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PUBLIC HEALTH ASSESSMENT

NEW BRIGHTON/ARDEN HILLS
(a/k/a U.S. ARMY TWIN CITIES AMMUNITION PLANT)
NEW BRIGHTON, RAMSEY COUNTY, MINNESOTA


SUMMARY

The New Brighton/Arden Hills National Priorities List (NPL) Site is a 25-square-mile area in Ramsey County, Minnesota, just north of the Minneapolis/St. Paul metropolitan area. The site includes the 4-square-mile Twin Cities Army Ammunition Plant (TCAAP) and portions of seven nearby communities: New Brighton, St. Anthony, Arden Hills, Shoreview, Mounds View, Columbia Heights, and Minneapolis. As presently defined, the site covers much of the U.S. Geological Survey's New Brighton, Minnesota, 7.5-minute quadrangle map.

In June 1981, the Minnesota Pollution Control Agency (MPCA) and the Minnesota Department of Health (MDH) discovered trichloroethylene (TCE) and other volatile organic compounds (VOCs) in municipal, mobile home park, and private well water in the vicinity of TCAAP. Initial analysis of TCAAP water supply wells revealed high concentrations of TCE (720 parts per billion [ppb), 1,1,1-trichloroethane (360 ppb), 1,1-dichloroethane (130 ppb), and other VOCs.

Scientists with MPCA and MDH worked with all involved parties to identify contaminated wells and, when possible, to reduce the concentrations of contaminants below state and federal drinking water standards or to provide alternative water supplies. However, some people using private wells and mobile home park wells may have continued to use contaminated well water for 2 to 3 years before their homes were connected to alternative water supplies.

In May 1987, 15 families petitioned the Agency for Toxic Substances and Disease Registry (ATSDR) to conduct a public health assessment of TCAAP for populations exposed to hazardous substances from TCAAP. ATSDR agreed to conduct the public health assessment in conjunction with the public health assessment of the New Brighton/Arden Hills NPL site. Therefore, this public health assessment addresses the contaminants and the health concerns of people affected by contaminants from TCAAP. Some of the health concerns expressed by people living near TCAAP include past exposures to contaminated drinking water and the possibility of adverse health effects, such as birth defects and leukemia.

From its review of available data, ATSDR concludes that hazardous waste sites within TCAAP are public health hazards because people were exposed in the past to groundwater contaminants at concentrations that may cause adverse health effects. People were exposed to solvents via ingestion, inhalation, and skin contact when contaminants from TCAAP migrated into private, mobile home park, commercial, industrial, TCAAP, and municipal water supply wells. Human exposure to TCAAP contaminants in municipal and TCAAP water supply wells was ended with the use of comprehensive water treatment technology. Current municipal water supplies used by the cities surrounding TCAAP, as well as the TCAAP water supply system, meet all state and federal drinking water standards.

The concentrations measured in some of the contaminated private wells were high enough that long-term exposure (greater than 1 year) to those concentrations could have resulted in adverse health effects. Exposure ended for many of the people with contaminated private wells when their homes were connected to municipal water supplies in the early 1980s.

Nonetheless, other water supplies may be threatened. Unless they are remediated, concentrations of TCAAP contaminants in the Hillside Sand and Prairie du Chien/Jordan aquifers will remain above levels of health concern for many years. The contaminants continue to move and to contaminate other portions of the two drinking water aquifers.

TCAAP groundwater contaminants also pose an indeterminate health hazard because people may be exposed to TCAAP contaminants now or in the future as a result of the unreported or unidentified use of private, mobile home park, commercial, and industrial wells within two plumes of contamination, the North Plume and the South Plume. MPCA, MDH and the Army have undertaken special efforts to identify all wells threatened by TCAAP contaminants. In addition to past inventories and monitoring by MPCA, the Army has conducted a detailed well inventory, at MPCA's request, to determine if there are any previously unidentified water supply wells threatened by TCAAP contaminants.

