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Swanson Creek Oil Spill

Current Site Information

EPA Region 3 (Mid-Atlantic)

Chalk Point Generating Station
Swanson Creek and the Patuxent River

EPA ID# number

5th Congressional District

Last Update: July 2004
No future updates

Other Names

Pepco Oil Spill

Current Site Status

Pepco completed the final season of cleanup activities at the Swanson Creek Marsh, Patuxent River and its tributaries in 2002. SCAT and Trustee inspections were conducted on the 15 zones not meeting Phase I or Phase II criteria. As a result of these intense inspections and clean-up process over the three year period, all 53 of the zones have passed the Phase I Cleanup Guidelines (free of substantial mobile, liquid or black oil) and 40 of the 53 zones have passed the Phase II Cleanup Guidelines (no rainbow sheen on the sediment, soil or water).

The 13 remaining zones have passed the Phase II Provisional Guidelines. These zones contain environmentally sensitive areas, such as marshes, that present a cleanup challenge and mechanical/manual cleanup techniques may cause further damage to the environmentally sensitive areas. Areas that have received Provisional Approval allow closeout of shoreline areas within zones that do meet the Phase II criteria and a mechanism to place the remaining areas into a long-term monitoring program. The 13 zones that have received Provisional Approval include

Upon completion of the active cleanup operations, a Long Term Monitoring (LTM) Program was established to periodically assess designated areas for the presence of residual oil from the April 2000 oil spill. The LTM Program incorporates the results of the Site Characterization Study, the Biostimulation Program and Shoreline Assessments into an all-inclusive monitoring program. The LTM Program includes the assessment of residual oil in the intertidal and subtidal sediments in the Patuxent River and it tributaries, the assessment of bivalves in Swanson Creek to measure long-term water quality, the assessment of potential long-term toxicological effects of the residual oil and to visually monitor oiled intertidal zones along the Patuxent River and tributaries that have received Provisional Phase II Approval and continue to evaluate these areas against the Phase II criteria.

Pepco conducted its first season of long-term monitoring in August 2003 and included sampling and analysis of marsh cores, marsh surface sediment, bivalve sampling and marsh vegetation. Shoreline inspections included 101 monitoring stations within the 13 zones that have Provisional Approval. Only 6 monitoring stations passed the Phase II Cleanup criteria - none of the 13 zones received final closeout.

Pepco will continue the second season of long-term monitoring in the Summer of 2004. Sampling and analysis of marsh cores, marsh surface sediment, bivalve sampling and marsh vegetation will remain the same. Shoreline inspections will include 95 monitoring stations.

Site Description

The location of the oil spill was in an area of the Swanson Creek Marsh located on property of the Pepco Chalk Point Generating Station in Aquasco, Prince George County, Maryland. Severe weather on April 8, 2000 caused the oil to breach containment and enter the Patuxent River and its tributaries. The spill spread approximately 17 linear miles downstream of the facility and impacted approximately 40 miles of shoreline. The four counties impacted by the oil spill included Calvert, Charles, St. Marys and Prince George counties. The impacted area was divided into 53 operational work zones beginning north of the facility in Lower Marlboro, Maryland and extending down to Solomon’s Island on both the eastern and western sides of the Patuxent River.

Site Responsibility

This site is being addressed by Pepco, under an EPA unilateral order issued under the Oil Pollution Act.

NPL Listing History

This site is not listed on the National Priorities List.

Threats and Contaminants

Fuel Oil #2 and #6 are light brown liquids used as heating fuels, and each has an odor similar to kerosene. Humans may be exposed to these products via inhalation, ingestion, and skin contacts. Prolonged exposure may result in dry and/or cracking skin, headaches, dizziness, and irritation to the respiratory tract and to the eyes. Exposure by ingestion may result in nausea, vomiting, and central nervous system depression with symptoms ranging from headaches to coma. Fuel Oil #2 and #6 adversely affects wildlife by coating plant and animal surfaces. This coating can block vital respiratory areas which may suffocate the organisms. Fuel Oil #2 and #6 have various other adverse effects on natural ecosystems.

