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The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated the potential for contamination at the Naval Support Activity, Mechanicsburg (NSA) to cause harm to human health. The NSA, a naval support facility, encompasses 824 acres of land in Hampden Township and Cumberland County, Pennsylvania. In the 1940s, the installation was created to repair Navy ship parts, and its responsibilities were later expanded to undertake additional responsibilities, such as managing conventional ammunition and providing maintenance and engineering services for the installation. The installation also served as a repository for a variety of metal ores received as war payment and a reprimand in the early 1950s.

The former NSA operations have resulted in various fuel and chemical spills, some of which have reached underlying groundwater and a stormwater drainage ditch. The U.S. Environmental Protection Agency (EPA) listed NSA on its National Priorities List on May 31, 1994, because of contamination detected at the site. The primary contaminants of concern are metals (such as lead and arsenic in surface soil) and polychlorinated biphenyls (PCBs) (in sediment and fish). These contaminants, as well as volatile organic compounds (VOCs) (in groundwater), have been detected at levels above ATSDR's health-based comparison values.

As part of the public health assessment process, ATSDR conducted site visits and met with representatives from NSA in 1996 and 2000. At the time of the visits, ATSDR identified ways in which people might come in contact with environmental contamination associated with NSA, including contact with contaminants in groundwater, surface soil, surface water and sediment, and consumption of Trindle Spring Run fish. However, ATSDR did not identify any environmental health hazards posing immediate threats to the public.

After conducting a thorough evaluation of available environmental monitoring data and key potential exposure situations, ATSDR developed the following conclusions about potential exposure hazards (also summarized in Table 1):

Groundwater: VOCs, such as those found in cleaning solvents, are the primary contaminants of concern in groundwater. There is, however, no public exposure to groundwater contaminants. Groundwater underlying NSA has never been used as a source of drinking water, nor will it be used for potable water in the future. NSA and the surrounding community receive drinking water from municipal water sources that safely meet federal and state drinking water standards.

Soil: ATSDR reviewed on-site surface soil data and evaluated potential exposures at NSA locations where past military operations resulted in contamination. At these sites, ATSDR concluded that soil contaminants do not pose a public health hazard because either contaminants in on-site soil were detected at levels that do not pose a public health hazard and/or contamination was located in areas where public exposure was infrequent or unlikely.

Surface Water and Sediment: ATSDR reviewed surface water and sediment quality data from the NSA stormwater drainage ditch (SWDD) and the Trindle Spring Run. PCBs were detected in the sediment along the ditch and in the creek. Some contamination appears to originate from off-site sources along the SWDD and along the upstream reach of Trindle Spring Run, but NSA installation restoration program (IRP) sites have also contributed to the pollutant load. Minimal, if any, public exposure occurs to the surface water and sediment of the SWDD and the creek. Much of the SWDD is vegetated and fenced to restrict access, and local residents do not swim in or drink from Trindle Spring Run. Incidental exposures to the detected levels of contaminants are not expected to pose a public health hazard.

Fish: Fish in Trindle Spring Run have been impacted by PCBs, some of which probably originated from NSA operations. If consumed in sufficient quantities, PCBs can cause adverse health effects. The Pennsylvania Department of Environmental Protection (PADEP) issued a fish consumption advisory in 1998 encouraging people to limit consumption of Trindle Spring Run rainbow trout to one meal a month. ATSDR reviewed available fish data for the stream and determined that Trindle Spring Run anglers can best protect themselves from the harmful effects of PCBs by adhering to the PADEP fish consumption advisory.

Based on review of available information, exposure to groundwater, on-site surface soil, and surface water/sediment pose No Public Health Hazard or No Apparent Public Health Hazard. ATSDR also concludes that the consumption of locally caught fish posed an Indeterminate Public Health Hazard in the past, but should pose no Public Health Hazard for people adhering to the PADEP limited fish consumption advisory for rainbow trout now and in the future.

Table 1. Exposure Hazards Summary Table--NSA Mechanicsburg

Exposure Scenario Time Frame Exposure
Hazard Actions Taken/Recommended
Exposure to groundwater contaminants underlying NSA Past
Past: no
Current: no
Future: no
No public health hazard • No actions are necessary to protect public health since groundwater contamination has not reached off-site drinking water sources (e.g., Union Water Company water supply well).
• The Navy is conducting long-term groundwater monitoring at Site 3 and at Site 9, the stormwater drainage ditch (SWDD).
Exposure to soil contaminants at NSA Mechanicsburg Past
Past: limited
Current: no
Future: no
No apparent public health hazard • The Navy has installed fences to restrict access to areas of contaminated soil and/or removed the contaminated soil.
Exposure to surface water and sediment contaminants Past
Past: limited
Current: limited
Future: limited
No apparent public health hazard • The Navy has conducted remedial action to manage PCB- contaminated sediment at Site 9, the SWDD. These measures include excavating contaminated sediment, constructing gabion dams, and extending the fences along the ditch.
• The Navy conducted a five-year annual monitoring plan for sediment in the SWDD. This program ended in 1997.
• The Navy plans to close Site 9 in fiscal year 2002/2003.
Consumption of locally-caught freshwater fish Past
Past: yes
Current: limited, if any
Future: limited, if any
Past: Indeterminate
Current and Future: No public health hazard for people following the limited fish consumption advisory
• PADEP and the Navy have sampled fish from Trindle Spring Run. The data indicated that rainbow trout have accumulated PCBs.
• In 1998, PADEP issued a limited fish consumption advisory that encourages people to limit their consumption of Trindle Spring Run rainbow trout to one meal a month.
Exposure to lead via paint scraping Past
Past: limited, if any
Current: no
Future: no
No apparent public health hazard • Navy soil monitoring determined that lead contamination (up to 400 parts per million [ppm] lead) extends no more than 80 feet from any one water tower.
• The Navy dismantled the water towers and removed the structures and surrounding contaminated soil from the site.
Key: NSA = Naval Support Activity; ppm = parts per million; SWDD = stormwater drainage ditch; PADEP=Pennsylvania Department of Environmental Protection;
PCBs = polychlorinated biphenyls.


Site Description and History

The Naval Support Activity at Mechanicsburg (NSA), formerly known as the Ships Parts Control Center (SPCC) and then as the Naval Inventory Control Point (NAVICP), is located in Hampden Township and Cumberland County, Pennsylvania, located approximately 7 miles west of Harrisburg, Pennsylvania (see Figure 1). The installation encompasses approximately 824 acres, most of which are paved or covered with storage areas, warehouses, and railroad tracks. Only about one-fifth of the site is undeveloped, unpaved or covered with grass. Public access to the site is restricted by perimeter fences and gated entrances at the north, south, east and west boundaries of the site (Foster Wheeler 2001).

The installation was first created for the global management of Navy ship repair parts in the 1940s, and was expanded to undertake additional inventory management responsibilities, such as managing conventional ammunition and providing maintenance and engineering services for the installation. By 1943, 57 semi-permanent warehouses had been built to support their storage needs. The installation also served as a repository for a variety of metal ores received as war payment and reprimand in the early 1950s (EA 1999a, 1999b). At one time, about 39 stock piles of ores, which included chromite, manganese, kyanite, and aluminum oxide ores, were maintained by the Defense National Stockpile in the southwest portion of NSA. Only four grass-covered piles and one additional pile staged on concrete currently exist at NSA.

On October 2, 1995, the former Aviation Supply Office in Philadelphia and the SPCC in Mechanicsburg merged to form the NAVICP. The merger was performed to place all of the Navy's Program Support Inventory Control Point functions under a single command, reducing costs and infrastructure, as well as standardizing inventory management procedures. In fall 1998, host activities at NAVICP (e.g., environmental and safety services, facilities, and engineering) were transferred to Commander in Charge of Atlantic Fleet, which resulted in an installation name change to Naval Support Activity, Mechanicsburg, Pennsylvania. More than 30 other tenants are also residents at the installation, including the Defense Logistics Agency, Naval Sea Logistics Center, and Naval Fleet Material Support Office. NSA controls the inventory management of weapons and equipment, end items, and non-weapons system related items (EA 1999a, 1999b).

Remedial and Regulatory History

The Navy began environmental investigations at NSA in the mid-1980s under the Department of Defense's Installation Restoration Program (IRP). Most of investigations focused on former waste disposal practices to determine if they posed any threats to public health or the environment. Through these investigations, the Navy found contamination, including solvents, metals, and polychlorinated biphenyls (PCBs), in soil and in groundwater at several locations of the site.

As a result of the contamination detected at NSA Mechanicsburg, the U.S. Environmental Protection Agency (EPA) added NSA (at the time it was known as SPCC) to the National Priorities List (NPL) of sites to be investigated on May 31, 1994. The NPL is part of EPA's Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as "Superfund." The Navy is planning on entering into a Federal Facility Agreement (FFA) with EPA and Pennsylvania Department of Environmental Protection (PADEP) to outline a comprehensive strategy for conducting environmental investigations and complete remedial actions on NSA property where hazardous materials may have been disposed, spilled, or stored (EA 1999b).

Under the IRP, the Navy has investigated 16 sites (Sites 1, 2, 3-soil, 3-groundwater, and 4 through 15), including former landfills, burn pit areas, storage areas, underground fuel tanks, and the stormwater drainage ditch (see Figure 2). The Navy has also conducted interim removal actions to control or reduce the spread of contamination from these areas. Actions completed to date include removal of contaminated soil from several of the IRP sites. The Navy also removed highly contaminated sediment from its stormwater drainage ditch and installed gabion dams along the ditch to limit sediment migration and extended fencing to prohibit public access to the ditch. By 1992, more than 5,700 tons of contaminated sediment had been removed from the first half mile of the ditch and disposed of off site. Only four of the 16 sites remain open for investigation (Navy 2001).

