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Maryann Welsch

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Maryann Welsch
Consultant

Maryann Welsch

Consultant (207) 800-3808 Portland, ME mwelsch@integral-corp.com

Ms. Maryann Welsch is an environmental scientist with more than 20 years of experience working with industrial clients of regulated community and government entities to assess and reduce environmental risks and damage. She has provided strategic support and technical analyses on a variety of chemicals, including per- and polyfluoroalkyl substances (PFAS), petroleum compounds, dioxins, PCBs, PAHs, and metals to help clients and regulators understand the significance of ecological exposures and the potential for risks. As a project manager, Ms. Welsch collaborates with multidisciplinary project teams to deliver results in support of remedial investigations, feasibility studies, ecological risk assessments, natural resource damage assessments (NRDAs), ecosystem restoration, sediment management, and expert reporting.

Beneficial Use of Contaminated Sediments: Focused Review of Treatment Technologies

Poster

January 30 2025

Ecological Risk Assessment

Former Landfill, Chatham, New Jersey Derived preliminary remedial goals protective of wildlife based on the evaluations performed for the ecological risk assessment. Supported the remedial design in terms of ecological relevance and protection of high-quality habitats present on site.
Chemical Manufacturing Facility, New Jersey Conducted an ecological risk evaluation of aquatic and wetland resources based on exposures to PFAS at a waterfront facility. Identified ecologically relevant screening values for PFAS compounds without promulgated benchmarks based on reviews of toxicological literature. Designed a field sampling plan to evaluate exposures of aquatic resources via soil, sediment, and surface water.
Former Manufacturing Site, Ohio Provided litigation support in a matter of alleged ecological risks. Incorporated site-specific data to refine the risks in a baseline ecological risk assessment and to derive realistic preliminary remedial goals.
Former Wood Treating Facility, Superfund Site, Navassa, North Carolina Prepared an update to a baseline ecological risk assessment of a freshwater marsh adjacent to a facility with a focus on invertebrate-consuming birds and benthic invertebrates. Evaluated the bioavailability of PAHs in sediment and porewater using the equilibrium partitioning approach. Derived preliminary remedial goals protective of ecological receptors based on sediment and porewater chemistry.
Chemical Manufacturing Facility, Maine Evaluated the potential for ecological risks based on modeled exposures of aquatic organisms to an organic chemical released to the surface waters of a nearby river.
Former Landfill Superfund Site, New Jersey Supported a site investigation at a CERCLA site involving ecological exposures in a creek adjacent to the landfill. Prepared a field sampling plan to support the ecological risk assessment involving the collection of sediment, hydric soil, and surface water.
Klamath Basin National Wildlife Refuge Complex, California and Oregon Managed the review of environmental risks related to herbicide and pesticide applications to agricultural fields in support of an integrated pest management program on federal lease lands of the Klamath Basin National Wildlife Refuge Complex. The program is administered jointly by U.S. Fish and Wildlife Service and Bureau of Land Management.
Former Electric Power Facility, Lower Anacostia River, Washington, DC Conducted a baseline ecological risk assessment for aquatic receptors associated with river sediments adjacent to the facility. Evaluated potential risks to benthic invertebrates using multiple lines of evidence, including sediment bioassays, a macroinvertebrate community survey, sediment and porewater chemistry (particularly PCBs), and metals. Performed statistical analyses for the comparison of site-related risks relative to urban background reference conditions.
