Management Team

President, Senior Principal Geotechnical Engineer, Senior Principal Geophysicist

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Mr. Shires has over 46 years of professional experience in the fields of civil and geotechnical engineering. Mr. Shires is qualified as an expert witness in Civil/Geotechnical Engineering. He has testified in trials resulting in landmark legal decisions involving natural watercourse, earth movement and construction dispute issues. 

He has been the chief design engineer on over 120 landslide repair projects, and was retained by the Chinese government to work on the Yangtze Water Resource Commission’s Three Gorges Dam project in China. He was also the MTA geotechnical engineering expert for their Redline Tunnel distress litigation in Los Angeles.    

As Principal Geophysicist, Mr. Shires has conducted numerous geophysical investigations throughout the western United States, from small-scale studies of rippability for grading to providing Quality Assurance for investigations at P.G.&E.’s nuclear power plants in California to investigations of numerous dam sites. He also investigated over 50 dam sites and was the chief design engineer for a 160-foot high rockfill dam in Arizona. 

At Cotton, Shires and Associates, Inc.,  Mr. Shires is charge of all civil and geotechnical engineering projects. His responsibilities range from investigation, analysis and product review to final design participation and project management for large projects.  

Mr. Shires remains actively involved in the engineering investigation, design, construction, and review for technical investigations.

Click here to download Mr. Shires’ CV.

Registered Geotechnical Engineer in California, Registered Geophysicist in California
Registered Professional Civil Engineer in California, Colorado, Hawaii, Idaho, Oregon, and Washington 

M.S., Civil Engineering: Stanford University, Stanford, California, 1975
B.S., Stanford University, Stanford, California, 1972

Technical Expertise
• Landslide mitigation and flooding and levee stability 
• Dams, waterway and coastal engineering and design    
• Geotechnical design for water and wastewater facilities   
• Grading (filling & excavation) design and practice 
• Roadway, parking, pavement and drainage design  
• Seismic and radio-detection surveys for pipelines  
• Surface surveys for regional seismic analyses  
• Reflection surveys for fault investigations 
• Surface and downhole seismic surveys for landslide investigations
• Seismic studies of waste disposal landfills and tailings dumps
• Downhole, crosshole and/or surface seismic surveys for over 30 dams
• Seismic studies of rippability for grading construction
• Environmental hazards exploration

Principal Geologic Engineer

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Mr. Marcum has over 34 years of professional experience in the geotechnical consulting
field, working on geologic and geotechnical engineering projects in both northern and
southern California, Hawaii, Colorado and Utah. 

Mr. Marcum has a background in both geology and geotechnical engineering and has
combined these disciplines as a geologic engineer (Registered Professional Engineer)
specializing in earth and rock slope stability issues.  He has worked on many large
landslides, including the Love Creek Landslide in Santa Cruz, the Big Rock Mesa
Landslide in Malibu, The Hulu-Woolsey and Ailuna-Leighton landslides on Oahu, and
the Ocean Trails landslide and the White Point rockslide in Palos Verdes.  Mr. Marcum
has performed geological engineering review services for a ski resort expansion in
landslide terrain in Crested Butte, Colorado, rock slope stability mapping and peer
review services for an interstate widening project in Utah, and he has served on an
appeal panel for Draper City Utah regarding development within landslide terrain in the
Traverse Mountains.  Mr. Marcum also served as an independent reviewer for the
characterization and analysis of a potential rockslide at PG&E’s Diablo Canyon Nuclear
Power Plant, and as as a technical reviewer for an engineering geologic investigation
and geotechnical analysis of the White Point Rockslide in Palos Verdes.  The work Mr.
Marcum has performed on slope stability projects has included aerial photographic
research, engineering geologic reconnaissance and mapping, downhole logging of large diameter borings, logging of small diameter core and installation of both manual and automated instrumentation, review of laboratory data and engineering characterization of the earth units, and performing and reviewing limit equilibrium and finite element modeling results.  Mr. Marcum has mapped and designed repairs (retaining systems and rockfall mitigation measures) for steep rock quarry slopes in San Francisco (recently completed the Telegraph Hill-Chestnut Street project) and steep rock slopes above hydro facilities in the Sierra.

