A rumbling engine, a cloud of white smoke and a patch of grass along East Third Street might not seem like the makings of an underground investigation.
But in Apopka on Wednesday, those unusual sights and sounds helped crews uncover a problem hidden beneath the surface — without digging up a single shovel of dirt.
The city is conducting smoke testing of its sanitary sewer system, using a specialized method to identify damaged pipes, leaking manholes and improper connections that allow rainwater and groundwater to enter a system designed to carry wastewater.
News 6 joined crews from contractor USSI as they worked in one of Apopka’s older sewer service areas, where smoke emerging from the ground revealed a potential opening in the underground system.
And that was just one of the locations crews identified.
An exclusive look at a digital inspection map shown to News 6 by a crew member revealed more than 40 green markers indicating locations workers said had been flagged for problems.
The exact number of unique defects requiring repairs has not yet been independently confirmed. The map documents suspected trouble spots within the area being inspected, not confirmed defects throughout the entire city.
SEE THE MAP: Where Apopka crews are conducting sewer smoke testing — official city map
The city’s map shows the Lift Station 17 service area and sewer infrastructure being assessed. It is separate from the crew’s digital map of flagged locations obtained by News 6.
How a little smoke can expose an underground problem
The testing process begins with a powerful blower that pushes specially manufactured, non-toxic smoke into sanitary sewer lines through access points in the system.
From there, crews follow where the smoke travels.
Some of what they see is expected. Smoke rising from plumbing vents on rooftops, for example, is generally a sign that those vents are connected and functioning as intended.
“When you see smoke emitting from the roofs, that’s healthy. That’s a normal plumb vent,” said Tim McRoberts, a senior project manager working on the operation.
But smoke emerging from somewhere else can tell a different story.
McRoberts explained that when smoke escapes through the ground, a street or a damaged pipe opening, it may reveal a place where rainwater can enter the sanitary sewer system.
“Our job is to find those defects,” McRoberts said.
During Wednesday’s testing, News 6 watched crews investigate smoke escaping from a grassy area near East Third Street. Workers examined the location and marked the ground to help document what they discovered.
McRoberts said the process can identify several different types of problems, including broken sewer cleanouts, leaking manholes, improper connections from residential gutters and stormwater pipes connected directly to sanitary sewer lines.
A sewer cleanout is an access point that allows workers or plumbers to inspect and maintain a pipe. If the opening is damaged or improperly sealed, unwanted water can enter.
The same can happen when a manhole leaks or when a home’s drainage system sends roof runoff into a sewer line instead of an appropriate stormwater drainage system.
McRoberts said crews sometimes find what he described as stormwater crossovers, where storm drainage was connected directly to the wastewater system by a previous contractor.
Although the problems can be difficult to spot from above ground, the escaping smoke helps crews narrow down where to investigate.
And unlike other inspection methods that may require additional equipment, extensive camera work or excavation, smoke testing can identify many possible openings relatively quickly.
“Number one is cost,” McRoberts said when asked why the city uses the method.
He described smoke testing as one of the most affordable ways to assess the condition of a wastewater collection system.
Why rainwater getting into sewer pipes is a serious concern
The purpose of the testing goes well beyond identifying a leaking pipe.
Sanitary sewer systems are designed to transport wastewater from homes and businesses to treatment facilities. They are not intended to collect large quantities of rainwater.
When stormwater or groundwater enters through damaged pipes, manholes or improper connections, it increases the amount of water that must move through the system.
That problem is commonly called inflow and infiltration, or I&I.
Inflow generally refers to water entering directly through openings or connections, such as gutters or damaged manhole covers. Infiltration typically involves groundwater seeping through cracks, joints or other defects in underground pipes.
Both can place additional pressure on wastewater infrastructure.
The consequences can include higher pumping and treatment demands, increased operating expenses and reduced available capacity during heavy rainfall.
In more serious circumstances, excessive flows can contribute to sewage backups or sanitary sewer overflows, potentially creating public health and environmental concerns.
During Wednesday’s field visit, crew members told News 6 that approximately 800,000 gallons of unwanted water per day can enter the wastewater system during rainy conditions.
That figure is an estimate provided by the crew. News 6 has not independently verified the calculation or established whether it applies specifically to the Lift Station 17 service area or a larger portion of Apopka’s wastewater network.
The concern is not that the testing smoke itself is harming the environment. Rather, the smoke helps reveal openings that may be allowing water to enter a system already responsible for transporting and treating the city’s wastewater.
Apopka Utility Program Supervisor Gabby Lederer said preventing that unnecessary flow is central to the city’s efforts.
“We really want to try to prevent any type of storm water going into our system, which increases the flow that goes to our wastewater, um, plant itself,” Lederer said.
In practical terms, the less unwanted water entering the sewer system, the more capacity remains available for the wastewater it was designed to handle.
The testing involves wastewater collection infrastructure, not Apopka’s drinking-water distribution pipes.
Why crews are starting in this part of Apopka
Wednesday’s testing focused on the service area associated with Lift Station 17.
A lift station helps move wastewater through the collection network, particularly in locations where gravity alone cannot carry it to the next destination.
Lederer said the city intentionally began its work in one of its older sewer basins.
“Right now we’re starting with one of the oldest basins, because there really hasn’t been too much preventative work here,” she said.
