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

which is now available for unrestricted use (IT, 2001a). The remaining areas of the landfill (Cells B, C,
D, E and F) have been covered by a landfill cap constructed after consolidation activities were completed.
A seven-acre portion of Cell E (Interim Cell E) was kept open to allow the placement of additional waste
from other Fort Ord remediation sites (Army, 1997a). The landfill cap was placed over the Interim Cell E
in December 2002.
Groundwater Treatment
A groundwater treatment facility was constructed in 1995 to remediate groundwater underlying the
landfill. Remediation is expected to take about 30 years. During the operation of the treatment system,
groundwater is sampled to confirm that the treatment system is operating effectively. Since 1995, water
samples and water levels from groundwater MWs have been collected every three months. This
information has been compiled into quarterly and annual reports to show the long-term trends of system
operation. The groundwater plume as of July 2006 is shown on Plate 3.
6.2.3 System Operations and Maintenance
Landfill Cap
O&M of the landfill includes inspection and maintenance of the landfill cover (vegetative cover and
geomembrane), slope stability, survey monuments, settlement plates, erosion and drainage control, and
security fence. Landfill gas monitoring to evaluate subsurface landfill gas migration in the perimeter
probes has been ongoing since June 2000.
Groundwater Treatment
O&M have kept the OU 2 groundwater treatment system functioning in accordance with design
parameters since the inception of operations in 1995. The OU 2 groundwater remedy is operated in
accordance with the Operation and Maintenance, Groundwater Treatment Systems, Former Fort Ord,
California (Harding ESE/IT, 2001a) and Sampling and Analysis Plan, Operable Unit 2, and
Sites 2 and 12 Groundwater Treatment Systems, Former Fort Ord, California (AGSC, 2004). O&M
activities are summarized annually in treatment system data summary reports. The most recent annual
report describing OU 2 O&M is 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). To date, the system has processed over 3.35 billion gallons of water and removed over
496 pounds of COCs, of which approximately 98 percent are TCE, cis-1,2- DCE,
1,1- dichloroethane (DCA), PCE, and chloroform. In 2005, all COCs were below the allowable treated
water discharge limits in samples obtained from OU2 groundwater treatment plant (GWTP) effluent
stream for the entire reporting period. The system operates continuously except for periods of routine
maintenance, carbon servicing, and replacement of worn equipment. To date, the system has been in
operation approximately 99.5 percent of the time. Carbon replacement in the system has occurred
approximately every 4 to 6 months since operation began.
The OU 2 groundwater treatment system originally consisted of carbon adsorption followed by catalyzed
ultraviolet chemical oxidation (UV-Ox) polishing. The carbon adsorption was accomplished using two
20,000-pound carbon vessels connected in series. The original system extracted water from two Upper
180-Foot Aquifer EW and 13 A-Aquifer EW to produce a total flow of approximately 765 gallons per
minute (gpm). Following treatment, the extracted water was injected back into either the A-Aquifer or
Upper 180-Foot Aquifer.
Expansion of the OU 2 treatment system was initiated following discovery that the aquifer area with
COCs greater than aquifer cleanup levels was larger than originally recognized during the groundwater
treatment system design. Hydraulic capture of the resulting plume by the original system was not
complete, and a system expansion was initiated to enable complete plume capture and fulfill the
Final
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FORMER FT ORD 5YR REVIEW 2007_FINAL United States Department of the Army