Laserfiche WebLink
09/02 '00 WED 17 04 FAX 19289469968 ERMWEST QVC X1020 <br /> P A G E 3 <br /> (1,2-OCA);1,3,5-trimethylben.zene(7.,3,5-TMB), and 1,2„4- <br /> trimethylberi7-ene (1,2,4-TMB)z <br /> All of these constituents are commonly associated with weathered <br /> gasoline, and all of these constituents were considered constituents of <br /> potential concern for the purposes of the HRA <br /> Soil and ground water data for the subject properties included analysis of <br /> total petroleum hydrocarbons(TPI-1) However,both ASTM(1946)and <br /> USEPA(1989)recommend that evaluation of chemical tztixtures should <br /> focus on specific chemical constituents (e g., benzene) that may be present, <br /> rather than on an evaluation of the chemical mixture_ Tim <br /> recommendation is based ort the following <br /> m The boxicnty of nzrxtu res may be highly variable,particularly in the case <br /> of weathered materials such as those present at these sites. <br /> ® Little infox matroat is available to characterize the toxicity of mixtures <br /> The toxicity of mixtures is largely related to the presence of specific <br /> constituents <br /> For these reasons, this HRA focused ort an evaluation of the sped <br /> constituents present (e.g, benzene) However,with regard to the TPH <br /> detections,it as worth noting that weathering appears to have restdwd in <br /> the toss of the more volatile(and typically more bDxxc)fractions,as <br /> reflected in tli a most recent sampling event Furthermore, as will be <br /> discussed in the following sechoA the orpportunxty for any exposure to <br /> constituents of potexitml concern is limited both by land use and by the <br /> infrequent occurrence of residual compounds <br /> IDEN1'IFIC4TION Of:REALISTIC EXPOS MW PATHWAYS <br /> The foIlowing subsections describe land use infozmation for the subject <br /> properties,discuss potential exposure pathways for soil and ground <br /> water,and summarize the realistic exposure pathways for the subject <br /> properties <br /> x Idenb catrotn of these compounds was based on mformaton provided lar the <br /> Ckr3ure Report TRM,1999)reggardm&the results of ground water sampling <br /> conducted ager oxygen=Uwrab g compounds were introduced Into the <br /> moratormg system to enhance natural degradation processes <br />