October 17, 2007
Mr. Rodney Sinclair, Project Manager
Boston Redevelopment Authority
One City Hall Square
Boston, MA 02201-1007
Subject: Prudential Center Redevelopment
Dear Mr. Sinclair:
Thank you for the opportunity to comment on the Notice of Project Change/Project Notification Form concerning the addition of the 888 Boylston St and Exeter Avalon buildings to the Prudential Center.
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 lowered groundwater levels and to make recommendations for solving the problem. As such, my comments are limited to groundwater related issues.
As noted in the NPC/PNF, the project is located within the Groundwater Conservation Overlay District. I am pleased to note that the proponent says that it will need to comply with the associated requirements such as infiltration of rainwater. Because of the design and location of the Prudential Center, these will present both challenges and opportunities.
I am pleased that both in the scoping session and in a meeting with the Trust the proponents have made clear their intention to comply with the requirements. Because the Prudential Center is encircled by a sheet pile cutoff wall, groundwater levels within the Center have not been reflected at nearby wells monitored by the Trust. This has been demonstrated during construction of the Mandarin Oriental project, when construction dewatering led to substantial reductions in the levels measured by wells within the Prudential Center but no corresponding reductions were seen in Trust wells located outside the cutoff wall. Therefore, recharge within the boundaries of the Prudential Center is unlikely to offer any benefit to the foundations of nearby wood piling supported buildings.
The proposed Exeter Avalon tower is located near an area across Exeter Street where there are low groundwater levels that could threaten the foundations of several buildings. Therefore, it would be helpful if the required recharge can occur along Exeter, particularly if it can reach past the MBTA Green Line tunnel. Several buildings on the east side of Exeter Street are supported on wood pilings, as is the Lenox Hotel on the west side of the street.
There are even more obstructions that could prevent the installation of a recharge system in Boylston Street in front of the 888 Boylston building. It may make more sense to look at the Prudential Center as a whole, and then install a recharge system of the size required for 888 Boylston on either Belvidere or Dalton Street where there are less obstructions and the potential for the recharge to help raise groundwater levels is higher.
I’m pleased that the proponent has addressed the issue of the potential to affect nearby groundwater levels, as required by GCOD, in its filing. The proponent offers assurance that the goal will be met because of the existing sheet piling wall and because, other than drilled shafts and elevator pits, there will be no construction below the existing garage slab.
I look forward to continuing to work with the proponent to come up with the best solution for the location of the recharge systems. As with all major projects, I’m hopeful that this proposal will be designed and built in such a way that it can only help to raise area groundwater levels.
Very truly yours,
Elliott Laffer
Executive Director
Cc: Kathleen Pederson, BRA
Maura Zlody, BED
