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  1. Kent Highlands Landfill is categorized as being no apparent public health hazard because, (1) none of the estimated exposures exceeded ATSDR Minimal Risk Levels, (2) data were available for all environmental media to which humans were exposed, and (3) there are no community-specific health outcome data to indicate that the site has had an adverse impact on human health.
  2. Only one completed pathway exists, which is the use of Midway Creek by recreationists. However, worst case scenarios were evaluated and there did not appear to be a human health threat. Two potential pathways were analyzed, for landfill gas and ground water. Again the worst case scenarios did not reveal any imminent human health threat.
  3. The south property line has not been fenced, but is scheduled for the summer of 1994 as part of the currently underway closure construction.
  4. Contaminants have migrated to ground water, surface waters, and air. However, site remediation efforts for leachate collection and gas collection have reduced contaminant concentrations to very low levels.
  5. Because there are contaminants in the ground water and there are privately owned wells which draw from the contaminated aquifer, there is still a potential for human exposure. There is a need for continued monitoring of the ground water.
  6. There is evidence that the landfill cover material has settled. The final cover system is designed to be stable.


Cease/Reduce Exposure Recommendations

  1. The south property boundary should be secured as soon as possible against trespass as planned to minimize exposure to surface waters.
  2. Ground water monitoring should continue as required by applicable regulations for protection of private wells.
  3. Careful maintenance of the gas control system and air monitoring should continue as required by applicable regulations.
  4. Stability of the cover material should continue to be monitored. The final cover system should be visually inspected as part of the regular post-closure maintenance.

Site Characterization Recommendations

None necessary

Health Activities Recommendation Panel (HARP) Recommendations

The data and information developed in the Kent Highland Landfill Public Health Assessment has been evaluated by the ATSDR Health Activities Recommendation Panel (HARP) for follow-uphealth actions. No follow-up health actions are indicated at this time.


Based upon conclusions and recommendations from the public health assessment for Kent Highlands Landfill site and the HARP review, ATSDR has developed the following public health actions which ATSDR, in cooperation with DOH, will conduct:

  1. As additional data becomes available, ATSDR and DOH will re-evaluate the Kent Highlands Landfill site for necessary follow-up health activities.
  2. As remedial measures are implemented, DOH staff will be available for health consultation where needed.

Activities from other agencies or companies include:

  1. Negotiations between the City of Seattle Solid Waste Utility and the Washington State Department of Transportation to fence the right-of-way have been completed and the fencing is currently under construction.
  2. The gas extraction/control system has been completed as planned by the City of Seattle Solid Waste Utility.


Public Health Advisor
Washington State Department of Health

ATSDR Senior Regional Representative

Office of Regional Services
Office of the Assistant Administrator

ATSDR Technical Project Officer

Environmental Health Scientist
Remedial Programs Branch, State Programs Section
Division of Health Assessment and Consultation


This Seattle Municiipal Landfill/Kent Highlands Public Health Assessment was prepared by the Washington 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 public health assessment was begun.

Richard R. Kauffman, M.S.
Technical Project Officer
Superfund Site Assessment Branch
Division of Health Assessment and Consultation (DHAC)

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

Robert C. Williams, P.E., DEE
Director, DHAC, ATSDR


  1. Agency for Toxic Substances and Disease Registry, 1990, Preliminary Health Assessment for Seattle Municipal Landfill (Kent Highlands Landfill).

  2. U.S. Environmental Protection Agency, 1986, Hazard Ranking Documents for Seattle Municipal Landfill (Kent Highlands).

  3. Seattle Engineering Department Solid Waste Utility, Oct 1986, Final Environmental Impact Statement for Kent Highlands Landfill Closure.

  4. City of Seattle Engineering Department Solid Waste Utility, 1989, Kent Highlands Landfill Closure and RI/FS, Preliminary Phase 1 Remedial Investigation Data Report.

  5. City of Seattle Engineering Department Solid Waste Utility, 1991, Kent Highlands Landfill Closure and RI/FS draft Remedial Investigation Report, Vol. I,II,III.

  6. CH2M HILL, Inc., 1989, Draft Kent Highlands Landfill Phase I Remedial Investigation Ambient Air Investigation Work Plan.

  7. CH2M Hill, Inc., 1991, Final Remedial Investigation Report for the Kent Highlands Landfill.

  8. Seattle Engineering Department Solid Waste Utility, June 1992, Executive Summary to the Final Kent Highlands Landfill Closure Action Report.

  9. Washington State Department of Ecology, October 1992, Draft Cleanup Action Plan.

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