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 officiall y 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 I RP studies, Pease AFB was listed on the NPLon 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 assis tance 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 b y 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 qualit y. In 1994 and 1995, the Air Force excavated waste in contact with groundwater at Landfill 5. Concurrentl y, solid waste from Landfills 2, 4 and 6 was excavated and consolidated into L andfill 5. In addition, quantitie s of petroleum

- contaminated soil, excavated under the Underground Storage Tank program were placed in Landfill 5. The landfill was then covered with a multi

lay ered cap, which is regularly inspected and maintained. Groundwater monitoring is ongoing.
In 199 5, the Air Force constructed a soil vapor extraction (SVE) and groundwater treatment sy stem to extract and contain contamination at Fire Department Training Area 2. A re

- evaluation of the remed y was conducted in 2007 leading to the addition of an air sparg e sy stem, improved free

- product removal methods and enhanced bio

- remediation. The additional remedial components were installed and began operating in 2009. Sy stem operations and groundwater monitoring are ongoing. Also in 1995, the Air Force installed she et

- piling to the top of bedrock to form a phy sical barrier around the source of groundwater contamination at Building 113 (Site 32) and constructed a groundwater treatment plant to treat groundwater pumped from seven h ydraulic containment extraction wells.At Site 32 it is technically impracticable to extract the source of contamination (dense non

aqueous 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 qualit y i s mitigated. Performance monitoring is ongoing. In 1996, the excavation and disposal of sediments in Upper Newfields Ditch and Upper Grafton Ditch wa s completed. In 1997, the Site 34/39 groundwater extraction s ys tem was brought on

line. This sy stem 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 s ys tem was not operating properly and successfull y in accordance with Section 120(h) (3) of CERCLA. Revision of the remed y through an amendment to th e 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 remed y s tarted in 2004 and was completed in 2005. Remedial sy stem and groundwater m onitoring is ongoing. In May 1997, an SVE/air sparging s ys tem became operational at Burn Area 1, which is located on the west side of the runway . The SVE/Air Sparge treatment s ys tem was taken off line in 2004. Comprehensive groundwater sampling in the sour ce 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 McInt yr e Brook and Pauls Brook wa s completed. At the Old Jet Engine Test Stand (Site 45) the SVE sy stem has cleaned up contaminated soils to below regulatory

standards and the sy stem was shut down in 1998. L ow 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 so lvents 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 geoph ys ical investigations, geo

- probe installations, test pitting and soil samplingwas conducted between 2001 and 2 003, 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 currentl y 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 b y the Air Force that indicated waste materials containing residual radioactive contamination generated during cleaning of certain weapons sy stems in the 1950s and earl y 1960s may have been buried within the former Weapons Storage Area. The site is being managed under the CERCLA program and geoph ys ical and radiological survey investigations were completed in 2003. Follow on t est

- pitting investigations were conducted in December of 2004 and did not locate an y radiological waste materials. The Final Preliminary Assessment and Site Inspection Report (PA/SI) was completed in November 2006 and recommended no further action. In addi tion 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 w as the selected remed y for man y of the petroleum release sites; however a number have undergone soil removal actions or have active remedial sy stems. 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 s ystem. The Plume 13/14 remedial s ys tem is one of the largest remedial sy stems at the former Base. Construction for the SVE/AS remedial sy stem was completed in the spring of 2008 and start

- up began in early summer. Excessive explosive vapor generation however caused the s ys tem 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 remed y was not effective. An alternatives anal ys is was conducted in 2007 to determine cost and feasibility of a number of remedial alternatives. A SVE/AS remedial sy stem was selecte d by the Air Force and construction was completed in 2009 with start

- up of the s ys tem 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 th e remaining Pease land parcels and the deeded propert y transfer to the Pease Development Authorit y (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

- termmonitoring data to ensure response actions are optimized and remedial obj ectives are achieved in

a timely and cost effective manner.