USACE Alaska, Groundwater Monitoring, Amaknak Pre-WWII Tank Farm FUDS

Brice conducted groundwater monitoring, monitoring well installation, monitoring well decommissioning, and a remedial action-operation (RA-O) phase at the Amaknak Pre-World War Two (WWII) Tank Farm, Formerly Used Defense Site (FUDS). The project objectives were to verify that the selected remedies are still protective of human health and environment, and to provide the basis for the current periodic review. Since the 2007 Decision Document, groundwater monitoring was conducted at the Pre-WWII Tank Farm site in 2008, 2009, and annually from 2012 to 2014. Groundwater monitoring will continue to be conducted every 5 years to coincide with periodic reviews.

Brice optimized groundwater monitoring as follows: five wells were decommissioned, four wells were installed, and multiple wells were repaired to ensure that groundwater monitoring at the site remains effective for sampling events in the future. The wells were checked for free product and sampled, if possible. Free product was found in three wells. Groundwater sampling was conducted in 10 wells. All results were below the cleanup levels defined in the 2007 Decision Document.

Brice used MAROS to evaluate the stability of the DRO and RRO plumes, and DRO and RRO trends were evaluated graphically for individual wells with multiple years of sampling since the remedy was implemented. The graphical evaluation of trends indicates that DRO and RRO concentrations are decreasing or stable in individual wells. The results from this groundwater monitoring event show that not all concentrations or plumes are decreasing (i.e., some are stable or show no trend).

We collected and evaluated natural attenuation parameters using BIOSCREEN on the currently dissolved contaminant mass in groundwater. The results indicated that contaminants are attenuated through solute transport and biodegradation.

As part of this effort, we installed new covers on the Building 551 crawlspace openings to ensure that the remedial action objectives for the Amaknak Pre-WWII Tank Farm continue to be met and comply with the Decision Document. The plywood covers installed in 2007 were replaced with concrete wallboard as a more permanent solution to eliminate exposure to contamination present in the Building 551 crawlspace.

Brice also supported public involvement at the RAB initiation meeting by providing results and figures from this event for members of the public to view.