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The Washington State Department of Health (DOH) prepared this health consultation at the request of the Whatcom County Health Department (WCHD) to evaluate the potential human health risks for residents living near the Wilder Landfill.

The 20-acre landfill is located at 1524 Slater Road in Whatcom County, about two miles south of Ferndale, Washington (Figure 1). The Landfill is located in a mixed residential and farming community. The site began as a municipal landfill in 1975.1 The landfill received municipal refuse, incinerated refuse, and demolition debris starting in the early 1970s. In 1976, the site was authorized by WCHD to receive and dispose of hazardous waste. The site was purchased in 1990 by a reduction/energy and recovery company known as Recomp of Washington (Recomp). The site remains a municipal waste collection and transfer facility. Municipal waste is collected, sorted, and compacted into railroad freight containers and shipped to Klickitat County for disposal.

The facility consists of an office, incinerators (currently shut down), a closed municipal landfill, a closed hazardous waste pit, an autoclave for sterilization of medical wastes prior to disposal, and a former ash storage area, which is underlain by a high density polyethylene (HDPE) liner.1 The 76,000 tons of stockpiled ash has been removed and transported to Roosevelt, Washington, for disposal. It is speculated that cadmium in the ash had caused elevated cadmium in soils around the facility perimeter; however, more recent soil sampling has shown a decrease in cadmium levels.

The former municipal landfill appears to underlie much of the Recomp property.1 The maximum thickness of the closed landfill is approximately 20 feet. In 1989, the landfill was capped with a low permeability clay cover. As part of the closure, a slurry wall was constructed on the north, east, and south boundaries of the landfill to minimize groundwater flow underneath the facility. An underground leachate collection system was installed on the west side of the landfill.

Monitoring wells were installed and surface water sampling locations were established to monitor the effectiveness of the slurry wall and leachate collection system. Groundwater depths below ground surface vary from 10-20 feet and 40-50 feet.1 The groundwater collected from the monitoring wells had contained elevated chloride and specific conductivity; however, it is unknown as to whether this is due to leachate coming off the landfill, or stockpiled salt deposits located upgradient from the landfill.

The hazardous waste pit, located on the north side of the landfill (Figure 2), contains up to 20 feet in depth of waste, with an estimated volume of about 4,000 cubic yards.1 Wastes disposed of in the hazardous waste pit include incinerator ash, oils, resins, solvents, pentachlorophenol, asbestos, insecticides, catalyst beads from oil refineries (sources of cobalt, molybdenum, and hydrochloric acid), and lignosite from the local paper mill. The hazardous waste pit is not fenced, but was reportedly covered with a five-foot clay cap. No cleanup activities and very little environmental monitoring have been conducted.

Groundwater generally flows west/northwest. Groundwater monitoring at Recomp is conducted quarterly from nine monitoring wells, located up and downgradient, with varying depths ranging up to 95 feet (Figure 2).2 The highest concentration of arsenic in MW-4 was at 39 ug/l. The highest concentration of lead, also in MW-4, was detected at 6 ug/l, and the highest concentration of manganese in MW-11 was detected at 3,930 ug/l.2 MW-1 and MW-2 have been abandoned since 1990. The only known domestic drinking water well is located approximately one-half mile northeast of the facility near the intersection of Byres Road and Smith Road (Figure 1). The domestic well was tested in July of 1996 and found to be free of heavy metals contamination.3

Claypit Pond is an 11-acre, 30-foot deep, constructed pond, located on the west side and downstream of the landfill.1 A drainage ditch located immediately west of the landfill drains into the pond. Sediments from Claypit Pond have contained elevated levels of chromium.4 In the late 1980s, concentrations of chromium in surface water were measured as high as 740 ppm.5 Claypit Pond was routinely stocked with fish by the Washington Department of Game; however, since the surface water in the pond and fish reportedly contained elevated metals, the Washington State Department of Wildlife closed the pond to fishing in 1988.


Monitoring well sampling results were evaluated using health comparison values (CVs) for both non-carcinogenic and carcinogenic health effects. CVs for non-carcinogenic health effects are based on the Agency for Toxic Substances and Disease Registry's (ATSDR's) Minimal Risk Levels (MRLs) or the Environmental Protection Agency's (EPA's) reference doses (RfDs). MRLs and RfDs are estimates of daily human exposure to a contaminant that are unlikely to cause non-cancer adverse health effects over a lifetime. The MRLs and RfDs used in this assessment are based on chronic exposure to contaminated drinking water through ingestion. CVs for carcinogenic risk, derived using EPA's cancer slope factors, are based on a theoretical upper bound risk of one excess cancer in one million people exposed over a lifetime. Health consultation comparison value concentrations are used to select environmental contaminants for further evaluation. CVs are not used as predictors of adverse health effects or as threshold values for cleanup activities.

