Another 11.483 gallons of partially treated sewage ends up in bay, as well
Because of the rainfall that Tropical Storm Debby produced, the City of Sarasota ended up discharging about 6.243 million gallons of raw sewage into Sarasota Bay and another 11.483 million gallons of partially treated effluent, city staff informed the Florida Department of Environmental Protection (FDEP) on Aug. 10.
That report covered the period from 4 a.m. on Aug. 5 through 11:55 p.m. on Thursday, Aug. 8, it noted.
The city’s advanced wastewater treatment plant, which stands at 1750 12th St., suffered severe effects, the report said. Operations staff members “did everything in their power to control the flow coming into the facility,” the report pointed out. “The collection system had all lift stations at high well status and all pumps running to push the flow to the plant to avoid numerous catastrophic spills in the field,” the report explained.
As High Tide Technologies explains, a wet well is “a holding cell that empties out once it reaches a predetermined level.”
Staff was dealing with up to 44.29 million gallons of wastewater coming into the plant in a single day, the report added.
“Staff made every effort to contain and control the spill, but the volume was too significant to avoid the mixture of rainwater and untreated sewage entering the [stormwater] collection system,” the report continued. “Staff operated the collection system and treatment plant processes” and were able to stop the overflow at approximately 6 p.m. on Tuesday, Aug. 6, the report said.
Workers “continued to manage the plant and collection system throughout [that] night,” the report noted, “and everything seemed to be operating normally albeit at considerably higher than normal flow levels.”
However, the report continued, at approximately 9 a.m. on Wednesday, Aug. 7, “the number 3 and 4 clarifiers began to overflow.”
Ecologix Environmental Systems explains, “Clarifiers are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening. Concentrated impurities, discharged from the bottom of the tank, are known as sludge, while the particles that float to the surface of the liquid are called scum.”
The city report then explained, “Flow in the collection system and the treatment plant were still at extreme levels,” but were anticipated to be manageable.
“Operations staff used every possible option to divert flow, clear pipelines between tanks and adjust tank levels within the minimal margins available to them,” the report pointed out. “Despite all their efforts the clarifier levels did not change. Further investigation revealed an obstruction in the discharge line from the clarifiers was preventing the proper volume of flow [from exiting] the clarifiers. Staff made the decision to contact a pump vendor and bring large pumps to the treatment plant site to bypass the clogged clarifier discharge lines and pump the flow from the clarifiers directly to the flash floc.”
In a July 2019 article posted on the CleanaWater website, Mark Maggiore explains, “Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water.”
Altogether, 10 pumps were delivered to the city site between the evening of Wednesday, Aug. 7, and early Thursday morning, Aug. 8, the city report added.
City-owned pumping equipment “was set up in the clarifiers to attempt to control the overflow” while staff awaited the arrival of the vendor-owned pumps, the report said. City staff also erected berms at the site in an effort to control the flow of the effluent onto the ground, the report pointed out.
After the vendor pumps were set up in the clarifiers, the report said, the overflows stopped at 11:55 p.m. on Thursday, Aug. 8. “Staff remained on site to monitor the situation and adjust the flow rates based on incoming flows and clarifier levels,” the report noted.
On Friday morning, Aug. 9, “staff began attempting to clear the blockage in the clarifier discharge lines,” the report continued. “It appears the incoming flow was so significant that the discharge pipe grating in clarifier 3 was dislodged and foreign material entered the pipe and became lodged at a [T juncture]. Staff spent the entire day trying to clear the blockage but were unsuccessful,” the report explained.
“The bypass pumps remain in place while staff gather resources to continue the line clearing process,” the report added. “The treatment facility is operating properly despite the bypass pump situation. Staff continue to deal with excessive flow levels but are working to restore the plant to normal operations,” the report noted.
[I don’t understand] how it is possible for so much storm water to enter the sewage treatment facility. The storm water drainage system presumably is a completely different set of pipes and drains from that of the sewage system. Storm water pipes empty into the bay – they should not be running through a sewage treatment facility. At least not in any modern system.
Week after week I read of sewage spills in Sarasota. While spills may be understandable with unique events like Debby I am unable to understand why city and county leaders would not act to prevent the repeated spills. I live in a large metropolitan area of Minnesota and I have never heard of a sewage spill here in the city. I own property in Sarasota and I am curious about these repeated spills. What am I missing?