Remedial Action Plan - Rochford Field - Newhall Remediation Project

3. REMEDIAL ALTERNATIVE ASSESSMENT AND REMEDIAL ACTION PLAN
3.1 Regulatory Compliance
In accordance with the Consent Order, Haley & Aldrich considered remedial options and alternatives to
address soil and groundwater contamination at the subject site. Properties subject to a Consent Order,
such as the subject site, are subject to the CTDEEP RSRs. Several RSR criteria are applicable to the
site due to the presence of both GAA and GB groundwater resources. CTDEEP criteria applicable to
the site soil includes; RSR RDEC, GAPMC, and GBPMC. CTDEEP RSR GWPC, SWPC, and
Residential Volatilization Criteria (RVC) are also applicable to the site groundwater. During the Phase
III and Supplemental Phase III investigations, Haley & Aldrich compared site soil and groundwater
quality to applicable RSR criteria. Results of the site characterization detected soil containing SVOCs,
ETPH and/or metals in excess of RDEC at depths ranging from less than 2 ft. to below the water table.
Soils above the water table also exceeded applicable PMC at widespread locations. Groundwater
beneath Rochford Field contained SVOCs, ETPH, nickel, and zinc at concentrations above RSR
GWPC.
Given the widespread nature and extent of impacts that exceed RSR criteria encountered on the site,
remedial action will be required to achieve RSR compliance at the site. The RDEC is applicable to
soils at depths up to 15 ft below grade. The RSRs allow for use of deed restrictions (known as
Environmental Land Use Restrictions, or ELURs) to reduce the potential for future human direct
exposure to environmentally-impacted materials. ELURs not only record the location of
environmentally impacted materials exceeding RSR criteria, but also require placement of 2 to 4 ft of
clean fill material over environmentally-impacted material exceeding RSR Direct Exposure Criteria
(DEC). The CTDEEP requires the ELUR and the clean fill in order to render environmentallyimpacted
materials “inaccessible”.
In addition, environmentally-impacted material located above the water table that exceeds the RSR
PMC has the potential to pollute groundwater at and down-gradient from the site. Environmentallyimpacted
material that exceeds the RSR PMC will either require excavation and off-site disposal, or an
engineered control (i.e., a cap designed in accordance with the RSRs). An engineered control would be
used in order to make the material “environmentally isolated”. The RSRs allow for several other
options to address PMC impacts including a variance due to the presence of “Widespread Polluted Fill”
and determination of alternative PMC. Widespread Polluted Fill is defined in the RSRs as fill that is:
not polluted with volatile organic substances; does not affect the quality of an existing or potential
public or private water supply; additionally, the placement of the fill was not prohibited by law at the
time of placement and the fill was not placed by the party requesting the variance. The evaluation of
remedial options included the consideration of variances and ELURs as allowed for by the RSRs.
3.2 Initial Screening and Remedial Feasibity Assessment
As part of the Preliminary Remedial Action Plan, Haley & Aldrich considered a variety of potential
remedial technologies and strategies, associated costs, and schedule. A number of remedial alternatives
were eliminated during our initial screening due to their expense, ineffectiveness in treating metalimpacted
soils, potential for direct exposure to neighborhood residents, or limitations due to the volume
and nature of fill at the site. Potential alternatives eliminated during initial screening included:
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