Combined Sewer Systems: How One City Is Coping

March 24, 2000

Pundits offer a variety of reasons for the problem of “why America’s cities are going down the drain.” Ironically enough, considering the projected costs of solving the problem, one of the reasons rarely mentioned is those drains–specifically, sewer and stormwater drains and systems. 

Municipalities built in the latter half of the 20th century created their infrastructures for a different set of codes than those in place when most major American cities were designed. Beginning in the 1950s and ’60s, sanitary sewers and storm sewers were often separated in new developments. Although the initial costs may have been higher, these dual systems were better prepared to meet the changing federal regulations that developed in the last 30 years of the century. As an added “bonus,” unexpected rain events also didn’t put such a strain on the sanitary system; a heavy downpour usually did not cause citizens’ basements to fill with raw sewage.

Older US cities aren’t so fortunate. Most still contain miles of combined systems, and in many cases the cost and disruption of separating them would be a heavier burden than taxpayers would tolerate. However, the problem must be solved; not only must stormwater be managed to more exacting standards, but also sanitary system overflows are not acceptable to residents and governments at every level.

“Our first sewers were built in the late 1800s,” says Martin Umberg, sewers chief engineer for the Metropolitan Sewer District of Greater Cincinnati (MSD). “Actually, the first were storm sewers, designed to move rainwater away from populated areas.” The reason? In the early 19th century, sewage was dealt with on a building-by-building level; outhouses were the responsibility of those who built them, and the waste usually didn’t leave the site (although some did impinge upon groundwater). When “indoor plumbing” became more common in the latter part of the century, homeowners installed septic tanks or fields, a procedure still common in some areas. However, metropolitan areas with little or no open land had to find other outlets for waste, and the storm sewers were given a second use.

“At one time, it was thought a good idea to have them combined–water keeps the sewage moving along,” Umberg explains. “Now in most areas we have two sets of pipes; we treat the sewage and just divert the stormwater.”

The existing combined sewer systems still pose problems, and Greater Cincinnati’s MSD must develop solutions, at an estimated cost of several billion dollars.

If the Suit Fits, Fix It
In late 2001, the Sierra Club notified the MSD, Hamilton County, and Cincinnati that it intended to sue them for allowing raw sewage to flow into waterways. Alleging that more than 100 overflows discharged raw sewage and industrial waste into the Little Miami River and Mill Creek (and, eventually, the Ohio River), the Sierra Club estimated the governing bodies were in violation of the Clean Water Act during 198 days of 2001. Unfortunately, MSD’s storm sewers were designed to overflow in wet weather, and, even if separated, sewer systems alone can overflow, as excessive rainfalls can fill sanitary sewers with rainwater. (This can happen due to excessive infiltration, from cracked pipes and from inflow of illegal storm drain connections.

“Cincinnati is not unique in having combined systems,” MSD Manager Bob Campbell points out. “There are 87 other cities in Ohio alone.”

The MSD had not been ignoring those problems; for some time, it had been negotiating with the US Department of Justice (DOJ) for an affordable way to eliminate overflows, a problem the DOJ had been addressing nationwide since the early 1990s.

In first quarter 2002, a federal consent decree, negotiated between MSD lawyers and the DOJ, the USEPA, and the Ohio EPA over the previous six years, was made public. A proposed interim partial consent decree for the remediation of the 17 most active sanitary sewer overflows in Hamilton County mandated that these problem areas would be eliminated within five years, by 2007.

Long-term solutions were mandated under the global consent degree, which require MSD to implement the program addressing overflow problems by February 2022, unless the cost exceeds the then-expected $1.5 billion. At such time, MSD would be given additional time to complete the projects. According to the decree, MSD must:

  •  Design and construct 24 projects to reduce and eliminate combined sewer overflows (CSOs)
  •  Update its CSO Long Term Control Plan by June 2006
  • Enhance operations programs to minimize overflows, to respond to overflow reports, and to notify the public when they occur
  • Invest $5.3 million in habitat improvements, streambank stabilization, greenway development, and brownfield remediation
  • Pay $1.2 million in civil penalties for federal and state agencies (for former overflows)
  • Create a comprehensive response program for water-in-basement complaints (and prevent such from occurring)
  •  Develop and implement a Capacity Assurance Program to ensure that the sanitary sewers have enough capacity to prevent overflows
  • Construct any facilities needed by February 2022 (More time will be granted if the $1.5 billion cost is exceeded.)