The possibility of current and future human exposure to TCAAP groundwater contaminants from the North Plume will be mitigated for private well users through implementation of the selected remedy for Operable Unit 1, which was proposed by the Army, MPCA, and the Environmental Protection Agency in September 1993. As described in the Background section of this document, the remedy includes the use of drilling advisories that regulate the installation of new wells within the North Plume as a Special Well Construction Area and the provision of alternative water supplies to residents with private wells within the North Plume. The proposed containment system will prevent future movement of the most highly contaminated portion of the groundwater contaminant plume.

MPCA has stated that the South Plume will also be contained in the Special Well Construction Area (48).

To prevent future human exposure, ATSDR has the following recommendations:

  1. Regulatory agencies should continue their efforts to identify private, mobile home park, commercial, and industrial wells that may be contaminated and are still used for drinking water. Regulatory agencies should continue to sample such wells in a timely way. Alternative water supplies should be provided or contaminant removal systems should be added if sampling results show concentrations exceeding drinking water standards. Contaminated drinking water wells should either be connected to an appropriate treatment system or, after alternative water is provided, be properly plugged and abandoned.

  2. To address future groundwater contamination problems, long-term institutional prohibitions (30 years or longer) should be implemented to prevent installation and operation of wells that would supply water for drinking or bathing unless the wells have appropriate treatment systems. The Army has proposed such institutional prohibitions in the Feasibility Study for Operable Unit 1.

The Health Activities Recommendation Panel, a group of ATSDR scientists, reviewed this document and discussed appropriate follow-up health actions. Based on the recommendations from the panel, the following public health actions will be undertaken by ATSDR:

  1. ATSDR's Division of Health Studies will evaluate the feasibility of conducting a community health investigation.

  2. ATSDR's Division of Health Education will provide environmental health education for local health care providers and the communities.

  3. ATSDR's Division of Health Assessment and Consultation will conduct a health statistics review if appropriate information is available.

BACKGROUND

SITE DESCRIPTION AND HISTORY

The New Brighton/Arden Hills NPL site is a 25-square-mile area in Ramsey County, Minnesota, just north of the Minneapolis/St. Paul metropolitan area. The site includes the 4-square-mile and portions of seven nearby communities: New Brighton, St. Anthony, Arden Hills, Shoreview, Mounds View, Columbia Heights, and Minneapolis. As presently defined, the site covers much of the U.S. Geological Survey's New Brighton, Minnesota, 7.5-minute quadrangle map (1).

Environmental Setting of NPL Site Area

The topography, surface water, and groundwater of the land within the New Brighton/Arden Hills NPL area have all been influenced by the actions of ancient glaciers. The predominant topographic feature of the area is the Arsenal Kame, a hill of glacially deposited sands, silts, and gravel, near the center of TCAAP. The hill is approximately 200 feet above the surrounding land.

The last glacial retreat resulted in a large number of glacial kettle holes that form the many natural lakes and ponds within the NPL area. Some of the kettle-hole lakes, such as Rush Lake (southwest of TCAAP) and Karth Lake (southeast of TCAAP), appear to receive their water primarily from groundwater; the two lakes have very limited surface water drainage and no connection to streams or creeks.

Most of the surface water in the area appears to drain into Rice Creek. Rice Creek enters TCAAP at the northwestern boundary of the facility and exits near the west central boundary. From TCAAP, Rice Creek flows westward until it discharges into the Mississippi River.

Groundwater flow within the NPL area also is influenced by the glacially derived terrain. The permeable geologic sediments composing the Arsenal Kame intersect or overlie two other glacial deposits, the Twin Cities and the Hillside Sand formations (2). The Twin Cities Formation is a silty, clayey, glacial till that retards the downward movement of groundwater to the underlying sands and gravel of the Hillside Sand Formation. Although the Twin Cities Formation extends beneath much of the NPL area, it is not immediately beneath the central portion of the Arsenal Kame; therefore, contaminants leaking into the soils in the central portion of TCAAP may flow directly into the Hillside Sand Aquifer and the underlying Prairie du Chien and Jordan bedrock aquifers.