Through record review and site investigations, the Navy identified over 49 areas of concern (AOCs) that include small hazardous waste storage areas and hazardous material handling areas suspected of contamination, but not associated with IRP sites. Recently, EPA and PADEP have allowed the Navy to eliminate 40 of the AOCs for further consideration because of minimal threat to human health and the environment; therefore, only 9 AOCs (AOCs 1-A, 9-A, 10-A, 16, 17, 21, 38, 51, and 52) remain under investigation. The Navy conducted fieldwork at most of the remaining AOCs in 2000. Table 2 lists the 16 IRP sites and 9 AOCs, and the status of their completed or planned remedial investigations.

By January 2001, the Navy, EPA, and PADEP reached a final clean-up decision, known as a Record of Decision (ROD), at two IRP sites, Site 1 (Carter Road Landfill) and Site 3 soils (Ball Road Landfill and burn pits). The ROD for Site 1, signed in September 1998, calls for land-use restrictions and the ROD for Site 3 soils, signed in September 2000, summarizes a soil removal action that had already occurred (NSA 2001; Navy 2001). Similar to Site 1, the final remedy for Site 3 soil is a restriction on residential land-use of the site (Navy 2001).

ATSDR Activities

The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial visit of the NSA in April 1996. The purpose of the visit was to collect information necessary to rank the site according to its potential public health hazard, to identify public health issues related to environmental contamination at the facility, and to identify community health concerns. During the visit, staff met with Navy personnel and representatives from federal and state agencies. Based on discussions, the site visit, and data review, ATSDR concluded at the time that there was little potential for immediate threats to human health, but that several potential exposure pathways and community health concerns required further evaluation.

As part of its ongoing involvement at NSA, ATSDR revisited the site and met with representatives from the Navy in November 2000 to obtain updated information on environmental studies and community concerns.


When assessing a site, ATSDR seeks to identify the people in the site's vicinity who are more likely than usual to be exposed to contamination, as well as populations (such as young children and the elderly) that are especially sensitive to exposure. To do this, ATSDR uses demographic (or population) information and land use information. Demographics also provide details on residential history in a particular area--information that helps ATSDR assess time frames of potential human exposure to contaminants. Demographic information for the residential areas surrounding NSA is presented in this section. (Note that proximity, in itself, is not an adequate indicator of exposure to site-related contaminants. Whenever possible, proximity measures must be supplemented with environmental pathway information to evaluate exposed populations.)

At its peak in 1945, NSA employed about 5,332 civilians, 507 officers, and 676 enlisted personnel (NAVCIP 2001). Today, NSA employs about 5,000 civilian and 190 military personnel. Some military personnel live with their family members in the residential housing area located in the northwest section of NSA. The Borough of Mechanicsburg, a community of over 25,000 people, is situated to the southwest of the site. Other nearby towns include the Borough of Camp Hill to the east, New Cumberland to the southeast and Carlisle to the west. Harrisburg, the nearest metropolitan area, is located 7 miles east of the site.

Land Use and Natural Resources

NSA is located in Cumberland County, Pennsylvania, within Hampden Township, and northeast of the Borough of Mechanicsburg. Land use at the site is varied and includes the following broad categories: storage (30%), buildings (25%), roads (13%), and railroads (11%). About 155 buildings are situated at the installation, most of which are used for storage. Other uses include; administrative and maintenance and production operations. NSA Mechanicsburg has one child development center, which is located near the northern boundary of the installation and away from any areas of contamination (Navy 2001). A nine-hole golf course also is situated along the northeastern boundary of the installation (Navy 2001).

Access to NSA is restricted to military personnel, on-base residents, and civilian employees. Members of the general public and contractors may enter by passing a security guard station, registering their vehicle, and obtaining a pass. The installation is surrounded by a perimeter fence that is regularly patrolled. Once within the NSA boundaries, access to contaminated areas is not limited except for several fenced off areas.

Land use varies beyond the boundaries of NSA. Land to the west is used for a combination of industrial, residential, and a municipal recreational park. Land to the east and southeast is primary residential with some commercial property, including a fuel storage area. The Hampton Elementary School and athletic fields lie immediately outside the northeast perimeter of the NSA. The Mechanicsburg Borough Park, a municipal park, is west of NSA. Neighboring industries, Overnight Trucking and Capitol Products, to the north have been identified as sources of chemical spills and releases, primarily with petroleum hydrocarbons and chlorinated hydrocarbons, respectively (EA 1999c).

Trindle Spring Run, a cold-water fishery, flows about 2 to 3 miles west/northwest of the NSA site before emptying into Conodoquinet Creek. Conodoquinet Creek supplies drinking water for a municipal water supplier serving the Borough of Mechanicsburg area. Conodoquinet Creek flows eastward eventually meeting the Susquehanna River along the western boundary of Harrisburg (EA 1999c).

Quality Assurance and Quality Control

In preparing this public health assessment (PHA), ATSDR reviewed and evaluated information provided in the referenced documents. Documents prepared for the CERCLA program must meet standards for quality assurance and control measures for chain-of-custody, laboratory procedures, and data reporting. The environmental data presented in this PHA are from Navy site and remedial investigations. Based on our evaluation, ATSDR determined that the quality of environmental data available in site-related documents for NSA is adequate for making public health decisions.



What is meant by exposure?

ATSDR's public health assessments (PHAs) are exposure (or contact) driven. Given sufficient exposure levels, chemical contaminants disposed or released into the environment have the potential to cause adverse health effects. However, a release does not always result in exposure. People can only be exposed to a contaminant if they come in contact with that contaminant. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin contact with a substance containing the contaminant.

How does ATSDR determine which exposure situations to evaluate?

ATSDR scientists evaluate site conditions to determine if people could have been (a past scenario), are (a current scenario), or could be (a future scenario) exposed to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure to contaminated media (soil, water, air, waste, or biota) has occurred, is occurring, or will occur through ingestion, dermal (skin) contact, or inhalation. ATSDR also identifies an exposure pathway as completed or potential, or eliminates the pathway from further evaluation. Completed exposure pathways exist if all elements of a human exposure are present. (See Appendix B for a description of the elements of a completed exposure pathway.) A potential pathway is one that ATSDR cannot rule out, because one or more of the pathway elements can not be definitely proved or disproved. A pathway is eliminated if one or more of the elements is definitely absent.

If exposure was, is, or could be possible, ATSDR scientists then consider whether contamination is present at levels that might affect public health. ATSDR scientists select contaminants for further evaluation by comparing them against health-based comparison values (CVs). CVs are developed by ATSDR from scientific literature available on exposure and health effects. These CVs are derived for each of the different media and reflect an estimated contaminant concentration that is not expected to cause adverse health effects for a given chemical, assuming a standard daily contact rate (e.g., amount of water or soil consumed or amount of air breathed) and body weight.

CVs are not thresholds for adverse health effects. In order to be conservative and protective of public health, ATSDR CVs are generally based on contaminant concentrations many times lower than levels at which no effects were observed in experimental animals or human epidemiologic studies. If contaminant concentrations are above CVs, ATSDR further analyzes exposure variables (for example, duration and frequency), the toxicology of the contaminant, other epidemiology studies, and the weight of evidence for possible health effects.

Some of the CVs used by ATSDR scientists include ATSDR's environmental media evaluation guides (EMEG), reference dose media evaluation guides (RMEG), and cancer risk evaluation guides (CREG) and EPA's maximum contaminant levels (MCL). MCLs are enforceable drinking water regulations developed to protect public health. CREGs, EMEGs, and RMEGs are non enforceable, health-based CVs developed by ATSDR for screening environmental contamination for further evaluation.

More information about the ATSDR evaluation process can be found in ATSDR's Public Health Assessment Guidance Manual at or by contacting ATSDR at 1-888-42ATSDR.

If someone is exposed, will they get sick?

Exposure does not always result in harmful health effects. The type and severity of health effects that occur in an individual from contact with a contaminant depend on the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, lifestyle, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together, these factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant in the environment.

There is considerable uncertainty about the true level of exposure to environmental contamination. To account for the uncertainty and to be protective of public health, ATSDR scientists typically use worst-case exposure level estimates as the basis for determining whether adverse health effects are possible. These estimated exposure levels usually are much higher than the levels that people are really exposed to. If the exposure levels indicate that adverse health effects are possible, then a more detailed review of exposure combined with scientific information from the toxicological and epidemiologic literature about the health effects from exposure to hazardous substances is performed. Figures 3 provides an overview of ATSDR's exposure evaluation process.

What exposure situations were evaluated for NSA, Mechanicsburg?

ATSDR analyzed data for NSA's 16 IRP sites and available, but limited, information for the 9 AOCs under investigation to determine if they are associated with past, current, or future public health hazards. Table 2 provides a description of each site and a summary of our evaluation. Our review indicated that most sites at NSA are not associated with any known public health hazards because: (1) no site-related contaminants are present, (2) contaminant concentrations detected are too low to pose a health hazard, or (3) past and current exposure to the general public has been prevented.

From this review, however, ATSDR did identify several pathways at NSA for further evaluation, including one completed exposure pathway (fish consumption) and three potential exposure pathways (groundwater, surface soil, and surface water/sediment). In response to community concern, ATSDR also evaluated potential exposure to lead paint that was removed from the base water towers during maintenance activities. Our evaluation on exposure pathways is summarized in Table 3 and discussed in greater detail in the following discussion. To acquaint the reader with terminology and methods used in this PHA, Appendix A provides a glossary of environmental and health terms presented in the discussion, Appendix B outlines the assessment methodology and lists the comparison values used in this PHA, and Appendix C describes the methods ATSDR used to evaluate whether health hazards exist at the NSA, Mechanicsburg site. Comments received during public comment review period of this document (February 28, 2002 to April 15, 2002) and ATSDR's response to the comments are provided in Appendix D.

