RI-RAP presented screening of remedial technologies and evaluations of remedial alternatives for soil and ground water leading to preferred remedial alternatives. The RI/RAP report was conditionally approved by CTDEP on 24 June 2009. Based on analyses of collective Site investigation data, including PDI data, discussed in previous sections, this section presents the final RAP, including recommended remedial approach and proposed actions, permits and approvals required, regulatory required deliverables and a proposed schedule for remedial action implementation.

6.1 Remedial Approach
The proposed remedial approach for the Site includes institutional controls based on a Site-wide ELUR and specific remedial actions to address AOCs discussed in Section 5. Table 22 presents a summary of proposed remedial actions. Further descriptions of the ELUR and proposed remedial actions are presented below.

6.1.1 Environmental Land Use Restriction
As previously proposed in CTDEP conditionally approved RI/RAP, institution of an ELUR will be an integral component of remedial actions for the Site. In general, an ELUR is an easement recorded in municipal land records that can be used instead of, or in conjunction with, other remedial actions to ensure site conditions are protective of human health and the environment. Standard ELUR provisions place restrictions on use of the “subject area” by the property owner or anyone holding interest in the property and grants CTDEP an easement to access the subject area and take necessary remedial actions if necessary.

There are two major categories of ELURs. The first category of ELUR restricts the use and activity of an entire property to industrial/commercial use. This allows remediation to be completed to industrial/commercial criteria. As discussed in previous sections of this report, it is anticipated that an ELUR will be established to restrict the Site use to only industrial/commercial activities, and, thus, the industrial/commercial remediation criteria are applicable at the Site. The second category of ELUR encompasses restrictions that prohibit exposure to or disturbance of inaccessible soil; demolition of buildings which render soil environmentally isolated and prohibit infiltration of water; disturbance of an engineered control or underlying polluted soil; construction of buildings over groundwater that exceeds volatilization criteria for groundwater; and use of groundwater for drinking or other domestic purposes at properties where it is technically impracticable to remediate groundwater. As discussed below, Site-specific ELUR provisions are necessary to facilitate implementation and sustainment of proposed remedial actions for AOCs.

CTDEP Commissioner may grant a release of an ELUR in whole or in part if a landowner wishes to demolish one or more building(s) or take on other activities restricted by an ELUR. Releases from ELURs are routinely approved by CTDEP and have played a successful role in cleanup and redevelopment of impacted properties. The process for obtaining a release is provided in CGS section 22a-133o(d).

All remedial actions described below for individual AOCs include certain ELUR provisions specific to support the proposed actions.

6.1.2 Solid Waste Disposal Areas
6.1.2.1 ROW Disposal Area
Proposed remedial actions for ROW Disposal Area include a combination of excavation, on-site management of soil, off-site disposal and soil capping, as summarized in Table 22. These remedial actions will specifically address AOCs defined by presence of waste materials, soil DEC exceedances and soil metal GB PMC exceedances (Figure 12). As discussed in Section 5.4.5, soil TPH/PAH conditions in ROW Disposal Area apparently have not resulted in exceedances of applicable ground water remediation criteria, and, thus, soil capping is proposed as a more cost-effective and practical remedial approach.

As presented in Figure 12, waste materials that have been observed and anticipated to be present in two separate areas outside the Site property boundary will be removed through excavation. Based on test pit observations, excavation depth will range from less than 2 ft in an area near the wetland boundary to approximately 5 ft near the property boundary. This proposed excavation will be backfilled with clean soil and graded to generally restore original topography. As currently known, an estimated area for excavation is approximately 10,200 SF with an excavated volume of approximately 1,900 CY that will be addressed. A pre-excavation delineation sampling plan will be developed and submitted for CTDEP approval prior to excavation and remedial construction. Execution of that plan will allow definition of final excavation boundaries and depths. Excavated materials will be characterized following a waste characterization plan. Based on waste characteristics, hazardous materials, if any, will be managed through off-site disposal and/or possible recycling at an off-site facility. Non- hazardous materials/soils will be managed either through off-site disposal or through consolidation under the proposed soil cap within ROW Disposal Area. Final quantities for off- site management and on-site consolidation will be determined based on waste characterization results, final plan specifications, and design grade for finished soil cap.

