Perchlorate Contamination in the Citizens Utilities'
Suburban and Security Park Water Service Areas
RANCHO CORDOVA, SACRAMENTO COUNTY, CALIFORNIA
The California Department of Health Services (CDHS), under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR), is conducting health assessment activities on the Aerojet-General Corporation (Aerojet) Superfund site in Sacramento County, California (See Figure 1). A Preliminary Health Assessment written in December 1988 recommended that when additional environmental information and data became available ATSDR would make another assessment (1). A Site Review and Update written in March 1993 also recommended a health assessment be conducted when more data became available (2).
This health consultation is one in a series that will be performed as part of the ATSDR health assessment process at this site. During this process, data and information on the release of hazardous substances and their impact on public health will be evaluated. Four health consultations have recently been written as part of this series (3-6). In this health consultation, we will focus on describing the Citizens Utilities service areas potentially affected by the perchlorate contamination (Figure 2). We are also in the process of writing several other health consultations that focus on perchlorate exposure to consumers of water from other water purveyors in the area and from private wells in the area. In addition, we have also written a health consultation that describes the perchlorate groundwater contamination west of the Aerojet Superfund site.
Aerojet began operation in 1951. Since that time, Aerojet has manufactured liquid and solid propellants for military and commercial rocket systems and has fabricated, assembled, tested and rehabilitated rocket engines (1). In addition, between 1974 and 1979, Cordova Chemical Company, a wholly-owned subsidiary of Aerojet, manufactured paint components, herbicides, and pharmaceutical products. Over the years, Aerojet and Cordova Chemical disposed of hazardous waste by burial, open burning, discharge into unlined ponds, and injection into deep underground wells (1). Some of these discharges, including perchlorate, contaminated the environment and have moved off-site of the Aerojet facility boundary (Figure 1). Perchlorate in the groundwater arises from ammonium perchlorate being a main component of solid rocket fuel. In addition to the natural migration of perchlorate-contaminated groundwater from the site, Aerojet is reinjecting treated groundwater, contaminated with perchlorate, at the site's western boundary. The Regional Water Quality Control Board (RWQCB), the California Department of Toxic Substances Control (DTSC) and the U.S. Environmental Protection Agency (USEPA), are the lead regulatory agencies overseeing groundwater investigation and cleanup at Aerojet, and are also investigating other sources of the perchlorate, such as the McDonnell Douglas (now Boeing) and Purity Oil Sales sites.
The Citizens Utilities Company is a full-service telecommunications company with utility assets that provide natural gas distribution, electric distribution, and water and wastewater treatment services. Citizens Utility stock is traded on the New York Stock Exchange. Citizens Utilities serves water to several geographical areas in Sacramento County, including two separate water systems near the Aerojet site, the Suburban and the Security Park systems (Figure 1).
The Suburban system is located to the west of the Arden Cordova Water Service and Mather Air Force Base. Citizens Utilities Company serves water to approximately 33,600 people via 10,192 connections (as of 1996), approximately 2000 are commercial and the rest residential in the Suburban System (7). Water is supplied to the Suburban system from 20 wells located within the service area (Figure 1)(7).
Due south of the Aerojet and McDonnell Douglas sites, the Citizens Utilities Company services the Security Business Park (8). There are two separate water systems located within Security Business Park; only one is being used. The system which is being used consists of two wells (only well #2 is being used), two storage tanks, and a booster pumping station. The second system, referred to as the Beta area has two pit wells, one storage tank, and a booster pumping station. A total of 16 service connections are in use and receive water from Security Business Park well #2. Approximately 600 people work at Security Business Park.
Citizens Utility was forced to shut down one its Suburban system wells (Citizens Utility Well #29, the Explorer well) because of tetrachloroethylene (PCE) contamination that originated from Mather was detected in the well water (8). Citizens Utilities requested compensation for the water production loss so the Air Force constructed an intertie between the Main Base system and Citizens Utilities' Suburban System which could provide 900 gallons per minute. The intertie was used to supply water from July to November 30, 1995 (9) and from July to October 1996 (10).
Another Suburban well (Citizens Utility well #37, the Moonbeam well) has also been contaminated by a plume coming from Mather Air Force Base (7). Carbon tetrachloride was found in the Moonbeam well (up to 0.5 parts per billion (ppb) and the Air Force placed a granular activated carbon treatment system on the well in early 1997.
Two of the 20 Suburban wells have had levels of nitrate above 22.5 parts per million (ppm) and one well (Whitewater well) has at least one reading above the Maximum Contaminant Level of 45 ppm (7).