ARCHIVED REPORTS_XR0012651 - Laserfiche WebLink

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. _ "T r l I On January 27, 1987, the excavation was examined, and it was seen that the sides of the excavation were caving in, thus exposing and removing support from a 4" gas supply line. In order to prevent damaging or rupturing to the gas line, it was decided to back-fill the pit. This action provides support for the gas line as well as a working surface for Future soil samalfna. Proposed Proqram of Investigation As the soil lander the excavated tanks is known to contain diesel and aromatic hydrocarbon residues, it is proposed to perform a soil investigation underneath and adjacent to the underground tank site. In subsurface work involving Penetration through contaminator} soil, the work should be performed in such a manner to Drevent the introduction of contamination into underlying groundwater. Therefore, the soil investigation will be to a depth of 30 Feet and will not penetrate into the groundwater. Should the findings of the soil investigation warrant, then groundwater duality will be investigated using appropriate methods. All soil borings will be sealed to insure that there is no inadvertent contamination of the groundwater. The proposed program consists of 3 soil borings, collection of soil samples, and laboratory analysis for diesel and aromatic hydrocarbon residue. One of the soil borings will be through the center of the tank area and the other two soil borings will be located 10 feet from the perimeter of the excavated areas. The boring locations are shown in Figure I. Soil boring R-1 will be made through the backfilled excavation with the first soil sample being collected at a depth OF 15 feet. As the sol]..._has_been_..excavated-to-a-depth-of--14--feet-during- ------- --- Previous excavation, the 15-foot depth will be the first available sample of t . undisturbed soil underlying the tanks. Subsequent soil samples will be gathered -2-