HomeMy WebLinkAbout2008-07-10 BRAA RCP Pipe Review & CommentsPa I of 2
Julie Hultman
From:
Eric Johnson
Sent:
Thursda Jul 101 2008 1:23 PM
To:
Julie Hultman
Subject: FW: A.S. Kin Ash Disposal Facilit - RCP Pipe Review
Julie,
Please put Dennis' comments below into the Xcel plannin file — fl ash site revisions
Thanks
eric
From: Postler, Dennis M [mailto: Dennis. Postler@bonestroo.com]
Sent: Thursda ]ul 10, 2008 1:11 PM
To: Eric Johnson
Cc: Scott Richards Tom Ozzello Erickson, Karen S
Subject: FW: A.S. Kin Ash Disposal Facilit - RCP Pipe Review
Eric & Scott:
Here are some bullet-point concerns from Eric Lea in our Structural Department. For a little clarification, Item
#4 relates to localized impacts to the pipe, whereas Item #6 relates to the overall ali of the pipe for the
len of the fill throu the entire site based on existin underl soil conditions. I know we alread discussed #8,
and we can g et better information related to alternative routes and related costs prior to the next Plannin
Commission Meetin (new g ravit y ali lift station and forcernain, line existin pipe, directionall drill relief pipe
adjacent to existin etc.).
Not sure if y ou wanted me at the meetin toni --- I am not able to attend. Please call me on m cell phone (651-
775 -5102) an toda or this evenin if y ou have an q uestions or re additional information. Thanks much.
Dennis
From: Lea Eric E
Sent: Thursda Jul 10, 2008 11:03 AM
To: Postler, Dennis M
Cc: Erickson, Karen S Caswell, Philip J
Subject: A.S. Kin Ash Disposal Facilit - RCP Pipe Review
Dennis,
Here are m initial thou and concerns on the proposed increased fill hei over the existin storm and sanitar
pipes.
1. The pipes should be televised or visuall inspected to determine if there has been a reduction in the pipes
structural capacit
2. The ash backfill materials should be evaluated to determine their in-place values such as friction an and unit
wei I would expect that the properties ma be variable due to partial cementin of the particles and
consolidation/compaction. Ash overburden is not a t backfill material, so definin the basic properties is
important and ma impact the structural anal of the pipe.
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3. The easements for the existing pipe alignments should also be verified to determine what limitations may be in
place on filling activities above and adjacent to the pipe.
4. The placement of additional fill over and embankments adjacent to the pipe should be evaluated to determine
the structural impacts (pipe bending, joint deflection and pipe shear). Based on a quick look at the pipe, I
would speculate that the pipe will not have sufficient capacity to carry the proposed fill heights.
5. The pipe could be strengthened in place either by sliplining or a cast -in -place liner if required. Providing a new
liner may be prudent in all cases, since access to the pipe will become difficult with increased fill heights.
6. The placement of additional fill over and embankments adjacent to the pipe should be evaluated to determine
the impacts to pipe grade. As previously discussed, the impacts to grade are likely minimal, but they should
still be investigated.
7. The condition of the manholes in the area of increased fill should be opened and inspected.
8. Alternative routes for a new sanitary interceptor should also be evaluated, as the increased fill height of 70+
feet of ash will make repairs and or replacement in the future almost impossible.
9. I would recommend that a report be provided by Xcel Energy (McCain Associates) which addresses the above
mentioned items. As an alternative, I believe Bonestroo, in conjunction with assistance from AET, could also
provide a review of the proposed impacts to the existing sanitary and storm pipes.
Please let me know how you would like to proceed.
Rega rd s,
Eric Leagjed, PE
Tel 651 - 6044784
eric.leagjeld@bonestroo.com
21r
1110 Bonestroo
2335 Highway 36 w
St. Paul, MN 55113
Tel 651 -636 -4600
Fax 651-636-1311
www.bonestroo.com
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7/10/2008