Dr. Walker has over 15 years of professional experience in geochemistry and analytical chemistry. He received a B.S. in Chemistry from St. Louis University in 1975, an M.S. in Soil Chemistry from the University of Minnesota in 1980, and a Ph.D. in Soil Chemistry from the University of California, Davis in 1985. Dr. Walker specializes in metal speciation studies, metal cycling in the environment and the fate and transport of chemicals in the vadose zone and saturated zone. Dr. Walker has completed numerous projects for industrial clients and mining companies throughout the United Sates and Canada and has designed several state of the art passive treatment systems for the removal and destruction of various contaminants in surface water and groundwater.


Lara Pucik Christensen
Senior Environmental Scientist/Chief Financial Officer

Ms. Pucik has 8 years of profesional experience in environmental consulting. She holds a B.S. in Chemistry from the University of California, Berkeley and an M.S. in Environmental Engineering from Rice University. Ms. Pucik has published some of the seminal work on the use of Fenton's reagent for the destruction of organic compounds and has designed and overseen numerous projects involving the use of in-situ approaches to groundwater cleanup. Ms. Pucik has completed several recent pilot projects involving the use of novel treatment technologies for the purification of acid mine drainage. She also handles much of the firm's chemical and forensic modeling.


Digna H. Walker, M.Sc., R.N., N.P.
Senior Occupational Health Specialist

Ms. Walker is a professional licensed nurse practitioner and specialist in occupational health. She holds a B.Sc. in Nursing from the University of Phoenix, and an M.S. in Occupational Health from the University of California, San Francisco. Ms. Walker has over 15 years of experience in consulting and medical practice. She has worked extensively with OSHA and MSHA regarding special workplace hazards and safety issues. She recently completed, along with other team members, OSHA's Blood Borne Pathogen document that has received national attention. Ms. Walker handles the firm's health and safety issues and toxicology/epidemiology related projects. Ms. Walker has also recently developed a comprehensive educational program for industrial clients concerning special workplace hazards.


Fred Mueller, P.E.
Senior Engineer

Mr. Mueller is a professional licensed civil engineer. He holds a B.S. in Engineering from the University of Nevada, Reno. Mr. Mueller has 25 years of experience in the environmental consulting business. He was previously employed as a Senior Engineer with the U.S. Army Corp of Engineers. He is responsible for the design and specification of all engineering related projects. Mr. Mueller has a tremendous amount of experience in engineered mine closures, design of caps, and design of above and below ground passive and active contaminant treatment systems. Mr. Mueller has been very active in the cleanup of the Sulfur Bank Mine in Clearlake, CA.


Spike Palmer
Senior Biologist / GIS Specialist

Mr. Palmer has six years of experience in the environmental consulting business. He worked for two years in southern Africa as a Fisheries Biologist for the Ministry of Agriculture in the Kingdom of Swaziland where his responsibilities included the set up of agricultural and game fisheries, biological surveys of the lesser waterways of the country and water quality monitoring. The Nature Conservancy, in conjunction with the California Department of Fish and Game, employed him as a biologist and GIS (Geographic Information System) specialist. Mr. Palmer holds a B.A. in Aquatic Biology from the University of California, Santa Barbara. He is responsible for project issues pertaining to biological resources and handles the firm's mapping and GIS services.

Ellen Bowden
Senior Cultural Anthropologist

Miss Bowden has approximately ten years experience in a range of California archaeological work. Her work has included intense data gathering of pre-historic artifact materials, excavation of historic structures, laboratory processing of field bags, cataloguing, accessioning materials, and investigation of Native American burials and associated artifacts. Since joining Walker and Associates, Miss Bowden has been directing all archaeological investigations associated with the Spenceville Mine Closure Project.