ST8201-CS 890526RUSS DOYLE
~ ~IBI~BI~._~_ ~ HANDI*/RITTEN r,I£/VlORANDUr,1
~ TI4~ CITY WITH A
~ B~.AUTIFUL FUT
TO:~FROM:
SUBJECT:
MESSAGE:
CITY OF COPPELL
DE pA R?HEN? OF pOLICE
Chief Foley
SUBJECT~ Drainage
FROM~ Lt. M.S.
DATE~ 05-24-89
Regarding the memo you gave me from Russ dated 05-19-
89 on drainage, please be advised that I would have no
idea concerning the issuance of permits for grading or
whether the grading was properly or improperly done.
However, we did have several areas of concern due to
the extremely heavy rains and the flooding it caused
in the City. Our major areas of concern are as follows.
2.
3.
4. Lock and Bethel
5. 215 N. Moore
6. 230 S. MacArthur
Sandy Lake Rd. east of MacArthur
North Denton Tap between Sandy Lake Rd. and Parkway
West Beltline between Mockingbird and MacArthur
These were the main areas of concern in the City, however
there were several side streets in the sub-divisions
where flooding occurred but subsided as fast as the rain
going past.
It should also be noted that there were several areas
outside of our City that were causing us problems.
1. Beltline east of the Longbranch
2. Bethel Rd. just outside our City Limits
3. MacArthur south of the bridge south of Beltline
As I stated, it is unknown whether this was caused
grading problems or not.
Leonar~
M.S.L.
by
MSL/mjt
c/file
HANDWRITTEN MEMORANDUM ·
THE CITY WITH A
MESSAGE:
GINN, INC.
May 17, 1989
Mr. Russell Doyle, P.E.
city Engineer
city of coppell
P.O. Box 478
coppell, Texas 75019
Re:
CONSULTING ENGINEERS
Denton Tap Road Improvements from Sandy Lake Road to Denton
Creek - Handwritten Memorandum dated 5-3-89.
Dear Mr. Doyle:
This letter is in response to your Handwritten Memorandum dated
May 3, 1989, copy attached. During the recent rains resulting
from heavy thunderstorms our resident project representative
observed the lane flooding situation in the vicinity of the storm
water inlets along the west curb line at project stations 176+50
and 177+80. Based on the field reports we have received and your
verbal and written inquiries, we have been studying the situation
in search of both long and short term solutions to the lane
flooding recently experienced. We will address the specific
issues raised in your Memorandum, and then cover the critical
elements of the potential solutions identified.
As you are aware, intense rainfalls are usually associated with
the frequent heavy thunderstorms typically experienced in this
locality at this time of year. Street flooding occurs both
during the rainfall and until the resulting significant run-off
subsides. This lane flooding cannot practically be eliminated in
most cases. Typically, as in the city of Coppell, the enclosed
storm sewer systems are designed to handle the stormwater run-off
from a 100-year storm and the on-grade inlets are designed to
remove stormwater run-off generated from a 5-year storm from the
gutters. During more intense storms the inlet capacity is
temporarily exceeded and storm water is allowed to pond in the
designated traffic lanes for the duration of the event which
produces stormwater run-off in excess of the design capacity of
the inlets.
The subject roadway has been designed in accordance with the city
of Coppell Standard Construction Details, and as such has a
standard cross slope of 1/4" per foot in the area of concern.
The longitudinal slope (gutter slope) is essentially 0.5%. It
should be noted that a grade change occurs at station 176+50, the
location of the more southerly of the two inlets in question.
This particular inlet was located at the grade change in order to
remove as much gutter flow as possible before it reached the
lower gutter capacity of the paving section i~u~ediately downslope
of the grade change.
17103 Preston Road ® Suite 100 · LB II8 · Dallas, Texas 75248 · Phone 214/248-4900
The current problem appears to be related to the fact that
portions of the adjacent properties which were not originally
included in the drainage area for this project may have been
recently graded in such a fashion that they now contribute run-
off to this project. Additionally it appears that the run-off
flow is concentrated in a couple of areas, rather than being a
sheet flow condition for which the storm drainage system was
originally designed. Compounding the above, the slopes behind
the property line of the adjacent property cause the run-off to
flow further out into the roadway than originally anticipated.
The long term solution to this problem is related to the fact
that the adjacent property in the area of concern is currently
undeveloped. In anticipation of the ultimate development of the
property, a storm sewer lateral stubout (lateral D-13a) has been
provided from the main Denton Tap Road storm sewer system, as a
part of the original project design, to provide for the developed
storm water run-off from the adjacent properties. In order to
accomplish this long term solution, the adjacent property owners
must design and build an onsite extension of the existing storm
drainage system as a part of the development of their properties.
This morning we were notified of the closure of Denton Tap Road
between Sandy lake Road and Parkway Blvd. as a result of the
recurrence of the lane flooding due to the heavy thunderstorms
experienced last night and this morning. After traveling to the
site this morning and observing the lane flooding situation, we
directed the Contractor to create openings at the rear of the
inlet at station 176+50 and grade the slope immediately behind
the inlet to the bottom of the openings. We also had the
Contractor deposit excavated materials in such a way as to
collect the run-off at the property line and funnel it into the
back opening of the inlet. The work and street cleanup was
completed by 2:30 P.M. this afternoon and the road opened to
traffic at that time.
If the above method of temporarily controlling the run-off
discharges from the adjacent property is successful we may have a
concrete riprap flume constructed at the rear of the inlet as a
temporary measure until the property develops.
Please call me if you have any questions.
Sincerely,
John C. Karlsruher, P.E.
Project Engineer
attachment
cc:
H. Wayne Ginn, P.E.
Randy Fleming
File 379 (A:DENFLOOD)