2000-04-05_PERMIT FILE - M2000002

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_„ ,,,,_ , ,,; ,,;,, rtpr S 2000 13 ~ 47 P, 07 I?.rn,~ ~tc~~ Q.a~ r M M M= • ~ .-. -- M_ ._ Identification of the Seleeied Remedy 9.3 4dditional Components of rho Selected Remedy Ia accordance with the NCP, the pUbllC had 8D Opportunity to review cad comment oa the selected remedial alternatives presented in the Proposed Plea In response, tho Parties held additional discussions to determine hots best to addreu these comments. These discussions resultod is darificationa and minor technical changes that do not significantly alter the overall scope, perfor- mance, or cost of the Of;lwst preferred alternative. Because the main focus of the Oftpost preferred alternative is unchanged, and the additional actions only clarify and enhance the prefeaed alternative, the changes were not considered to be significant. The discussions also involved broader issues which were resolved in a document entitled "Agzaement for a Conceptual Remedy for the Cleanup of the Rocky Mountain Arsenal," dated Juno 13, r 995. With regard to the Offpost azea. the Parties agreed to several additional components which are an integral part of the overall remedy but aze proposed for inclusion in the Onpost ROD. Many of these components are in the Onpost Proposed Plan, which is available for public comment from October 16, 1995, through January t9. 1985. The additional components added in response to public comment end as pan of the Conceptual Remedy Agreement discussions include: • The U.S. Army and Shell Oil Company agree to continue monitoring and to complete an assessment of the NDMA plume by June 13,.1996, using a 20 ppt method detection limit • The U.S. Army and Shell Oil Company agree to prepare a feasibility study of potential aetioa+, both onpost cad at the houndary, or adjacent to the boundary in order to achieve NDMA remediation goals at the RM.9 boundary and to use 7.0 ppt PRG or a certified analyti- cal detection level readily available at a certified commercial laboratory icurrently 33 pptl. • The U.S. Army and Shell Oil Company agree to revegetate approximately 160 acres located in the southeast portion of Section 14 and the southwest portion of Section 13 as depicted in Figure 9.1. Revegetation~+-ill ineolve tilling and seediryg. No sampling will be conducted before or after revegetatioa. Existing soil risks in the azee to be revegetatedfall within hYA's established acceptable risk range and revegetation is not necessary. However, the U.S. Army and Shell Oil Company ogee to the recegetation program as part of the Offpost settlement. 'atoos aozoro Heeding Lawson AssoeiaDes 9.5 .. n~.~•mc orn