On Friday, June 24, 2005, at approximately 6:00pm, OSC Wainberg was dispatched to the Boott Hydropower Facility (owned and operated by Enel Corporation), located at 145 Pawtucket Street along the Merrimack River. Earlier in the day, at approximately 4:30pm, the Lowell Fire Department responded to a report of a visible sheen on the Merrimack River and determined that the Boott facility was the source of a hydraulic oil release. Subsequent to this determination the fire department notified the National Response Center and Massachusetts Department of Environmental Protection (MA DEP).
On the morning of June 24th, facility personnel had shut down the power generation system when increased vibrations were observed. At approximately 12:30pm, a low oil level alarm sounded indicating a drop in the oil level in the 400 gallon hydraulic oil head tank that gravity feeds lubricating oil to hydropower components. At approximately 1:30pm, facility personnel observed a sheen in the tailrace and at approximately 2:30pm the head and tailgates of the facility were closed. The tailgate was unable to close completely due to debris lodged in the gate area and a diver was scheduled for Saturday morning to remove debris from the area and assist with seating the gate properly. Facility personnel observed that the 400 gallon tank was empty and it was estimated that a majority of the product was trapped within the draft tube (the portion of the facility between the head and tailgates through which water moves and impels the turbines). By early Friday evening there was no visible sheen in the tailrace.
By 7:00pm, when OSC Wainberg had arrived on-scene, the Lowell Fire Department had deployed curtain and sausage boom in the tailrace to contain any further release of hydraulic oil. In addition, the Fire Department, via Lowell Regional Wastewater, had notified downstream water suppliers in the communities of Tewksbury, Methuen, Lawrence, and Andover. Duty Officer Lipson accessed the US Coast Guard Oil Spill Liability Trust Fund (OSLTF) for $10,000 in case federal resources were required.
Tewksbury Water Supply requested contingency provisions to protect their water intake until the situation was fully stabilized. Facility represenstatives agreed to stage personnel and containment boom adjacent to the Tewksbury water intake until the situation stabilized.
At approximately 11:30pm representatives from MADEP, EPA, and Boott Hydropower met Tewksbury Water Utility personnel on-site and determined an appropriate location to stage boom and personnel overnight.
At approximately 9:00am on Saturday morning, OSC Wainberg returned to the Site to observe diver operations and the complete closure of the tailgate. During debris removal (approximately 1.5 hours) a sheen was observed coming from the gate area. The sheen appeared to terminate at the containment boom as no visible sheen was observed beyond the boom.
After the tailgate was secured, water in the draft tube was pumped into the tailrace until the level inside was below the man-way allowing personnel to access the area and assess the conditions. Upon entry into the draft tube, a large quantity of free product was observed on the surface of the trapped water and the hydraulic line appeared to be leaking slowly. It was decided that the draft tube would be pumped on Monday morning to allow the product to leak out of the system and be recovered with the rest of the free product.
At 1:00pm, after the gate was secured and no sheening observed during pumping activities, OSC Wainberg demobilized from the Site and continued to coordinate with MA DEP and facility personnel via telephone.
On Monday, June 27, oil remediation crews pumped out the draft tube and continued to investigate and remediate free product within the draft tube.
With the facililty operator assuming responsibility for the cleanup, additional federal resources were not required and the request for OSLTF money was cancelled on June 28, 2005.
Summary of Oil Disposition:
Initially, the facility operator indicated that a maximum of 400 gal. (based on the volume of the empty head tank) could have been released to the Merrimack River. The final estimate of oil actually released to the river was to be made after the draft tube had been cleaned and the volume of recovered oil calculated. However, between Monday and Wednesday, the facility operator refined their calculations, which are reflected below:
Total capacity of the system for one turbine unit (facility has two turbine units): 2997 gal.
Volume remaining within the system: 1577 gal.
Volume released into the draft tube: 1420 gal.
Volume recovered into the vaccuum truck: 1403 gal.
Volume released into the river: 17 gal.
The Responsible Party will continue to remediate any residual oil left in the tube and repair the system under the direction of a Licensed Site Professional with oversight from MA DEP.
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