January 27, 2006
Ms. Heather Campisano, Senior Project Manager
Boston Redevelopment Authority
One City Hall Square
Boston, MA 02201-1007
Subject: 346-354 Congress Street
Dear Ms. Campisano:
Thank you for the opportunity to comment on the Project Notification Form for 346-354 Congress Street. The Boston Groundwater Trust was established by the Boston City Council to monitor groundwater levels in sections of the City where building foundations are threatened by lowered groundwater levels and to make recommendations for solving the problem. As such, my comments are restricted to groundwater issues.
This project consists of two rehabilitated buildings and one new building to be constructed on filled land in the Fort Point Channel section of South Boston. As stated in the PNF, the existing buildings are, and will continue to be, supported on wood pilings. According to the PNF, the pilings appear to be in good condition, based on test pit investigations.
The project plans to prevent lowering of existing groundwater levels by using a fully waterproofed structurally supported slab with no subsurface drainage or long term pumping. We commend the proponent for incorporating this foundation design which has proven successful at preventing groundwater drawdowns at other locations in Boston.
At the scoping session, I raised questions concerning the cutoff height of the existing pilings and groundwater levels found at the observation wells that the proponent has installed in the area of the project. I want to thank the proponent for promptly and completely providing the information that I requested. When we discussed the fact that the Fire Museum appeared to have a new source of groundwater coming into their basement, the proponent mentioned that, surprisingly, the test pit closest to the museum was the only one in which pile tops appeared to be above the groundwater level. In studying the data from their test pits, this appears to be not because groundwater levels are lowest at that point, but because the piles were cut off at a higher elevation. Covering those piles requires maintaining groundwater levels at an elevation of nearly 8 feet BCB. Because the piles are in good condition, this level has probably been maintained in the past.
In order to continue to understand groundwater conditions in the area, it will be helpful to receive the readings from the proponent’s groundwater observation wells, as promised in Section 2.2.8.4. I believe that we should receive the information at least monthly before and during construction and at least quarterly, rather than annually, thereafter. If access on a satisfactory can be arranged, the Trust would appreciate the opportunity to monitor the proponent’s wells located along private streets and to incorporate those wells into our network and post the data on our website.
I also believe that this project may offer an ideal opportunity to incorporate recharge from the roof drains to help to maintain the high groundwater levels necessary to protect the pilings supporting these and neighboring buildings. In Section 2.5.3, the proponent mentions the potential construction of a stormwater retention structure to recharge a portion of the stormwater runoff from the building roofs. I look forward to the incorporation of such a structure in the project design.
Again, I appreciate the cooperation of the proponent in providing the information that I requested at the scoping session and their interest and concern for the groundwater situation. Maintaining sufficient groundwater levels in the area is crucial to the viability of the buildings to be rehabilitated for this project and for the many other historic buildings in the Fort Point Channel area. I look forward to working with the proponent and the Authority in our efforts to maintain these levels.
Very truly yours,
Elliott Laffer
Executive Director
Cc: John Walser, BRA
Maura Zlody, BED
