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<br />Former Lexington School <br />STS Project #95192-XF <br /> <br />TANK REMOVAL DOCUl\tENTATION <br /> <br />Site Obsenrations <br /> <br />The former Lexington School is located at 1130 W. County Road B. Roseville. Minnesota. The <br />Site Location Diagram (Figure I) is included in the Appendix. <br /> <br />One underground storage tank was removed from the Lexington School site. During the remo- <br />val. the tank was determined to bel .000 gallons in capacity. The tank was used as a <br />reserve fuel oil supply. Tank removal at the former Lexington School occurred on May 2. <br />1991 . The tank was located beneath a landscaped area on the northwest comer of the <br />school. Figure 2 in the Appendix shows the site configuration. Photographs # I through #6 <br />pictorially document the tank removal process. <br /> <br />Tank Removal <br /> <br />A backhoe was used to remove soil overlying the tank. Soils were scanned for petroleum <br />impacts during the tank removal. An HNU photoionization meter and visual observations of <br />the soil were used to monitor for soil contamination. Figure 3 in the Appendix shows the <br />location at which soil samples were obtained for HNU screening. <br /> <br />Excavation of soils over the tank continued until access to the top of the tank was <br />obtained. The fill pipe was disconnected and the tank purged of fuel vapors with carbon <br />dioxide. Approximately 50 pounds of dry ice (carbon dioxide) was placed in the tank. <br />Carhon dioxide gas is a non-combustible gas and is heavier than fuel vapors. Carbon <br />dioxide gas serves to displace the fuel vapors. thus reducing the risk of ignition of the <br />fuel vapors. <br /> <br />Excavation of the soil around the tank continued after purging the tank. When the tank was <br />exposed. supply lines and vent lines were disconnected. The underground storage tank was <br />not anchored to a concrete hold down pad. <br /> <br />- 2 - <br />