Groundwater flow beneath TCAAP and the surrounding area has been divided by environmental investigators into four groundwater units on the basis of local and regional geologic strata (Figure 3, Appendix A). In Unit 1, the uppermost groundwater unit, groundwater flow is through lenses of sands, silts, and clays (lacustrine geologic deposits) above the Twin Cities Formation. The multiple, disconnected (discontinuous) clay lenses have accumulated small, saturated zones of groundwater (perched groundwater) that lie above the true water table (saturated zone). Unit 1 is absent from the central portion of the Arsenal Kame.

Unit 2 is composed of sands, silts, clays, and gravels of the Twin Cities Formation. Clays within the Twin Cities Formation act as an aquitard by limiting downward flow of water into the sands and gravels of Unit 3, (Hillside Sand and Arsenal Sand formations). Underlying Unit 3 is Unit 4, which is composed of the Jordan Sandstone Formation and the sandstones and dolomites of the Prairie du Chien Group (2).

Site History
In June 1981, the MPCA and the MDH discovered trichloroethylene (TCE) and other organic chemicals in municipal and private well water in the vicinity of TCAAP. Initial investigations identified a plume of contaminants in the Hillside Sand and Prairie du Chien/Jordan aquifers system extending west and southwest from TCAAP. In the 1980s, as a result of the discovery of widespread groundwater contamination, the following actions were taken (1):

  1. The City of New Brighton abandoned some municipal wells and either placed other wells on standby or deepened them.

  2. The Village of St. Anthony decommissioned one municipal well and temporally connected the homes in part of the village to Roseville water supplies.

  3. A number of contaminated private wells owned by New Brighton/Arden Hills residents were connected by a water main extension to municipal water.

  4. The contaminated, main water supply well at Arden Manor Mobile Home Park was replaced with a new well installed in a deeper, clean aquifer. The Army reimbursed the mobile home park for the new well.

The New Brighton/Arden Hills site was proposed for inclusion on the NPL in July 1982; it was added in September 1983. TCAAP has been identified as the major contributor to the groundwater contamination problem, although several other suspected sources of contamination have also been identified. A list of the suspected sources is contained in the Phase IA remedial investigation report (16).

TCAAP is about 13 miles north of Minneapolis and St. Paul (Figure 1, Appendix A). Originally owned by several farming families, the 960 hectares (3.75 square miles) of land encompassed by TCAAP were acquired by the Army in 1941. The construction of the industrial plants, 323 buildings with supporting utilities and services, was completed in 1943 (2). TCAAP is a government-owned, contractor-operated federal facility, and its primary purpose is production of ammunition in support of military operations.

TCAAP is considered by the Army to be an inactive military facility that is not needed for current Department of Defense (DOD) programs. However, if the national defense needs change, the land may be needed for future DOD programs. As a result, the Army considers TCAAP to be in a "modified caretaker" status.

Historically, ammunition production has been periodic; peak production has been during wars and other armed conflicts. During its 50-year existence, the plant has actively produced ammunition for about 22 years (3). Except for the period from 1946 to 1950, when the facility was operated by the Army, the Federal Cartridge Company (FCC) has been the primary operating contractor.

TCAAP has hosted many industrial and commercial activities. Beginning in the 1950s, several tenant industries have operated at the facility. Included are the Minnesota Mining and Manufacturing Company (3M), which produced self-luminous materials, medical products, and static eliminators; and Alliant Techsystems Inc. (formerly Honeywell Inc.), which manufactured fuses and selected ammunition. Local businesses and organizations also leased numerous areas and buildings for storage.

Industrial operations take place in the western half of the TCAAP area; there are entrances from U.S. Highway 10, County Road H, and Lexington Avenue. The entire facility is fenced; the only authorized access is through the guarded entrances.

Former firing and test ranges are on the eastern part of TCAAP, between the Arsenal Kame and Marsden Lake. In the southeastern corner is a shallow lake known by two names, Sunfish Lake and Ryan Lake. The Army Reserve Center, which has an entrance off Minnesota Highway 96, is along the southeastern boundary of TCAAP. The reserve center property was once part of TCAAP but was transferred to the Army Reserve for construction of the Army Reserve Center.

A closed military housing area (14 units) is on the northwestern boundary of TCAAP. Families of active-duty military personnel occupied the units until the area was closed in late 1992. During the June 1992 site visit, ATSDR personnel saw a small playground and some individual gardens next to the security fence that separates the housing area from TCAAP operations.