Flood Control System, Minneapolis, Minnesota Supported a baseline ecological risk assessment for aquatic receptors in a flood control system in the Tri-Lakes area. Developed site-specific bioaccumulation models of PFAS compounds for an aquatic trophic transfer model in support of an ecological risk assessment. Conducted trophic transfer modeling for herbivorous mammals and birds based on site-specific plant tissue concentrations.
Manufactured Gas Plant, Lower Anacostia River, Washington, DC Supported a baseline ecological risk assessment for aquatic receptors associated with river sediments adjacent to a plant. Evaluated potential risks to benthic invertebrates using multiple lines of evidence, including sediment bioassays, a macroinvertebrate community survey, and sediment chemistry, including PAHs bioavailability based on the equilibrium partitioning approach. Conducted a background evaluation using a reference envelope approach to support the sediment quality triad evaluation.
Electric Power Generating Stations, Raritan River, New Jersey Performed ecological risk assessments following New Jersey Department of Environmental Protection guidelines for aquatic receptors associated with river sediments adjacent to two generating stations on the Raritan River. Lines of evidence evaluated included benchmark screening and wildlife dietary exposure modeling. Developed sampling programs and evaluated regional background sediment conditions to support the investigations.
Military Facilities in Rhode Island, Maine, Maryland, and Washington, DC Conducted screening-level and baseline ecological risk assessments of natural resources, including soils, groundwater, surface water, sediment, and porewater at or adjacent to current and former military facilities. Line-of-evidence evaluations included a benchmark screening, sediment invertebrate toxicity testing, invertebrate community surveys, dietary dose modeling for wildlife exposures, and comparisons with background levels.
Generating Station, Mount Vernon, Indiana Performed an ecological risk assessment of modeled air deposition concentrations in soils, sediments, and surface water for permit compliance. Line-of-evidence evaluations included a benchmark screening and aquatic and terrestrial dietary dose modeling for wildlife exposures based on current and future concentrations expected from emissions.
Petrochemical Storage and Distribution Facility, Linden, New Jersey Conducted an ecological risk assessment following New Jersey Department of Environmental Protection guidance for aquatic receptors associated with wetland and river sediments. Lines of evidence evaluated included benchmark screening and wildlife dietary exposure modeling. Developed sampling programs for the collection of site and background samples and evaluated regional background sediment conditions to support the investigations.
Former Industrial Facility, Wilmington, Massachusetts Conducted a baseline ecological risk assessment of soil, groundwater, sediment, and surface waters following Massachusetts Contingency Plan risk assessment guidance in support of a Permanent Solution Statement. Lines of evidence evaluated included benchmark screening, dietary dose modeling for wildlife exposures, and comparisons with background levels.
Power Plant and Generating Station, Farmington, New Mexico Supported an ecological risk assessment of modeled air deposition concentrations in soil, sediment, and surface water for an environmental impact statement. Lines of evidence evaluated included benchmark screening and aquatic and terrestrial dietary dose modeling for wildlife exposures based on current and future concentrations expected from emissions.
Lower Passaic River, Newark, New Jersey Supported an ecological risk assessment. Developed and implemented field sampling programs for the habitat, birds, fish, and benthic invertebrate tissue.
Lower Willamette River, Portland, Oregon Supported an ecological risk assessment. Developed and implemented field sampling programs for the collection of abiotic and biotic samples.
Lower Duwamish Waterway, Seattle, Washington Supported an ecological risk assessment. Developed and implemented field sampling programs for fish, benthic invertebrates, and clam tissue for chemical and biological analyses.

