William Schew
William A. Schew, Ph.D.
Senior Managing Scientist
Ecological & Biological Sciences
  • Philadelphia

Dr. Schew draws on over 30 years of knowledge gained in industry and academia to help solve complex environmental problems. Dr. Schew is a nationally recognized expert in the fields of human health and ecological risk assessment, vapor intrusion/indoor air assessment, quantitative exposure modeling, contaminant fate and transport, stochastic modeling, and environmental physiology. He has worked at many high-profile hazardous waste sites throughout the country, including major contaminated sediment sites such as the Lower Passaic River Study Area and the Housatonic River.

Dr. Schew uses an interdisciplinary approach in developing Conceptual Site Models (CSMs) to attack complex environmental problems. Dr. Schew is adept at developing pro-client environmental site strategies by integrating technical, regulatory and political approaches to find practical solutions that satisfy business goals while meeting regulatory requirements. He is a skilled facilitator and often serves as an industry liaison to regulatory agencies where he excels in company-stakeholder dialogue. Dr. Schew has served as a trusted advisor to many industrial clients and has represented the interests and been a staunch client advocate for numerous PRP groups. Among his accomplishments, Dr. Schew has successfully negotiated alternative water quality, soil, and sediment cleanup criteria. Of particular interest to him are the impacts of non-chemical stressors in urban rivers and the contribution of background environmental concentrations of chemicals in sediment and soil to both human health and ecological risk.

Dr. Schew also has significant experience in conducting human health and ecological evaluations at CERCLA and RCRA sites, chemical source attribution, advanced data analysis using stochastic modeling and advanced statistical techniques, and endangered species investigations and population management.

Dr. Schew received his Ph.D. from the University of Pennsylvania and has had academic appointments at Princeton University, the University of Pennsylvania, and West Chester University. He was awarded a 3-year fellowship by the National Institute of Health for his research at the UCLA Medical Center, which focused on intestinal nutrient uptake in animal models. He has authored numerous peer-reviewed paper and technical presentations. Dr. Schew also worked with industry and government leaders in developing EPA's Ecological Soil Screening Level Guidance.

Dr. Schew has been active in litigation support for more than 15 years. He has provided technical support to legal teams in the form of expert testimony at depositions, hearings, and trials, written opinion and affidavit, as well as document review and site inspection. His testimony has been admitted in court proceedings as an expert in human health risk assessment, ecological risk assessment, quantitative environmental modeling, and assessing vapor intrusion.


  • Ph.D., Biology, University of Pennsylvania, 1995
  • M.S., Biology, California State University, Long Beach, 1990
  • B.S., Biology, University of Connecticut, 1985
  • NIH Post-Doctoral Fellow, 1996


Sinha P, Lambert MB, Schew WA, Sawant A, Kolwaite KJ, Strode SA. Greenhouse gas emissions from U.S. Institutions of Higher Education. Journal of the Air & Waste Management Association 2010; 60:568–573.

Sinha P, Lambert MB, Schew WA. Evaluation of a risk-based environmental hot spot delineation algorithm. Journal of Hazardous Materials 2007; 149:338–345.

Sinha P, Kriegner CJ, Schew WA, Kaczmar SW, Traister M, Wilson D. Regulatory policy governing cadmium-telluride photovoltaics: A case study contrasting life cycle management with the precautionary principle. Energy Policy 2007; 36:381–387.

Schew WA, Ricklefs RE. Developmental plasticity in growing birds. In: Avian Growth and Development: Evolution within the Altricial-Precocial Spectrum. Starck JM, Ricklefs RE (eds), Oxford University Press, 1998.

Schew WA, McNabb FMA, Scanes CG. Comparison of the ontogenesis of thyroid hormones, growth hormone, and insulin-like growth factor-i in ad libitum and food restricted (Altricial) European Starling and (Precocial) Japanese Quail chicks. General and Comparative Endocrinology 1996; 101:304–316.

Lane JS, Schew WA, Todd KE, Lam MM, Chandler CF, Diamond J, Ashley SW. Growth hormone increases mucosal nutrient transport efficiency following intestinal resection. Gastroenterology 1997; 112(4) Suppl: A378

Ricklefs RE, Schew WA. Feeding stochasticity and lipid accumulation by nestling petrels. Functional Ecology 1994; 8:159–170. 

