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' Site Background Information Chapin Brothers Investements, Inc Page 4 of 12 1 the extracted vapors ranged from 35,000 pg/L to 56,000 gg/L ' Converting these values to parts per million volume(ppmv),concentrations ranged from 9,800 ppmv (at 6 hours) to 15,680 ppmv (at 12 hours) Generally, a vacuum of 0 10 is required to successfully ' volatilize subsurface hydrocarbons The maximum vacuum measured at each well was plotted versus the distance of each well from the extraction well Drawing a"best fit" line through the three data points will determine the effective radius of influence at this site, the effective radius of influence at the site appears to be approximately 37 feet It appears that vapor extraction, using an IC engine, would successfully remove a significant volume of petroleum hydrocarbons from impacted soil at the site Furthermore, it is likely that extraction on VE-2 (slant boring) will have a positive influence on impacted soil in the vicinity of MW-3 Dissolved oxygen and ground water depth data collected during the pilot study indicate that IAS, ' combined with SVE should provide a viable alternative for remediation of impacted ground water at the site The ground water depth was increased (depressed) as much as 144 feet in ASO-1 (located approximately 3 feet from AS-1), groundwater depth decreased as much as 0 20 feet in ASO-2 No ' significant change in ground water depth was anticipated in ASO-3 and therefore, ground water • depth was measured only once Dissolved oxygen in ground water was measured in the IAS observation wells at several intervals throughout the IAS test In ASO-1, dissolved oxygen ranged from 84 1%to 87 4%,in ASO-2,dissolved oxygen ranged from 16 0%to 32 9%,dissolved oxygen was measured at 62 4%in ASO-3 It appears that the effective radius of influence for the air sparging wells on-site maybe as great as 20 to 30 feet tThe increased dissolved oxygen and the change in groundwater depths indicate that the Injected air had an influence on all IAS observations wells at the site Although the concentration of petroleum hydrocarbons increased in two of the three observation wells, this may be a results of desorption of hydrocarbons from the Impacted soil in the smear zone or sample collection techniques REMEDIATION WELL INSTALLATION On 19 April 1997, one additional SVE well, VW-7 was installed at the eastern edge of the site to a depth of 15 feet Also six in-situ air-sparing (IAS) points point were installed using two 21-inch long, 3/8-inch I D stainless steel screen implants attached to an anchor tip at 30 feet bsg (IAS-2 through IAS-7) were installed to depths of 30 feet bsg using AGE's van-mounted Geoprobe 5400 soil probing machine Two probe bonngs were completed as IAS points using one 21-inch long,3/8- inch I D stainless steel screen implant attached at 26 feet bsg to an anchor tip Vinyl tubing(3/8-inch ' O D ) was extended from the sparging screen implant to the surface and a filter pack (fine glass • beads)was Installed around the screen implant from a depth of 25 to 30 feet bsg Bentonite sand(#8 Advanced GeoEnvironmental,Inc 1