Natural Resource Damage Assessment

Confidential Site, Delaware Provided strategic support for the settlement of natural resource damages based on claims for potential injuries related to losses of wetlands, damages to soils of forested habitats and surface waters in adjacent waterbodies, and lost recreational uses and cultural resources. Provided technical analyses of potential damages and participated in communications with the trustees, which included presentations regarding potential damage and restoration opportunities.
Statewide NRDA, New Mexico Provided litigation support to evaluate potential natural resource liability related to PCBs. Supported a technical analysis of potential lost ecological services to terrestrial and aquatic wildlife. Managed a multidisciplinary team to evaluate claims related to contaminant sources and pathways and forensic evaluations.
Former Mine, New Mexico Evaluated potential injuries at a mine site in northern New Mexico based on metal exposures to terrestrial wildlife, which included an evaluation of baseline conditions. Habitat equivalency analysis (HEA) was used to estimate injury. Technical results will be summarized in an expert report to support ongoing litigation.
Former Industrial Facility, Rhode Island Assessed potential injuries to ecological resources using the HEA model and considering baseline conditions. Supported discussions with trustees regarding analytical data to evaluate the resources and establish a path forward for a cooperative process.
Statewide NRDA, Maryland Provided litigation support to evaluate potential natural resource liability related to PCBs. Evaluations included the assessment of aquatic and terrestrial receptors and fish consumption advisories.
Industrial Facility, Mid-Atlantic United States Evaluated potential ecological service losses to soils, groundwater, surface water, and sediments associated with historical industrial waste disposal using the HEA model. Assisted client with agency negotiations and litigation support.
Former Industrial Facility, Lower Anacostia River, Washington, DC Assessed potential ecological service losses to surface water and sediments using the HEA model. Evaluated a range of restoration actions such as the creation of mussel habitat to compensate for potential losses. Coordinated the development of a restoration project associated with the remedial design. Assisted client with presentations of both potential damages and compensatory restoration during agency negotiations.
Former Industrial Facilities, Mid-Atlantic United States For several former facilities, conducted technical analyses of potential ecological service losses related to chemical exposures in soil, surface water, and sediment using the HEA model. One of the cases involved the evaluation of potential for future risks to wildlife based on various restoration concepts. Supported the clients in negotiations with the trustees and the design of compensatory restoration projects.
Electrical Power Station, Washington, DC For a mineral oil spill in a tributary to the Anacostia River, conducted an analysis of lost ecological services to macroinvertebrates and fish based on the comparison to urban background levels, forensic analyses, and a fate and transport analysis of PAHs related to the spill. Designed a field sampling program for the collection of site-specific biological community data (aquatic invertebrates and fish). Prepared a report presenting the findings that was submitted to the regulatory agency for resolution of the potential damages.
Electrical Power Station, Arlington, Virginia Assessed potential ecological service losses to macroinvertebrates and fish following a small mineral oil spill to the Potomac River based on an evaluation of PAHs in sediment and biological data (macroinvertebrate surveys and wildlife mortalities) and forensic, fate, and transport analyses. Used the HEA model to inform technical and strategic approaches and potential compensatory restoration scenarios.
Hylebos Waterway, Tacoma, Washington Developed a stream and wetland restoration project on a tributary of Hylebos Waterway in Commencement Bay to compensate for natural resource injuries to fish (juvenile salmonids) and aquatic birds. Applied the HEA model to the range of restoration credits. Assisted client in negotiations with the trustee group. Procured necessary permits and developed the postconstruction monitoring program for compliance with permit requirements and the consent decree. Also conducted required site assessments to satisfy permitting requirements including wetland delineation, stream channel, and habitat assessments.

Contaminated Sediments

Review of Treatment Technologies of Dredged Materials in Support of Beneficial Uses, United States Authored a white paper on behalf of the Sediment Management Work Group presenting a literature review of treatment technologies used for preparing dredged materials for beneficial use applications such as beach replenishment or roadway fill.
Former Industrial Sites, Western United States Provided litigation support on PCB contamination in river sediments related to alleged upland sources at the former industrial sites. Evaluated historical land uses, abiotic data, and transport mechanisms of contaminants from upland facilities downgradient to river sediments.
Pre-design Investigation, Superfund Site, Rhode Island Evaluated the results of a benthic macroinvertebrate community survey of the site and reference locations to establish baseline conditions prior to the remediation of the river sediments.
Long-Term Monitoring Data Review, New Bedford, Massachusetts Performed a review of 28 years of sediment PCB chemical concentrations and benthic infaunal community metrics data to evaluate spatial and temporal trends. Explored the potential for relationships between sediment chemistry and the benthic community. Determined methodologies for evaluating the effectiveness of sediment remediation over the long term.

