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Natural Disaster Damage Assessments

In case of emergencies, we provide geologic safety assessments of damage to properties and transportation routes impacted by earthquakes and storm-related causes, such as debris flows, landslides, and flooding. Such emergency situations require immediate attention so that appropriate recommendations can be made and implemented to save a road from further damage, or to prevent an active landslide from encroaching toward a structure. Permanent repair of damages can be addressed as soon as is practical.

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Historic Aerial Photographic Review and Building Permit Research

By reviewing historic aerial photographs and researching available building permit records and building/grading plans, we are able to provide a chronology of site conditions. The information collected from this review includes the history of development at the site, landscape modifications to the property, and the relative stability of slopes in and around the site. Aerial photographs are available for many areas in California dating back before WWII, and even earlier (see website: http://www.pacificaerial.com/). This is the first step for many site geology investigations.

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Landslide Hazard Evaluation, Investigation Reports, and Repair

We provide many levels of landslide evaluation and hazard assessment, depending on the needs of our clients. We offer basic reconnaissance-level geologic mapping, historic aerial photographic review, and landslide consultation for projects with minimal budgets or developments that are in the initial planning stages. We can expand our basic reconnaissance-level evaluation to include a complete subsurface investigation report that characterizes landslides. This may include logging of exploratory backhoe trenches, logging and sampling small diameter exploratory borings, and down-hole logging of large diameter borings. We work with geotechnical engineers and grading contractors to assist in the design and repair of landslides. Our services offered during landslide repairs generally include project management, geologic mapping of keyway excavations, locating subdrains and outlets, and the preparation of an as-constructed geologic map and construction report (see example of landslide repair).

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Slope Inclinometer and Water Piezometer Installation & Monitoring

We install slope inclinometer casings to measure shallow, downslope soil creep and deeper landslide movements. Such instruments provide long-term monitoring of hillslopes to evaluate ground movements (see example of graphic plot). We also install and monitor water piezometers to collect data on ground water fluctuations. Piezometers are especially useful in stream, wetlands, and tidelands studies. Both of these instruments are sometimes installed on the same project site, and the combined data can be beneficial to the outcome of the project.

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Earthquake Fault Hazard Evaluation (Alquist-Priolo Studies)

We evaluate new construction sites for active faulting in accordance with California’s Alquist-Priolo Earthquake Fault Zoning Act of 1972 (see website: http://www.consrv.ca.gov/cgs/rghm/ap/ ). The basic evaluation includes a review of historic aerial photographs, a geologic site reconnaissance, and conclusions and recommendations. If necessary, a more comprehensive evaluation might include logging trench excavations to uncover faults, evaluating the age of most recent movement, and establishing appropriate construction setbacks from active faults.

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Down-Hole Visual Logging of Large Diameter Borings

Down-hole logging is a proven method of exploring the deepest shear plane of a landslide. We drill vertical shafts >24-inches in diameter to depths of over 100 feet, and our geologists are lowered into the boring in a protective cage suspended by a cable. Using a miner’s light, rock pick, and Brunton compass, we make firsthand observations and characterize the subsurface geologic conditions. We typically produce a boring log of our observations along with geologic attitudes collected within the boring. In addition, we are also capable of videotaping the logging process inside the boring for future documentation.

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Geology Evaluation and Feasibility of Development Studies

We provide geologic evaluations and assess the feasibility of proposed developments for vacant and occupied parcels. This is usually performed prior to any subsurface exploration, to identify potential geologic hazards, such as landslides and faults that might impact development plans. This is a cost-effective reconnaissance tool that can provide important planning information.

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Geologic Hazard Abatement District (GHAD)

A GHAD offers an alternative means of recognizing potential geologic hazards within developed property, such as residential subdivisions, and mitigating such hazards as necessary and immediately without time-consuming litigation. A GHAD is mandated under California state law. Potential geologic hazards generally include all types of slope failures including rapid debris flows, fill slope failures, and slow-moving landslides. Working with legal consul, we provide the technical expertise necessary to establish and develop a GHAD and to prepare a site maintenance plan or a Plan of Control. This technical expertise may include geologic mapping of the potential GHAD site, review of all grading and development information, installation and monitoring of slope inclinometers, and geologic consultation (see website for more information on GHADs: http://www.consrv.ca.gov/cgs/rghm/haz_abatement.htm).

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Earthwork Grading Inspection and Geologic Mapping

We provide part-time and full-time field cotrol during placement and compaction of fill soils, and geotechnical supervision during the course of a grading project. This usually includes detailed geologic mapping of keyways and benches, determining and mapping the best location for canyon subdrains, and daily documentation of progress (see example of grading site).

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Telecommunication Site Investigation

We prepare geologic and geotechnical investigation reports for the construction of telecom sites throughout California. Such investigations include subsurface drilling and sampling of the earth materials at the site, geologic mapping, review of potential landslide and other geologic hazards, and foundation recommendations for the proposed facilities. We also prepare soil resistivity surveys for the design of grounding systems at telecom sites.

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Stream Restoration and Stream Bank Repair

If a stream bank failure is to be repaired, we evaluate the existing stream conditions and the cause or causes of the failure. We offer alternatives to common hardscape repair elements such as gabions, concrete, and rip-rap. We work with biologists, habitat restoration specialists, and stream regulatory agencies to develop the most appropriate restoration plan for the site. As part of our plan to restore the stream bank, we incorporate soil bioengineering and biotechnology techniques into the repair. These techniques consist of using live and dead plant materials placed in such a way as to control creek bank erosion and to provide natural stability to the creek bank through plant roots, act as a catchment for sand and silt deposition, and to provide habitat for fish and wildlife (see website: http://www.urbancreeks.org).