Immediately north of the military housing area and outside the northwestern boundary of TCAAP are the Minnesota Department of Transportation offices and buildings. While they are on state property, these buildings are served by the TCAAP water supply system.

Although several limited environmental investigations were performed from the 1950s to the 1970s, the majority of the environmental investigations at TCAAP have been performed since 1981. Fourteen source areas at TCAAP have been identified and investigated (Figure 2, Appendix A). The source areas are described in Appendix D.

Periodic monitoring of the source areas and environmental media continues. Pertinent environmental investigations and results are discussed in the Environmental Contamination and Other Hazards section of this document.

Interim Remedial Actions

Many interim remedial actions (IRAs) have been instituted on and off TCAAP to mitigate or eliminate human exposure. The IRAs being conducted by the Army and Alliant Techsystems have concentrated on contaminant source control, with a focus on individual site cleanup and groundwater remediation. Actions in the following categories have already been taken: a) alternative water supplies, b) unilateral actions by the Army, c) actions with EPA and state concurrence, and d) other actions initiated by EPA or the Army (1). The actions are summarized in the following paragraphs.

Alternative Water Supplies

In addition to the alternative water supplies provided shortly after the discovery of contamination at the site, the following systems have been completed:

  1. Army contractors built a temporary granular-activated carbon (GAC) treatment system for the City of New Brighton as part of a litigation settlement agreement. The temporary system was replaced by a permanent GAC system. The permanent system, completed in June 1990, presently treats water from New Brighton Wells 3, 4, 5, and 6 and has a capacity of 3,200 gallons per minute (gpm).

  2. A temporary GAC treatment system was built for the Village of St. Anthony by EPA and MPCA and was replaced by a permanent GAC system. The permanent system is a remedial action pursuant to a record of decision (ROD) signed in September 1986. The system, completed in April 1991, treats water from St. Anthony Wells 3, 4, and 5 and has a capacity of 2,400 gpm.

Unilateral Actions (Army)

Unilateral actions taken by the Army include the following:

  1. In situ soil vapor extraction (ISV) systems were installed for the remediation of contaminated soils at sites D and G on TCAAP. The ISV systems were activated in 1986; since then, more than 115 tons of volatile organic compounds (VOCs) have been removed from site soils.

  2. Groundwater pump-and-treat systems have been installed at sites A, I, and K.

Actions undertaken by the Army with EPA and State Concurrence include the following:

  1. In 1987, the Army implemented the Boundary Groundwater Recovery System (BGRS), for which EPA signed an ROD in September 1987. The system initially consisted of a series of six groundwater extraction wells (located along the southwestern boundary of TCAAP) designed to prevent further migration of contaminated groundwater from TCAAP. Four wells in Unit 4 and two additional wells in Unit 3 were later added to the BGRS. The expanded BGRS became operational on January 31, 1989.

  2. In addition to the implementation of the BGRS, the Army subsequently installed five source control (SC) wells downgradient of sites D, G, and I. The BGRS and SC wells together make up the TCAAP Groundwater Recovery System (TGRS).

Other Actions by the EPA or the Army include the following:

  1. Site J, which contains the sanitary sewer system for TCAAP, was investigated several times; cleaning and testing began in 1984 and ended in 1986.

  2. Between 1984 and 1986, Alliant Techsystems removed contaminated sludge from the sewers leading away from Building 502. In addition, Alliant excavated soils contaminated with polychlorinated biphenyls (PCBs) around Building 502 in 1985.

  3. About 1,400 cubic yards of PCB-contaminated soil at Site D was thermally treated in 1989.

Operable Units and Selected Remedies

For the purpose of selecting and implementing appropriate remedial solutions, the NPL area has been subdivided into three operable units. The first operable unit (OU-1) consists of the North Plume of off-TCAAP contaminated groundwater in aquifer units 3 and 4. The second operable unit (OU-2) consists of the on-TCAAP soils, sediments, surface waters, and groundwater. The third operable unit (OU-3) consists of the South Plume of off-TCAAP groundwater contaminants (1).

