A weekend sewer spill at Miami-Dade County’s Virginia Key treatment plant triggered another round of beach warnings.
Health officials advised swimmers to stear clear of water on beaches at Virginia Key, Key Biscayne and Fisher Island Sunday after about 35,000 gallons of treated sewage spilled from the plant into a lagoon that flows into coastal waters, said water and sewer department spokeswoman Jennifer Messemer-Skold.
The spill happened after a pump was disabled for about an hour, causing the treated sewage to back up into a holding pool for an offshore outfall pipe.
Messemer-Skold said plant officials initially reported a power outage. But a Florida Power & Light spokesman said Monday evening the utility traced the problem to equipment failing at the 1950s-era plant.
The sewage had already been treated and met safety limits for recreational waters, Messemer-Skold said.
“This was not sewage,” she said. “This was highly treated chlorinated water.”
Swim warnings were issued until tests can be completed to confirm water quality, she said.
In recent months, beaches have shut down repeatedly after routine water quality tests turned up high levels of fecal matter. Often those warnings coincide with high tides, when increased stormwater and run-off can wash pollution into coastal waters.
Over the weekend, unexpectedly high tides increased the volume of sewage flowing into the plant, Messemer-Skold said. But she said the increased volume did not exacerbate the spill.
“We had more volume coming in, but it wasn’t the cause at the back end,” she said. “One was unrelated to the other.”
Officials initially estimated the spill at about 100,000 gallons, but Messemer-Skold said based on flow levels and the time it took to reboot the pump the amount was revised to about 35,000.
In a report to state environmental regulators, sewer plant operators noted the spill was first spotted about 10:20 a.m. and stopped at 11:30 a.m. The treated sewage flowed into a nearby lagoon named Shrimp Lagoon where shrimper Jimbo Luznar sold bait for decades. The mouth of the lagoon faces Fisher Island.
Tests performed on water sampled Sunday and Monday should be completed by Tuesday afternoon. The warnings will remain in place at least until then.
