Remedial Action Plan - Rochford Field - Newhall Remediation Project

4. SOIL REMEDY
4.1 Overview
In accordance with Alternative 4 outlined in Section 3, proposed remedial measures to be used at
Rochford Field include construction of an engineered control (EC), placement of an ELUR to restrict
access to soil below the EC, and natural attenuation groundwater monitoring. The following sections
address the remedial strategies will be used to bring Rochford Field into compliance with the RSRs.
An overview of the proposed site design for Rochford Field is shown in Figure 3. The site design
includes baseball and little league fields, landscaped areas and an entrance gate. A detailed profile view
is shown on Figure 4. Plan notes and details are shown on Figure 5.
4.2 Engineered Control Design and Construction
Section 22a-133k-2(f)(2) of the RSRs permits the use of an engineered control (EC) to physically isolate
polluted soil from direct exposure to humans and/or infiltrating storm water from polluted soil to
protect groundwater quality. CTDEEP published a “Guidance Document, Engineered Controls
pursuant to Section 22a-133k-2(f) of the Connecticut Remediation Standard Regulations” dated
February 2009 and revised November 2010. This guidance document describes an engineered Control
as:
A permanent physical structure designed to safely isolate pollutants which would
otherwise not comply with the self-implementing remedial options allowed in sections
22a-133k-1 through -3 of the Remediation Standard Regulations (RSRs). An EC is a
“variance” which requires the Commissioner’s approval. It generally contains
inspection, maintenance and reporting requirements, the recording of an Environmental
Land Use Restriction (ELUR), and the posting of financial assurance to ensure such
measures will be sustained into the future.
In accordance with 22a-133k-2(f)(2)(A)(iv), CTDEEP requires a variance to construct a direct exposure
EC to prevent direct human contact with polluted soil. In the 2007 Remedy Selection Plan, CTDEEP
has requested, and as such, approved construction of an EC at the subject site.
4.2.1 Overview
The EC will be necessary to address RDEC and PMC compliance through the physical isolation
of polluted soil. The EC will include an impermeable membrane and 2 ft of fill material; the
EC design is shown in Figures 4 and 5 and described in the following section. Generally, the
EC will be constructed with a gravel layer (above the impermeable liner) to facilitate drainage,
graded to promotes runoff, resistant to erosion, and designed to account for settlement. The
EC design will be locally modified to include:
Shallow rooted trees with approximately 90 percent of root mass within two feet of the
ground surface and no tap root (see Figures 4, 5 and 6);
Footings for a retaining wall and sidewalk to be constructed along the perimeter of the
site (see Figures 4 and 5).
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