ST9301-CS 981001COPPELL, TEXAS 75019
P.O. Box 478
Coppell, Texas 75019
972-462-O022
October 1, 1998
John L. Mears, P.E., Project Engineer
Dallas County
411 Elm Street
Dallas, Texas 75202
RE: Sandy Lake Road Project Dallas Project//91-830 / Coppell Project//ST 93-01
Dear Mr. Mears:
I have received and reviewed the plans submitted for the construction of Sandy Lake Road from
MacArthur Blvd. to Kimbel Court and have the following comments to offer:
1. The typical roadway width is 27 foot back of curb to back of curb, not 28 foot.
2. The City's Sandy Lake Road plans show that the existing 16" water line needs to be lowered.
The 16" water line should be shown in your profile to insure that there are no conflicts with
the proposed improvements. There is also a City of Coppell proposed 30" water line that
should be shown on your plans to insure that it does not conflict with the proposed
improvements.
3. The transition to the free right turn lane is shown at approximately Sta. 17 +42 on the City of
Coppell Sandy Lake Road plato. In essence, the transition should begin in your section not
in the City of Coppell section. Our roadway eastbound as we approach this section of Sandy
Lake is only 27 foot back to back, not 40 foot back to back as shown.
4. The top of curb elevations as shown do not match the top of Curb elevations in the cross
sections.
5. The approach grade on the City of Coppell Sandy Lake portion is 3.54% and the beginning
grade on this section is 3.89 %. Is that an instantaneous change or an error in the grade?
6. The note at Sta. 17+50, that states "begin brick pavers" should be removed, the pavers
should only be at the nose of the median.
7. The intersection at MacArthur Blvd. and Sandy Lake Road should be a full brick paver
intersection, not a banded intersection as shown.
8. The radius at the intersection should be 40 foot, not 50 foot as shown.
9. The traffic signal poles and controller location should be shown on the plan view to insure
that they do not conflict with any other improvements.
10. The left turn lane for Kimbel Court ends approximately 35 feet away from Kimhel Court.
Why? It appears that it should be lengthened approximately 25 feet.
11. The 50 foot elevation should be provided at Sta. 22+50 and 23+50.
12. The transition from Sra. 24+ 11.82 to approximately 25+40 shows what appears to be a curb
line. Is it in fact an asphalt curb, striping or buttons?
13. The contract between Sverdrup and the City of Coppell states that the deliverables for the
Sandy Lake sewer design is plan and profile drawings and a parcel site plan at the Sandy
Lake Road lift station. The site plan should show the sewer line interface and connection
requirements at the pump station. The parcel site plan and the profile are not provided for
the proposed 21' sewer line. That information should be provided.
14. Please comment as to why the removal of the section of MacArthur Blvd. north of Sandy
Lake starts at Sta. 3+05 and 3+60. Is it possible that both of those could start at th{
transitions to the inlets? Also, with a steeper grade on both sections, i.e. around
approximately 2% as opposed to 1.6%, it appears that trees and the existing brick wall could
be saved. They also might be salvageable under the existing design when your cross sections
are corrected. It appears that the cross section at Sta. 3 +60 on MacArthur is incorrect.
15. No cross sections were provided for the section of MacArthur south of Sandy Lake from Sta.
6+06 to approximately 8+50. Is there a grade difference that would necessitate the removal
of trees or will some type of retaining wall be needed?
16. The drive approach at Sta. 17+46 appears to be steeper than necessary. It is quite possible
that the removal and replacement may need to extend to Sta. 0+87 as opposed to 0+74.
17. The driveway located at Sta. 24+37 appears to be steep. It is quite possible that the
replacement may need to extend to the proposed right-of-way line.
18. The cross section shown at Sta. 3+40 on MacArthur probably should be 3+90.
19. The cross section shown at Sta. 4+15 on Kimbel Court doesn't match the profile view.
Several numbers are given as 454.36, however, the actual elevation appears to be closer to
447.4.
20. The drainage pipes discharging into the channel on the south side of Sandy Lake should
discharge more with the direction of flow i.e., approximately a 45° discharge if possible as
opposed to a 90° discharge.
21. The hydraulic grade line should be shown on all storm drain system profiled, along with the
pertinent hydraulic information.
22. Details for the street name blade should be provided.
23. Thc signal heads on the traffic lights should align with thc lancs. 3~hcrc should also bca light
provided for each lane.
24. Are advance detectors going to be provided for the traffic lights on north and south bound
MacArthur Blvd? It appears that they may be needed.
25. The opticom is not to be provided by the City of Coppell. It is part of the signal installation
and should be provided as part of an overall turnkey signal installation by the contractor.
26. When additional traffic lights are added it is quite possible that the mast arms as proposed
may be too short. Also, cable and signal heads will need to be recalculated.
27. Typically any mast arm over 36 feet requires a 36" diameter drill shaft. This is even 'shown
on the TxDOT Pole Foundation sheet included with these plans.
28. It appears that the ground boxes A & C do not match what's shown on the diagram.
29. Pull boxes and the controller should be relocated outside the limits of the brick pavers.
30. The first loop detector for westbound Sandy Lake should be relocated west of Kimbel Court
so turning movements onto Kimbel Court do not activate the MacArthur traffic light.
31. Please be advised that the City of Coppell does not use the standard TxDOT traffic signal
structure. The City of Coppell mast arms should be used.
32. It appears that most of the cross sections as provided do not match the profiles. The top of
curb elevations given on the profiles are different than the top of curb elevations given on the
cross sections.
33. It appears that at several locations the transition f~om the sidewalk to the existing channel on
the south side of Sandy Lake Road is approximately 2 to 1. This is too steep.
34. It appears that some of the transitions along Kimbel Court are approximately 3 to 1 from the
back of curb to the natural ground. Please try to maintain a 4 to 1 slope. ,
35. The elevation for the cross section at Sta. 3+60 is incorrect. The cross section as shown
shows you are cutting approximately 1~/i foot out of the median of MacArthur north of Sandy
Lake which would eliminate all of the trees, the brick sign, etc. However, upon
investigation, it appears that the top of curb as shown on your cross section is incorrect. The
profile shows the top of curb as 455.8 while you are showing the top of curb elevation at
454.12. Please reevaluate and correct this.
36. Please provide cross sections from Sta. 6+06 to Sta. 8+50 along MacArthur Blvd. south of
Sandy Lake Road.
Sincerely,
Director of Engineering and Public Works
fil¢/kgriffin/s193-O 1/plnrvw98 .doc