June 25, 2008
Ms. Kristin Kara, Senior Project Manager
Boston Redevelopment Authority
One City Hall Square
Boston, MA 02201-1007
Subject: Boston East
Dear Ms. Kara:
Thank you for the opportunity to comment on the Draft Project Impact Report for Boston East. The Boston Groundwater Trust was established by the Boston City Council to monitor groundwater levels in areas of the City where the integrity of building foundations is threatened by low groundwater levels and to make recommendations for solving the problem. Therefore, my comments are limited to groundwater related issues.
The project is not in the Groundwater Conservation Overlay District, but it is near an area with very low groundwater levels and where buildings are supported on wood pilings. I appreciate the proponents response to my comments on the Project Notification Form and his commitment to work with the Trust to identify the best site to install a groundwater observation well to be used as part of the observation well network in East Boston. The well should be installed prior to construction so that a baseline groundwater level can be established and monitored throughout the construction process.
I also appreciate the commitment to all below grade space having waterproofed slab and foundation walls. The proposed underdrain system causes some concern. Project excavation can create a path for groundwater perched above the relatively impervious organic layer to drain to lower elevations where it could be removed by the underdrain system. Backfill should be designed to be impervious to water so that no such path can occur.
Groundwater levels along Decatur Street are much lower than might be expected given how close the street is to the harbor. The DPIR notes that groundwater is flowing to the east or northeast away from the harbor. As noted in my comments on the PNF, there is a well at Central Square and Border Street, only a block or two northeast of the site, that has shown consistently low groundwater levels, often below Elevation 2 Boston City Base. It is important that this project not do anything to create a further lowering of area groundwater levels.
I look forward to working with the proponent to site the observation well and with the proponent and the Authority to assure that the project will not have any adverse effect on area groundwater levels.
Very truly yours,
Cc: Kathleen Pederson, BRA
Maura Zlody, BED