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SEMCO • 0 <br /> GENERAL & ENGaINEERING CONTRACTORS <br /> August,1990 <br /> 3.0 EXCAVATION AND REMOVAL <br /> OF FUEL STORAGE TANKS <br /> Two underground fuel storage tanks were exca- 1990, D. Light delivered the soil samples to <br /> vated and removed from the site on August 10, California Water Labs (CWL),a DHS-certified <br /> 1990 under the supervision of the San Jouqin hazardous materials testing laboratory, for <br /> County Enviromental Health Department. The analysis. SEMCO requested the laboratory to <br /> tanks contained regular gasoline fuel and diesel. analyze samples from the base of the excavation <br /> Inventory records were available for inspection. for total petroleum hydrocarbons (volatile aro- <br /> The dates of tank installation could not be deter- matic organics) (EPA Method 8020), and total <br /> mined. The owner of the tanks is M&M Ditch- recoverable petroleum hydrocarbons as gaso- <br /> ing line (EPA DHS:GC-FID) and diesel (EPA <br /> Method 3550/GC-FID). These are the labora- <br /> It was determined that the tank was dry before tory testing procedures recommended under the <br /> removal procedures were begun.The tanks were LUFT Field Manual guidelines. <br /> triple rinsed with water and purged with dry ice <br /> to remove explosive vapors.The tanks appeared 4.0 RESULTS <br /> to be in good condition with no obvious signs of Summaries of the analytical results are pre- <br /> severe rusting or pitting. The piping and filler sented in Tables 1,2,and 3. Review of the labo- <br /> vents were not deteriorated.An inspection of the ratory reports pertinent to the tank excavation <br /> excavation, following tank removal, revealed activities conducted at 775 W. Second Street, <br /> areas of discoloration and the odor of petroleum indicates further investigation is required. <br /> products. <br /> Laboratory analyses confirmed detectable lev- <br /> els of petroleum hydrocarbon contaminants in <br /> the collected samples. Augeas Corporation per- <br /> sonnel collected soil samples from the native <br /> soils approximately one to two feet below the <br /> bottom of the tank cradle,at a depth of approxi- <br /> mately ten feet. Sampling locations are detailed <br /> as follows: <br /> One sample from the east end and one from the <br /> west end of each tank. <br /> Samples were collected with a drive sampler, <br /> contained in sealed brass tubes, labeled, then <br /> stored in an iced container. Chain-of-custody <br /> procedures were observed.Locations of the for- <br /> mer tanks are shown in Figure 1.On August 10, <br /> 3 <br />