Grapevine Creek-CS 910731 ALBERT H. HALFF ASSOCIATES, INC.
ENGINEERS · SCIENTISTS · SURVEYORS
m~l DALLAS. ARLINGTON . CHICAGO . FORT WORTH
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2' 4 739-3694
July 31, 1991
AVO 10565
City of Coppell
P.O. Box 478
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Coppell, TX 75019 ~ ;: "' ~;' ~f ?" "' ': '"-
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Attn: [V[r. B~l~a~Cruz
Re: Gateway Business Park
Grapevine Creek
Dear Mr. Cruz:
Please find enclosed for your approval ten (10) sets of the above referenced
construction drawings. Two (2) set of City of Coppell markups dated 7-30-91. The
comments have been addressed as follows:
- Sheet GP-1 Plan View
1. Question size of rock rip rap versus thickness to be installed. The rip rap is
a graded rip rap with the maximum size of rock lO00pounds and the minirnum
size of rock 30 pounds.
Action Taken - Deleted 18" from Note.
2. Size of rock rip rap - The gradation is shown on Sheet GP-i.
3. Detail transition areas to tie to the existing channel to the north and the
transition from Station 5+35 to Station 6+80.
Action Taken - Showed 1' contour lines to illustrate the final channel shape.
4. Grout rock rip rap in place - The rock rip rap gradation was selected based on
the design water velocity and depth in the channel and does not require grout to
remain stable. We feel the non-grouted rip rap will provide a higher roughness
coefficient than the grouted dp rap thus providing a more effective transition
between the concrete surfaces and the grassed channel In addition the non-
grouted rock rip rap provides a flexible lining as opposed to a ridged grouted rock
dp rap again providing a better transition between the grass lined channel and the
concrete structure.
Action Taken - We would respectfully request that non-grouted rock rip rap
be accepted.
ALBERT H. HALFF ASSOCIATES, linC.
ENGINEERS · SCIENTISTS · SURVEYORS
City of Coppell
July 31, 1991
Page 2
5. Detail rock rip rap
Action Taken - Added cross section detail in profile.
- Sheet GP-1 Profile
1. Grout rock rip rap in place.
Action Taken - (See comment 4 for Sheet GP-1 Plan View discussed
previously).
2. Section A-A - match existing ground type.
Action Taken - Moved leader on Note to clarify elevation and location.
3. Rock rip rap 3'?
Action Taken - Revised 3' to 4' in Note to match profile dimensions.
4. 45' transition to existing channel?
Action Taken - See Comment 3 for Sheet GP-1 Plan View discussed
previously.
In addition the 100 year water surface elevation has ben added to the channel profile
and Cross Section A-A.
- Sheet S-1
1. Weep
Action Taken - Added the word weep in parenthesis next to all drain calls on
Sheets S-! through S-3.
2. (General Notes) -
o To be submitted to the City of Coppell.
No action taken on drawings. The Contractor will submit concrete
batch designs to the City of Coppell for approval. All testing results
will be distributed to the City of Coppell for their use.
o This section must also meet all City of Coppell requirements.
Action Taken - Added General Note Number 12.
o Density requirements?
Action Taken - Added General Note Number 13.
In addition General Note Number 7A was added to allow for a two rub surface finish
as an Alternate to the sandblast surface finish.
ALBERT ti. HALFF ASSOCIATES, INC.
ENGINEERS · SCIENTISTS · SURVEYORS
City of Copper
July 31, 1991
Page 3
- Sheet S-2
1. Weep
Action Taken - See Comment 1 for Sheet S-1.
- Sheet S-3
1. Weep
Action Taken - See Comment 1 for Sheet S-1.
2. Seal on weir contraction joint details for weir stem (wall).
Action Taken - A 6" water stop is provided on the upstream side of the wall
to seal the joint against seepage.
We hope that these corrections and explanations of our design will meet with your
approval. We request that these plans be approved as corrected. However, if the grouted
rock rip rap requires further review we would ask that the plans be approved subject to this
issue being resolved prior to placement of the rock rip rap. We would also request a
preconstruction meeting be scheduled at the earliest possible date.
These requests are made in an effort to allow this construction to proceed in a timely
manner through the seasonally dry months of August and September. In addition this
construction should be completed in these months to allow time for the grass lining of the
channel to be established. The Contractor has performed the preparatory work for this
project and is prepared to begin construction on the structure immediately.
Thank you for your time and consideration in this matter and again we respectfully
request prompt action on this project as possible due to the seasonal restraints listed
previously.
Very truly yours,
ALBERT It. HALFF ASfOCIATES, INC.
ratrick L. Acker, P.E.
Attachments
cc: Wayland Threadgill, Catellus
Bill Gibson, Gibson & Associates,,.
Larry Davis, City of Coppell