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SDAG Monthly Meeting
Wednesday, May 17, 2017

Location: Geocon Incorporated - Upstairs Lounge
6960 Flanders Dr
San Diego, CA 92121
Tel: (858) 558-6900

FROM INTERSTATE 805: Take the Mira Mesa Blvd (Exit 27) exit. Head east on Mira Mesa Blvd for roughly 2 miles. Turn right onto Flanders Drive and Geocon will be on your left in about 0.4 miles.

FROM HIGHWAY 15: Take the Mira Mesa Blvd (Exit 16) exit. Head west on Mira Mesa Blvd for roughly 3.3 miles. Turn left on Camino Santa Fe and then turn right on Flanders Drive. Geocon will be on your right in about 0.2 miles.

happy hour
5:30pm -
Social hour  

Menu: Mexican Buffet (The Tacoman), Walawender Tavern (Beer & Wine)
*Geocon will be checking all student ID's. No alcohol can be served to anyone under the age of 21*
6:15pm -

Cost: $35.00 for non-members, $30.00 for members, $15.00 for students. if pre-registered by the deadline, $5 extra if you did not make a reservation. Click the SDAG member checkbox on the reservation form if you are a member.

Reservations: Make your reservation online by clicking the button below no later than NOON, Monday, May 15. RESERVATIONS CANNOT BE ACCEPTED AFTER Monday at noon. Late reservations/cancellations are preferred over walk-ins or no-shows. Fees payable at the meeting or pre-pay with PayPal.
As a new payment option, there will be a phone credit card reader at the meeting.

If you are a current SDAG member and are not getting e-mail announcements,
make sure the SDAG secretary has your correct e-mail address.

7:00pm -

Speaker: John Wallace & Pat Shires

"Inadequate Characterization and Subsequent Inappropriate Landslide Repair Leads to Complex Massive Destabilization of a Residential Hillside in Santa Barbara, CA: How Can This Happen in This Day and Age and How Do You Fix It?"

Abstract: In the winter of 1998, a relatively small, slow-moving landslide mobilized near the base of a residential hillside in Santa Barbara California, and by the summer of 1999, it had destroyed one home and threatened closure of a state highway. The landslide was approximately 350 feet in length, 250 feet in width, and averaged approximately 40 feet in depth. A very limited investigation of the landslide was undertaken by a state agency and slope mitigation was completed by 2001, which consisted of removing nearly 130,000 cubic yards of earth material from the base of the hillside. The landslide investigation included no geologic mapping, no survey control of the topographic surface, only two small-diameter borings within the landslide, no piezometers, and no laboratory testing of the basal slide surface. Two inclinometers were installed in the landslide, both showing discrete shear offsets; however, only one of the offsets was utilized for controlling the basal slide geometry. Back-calculated strengths of the assumed slide surface were generated, which included a significant component of cohesion. These erroneous strengths were then applied to a forward analysis of the proposed graded slope repair. The forward analysis was performed using circular searches for the weakest basal surfaces, even though the entire hillside is composed of tertiary bedrock materials, not soil, and the searches were limited only to the area of the graded repair. These analyses still did not achieve factors of safety of 1.5. Furthermore, the as-built graded landslide repair resulted in steeper slopes than those that were analyzed.

During the landslide repair grading operations, signs of earth movement were apparent immediately, as cracks were observed on the freshly graded slope. Seven inclinometers and piezometers were then installed following the slope mitigation (nearly double the number installed for characterization of the landslide), but were not monitored for nearly 1.5 years after their installation, despite the early signs of slope movement. When the inclinometers were finally monitored in late 2002, several inches of movement could be seen in the inclinometer plots; however, in at least one case, the technician responsible for collecting the readings misinterpreted the data and performed bias corrections on the data set, effectively eliminating the early warning signs of impending movement. By the spring of 2005, an approximately 800-foot long by 450-foot wide, and up to 100-foot deep rock block slide was evident, and began accelerating to several inches per day. An active toppling zone in the upper portion of the slide was failing along near-vertical bedding of the Rincon Shale and into the void left by the block slide, resulting in an enlarging zone of instability.

