Kat Ridolfi
Senior Consultant
M.S., Aquatic Resource Ecology and Management, University of Michigan, Ann Arbor, Michigan, 2006
B.S., Environmental Economics and Policy, University of California, Berkeley, California, 2002
Hazardous Waste Operations and Emergency Response 40-Hour Certification (2019)
First Aid and CPR Certified (2019)
Kat Ridolfi Senior Consultant (415) 787-6308 Santa Rosa, CA kridolfi@integral-corp.com
Ms. Kat Ridolfi is an aquatic ecologist and experienced consultant. She consistently provides clients with a clear strategy for addressing complex environmental contaminant issues based on high-quality technical analysis. She leads teams of scientists and engineers in developing expert reports for cost allocation strategies and conducting field investigations to characterize and evaluate aquatic systems contaminated by per- and polyfluoroalkyl substances (PFAS), PCBs, mercury, dioxins, and other contaminants using a wide range of scientific tools. Success for Ms. Ridolfi means finding the right solution for the particular project using the highest standards of technical integrity to meet the needs of regulatory agencies while protecting the environment. She effectively communicates technical findings to the client, regulators, and stakeholders in a meaningful and digestible manner to ensure that realistic expectations are shared among all parties. Clients view Ms. Ridolfi as a trusted advisor and professional able to get things done. She keeps complicated projects on schedule and within a set budget, while maintaining close communication with regulators, attorneys, and other parties.
Ms. Ridolfi also serves as Integral’s regional advisor for the Pacific region, coordinating business development efforts for staff in California and Hawaii and working with the other three regional advisors to implement companywide objectives for business development.
- Cost Allocation
- Litigation Support
- Regulatory Compliance
- Risk Assessment
- Planning and Permitting
- Contaminated Sediments
- Environmental Impact Assessment
Cost Allocation
Portland Harbor Superfund Site, Active Steel Mill, Portland, Oregon Project manager responsible for managing a complex scope, including remedial design and cost allocation at a sediment site involving 100+ participating and nonparticipating parties. Lead author of a series of expert reports for allocation related to stormwater and sewer systems involving extensive analysis of data and mass load calculations for a range of contaminants. Managed a multiyear in-water field investigation to determine nature and extent of contamination. Extensive collaboration with attorneys, EPA, state regulatory agency, and client to report results and to evaluate appropriate remedial actions for the site.
City of Port Angeles, Washington Coauthored an expert report focused on the analysis of the City’s stormwater and sewer systems, other party’s pulp mill discharges to water, and air emissions. Communicated findings to end client and attorneys, and participated in collaborative teams with attorneys.
Small Industrial Facility, Portland Harbor Superfund Site, Portland, Oregon Provided a variety of technical and strategic risk consulting services for a small industrial facility located on the Willamette River that was formerly occupied by a U.S. Navy shipbuilding and repair facility. The chief constituent of concern for the greater Portland Harbor site was PCBs; there were also localized upland concerns about zinc in stormwater, and benzene, toluene, ethylbenzene, and xylenes in groundwater at this client’s facility. Reviewed all RI/FS materials, and provided comments and strategy support to client for allocations. Advised on uplands stormwater sampling program and worked with Oregon Department of Environmental Quality and local field crew to implement approved monitoring program and report to state.
Former Industrial Plant, Berry’s Creek and Universal Oil Products Superfund Sites, East Rutherford, New Jersey Provided a variety of technical services for Universal Oil Products located on Ackerman’s Creek, a tributary to Berry’s Creek. The main constituents of concern for the site were PCBs and lead. The site had its own CERCLA designation as Universal Oil Products, and was part of the larger Berry’s Creek site. Researched historical operational practices of client and neighboring sites, as well as sewer/stormwater routing and other relevant site characteristics to support development of a contaminant fate and transport model for Ackerman’s Creek.
