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<br />I <br />I <br /> <br />] <br /> <br />Engineering Administration and Testing Senrices <br />for the Removal of One Underground Storage Tank <br />at Lexington School, Roseville, Minnesota <br /> <br />J <br /> <br />INTRODUCTION <br /> <br />I <br /> <br />Independent School District No. 623 (ISD #623), Roseville School District, is in the <br />process of selling Lexington School. As part of the purchase agreement, Independent School <br />District No. 623 agreed to remove the 250 gallon tank (exact capacity unknown) and recon- <br />struct the site to the existing conditions prior to the tank removal. STS understands that <br />the age of this tank is at least 25 years of age or more. <br /> <br />Previous work was perfonned at the site by STS and included detennining the approximate <br />location of this underground storage tank and conducting two soil borings. The two soil <br />borings were conducted within the soil envelope of the 250 gallon tank. A description of <br />these work items is defined in the letter to the School District dated September 26, 1989. <br />Soil boring B-3 was conducted over the top of the tank to assure the location of the tank <br />and boring B-4 placed next to the tank. Soil boring B-4 was conducted to a depth of 7 <br />feet. The soils were placed in a clean glass jar and the head space was monitored with an <br />HNU meter. No values above detection limits were identified in the soils. However, from a <br />depth of 5.5 to 6.5 feet color change was observed from brown to green brown. This dis- <br />coloration is common in soils affected by petroleum product and is an indirect indicator <br />that there may have been a past overs pill or piping failure associated with this tank <br />system. Therefore there is a possibility that an unknown amount of contaminated soils may <br />be associated with this tank system. Because of this. removal and treatment for a limited <br />amount of contaminated soils will be included in the specifications for tank removal. The <br />engineering services proposed to be provided by STS Consultants, Ltd. are: <br /> <br />~ <br />:z: <br />m <br />c <br />c: <br />... <br />m <br />U> <br /> <br />o <br /> <br />Preparation of specifications for removal of one 250 gaUon (exact capacity unknown) <br />tank. <br />Monitoring of construction activities. <br /> <br />o <br />o <br />z <br />52 <br />-t <br />6 <br />z <br />U> <br /> <br />o <br />