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CalGEO - The California Geotechnical Engineering Association

The Voice of California's Consulting Geotechnical Engineers


Member Highlights

Danny Cohen, P.E., G.E., J.D., QSD
Sr. Project Manager/Estimator-J.C. Baldwin Construction

Danny Cohen recently joined JC Baldwin Construction Company after 1.5 years as Chief Geotechnical Engineer at RMA Group\'s San Diego, San Jose and Sacramento offices and nearly 2 years prior to that as branch manager and Chief Geotechnical Engineer at BSK Associates\' Fresno office starting in the fall of 2011. This follows a 26-year long career with Hetherington Engineering, Inc. starting in 1985.  He has long been involved in planning, implementing and supervising a broad range of geotechnical projects, including geotechnical investigation programs for development of residential and commercial structures and site improvements, development of hillside sites, and investigations of distressed structures. During his 2 years as Branch Manager for BSK Associates, Mr. Cohen was responsible for the day to day operations of the Fresno office, supervising the environmental, geotechnical and construction services division, including the soils and materials testing laboratories. and while at RMA Group he focused on developing and building strong materials testing and geotechnical engineering groups for RMA in the San Diego, San Jose and Sacramento offices. He now turns his attention to the construction industry, focusing on expanding and building JC Baldwin\'s scope of services and clientele, as well as doing the estimating for new projects. 

His work also includes performance and supervision of geotechnical observation and testing services during conventional grading and backfilling operations for site development, as well as during implementation of repairs to distressed structures, including projects utilizing drilled piers and driven piles, tiebacks, compaction grouting, mechanically stabilized earth wall systems, geogrid soil reinforcement, dewatering systems and shoring. Mr. Cohen has also performed studies related to groundwater, landslides, liquefaction, environmentally contaminated sites, and design and development of on-site sewage disposal systems. Mr. Cohen has served as an expert witness in regards to numerous geotechnical issues, is a licensed civil engineer in California, Nevada, Arizona, Hawaii, Texas, Oregon and Washington, and Colorado, a licensed Geotechnical Engineer in California and Oregon, a licensed attorney in California, and has served on the Board of Directors of CalGeo since 2006.

David Cymanski, P.E., G.E.
President - KC Engineering

David Cymanski, P.E., G.E. is one of the Founders and President of KC Engineering Company, a geotechnical engineering subsidiary of Materials Testing, Inc.  KC Engineering was founded in 1996 in Vacaville and Redding, California.  His firm provides geotechnical engineering, geologic, environmental assessment, materials testing and special inspection services for a wide range of clientele and projects throughout Northern California.   Dave received his bachelor of science degree in Civil Engineer at Chico State in 1990 and has worked as a geotechnical engineer since that time.  He has practical experience and provides design recommendations for sites of varying terrain from hillsides with landslides that require reinforced earth buttresses or soldier piers and tie-back wall systems, to flat areas with alluvial deposits and liquefaction hazards, to Bay Muds with settlement concerns that require ground improvement or deep foundations.

Christopher Diaz, P.E.
President/Principal - Diaz-Yourman & Associates

Christopher Diaz, P.E. has over 30 years of experience in civil construction and geotechnical engineering.  For the past 15 years, the major focus of his work has been in the design and construction of liquefaction mitigation, as well as in-ground improvement projects, including stone columns, grouting, and deep dynamic compaction. Chris became a principal and company president of Diaz-Yourman & Associates (DYA) in December 2004, after 10 years as a staff engineer through senior engineer.

In addition to his corporate responsibilities, Chris serves on the CalGeo Board of Directors and the Orange County and State boards of ACEC. He is also involved in several professional and engineering organizations, including ASCE, WTS, and is a member of the DFI Ground Improvement Committee.  Chris has been instrumental in directing DYA to generously support the student chapter of CalGeo at Cal Poly Pomona.