Evaluation of Groundwater Exposure Pathway

After reviewing the available groundwater monitoring data and exposure information, ATSDR has drawn the following conclusions:

  • Former operations and waste disposal practices at NSA have contaminated the groundwater beneath the site with VOCs, primarily TCE.

  • No drinking water wells are located in or near the area of contamination.

  • Drinking water for NSA and most residents in the Borough of Mechanicsburg is supplied by municipal water suppliers. Routine testing of the drinking water supply required by EPA and PADEP ensures that the water has been and will remain safe to drink.


NSA Mechanicsburg's Hydrogeology

NSA is located between the Conodoguinet Creek and the Yellow Beeches Creek watersheds, which are part of the Lower Susquehanna Subbasin. Groundwater flows within three water-bearing rock formations in the NSA area, the Rockdale Run Formation, the St. Paul Group, and the Pinesburg Station Formation. The Rockdale Run Formation is the principal water bearing unit for the immediate area around NSA, with a calculated median sustained yield of 405 gallons per minute (gpm). The St. Paul Group is also a potential drinking water source. Its calculated median sustained yield is 82 gpm. A third formation, the Pinesburg Station Formation, is typically a poor yielding water source. Although each rock formation has varying characteristics, groundwater flows between the formations and the collectively the formations are considered one aquifer (Navy 2001).

The groundwater surface, or the water table, varies seasonally, ranging from 5 to 15 feet below the surface in spring and early summer to about 80 feet below the surface in the late summer and fall (EA 2001a; EPA 2001). A regional groundwater divide crosses NSA between Site 1 and Site 3. Because of the divide, groundwater from Site 3 flows north along a north-northwest gradient and groundwater from Site 1 flows south (see Figure 2).

Groundwater Use

NSA and most residents in the Borough of Mechanicsburg depend on drinking water supplied by one of two municipal water systems: the Pennsylvania-American Water Company (PAWC) or the United Water Pennsylvania. PAWC operates three treatment plants that furnish a combined total to the Mechanicsburg community of 19 millions gallons of water per day. One plant draws water from the Conodoguinet Creek and the other two plants draw from the Yellow Breeches Creek (PAWC 2001). United Water Pennsylvania relies on a combination of surface water and groundwater sources. They operate one treatment plant for surface water drawn from the Yellow Breeches Creek and another plant for groundwater drawn from a 115-foot deep well located on Market Street, about 3,500 feet from the southwest corner of the NSA site. United Water Pennsylvania serves about 25,000 residents of the Borough of Mechanicsburg; residents south of the Cumberland Parkway receive treated water originating from surface water sources only while residents north of the parkway obtain treated water originating from both surface water and groundwater sources (United Water Pennsylvania 2001).

Both PAWC and United Water Pennsylvania routinely monitor their water and treat as needed according to standards set by the EPA and PADEP. Although not required by regulations, United Water Pennsylvania also tests its groundwater for the volatile organic compounds (VOCs) benzene, toluene, and xylene, which are components of gasoline. They have equipped their groundwater treatment system with an air stripping unit to remove any VOCs that may be present in the raw groundwater (United Water Pennsylvania 2001).

NSA formerly stored municipal water in three steel water towers designated 16-A, O-C, and 504A. The water tanks were originally needed to maintain adequate pressure in the water distribution system to operate fire hydrants throughout the installation. High costs associated with maintaining the tanks prompted the Navy to upgrade the NSA water system. As part of the upgrade, the Navy removed the towers from service and demolished the structures in the summer of 2000 (Foster Wheeler 2001).

Groundwater Quality

On-Base Groundwater Monitoring Wells

Past activities and waste disposal practices have impacted groundwater underlying the site. Monitoring to date has revealed that contaminants, including VOCs, semivolatile organic compounds (SVOCs), and PCBs, have reached the underlying groundwater, some at concentrations above ATSDR CVs for drinking water. These contaminants have been encountered predominantly at IRP Sites 3, 7, and 9. Interpretations of groundwater flow based on hydraulic gradient and water-table contours indicate that contaminants at Sites 7 and 9 could have originated at Site 3. Site 3 originally served as a quarry for borrow materials used in construction activities at NSA. Two large quarry pits at the site had been used for waste disposal (EA 1999b).

Table 4 lists the maximum concentration of a contaminant detected in groundwater beneath the site, the locations of the maximum detection, and the comparison value for that contaminant. Some of the highest levels of contamination were found in the groundwater samples collected from Site 3 burn pits. Contaminants such as VOCs, SVOCs, and metals were found there in concentrations that exceed comparison values. Of the VOCs detected at Site 3, trichloroethylene (TCE) has been detected most frequently and in the highest concentrations. TCE concentrations reached a high of 11,131 ppb in 1990 at a well located at the Site 3 burn pits. (1) Groundwater was not sampled at Site 3 between 1992 and 1996. Much lower TCE levels ( 23 ppb) were recorded in 1997 following the removal of the contaminated soil from the Site 3 burn pits in 1994, but the groundwater beneath Site 3 has not been sampled since 1997.

Concentrations of TCE at Sites 7 and 9 (up to 57 parts per billion [ppb] in 1992) also exceed ATSDR screening values, but are much lower than levels reported at Site 3 (EA 1999c). Other VOCs found at elevated concentrations at Site 3 include benzene (up to 15.12 ppb) and tetrachloroethlyene (PCE) (up to 400 ppb). (2) Like, TCE, concentrations of these VOCs were much lower in 1997 sampling.

Even though VOCs in groundwater have decreased substantially since the removal of contaminated soil from the Site 3 burn pits, the Navy suspects that another source of contamination lies within the bedrock at the site because of the discovery of "floating product" within certain Site 3 monitoring wells. Floating product is believed to be related to fuel and oil waste disposed of at the site. The Navy will install several new monitoring wells, including two deep wells at the most contaminated location, which will be used to assess free and dissolved phase VOCs that may reside in the underlying aquifer (EA 2000a, 2001; NAVICP 2001).

VOCs have also occurred sporadically and in lower concentrations in groundwater samples collected from other IRP sites, including Sites 1, 5, 6, 8, and 10. Based on flow patterns and hydrogeologic gradients, it appears that VOCs from Site 3 may have also migrated north/ northeastward to Sites 6 and 8 (EA 1999c).

Metals have also been detected in unfiltered groundwater samples collected from NSA, but less consistently than VOCs and without any distinct trends. (3) Metals exceeding ATSDR CVs or EPA maximum contaminant levels (MCLs) include antimony (up to 257 ppb), arsenic (up to 177 ppb), barium (up to 2,190 ppb), beryllium (88.6 ppb), cadmium (149 ppb), chromium (up to 1,030 ppb), and lead (up to 27,000 ppb). These metals were detected most frequently and in the highest concentrations in samples collected from Site 3, followed by Sites 1, 2, 5, 7, 8, and 9.

Off-Base Groundwater Monitoring Wells

During a 1991-1992 dye tracer study, the Navy injected dye in the groundwater underlying Site 3 to track groundwater flow. Virtually all the groundwater flow emanating from Site 3 was found to pass through Site 7 and Site 9 before emerging at two springs located north of the NSA site: Spring SSP-08 on the Trindle Spring Run and SRS-01 on the Conodoquinet Creek. Water samples taken from these springs contained the VOCs TCE (up to 57 ppb) and PCE (up to 7 ppb) at levels above CVs for drinking water (EA 1999c). Other sources of VOCs may be contributing to the discharges measured at these springs. Industrial property, such as Capitol Products and Overnight Trucking, lie between the springs and NSA. Monitoring of groundwater at the Capitol Products property showed TCE, PCE, and 1,2-dichloroethylene in groundwater at levels well above their CVs. Likewise, the VOC concentrations reduced substantially following the removal of contaminated soil from the Capitol Products property in 1994-1996 (EA 1999c).

Evaluation of Potential Public Health Hazards

Municipal water: The majority of Mechanicsburg residents receive their drinking water from either the PAWC or United Water Pennsylvania. The Safe Drinking Water Act requires public suppliers to test their water regularly for contaminants, including TCE. Each of the Mechanicsburg public water suppliers tests for TCE in their system or production wells either on a quarterly or annual basis. Those wells exceeding the analytical detection limit for TCE are sampled on a quarterly basis. In recent sampling of the public water supplies, no TCE was detected at concentrations above ATSDR's CV or EPA's MCL. Should a contaminant be detected above its MCL, the supplier is required to switch to an alternative drinking water source or to purify the contaminated water. TCE has been detected at the spring along the Conodoquinet Creek, which serves PAWC and United Water Pennsylvania, but municipal drinking water is tested and it meets safe drinking water standards.

NSA Drinking Water: Although the groundwater beneath NSA contains high concentrations of volatile organic compounds (VOCs), it has never been used as a source of drinking water. Over its years of operation, NSA has supplied its employees with drinking water from PAWC or United Water Pennsylvania. Monitoring of the public water supply indicates that the water consistently meets safe drinking water standards. Future exposure to contaminated groundwater is not expected to occur because NSA does not anticipate using the contaminated groundwater for drinking or other domestic uses and the installation will continue to provide its employees with drinking water from one of the municipal water suppliers.