The metal (lead) GB PMC AOC identified within ROW Disposal Area (Figure 12) will be addressed by excavation, to a maximum depth defined by the seasonal-high water table (estimated at 9 ft bgs in this AOC). A sampling plan for pre-excavation delineation will be developed for CTDEP approval. As currently known, an estimated area for excavation is approximately 230 SF with an excavated volume of approximately 80 CY that will be addressed. Excavated material will be characterized for waste characteristics and transported for off-site disposal to an appropriate waste disposal facility and/or possible recycling at an off-site facility. This proposed excavation will be backfilled with clean soil or impacted soil that meets all applicable RSR criteria.

Soil DEC AOCs and a disposal area where waste materials were observed will be addressed through placement of a soil cap as shown on Figure 12. This capped area will be approximately 43,000 SF and have a minimum thickness of four (4) ft within DEC AOCs. Cap construction in this manner will render these soils inaccessible in conjunction with an ELUR. Depending on final grade specification, portions of the soil cap for area beyond DEC AOCs may transition to a two (2) ft thick final cover.

A final capping plan will be designed and submitted to CTDEP prior to remedial construction. It is expected that in general, final grade of the soil cap top will be a minimum of four (4) percent to avoid ponding and reduce infiltration. Side slopes will not exceed a grade of three to one (3- to-1) (horizontal to vertical) to prevent erosion. If necessary, drainage features will be designed for implementation. Based on geotechnical boring data and analyses discussed in Section 5.3, it is currently expected that placement of a 4-ft thick soil layer on top of existing fill areas can be achieved with an adequate factor of engineering safety. During design, final grades and cap thicknesses will be determined in coordination with the City. Upon application of final cover and final grading, surface vegetation will be established. Future cap maintenance may include vector control and vegetative cover maintenance.

Following approval of this RAP, a ground water monitoring plan will be developed and submitted to CTDEP for approval. Further descriptions for ground water monitoring are provided below in Section 6.1.5.

6.1.2.2 Railroad Spur Disposal Area
Proposed remedial actions for Railroad Spur Disposal Area include a combination of excavation and paving, soil capping, and construction of an engineered control, as summarized in Table 22. These remedial actions specifically address AOCs defined with respect to presence of waste materials, soil DEC exceedances, and soil metal GB PMC exceedances (Figure 13). As discussed in Section 5.4.5, TPH/PAH soil conditions within Railroad Spur Disposal Area have not resulted in exceedances of applicable ground water remediation criteria. Therefore, the TPH/PAH GB PMC AOC shown on Figure 11 will not be specifically addressed by proposed remedial actions.

Figure 13 depicts targeted excavations proposed for a portion of the DEC AOC. This remedial action addresses DEC exceedances and facilitates City’s plan to pave this area for vehicle access and/or parking. Final excavation boundaries will be determined in consultation with the City, but remedial action design parameters within the DEC AOC will be finalized by Unisys through pre-excavation delineation sampling. In conjunction with City’s plan to pave this area and implementation of an ELUR, an excavation depth of 2 ft is envisioned to render remaining, deeper soil inaccessible. Preliminary estimated area of excavation is approximately 4,000 SF with an approximate volume of 300 CY. A pre-excavation delineation sampling plan will be developed for CTDEP approval prior to excavation and remedial construction. As appropriate, excavated materials will be characterized for off-site disposal and/or possible recycling. Unisys expects City’s paving plan and design will be approved by CTDEP and incorporated into remedial action implementation.

Two AOCs with metal PMC exceedances will be addressed through an engineered control constructed to prohibit infiltration of precipitation. This engineered control is anticipated to cover an area extending from the edge of paved area to approximately the eastern extent of fill area. This includes a portion of the DEC AOC (Figure 13). This engineered control has an area of approximately 10,000 SF and will be designed to achieve a permeability of less than 10-6 centimeters per second (cm/s). Construction may include a liner overlain by geotextile for structural integrity and a drainage grid. In addition to a liner, this engineered control will also include up to two (2) ft of clean fill material above the liner. An ELUR restricting activities that could affect integrity of this engineered control will be established. In combination, this proposed engineered control and ELUR will environmentally isolate materials underneath the cover and achieve the intended remediation objective.