Arsenic and manganese were the only constituents that exceeded health comparison values for drinking water in monitoring wells MW-4 and MW-11; however, it is not necessary to evaluate these constituents for cancer and non-cancer health effects because there do not appear to be any completed ingestion pathways. The groundwater gradient is to the west/northwest and other on-site groundwater monitoring wells, located downgradient of MW-4 and MW-11 have not shown elevated levels of arsenic and manganese. The only known domestic drinking water well is located approximately one-half mile northeast, and has been shown to be free of contamination. Thus far, it appears that a house to house survey for private wells has not been performed.

There has been a concern with cadmium in the ash causing an accumulation of cadmium in the surrounding soil areas. However, over the years, cadmium in soil has been declining. On an annual basis, soil sampling has been conducted at 16 locations along the property line since 1993 and analyzed for cadmium. The cadmium concentrations decreased from 1993, from an average of 1.43 mg/kg to an average of 0.69 mg/kg in 1997.

There has been no groundwater monitoring or surface soil sampling at the hazardous waste pit. The only environmental samples taken near the hazardous waste pit were two surface water samples at the northwest and southwest ends of the hazardous waste pit, in which heavy metals were detected at low concentrations.1 There is no information about groundwater near the hazardous waste pit. Since the waste pit is a source of hazardous waste, associated groundwater may be impacted. The only known drinking water well, located approximately one half-mile northeast of the site, does not appear to have been impacted; however, this well is not downgradient of the hazardous waste pit, but rather perpendicular to a potential groundwater plume.


The potential for exposure and subsequent adverse health effects are often increased for young children as opposed to older children or adults. Children are far more likely to engage in activities that involve getting dirty. Playing in dirt combined with frequent hand-to-mouth activity provides toddlers and young children with an increased chance of exposure to contaminants by way of ingestion, inhalation, and skin contact. In addition to the potential for higher exposures of young children, the risk of adverse health effects is also increased. ATSDR and DOH recognize that children are susceptible to developmental toxicity that can occur at levels much lower than those causing other types of toxicity. Since residential areas are near this site, and the hazardous waste pit and Claypit Pond are not fenced, children could venture near these areas to play.


  1. There is very little information for surface water and no information for surface or shallow soil at the hazardous waste pit, and there is no intruder barrier surrounding this area. In addition, there is no information about the groundwater near the hazardous waste pit. Since the waste pit is a source of hazardous waste, it may be affecting groundwater. There also is incomplete information with respect to private drinking water wells downgradient of the hazardous waste pit; therefore, an indeterminate public health hazard exists for this area.

  2. It appears that sediment and surface water in Claypit Pond have been impacted by elevated concentrations of metals. However, since the pond is not used for drinking water, and is no longer being stocked with fish, and fishing is prohibited, no ingestion pathways appear to exist, hence, there is no apparent public health hazard.

  3. Based on available groundwater data with the closed municipal landfill, some monitoring wells have shown elevated levels of manganese and arsenic; however, other on-site monitoring wells further downgradient do not show these constituents, hence there is no apparent public health hazard.


  • The hazardous wastepit located north of the Wilder Landfill should be completely characterized to determine if soil, surface water, and groundwater have been impacted. If surface water and/or soil have been impacted, an intruder barrier should be installed. In addition, a house-to-house survey should be performed in order to verify the location, if any, of private drinking water wells downgradient of the hazardous waste pit. If groundwater has been impacted and if there are private wells downgradient of the hazardous waste pit, alternate sources of drinking water should be established.

  • Continue to prohibit fishing in Claypit Pond until it has been determined that heavy metal contamination in surface water and sediment has diminished below levels of health concern.
  • Action

    DOH intends to review upcoming work plans for environmental sampling of the hazardous waste pit, and review future environmental monitoring data to assess human health pathways. Copies of this health consultation and future recommendations will be provided to Ecology, Whatcom County Health District, Recomp of Washington, and made available to citizens in the area.


Steve Matthews
Office of Environmental Health Assessments
Washington State Department of Health

ATSDR Technical Project Officer

Debra Gable
Division of Health Assessment and Consultation
Superfund Site Assessment Branch


  1. Site Evaluation, Wilder Landfill, Site Hazard Ranking Category - 1, B. Trejo, December 2, 1999.

  2. 1998 Recomp Annual Report, Recomp of Washington, Inc., February 1999.

  3. Water Well Report, Whatcom Identification #583, B & C Well Drilling & Pump Service, October 14, 1996.

  4. Claypit Pond Sediments High in Metals, J. Cubbage, February 10, 1989.

  5. Metals Concentrations in Sediments of Claypit Pond Area Including a Review of metals Levels found in Water Samples, March 1996.


Regional Map
Figure 1. Regional Map

Facility Layout
Figure 2. Facility Layout


This Health Consultation was prepared by the Washington State Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.

Debra Gable
Technical Project Officer,

The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.

Lisa C. Hayes
for Richard Gillig
Branch Chief,

Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

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