Tom Farrell, C.E., G.E.
President and Owner - Farrell Design-Build

Tom Farrell is the President and Owner of Farrell Design-Build. Farrell Design-Build was incorporated in 1999 as a new company focused on specialty geotechnical contracting in California. Since then, Tom has grown Farrell beyond Geopier to include multiple design-build ground improvement and pile solutions including Impact pier, Rapid Impact Compaction, Driven Grout Pile, Drill Displacement Columns and Piles, Auger Cast Pile, and Helical Mini-Piles.

Tom holds Civil and Geotechnical professional engineering registrations in California. Tom earned his Bachelor of Science in 1990 from Cal Poly, San Luis Obispo and his Master of Science in Engineering from the University of California, Davis. Tom’s graduate studies focused on liquefaction and soil-structure interaction during earthquake events under the direction of Dr. Bruce Kutter and Dr. I.M. Idriss at UC Davis. Tom worked as a geotechnical consultant in the Sacramento and Bay Area for 10 years before becoming a geotechnical contractor in 1999. Tom has over 20 years of experience in geotechnical, foundation engineering, and ground improvement in California. Tom’s interests include being an owner-builder on two custom homes, fishing, camping, reading historical accounts, and mostly spending time with his wife, 3 daughters and son in El Dorado County.

David T. Hamilton, P.E., G.E.
President - Hamilton & Associates

David Hamilton, P.E., G.E., is the Founder and President of Hamilton & Associates, a geotechnical engineering firm located in Los Angeles. His firm provides geotechnical and geologic services, soils and materials laboratory testing, construction observation and testing, and limited drilling and sampling services. Hamilton received his B.S. in civil engineering at Loyola Marymount University in 1994 and an M.S. in geotechnical engineering at the University of California, Berkeley in 1995.

He has more than 14 years of experience in public works, commercial, industrial, school, and residential projects, including soft and liquefiable sites, port facilities, and hillside and canyon landfill development. He has taught soil mechanics and solid waste engineering in both undergraduate and graduate engineering programs at Loyola Marymount University and is currently active with the California Board of Professional Engineers. David serves on the Board of Directors for CalGeo.

Charles H. Hartsog, SE., GE., CE., CEG., CHG., RG.
Owner, Founder & Principal of US Soils

             Call 800-US-Soils or 650-969-1985

Registered Soils Engineer #2101

Registered Structural Engineer #2532 

Registered Civil Engineer #29244 

Registered Geologist #6348 

Registered Geotechnical Engineer #2101 

Certified Engineering Geologist #2029 

Certified Hydrologist #539 

Former Cal State University Professor 

Former Cogswell College Professor 

Former Menlo College Professor 

Former Professional Engineering Institute Professor 

Former Pyrotechnic Operator – Explosives and Fireworks 

Subject Expert, National Council of Examiners for Engineers 

Subject Expert, California Board for Professional Engineers 

40+ years of experience, 37+ years in business 

Pilot, etc. 

Proverbs 13:20 (KJV):"He That Walketh With Wise Men Shall Be Wise."

Tom Holdrege, P.E., C.E.G., QSD/QSP
Founding Principal, President - Holdrege & Kull Consulting Engineers

Tom Holdrege has completed over 1,000 environmental, hazardous materials, solid waste, geotechnical and geologic site characterizations in California since 1986. His experience in environmental site characterization ranges from initial site assessment to complex fracture flow modeling and soil and groundwater remediation.

John Hoobs, C.E.G.
Vice President/Principal - Geocon

John Hoobs has more than 25 years of experience with Geocon in engineering geology and geophysics in Southern California. He specializes in structures, transportation, schools and pipelines for residential and commercial land development projects for both private and public clients. His expertise in managing large-scale development has provided clients timely service on projects that have critical schedules. Hoobs has extensive experience in landslide and fault studies, as well as projects requiring rock blasting and placement.

Construction monitoring, verification and adherence to specifications are an integral part of his experience and expertise. He has also provided consultation and expert-witness services for plaintiff and defendant cases involving disputes on residential and public works projects. He is a registered geologist and a certified engineering geologist in California, and a member of the American Society of Civil Engineers, Association of Engineering Geologists, Geologic Society of America, and the San Diego Association of Geologists. John is a Past President on the Board of Directors for CalGeo.