Preferred remedies have been selected for OU-1 and OU-3. As described in the September 1993 Record of Decision for OU-1 (1), the major components of the selected remedy for OU-1 are these:

  • providing an alternative water supply to residents with private wells within the North Plume;

  • implementing drilling advisories that would regulate the installation of new private wells within the North Plume;

  • implementing the groundwater extraction scheme for containment of the North Plume at the boundary of County Road E;

  • pumping the extracted groundwater to the Permanent GAC Water Treatment Facility in New Brighton for removal of volatile organic compounds by a pressurized GAC system;

  • discharging all of the treated water to the New Brighton/Fridley municipal distribution system interconnect; and

  • and monitoring the groundwater to verify the effectiveness of the remedy.

An ROD for the selected remedy for OU-3 was issued in September 1992. The major components of the selected remedy include these:

  • extracting groundwater at the leading edge of the South Plume;

  • treating extracted groundwater with a pressurized GAC system to remove VOCs;

  • discharging the treated groundwater to the potable water supply of the City of New Brighton; and

  • monitoring the groundwater to verify the effectiveness of the remedy.

A remedy for OU-2 is expected to be proposed in mid-1994 (1).

PUBLIC HEALTH SERVICE AND ATSDR INVOLVEMENT

In September 1981, representatives of the Region V Office (Chicago) of the Public Health Service participated in discussions about groundwater contamination in the New Brighton/Arden Hills area with other members of the Regional Response Team (4), a group of federal agencies that evaluates environmental and health issues during environmental and public health emergencies. In 1983, ATSDR's predecessor, the Superfund Implementation Group (SIG) within the Centers for Disease Control (CDC), received a request from the Army to evaluate cancer cases in the New Brighton/Arden Hills area or to conduct a health study (5). The EPA Region V office also requested assistance from CDC/SIG (6). CDC scientists reviewed information from MPCA and MDH but concluded that there were not sufficient scientific data at that time to support meaningful recommendations (7).

In May 1987, 15 families from St. Anthony, Minnesota, petitioned ATSDR to conduct a health assessment focusing on populations exposed to hazardous substances from TCAAP. The petitioners believed that the health assessment would lead to epidemiologic studies and the establishment of a health surveillance program (8). ATSDR agreed to conduct the health assessment in conjunction with the health assessment of the New Brighton/Arden Hills NPL site, of which TCAAP was an integral part (9).

In November 1987, in response to a request from EPA Region V, ATSDR issued a health consultation on TCE emissions from air-stripping towers proposed for use in remediating groundwater contamination (10). ATSDR recommended instituting a comprehensive air-monitoring plan that called for monitoring air at the emission source as well as monitoring potential points of human exposure on TCAAP and in nearby residential areas. The health consultation noted the contamination of private wells; therefore, ATSDR recommended alternative water supplies for affected populations.

In August 1988, ATSDR prepared an initial release preliminary health assessment that was sent to the MDH and the EPA for review and comment. The initial release document erroneously identified TCAAP, rather than New Brighton/Arden Hills, as the NPL site. All comments from EPA and MDH were received by November 1988, but the error in the title was not noted until May 1989, when the report was revised. A final version was issued in June 1989 as, The Preliminary Health Assessment of the New Brighton/Arden Hills NPL Site. The circulation of the final preliminary health assessment was unintentionally limited, and many concerned people, including petitioners; concerned residents; and project managers for the Army, EPA, and MPCA; did not receive copies until 1990.

Both the initial release draft and the final preliminary health assessment contained recommendations for a private well inventory to identify potentially contaminated wells. As part of a follow-up to that recommendation, ATSDR in 1991 prepared a health consultation that identified areas where contaminated wells might still be in use and recommended follow-up by appropriate agencies. The consultation was discussed at the July 1991 project managers meeting at TCAAP.

ATSDR attempted to recruit residents from the New Brighton/Arden Hills communities for the TCE Exposure Registry in 1989. After consulting with the MDH, community leaders rejected participation in the registry. MDH stated in a letter to ATSDR (11) that "the levels of exposure in New Brighton are of such low levels that the likelihood of developing new insights on TCE health risks is extremely small." In the same letter, the MDH concluded that "the benefits for either science in general or the residents in particular appear to be minimal."