Schew WA, McNabb FMA. Thyroid ontogeny of altrical starlings and the effects of food restriction in altrical starlings and precocial quail. American Zoologist 1994; 34:120A.

Schew, WA, Collins CT, Harvey TE. Comparative Growth of Caspian terns (Sterna caspia) in two coastal California environments. Colonial Waterbirds 1994; 17:153–159.

Collins, CT, Schew WA, Burkett EE. Elegant terns breeding in Orange County, California. American Birds 1991; 45:393–395.

Schew WA, Collins CT. Annual and within year variability in growth patterns of black skimmer (Rynchops niger) chicks. Eighth International Symposium of Marine Biology, Dailey M, Bertsch H (eds), Ensenada, Baja California, Mexico, 1991.

Schew, WA, and Collins CT. Age and sex determination of black skimmer chicks. Journal of Field Ornithology 1990; 61:174–179.

Schew WA, Richards SW. Roseate tern behavior in modified nest sites. Connecticut Natural History Notes 1989; 3:1–4.

Richards SW, Schew WA. Food and feeding rates of roseate tern (Sterna dougallii) chick on Faulkner Island, CT. Connecticut Warbler 1989; 9:1–5.

Selected Published Abstracts

Schew WA, Roe C. Vapor intrusion update: The changing landscape. Proceeding of the 2012 Pennsylvania Bar Institute, Environmental Law Forum, PBI 2012; Harrisburg, PA.

Selected Presentations

Schew WA, Roe C, Miano S. Dealing with vapor intrusion in redevelopment: Understanding and Managing Risks. 2015 Pennsylvania Brownfields Conference, Erie, PA, May 2015.

Schew WA. 2013 – The year for substantial changes to state and federal vapor intrusion guidance? Pennsylvania Bar Institute Environmental Law Forum, April 2013.

Schew WA, Roe C. Vapor Intrusion update: The changing landscape. Pennsylvania Bar Institute Environmental Law Forum, April 2012.

Kriegner CJ, Sinha P, Schew WA, Cragin D. Development of ecotoxicity safety factors for pharmaceuticals using population modeling. Society for Environmental Toxicology and Chemistry, Milwaukee, WI, 2007.

Kriegner CJ, Sinha P, Schew WA, Trumbull VL. Using STELLA to model population-level ecological risk. Society for Environmental Toxicology and Chemistry, Milwaukee, WI, 2007.

Schew WA. Leadership dialogue on open space in Philadelphia. Philadelphia Convention Center, Philadelphia, PA, 2007.

Kaczmar SW, Schew WA. Integration of habitat creation and enhancement into a hazardous waste site restoration program. SETAC, Montréal, Canada. 2006.

Schew WA. Ecological risk assessment: A primer. Arcadia University, Glenside, PA. 2006. 

Schew, WA. An Industry Perspective on Vapor Intrusion. Society of Women Environmental Professionals Seminar Series –Environmental Liability Protection: PA vs. NJ. Philadelphia, PA, 2005.

Schew WA. Vapor intrusion – Emerging issues and perspectives. Presentation with MDM&C to DuPont, Wilmington, DE, 2004.

Schew WA. Avian responses to undernutrition: Adaptive response and developmental constraint. American Society of Zoologists, St. Louis, MO, 1995.

Schew WA, McNabb FMA. Thyroid ontogeny of altricial starlings and the effects of food restriction in altricial starlings and precocial quail. American Society of Zoologists. St. Louis, MO, 1995.

Schew WA Vapor intrusion – The basics. Vapor Intrusion Seminar, Conshohocken, PA. March 30, 2005.

Schew WA. Detection and Quantitation Limit Roundtable Discussion Panel participant, National Environmental Monitoring Conference, Arlington, VA. 2003.

Schew WA. Shifting paradigms in human health and ecological risk assessment. Arcadia University, Glenside, PA. 2002.

Schew WA. The application of human health and ecological risk assessments within regulatory frameworks, Arcadia University, Glenside, PA, 2001.

Schew WA. Innovative advances in ecological risk assessment. University of Pennsylvania, Philadelphia, PA, 2001.

Schew WA. Natural resource damage assessments: A critical review of methods and practical applications. University of Pennsylvania, Philadelphia, PA, 2000.

Schew WA. Physiological responses to environmental stress: A bird’s eye view. Swarthmore College, 1997.