Dr. Siamak Jafroudi, P.E., G.E., R.E.A.
President - Petra Geotechnical

Dr. Siamak Jafroudi has more than 36 years of professional experience in geotechnical engineering. His area of specialization is material characterization in relation to slope stability evaluation, liquefaction analysis, pavement design, collapse potential, earth retaining structures and earthquake engineering. Dr. Jafroudi's experience encompasses the design and supervision of a multitude of soil mechanics laboratory tests and drilling programs.

He has served as a Principal Engineer on several key projects for such clients as schools, university and college districts, public agencies, transportation agencies, residential and commercial developers, as well as private-sector clients. Dr. Jafroudi is a Registered Geotechnical Engineer (GE), a Registered Environmental Assessor (REA), and is registered in Civil Engineering (PE), all in the state of California. Additionally, he is an active member of the American Society of Civil Engineers, the Earthquake Engineering Research Institute and is a Past President of the Board of Directors for CalGeo.

Todd Kamisky, P.E., G.E.
President/Principal Engineer - Mid Pacific Engineering

Todd Kamisky is a Founder and President of Mid Pacific Engineering, and currently manages the firm's Sacramento operations. Kamisky has been working in the geotechnical engineering field since 1994, and his project experience includes master-planned communities, residential subdivisions, infrastructure improvements, detention basins, bridges, communication towers, schools, and commercial/industrial developments.

Kamisky has also performed site-specific ground response studies for numerous projects in the Sacramento and Stockton areas, as well as slope-stability analysis of bluffs, levees and mining pits in the Sacramento and San Joaquin Valley regions. He is a member of the American Society of Civil Engineers, the Structural Engineers Association of Central California, and currently serves as President on the Board of Directors for CalGeo.

Judd King, P.E., G.E.
Sr. Geotechnical Engineers, Yeh and Associates, Inc.

Judd King is a senior geotechnical engineer with the Grover Beach office of Yeh and Associates. A graduate of California State Polytechnic University at San Luis Obispo with a degree in civil engineering (geotechnical emphasis), Judd started his professional career in the greater Sacramento area as a staff engineer with Blackburn Consulting, Inc. and later Youngdahl Consulting Group, Inc. In 2004, he joined Earth Systems and relocated back to the central coast. In August of 2015, Judd transitioned to Yeh and Associates’ Grover Beach office. As a senior geotechnical engineer, Judd's experience has been wide ranging; his projects include industrial and municipal infrastructure, residential and commercial structures, pier reconstructions, and energy related developments. 

Judd is active with several professional organizations, including CalGeo, ASCE and the Geo-Engineering Extreme Events Reconnaissance. He currently serves on the Board of Directors of CalGeo. In his free time, Judd enjoys trail running, working on a 1967 Volkswagen Bug, and traveling with his wife Valarie and 7-year old daughter, Aleah.


Alan Kropp, G.E., P.E.
Principal Geotechnical Engineer - Alan Kropp & Associates, Inc.

Mr. Kropp has over 30 years of local geotechnical experience and is recognized for his expertise in the identification, characterization and mitigation of landslide hazards. Mr. Kropp currently serves on the board of the Earthquake Engineering Research Institutes Northern California chapter (EERI-NC) and is recognized for his contributions in earthquake hazard research. His project experience includes performing geotechnical investigations for schools, roads, subdivisions, hillside properties, office and commercial buildings, and bridges. Mr. Kropp regularly provides geotechnical peer review services to City and County governments and is knowledgeable about geotechnical conditions, principles and practices throughout much of California.

Lutz "Yogi" Kunze, P.E., G.E.
Associate Geotechnical Engineer - Earth Systems Southwest

Lutz "Yogi" Kunze is the semi-retired Executive Vice-President of Earth Systems Southwest (ESSW) and currently serves as an Associate Geotechnical Engineer to provide oversight of the geotechnical engineering staff for ESSW.  He is a Registered Civil Engineer in California, Arizona, Nevada and a Registered Geotechnical Engineer in California.  He served on the Board of Directors of CalGeo and was its president in 1996-97.