By the fall of 2005, three multi-million dollar homes were destroyed along this hillside, 4 others were severely distressed, a state highway was closed, and access was still threatened to nearly 70 other homes. Systematic procedural, technical and communication breakdowns characterize just about every phase of this investigation, with the outcome directly responsible for tens of millions of dollars in damages: prompting the question: how can this happen in this day and age?

Mitigation of this huge and complex slope failure was no easy task. After obtaining funding through settlement of litigation, and comprehensive investigation and careful analyses, it was decided to effect a "top down" mitigation effort whereby the upper reaches where homes were immediately threatened was stabilized first with subsequent mitigation efforts marching down the hillside until the entire hillside was stabilized. The cost of the landslide stabilization effort exceeded $50,000,000 and took several years to implement.

John Wallace is a Principle Engineering Geologist with Cotton, Shires and Associates, Inc. (CSA), a full-service geotechnical engineering and engineering geologic consulting firm recognized nationally and internationally for its landslide expertise, having specialized in the identification, characterization, analysis and mitigation of slope instability for over 35 years. John Wallace is a Certified Engineering Geologist in California with 29 years of professional experience. Mr. Wallace has a Bachelor of Science degree in Geology from the University of Southern California and a Master of Science Degree in Geology from San Jose State University. Mr. Wallace's primary responsibilities with respect to landslide investigations are to accurately identify and characterize the landslide type, three-dimensional limits, and earth material characteristics, and to work closely with the geotechnical and civil engineers in the design of mitigation elements. Mr. Wallace recently participated in, and presented technical papers at, the 13th International Conference and Field Trip on Landslides in Japan, the 1st and 2nd North American Landslide Conferences in Vail Colorado and Banff, Alberta, Canada in 2007 and 2012, and the American Rock Mechanics Association, 47th and 49th U.S. Rock Mechanics Symposia in San Francisco.

In his spare time, Mr. Wallace enjoys water skiing, snow skiing and snow-boarding, is the father of twin 14-year olds, and is also an avid windsurfer and racquetball player.

Patrick Shires is a Principal Civil and Geotechnical Engineer and Geophysicist with Cotton, Shires and Associates, Inc. (CSA), a full-service geotechnical engineering and engineering geologic consulting firm recognized nationally and internationally for its landslide expertise, having specialized in the identification, characterization, analysis and mitigation of slope instability for over 43 years. Patrick Shires is a Registered Civil Engineer, Geotechnical Engineer and Geophysicist in California with over 45 years of professional experience in California, the United States and internationally. Mr. Shires has Bachelor of Science and Master of Science degrees in Civil Engineering, specializing in geotechnical engineering and geophysics, from Stanford University. Mr. Shires' primary responsibilities with respect to landslide investigations are to analyze slope stability and to formulate mitigation designs, and to work closely with engineering geologists in the design of appropriate mitigation elements. Mr. Shires was retained by the Peoples Republic of China to study landslides impacted by the Three Gorges Dam project in China and has participated in and presented at international field workshops on landslides in Japan (twice), Australia, New Zealand, Switzerland (twice), Austria, Italy, Czech Republic, Slovak Republic, Spain, England and Norway. He has designed hundreds of landslide repair projects from small-scale projects to repairs exceeding $50,000,000 in construction costs and has testified as an expert witness in over 88 trials.

In his spare time, Mr. Shires enjoys cattle ranching, tending vineyards, hiking, fixing things (old cars, tractors, trailers, etc.) and building things (barn, tiny house and outdoor furniture).

Upcoming SDAG meetings - 2017

June 21: Jorge Ledesma Baja California, Mexico

July: Joint Meeting with South Coast

August 9 (2nd Wednesday): Society of Military Engineers

Meetings are usually scheduled for the 3rd Wednesday evening of the month. Meeting information on this website is normally updated the second week of the month.

If you have any information, announcements, ads or suggestions for an upcoming newsletter, please submit it to Ken Haase, (2017 SDAG Secretary). Any news regarding upcoming events that may be of interest to the Association or news of your business can be submitted. The submittal deadline for the next SDAG newsletter is the last Friday of the month.
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