
West Yost has been providing wastewater treatment and disposal system planning, regulatory compliance, and engineering design services for the City of Lodi’s White Slough Water Pollution Control Facility (WPCF) since the late 1990s. This project work started with a role in the development of a flexible Wastewater Master Plan to identify the improvements needed to address Lodi’s capacity and rehabilitation needs over a 25-year planning horizon. The Plan was completed in December 2000.
The Master Plan, followed by additional pilot studies, stakeholder negotiations, and regulatory coordination efforts provided by West Yost, guided Lodi through the completion of all the upgrades necessary for compliance. In 2005, Lodi constructed a cloth media tertiary filtration system and UV disinfection facilities. In 2009, Lodi constructed the facilities needed to expand the treatment capacity from 6.5 mgd to 8.5 mgd, while adding in the improvements needed to achieve reliable nitrification and denitrification.
In 2014 and onward, West Yost designed a new anaerobic digester, pumped-mixing system, flame arrester, heat exchanger, boiler, gas piping, and accessories as part of a project to increase the average flow capacity of the plant from 6.8 mgd to 8.5 mgd. Subsequently, plant staff discovered sludge in the attic space of two floating digester covers, and West Yost design replacement covers and the replacement of the gas-mixed systems with pump-mixed systems. In addition, West Yost designed a new digester gas/natural gas-fired boiler, heat exchanger and hot water piping loop, digester gas scrubbing and waste gas burner improvements, and new biosolids dewatering and storage facilities.
West Yost has also provided regulatory assistance services for Lodi over this entire period, including support with adoption of new NPDES Permits in 2007, 2015, and 2019.
Team Spotlight

Kathryn Gies, PE, ENV SP
Regulatory and Planning Practice Area Leader. Engineering Manager II

Kathryn Gies, PE, ENV SP
Regulatory and Planning Practice Area Leader. Engineering Manager II
“As a facilities planner, I help guide our clients through process of evaluating treatment alternatives and selecting the solutions that provide the most sustainable approach for their community. Helping communities select and implement effective solutions for achieving environmental protection and water reuse is so rewarding.
What I’m most proud of are the long term relationships I have with clients. I have been working with a large percentage of the clients that I work with today since I started at West Yost over 20 years ago. These long-term relationships not only make me feel like a valuable member of their team, but I also feel like a real member of their community.”

Charles Hardy, PE
Senior Engineer II

Charles Hardy, PE
Senior Engineer II
“I really like chemistry and studied chemical engineering as an undergraduate. I’m environmentally minded, and the combination of chemistry, environmental sustainability, and water really appealed to me. The rewarding work I do on the wastewater side helps agencies produce high-quality water that meets discharge permit limits and supports clean water for our communities and global health. In graduate school my friends who were in consulting encouraged me to enter this field.
I perform BioWIN process modeling and have been working on a multi-year analysis for Davis WWTP. It’s a newly upgraded treatment plant that had a lot of data gathered by us and the City. The project was collaborative with much interaction with City staff. I oversaw setting up the sampling plan, led our assistance with sampling, and have been more recently involved in a capacity analysis. The project has covered a lot of ground and has been personally rewarding. I look forward to the future phases of the capacity analysis.”

Bill Schilling, PE
Principal Engineer I

Bill Schilling, PE
Principal Engineer I
“The main thing that I enjoy about being part of West Yost is getting to develop innovative, yet practical solutions to real world problems that our very own communities are facing. It feels good to work with a team you really respect and have a good time with to help out others around you.
One of my most memorable experiences at West Yost has been working on the Dublin San Ramon District Primary Sedimentation Expansion and Improvements Project. The project involves design, construction, and startup of two new primary clarifiers and one new grit tank, and rehabilitation of several other existing process units. It is one of the first projects I got to see all the way through from preliminary design to construction and I am really proud to see it come to completion.”