Saturday, May 29, 2010

A Patch Over Bellingham's Void

Pavement patch on East Holly Street

Coal was discovered adjacent to Bellingham Bay in the early 1850s. The discoveries were very fortuitous as the coal could be loaded directly onto ships for transit to centers of demand. Bellingham had at least three coal mines adjacent to the bay. If there ever was any documentation of the first mine it has remained undiscovered and for many years it was assumed the mine entailed simply a minor amount of surface mining. However, the old mine was rediscovered during a construction project near the shore in south Bellingham in the early 1990s. The shaft was filled with gravel after discovery and was described to me as being a steep audit that was approximately 80 feet deep. The second mine had a longer life with workings extending beneath what was then the small town of Sehome. The mine operated from the 1850s through the early 1870s.

Schooner and coal loading facility, Bellingham Bay.

Coal loading facility on Bellingham Bay

This second mine has presented a bit of a problem because of the risk of collapse. The downtown area of Bellingham later developed over a portion of the area mined. Several collapses of portions of the mine were reported in the 1880s and very early 1900s along Railroad Avenue and there were reports of holes between North State Street and Railroad Avenue as recently as the 1970s. A hole was reportedly filled at the corner of Railroad Avenue and Holly Street in 1888.

In the early 1990s the Mason Building, one of the largest buildings in downtown Bellingham burned. The entire interior burned leaving a precarious skeleton of steel and masonry. The structure was torn down and a chain link fence enclosed the basement foundation. This blight on Bellingham’s downtown landscape was referred to as The Pit. The Pit gained considerable notoriety in Bellingham. The Pit stood at the most important downtown intersection in the city. After no apparent action from the land owner to do anything with the site the City of Bellingham began condemnation proceedings ultimately buying the property.

This is where the patch in the pavement comes in. The company I worked for at the time was hired to assess the property for potential contamination and geotechnical issues. We were aware of the possibility of a mine under the site but various maps had the mine located at different places. Tim Walsh and Robert Logan (1989) had estimated the mine location based on old mine reports and an assumed shaft entrance. The structural engineering company we were working with had a map that was similar to Walsh and Logan but with a sharper turn to the trend of the mine as I recall it. Tetra Tech (1984) had the mine under the site at a depth of 300 feet. We proposed using an auger drill rig to drill to bedrock and then switch to mud rotary with a few change outs to obtain rock cores. I had the pleasure of overseeing this operation and really enjoyed the reaction of people had to mud drilling at the busiest intersection in Bellingham.

Walsh and Logan (1989) showing two of the mines underlying
Bellingham with the downtown area on the lower right. 
A much bigger mine underlies the northwest portion of the city. 

One of the best parts was that we did rock coring at a few intervals. This entailed pulling out the rotary drill bit and then stringing the core tool down the boring. I did not have a lot to do while the drillers did the work of changing out the drill tool so I crossed the street and had eggs, hash browns, and coffee while watching the drillers from through the window. After a couple of rock coring runs we did continuous mud drilling with a goal of reaching the coal seam. The returning mud was light brown but at 110 feet it suddenly turned black and just as suddenly all drained down the bore hole. We had found the void! The next day we preformed the same operation around the corner on Railroad Avenue. This time the same thing happened at 88 feet.

Ultimately we did lots of research to come up with an approach to estimate the potential settlement if the void collapsed and the collapse worked its way to the surface; not very good news for the structural engineers. Additional drilling was done using continuous rock coring methods, but by then I had left the company. The continuous coring was done to the south and west and found the coal seam but no voids. This means that retreat mining was not done and the scale of collapses and risks posed are significantly less than if all the coal had been taken. All said it appears that Walsh and Logan (1989) had very closely located the mine and mine orientation on their map though very good research.

Today the building that replaced The Pit is at the center of an area that has seen redevelopment. Other development has taken place over the mine in the past few years and it has been interesting to see how seriously various geotechnical consultants and for that matter the City of Bellingham take the issue. I am aware that drilling has taken place on some of the sites but not on others and I am also aware of one building that was redeveloped that likely had been impacted by mine subsidence.
The former Pit, now offices and Starbucks

An additional segment of The Pit is worth mentioning. Once the City began moving towards funding the building project, a number of citizens demanded that The Pit be turned into a park versus being developed. Lots of passionate protesting ensued including at the City Council meetings. Protesters were arrested, but one the most infamous protester who went by the name Raptor was never arrested. He was never identified and from all appearances drove the police nuts. Three arrested protesters were tried at least in part because they wouldn’t give up Raptor’s true identity. One of the joys of living in a small city is that one can get to know a lot of the personalities involved. The defense attorney was a friend of mine, and I knew a couple of the protesters, the lead detective and a couple of the jurors as well as numerous witnesses. There was a three day trial that ended with a hung jury.

