Separating Sewer Flow

The City of Hamilton is taking a progressive approach to eliminating cross connections.

Separating Sewer Flow

Hamilton (Ontario) Water crew members excavate to expose a cross connection between the sanitary and storm sewer systems. The discovery of E. coli in a local waterway 20 years ago led to the establishment of the utility’s Sewer Lateral Cross Connection Program.

(Photographs contributed by the City of Hamilton) 

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Hamilton, Ontario, has a long history. The beginnings of its wastewater system date back more than 160 years, but its future is taking a divergent path thanks to a program that started just a decade ago.

The port city is situated on the western side of Lake Ontario with a population of 550,000 people. The Niagara Escarpment runs through the middle of the city across its entire breadth, producing roughly 92 miles of watercourses that flow through Hamilton and naturally feed into Lake Ontario. Protecting them is a significant concern.

The city has two types of sewer systems: a separated system with separate lines for wastewater and stormwater, and a combined system that exists in older parts of the city. That system sends both stormwater and sewage directly to the wastewater treatment plant. Once the water is cleaned, it flows into Hamilton Harbor. The city has nine large storage tanks that can hold close to 80 million gallons of diluted wastewater in the event of extreme rain or snowmelts, so it’s rare that the city’s treatment plant is forced to release wastewater into the harbor.

Making connections

At the end of 2001, the Ministry of the Environment, Conservation and Parks notified the city that there was E. coli present in Red Hill Creek. Given that rainwater washes animal waste into streams and rivers, it’s not uncommon to find E. coli in watercourses when there are big rain events.

“It was important that we understood where this E. coli came from, so we ran a series of tests in storm sewer outfalls upstream of Red Hill Creek to determine if human waste was a factor in this E. coli discovery,” says Calvin Huizinga, project manager for the utility’s Sewer Lateral Cross Connection Program. “Unfortunately, the results indicated this was the case.”

The city discovered that part of the problem was cross-connected sewer laterals from residences where builders had mistakenly linked sewage outputs to the storm sewer system. In addition, there were partial cross connections that typically occur from homeowner renovation projects, with new plumbing fixtures being connected to an internal storm drain.

Hamilton immediately launched a sampling program in 2002. “The starting point was easy — we investigated the surrounding catchment area for Red Hill Creek,” Huizinga says.

Crews sampled the storm sewers, and upon a positive result, they deployed CCTV into the storm sewer system during dry weather to look for the source of entry for human waste. Once the source was determined, the city contacted the homeowner to advise them of the situation so that they could gain access to their internal plumbing. This would allow crews to run a definitive dye test and another CCTV inspection to identify where the cross connection took place. Two-hour on-site investigations cost Hamilton around CA$650.

Stepping up

In two years, the utility investigated 153 storm sewer outfalls that were part of the two most significant (and environmentally sensitive) watershed areas in the city: Cootes Paradise and the Red Hill Valley. They identified concerning levels of E. coli in 31 streams, indicating a high probability for cross-connection contamination.

“Unfortunately, we were met with some resistance from residents to gain access to homes for dye testing,” Huizinga says. “Homeowners were concerned that they would be found at fault, resulting in fines and costly repairs. Our primary concern was to stop the flow of this raw sewage through the drains as it posed a serious health risk and environmental contamination at its final harbor destination. So, in 2009 the city chose to waive owner liability, which significantly improved resident cooperation in giving us access for the final confirmation of what we suspected.”

Hamilton looked for ways to expand the program by identifying other hot spots, conducting regular testing and fixing the cross connections wherever they occurred. In 2009 the Sewer Lateral Cross Connection Pilot Program was initiated, gaining momentum over the next several years as resources and funding were added. Today it’s a permanent program with two full-time employees and a $700,000 annual budget.

“We are saddled with one of Canada’s oldest water systems, so we have learned how to get creative and put our heads together to find a way to get the job done,” Huizinga says. “One corrected cross connection diverts approximately 59,438 gallons of sewage out of watercourses and into the treatment system each year. This has a significant impact on the health and safety of our residents and the health of surrounding ecosystems, which is why the city stepped up to fix these cross connections at a cost of $7,200 per residence for the full repair and restoration.”

