Wheeler Landslides and Google Earth Images A Photo Essay

Transcription

1 WHEELER CITIZENS FOR RESPONSIBLE DEVELOPMENT NEWSLETTER October 2014 By Ralph Thomas, P.E. (retired) Wheeler Landslides and Google Earth Images A Photo Essay Because of size of file, which is limited to 1 Mb on BBQ, we have had to break this newsletter into three parts the images, consultant s reports, and the commentary. We hope you will read them together. Key Plan Do not scale! Locations of the Brunner and 3 rd Street Landslide Image 1: The Fishery Point Landslide Could this happen in Wheeler? Wheeler CRD Newsletter FINAL Page 1 October 2014

2 Image 2: the Fishery Point Landslide Location related to Wheeler In the image above, the Fishery Point slide is on the extreme left, within a mile of Paradise Cove and Wheeler. Image 3: A portion of the Wheeler drainage and Wheeler s Watershed Wheeler CRD Newsletter FINAL Page 2 October 2014

3 Image 4: Wheeler s Gervais Reservoir Image 5: 3 rd Street Slide (Looking South) Wheeler CRD Newsletter FINAL Page 3 October 2014

4 Image 6: Pictorial from Hydro-Geo-Engineering of Brunner Landslide Image 7: Pictorial from PSI Geological Report on 3 rd Street Landslide Wheeler CRD Newsletter FINAL Page 4 October 2014

5 FORWARD This is the third newsletter in a series that deals with Wheeler and coastal landslides, forestry practices, and local politics as small coastal towns and communities struggle with State Agencies against logging and aerial spraying in their watersheds. The previous newsletters dealt with the Ross Report, which is the only definitive background report for the whole of Wheeler and the Oso Landslide and Geer Report which provides pertinent information on the disastrous Oso landslide and the legal issues now evolving. These are the previous issues in the series: May 2014 Ross Report and Wheeler and Coastal Geology August 2014 OSO LANDSLIDE, LOGGING, AND GEER REPORT The May issue introduced SLIDO, the Statewide Landslide Information Database [2] and touched upon recent information regarding the relationship between logging and landslides. It also introduced the Wheeler Comprehensive Plan Background Data Report. (If your town is in the north coast area, your Comprehensive Plan Background Data Report may include a geologists report prepared by Martin Ross). And critically, we introduced the subject of Technical Overreach, which we will pursue in this and other issues. [5] The August issue also looked at the GEER report on the causes of the Oso landslide. [1] The report is critically important for a number of reasons. One is that it gives credence to the geologist s opinion that logging contributes to landslides. We also looked at recent news accounts regarding pending litigation between the victims of the slide and Snohomish County, who issued building permits in the slide area, even after reports had warned of the dangers. In this issue, we are going to build upon this information and look at two of the active landslides within Wheeler and try to orient people to where these slides are, and give some information from the geological reports pertaining to these slides. THE GOOGLE EARTH IMAGES and CONSULTANTS REPORTS Note that each Google image, unless it s been cropped, has the image date in the lower righthand corner. These images were all taken in July of 2012 and much logging has occurred since then. One caution: two dimensional imagery can be misleading since a steep slope can look flat or area that has been bulldozed flat can be imagined to be a landslide. Key Plan: The information on the location and extent of the slides is taken from the geologist s reports pictorials shown in Image 7 and 8. This is a sketch prepared by us which relied upon the information in these reports. Do not scale this image or rely upon it for any purpose other than a general orientation. Rely upon the information in the geologists report provided in the supplement to this newsletter. Image 1: The Fishery Point Landslide. Many residents in Wheeler remember this slide. It was not small and took weeks to remove the debris. The close proximity to Wheeler is alarming. It should prompt the question why isn t Wheeler doing all it can to adopt the recommendations of the Ross Report to minimize the risk from landslides? Wheeler CRD Newsletter FINAL Page 5 October 2014

