Youn Sim, Ph.D., P.E., ENV SP // Chief, Strategic Planning & Sustainability Office, LA County Public Works

As a 21-year public servant at Los Angeles County Public Works, the largest public works agency in the US, Dr. Youn Sim is currently serving as the Public Works Sustainability and Innovation Officer.  For the past years, he has played a leadership role in sustainability initiatives in a variety of infrastructure sectors including water, transportation, solid waste, land development, green buildings, climate resilience, and most recently, renewable energy.  In 2012, he created the Public Works Sustainability Council and has been leading it since then. He later played a leadership role in establishing the Los Angeles County Sustainability Council.  From 2014 to 2016, he led a think tank group, Innovation Laboratory. In 2016, he was appointed to lead Public Works Strategic Planning & Sustainability Office and has been managing the Office since then.

He is the former chair of the Sustainability Committee of American Society of Civil Engineers (ASCE) Environmental and Water Resources Institute. He is a member of ASCE Committee on Sustainability and a member at ISI Envision Review Board. He received a Ph.D. from the University of California at Irvine in Civil and Environmental Engineering. 

Rebekah Oulton, Ph.D., P.E., LEED AP, ENV SP // Associate Professor, Cal Poly, San Luis Obispo. 

Ms. Oulton’s technical research addresses advanced treatment methods to target emerging contaminants during water and wastewater treatment, and optimization of green infrastructure for stormwater management and pollutant control. She teaches water resources engineering, water treatment and reuse, and sustainable practices in civil and environmental design. Prior to Cal Poly, Rebekah worked as a professional engineer and project manager for a civil engineering consulting firm.

Jennifer J. Walker PE, DWRE, ENV SP, CFM, QSD // Principal-In-Charge - Watearth, Inc.

Jennifer Walker brings nearly 30 years of experience in low impact development, green infrastructure, sustainability and resiliency, water quality, flood control, hydrology/hydraulics, stormwater, water resources, and complex projects with multiple stakeholders. She excels at solving water resources challenges at a regional level. Walker was one of the first engineers to receive the Diplomate, Water Resources Engineer certification. Walker has a Masters in Civil Engineering, is a Certified Floodplain Manager, and is a licensed Professional Engineer in multiple states. Walker’s experience includes developing a California statewide Low Impact Development (LID) modeling tool for Phase II communities in collaboration with California State Sacramento’s Office of Water Programs. Walker serves as LID technical expert on the San Francisco Bay Area Regional Green Infrastructure Tool and the San Francisco Bay Area Green Plan-It Master Plan in collaboration with the San Francisco Estuary Institute.

Aaron Yonker, PE | Senior Project Engineer - Tetra Tech

Mr. Yonker’s civil engineering experience includes work within stormwater, water and wastewater system analysis and design, technical specification and bid packet development, hydrology and hydraulic analysis modeling and design, drainage analysis modeling and design, plan-check services, and municipal stormwater and wastewater regulatory compliance support. Mr. Yonker has been providing local professional engineering support services within San Luis Obispo County for the past 10 of his 15-year professional career. His experience extends equally to the private sector where he has provided drainage, hydrology, and hydraulic support design services to clients in the Land Development, Agriculture, and Renewable Power Industries. As DOT Resident Engineer for the Massachusetts Department of Transportation during the early part of his career, Mr. Yonker gained extensive construction inspection, administration, and management experience on large-scale civil transportation and development projects, and has continued to provide these services to numerous municipalities throughout San Luis Obispo and Santa Barbara County.

Hernan Cortez, PE // Water Resources Project Manager - Rick Engineering

Hernan holds a Master’s degree in Civil and Environmental Engineering with an emphasis in water resources from Cal Poly San Luis Obispo. He is well-versed in the Central Coast Post-Construction and drainage requirements, having worked with the Central Coast Low Impact Development Initiative (LIDI). He has experience in a variety of water resources projects including hydrologic and hydraulic analyses, erosion and sediment control, FEMA floodplain studies and mapping, bridge hydraulics, hydromodification management, low impact development, watershed planning, and multi-purpose stormwater facilities.

Andrew Thies, CFM // Water Resources Project Manager - Rick Engineering

Andrew Thies is a Water Resources Project Manager at Rick Engineering Company where he specializes in GIS watershed master plans and the development of GIS based tools to aid in asset management and stormwater projects. He has successfully completed numerous stormwater master plans with experience across a wide range of water resources projects including hydrologic and hydraulic analysis, drainage and water quality design, FEMA map revisions, California State Trash Amendment implementation planning and watershed master planning. He has extensive experience in using a combination of GIS and PCSWMM to develop drainage and water quality master plan models of varying resolution and type.

Joseph L. Ririe, PE // Senior Principal Engineer - Pavement Engineering Incorporated

Joe is the president of PEI and has 27+ years of wide-ranging experience in engineering and project management and in developing practical, cost-effective and quality pavement solutions for clients throughout California, including 21 specifically focused on pavement design. Joe has worked on pavement projects for dozens of public agencies throughout California and specializes in pavement rehabilitation design and construction administration.

Mimi Le // Construction and Materials Engineer/Manager - Pavement Engineering Incorporated

Mimi is PEI’s Concord Office Branch Manager and specializes in recycling technologies, including full-depth reclamation (FDR) and cold in-place recycling (CIR). She supervises the mix design process and laboratory testing for cement and foamed asphalt recycling projects and oversees the Quality Control/Quality Assurance portions of these projects.  She also assists with and advises on the design process for PEI recycling and other paving projects in the Bay Area. In addition, estimates construction quantities and develops plans and specifications for client rehabilitation and new construction projects.

Peter Engel // Director of Programs - Contra Costa Transportation Authority

Peter Engel has worked in public transit and transportation demand management for over 25 years. As Director of Programs for the Contra Costa Transportation Authority, Peter is responsible for the programming and allocation of Measure J sales tax revenues to the county’s five public transportation operations, helping to ensure that the transit operators can effectively meet the need of the residents of Contra Costa County. Recent focus has been on new technologies, clean vehicles and infrastructure, and innovative approaches to service delivery in the transit industry, job access, first/last mile solutions, shared mobility hubs, and shared mobility options all with a focus on disadvantaged communities.