Partial cross connections represent 10% of all identified cross connections in the city. Since the repair is required within the household, the city is not able to fix the connection. “We are still looking at ways to deal with partial cross connections. It’s tricky because none of these problems were the fault of the city, but we are dealing with this effluent in our storm system, and our top priority is to stop it,” Huizinga says.

Since 2010, the program has inspected 183.8 miles of storm sewer, which represents nearly 25% of the total storm sewer system. The city has conducted more than 615 dye test investigations, positively identified 376 homes with complete cross connections and conducted 376 repairs. This amounts to one repair for every 0.47 miles of inspection. This translates to more than 22,348,955 gallons of sewage being redirected from city watercourses and the natural environment each day and into Hamilton’s wastewater treatment facilities. Or put another way, approximately 34 Olympic-size pools of sewage are prevented from flowing into the lake every year.

In addition to field investigations and repairs, Hamilton has also made changes to the building inspection program and created new bylaws to help prevent future cross connections. New subdivisions are now required to dye test private sewer laterals to ensure they are correctly connected.

“The Sewer Lateral Cross Connection Program is an integral contribution to the improvement of water quality in many of the watercourses within the city, including Hamilton Harbor and Lake Ontario,” says Cari Vanderperk, director of Watershed Management for Hamilton Water. “The city is committed to fixing this legacy issue and has identified and repaired a number of cross connections across Hamilton. To date, cross-connection corrections are diverting 22.3 million gallons of raw sewage per year from our local receiving waters.”

Leveraging data

In 2017, municipalities in Canada and the United States with cross-connection issues were contacted to complete a survey for industry review. Participants were provided an overview of the City of Hamilton’s program and were asked to provide information about their own programs. Of the returned survey responses, only the City of Toronto and the Boston Water and Sewer Commission had well established programs in place.

“This was definitely surprising to us, as cross connections are not an uncommon problem, yet it was clear that our relatively small city already had a mature program in place,” Huizinga says.  “Furthermore, we discovered that we had corrected twice the number of cross connections per staff and at 12% less cost.”

The city also partnered with Redeemer University’s Environmental Studies program as they began actively monitoring water quality in the Chedoke Creek watershed in 2012. “Our students collect and analyze samples for a variety of biological and chemical contaminants. Nitrates, E. coli, total coliforms, phosphorus, chlorides (from road salt) and several others are being studied,” says Edward Berkelaar, professor of chemistry and environmental science for Redeemer University. “It only makes sense that we share our findings with the city as we all have the same vested interest in restoring the health of Hamilton’s watersheds.”

Hamilton, in turn, provided some further insight into the civil side of how collections systems operate. “Environmental stewardship is all of our responsibility and the students of Redeemer are our future policy makers, water scientists, operators and engineers. Partnerships like this accelerate a successful outcome,” Huizinga says.

A Redeemer University independent student research project started in 2018 looking specifically at Microbial Source Tracking of Fecal Contamination in Hamilton’s Chedoke Watershed. Using cutting-edge lab equipment, the student was able to perform quantitative polymerase chain reaction (qPCR) lab procedures to isolate and amplify specific characteristics of the DNA to identify if the bacterial contamination was human or otherwise. Two of the seven sample locations registered human fecal contaminations of 10% and 13% of the total E. coli and five of the locations registered indiscernibly (less than 3%) small amounts.

“While the methodology and application of this technology is fairly new at Redeemer University, we are all keen to better understand the sources of contamination within our watersheds and to quantify the positive environmental impact of repairing cross connections,” Huizinga says.

The utility has already inspected 25% of the storm sewer system, and plans to continue inspecting 28.5 miles every year until the entire separated sewer system has been reviewed. In addition, they have expanded the scope of the program to include other potential sources and causes for sanitary sewer cross contamination. With over 186 miles of coded CCTV storm sewer footage as a result of searching for cross connections, it makes sense to leverage this data for a deeper structural pipe condition assessment.

“We plan to work with environmental engineers to use this data with additional infrastructure records and innovative software to pinpoint other potential sources of sewer cross connections, such as improperly abandoned sewer lines or sewer exfiltration,” Huizinga says. “Diverting 22,348,955 gallons of sewage from the environment every year is something we are very proud of, but with human E. coli still present at outfalls we still have lots of work to do.” 

Dave Alberton is the manager of Water Distribution & Wastewater Collection for Hamilton Water, and Donald Young is superintendent of Water Distribution & Wastewater Collection.


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