Frank Groffie, PG, CEG                  Geology consulting                      Clarity, communication, closure.                             Contact us ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
About   Fault investigation   Landslide investigation   Rock-slope analysis   Seismic hazard analysis   Site characterization   General geosupport	Rock-slope analysis  Our analyses of rock slopes at various sites rely on quantitative methods and have resulted in numerous  successful mitigations of hazards. Below, view just a few examples of our work with large rock slopes.
	Rock slope stability  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  This large site in east Oakland, California, was once Leona Quarry. For decades, up to a few years ago, its rock  quarry slopes were tall, steep, and unattractive. Engineers, geologists, and biologists2 entered the scene, and  this former quarry underwent reclamation for residential use. In the mid 2000s, it became the reconfigured,  attractive site of several hundred residential units and open space. One of the new reconfigured slopes, shown  in the left photo, is actually 500 feet high.  The former rock quarry slopes were carefully engineered and graded and laid back to relatively gentle gradients.  While earthwork machinery drove about, Frank Groffie1 spent much boots-on-the-ground effort collecting data  on the freshly exposed rocks across the project to check against geologic surprises. He then analyzed the data,  plus laboratory rock-strength data, using software by RockPack®. Efforts were aimed at ensuring the engi-  neered slopes would remain stable.  Engineering and revegetation2 of former slopes are now quickly resulting in an attractive, stable backdrop to the  new residential development. Native wildlife and plant habitat2 and recreation access along the slopes are  bonuses.
	Rockfall barrier fencing, Leona Quarry  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  As a result of a careful decision-making process, a few quarried rock slopes above the residential development  at Leona Quarry were left more-or-less in their former state.  Frank Groffie1 analyzed these slopes and their rocks. Data included slope heights, gradients, and materials, and  rock sizes, shapes, and weights. Our analyses were aided by CRSP (Colorado Rockfall Simulation Program) soft-  ware. Groffie even sent a few rocks tumbling downslope as an empirical check on the computer-generated data  (while construction workers were at a safe distance).  Output from the analyses consisted of possible bounce heights and distances, kinetic loads, and numbers of  falling rocks. Consequently, the contractor was given directions for installing specialized protective fencing at  the proper locations and with appropriate heights and strengths. Barrier fencing was meticulously engineered  and installed below the slopes to shield the development from possible future tumbling rocks. The photo below  shows a relatively moderate-duty fence; heavier-duty fences were also installed elsewhere on the project.  Pedestrians and cars on the streets and downslope homes are thus protected.
	Dumbarton Quarry, Newark, California  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  We dedicated much effort collecting data on discontinuities (joints) in rock at Dumbarton Quarry while it was an  active producer of road pavement products. As quarrying progressed, we painstakingly measured structural  attitudes in the exposed slopes. We returned the data to the office and plotted them stereonet style, as in the  lower-right photo. Frank Groffie1 analyzed these plots to check that slopes would remain reasonably stable.  Rock consists mainly of Mesozoic seafloor (lower-plate) basalt, with lesser amounts of maroon chert and other  gray ophiolite rocks. Contrary to earlier interpretations by some, not a speck of serpentinite is or was present.  Dr. John Wakabayashi accompanied Groffie on a survey through the quarry and helped identify the rock types.  This quarry reached a depth of some 300 feet; same depth below sea level (site location near San Francisco  Bay). Tall eucalyptus trees are at the quarry rim. A yellow diesel water pump, barely discernable at the bottom  of the photo, handled groundwater seepage from the quarry walls. The bottom of Dumbarton Quarry recently  was, for a time, the lowest open-sky land-surface elevation in North America, albeit artificially and temporarily.  Lower than Death Valley even. Only the Dead Sea (Israel/Jordan) and areas in Argentina and Djibouti (Africa)  held areas of lower land elevation. The pit is now slowly becoming a recreational lake for eventual public recrea-  tional access.
	1. As employee of Berlogar Geotechnical Consultants, client legal relationship with that firm. Relevant technical documents on file      as public record with applicable public agencies.  2. Biological and revegetation work by H.T. Harvey & Associates.
Frank Groffie, PG, CEG, MSc, is Professional Geologist 4930 and Certified Engineering Geologist 1539, in good standing since initiation in 1989, with the State of California Board of Professional Engineers, Land Surveyors, and Geologists This web page last modified October 25, 2012.