So every time I see the fading patches in the pavement of Holly Street and Railroad Avenue it brings back fond memories of a mud rig on one of Bellingham’s busiest street, a great breakfast at the Little Cheerful and finding the void under downtown Bellingham. But unknowns still remain; I never did find out the identity of Raptor.

Friday, May 28, 2010

Attabad landslide and Dave's Landslide Blog

Attabad landslide will likely be over topped today. NASA has a great image of the lake formed by the landslide in northern Pakistan and how the lake has grown over the past month and a half. The red areas are farm fields in this infrared image. Farming takes place on the alluvial fans and terraces along the sides of the valley. The white areas are snow and on the right portion of the image are two valley glaciers extending down to the edge of the farming area. In the upper left of the image the farm fields have been cut by the landslide. The people living there lost everything they owned when the slide took place in January.
When I'm in my office and not too pressed with report writing (like most of this week) I routinely check a few web pages as a means of self educating. One that has been a great service to my education is Dave Petley's Dave's Landslide Blog . He's been providing great updates on the Attabad Slide since the slide took place in January. Whenever I come across any interesting slides and do a little research on line his site inevitably comes up. He really has created a great community of landslide followers. A couple of weeks ago a geologist I know mentioned he had seen a comment I posted on Dave's blog. And folks from all over the world send him alerts about landslides that he then posts. Some of the slides are very humbling and given that I routinely am assessing geologic risk its a good thing to stay humble and think through all the possibilities.

Monday, May 24, 2010

Mount Rainier Lahar Hazard Map

With the 30th anniversary of the eruption of Mount Saint Helens in southern Washington our Washington State volcanoes as well as other volcanoes are getting some attention. Mount Rainier gets the most and for good reason. I came across this map of the lahar hazard for Mount Rainier prepared by the United States Geological Survey.

Rainier is a big mountain and mudflows from Rainier have deeply buried the downstream valleys in the past. Crandell and Waldron initially recognized the massive mud deposits from Mt. Rainier in 1956. These deposits had initially been mapped as glacial till. Dragovich, Pringle and Walsh (1994) subsequently used well and geotechnical borings an determined that the mud flows traveled as much as 62 miles and the mudflow combined with post mudflow sedimentation played a major role in filling in an arm of Puget Sound now occupied by Puyallup, Auburn, Sumner, Kent and Fife.

I am used to seeing Mount Baker’s summit rising above the Nooksack and Skagit Valleys in northwest Washington. But the view of Rainier from Orting is awesome looking in more ways than one.

Sunday, May 23, 2010

May is Rhody Time

Most of western Washington is covered by forest and as such micro climates do not stand out as much as places like coastal California. Nearly all of western Washington gets enough rain and is cool enough to support forests. Even area areas that get less than 20 inches of rain are still typically tree covered. A few steep exposed slopes in the drier areas will be free of trees.

The forest understory is a different matter. As a geologist passing through the understory of the forest I have developed a pretty good sense of the different understory plant communities. But it is more than rain fall totals that define where plants grow. The underlying geology can make a big difference as well. Silty or clayey soils hold a lot more water and that is reflected in the types of plants that will grow. I have gotten pretty good at predicting the types of soils I will dig into with my shovel by the type of plants I see.

May is the month when rhododendrons bloom in the Washington forest. They always provide a nice surprise particularly since they are common in some of the areas I work. Rhododendrons are not found everywhere. They prefer drier areas and a look at the leathery leaves on this evergreen plant indicates that they are drought tolerant. The rain shadow area of the Olympic Mountains creates a band where they are much more common, but well drained soils seem to help as well. The thickest area I have seen them is in the Quilcene area and on the Toandos Peninsula east of Quilcene. Port Townsend to the north has a festival celebrating the blooms. Quilcene is not dry in regards to total rainfall, but it has been my experience that the area gets a lot warmer than the rest of western Washington during the dry summer months. This is partially hinted at by another plant. The southwest tip of the Toandos Peninsula is called Oak Head. I have been there and Have never observed any oak trees. However, the steep shoreline slope does have a good crop of poison oak. I have also encountered thick poison oak thickets in the Brinnon area.

