ARCHIVED REPORTS_XR0012660 - Laserfiche WebLink

Home Browse Search

/f r Lq w� 1 excavatlon.eLXEAte mentioned In section 5.1, 0.3 ppm is the accepted minimum detection limit for BTHE In the generaI risk appraisal. Since the collected ! soil samples have resldual levels less than 0.3 ppm,the general risk worksheets aro not necessary. The results show that these residual hydrocarbon levels can be left In place without ph,log threat to the groundwater resources In the area. Therefore, r based an the LU FT Hamual leaching poianlial analysis and general risk appraisal, . 111111) LN proposes that the BCA drums and existing soli stockpile bo used as ackfill material for the current open excavation. -5.3 EYALUATIOH OF CROUNOYATER - J The LUFT Manual does not specify maximum allowable hydrocarbon concentrations - ingroundwater; Therefore, for illustrative purposes only, LH will compare the ;j analytical rnsults from the monitoring weit3 to tstabllshed California drinking water standards. �Bepartment of Health Services(UGHS}has established maximum concentration.levels - -(MCL)for-specific organic and Inorganic chemicals (Title 22, Soctlon 64445 of ry the California Administrative Code). Three gasoline constituents are on the list -of regulated heml[als: benzene{MCL-1.0 ppb), ethylbenzene {MCL-500 ppt} and ...� rylenes(MLL=V50 ppb{.-An MLL is a legally enforceable maximum level;therefore, ?- water to be provided for.public o umption cannot contain ccocentratior,leve}, l in excess of the established MCL, ns OOHS has also established action levels for a much bro�dor 71st of chemicals, ry 'These suggested action levels are to he used for guidance purposes only,and are - not legally enforceable maximum concentration l evels. The action level for Toluene is 100 ppb• Yater samples collected from afive monitoring wells showed detectable levels - of petroleum hydrocarbon constitll uents. Levels detectad In MW1 are below'ali of the above MCL and action levels. .Levels detectad in MW3 and 111,14 only exceed MCL - levels for benzene.I Samples collected from MU2 and MW5.lydicate, gasoline �{ constituents in excess of all of the above HCL and action levels. Ln-genet 1, .these levels are several orders of magnitude greater than the regulatory guidelines. As discussed In Section 4 3 area ndmer Flcw, flow jag" across the site. Since MW5 is in the far mertheast� of the site,and does ., ,contain-detectable levels of BTABE and TFII there4s a'corner 6-ern regarding offsite release of these constituents. 1 f. -25- d. _ _ -