Final Second Five-Year Review Report Fort Ord Superfund Site ...

With regard to the area within the boundary of the Former Fort Ord, the groundwater remedy, comprised
of the source area GWETS and the HCPP system, is continuing to effectively reduce the total mass and
concentration of COCs in groundwater. Groundwater samples from all A-Aquifer MWs within the
capture zone of the source area GWETS met the clean-up targets in the December 2005 event. Operation
of the source area GWETS was suspended in February 2006 to conduct a rebound evaluation study and
determine if the system can be permanently shut down.
At the northwestern property boundary, the initiation of pumping from the HCPP during July 2006 is
intended to halt the migration of the VOC plume beyond the property boundary. Although the HCPP has
not been operating or monitored long enough to reach definitive conclusions regarding performance, the
initial data suggest that the desired hydraulic control of the plume has been established along the
northwest property boundary.
With regard to the area downgradient from the northwest property boundary of the Former Fort Ord, MW
data from early 2007 show that concentrations of TCE exceeding the aquifer cleanup level extend
approximately 400 feet beyond the boundary of the former Fort Ord. This part of the plume is not being
captured by the HCPP system, although the HCPP system will prevent further migration beyond the
property line. The Army is characterizing the extent of the contamination and evaluating options for
addressing the plume beyond the property line.
Monterey County Ordinance 4011 has been put into effect that regulates water well installation within
either the “Groundwater Prohibition Zone” or “Groundwater Consultation Zone,” which includes the
known groundwater plumes at the former Fort Ord. In addition, the Army has included groundwater use
restriction in the federal deed and has executed a Covenant To Restrict Use Of Property (CRUP)
(recorded with the deed) for all transferring parcels that are located over the groundwater plume. The
deed restriction and the CRUP will prohibit construction of wells for injection or extraction of any
groundwater until the aquifer cleanup levels are attained.
5.3.2 Question B
Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy
selection still valid?
Land use within the limits of the groundwater plume is consistent with the exposure assumptions used for
the development of the aquifer cleanup levels specified in the OU 1 ROD. The standards for site aquifer
cleanup levels were based on state and federal maximum contaminant level (MCL) except where more
stringent values were developed from the human health risk assessment. The MCLs for the OU 1 COCs
have not changed since the OU 1 ROD was signed, thus the aquifer cleanup levels are still in compliance
with, or more conservative than, federal standards. Maximum COC concentrations detected in the OU 1
groundwater monitoring network since the OU 1 ROD was signed are less than the maximums identified
in the OU 1 ROD.
5.3.3 Question C
Has any information come to light that could call into question the protectiveness of the remedy?
As described in above, MW data from early 2007 show that concentrations of TCE exceeding the aquifer
cleanup level extend approximately 400 ft beyond the boundary of the former Fort Ord. The existing
extraction system is not able to capture this part of the plume and the Army is evaluating options to
address this portion of the plume. The HCPP system will prevent further migration beyond the property
line.
Final
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FORMER FT ORD 5YR REVIEW 2007_FINAL United States Department of the Army