ARCHIVED REPORTS XR0005968 - Laserfiche WebLink

Home Browse Search

Only very low concentrations of these contaminants were detected in soil samples from these wells, however. 3.0 TANK REMOVAL Mr. Peters retained SEMCO to secure the tank removal permits and perforin the removal. SEMCO used a Hundai excavator to remove the asphalt and expose the UST's on March 2; the removal was performed on March 3. The UST's were side by side and oriented north-south in the excavation (Figure 2). Groundwater entered the excavation, so Upgradient measured the depth to water in monitoring well KF-2. At the time of the removal, the depth was 4.2 feet,approximately 10 feet above its previously known shallowest depth. Prior to their removal, an inspector from SFD used an LEL meter to check the oxygen level in the tanks, and reported that the levels were slow to stabilize, suggesting a possible leak_ At approximately 10:00 a. m., the inspector certified the UST's safe for removal. The western tank was the first to be removed. Initially, it appeared to be in very good condition, with only minor rusting and pitting. After it was examined by SFD, EHD, SEMCO, and Upgradient, the excavator operator lowered it onto a flat bed truck for transport. The eastern UST was then removed and examined, and the fire inspector discovered a hole in each end of this tank. Both holes were located at seams where the end caps had been welded to the body of the tank. One hole was approximately 1/8 inch in diameter; the other was elliptical, measuring approximately 1/4 inch by 3/4 inch. This prompted further examination of the western UST, and two holes were also found in this tank. Again, both holes were located near the bottom of the tanlc along the end seam. The east tank was then placed on the flat bed truck and transported to SEMCO's yard in Modesto. 4.0 SAMPLE COLLEC71ON After the UST's had been removed, groundwater began draining from the (shallower) western half of the excavation to the (deeper) eastern side. Mr. Kith directed Upgradient to collect a water sample from each side. Upgradient lowered a disposable plastic bailer into the excavation and collected five 40-m1 vials from the east side and three vials from the west side. These were labeled and placed into a cooled ice chest. Mr. Kith then directed the excavator to expose fresh, native soil at the base of each wall of the excavation so that soil samples could be collected. Samples were collected from the walls at both ends of each tank, and Upgradient used a slide hammer loaded with brass sample tubes to obtain each sample from the excavator bucket. Sample WS-1 was collected at a depth of 8 feet, ES-1 and EN-1 at 13 feet, and WN-1 at 14 feet. All samples were covered with Teflon sheets and plastic end caps, and then placed into the ice chest. 2