Patrick O. Gwinn
Principal, Toxicology, Health, and Ecological Sciences
M.S., Environmental Studies, University of Massachusetts, 1992
B.S., Industrial Chemistry, Keene State College, Keene, New Hampshire, 1987
Hazardous Waste Operations and Emergency Response 40-Hour Certification (1988; annual refreshers through 2006)
OSHA 40-Hour Health and Safety Training, Hazardous Material Handling (1988)
EPA/Air Waste Management Association Training Course, Air Pathway Analysis at Superfund Sites (1989)
American Chemical Society, Member (1984–present)
Maine Department of Environmental Protection Agency’s Surface Water Ambient Toxics Technical Advisory Group, Appointed (2006–present)
Patrick O. Gwinn Principal, Toxicology, Health, and Ecological Sciences (207) 800-3806 Portland, ME pgwinn@integral-corp.com
Mr. Patrick Gwinn has more than 30 years of environmental consulting experience, providing a broad base of expertise in the areas of human health and ecological risk assessment, water quality, fate and transport dispersion modeling, product stewardship, air toxics sampling, and hazardous waste management. He specializes in managing and conducting human health and ecological risk assessments, site assessments, air quality modeling projects, and remedial investigations for municipalities and the manufacturing and chemical industries. He has modeled the transport, exposure, and risks associated with PCBs, dioxins, chlorinated and aromatic hydrocarbons, aluminum, cadmium, chromium, lead, copper, and other heavy metals. He has been instrumental in developing and leading projects aimed at establishing site-specific ambient water quality criteria and pollutant discharge limits. Mr. Gwinn has served as an expert witness and as a non-testifying expert, providing technical guidance to legal counsel on matters related to organic and inorganic chemical forensics as well as chemical fate and transport. As an expert witness, he has prepared expert reports, undergone pretrial depositions, and provided courtroom testimony. As a non-testifying expert, he has provided technical support to legal counsel prior to, during, and subsequent to depositions as well as during courtroom proceedings.
Following EPA's PFAS Roadmap to Human Health Ambient Water Quality Criteria
Resource
October 26 2022
Occupational Risk Assessment and Exposure Mitigation for Laser Device Emissions
Case Study
November 19 2024
Collecting fish samples to provide analytical data for tracking future sediment remediation efforts
Case Study
March 05 2024
A fish and benthic invertebrate community survey in support of a pre-design investigation
Case Study
March 01 2024Ecological Risk Assessment
Maine Pulp and Paper Industry Representative on the Maine Department of Environmental Protection (DEP) Surface Water Ambient Toxics Technical Advisory Group (SWAT TAG) Appointed by the Commissioner of the Maine DEP to be the Maine Pulp and Paper Industry’s committee representative to the SWAT TAG. The SWAT TAG advises DEP on the design and implementation of a scientifically valid monitoring program that determines the nature, scope, and severity of toxic contamination in the surface waters and fisheries of the state. In addition, the SWAT TAG advises DEP on the implementation of the state’s dioxin monitoring program. Study proposals evaluated by the SWAT TAG include the assessment of dioxin and PFAS in water and aquatic biota, the investigation of the effects of atmospherically transported mercury on eagle reproduction, the assessment of potential estrogenic and immune system effects of industrial and municipal waste discharge on biota, and the collection of data to assess the need for fish consumption advisories.
Development of Site-Specific Ambient Water Quality Criteria for Aluminum, Cadmium, and Copper in Freshwater, Androscoggin River, Maine Project director for the development of water effects ratios (WERs) for aluminum, cadmium, and copper in support of establishing site-specific water quality criteria. On behalf of multiple paper industry clients and their outside counsel, developed and successfully implemented a work plan with scientifically defensible WERs that were approved by state and federal regulators. Data from the studies are being used to support metal-specific WERs and the development of site-specific ambient water quality criteria for aluminum, cadmium, and copper.
Development of Site-Specific Ambient Water Quality Criteria for Copper in Freshwater, Paris Utility District, Paris, Maine Project director for development of acute and chronic site‑specific ambient water quality criteria for copper in the Little Androscoggin River. Worked collaboratively with the utility as well as state and federal regulators to develop a comprehensive 16-month study to collect and analyze water quality data from the Little Androscoggin River, the receiving water body into which the utility discharged. Data were used in EPA’s Copper Biotic Ligand model to determine copper bioavailability in aquatic organisms specific to the waters downstream of the utility. Provided testimony and answered questions on behalf of the utility at a Maine Board of Environmental Protection (BEP) hearing regarding the proposed site-specific criteria and the draft NPDES permit. The BEP ruled unanimously to accept the site-specific water quality criteria, raising the criteria by a factor of 3, and accepting the draft permit as final.
Development of Site-Specific Ambient Water Quality Criteria for Cadmium, Copper, Lead, and Zinc in Freshwater, St. Croix River, Maine Project director for the development of WERs for cadmium, copper, lead and zinc in support of establishing site-specific water quality criteria on the St. Croix River. On behalf of the client, planned and negotiated with the state and federal agencies a work plan to develop scientifically defensible WERs for the four metals. Data derived from the ongoing study will be used to develop site-specific water quality criteria for cadmium, copper, lead, and zinc. The site-specific criteria will inform mill discharge license limits.
Biotic Ligand Modeling of Copper in Freshwater, Baileyville, Maine Project director for development of a site-specific ambient water quality criterion for copper on the St. Croix River. Used the biotic ligand model to develop the site-specific criterion. Results will be used as the basis for alternative discharge permit limits for copper.
