FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Geologica[Tlecknics Inc. Page 2 Project No.: 646.2 Hayres(Manthey) Tank Investigation Report June 26, 1998 Gabriel, the plant maintenance supervisor, was contacted and he showed GTI where the two 1000 gallon USTs were located and how they were orientated. Del-Tech used a backhoe to excavate trenches to investigate the following features: • Pump island area and product pipe line from pump island to USTs • Two 1,000 gallon USTs • Two 10,000 gallon USTs The trenches were excavated to 10 feet below ground surface. Observation of soil and evidence of contamination were made and soil samples were collected at the capillary fringe. The soils beneath the site consisted of clayey sand and areas where the tanks were located were backfilled with gravel and sandy loam. While excavating the pump island, two former subsurface facility features were found. These are reviewed below: 1. A former truck service pit was found to be located in the area of the former pump island. This pit had been filled with dirt. Upon excavation, the bottom of the pit was found to be intact and no evidence of contamination was observed. 2. A former septic tank was found immediately on the west side of the service pit and appeared to have been the location of the former pump island. The top and west wall of the concrete septic tank had been broken out and electrical conduit was observed running underground from the power pole into the area of the former septic tank. A drainpipe was also observed running from the shop to the septic tank. Dirt excavated from inside the septic tank was observed to be dark stained and contained an old weathered hydrocarbon odor. A trench (TK 10,000 E) dug 10 feet west of the septic tank and right at the east end of the two 10,000 gallon USTs) showed heavily contaminated soil below 7 feet and groundwater contamination. Just above groundwater was a large "burial ground" of chicken bones. < Chemical test results showed that the contamination in the soil was old weathered degraded gasoline. '—z:a-- 41, motor oil, solvents, or oxygenated fuel blending compounds were present. Since contaminated soil of the sidewalls sloughed into the trench, a sample of the groundwater was not collected. Two 1.000 USTs Test results of the two 1,000-gallon USTs show that only a trace amount of MTBE was found in the soil sample at 10 feet (sample no. TK 1000 SW 10 ft). This data suggests that an insignificant release of gasoline occurred and possibly took place during tank removal. Test results of the stockpiled soil show that a minor amount of diesel is present in the southern sample. Two 10.000 USTs Test results of the two 10,000-gallon USTs (TK 10,000 E & TK 10,000 W) show that no contamination was found that could be linked to releases from these tanks but was probably sourced from the septic system. The reasons for this interpretation are: 1. The gasoline detected in this sample is old, degraded, and has been altered from its original composition. 2. The tanks were removed only 9 years ago which is probably not enough time for the degradation to proceed to this extent.