6 Image 2: the Fishery Point Landslide Location related to Wheeler. This is self-explanatory. Image 3: A portion of the Wheeler drainage and Wheeler s Watershed. This view from above Wheeler shows the extent of the logging and clear cutting as of July 6, The logging has continued and the Wheeler watershed is all but denuded. The Geer report indicates a possible link between logging and landslides. Image 4: Wheeler s Gervais Reservoir. For years, this was Wheeler s source of drinking water. It is located outside of the City Urban Growth Boundary, presumably on private land. Note that logging completely surrounds the reservoir. Today, the City of Wheeler s water system consists of a well site and treatment system located off Foss Road, and the City s distribution system. In the image, we think the white area in the right-hand corner is from the logging practices not a landslide. We could be wrong. Image 5: A close look at the 3 rd Street Slide. Note that on the left of the photo the road ends where it washed out. Geologists haven t investigated downhill from the washout and presumably the full extent of the slide is not known. Image 6 and 7: These are pictorials taken from the two geologists reports. Note that these reports are site-specific, meaning that the consultant s investigation did not extend much beyond the site they were investigating. The reports do not extend downhill of 3 rd Street, so we have no information in this critical area as to geologic stability. ***** More About Citizens For Responsible Development Wheeler Citizens for Responsible Development is a grass-roots citizen s coalition dedicated to opposing large-scale development and promoting the kind of development that the vast majority Wheeler citizens want. Past accomplishments include the 2007 Citizens for Responsible Development Petition, and Voters Annexation ballot measure. We now see our mission expanded to a more regional venue, and working with other conservation groups on issues such as dredging and landslide prevention. We work in close association with Oregon Coast Alliance. We are not geologists or practicing engineers. Reach us at wheelercitizens@comcast.net and sign up for our newsletter today. NOTES [1] Geotechnical Extreme Events Reconnaissance, Sponsored by the National Science Foundation, July 22, 2014 The 22 March 2014 Oso Landslide, Snohomish County, Washington w-res.pdf The Geotechnical Extreme Events Reconnaissance, Sponsored by the National Science Foundation, July 22, 2014, is the pre-eminent, in-depth technical geological report that analyzes the OSO slide. Its findings will help determine the results of claims and lawsuits, and could influence technical issues. See Wheeler CRD Newsletter August 2014 for more details. [2] See Wheeler CRD Newsletter, May 2014 for details. The SLIDO (Statewide Landslide Information Layer for Oregon) can be found here: The following quotation is from the SLIDO Background Data Limitation and Project Purpose. Note carefully the emphasis upon pre-disaster mitigation : Wheeler CRD Newsletter FINAL Page 6 October 2014

7 One of the most common and devastating geologic hazards in Oregon is landslides. Average annual repair costs for landslides in Oregon exceed $10 million, and severe winter storm losses can exceed $100 million (Wang, Y., Summers, R. D., and Hofmeister, R. J., 2002, Landslide loss estimation pilot project in Oregon: Oregon Department of Geology and Mineral Industries Open-File Report O-02-05, 23 p.). As population growth continues to expand and development into landslide susceptible terrain occurs, greater losses are likely to result. In order to begin reducing losses from landslides, widespread endeavors are necessary at all community levels from state government to individual family homes. One successful way to reduce losses from landslides is through pre-disaster mitigation, which can be performed at many scales from statewide to local. To begin pre-disaster mitigation, the landslide hazard must be located. Once the hazard is located, the population and infrastructure vulnerable to the hazard can be identified and the risk mitigated. [3] Oregon Department of Geology and Mineral Industries, [4] Dr. Ross received his Phd from the University of Idaho in 1978, about the time frame Wheeler s report was authored by him. [5] SLIDO file name, ODOT2011, Ref ID SL009-Z045-50LN1, Fishery Point Slide, Wheeler CRD Newsletter FINAL Page 7 October 2014