PFAS Drinking Water Well Sampling

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In August 2019 to January 2020, the Navy conducted sampling of drinking water from off-base private wells near Naval Support Activity (NSA) Mechanicsburg (Figure 1) for certain per- and polyfluoroalkyl substances, commonly known as PFAS.

Navy’s off-base PFAS private well sampling program near NSA Mechanicsburg:

62 off-base private wells sampled,

61 of the 62 results below the U.S. EPA health advisory levels for PFOA and PFOS.



The table below summarizes the results of the sampling conducted near NSA Mechanicsburg in August 2019 through January 2020. The single property that had drinking water with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) levels above the United States Environmental Protection Agency (EPA) health advisory was provided bottled water for drinking and cooking within 24 hours of receipt of the result. The analytical results for all drinking water samples are presented in the Updated NSA Mechanicsburg Drinking Water Investigation Fact Sheet (January 2020). The Navy will ensure individual property results are kept confidential to the extent permitted by law.

Number of Samples Analyzed

PFOA and/or PFOS Not Detected

PFOA and/or PFOS Detected

Below EPA Health Advisory

Above EPA Health Advisory







NSA Mechanicsburg is located in Central Pennsylvania at the eastern boundary of Mechanicsburg, in Hampden Township, Cumberland County. The facility is readily accessible from a number of highways and railroads. NSA Mechanicsburg, Figure 1, occupies nearly 824 acres of land, of which the largest portion (30 percent) is designated as grounds for storage.

Presently NSA Mechanicsburg serves approximately 4,300 civilian, military and industry partners assigned to over 40 tenant activities or commands. The largest of these are: NAVSUP Weapons Systems Supply (formerly NAVICP), with approximately 1,000 personnel; the NAVSUP Business Systems Center (formerly NAVSISA), with approximately 500 personnel and NAVSUP headquarters, with a complement of approximately 300 personnel.

The off-base private drinking water sampling program of NSA Mechanicsburg was conducted as part of the Navy’s proactive policy to address past releases of certain compounds called per- and polyfluoroalkyl substances, commonly known as PFAS. These substances may be present in the soil and/or groundwater at Navy sites as a result of historical activities using certain types of firefighting foam (aqueous film forming foam or AFFF), including response to crashes, equipment testing, and training. In 2018, following the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the Navy initiated a Preliminary Assessment (PA) to identify areas on NSA Mechanicsburg where PFAS was used and may have been released into the environment. Through the preliminary findings of the PA, the Navy identified areas where PFAS were historically used and possibly released to the environment on the base. (See Section entitled “Preliminary Assessment (PA) Summary” below for more information on the NSA Mechanicsburg PFAS PA.) As a result of these potential releases, there is possibility for PFAS to be in the groundwater on-base, and it therefore may be present in off-base groundwater in the direction that the groundwater flows away from the base. Because some of the community surrounding the facility uses groundwater as the source of drinking water, the Navy conducted voluntary drinking water sampling in a designated area (Figure 2) to evaluate groundwater used as drinking water for off-base neighbors. Results from this sampling program indicate that PFAS, specifically (PFOA) and (PFOS), generally were not detected in private drinking water wells at levels requiring action. One out of the 62 private wells sampled had results that exceed the EPA lifetime health advisory; however, there were no other exceedances in nearby wells that were sampled.

PFAS are a family of thousands of different chemicals that have been widely used in industrial and consumer products since the 1950s. The Navy developed a proactive policy to address past releases of PFAS at installations nationwide, as several PFAS are now of emerging public health concern. The most common Navy activity that could have resulted in the historical release of PFOA, PFOS, and other PFAS to the environment is the use of firefighting foam (specifically certain types of aqueous film forming foam or AFFF) for testing, training, firefighting, and other life-saving emergency responses. PFAS compounds may be present in the soil and/or groundwater at NSA Mechanicsburg as a result of historical firefighting training and response activities using the AFFF firefighting foam. Because of this historical use, there is potential for PFOA, PFOS, and other PFAS to be in the groundwater on base, and also be present in nearby private drinking water wells that are located in the direction that the groundwater flows away from the base. The designated sampling area (Figure 2) was selected because of the proximity to NSA Mechanicsburg and the general groundwater flow direction.