Ecological Risk Assessment of Chromium in Baltimore Harbor Sediments, Maryland Conducted a critical review of the basis for the Maryland Department of the Environment’s (MDE) proposed total maximum daily load (TMDL) for chromium in Baltimore Harbor. Demonstrated to the state that the basis of the TMDL listing was not scientifically based, and suggested alternatives for evaluating the potential toxicity, if any, being contributed by chromium in sediments. Prepared white papers that discussed the role of geochemistry in determining the fate of chromium in water and sediment, and evaluated the toxicity of trivalent chromium on benthic-dwelling organisms. Based on this work, MDE agreed that there is not a current basis for developing TMDL allocations for chromium and, as such, will not pursue proposed allocations.
Development of a Strategic Plan for Chromium at the Dundalk Marine Terminal, Baltimore, Maryland Provided expert technical input on a multi-year strategic sampling and analysis plan to assess the potential ecological health risks from hexavalent chromium discharges from portions of the Dundalk Marine Terminal where chromite ore processing residue (COPR) had historically been used for fill material. Media evaluated for sampling included groundwater, stormwater runoff, surface water, sediment, and sediment pore water.
Human Health Risk Assessment
Human Health and Ecological Risk Assessment, Centredale Manor Restoration Project Superfund Site, Rhode Island Provided human health and ecological risk assessment, environmental fate and transport, sampling design, and data quality assurance support services to outside counsel. This Superfund site, based in North Providence, has multiple operating units and contemplated actions, including non-time critical removals and an RI/FS process. The site is associated with human health issues and ecological concerns from the presence of dioxins, furans, PCBs, pesticides, herbicides, and volatile organic compounds (VOCs) in all environmental media, but particularly in riverine and aquatic environments, associated biota, and floodplain soils.
Preparation of Technical Comments on Proposed Federal and State Regulations Reviewed draft rules related to PFAS and prepared technical comments related to the consistency of the draft rules and existing guidance and past practices.
Study of Mercury Sources to the Penobscot River and Comparative Assessment of Human Health Risk from Mercury Discharged from a Former Chlor-alkali Facility, Maine On behalf of outside counsel, estimated the mercury loading to the Penobscot River from all sources, including wet and dry atmospheric deposition, point source discharge, and groundwater flux from landfills associated with a former chlor-alkali facility. Conducted a comparative assessment human health risks associated with pre-remedial and potential post-remedial conditions of the landfills. Conclusions drawn were that the vast majority of mercury to the lower Penobscot River is from global sources, global sources of mercury are not likely to diminish in the future, and selection of a remedial alternative should not necessarily be based on human health risk reduction because post-remedial risks are not discernible when compared to pre-remedial risks.
Human Health and Ecological Evaluations/Risk Assessments of 20 Properties with Chromite Ore Processing Residue, New Jersey Conducted human health risk assessments and baseline ecological evaluations for 20 properties in Hudson County, New Jersey, where COPR had been used for fill material. This was a multiyear effort to characterize potential human health and environmental risks associated with COPR, which was used extensively to fill wetland and low areas in eastern New Jersey. Exposure analyses included residential and recreational incidental ingestion of and dermal contact with soil, inhalation of wind- and vehicle-entrained dust, and contact with puddle water. Endpoints included cancer and noncancer effects as well as the elicitation of allergic contact dermatitis. Risk assessments were submitted to the New Jersey Department of Environment Protection.
Pre-Design Investigation, Centredale Manor Restoration Project Superfund Site, North Providence Rhode Island Project manager for two remedial pre-design investigations: 1) hydrodynamic modeling of Allendale and Lyman Mill Ponds and the Woonasquatucket River, and 2) baseline ecological assessment of the aquatic, floodplain, and upland flora and fauna that may be impacted by remediation of contaminated soil and sediment. Hydrodynamic modeling results will be used to design sediment cover material, and the ecological evaluations will provide information to assist with restoration activities and set the baseline from which remedial efficacy will be determined.
Strategic Risk Assessment and Environmental Consulting, Lower Passaic River Superfund Site, New Jersey Project manager involved with strategic consultation and technical support in human health and ecological risk assessment and conceptual site model development, on behalf of certain parties engaged in the Lower Passaic River Study Area, one of the largest Superfund projects of a contaminated river in the U.S. This work includes providing technical support in the development and review of the human health and ecological risk assessments, and reviewing environmental chemistry, toxicity, bioaccumulation and related test results.
Remedial Risk Management Strategy Model Development, Montana As part of an interdisciplinary team, developed a unique exposure apportionment model and risk management tool for application in the feasibility study for a large and complex CERCLA site. The risk management tool applies EPA risk assessment results along with multiple landscape attributes to identify the areas of higher- and lower-potential human exposures and risk across an operable unit comprising thousands of acres. The resulting spatial models allow for the assessment in the feasibility study of remedial alternatives and the ultimate attainment of risk-based remedial action outcomes.
Human Health and Ecological Risk Assessment, Georgia Principal human health and ecological risk assessment scientist for a wetland containing PAHs, cyanide, and metals. Negotiated the technical approach of the risk assessments with the Georgia Department of Natural Resources under Hazardous Site Response Act. Conducted a fast-tracked baseline human health and ecological risk assessment and developed risk-based cleanup concentrations for surface water, soil, and sediment. Ecological risk assessment included a preliminary risk evaluation and supplementary sediment and surface water toxicity testing. Results of the risk assessment were used to develop time-critical cleanup goals and objectives for a site corrective action plan.