Public Input Before Implementation
In late 2005, MSD began presenting its plans to the Greater Cincinnati public. A series of open-house forums were held, to gauge what problem areas were most important to residents and which proposed solutions garnered the most support.

“Public health is of the utmost concern,” says Kathy Rahtz, MSD’s supervising management analyst. “We monitor local waterways for dissolved oxygen, conductivity, pH, and temperature, as well as nutrients, metals, total suspended solids, BOD, and bacteria. We test downstream from overflow points and stormwater inputs. We’re also monitoring the Ohio River.”

“Everything eventually gets into the Ohio. Luckily, the dilution levels are such that any pathogens, such as E. coli, will be harmless by the time they get downstream to Louisville,” says Bob Campbell. “That’s why we don’t worry about [upstream] Pittsburgh.”

Some pollutants might not be all Cincinnati’s fault; tributaries such as the Great- and Little-Miami Rivers run through other heavily populated areas before reaching Hamilton County. Will other Ohio counties be donating funds to the project?

“The State of Ohio and the USEPA regulate the other counties too, but we’re not going to get money or help from them. Northern Kentucky is now also under a consent degree and is working on its own plan,” Rahtz explains.

Cincinnati MSD consults with other cities in the same situation: “We belong to industry groups such as the National Association of Clean Water Agencies; we compare notes and information from around the country. We also belong to a five cities conference, which includes St. Louis, Louisville, Columbus, and Indianapolis–so we know what other cities are doing and get ideas from them,” she adds.

During a series of public meetings in fall 2005, MSD outlined the problems and possible solutions:

  • “Upgraded CSOs.” Ideas were presented on collecting more water with the existing system; one means is to use inflatable dams. If the flow exceeds a certain level, the dam deflates so nothing backs up into basements.
  • Storage tanks were offered as an option. Underground tanks would hold onto overflows until more system capacity was available.
  • Building parallel pipes and/or new sewers would definitely increase capacity, but its cost is prohibitive, and the installation would be highly disruptive to neighborhoods and area traffic.

Upgraded treatment plants were also suggested; such a solution would offer a high rate of treatment, moving more water through the system. “Satellite treatment plants” that would safeguard a particular problem locale were also offered as an option.

Campbell emphasizes, “The water-in-basement issues must be eliminated. As for the sanitary portion of the flows, we must have reasonable capacity for dealing with it. MSD must reduce CSOs, and we need public input to establish priorities of how/when we tackle these issues. As for overflows, local streams that have very high “˜recuperation potential’ might have to be used more. In any case, a combination of options must be used to combat overflows.”

As for projected costs, Campbell says the total price is “to be determined,” but that the massive project “probably will exceed $1.5 billion.” Which revenue sources will fund this project? “Right now, our primary source of income is user rates,” he notes. “We will work hard to find funding outside of the city,” he adds, citing possible federal and state financial help.

The public was asked to offer priorities; as could be expected, residents were most concerned about the waterways located in their neighborhoods, as well as those streams that were easily accessible to people–specifically, children.

Drafting a Plan
In early 2006, MSD developed its draft plan, which also included input from Cincinnati City Council and Hamilton County Commissioners. The amount of input garnered caused delays in the next round of public comment meetings; originally slated for March, the public reviewed the plan in late April and early May.

During the meetings, Campbell stressed that “the wet-weather program is more to solve overflows, not to replace the sewer system. We must comply with the Clean Water Act and consent decrees, but we must balance costs versus benefits versus environmental regulations. We need to improve local water quality and quality of life here, but we’re also concerned about costs.”

As one might expect, the public survey results stressed that residents’ health was the most important factor (80% of respondents). Sixty-seven percent of the public also thought that sites with the worst pollution problems should be given first priority. With those facts in mind, MSD’s goals were outlined: 

  • Maximize reasonable capacity, to achieve no overflows in a typical year (events such as 100-year storms excepted).
  • Reduce sewer overflows, with priorities given to environmentally sensitive areas, headwater areas, and urban streams with easy public access. Streams with “strong recovery potential” would be utilized more often.