Private Wells: Mechanicsburg residents who receive their drinking water or other domestic use water from private wells are not required to test their well water. The Navy tested two off-base private wells located about 3,000 feet west of the property that are reportedly used for drinking water. Using results from the dye tracer study, the Navy identified these wells as possibly being impacted by NSA contamination (PADER 1990). The Navy analyzed the well-water samples for VOCs, semi-volatile organic compounds (SVOCs), metals, and pesticides, but the results indicated that analytes were either not detected or detected at levels below ATSDR's CVs and EPA's MCLs (EA 1999b). To date, the regulators and Navy are not aware of any other downgradient wells from the site that have been or are expected to be impacted by NSA contaminants.

The Navy has off-site monitoring wells to determine the outer limits of NSA-related contaminant migration in the groundwater while they continue to monitor groundwater in on-site wells on a periodic basis to further identify areas of contamination that could possibly threaten off-site private wells. The Navy will continue to monitor groundwater movement from the site and off-site groundwater quality to identify and diminish the threat of potential health hazards. Because there is no exposure, ATSDR concludes that groundwater poses no public health hazard.

Evaluation of Soil Exposure Pathway

After reviewing the available soil monitoring data and exposure information, ATSDR has drawn the following conclusions:

  • Lead and arsenic are the primary contaminants of concern in NSA surface soils. Some of the highest levels were found in the past in soil samples collected from the installation water towers (Site 14). ATSDR does not expect that people came in contact frequently or for long periods of time with lead or other soil contaminants at levels that might be harmful to either adults or children. The water towers and contaminated soil were removed from the base in 2000.

  • Harmful exposures to contaminated soil at other areas of the installation are largely prevented because the land surface is either paved, covered by grass or buildings, or lies in restricted land use areas.


Description of Site

NSA occupies almost 824 acres of land on predominantly flat terrain, with slopes increasing toward the property boundaries. Elevation ranges from 410 to 458 feet above mean sea level. The largest flat area at NSA is found at the warehouse area, which slopes at a 0.5 % grade to the east and west. Most of the land is covered with buildings, roads, or railroads. Undeveloped grass covered land makes up about one-fifth of the property (EA 1999b).

Nature and Extent of Contamination

As a result of routine operations and waste disposal practices at NSA, hazardous materials have been spilled or released to on-site soil. The Navy sponsored a series of investigations to characterize the type and amount of surface soil contamination at on-site locations where contamination was suspected. Surface soil samples were collected and then tested for VOCS, SVOCs, metals, and PCBs. Selected samples were also tested for pesticides. ATSDR reviewed these data to assess possible public health hazards and to form the basis for our conclusions.

For many locations at the installation, soil samples revealed no contamination, low levels of contamination (below CVs), or infrequent detections above health-based CVs. Areas where contaminant levels in surface soil exceeded CVs include Site 3, Site 11, and Site 14. PCBs and metals, primarily lead and arsenic, were the most predominant contaminants identified in the soil samples. ATSDR summarizes the surface soil sampling results for Site 3, Site 11, and Site 14 in Table 5 and describes the data in further detail in the discussion that follows. Note that the discussion focuses on contaminants in surface soil because ATSDR considers surface soil to be representative of exposure levels and because subsurface soil is generally not accessible to the public.

Site 3: Ball Road Landfill and Burn Pits (PCBs)

Site 3 consists of the Ball Road Landfill and Burn Pits, covering more than 7.5 acres of land in the western portion of the site. Early on, this area served as a quarry for borrow material used in the construction of NSA. Two pits--known as Pit 1 and Pit 2--situated in the quarry were used for the disposal of solvents, lubricants, coating materials, and medical supplies. Material disposed of at this area was reportedly doused with gasoline and burned on a weekly basis (EA 1997, 1999b).

The Navy collected soil and fill samples from the pits and analyzed the samples for VOCs, SVOCs, pesticides, PCBs, and metals. PCBs were the principal contaminant of concern. Most samples collected from the pit contained PCBs at concentrations above ATSDR's CV of 0.4 ppm, and one in four samples collected contained PCBs at concentrations above 50 ppm. One in five samples from outside the pit area also exceeded 50 ppm. (PCBs detected in concentrations greater than 50 ppm must be disposed of in a Toxic Substances Control Act facility). Metals and SVOCs were also detected in surface soil at Site 3,of which antimony (up to 45 ppm), arsenic (up to 35.7 ppm), lead (17,800 ppb), and benzo(a)pyrene (0.420 ppm) exceeded their respective comparison values.

Since identifying elevated levels of contaminants at Site 3, the Navy has undertaken measures to reduce contamination and access to the site. Specifically, action completed in 1994 resulted in excavation of Burn Pit 1, partial excavation of Burn Pit 2, installation of perimeter fencing, and pavement of certain sections of the site. A removal action in 1998 completed excavation of Burn Pit 2, disposed of contaminated soil off site, and finished paving both pits (Navy 2001). Because of the risk posed by residual levels of soil contaminants in samples collected in the area, but away from the burn pits, the Site 3 ROD (signed in September 2000) implemented a residential land-use restriction.

Site 11: Ingot Storage Area

The General Services Administration maintains stockpiles of lead and zinc ingots at Site 11. Lead is stored at four different locations and zinc is stored at the largest of the storage areas, a location extending westward from Q Street. A fence is in place around the storage areas to restrict public access (EA 1999b).

Storage of ingots in these areas has resulted in lead being elevated in the surface soil in the "footprint" of the piles. Surface soil lead concentrations up to 20,400 ppm have been reported (EA 1999b). There appears to be little opportunity for migration, however, as monitoring indicates that concentrations decrease substantially within a few feet of the pile. Lead concentrations also decrease with depth, as background concentrations are reached at about 2 feet below the ground surface (EPA 1995). Cadmium was also detected at a maximum concentration of 18.3 ppm, which exceeds the ATSDR CV for a child of 10 ppm (EA 1999b). (Zinc was detected, but infrequently and at levels below comparison values.)

Interim remedial actions consisting of installation of gravel blankets and curbing to control soil erosion were completed in 1997. The Defense National Stockpile Center is working to relocate the ingots to an indoor storage facility. Final cleanup of the contaminated soil will be accomplished once the ingots are relocated. The Navy plans on closing the area in 2003 (NSA 2001).

Site 14: Water Towers O-C, 16-A, and 504-A

The main source of surface soil contamination at Site 14 is lead paint that was used on the exterior surfaces of the water towers. The towers supplied the installation's distribution system with water since the 1940s until they were dismantled in the summer of 2000. Each water tower sat about 165 feet above its foundation and held up to 250,000 gallons of water. At the time of construction, the exteriors of the towers were painted with lead-based paint. During repainting procedures, the towers' surfaces were sandblasted to remove the lead-based paint and expose the bare metal (EA 1999b).

The Navy collected samples in 1997 that revealed elevated levels of metals in surface soil around the water towers. Contaminants found at levels above comparison include metals (arsenic, lead, and chromium) and Aroclor 1260. Lead, however, was found frequently and in the highest concentrations, generally in close proximity to the base of each tower (EA 2000c). (4) The following describes the locations and concentrations of lead detected at Site 14.

Water Tower O-C: The area around water tower O-C is flat and covered with grass, but the areas to the southeast and west are paved. Lead surface soil concentrations collected in 1997 reached a maximum concentration of 2,750 parts per million ( ppm). Levels above EPA's soil screening level (SSL) of 400 ppm (cleanup levels for residential soil) extended to an approximate 80-foot radius around the central distribution line of the tower and to a depth of 1 foot below ground surface. Also, arsenic (30.8 ppm) exceeded its ATSDR comparison values (CV) for a child of 20 ppm (EA 1999a). During the April 2000 waste characterizations sampling at water tower O-C, the PCB Aroclor 1260 was found in two soil samples collected from beneath the tower. The concentrations of 190 ppm and 210 ppm exceed ATSDR's CV of 10 ppm for Aroclor 1254. ATSDR does not have a comparison value for Aroclor 1260, so the maximum detected concentrations were screened against the most conservative Aroclor compound CV, which is Aroclor 1254.

Water Tower 16-A: Water tower 16-A is bounded to the north by Fox Road and to the south by a parking lot. The area around the tower is flat and covered with grass and shrubs, but the area to the south and east is covered with pavement. Lead surface soil samples were detected at concentrations up to 5,030 ppm in 1997 sampling. Surface soil concentrations greater than EPA's of 400 ppm extended to a maximum of 15 feet to the west of the tower, and up to 1 foot below ground surface on the east side (EA 1999a, 1999b). Arsenic, antimony, and manganese were also detected, but at levels below their ATSDR's comparison values for a child (EA 1999a).

Water Tower 504-A: The area around this tower is flat and covered with grass, but the area to the north, south, and east is covered with pavement. Soil around tower 504-A was not sampled in 1992. During 1997 sampling efforts, however, lead in surface soil samples reached levels up to 2,930 ppm. Levels above EPA's SSL of 400 ppm extended up to an approximate 50-foot radius around the central distribution line of the tower southwest from the site up to 90 feet toward the east, in the direction of prevailing winds. Elevated concentrations extended to at least 1 foot below ground surface. Also, the estimated concentration of arsenic (101 ppm) in surface soil samples exceeded ATSDR's CV for a child (EA 1999a).

Since detecting elevated contaminant concentrations in surface soil at Site 14, the Navy has taken measures to reduce the level of contamination and possible human exposure. In the summer of 2000, the Navy dismantled each of the water towers and excavated the contaminated soil. The excavation area was delineated by the 400 ppm of lead contour lines around each tower. As noted, 400 ppm is considered an acceptable level by EPA for lead in soil in a residential setting. Excavated material was shipped to an off-site disposal area. Following the excavation of soil within the delineated area, additional sampling confirmed that lead and arsenic concentrations were below the cleanup criteria of 400 ppm and 17.2 ppm, respectively. [Note that while the arsenic cleanup criteria exceeds ATSDR most conservative comparison value for arsenic of 0.5 ppm, it is based on the 95% upper bound confidence limit of the mean for background arsenic at NSA.] Confirmatory sampling results also indicate that the PCBs have been removed to levels below 5 ppm. In addition, the Navy removed or capped structures associated with the former water towers, including pipes and valves. Excavated areas have been backfilled with certified clean fill and covered with top soil and seed or sod (Foster Wheeler 2001).

