Geosciences

One SHN geologist describes his perspective: “There is no stable.  Mountains grow, become unstable, and fall.  Seemingly solid ground shakes and becomes liquid.  The sea sends tsunamis every few hundred years to drown forests and reconfigure the coastal landscape.  In places like northern California and southern Oregon, we read this geologic story of the landscape and know it is all intimately tied together.  The restless crust beneath our feet shapes the beautiful environment we call home; the locations of mountains and rivers are controlled by faults, and the trees grow as the rocks and soil dictate.”  

SHN geologists are that special subset who bring their sense of awe to contemporary  problems such as finding safe and seismically stable locations for hospitals, schools, and other infrastructure (for example, roads and bridges, water treatment plants, pipelines).  Their projects include landslide evaluations and stabilization design, fault hazard evaluations, resource and watershed studies, geohazard evaluations for power plants, dams, and hydroelectric facilities, and soils engineering assessments.  They make complex geologic issues simple, and develop creative, effective solutions.  SHN geologists are creating new methodologies using new technology, such as high resolution trench photography, which allows more detailed documentation of geologic conditions.

 

Fault investigation and geotechnical characterization for a regional hospital facility

Project Details

Location:  Frank R. Howard Memorial Hospital, Willits, CA

Owner/Client:  Howard Foundation

Partners:  U.S. Geological Survey and Humboldt State University

Project Timeline:  2001 to 2014

Project Details

Location:  Frank R. Howard Memorial Hospital, Willits, CA

Owner/Client:  Howard Foundation

Partners:  U.S. Geological Survey and Humboldt State University

Project Timeline:  2001 to 2014

Project Details

Location:  Frank R. Howard Memorial Hospital, Willits, CA

Owner/Client:  Howard Foundation

Partners:  U.S. Geological Survey and Humboldt State University

Project Timeline:  2001 to 2014

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Project Details

Location:  Frank R. Howard Memorial Hospital, Willits, CA

Owner/Client:  Howard Foundation

Partners:  U.S. Geological Survey and Humboldt State University

Project Timeline:  2001 to 2014

SHN geologists completed an extensive investigation of fault rupture and liquefaction potential for the new Frank R. Howard Memorial Hospital.  The hospital site is associated with a high level of geohazard potential because it is adjacent to the active Maacama fault and is situated on young alluvial deposits subject to liquefaction potential.  Hospitals are defined by the State as “critical structures,” so this investigation was completed to the highest professional standards and requirements, dictated by State and CBC guidelines, and was subject to rigorous State review.  To adequately define rupture potential per State criteria, excavations on the order of 30+ feet were required.  Large benched pits up to 25 feet deep were created, and then a standard fault trench was excavated on the floor of the pit.  Very young alluvial soils were a significant geotechnical concern due to their inherent liquefaction potential, especially when so close to an active seismic source.  State-of-the-industry investigation, materials testing, and computer modeling were completed to define the level of liquefaction hazard.  

We successfully identified a suitable building site, free from past ruptures, despite proximity to the nearby active fault.  The liquefaction potential was mitigated at the site by extensive removal of unsuitable native materials, on-site soil mixing, and replacement as engineered fill.

Humboldt State University Geotechnical Engineering Projects

Project Details

Location:  Arcata, California

Owner/Client:  Humboldt State University

Partners: GR Sundberg, Kernen Construction, Maples Plumbing, O&M Industries, Beacom Construction, and Danco

Project Timeline:  2004 to present

Project Details

Location:  Arcata, California

Owner/Client:  Humboldt State University

Partners: GR Sundberg, Kernen Construction, Maples Plumbing, O&M Industries, Beacom Construction, and Danco

Project Timeline:  2004 to present

Project Details

Location:  Arcata, California

Owner/Client:  Humboldt State University

Partners: GR Sundberg, Kernen Construction, Maples Plumbing, O&M Industries, Beacom Construction, and Danco

Project Timeline:  2004 to present

Project Details

Location:  Arcata, California

Owner/Client:  Humboldt State University

Partners: GR Sundberg, Kernen Construction, Maples Plumbing, O&M Industries, Beacom Construction, and Danco

Project Timeline:  2004 to present

Project Details

Location:  Arcata, California

Owner/Client:  Humboldt State University

Partners: GR Sundberg, Kernen Construction, Maples Plumbing, O&M Industries, Beacom Construction, and Danco

Project Timeline:  2004 to present

SHN has provided geotechnical engineering, geology, and materials testing and inspection services for Humboldt State University since 1998.  Geotechnical and geologic hazard studies on college campuses is completed to the highest standards of practice and is routinely subject to rigorous review by the California State University Seismic Safety Commission.  SHN is also HSU’s Surveyor of Record and Geotechnical Engineer of Record.  Three recent projects are:

  • College Creek Housing Project.  This $47 million housing project includes four dormitories, a student services Community Center, a retail and marketing space, a new soccer field, and a retaining wall for the soccer field.  SHN provided the initial geotechnical investigation, a fault rupture hazard evaluation, project design, a construction Storm Water Pollution Protection Plan (SWPPP), and construction observation and materials testing.
  • Behavioral and Social Sciences Building (BSSB).  SHN provided geotechnical evaluation, soils/foundation design criteria, construction inspection, and as-built surveys for this 5-story building located in a relatively steep, wooded portion of the HSU campus.  SHN provided construction inspection services for the foundation work, concrete and steel tower construction, and application of the fireproofing material for the steel structure.  
  • Schatz Energy Research Center.  HSU’s new 6,000-square foot facility is built on the slope adjacent to the BSSB.  SHN geoscientists performed a subsurface investigation, evaluated proximity to a nearby mapped fault, and provided design recommendations.  Subsurface investigation identified variable bedrock/soil conditions, and non-engineered fills provided an additional geotechnical complication.  SHN also provided survey and construction materials testing services.  A follow-up investigation was recently completed for an addition to this research center.

Investigating seismic hazards at an operating hydroelectric dam

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

Project Details

Location:  Near Burney, Shasta County, California

Owner/Client:  Pacific Gas & Electric Company

Partners:  Lettis Consultants International (trenching team); Desert Research Institute

Project Timeline:  2014 to present

SHN geologists investigated potentially active faults near the Pit River #3 Hydroelectric Dam to determine the seismic hazards to the dam.  This paleoseismic investigation involved excavation, analysis, and logging of multiple trenches and test pits over a two-year investigation period.  SHN was responsible for characterization of faults north of the dam, and worked with a consultant team providing a comprehensive assessment of hazard.  SHN incorporated an “in house” TrenchScan methodology to photograph the exposed soils for preparation of trench logs.  This emerging technology utilizes thousands of photographs that are merged into a single photo-mosaic of the trench wall.  SHN geologists are then able to document the exposure more quickly and accurately.  This cutting edge approach provides a unique, lasting record of these important trenches.  

The study was conducted under the over-sight and formal review of a PG&E Technical Advisory Committee (TAC), consisting of a group of senior industry leaders.  The project is also subject to review by the Federal Energy Regulatory Commission (FERC) and the California Division of Safety of Dams (DSOD).  The scope and necessary detail for an investigation of this magnitude and importance required that a significant amount of high-level paleoseismology occur in a relatively short investigative period.  SHN staff met the challenge because of our staff’s unique experience in paleoseismic investigations and their dedication and willingness to “go the extra mile.”  Field work was completed on time and on budget.  Follow-up reporting and final documentation was due at the end of each field season.  A synthesis meeting with the TAC and regulatory reviewers was completed each year as well.

 

 

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