On March 11, 2010, the Massachusetts Department of Environmental Protection (Mass DEP) requested assistance from the EPA Region 1 Removal Program with the Capen Street Site In Milton, MA . An investigation conducted by the Mass DEP and their state contractor, MACTEC Engineering and Consulting, in November 2009, documented elevated levels of arsenic (As) and lead (Pb) in surface soils on property owned by the Massachusetts Department of Conservation and Recreation (MA DCR) on land close to the Neponset River in Milton, MA. This property was immediately adjacent to the site where spoils from the Neponset River were placed during a dredging operation in the 1960’s. As there is a residential neighborhood adjacent to this DCR property (centered around Capen Street), the Mass DEP utilized MACTEC to collect soil samples on private properties (¼ - ½ acre in size ) throughout the neighborhood during the summer of 2010 to determine if arsenic and lead were present in surface soils at concentrations of concern. The Mass DEP investigation consisted of samples collected at the center points of 20’ x 20’ grids throughout the neighborhood and they have stated that the lead and arsenic concentrations of concern appear to be limited to surface soil. Lead and/or Arsenic were detected in surface soils on ten properties above potential imminent hazard levels (As: 40mg/kg, Pb: 1000 mg/kg established by the Massachusetts Contingency Plan (MCP)).
Although it is documented that river dredge spoils were placed on the DCR property adjacent to the river sometime in the 1960’s, it is unclear if that is the source of the contamination. Polychlorinated Biphenyls (PCBs) along with lead and arsenic were detected in the river sediment, but PCBs have not been detected on the residential properties. There is evidence that in the early 1900’s, a sand and gravel borrow pit on what is now the DCR land between the dredge spoils area and the residential neighborhood was filled from an unknown source. It is also believed that lead arsenate, a widely used insecticide from the late 1800’s until the 1960’s, may have been sprayed at some point along railroad tracks that bisect Capen Street.
An EPA-lead time critical removal action is scheduled to begin during the Spring, 2011. The action will commence after the MA DCR completes the cleanup of contaminated surface soil from their property.