Evaluation of Potential Public Health Hazards

Past Exposure

Table 2 provides a summary of potential public health hazards associated with soil contamination at each NSA site. Most sites are not associated with any known public health hazard. Contaminated surface soils at NSA were generally inaccessible to the public because a perimeter fence with gated entrances limited unauthorized access to NSA. Exposure to contaminated soil for extended periods is not expected to occur to workers in their routine responsibilities, or to residents and visitors during their infrequent access to an operational area, IRP site, or AOC. Many NSA IRP sites are surrounded by perimeter fencing and/or covered surfaces (e.g., vegetative growth, paved areas), both of which prevent or reduce potential exposure to contaminated soil. At other locations, harmful exposures were limited because either no site-related contaminants were present where exposure to the public could occur, or contaminant concentrations detected are too low to pose a health hazard. For some locations where levels were high enough to be a concern to regulators, cleanup efforts have successfully removed contaminated soil.

If workers or trespassers contacted contaminated soil, exposure would have been intermittent and brief. Moreover, workers entering these areas must wear protective clothing, which would have further reduced exposure and any associated health effects. Such minimal, infrequent exposure to on-site contaminants, if it had occurred at all, would not be expected to result in adverse health impacts.

For Site 14, lead and arsenic concentrations in surface soil reached levels greater than health-based screening values. PCBs were also detected, but much less frequently than either lead or arsenic. Access to the towers and the surrounding grounds was unrestricted, so visitors could have come in contact with contaminated soil. It should be noted, however, that screening values are derived assuming daily contact with contaminants in soil. Contact with soil at Site 14 was expected to occur less often than assumed by the comparison values. Still, as a conservative measure, ATSDR evaluated potential health hazards associated with past exposure to soil at Site 14.

To evaluate whether past public health hazards may be associated with surface soil contamination at Site 14, ATSDR considered who may be exposed, how often and how long this exposure may occur, and what contaminant concentrations are present in the soil. Since public contact around the towers was not deterred or restricted, residents could have accessed the soil, and dermal contact with and incidental ingestion of contaminant concentrations above their CVs could have occurred. Residents might have come in contact with contaminants when handling soil or by inadvertently eating soil through hand-to-mouth activity. Inhalation of soil particles is not considered to be a significant source of exposure because all land on IRP sites is either extensively vegetated, paved, or enclosed. ATSDR assumed that any soil contact would be with surface layers, since individuals would be unlikely to dig in soil around the towers. Using these assumptions, ATSDR derived doses for exposure to lead and arsenic in surface soil near the towers. Lead and arsenic were the most commonly detected contaminants and would therefore drive any associated health hazards brought about by contact with contaminated soil. Appendix C describes the methodology used to evaluate exposure to lead and arsenic in soil.

Based on ATSDR's estimated exposure doses using hypothetical exposure scenarios and the maximum detected concentrations, past blood lead levels for children living at NSA may have been elevated above the Centers for Disease Control's (CDC's) recommended action level of 10 microgram per deciliter (µg/dL) in blood. Therefore, visitors who were expected to come in contact with or inadvertently ingest lead in soil may have an increased likelihood of having an elevated blood lead level and of developing adverse effects, if exposed to the highest levels of these contaminants over time. However, the exposure doses overestimate the actual exposure incurred by visitors to the towers in the past. For example, it is not expected that a child would come in contact with the most contaminated soil during infrequent visits to the site. When ATSDR assessed exposure based on a more representative concentration of lead (geometric mean) in soil at the towers, the blood lead level was below CDC's recommended action level of 10 µg/dL. In all likelihood, any exposure would be infrequent and of short duration, because security measures would limit the time individuals spend around the towers. Furthermore, grass covering around the towers would further reduce potential contact with contaminated soil. Such minimal, infrequent exposure to on-site contaminants, if it occurs at all, would not be expected to result in adverse health impacts.

Current and Future Exposures

Current and future accessibility of certain IRP sites will remain restricted. Note that certain sites have been or are being remediated by the Navy as a precautionary measure to prevent exposure to on-site workers and to prevent contamination from leaching into groundwater. Among their completed efforts, the Navy dismantled the water towers and removed contaminated soil from Site 14 in 2000. (See Table 2 for the status of each IRP site and AOC.) These remedial actions are conducted with oversight by EPA and PADEP to ensure protection of human health and the environment. In evaluating available monitoring data and proposed remedial actions, ATSDR has identified no current or future public health hazards associated with contaminated soil. ATSDR concludes that contaminants in surface soil pose no apparent public health hazard.

Evaluation of Surface Water and Sediment Exposure Pathway

After reviewing the available surface water and sediment monitoring data and exposure information, ATSDR has drawn the following conclusions:

  • High levels of lead and PCBs have been measured in surface water and sediment samples collected from the stormwater drainage ditch (SWDD) that conveys runoff from almost all paved areas of NSA, which encompasses the majority of IRP sites. Contaminants have traveled via the SWDD to Trindle Spring Run.

  • Exposure to contaminants in the SWDD or in the Trindle Spring Run is minimal, limited to infrequent dermal contact, and not of health concern.


Description of Surface Water Flow at NSA

The Naval Support Activity (NSA) is located in the Conodoquinet Creek and Breeches Creek watersheds, but no natural water bodies exist at the installation. Surface runoff from the paved warehouse area collects in on-site catch basins and flows through storm sewers into a 1.5 mile long stormwater drainage ditch (SWDD) at the western boundary of NSA, near the Hampden Township sewage piping station (see Figure 4). Surface water from the family housing areas in the northwestern section of the installation flows into a separate system from the warehouse areas, which then also discharges into the SWDD. During periods of heavy rainfall, the SWDD discharges into the Trindle Spring Run, a Pennsylvania, high quality, spring-fed, cold-water fishery, which flows northerly along the western boundary before emptying into the Conodoguinet Creek. Although the drainage ditch was constructed originally to receive stormwater from NSA, it appears that the ditch now receives discharges from private, commercial, and industrial properties along its length (EA 1999b, 2000b). The following discussion describes the SWDD and Trindle Spring Run in greater detail and summarizes available sampling data.

Stormwater Drainage Ditch (SWDD)

Stormwater runoff collected from paved areas at NSA has been directed into the 1.5 mile SWDD at the western boundary of the site. Paved areas at NSA encompass a majority of the IRP sites. More recently, the SWDD has also served as a public conveyance, drawing runoff from private, commercial, and industrial properties along its length. Much of the SWDD (about two-thirds of its length) is fenced and overgrown with vegetation (EA 2000b). Gabion dams constructed along certain portions of the ditch help to limit downstream migration of ditch sediment. In 1988, PADEP collected samples that showed widespread PCB contamination in sediment from the ditch. The Navy continued investigations of contamination in the ditch in 1988 and 1989, collecting more than 500 sediment samples overall and analyzing them for metals, PAHs, and PCBs.

Table 6 presents the results of the sediment sampling of the SWDD. The results confirmed the presence of metals, SVOCs, PCBs in the ditch sediment at levels above the soil CVs. The Navy also collected surface water samples from SWDD in 1988 and 1989. The results indicated no measurable quantities of PCBs or PAHs. Metals, such as cadmium, lead, and zinc, were detected but only lead exceeded its screening value (EA 1999b).

The SWDD was subdivided for further study into three segments based on different physical characteristics and decreasing levels of contamination. (5) The segments and PCB monitoring data are described below and in Tables 7.

Segment 1 (0 - 1,800 feet): This portion of the ditch is fenced and extends from the headwall at NSA to the First Avenue Outfall. It is bordered by the township recreation fields, and is residential only at the upstream end. Much of the vegetation in the early portion of this segment has been removed as a result of prior removal actions. A gabion dam at the end of this segment inhibits downward sediment migration. Further downstream from the first gabion dam, trees and other vegetation are growing in the ditch and along the bank. PCBs concentrations greater than 100 ppm have been detected in this segment (EA 1999b).

Segment 2 (1,800 - 4,000 feet): Segment 2 extends from below the First Avenue Outfall to a second gabion dam. This segment of the ditch becomes increasingly vegetative along its length and is fenced. Residential housing, a small forested area, and a series of trucking companies occupy the southern bank of the ditch. Other non-NSA culverts convey runoff into the ditch. PCBs in this segment reached concentrations up to 70 ppm.

Segment 3 (4,000 - 7,859 feet): This portion of the ditch extends from the second gabion dam to the confluence with Trindle Spring Run. Residences appear scattered along the border of this heavily vegetated segment. In 1991, fencing was added up to Salem Church Road, about half way down. PCB concentrations were generally less than 35 ppm in this section of this ditch (EA 1999b).

Starting in the early 1990s, the Navy began a series of actions intended to manage the PCB- contaminated ditch sediment. Through these actions, they removed more than 7,000 tons of contaminated sediment; extended existing fencing to Salem Church Road (in Segment 3); and installed another gabion dam in Segment 3 to limit downstream migration of sediment toward Salem Church Road. (EA 1999b). Following these measures, the Navy conducted additional sediment sampling as part of an ecological risk assessment (EA 2000b). PCBs were still present, but at lower levels (total PCBs, 0.08 to 21 ppm; Aroclor 1260, 0.085 to 41 ppm). (6) At that time, the highest levels were measured within the mid-section (Segment 2) of the SWDD, a fenced section that reportedly receives runoff/discharges from other commercial/industrial sources (EA 2000b).

