Emerging Contaminants Summit
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Emerging Contaminants Summit
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Shalene Thomas Shalene Thomas
Emerging Contaminants Program Manager

Ms. Shalene Thomas, PMP, is the Emerging Contaminant Program Manager for Wood. She has more than 20 years of experience in environmental consulting that includes 10 years of experience supporting per- and polyfluoroalkyl substance (PFAS) evaluations. She has extensive program and project management, human health risk assessment, data management, GIS and 3D visualization and animation experience and has supported State, Federal and industrial clients with PFAS evaluations. She serves as Wood’s PFAS Work Group Lead and has supported PFAS projects in 32 different states in 9 of the 10 USEPA regions as well as in Australia and Canada.


Regional Management Approach to Sustainable Drinking Water; Addressing PFAS Contamination across Fourteen Communities

In 2004, PFAS were first detected as contaminating drinking water supplies in parts of the East Metropolitan Area of Minneapolis, MN. Most of the contamination was traced to four dumps or landfills. From the 1950s through the early 1970s, 3M disposed of wastes from PFAS manufacturing primarily in disposal sites in Oakdale and Woodbury, at the 3M manufacturing facility in Cottage Grove, and at the Washington County landfill. Following its first detection, MPCA began sampling groundwater monitoring wells at the disposal sites and nearby private wells, and the MDH sampled city municipal wells in Washington County to identify drinking-water supplies with PFAS. Sampling soon expanded to a wider area of the East Metropolitan Area. In 2010, Minnesota filed a lawsuit against 3M to recover damages for injuries to Natural Resources Damage lawsuit that charged 3M with damaging the environment from releasing PFAS chemicals in the East Metropolitan Area. On February 20, 2018, the State of Minnesota settled its Natural Resources Damage lawsuit against 3M in return for a settlement of $850 million to address the approximately 150 square mile groundwater plume contamination affecting more than 140,000 residents in 14 communities of the East Metro. The objective of this presentation is to discuss the technical approach used in the development of a Conceptual Drinking Water Supply Plan (CDWSP) for the East Metro area. The CDWSP is currently being developed and is intended to define the path to providing clean, sustainable drinking water in the East Metropolitan Area that addresses each community’s needs now and in the future. The plan considers both public water systems and private wells, using a region-wide approach.
Several phases of the technical approach will be discussed including:

  1. The compilation of regional information and community profiling
  2. The identification and evaluation of drinking water supply improvement options
  3. The development, screening and evaluation of concept-level projects, and
  4. The development, evaluation and recommendation of scenarios.

Stakeholder communication and management will also be presented as well as how the drinking water system modeling, groundwater modeling, concept-level projects and scenarios were developed and integrated to drive the comprehensive regional approach.

Learning Objectives:

  1. Learn and understand how to approach contaminated drinking water using a comprehensive regional approach
  2. Learn what components go into development of a Conceptual Drinking Water Supply Plan
  3. Understand how to evaluate drinking water improvement options using drinking water and groundwater modeling tools.


Programmatic Approach to Management of PFAS; One State’s Strategy

In 2002, the Minnesota Department of Health (MDH) partnered with the Minnesota Pollution control Agency (MPCA) to investigate PFAS in Minnesota. This work began with ground water and drinking water investigations at and near the 3M Cottage Grove plant and related legacy waste disposal sites in Washington County (east of St. Paul). Since 2002, MDH has: established and updated health-based criteria for four PFAS; developed analytical methods for environmental media, blood serum, and garden produce; conducted many community engagement activities; completed investigations at some fire training areas and chrome-plating facilities; and completed fish monitoring of 93 lakes and rivers. As the MDH and the MPCA moves forward in evaluating PFAS, they are taking a programmatic approach evaluating potential sources and managing and mitigating impacts to human health and the environment, where appropriate and necessary. The objective of this presentation is to outline the approach taken for that evaluation, share the results and lessons learned from the process, discuss the next steps in the program, and how the approach has applicability across sectors. This programmatic approach is not only invaluable for a State to determine potential sources of PFAS and efficiently manage and mitigate impacts, but it also can be modified and applied to an industrial portfolio to identify/mitigate unacceptable exposures and establish remediation reserves across a given set of assets.
The approach includes a multi-phased plan to identify and evaluate potential locations across the State that may have been contaminated with PFAS. The first phase, potential source locations and candidate evaluation, established a basic framework and protocol to identify and evaluate potential PFAS locations. A pilot test of four counties was initially conducted to develop and test the protocol prior to roll-out across the remaining 83 counties statewide. Businesses in each county were compared to North American Industry Classification System (NAICS) codes anticipated to be potential PFAS users, then addresses were geocoded using Geographical Information Systems (GIS), stored in a geodatabase and mapped. Potential pathway analysis and a receptor evaluation was performed to determine relevant sensitive sub-populations.
The second phase, location prioritization and selection, included a risk ranking evaluation of potential risk categories including sub-categories of sources, pathways, and receptors. Each risk category was given a risk score that was added together for each location yielding a final location risk rank. Locations were then prioritized and location profiles were developed for the top-ranked sites.
The last phase, absence/presence determination is planned and will include biased sampling and analysis at top-ranked sites to determine the absence or presence of PFAS at each location. Preliminary conceptual site models have been developed by location type and a risk communication plan has been drafted to support the roll-out of the program.
Several lessons have been learned through the protocol process. The pros and cons of the protocol process are discussed as well as potential applicability to other types of industries.
Learning Objectives:
1. Learn how to systematically evaluate sources
2. Understand how to evaluate receptors and pathways
3. Learn how to perform risk-ranking

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