Recently, cement kiln dust (CKD) fill was placed in part of the mine. Testing identified high pH seeps and surface water.

Shannon & Wilson provided permitting services associated with King County Department of Health and the Department of Ecology. We assessed the proposed landfill operations, and developed standards of procedure to maintain permit compliance. Our work also included reviewing permit conditions, developing site conceptual and groundwater/surface water models, developing a process flow chart for use in acceptance of inert waste, and developing treatment schemes to allow acceptance of high pH and/or organic-rich material.

Shannon & Wilson also conducted a wetland delineation to better understand impact and remedial approaches associated with the elevated pH, performed site investigations to delineate the extent of impacts in groundwater, surface water and sediment. We developed preliminary plans for remediation of the site; and prepared work plans for focused groundwater investigations to finalize remedial plans associated with the high pH, lead and arsenic impacted water and sediment.