http://www.epa.gov/regionl/ge/thesite/landhalfmile.html Lastjjpdated on Monday, September 15th, 2008. Last update GE/Housatonic River Site in New England You are here: EPA Home EPA New England Cleanup Find NE Sites Housatonic River IV2 Mile Housatonic River IV2 Mile The IV2 Mile Reach represents a section of the East Branch of the Housatonic River between Lyman Street Bridge and the confluence of the East and West Branches of the Housatonic River. The l1/2 Mile Reach is located within residential, commercial, industrial and undeveloped/recreational properties. There are approximately 40 residential properties located adjacent to the Housatonic River or within the floodplain. In the 1940s, approximately 1,500 feet of this reach was re-channelized by the City of Pittsfield and the United States Army Corps of Engineers. During the re-channelization efforts, three oxbows located within the firstl,500- foot stretch of the 1.5 Mile Reach were filled in. In the first mile of the 1.5 mile reach, the riverbanks are generally steep and the floodplain is narrow. In the last half mile, the riverbanks are relatively low, resulting in a broad floodplain. Figure 1 shows the V/2 Mile Reach and its proximity to the GE facility. Jump to Report Index Allendale School Floodplain Properties Former Filled Oxbows GE Plant Area General Groundwater Housatonic River IV2 Mile Housatonic River V2 Mile Removal On-Plant Consolidation Areas Rest of River Silver Lake The average concentration of PCBs in the surficial sediments (0 tol foot depth) was 21 parts per million (ppm) and the average concentration of PCBs in sediments at all depths was 29 ppm. For the riverbanks, the average concentration of PCBs in the top foot was approximately 23 ppm and the average concentration of PCBs in the top three feet was 40 ppm. The Consent Decree required EPA to implement the removal action, with General Electric (GE) reimbursing EPA as part of a cost-sharing arrangement. As an example of how the cost- sharing agreement works, if the selected cleanup alternative costs a total of $85 million, GE will pay about $50 million and EPA will pay about $35 million (see the Consent Decree language under "Cleanup Agreements" for more details). EPA's selected remedy for the V/2 Mile Reach is described in a November 2000 "Action Memorandum" (PDF) (173 pp., 17.22 MB. about PDF). In September 2002, immediately following GE's completion of the Upper V2-Mile Reach remediation, EPA initiated remediation activities in the Vh Mile Reach. EPA completed excavation activities in March of 2006. Restoration activities, including restoration of support areas, were substantially completed by the end of 2006. EPA performed the V/2 Mile removal action using two "dry excavation" techniques. The first technique used was similar to the method employed by GE in the Upper 1/2-Mile Reach. This is the sheetpile coffer dam technique, which consisted of using sheetpile to construct individual sheetpile cells along the river. To build a cell, a sheetpile wail was installed along the centerline of the riverbed, followed by an installation of upstream and downstream sheetpile cut-off walls, which branched off the centerline sheetpile wall and extended up the riverbank. The river flow is thus diverted around the sheetpile cell, the cell is then dewatered, and the sediment and riverbank soil is removed. The cell is then backfilled with clean fiil and riprap to the design grade. Next, the two cut-off walls were removed and re-installed on the opposite side of the river, thus creating the next cell to be remediated and restored. Remediation activities then proceeded downstream, with the activities alternating from one side of the river to the other. Standard excavating equipment was used to complete the sediment and soil removal and backfilling. A typical sheetpile cell was approximately 300 feet long and approximately 30 feet wide. ------- |