Laserfiche WebLink
31 October 2002 <br /> AGE-NC Project No 95-0184 <br /> IPage 4of5 <br /> I4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site, AGE concludes the following <br /> IGround water levels were as high as approximately 22 feet above the screened Intervals of <br /> all the monitoring wells The ground water gradient ranged widely,from 0 025 ft/ft along the <br /> I northwestern edge of the site to 0 0033 ft/ft in the southern portion of the property The <br /> ground water flow direction vanes from northwest near the northwest corner of the site to <br /> southeast along the south side of a ground water finger in the northern portion of the site,the <br />' flow direction over much of the site is generally northeast <br /> • Detectable concentrations of TPH-g were found in all of the ground water wells sampled <br />' <br /> Sowe,BTEX compounds were found in all ground water samples,except for MW-7,these samples <br /> contained one or more analytes at concentrations above California's Maximum Contaminant <br /> Levels (MCLs) <br />' No free product was measured during this sampling event,however,most of the well screens <br /> are drowned and are not likely to produce direct evidence of free product <br /> • The oxygenated volatile organic compound MTBE was detected at a concentration of 550 <br /> gg/l (VW-4), no other oxygenated volatile organics were detected at concentrations above <br /> laboratory reporting limits <br />' The concentrations of MTBE, EDB and 1,2-DCA in the ground water samples exceed the <br /> DHS MCLs for drinking water <br />' Naththalene, n-propylbenzene, 1,2,4-trimethylbenzene and 1,3,5 tnmethylbenzene were <br /> detected in ground water samples at concentrations above the DHS-recommended drinking <br /> water action levels <br />' The vertical and lateral extent of impacted soil and ground water has not yet been defined <br />' <br /> 5.0. RECOMMENDATIONS <br />' Based upon data collected from the site, AGE recommends continued ground water monitoring <br />' Two of four proposed cone-penetrometer test(CPT)soil borings were advanced to a maximum depth <br /> of 180 feet bsg on 13 to 15 November 2001 to assess the vertical and lateral extent of impacted soil <br /> and ground water, to define hydrogeologic flow units at the site, and to optimize locations of <br />' additional monitoring and extraction wells, however, ground water was s Ill q cted at 180 feet <br /> AGE is preparing an addition to the original Work Plan Addendum -�i ry 2� 2 to advance the r,— <br />•� two remaining CPT borings to 200 feet bsg and install multilevel monitoring wells 411g/Ds <br />' Advanced GeoEnvironmental,Inc <br /> 1 <br />