ST0301-CS040330~an:Tayl°r~. IRK Meeiin~ M~r~-utes from-3/25/6~4 Progress._ M~ing . - - ' P~ 1 i
From: "Chris Moorman" <CLM~freese.com> (~¢~4 ([
To: "Keith Matin" <kma~in~ci.coppell.tx.us>, <kgriffin~ci.coppell.tx.us>,
<staylor~ci.coppell.tx.us>
Date: 3/30/2004 5:58:21 PM
Subject: RE: Meeting Minutes from 3/25/04 Progress Meeting
Keith,
We do have some discrepancies with the numbers that are in question. At
the upstream face of the culvert at Coppell Road, our model indicates a
WSE of 505.24 (as opposed to 505.16) and our proposed roadway grade at
this location is 507.40 (as opposed to 506.8). The 506.80 elevation is
in the model but should be changed to 507.4 in order to match the
attached design. We have re-run the model with this change and it makes
no difference in water surface elevation of the design storm. I
apologize if I gave you an incorrect plan/profile sheet of the culvert
area and am attaching a copy of the most current plan/profile sheet for
your convenience.
As for the backwater condition upstream of Coppell, we did a preliminary
analysis looking at larger (i.e., taller) culverts and the following are
the results. As you can see the taller culverts do lower the water
surface. However, they only lower it about 1 foot in the extreme case
of the 10x9 box and less than 0.5' using the 10x8 box. The 10x8 box
design appears to be a viable option while the 10x9 does not (see note
below table).
WSE Soffit Top of Road (2'
freeboard)
10x7 box 505.24 503.62 507.24
10x8 box 504.86 504.62 506.86
10x9 box 504.12 505.62 506.12
NOTE: Based on the Transystems model the top of bank immediately
upstream of Coppell is approximately 505.00. Therefore, the 10x9 box
would be higher than the channel (comparing soffit at 505.62 to t/bank
at 505.0) and not all of the culvert would be utilized in the design
storm (comparing WSE at 504.12 to soffit at 505.62). For those reasons
this does not appear to be a desirable option.
The culvert design does appear to contribute to the backwater condition
but a larger culvert does not eliminate the situation. Furthermore,
even the 10x9 box scenario causes water to escape the proposed channel
at XS16+50 where the adjacent natural ground is only around 503.5.
Generally, these preliminary findings are consistent with our previous
comments that we can lower the headwater somewhat but not significantly.
Please let us know which direction you would like us to proceed with.
Thank you,
Chris Moorman, E.I.T.
Freese & Nichols, Inc.
1701 N. Market St.
Suite 500 LB 51
Dallas, TX 75202
(214) 217-2221 - voice
Suz~n 7ayio~r :.RE: ~eeting M~nute~ro~-:~/2-5/O~Pro~gres~ ~M~e~ing -- ~g~ ~ ,'
(214) 217-2275 - fax
..... Original Message .....
From: Keith Marvin [mailto:kmarvin@ci.coppell.tx.us]
Sent: Tuesday, March 30, 2004 12:18 PM
To: Chris Moorman; Tricia Harley
Cc: Ken Griffin; Suzan Taylor; Tony Diaz; Alan Greer; Bow Lin; Bill
Cotten; Chris Bosco; Scott Fisher; Melinda Polley; Mark Cdswell
Subject: Re: Meeting Minutes from 3/25/04 Progress Meeting
I have discussed the water surface elevation and top of pavement
elevation with Transystems as well as Rob Bergeron of FNI. It seems
that the discrepancy in the models has been resolved and that all
parties are in agreement with the results.
The information I received from Transystems is the following:
The water surface at the upstream face of the culvert under Bethel is
507.2
The proposed grade of Bethel at this location is 509.2
This structure should be fine.
The water surface at the upstream face of the culvert under Coppell is
505.16
The proposed grade of Coppell at this location is 506.80
City of Coppell requires 2' of freeboard above the water surface for
the top of pavement. This does not appear to be met.
Let me know if there is a discrepancy with any of the above numbers.
Both models/modelers also agree that there is a backwater condition
between Bethel and Coppell Roads. It appears that a portion of that
issue is a result of the culvert design at Coppell Road. Can anything
be done at this point with the Coppell Road crossing to eliminate this
situation?
Please let me know if you concur with the model numbers, and if so,
address the two outstanding issues.
Thanks.
Keith R. Marvin, P.E.
City of Coppeil
(972) 304-7044
kmarvin@ci.coppell.tx.us
>>> "Chris Moorman" <CLM@freese.com> 3/30/2004 11:29:44 AM >>>
Ladies & Gentlemen,
Here are the meeting minutes from our last progress meeting on March
25,
2004. If there are any discrepancies or omissions please feel free to
contact me and I will adjust the minutes accordingly. If there are no
Suzan Taylor -,RE: Meeting MinuteS f~rom 3/2~/o4 Progresls- Meeti~g ' .~ = - Page 3 I
responses, then I will assume the meeting minutes are complete and
accurate.
If there are any questions or comments, feel free to contact myself or
Tricia Hatley.
Thank you,
Chris Moorman, E.I.T.
Freese & Nichols, Inc.
1701 N. Market St.
Suite 500 LB 51
Dallas, TX 75202
(214) 217-2221 - voice
(214) 217-2275 - fax
<http://www.freese.com/>
CC: "Tricia Hatley" <thh@freese.com>, "Robert Bergeron" <rpb@freese.com>, "Michael
Hobbs" <mrhobbs@transystems.com>