Human Health and Ecological Risk Assessment, Georgia Project manager for human health and terrestrial ecological risk assessment of 100 acres of undeveloped forest and wetland contaminated with PCBs. Provided technical consultation regarding human health and ecological risk assessment and remediation alternatives. Negotiated technical approach for implementation of a post-corrective action risk assessment protocol with state regulatory agencies. Demonstrated that residual levels of PCBs remaining onsite after the corrective action were not significant to human health or ecological risk.
Probabilistic Microenvironment Air Exposure Model Development, Ontario, Canada Manager in charge of critiquing a previously developed personal air exposure model and developing a technically and functionally improved model. The model, named the Canadian Air Personal Exposure Model (CAPEM), was developed as a tool for assessing potential exposures to chemicals in microenvironment ambient air. CAPEM is a probabilistic exposure model that uses age- and Canadian-specific time-activity distributions to estimate the amount of time individuals spend in specific microenvironments at different levels of physical activity. CAPEM combines the time and inhalation rate distributions with distributions of microenvironment vapor concentrations to yield plausible distributions of personal exposures over time.
Human Health and Ecological Risk Assessment, Lexington, Ohio Project manager for a human health and ecological risk assessment for a former circuit manufacturing facility. The human health risk assessment evaluated potential worker, trespasser, and residential exposures to chlorinated solvents in soil, groundwater, and indoor air. Ecological risk to benthic and aquatic organisms was assessed for areas downstream of a groundwater plume discharge point.
Monte Carlo Exposure Analysis to PAHs in Soil, Illinois Prepared a 1-dimensional Monte Carlo analysis of potential exposures to PAHs in soil using the @Risk application in Excel. Data were used to assess the need for property cleanup given its intended use.
Product Risk Assessment, United States Principle-in-charge of an assessment of potential indoor air exposures resulting from the exhaust of a laser-cutting apparatus. Evaluated analytical data and developed a conservative exposure model to estimate upper-end user exposures. Compared modeled exposure concentrations to health-protective, OSHA-permissible, exposure limits to assess the safety to users and provide recommendations to the apparatus manufacturer.
Human Health Risk Assessment, Hoboken, New Jersey Prepared technical comments on an EPA Region 2 human health risk assessment related to incidental ingestion of soil containing mercury released during historical manufacturing processes. Prepared and presented a protocol to EPA Region 2 to assess site-specific bioavailability of mercury in soil using in vitro and chemical speciation analyses.
Human Health Exposure and Risk Assessment, Northeastern U.S. Project manager for an assessment evaluating potential exposure of dioxins, furans, and PCBs introduced to residential and commercial indoor air as the result of combustion.
Product Risk Assessments/California Proposition 65 Compliance Assessment, California Project manager for the assessment of consumer paper product compliance with California’s Proposition 65. For this risk-based assessment, demonstrated that paper used in high-end consumer magazines was in compliance with Prop 65 by estimating the product content and potential worker and consumer exposure to chemicals used in paper manufacturing. This compliance demonstration was conducted to ensure that the labeling requirements of Prop 65 were being adequately addressed. The study’s conclusions mean that labeling or notification is not required for these products.
Product Risk Assessment, Maine Project manager for a project that assessed the potential human and ecological health risks to a new soil amendment product. Evaluated potential risks of the product if used as a flower garden soil amendment and as potting soil amendment for agricultural use. Evaluated the potential for direct contact and indirect contact from potentially leached chemicals. Demonstrated that the new product was not likely to pose a substantial risk to human health or the environment at agronomic loading rates.
Pulp and Paper Mill Sludge Consultation Provided technical support on the historical generation of dioxins and furans at a bleach Kraft pulp mill, as well as on present-day and potential future regulatory compliance, on behalf of a joint venture during the purchase of a U.S. paper mill.
Pulp and Paper Sludge Application Study, U.S. Project manager in charge of back-calculating risk-specific concentrations for 11 chemicals in land-applied pulp and paper sludge. Modified EPA 503 rule methodology for application to pulp and paper residuals. Using fate, transport, and uptake models, evaluated 15 hypothetical human and ecological exposure pathways, and calculated risk-specific threshold concentrations. Results of the analysis were used to assess the potential impact of future state or federal regulatory efforts related to land-applied residuals.
CERCLA Human Health Risk Assessment, Pennsylvania Project scientist and task manager for the preparation of a human health risk assessment for a former transformer manufacturing facility in support of a CERCLA consent agreement. Evaluated residential and industrial exposures to organic and inorganic chemicals in soil, groundwater, surface water, sediment, surface water runoff, and light, nonaqueous phase liquids (LNAPLs). Supported the estimation of indoor and outdoor air impacts from contaminated groundwater, LNAPL, and soil. Provided strategic regulatory consultation regarding human health risk assessment.
RCRA Risk Assessment, New Jersey Project scientist tasked with calculating potential construction worker health risks at a major pharmaceutical manufacturing facility. Estimated vapor-phase and particle-phase emission rates and impacts resulting from excavation of contaminated soil, contaminated groundwater dewatering, and soil storage and handing operations in support of a New Jersey Department of Environmental Protection RCRA facility risk assessment.
Human Health Risk Assessment, Ft. Lauderdale, Florida Task manager responsible for modeling the exposure to volatile chemicals dissolved in household water sources for the Florida Department of Environmental Protection. Modeled hypothetical concentrations of chlorinated solvents that could be pumped into a household water supply system and evaluated the risks to residents exposed to chemicals volatilized during shower or bathtub use. Also prepared an argument that groundwater in the vicinity of the facility was not likely to be a risk to nearby residences because of the saline nature of the aquifer.