The initial release draft of this document was sent to EPA, the Army, MDH, and MPCA for review and comment in October 1992. The City of New Brighton also obtained a copy of the 1992 initial release draft. Many constructive and detailed comments on background information and environmental data were provided by the reviewing agencies. Also, the City of New Brighton (12) and MDH (13) indicated concern about possibly misleading wording related to municipal water supplies and about recommendations of the Health Activities Recommendation Panel (HARP). ATSDR staff members met with representatives of all the reviewing agencies to resolve the comments and issues.

A second draft document was issued in November 1993 for public review and comment. Copies of the document were made available at public libraries in Ramsey County and at the document repository on TCAAP. ATSDR authors attended a Technical Review Committee (TRC) meeting at TCAAP on December 7 to answer questions about the draft document from the Army, EPA, MPCA, and MDH and any other member agency of the TRC.

Public availability sessions were held in the New Brighton City Hall during the evening of December 7 and during the morning and afternoon on December 8. Only three citizens visited the public availability sessions to discuss health concerns. These concerns are summarized in the Community Concerns section of this document.

Written comments were received from government officials but not from any individual citizen or non-government group. Comments on the draft document were received from EPA, MPCA, the City of New Brighton, and the Army during the comment period, which ended December 20. A letter from MDH concerning the draft document was received on December 29.

The comments recieved are summarized and discussed in Appendix F of this document. Pertinent information, corrections, and many of the editorial suggestions received in the written comments were incorporated into this document.

B. SITE VISITS

ATSDR staff members have attended several technical and public meetings at TCAAP since 1987. In 1987, an ATSDR regional representative met with community leaders and residents, including petitioners. Scientists from the ATSDR Division of Health Assessment and Consultation have visited TCAAP several times, and they attended public meetings there in 1991 and 1993.

Observations and information obtained during the various site visits are incorporated into this report.

C. DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE

DEMOGRAPHICS

ON-TCAAP HUMAN POPULATIONS

On-TCAAP human populations of the past are categorized as residents or workers. Residents are limited to active duty members of the U.S. armed forces and their dependents who occupied the 14 housing units along the western boundary of TCAAP while they were stationed in the Minneapolis/St. Paul area. Only one of those persons appeared to have a duty station on TCAAP. Duty stations of the others appeared to be off TCAAP at recruiting or other military offices.

In 1981, 14 members of the military and 40 dependents occupied the housing units. Housing records do not indicate age, sex, or race of the residents; however, in 1989, of the 58 people living in the on-TCAAP housing units, 32 were children and 26 were adults. No housing records were available for years earlier than 1981, so it was not possible to determine lengths of residence for occupants on TCAAP before that year. However, records from 1981 to 1990 indicated that 6 years was the longest single period of occupancy by any one family. Because the military housing units were closed in 1992, there are no current residential populations on TCAAP.

As of September 1993, approximately 980 people were employed at TCAAP (1). The on-TCAAP worker population comprises employees of the Army, FCC, and Alliant Techsystems (formerly Honeywell). The TCAAP water supply serves those employees as well as other nearby government workers, including members of the U.S. Army and Army Reserve and workers at the Minnesota Department of Transportation.

OFF-TCAAP HUMAN POPULATIONS

The communities around the TCAAP facility were studied in an attempt to identify the total population of people exposed to hazardous waste. Census tract information from 1980 and 1990 was obtained for census tracts that border the installation. In 1980, the total population living within a 2-mile radius of the site was approximately 16,073 persons; 97% were white; 9% were under 5 years old, and 3% were over 65 years old.

This population was analyzed using a geographic information system (GIS); results appear in Appendix B. The GIS indicates increased minority population in the Round Lake area; general population density in that area is also increased. In 1980, the majority of the homes in that area (80%) were owner-occupied, indicating a stable population.

In 1990, the population in the census tracts bordering TCAAP was 39,976; 96% of the population was white; 8% were below age five, and 7% were over age 65. Tables 1B through 8B in Appendix B provide additional details about the populations surrounding TCAAP.