Schew WA. Evolution, life histories, and reaction norms. Annual Physiological Ecology Meeting, Bishop, CA, 1996.

Schew WA. Oh, grow up. . . Growth and developmental responses of European starling and Japanese quail chicks to undernutrition. American Society of Zoologists, Washington, DC, 1995.

Schew WA and Scanes CG. Ontogenetic patterns of circulating concentrations of growth hormone and insulin-like growth factor-i in Japanese quail and European starling. American Society of Zoology, St. Louis, MO, 1995.

Schew WA. Developmental plasticity in growing birds. Round Table Discussion at the XXI International Ornithological Congress, Vienna Austria, 1994.

Schew WA. Evolutionary considerations for developmental plasticity in growing birds. XXI International Ornithological Congress, Vienna Austria, 1994.

Schew WA. Metabolic responses of European starling and Japanese quail chicks to undernutrition: Developmental constraints vs. adaptive responses. AOU, COS, and WOS Joint Meeting. Missoula, MT, 1994.

Schew WA. To grow or not to grow: A look at the developmental plasticity in birds. California State University, Long Beach, CA, 1994.

Schew WA. Field ecology in an urban setting. Philadelphia Scholars Program for Teacher Education, Philadelphia, PA, 1992.

Schew WA, Ricklefs RE. Feeding stochasticity and lipid accumulation by Leach’s storm-petrels. American Ornithologists’ Union, Montréal, Canada, 1991.

Schew WA. Ecological and environmental determinants of growth patterns in terns. American Ornithologists’ Union. Los Angeles, CA, 1990.

Collins CT, Schew WA. Growth patterns in California least terns: Phenotypic constraints and environmental variability. Colonial Waterbird Society, Key Largo, FL, 1989.

Schew WA. Growth of Caspian terns in central and southern California. American Ornithologists’ Union. Fayetteville, AR, 1988.

Schew WA, Collins CT. Age and sex determination of black skimmer chicks. Pacific Seabird Group. Asilomar, CA, 1987.

Prior Experience

Vice President, O’Brien & Gere, Inc., 2003–2015

Technical Director, Environmental Standards, Inc., 1997–2003

Sole Proprietor, Avitech Research Associates, 1985–1991

Project Director, Little Harbor Laboratory, 1983–1985

Academic Appointments

Lecturer – Princeton University, Department of Ecology and Evolutionary Biology, 1995

Lecturer – University of Pennsylvania, Department of Biology, 1994–1995

Lecturer – West Chester University, Department Biology, 1996–1997

Project Experience

Exposure Assessment and Risk Assessment

Represented the collective interests of a large PRP group in matters related to risk assessment, chemical fate and transport, characterization of urban background conditions, assessment of chemical inputs from stormwater outfalls and CSO outfalls, pollutant reduction through stormwater BMPs and green infrastructure among others. Provided strategic guidance, acted as a lead technical reviewer and client advocate for the group. Also providing opinions, observations and recommendations for activities that supported the interests of the group and assisted in developing alternate approaches for risk characterization and cost allocation.

Provided litigation support in a South Carolina case involving SCDHEC’s selection of an inappropriate remedial action plan at the plaintiff’s expense. Reevaluated the SCDHEC's flawed Human Health and Ecological Risk Assessments and developed a strong case demonstrating that necessary remedial action required only minimal excavation of "hot-spot" areas to reduce ecological risks within acceptable ranges.

Provided a 3rd party review of a human health risk assessment of arsenic in NY. Corroborated the results of the risk assessment and provided technical suggestions to bolster the client’s argument to undertake limited remediation.

Provided litigation support for a case involving widespread Cr+6 contamination. Developed an independent assessment of the potential health risks posed and performed a critical review of EPA’s development of Site-Specific soil screening levels for Cr+6. Demonstrated that the USEPA methodology for developing the Cr+6 soil screening levels was flawed and thus the screening levels were incorrect.

Provided litigation support regarding groundwater affected by releases of chlorinated VOCs from a nearby Superfund Site, which had migrated onto the property where a new elementary school was proposed. Prepared a technical report evaluating the potential exposures to elementary school children to chlorinated VOCs from the vapor intrusion pathway at the proposed location. Represented the client effectively at contentious public meetings that included concerned parents.

