The Boston Planning and Development Agency (BPDA) held a public meeting on March 29 to discuss proposed amendments to the zoning code related to the Article 32 Groundwater Conservation Overlay District (GCOD), “and receive comments in order to extend protection to groundwater levels in areas of the city with older buildings on wooden piles built on filled land,” including portions of the South End and Audubon Circle,” according to the BPDA.
Christian Simonelli, Executive Director of the Boston Groundwater Trust, presented some information about the history of the use of wood pilings as foundations for buildings in areas of the city that are on filled land, and then went over the proposed modifications to the zoning code and addressed comments and questions from residents on the webinar.
According to a slide presented, “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 low groundwater levels and to make recommendations for solving the problem.”
Simonelli said that when buildings were constructed on filled land between the mid-1800s to about 1920, “if the building was heavy enough; if it was brick, it’s supported on wood piles. It was the method at the time.” He said that there are usually about 200 piles per building, and for a typical rowhouse, the “piles are submerged below area groundwater levels,” according to a slide. The piles are capped with granite blocks, and water levels are monitored with approximately 800 observation wells that are located across areas of filled land.
Simonelli said that the current groundwater zoning was drafted in 2005, adopted in 2006, and amended in 2007.
“Now is really the time for us to modify the zoning and bring it up to where it should be,” Simonelli said. This will help to both preserve the water table as well as protect the buildings that are built on wooden pilings in the Groundwater Conservation Overlay District, and new areas are also being proposed to protect even more buildings in the city.
He sad that currently, there are four different Article 32 GCOD triggers, including that a new structure or extension of a structure will occupy more than 50 square feet of lot area, if the construction or extension of a structure “involves the excavation below grade to a depth equal to or below seven feet above Boston City Base,” if any structure is to be “substantially” rehabilitated, or paving or surfacing of a lot area, according to a slide presented.
Simonelli then talked about the four proposed changes. The first is to update the one inch capture requirements. He said that currently, there is an assumption that the one inch capture is over the entire area of the lot, and that this should be written into the zoning code.
“As it is written now, the language specifically states a recharge system needs to be designed to capture the area one inch over the area occupied by the building,” Simonelli said. “We want to basically upgrade this language to require a one inch capture be applicable to the area of the entire lot,” as is currently required by the BWSC.
Additionally, he said that the BPDA Smart Utilities policy “has a 1.25 inch requirement for projects at or above 100,000 square feet of floor area, so we think to really maintain consistency with that, that this should be included in the zoning, so the idea here being that the bigger footprint and the bigger area that you have, the more you should be do ing to put water into the ground.”
The second proposed change is to raise the no harm threshold, which is currently Elevation 7, pr “equal to or below seven (7) feet above Boston City Base,” according to the zoning code, to Elevation 8 “based on existing groundwater levels and pile cut off information,” according to a slide presented.
“We want to do this because…we’ve learned so much more really in the 15 years almost that the zoning has been adopted and this change is really, really significant to protect the buildings that have higher pile cutoffs,” Simonelli said.
“When a building is proposed and especially a deep building,” Simonelli said, such as one that has two or three levels of underground parking, it “needs to be designed, engineered, and built to be watertight,” he said. This includes no sump pumps or water drains or anything that will take water away, which will expose adjacent buildings and lower the groundwater table.
Simonelli said that this is indicated in a no-harm letter which is presented to the Zoning Board of Appeal.
He said that since not all buildings were constructed at the same time with the same pile cut off elevations,” and there is variability even within the same block, raising the no harm threshold will ensure the protection of more buildings.
The third proposed change is to update the existing map and coverage areas, as new data on buildings and water elevations in other areas has been collected and needs to be reflected on the map, Simonelli said.
Right now, the map includes both an existing overlay district and a no harm overlay area, but the proposed change would “create a universal overlay area,” according to a slide, and remove the two separate requirements in favor of a project being required to meet both the one inch capture requirement and prove that it will not have a negative impact on the groundwater table, Simonelli said.
The map will now include Audubon Circle, the Central Waterfront, Lower Roxbury, and portions of East Boston.
The final proposed change includes amendments to the standards section, Simonelli said.
“This really is language that’s tailored around the certification and really puts the burden on the applicant to state substance and facts in really how they’re complying with the zoning,” he said, and will require that the one inch capture and no harm requirements “are two separately met requirements.”
Elliott Laffer, the former Executive Director of the Boston Groundwater Trust and the current Chair of the Neighborhood Association of the Back Bay (NABB), said that NABB has “very, very strong support for the changes proposed here.”
He said that they are “all important investments in what’s been a really successful zoning and regulatory effort.” Laffer also said that the “GCOD has led to increases in groundwater levels…” and he’s happy to see that it will be expanded to other areas of the city.
“I think that the increased elevation to eight doesn’t sound like much, but this is a world of inches…” he said, and he believes it will make a difference.
Dolores Boogdanian, president of the Audubon Circle Neighborhood Association, said that she is “very pleased to take part in this discussion,” and said that she supports these proposed changes.
At the beginning of the meeting, City Councilors Kenzie Bok and Ed Flynn, who both have portions of the GCOD in their districts, made remarks.
“I’m excited that part of the proposal here is to sort of include parts of the city that we didn’t originally have canvassed as places where we need groundwater stewardship, like Audubon Circle in my district,” Bok said. “I just want to underscore that our reliance on stable groundwater levels is essential to the preservation of communities and to property throughout the city.”
Flynn said, “We’re so fortunate that the BPDA has a great relationship with the Groundwater Trust on these development proposals and I also have a lot of areas in my district that it impacts, so I’m glad that these provisions are going to be strengthened and to be added to other areas across the city,” adding that “you have my strongest support.”
After the question and comment period, Bryan Glascock of the BPDA said that next steps include a hearing on this matter at the BPDA monthly board meeting on April 15, and if the board “then makes a recommendation to the Zoning commission, the Zoning Commission would hear it on May 12 at 9am,” he said. The full video of this meeting as well as more information can be viewed at bostonplans.org/news-calendar/calendar/2021/03/29/amend-article-32-groundwater-zoning-public-meeting.