Oct. 27, 2006
Secretary Robert Golledge
EOEA, Attn: MEPA Office
William Gage, EOEA No. 6826/11707
100 Cambridge Street, Suite 900
Boston, MA 02114
Subject: MBTA Silver Line Phase III
Dear Secretary Golledge:
Thank you for the opportunity to comment on the Notice for Project Change filed by the MBTA on October 2, 2006, concerning an additional portal alignment as well as potential Boylston Street Station changes to the proposals studied by the MBTA for the Silver Line in the May 2005 Supplemental Draft Environmental Impact Report.
The Boston Groundwater Trust was established by the Boston City Council to monitor groundwater levels in areas of the City where building foundations are threatened by low groundwater levels and to recommend solutions to the problem. As such, my comments are restricted to groundwater related issues.
The proposed route of the Core Tunnel and the various portal alternatives passes either through or very close to the Leather District, Chinatown, Bay Village, the South End, and the Back Bay. Because all of these neighborhoods are substantially built on made land and many of the older structures in them are supported on wood pilings, all of them are included in the Groundwater Conservation Overlay District. This new zoning, adopted in February 2006, requires careful study of new building proposals to assure that they cannot cause reductions in groundwater levels. As Secretary Pritchard noted in his Supplemental EIR certificate of August 15, 2005, "The maintenance of groundwater levels is particularly important because of the number of buildings constructed on untreated wood piles that were designed to be continuously submerged in groundwater". Many of the commenters at the public hearing held on October 19 raised similar concerns. Avoiding groundwater reductions both during construction and over the lifetime of this tunnel is critical to the long term survival of the buildings in these historic neighborhoods.
I am pleased that the MBTA has recognized the importance of this issue. I have met with the MBTA’s geotechnical consultant to define locations for additional groundwater observation wells that will help to better define existing groundwater conditions in the area of the proposed additional potential alignment. Of equal importance is the Secretary’s requirement, again in the Supplemental EIR Certificate, that "The SFEIR should include a census/survey of existing building foundations to determine which are supported on wooden pilings and where those pilings are cut off. This census should be performed within a two block radius of the core tunnel and the Preferred Alternative’s tunnel and portal areas". It is critical that we have this information in order to make sure that levels are maintained at a high enough level to preserve these foundations. If the MBTA is not yet ready to select a preferred alternative, it should perform this survey for any of the alternatives that have not yet been eliminated from consideration.
Designing and constructing Silver Line Phase III so that it cannot cause reductions in nearby groundwater levels will be critical to the ability of potentially affected neighborhoods to thrive and, therefore, to whether the line can be considered a success. I believe that the MBTA recognizes the importance of the issue, and that they are committed to a solution. However, it is necessary that we take all of the steps that will assure a long term positive impact. Once built, a tunnel will likely be in place for centuries. If not designed, built, and maintained properly, it will present a continuous threat of leakage and lowering of groundwater levels. I look forward to working with the T to help assure that all of the necessary steps are taken.
Very truly yours,
Elliott Laffer
Executive Director
