Swift Creek Landslide
Encyclopedia
The Swift Creek Landslide is an active, slow moving landslide
located in western Washington, USA, due east of Everson
on Sumas Mountain
. Asbestos
laden sediment originating from the landslide has recently generated much interest in this area. The reasons why this has created interest is because the landowners are trying to clear this asbestos from the area but the EPA has made the process too costly to even give the material away to other countries who want the minerals. Asbestos is a known carcinogen. EPA sampling has documented asbestos in sediments in Swift Creek and in downstream Sumas River. Average asbestos levels in Swift Creek dredged material exceed the level that, in construction materials, triggers worker safety requirements and material handling and disposal regulations.
Swift Creek Landslide side view from west side
WWU Landscape Observatory
are caused by a number of reasons. One is the geology of the area; layers of loosely consolidated sediments, such as sand, overlay strongly consolidated (less permeable) layers of sediments such as clays. That, in addition to the large amount of precipitation received in Washington state each year, makes for prime landsliding conditions.
Earthquakes are thought to help trigger landslides in the Puget Sound
, as well as things such as logging and wave erosion. The Swift Creek Landslide is thought to be a smaller reactivation of an older and larger landslide in that area; perhaps an earthquake set the older, then static landslide into motion.
The main ingredient in this landslide is Serpentinite
,which is formed from serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle. The asbestos mineral that forms from this serpentinite is chrysotile
.The possible reason why there wasconglomerate bedrock underneath of the serpentinite could be because of the glacial till or delta deposits flowing out of the Cascade mountain range as it was forming millions of years ago. After this or while this was all happening the North American plate and the Pacific Plate were colliding causing uplift that eventually formed Sumas Mountain. As the weathering of this place was happening the landslide started to slip away from the face of the mountain to its current position.
About the time that all this was happening, 45 mya, the Chuckanut Formation
was ceasing to gain deposits and the volcanic activity known as the North Cascades was in its youth. This area was also heavily affected by the Pleistocene
Glaciation. Loose unconsolidated sediment is piled on top of the Chuckanut Formation and is causing a very unstable environment.
This also has an effect on the rate at which this mass is moving. Since there isn't a bond between the conglomerate bedrock and the serpentinite above, the Swift Creek Landslide is moving at a much faster rate.
About 50– 100 feet away from the landslide by a company called great western timber. This could have large effects at which the rate of this landslide moves per year. If you have too much logging the water is going to either sit in the soil, making this mass more likely to move suddenly,with less rainfall, or it could run off and create more and more erosion of these asbestos particles. Also Taking away trees from the surface of the landslide itself would cause the soil to be less and less likely to stay together. Picking up this sediment, you would find that the particles easily crumble in your hands, making them more likely to fall apart in weathering. With logging you have damage of the undergrowth which is also a very important part of holding soil together by protecting the soil from direct rain fall. This could also be called cushioning the fall. Thinning operations to the north and east.
(EPA) commented on the application for a dredge permit, recommending that because of the potential health risks, dredged material at the site no longer be removed as it had been in the past, and that community education be continued to help prevent or minimize ongoing exposures to residents. Previously dredged materials remaining alongside the creek banks were sprayed with an EPA approved "tackifier
" (tinted green) to keep asbestos from blowing off the surface.
There is a growing rift between the government and the people who live near Swift Creek. Soon, the sediment will build up enough causing the river to flood and destroy neighboring roads and properties, but because of the environmental and health risks that the EPA decided would be caused by this asbestos, nothing can be done to stop the flooding, without incurring the cost of safely handling, moving, and storing the material.
Agencies at the local, state, regional and federal level are working together to address the situation, communicating with the public about the health risks while seeking funds and authorities for interim approaches. Naturally occurring asbestos is found in other communities across the United States, and in some counties in California and Virginia is factored into land use planning and permitting. The Sumas Mountain landslide, with the sedimentation and flooding issues combined with the mobility of the asbestos adds to the challenges to this site.
In 2008, EPA collected samples outside some homes where residents had used Swift Creek dredged material to make driveways or pathways. Asbestos levels of up to 6 percent were measured.
In September 2008, Whatcom County Health Department and the Washington Department of Health jointly issued a health advisory regarding Swift Creek.