The age of the infrastructure is important because sewer pipes and their connections can deteriorate over time. Older systems may reveal problems that have developed over many years.
Lederer said understanding those weaknesses could also help Apopka anticipate future maintenance needs in newer developments.
The city plans to continue assessing its wastewater infrastructure one lift-station basin at a time, rather than treating Wednesday’s inspection as a one-time project.
“We will do it citywide,” Lederer said, explaining that the city intends to proceed basin by basin.
The longer-term objective is to identify weaknesses before they develop into more expensive or disruptive problems.
Lederer described the effort as part of building an infrastructure maintenance strategy spanning the next five to 10 years.
What happens to the problems crews are finding?
Identifying a defect is only the first step.
McRoberts said his team is focused on locating problems throughout the assigned service area and determining whether the contractor can address any of them.
“Number one, we’re trying to locate all the defects within a certain basin. And then if we can fix it, we will,” he said.
For issues that cannot be corrected by the testing crews, additional work may be required from city personnel, plumbers or other contractors.
Lederer said the city will use the contractor’s inspection findings to create a more detailed picture of the system’s condition.
That information could guide repairs to individual manholes, the rehabilitation of sewer laterals that connect properties to larger pipes, or improvements to sewer mains themselves.
“I really just wanna know what the problems are,” Lederer said. “But really, I just wanna know what’s out there and then move forward to fix it.”
She explained that the city will prioritize its response based on the severity of the identified issues.
“We’re going to strategically plan it based off of worst case scenario,” Lederer said.
Some issues may be addressed relatively quickly, while larger repairs could require engineering work, additional funding or separate construction projects.
Lederer said she expects the city to receive substantial inspection data from USSI within approximately one to two weeks.
Her goal is to address at least some of the manhole rehabilitation needs before the end of the year.
The cost of repairs and the total number of confirmed defects have not yet been established in the information provided to News 6.
Part of a broader effort to prevent sewer overflows
Apopka’s work also comes as Florida requires wastewater utilities to take a more systematic approach to evaluating aging infrastructure.
Under a regulation that took effect in June 2023, the Florida Department of Environmental Protection requires domestic wastewater facility permittees to develop collection-system action plans addressing pipe assessments, repairs and replacements.
The plans generally must establish a goal of evaluating at least 25% of a utility’s sewer collection system over a five-year planning period, subject to exceptions allowed by the rule.
Smoke testing is one of several methods utilities may use, alongside camera inspections, flow monitoring and other assessment techniques.
The state’s objective is to encourage utilities to identify leaks and infrastructure weaknesses before they contribute to sanitary sewer overflows or other failures.
For Apopka, that means the information collected during Wednesday’s work could help inform future maintenance priorities well beyond the neighborhood where the smoke was visible.
Residents can learn more about those statewide requirements through the Florida Department of Environmental Protection’s collection-system action plan information.
What Apopka homeowners should know about the testing
While smoke emerging from unexpected locations may look alarming, the City of Apopka and USSI say the testing smoke is specially manufactured for the process and is non-toxic.
Residents may notice smoke rising from manholes, yards, cleanouts or rooftop plumbing vents while crews work nearby.
The city says smoke emerging from rooftop plumbing vents is normal during testing.
However, if smoke enters a home or business, it may indicate a dry plumbing trap, an improperly connected fixture or another opening between the building and the sewer system.
Residents can reduce the likelihood of smoke entering through unused drains by making sure plumbing traps contain water.
That includes seldom-used sinks, showers, bathtubs and floor drains.
USSI advises anyone who notices smoke entering a building to open doors or windows to ventilate the space and notify a uniformed testing crew member. The company can help identify where the smoke may be entering, although its public guidance says crews do not perform repairs to private plumbing.
According to the city, homeowners do not need to be present during testing, which typically takes approximately 15 minutes in a given area.
Residents in scheduled testing areas should receive a door hanger notifying them that crews will be working nearby.
Testing is scheduled on weekdays from 8 a.m. to 5 p.m., weather permitting, through Friday, October 30, 2026.
Residents with heart or respiratory conditions who would like advance notice of testing near their homes can contact USSI at 1-888-645-9570 or 941-926-2646, between 9 a.m. and 4 p.m., to inquire about scheduling and request a call ahead when needed.
The contractor also says its testing smoke is designed not to harm pets or leave stains and residue.
For homeowners who want a more detailed explanation, USSI provides an online guide covering smoke testing, pets, plumbing concerns and what to do if smoke enters a building.
HOMEOWNER GUIDE: What to expect during sewer smoke testing, according to USSI
Where residents can find additional information
The City of Apopka has published a public notice containing its official testing-area map, schedule, door-hanger information and instructions for residents.
SEE THE MAP: Apopka’s official Lift Station 17 smoke-testing area
CITY INFORMATION: Official Apopka sewer smoke-testing notice and homeowner instructions
WATCH AND LEARN: USSI videos showing how smoke testing works
HOMEOWNER FAQ: Answers about smoke entering homes, health concerns and pets
The company’s official website also provides additional details about the inspection process and resources for property owners.
For residents, the important thing to understand is that the smoke itself is not the underground problem. It is the tool being used to find one.
And as crews move from one Apopka neighborhood to another, the information they collect may help determine where the city needs to make repairs before hidden weaknesses become much larger problems.