Sewer overflows: Deluge of issues facing counties
The old saying about foul matter flowing downhill – in this case actual sewage – takes on literal and figurative meanings in metro Detroit, where billions of gallons of stormwater and sewage flow each year from the northwest suburbs to the southeast communities that border Lake St. Clair and the Detroit River.
"It follows the natural topography of the land and flows in that direction," said Gary Nigro, chief engineer for the Oakland County Water Resources Commissioner (OCWRC). "It's not personal."
And so it flows – the water, the waste and the storm runoff, all of it down the drain where it leads to a combined sewer system that serves much of Birmingham, Bloomfield Hills, Bloomfield Township and 11 other communities in southeast Oakland County.
During dry weather, the sewage from the combined system is pumped to the Detroit Wastewater Treatment Plant, where 85 to 90 percent of its contaminants are removed before it is released into the mouth of the Rouge River and into the Detroit River, near Zug Island. But when stormwater floods the system, the sewage is diverted to one of four retention treatment basins (RTB) in Oakland County, where it is held, screened, settled, skimmed and disinfected until the system can take it or it is released to nearby surface water – either the Rouge River or Red Run Drain (which is a tributary of the Clinton River).
The releases, or overflows, are referred to as combined sewer overflows (CSO), and have been a point of contention for officials in Macomb County. The problem, they have said for years, is that partially treated sewage entering the Clinton River empties into Lake St. Clair and leads to poor water quality, high E. coli levels and dozens of beach closures. Yet, Oakland County water resources officials and representatives from the Michigan Department of Environmental Quality (DEQ) say large CSO releases meet state and federal water quality standards, nor can all E. Coli be traced back to human sources, let alone CSO releases from Oakland County.
From January 1 to April 18, 2018, a total of 95.4 million gallons of partially treated sewage were released into the Rouge River from retention treatment basins in Birmingham and Beverly Hills. More than another billion gallons of water were released from retention basins in Macomb County, the majority of which included wastewater discharged from the George W. Kuhn treatment basin, which collects sewage from 14 communities upstream of the Red Run Drain, including Birmingham, Bloomfield Hills, Bloomfield Township, Berkley, Clawson, Ferndale, Hazel Park, Huntington Woods, Madison Heights, Oak Park, Pleasant Ridge, Royal Oak, Royal Oak Township, Southfield, Troy and Beverly Hills.
Large amounts of snowmelt and rain led to several overflows in 2018, which have already outpaced 2017, when Oakland County RTBs released 35.4 million gallons of partially treated sewage, and the Kuhn drain and others in Macomb County released 1.2 billion gallons. Still, those releases are relatively minor compared to the more than 2.4 billion gallons released in August of 2014 when stormwater flooded much of metro Detroit.
But, more recently, Macomb County officials have become increasingly vocal about the wastewater that has been dumped on them for years.
In October of 2017, a few hundred Macomb County residents gathered in Harrison Township at MacRay Harbor, located near the mouth of the Clinton River where it empties into Lake St. Clair. Among the speakers were state Representative Peter Lucido (R-Shelby Township), who questioned DEQ officials about water quality in the lake, and whether water flowing from Oakland County is to blame for problems in the lake.
Nutrient pollution, such as nitrogen and phosphorus, is one of the country's most widespread, costly and challenging environmental problems. Excess nutrients support the growth of algae and aquatic plants, which provide food for aquatic habitat, but can lead to health and environmental issues. Algae may harm water quality, food resources, habitats and decrease dissolved oxygen. It can also lead to fish kills and produce toxins and bacteria that make people sick if they come into contact with it. A main source of those nutrients is stormwater.
Attending as a listener, Nigro said DEQ officials confirmed that Oakland County's system was meeting current water quality standards and were ready to present that information but were stopped before they had a chance.
"Until recently, it hasn't been that easy to test where E. coli is coming from," Nigro said. However, he said advances in testing now reveal whether tested E. coli stems from human or other animals. Such advances, he said, lead to more beach closings and awareness of pollution.
"It's not that we are necessarily polluting more – it's that we know what it is now," he said. "The pollution has been going on for decades, but now we are aware of it. We are very conscious about it."
