HomeMy WebLinkAbout2018-09-21 Stantec RTW Plan Review Julie Hultman
From: Mann, Lee <Lee.Mann@stantec.com>
Sent: Friday, September 21, 2018 11:03 AM
To: Eric Johnson
Cc: Julie Hultman; Andrew Kegley; Miller, Lucas; Kieffer, Charles; Bellemare, Brian
Subject: Palmer Station Retaining Wall Plan and Calculation review
Attachments: johnson_mann_PalmerStation_09-21-2018_retwall_letter.pdf
Hi Eric,
Attached is our review of the plan and calculations for the retaining wall in the Palmer Station project that were submitted
yesterday. There are comments that need to be addressed and the plans and calculations will need to be resubmitted for
further review. There will also need to be a Geotechnical engineer on site during construction as described in the letter. I
have not copied the developer on this in case Julie has other items to include in the communication to the developer.
Let me know if you have any questions.
Lee M. Moth, PE MN,WI, CA
Principal
Direct:651 604-4850
Mobile: 651 775-5956
Lee.Mann@stantec.com
Stantec
2335 Highway 36 West
St. Paul MN 55113-3819 US
Stantec
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Stantec Consulting Services Inc.
2335 Highway 36 West
Stantec St.Paul MN 55113
September 21,2018
File: 193800151
Attention: Mr.Eric Johnson,City Administrator
City of Oak Park Heights
14168 Oak Park Blvd. N., P.O. Box 2007
Oak Park Heights, MN 55082-2007
Reference: Palmer Station Retaining Wall Review
Dear Eric,
We have reviewed the plans and calculations for the Palmer Station development retaining wall, received 9-
20-2018. Following are comments and recommendations from our structural engineer, Brian Bellemare,
PE, SE. Items 4-6 will need to be addressed on the plans and calculations and resubmitted.
1. This is a small block, dry cast wall. We specify and approve both types of block (small block, dry cast
and large block, wet cast). The small blocks are easier to work with but have less compressive strength
and are more porous than the big blocks.
2. The calculation package looks good. The design follows the required NCMA guidelines. The assumed
loads and safety factors are appropriate.
3. There is no geotechnical information. The designer has made assumptions based on previous
experience in Oak Park Heights. This will require an onsite Geotech during the excavation and backfill
periods. The Geotech will need to verify the existing subgrade is suitable, watch the placement and
compaction of the aggregate base and then verify the quality and compaction of the retained backfill.
4. Detail 11/W2: Behind the top of the wall, there should be a layer of impervious material (clay, asphalt,
etc)to reduce water infiltration. This is key when using the small, porous blocks. Also, there should be
a small swale at the top to prevent runoff from going over the top of the wall.
5. They show details for drain tile but not where it is routed or how it daylights. I would expect the draintile
to be placed behind the first course of block above grade and slope down to the center of the wall,
where it can then stub through the wall.
6. The plan calls for a"42" High Black Vinyl Coated Chain Link Fence on Top of Wall". If the intent is to
attach directly to the top of wall, then they should provide a detail. Also, the calculations would need to
be updated to account for sliding and overturning due to a load pushing on the fence. Alternatively,
they could grout the fence posts behind the wall to reduce the impact on the wall design.
Regards,
Stantec Consulting Services Inc.
Lee M. Mann, PE
City Engineer
Phone:651-604-4850
Lee.mann@stantec.com
c. file
Andy Kegley
Julie Hultman