City to propose testable backflow assembly after sanitary-survey finding on raw-water line
Summary
Public works staff said they will seek council approval to install a testable reduced-pressure (RP) backflow assembly on the raw waterline to protect wells and groundwater from potassium permanganate exposure after a Department of Health sanitary-survey finding.
Ocean Shores public works staff told council they will ask to install a testable, high-protection backflow assembly on the city’s raw-water line after a Department of Health sanitary survey identified a vacuum at a raw-water sample point.
Ricardo Victoriano, the city’s new public works director, explained that the proposed reduced-pressure (RP) backflow assembly provides the highest protection short of an air gap and is testable so staff can confirm it is operating properly. He said installing one assembly “right before our chemical injection” will protect current and future wells rather than replacing check valves at each well, which are not testable and could be expensive to replace individually.
Victoriano said staff first noticed the issue during a sanitary-survey walk-through with the Department of Health in July. The alternative — replacing individual check valves on every well — would include wells not in service and would likely cost more than the proposed single assembly, he said. He described the RP assembly as “the highest degree of protection besides an air gap.”
Councilmembers asked about the chemicals involved; Victoriano said potassium permanganate is the only chemical in the city’s process that could plausibly reach groundwater. He explained potassium permanganate “oxidizes the water” and is used to reduce manganese and iron and to address an “egg” smell in raw water. Staff said groundwater is monitored monthly (including for E. coli) and that they have not observed evidence of harm from the issue.
Victoriano summarized procurement and timing questions: bids for the installation were reported to be close together (examples given as about $39,000–$43,000), and the city may need to take its treatment plant offline for about 24 hours to obtain post-construction bacterial samples. He said staff would select a construction window with lower demand — noting Labor Day weekend as a candidate — and that installation timing will depend on the awarded contractor’s schedule.
Council directions: staff will put the RP backflow assembly installation on the council agenda for approval, include cost estimates and construction timing, and coordinate sampling plans required after taking the plant offline.
No formal council vote was recorded in the transcript.
