Washington State Department of Ecology - October 9, 2013

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Cleanup proposed for southeast King County coal mine

BELLEVUE – The Washington Department of Ecology (Ecology) seeks public comment on a proposed cleanup plan and legal agreement for a former southeast King County coal mine, once used as a waste disposal site.

While no contaminants have been detected in more than 20 years of ongoing groundwater testing, the responsible companies would permanently cover and confine the northern portion of the mine, the only area known to have received wastes. They also would permanently monitor groundwater, and have treatment contingencies ready should groundwater contamination be detected.

The Landsburg Mine site is east of Maple Valley, near Ravensdale.

Ecology seeks public comment through Nov. 12, 2013, on whether to approve:

Ecology will hold an informational public meeting on Oct. 24, 2013, at Tahoma Junior High School, 25600 Southeast Summit-Landsburg Road in Ravensdale. An open house will begin at 6:30 p.m., and a presentation will start at 7 p.m. Ecology staff and others will be available to answer questions about the site.

The proposed plan and related documents are available for review at:

Comments should be sent to Jerome Cruz, Ecology site manager:

During the late 1960s and late 70s, several companies deposited an estimated 4,500 steel barrels and 200,000 gallons of oily waste water and sludge in part of a hilltop depression that resulted from coal mining. Coal extraction in this section of the Landsburg mine ended in the late 1960s. The rest of the mine closed in 1975.

Samples taken from recovered drums indicate that the contents were organic and inorganic industrial waste, including paint waste, polychlorinated biphenyls (PCBs), solvents, cyanide, metals, and oily sludge. A portion of the waste may have burned during fires in the early 1970s. The site also received construction and land-clearing debris until the early 1980s.

Under Ecology’s oversight, some of the group of six responsible companies have investigated the mine and surrounding area for possible contamination. In more than 20 years of testing, 11 monitoring wells ranging from 13 to 700 feet deep have detected no contamination. Samples are collected twice every year.

Under the cleanup plan, these wells would remain in place, with four more to be installed. The northern half of the trench-like depression would be filled with clean material, shaped to shed rain, and covered with a non-permeable material to reduce the inflow of water to the site.

Should the monitoring network detect groundwater contamination in the future, a system would pump and treat contaminated groundwater and prevent it from moving off the former mine site. Parts of this infrastructure have already been constructed as interim work, approved by Ecology.

The group of responsible companies also will establish a financial trust to permanently continue groundwater monitoring.

A permanent environmental covenant would restrict access and land use on the property. This would prevent public exposure risks, and safeguard the monitoring system and any cleanup work from interference.

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Media Contacts:

 Larry Altose, Ecology communications, 425-649-7009, larry.altose@ecy.wa.gov; @ecyseattle
 Jerome Cruz, Ecology site manager, 425-649- 7094, jerome.cruz@ecy.wa.gov

For more information:

Landsburg Mine Consent Decree (https://fortress.wa.gov/ecy/gsp/Sitepage.aspx?csid=60)

Video: Landsburg Mine Site (on YouTube)

Ecology’s social media (www.ecy.wa.gov/about/newmedia.html)