ST9801-CS 981228by:
FREESE & NICHOLS
21~,'2565
2149202565
12/28/98
Job 194
Page
FREESE - NICHOLS
TO:
FROM:
Fax Transmittal
Ken Griffin, P.E.
fax: 972-304-3570
Eric Riedinger, E.I.T.
~imoll W h'cese. P.E.
Marvin C.
19(1~-t990
1896-1969
DATE: December 28, 1998
SUBJECT: Coppelt Road
Total number of pages including transmittal sheet: l: ~
If there is a problem receiving any of the pages, please call Kathr>,n at 214-920-2500.
1/1
COMMENTS:
I was able to reach Jim Riley with BDD on the GTE project to deten-nine how a 66" RCP was
determined. After reviewing his calculations and ours, we feel comfortable with just extending the
96" RCP under Coppell Road and providing erosion protection at the upstream end of the pipe. The
differences in our calculations are ms follows:
BDD: CA= 85.41 F&N:
Tc = 10 min
lmo = 8.88 in/hr
Q = 758.4 cfs
CA = 68.05
Tc = 17.29 rain
Iux~ = 7.20 in/hr
Q = 489.94 cfs
The area discrepancy is from our 18.01 ac from HWY 121 and their 35.4 ac from HWY 12t. This
difli~rence was discussed in our meeting last Monday. I have also include travel time through the
system lowering my intensity. These differences result in only requiring a 96" RCP. W t~have a
sheet from Halff & Associates showing the downstream channel lined with rip-rap and · open
channel to the creek We are not planning any design to be done to the downstream chan el from
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- END -
cc: CPL98447 3. I
FREESE AND NICHOLS. INC. · t341 W. MOCKINGBIRD LANE, SUITE 23C)-E · DALLAS, TEXAS 75247-4922
TELEPHONE: 2 ! 4-920-2500 · FAX: 214-9211. 2565