Human Health Risk Assessment, Recife, Brazil Conducted a human health risk assessment to determine the hypothetical risks to industrial workers posed by existing conditions within a former lighting manufacturing facility. Recommended remedial actions based on the results of the risk assessment such that risk to future workers would be significantly reduced. This risk assessment resulted in a focused remedial action aimed at reducing future worker health risks.
Human Health Risk Assessment, Pembroke, Illinois Performed baseline public health evaluation for a hazardous waste site. Focused on the identification of potential exposure pathways, evaluation of the pathways for potential public health risks, and determination of appropriate remedial action objectives.
Baseline Human Health Risk Assessment, Indiana Performed baseline risk assessment for three U.S. Air Force hazardous waste sites. Evaluated all contaminants based on physical, chemical, toxicological, and biological characteristics; release mechanisms; and exposure pathways.
Litigation Support
Litigation Support Services, Miles & Stockbridge, Sullivan & Worcester, and Foley Hoag (U.S. District Court, District of Rhode Island, Civil Action 06-218-S) Provided litigation support services on matters related to the origin and fate and transport of chemicals from historical manufacturing operations and waste disposal practices at the Centredale Manor Restoration Project Superfund site. Also, provided litigation support on matters related to the government performance of human health and ecological risk assessments. As part of this project, provide technical direction to legal counsel on matters related to expert testimony, expert report review and rebuttal, deposition support, and Daubert motion development. Provided deposition and in-court support services to counsel on technical matters related to the case. Technical topics supported include human health and ecological risk assessment, chemical fingerprinting of dioxin/furan sources, chemical fate and transport, and chemical manufacturing.
Designated Expert, Industrial Air Emissions Fate and Transport (Sierra Club, Dustin Stafford and Abbie Luman v. Woodville Pellets, United States District Court, District of Eastern Texas Lufkin Division Civil Action No. 9:20-cv-00178) On behalf of defendants, provided expert opinions related to the fate and transport and potential plaintiff exposures to emissions from a wood pellet processing facility in Woodville, Texas. Prepared expert report describing the opinions, data relied on, and methods employed to reach the stated opinions.
Litigation Support, PCB Source Evaluation (William Liebhart and Nancy Liebhart v. SPX Corporation, TRC Environmental Corporation, and Apollo Dismantling Services, LLC, United States District Court for the Western District of Wisconsin, Case No. 16-cv-700) Critically evaluated the plaintiff’s alleged conceptual site model (CSM) for PCB fate and transport resulting from an industrial facility demolition project, and prepared opinions about an alternative CSM based on demolition timing, evaluation of meteorological data recorded during demolition, application of air-entrained particle fate and transport mechanisms, assessment of analytical data, and observations of physical attributes important to CSM validation.
PFAS Air Emissions Modeling Workplan Development, Northeast U.S. Developed a draft air quality modeling plan to assess emissions from an industrial facility. The goal of the dispersion modeling effort is to estimate the bounding estimates and long- and short-term average PFAS air concentrations and wet and dry deposition rates resulting from the emissions.
Litigation Support Services, Preti, Flaherty, Beliveau & Pachios on Behalf of Mallinckrodt U.S., LLC, U.S. District Court, District of Maine, Civil No. 1:00-cv-00069-JAW (Natural Resources Defense Council et al. v. HoltraChem Manufacturing LLC et al.) Provided litigation support services on matters related to the human health and ecological risks to populations of fish and shellfish due to mercury in the lower Penobscot River and Estuary, Maine.
Litigation Support Services, Preti, Flaherty, Beliveau & Pachios (Appeal of Designation of Uncontrolled Hazardous Substance Site and Order Concerning Chlor-alkali Manufacturing Facility, Orrington, Penobscot Co., Maine, Proceedings under MSRA §1365 Uncontrolled Hazardous Substance Site Law) Provided ligation support services on an appeal to the Maine Board of Environmental Protection regarding the Maine Department of Environmental Protection’s selection of a remedy for four closed industrial landfills. Provided technical support on expert report preparation, expert report review and rebuttal report preparation, and trial cross examination preparation.
Designated Expert, Accidental Ammonia Release Dispersion Modeling and Exposure Assessment, Pasco, Washington Conducted air dispersion modeling of an accidental short-term release of ammonia from a tank truck using the INPUFF2 dispersion model and local meteorological data to assess the potential exposure to hypothetical receptors. Provided deposition testimony on the results of the modeling and the implications of the alleged exposures. Soon after the deposition, the case was settled.
Designated Expert, Mining Dust Fate and Transport Modeling, Chemical Fingerprinting (Stephen and Kathy Darney, personally, and on behalf of K.D. and S.D., v. Dragon Products Company, LLC, United States District Court, District of Maine, Civil Action 08-CV-47-P-S) On behalf of a confidential commercial defendant in a civil litigation, derived estimates of mining and slag dust emissions and conducted particle dispersion and deposition modeling of to assess the potential source contribution at several ambient monitoring stations. Utilized locally collected meteorological data to assess the likely contribution of dust at several ambient air sampling stations from the modeled source. Additionally, conducted chemical fingerprinting of household dust and ambient air dust samples using stacked histograms and principal components analysis. Generated an expert report detailing the analyses and opinions derived from those analyses.
