June 7, 2006
Secretary Stephen Pritchard
Executive Office of Environmental Affairs
Attn: MEPA Unit
EOEA Number 13777
100 Cambridge Street, Suite 900
Boston, MA 02114
Subject: Storrow Drive Underpass
Dear Secretary Pritchard:
Thank you for the opportunity to comment on the Environmental Notification Form for the Storrow Drive Underpass project and for your commitment that the project will be required to do a full 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 reduced groundwater levels and to make recommendations for solving the problem. As such, my comments are limited to groundwater related issues.
The area along Back Street in the Back Bay and nearby areas of Beacon Hill have long had among the lowest groundwater levels among all of the sections of the City monitored by the Trust. The large amount of water pumped from the existing Storrow Drive underpass has raised concerns that it might be a contributing factor to these low readings. This concern has been clearly acknowledged by DCR in its public presentations on the project. It is raised, as well, as an important mitigation measure both for the construction period and long term in the ENF.
I am pleased with DCRs recognition of the importance of this critical issue. They are participants in the City-State Groundwater Working Group, and all of their input to that group has been related to the area around the underpass. They have stated repeatedly that their goal is to have a design that cannot contribute to groundwater level reductions in the area near the underpass from what would exist if Storrow Drive were not there.
I was pleased as well to see that the alternatives laid out were all rated for their potential impact on groundwater. According to the ENF, the surface road alignment is the most benign for its potential groundwater impacts. Therefore, I request that at least one surface alignment be studied in detail in the DEIR.
According to the ENF, the reduced potential impact of tunnel alternatives compared to the existing road is primarily accomplished by the installation of a recharge system designed to transfer all of the water drained from the tunnel (both groundwater and rainwater) to the ground on the land side of the old seawall that separates Storrow Drive from Back Street. In addition to the recharge system, the proponent should study how to make any tunnel as watertight as possible, with the goal that there be no pumping of any infiltrated groundwater, with the recharge system serving to get rainwater into the ground. Because this recharge system is critical to improving groundwater levels, I ask that it be studied in substantial detail. Any possible impediments to its successful installation and operation should be identified along with the measures that will be taken to overcome them. Also studied should be whether the recharge system could cause a transfer of groundwater locally, so that levels are reduced in the area away from the recharge chambers because groundwater enters the tunnel drain system and is then recharged at a different location.
Recently, DCR has indicated that the Storrow Drive underpass project may be delayed so that it will not be occurring at the same time as the rebuilding of the Longfellow Bridge. If the project is to be significantly put off, the proponent should be asked to study what interim measures might be put in place that could minimize any current effects that the existing underpass has on what is one of the largest and most persistent areas of low groundwater in the city.
It is critical that we get the treatment of groundwater right when the road is rebuilt. The current design has had the potential to cause negative impacts for over half a century. We should not allow a new design to have the same potential for decades to come. The words of concern and commitment from DCR have been very encouraging. I look forward to this commitment being enforced through the MEPA process, as well as during detailed design and construction.
Very truly yours,
Cc: Rep. Marty Walz
Sen. Dianne Wilkerson