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Investigation and Remediation
The Rhode Island Department of Environmental Management (RIDEM) issued a Letter of Responsibility (LOR) on September 12, 1995, to Blackstone Valley Electric Company (BVEC), a predecessor to The Narragansett Electric Company, for “a Release of Hazardous Substances to the environment as defined in Rules 3.64 and 3.30 of the Regulations.” The LOR alleged that soil sampling had revealed elevated levels of cyanides and polynuclear aromatic compounds at the site. It asserted that BVEC was a Responsible Party for the alleged releases, and it required that BVEC undertake a remedial investigation.
The site was listed as State Site #95-022. The primary investigation work was performed in four phases, conducted in 1996, 2006 and between 2008 and 2010, while certain limited investigation and remediation activities were performed at the site as early as 1986. The Narragansett Electric Company documented the results of this phased investigation program in a Site Investigation Data Report to RIDEM in January 2011. This report can be found in the Documents tab of this website.
The results of these investigations indicated the presence of certain MGP and power plant residuals in the site’s soil and groundwater. Typical of former MGP and power plant facilities, constituents detected included volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). The most prevalent VOCs included benzene and other aromatics, and the primary SVOCs detected were polycyclic aromatic hydrocarbons (PAHs), including naphthalene. In general, the most significant impacts were detected in subsurface soils located at/or below the water table with lesser impacts in the near surface soils. In terms of groundwater quality, typical of former MGP and power plant sites, the most prevalent compounds detected in groundwater were benzene and naphthalene. In addition, the presence of both light and dense non-aqueous phase liquid (NAPL) have been observed in certain groundwater monitoring wells on the site.
In July 2011, The Narragansett Electric Company submitted a Remedial Alternative Evaluation (RAE) Report to RIDEM which completed the Site Investigation Report (SIR) for this site. The RAE recommended a remediation plan for this site. The recommended remedial alternative involves removal and off-site disposal of certain impacted materials, installation of downgradient subsurface containment features, and construction of an engineered surface cap. This plan would also include routine groundwater monitoring and non-aqueous phase liquid (NAPL) gauging/recovery and the recording of an Environmental Land Use Restriction (ELUR). The ELUR would include restrictions on the use of the groundwater at the site, restricted use of the site and guidelines on disturbance and maintenance of the engineered cap. This report can be found under Major Reports in the Documents tab of this website. On April 19, 2018, the Rhode Island Department of Environmental Management (RIDEM) issued a Remedial Decision Letter (RDL) that formally approved the Site Investigation Report (SIR) and the proposed remedial alternative and required submittal of a Remedial Action Work Plan (RAWP), which provides details and a schedule for implementation of the proposed remedy. The RDL can be found under Major Correspondence in the Documents tab of this website.
Between September 21, 2017 and December 28, 2017 a Limited Design Investigation (LDI) program was performed to collect supplemental data to facilitate the design of the Site remedy. The Narragansett Electric Company submitted a RAWP to RIDEM, summarizing the results of the LDI program in June 2018. This report can be found under Major Reports in the Documents tab of this website.
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Keeping the Public Informed
The Public Involvement Plan (PIP) is a document filed by The Narragansett Electric Company with the Rhode Island Department of Environmental Management (RIDEM). It explains how The Narragansett Electric Company will meet its requirements to communicate with the community and receive input from the public as the project moves through its various phases. The PIP is a living document and can be amended to reflect additional issues or challenges that may arise during the site cleanup process. The PIP was prepared consistent with the requirements of Rule 7.07 A, B, C, and D of the Rules and Regulations for the Investigation and Remediation of Hazardous Material Releases (Remediation Regulations). Per Rule 7.07 (Public Involvement), this PIP addresses the following primary elements:
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- Public Notice
- Fact Sheets and Enhanced Communication
- Community Meetings
- Information Repositories
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The Narragansett Electric Company has finalized the Public Involvement Plan (PIP) for the Tidewater site. The complete final PIP was submitted to RIDEM on October 16, 2013. Click here to view the final Public Involvement Plan. [/note]
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Click here to view the color-coded map for the Tidewater project that illustrates areas of the Site where impacts have been identified in groundwater and soils. [/note]
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