A companion plant frequently seen with rhododendrons is the evergreen huckleberry. Both plants combined can form nearly impassible thickets. But they both put on a great show in May, the Rhododendrons with their large white to pink blooms and the huckleberries with their new coppery leaves. The huckleberries produce very dark berries in the fall that I nibble on from October till January.

Saturday, May 22, 2010

A Curious Otter

Last Monday I was checking out a large landslide complex on the west shore of the Toandos Peninsula on the shore of Dabob Bay. This was a big slide with most of the steep shoreline bluff failing over a distance of nearly one quarter of a mile. The slide took place in 1998. A month ago I observed a new scarp above the landslide area indicating that the 1998 failure may have caused a very old, large landslide to reactivate. The slide deposit has been eroded back but the presence of logs in the slide debris has slowed the rate of erosion and the failed soil is now covered with red alder. Alders are often the first trees to pioneer disturbed soil and later will get shaded out by evergreens if enough time goes by.

During my walk along the shore I was followed by an otter. There are two otters in our waters: the river otter and the sea otter. River otters are relatively common and the term river causes confusion as these otters are found in all waters. They are also much more common than sea otters and I see them fairly often in various water settings. This otter was very curious about me and followed me a long the shore for about 5 minutes.

Sea otters were nearly hunted to extinction during the 1700s through 1800s. The presence of sea otters along the coast played a big role in the early exploration and settlement of the Washington coast. Sea otter pelts were very lucrative. The pelts were purchased from Indian tribes along the coast, sold in China and then trade goods purchased in China were brought to England. In 1794 the Jenny sailing out of Bristol returned 2,400% on the voyage investment (Bill Gulick, 2005) by trading for sea otter pelts. Unlike other marine mammals sea otters rely on their fur to stay warm and hence have very thick pelts with up to 600,000 hairs per square inch. Hence the furs were highly prized. The sea otter fur trade was well underway before the Alexander Mackenzie and later Lewis and Clark crossed the North American Continent.

The sea otter trade completely changed the political and economic conditions on the Pacific coast. It was a gold rush with a violent history but could not last as the otters were killed off. Initially the otters were shot or trapped by Indians and then sold. By the mid 1800s only the shyest and least accessible sea otter populations remained. One area where a population hung on longer was the kelp beds off of Ocean City, Washington. With the advent of long range, accurate repeating rifles shooting platforms were built out in the kelp beds and the last slaughters began coinciding with the near extinction of the buffalo. A sharp shooter would shoot the otters from hundreds of yards and then a collector would paddle to the otter to collect the skin. The last two otters shot near Ocean City reported fetched $1,400 and $600 in 1906 (Van Syckle, 1982). Sea otters from Alaska were reintroduced to the north Olympic Peninsula Pacific coast in 1969 and 1970 and the population has been slowly recovering with occasional reports of sea otters as far as the San Juan Islands.

Friday, May 21, 2010

Puget Sound 13,980 B.C.

I came across a couple of short films. The first one was put together by Ralf Haugerud and Harvey Greenburg and shows a time lapse map of the Vashon glaciation in Puget Sound. The film can be viewed by clicking HERE

The most fascinating part is the timing of flooding of large areas after the ice retreated. During the ice age sea levels were much lower. The western Washington coastline extended many miles out to the west. Local sea level in Puget Sound at the end of the ice age can be tricky to figure out. As the ice age was ending sea levels were rising due to ice melt. However, the mass of glacial ice in the Puget lowland had depressed the local earth surface downward. There was a delay from the time of ice retreat to full flooding by sea water and then as the land rebounded flooded areas emerged. In the Bellingham area on the northwest portion of the map, local sea level was as much as 600 feet above the current local level. At that time there was significant ice floating on the sea water and as the ice melted it rained silt and clay onto the sea floor below. Much of the low lands of Whatcom County are mantled with this sea floor deposit.

The still picture I saved is of particular interest to me as I do a lot of work on the northwest portion of the Olympic Peninsula. The picture captures the period of time when the ice lobe was still blocking the outlet to the sea and what is now Puget Sound was a fresh water lake called Lake Russel. Just where did the lake drain to the north when the ice retreated? Ralph Haugerud has suggested the Chimacum Valley as being the outlet. My thoughts are that it may be more complicated and the drainage may have taken place in phases, but I do concur that a surge of water went down the Chimacum Valley at some point. The film does show that the ice edge hung up for at least a little while near Port Townsend and that is very consistent with my observations of the deposits in the Port Townsnd area.    

Thursday, May 20, 2010

The Approaching Vortex

I was in the field yesterday with a leery eye on the weather. The low pressure center slid up along the west coast of Washington State yesterday. A bit unusual for this time of year. Went from a warm sunny morning with a great view of Whatcom County's Mount Baker to dark and rain fairly fast for these parts.