Mr. Marcum currently teaches a portion of an annual slope stability course presented by
the University of Wisconsin.  He has also presented technical lectures on a variety of
subjects including instrumentation, landslides, engineering geology, rock toppling and
rock fall case histories, and co-led geological engineering tours of the Bay Area with Dr.
Richard Goodman for the 45th  and 47th American Rock Mechanics Association

Mr. Marcum has extensive experience performing geological engineering hazard
assessments of rock and soil slope stability for hydro-electric water conveyance
facilities in the central and northern Sierra Nevada.  This work includes stability
assessments of over 240 miles of canals and flumes, 19 penstocks, 5 siphons and the
abutments of 8 dams.  Mr. Marcum also evaluated the landslide and debris flow
potential along an 8-mile long diversion pipeline in the Sierra Nevada, and assessed the
stability of two water conveyance tunnels.

Many of Mr. Marcum’s projects involved the design of remediation measures including
shotcrete, low and high capacity rock bolts and deep rock anchors, cantilevered and
tied-back concrete shear pins, grading repairs involving removal and replacement of the
unstable material and/or the installation of earth buttresses, cantilevered retaining walls
and lowering the ground water table using both vertical and horizontal drains.

As Principal Geologic Engineer, Mr. Marcum is responsible for overall project
supervision and coordination including mapping, exploration and site assessment,
analysis of geologic and geotechnical data, geotechnical design, and preparation and
presentation of technical reports.  His areas of expertise include:
• Engineering geologic mapping, hazard mapping and risk assessment
• Subsurface investigation, small and large diameter drilling and coring
• Instrumentation design, installation and analysis for rock and soil sites
• Laboratory testing, program design and analysis
• Stability analyses, rock and soil slopes, two and three dimensional limit equilibrium
• Landslide and erosion mitigation design, retaining walls, tieback shear pins, rock
anchors and bolts
• Aerial imagery and surveying products using an sUAS (drone)

Click here to download Mr. Marcum’s CV

Registered Professional Civil Engineer in California, No. 65837
Certified FAA sUAS Remote Pilot No, 4065451

M.S., Geotechnical Engineering: University of California, Berkeley, California, 1987
B.A., Geology: Western State College, Gunnison, Colorado, 1983

Professional Affiliations
American Society of Civil Engineers
Association of Engineering Geologists

Selected Publications

Wallace, R. Reynolds, E. Steen and R. McManus), Applied Geology in California,
Association of Engineering Geologists Special Publication

HILL, SAN FRANCISCO, CALIFORNIA, 2015, (with WALLACE J.), Abstract submitted
for the 49th U.S. Rock Mechanics/Geomechanics Symposium, San Francisco,

2011, (with R. Goodman and R. McManus), Paper submitted for the American Rock
Mechanics Association, 45th US Rock Mechanics/Geomechanics Symposium, San
Francisco, California.

Principal Geotechnical Engineer

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Mr. Schrier has over 32 years of professional experience in the field of geotechnical engineering.   Recently he has acted as Principal Engineer for a large landslide investigation and stabilization project in Santa Barbara, California.  The stabilization design consists of multiple rows of large diameter shear pins, high tension tiebacks, grading, retaining walls, and subdrains.    

His experience in engineering analysis for landslide related projects include: analyzing laboratory data, determining static and seismic slope stability, and determining seismic displacement magnitudes.  Mr. Schrier has designed retaining walls, buttress repairs, and drainage mitigation measures.   

He has an extensive background working with UTEXAS3 slope stability programs, FEADAM for the finite element analysis of dams, SHAKE for the determination of surface acceleration from earthquakes, DISPLMT for determination of permanent seismically induced displacements; and AutoCAD. 

As a Principal Geotechnical Engineer, at Cotton, Shires & Associates, Inc.,  Mr. Schrier performs geotechnical engineering analysis, and prepares reports, designs, plans and specifications.

