2009-05-27 CC Packet Add.'l Handouts

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-, I A AMERICAN ENGINEERING TESTING, INC. CONSULTANTS . ENVIRONMENTAL . GEOTECHNICAL . MATERIALS . FORENSICS May 27, 2009 City of CenterviIle c/o Bonestroo 2335 West Highway 36 St. Paul, MN 55113 Attn: Mark Statz RE: Peltier Lake Drive Area Street and Utility Improvements CenterviIle, Minnesota AET No. 20-08832 Dear Mr. Statz: This letter presents a review of the recommendations we provided during our meeting at site on May 26, 2009. The topic of the meeting was the segment of Peltier Lake Drive to the west of CenterviIle Road which is adjacent to the DNR wetland. During construction, organic swamp deposits (peat, organic clay, and/or boglime) were found to be present below the proposed street, roughly between Station 16+00 to 20+00. This organic condition was noted to be particularly deep (below utility grades) between Stations 18+00 to 19+00 (approximate). This latter segment will be referred to as the "Deep Swamp Area" in this letter report. The remaining area (where the swamp was thin enough such that the utilities do not have swamp below) will be referred to as the "Shallow Swamp Area." 1.0 Background Soil borings were performed at the site by Braun Intertec in November of 2007. A boring was placed on Peltier Lake Drive, although appears to have been placed just to the east of the limits of the swamp. The boring indicates the natural inorganic soils in the area to be sandy lean clay glacial tills. A pre-existing sanitary sewer lies below the north side of the existing road. The sewer pipe reportedly sagged through the Deep Swamp Area. We understand the sewer,wilt' be reconstructed though this sagged area. w..tr 1b In addition, a new watermain has been placed closer to centerline; the pipe being about 8 feet below the final street grade. To provide foundation stability for the pipe, the waterrnain was undercut by about 3 feet and rock foundation bedding was placed below the pipe, as well as to the sides and just above the pipe. Sand was then placed above this, with the thickness of sand only being about I foot in the Deep Swamp Area and about 3 feet in the Shallow Swamp Area. Inferior on-site soils were then placed above this, recognizing that additional future correction would be needed. 550 Cleveland Avenue North 1 SI. Paul, MN 55114 Phone 651-659-90011 Toll Free 800-972-63641 Fax 651-659-13791 www.amengtesl.com I AA/EEO .... This document shall not be reproduced, except in fUll, without written approval from Amencan Englneenng Testlng, Inc. ,."