Litigation Support, Lowenstein Sandler (Interfaith Community Organization; Lawrence Baker, Martha Webb Herring, Margaret Webb, Rev. Winston Clarke; Margarita Navas v. Honeywell International, Inc., United States District Court, District of New Jersey, Civil Action 95-CV-02097) Provided technical support to Lowenstein Sandler on a civil litigation regarding the “imminent and substantial endangerment to human health and the environment” under RCRA for a chromite ore processing residue site in Hudson County, New Jersey. Worked with counsel during expert and rebuttal report preparation, depositions, and courtroom direct, rebuttal, and surrebuttal testimony.
Litigation Support Services, Sidley & Austin (Maine’s Peoples Alliance and Natural Resources Defense Council, Inc. v. HoltraChem Manufacturing, LLC, and Mallinckrodt, Inc., United States District Court, District of Maine, Civil Action 00-69-B-C) Provided technical support to Sidley & Austin on a civil litigation regarding the “imminent and substantial endangerment to human health and the environment” under RCRA for historical discharges of mercury to the Penobscot River in Maine. Assisted with expert report scope and preparation and rebuttal report preparation and trial cross examination.
Air Quality Modeling
PSD Permitting, Oahu, Hawaii Managed and performed the air quality impact analysis in support of a Prevention of Significant Deterioration of Air Quality (PSD) permit for a major modification of an existing refuse-derived fuel waste-to-energy facility. Evaluated the air quality impacts of emissions from a proposed 900 ton per day mass burn combustion unit, carbon and lime silo baghouses, cooling towers, and truck traffic. Prepared modeling protocol and PSD permit application for State of Hawaii. Created PSD increment consumption and National Ambient Air Quality Standard (NAAQS) emissions databases. Conducted complex terrain modeling using CTSCREEN and AERMOD. Successfully implemented AERMOD using the plume volume mixing ratio method to provide a more realistic assessment of NOx impacts. Also conducted a visibility impairment analysis for the Arizona Memorial.
Dispersion Modeling for Multipathway Risk Assessment, Oahu, Hawaii Conducted air dispersion and atmospheric deposition modeling to estimate atmospheric transport and wet/dry deposition of gaseous and particle-phase/bound chemicals from a refuse-derived fuel combustor and a proposed mass burn unit in support of a multi-pathway risk assessment. Used measured and surrogate dioxin/furan emission estimates coupled with particle-size distribution data to determine the phase (gaseous, particle phase or particle bound) of dioxins/furans for modeling. Used site-specific meteorological data to determine deposition rates of dioxin/furans in flat and complex (elevated) terrain.
Environmental Impacts Assessment of Emissions from Kawaihae-Mamalahoa Connector Expansion, Waimea, Hawaii Conducted emissions and dispersion modeling for a proposed expansion of the Kawaihae-Mamalahoa Connector using Mobile6.2 and CAL3QHC. Evaluated the impact of emissions of NO2, PM10, PM30, and total hydrocarbons as VOCs on ambient air proximate to the proposed roadway expansion.
Dispersion Modeling in Support of a Human Health Risk Assessment, Plymouth, Minnesota Conducted dispersion modeling of VOCs from a proposed research and development laboratory using a modified Minnesota Pollution Control Agency DISPERSE model to assess potential human health impacts of potential facility emissions. Using both screening-level and refined modeling, demonstrated that emissions from the facility would be lower than the Minnesota Department of Health’s health risk values.
Fugitive Dust Evaluation for the Hudson County Chromium Sites, Hudson County, New Jersey As part of the New Jersey Department of Environmental Protection remedial investigation/human health risk assessment process, evaluated the potential for windblown and vehicle entrained emissions of dust from 20 sites containing hexavalent chromium in soil. Developed a methodology to assess the hypothetical generation of a wind- and traffic-entrained dust and, using ISC3ST, modeled the emissions to estimate an ambient air concentration to which a receptor (worker) may potentially be exposed. Using a risk-based approach, back-calculated alternative remediation standards (ARS) for soil which, if achieved, would not result in adverse effects to human receptors. Using this method, developed ARS values that were more realistic and 10 to 100 times greater than the default cleanup standards proposed by the State of New Jersey.
Microenvironmental Exposure Model Development, Canada Developed a probabilistic microenvironmental exposure model called CAPEM. CAPEM uses Canadian-specific time-activity pattern distributions to estimate the amount of time individuals spend in specific microenvironments at different levels of physical activity. Time-activity information is correlated with age- and activity-specific inhalation rates, which, when taken together with chemical air concentration data, result in estimates of chemical exposure. CAPEM includes both a Monte Carlo model and a users’ manual.
Fugitive Dust Assessment, Minnesota Prepared recommendations for an ambient air monitoring program for potential fugitive dust emissions from a mine-tailings storage area.
Plant-Wide Air Toxics and PSD Increment Consumption/NAAQS Compliance Modeling, Aiken, South Carolina Modeled the emissions of 190 air toxics from a tire manufacturing facility to evaluate compliance with the state air toxics regulations. Evaluated the potential impact of doubling the facility on the local air quality by determining the PSD increment consumption of all criteria pollutants. In addition, conducted an NAAQS/SAAQS compliance modeling analysis.
Dispersion Modeling and Preparation of a PSD Permit for a Proposed Automotive Assembly Plant, Canton, Mississippi Conducted time-critical PSD dispersion modeling for a proposed 500,000 vehicle per year automotive manufacturing facility. Developed the modeling protocol and collected emission and structure information to perform dispersion modeling to set the minor baseline levels of NO2 and particulate matter and to assess the potential for NAAQS violations for NO2, particulate matter, and ozone. Conducted building downwash, cavity, and good engineering practice analyses, evaluated potential emission impacts to soil and vegetation, and prepared modeling text for the PSD permit.
