CONFLUENCE ENGINEERING GROUP - Key Persons
Confluence is a dynamic company that provides professional engineering, field training, and water quality services to our clients in the drinking water industry. We are comprised of civil engineers, chemical engineers, licensed treatment and distribution operators, and field services professionals. We are located in the Pacific Northwest and work throughout North America.
Select a Team Member to read about our specific areas of expertise and contributions to the drinking water industry.
Before joining Confluence Engineering Group (Confluence), Al served as a project coordinator for MicroHAOPs, Inc., a University of Washington Department of Civil and Environmental Engineering technology start-up, tasked with the scale up and commercialization of a novel water treatment chemistry. Prior to this Al was the manager of HDR's Water Treatment Evaluation Laboratory in Redmond, WA. During these 9 years Al facilitated a wide variety of drinking water, industrial and wastewater laboratory-based and pilot scale field projects. Al has also been a sole proprietor of a custom field sampling equipment company and a commercial and a residential remodeling contractor. Since graduating with an MS in Zoology from the University of New Hampshire in 1990 Al has been supporting water related engineering projects providing pilot system construction and maintenance services along with laboratory and field-testing support.
Job Titles:
- Senior Project Manager at Confluence
Alex is a senior project manager at Confluence with over 25 years of experience evaluating and optimizing utility and building potable water treatment and reticulation systems, assessing effectiveness of drinking water disinfectants, developing water quality monitoring & improvement programs, developing design criteria for new applications of conventional & advanced treatment technologies, managing and training utility operations staff, and facilitating the evaluation and design of water quality and treatment solutions for clients across North America, Australia, New Zealand, and East Asia.
Prior to consulting, Alex completed 15-years with Metropolitan Water District of Southern California. He was appointed Metropolitan's Water Quality Purification Engineer, responsible for watershed, treatment, and distribution regulatory compliance for 2,000 MGD of treated water flow.
Andrew Hill is a Senior Project Manager at Confluence Engineering Group, LLC with over 20 years of professional engineering experience in planning, design, and research related to drinking water treatment and distribution system water quality. Andrew's areas of technical expertise include: behavior and treatment of inorganic contaminants; reaction chemistry; assessment and mitigation of legacy pipe deposits; disinfection byproduct (DBP) control; and corrosion control.
Andrew has published numerous industry guidance manuals and peer-reviewed articles related to asset and water quality management, distribution system best practices for water quality control, and mains cleaning. Andrew routinely conducts applied research studies, bench- and pilot-scale treatment tests, and distribution system pilot tests to evaluate treatment processes and source-to-tap mitigation strategies. Andrew has worked with utilities thoughout North America to plan and implement capital improvements for new, upgraded, and expanded treatment facilities, addressing the unique challenges, needs, and opportunities in each project.
Chris joined Confluence Engineering as a Senior Project Manager in 2020, following 17 years with Tacoma Water, where he served as Deputy Superintendent of Water, and Manager of the Water Quality and Supply Sections. He was responsible for planning and execution of large infrastructure, surface and groundwater treatment, watershed management, environmental stewardship programs, and drinking water regulatory compliance. Among his most recent responsibilities has been leading the development of regional resilience studies with the Water Supply Forum, an organization of several of the largest water utilities in Washington State.
Prior to his time with Tacoma, Chris worked 7 years for the Washington State Department of Health, where he led State-wide water treatment evaluations and technology approvals, and 5 years with a Seattle based consulting engineering firm. He holds Bachelor's and Master's Degrees in Civil Engineering, is a licensed professional engineer and a certified Level 4 Waterworks operator.
Melinda Friedman is founder and President of Confluence Engineering Group, LLC (Confluence) in Seattle, Washington. Prior to founding Confluence in 2008, she spent 18 years serving as Water Quality Program Lead and Project Principal at HDR Engineering, Inc., and at Economic and Engineering Services, Inc., in Bellevue, Washington.