LAND USE

Land use in the New Brighton/Arden Hills area has changed from agricultural to commercial, industrial, and suburban residential. TCAAP contains the largest area of undeveloped land. Subdivisions are north and east of TCAAP, just across the highways from the facility. A community park (Shamrock Park) is immediately north of TCAAP. Turtle Lake Elementary School is across Marsden Lake marsh from the northeastern boundary. Immediately south of TCAAP and across highway 96 are additional suburban residential areas as well as the government offices of Arden Hills Village.

Land use west of TCAAP is a mixture of commercial operations, such as lumber yards; single-family residences; and a mobile home park. Located approximately 800 feet southwest of TCAAP and housing an estimated 750 people, Arden Manor Mobile Home Park is the high-density residential area closest to the sources of groundwater contamination.

The original mobile home park consisted of 96 locations (pads) for mobile homes. Expansion of the mobile home park began in 1973, when 26 pads were added. Additional pads were added each year until 1979; currently, the park contains 298 pads (14). Although a few families may have lived in the park for as long as 15 years, one of the owners estimated that the average residency period is 5 years.

Approximately 1 mile southwest of TCAAP, on the eastern shore of Long Lake, is a county park. South-southwest of TCAAP, along the shore of Round Lake, are suburban homes. The center of New Brighton is approximately 2 miles southwest of TCAAP. Northwest of TCAAP are the commercial and housing areas of Mounds View. Several public schools and day-care centers are within a mile of the TCAAP boundaries.

The numerous lakes and parks in the area are used for outdoor recreation. During the summer site visits, ATSDR personnel saw several people fishing, swimming, or wading in the lakes.

NATURAL RESOURCE USE

Natural resources used by people living in the vicinity of TCAAP include groundwater, surface water, and edible plants.

Groundwater Use

Groundwater is the source of drinking water for many of the communities surrounding TCAAP. Wells tapping both the Hillside Sand aquifer and the deeper Prairie du Chien/Jordan aquifer system supply individual homes, businesses, and municipal systems. However, within the area of groundwater contamination, there has been a greater reliance on municipal water supplies since the discovery of contaminated wells in the early 1980s.

With the exception of those serving some residences on the shore of Round Lake, private wells immediately west and southwest of TCAAP (primarily wells in the New Brighton and Arden Hills communities) appear to use the Hillside Sand Aquifer. Private wells at Round Lake draw water from the Unit 1 aquifer. Some private wells a mile or more west and southwest of TCAAP draw water from the deeper Prairie du Chien/Jordan aquifer system. The few wells still in use in the Edgetown subdivision of Shoreview, which is immediately north of TCAAP, tap either the Unit 1 aquifer or the Unit 3 aquifer. The majority of the homes in Edgetown subdivision are now connected to the Shoreview municipal water system.

Municipal water is available in most of the residential locations in the area surrounding and downgradient of TCAAP. The cities north of Minneapolis and St. Paul use the deep regional drinking water aquifers, such as the Prairie du Chien/Jordan aquifer system or the Mt. Simon/Hinckley aquifer system.

The Prairie du Chien/Jordan aquifer system also supplied water to the Arden Manor Mobile Home Park until 1983, when a well (Well #2) originally drilled in 1976 was replaced by a newer, deeper well (Well #3) drilled in the uncontaminated Mt. Simon/Hinckley aquifer system (14). Well #2 was used as an emergency back-up well from 1983 to 1993. Before 1976, the original mobile home park area was supplied by a well (Well #1) drawing water from the Hillside Sand aquifer.

As part of their early efforts to identify all wells within the area of contamination, MDH and MPCA in the early 1980s catalogued approximately 2,000 wells within a 3-mile radius of TCAAP. This well listing has been refined over the years as MPCA and MDH have continued to monitor the impact of groundwater contamination on drinking water wells. However, as indicated in the 1989 ATSDR preliminary health assessment and the 1992 ATSDR health consultation, an additional, detailed inventory was needed to determinate if any contaminated wells were still being used or if any wells not previously identified might become contaminated in the future. In response to this need, MPCA and EPA recommended that the Army perform such a detailed inventory within the area of groundwater contamination.

