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

6.3 Technical Assessment
6.3.1 Question A
Is the remedy functioning as intended by the decision document?
Landfill Cap
The landfill cap is functioning as intended.
Groundwater Treatment
The OU 2 groundwater remedy is functioning as intended. Both the original system installed in 1995 and
the expanded system completed in 2001 achieved the groundwater extraction and treatment design
parameters described in design documents. System operation has been relatively constant since system
startup in 1995. Details regarding operation and system performance are described in the Annual
Groundwater Treatment Systems Operation Data Summary Report, January through December 2005,
Operable Unit 2 and Sites 2/12, Former Fort Ord, California (AGSC, 2007).
Statistical evaluation of data obtained from OU 2 treatment system influent samples indicate that
concentrations are generally decreasing over time. The influent chemistry data indicates that the OU 2
groundwater remedy is effectively reducing the total mass of COCs in groundwater, and is functioning in
accordance with the objectives stated in the OU 2 ROD (Army, 1994b).
The expanded OU 2 groundwater remedy is operating at the designed flow rates. Based on monitoring
performed since system modification, it appears to have achieved hydraulic capture of the groundwater
containing COCs at concentrations above aquifer cleanup levels except at the eastern edge of the plume
where two additional wells have been installed for capture. The groundwater contaminant mass within
the hydraulic capture area is expected to be adequately addressed by the existing remedy.
Opportunities for future system optimization include discontinued groundwater pumping from individual
wells where cleanup goals (aquifer cleanup levels) have been attained. Ending extraction at an individual
well will allow for increased extraction from other existing wells and will reduce O&M costs associated
with the well.
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 CRUP (recorded with the deed) for all transferring
parcels that are located over the groundwater plume. The deed restrictions and the CRUP will prohibit
construction of wells for injection or extraction of any groundwater until the aquifer cleanup levels are
attained.
6.3.2 Question B
Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy
selection still valid?
Landfill Cap
The exposure and toxicity criteria used to evaluate human health risks are still valid.
Final
6-5
FORMER FT ORD 5YR REVIEW 2007_FINAL United States Department of the Army