ARCHIVED REPORTS - Laserfiche WebLink

Home Browse Search

Job No 4780200 Peg* B 4.0 CONCLUSIONS AND RECOMMENDATIONS Based on our site observations, laboratory reports, and our professional opinion, E2C concludes that soils at the subject site have been adversely impacted by the former presence of gasoline and USTs Elevated levels of TPHg and BTEX were reported from boring B2 which was installed in the former vicinity of a 2,000-gallon gasoline UST The high concentrations of TPHg and BTEX were reported from soil samples collected from 15 and 20 feet bgs. The laboratory reported that TPHg and VOCs (including STEX) were not present in detectable levels from soil samples collected from the 5 and 10 foot bgs in B2 or from any of the other soil borings installed on-site (including the stockpile sample). IWhile drilling B2, we noted that the soil cuttings from an approximate horizon of 12 to 23 feet bgs were very wet (See Section 3. 1), while in-situ soil samples collected from 10 and 15 feet bgs were only damp to moist. The two most likely explanations for this wet zone are that it is a small perched aquifer or, more likely, water which has seeped into soils at this horizon from the runoff water observed in the open excavation next to the boring Possible environmental significance of this wet zone is that, if it is a perched aquifer, it represents a zone of lesser resistance which would allow for a greater dispersion of contamination. Or, if the wet zone is the result of water seeping Iinto the area from the excavation and the water in the excavation is contaminated (which is likely given its proximity to B2), the water is serving as Ia means of transportation of contamination which would not normally be present. It is the recommendation of E2C that this water be pumped from the excavation and further drainage of water into the excavation be prevented. It should be noted here that in the likelihood that the water indeed is the result Iof a perched aquifer, water will seep into the excavation soon after the removal of the existing water. I TPHg was reported from B2 at concentrations of approximately 687 and 693 ppm. A concentration of 100 ppm total petroleum hydrocarbons in soil is IE2 C' Inc January 29, 1993