Last Thursday the Boston Planning and Development Agency (BPDA) board voted to expand the Groundwater Conservation Overlay District (GCOD) zoning Article 32 to East Boston, as well as Lower Roxbury, Audubon Circle and the Central Waterfront area.
According to the BPDA the GCOD ensures stable groundwater levels where buildings stand on filled land and utilize wooden pilings to support their foundations.
Depleted groundwater exposes the tops of those pilings to oxygen and promotes decay, causing structural damage and potential collapse of the buildings they support. The GCOD helps ensure stable groundwater levels by requiring projects that meet certain thresholds to release rainwater into the ground, rather than discharging it into the stormwater sewer system.
A decade ago several buildings on Chelsea Street, just before Maverick Square, collapsed and displaced dozens of residents.
Numerous structural engineers blamed displaced groundwater as a contributing factor to destabilizing these structures and the entire block. Displaced groundwater, the MBTA tunnel running under the street and pervasive truck traffic rumbling on Chelsea Street all hours of the day and night exacerbated the situation. In addition, cracked foundations and displaced groundwater were found in some of the structures that collapsed as far back as 1978.
Eastie was originally several smaller harbor islands that were filled in and connected to form the neighborhood. Much of what the neighborhood is built on is former marsh land and tidal basins.
The BPDA said the expansion is based on several years of data collected by the Boston Groundwater Trust (BGWT) from over 800 monitoring wells, and research of the foundation types and soil conditions of Boston’s neighborhoods where masonry buildings on wooden pilings may exist.
“The expansion of the GCOD area will ensure the structural safety of Boston’s older buildings that exist on filled areas of the City,” said the BPDA in a statement. “The proposed amendment will harmonize GCOD requirements with those of the Boston Water and Sewer Commission, provide for earlier notification to abutters of proposed projects, and standardize recharge requirements across the area of the GCOD.”
Both items also require approval by the Boston Zoning Commission.