Welsch, M., S. Bentsen, and M. Henning. 2025. Beneficial use of contaminated sediments: critical review of treatment technologies. Integrated Environmental Assessment and Management. doi.org/10.1093/inteam/vjaf046.

Henning, M., M. Welsch, and X. Santiago. 2023. Expert Analysis: Enviro justice can help cos. with regulators, communities. Law360, New York, NY. March 9. https://www.law360.com/articles/1583250/enviro-justice-can-help-cos-with-regulators-communities.

Henning, M., and M. Welsch. 2023. Opportunities for meaningful environmental justice actions by the regulated sector. JDSupra. July 12. https://www.jdsupra.com/legalnews/opportunities-for-meaningful-9693652.

Yavitt, J., J. Burtis, K.A. Smemo, and M. Welsch. 2018. Plot-scale spatial variability of methane, respiration, and net nitrogen mineralization in muck-soil wetlands across a land-use gradient. Geoderma 315:11–19.

Welsch, M., and J.B. Yavitt. 2007. Microbial CO2 production, CH4 dynamics and nitrogen in a wetland soil (New York State, USA) associated with three plant species (Typha, Lythrum, Phalaris). Eur. J. Soil Sci. 58:1493–1505.

Welsch, M., and J.B. Yavitt. 2003. Early stages of decay of Lythrum salicaria and Typha latifolia in a standing-dead position. Aquat. Bot. 75:45–57.

Welsch, M., S. Bentsen, and M. Henning. 2025. Beneficial use of contaminated sediments: Focused review of treatment technologies. 12th International Conference on the Remediation and Management of Contaminated Sediments. Tampa, Florida. January.

Barra, B., H. Jones, and M. Welsch. 2023. Long-term ecological monitoring of New Bedford Harbor over 28 years. 11th International Conference on the Remediation and Management of Contaminated Sediments. Austin, Texas. January.

Welsch, M., C. Archer, H. Loso, C. Puopolo, H. Patterson, H. Temme, and A. Gorski. 2021. Developing site-specific uptake factor relationships for a PFAS investigation and risk assessment at a flood control system in Minnesota. 42nd Annual Meeting of SETAC North America, Ecological Risk Assessment for Contaminants of Emerging Concern. November.

Archer, C., H. Loso, H. Patterson, C. Puopolo, M. Welsch, H. Temme, and A. Gorski. 2021. PFAS investigation and risk assessment at a flood control system in Minnesota. 42nd Annual Meeting of SETAC North America, Ecological Risk Assessment for Contaminants of Emerging Concern. November.

Welsch, M., B. Ruffle, H. Jones, J. Bleiler, R. Damera, and F. Mahvi. 2015. Evaluating risks to benthic invertebrates and fish at an urban waterfront site on the Lower Anacostia River. North Atlantic Chapter of SETAC Meeting.

Hurley, K., L. Saban, and M. Welsch. 2009. Practical considerations of implementing a natural resources damage assessment restoration project. National Conference on Ecosystem Restoration, Los Angeles, CA.

Welsch, M. 2007. Ecological factors to consider when selecting a mitigation site. Law Seminars International Workshop on Mitigation and Conservation Banking. Seattle, WA.

Welsch, M., T. Deshler, S. Pierce, and S. Reiersgaard. 2004. Monitoring changes in wetland habitat functions following the introduction of wastewater effluent from cheese manufacturing. SETAC 25th Annual Meeting, Portland, OR.

Johns, D.M., L. Saban, M. Welsch, M. Luxon, D. Pelletier, and C. Jackson. 2004. Use of habitat suitability index models to scale site-specific injury for multiple resources. SETAC 25th Annual Meeting, Portland, OR.

Johns, D.M., L. Saban, M. Luxon, and M. Welsch. 2003. Establishing habitat valuations for HEA. SETAC 24th Annual Meeting, Austin, TX.

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