PFAS include thousands of manufactured fluorinated chemicals that have been widely used since the 1940s in common, everyday products from food packaging, to personal care products, to water-resistant clothing, to firefighting foam. Due to the widespread use of PFAS over the last 80 years, and their resistance to biodegradation, trace amounts of many PFAS chemicals are commonly found in the air, soil, and blood of animals and humans. One prevalent PFAS compound suspected of posing a risk to human health is PFHxS.
In October 2022, the State Water Resources Control Board’s Division of Drinking Water issued a statewide order establishing a notification level (NL) and response level (RL) for PFHxS at 3 parts per trillion (ppt) and 20 ppt, respectively. Drinking water sources that exceed the established NL are required to provide notification to their governing body. Sources that exceed an established RL are required to be treated to remove the contaminant or be removed from service.
The overall goal of the Project is to support the construction and implementation of the PFAS Treatment Facility for compliance with the recently established NL and response level RL for PFHxS, enabling Zone 7 to continue the use of the Stoneridge groundwater well as part of the overall water supply program for the service area.
The treatment process to be employed at the PFAS Treatment Facility include media pressure vessels for ion exchange (IX) adsorption of PFAS and would consist of several key components:
• Booster pump.
• Cartridge filters.
• Media pressure vessels.
• Concrete pad foundations for vessels and booster pump.
• Small electrical building.
The facility includes construction of conveyance pipelines. New piping and valves would be provided to divert raw water from the production well to the treatment system. Treated water from the pressure vessels would be sent to the distribution system. These pipelines would connect to the existing conveyance system and would be within existing property lines and easements. Additional permanent easements for the pipelines are not anticipated.
The steel media pressure vessels would remove contaminants utilizing IX treatment technologies. These steel vessels would be anchored to concrete mat foundation slabs and would be approximately 15 feet tall. The treatment system at the Stoneridge well facility would consist of three parallel trains of two pressure vessels per train arranged in series, trains of the system would be arranged in parallel. In addition to these steel vessels, there would be a booster pump, cartridge filters and a small electrical building, approximately 15 feet by 25 feet, to house the new electrical panels for the facility. Work will be contained within the existing footprint of the well facility.
Project construction is anticipated to begin in late January to early February 2023, and be functionally completed by about July, 2023, with full completion of the project anticipated in January 2024 – an additional period of six months. The majority of Project construction would occur during the February through July 2023 period, with the exception of inclement weather conditions, with only minor addition construction and equipment installation during the July 2023 through January 2024 period.