Litigation Support
Confidential Statewide Natural Resource Damages Litigation, Multiple States in the Northeast United States Project manager of team supporting a testifying expert in defense of several statewide claims for damages to natural resources from historical releases of PFAS with potential injury to ecological services and human uses of resources.
Confidential Human Health Risk Assessment Litigation, Many Cities and States throughout the United States Contributed technical analyses and writing to a series of expert reports assessing risk to human health related to fish consumption from PCB-contaminated waterbodies (often many water bodies per case). Technical topics included fish consumption advisories, beneficial uses of water bodies, impaired water bodies, contaminated sites, and regulatory basis for water quality criteria and risk methods. Developed conceptual site models for recreational exposure scenarios.
Superfund Site, New York City Provided technical support on a variety of tasks for a site in the early stages of investigation. Directed the development of a database of PRPs at the site to assess the potential allocation and/or liability shares of the client, in relationship to contributions that can be attributed to other PRPs. Data included historical information on site use and predecessor companies, any spills or contaminant releases, and information on chemicals/materials used. Provided overall strategic risk management consulting related to allocation and liability/contribution issues and prepared client for potential future litigation related to contaminant fate and transport model.
Superfund Site, Southeastern United States Reviewed financial documents, provided comments on neighboring site RI/FS documents, reviewed ecological risk assessment, and evaluated development of remedial goals on neighboring site in preparation for litigation regarding conflicting remedial goals and liability for contamination.
Regulatory Compliance
RCRA and CERCLA Regulatory Compliance for a Former DDT Manufacturing Facility, Ciba-Geigy Superfund Site, McIntosh, Alabama This 1,500-acre facility, which manufactures industrial and agricultural chemicals, was considered closed under CERCLA but is still participating in EPA- and state-RCRA-managed monitoring and reporting efforts. Provided regulatory compliance services for RCRA permit application, state visual site inspection, EPA five-year reviews, Explanation of Significant Differences, and long-term implementation and effectiveness monitoring and reporting for sediments in the floodplain and groundwater. Additional work included ongoing identification, delineation, and risk management of other potential source areas.
District of Columbia Department of Energy and Environment Municipal Separate Storm Sewer System (MS4) Monitoring Program and Integrated Surface Water Quality Monitoring Program, Washington, DC Developed a revised stormwater monitoring program required as part of the District’s MS4 permit and a coordinated program that covered all surface water quality monitoring programs for the city into one plan (The Integrated Surface Water Quality Monitoring Program). The revised monitoring plan was developed to meet the following objectives: ensure compliance with MS4 monitoring requirements; evaluate MS4 program effectiveness; and provide support for any recommended changes in MS4 program activities. Additional tasks included statistical analysis of historical stormwater outfall monitoring data and a comprehensive inventory of data used to develop all TMDLs in the District of Columbia. These data sets were used to assess compliance with waste load allocations, to assess the effectiveness of current monitoring stations/programs, and to provide recommendations for the consolidated TMDL implementation plan.
Statewide Mercury and PCBs TMDLs for the State of Michigan Developed TMDLs for thousands of Michigan inland lakes and streams, impaired due to atmospheric deposition of mercury and PCBs, in close collaboration with EPA Region 5 and the Michigan Department of Environmental Quality. Atmospheric pollutant load reductions described in the TMDLs were based on a regional analysis that considered geographic variability in deposition and accumulation in fish tissue. Ultimately, the TMDLs described the atmospheric mercury and PCB load reductions necessary to achieve Clean Water Act targets and address all required TMDL elements. The TMDLs were approved by EPA Region 5 in September 2018.
Mercury and PCBs TMDLs for the Nearshore Segment of Lake Michigan, Illinois Developed TMDLs for the 56 waterbody segments that drain to Lake Michigan (covering about 100 square miles within Lake and Cook counties, Illinois) that were impaired from atmospheric deposition of mercury. Atmospheric pollutant load reductions described in the TMDLs were based on a regional analysis that considered geographic variability in deposition and accumulation in fish tissue. Ultimately, the TMDLs described the atmospheric mercury and PCB load reductions necessary to achieve Clean Water Act targets and address all required TMDL elements. The TMDLs only addressed reductions from Illinois sources.
