Denton Co Levee-CS 921110�D CARTER & BURGESS'NC.
ENGINEERS • PLANNERS •SURVEYORS
November 10, 1992
Ken Griffin, P.E.
City of Coppell
255 Parkway Blvd.
Coppell, Texas 75019
RE: Denton County Levee Improvement District No. 1
Siltation Control Project - Phase I
Dear Ken:
As you requested, I ha a determined the effect that the proposed diversion dams will have on 100 -year
water surface levels on tenton Creek. I have modeled three conditions as follows:
1. Without proposed diversion dams.
2. With proposed Diversion Dams A and B with 76 -foot long weirs shown on original
construction plans.
3. With proposed Diversion Dams A and B lengthened to 87 feet.
The 100 -year water surface levels for these three conditions are summarized in Table 1. The maximum
increase in water surface levels caused by the dams as originally proposed and with FEMA encroachments
is 0.05 feet. With the weirs lengthened to 87 feet, there is no increase in 100 -year water surface levels.
The estimated cost to increase the dams from the originally proposed 76 feet to 87 feet will be
approximately $28,000. I understand the City's policy of no rise in water surface levels as a result of
construction in floodplain areas. However, I believe that a minor increase of 0.05 feet meets the spirit of
the policy and request that our construction plans be approved as submitted.
I have also enclosed a 'copy of a June 17, 1992 letter which states the committment of the District to
address the Denton Creek siltation problem.
PD Jlf
173301.L07
cc: Mr. Jay Terry
Mr. Dennis VA
Sincerely,
CARTER &-.13URGESS, INC.
4 ,ea-4
Phil Deaton, P.E.
Vice President
7950 ELMBROOK DR. /STE 250 /DALLAS, TX 75247-4951/(214) 638 -0145
DALLAS • FORT WORTH • HOUSTON • ARLINGTON • AUSTIN, TEXAS
FORT MYERS, FLORIDA
TABLE 1
DENTON CREEK
100 -YEA WATER SURFACE LEVELS WITH AND WITHOUT PROPOSED DIVERSION DAMS
WITH FEMA ENCROACHMENTS
INCREASE
INCREASE
WITH
(DECREASE)
WITH
(DECREASE)
BACKWATER WITHOUr
76' WIDE
IN
BACKWATER
WITHOUT
87' WIDE
IN
SECTION DIVERSION
DIVERSION
WATER
SECTION
DIVERSION
DIVERSION
WATER
NUMBER
DAMS
DAMS
SURFACE
NUMBER
DAMS
DAMS
SURFACE
18440
452.36
452.36
0.00
18440
452.36
452.36
0.00
19330
453.14
453.14
0.00
19330
453.14
453.14
0.00
19930
453.14
453.14
0.00
19930
453.14
453.14
0.00
21560
453.33
453.33
0.00
21560
453.33
453.33
0.00
22370
453.50
453.50
0.00
22370
453.50
453.50
0.00
23800
453.53
453.53
0.00
23800
453.53
453.53
0.00
24700
454.13
454.13
0.00
24700
454.13
454.13
0.00
25530
454.68
454.68
0.00
25530
454.68
454.68
0.00
26830
455.86
455.86
0.00
26830
455.86
455.86
0.00
28080
456.75
456.75
0.00
28080
456.75
456.75
0.00
28870
457.15
457.15
0.00
28870
457.15
457.15
0.00
29610
457.59
457.59
0.00
29610
457.59
457.58
(0.01)
DIVERSION DAM B
DIVERSION
DAM B
29674
457.64
457.66
0.02
29674
457.64
457.62
(0.02)
30570
458.24
458.26
0.02
30570
458.24
458.23
(0.01)
31230
458.83
458.85
0.02
31230
458.83
458.83
0.00
DIVERSION DAM A
DIVERSION
DAM A
31293
458.88
458.93
0.05
31293
458.88
458.87
(0.01)
32150
458.99
459.03
0.04
32150
458.99
458.98
(0.01)
32200
458.48
458.53
0.05
32200
458.48
458.47
(0.01)
32230
458.62
458.66
0.04
32230
458.62
458.61
(0.01)
32250
460.51
460.54
0.03
32250
460.51
460.50
(0.01)
32780
461:39
461.60
0.01
32780
461.59
461.58
(0.01)
34130
462.59
462.60
0.01
34130
462.59
462.59
0.00
35170
462.98
462.98
0.00
35170
462.98
462.98
0.00
36970
465.59
465.60
0.01
36970
465.59
465.59
0.00
39440
468.53
468.53
0.00
39440
468.53
468.53
0.00
DENTON
Mr. Alan Ratlif
City Manager
City of Coppell
255 Parkway
Coppell, Texas
COUNTY LEVEE IMPROVEMENT DISTRICT NO. 1
2001 Bryan Tower, Suite 700
Dallas, Texas
214/954 -6300
Dear Mr. Ratliff:
Confirming
representatives
1, we would prop
two weir or che<
and the desiltat .
these check dame
restore water fl
improve the sil
understanding an
of the two check
associated with
season of high
evaluation made
WHV:sm
June 17, 1992
5019
a recent meeting between yourself and
of the Denton County Levee Improvement District No.
se to build, as was discussed in the meeting, the
k dams in the Denton Creek flood control channel
'on of the sections of Denton Creek associated with
as a test of the effectiveness of the dams to
ows to Denton Creek in low flow conditions and to
tation condition that now exists. Our further
d proposal is that upon completion of construction
dams and desiltation of the areas of Denton Creek
these dams a study would be conducted through a
(or flood) and low water conditions and an
of their effectiveness.
Sincerely,
%/m4 *66—,
William H. Vanderstraaten
Chairman
The ity With A Beautiful Future
P O. Box 478
Coppell, Texas 75019
214- 462- 0022
FACSIMILE NO. 214/393 -0948
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