Completion of the Remedial Design,
Aluminum Company of America Site, Riverdale, Iowa, and Mississippi River Pool 15 Site, near Riverdale, Iowa
The U.S. Environmental Protection Agency (EPA) Region 7 announces the completion of the Remedial Design (RD) and initiation of Remedial Action (RA) activities at the Aluminum Company of America (Alcoa) Site and the Mississippi River Pool 15 (MRP15) Site. These two interrelated sites are located in Riverdale, Iowa.
The Alcoa-Davenport Works facility is an active aluminum sheet and plate rolling mill that has been in operation since 1948. Aluminum production and waste management activities have resulted in ground water contamination at the Alcoa Site. The primary contaminants of concern in the ground water are classified as volatile organic compounds (VOCs). The VOCs include compounds associated with degreasing solvents that were used to clean the aluminum prior to entering the finishing process. Prior waste management activities have also resulted in historical releases of polychlorinated biphenyls (PCBs) to MRP15.
The remedy for the Alcoa Site is ground water containment, which includes the ongoing operation of a ground water containment, extraction, and treatment system (GCETS), source area remediation, ground water monitoring, and institutional controls. The remedy established a Technical Impracticability (TI) zone on the Alcoa property, within which the ground water cleanup is not expected to meet drinking water standards within a reasonable time frame. The performance goal of the remedial action with respect to ground water is containment of ground water contamination through the continued operation of the GCETS so that ground water concentrations outside the TI zone do not exceed the established ground water performance standards. Operation of the GCETS also provides an effective mechanism to permanently reduce the volume of subsurface contamination through extraction and treatment of the contaminated ground water.
The remedy for the MRP15 Site is monitored natural recovery (MNR) with management of on-site media at the Alcoa-Davenport Works. The MNR program will: 1) evaluate PCB concentrations in fish collected from areas near the Alcoa shoreline and reference areas, and 2) monitor sediment elevations and document physical changes along the Alcoa shoreline.
The Remedial Design and Remedial Action activities are being conducted by Alcoa Inc. and its contractors. The Remedial Design/Remedial Action (RD/RA) Work Plan describes the activities that will be taken at the Alcoa and MRP15 sites during the Remedial Action phase.
As part of the construction activities for the Remedial Action at the Alcoa Site, new wells will be installed at a location along the eastern facility boundary. In addition, preferential flow path analysis will be conducted on numerous existing open borehole bedrock monitoring wells that are located near the facility boundaries. Upon completion of these activities, this more extensive ground water monitoring well network will be used to monitor the effectiveness of the ground water remedy. The Long-Term Monitoring Plan (LTMP) component of the RD/RA Work Plan provides a description of the ground water monitoring well network and details of the sampling/monitoring activities.
The GCETS Plan component of the RD/RA Work Plan describes the operation of the system that is currently being used to provide containment, extraction, and treatment of contaminated ground water. The treated water from the GCETS will be monitored to ensure compliance with the effluent performance standards. Influent and effluent monitoring data will also be used to model air emissions from the GCETS. A new shallow tray air stripper configuration for the GCETS is being installed by Alcoa to replace the existing tower configuration.
As part of the construction activities for the Remedial Action at the MRP15 Site, sediment monitoring pins will be installed along portions of the Alcoa shoreline. Sediment monitoring events will be conducted concurrent with the future fish sampling events. The initial fish sampling event that will be conducted during the Remedial Action phase is scheduled for September 2012. The MNR Program Plan (MNRPP) component of the RD/RA Work Plan provides details regarding fish sampling and sediment monitoring activities.
FOR MORE INFORMATION
The RD/RA Work Plan and other site-related documents are available at the following location:
EPA Region 7 Office
901 N. 5th Street
Kansas City, Kansas
If you have questions about the remedial design or the remedial action, please contact:
Community Involvement Coordinator
Office of Public Affairs
U.S. EPA Region 7
901 N. 5th Street
Kansas City, KS 66101