PM10 and NOx Emissions Modeling for PSD Permit Application, West Virginia Conducted multiple emission source dispersion modeling in support of a PSD permit application. Using EPA’s Buoyant Line and Point Source model, simulated potential offsite air concentrations from 22 point and two line emission sources at 400 receptor locations. Modeling results indicated no significant deterioration to offsite receptor locations.
State Air Toxics Compliance Permitting, North Kingston, Rhode Island Conducted air dispersion modeling for a new manufacturing line to demonstrate compliance with the Rhode Island Department of Environmental Management air toxics regulations. Prepared permit for state air toxics compliance.
Vehicular Traffic Emissions Impact Assessment, Portland, Maine Assessed the potential for vehicular highway traffic emissions to result in elevated concentrations of criteria pollutants and air toxics at a proposed elementary school location. Conducted an emissions inventory for criteria pollutants and air toxics and modeled those emissions to estimate ambient air concentrations at the proposed school location. Compared the modeled results to health-based criteria to demonstrate that the potential for deleterious health impacts from vehicular emissions are not a concern.
Atmospheric Dispersion and Deposition Modeling of a Resource Recovery Facility and an Ash Landfill for Use in a Multipathway Risk Assessment, Honolulu, Hawaii Evaluated the potential emission of vapor- and gaseous-phase chemicals from daily operations at a resource recovery facility and its associated ash landfill. Estimated long-term average air concentrations and atmospheric deposition rates for use in a multipathway risk assessment.
Technical Review of Maine Department of Health Services Report on Chemical Assessment and Ranking Project, Lewiston, Maine Provided a technical review and assessment of the Maine Department of Human Services (MDHS) draft report on chemical assessment and ranking project. Conducted site specific dispersion modeling, hypothetical exposure assessment, and risk calculations to demonstrate that emissions from the facility do not pose a significant risk to the general public. Based on this finding, prepared comments to MDHS recommending that the facilities relative risk rank of 10 should, in fact, be zero.
Preparation of State Air Emissions License for a Turbine Manufacturing Facility, Bangor, Maine Performed an emission inventory for the facility and prepared the license renewal application. Conducted onsite survey of fuel storage tank vents and delivery systems, boilers, generators, heating units, cutting, grinding, welding, and other metal fabricating processes and developed a plant-wide emissions inventory for criteria pollutants and hazardous air pollutants. The emissions inventory developed as part of this effort demonstrated that the source was a true minor source, and not a synthetic minor source as previously licensed. This modification in source status reduced the record keeping requirement of the plant personnel.
Vapor-Phase PCB Air Dispersion Modeling, Northeastern U.S. Project manager responsible for the determination of hypothetical risks associated with volatilization of PCBs from the water column of a major river system in the northeastern U.S. Modeled the dispersion of PCB vapor from the river water surface to hypothetical residences along and inland from the river’s edge. Using the highest modeled ambient air PCB concentration, determined that risks associated with inhalation were insignificant.
Remedial Option Evaluation, PCB Site, Massachusetts Task manager of a CERCLA remedial design for a PCB site. Estimated potential emissions of PCB-laden dust and vapor-phase chlorinated solvents from the proposed remedial action of site soils. Using air dispersion modeling, evaluated potential air concentrations of site chemicals at neighboring residences, and evaluated the effect of three emission reduction techniques on the modeled air concentrations. Evaluated the effectiveness of dust and vapor suppression foam, windshields, and the use of a temporary enclosure. Information from this analysis was used to design the remediation of onsite soils and to establish the placement of offsite air monitoring stations.
Human Exposure to Airborne Particles Containing PCBs, Anaheim, California Using local meteorological data and site-specific soils data, estimated the concentration of entrained particles in air. By applying site-specific information regarding soils and groundcover, calculated airborne particle concentrations by particle size fraction. Applied physiologic parameters describing the fate of the particle size fractions in the respiratory tract as a function of activity patterns to determine the bioavailable portion of the airborne dust. Estimated particle exposure to the dust based on activities performed at the facility and its general surroundings.
Area Source Dispersion Modeling of a Former Landfill and Aeration Pond, Carrolton, Kentucky In support of a RCRA facility investigation, modeled emissions of hazardous air pollutants from a former landfill and an aeration pond to assess the potential risks to hypothetical facility fence-line receptors. Previous air sampling measurements at the source areas indicated that air concentrations of several VOCs were in excess of risk-based guidance values. However, dispersion modeling of the emissions to hypothetical fence-line receptors showed that the annual average air concentrations at the fence line would be several orders of magnitude below the risk-based guidelines. This assessment was used to eliminate the air pathway from further analysis for these sources in the RCRA facility investigation.
Lead Emissions Evaluation, Michigan Conducted dispersion modeling of lead emissions from a steel manufacturing facility to determine compliance with the NAAQS for lead. Modeled the emissions of lead assuming several configurations to identify the most cost-effective system.
Hazardous Air Pollutants Delisting Petition, U.S. Air dispersion modeling scientist on a team responsible for removing ethylene glycol monobutyl ether (EGBE) from the glycol ethers definition as specified by Title III of the Clean Air Act Amendment (CAAA) of 1990. Collected EGBE use and emission data from manufacturing facilities nationwide, electronic databases, and literature. Evaluated the potential impact of current and future emissions of EGBE on nearest offsite receptors, and researched past, current, and future production and use rates of EGBE. Evaluated the effect of delisting of EGBE on Title I of the CAAA as it pertains to volatile organic emissions from coatings and ink applications and ground-level ozone concentrations.