A detailed well inventory has been conducted by Army consultants (15) on behalf of the Army. Part I summarized existing information from several sources, including MPCA and Army files. Wells identified in Part I were classified according to the likelihood that they would be affected by TCAAP contaminants. Part II, completed in September 1993, provides a more detailed analysis of wells that may be threatened by TCAAP contaminants.

Surface Water Use

Rice Creek may be used by local children as part of a general play area, because it flows near schools and homes. Between approximately 1 and 2 miles downstream from the exit point from TCAAP, Rice Creek flows past Edgewood School, Irondale School, and a Mounds View subdivision before it empties into Long Lake.

Lakes and ponds in the vicinity of TCAAP are used for swimming, boating, and fishing. Approximately 2 miles downstream from TCAAP is Long Lake, which is part of a county park with two swimming beaches. Long Lake also borders residential areas. Approximately 110 homes are along the northern and western shores of Long Lake.

Many other residents near TCAAP have year-round access to lakes and ponds that receive drainage waters from TCAAP. Many of the homes downgradient of TCAAP are adjacent to other lakes in the area, such as Round Lake and Valentine Lake. Arden Manor Mobile Home Park has a small pond that receives a portion of its drainage water from the Gate 4 area of TCAAP.

Edible Plants and Animals

Local animals and fish may be eaten as a result of hunting and fishing in the area. White-tailed deer that range within the TCAAP boundaries are hunted by specialists from the University of Minnesota to limit the deer population; the deer meat is given to local charitable organizations. The Minnesota Department of Natural Resources stocks state fishing areas with walleye fingerlings raised in Sunfish Lake on TCAAP.

ATSDR scientists on site visits have observed recreational fishing downstream from TCAAP in Rice Creek and in the connected lakes. Edible terrestrial biota on and near TCAAP include deer, rabbits, ducks, geese, doves, pheasant, grouse, and turkeys. Consumable aquatic biota found on TCAAP and downstream from it include walleye (Sunfish Lake) and bullheads (Round Lake).

The only known cultivated, edible plants in the area are the garden vegetables and fruits observed in the military housing area (when it was still in use) and in residential areas near TCAAP.

D. HEALTH OUTCOME DATA

ATSDR personnel reviewed vital statistics for the communities of Arden Hills, New Brighton, Shoreview, and Mounds View, as well as vital statistics for the state of Minnesota, for the years 1980, 1985, and 1988. Statistics on births and deaths were reported at the county level. Cancer statistics at the county level were obtained from the state cancer registry; no site-specific information was available.

In 1985, MDH studied the feasibility of conducting an epidemiologic investigation of drinking water and health in the New Brighton community. That study is described in the Public Health Implications section of this public health assessment.

ATSDR personnel reviewed depositions of physicians who had examined several persons from the residential populations surrounding TCAAP. Because the persons examined were self selected, there exists a bias that prevents valid statistical analysis. On the other hand, the reports do indicate the types of symptoms reported by persons in the communities.


COMMUNITY HEALTH CONCERNS

Several members of the New Brighton and Arden Hills communities filed a lawsuit against the Army because they believe their health has been adversely affected by the contamination of the area's water supply. The health effects reported by the community members were primarily neuropsychiatric: mood disorders, attention disorders, memory problems, and symptoms of peripheral neuropathy. Several community members were seen by a neurologist and an occupational medicine physician. The physicians' reports are discussed in the Public Health Implications section of this document.

At a November 1991 public meeting in Mounds View concerning TCAAP hazardous waste investigations and remedial actions, some local citizens expressed health concerns summarized here:

  1. Will epidemiologic studies be performed? If so, when?

  2. Can birth defects result if a pregnant woman ingests contaminated water (at the concentrations reported for a mobile home park near TCAAP)?

  3. Are citizens being exposed to toxic substances in the air?

  4. Is there a link between cases of leukemia in the exposed population and the use of solvent-contaminated drinking water?

During the public availability sessions held on December 7 and 8, 1993, the following health concern was raised:

  1. Could drinking the water from the municipal water system during the period that the municipal water supply was contaminated cause testicular cancer or other cancers noted in a New Brighton neighborhood?

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