Implementation Plans for Mercury and PCBs TMDLs for San Francisco Bay, California Served as project manager and field lead for effort to develop best management practices (BMPs) appropriate for meeting implementation goals for mercury and PCBs in San Francisco Bay. Collected soil and sediment samples from hundreds of source areas throughout the bay watershed and oversaw processing and analysis.
Comprehensive Plan to Reduce PCBs in the Spokane River, Spokane, Washington Developed source assessment and conceptual model for PCBs impacting the Spokane River. Work involved compiling data from a variety of state and local agencies, conducting gap analysis, identifying potential sources within the watershed, and developing a conceptual model of fate, transport, and pathways of PCBs. With input from a large variety of stakeholders, completed an inventory of BMPs to reduce PCB loads to the river, analyzed cost effectiveness, and prioritized BMPs appropriate for the watershed. The goal of the Comprehensive Plan was to bring the Spokane River into compliance with applicable water quality standards for PCBs.
Bacteria Translator for Bacteria TMDLs, Washington, DC Developed a translator to convert bacteria TMDLs from fecal coliform to E. coli as mandated by new water quality standards. Work included review of other state translator methods, analysis of paired bacteria data collected in DC, evaluation of the ability of the DC monitoring strategy to support new water quality guidelines, and recommendation of a translator to use in DC.
Risk Assessment
Human Health Risk Assessment for Potential Expansion of a Former DDT Manufacturing Facility, Ciba-Geigy Superfund Site, McIntosh, Alabama Assessed potential risk to human health in a small area of this manufacturing facility following an investigation that revealed elevated levels of a range of organic contaminants in soil and groundwater. Analysis included several pathways, receptors, and contaminants to calculate cumulative carcinogenic and non-carcinogenic risk for the property. Risk-based target levels were used because cumulative target risk was exceeded for some pathways.
Field Investigation and Ecological Risk Assessment for Mercury in Tomales Bay, Tomales, California Developed an impairment assessment report for Tomales Bay, which is contaminated with mercury from historical mining waste in the 561 km2-watershed. The report analyzed the risks to ecological health that may have resulted from improper disposal of mercury mining waste, including the spatial distribution of elevated mercury in sediment, fish tissue, and water; temporal trends in mercury-contaminated sediment; and risk to the aquatic food web. Led all work, including estimating a numeric target for the protection of wildlife; collecting fish, sediment, shellfish, and water samples; and developing a source analysis. The San Francisco Bay Regional Water Quality Control Board subsequently used this work to develop a total maximum daily load (TMDL) for mercury, which was approved by EPA.
Planning and Permitting
Multiple Contracts for California Department of Transportation, Northern California Project manager supporting team of biologists developing aquatic resources delineation reports, identifying offsite mitigation locations, designing mitigation projects, and developing mitigation and monitoring plans for onsite and offsite riparian restoration and enhancement activities connected to roadways and bridges managed by Caltrans.
Contaminated Sediments
Portland Harbor Superfund Site, Active Steel Mill, Portland, Oregon Project manager responsible for managing a complex scope, including remedial design and cost allocation at a sediment site involving 100+ participating and nonparticipating parties. Lead author of a series of expert reports for allocation related to stormwater and sewer systems involving extensive analysis of data and mass load calculations for a range of contaminants. Managed a multiyear in-water field investigation to determine nature and extent of contamination. Extensive collaboration with attorneys, EPA, state regulatory agency, and client to report results and to evaluate appropriate remedial actions for the site.
City of Port Angeles, Washington Coauthored an expert report focused on the analysis of the City’s stormwater and sewer systems, other party’s pulp mill discharges to water, and air emissions. Communicated findings to end client and attorneys, and participated in collaborative teams with attorneys.