Click here to download Mr. Schrier’s CV

Registered Geotechnical Engineer in California, No. 2334
Registered Professional Civil Engineer in California, No. 47816 

M.S., Civil Engineering: Stanford University, Stanford, California, 1986
B.S., Applied Earth Science: Stanford University, Stanford, California, 1985

Professional History
Principal Geotechnical Engineer, 2006 – present; Cotton, Shires & Associates, Inc., Los Gatos, California.
Senior Geotechnical Engineer, 1996 – 2006; Cotton, Shires & Associates, Inc., Los Gatos, California.
Project Geotechnical Engineer, 1990 – 1996; Harlan Tait Associates, Inc., San Francisco, California.
Assistant Professor of Civil Engineering, 1988 – 1990; University of Los Andes, Bogota, Colombia.
Staff Geotechnical Engineer, 1986-1988; Harlan Tait Associates, Inc., San Francisco, California.

Technical Expertise
• Slope stability analysis; 
• Grading design and practice; 
• Construction inspection and testing;
• Erosion control and drainage design;
• Design of repairs and mitigation measures for failed slopes.

Principal Engineering Geologist

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Mr. Wallace has over 25 years of experience in the fields of geology and engineering geology, working on projects in both northern and southern California as well as Colorado, Utah, Hawaii, and North and South Dakota.

Mr. Wallace has performed geologic mapping and evaluation of steep rock slopes affecting more than 40 penstocks, 20 dams and powerhouses, and 4 tunnels primarily within PG&E’s hydro-generation facilities in the northern, central and southern Sierra Nevada. In addition, Mr. Wallace has extensive experience in hydro-projects such as mapping dam abutments, tunnels and penstock alignments, as well as tunnel, abutment, and portal rock bolting.

He uses his extensive experience in coastal geologic processes to perform detailed geologic investigations of coastal bluff properties. In addition, Mr. Wallace recently investigated several large, active landslides that severely distressed roadways and residential areas, throughout northern and southern California. These projects involved extensive surface and subsurface investigation, instrumentation, and analysis.

Mr. Wallace has also been involved with geologic mapping and siting studies for several fault and landslide constrained reservoirs, and recently mapped unstable coastal bluffs in throughout California.  Many of these projects involved using rock climbing techniques to safely access steep rock slopes.

As our Principal Engineering Geologist, Mr. Wallace is responsible for the research, compilation and analysis of all pertinent geologic data. He also prepares technical reports, gives technical talks at professional conferences and provides expert witness testimony.

Click here to download Mr. Wallace’s CV.

California Professional Geologist, PG 6151, February 8, 1995
California Certified Engineering Geologist, CEG 1923, February 8, 1995

M.S. Geology:  San Jose State University, San Jose, California, 1991
B.S. Geology:  University of Southern California, Los Angeles, California, 1985

Professional History

Staff to Principal Engineering Geologist, 1990 – Present; Cotton, Shires and Associates, Inc., Los Gatos, California.

Field Geologist, 1986-1988; Electrowatt Engineers/Gibbs and Hill, North Fork Stanislaus Hydroelectric Project, Murphys, California.

Field Geologist, 1986; United States Geological Survey, Denver, Colorado.

Selected Publications/Abstracts 

DETAILED GEOLOGIC MAPPING UNCOVERS PREHISTORIC LANDSLIDE DAM IN THE RIDGE BASIN, CALIFORNIA, 2011, (with JOHNSON, Philip L.), Abstract submitted for the 11th International & 2nd North American Symposium on Landslides, Banff, Canada.

GEOLOGIC ENGINEERING TOUR OF SAN FRANCISCO AND THE SAN FRANCISCO PENINSULA, 2011, (with R. GOODMAN and D. MARCUM) American Rock Mechanics Association, 45th US Rock Mechanics/Geomechanics Symposium, Field Trip Leader and Field Trip Guide Book.

THE HIDDEN COMPLEXITY OF A DEEP-SEATED LANDSLIDE IN RICHMOND, CALIFORNIA, 2011, (with JOHNSON, Philip L.), Abstract submitted for the 11th International & 2nd North American Symposium on Landslides, Banff, Canada.

DEEP ROCK TOPPLING DISTRESS AT BELDEN TUNNEL AND SIPHON, SIERRA NEVADA, CALIFORNIA, 2011, (with D. Marcum), Abstract submitted for the 13th International Conference and Field Trips on Landslides, Kyoto, Japan.

