A Maine shipyard contaminated with hazardous waste is vulnerable to flooding as sea levels rise, a new analysis warns.

Portsmouth Naval Shipyard is one of three extremely polluted Superfund sites in Maine examined in an analysis by The Associated Press.

The Kittery shipyard employs more than 5,000 people. Thousands more live within a few miles of the facility, which occupies a 278-acre island near the mouth of the Piscataqua River between Maine and New Hampshire. It is owned and operated by the Navy’s Naval Sea Systems Command.

The shipyard also is where, over three decades following World War II, industrial wastes were either dumped in the river or buried in fill that was used to transform several natural islands in the river into one land mass. If the surface level of the Gulf of Maine rises as much as 6 feet, which scientists say is possible by 2100, the site could be flooded enough to become multiple islands.

The Navy has made progress in cleaning up the site, spending approximately $70 million on remediation since it was added to the Superfund list in 1994, said Doug Bogen, director of the community-based organization Seacoast Anti-Pollution League. But his group is concerned about ongoing seawater infiltration into the old toxic burial sites at the facility.

“Our main concern with the shipyard is that the ocean flows in and flows out [of the river] on a daily basis. A lot of these places get saturated,” Bogen said. “With sea level rise, it could get worse.”

Shipyard spokesman Jeremy Lambert wrote Friday in an email to the BDN that since 1995, 13 remediation projects at the shipyard have been completed. He added that, based on current Federal Emergency Management Agency maps, the facility is adequately prepared for a 100-year storm and tropical storm surge, and shipyard officials are looking ahead at possible needed changes when FEMA maps are updated.

“Portsmouth Naval Shipyard understands the need to plan and prepare to mitigate adverse impacts to our mission from a variety of possible risks, including but not limited to flooding,” Lambert wrote. “This proactive approach ensures the shipyard can continue to operate as required.”

There are 98 Superfund sites across the country considered at risk from sea level rise between 1 and 1½ meters, or roughly 3 and 5 feet, and more than 200 others are at risk from severe flooding, according to AP. There are 16 Superfund sites in Maine — which contain so much hazardous waste that the EPA has ordered them to be cleaned up. But most are not considered to be vulnerable to rising seas or flooding that could result from severe storms.

The former Callahan Mine, located directly on saltwater shore frontage in Brooksville, and the former O’Connor Co. salvage yard on Eastern Avenue in Augusta, are the two other Superfund sites in Maine where water levels could rise, according to the AP.

The defunct mine property, though already partially flooded, is mostly elevated well above the waterline, making it unlikely that there will be additional threats posed by projected sea level rise. The Augusta site was cleaned up 20 years ago, and the remaining contaminants are buried and capped 150 feet away from the nearest brook, putting them at low risk of disturbance.

Of the three, the Portsmouth Naval Shipyard is in the most heavily populated area and is the only one that continues to operate as an industrial site. It has been in use as a naval shipyard since 1800 and currently is used to overhaul nuclear powered Navy attack submarines. Two-thirds of the island is a high-density industrial area that includes 376 buildings.

The AP analysis, which was prompted by flooding at industrial sites in Houston after Hurricane Harvey last summer, does not delve into how severely any coastal sites in Maine might be flooded as a result of a combination of sea level rise and tropical storm surge.

But according to a report on the shipyard issued last year by the Union of Concerned Scientists, by 2100 “roughly 25 percent of the base would be exposed to flood depths of five feet or more by a Category 1 [hurricane], compared to just 8 percent today.”

Hazardous wastes from the shipyard’s operations were routinely discharged into the Piscataqua River from 1945 to 1975 via drains and other outfalls, according to the EPA. Untreated acidic and alkaline wastes, battery acid and lead sludge, wastewater and spent baths from an electroplating operation, and other byproducts were among the substances dumped into the river.

During the same approximate period, 25 acres of tidal flats between two of the natural islands were filled with wastes, including chromium-, lead-, and cadmium-plating sludge; asbestos insulation; volatile organic compounds such as benzene; waste paint and solvents; mercury-contaminated materials; and sandblasting grit containing various metal wastes, according to EPA. Dredged sediments from the Piscataqua River also were used as fill between the islands.

The Gulf of Maine Research Institute has compiled data and developed an online tool that shows how much of low-lying areas along the Maine coast will be flooded at certain heights of sea level rise.

The tool shows 1 meter of rise would flood some areas along the shipyard’s current shoreline — in particular along Decatur, Farragut and Goodrich avenues and John Paul Jones Street. It also shows that if the sea rises as much as 6 feet, which is roughly 1 foot higher than the top of the range considered by the AP analysis, the shipyard would be cut into two islands, roughly from the drydock between Farragut Avenue and John Paul Jones Street to the northeast. The western tip of the island around Decatur and Dewey avenues also would be fully submerged.

The GMRI visual tool does not show projected flood levels between 1 meter (3.3 feet) and 6 feet, or above 6 feet.

Since 2012, 6 feet had been considered by National Oceanic and Atmospheric Administration to be the highest, but unlikely, amount of sea level rise by 2100. A new analysis by the federal agency that was released in January, however, says that sea levels could rise higher than that by the end of the century.

“Eight feet [of sea level rise] cannot be ruled out,” Radley Horton, a climate scientist at Columbia University, said Monday in a conference call with reporters. “It is possible.”

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Bill Trotter

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....