On September 26, 2018, EPA issued an OU3 ROD Amendment, which modified the OU3 Selected Remedial Action selected in the OU3 ROD, dated August 10, 2000, at only the Central Sprinkler Parcel portion of the North Penn Area 6 Site. The estimated present worth of the total cost for the Selected Remedial Action, as modified in the OU3 ROD Amendment, is $242,624. EPA recognizes that contaminant levels may rebound and increase in the future; therefore, the estimated total present worth cost ($242,624) includes periodic costs ($99,760) for two additional ERD injection events with post-injection monitoring, if needed. The estimated total present worth cost of the Selected Remedial Action for the Central Sprinkler Parcel set forth in the OU3 ROD Amendment also includes long-term monitoring costs for 10 years after achieving cleanup levels. The OU3 CD Modification modifies the 2005 OU3 CD with Central Sprinkler Corporation, and requires Central Sprinkler Corporation to implement the Selected Remedial Action as modified by the OU3 ROD Amendment, dated September 26, 2018.