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~~ <br />s <br />~r~ ~ ~~w 1J •40 t'. U5 <br />9.0 IDENTIFICATION OF THE 5ELECTED REMIISY <br />The selected remedy for the Offpost OU consists of implementing Alternative N-4 for remedfation of <br />_ groundwater in the North Plume Group. Alternative NIN-2 for remediation of groundwataz in the <br />Northwest Plume Group, and continued operation of the $ondale Containment System consistent <br />with the Irondale DtA. The selected alternatives are described in detail in Section 7 end the <br />Dedaratioa to thr ROD. <br />9.1 Alternatlw N•4: OHpoxt Groundwater Intercept and Treatment System <br />Coastrtretioa of the Offposl Groundwater Intercept and Troatmeat System began in November 1991 <br />r end full-scale system operntioa began is June 1993. Additional detail concernia~g design specifie+ is <br />• contained is the Final Implementation Document for the Groundwater Intercept and 'IYeatment <br />System North of RMA (HLA, 1991). The major components of this alternative are as follows: <br />r Operation of the Offpost Groundwater Intercept and Treatment System <br />- Removal of contaminated UFS groundsater north of the RMA boundary in the First <br />Creek and northerv pa]eochaanels, using Offpost Groundwater Intercept and Treat- <br />ment System groundwater extraction wells <br />- Treatment of the expaded groundwater, using carbon adsorption <br />- Recharge of treated groundwater to the UFS, using Offpost Groundwater Intercept and <br />Treatment System rechazge walk and trenches <br />" - Natural attenuation of inorganic rbloride and sulfate concentrations to meet <br />_ applicable standards for groundwater in a meaner consistent with the on-Post <br />remedial action <br />• Continued operation of the NBCS <br />• Improvements to Offpost Groundwater Intercept and Treatment System and the NBCS, as <br />necessary <br />• Long-term groundwater and surface-water monitonag <br />• Site reviews <br />• Exposure coatrollpro~zsion of alternate water supply u described in Section 7.1 <br />- Well e]osure in conformance with criteria listed is Appendix C, pages C-1 and G-2 <br />'2190.5 40301D Hardln9 La+vsen Associates 9.7 <br />tta7tztses R02 <br /> <br />