Detailed work plans were offered for each of the county’s watersheds. “Our selection and solutions were made on impacts on existing conditions,” Campbell explains. “We gauged the effects on public health and water quality, the area’s expected future needs, the affordability and cost/benefit of alternatives, and the local community’s values and priorities. More weight was given to residential projects.”

A total of 380 projects, located in 34 Hamilton County municipalities and townships and 30 Cincinnati neighborhoods, were outlined. The work is scheduled to begin in 2007, at an estimated cost of $2 billion.

Along with overflows reduced in typical year, MSD wants to reduce the number of combined systems. When overflows do occur, odor and debris will be reduced, resulting in cleaner streams. One important goal: no more water in basements.
To increase capacity, 94 new sewer projects are planned, which will capture more flow for treatment. These new projects should reduce storm- and groundwater infiltration, as well as inflow from cracks and breaks in existing pipes. 

Thirty projects of high-rate treatment are proposed, which will screen solids and debris in wastewater, and then disinfect the water before it’s released into the environment.

A total of 18 storage projects should allow the system to “catch its breath” during heavy rains, resulting in no overflows.

Where available land allows, 65 sewer separations are planned, to separate storm from sanitary sewers. Such separation will keep some stormwater from treatment plants, which are often overburdened.

Eighty-six regulator improvements and 11 pump stations are proposed, which control how wastewater flows through the combined system. These improvements will increase capture of wet-weather flow.

Twelve projects will upgrade treatment plants, increasing capacity and providing additional wet-weather safeguards.

Eighty-four projects were listed as “miscellaneous,” including lining deteriorating sewers to extend their life. Installation of inflatable dams to store excess water was also mentioned in the plan, as well as installation of grit pits, which would separate grit and dirt from wastewater before it reaches treatment plants.

Campbell highlighted some specific projects. “Muddy Creek [a natural waterway that winds through Cincinnati’s heavily wooded west side] will receive a stormwater storage release tunnel, which will keep the water out of the wastewater system, until capacity is such that it can discharge to the Ohio River.”

On the city’s high-end-residential northeast side, Sycamore Creek will receive a treatment plant optimization. “These sanitary sewers act like stormwater sewers,” Campbell explains. “We have to find out how to stop that.” 

Mill Creek, a sometime-natural waterway that has been lined with concrete for its run through the city’s heavily industrial midsection, will receive separated sewers, as well as gain a storage tank.

Filling the Bill
Along with the “good news” of problem solving, Campbell announced the “bad news”: Projected costs have now crept up to $2 billion. As the USEPA had stated that costs above $1.5 billion would allow MSD more time, MSD will apply for an extended deadline.

“This project will increase user rates,” Campbell says. “We hope to not exceed 2% of median household incomes. Rate increases will apply to all MSD customers. Of course, the actual amounts will depend on how many people are paying the bill,” he adds, an acknowledgement of Cincinnati’s steady population decline.

Rates must generate the revenue required for this project. Future user rates will depend upon the economy, the number of customers, inflation, and rising construction costs. If people keep moving out of the area, those of us left will have to pick up the slack.”

As a comparison, MSD ranked its rates against other local utilities. Where typical Hamilton County residents paid $148 monthly for natural gas, $103 for electric, $60 for digital cable, and $45 for high-speed Internet and phone service, sewer rates averaged $29, and water, $15 (figures as of February 2006). MSD expects annual rates to continue increasing throughout the life of the program, although it hopes to keep increases to 10.5% per year or less. From 2006’s typical $29 per month residential bill, costs are projected to rise to $58 per month by 2022. (Estimates are based on information currently available.

Campbell did offer a ray of hope: Projects of this magnitude cannot be handled solely by local firms, and MSD’s tasks will likely require an influx of construction crews from around the country. “The temporary workers coming into the county will generate millions of dollars for the local economy,” he says, adding that he did not anticipate any assistance from the US Army Corps of Engineers.

After further public comments, the plan was further revised, as its final draft was due to USEPA by June 30, 2006. “We hope the USEPA will approve it by January 2007 so we can get under way,” Campbell says. 
About the Author

Janis Keating

Janis Keating is a frequent contributor to Forester Media, Inc. publications.

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