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13 The Urban Wastewater Infrastructure BERNARD B. BERGER The urban wastewater treatment infrastructure is by tradition, prefer- ence, and engineering necessity either underground or so remotely located as to be out of sight. Still, system shortcomings or malfunctions are in time inevitably impressed on system users and almost always in disa- greeable ways. It would be tempting in this overview of system evolution to set aside for the moment the problems of today, to take a bold leap into the future and describe where we should like to be and therefore expect to be 50 years from now. Unfortunately, the problems of today cannot be ignored or solved simply by fiat; their solution will shape the wastewater infrastructure of the future. The function of the wastewater infrastructure is of course to protect public health and decency by carrying wastewaters away from those who generated them, to dispose of such wastewaters in ways that will not harm aquatic ecosystems or wildlife, and to present no significant hazard or displeasure to humans. The wastewater treatment infrastructure is not intended, and should not be depended on, to produce an effluent clean enough to keep a pristine receiving stream unchanged in purity and of drinking water quality. The main defense of the quality of drinking water is the drinking water treatment plant, not the wastewater treatment infra- structure. The systems are of course sequentially related, and sometimes they are combined. Separate infrastructures are traditional, however, and this arrangement, which has worked satisfactorily for years, is reflected in our political and professional institutions The main physical components of the urban wastewater infrastructure 278

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URBAN WASTEWATER INFRASTRUCTURE 279 are the collection system, the treatment plant, and the water body the receives the plant effluent. The tasks these components present to the "keepers" of the infrastructure go beyond improvements in technology, multiple and difficult as they are. The responsibilities of water pollution control authorities include developing more effective and reliable planning techniques for projecting system growth and modification, resolving cur- rent uncertainties in setting water quality standards for water bodies re- ceiving wastewater discharges, solving He troublesome problem of Heating wastewaters of industries using the public sewerage system, coming to grips effectively with the problems of combined sewer overflows and nonpoint runoff, finding acceptable ways for permanent disposal of sludge, and establishing an adequate and equitable funding base for operating, maintaining, and upgrading the wastewater disposal system. To place these tasks in perspective, the following sections of this chapter will describe the evolution and outstanding problems of the system's major components. THE COLLECTION SYSTEM The existing sewerage systems of most large municipalities, particularly the older cities of the eastern United States, are patchworks of pipes and conduits of various ages and sizes. Some were installed to convey both household sewage and industrial wastewaters, some serve only to collect and carry away storm-water runoff, and some are designed to transport both wastewater and runoff. The applicable terms are sanitary- sewer, storm sewer, and combined sewer, respectively. Chronologically, the sequence of development and use should be storm sewer, combined sewer, and sanitary sewer. Until about the 1 830s, with only rare exceptions, collection systems, many just open ditches, were designed for the sole purpose of carrying off storm-water runoff. Household wastes were to be placed for final disposal in privy vaults or cesspools, many of which served multiple families. Deposition of household wastes in storm drains was banned by law to prevent creating noisome conditions and public nuisance. This policy, which presumably reflected the best professional judgment of the late eighteenth and early nineteenth centuries, proved disastrous in a short time. This was evident in the filthiness of the city environment of the day, as suggested by Hogarth's well-known drawings and as attested to by writers of the period. A particularly vivid picture of an early morning in Edinburgh in Queen Anne's time is painted by G. M. Trevelyan in English Social History: Far overhead the windows opened, five, six, or ten storeys in the air, and the close stools of Edinburgh discharged the collected filth of the last twenty-four hours into the street. It was good manners for those above to cry 'Gardy-loo!'

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280 BERNARD B. BERGER (Gardez beaus before throwing. The returning roysterer cried back 'Haud yer hen,' and ran with humped shoulders, lucky if his vast and expensive full-bottomed wig was not put out of action by a cataract of filth. The ordure thus sent down lay in the broad High Street and in the deep, well-like closes and wynds around it making the night air horrible, until early in the morning it was perfunctorily cleared away by the City Guard. Only on a Sabbath morn it might not be touched, but lay there all day long, filling Scotland's capital with the savour of a mistaken piety. (1942, pp. 437-438) The Combined Sewer The discovery in 1849 of the role of the backyard cesspool in spreading cholera through a contaminated drinking water system, a landmark in protecting the public health, led to a reversal in wastewater policy and practice. Soon thereafter, household wastewaters had to be discharged into the nearest storm drain to be conveyed away from human habitation as quickly as possible. Thus, the storm drain became the combined sewer. From a cost-benefit point of view, the use of a combined sewer rather than separate sewers seemed to be obviously advantageous, and it soon became standard practice in the cities of Europe and the United States. The sizing of combined sewers was based on accepted assumptions about the extent of area to be served, population density, per capita wastewater . . contra buttons, wastewater discharges from commercial and industrial es- tablishments, rainfall intensity and duration, and physical characteristics of the ground surface. The combined sewer, which was so logical a development a century and a half ago, has in the past 25 years presented a major problem. This conclusion is based on the fact that it is simply not feasible from an engineering or economic point of view to provide sufficient capacity in such sewers to transport all of the runoff resulting from a heavy storm. Even moderate storms may produce flows far in excess of the combined sewer's carrying capacity, which is usually limited to about three times the average daily dry-weather flow. Overflow or relief devices are there- fore provided in the combined sewer to prevent the backup of sewage into basements at times of sewer surcharge. The overflows are discharged without treatment into nearby watercourses. Given the apparent logic of the planning assumptions, design engineers of the early city systems believed that the life and utility of the combined sewer would be affected only by deterioration of materials, which could readily be repaired. Unfortunately, in many cities the planning assumptions proved to have their own life expectancies, and over time they failed to hold up. The populations connected to the sewer increased, as did the per capita sewage contribution. In many cities the area served by main sewers

