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Naples staff to install backflow preventers on prioritized Moorings Bay outfalls, city engineer says
Summary
City staff told the Moorings Bay Citizens Advisory Committee that 10 primary outfalls (30 inches or greater) have been prioritized for backflow-preventer installation, with work expected this summer and fall pending tides and manufacturing timelines.
City engineers told the Moorings Bay Citizens Advisory Committee on April 21 that the city has identified a set of primary stormwater outfalls that will receive backflow preventers intended to reduce seawater intrusion into the storm system.
Dan Orenstein, the city engineer and stormwater manager, said a recent review found 15 primary outfalls and 34 secondary outfalls in the Moorings Bay watershed, and that staff is prioritizing 10 primary outfalls — those 30 inches in diameter or greater — for backflow-preventer installation. "Staff is working with suppliers to order and manufacture the required fittings," Orenstein said, and installations are anticipated this summer and fall depending on tides, manufacturing and procurement timelines.
Committee members pressed Orenstein for technical details. He described the devices as either inline check valves or wall-stop check valves and said they open and close with tide and flow pressure. Members raised maintenance concerns based on local experience with salt-water corrosion of springs and hinges. "They work great when they're first put in," one member said. Orenstein acknowledged the maintenance burden and said the city is coordinating follow-up cleaning and maintenance with contractors as part of operations work.
The engineer said the devices should reduce flooding and lessen infiltration of stormwater into sanitary systems during many events, but they cannot prevent flooding or sewage backflow during extreme surge conditions. "It will help, reduce flooding," Orenstein said, "but if there's a big enough storm ... it's just gonna get flooded in there." Committee members also asked whether Naples Bay is receiving similar treatment; Orenstein said the city is looking at outfalls citywide but is prioritizing this Moorings Bay area first.
Orenstein noted the stormwater division is also updating the 2018 stormwater master plan with consultant WSP, conducting citywide modeling for design storms and composing basin-by-basin maintenance and special-project plans for the capital improvement program (CIP).
The presentation and the Q&A are intended to inform upcoming maintenance scheduling and CIP funding decisions; no formal committee action was taken during this agenda item.
