ARCHIVED REPORTS_XR0008817 - Laserfiche WebLink

Home Browse Search

02 June 2004 AGE-NC Project No 99-0645 Page 4of5 toluene, 160µgll ethylbenzene,990µg/1 xylenes,and MTBE was detected in all the samples ranging from 730 µg/1 to 860 µg/1 Toluene and total xylenes were detected in one sample collected from VWIA on 06 October at a concentration of 0 39 µg/1 and 0 29µg/1,respectively No other analytes were detected at or above laboratory reporting limits in the soil vapor samples The shallow test results indicated the flow rate was initially measured at 42 cfin(standard cubic feet per minute) and the maximum observed was 75 cfin OV readings ranged from 923 ppm to 1,100 ppm Induced vacuum measured at the extraction well V W 1 B ranged from 20 to 32 inches of water On 06 October 2003, the Iower screened vapor extraction test indicted that the flow rate was measured between 25 cfin and 31 cfin, a much lower flow was observed OV readings ranged from 1 2 ppm to 2 5 ppm, which was consist across the pilot test Induced vacuum measured at the extraction well (VW1A)was always greater than 100 inches of water During the shallow soil vapor extraction pilot test(18 September)the greatest induced vacuum was measured in the observation point nearest the extraction well, at 0 60 inches of water in wells VW2 and VW3 The lowest vacuum was measured in MW-3,approximately 30 feet west of the extraction point and screened much lower in the stratigraphy at the site, however, sufficient induced vacuum was observed to the monitoring wells to demonstrate that a vertical connection may exist across the vertically separated layers at the site During the deeper soil vapor extraction pilot test (06 October) the greatest induced vacuum was measured in the observation point nearest the extraction well, at 0 45 inches of water in well MW-1R The lowest vacuum was measured in VW2 and VWIB, approximately 20 feet west of the extraction point and screened above the lower stratigraphy at the site Again, sufficient induced vacuum was observed in the monitoring wells and also in the upper soil vapor extraction wells, to demonstrate that a vertical connection may exist across the vertically separated layers at the site AGE plotted in a logarithmic scale,the maximum vacuum measured at the observation points during the pilot test versus the distance from the extraction well The effective radius of influence was determined by drawing a best-fit line though these data points to correlate distance to vacuum data At a vacuum potential of 0 10 inches of water, the radius of influence is approximately 30 feet for the lower screened well (VW1A) and radius of influence is approximately 40 feet for the upper screened well (VW1B), at an induced vacuum potential of 10 inches of water, the radius of influence is 20 feet for well VW1A and approximately 25 feet for well VW1B Further, a vacuum potential of 10 0 inches of water the radius of influence is less than 10 feet Based upon an effective vacuum potential of 0 1 inches of water, the calculated effective radius of influence at the site will be 30 feet up to almost 40 feet for the upper screened vapor well The majority of the residual impacted soil would be collected within the 40 foot radius of influence Advanced GeaEnnronmenta!