Officials, like Macomb County Public Works Commissioner Candice Miller, are pushing for the state to implement more stringent water quality standards to force Oakland County and others in the Great Lakes Basin to do more to control overflows.
Miller, who failed to return calls to Downtown newsmagazine, has said that E. coli from sewage isn't the only thing heightening E. coli levels in the lake. E. coli traced to geese and other wildlife that share the water are part of the problem. In fact, DEQ officials are reluctant to name any one source of water quality issues. Still, Lucido and others continue to point to Oakland County's combined sewer systems as the problem.
Unlike combined sewer systems, separate sanitary sewers are designed to carry only sanitary sewage to a wastewater treatment plant. Combined sewer systems are generally older sewer systems designed to send both sewage and stormwater to a treatment plant. Because combined systems may receive massive amounts of water from storm events or snow melt, they are designed with overflow points in the system and/or at the treatment plant.
Michigan started its CSO control program in 1988, and in 1994 the federal government developed a nationwide policy. The policy suggested states use an enforceable permit program called the National Pollution Discharge Elimination System to require CSO communities to implement interim measures, or minimum controls, and then develop long-term control plans. As an alternative to separating combined systems, some communities, including several in Oakland County, opted to build retention treatment basins, which are designed to capture the combined sewage and rainwater that would otherwise flow to surface waters untreated. The basins hold the combined sewage long enough to provide treatment and disinfection before the combined sewage is discharged.
In Oakland County, the Water Resources Commissioner (WRC) operates four such retention basins. In each case, water is treated, at least partially, before being released to a wastewater treatment facility. Each of the retention basins are capable of storing massive amounts of combined sewage. However, even with such measures in place, combined systems still get overloaded and are forced to release the holdings to their respective waterbodies.
"You're still going to have back ups," Nigro said. "In a highly urbanized area like southeast Oakland County, the storm system alone isn't going to handle every single rain event. There's a certain level of service they are designed to provide. People think that if there's a backup from a rain event, then something must have failed, but that's not necessarily the case."
Nigro likened the system’s design to that of a freeway system – while a 12-lane highway may help move the heaviest flows of traffic during peak times, such a system will be virtually empty most of the time – and have higher costs.
"The same can be said for storm systems," he said. "It's not designed for Noah's flood because it would be unachievable, practically, and the cost would be unbearable. If you can imagine separating that system (into a single sanitary sewer system), it would have a $2 billion bill. Nobody likes paying their bills now. Multiply them by 10 or 20 times – it's not practical."
In addition to the high cost of converting combined systems, Nigro said there isn't consensus that such a conversion would actually increase water quality downstream.
"Some say it's a bad idea to separate them, others say it's good to separate," he said. "When you do separate them, that stormwater goes right into the lakes, rivers and streams without being treated."
That means stormwater runoff from Woodward, I-75 and other urbanized or heavily-paved areas would flow directly into the Clinton and Rouge rivers, along with oil and other contaminants picked up along the way. Nigro said that in a combined system, at least the runoff is being treated to a degree, the same way sewage would be before it is sent to a treatment facility or prior to being discharged during an overflow event.
In general, both Combined Sewer Overflows (CSO) and Separate Sanitary Overflows (SSOs) can discharge untreated human and industrial waste, toxic materials, debris and disease causing organisms onto the ground or in lakes, streams and rivers. However, discharges from Retention Treatment Basins (RTB) are treated to collect and treat water before its discharged. The basins are designed to meet wastewater discharge permit requirements overseen by the state DEQ and to be protective of water quality and public health.
Each of the retention basin facilities use screening cells and operations to skim wastewater and allow heavy solids to settle and be removed. The water is held for at least 30 minutes for the treatment, which also includes a disinfectant treatment.
Secondary treatment of wastewater is done at wastewater treatment plants, which removes 85 to 90 percent of the remaining pollutants before being released. Because separate sanitary sewer systems don't carry stormwater or route through retention treatment basins the way that combined systems do, SSO's typically occur at wastewater treatment plants that get overloaded at manholes along the system lines where blockages may occur.