Records indicate the majority of residents in the sampling area purchase their drinking water from Pennsylvania American Water Company (PA American) or Suez Water Company (Suez), but a limited number of properties use or may be using a private well for their drinking water. The Navy did not request to sample water from residents in the designated off-base sampling areas who receive their drinking water from PA American or Suez as that water is tested prior to distribution. Homeowners who receive their drinking water from PA American or Suez Water should contact them with any questions regarding treatment and testing of the drinking water.

The EPA has issued a lifetime health advisory for two commonly used and studied PFAS, PFOA and PFOS, and is currently studying PFAS to determine if national regulation is needed. The EPA’s lifetime health advisory levels provide Americans, including the most sensitive populations, with a margin of protection from a lifetime of exposure to PFOA and PFOS in drinking water. The EPA’s health advisory level for lifetime exposure is 70 parts per trillion (ppt) for PFOA and 70 ppt for PFOS. When both PFOA and PFOS are found in drinking water, the combined concentrations should not exceed 70 ppt. EPA's health advisories are non-enforceable and non-regulatory and provide technical information to state agencies and other public health officials on health effects, analytical methodologies, and treatment technologies associated with drinking water contamination.

Figure 2: Designated Sampling Area

Navy PFAS Policy

Until a decision for regulating PFAS is made, the Navy has proactively developed a policy to conduct investigations at installations where there has been a known or suspected release of PFAS to the environment. The Navy’s first priority with these investigations is to ensure people are not being exposed to PFOA and/or PFOS in their drinking water at concentrations exceeding the EPA’s lifetime health advisory as a result of a Navy PFAS release. When a known or suspected release of PFAS is identified on a Navy installation, a sampling area is established 1-mile in the direction the groundwater flows away from the release site. To ensure protectiveness, the Navy offers sampling to all residents whose drinking water is supplied by private wells in this designated area. Once any potential exposure from drinking water has been addressed, the Navy will then complete the full investigation to determine the extent of these compounds in the area near the known or suspected PFAS release areas.

The Navy will provide bottled water for drinking and cooking to any properties in the designated sampling area whose water contains PFOA and/or PFOS above the EPA’s lifetime health advisory. The Navy will continue to provide bottled water until a long-term solution is implemented.

The Navy’s priority with PFAS investigations is to identify and eliminate drinking water exposures above the EPA’s lifetime health advisory level. To protect our neighbors, the Navy did not wait until all on-base investigations under CERCLA are complete at NSA Mechanicsburg to confirm if a release occurred. We conducted the off-base drinking water investigation first, based on newly identified locations where a potential PFAS release may have occurred. The designated sampling area selected near NSA Mechanicsburg lies in the direction that the groundwater flows off-base, away from these 8 sites where additional investigation is needed.

Preliminary Assessment (PA) Summary - PFAS at NSA Mechanicsburg

The Navy first evaluated the need for an off-base drinking water investigation at NSA Mechanicsburg in summer 2016 in response to a new Navy policy (DASN (E), 20 June 2016). This policy required a review of existing environmental restoration database information to identify sites with drinking water sources within 1-mile in the direction of the groundwater flow away from known or potential releases of PFAS. Off-base drinking water investigations were conducted starting in October 2017 for sites meeting this criteria. No known sites on NSA Mechanicsburg met the policy criteria in initial review. However, the Navy did not stop with these initial sites. Across the country, the Navy has been conducting base-wide evaluations to identify additional potential PFAS releases. These evaluations are being conducted under the federal cleanup program which meets the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Following CERCLA, the Navy’s installation-wide assessments are called preliminary assessments/site inspections (PA/SI), and their purpose is to verify, validate, and update the inventory of PFAS release sites for further investigation and cleanup.