Mt. Baker with the Twin Sisters on the right and Lummi Island on left from the southeast shore of Orcas Island

Heading towards Anacortes on the ferry looking southwest. The bright sky is at least in part the rain shadow from the Olympic Mountains

Not a bad work gig on Wednesday. I stayed most dry as the front did not arrive until late and the rain shadow from the Olympic Mountains greatly reduced the rain fall. It is storms like these that shape our landscape. They do some tree trimming as well. Winds of 80 plus miles per hour were reported along the coast.

Thursday, May 13, 2010

The Grassy Knoll - Tacoma's

Tuesday I had a morning meeting in Olympia, Washington. Olympia is about 150 miles south of Bellingham where I live. The route down Interstate-5 passes through Washington State’s most urban landscape and hence sometimes can take a lot longer than the 2.5 hours with no traffic. Hence I left on the early side to give myself plenty of time.

Turns out I encountered no traffic at all so I paid a short visit to Tacoma to fuel the car and visit the Grassy Knoll. In the mid 1990s I spent the better part of a year working at the Tacoma Tar Pits. The Tar Pits were an area of wetlands on what had once been tide flats. The tide flats had been filled and used for a variety of industrial purposes including converting coal to natural gas. The waste product was coal tar. The tar was disposed of by discharging it into the wetlands and other low areas around the site.

Tacoma Tide Flats. The gray/brown plume is silt from the Puyallup River. The silt is from glacial melt water derived from Mount Rainier.
Grassy Knoll on Tacoma Tide Flats. Building in upper left is a new prison.

Most environmental projects are not particularly interesting geologically. But this site had many layers. I developed an entire stratigraphic system for the site that included a variety of formations: Tide Flats, Grass Mat, Plank Roads and Pilings, Smelter Slag, Auto Wrecking Units with sub units of fluff, acid, oil, and coolant, PCP waste oil, Rail Waste, Coal Tar and Hair Tar. The Hair Tar was the waste tar that was used to strip the hair off of hogs. I was not on site when investigators encountered the Blood layer.

One of the jobs I had was the daily oversite of the construction of the Grassy Knoll. Essentially we mined all the contamination mess described above, mixed it with clay and concrete and built the Grassy Knoll. The Grassy Knoll is a new term for the hill that was built. Prior to the grass planting we called the mound that began to rise above the surrounding tide flat industrial area something else that can not be repeated in civil company.

A lot has changed in the tide flat area. New industrial development has come into some of the areas we excavated. Near the city center, a glass museum has been built, the old rail station and other buildings have been fixed up and a new bridge has been constructed over the waterway. The term gentrification could even be used for some of the old buildings. When I worked here most of the windows in these buildings were broken and the neighborhood above the area was considered dangerous.

New cable stay bridge

Fixed up train station

Old flour mill and glass museum

The Grassy Knoll was a small part of the effort to clean up the area. When I think of the stratigraphy under the Grassy Knoll, I think about how much our urban landscapes have changed over time. I hope Tacoma will maintain its character and there will remain people that will defend its honor.

Neco Case has a great song called Tacoma Here

Monday, May 10, 2010

Could a Pakistan-like event happen in Washington State?

As posted on my previous post, a large landslide has blocked a river in northern Pakistan. The slide blocked a critical road that is the only access through this portion of the mountains. The dammed up river is now flooding villages upstream and the risk downstream is substantial as the river rises with the risk of a sudden failure of the landslide dam and subsequent floods.

Washington State has steep mountains that have very steep valleys. Could large mountain landslides happen here? That answer is easy. We have had several of various scales. The most recent was the Naches/Nile River slide in 2009. This slide destroyed several homes, buried a state highway and dammed a river.

In 1964 the Hope Slide blocked Highway 3 in southern British Columbia. Somewhere under the piles of rocks are buried cars where people who were at the wrong place at the wrong time were driving.

The Frank Slide in southwest Alberta killed 70 people, blocked a railroad and buried the entrance of a coal mine with people inside. The miners were able to dig their way out.

Several large landslides have been identified in the steep valleys of northwest Washington. The Church Mountain landslide buried the North Fork of the Nooksack River. The town of Glacier and other home subdivisions are built on top of the landslide debris form that slide. David Tucker provides a field trip guide to the Church Mountain slide at Here as well as a trip to a lake deposit up the Skagit Valley from a slide that dammed the Skagit River Here.

