Public engineering firm profile
Confluence Engineering Group, LLC
Seattle, WA
Ready to Address Your Water Quality Needs
- Services
- 7
- Offices
- 1
- Leaders
- 9
- Founded
- 2008
Overview
Confluence Engineering Group, LLC is a drinking water quality engineering firm headquartered in Seattle, Washington, providing specialized engineering, planning, and applied research services throughout North America. Founded in 2008 by Melinda Friedman and Michael Hallett, Confluence works with utilities, municipalities, school districts, regulatory agencies, water districts, research organizations, and building owners on the management, operations, maintenance, and regulation of drinking water distribution systems. Its team includes civil engineers, chemical engineers, environmental health scientists, licensed treatment and distribution operators, and field services professionals.
- Founded
- 2008
Services
Corrosion Control and Metals Release
Confluence addresses corrosion and metals release across a wide range of projects, from prevention and mitigation of discolored water events to process selection for optimal corrosion control under the US EPA Lead and Copper Rule. Desktop modeling and field protocols are developed to evaluate risks associated with new water-supply introduction, supply blending, changes in treatment practices, and shifts in secondary disinfectant residuals. Microbial, chemical, and physical factors are considered when diagnosing water quality issues and selecting corrosion control parameters.
Optimization and Main Cleaning
Confluence develops and implements engineered main cleaning programs for drinking water distribution systems. Work combines desktop modeling, field protocols, pilot studies, bench-scale studies, and monitoring plan implementation, addressing sediment accumulation, legacy pipe deposits, supply integration, and distribution system water quality control. Programs are delivered alongside utility operations crews, with field training support included.
Filtration and Treatment Studies
Confluence conducts bench-scale and pilot-scale filtration and treatment studies to support process evaluation and selection for drinking water systems. Studies encompass water quality data analysis, applied research, and field investigations, providing utilities with research-backed guidance for treatment improvement and optimization.
Industry Guidance
Confluence staff author and contribute to industry guidance documents and peer-reviewed research for the drinking water sector. Published work covers corrosion control, distribution system best practices, water quality asset management, and Legionella risk management, supporting regulatory development and utility practice across North America.
Building Water Quality Management
Confluence works with building owners on water quality management for building plumbing systems, with a focus on identifying and controlling Legionella and other waterborne risks. Services span risk assessment, water management plan development, and implementation support. Alex Mofidi leads the practice and has contributed to the development of current industry guidance on Legionella management best practices.
PFAS Monitoring and Assessment
Confluence provides PFAS monitoring and assessment services to drinking water utilities, covering monitoring program design, water sampling, data interpretation, and evaluation of regulatory compliance options. Chris McMeen, who brings 30 years of leadership in water utility management across private and public organizations, leads the program.
Industries
Firm type
Credentials and affiliations
Leadership
Melinda Friedman
President
P.E.
Melinda Friedman co-founded Confluence Engineering Group and has been working to solve complex water quality problems for 30+ years. She helped prepare many prominent industry guidance manuals and research papers. She is the 2017 recipient of the AWWA George Warren Fuller Award for engineering leadership and the 2022 recipient of the A.P. Black Research Award.
Michael Hallett
Chief Operating Officer and Lead Field Scientist
Michael Hallett co-founded Confluence with Melinda Friedman in 2008. He specializes in development and implementation of main cleaning programs, pilot studies, bench-scale studies, and implementation of monitoring plans, working closely with utility crews and providing field training.
Andrew Hill
Senior Project Manager
P.E.
Andrew Hill has 22 years of expertise in process engineering, reaction chemistry, supply integration, and mitigation of legacy pipe deposits. He leads the Main Cleaning Optimization program and has published numerous reports and peer-reviewed manuscripts on water quality, asset management, distribution system best practices, and distribution main cleaning.
Chris McMeen
Senior Project Manager
P.E.
Chris McMeen spent 30 years serving as a leader in both private and public organizations, including as Deputy Superintendent at Tacoma Water. He manages projects of all sizes, works across utility management to find solutions to water quality challenges, and leads the PFAS monitoring and assessment program.
Alex Mofidi
Senior Project Manager
P.E.
Alex Mofidi has 34 years of experience in water planning and process engineering for treatment and distribution system improvement projects. He has had a prominent role in many corrosion control studies, leads the Legionella risk assessment program, and has helped develop the most recent industry guidance for Legionella management best practices.
Virpi Salo-Zieman
Senior Project Engineer
P.E.
Virpi Salo-Zieman serves on regulatory assessments, corrosion control, supply integration, and distribution system water quality projects. Prior to joining Confluence, she worked at the Washington State Department of Health as a regional engineer for 11 years and was the Lead and Copper Rule specialist.
Yarrow Polacek
Project Engineer
Ph.D.
Yarrow Polacek has expertise in water treatment, data analysis, and applied research, conducting bench-scale and pilot-scale testing activities, water quality data analysis, and field investigations.
Al Vetrovs
Field Services
Al Vetrovs has 30 years of experience supporting municipal drinking water engineering projects with pilot system logistics, construction, innovation, and maintenance services, along with laboratory and field-testing expertise. He oversees manufacturing of pilot and bench-scale equipment and supports all aspects of field implementation and research.
Grace Crowe
Project Engineer
E.I.T.
Grace Crowe has hands-on experience in design, project management, and research and development, conducting field assessments, bench-scale and pilot-scale testing, and water quality data analysis and modeling.
Offices
Headquarters
HeadquartersSeattle, WA