The PA included four primary activities: document searches, public database searches, interviews with facility staff, and site reconnaissance. When completed, the PA will be used to determine future actions at, and near, the base. This will likely include an SI to determine if PFAS are present or absent in each potential PFAS release area. The PFAS PA for NSA Mechanicsburg identified the following 8 locations where PFAS-related operations, use, or storage potentially occurred and additional investigation is needed to determine if a release occurred. These are listed in the following table, and locations are shown on Figure 3.

Figure 3: Potential PFAS Site Locations

PATH FORWARD – PFAS at NSA Mechanicsburg

The Navy will continue the on-base environmental investigation for PFAS at NSA Mechanicsburg. Throughout this process, the Navy will continue to communicate with local residents and partner with Federal, State, and local agencies.


Per-and Polyfluoroalkyl Substances

PFAS are chemicals used in many consumer products to prevent stains, and repel water, oil, and grease. Commercial and consumer products containing these compounds were first introduced in the 1950s. They were used in a variety of products such as for the treatment of upholstered furniture fabric and carpets, in nonstick cookware, floor wax, the lining of food containers/packaging and firefighting foam. PFAS are now present virtually everywhere in the world because of the large amounts that have been manufactured and used by international consumers and industry. Once these compounds are released to the environment, they break down very slowly.

PFAS are chemicals of emerging concern, which have no Safe Drinking Water Act regulatory standards or routine water quality testing requirements. The EPA is currently studying PFAS to determine if national regulation is needed. Studies by the EPA, the Agency for Toxic Substances and Disease Registry (ATSDR), and others indicate that exposure to PFAS may cause elevated serum cholesterol levels and developmental effects to fetuses during pregnancy (e.g., low birth weight, accelerated puberty, skeletal variations) or to breastfed infants.

Department of the Navy (DON) use of PFAS

While PFAS have been used in a variety of products and substances world-wide, the most common historical use by DON has been in certain types of fire-fighting foam (specifically aqueous film forming foam or AFFF) used for testing, training, firefighting, and life-saving emergency responses. The DON is working on identifying formulations for firefighting foam that do not contain PFOA and PFOS, but will still maintain critical fire-suppression and life-saving properties. In the short term, the DON intends to use AFFF with the lowest possible concentrations of PFOA and PFOS.

Since AFFF containing PFOA and PFOS is still in use, the Navy has taken steps to prevent or minimize additional release of firefighting foam to the environment. A DON policy memo issued on 17 June 2016 directs the following actions until suitable AFFF replacements are certified:

  • Immediately cease the uncontrolled environmental release of AFFF for shoreside installations, with the exception of emergency responses.
  • Update and implement Navy and Marine Corps firefighting system requirements, as needed, to ensure fire and emergency service vehicles and equipment at DON installations and facilities are tested and certified in a manner that does not allow the release of AFFF to the environment.
  • By the end of September 30, 2017, remove and dispose of uninstalled PFOS-containing AFFF in drums and cans from local stored supplies for shore installations and ships to prevent future environmental releases.

Regulatory History

PFOA Stewardship Program

In 2006, EPA initiated the 2010/2015 PFOA Stewardship Program in which eight major companies in the United States committed to reduce facility emissions and product contents of PFOA and related chemicals on a global basis by 95% no later than 2010, and to work toward eliminating emissions and product content of these chemicals by 2015. All U.S. companies have met the program goals. To meet the program goals, most companies stopped the manufacture and import of long-chained PFAS (such as PFOA and PFOS) and then transitioned to alternative chemicals. On January 21, 2015, EPA proposed a Significant New Use Rule under the Toxics Substances Control Act to require manufacturers (including importers) of PFOA and PFOA-related chemicals to notify EPA at least 90 days before starting or resuming new uses of these chemicals in any process.

