by Martin Doyle
Though the ecological costs were thus easily dismissed, it was harder to stomach the colossal financial toll. Re-plumbing a city required digging up and rebuilding entire city streets—a huge burden when added to the growing list of responsibilities and costs borne by city governments. As more people moved into Chicago, as with any city, the infrastructure had to be scaled up and extended farther from the city center as overcrowded residents sprawled outward. And Chicago’s government needed to fund those developments in addition to the costs associated with reversing the Chicago River.
The switch from the privy vault system to the water carriage system, along with the switch from water cart or private well to piped-in water, shifted urban water systems from a labor-intensive approach toward a capital-intensive approach. Privies had required unskilled laborers working constantly at what must have been a horrendously nauseating task. Though the technically complex water carriage system would be largely self-operating once complete, it required planners, engineers, and enormous construction crews to design and build it. Water sources had to be identified, pumps built, and water mains constructed. Sewer systems had to be planned along topographic gradients that kept the water and waste moving continuously until it was eventually disposed of.
All of the houses and businesses had to be connected to the sewer lines. The route from the water source to the city, and from the city to the “toilet” of the waste stream, had to be surveyed by engineers, geologists, and planners. It had to be laid out in ways that balanced hydrologic and political realities of private property and myriad political subdivisions along the route of pipes and canals it had to cross. As such complications mounted, the costs of projects regularly exceeded municipal revenue many times over. These enormous costs came at the turn of the twentieth century, when the financial structure of the United States was undergoing its second great reordering.
From the founding of the United States through the Panic of 1837, state governments were the fiscal center of revenue and finance. After 1837 the financially crippled state governments had fiscally contracted, leaving their citizens’ underserved needs to be filled by local governments. Consequently, the budgets of local governments grew dramatically in terms of the debt they took on to finance new projects as well as the revenue they took in to service this mounting debt. The growing debt took the form of the increasingly ubiquitous municipal bond.
As cities grew, and their revenue grew, “muni bonds” were seen as stable investments. When representatives of Chicago went to New York City to sell $400,000 worth of municipal bonds to finance Chesbrough’s proposed sewer system along with other necessary water supply infrastructure, the bonds sold so quickly and were in such demand that representatives were able to sell a second round of bonds at far more favorable rates for the city. Throughout the late nineteenth and early twentieth centuries, Chicago’s water and sewer bonds sold at interest rates comparable to those for American railroad bonds—one of the most stable private investments available. The City of Chicago and these new municipal water bonds in general were being seen as reliable, long-term investments within the broader investment markets.21
This fiscal soundness was not limited to Chicago: in the Panic of 1837, many state governments were unable to cover their debt; but during the Panic of 1893, which struck at the zenith of municipal fiscal growth, municipalities came out showing robust financial stability and certainly fared much better than the vast majority of private businesses. From the Panic of 1893 on, municipal bonds were considered extremely stable investments; boring, but steady. This growth was beyond what was occurring in the state and federal governments, which had contracted by a comparable amount. By 1902 local government tax revenues exceeded state revenues by 260 percent and national government revenues by almost 40 percent. Cities were now the fiscal heavyweights of governments.22
In 1905, waterworks—water supply and wastewater systems—had become the largest line item in the debts of municipal governments. In fact, waterworks costs often exceeded total revenue of even the largest cities: Chicago’s waterworks in 1915 was valued at over $350 million, and yet the city’s total municipal revenue was only $206 million: a 1.7 ratio of water cost to revenue. The ratio for Los Angeles was 1.48; for Harrisburg, Pennsylvania, 1.68; and for Ft. Worth, Texas, 2.32. Normally, such rapid growth in demand for debt would cause a corresponding increase in interest rates. Yet the growth in demand for municipal debt was not matched by high or rising bond yields. Bizarrely, municipal bonds continued to be characterized by relatively low interest rates amid ever-growing municipal indebtedness. Economists David Cutler and Grant Miller have suggested that this rise in municipal debt and lack of a corresponding rise in interest rates at the turn of the twentieth century was made possible by the development of increasingly sophisticated financial instruments. That is, the growth of the financial sector—of Wall Street itself—was part and parcel of facilitating the nation’s municipal water infrastructure.23
The final monetary revolution devised by Chicago’s water and sewer engineers, and eventually adopted by other cities, was an obscure but critical administrative and fiscal development: the special district. In Chicago’s case, the special district, originally named the Sanitary District of Chicago, has been known since 1955 as the Metropolitan Sanitary District of Greater Chicago. Special districts were essentially an intermediate level of government in terms of size: they were under states but often spanned several municipalities. What made special districts useful was their fiscal and administrative independence from government entities. While municipalities were responsible for a range of functions within political boundaries from garbage removal to police forces, special districts could focus on specific services and had the flexibility of covering more regions on the basis of what made the most sense for each service.
