ST9902-CS131122 (2)
Halie Hernandez
From:Andrew Luce <ALuce@TNPINC.com>
Sent:Friday, November 22, 2013 11:08 AM
To:Keith Marvin
Cc:Casey McBroom; Chris Schmitt
Subject:Revised Sandy Lake Storm Drain Sheets
Attachments:REVISED SHEETS 64-67 2013_11_22.pdf
Keith,
Attached are revised storm drain sheets for Sandy Lake Ph. 2B. We have been able to get above the duct bank at all
conflict locations by reducing the pipe size and raising the elevation. There will also be sufficient cover to increase the
pavement thickness by two inches at all locations as well. This will result in the following changes to quantities:
+ 51 LF 15” Class IV RCP
+ 60 LF 18” Class IV RCP
+21 LF 21” Class IV RCP
-111 LF 18” Class III RCP
-21 LF 24” Class III RCP
I have raised the elevation of G-2 to attain 0.60’ of cover over the existing gas line. By doing this however, due to
entrance losses, the headwater elevation will be 0.49’ above the parkway elevation. The capacity of the box is more
than sufficient for the amount of flow, the headwater is caused by the opening size of the box. During previous
discussions you had mentioned that this would most likely become a closed system when that property developed,
linking this line to the headwall just north of the subdivision which would mean that this would be a temporary
condition. There are a few options in dealing with this:
1.Raise the storm drain line as shown in the sheets I have attached, knowing that the 100-yr headwater elevation
will temporarily be above parkway elevation until the culvert becomes a closed system.
2.Lay the box directly on top of the gas and the temporary 100-yr headwater elevation will be below elevation of
the parkway.
3.Lower the Atmos line and build the box per the original design.
4.Transition the line to a taller box to reduce entrance losses.
Please let me know if you have any questions to the above items.
Thanks,
Andrew
Andrew Luce, P.E.
Project Manager
1100 Macon Street
1
Fort Worth, Texas 76102
817.336.5773 Main
817.665.8208 Direct
817.336.2813 Fax
aluce@tnpinc.com
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