Melinda has many years of experience providing services related to source water and distribution system water quality evaluation, regulatory compliance, comprehensive planning, and optimized treatment practices. As a recognized leader with respect to distribution system water quality, she has participated in numerous research efforts and has helped to prepare many prominent industry Guidance Manuals published by the American Water Works Association (AWWA) and the Water Research Foundation (WaterRF). Examples include:
Criteria for Optimized Distribution Systems (WaterRF, 2010)
Assessment of Inorganics Accumulation in Drinking Water Scales and Sediments (WaterRF, 2010)
Strategies for Managing and Responding to Total Coliform and E. coli in Distribution Systems (WaterRF, 2009)
Development of Distribution System Water Quality Optimization Plans (AwwaRF and AWWA, 2005)
Verification and Control of Pressure Transients and Intrusion in Distribution Systems (AwwaRF, 2004)
Establishing Site-Specific Flushing Velocities (AwwaRF, 2003)
Melinda is a Past Trustee of the Pacific Northwest Section (PNWS) AWWA, and Past Chair of the PNWS AWWA Water Quality Management Committee. She is an active member of National AWWA Distribution System Water Quality, Inorganic Contaminant, and Distribution System Research Committees. She was the 2017 recipient of the George Warren Fuller Award for Engineering Excellence. She is routinely called upon to present at national and international conferences and symposiums.
Job Titles:
- Chief Operating Officer and Field Scientist
Michael Hallett serves as Chief Operating Officer and Field Scientist for Confluence Engineering Group, LLC. In this capacity Michael manages the day-to-day business operations of the company, as well as acting as project scientist for all field related work. For the past 33 years Michael has worked in a wide variety of positions within the field of physical sciences, with experience in the collection and analysis of air, water, and soil samples.
Before co-founding Confluence in 2008 Mr. Hallett served as President of Three Rivers Contracting Services (TRCS), a small company providing field support in the physical sciences. TRCS was involved in the construct and operation of pilot water treatment studies for various municipalities in the Pacific Northwest and the US Environmental Protection Agency. Staff at TRCS also constructed and operated air quality monitoring pilot studies for the Hanford Nuclear Reservation and the California department of Evironmental Protection.
Before founding TRCS Michael was a member of a research team employed by the US Forest Service to assess firefighter exposure to the hazardous constituents of smoke at wildfires and prescribed burns. The core of this work involved the collection and analysis of gas and particulate phase pollutants in breathing zone samples from forest firefighters. In this position he conducted chemical and gravimetric analyses of samples using gas and liquid chromatographs, infrared spectrophotometers and high sensitivity balances, wrote standard operating procedures, and provided graphics and data management support to senior scientists. Michael contributed extensively to method development on the high-performance liquid chromatograph, while also developing several innovations to improve the efficiency and quality of data collection. Additionally, he supervised the organization and implimentation of long field seasons, including the preplanning necessary for extended field efforts in remote locations throughout the western states, while also managing the operations of a high efficiency organics lab.
Job Titles:
- Senior Project Manager With
Stephen Booth is a Senior Project Manager with Confluence Engineering Group, LLC (Confluence) in Seattle, Washington. Before joining Confluence, Stephen was a Research Engineer with Carollo Engineers and an Associate Scientist with Kennedy/Jenks Consultants. Stephen has 23 years of experience, specializing in drinking water quality and treatment. He has led applied research projects, water quality studies, and system and facilities plans for utilities across the western US.
Stephen brings to Confluence a variety of research and applied skills in drinking water treatment design, pilot plant design and operation, and water aesthetics. He has performed detailed treatment plant evaluations, assisted utilities is developing new source waters, led extensive pilot studies, and worked to help utilities develop and implement novel treatment options. Stephen is the author of numerous technical papers and has presented at various regional and national AWWA, IWA, and IOA conferences. In addition, Stephen has served as Chair of the AWWA Taste and Odor Committee and the PNWS AWWA Water Quality Committee, and is a current member of the PNWS AWWA Research Committee.
Prior to joining Confluence Engineering Group (Confluence) in November 2018, Virpi worked at the Washington State Department of Health (DOH) as a regional engineer for 11 years. Virpi administered the federal and Washington State specific drinking water regulations in assigned geographic areas that included inspecting public water systems, providing technical assistance to utilities and stakeholders (such as local health jurisdictions), reviewing and approving projects and water system plans for adequate capacity and regulatory compliance, assisting in public health emergencies, responding to public and customer inquiries. She has inspected approximately 150 water systems in western Washington. In addition to her role as a Regional Engineer at DOH, she was the Lead and Copper Rule (LCR) specialist while in the Southwest region, and regional lead for the Arsenic Treatment Optimization Program (ATOP) while in the Northwest region at DOH. She completed graduate school at the University of Washington in Seattle, and post-graduate school at Tampere University of Technology in Finland. She has worked as a research engineer and research assistant for a biomining research project and as an assistant in academic research projects related to screening and enriching microbes for medical purposes. She has years of laboratory experience ranging from every day testing at a wastewater treatment plant to applied molecular microbiology and clinical research.