Gateway BP(1.4)-CS010924September 24, 2001
Marty Paris, P.E.
Halff Associates
8616 NW Plaza Dr
Dallas, TX 75225
T H £ · (:: I T Y · 0 F
COFFELL
FILE
Gateway Business Park, Lot 1R
Haverty's Drainage Improvements & Exchange Circle Reconstruction
Construction Plan Review Comments
Dear Marry:
I have reviewed your revised plans as submitted and have several areas of concern:
Sheet DA-1
1. Please provide detailed calculations showing the
calculations associated with line 'A' and line 'B'.
concentration is 10 minutes.
beginning time for your drainage
Typically the beginning time of
Sheet STM-I
1. I am concerned about constructing a drainage system and then having 14 field connections to
that system in the future. Is it possible to install all or some of the stub-outs now?
2. Are you proposing to build the parking lot and buildings as shown? If so you should provide
the stub-outs for the drainage connections.
3. The abandoned portion of the 60" RCP and the 33" RCP near station 19+00 on line 'A'
should be removed, not plugged and left in the ground.
4. You're proposing to tie into an existing 12" stub-out for an 8" sanitary sewer. Please be
advised that the 12" stub-out is a clay pipe installed in 1981. It is doubtful that it is in an
acceptable condition, therefore you should remove the existing 12" V.C.P. sanitary sewer and
install your proposed 8" directly to the existing manhole in Freeport. With some slight
modification of the proposed 8" sanitary sewer, it is possible you could eliminate the need for
the two onsite manholes. There would still need to be some repair work to the existing
manhole in Freeport caused by the removal of the existing 12" V.C.P. sanitary sewer stub-
out.
5. A headwall should be provided on the proposed 6x5 RCB.
Sheet STM-2
1. The hydraulic grade line needs to be lowered from approximately station 9+73 to station
20+68. The hydraulic grade line as proposed in that location is at the existing ground. I am
unsure whether the ground will be cut or filled for future paving operations, however, it is not
good engineering practice to design the hydraulic grade line at or above the proposed ground.
Also, the hydraulic grade line at that elevation more than likely will cause water to come out
of the proposed mar&ole at station 16+86. Lowering the hydraulic grade line will more than
likely necessitate larger pipe sizes.
Sheet STM-3
1. Please provide the slope of the existing 60" RCP in Freeport which you are connecting line
'B' to.
I recommend that you schedule a time to meet with this office to discuss these comments. If you
choose not to meet, then please make the appropriate revisions and return these marked-up
plans and two sets of revised plans to the City for review. If you have any questions or want to
schedule a meeting, please contact me at (972) 304-3686.
Sincerely,
Kenneth M. Griffin, P.E.
Director of Engineering & Public Works