Coppell Comm 1R3-CS040414 (2)JE J 0 N ES & CARTE R,l.c.
ENGINEERS' PLANNERS'SURVEYORS
3030 LBJ Freeway, Suite 910
Dallas, Texas 75234-7747
TEL 972 388 4880
FAX 972 488 3882
AUST]N
DALLAS
HOUSTON
THEW00DLANDS
April 14, 2004
Mr. Keith R. Marvin, P.E.
Civil Engineer
City of Coppell
255 Parkway
Coppell, Texas 75019
Re:
Royal Park, Coppell Commerce Center, Lot 1R Block 3
Construction Plan Review Comments Response
Coppell, Texas
Dear Mr. Marvin:
Pursuant to your letter dated March 23, 2004 and our April 13, 2004 telephone conversation, please
accept this letter as a formal response to plan comments:
Dimension Control Plan
1. Using turning templates for a 19' vehicle with an 11' wheelbase and a 7' track, the 5-foot area is
sufficient for backing out of the most northwesterly parking space.
Drainage Plan
1. The grading along the southern property line has been revised to eliminate any off-site grading
that would affect the DART property. Therefore, no license agreement will be needed.
2. After further investigation, the off-site area that flows under Freeport Parkway was better defined
using the City of Coppell aerial topography. After analyzing the total pervious ("C"=0.30) and
impervious ("C"=I.0) areas, a cumulative "C" of 0.39 was found for the 2.83-acre area. The
reduction of the offsite area from 3.00 acres to 2.83 acres and the reduction of the "C" from 0.70
to 0.39 yielded a lowered required detention in the pond. The required storage for the 80-minute,
100-year storm dropped from 90,570 cubic feet to 65,859 cubic feet. Obviously, the water
surface elevation during the design storm event also dropped from 514.29 to 513.70.
3. The following notes have been added to the drainage plan: (1) Contractor shall repair pavement
throughout the extent of the gutter transition and pavement depression when relocating existing
inlet. (2) Contractor shall provide continuous concrete curb in area of relocated inlet. (3)
Contractor shall provide appropriate gutter and pavement transition to insure flow into proposed
recessed inlet. (4) Within public right-of-way, Contractor shall replace existing concrete to City
of Coppell standards. (5) When performing saw-cut operations, if the proposed cut line falls
within 4-feet of an existing joint line, Contractor shall move cut line to said joint.
4. As stated previously, additional data was collected that indicated that the off-site area is 2.82
acres with a "C" of 0.39. Copies of the calculations are attached to this letter for your use.
Utility
1.
2.
Plan
The referenced line work has been removed.
The comments on said sheet have been addressed.
Smart Engineering. Smart Solutions.'" www,jonescarter, com
Mr. Keith R. Marvin, P.E.
April 14, 2004
Page 2
Under cover of this letter, I have transmitted nine (9) sets of revised drawings dated April 14, 2004
"Issued for Construction" for your approval and release.
If you have any questions or wish to discuss these comments further, please call.
Sincerely,
Pr~ectManager
JRE~e
l:~rojects~&CDallasXPritchard Associates (D076)\002 Bums & Fre~ofl\~tter\planresponse4-14-04.DOC
cc: Brett Ratlif£, Pritchard Associates, Inc.
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JONES & CARTER, INC.
Consulting Engineere
Houston - Dallas
DESIGN AND COMPUTATIONS
CLIENT ~J'a' '~4,
PROJECT
SUBJECT 0~"
DATE +/
BY 0~ SHEET
515~5
x
519.5
x
519.0
×
PARKING
PARKING
×
PARK]NO
x 517
PARKING
x517.~
x515.~
x515.6
x51
.,..-------520
519.0
51T.6
x
x518.4
~ARK[NG
x517.9
x518.6
Modified Rational Method Detention Basin Design
Royal Park
Step 1
Present Conditions
4.07 cfs
Area= 8,72 acres
Step 2
Future Conditions
C = 0.54
Tc = 10 min
hoo = 8.88 ingnr
Qi00= 41.81 cfs
Step 3
Check Various Storm Durations
Duration I Q
(rain) (in/hr) (cf s)
10 8.88 41.81
20 7.00 32.96
30 5.80 27.31
40 5.00 23.54
50 4.40 20.72
60 4.00 18.84
70 3.70 17.42
80 3.40 16.01
90 3.10 14.60
Step 4
fnflow vs. OuOqow
Inflow = Storm Duration * Respective Peak Discharge * 60 sec/min
Outflow = Half of Respective Inflow Duration * Control Release Discharge * 60 sec/min
Storage = Inflow - Outflow
20 min Storm
30 rain Storm
40 rain Storm
50 rain Storm
39,554 cf
3,663 cf
35,891 cf
49,160 cf
4,884 cf
44,276 cf
56,506 cf
6,105 cf
50,401 cf
62,156 cf
7,326 cf
54,830 cf
60 rain Storm = 67,807 cf
70 min Storm
80 rain Storm
90 min Storm
8,547 cf
59,260 cf
73,175 cf
9,768 cf
63,407 cf
76,848 cf
10,989 cf
65,859 cf
70,067 cf
12,210 cf
57,857 cf