St Joseph-CS030121T H E C I T Y O F
COPPELL
r e ~ ~`"f q ~ January 21, 2003
Mr. J. Michael Millican, P.E. s
Aguirre Corporation
12700 Park Central Dr., Floor 15
Dallas, TX 75251
RE: St. Joseph Village /Sandy Lake Road Project #ST 93-O1
Dear Mr. Millican:
Recently you provided information about the location of an inlet shown on the Sandy Lake Road plans to
accommodate your proposed entrance off of Sandy Lake Road into St. Joseph Village. As part of this submittal,
you provided amarked-up copy of Sheet 18 of the Sandy Lake Road plans. The marked-up copy showed that the
grade between Sta. 35+50 to Sta. 37+25 would be revised to a -.64% grade and the vertical curve would begin at
37+25 and end at 38+25. Your information also showed that the low point was at Sta. 37+75.
This information was provided to show that the inlet on the Sandy Lake Road plans currently shown at Sta. 38+15
could be relocated to Sta. 37+75 to accommodate your driveway. In reviewing your information, there appears to
be an error in the calculations. Utilizing the -.64% approach grade in the vertical curve that begins at Sta. 37+25
you end up with an elevation of top of curb of 448.27 at Sta. 38+25. Utilizing that elevation beginning at Sta. 38+25
and proceeding to Sta. 39+50 in a straight line, only provides you with a top of curb grade of .43%. This is below
our minimum grade.
I ran some trial and error calculations utilizing a steeper grade coming from Sta. 35+50 while maintaining a .5%
grade between Sta. 38+25 and Sta. 39+50. My calculations show that the grade between Sta. 35+50 and 37+25
should be a -.68%. This would give you an elevation of 448.27 at Sta. 37+25 and an elevation of 448.18 at Sta.
3g+25. The low point would be an elevation of 448.07; however, that low point would be at Sta. 37+82.6. Utilizing
these calculations, your proposed relocated inlet would need to shift further east, closer to Sta. 37+82. This in tum
will impact the radius shown on your Sheet C 10.0 that was also provided.
If it is your intent to have your proposed relocated inlet to remain at Sta. 37+75, then revisions to the proposed
Sandy Lake Road plans will entail more than just the changes you proposed between Sta. 35+SO and Sta. 38+25. If
your inlet remains at Sta. 37+75, the actual low point will still be within the transition of the gutter. However, to
insure no flat spots of standing water it would be desirable to have the inlet shift further east. Please review this
information and respond back to me at your earliest convenience. Once this has been accepted, the City will expect
your firm to revise Sheet 18 and any other peripheral sheets within the Sandy Lake Road plans to insure that the
inlet gets constructed in the correct location during the construction of Sandy Lake Road.
If you have any questions or need any additional information please feel free to contact me at your convenience.
Sincerely,
x~ r~~
Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
Office 972/304-3686
Fax 972/304-7041
235 PARKWAY * P. O.BO% 47B * COPPE LL TX 75019 * TEL 972/462 0022 * FAX 972/304 3673