Small Industrial Facility, Portland Harbor Superfund Site, Portland, Oregon Provided a variety of technical and strategic risk consulting services for a small industrial facility located on the Willamette River that was formerly occupied by a U.S. Navy shipbuilding and repair facility. The chief constituent of concern for the greater Portland Harbor site was PCBs; there were also localized upland concerns about zinc in stormwater, and benzene, toluene, ethylbenzene, and xylenes in groundwater at this client’s facility. Reviewed all RI/FS materials, and provided comments and strategy support to client for allocations. Advised on uplands stormwater sampling program and worked with Oregon Department of Environmental Quality and local field crew to implement approved monitoring program and report to state.
Former Industrial Plant, Berry’s Creek and Universal Oil Products Superfund Sites, East Rutherford, New Jersey Provided a variety of technical services for Universal Oil Products located on Ackerman’s Creek, a tributary to Berry’s Creek. The main constituents of concern for the site were PCBs and lead. The site had its own CERCLA designation as Universal Oil Products, and was part of the larger Berry’s Creek site. Researched historical operational practices of client and neighboring sites, as well as sewer/stormwater routing and other relevant site characteristics to support development of a contaminant fate and transport model for Ackerman’s Creek.
Environmental Impact Assessment
CEQA for PAH Remediation Site, San Francisco, California Developed an initial study under the California Environmental Quality Act (CEQA) for remediation of PAH-contaminated sediments in the intertidal and subtidal areas near multiple pier areas in San Francisco Bay.
Environmental Assessment and NEPA Review for Restoration of Springhouse Run, Washington, DC Developed environmental assessment for restoration of a stream in the National Arboretum. Work required extensive consultation with the State Historic Preservation Office and oversight of two comprehensive archaeological surveys to determine presence of archaeological artifacts in the site.
Cumulative Impact Assessment for the Proposed Onsite Wastewater Treatment System Discharge at the Northern California Youth Regional Treatment Center, Yolo County, California Conducted the nitrogen loading analysis for the proposed onsite wastewater treatment system. The nitrogen loading analysis evaluated the effect of nitrogen discharge to groundwater using an annual mass-balance method.
Ridolfi, K. 2016. Nonpoint source pollution. In: Encyclopedia of Estuaries. M.J. Kennish (ed.). Springer Science.
Greenfield, B.K., A.R. Melwani, R.M. Allen, D.G. Slotton, S.M. Ayers, H. Hintelmann, B. Dimock, J.D. Blum, G.E. Gehrke, A. Jahn, K. Harrold, K. Ridolfi, J. Griswold, and M.B. Sandheinrich. 2012. A stratified probabilistic survey of biosentinel mercury and mercury isotopes in San Francisco Bay, CA USA. Sci. Tot. Environ. 444: 591–601.
Ridolfi, K., N. Ott, L. Baker, M. Edwards, E. Pendleton, and D. Silva. 2023. Demonstrating sediment recovery in Portland Harbor through PCB temporal trends. Platform presentation at the Eleventh International Conference on the Remediation and Management of Contaminated Sediments, Austin, TX. January 9–12.
Ridolfi, K. 2016. What can we learn from other Comprehensive Plans: San Francisco Bay PCB TMDL. Spokane River Regional Toxics Task Force Technical Workshop, Spokane, WA.
Ridolfi, K. 2010. Assessing impairment of Tomales Bay due to mercury. Bay-Delta Science Conference, Sacramento, CA.
Ridolfi, K. 2010. Assessing impairment of Tomales Bay due to mercury. National Water Quality Monitoring Council Conference, Denver, CO.
Ridolfi, K. 2009. How healthy is your watershed? Recent progress on developing indicators of ecological health and the potential applications in the San Francisco Bay Area and beyond. Salmonid Restoration Federation’s 27th Annual Salmonid Restoration Conference: Elements of Watershed Restoration, Santa Cruz, CA.
