REMEDIAL ACTION WORK PLAN OPERABLE UNIT 2, LANDFILL ...

previous field studies. Additional gas probes encountered during or prior to earthwork will be
removed in accordance with the procedures outlined below. The procedures set forth in this
section are intended to comply with regulatory agency requirements for legal destruction of water
wells as promulgated by the State of California Department of Water Resources (DWR) Water
Well Standards Bulletins DWR 74-81 and 74-90, Monterey County Ordinance 3316, and IT’s
Standard Operating Procedure (SOP) 8.3. Additionally, monitoring well abandonments will be
performed under permit issued by the County of Monterey Department of Health, and under the
direction of a California registered geologist. Since the 20 documented probes located within the
landfill areas terminate within six feet of existing grade, there are no formal regulatory protocols
to be implemented during probe removal.
Existing monitoring wells and gas probes are shown in Figures 2-8 and 2-9. A fourth well (MW-
0U2-1 O-180) located within the landfill area was abandoned in August 1995 in conjunction with
previous field activities of the 0U2 groundwater remedial system installation. Monitoring wells
existing within the limits of the earthwork are identified as:
● MW-0U2-1 O-A
● MW-0U2-1 0-400
● MW-0U2-1 l-A.
The known gas monitoring probes within the limits of the earth work are identified as GP-OU2-
001 through GP-0U2-020.
Well destruction and probe removal procedures are discussed below.
2.4.1 Monitoring Well Destruction
The destruction of monitoring wells will be in accordance with Monterey County Department of m
Health. Well destruction will be completed by filling the well casing with a cement bentonite
grout. Placement of the grout will be accomplished by pumping through a tremrnie pipe placed
at the base of the well casing. Prior to placement, each well will be sounded to measure the total
depth of the well and to ensure no obstructions (such as dedicated pumps and piping) exist within
the well. Logs of the wells will also be reviewed to confirm well depths, estimate filter pack
volumes and calculate minimum total volumes of grout necessaty to seal each well. A filter pack
,--,>, porosity of 30 percent will be used to calculate the volume of the annulus surrounding the
screened interval of each well. Grout material used to fill the well will consist of one sack of
SI16-24-961SACTERCITTORD 0U21R4WP.RVI
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