Laserfiche WebLink
SECOR L, :RNATIONAL INCORPORATED <br /> 0 wwwsecor,com <br /> S ECOR <br /> M e m o r a n d u m <br /> dissipate more slowly due to lower partitioning coefficients and solubility. Site data indicates <br /> that this decrease is taking place, and that further plume growth is very unlikely due to the <br /> evidence that GRO concentrations are already decreasing. <br /> Examination of the geology of the plume centerline ind cates that there is a further barrier to <br /> „ contaminant migration in the form of a thick clay lens a Ktending east from approximately well <br /> ` MW-9M past the MW-11 cluster. This lens of low-permeability material tends to slow plume <br /> migration considerably and is likely a reason why the p ume did not extend farther initially. <br /> Thus, it is extremely unlikely that the current plume will grow any larger; rather, the existing <br /> plume will continue to shrink due to natural attenuation until standards are achieved. <br /> i In conclusion, current trends indicate that benzene and MTBE will likely reach groundwater <br /> :i standards due to natural attenuation within the next 10 years. It is difficult to predict exactly <br /> when GRO will reach standards, due to the factors mentioned above. However, provided that <br /> current trends continue and no further releases occur, the GRO plume will shrink both in size <br /> ,,.and concentration over time. <br /> I:1BP-ARCO\04 BP vaiiey Portfolio144931Reports\NFARIAddendum\COC m deiing tech memo.doc <br /> 2 of 2 <br />