Whispering Hills-CS 870427 FILE COPY
GINN, INC. CONSULTING ENGINEERS
TO: Alan Ratliff, City Manager
FROM: Wayne Ginn, City Engineer
DATE: April 27, 1987
SUBJECT: ~~~Loop/Whispering..~.Hills Dr'var~
Pursuant to your April 3, 1987 memo advising us of a drainage
problem along Fieldcrest Loop and west of Whispering Hills, we
made an investigation and the following sets forth our comments
and suggestions.
I sent one of my technicians to review the areas and provide me a
preliminary "cause and effect" report. On April 16, 1987, Steve
Goram, Gabe Favre and myself visited the area to observe the
problem. On April 21, 1987, Gabe Favre made a detailed
investigation as to probable causes, hereinafter listed, and
possible solutions, also listed.
DiscussION OF PROBLEMS: (contributing factors)
1. Drainage inlets at intersection of Fieldcrest Loop and
Whispering Hills have smaller openings than our present
standards indicate. Flowlines of openings are higher than
existing surrounding ground at places, preventing overland
flow from entering the inlets freely.
2. Existing "swales" in yards are not allowing positive flow of
surface runoff.
3. Street constructed without curb and gutter, with some places
in street higher than finish floor elevations of homes,
thereby having to create drainage "swales" or ditches in
yard. Homeowners dislike ditches in their yards and over
period of years, they have "constructed" their solutions to
unsightly ditches by: placing very small pipes in ditch
bottom attempting to convey runoff and then filling in ditch
over pipe; or filling in ditches with grass clippings, fill
dirt, etco, so the ditch will not be so visible in their
yard.
4. The inlets and pipes have debris, silt, and trash in them
which prevents maximum allowable flows to be maintained.
5. PVC "culverts" under drives and walks are placed, not in
flowline of ditch, but in some cases higher which prevents
positive drainage. Small PVC drain pipes, open on lower end,
but clogged on upper end, contributes to ponding water.
17103 Preston Road · Suite I00 · LB 118 · Dallas, Texas 75248 · Phone 214/248-4900
6. 'On upper end of culvert, under Fieldcrest Loop, just east of
Fieldcrest Circle, debris, grass clippings, silt, trash,
etc., prevents uniform flow into culvert and ultimately
downstream. The culvert under the road appears to be in good
condition for conveyance of water that does enter the system.
7. Downstream concrete flume, 4' in width, with railroad tie
retaining wall appears to be in good working order, except
that approximately halfway down the flume, silt, debris,
grass, etc., prevents a uniform flow through the entire
length of the flume. At the end of the flume, coincidental
with the back of the lots, very little provision was made to
allow runoff to continue down the hill to the rear of the
subdivision. Trees and undergrowth prevent a smooth outfall.
8. General statement about all area around Fieldcrest Loop is
that it is relatively flat, with little provision for other
than very minimal ditch flow.
9. At 136 Fieldcrest, the "ditch" or "swale" was filled in with
PVC "culvert" and dirt, but on homes either side of #136 the
swale exists. The pipe was probably not sized to adequately
handle any appreciable flow, laid on too flat of a grade, or
even reverse slope, thereby creating backup, ponding, etc.,
on both ends. Water is standing on 140 Fieldcrest. The 6" or
8" PVC pipe at #136 has 4" of standing stagnant water in it.
10. The drive and subsequent "culvert" between Lots 203 and 207
appears to be higher than ditch flowline, thereby preventing
positive drainage. Water is standing in front of 207 and
appears to have been there for quite some time.
11. From Lots 223 west to 207 the "swale" which is supposed to
convey overland runoff is very indistinguishable and shallow
creating a situation where it is not doing the job it
probably was designed to do.
12. The ditch along the north side of Fieldcrest immediately east
of intersection with Whispering Hills is unkept, with tall
grass, weeds, debris, etc., in the ditch. People from across
the street are apparently dumping their grass clippings in
the ditch. This causes the ditch to become clogged and
prevent it from draining, thereby causing problems.
13. The culvert under Whispering Hills, running west to east,
creates a problem. The area to the east of Whispering Hills
where the lots of Whispering Hills Addition back up to
Shadowridge I is supposed to have an easement along the backs
of the lots. It appears fences have been built back to back
in some locations. This could conceivably prevent adequate
positive drainage in this area. There is a drainage easement
west of Whispering Hills that has a relative minimal slope
and needs to be cleared of debris, grass, etc., to properly
function. This is probably causing backup and breeding place
for mosquitoes. When culvert crosses under Whispering Hills
it goes into sump, then 90 degree bend, south, down
Whispering Hills Drive. This could be cause for backup
problems also.
14. The topo maps indicate the area west of Whispering Hills to
be very flat, and maybe when development continues in
Shadowridge II better drainage will be provided.
DISCUSSION OF SOLUTIONS:
Immediate Impact
1. Clean out all existing "ditches" or "swales."
2. Keep grass, debris, and silt from ditches, culverts, and
flumes so as to allow for positive surface water runoff.
3. Advise homeowners they are not allowed to place grass
clippings, trash, etc., in ditches.
4. Get homeowners association, if there is one, to provide for
keeping vacant lots cleared of all undergrowth.
5. Regrade any ditches or swales that do not provide for
positive surface runoff.
6. Do not allow any further "filling" of existing ditches with
PVC culvert pipe and dirt to remove the unsightly swales from
yards.
FUTURE POSSIBILITIES:
1. Relay and enlarge existing culverts under drives using
corrugated metal or concrete pipe, providing a positive slope
to all ditches (contingent upon having adequate "fall" in
overland flow).
2. Rework inlets so they work as they were designed.
3. Have fences removed within drainage easement to east of
whispering Hills so adequate flows may occur.
4. Construct inlet at east side of Whispering Hills where
headwall and culvert exist now in "sump."
5. Provide continued monitoring and maintenance of regraded
ditches, etc.
6. On the area west of whispering Hills which is holding water,
we would suggest regrading the ditch and cleaning it out as
one measure to insure positive flow at all times, thereby
eliminating the cause of the standing water. This area is in
a natural "low" flat lying area and until development
continues, will remain like that.
RECOMMENDATIONS:
Due to the fact that the homeowners problem was generated
preViously by builders/homeowners, it is difficult to determine
the monetary level of participation by the city.
The estimated cost of the immediate impact improvements should be
minimal, if it is done by City forces. The estimated cost of the
future improvements may range between $35,000.00 to $40,000.00,
depending on degree of improvements.
In our opinion, the regrading and construction of larger ditches
in the front yards will not be readily acceptable by the
homeowners. The ultimate solution may be a complete design of an
underground storm drainage system.
We need to discuss implementation of recommendations and whether
or not the City chooses to participate in the improvements at
this time.
If you need additional information, please contact us. We are
available at your convenience to discuss this further.
GF/HWG/ss
cc: Steve Goram
Gabe Favre
0241
Ratliff21-24