One remaining disposal area north of the aforementioned engineered control will be addressed through a soil cap with a minimum thickness of four (4) ft. This proposed soil cover, in conjunction with an ELUR, will render soils underneath the cap inaccessible. Estimated cover area for this soil cap is approximately 1,500 SF.

A final capping plan, excavation plan and engineered control design will be developed during remedial design while coordinated with the City. These plans and designs, including City’s paving plan and design, will be submitted to CTDEP prior to remedial action implementation. Following approval of this RAP, a ground water monitoring plan will be developed and submitted to CTDEP for approval. Further descriptions for ground water monitoring are provided below in Section 6.1.5.

6.1.3 Soil AOCs in TCE and Petroleum Areas
Proposed soil remedial actions for soil AOCs in TCE and Petroleum Areas are shown on Figure 14 and summarized in Table 22. Selective excavation will address I/C DEC AOC and GB PMC AOCs for cVOCs, PAHs and TPH. A pre-excavation delineation sampling plan will be developed and submitted for CTDEP approval prior to excavation and remedial construction. Final excavation boundary and depth will be determined based on pre-excavation delineation results.

Exceedances associated with Building No. 1A cVOC GB PMC AOC, south of Building No. 1A, will be addressed by excavation to a depth approximate with seasonal high ground water, approximately 3 to 4 ft bgs in this area. Area estimated for excavation is approximately 1,100 SF with an approximate volume of 130 CY. Final excavation boundary and depth will be determined based on pre-excavation delineation results. Excavated soil is expected to be managed through off-site disposal. After backfilling with clean soil, the area will be graded to pre-construction topography and vegetative cover will be planted.

Building No. 2 DEC AOC and Suspect UST-5 GB PMC AOC will be addressed by excavation to a depth approximate with seasonal-high ground water, approximately at 3 to 4 ft bgs in these areas. Area estimated for excavation is approximately 5,500 SF with an approximate volume of 820 CY. Final excavation boundary and depth will be determined based on pre-excavation delineation results. Excavated soil is expected to be managed through off-site disposal. After backfilling with clean soil, the area will be graded to its pre-construction topography and paved. Exceedances associated with soil GB PMC AOC are identified in Building No. 5 Area (Figure 11), as discussed in Section 5.4.5. Soil with GB PMC exceedances exist beneath existing Building No. 5, which prevents infiltration. Ground water cVOC concentrations in this area are below I/C GWVC and considered stable as discussed in Section 5.5.1 (Table 20-B). Based on these considerations and with an ELUR to restrict building removal, soil remedial action is not recommended for this AOC.

6.1.4 MNA for Ground Water AOCs
As summarized in Table 22, ground water AOCs will be addressed by MNA in conjunction with ELUR implementation. Ground water remediation through MNA will address ground water AOCs in the vicinity of Building Nos. 1A/1B/2, Building No. 5, Building No. 8, and Suspect UST-5 Area. As discussed in Section 5.5, current ground water data provide converging lines of evidence, including plume stability, that support a natural attenuation approach. As discussed in Section 5.5 and shown in Tables 20A-C, this remedial action approach requires collection of additional data to determine temporal trends for certain locations. Such a ground water monitoring program will also provide temporal and spatial data to better establish trends and plume stability for ground water AOC in Suspect UST-5 Area, with respect to PAHs.

A ground water monitoring program to support ground water remedial action will be developed following CTDEP approval of this final RAP. Preliminary evaluations of monitoring program requirements are presented in Figure 15, which presents a proposed monitoring well network, and Table 14 presenting a proposed MNA monitoring program. For cVOC ground water AOC, analytical parameters would include cVOCs, DHG (ethene, ethane and methane), and geochemical field parameters (e.g., pH, DO, ORP). For PAH ground water AOC, analytical parameters would include PAHs, VOCs, and geochemical field parameters. Additional biogeochemical parameters [e.g., total organic carbon [TOC], alkalinity and dissolved ions (sulfate, iron, and nitrate)] may be collected on an as needed basis and in accordance with approved ground water monitoring plan.