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URBAN WASTEWATER INFRASTRUCTURE 281 grew far beyond what was expected and designed for as a result of com- munity growth, intensive land development, and annexations. Overflows that initially occurred rarely and lasted for only brief periods increased in frequency and duration. Many examples of stream pollution by overflow from combined sewers may be cited; a well-documented case is the shore- line and coastal waters of Boston Harbor, into which more than 100 overflows discharge. Long an insignificant source of water pollution, sewer overflows have now become one of our most important and in- tractable pollution problems, one that will continue to trouble us as far ahead as we can see. Unless this shortcoming of our municipal wastewater infrastructure is corrected, the benefits we expect to result from capital investment in wastewater treatment plants will not be fully realized. Even if treatment plant effluents were given the quality of distilled water, the receiving water bodies would still be polluted at times by the discharges from combined sewer overflows. It may appear surprising that water pollution control agencies have been so slow to recognize the problem. In retrospect it seems so clear: popu- lations, per capita water use, and contributory areas were all increasing, but the combined sewers remained the same in size and carrying capacity. It would seem, again in retrospect, that anyone with common sense should have seen the problem developing. Many environmental engineers did, of course, and where conditions approached the unendurable, sewer im- provement programs were undertaken despite their high cost and the ex- treme disruption they produced. What appears to be a failure in problem perception is more likely the result of the priority given to construction of treatment plants and to preoccupation with this latter task. Engineers believed at first that the solution to the problem of overflow from combined sewers would be found in a sewer separation program: The existing combined sewer would receive wastewater from only house- holds and commercial and industrial establishments for conveyance to the treatment plants; the storm sewer would collect runoff for discharge to the nearest watercourse. The idea of separate systems was a sound one, but the enormous cost of such a program, apart from the disruption as- sociated with it, was a major deterrent to aggressive planning. Whatever support remained for sewer separation, except in special cases, weakened further with findings that street wash (runoff) could be highly pollutional: the first flush from the storm sewer could be stronger than raw sewage, and the pollutional character could persist throughout the discharge. Some engineers suggested that the problem could be controlled by constructing storage tanks at each overflow. The tanks would permit the return of overflow to the sewer when dry-weather flow resumed. Alter- natively, the tank contents could be chlorinated and discharged to the

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282 BERNARD B. BERGER watercourse. This approach was generally rejected except in special sit- uations because of the difficulties and costs of land acquisition at overflow locations, problems in controlling settleable solids, and the enormous cost of operating and maintaining storage chambers, pumping equipment, and chlorinators at what might well be a hundred or more locations in the city. A unique solution to the combined sewer overflow and storm runoff is seen in Chicago's Tunnel and Reservoir Plan (TARP), which was proposed initially in 1962 (Dalton and Rirnkus, 19851. Here, 131 miles (ml) of tunnel (47 mi completed by the end of 1985) 9 to 33 feet (ft) in diameter and 150 to 350 ft below street level will intercept all excess sewage and runoff for conveyance to underground reservoirs sized to contain the largest rainfall in Chicago's history. When dry weather returns, the diluted sewage will be pumped back and treated before discharge into the canal system. A plan similar to Chicago's multibillion-dollar project was proposed in 1963 for the city of Boston but was never accepted (Horsefield, 19681. Urban Hygiene The Chicago plan, heroic in concept and size, would probably be ap- plicable at only a few locations. More generally, a solution for the problem of overflow from combined sewers must entail either capture and man- agement of the overflow or separation of sewers. The difficulties that occur with the latter have already been described. Still, urban storm-water collection systems are used extensively, and therefore ways of minimizing the pollutional impact of such discharges must be considered. The obvious solution is to keep our urban land surfaces, paved and unpaved, as clean as possible. This means more than frequent street cleanings; it signifies the recognition of a new and heightened perception of urban cleanliness or urban hygiene, which should include special collection and disposal of potentially hazardous chemicals used in the home, cleanup of unmapped and perhaps forgotten dumps and sites once used for disposal of concen- trated industrial liquid wastes, and rigorous control of animal wastes. More fundamentally, it means the initiation of an education program in which urban hygiene is equated with personal hygiene. Although one cannot expect that the pollutional character of urban nonpoint runoff could be reduced to zero or even near zero, an effective urban hygiene program may provide a basis for rendering such pollution innocuous. Land Use Management The ultimate utility of a deep tunnel and reservoir plan or any other plan will of course depend on the long-term accuracy of the assumptions

