Laserfiche WebLink
Std <br /> ' L& M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Soil Vapor Sampling <br /> ' October 27, 2010 <br /> 4.2.2 APSV Soil Vapor Concentrations <br /> Soil vapor sampling data collected during the third quarter 2010 sampling event is provided in <br /> Table 25 and shown on Figure 35. TPHg was detected in two soil vapor samples at <br /> ' concentrations of 2.4 parts per million by volume (ppmV) (APSV-1) and 2.7 ppmV (APSV-9). <br /> No other of the requested analytes were detected at or above the MRL in the APSV wells during <br /> third quarter 2010. <br /> ' 4.2.2.1 APSV Trends <br /> APSV-1 and APSV-9 had slight detections of TPHg (2.4 ppmV and 2.7 ppmV, respectively) <br /> during the third quarter 2010 sampling event, but historically these sampling points have been <br /> none detect. For all other APSV wells, there were no detections of the requested analytes at or <br /> above the detection limits in the samples collected from the wells for the fourth consecutive <br /> quarter (4Q09 through 3Q10)., Concentrations of TPHg typically exhibit a decreasing trend, with <br /> the exception of the slight detection in the two wells (APSV-1 and APSV-9) during the third <br /> ' quarter 2010 event (Table 25, Figure 36, Figure 37, Figure 38). <br /> 4.2.3 UPSV Soil Vapor Concentrations <br /> Soil vapor sampling data collected during the third quarter 2010 sampling event is provided in <br /> Table 25 and shown on Figure 35. TPHg was detected in three soil vapor samples at <br /> concentrations of 7.3 ppmV (UPSV-3), 6.6 ppmV (UPSV-3D), and 416 ppmV (UPSV-5). No <br /> other requested analytes were detected at or above the detection limits in the samples collected <br /> from the UPSV wells during 3Q10. There have been no fuel oxygenates detected in UPSV <br /> wells since their installation. <br /> 4.2.3.1 UPSV Trends <br /> ' UPSV-3 had a slight detection of TPHg (7.3 ppmV) during the third quarter 2010 sampling <br /> event; previously, this sampling point had two consecutive quarters of non detect TPHg <br /> ' samples. UPSV-5 had a detection of TPHg (416 ppmV) during the third quarter 2010 sampling <br /> event, but has been showing a decreasing trend during the past five quarters. For all other <br /> UPSV wells, there were no detections of the requested analytes at or above the detection limits <br /> ' in the samples collected from these wells for the fourth consecutive quarter (4Q09 through <br /> 3Q10). As shown in Table 25, TPHg has historically decreased in wells UPSV-1, UPSV-2, <br /> UPSV-3, and UPSV-6 base line sampling in July 2005 and since start up of the on-site <br /> ' remediation system on May 31, 2007. Additionally, benzene, ethylbenzene, and total xylenes <br /> have decreased to below detection limits which are complimentary to the decreasing trend to <br /> TPHg observed in well UPSV-6 (Figure 39). There have been no other apparent trends <br /> associated with reported concentrations in the UPSV wells. <br /> ' h7iide ler\W SWd wn(Panel 2A 4l 5)\ReportsWMR@010 QIO\3QIOQSSRQRSRQMR StDAWn_FINALAm 4.2 <br />