Newcastle Coal Creek Landfill

 The Newcastle Coal Creek Landfill is a closed landfill located within the Newcastle Golf Club property (the Property) in the City of Newcastle, King County, Washington. The Property consists of approximately 350 acres. Among it, 70 acres were permitted for demolition landfill and 137 acres were permitted for grading and clean earth disposal.

The Property and its surrounding area were historically mined for coal from the late 19th century. Landfilling began in the old mine pits left vacant after mine closure. Palmer Coking Coal Company operated the landfill as a permitted demolition waste disposal site from 1970 until it was purchased by Coal Creek Development Corporation in 1985. The landfill stopped receiving demolition waste in 1992 and it was formally closed in June 1993.

Newcastle Golf purchased the Property in 1994. Since then, the property has been developed and operated as a golf course, and its surrounding vicinity has been developed for residential use.

The landfill was closed in June 1993. Remedial actions were conducted under the Prospective Purchaser Consent Decree (PPCD) during construction of those portions of the golf club overlying the closed landfill. A minimum of 1 foot of soil cover was provided according to the site closure plan. Areas with slopes less than 6 percent were lined with synthetic liner. All unlined areas were sloped to greater than 6% to promote runoff and reduce infiltration. Fairways, greens and tees were constructed to collect runoff. The golf course has been operated according to the King County Golf Course Design and Operations Best Management Practices Manual. Irrigation is based on computer assisted decision making. Routine inspections have been conducted by the golf club, including checking for seeps following significant rainfall events. If seeps are detected, corrective actions are taken.

Leachate from the landfill is directed to a manhole located in the parking lot next to the golf course entrance. Leachate is treated with chlorine and discharged to the King County Metro sewer system.

Ecology performed a Site Hazard Assessment of the landfill in 1992. No release of contaminants from the landfill to ground water or to surface waters was confirmed. However, since hazardous materials were documented to have been disposed of at the Site in the 1960s, the landfill was ranked 5 out of 5 on its priority list for cleanup. Rank 5 sites have the lowest priority for Ecology action. 

Ecology and Newcastle Golf entered into a Prospective Purchaser Consent Decree (PPCD) 95-2-26414-0SEA in 1995. The purpose was to resolve the potential liability of Newcastle Golf for any historical contamination associated with the landfill, to promote the public interest by expediting cleanup activities at the landfill, and to facilitate the reuse of a closed demolition waste landfill. 

Ecology issued a Certificate of Completion of Remedial Actions on August 29, 2000 to certify that all remedial actions required under the PPCD were completed. However, all activities required to operate and maintain the integrity of the remedial actions are to continue. A post-closure monitoring program was initiated in July 1993 under the oversight of Public Health – Seattle & King County (PHSKC). Per the solid waste permit issued by PHSKC, the post-closure plan shall be implemented for a minimum of 30 years after the completion of final closure and may be extended as necessary.  Monitoring has included surface water, ground water, landfill gas and landfill seeps. 

A periodic review is conducted every five years following a cleanup action when institutional controls are used as part of the remedy, as required by the Model Toxics Control Act (MTCA). The purpose of the periodic review is to evaluate current site conditions and to ensure continued protection of human health and the environment.

The Environmental Covenant restricts ground water for any domestic purposes from any well within 1,000 feet of the landfill boundary. At least one domestic well within 1,000 feet of the landfill boundary was identified by Ecology. A more thorough search by the landfill property owner is needed to identify all potential domestic wells within 1,000 feet of the landfill boundary. Property owners with domestic wells within 1,000 feet of the landfill boundary will need to be contacted by the landfill property owner to determine the status of the well and to evaluate potential drinking water quality issues. A well inventory report should be submitted to Ecology prior to the next periodic review to determinate if the remedy is still protective of human health and the environment. Additional details can be found in the 2019 Periodic Review report.