Remedial Action Plan - Rochford Field - Newhall Remediation Project

On-site soil washing
Bioremediation or land farming
On-site or off-site thermal desorption or incineration
In-situ solidification or stabilization.
The remedial “Alternatives” which were considered as part of the RAP evaluation included:
Alternative 1 – Complete excavation of all fill material on site that exceeds regulatory criteria:
All material that exceeds RDEC and/or PMC would be excavated to an average depth of
approximately 8 ft. and either temporarily stockpiled on site or loaded directly into trucks for
transportation for off-site disposal (permitted landfill or other no-cost disposal alternative
approved by CTDEEP.) In addition to the average thickness of 2 ft of earthen fill, we assume
that an average contaminated fill thickness of 6.0 ft at Rochford Field exceeds RDEC and
PMC. The contaminated fill must be disposed of at a permitted landfill. Clean fill would need
to be imported to the site to offset the volume of material being disposed of offsite.
Groundwater would be addressed via natural attenuation groundwater monitoring.
Alternative 2 – Excavation of upper 4 ft of fill material: This option would be used in order to
render remaining soil (below a depth of 4 ft) that exceeds the RDEC inaccessible, would use
variances or alternative criteria to address soil exceeding PMC. All material to a depth of 4 ft
would be excavated and either temporarily stockpiled on site or loaded directly into trucks for
transportation for off-site disposal (permitted landfill or other no-cost disposal alternative
approved by CTDEEP.) In addition to the average thickness of 2 ft of earthen fill, it was
assumed that the remainder of the contaminated fill to the depth of 4 ft also exceeds the RDEC.
Clean fill would need to be imported to the site to offset the volume of material being disposed
of offsite. Upon completion of the work, an ELUR would be recorded on the land records.
Groundwater would be addressed via natural attenuation groundwater monitoring.
Alternative 3 – Excavation of upper 2 ft of fill material and installation of an asphalt cap: This
option would be used in order to render remaining soil (below a depth of 2 ft) that exceeds the
RDEC inaccessible, would use variances or alternative criteria to address soil exceeding PMC.
All material to a depth of 2 ft would be excavated and either temporarily stockpiled on site or
loaded directly into trucks for transportation for off-site landfill disposal and or recycling. It
was assumed that all fill to a depth of 2 ft exceeds the RDEC. Clean fill would need to be
imported to the site to offset the volume of material being disposed of off-site. The clean fill
and a 6 in. layer of processed aggregate would be covered with a minimum 3 in. thick paved
surface. The paved surface would also require the installation of storm drains, and potentially
additional storm water management facilities, to control the additional surface water runoff.
Upon completion of the work, an ELUR would be recorded on the land records. Groundwater
would be addressed via natural attenuation groundwater monitoring.
Alternative 4 – Installation of a 2 ft thick engineered cap placed on the ground surface and
designed in accordance with the RSRs: The RSRs allow placement and maintenance of a
CTDEEP-approved engineered control as a means to achieve RSR compliance. The engineered
control would consist of an impermeable HDPE membrane and drainage system to be installed
over the contaminated soil. The membrane would be underlain by a 6 in. “cushion” layer of
imported sand or screened earthen fill, and covered by a 12 in. layer of imported sand. The
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