From: Jennifer Cline
Sent: Fri Jun 10 11:07:34 2016
To: Randall Stark
Cc: Chris Link; Dan Huff
Subject: RE: Molalla Avenue - Street Section Topics
Importance: Normal
Hi Randy,
See my comments below.
Jennifer Cline, P.E. | Public Works Director
Licensed in OR, WA
117 N Molalla Ave. | PO Box 248 * |Molalla, OR 97038
O: 503.759.0218 | F: 503.829.3676
From: Randall Stark [mailto:Randall.Stark@msa-ep.com]
Sent: Friday, June 10, 2016 10:47 AM
To: Jennifer Cline <jcline@cityofmolalla.com>
Cc: Chris Link <Chris.Link@msa-ep.com>
Subject: Molalla Avenue - Street Section Topics
Hi, Jenn. We talked with Dan Trisler, the project geotechnical engineer, regarding the two items that have come up recently regarding street typical sections and construction methods, and wanted to get your input before we pass it on to ML Houck.
1. Street typical sections –
For street sections within intersections, the geotech continues to recommend the travel lane sections specified in the geotech report, either with cement treated subgrade (CTS) or full digout with geotextile, stabilization rock, etc. Full-depth construction within intersections is called out on the bid plans per Note 7 on the Molalla Avenue typical section on Sheet C-1. We don’t feel comfortable approving the parking stall section that ML Houck has already installed through the Robbins Street intersection. I agree, the contractor will need to build the full depth rock section or use CTS (their choice) across the intersection. They may recover some cost in the reduced 1” base rock section.
During our discussion about this in our meeting yesterday, Greg said that due to constructability issues he prefers to build the portions of the intersections in alignment with the parking stalls with full digout instead of CTS. We don’t see an issue with this. We would need to adjust/ prorate the cost prepared for the parking stall full digout to cover this cost. Let me know, unfortunately, Dan already sent the quote to MCC for their half. I suggest waiting to see if they request the additional costs for the roadway section since it is identified in the plans and they did already give us the cost for the work.
2. Compaction testing for cement treated subgrade –
Mike Houck had expressed concern about getting consistent compaction test results using a nuclear density gauge. Dan Trisler said that nuclear gauges don’t function well on CTS, and the preferred method is proof rolling. Proof rolling needs to wait a minimum of 24 hours after compacting, with 48 hours preferred. Proof rolling appears to be the better option in this case. I agree to this method as well.
Attached is a sketch we want to provide to ML Houck, which depict the 2 typical sections utilizing the full digout method
Sketch looks acceptable to me.
Please provide any input you may have.
Thanks!
Randy Stark, P.E. | Civil Engineer
Licensed in WA, OR
T: 360.448.4230 | F: 360.448.4239 | Randall.Stark@msa-ep.com
400 E Mill Plain Boulevard, Suite 203 | Vancouver, Washington 98660-3492 | www.msa-ep.com
Murray, Smith & Associates, Inc. | Your Public Works Partner
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