Lake Park/FP-CS 900424GINN, INC.
Date:
To:
From:
CONSULTING
PLAT/PLAN REVIEW MEMORANDUM
April 24, 1990
Public Works Department
John C. Karlsruher, P.E.
Re:
Review Comments for the Final Plat and Engineering
Plans for the Lake Park Addition
FINAL PLAT:
Show minimum finished floor elevations on each lot based on
Denton Creek 100 yr Ultimate Development Flow for Existing
Conditions Channel HEC-2 model + 2 feet.
PAVING PLANS:
Sheet 4/7 - Revise Lake Park Road width between Circle Cove
Drive and MacArthur Blvd. as per the requirements of
Planning & Zoning Commission meeting on April 19, 1990.
WATER AND SEWER PLANS:
Water and Sanitary Sewer Plan, Sheet 1/3 - Show calculated
centerline curve data for curved sanitary sewer lines.
Sheet 1/3 - Address 20' easement issue on Line D and check
to see if buildable area exists on Lot 7, Block A due to
easements.
Sheet 2/3 - Use one foot thickness of concrete encasement on
sanitary sewer drop connections.
Sheet 2/3 - Use D.I. pipe for Line A at crossing of storm
sewer (in addition to concrete encasement).
Sheet 3/3 - Use one foot thickness of concrete encasement on
sanitary sewer drop connection.
DRAINAGE PLANS:
Drainage Area Map, Sheet 1/3 - Use Type C headwalls for
storm sewer outfalls. Extend concrete rip rap flume to flow
line of creek or toe of slope in the lake bottom as
appropriate.
17103 Preston Road · Suite 100 · I,B 118 · Dallas, Texas 75248 · Phone 214/248-4900
Sheet 2/3 - Use 100 yr water surface elevation = 454.16 in
lake and Denton Creek for storm sewer HGL calculations.
Also, as per the Subdivision Ordinance in effect in 1982,
the elevation of the hydraulic grade line shall be a minimum
of 1.5 feet below the elevation of the adjacent street
gutter.
Sheet 3/3 - Use Type C headwalls on storm sewer outfalls.
Extend slope protection to toe of slope in lake and Denton
Creek.
Sheet 3/3 - Use 100 yr water surface elevation of 454.16 in
lake and Denton Creek for HGL calculations.
Sheet 3/3 - Use Type C headwalls for storm sewer outfalls.
Extend concrete rip rap flume to toe of slope in lake and
Denton Creek.
Sheet 3/3 - As per the Subdivision Ordinance #185, the
elevation of the hydraulic grade line shall be a minimum of
1.5' below the elevation of the adjacent street gutter.
As agreed to in a meeting held on Thursday, April 19, 1990, at
the Coppell Service Center, the applicant will obtain a
Conditional Letter of Map Revision from FEMA prior to the
beginning of any construction beyond grading, paving and
drainage. No Certificates of Occupancy will be issued until a
Final Letter of Map Revision has been obtained from FEMA for this
project. The Owner of the property shall furnish the City of
Coppell a letter stating that he will assume all liability
associated with his construction of this project in and adjacent
to the floodplain of Denton Creek and will indemnify and hold
harmless the city of Coppell from any damages resulting from the
Owner's construction activities in and adjacent to said
floodplain.
This review has been conducted in accordance with the Subdivision
Regulations o.f Ordinance No. 185 adopted July 25, 1978.
FILE COPY
TIlE DIT Y fill TII A ~EAIITIFIIL FIITIIIIE
FiLE CO?'i
FILE COPY
SUB-DIVISION ORDINANCE
CITY OF COPPELL, TEXAS
SUBDIVISION REGULATIONS
ORDINANCE NO. 185
6. Storm Sewer Design ,
Storm water in excess of that allowed to collect in
the streets shall be intercepted in inlets and carried
away in a storm sewer system. Storm sewer capacity shall
be calculated by Manning's formula --
Q = 1.486 AR2/3S1/2 where
n
Q
R
S
is the discharge in cubic feet per second;
is the cross-sectional area of flow in square
feet;
is the hydraulic radius in feet;
is the slope of the hydraulic gradient in feet
per foot;
is the coefficient of roughness (n : .013 for
new concrete pipe)
Sample computation sheets are included for inlet and
storm sewer design calculations.
I_n__.t_h_e_d_e_s.~g n_q.~..t h e_. storm., s ewe?_ s ys tern, .. th e.. e 1 e va t i o.n
otf__the hydrau]_ic_ gradienKo.? th_e Storm sewer shall be
.a m!nimum.of.l.5.fe_et._below the.elevation of the adjaEent
s~ee t gutter: .......
Storm sewer pipe sizes shall be so selected that the aver-
age velocity in the pipe will not exceed 15 feet per
second nor less than 3 feet per second.
Storm sewer systems shall be installed in all areas
where the quantity of storm run-off is 200 cubic feet
per second, or less. A storm sewer system may be con-
structed when the quantity exceeds 200 c.f.s, at the
discretion of the subdivider.
7. Open Channel Design
Storm water run-off in excess of that allowed to collect
in the streets in developed areas and run-off is un-
developed areas may be carried in open channels (not in
the street right-of-way). Open channel capacity shall
be calculated my Manning's Formula and roughness co-
efficients shall be as follows:
Type of Lining
Earth (Bermuda Grass)
Earth (Non Vegetated)
Concrete Lined
Weathered Road
Roughness Coefficient
Maximum Permissable
Mean Velocity
0.035 8 ft. per sec.
0.030 5 ft. per sec.
0.015 15 ft. per sec.
0.030 15 ft. per sec.
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9.04
9.05
SEVERABILITY
If any section or part of any section, paragraph or
clause of this Ordinance is declared invalid or un-
constitutional for any reason such declaration shall
not be held to invalidate or impair the validity,
force or effect of any other section or sections,'
part of section, paragraph or clause of this Ordinance.
EFFECTIVE DATE
This Ordinance shall become effective immediately upon
its publication.
Passed and adopted this 25th day of July
19 78 ,
ATTEST:
uorothy minions, CiJ>9 Secretary
APPROVED AS TO FORM:
Lawrence W. Jackson, City Attorney
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