Site Summaries 

Pease Air Force Base

Newington/Portsmouth

Contact: Scott Hilton 559-1512 

The former Pease Air Force Base site is located in the towns of Newington and Greenland and 

the City of Portsmouth. Construction of the Strategic Air Command base was completed in 1956 

and, on March 31, 1991, Pease AFB officially closed.

In 1983, the Air Force initiated installation restoration program (IRP) activities, to assess and 

control the migration of contamination that may have resulted from past operations and disposal 

practices. Based largely upon information gathered by the Air Force during IRP studies, Pease 

AFB was listed on the NPL on February 21, 1990.

A restoration advisory board (RAB), which includes representatives from local communities, 

EPA, and the state, was formed to facilitate communication and coordination concerning the IRP 

activities conducted at Pease AFB. Additional community input was acquired through Seacoast 

Citizens Overseeing Pease Environment (SCOPE), which received a technical assistance grant 

from EPA to hire a technical consultant to assist them in their review of the cleanup activities at 

Pease AFB.

NHDES has concurred with all of the 11 Superfund records of decisions (RODs) signed by EPA 

and the Air Force. By the summer of 2000, the Air Force had implemented all remedial actions 

required by Superfund.

In 1993, the Air Force completed the excavation of contaminated soils at the Jet Engine Test Cell 

site (Site 34), which removed a source of groundwater contamination and has resulted in an 

improvement in groundwater quality.

In 1994 and 1995, the Air Force excavated waste in contact with groundwater at Landfill 5. 

Concurrently, solid waste from Landfills 2, 4 and 6 was excavated and consolidated into Landfill 

5. In addition, quantities of petroleum-contaminated soil, excavated under the Underground 

Storage Tank program were placed in Landfill 5. The landfill was then covered with a multilayered cap, which is regularly inspected and maintained. Groundwater monitoring is ongoing.

In 1995, the Air Force constructed a soil vapor extraction (SVE) and groundwater treatment 

system to extract and contain contamination at Fire Department Training Area 2. A re-evaluation 

of the remedy was conducted in 2007 leading to the addition of an air sparge system, improved 

free-product removal methods and enhanced bio-remediation. The additional remedial 

components were installed and began operating in 2009. System operations and groundwater 

monitoring are ongoing.

Also in 1995, the Air Force installed sheet-piling to the top of bedrock to form a physical barrier 

around the source of groundwater contamination at Building 113 (Site 32) and constructed a 

groundwater treatment plant to treat groundwater pumped from seven hydraulic containment 

extraction wells.
At Site 32 it is technically impracticable to extract the source of contamination (dense nonaqueous phase liquids) from the subsurface. Until remedial response technologies are developed 

that the can overcome the limitations of current technologies, the Air Force will be required to 

contain the source of contamination until the threat to groundwater quality is mitigated. 

Performance monitoring is ongoing.

In 1996, the excavation and disposal of sediments in Upper Newfields Ditch and Upper Grafton 

Ditch was completed. In 1997, the Site 34/39 groundwater extraction system was brought online. This system consisted of seven extraction wells positioned to allow containment of 

groundwater contamination from Sites 34 and 39 and prevent it from migrating towards the 

Haven well. In 2001, based upon review of performance monitoring data, it was determined this 

remedial system was not operating properly and successfully in accordance with Section 120(h) 

(3) of CERCLA. Revision of the remedy through an amendment to the ROD was completed in 

2003. The revised remedy includes wellhead treatment capacity for the Haven well and 

optimization of source area pumping. Construction of the revised remedy started in 2004 and 

was completed in 2005. Remedial system and groundwater monitoring is ongoing.

In May 1997, an SVE/air sparging system became operational at Burn Area 1, which is located 

on the west side of the runway. The SVE/Air Sparge treatment system was taken off line in 

2004. Comprehensive groundwater sampling in the source area was completed in 2005 and it 

was determined additional active soil treatment was not needed and natural attenuation was 

appropriate. Plume monitoring is ongoing.

In 1997, the excavation and disposal of sediments in McIntyre Brook and Pauls Brook was 

completed.