In Chicago, city officials soon realized that the hydrologic landscape did not conform to the political boundaries of the city; the suburbs and newly connected upstream regions, which were part of the sewer system, extended well beyond Chicago’s municipal limits. For the city, these suburbs were part of the problem because their existing drainage and sewage systems continued to route their waste directly into Lake Michigan. Thus, if the sewer system were constrained to the city of Chicago itself, the lake would still be polluted as long as the suburbs continued on their own independent paths. Residents of these outlying communities did not want to become part of the City of Chicago proper, but they did want to be part of the new drainage district. The use of a malleable special district allowed a broader geography of water and sewage service for suburbs of Chicago.24
Special districts also led to the implementation of new methods of financing government services, marking a continued fiscal evolution in the United States. In the early nineteenth century, state governments had relied on asset financing for revenues. That is, state governments financed infrastructure and then used the tolls paid by users of that infrastructure to service the debt incurred in building the infrastructure as well as cover the costs of daily operations. Meanwhile, municipal governments relied on property taxes, and the national government continued to rely on tariffs. Because local city governments bore the burden of providing most services in the early twentieth century, by 1902, property taxes accounted for 42 percent of all government revenues (national, state, and local levels combined).25
Following the innovation of the sanitary district in Chicago, the financial and administrative structure of the water and sewer district became a standard form of governance in the twentieth century. Other special districts formed, first in Illinois and then throughout the United States. The political and fiscal model of special districts, first established on the banks of a backward-flowing river, is the reason most city dwellers today pay their city a monthly water and sewer bill, based on the amount of water used, separate from taxes paid directly to the city.
CHAPTER 8
Burning Rivers
When a toilet is flushed in Durham, North Carolina,
John Dodson has to deal with it. Dodson is a gentle giant of a man; tall and broad, but unassuming and patient. Along with wastewater treatment plant operators across the United States, Dodson is always on call, just like a physician with a pager. But when John gets a call from work, the issue involves tens of thousands of people and their unspoken millions of gallons of sewage.
On an average day Dodson supervises the treatment and processing of about half of the wastewater produced in Durham, a city of about a quarter million people. Each day over 8 million gallons of sewage come to his plant—about twelve Olympic-sized swimming pools per day of human waste. Across America others like John Dodson are managing the unseen treatment of human waste: almost 15,000 wastewater treatment plants pepper the country, along with over 700,000 miles of public sewer mains. All of this infrastructure is effectively invisible to the public, assumed to be working sufficiently well to justify being blithely ignored.
The waste from any toilet in Durham is transported through the pipes from the building where it’s housed into larger collection pipes that combine with the many storm sewers of the city. Then it moves on to the sewage main—the large intestine of the city—where, along with the waste in thousands of miles of other pipes connected to countless other homes, buildings, and businesses, the collective waste is routed through ever more miles of pipe and pushed through the pipe system using sixty-six pumping stations spread through the city. Half of this waste eventually reaches Dodson’s treatment plant, which sits innocuously at the edge of town alongside Ellerbe Creek.
The modern wastewater treatment plant is an extension of the work of early twentieth-century sanitary engineers: waste can be naturally processed, given enough time and the right conditions. The right conditions inevitably mean the right microbes, and Dodson is fixated on “the organisms,” as he calls them, for his job is to ensure that the organisms have enough time and the right environment to do their work. When Sedgwick described streams and rivers as “self-purifying,” he was really saying that they naturally contain the necessary microbes to process the waste.
In the early twentieth century, when streams were relied on to purify sewage, it was the distance between cities that made this approach effective. In the time it took for sewage to move from one city to the next along the streams and rivers, the microbes could process the waste. However, as America’s population grew and cities expanded, the distances between communities decreased while the amount of sewage being loaded into the streams increased.
Modern treatment plants use the same fundamental processes to do the work of self-purifying rivers, but they have to do it in much less space. To accomplish this, modern sewage treatment plants use immense tanks that are constantly filling with wastewater. Some treatment plants serving small communities have tanks the size of home swimming pools. Others, like Dodson’s, serve tens of thousands of people and have tanks that look more like a series of Olympic-sized pools: accompanied by the noise of pumps and blowers, wastewater constantly moves from one pool to the other, with pipes here and there moving wastewater from one tank to another. As noted earlier, the key to sewage treatment is time. Self-cleaning streams gained time thanks to moving sewage over long distances; treatment plants create time by slowing down the wastewater almost to a standstill. Dodson’s tanks can slow down the millions of gallons a day and pass it through the plant in just under 24 hours, just enough time for the microbes to do their consumptive work. But the flow can only get so slow, because the tanks run close to capacity to save space—and all the while, more sewage is coming from the city as people keep washing dishes and flushing toilets.
Understanding what actually happens in a treatment plant takes a little microbiology. The main substance to be handled in sewage is the poop—alternatively, and perhaps preferably, called sludge. Besides sludge there are dissolved pollutants, primarily nitrogen and phosphorus, that environmental regulations require treatment plants to remove. Any substance or chemical is pollution only when it is present in excess; and though the large quantities of sludge and nutrients are pollution in streams, they are a feast for these “purifying” microbes.
Water treatment engineers have learned over decades that there are infinite varieties of microbes, each with its own peculiarity. Some microbes are like humans in that they consume oxygen and give off—respire—carbon dioxide. Other microbes are anaerobic; they live by combining sludge with carbon dioxide and respire methane. Still other microbes can use nitrate—a form of nitrogen—instead of oxygen or carbon dioxide.
