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STS Consultants Ltd. <br />Consulting Engineers <br />2405 Annapolis Lane, Suite 280 <br />Minneapolis, Minnesota 55441 <br />(612) 559-1900 <br />July 10, 1987 <br />Mr. Ron Backus <br />The Shelard Group <br />7825 Washington Ave. S. <br />Suite 700 <br />Bloomington, MN 55435 STS Project 94039-XA <br />Re: Rice Street Retail Center in Roseville, Minnesota <br />Dear Mr. Backus: <br />As you requested on July 9, 1987 we have examined the above - <br />referenced site for the presence of petroleum product in the <br />subsurface soils. Petroleum odors were noted by STS person- <br />nel during excavation for the foundations of the retail <br />center. The area of concern was within the east foundation <br />line just north of the southeast corner of the building. <br />The initial contaminated area observations were conducted on <br />July 9th. During that site visit the HNU photoionization <br />meter was used to identify the presence of organic vapors in <br />the soils at the southeast corner of the building. -An HNU <br />deflection of 118 parts per million was identified at a depth <br />of approximately 7 feet below site grade in the footing <br />subcut excavation. <br />On July loth a project engineer from STS Consultants, Ltd. <br />observed two backhoe test pits, one east and one west of the <br />area of concern. The purpose of these test pits was to <br />identify the vertical and horizontal extent of the contamina- <br />tion. These test pits extended to an approximate depth of 17 <br />feet. The locations of these test pits are shown on the <br />attached site diagram (Figure 1). <br />The soils encountered were similar to those identified in the <br />test borings conducted at the site. To a depth of approxi- <br />mately 14 feet, fill materials were encountered. The fill <br />was silty sand with varying quantities of concrete rubbla, <br />debris and concrete blocks. A larger quantity of rubble was <br />encountered in test pit 2 than in test pit 1. <br />HNU deflections were recorded in areas where petroleum odors <br />were noted. A summary of HNU deflections calibrated with a <br />benzene referral is presented on Table I. It was noted thl:,t <br />the HNU deflections were relatively low in the Eill material <br />