Unregulated Contaminant Monitoring Rule (UCMR)

The EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect data for contaminants suspected to be in the nation’s drinking water, but that do not have health-based standards set under the Safe Drinking Water Act (SDWA). Every five years, EPA develops a new list of contaminants that will be monitored by the nation’s large public water systems (PWSs) serving more than 10,000 people and 800 representative small PWSs (i.e., serving 10,000 or fewer people).

The Third Unregulated Contaminant Monitoring Rule (UCMR3) was issued in May 2012 and the sampling was completed in 2015. Six PFAS compounds were included in the UCMR3 contaminant list, including PFOA and PFOS. The UCMR3 results found these two chemicals were present in less than 1% of the nearly 5,000 public water systems that sampled.

In December 2016, the EPA issued the fourth Unregulated Contaminant Monitoring Rule (UCMR4). There are no PFAS included on the UCMR4 list of contaminants that require analysis.

EPA Lifetime Health Advisories

In May 2016, the EPA Office of Water issued a drinking water lifetime health advisory for PFOA and PFOS. Health advisories are not enforceable, regulatory levels; rather they are levels that provide Americans, including sensitive populations, with a margin of protection from a lifetime of exposure to PFOA and PFOS in drinking water. The health advisory is 70 parts per trillion (ppt) for PFOA and 70 ppt for PFOS. When both PFOA and PFOS are found in drinking water, the combined concentrations of PFOA and PFOS should be compared with the 70 ppt health advisory level.

Navy Policy Memoranda

Policy Memo, 21 October 2014

The DON issued a policy requiring on-base drinking water sampling for PFOA and PFOS for bases where groundwater was used as drinking water and PFAS could have been released nearby in the past. Installations that were not required to sample finished drinking water under UCMR3 that produce drinking water from on-installation groundwater sources and have an identified or suspected PFAS release within approximately 1-mile upgradient to the drinking water source were also required to sample their finished drinking water by December 2015.

Policy Memo, 14 September 2015

Similar to the October 2014 policy memo, this memo related to testing on-base drinking water. However, this memo also specified that if levels of PFOA and/or PFOS in drinking water exceeded the then current EPA health advisory (i.e., the 2009 provisional short-term health advisories), then alternative drinking water must be supplied until the PFOA and/or PFOS levels were reduced to below the EPA health advisories.

Policy Memo, 14 June 2016

This policy expanded the sampling of PFOA and PFOS at all DON installations where such sampling was not previously completed under EPA’s UCMR3 or the DON’s October 2014 policy. This memo also specified that for instances where an installation’s drinking water is purchased from a public water system, but wasn't tested under UCMR3, that the installation must sample the finished drinking water and provide alternative water if the PFOA and/or PFOS levels in drinking water exceed the EPA lifetime health advisory levels. Additionally, this policy included reporting requirements to the Deputy Assistant Secretary of the Navy’s office for all PFOA and/or PFOS drinking water results.

Policy Memo, 17 June 2016

This policy defines the DON’s intention to remove, dispose, and replace legacy AFFF that contains PFOA and/or PFOS once environmentally suitable substitutes are identified and certified to meet certain performance requirements.

Policy Memo, 20 June 2016

This policy required Navy to identify and prioritize sites for investigation if drinking water resources, on- or off-installation, are thought to be vulnerable to PFOA/PFOS contamination from past Navy/Marine Corps PFAS releases. The primary mechanism to identify potential PFAS release sites, was review of existing Navy environmental restoration databases. Sites with drinking water sources within 1-mile downgradient from known or potential releases of PFAS were considered the highest priority. This policy directed the sampling of off-base drinking water at these high priority (Priority 1) sites by September 30, 2017.

1 The 1996 Safe Drinking Water Act (SDWA) amendments require that once every five years EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems (PWSs).

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