Commentary: Proposed Million Air project could harm Seacoast drinking water

The public is following and working to understand the potential impacts of Million Air’s proposal for a fixed base operator (FBO) project at Pease Tradeport.  The project would include development of an access road, a hangar, a multi-purpose building for plane owners, and a “fuel farm."  The fuel farm would store and dispense aviation fuel and deicing liquids for private plane owners who use the FBO facility. It’s important to look at the details and possible impacts of this plan.

The proposed site includes a wetland area, which is situated over a water supply aquifer, and is near the crest of the Hodgson Brook watershed. Wetlands on and near Million Air’s proposed site are generally lower in elevation than the Pease apron and adjacent areas, meaning there is a natural flow of stormwater into the wetland. From there, groundwater flows south and east, and surface water flows towards Hodgson Brook naturally and through stormwater pipes. Hodgson Brook crosses under the Portsmouth traffic circle area then on to North Mill Pond and the Piscataqua River.

Wetlands serve important functions for both wildlife and people. They help keep water clean and plentiful and provide habitat and dependable water sources for wildlife. The wetland scientists for the Million Air project identified some of these values — sediment/toxicant retention, nutrient removal/retention/transformation, and wildlife habitat. In other words, this wetland helps to maintain and improve water quality.

Another essential function and value of this wetland area that Million Air’s scientist did not highlight is groundwater recharge to aquifers. This wetland sits above a sand and gravel aquifer.  Water reaching these wetlands recharges—or helps to refill — the aquifer.  This aquifer currently provides drinking water to the Pease International Tradeport and to Newington village from the nearby Haven well. Previously, the area immediately beneath these wetlands provided water to a drinking water well system. Although the system hasn’t been used in decades, the presence of this adjacent water supply area underscores the importance of the area for ground water recharge and protection.

Historically important to note, this area of Pease continues to be a focus of environmental clean-up from contamination from several decades from military operations at the site.  The Air Force has spent millions of dollars on clean-up efforts at Pease. There are several monitoring wells in the wetlands and surrounding parcels of land that authorities use to measure water quality as part of these remediation efforts.

Contaminants, many above state or federal action levels, can still be detected today beneath and nearby this wetland area. Testing by the Air Force has shown PFOS levels exceeding 10 times the acceptable aqueous standard in the groundwater beneath the wetlands. 

This brings us back to the proposal before the Pease Development Authority relative to a fuel farm and fixed base operator.  According to the plan offered by Million Air, the petroleum fuel and de-icing fluid (ethylene glycol) storage farm is located within 100 feet of the wetland described above.  Fuel will be delivered to the fuel farm to fill storage tanks.  The tank storage facility will distribute fuel for service trucks and flightline activities. 

Million Air proposes to dredge and fill part of the wetlands to build a new roadway. Dredging and filling the wetlands to build the road could disturb contaminated soil which could then impact water resources. While extra care can be exercised to manage excavated soil and construction dewatering fluids to avoid spreading contamination, there is still a risk that building the road will spread pre-existing contaminants.

A surface water runoff swale is designed based on current plans (Hoyle Tanner, 2022), to direct stormwater from an area just north of the fuel farm towards the wetland. The fuel farm includes the necessary federal design safeguards to prevent contamination from operations or a spill.  Sadly, even with safeguards, releases may occur that could impact the wetland, aquifer, and Hodgson Brook.

Danna Truslow is a professional geologist and hydrologist working with municipalities, agencies, and private clients throughout the Seacoast and northeastern US for more than 30 years.