Michael W. Laney, P.E., G.E., P. Eng
Senior Geotechnical Engineer/Energy Sector Specialist - Terracon Consultants, Inc.

Michael Laney is currently a Senior Geotechnical Engineer and Energy Sector Specialist for Terracon Consultants, Inc.  He is a Registered Civil Engineer in California and 24 other states, a Professional Engineer in Alberta, Canada,  and a Registered Geotechnical Engineer in California. He has overseen civil and geotechnical engineering projects, and has supervised observation and testing of compacted fill and grading operations.

He has been involved with residential, commercial, industrial, transportation, military and infrastructure projects. Currently he is focused on green projects, such as Transmission line, Substation, Wind and Solar foundations. Mike has helped develop and grade the State Geotechnical Engineer license exam for the California State Board of Professional Engineers, Land Surveyors and Geologists (BPLESG) and is on the BPLESG list of Subject Matter Experts who provide review services for reported enforcement actions regarding geotechnical issues. He has served on the Board of Directors of CalGeo since 2007.


Robert Lokteff, CE, GE
Principal Geotechnical Engineer, Vice President - Blackburn Consulting

Mr. Lokteff has devoted his 20-year professional career to geotechnical engineering and has been with Blackburn Consulting for 11 of those 20 years. He has performed subsurface investigations and provided geotechnical recommendations for levees, roads, bridges, pipelines, communications towers, schools, commercial buildings, residential subdivisions, and landslides. Mr. Lokteff specialized in pipeline installations, deep and shallow bridge foundations and pavement design.

Bob is currently on the CalGeo Board of Directors.

Robert D. Mahony, G.E., C.E.G.
President/Founder - Soil Engineering Construction, Inc.

Since founding the company over 40 years ago, Bob Mahony has structured and guided the growth of Soil Engineering Construction, Inc. (SEC) to a point that it is recognized as one of the pre-eminent geotechnical engineering/construction firms in the state.

Bob specializes in geotechnical construction, primarily focusing on landslide repairs, foundation work, groundwater work, grouting, and general work related to Geotechnical Engineering. He originated and first patented the small diameter pipe method of underpinning foundations. In the early stages of the company's development, Bob initiated the process of installing drilled horizontal drains and anchors utilizing high-pressure water jetting.

Bob has been a member of a panel of experts formed by San Mateo county to advise Caltrans on methods of stabilizing the Devil's Slide area on Highway One.

Mr. Mahony is a Registered Civil Engineer, Geotechnical Engineer, Engineering Geologist, and Geologist in the state of California. He is professionally affiliated with the Amcerican Society of Civil Engineers, as well as, the California Contractor's State License Board.

Martin McIlroy, P.G., C.E.G., P.E.
Associate Engineering Geologist and Civil Engineer - Shannon & Wilson

Martin McIlroy is an Associate Engineering Geologist and Civil Engineer at Shannon & Wilson. He received his B.S. in Geology from the University of California at Davis and has been practicing geology for 21 years.  He is developing the bridge and highway transportation market sector at Shannon & Wilson’s Sacramento office. He has participated in transportation, water and levee projects that include: state highway interchanges and local agency bridge replacements/retrofit, bridge scour evaluations, earth fill dam design, levee design, rehabilitation and inspection, water tanks and wastewater treatment facilities, and roadway landslides and storm damage repair.

Martin has served on the CalGeo\'s board of directors since 2011.  He has become involved with professors and students at UC Davis, UC Berkeley and California State University, Sacramento to help develop the CalGEO Emerging Geoprofessionals group in Sacramento and develop student chapters at the universities. Martin believes that student outreach and participation in CalGeo will strengthen the engineering community and develop future leaders in the profession. He also plays beer league ice hockey and enjoys photography.


Mike Moscrop, P.E., G.E.
Principal Engineer - GMU Geotechnical, Inc.

