Photo Credit: Somerville Patch
A distinctive sheen on the saltwater section of the Mystic River in early April led to the discovery of an underground oil leak. The dielectric oil was coming from an Eversource Energy cable encased in a metal pipeline that runs near the Alford Street Bridge at Mystic Avenue in Somerville. The oil was leaking into a stormwater system and being discharged at a Massachusetts Water Resource Authority outfall. The sheen was spotted throughout the Lower Mystic extending from the Amelia Earhart Dam, to the Encore Resort to areas near the Tobin Bridge.
Since the leak was discovered, the US Coast Guard, Department of Environmental Protection (MassDEP), and Eversource have been collaboratively leading the cleanup with GZA as licensed site professional and implementation by Clean Harbors. Already 3,600 gallons of the estimated 6,870 gallons spilled have been recovered. A majority of the recovered oil was pumped out of recovery wells in the cavity below the street where the pipe ruptured.
In the coming weeks, the project team will sample the sediments and along the shoreline to determine if there is residual oil present. Though residual petroleum and sediment from historical spills exist in some locations--it is possible for the team to ‘fingerprint’ the oils and determine if this particular oil is present. If so remediation might include the cleanup through sediment removal.
A coincident die-off of nearly 30,000 menhaden in this area raised concerns about the impact of this local pollution. The conclusion from experts at MassDEP and Fisheries and Wildlife was that the fishkill was a wholly natural event and not related to this pollution event.
The cleanup will continue to be managed by the Coast Guard convened incident command until no sheens are found on the water for multiple weeks. At that point, the MassDEP will take over management of the incident.
Though a spill is never good news for a river--as it can have lasting and negative impacts--MyRWA has been encouraged by the intensity of the cleanup efforts to date. We will continue to monitor progress and share news.