Trindle Spring Run

Trindle Spring Run is the closest natural surface water to the NSA property. Local anglers may use the run for limited fishing, but the water is not used as a drinking water source or commonly used for swimming. While swimming in the creek is not prohibited, low flow and overgrowth makes it undesirable.

Recent surveys of the sediments in the stream revealed elevated concentrations of PCBs. Most creek contamination today appears to primarily result from stormwater runoff (SWDD) discharges or from other upstream off-site non-point sources. The extent to which SWDD sediment currently contributes to the Trindle Spring Run pollutant load is decreasing. It is doubtful that contamination in the stream results from current Navy activities. Additionally, over many years, Trindle Spring Run has experienced problems from erosion, sedimentation, and the delivery of excess nutrients.

During the Navy's 1999 ecological risk assessment, two sediment samples were collected from the Trindle Spring Run downstream of its confluence with SWDD and one sediment sample was collected upstream. All samples were analyzed for metals, PCB congeners, PCB Aroclors, and PAHs. The results of the sampling are presented in Table 8. As noted in Table 8, the concentrations of total PCBs ranged from 0.07 ppm to 0.104 ppm and Aroclor 1260 ranged from 0.025 to 0.100 ppm and appear to be increasing downstream. Total PCB and Aroclor 1260 levels were slightly below the Aroclor 1254 CV of 1 ppm for a child (and 10 ppm for an adult). (A reference sample taken from Cedar Run had 0.002 ppm PCBs.) (EA 2000). The Navy also collected surface water samples during their 1989 remedial investigation monitoring activities. Only metals, SVOCs, and PCBs were found at levels below CVs in surface water samples collected both from upstream and downstream of Trindle Spring Run's confluence with the SWDD (EA 1999b).

Evaluation of Potential Public Health Hazards

PCBs have been detected in sediment of the SWDD and Trindle Spring Run at levels above ATSDR's comparison values for PCBs in soil. However, people are not expected to come in contact with harmful levels of contaminants. This is because there are no indications that people use or will use the SWDD or Trindle Spring Run in ways that would result in appreciable skin contact with contaminated sediment. Fencing or thick vegetation bordering the SWDD limit the public's access to the ditch. Use of Trindle Spring Run is limited to fishing rather than swimming or wading. Any skin contact with PCBs in sediment and surface water is therefore expected to be limited in frequency and duration. Furthermore, NSA has and continues to take measures to prevent contaminants from NSA IRP sites and existing contamination in the SWDD from reaching Trindle Spring Run. The Agency for Toxic Substance and Disease Registry (ATSDR) concludes that incidental exposure to contaminants in sediment and surface water is not expected to pose a public health hazard.

Evaluation of Fish Consumption Pathway

After reviewing the available fish monitoring data and exposure information, ATSDR has drawn the following conclusions:

  • PCBs have accumulated in rainbow trout inhabiting Trindle Spring Run.

  • People who eat fish regularly can be particularly susceptible to the effects of PCBs that build up over time.

  • The Pennsylvania Department of Environmental has issued a fish consumption advisory urging people to limit consumption of rainbow trout caught from the Trindle Spring Run to one meal a month. By following this advisory, people will protect themselves against the harmful effects of PCBs.


Trindle Spring Run is a cold-water and popular recreational fishing spot for NSA-area anglers (PADEP 1998, PAFBC 1996). Of the fish inhabiting the river, rainbow trout is the most commonly sought-after species. As noted in the Evaluation of Surface Water and Sediment Pathway discussion, Trindle Spring Run water quality and the sediment have been impacted by pollutants conveyed by SWDD or from other upstream sources. Studies conducted at NSA have shown that PCBs (Aroclor 1260) are the primary contaminant of concern. The SWDD receives runoff from NSA and conveys it to Trindle Spring Run. Today, the SWDD also receives runoff from additional private, commercial, and industrial properties (EA 2000b).

Contaminants, such as PCBs, settle to the bottom of a stream and collect in sediment. PCBs do not decompose easily, so they remain in the environment for many years after release. Even though the levels of PCBs in surface water or sediment of the Trindle Spring Run are relatively low or have been greatly reduced, the contaminants can accumulate in fish tissue. Fish take in PCBs when they eat smaller fish or sediment containing PCBs. In this way, larger and older fish can build up high levels of contaminants (EPA 1994).

Textbox: Trindle Spring Run Fish Consumption Advisory: People taking fish from Trindle Spring Run, Cumberland County, are advised to eat only one meal per month of rainbow trout. One meal is considered to be one-half pound of rainbow trout (before cooking) for a 150-pound person. Anglers should properly clean, skin, and trim fish before cooking. Any juices and fats that cook out of the fish should not be eaten or reused. For more information contact:
The Pennsylvania Department of Environmental Protection at 
(717) 787-9637.In 1998, the PADEP issued a fish consumption advisory, urging people to limit their consumption of rainbow trout caught in the waters of the Trindle Spring Run in Cumberland County (see Text Box). This advisory was primarily based on elevated levels of PCBs in rainbow trout (see Fish Tissue Data section below). The PADEP advised community members on the amount of rainbow trout that they could safely eat without developing adverse health effects from PCBs. In particular, the advisory encouraged women of childbearing age, nursing mothers, and young children to limit the amount of rainbow trout that they eat (PADEP 1998, PADEP 2001). While it is believed that the vast majority of people heed the advise issued in the advisory by practicing catch and release fishing, some anglers may still cook and eat their catches.

Fish Tissue Data

The Pennsylvania Department of Environmental Protection (PADEP) has sampled to assess whether and to what extent contaminants have been taken up by Trindle Spring Run fish. Field work done in 1988 and in 1996 indicated that Trindle Spring Run rainbow trout had accumulated PCBs at levels up to 0.98 ppm and 0.76 ppm, respectively (see Table 9). These levels are below the tolerance level set by the U.S. Food and Drug Administration (FDA) to protect consumers of commercial fish. FDA's tolerance level for PCBs, used by ATSDR as a screening value, and referenced in the following discussion, is 2.0 ppm (wet weight). (7)

In October 1999, the Navy collected additional fish samples from Trindle Spring Run to further assess the impact of PCBs on the local fish community. Using electrofishing techniques, the Navy collected a combined total of over 1,300 fish specimens representing two different species: rainbow trout (27 samples), a top level predatory species, and slimy sculpin (1,357 samples), a bottom dwelling species. The higher fat content bottom dwelling species tend to accumulate higher levels of PCBs than do the top level predatory species found in the same waters. The samples came from three sampling locations along the stream: a location upstream of SWDD's confluence with Trindle Spring Run (TR-1); a location immediately downstream of the confluence (TR-2); and a location further downstream (TR-3). Control samples were also taken from Cedar Run (EA 2000b).

Fish samples were segregated by size and designated as either whole body or fillet samples. Depending upon the size of the fish, some of the samples were taken from a single fish. Note that for the purposes of this public health assessment, ATSDR was most interested in assessing data for fish types most relevant to local population's eating habits. Since ATSDR is not aware of any groups of people visiting Trindle Spring Run whose diet consistently rely on other portions of fish (i.e., bones, fat, viscera), ATSDR evaluated fish "fillet" data, as representing the "edible" portion of fish. For its analysis, the Navy combined fish fillet samples of like species into eight rainbow trout (juvenile) and nine sculpin fillet composite samples. The Navy tested each of the composite samples for the presence of metals, PAHs, and PCB congeners.

Results appear to confirm previous findings, mainly that PCBs are the primary contaminants of concern and are consistently detected in fish from Trindle Spring Run Mean total PCB fish tissue concentrations for rainbow trout (0.6-1.2 ppm) and slimy sculpin (0.2-1.1 ppm) were below the FDA action level for commercial fish of 2.0 ppm. (8) A slightly higher concentration of total PCBs (1.2 ppm) was reported in a composite of rainbow trout collected from the upstream portion of the stream than had been reported for downstream samples (0.633 ppm). This finding suggests that other sources may exist upstream of the point where the SWDD discharges into the stream. Because fish migrate, there is, however, no way to determine how much PCB contamination in Trindle Spring Run fish actually originated from NSA operations.

The screening data provide some general information and suggest PCB levels in fish were below FDA tolerance levels. Screening data, however, often lack sufficient detail for determining whether or how much fish can safely be eaten. For example, composite analysis used in this screening approach lacks information on levels of contaminants in individual fish. Without this information, we do not know the highest level of PCBs in larger, more desirable fish to which an individual could be exposed. This is important because larger fish of any one species would be expected to have accumulated more of the contamination. Furthermore, the composite samples used in the screening approach were made up of juvenile samples. Generally, younger fish have accumulated less contaminants than older fish younger of the like species. (9)

Evaluation of Potential Public Health Hazards

PCB concentrations in fish samples collected from Trindle Spring Run were below FDA action or tolerance levels. Although used as a screening level value, the FDA actions levels are not considered to be very conservative by ATSDR for several reasons: (1) the FDA action levels apply only to fish sold in interstate commerce, so that fish from a specific area would not be eaten regularly or frequently by consumers, (2) the FDA action levels factor in economic considerations and are not necessarily as conservative as health-based action levels, and (3) fish consumption rates for sport anglers could be higher than those assumed for the consumption of commercially bought fish, particularly for fish from a specific area.