In 2009, during heavy rains in January, the Sumas River flooded, leaving sediments behind after the floodwaters passed. EPA sampled upland flood deposits, streamside sediments, and water at 14 locations. Sediments contained up to 27% asbestos, and measurements of asbestos in surface water exceeded federal drinking water standards.
That July, Whatcom County Health Department and the Washington Department of Health updated their health advisory to include the northern part of the Sumas River.
Washington Department of Health completed a health consultation http://www.atsdr.cdc.gov/hac/pha/SwiftCreekAsbestos/SwiftCreekAsbestos_2-22-2008.pdf.
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
located in western Washington, USA, due east of Everson
Everson, Washington
Everson is a city in Whatcom County, Washington, United States. The population was 2,481 at the 2010 census.Everson and the nearby city of Nooksack lie near the foothills of the Cascade mountains in Northwest Washington. Located on the banks of the Nooksack River, the businesses support the...
on Sumas Mountain
Sumas Mountain
Sumas Mountain is a mountain located in Whatcom County, Washington, 15 miles northeast of Bellingham and southwest of Vedder Mountain. Located in the Skagit Range the mountain is notable for its high biodiversity and year-round hiking trails. It is sometimes referred to as American Sumas to...
. Asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...
laden sediment originating from the landslide has recently generated much interest in this area. The reasons why this has created interest is because the landowners are trying to clear this asbestos from the area but the EPA has made the process too costly to even give the material away to other countries who want the minerals. Asbestos is a known carcinogen. EPA sampling has documented asbestos in sediments in Swift Creek and in downstream Sumas River. Average asbestos levels in Swift Creek dredged material exceed the level that, in construction materials, triggers worker safety requirements and material handling and disposal regulations.
Swift Creek Landslide side view from west side
WWU Landscape Observatory
Cause
Landslides in the Pacific NorthwestPacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
are caused by a number of reasons. One is the geology of the area; layers of loosely consolidated sediments, such as sand, overlay strongly consolidated (less permeable) layers of sediments such as clays. That, in addition to the large amount of precipitation received in Washington state each year, makes for prime landsliding conditions.
Earthquakes are thought to help trigger landslides in the Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
, as well as things such as logging and wave erosion. The Swift Creek Landslide is thought to be a smaller reactivation of an older and larger landslide in that area; perhaps an earthquake set the older, then static landslide into motion.
Dynamics
This landslide is roughly half a kilometer in width, and 1.5 kilometers long. The depth of the landslide is approximately 100 meters. The velocity of the landslide varies, but the fastest moving part is at the toe, which moves upwards of 10 meters annually. There is a lack of vegetation on the toe of the landslide because it is over steepened and constantly sliding, providing no stable area for trees to grow. The trees that are growing on the sides and front of the landslide are tilted and disturbed due to the constant motion of the land. However, there is a section of trees in the middle of the slide that are not disturbed and seem to be moving as a connected unit riding on top of the sliding ground. At the head of the landslide, there is pronounced scarping, and on the sides of the slide, there is transform faulting. At about the middle of the slide you can see where, just above the topples of the slide, the trees are moving in motion with the landslide. The soil under the trees is compact; however, just away from the outside of the root ball you can see cracks, which is an indicator of how fast this landslide is moving. If this landslide was moving slowly the rain fall would move this soft sediment into the cracks and fill them. We visited this site the morning after rainfall and the cracks were pronounced up to 1 cm in width.The main ingredient in this landslide is Serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
,which is formed from serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle. The asbestos mineral that forms from this serpentinite is chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...
.The possible reason why there wasconglomerate bedrock underneath of the serpentinite could be because of the glacial till or delta deposits flowing out of the Cascade mountain range as it was forming millions of years ago. After this or while this was all happening the North American plate and the Pacific Plate were colliding causing uplift that eventually formed Sumas Mountain. As the weathering of this place was happening the landslide started to slip away from the face of the mountain to its current position.
About the time that all this was happening, 45 mya, the Chuckanut Formation
Chuckanut Formation
The Chuckanut Formation in northwestern Washington , its extension in southwestern British Columbia , and various related formations in central Washington are fluvial sedimentary formations of Eocene age, deposited from about 54 Ma The Chuckanut Formation in northwestern Washington (named after...
was ceasing to gain deposits and the volcanic activity known as the North Cascades was in its youth. This area was also heavily affected by the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
Glaciation. Loose unconsolidated sediment is piled on top of the Chuckanut Formation and is causing a very unstable environment.