"I wouldn't want to swim in it, or even after it's had secondary treatment, but those retention basin facilities are designed to meet water quality standards," said Dan Beauchamp, statewide program coordinator for the DEQ. "For that matter, I wouldn't say to swim during any wet weather events."
Beauchamp said the retention basins in Oakland County meet all state discharge standards. Those standards, he said, are already more stringent than what the federal Environmental Protection Agency (EPA) requires.
"They do screening, settling and disinfecting, and they have permits for these basins and have to meet limits for E. coli and other contaminants," he said.
Still, Beauchamp said, as did Nigro, the retention basins aren't designed to eliminate all discharges; rather they aim to reduce them and ensure water released during discharges is treated to a minimum standard.
"The facilities are designed for a certain amount of control," he said "They must meet a presumptive criteria, which in a one-year capture is basically one inch of rain and 30 minutes of detention time, or basically 30 minutes for a 10-year event, which is about 1.8 inches. If a facility builds to that size, they are presumed to meet water quality standards at any type of receiving stream. They also have an option to build a demonstration size basin, which would be smaller than the presumptive size and do water quality monitoring and modeling. The majority of facilities don't build to the presumptive size – they build to demonstration size and do monitoring to ensure water quality standards are met."
The Oakland County Water Resources Commissioner's Office operates four retention treatment basins in Oakland County, including three that discharge into the Rouge River and one that discharges to the Red Run Drain, a tributary of the Clinton River, during heavy rain events. All of the facilities receive water from combined sewer systems in Oakland County.
The largest of the four retention basins, and that which receives the most scrutiny by those in Macomb County, is the George W. Kuhn retention basin, or GWK, formerly known as the 12 Towns drainage district and retention basin.
Originally located between I-75 and John R, north of 12 Mile Road in Madison Heights, the facility was updated and expanded in 2006. That expansion was done to meet the DEQ's permit requirements for treatment of combined sewer overflows. Storm drains discharging into the basin were removed and rerouted to provide more volume to control combined sewer flows, with storage at about 124 million gallons. The basin reduces overflow volumes by about 875 million gallons per year, and has eliminated all untreated combined sewage by rerouting two combined sewers into the basin that would have entered the basin downstream of screens and disinfection facilities.
The GWK drainage district has historically averaged about 10 treated discharges per year, all of which go to the Red Run Drain. During normal operations, when the system isn't overloaded, flows are returned to the collection system for processing at the Detroit Wastewater Treatment Plant.
The GWK serves 24,500 acres upstream of the Red Run Drain, including all or part of 14 communities, including Berkley, Birmingham, Clawson, Ferndale, Hazel Park, Huntington Woods, Madison Heights, Oak Park, Pleasant Ridge, Royal Oak, Southfield, Troy, Royal Oak Township and the Village of Beverly Hills.
Three other retention basins in Oakland County discharge overflows into the Rouge River.
Constructed in 1997 for a cost of $11 million, the Acacia Park RTB was part of an $82 million national demonstration project intended to eliminate combined sewage overflows in the Rouge River watershed. The retention basin serves 816 acres and treats about 70 million gallons of combined sewer overflows each year, of which about 19 million gallons are discharged to the Rouge River. The basin has a capacity of about four million gallons, and is designed to provide 30 minutes of detention time for a one-year, one-hour storm. It serves the Village of Beverly Hills drainage district community.
Flow to the Acacia Park RTB is regulated by a tipping plate that diverts flow of more than four cubic-feet per second to a 10-foot diameter influent tunnel, which provides about 400,000 gallons of storage. As cells are filled, the facility provides disinfection, settling and skimming of stormwater and sewage. Treated flow exceeding the storage capacity of the cells is screened and overflows via weir troughs to an effluent channel that discharges into the Rouge River.
The WRC said that discharge water quality consistently exceeds water quality from separated storm sewers upstream and downstream from the basin. Retained flow is pumped back into the Evergreen Interceptor for treatment at the Detroit treatment facility. After the basin is dewatered, a pivoting trough flushes the system of any remaining sediment.