Mike Moscrop, P.E., G.E., is a Principal Engineer at GMU Geotechnical, Inc., a geotechnical and materials testing consulting firm based in Rancho Santa Margarita, Orange County, California. Mike received his undergraduate degree from the University of Huddersfield, England and obtained his Master of Science in Civil Engineering (Geotechnical) from California State University Long Beach. Mike has a broad range of geotechnical experience from his 25+ years in the business, including a wide variety of large and small office, residential, commercial and retail development, public works and infrastructure projects. Mike has also provided expert witness services on a variety of geotechnical issues.

Mike has been an active support of CalGeo for many years, and was recently elected to be a CalGeo board member.

Hannes H. Richter, P.E.
Principal Geotechnical Engineer - Geofirm/Stoney-Miller Consultants

As President of Stoney-Miller Consultants, Inc., Hannes Richter provides clients with national experience in a broad range of geotechnical engineering applications, including residential, commercial, industrial and government projects. He has practical experience in a number of states that includes project management, laboratory and field investigations, rock and soil slope stability analysis, shoreline processes and protection measures, pavement analysis and design, earth dams, shallow and deep foundations, shoring walls and tieback anchor systems, groundwater development/dewatering, engineering feasibility studies, distress investigations, expert witness testimony, and grading and construction monitoring programs.

Richter is a registered Civil Engineer in Oregon, Arizona, California, Nevada and Colorado and a Geotechnical Engineer in California. He is a member of the American Society of Civil Engineers and serves on the Board of Directors of CalGeo. He has a B.S. for Civil Engineering from California State Polytechnic University, Pomona and an M.S. in Geotechnical Engineering from the University of California, Berkeley.

Peter K. Robertson, Professor Emeritus
Technical Advisor - Gregg Drilling & Testing, Inc.

As Technical Advisor to Gregg Drilling & Testing Inc., Dr. Peter Robertson brings more than 40 years experience as an educator, researcher, consultant and practitioner specializing in the areas of in-situ testing and site investigation, earthquake design of geotechnical structures, and soil liquefaction.  Peter is recognized as an expert both nationally and internationally in the areas of in-situ testing and soil liquefaction. He has been a consultant to various industrial clients and insurance companies in North America, Asia and Europe for projects involving liquefaction evaluation for major structures, stability of on-shore and off-shore structures, landslides, stability of natural slopes and tailings dams, and use and interpretation of in-situ tests.  He is the co-author of the primary reference book on Cone Penetration Testing (CPT).  He has also authored or co-authored over 250 publications as well a popular CPT Guide that is freely available via the Gregg website.  With support from Gregg, Peter has also assisted in the development of several inexpensive CPT-based interpretation software programs and has presented a series of free webinars on the CPT in an effort to enhance education and practice.  Peter continues to provide some private consulting to a wide range of clients.

Greg Silver, M.S., P.E., G.E.
Vice President/Principal Engineer - GMU Geotechnical

Greg Silver joined GMU in 1997 and currently serves as the company's President and Principal Engineer. He is instrumental in furthering the direction and character of the company and oversees the majority of the firm's day-to-day operations. Greg's experience in the industry includes more than 29 years of working with clients throughout Southern California on some of the most challenging geotechnical projects. He has worked successfully for and with industrial, residential and commercial developers, master community planners and governmental agencies. He has extensive experience in landslide evaluation and remediation design, geotechnical instrumentation, residential and commercial development, public works projects, municipality consultation, mechanically stabilized earth walls, and forensic projects. In addition, Silver has served as an expert witness in regards to numerous geotechnical issues and as city geotechnical engineer for numerous cities throughout Southern California.

Mr. Silver has a Bachelor’s degree in geological sciences with an emphasis in Geophysics from the University of California at Santa Barbara and a M.S. in Civil Engineering (emphasis Geotechnical engineering) from California State University at Long Beach.  He is a registered civil engineer in California and Nevada as well as a Registered Geotechnical Engineer in California.   He served as CalGeo’s president in 2010 and is also member of ASCE.  Mr. Silver has published several papers on subjects ranging from MSE wall design and performance to Landslide mitigation.

