COULD ENHANCED ROCK WEATHERING SEQUESTER CO2 AND REDUCE THE HAZARD OF NATURALLY OCCURRING ASBESTOS DOWNSTREAM OF THE SWIFT CREEK LANDSLIDE (WHATCOM COUNTY WA)?

The Swift Creek Landslide is an active, slow-moving, deep-seated landslide in altered ultramafic rocks of Sumas Mountain in Whatcom County, Washington. Previous workers have estimated that the landslide deposits approximately 120,000 cubic yards of sediment annually into Swift Creek. Other prior work estimates that up to 50% of the suspended sediment introduced into the creek is chrysotile, a naturally occurring asbestos, posing a significant threat to the nearby community. Separately, Washington State’s commitment to reducing greenhouse gas emissions motivates investigation strategies sequester CO2 from the atmosphere or point sources, including enhanced rock weathering (ERW) of ultramafic and mafic rock to produce carbonate minerals. Typically, ERW requires mining and milling to produce fine sediment to provide surface area for the weathering reactions which remove CO2 from the atmosphere. These mining activities reduce the net sequestration potential of ERW. At the Swift Creek Landslide, very fine ultramafic sediments are naturally produced. This study aims to explore the potential utilization of sediment from the Swift Creek Landslide for geologic carbon sequestration. We model the weathering of chrysotile under a range of conditions to examine the potential annual sequestration capacity of SCL sediments. The approach presents a prospective strategy for mitigation of the asbestos hazard while concurrently addressing the pressing issue of climate change.