PORTSMOUTH — The Air Force has agreed to reimburse Portsmouth for as much as $14.3 million for the city’s costs to construct a water treatment facility to remove two types of dangerous PFAS chemicals from city-owned wells at the former Pease Air Force Base.

The new treatment facility includes a dual filtration system consisting of both resin and granular activated carbon filters.

The agreement follows extensive research, pilot testing and design of a system to treat the PFOS/PFOA contamination, according to city officials. Previous agreements with the Air Force have included the funding of a demonstration project for activated carbon filters for the Harrison and Smith wells, filters that have been in service for these wells since September 2016.

The new treatment facility will treat those wells and the Haven well, which has been closed since May 2014 after Air Force officials found high levels of PFAS contamination in the well.

Dr. Steve TerMaath, chief of the Air Force’s Base Realignment and Closure (BRAC) Program Management Division, said “working directly with the city, the Pease Development Authority and state and federal regulators to address PFOS/PFOA has been a top priority at Pease since the discovery of these emerging contaminants in 2014.”

“The leadership provided by the city and active communication and collaboration among the parties have been instrumental to the success of this initiative,” TerMaath said in a city press release issued Friday.

Thousands of people working at the former air base – and children attending two day-care centers there – were exposed to the contaminated water before the Haven well was closed. The city closed the well at Pease International Tradeport after the Air Force found high levels of perfluoroctane sulfonic acid, or PFOS, in the well. Officials believe the PFAS contamination came from firefighting foam used extensively at the base.

The Environmental Protection Agency in May 2016 set permanent health advisories for PFOS and perfluorooctanoic acid, or PFOA at 70 parts per trillion.

In addition to being a suspected carcinogen, the Agency for Toxic Substances and Disease Registry states PFAS exposure can harm childhood development, increase cholesterol levels, hurt the immune system and interfere with the human body’s hormones.

Andrea Amico of Portsmouth, co-founder of the community group Testing for Pease, called the announcement about the funding for the treatment facility “great news.”

“It’s very positive that the city is looking at a dual system because the community has real concerns about the effectiveness of GAC-only (granular activated carbon),” Amico said Friday. “The community continues to be concerned with all the PFAS in the water at Pease, not just PFOA and PFOS.”

“This is a really positive step because we want them to treat as many PFAS chemicals as possible,” Amico said.

Portsmouth Deputy Director of Public Works Brian Goetz said Friday “we are pleased that the Air Force has been a partner in addressing this complicated issue involving a contaminant that little was known about in 2014. With this agreement in place we anticipate bidding the project this fall with an early 2019 start date for construction.”

City Manager John Bohenko said it is “great that the city was able to negotiate the $14 million agreement with the Air Force.”

“It’s an official commitment from them and I assume there will be processes in place where the city can draw down on the money,” Bohenko said Friday.

He acknowledged the planned dual filtration system for the water treatment facility “has the opportunity to be able to do other things” than just remove PFOS and PFOA from the water.

“Again, I think it will have other capabilities,” Bohenko said Friday.

The facility will be located off Grafton Road where the city has been operating a treatment facility to treat the Smith and Harrison wells, Bohenko said.

Goetz said Friday the city has now received a total of $16.8 million from the Air Force to deal with the PFAS contamination.

He expects construction of the treatment facility will take about 18 months to complete.