WOODLEAF ROCKFALL, NORTHERN SIERRA NEVADA, CALIFORNIA: KEEPING THE POWERHOUSE OPERATING AFTER A NEAR MISS, 2011,  (with D. MARCUM), Abstract submitted for the 13th International Conference and Field Trips on Landslides, Kyoto, Japan.

COMPLEX INTERPLAY BETWEEN TOPPLING, SLIDING, AND STRESS CHANGES ASSOCIATED WITH A MASSIVE LANDSLIDE, SANTA BARBARA, (with SHIRES, Patrick O., DURDELLA, Milton J., SNEDDON, Tim P.), in Program with Abstracts, 2009 Association of Engineering Geologists Annual Convention, South Lake Tahoe.

UNSTABLE SLOPES IN THE FRANCISCAN COMPLEX TERRANE: LESSONS LEARNED FROM URBAN QUARRY SLOPES IN THE SAN FRANCISCO BAY AREA, 2007, (with Ted M. Sayre), in Program with Abstracts, First North American Landslide Conference, Vail Colorado, Page 81.

GEOLOGIC CHARACTERIZATION OF RANGE-FRONT THRUST FAULTS, WESTERN MARGIN OF SANTA CLARA VALLEY, CALIFORNIA, 2005, (with Ted M. Sayre, Ron S. Rubin), in Abstracts with Programs, Geological Society of America 101st Annual Meeting, Cordilleran Section, Page 43.

CATASTROPHIC DEBRIS FLOW FAILURE OF THE LA CONCHITA HILLSIDE: LESSONS REVISITED, VENTURA COUNTY, CALIFORNIA; 2005 (with William R. Cotton), in Abstracts with Programs, Geological Society of America 101st Annual Meeting, Cordilleran Section, 2005, Page 43.

THE OCEAN TRAILS LANDSLIDE: DEFINING SAFE ZONES ALONG HIGH COASTAL BLUFFS, RANCHO PALOS VERDES, CALIFORNIA; 2005 (with William R. Cotton), in Abstracts with Programs, Geological Society of America 101st Annual Meeting, Cordilleran Section, 2005, Page 43.

ROCKFALL HAZARD EVALUATION AT THE KERN INTAKE, KERN CANYON PENSTOCK, KERN RIVER, SOUTH-CENTRAL CALIFORNIA:  2003 (with William D. Page, Dale R. Marcum and Joseph M Durdella ), in Program with Abstracts, Association of Engineering Geologists, 2003, Annual Meeting, Page 70.

INSTABILITY OF AN ABANDONED QUARRY SLOPE: LESSONS LEARNED FROM FRANCISCAN COMPLEX CHERT, SAN FRANCISCO, CALIFORNIA:  2002 (with Dale R. Marcum, and William R. Cotton), in Program with Abstracts, Association of Engineering Geologists, 2002, Annual Meeting, Page 89.

LIVING WITH MOVING GROUND- LANDSLIDES AND COSTAL EROSION IN SAN MATEO COUNTY, CALIFORNIA: 2000 (with W.F. Cole, M.G. Smelser, E. Hay, T. Sayre, J. Van Velsor, T. Whitman, C. Snell and D.S. Kieffer) Association of Engineering Geologist Field Trip Guidebook, 31 pages.

GEOLOGIC AND GEOTECHNICAL CHARACTERIZATION OF THE WEEKS CREEK LANDSLIDE, SAN MATEO COUNTY, CALIFORNIA:  1994 (with William F. Cole and Patrick O. Shires), National Earthquake Hazards Reduction Program, U. S. Geological Survey grant 1434-93-G-2340.

GEOLOGIC INVESTIGATION OF MECHANISMS CAUSING DEFORMATION OF COYOTE LAKE DAM, SANTA CLARA COUNTY, CALIFORNIA:  1994 (with Tim Hall, Michael Angell, and William F. Cole), in Geological Society of America, Cordilleran Section 90th Annual Meeting, March 21-23, 1994, San Bernardino, California, Abstracts with Programs, p. 56.

GEOLOGIC CONSTRAINTS ON THE QUATERNARY TECTONIC HISTORY OF THE NORTHEASTERN MARGIN OF THE CENTRAL SANTA CRUZ MOUNTAINS, CALIFORNIA:  1994 (with William R. Cotton, and William F. Cole), in EOS, Transactions, American Geophysical Union, 1994, Fall Meeting, p. 682.

