ARCHIVED REPORTS XR0003301 - Laserfiche WebLink

Home Browse Search

5 A discrete pocket of discolored fill material was observed at the eastern end of the former diesel tank cavity, beneath a concrete slab used to support a small shed and sand tower A 6 5-foot-long section of the slab was removed Soil was excavated at the eastern end of the tank cavity to approximately 9 5 feet below grade Two samples (7A and 7B) were collected, as shown in Figure 4 Sample 7A was collected within the fill material at a depth of approximately 6 6 feet, and sample 7B was collected within native soil at a depth of approximately 9 5 feet. These samples were analyzed for TPHd Samples 7A and 7B were reported to contain 500 and 2 7 mg/kg TPHd, respectively 6 Due to the close proximity of the sand tower, further portions of the slab could not be removed and complete excavation of the fill material was not possible However, an underground concrete vault, used for holding sand, is associated with the sand tower and forms a boundary to the east of the observed discolored fill material 7 In order to delineate the areal extent of contaminated fill at the eastern end of the tank cavity near the sand tower, trenches were dug along the north and south sides of the sand tower extending to the former tank cavity Sample 6A was collected at a depth of 2 feet from the north trench, and sample 6B was collected at a depth of 2 feet from the south trench Fill was not encountered in either trench Samples 6A and 6B were reported to contain 7,600 and 2 1 mg/kg TPHd, respectively Due to the elevated levels of TPHd detected in sample 6A, I an additional 1 foot of soil was excavated in the immediate area, and sample 6A-1 was I r collected Sample 6A-1 was reported to contain 18 mg/kg TPHd 8 The discolored fill maternal remaining at the east end of the former diesel tank cavity next to the sand tower is of limited extent and is not expected to represent a threat to the environment or to human health The discolored fill material is beneath a concrete pad, limiting the potential for physical contact with the fill and preventing the infiltration of rainwater which could leach petroleum hydrocarbons downward Additionally, the fine-grained native soil adjacent to and beneath the fill material would to impede potential migration of petroleum hydrocarbons from the fill material ��- 3.2 FORMER WASTEWATER TANK EXCAVATION 1 Although laboratory results for the initial soil samples collected during tank removal were • not reported to contain TPHd, discolored soil was observed along the sidewall of the former wastewater tank cavity Approximately 2 feet of soil was removed from the area 6 ENVIRONMENTAL SOLUTIONS