed the City's storm water management study pertbrmed by Halff
,Associates and the hydraulic modeling used to develop the study. The l'00-vear hydraulic
gradeline (HGL) immediately upstream of the proposed bridge is 459.34 feet. The HGL
at the downstream face of the railroad bridge is 459.39 feet. The HGL rises to'
approximately 426 upstream of the railroad bridge. The increase across the railroad bridge
is due to the undersized bridge and the resultant inadequate flow area. The storm water
management stud,,- does show in existing conditions base flood elevation (BFE) line
crossing the railroad embankment (Exhibit 3-2). This line would be mor appropriately
drawn along the northern side of the railroad embankment. We have compared the Citv's
topographic sun'ev and our field surveys vdth the hydraulic models and the storm water
management study. All parties agreed that flood waters overtopping the embankment vdll
STRUCTURAL
Dallas County Public Works
October 2.1995
Page 3
drop to the HGL at the downstream thce of the railroa4 bridge (459.39 feet). Therefore.
the 100-year water surface elevation shown on the drav,'ings is correct and. is slightly
above the calculated elevation. In conclusion. Mr. Griffin accepted our explanation an
agreed that the paving profiles could remain with respect to the 100-year v,'ater surface
elevation.
The proposed benchmarks have been relocated on the project layout sheets. The final
locations will be determined in the field and reflected on the appropriate paving plan.
Complete. =: .,'
Propert>' owners. addresses and file numbers are currently being determined and will be
shown on the paving plans and right-of-way documents.
5. See No. 2 above.
6. Complete.
7.- 10. Complete.
11.
12.
13.-15.
Conduit sleeves will be added during the final design phase of fhe project.
Drainage and slope easement geometD- will be established during the drainage system
design. Upon completion. the>' will be shown on the paving sheets.
Complete
16.
The right-of-way will dimensioned on the right-of-way plans.
17.-22. Complete.
Dallas County Public Works
October 2, 1995
Page 3
DRAINAGE CO~IMENTS
23. The outfall has been relocated.
24.
25.-26.
27.
28.-31.
32.
The drainage area map has been revised to correspond to the actual topography adjacent
to the roadxvay. The result is a reduction in gutter flows. ---
Complete.
The remote drainage areas will be picked up in Y-inlets located adjacent to the roadway.
Complete.
The note indicates that flows from the areas at the southwest comer of Beltline Road and
MacArthur Boulevard are limited by the capacit3,' of the existing drainage system extending
east of MacArthur Boulevard. The remaining flows in this area will need to be directed
to the Grapevine Creek to the south.
CROSS-SECTIONS
We have enclosed the revised cross-sections generated with the lowering of Beltline Road
and Moore Road.
Dallas Count',' Public W'orks
October 2, 1995
Page 4
During recent conversations with Ken Griffin and yourself. additional comments were
made regarding the tie-in to Northlake Drive. Additional field work will be required to determine
existing pavement elevations north of the entrance to Riverside Church. Once this field work is
complete, we anticipate extending the tie-in point to the north. reducing the proposed pavement
grades and incorporating a vertical curve.
Please call if you have an3' questions or require additional intbrmation.
TJK/kdh
Enclosure
Yours \cry truly.
HALFF ASSOCIATES, INC.
Thomas J. Knicker, P.E.
Project Engineer
'AVO', 14111 .WPxLT 10-02 J MS