February 7, 2008
Secretary Ian Bowles
Attention: Holly Johnson
EOEEA #14163
Executive Office of Environmental and Energy Affairs
100 Cambridge St, Suite 900
Boston, MA 02114-2524
Subject: Air Rights Parcel 7
Dear Secretary Bowles:
Thank you for the opportunity to comment on the Environmental Notification Form for Turnpike Air Rights Parcel 7. The Boston Groundwater Trust was established by the Boston City Council to monitor groundwater levels in sections of the City where the integrity of building foundations is threatened by low groundwater levels and to make recommendations for solving the problem. As such, my comments are restricted to groundwater related issues.
While this project is not located in Boston’s Groundwater Conservation Overlay District, we have learned in the review process for other nearby projects that there are likely wood piling supported buildings located in close proximity. As the proponent stated during the BRA scoping session, although this is an air rights project, a substantial proportion of the site is actually land based. Of particular concern from a groundwater perspective is the plan for an underground parking garage (five levels in the ENF but presented as more likely three at the scoping session) under Building 1, located near the corner of Beacon and Maitland Streets.
In order to maintain groundwater levels in the area, it is critical that the underground portions of the building be completely waterproofed. I was pleased with the proponent’s commitment at the scoping session that this will be done. Because the construction will, according to the ENF, extend through the relatively impervious organic deposits, it is important to assure that no groundwater from the critical upper aquifer is drained to the area below this layer. Ideally, this will be done by constructing the building without underdrains. Alternatively, there must be no potential path for the upper level groundwater to follow through the organic layer. I appreciate the attention offered by the proponent to this issue at the scoping session and look forward to more details on the solution to this issue in the Draft Environmental Impact Report. If the project is to include underdrains, there should be a detailed engineering analysis to prove that the design is such that they cannot cause a reduction in groundwater levels in the upper aquifer. Since use of the underdrains would be more an issue of the operation than of the construction of the project, any plan to include them should show how the lack of negative impact will be monitored and what will be done if they do cause a reduction in groundwater levels.
I was particularly pleased with the commitment of the proponent, without the requirement of the GCOD, to recharge some of the rainwater that will fall on the impervious surfaces of the development. I look forward to seeing more details of this system in the DEIR as well.
I believe that this project, with the stated intentions of the proponent to resolve the issues raised above, has the opportunity to make a contribution toward solving the groundwater problem in Boston. I look forward to working with the proponent to help make that happen.
Very truly yours,
Elliott Laffer
Executive Director
