Many environmental activities have been conducted at the Grasse River, including investigations, modeling efforts, pilot studies, and remedial actions, to address PCB levels in the river for the long-term protection of human health and the environment. Activities have included the following efforts:

For a summary of historical milestones, visit the Project Timeline.

Historical Overview

In the process of evaluating remedial options for the Grasse River, a number of site-specific studies have been conducted by the company. These studies included a dredging removal action, a pilot-scale capping study, a pilot study to investigate various remedial options (including dredging and capping), a pilot study to assess an innovative technology involving the addition of activated carbon to the river sediments, and extensive long-term monitoring of PCB levels in the river′s water, sediment and fish.

Conducted in 1995, the dredging removal action (Non-Time-Critical Removal Action) addressed PCB-containing sediments in a 1-acre area located directly off-shore from the plant′s main wastewater discharge (Outfall 001). The scope and results of this work were summarized in a report entitled Non-Time Critical Removal Action Documentation Report. A complete copy of this document can be found at the Massena Public Library.

The Capping Pilot Study, conducted in 2001, evaluated different cap material types and placement techniques in a 7-acre area of the river. The results of this study are summarized in a report entitled Documentation Report — Grasse River Capping Pilot Study, April 2002. A complete copy of this document is available in the Massena Public Library.

Following completion of the Capping Pilot Study, monitoring conducted through fall 2002 indicated that the cap had remained in place. As part of the routine monitoring work conducted in spring 2003, a loss of cap material and in some cases underlying native sediments was observed. As a result of these observations, extensive field studies were performed in 2003, which determined that an ice jam. occurred in March 2003 and was the cause of the disturbance to the cap and underlying sediments. Alcoa worked with EPA to develop a follow-up investigation plan to support an understanding of the impact of the 2003 ice event and the significance of these types of events as they relate to the evaluation of remedial alternatives for the river. Details regarding these studies and their findings are documented in the Addendum to the Comprehensive Characterization of the Lower Grasse River, which is currently under Agency review.

In addition to the post ice scour investigations, the Remedial Options Pilot Study was conducted in 2005 to develop additional information on the potential remediation options being considered for the lower Grasse River. The study components included removing sediment by dredging; covering areas of the river bed by capping; and monitoring conditions in the river before, during, and after the work including longer-term post-construction monitoring in 2006 and 2007. The Remedial Options Pilot Study Documentation Report is currently under review by EPA.

The Activated Carbon Pilot Study was performed in 2006 to evaluate the effectiveness of applying and mixing activated carbon in the lower Grasse River sediments downstream from its Massena West Plant. Activated carbon is widely used in water treatment facilities to remove organic materials from the treated water. Recent research has been conducted to evaluate the use of activated carbon in remediating contaminated sediments; promising results were obtained through laboratory testing work conducted prior to the 2006 field study. The technology utilized during this pilot study consisted of adding activated carbon to the upper layer of the sediments using specially designed equipment, and monitoring over a multi-year period to determine effectiveness. The Activated Carbon Pilot Study Documentation Report is currently under EPA review.

The 2003 ice jam event also initiated an evaluation of potential short term and long term options for controlling ice jams on the lower Grasse River. These efforts included the evaluation of ice breaking as an interim measure, the evaluation of ice control structure options, and implementation of an Ice Breaking Demonstration Project.

Alcoa has also conducted extensive river-wide monitoring of the PCB trends in fish, sediment and water over time. The results of these studies are being used to develop a baseline for river conditions against which future data can be compared. In addition, they provide the information necessary to understand the potential for natural recovery of the river. The results of this monitoring work are summarized in the Comprehensive Characterization of the Lower Grasse River Report and Addendum to the Comprehensive Characterization of the Lower Grasse River (under review). A summary of the long terms trends in fish and water column data can be found in Environmental Monitoring Results.

Information generated from these studies was used in the development and assessment of remedial options for the Grasse River. The information generated was incorporated into a revised Analysis of Alternatives Report, which served as the foundation for the selection of a remedy for the river. The revised Analysis of Alternatives was submitted to EPA in 2012.