These differences in microbes are what John Dodson must take into account. When he changes the flow or oxygen levels in the tanks, he will inevitably change the types of microbes that are doing the sludge eating. The design and engineering of sewage treatment plants is complex because it must provide a variety of ecosystems optimized for different microbes to eat the sewage. In natural streams, these various mini-ecosystem conditions exist in different places along the path downstream: oxygen-rich riffles and rapids provide habitat for some microbes while oxygen-depleted sandbars or stagnant pools are good for others. In wastewater treatment plants, the different habitats must be created at very large scales. When the different ecosystems are sequenced in the proper order, all of Durham’s sewage can be converted into specific by-products—whether carbon dioxide or methane—between the time the water enters the plant and the time it exits and runs into Ellerbe Creek.
When wastewater comes into Dodson’s plant from the sewer main, it is a grimy and smelly rivulet. As it enters the plant, the water passes through a screen to catch the large fragments of things in the water that microbes can’t digest. This first step is simply to “get the crud out.” After passing through the screen, the water—still viscous and rank—goes on to primary treatment: an enormous circular tank that looks and smells exactly like you might expect a sewage treatment plant to look and smell. This is where the initially foul work of treatment gets done. Each primary treatment tank is the size of a very large swimming pool and has a slightly cone-shaped bottom, where the sludge settles while the grease floats to the top. Scrapers and skimmers—long mechanical arms—do the work here: slow-moving scrapers creep along the bottom of the tank to force the settling sludge toward a collection hole at the bottom while skimmers at the top push the floating grease into collection troughs, from which it is first routed to a dumpster and then hauled off to a landfill.
The sludge has a more interesting fate. For most of the sludge, its next stop is a smaller circular tank with an enormous lid on top—an anaerobic digester. This little ecosystem has no atmospheric oxygen, and so the only sludge-eating microbes that can grow are the ones that convert the sludge into very small amounts of solids and very large amounts of methane, or natural gas.1 The methane is stored in an enormous gas tank and will be used for heating buildings. From the top of the three-story-tall gas tank, Dodson points to an enormous covered area a few hundred yards away, where bulldozers are busily pushing stuff around. That is where they dry the remaining biosolids into what is effectively concentrated fertilizer. Every day, dump trucks haul away seven or eight loads of concentrated biosolids to be delivered for use on over three thousand acres of farmland. Pointing out over the acres and acres of tanks, pools, pipes, and trucks, Dodson says that settling the solids is the easy part; the hard part is treating the dissolved nutrients. Anything dissolved in the water moves right along past the settling tank, like sugar dissolved in water. The two main soluble headaches in Dodson’s life are nitrogen and phosphorus. Despite the challenge of processing these two elements, environmental regulations require them to be reduced as part of wastewater treatment because of their effect on downstream ecosystems. This processing is done in the secondary treatment tanks.
Water coming to secondary treatment tanks is still gray-brown and foamy, laden with nitrogen and phosphorus. Whereas primary treatment was one big circular tank, secondary treatment takes the form of a very long rectangular tank broken up into a series of smaller, but sti
ll massive, sections. Each of the smaller sections is the size of a two-story house, and each one is sized specifically to ensure that the water spends the necessary amount of time in that section of the tank. Imagine a series of two-story houses with no roofs, lined up next to each other, each with a single open window in the second story. Water fills the house and pours from one house to the next through that single open window. To the naked eye, each sectioned-off tank looks the same as all the others, but every tank contains its own particular ecosystem with its own particular processes: one causes phosphorus to be released from the suspended sediment and become soluble in the water; another contains microbes that convert ammonia to other forms of nitrogen; another contains microbes that drive nitrogen out of the water and move it inertly into the atmosphere, and so on. Careful sequencing of conditions for microbes is the heart of wastewater treatment.
All of these microbes in secondary treatment must eat, and this need highlights one of the more interesting tricks of the modern sewage treatment plant. Some of the sludge from the primary treatment is mixed with incoming sewage and sent to this series of secondary tanks to feed the microbes. By the end of these secondary aeration tanks, the microbes are essentially out of food; they’ve eaten everything available to them, and the amounts of phosphorus and nitrogen dissolved in the water have dropped dramatically.
Even at this point, the water looks muddy and turbid; not as viscous, soupy, and frightening as when we started, but not something you would want to swim in, either. The next stop in the plant is where things visibly change. The wastewater flows into a second set of circular tanks, where the microbes come together and settle, leaving the “clean” water on the top. The water is then trickled through another filter: a bed of gravel, sand, and coal. When it comes out, it looks downright drinkable—but it isn’t, quite. From the filter, the water is funneled through a narrow channel that passes under bright ultraviolet lights to neutralize any remaining pathogens. Finally, it flows down a ditch that exits the treatment plant and leads into Ellerbe Creek. The contrast between the water coming into the plant and the water coming out is often stunning. In fact the water coming out of the plant is noticeably cleaner than the water in Ellerbe Creek, where Dodson points just a bit downstream to indicate some bass swimming in the output of his treatment plant.