This also has an effect on the rate at which this mass is moving. Since there isn't a bond between the conglomerate bedrock and the serpentinite above, the Swift Creek Landslide is moving at a much faster rate.
Logging at Swift Creek
It is not known what caused the landslide to reactivate. Sumas Mountain had not been logged as of 1924, but it is speculated that the 1930s was an unusually wet decade. Washington Department of Natural Resources reviews applications for logging on state lands and is aware of concerns that logging in the Swift Creek watershed could worsen slide conditions on Sumas Mountain. The majority of the slide is on privately owned lands.About 50– 100 feet away from the landslide by a company called great western timber. This could have large effects at which the rate of this landslide moves per year. If you have too much logging the water is going to either sit in the soil, making this mass more likely to move suddenly,with less rainfall, or it could run off and create more and more erosion of these asbestos particles. Also Taking away trees from the surface of the landslide itself would cause the soil to be less and less likely to stay together. Picking up this sediment, you would find that the particles easily crumble in your hands, making them more likely to fall apart in weathering. With logging you have damage of the undergrowth which is also a very important part of holding soil together by protecting the soil from direct rain fall. This could also be called cushioning the fall. Thinning operations to the north and east.
Environmental and political implications
Over 120,000 cubic yards (92,000 m³) of sediment from the landslide each year is deposited into Swift Creek. Due to the large amount of sediment being deposited in the creek, dredging was undertaken to prevent the creek from flowing over roads and flooding houses. The sediment collected by dredging the creek was given away free to use for projects such as building housing foundations or to be used as fill. In 2006, EPA samples indicated that the dredged material contains chrysotile asbestos at up to 4%, with an average of 1.7%. The United States Environmental Protection AgencyUnited States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
(EPA) commented on the application for a dredge permit, recommending that because of the potential health risks, dredged material at the site no longer be removed as it had been in the past, and that community education be continued to help prevent or minimize ongoing exposures to residents. Previously dredged materials remaining alongside the creek banks were sprayed with an EPA approved "tackifier
Tackifier
Tackifiers are chemical compounds used in formulating adhesives to increase the tack, the stickiness of the surface of the adhesive. They are usually low-molecular weight compounds with high glass transition temperature...
" (tinted green) to keep asbestos from blowing off the surface.
There is a growing rift between the government and the people who live near Swift Creek. Soon, the sediment will build up enough causing the river to flood and destroy neighboring roads and properties, but because of the environmental and health risks that the EPA decided would be caused by this asbestos, nothing can be done to stop the flooding, without incurring the cost of safely handling, moving, and storing the material.
Agencies at the local, state, regional and federal level are working together to address the situation, communicating with the public about the health risks while seeking funds and authorities for interim approaches. Naturally occurring asbestos is found in other communities across the United States, and in some counties in California and Virginia is factored into land use planning and permitting. The Sumas Mountain landslide, with the sedimentation and flooding issues combined with the mobility of the asbestos adds to the challenges to this site.
Human Health Concerns
In August 2006, EPA completed a report on activity-based sampling (ABS) for Swift Creek dredged materials. The ABS measures the amount of asbestos in the breathing zone of personnel (with respiratory protection) performing routine activities, such as raking, running or biking, and digging/loading. Using these data, EPA estimated cancer risks for adults and children doing the same or similar activities for a given duration and frequency. These risks were, in some cases, greater than 1 in 10,000, a level considered by many health agencies to warrant concern and regulatory action.In 2008, EPA collected samples outside some homes where residents had used Swift Creek dredged material to make driveways or pathways. Asbestos levels of up to 6 percent were measured.
In September 2008, Whatcom County Health Department and the Washington Department of Health jointly issued a health advisory regarding Swift Creek.
In 2009, during heavy rains in January, the Sumas River flooded, leaving sediments behind after the floodwaters passed. EPA sampled upland flood deposits, streamside sediments, and water at 14 locations. Sediments contained up to 27% asbestos, and measurements of asbestos in surface water exceeded federal drinking water standards.
That July, Whatcom County Health Department and the Washington Department of Health updated their health advisory to include the northern part of the Sumas River.
Washington Department of Health completed a health consultation http://www.atsdr.cdc.gov/hac/pha/SwiftCreekAsbestos/SwiftCreekAsbestos_2-22-2008.pdf.