LIDAR images of the mountains in Whatcom County identify numerous mountain size failures. As I posted before Here numerous slides are located on the slope of Sumas Mountain including the active Swift Creek slide on the west side of the mountain described in part in this post Here.

Perhaps the most impressive and most dangerous is the Bonneville slide complex on the Columbia River. The Bridge of the Gods slide that dammed the Columbia River in the Columbia River gorge. This slide was described by native people living in the gorge and it was obvious to Lewis and Clarke that the slide was a recent feature. This slide altered politics on the Columbia River as it blocked passage on the river first as a dam and then as a steep rapids. There is evidence that a massive flood 80 feet above current flood levels took place downstream of the dam when the landslide blockage was breached.

Lewis' map of the slide area.

As can be seen in this Washington State Department of Natural Resources map multiple slides have taken place at the Bonneville site. The current lake is the result of Bonneville Dam, built on the slide deposits. Major power lines, pipelines and highways use this natural corridor. Another slide at this site will have profound impacts on Washington State and Oregon. The fact that the slide is not ancient history causes one pause to think how it impacted people living in the area a few hundred years ago. It had a profound impact then and it will when the slope fails next time.

Friday, May 7, 2010

More Trouble in Pakistan

I do a fair bit of landslide work and so try to stay up with the science. I have been following the developments associated with a very large landslide in northern Pakistan. This slide took place in one of the most rugged landscapes inhabited by humans on the planet. It completely blocked the road between Pakistan and China. Its must be an amazing road to travel as it crosses just in front of huge valley glaciers, crosses very active alluvial fans and the entire valley is hemmed in by huge mountains.

I recently took a look at the satellite imagery accessed via Google and found that a newer high resolution view of the area shows the slide and the lake forming behind the slide. An older view of the river prior to being backed up can be seen on the right of the image. The yellow line is a rough approximation of the road route. The lake has inundated the bridge that formerly crossed the river to the northeast in the image.

The risk now is that the landslide dam will fail suddenly as the water levels behind the dam rise. Geologic evidence downstream indicates this sort of event has happened in the past and there are what appears to be lake terraces up stream from past landslide dammed lakes. Pakistan government has been excavating an emergency spillway to reduce the final height of the lake and reduce the risk of a catastrophic breach of the landslide dam. But this is an emergency effort with very limited time. It has been a heroic effort given the conditions and location. One worker was killed from further rockfalls on the slide. He was not able to hear the crashing boulders that were approaching as he was operating an excavator.

As the spring snow melt begins the lake will fill rapidly. The anticipated date of the dam being over topped is in about two weeks. 

Wednesday, May 5, 2010

Ophiolites and being a Grunt Geologist

I sometimes refer to myself as a grunt geologist. Grunt geologist do not have as much time to pursue geologic observations as much as they would sometimes like. Lately I have been doing a fair bit of small field site visits and I just completed a report that I would once describe as a thesis. I now can describe in detail the aggregate resources in Clallam and Jefferson County. But outside of a narrow self interested group, I would likely put anyone asleep with stories about sand and gravel deposits.

Field work the past two weeks has been damp and chilly. The field work has been followed up with lots of writing including the aggregate study. Below is a view looking north from Fidlago Island to Cypress Island, one of the Jan Juan Islands. I took the picture during a small project assessing a slope on a chilly wet late April afternoon. Cypress is one of the San Juan Islands that is actually not in San Juan County. It is in Skagit County. Most of Cypress is protected as a Natural Resources Conservation Area and as a Natural Area Preserve.  

The shoreline along Fidalgo Island I was traversing involved technical crawling. Lots of sharp boulders covered with very slippery oak leaf seaweed.

The boulders consist of ultamafic rocks of the Fidalgo ophiolite. Ultramafic refers to the fact that these rocks are very high in iron and magnesium content relative to most rocks. An ophiolite is a section ocean crust. These rocks are part of an ocean basement that somehow got thrust up and accreted to the edge of North America. The Fidalgo ophiolite is part of a complex assemblage of rocks making up parts of the San Juan Islands and the Northwest Cascades that is referred to as the San Juan - North Cascades Complex. The complex is well very complicated and not necessarily for the understanding of a grunt geologist like me just trying to figure out if a slope is stable. But it was fun to use the term ophiolite in a report. And I enjoyed observing the mineralogy and layering that only a metamorphic petrologist or a student of deep ocean crust can fully appreciate. And besides I once spent a fair bit of time helping try to sort out some the pieces of the puzzle explaining how these rocks ended up here as a graduate student.