Represented a PRP group in the development of the ecological and human health risk assessments for a former solvent recycling facility. The facility had soil and overburden/bedrock groundwater impacted with numerous volatile organic compounds and metals.

Provided litigation support regarding potential human health impacts resulting from exposing sediment during and following a dam removal action. Sediments were impacted by hexavalent chromium from a nearby Superfund Site; however, the levels of contamination were shown to be acceptable and not a threat to human health or the environment.

Led a Public Health and Environmental Risk Evaluation for a RCRA Corrective Action. Evaluated contaminant fate and transport, developed the site conceptual models and conducted the ecological and human health risk assessments for the site. The facility bordered the Housatonic River and included sediments impacted by contaminated groundwater as well as from soil runoff. The affected areas also included significant freshwater and tidal wetlands and tributaries to the Housatonic River. The ecological risk assessment focused on impacts to the river sediments and associated wetlands, transitional zones, and upland terrestrial habitat from pesticides, hexavalent chromium and other metals, PAHs, PCBs other organic compounds.

Conducted a human health and an ecological risk assessment and evaluated potential natural resource damages for 235 acres USEPA Region 2 CERCLA Site. Provided technical leadership for the development of PRGs and remedial alternatives.

Led a focused human health and ecological risk evaluation of lead shot and lead shot fragments at a former shooting range bordering the Housatonic River. Risks to human health were evaluated using a stochastic modeling based on measured size ranges of potentially ingestible lead fragments found in riverbank soils. Conducted an ecological assessment to evaluate potential impacts to local waterfowl from lead shot ingestion. Riverbank and sediment sample results were used to show that the risk to human receptors was within acceptable range and the potential for adverse effects to wildlife were minimal. This effort avoided the complex and costly removal of tree-lined riverbank soils along the affected river.

Conducted an evaluation of potential human health and ecological impacts from lead shot at a 400-acre private shooting club that had been operating since 1907. Lead shot, which had been used in shooting activities since the inception of the club, had accumulated in several areas of the property. Utilized site-specific conditions, including soil and stream pH to show minimal environmental impacts. 

Led an ecological risk assessment for 7,000-acre USEPA Region 4 RCRA facility with numerous SWMUs contaminated with organic pesticides, BTEX compounds, PAHs, PCBs, mercury, and other metals. Evaluated impacts to the aquatic community and resident wildlife from exposure to contaminated sediments. Conducted sampling of fishes and benthic invertebrates for tissue residue analysis and developed ecological food-chain exposure models to evaluate risks posed to higher trophic level receptors. 

Conducted a human health and ecological risk assessment at a USEPA Region 5 RCRA facility. Developed human health and ecological Conceptual Site Models, evaluated fate and transport of chemicals through Site media, including contaminant loading to a large urban river. Identified areas for "hot spot" removal that resulted in a reduction in the scope of the proposed remedial action. 

Conducted human health and ecological risk assessments for 5 operable units of a large USEPA Region 2 Superfund Site. Established common receptors and negotiated a streamlined process that included regulator agreement on major exposure assumptions.

Environmental Forensics

Assessed the nexus of a former manufacturing facility to a USEPA Region 2 Superfund site. Reviewed historical information, including former operations, site characteristics, environmental release information, ecological risk assessment documents, and other documentation provided by EPA in their General Notice Letter. The degree of alleged nexus between the site and the river was not supported by the available information.

Evaluated the origin of metals and anthropogenic PAHs deposited in wetland within a large Superfund Site. Established that the majority of both metals and PAHs originated from nearby former MGP sites and landfills adjacent to the site.

Provided an evaluation of regional Dieldrin groundwater contamination. Established that the likely source of the Dieldrin was from a nearby former landfill and not attributable to a local school.

Developed detailed conceptual site models for a USEPA Region 2 CERCLA site. Chemicals identified in surface water of a creek and nearby river, and site wetland sediment and surface soil were evaluated for potential links with chemicals present in Site impoundments or Site groundwater. 

Biological and Ecological Studies

Oversaw a cooperative study of the regional metapopulation dynamics and ecology of endangered Roseate Terns (Sterna dougallii), Common Terns (Sterna hirundo), and Herring Gulls (Larus argentatus) as part of a long-term metapopulation project. Studies used formal capture/recapture models to test various hypotheses about geographic and temporal variation in adult and juvenile survival, recruitment and age-specific breeding, and fidelity/intercolony movement rates. 

