ST9905-CS050429[~uzan Taylor - RE: Bethel Road Page 1 I
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"Sam Meisnef' <sam@freese.com>
<staylor@ci.coppell.b(.us>
Thu, Apr 29, 2004 8:48 AM
RE: Bethel Road
Suzan,
In the plans that we just submitted, the top of curb elevation over the
culvert is 509.52 (at Sta 9+82) and the Iow point just to the west is at
509.18 ($ta 9+00). Assuming that the full depth of the typical roadway
section is maintained over the culvert, the top of the culvert cannot be
more than 507.68. When this culvert is resized to allow for protection
of the existing sewer line, the headwater needs to be within the
freeboard limits established. This would mean a maximum freeboard of
508.18 for ultimate flows or 507.18 for existing flows. The driveways
at Sta 9+48 and 10+71 are what control the road profile over the
culvert. The current design shows both driveways with a 2% rise from
the gutter to the ROW and then a 4% and 6% drop to the existing
driveway.
An option to raise the elevation of the read would be to increase the
grade break at the driveways to a maximum of 10%. This is traversable
for most cars, but it is possible it could cause scraping problems with
Iow ground clearance vehicles. This change would allow the road to be
raised 0.40 feet.
Another option to raise the road elevation would be to omit the rise in
the driveway from the gutter to the ROW, and instead maintain a 2% slope
down before beginning a steeper slope (max 10%) at the ROW. A curb
inlet would be installed at Sta 11+00 to capture all of the gutter flow
upstream of the driveway at 10+71, and the driveways could be graded to
direct local runoff to the stream and away from the house. This change
would allow the read to be raised 1.30 feet. This change would create a
sag point at Sta 7+75 and would require an additional pair of inlets.
It would also require reconstructing the driveway all the way up to the
structure at Sta 9+48 (620 Loch Lane).
The current profile is the most desirable option and is the option we
would recommend, but I know that there are other constraints on the
design of the culvert. If you have any questions please call me or
Tricia.
Sam Meisner
Freese and Nichols, Inc.
p 214-217-2235
From: Suzan Taylor [mailto:staylor@ci.coppell.tx.us]
Sent: Wednesday, April 28, 2004 10:44 AM
To: Tricia Hatley
Subject: Bethel Road
! Suzan Taylor - RE: Bethel Road Page 2 1
Tricia:
Have you had a chance to determine how much we can raise the road at the
proposed culvert?
Thanks
CC: "Tricia Harley" <thh@freese.com>