At the Old Jet Engine Test Stand (Site 45) the SVE system has cleaned up contaminated soils to 

below regulatory standards and the system was shut down in 1998. Low levels of groundwater 

contamination are being naturally attenuated and groundwater monitoring is ongoing.

In 1999 the Air Force completed installation of a permeable reactive barrier (PRB) in overburden 

at Building 234 (Site 73) to clean up groundwater contamination associated with solvent 

releases. Performance monitoring data indicates the PRB is effective and an operating properly

and successfully (OPS) determination was made in 2004. Monitoring is ongoing.

As a result of an environmental site assessment conducted at a site where redevelopment 

activities were planned, chlorinated solvents were discovered in groundwater in the vicinity of 

Building 22. The site is now identified as Site 49. In 1997 a site investigation and soil removal 

action were completed. In the summer of 2000, the Air Force completed installation of a PRB in 

overburden and shallow bedrock to cleanup groundwater contamination. Performance 

monitoring is ongoing.

In 2000, groundwater monitoring at Site 10 (Leaded Fuel Tank Sludge Disposal Area) showed 

dramatic increases in contamination up gradient of the site. Site 10 is located on the west side of 

the runway and is an area where leaded fuel tank sludge was buried. Source investigation work 

that included geophysical investigations, geo-probe installations, test pitting and soil sampling 
was conducted between 2001 and 2003, however no contamination source was found. A 

comprehensive monitoring program was conducted to track contamination trends. In 2008 it was 

determined further investigation was needed. A plan for follow on work is currently being 

discussed with the Air Force.

In 2003, groundwater pumping was terminated at Site 35 because remedial goals were achieved.

In 2003, information was released by the Air Force that indicated waste materials containing 

residual radioactive contamination generated during cleaning of certain weapons systems in the 

1950s and early 1960s may have been buried within the former Weapons Storage Area. The site 

is being managed under the CERCLA program and geophysical and radiological survey

investigations were completed in 2003. Follow on test-pitting investigations were conducted in 

December of 2004 and did not locate any radiological waste materials. The Final Preliminary 

Assessment and Site Inspection Report (PA/SI) was completed in November 2006 and 

recommended no further action.

In addition to Superfund sites at Pease there are over 60 petroleum release sites and several 

landfill sites that are managed outside of the CERCLA program. The landfill sites have been 

capped and long-term groundwater monitoring is ongoing. Natural attenuation was the selected 

remedy for many of the petroleum release sites; however a number have undergone soil removal 

actions or have active remedial systems. Long-term groundwater monitoring at all petroleum 

release sites is ongoing to track remedial progress.

At Plume 13/14, one of the larger petroleum release sites, the initial remedial action was not 

effective. A revised remedial action plan (RAP) was developed to address high levels of soil 

contamination that remain below the water table. The final revised RAP for Plume 13/14 was 

approved in 2005 and consisted of a soil vapor extraction and air sparge system. The Plume 

13/14 remedial system is one of the largest remedial systems at the former Base. Construction for 

the SVE/AS remedial system was completed in the spring of 2008 and start-up began in early

summer. Excessive explosive vapor generation however caused the system to be shut-down. 

Additional investigations are being conducted to better understand the causes of the operational 

problems.

At Pump-House 2, another large petroleum release site the original enhanced bio-remediation 

remedy was not effective. An alternatives analysis was conducted in 2007 to determine cost and 

feasibility of a number of remedial alternatives. A SVE/AS remedial system was selected by the 

Air Force and construction was completed in 2009 with start-up of the system beginning in 2010. 

Performance monitoring is ongoing.

In addition to the clean-up activities at Pease, environmental survey and property transfer work 

was completed at the remaining Pease land parcels and the deeded property transfer to the Pease 

Development Authority (PDA) was completed in 2005. NHDES works closely with the PDA, 

Air Force and EPA to review planned development activities occurring in areas of environmental

use restrictions to ensure institutional controls and other issues associated with contaminated 

sites are addressed. The Air Force, EPA and NHDES will continue to evaluate long-term 
monitoring data to ensure response actions are optimized and remedial objectives are achieved in 

a timely and cost effective manner.