WORK PLANS FILE 2 - Laserfiche WebLink

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Introduction This work plan is a revision of the Work Plan dated October 4, 2002 . This work plan is a study to see if the MtBE at this station is originating from a leak from the tanks or pumps . The borings will be located around the tanks and pumps. From this work, we will find out if the source of the oxygenates is from this station or being transported on to this site from another source . WORK PROPOSAL AIR TEST WELLS We plan to drill 9 soil gas test borings around the tanks and the pumps, which are impacted with MtBE. The only possible sources of MtBE at this station are from the tanks or pumps. The borings will be 20 or 30 feet deep and soil air samples will be taken in borings SG- 1 to SG-5 at a depth of 13 to 17 feet in a silty clay layer and 25 to 29 feet in a silty sand layer. Soil air samples in borings SG-6 to SG-9 will be taken at a depth of 5 to 9 feet in silty clay layer and 20 to 24 feet in a silty clay and sand layer. We believe the difference in depth will indicate if the gasoline is leaking from the pumps or flowing deeper from another source . Each soil gas boring will be between 20 and 30 feet deep, which will place the soil gas around the tanks silty and a lower silt layer and around the pumps in a silty clay and a sandy silt. The borings will be located within 5 feet of the tanks and the pumps. The borings will be drilled by Fisch Environmental Services . These wells will be drilled with a Geoprobe unit which can obtain the gas samples . Each boring will produce a gas sample which will be tested by GeoAnalytical Laboratories of Modesto , CA. After the testing is completed the borings will be backfilled with bentonite and cement. LABORATORY TESTING The following tests will be performed on the air samples by GeoAnalytical Laboratories , Inc. of Modesto , CA. The samples will be placed on ice in a cooler until they are delivered to the laboratory . Air Sample Tests EPA 8021 BTEX 0 . 3 ug/L EPA 8260 MtBE 1 ug/L Luft 5030 50 ug/L