Scott Stephens, G.E., C.E.
President - Miller Pacific Engineering Group

Scott Stephens is President of Miller Pacific Engineering Group and is responsible for the overall business management of the firm.  He is also the Senior Project Manager and Reviewer for numerous Geotechnical and Geo-Civil projects.

He has prepared numerous geotechnical planning reports and environmental impact studies and serves as a Peer Reviewer for several local governmental agencies.

He has conducted many forensic geotechnical investigations and has provided expert testimony on geotechnical issues including slope instability, retaining wall failure, foundation distress and groundwater seepage.

His projects frequently combine investigation of distressed property and remediation design.  Such projects have ranged from compaction grouting to re-support a multi-story building, reconstruction of a tunnel lining collapse, stabilization of a creek channel with a tied back soldier pile retaining wall, and reconstruction of a landslide using subdrains and a reinforced earth buttress.

Scott’s Geo-Civil projects have included full engineering design, bid documents, contract management, and construction inspection for a variety of projects: retaining structures, landslide repairs, remedial drainage, pedestrian bridges, restoration of distressed foundations, and synthetic turf athletic fields.

His technical expertise includes sophisticated computer analyses, many conventional and unique exploration techniques, advanced testing methods including in-situ testing by field vane shear, monitoring with inclinometers and piezometers, field permeability measurement, nuclear density gauge testing and seismic refraction surveys.

Robert Tadlock, CEO
General Manager - Matriscope Engineering Laboratories, Inc.

As Chief Executive Officer, Robert Tadlock is responsible for overall firm leadership including implementing core values, mission, culture, and vision to staff. Robert contributes more than 27 years of industry specific experience in the geotechnical, construction inspection and materials testing field. His passionate commitment ensures that a high quality service is provided to all clients and that any necessary action is taken to maintain the firm’s high reputation for excellence in engineering and customer service. Robert manages business development related activities including; proposal preparation, contract administration, budget tracking, and assuring customer satisfaction. His responsibilities include participation as Project Principal on selected key assignments.

Larry Taylor, G.E.
President - Taylor Group, Inc.

Larry Taylor is the President of Taylor Group, Inc., a geotechnical, environmental and earth sciences consulting firm based in Oceanside, CA.  Larry earned a Bachelor of Science degree from California State University at Long Beach in 1979 while working for Southern California Edison's geotechnical group. He returned to CSULB in 1980 as a lecturer and research associate while taking graduate courses. Beginning in 1983, Larry worked for several earth sciences consulting firms including Dames & Moore, The Earth Technology Corporation (now Earth Tech) and Bing Yen & Associates before founding TGI in 1999.

As a CalGeo board member, Larry believes his 30 years of experience as a geotechnical engineer, project manager and executive in the geotechnical profession provides him with a good understanding of important issues affecting our members.

R. Rex Upp, PhD, G.E.
Geotechnical Consultation

In 2012, Dr. Upp transferred leadership of UPP Geotechnology, Inc., the company he founded in 1983 and headed for almost 30 years, so he could focus his professional practice on litigation support (expert witness) and independent geotechnical consultation. His former company, an efficient seven-person firm, was focused on hillside residential projects in the San Francisco Bay Area, including new construction and properties distressed by earth movement.

Dr. Upp holds a B.A. degree in geology, B.S. degrees in mechanical engineering and environmental engineering, M.S. degrees in watershed management and soil engineering, and a Ph.D. in engineering geology. He is licensed in California as a Geotechnical Engineer and Engineering Geologist. He has been an expert witness in more than 100 cases throughout the state.

Dr. Upp is active in multiple professional organizations. He has been a member of CalGeo since its SAFEA days and was President in 2011-2012. He is a past president of the Association of Environmental and Engineering Geologists (AEG) and is a Life Member of ASCE.

Add Your Highlight

Member Highlight

Robert D. Mahony

G.E., C.E.G.

President/Founder - Soil Engineering Construction, Inc.

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