Conducted post-oil spill NRDA impact studies of the endangered bird species nesting in wetlands in Huntington Beach and Upper Newport Bay, California following the American Trader oil spill. Monitored breeding success along California Coast from Port Hueneme to Camp Pendleton, California.

Assessed the suitability of mitigation alternatives for destruction of endangered species foraging areas in the Port of Los Angeles, California.

Conducted a radiotelemetric study of juvenile Great-blue Heron dispersal in Orange County, California. Monitored juvenile movement throughout southern California.

Conducted long-term monitoring of California Least Tern breeding success in southern California, including intervention using habitat modification and depredation efforts.

Served as expert witness in the evaluation of the ecological consequences resulting from a proposed WWTP discharge to the headwaters of a HQ stream. Established that the proposed discharge would lead to increased sedimentation, increases in-stream temperatures and flow rates, all of which would adversely impact the habitat for native brook trout and adversely impact the healthy benthic community structure. The planned introduction of wastewater into the stream was prevented successfully.

Natural Resource Damage Assessment

Evaluated the impact of American Trader oil spill on existing wetlands and on wetlands restoration efforts; focused on avian, plant, and mammalian communities.

Served as the RP’s manager of the wildlife capture and rehabilitation center during the Athos I oil spill response. Prioritized response efforts, to maximize recovery and minimize environmental damage. Oversaw collection of wildlife damage information used in evaluation of Natural Resource Damages. 

Evaluated a federal NRD claim on behalf of an industrial client for alleged impacts to a large urban river. Reviewed information regarding former operations, site characteristics, environmental release information, ecological risk assessment documents, and other documentation and established that the alleged nexus between the former facility and the river was de minimis.

Developed a series of NRD offset plans for a CERCLA facility along the Raritan River that were consistent with priorities of Federal, State and local stakeholders. Plan consisted of floodplain modifications to reduce flooding, fishing, birdwatching, and other recreational amenities, and connection to public transportation. 

Prepared an expert report related to an industrial ammonia release into an Exceptional Value stream. Evaluated the short-term and potential long-term impacts of the release. Provided an evaluation of potential Natural Resource Damages and developed a path forward designed to minimize potential damages. Documented negligible ecological impacts, which resulted in minimal fines imposed on the client.

Vapor Intrusion

Provided expert opinions regarding exposure to TCE, PCE, and benzene via the vapor intrusion pathway and the nexus to pancreatic cancer. Developed a supportable Conceptual Site Model for the vapor intrusion pathway. Using this CSM, demonstrated that the levels to which the plaintiff may have been exposed and the length and duration of the alleged exposure were negligible. Also demonstrated that the injuries experienced by the Plaintiff were not related to her alleged exposure to VOCs.

Supported litigation related to human exposure to volatile compounds following a catastrophic gasoline release from a service station. Developed a novel retrospective approach for estimating historical indoor air concentrations of BTEX constituents originating from affected groundwater underlying the impacted homes. Although this approach was considered novel with respect to the science of vapor intrusion at the time, this retrospective approach was subsequently recognized by the Court using the Frye Standard. 

Provided litigation support related to human health exposure to chlorinated compounds via the vapor intrusion pathway. Evaluated potential risk to human health from exposure to indoor air contaminants for a number of exposure scenarios that were developed based on the business activities of the tenants. Provide the client with a better understanding of potential liabilities associated with their tenants’ exposure to indoor air and identified weaknesses in the existing data. 

Developed an expert report that evaluated human exposure and vapor intrusion of BTEX compounds into a convenience store impacted by vapors emanating from historical releases from an attached service station. Demonstrated definitively that the final remedy, implemented on behalf of the State of Oklahoma, was not effective in mitigating vapor intrusion into the service station/convenience store. After reviewing this report, the State reversed their position and approved an alternative remedy that effectively controlled the vapor intrusion pathway.

Developed a modification of the J&E Model that accounted for retardation of mass flux through dirt basement floors. This modification was accepted by regulators and the analysis showed that the VI pathway did not pose an unacceptable risk to residents located above the groundwater plume.



  • Ph.D., Biology, University of Pennsylvania, 1995
  • M.S., Biology, California State University, Long Beach, 1990
  • B.S., Biology, University of Connecticut, 1985
  • NIH Post-Doctoral Fellow, 1996