Procedures and schedule for performance monitoring will be presented in a ground water monitoring plan to be submitted to CTDEP following approval of this final RAP. MNA monitoring would be conducted at a semi-annual frequency for a period of four (4) years. Monitoring data collected through this program will be used by Unisys to evaluate MNA effectiveness and make recommendations for future monitoring. This may include adjustment of sampling frequency and elimination of redundancy within the monitoring network and analytical program.

6.1.5 Site Ground Water Monitoring
Consistent with requirements of RCSA Section 22a-133k-2(f)(2)(B)(ii) for engineered controls and Section 22a-133k-3(g)(2)(A) for ground water monitoring in GB areas following soil remediation, a ground water monitoring plan will be developed to address groundwater downgradient of the ROW Disposal Area and Railroad Spur Disposal Area. This ground water monitoring program will document performance of remedial actions described for these areas (Section 6.1.2). Proposed monitoring locations (Figure 15) and analytical parameters are summarized in Table 23. Temporary wells installed at the toe of the fill areas during PDI will be abandoned, and permanent monitoring wells will be installed in areas shown in Figure 15. The revised ground water monitoring network will include wells located upgradient and within disposal areas.

Procedures and schedule for performance monitoring will be presented in a ground water monitoring plan to be submitted to CTDEP following approval of this final RAP. Monitoring will begin at semi-annual frequency to capture potential seasonal variations. Monitoring data collected through this program will be used by Unisys to assess effectiveness of implemented remedial actions and make recommendations for future monitoring, which may include adjustment of sampling frequency and elimination of redundancy within the monitoring network and analytical program. Ground water monitoring will include gauging water levels. Analytical parameters will include COPCs and geochemical field parameters (e.g., pH, DO, ORP) at select wells in accordance with the approved ground water monitoring plan.

6.2 Permits and Approvals
Paragraph B.2.f of the Order requires that all permits and requests necessary to carry out remedial actions approved by CTDEP be applied for on or before thirty (30) days after the Commissioner has approved a RAP. Table 24 lists permits and approvals currently considered necessary to implement the remedial actions described in Section 6.1. Subsequent to receipt of RAP approval, Unisys will proceed to developing engineering plans that are necessary to accompany and in support of permit applications. Unisys proposes to submit permit applications, as identified in Table 24, within ninety (90) days following approval of this final RAP. Unisys also anticipates that the City will complete the process of establishing a Site-wide ELUR with provisions necessary for supporting the remedial approach described in Section 6.1. Unisys can provide design information, as appropriate, to support City’s efforts of establishing the ELUR. Per Paragraph B.2.h of the Order, Unisys will submit to CTDEP notice of receiving any required permit or approval on or before ten (10) days of receipt of required permit or approval.

6.3 Schedule and Deliverables
A schedule for implementing this final RAP is presented in Table 25. Within sixty (60) days following CTDEP approval of this final RAP, Unisys will submit a ground water monitoring plan presenting the plan and schedule for sampling and analysis of Site ground water. It is anticipated that semi-annual ground water monitoring capturing seasonal-high and seasonal-low water table conditions will continue for four (4) years, during which annual monitoring reports will be prepared and submitted. Unisys anticipates making recommendations for subsequent monitoring and reporting frequencies based on monitoring results from this initial period. Following CTDEP approval of this final RAP, Unisys will develop engineering design plans and specifications, as well as prepare permit applications as identified in Table 24. Unisys proposes to submit permit applications within ninety (90) days following receipt of RAP approval. Unisys currently anticipates needing approximately five (5) months from RAP approval to complete remedial design and specifications with sufficient details to solicit contractor bids for remedial construction. Upon completion of a Remedial Design and receipt of written confirmation from the City of Middletown that it will file for an ELUR consistent with that Remedial Design, Unisys will proceed to the bidding and contracting process.

Prior to excavation and remedial construction, a sampling plan for pre-excavation delineation sampling will be submitted to CTDEP. Following CTDEP approval of this pre-excavation delineation sampling plan, Unisys will complete pre-excavation delineation sampling and, based on the results, finalize the excavation plan for remedial construction contractors. Selected remediation contractors will implement remedial actions in accordance with engineering plans and specifications. Within fifteen (15) days of completion of the approved remedial action construction, Unisys will submit a written certification to CTDEP.