ATSDR conservatively estimated exposure doses for individuals who eat rainbow trout from Trindle Spring Run contaminated with PCBs. Appendix C describes the method and conservative assumptions ATSDR used to estimate PCB exposure doses and potential health effects. Estimated exposures to PCBs from eating more than one 8-ounce fish meal a month was greater than levels considered safe for the general population. It is possible that people who ate fish in sufficient quantities in the past could have been at risk of developing health effects. Without specific information about how much fish a person ate and over what length of time or what the actual levels were in any fish eaten, ATSDR cannot draw firm conclusions about past exposure. Therefore, past exposure remains an indeterminate public health hazard. Based on current, available information, ATSDR concludes that rainbow trout consumed in the past from Trindle Spring Run in sufficient amounts could pose a public health hazard. The fish consumption advisory for Trindle Spring Run should continue to be observed to reduce potentially harmful effects, now and in the future.


NSA has a community relations plan (CRP) that provides guidance for involving the community and other interested parties in the remediation decision-making process and for distributing information to these parties (EA 1999d). As part of its community relations activities, NSA has formed a restoration advisory board (RAB). The RAB, which is represented largely by local community members, meets periodically to review site documents and comment on actions and proposed actions taken by NSA. Through the public health assessment (PHA) process, ATSDR has gathered information about health concerns identified in the CRP or voiced by community members at RAB meetings. The following is a summary of the community health concerns that have come to ATSDR's attention.

Concern: Could harmful levels of lead associated with paint scrapings from the water tower have migrated off site ?

No. Three base water towers constructed in 1943 were maintained with lead-based paint. During repainting procedures, the exteriors of the towers were sandblasted to remove the paint layers. Some of the paint scrapings fell onto the ground around the towers. It is possible that some of the scrapings became airborne and traveled from the towers during sandblasting activities or enters the SWDD with stormwater runoff over the nearby pavement. Soil sampling done in 1999 confirmed that lead was present in the surface soil around the tanks. The sampling also showed, however, that the scrapings were relatively confined within 80 feet of any one tank, and could not have reached residential housing areas. The Navy dismantled the water towers and removed the lead-contaminated soil from the site in September 2000 and subsequently backfilled and seeded the area.

Concern: Are there any potential health threats posed by the contaminated groundwater?

No. Chemical spills and releases associated with former waste disposal practices have contaminated the groundwater beneath Naval Support Activity (NSA). Through the public health assessment process, it is ATSDR's goal to first find out if people are being exposed to contamination released from a site and, if so, whether this exposure may lead to adverse health effects. At NSA, ATSDR reviewed information about base contamination and determined that people on and surrounding NSA have not been exposed to volatile organic compounds (VOCs) from NSA when they drink their water. Contaminated groundwater has not migrated to a municipal well that serves United Water Pennsylvania, one of the area water suppliers or to nearby private wells. Furthermore, both municipal suppliers PAWC and United Water Pennsylvania have installed water treatment systems and monitor raw water regularly to ensure continued protection of public health. Regular monitoring of the groundwater well includes analyzing samples for VOCs.

Concern: Could children have come in contact with harmful levels of PCBs in the ditch or creek?

No. As our evaluation has indicated, elevated levels of PCBs have been detected in the sediment of the stormwater drainage ditch and Trindle Spring Run. Still, we do not expect that young children came in contact with the PCB-contaminated sediment frequently or for long periods of time. Much of the ditch has been covered with water and dense vegetation or protected by fences, all of which would hinder direct contact with and incidental ingestion of sediment. There is also little chance that young children (0-2 years of age), the most susceptible to the effects of PCBs, are apt to be frequently left unsupervised for long periods of time near the ditch.

In early 1989, the Navy helped allay concerns about exposure of young children to PCB-contaminated sediment by installing a 6-foot high chain link fence around the more highly contaminated portion of the ditch. The Navy has also extended the fencing and removed the contaminated sediment from the ditch in the 1990s.

Concern: What measures are being taken to reduce the risk from exposure to contamination at the former burn pits within Site 3?

The Navy has conducted numerous investigations to characterize both the type and amount of contaminated soil at Site 3. Results of these investigation indicated that there was a sizeable amount of soil contamination related to the site's former use as a waste disposal area. In response to these findings, the Navy has undertaken measures to reduce contamination and access to the site. Specifically, action completed in 1994 resulted in excavation of Burn Pit 1, partial excavation of Burn Pit 2, installation of perimeter fencing, and pavement of certain sections of the site. A removal action in 1998 completed excavation of Burn Pit 2, disposed of contaminated soil off site, and finished paving both pits (Navy 2001). These measures have greatly reduced the likelihood for people to come in contact with contaminated soil at the former burn pit now or in the future. Still, however, residual levels of soil contaminants in samples collected away from the burn pits exceeded levels considered safe for residential uses. To ensure safety for future users of the area, the Navy, Environmental Protection Agency (EPA), and Pennsylvania Department of Environmental Protection (PADEP) agreed to land-use controls at Site 3 which would prohibit residential development. As part of the agreement, the Navy will furnish the EPA and PADEP with annual certification confirming appropriate use of the site (Navy 2001).


ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. In general, children are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, so they receive higher doses of chemical exposure proportional to their body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care.

Following a careful evaluation of these pathways as they relate to children, ATSDR determined that no harmful exposures have occurred in the past, nor are they expected to occur either now or in the future. Although contaminants have been detected at Naval Support Activity, children do not visit the installation restoration program sites or the area of concern. ATSDR determined that harmful exposures are not expected to occur, because children cannot access the site or locations of contamination at NSA and no harmful exposures associated with the site are specific to children in the vicinity of the site. Potential exposure pathways are discussed in the Evaluation of Contamination and Potential Exposure Pathways section of this PHA.


Based on a thorough evaluation of available environmental information, ATSDR has made the following conclusions:

  1. Contaminants from former Navy activities have leached into the groundwater beneath Naval Support Activities (NSA), Mechanicsburg. No exposure to these contaminants has occurred, however, because groundwater underlying NSA has never been used as a source of drinking water or as a source of other potable uses. Currently, the municipal water suppliers (Pennsylvania-American Water Company and United Water Pennsylvania) that provide water to NSA and the Borough of Mechanicsburg routinely test their water to ensure that it complies with state and federal drinking water standards. NSA contaminants have not migrated beyond NSA site boundaries to areas where private wells draw water.

  3. Surface soil at certain locations at NSA was found to contain contaminants associated with former installation activities. Even though certain areas have elevated lead and arsenic concentrations, no harmful exposures have occurred nor should they occur in the future. Most often, exposure has been prevented because soil contamination occurs in restricted access areas or is covered by pavement or grass. Occasional contact with surface soil contaminants, even at the highest levels reported, is not expected to pose a health concern for adults or children. Successful cleanup or removal of contamination will continue to reduce potential future exposures.

  4. Contaminants, primarily PCBs, have been detected in surface water and sediment of the stormwater drainage ditch (SWDD) leading from NSA. The SWDD also receives discharges from other non-NSA private sources bordering the ditch. No harmful exposures to contaminants in ditch sediment are expected because a fence and vegetation limit direct contact with ditch sediment. Any infrequent handling of the sediment associated with trespasser exposure is not expected to pose a health concern. Some contaminants have reached Trindle Spring Run via the SWDD. Exposure to sediment in the stream is minimal, limited to infrequent dermal contact while fishing, and not expected to pose a health hazard. Contaminant levels are not expected to accumulate downstream, namely in the Conodoquinet Creek.

  5. Reported concentrations of PCBs in certain locally-caught fish could pose a public health hazard. The Pennsylvania Department of Environmental Protection issued a fish consumption advisory encouraging people to limit their consumption of Trindle Spring Run rainbow trout to one 8-ounce meal a month. People can best protect themselves from the potentially harmful effects of PCBs by adhering to the advisory.


The public health action plan (PHAP) for NSA, Mechanicsburg contains a description of actions taken and those to be taken by ATSDR, the Navy, Environmental Protection Agency, and Pennsylvania Department of Environmental Protection at and in the vicinity of the site subsequent to the completion of this public health assessment. The purpose of the PHAP is to ensure that this public health assessment not only identifies potential and on-going public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The public health actions that are completed, ongoing/planned, or recommended are as follows:

Completed Actions

  1. Under the Installation Restoration Program, the Navy has identified and conducted environmental investigations at 16 IRP sites (Sites 1, 2, 3-soil, 3-groundwater, and 4 through 15) suspected of potential hazardous releases.

  2. As a result of its site investigations, the Navy has removed contaminated material from several installation restoration sites. These actions include: removal of contaminated soil/sediment from Sites 3, 9, 14, and 15; removal of tanks and contaminated soil at Sites 6 and 10; and erosion control at Site 11.

  3. The Navy, Pennsylvania Department of Environmental Protection, and Environmental Protection Agency have completed investigations and signed record of decisions (ROD) for Sites 1 and 3. The Site 1 ROD, signed in September 1998, requires the Navy to restrict residential land use of the site and the Site 3 ROD, signed in September 2000, outlines land-use control remedies prohibiting residential development.

  4. The Navy closed Sites 1, 2, 3-soil, 4, 5, 6, 7, 10, 12, 13, 14, and 15 based on the results of monitoring, human health risk assessments, and/or previous removal actions. For some of these sites, formal closure documents are pending even though the Navy, EPA, and PADEP have reached consensus that the sites require no further investigative/cleanup work.

  5. The Navy identified 49 areas of concern (AOCs), small areas of contamination not attributed to installation restoration sites. With Pennsylvania Department of Environmental Protection and Environmental Protection Agency approval, the Navy has been allowed to eliminate 40 AOCs from further work under the Federal Facilities Agreement. Nine AOCs remain open.

  6. The Navy prepared a community response plan (CRP) that provides guidance for community involvement in the remediation process. Subsequent to the CRP, the Navy sponsored community interviews in 1997 to gain a better understanding of community awareness of environmental issues at NSA.

