Geotechnical Investigations
ENW performs a wide range of geotechnical analyses including settlement, slope stability, and seepage. We have a large selection of computer software and maintain access to several on-line databases, enabling ENW to efficiently analyze alternatives to optimize designs and provide our clients with cost-effective geotechnical analysis.
Slope Stability: The stability of natural and man-made slopes is dependent on a number of factors, including site geology, slope inclination, strength of soils, construction activities, and ground shaking. ENW utilizes state-of-the-art computer programs to perform slope stability analyses for both planned and existing slopes, as well as to provide repair recommendations for slope failures. Typically, these analyses are conducted based on laboratory tests performed on samples obtained from exploratory excavations, such as borings or test pits.
Geologic hazard evaluations are incorporated into geologic studies and may also be performed as a site-specific objective. Geologic hazard evaluations range from preliminary assessments to detailed analysis of hazards and design of mitigation measures.
Geologic hazard evaluations address:
- Faulting and seismic hazards, including ground shaking, ground rupture and liquefaction potential
- Landslide, mudflow and rockfall potential
- Groundwater conditions and potential for flooding
- Erosion potential
- Compressible peat and organic soil deposits
- Expansive soils
- Geologic hazard assessments for school, hospital or other critical facilities projects
Prominent Geotechnical Projects
Bonneville Dam Navigation Lock, Oregon
Construction of a new lock required the stabilization of 3 landslide masses, relocation of a railroad mainline, and construction of an extensive diaphragm wall system to permit construction of the lock below the river level. The project, which incorporated all of the above-described activities, was a $40 million dollar federal project. Neil Woller was the Principal Technical Reviewer for the project. He wrote the Foundation Report, which documented design assumptions, public bid process, subsurface investigation, and construction as-builts.
Regional Landfill Siting and Feasibility Study, Eastern Oregon
Neil Woller was the Principal Investigator for the Landfill Siting Study and Site Characterization Study sections of the Landfill Feasibility Study. He directed all site exploration and subsurface hydrogeologic testing, mapped local geology, and directed materials testing. He wrote the Site Characterization Study Report for the proposed facility. The landfill is now in operation, and has a planned total expansion of 690 acres (greater than one square mile).
Siuslaw National Forest, Oregon
The Siuslaw National Forest hired Neil Woller to inventory the Forest’s aggregate sources and to design development plans in compliance with state and federal regulations. Neil evaluated over 25 potential and active rock sources, and designed environmentally sound development plans.
Pumped Storage Hydroelectric Project, Southern Oregon
The proposed pumped storage hydroelectric project involved pumping water to a dammed basin at an upper elevation on a mountain, followed by release of the water during periods of high electrical demand. Released water would be re-collected at a dammed impoundment at a lower elevation in the adjacent basin. Neil Woller evaluated soil and geologic conditions in the proposed impoundment areas on the mountain and in the basin below. He also evaluated the geology of the mountain between the two impoundments that would be tunneled to permit hydroelectric power generation.
Planned Development, Coast Region, OR
Lynn Green evaluated thefeasibility of a planned development in the area of a former camp, considering development feasibility, slope stability and geotechnical soil assessment. The investigation included mapping and characterization of geology, soils, erosion characteristics of the area, surface runoff, and slope failures. The geotechnical field investigation included exploratory borings and laboratory testing of subsurface materials.
Potential Quarry Prospect, Western, WA
Lynn Green performed a geologic assessment of the potential rock source. The investigation focused on geologic mapping, rock specification analyses, geophysical analysis, and site surveying with transit and GPS. He presented quarry development recommendations to the property owners.
Landslide Mitigation, Oregon
Lynn Green, working with Portland State University, was the principal surveyor for this project, which included both a topographic and subsurface survey. He wrote the Landslide Mitigation Report, which documented the anatomy of the landslide. The report included the results of the subsurface investigation and landslide mechanics.