Semiconductor Manufacture Emissions Dispersion Modeling, Colorado Conducted air dispersion modeling of chemicals being emitted as the result of semiconductor manufacturing. Emissions were released from point and area emission sources. Estimated highest potential offsite concentrations and highest potential concentrations are nearby sensitive receptors for a risk-based screening.
New Hampshire Air Toxics Compliance Evaluation, Concord, New Hampshire Conducted tiered modeling of emissions solvents, metals, and particles to determine whether an Air National Guard facility was in compliance with the state’s air toxics regulations.
Control Technology Assessment, Landfill Superfund Site, North Smithfield, Rhode Island Performed ambient air and source monitoring and conducted dispersion modeling to determine destruction efficiencies and offsite impacts for three alternative treatment technologies for a landfill Superfund site. Technologies evaluated included incineration, internal combustion, and enclosed flaring.
Catastrophic Atmospheric Release Analysis, Baird & McGuire Superfund Site, Holbrook, Massachusetts Conducted an analysis of a catastrophic release from a hazardous waste incinerator at the Baird & McGuire Superfund site. The analysis showed that the instantaneous release would not result in significant chronic impacts, but that acute effects may be experienced in close proximity to the facility. Data from the analysis was used to modify emergency response planning for the facility.
Emissions Modeling and Air Toxics Permitting, Rhode Island Air dispersion modeler responsible for air toxics permitting of a biomedical incinerator. Employed building downwash and cavity effect analyses, as well as screening-level and refined Gaussian dispersion modeling techniques to determine the potential short-term and chronic air concentrations at offsite receptor locations. Data from this analysis was used as input for a human health risk assessment and a state air toxics regulatory review.
Landfill Gas Migration Study, South Kingstown, Rhode Island Designed and performed study of landfill gas migration to determine the potential impact on neighboring residences at the Rose Hill Landfill Superfund site. Estimated landfill gas emissions to ambient air and the potential impacts to surrounding residences using measurements of chemical flux to air and computer modeling techniques.
Incinerator Performance Specification Preparation, Baird & McGuire Superfund Site, Holbrook, Massachusetts Project scientist and air dispersion modeler for the Baird & McGuire Superfund site. Prepared performance specifications for an air monitoring system and dispersion modeling protocols for the incineration of contaminated soils. Also provided consulting support for matters related to the startup and operational testing of the onsite incinerator, air monitor stations, and meteorological stations. Conducted sampling of all waste streams from the incineration process to determine whether destruction and removal efficiencies and emissions were in compliance with the required design specifications.
Historical Tank Farm Emission Modeling, New York Conducted air dispersion modeling of VOCs from a historical tank farm area in support of a RCRA facility investigation risk assessment. Modeled emissions using ISC3ST to estimate short- and long-term air concentrations at hypothetical receptor locations both onsite and in neighboring areas.
Incinerator Emissions Modeling, Texas Designed and conducted air dispersion and wet/dry depositional modeling of dioxins and furans from four industrial waste incinerators. Developed congener-specific annual average ambient air concentrations for dioxins and furans, as well as wet and dry deposition rates for particle-bound congeners. The generated information was used in a multi-pathway analysis to evaluate the hypothetical human and ecological health risks associated with the incinerator emissions.
Emissions Evaluation, Air Modeling Task, and Risk Assessment, Nassau County, New York Project manager responsible for emissions estimates and air dispersion modeling of airborne chemicals released from a 54-mgd sewage treatment plant. This task was performed to support a human health risk evaluation and epidemiological study for the Nassau County Department of Health. Estimated and modeled emissions from the following wastewater treatment plant processes: primary infiltration, primary settling, waste scavenging, grit screening, dewatering, sludge thickening, aeration, final settling and power generation. Evaluated local building downwash and cavity effects. Data generated from the modeling was used to locate offsite air sampling stations, assess inhalation risks, determine the potential for malodorous impacts to the surrounding community, and to identify appropriate study areas for an ongoing epidemiological study of the local population.
Particle and Vapor Emission Estimates and Transport Modeling, Eastern New Jersey Conducted detailed particle and vapor phase emission estimation resulting from construction operations and vehicular traffic at a manufacturing facility. Emission estimates were coupled with local meteorological data in a short-term dispersion model to estimate local air concentrations. Air concentration data were used to demonstrate that nearby workers would not be subject to unacceptable health risks from such emissions.
Particle and Vapor Emission Estimates and Transport Modeling, Massachusetts Using site‑specific soil data, demonstrated that particle emissions resulting from vehicular traffic and construction machinery operation would not result in unacceptable health risks for workers. Performed particle emission calculations to estimate emission rates resulting from excavation, stockpiling, and truck transport of soil containing heavy metals and volatile and semivolatile organic metals.
Gwinn, P., and M. Henning. 2023. Maine’s PFAS regulations—important dates are coming. JDSupra. April 18. https://www.jdsupra.com/legalnews/maine-s-pfas-regulations-important-3686658.
Clausen, J., M. Gray, S. Clough, P. Gwinn, and R. Cramer. 2009. Assessing the sensitivity of quantitative structural activity analysis models for evaluating new military compounds. Water Air Soil Pollut. 202(1-4):141–147.
Keenan, R.E., P.O. Gwinn, J.D. Schell, E.A. Carlson, and J.B. Silkworth. 2008. Application of nonlinear dose-response methods based on mode of action shows reduced cancer risks from PCBs. Organohalogen Compounds 70:430–433.
Rifkin, E., P. Gwinn, and E. Bouwer. 2004. Total chromium is not a good indicator of toxicity. Environ. Sci. Toxicol. 38(14)257A–272A.