  7. The Pennsylvania Department of Environmental Protection issued a limited fish consumption advisory for Trindle Spring Run in October 1998. The advisory encourages people to limit their consumption of rainbow trout caught from Trindle Spring Run to one meal per month.

  8. The Navy dismantled the three water towers associated with Site 14. So far, most of the 2,500 tons of contaminated soil around the three water towers has been excavated and disposed of off site.

Ongoing and Planned Actions

  1. The Navy will continue monitoring groundwater at Site 3-groundwater and Site 9.

  2. The Navy is awaiting the results of human health and ecological risk assessment for Sites 8 and 9. They are also planning a sediment investigation at Site 9.

  3. The Navy is working to relocate the ingots at Site 11. Cleanup of contaminated soil will commence once the ingots are removed.

  4. For the AOCs that remain open, the Navy is: conducting periodic groundwater monitoring at AOC 1-A; conducting additional investigations at Site 9-A; planning RI field work at AOC 21; awaiting a revised human health risk assessment for AOC 38; and planning groundwater monitoring at AOCs 51 and 52 in year 2002. AOC 16 is an ongoing ecological risk assessment and AOC 17 is a basewide background groundwater study, for which a draft report is prepared and under review.

  5. The municipal water suppliers regularly monitor their water supply to ensure that the water delivered to their customers, including NSA, is free of contamination at levels of health concern. Regular monitoring includes collecting samples from groundwater supply wells and analyzing the samples for volatile organic compounds.

  6. Members of the community and the NSA participate in regularly scheduled Restoration Advisory Board meetings. These meetings serve as a forum for communication of ongoing and planned activities at NSA to the community and for communication of community concerns to NSA personnel.

Recommended Actions

  1. If new information from site investigations identifies contaminants in site media above ATSDR's health-based comparison values, ATSDR will assess contaminant data and exposure situations to identify if any public health hazards exist. ATSDR will also re-evaluate the potential for public health hazards if changes in proposed land use, remedial activities, or risk management actions (e.g., institutional controls) may lead to future exposures.


Jeffrey Kellam
Environmental Engineer
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation

Gary Campbell, Ph.D.
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation


Agency for Toxic Substances and Disease Registry (ATSDR). 1998. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic (Update). August 1998.

Agency for Toxic Substances and Disease Registry (ATSDR) 1999a. Toxicological Profile for Lead (Update). Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services. Research Triangle Institute. July 1999.

ATSDR. 1999b. Toxicological Profile for Polychlorinated Biphenyls (PCBs) (Draft). Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services. Research Triangle Institute. April 1999.

Department of Navy (Navy). 2001. Navy comments on the data validation draft PHA. October 8, 2001.

Department of Navy (Navy). 2002. Navy comments on the public comment release draft PHA. April 2002.

EA Engineering, Science, and Technology (EA). 1992. Final Report. 1991-1992 Dye tracer investigations, Burn Pit Area. Volume 1 Text. Naval Ship Part Control Center, Mechanicsburg, Pennsylvania. October 13, 1992.

EA. 1997. Results of biocell and soil sampling at IR Program Site 3. Naval Inventory Control Point. Mechanicsburg, Pennsylvania. November 1997.

EA. 1999a. Site Inspection report for Sites 12, 13, 14, and 15 Naval Support Station (NSS). (Formerly Naval Inventory Control Point), Mechanicsburg, Pennsylvania. March 12, 1999.

EA. 1999b. Site management plan. Naval Support Station (NSS). (Formerly Naval Inventory Control Point), Mechanicsburg, Pennsylvania. May 18, 1999.

EA. 1999c. Analysis of historical groundwater data at Naval Support Station (NSS). (Formerly Naval Inventory Control Point), Mechanicsburg, Pennsylvania. June 10, 1999.

EA. 1999d. Final Community Relations Plan for Naval Support Station. June 8, 1999.

EA. 1999e. Results of sites 1, 2, 5, 10, and 11 ground-water investigation. Naval Support Station. Mechanicsburg, Pennsylvania. June 14, 1999.

EA. 2000a. Ground-water sampling work plan for basewide ground-water background at Naval Support Activity (former Naval Inventory Control Point), Mechanicsburg, Pennsylvania. May 2000.

EA. 2000b. Technical memorandum, part II. Ecological Risk Assessment, food web modeling. Naval Support Station (NSS). Vols. 1 and 2. (Formerly Naval Inventory Control Point), Mechanicsburg, Pennsylvania. August 2000.

EA. 2000c. Human health risk assessment memorandum, IR Program site 14: Water towers 16-A, 504-A, and O-C. Naval Support Activity, Mechanicsburg, Pennsylvania. November 10, 2000.

EA. 2001a. Report on May 2000 groundwater sampling at sites 3 and 9. Naval Support Station (NSS). (Formerly Naval Inventory Control Point), Mechanicsburg, Pennsylvania. March 1, 2001.

EA. 2001b. Letter Report from Kevin Sharpe, EA, to Ms. Catherine M. Mulhern, NSA, RE: Soil and Ground-water sampling at Site 1-A: S01M01 groundwater, naval Support Activity, Mechanicsburg, PA. February 12, 2001.

EA. 2001c. Site 9-A: Stormwater sewer system sediment sampling report. Naval Support Activity, Mechanicsburg, PA. April 18, 2001.

EA. 2001d. Report of site inspections for Sites 21, 22, 48, and 51 & 52. Naval Support Activity, Mechanicsburg, PA. May 10, 2001.

EA. 2001e. Calculation of basewide ground-water background for Naval Support Activity, Mechanicsburg, PA. July 17, 2001.

EA. 2001f. Letter Report from Ted Rodeffer, EA, to Jeffrey Henning, NSA, RE: Installation restoration Site 10-A and Site 38, Naval Support Activity, Mechanicsburg, PA. August 2, 2001.

EPA (U.S. Environmental Protection Agency). 1995. Letter from Andrew Sochanski, EPA, to Ed Boyle, Naval Facilities Engineering Command. RE: Comments on the civil design ingot Storage Areas, Navy SPCC, Mechanicsburg, PA. August 22, 1995.

EPA. 2001. EPA Superfund web site. Exiting ATSDR Website.

Foster Wheeler (Foster Wheeler Environmental Corporation). 2001. Contractors closeout report for contaminated soil removal, water towers 16A, 504A, and O-C. Naval Support Activity (NSA), Mechanicsburg, Pennsylvania. February 2001.

Navy see Department of the Navy.

NSA. 2001. Installation Restoration Program Metrics. Naval Support Activity, Mechanicsburg. July 2001.

Naval Inventory Control Point (NAVICP). 2001. NAVICP Web Site. Exiting ATSDR Website May 2001.

PADEP (Pennsylvania Department of Environmental Protection). 1988. 1988 fish tissue sampling data from Trindle Spring Run. October 5, 1988.

PADEP. 1996. 1996 fish tissue sampling data from Trindle Spring Run. August 13, 1996.

PADEP. 1998. Pennsylvania Department of Environmental Protection Fish Consumption Advisories. October 28, 1998.

PADEP. 2001. Web Site. Exiting ATSDR Website. July 2001.

PADER. 1990. Letter from Francis P. Fair, Regional Environmental Protection Manager, Pennsylvania Department of Environmental Resources, to Ms. Adrienne Townsell, Department of Navy. RE: Navy Ships Parts Control Center SWDD Groundwater Dye Tracer Study. October 23, 1990.

PAFBC (Pennsylvania Fish and Boat Commission). 1996. Comments and recommendation on Trindle Spring Run. October 13, 1996.

PAWC (Pennsylvania American Water Company). 2001. Pennsylvania American Water Company Web Site. Exiting ATSDR Website. July 2001.

United Water Pennsylvania. 2001. Consumer Confidence Report. United Water Pennsylvania. 2001.

1. The value for TCE represents a diluted concentration.
2. The value for PCE represents an estimated concentration.
3. Unfiltered samples are used for valid comparison between analyses of metals from groundwater samples and EPA and ATSDR drinking water standards. The standards and health studies are based on total metals found in unfiltered samples.
4. Monitoring conducted in 1992 at O-C and 16-A reported concentrations up to 12,400 ppm and 13,700 ppm, respectively. ATSDR does not have the information to assess whether these samples were analyzed in the field or in the laboratory.
5. As noted, ATSDR does not have a comparison value for total PCBs in sediment, so the maximum detected concentration was screened against the most conservative Aroclor compound comparison value for soil, which is Aroclor 1254.
6. PCBs are a group of 209 congeners that show wide differences in their biological effects. The analytical method used for "total" PCBs in sediment actually summed the concentrations of 28 select congeners. As such, the "total" PCB concentration does not truly represent the total of all 209 congeners, rather it is the total concentration of the 28 select congeners. Therefore, the "total" PCB concentration in sediment presented in this PHA may be less than the Aroclor 1260 concentration.
7. The FDA tolerance level was established for seafood sold through interstate commerce. It was developed to protect humans from harmful substances in commercial foods. Although the FDA level was not developed as a regulatory standard for freshwater fish, it is often used by states as guidance when setting freshwater fish consumption advisories.
8. Total PCBs were defined as the summations of detected PCB congeners multiplied by 2. ATSDR used this value when assessing public heath hazards and when comparing detected levels to the CV for the PCB Aroclor 1254.
9. Slimy sculpins were the only bottom feeding fish available in adequate quantity to provide a sufficient mass for sample analysis. Although the sculpin data provide some indication as to whether bottom feeders are accumulating contaminants, slimy sculpins are so small that they are probably not consumed by people who fish the creek. Because of the apparent lack of other bottom feeders in the stream, we would not expect the public to consume these types of fish often, if at all.

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