Cleanup Progress

On April 7, 2000 at approximately 6 pm, a fuel oil leak from an underground pipeline was detected at the Pepco Chalk Point Generating Station in southeastern Prince George's County, Maryland. The leak occurred in a section of pipeline which supplies No. 6 fuel oil to the Chalk Point facility. The pipeline was being cleaned with an internal cleaning tool and No. 2 fuel oil when the release occurred. A combination of No. 2 and No. 6 fuel oil was released into the subsurface of a tidal marsh within Swanson Creek.

Containment efforts by Pepco the night of April 7, 2000 consisted of containment boom at the mouth of Swanson Creek and around the Swanson Creek Marsh. Recovery methods were beginning on April 8, 2000 when severe weather was forecasted. Additional booms were placed around the point of release, upstream in the middle of Swanson Creek and doubled at the mouth of Swanson Creek. High winds, rain and choppy tidal conditions during the night of April 8, 2000 caused the oil to breach and crest over the containment booms in place and enter the Patuxent River and tributaries. The oil spread approximately 17 linear miles downstream and impacted approximately 40 miles of shoreline.

EPA issued Pepco an Administrative Order pursuant to Section 311 (c) of the Clean Water Act (CWA) to conduct emergency response actions to contain and recover the oil. Recovery operations were implemented around the clock. A Unified Command structure was established to direct and oversee cleanup operations. Over 800 workers and representatives from over twelve local, state and federal agencies worked on containing and removing the oil during the first few weeks of the response. The National Transportation Safety Board removed a 52-inch section of the failed pipeline for further investigation. Restrictions on boating were imposed and a precautionary advisory on the harvest and consumption of fish, crabs and shellfish from the Patuxent River was issued. A rehabilitation center for wildlife was established for oiled animals.

During the second week of the emergency, response activities were broken down into two phases. Phase I was identified as the emergency response phase and Phase II would focus on longer term cleanup. Impacted areas on the Patuxent River and its tributaries were separated into 53 operational zones. Shoreline Cleanup Assessment Teams (SCAT) began surveying the operational zones. Cleanup of sandy beaches, vegetated shorelines, man-made structures and wetlands/marshes were initiated using various mechical/manual cleanup techniques including flushing, fluidization and raking of oiled debris. On April 21, 2000, the RRT approved the use of biostimulation in the Swanson Creek Marsh. The emergency response phase was declared over on May 16, 2000.

On May 1, 2000, EPA issued a Unilateral Administrative Order, pursuant to Sections 311(c) and (e) of the CWA, to Respondents Pepco and ST Services to continue containment and recovery efforts at the impacted areas and transition into the longterm cleanup of the Swanson Creek Marsh, the Patuxent River and its tributaries. Under the longterm cleanup, Phase II cleanup guidelines were established for the 53 impacted zones. Each zone must be reinspected by SCAT and approved by the Natural Resource Trustees using the Phase II guidelines for final close-out.

Cleanup operations, SCAT inspections and Trustee sign-offs continued in the impacted areas of the Patuxent River and its tributaries through the end of October 2000. An evaluation of the remaining work at that time showed that out of the 53 impacted zones, 6 zones did not meet the Phase I and Phase II criteria and 9 additional zones did not meet the Phase II criteria. With the winter season and unfavorable weather conditions approaching, active operations were suspended and a winter monitoring program implemented for the period of November 1, 2000 through March 31, 2001. In April 2001, the 15 zones not meeting the Phase I or Phase II criteria were re-inspected and work crews remobilized to conduct cleanup operations.

Phase II operations also include a Site Characterization Study for the Swanson Creek and Marsh, Patuxent River and Tributaries, Pipeline Excavation Plan and Long Term Monitoring Plan.



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