Principal Engineering Geologist; Manager, Southern California Office

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Mr. Phipps has over 32 years of diverse technical, project management, operations management and executive experience in the geotechnical industry in southern California.  In addition to providing expertise in all phases of geotechnical investigation, Mr. Phipps has successfully managed projects with budgets exceeding $500,000.

Mr. Phipps has performed as City Geologist or Engineering Geological Reviewer for a large number of southern California cities, primarily in Ventura and Los Angeles Counties. This extensive background ensures that Mr. Phipps is well-versed in excavation, grading, and building code regulations, especially as they relate to engineering geology, hillside and coastal development.  

In addition to assisting in the development and review of geotechnical guidelines and proposed code changes for several municipalities, Mr. Phipps has also assisted several cities with obtaining disaster-related FEMA funding.

Click here to download Mr. Phipps’ CV

Professional Geologist in California, PG 5748
Certified Engineering Geologist in California, CEG 1832

B.S. Geological Sciences:  University of Southern California, Los Angeles, California, 1987
Graduate-level coursework in Hydrogeology, California State University, Northridge, 1988-1989,  1992 

Professional History

Principal Engineering Geologist and Manager, Southern California Office, October, 2008-Present; Cotton, Shires & Associates, Inc., Thousand Oaks, California. 

Principal Geologist, 2004-2008; Geolabs-Westlake Village, Westlake Village, California. 

Principal Geologist to Vice President of Operations and Branch Manager, 1998-2004; Bing Yen & Associates, Inc. (subsidiary of ATC Group Services Inc.), Camarillo and Irvine Offices, California. 

Senior Project Geologist, 1996-1997; Leighton and Associates, Inc., Westlake Village, California. 

Senior Project Geologist and Manager of Geological Services, 1993-1996; Bing Yen & Associates, Inc., Irvine, California. 

Staff to Project Geologist, 1986-1993; Slosson & Associates, Van Nuys, California. 

Technical Expertise
• engineering geological site characterization studies
• technical/peer review for municipalities,
• geotechnical construction observation and monitoring
• litigation support 
• expert witness testimony
• geotechnical evaluation and remediation of landslides and other geologic hazards

Professional Affiliations
American Society of Civil Engineers
Association of Engineering and Environmental Geologists
American Public Works Association
Coast Geological Society 

Selected Publications

Inverse Condemnation:  How to Win; How to Keep the Damages Down, co-presented with G. Fisher, C. Schweikhard, and L. Sommer, Public Agency Risk Managers Association Annual Meeting, Monterey, California, 2001, and six other venues.

GUIDELINES FOR PREPARING ENGINEERING GEOLOGY REPORTS, REVISED 1992, assistant to J.E. Slosson, co-assisted by T.F. Blake, J.A. Johnson, J.R. Keaton, R.A. Larson, C.M. Scullin, & T.L. Slosson in County of Los Angeles Department of Public Works, Manual for Preparation of Geotechnical Reports, Appendix pp. A28-A39, Revised August 2005.

The City of Agoura Hills Review Process:  A Case History of the Establishment of Guidelines to Expedite the Preparation and Review Process of Engineering Geology Reports, co-authored with T.L. Slosson in Proceedings of the Association of Engineering Geologists 35th Annual Meeting, Los Angeles, California, 1992.

An Example of Sequential Land Use Necessitating Mitigation:  Well Abandonment in the Kraemer Oil Field, Yorba Linda, California, co-authored with J. E. Slosson and E.C. Sprotte, in Proceedings of the Association of Engineering Geologists 34th Annual Meeting, Chicago, Illinois, 1991.

Use of Multiple Working Hypotheses and Multiple Geologic/Geophysical Technologies to Analyze a Complex Landslide, co-authored with D.D. Crowther, T.L. Slosson and J.E. Slosson in Proceedings of the 27th Symposium on Engineering Geology and Geotechnical Engineering, Logan, Utah, 1991.

Application of Oil Well Technology and Continuous Coring to Landslide Investigation, co-authored with A.B. Esmilla and J.E. Slosson in Geology of the Palos Verdes Peninsula and San Pedro Bay, Volume and Guidebook, Pacific Section AAPG and SEPM, 1987.