Danehy Park, located in North Cambridge, is a sprawling, 50-acre park that offers recreational opportunities to Cambridge residents and community members of all ages and abilities. The park’s amenities include 2 soccer fields, 3 softball fields, a rubberized track, 2 picnic areas, a dog park, a tot lot, and the Louis A. DePasquale Universal Design playground, all connected by walking paths. Danehy Park also hosts a variety of City and community events.
Fall - Winter 2023
City staff meet regularly with MassDEP staff and CDM Smith to review the monitoring, and coordinate on projects such as improvements to the Louis A. DePasquale Universal Playground at Danehy Park, short-term improvements to the softball field, the Danehy Park Sports Pavilion (currently in design), and a new public toilet (also currently in design). All projects and improvements in and around Danehy Park are closely reviewed and monitored to ensure that they are implemented in a way that is consistent with MassDEP regulations and continue to properly manage the landfill gases.
The City continues to work with MassDEP to close out the immediate response and develop an enhanced monitoring program, which will include a site-wide assessment that will continue into 2024.
The planned investigation seeks to further delineate the presence of landfill gas at Danehy Park as well as characterize the nature and extent of landfill-derived, leachate-impacted groundwater. The investigation will consider site conditions such as the extent of landfilled wastes, limit of landfill cap, depth of fill materials, proximity to the landfill gas vent trench, former clay pit excavations, and areas of potential offsite landfill gas and groundwater migration. The landfill gas assessment will involve a site-wide subsurface utility investigation to expand upon the locations screened in the current Environmental Monitoring Plan.
Spring - Summer 2023
On March 21, 2023, a contractor working for the City and performing soil borings identified a methane pocket beneath the clay cap in Danehy Park. Methane is a natural by-product of the biological degradation of organic waste deposited over several decades.
The design of the park, with perimeter venting, was intended to allow methane to naturally vent and limit the extent of methane migration beyond the boundaries of the park. Methane itself does not pose a significant health risk to people in an open and well-ventilated area.
Like other gases that are not acutely toxic (e.g. CO2) the primary health risk comes from displacement of oxygen in an enclosed space. Methane can be explosive at certain concentration levels (between the Lower Explosive Limit or LEL (5%) and Upper Explosive Limit or UEL(15%) ) if allowed to accumulate in an enclosed space.
Out of an abundance of caution, the City began limiting construction activities in the park and temporarily removed the charcoal grills for the BBQ / Picnic Areas.
Since the methane pocket beneath the clay cap in Danehy Park was discovered in March, the City worked closely with MassDEP to install additional venting structures to allow the landfill gases to safely vent. The City has also increased monitoring in the park to ensure the effectiveness of the venting modifications. This increased ventilation has been effective at decreasing the methane levels in the samples.
Prior to its use as a City park, the area was predominately clay, and between 1847-1952, the clay was extracted to manufacture bricks by the New England Brick Company. The City of Cambridge purchased the site from the New England Brick Company in 1946 and used the site, then known as the “New Street Landfill,” between 1952 and 1971. The landfill was closed to large-scale dumping in March 1971, but was used for a brief period during the early 1970s for disposal of leaves, trees, and similar items; for dumping of miscellaneous materials from excavations; and for transfer of collected garbage to offsite locations. From 1976 to 1982, the site was also used for the placement of excavated material generated from Massachusetts Bay Transportation Authority (MBTA) construction projects. In February 1990, the City received a final closure permit from MassDEP.
Methane is a natural by-product of the biological degradation of organic waste deposited over several decades. The design of Danehy Park allows methane to naturally vent through the perimeter vent trench. Proper ventilation is key to managing methane. Methane itself does not pose a health risk to people in an open and well-ventilated area. The primary health risk comes from displacement of oxygen in an enclosed space.
The Department of Human Service Programs’ Recreation Division manages the park’s programming and day-to-day operations. The Department of Public Works oversees site monitoring responsibilities. jwilcox@cambridgema.gov , 617-349-6426 acorbeil@cambridgema.gov 617-349-6229