The Acacia Park basin is located in the Village of Beverly Hills Nature Preserve. In 2009, the WRC completed chlorine minimization improvements to reduce the amount of chlorine in discharged water. Other control system improvements have also been made to the facility.
The Birmingham RTB, at the Birmingham Municipal Park, services a 1,185-acre watershed, treating about 71 million gallons of CSO annually, of which about 18 million gallons are discharged to the Rouge River. The basin has a capacity of 5.5 million gallons, which is designed to provide 30 minutes of detention time, or a one-year, one-hour storm. It serves the Birmingham drainage district community.
The Birmingham basin receives gravity flow from a 12-foot by 18-foot influent sewer, with five million gallons of storage provided in an upstream tunnel. Flows are treated by disinfection, settling and skimming through screened cells.
The Bloomfield Village Retention Basin is located below the eighth fairway of the Lincoln Hills Golf Course in Birmingham. The basin serves 2,325-acres of the watershed and treats about 122 million gallons of CSO annually, of which about 23 million gallons are discharged to the Rouge River, and has a capacity of about 10 million gallons.
Beauchamp said there are several factors that determine whether a discharge is necessary. For instance, the intensity of the rain, the makeup of the ground sediments, ground saturation and the water table determine how much rain will be absorbed by the land or sent to storm sewers. With hard clay in both the Clinton and Rouge, the rivers are "flashy," in that they are quick to flood and quick to drain.
Large capacity retention basins are one way of reducing the amount of overflows in a combined sewer system, but new technology and environmentally friendly approaches to design may also provide benefits.
Nigro said further reducing overflows may be done by implementing "green infrastructure," rather than building a larger basin. The approach means using more porous pavements that capture water and allowing it to flow through the pavement, rather than running off, and other improvements that reduce the amount of water entering the system.
"Gray infrastructure would be building additional storage capacity for fewer rain events that exceed the volume, but those are expensive – but work with instant results," he said. "Alternatively, more green infrastructure approaches would be infiltration. Instead of letting water run off into the system, the idea is to capture and detrain it, and infiltrate it into the ground.
"If you have a lot of clay, which a lot of this area does, you can't infiltrate that much water very quickly. There are things that make that more of a triple-bottom line. It's socially, economically and functionally good. You may see bioswales with plantings instead of a catch drain, but they don't have that much of an impact alone. It would have to be a change of mind in the whole area, and it has to be maintained. It's a change that long term, you'll see more green infrastructure and it will have a solid impact, especially in areas that are still developing. In older ones, undoing the old ways is expensive."
While elected officials in Macomb County continue to push for reforms within some of Oakland County sewer systems, watershed groups monitor the health of the rivers both upstream and down.
"It's a very complicated issue, not only from the environmental aspect, but from the location aspect, as well as the political aspect," said Eric Diesing, an environmental scientist with the Clinton River Watershed Council. "Between Oakland and Macomb counties pointing fingers at each other, when you look at watershed issues, which is a 10-foot point of view, it allows you to address the issues on a whole. A lot of rivers and watersheds deal with these issues around the country, and a lot of it comes down to aging infrastructure, and a lot of times it was never updated. We have seen progress, but we have a long way to come. We have come a long way from 'the solution to pollution is dilution,' as they said in the old days."
With the Clinton River Watershed containing more than 760 square miles and a population of more than 1.5 million people and massive development, it's natural for impervious surfaces to be increasing, and in turn, more stormwater runoff.
"The headwaters are in Clarkston and Independence (townships), but it flows through several lakes and underneath the city of Pontiac," Diesing said. "From Auburn Hills to Utica, the river has a 300-foot drop in elevation, so it picks up and starts moving through there. We have a very flashy system, partially due to elevation and partially due to development. It's moving a large amount of water very quickly. That's how some of these overflows happen. The systems get overworked and filled up so fast that it can't handle the water. "
Despite increased flows, Diesing said the council is seeing positive trends at most testing sites. That, he said, can be attributed in part to infrastructure improvements to combat stormwater.
"We focus a lot on stormwater education, and fish and wildlife habitat," he said. "It's all interrelated. Stormwater is one issue, but a lot of things need to be looked at as an overall view. There's not just one thing affecting a river or lake."