Keenan, R.E., J.M. Hamblen, J.B. Silkworth, M.N. Gray, P.O. Gwinn, and S.B. Hamilton. 2003. An empirical evaluation of the potency of dioxin toxic equivalents (TEQs) in several PCB mixtures. Organohalogen Compounds 65:312–315.
Gwinn, P.O., and W. Taylor. 2017. Emerging issues for wastewater. Maine Rural Water Association (MRWA) 37th Annual Technical Conference, Bangor, ME. December.
Gwinn, P.O., J. Samuelian, and E. Rand. 2017. Application of the biotic ligand model to derive acute and chronic site-specific water quality criteria for copper in the Little Androscoggin River. AEHS 33rd Annual International Conference on Soils, Sediments, Water, and Energy, Amherst, MA. October.
Gwinn, P.O., E. Rand, and J. Samuelian. 2016. Androscoggin River water-effect ratios and proposed site-specific criteria – Determinations for aluminum, copper, and cadmium. New England Water Environment Association (NEWEA) Annual Meeting, Boston, MA. January.
Gwinn, P.O., J. Samuelian, and E. Rand. 2016. Application of the biotic ligand model to derive acute and chronic site-specific water quality criteria for copper in the Little Androscoggin River, Maine. NEWEA Annual Meeting, Boston, MA. January.
Gwinn, P.O., E. Rand, and J. Samuelian. 2015. Is it appropriate to compare pore water concentrations to ambient water quality criteria? Sediment Management Working Group, Arlington, VA. December 2.
Gwinn, P.O. 2015. Regulatory chemical risk assessment from Superfund to contaminants of emerging concern—Where have we been and where are we going? Environmental & Energy Technology Council of Maine (E2Tech), Portland, ME. November.
Gwinn, P.O. 2015. Wood that it WER—Water-effect ratios for aluminum, cadmium, and copper. National Council for Air and Stream Improvement, Northern Regional Meeting, Portland, ME. May.
Gwinn, P.O. 2008. Application of the biotic ligand model for copper. NCASI Northern Regional Meeting, Auburn, ME. May 21.
Keenan, R.E., P.O. Gwinn, J.D. Schell, E.A. Carlson, and J.B. Silkworth. 2008. Application of nonlinear dose-response methods based on mode of action for PCBs. Society for Risk Analysis Annual Meeting, Boston, MA. Abstract W3-C2.
Keenan, R.E., P.O. Gwinn, E.R. Algeo, and P.D. Anderson. 2008. Characterizing and interpreting fish consumption rates for developing human health water quality criteria. (Abstract) Fifth Annual Conference on Integrating Water Resources Management, University of Massachusetts. April 8.
Bouwer, E., E. Rifkin, and P. Gwinn. 2005. A reassessment of chromium sediment quality values. The Eighth International In-Situ and On-Site Bioremediation Symposium, Baltimore, MD. June 6–9.
Keenan, R.E., J.M. Hamblen, J.B. Silkworth, M.N. Gray, P.O. Gwinn, and S.B. Hamilton. 2004. An empirical evaluation of the potency of dioxin toxic equivalents (TEQs) in four PCB mixtures. Toxicological Sciences (Supplement) 78: Abstract No. 1783.
Keenan, R.E., J.M. Hamblen, J.B. Silkworth, M.N. Gray, P.O. Gwinn, and S.B. Hamilton. 2003. An empirical evaluation of the potency of dioxin toxic equivalents (TEQs) in several PCB mixtures. Organohalogen Compounds 65: 312-315. Proceedings Dioxin 2003—the 23rd International Symposium on Halogenated Environmental Organic Pollutants and Persistent Organic Pollutants, Boston, MA. August 24–29.
Alsop, W.R., J.H. Samuelian, and P.O. Gwinn. 2001. Evaluation of alternate approaches to deriving exposure point concentrations for ecological risk assessments. Poster/platform presented at the Society for Risk Analysis Conference, Seattle, WA. December 2–5.
Alsop, W.R., P.O. Gwinn, J.H. Samuelian, and S. Clough. 2001. Development of a realistic screening tool for evaluating potential ecological risks associated with land-application of pulp and paper mill biosolids. Poster/platform presented at the Society for Risk Analysis Conference, Seattle, WA. December 2–5.
Gwinn, P.O., J. Rothrock, and R.E. Keenan. 1998. Application of USEPA’s Part 503 Methodology to pulp and paper industry residuals. National Council of the Paper Industry for Air and Stream Improvement, Central-Lakes Regional Meeting. May 12–13.
Gwinn, P.O., N.M. Shear, J. Rothrock, M.H. Henning, S.A. Lewis, J.C. Banks and J. Harrington. 1998. Title III delisting of ethylene glycol monobutyl ether—An assessment of emissions and health effects of a hazardous air pollutant. Air and Waste Management Association Annual Meeting Proceedings, San Diego, CA. June 14–19.
Shear, N.M., P.O. Gwinn, J. Rothrock, M.H. Henning, S.A. Lewis, and J.C. Banks. 1998. Title III delisting of ethylene glycol monobutyl ether—A weight-of-evidence approach for evaluating an emissions inventory. Air and Waste Management Association, San Diego, CA. June 14–18.
Maritato, M.C., P.O. Gwinn, C.S. Schmidt, and E.S. Ebert. 1997. Application of exposure- and risk-based principles in the development of industrial remediation goals for a former manufacturing facility in eastern Brazil. Water Environment Federation Industrial Wastes Technical Conference. March 3–5.