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URBAN ~'ASTEWATER INFRASTRUCTURE 283 used in the planning process. To minimize the chances of recurrence of the existing overflow problem, a prudent policy for protecting the sewerage system is required. At the least, such a policy should include adequate control of land use and development and careful assessment of programs of regionalization and land annexations for which sewerage service rights may be granted. The converse of the issue of granting sewerage service rights is that, although the wastewater infrastructure is an important determinant of the distribution of population and allied service industry, it is by no means exclusive. Population and industry move to outlying or extraurban areas as a result of many forces, including improved and expanded systems of public and private transportation and new housing developments, which offer attractive opportunities and facilities for education, recreation, and employment. The predicted widespread introduction of household tele- matic systems may, by weakening the need for central work sites, result in further redistribution of population to outlying areas. The sewerage system, which represents a very substantial public investment, is of course fixed in place. A policy or urban development strategy that results in redistribution of population and industry could reduce the use of portions of the existing sewerage system and the revenue derived from it. This reduction in turn could adversely affect system operation and maintenance. The strategy of urban land use planning should be to foresee such con- sequences and, to the degree possible, try to preserve the values inherent . . in the existing infrastructure. Although the focus here is on the collection of urban wastewaters, the impact of nonurban, nonpoint sources of pollution, such as from rural and agricultural lands, cannot be ignored. Such sources, particularly the runoff from agricultural land, may place a heavy burden on the receiving water body and at times reduce markedly the benefits of urban wastewater management. The significance of agricultural land runoff is evident: such runoff contains high concentrations of oxygen-demanding substances, sus- pended solids, bacteria, pesticides, and nutrient chemicals. The remedy lies in use of agricultural practices and land management techniques de- signed to minimize and control the stow runoff. Unfortunately, concern over this problem occupies a low position in the current hierarchy of agricultural priorities. In the long term, this need will have to be addressed. WASTEWATER TREATMENT AND THE RECEIVING WATER BODY The wastewater treatment plant and the receiving body of water are linked components of the municipal wastewater system. In principle, the nature and design of the treatment processes depend directly on the water

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284 BERNARD B. BERGER quality standards set for the water body. In practice, the mandatory re- quirement for universal secondary treatment that is, treatment that pro- vides separation of settleable and floatable solids and stabilization by microbial communities of oxygen-demanding substances-usually suf- fices. This treatment amounts to an acceleration of the processes of self- purification occurring naturally in the stream. Biological Wastewater Treatment Universal compliance by municipalities with the requirement for secondary (i.e., biological) wastewater treatment meeting conventional performance criteria would remove a major pollutional burden from the nation's waters. The U.S. Environmental Protection Agency (EPA) reports, however, that although industry (i.e., those businesses that are not served by public sewers) is doing an acceptable job in cleaning up its discharges, municipalities are lagging. In fact, EPA reports that about 30 percent of publicly owned wastewater treatment plants fail to meet the effluent criteria. Several reasons for such dereliction have been cited, but the reason most frequently noted is an insufficient number of adequately trained plant operators. This condition stems in the main from the nature of the federal program of grants to municipalities for the construction of wastewater treatment plants. Provision for such an incentive was contained in the original 1948 enactment of the Federal Water Pollution Control Act, but the Federal Water Pollution Control Grant Program was not adequately funded until passage of the 1966 amendments. The size of these federal grants was increased in subsequent legislation and in 1972 amounted to 75 percent of a plant's contraction cost. Many states supplemented the federal grant with a 15 percent state grant. The combined grant covered construction only, however; it did not extend to plant operation and maintenance. Given the conservative inclination of consulting engineers in the wastewater field and their understandable concern with reputation and with liability, few viewed with enthusiasm EPA's efforts to move them toward seeking in- novative, alternative methods of wastewater treatment. The conventional processes were generally installed. These processes require trained tech- nicians for plant operation and maintenance because of the nature of the mechanical and electrical equipment being used and the need for routine sensitive microbiological and chemical testing for process control. Too often, municipalities consider the costs of such requirements excessive. The result is a low-quality effluent, a degraded water body, and a capital investment that has been improperly employed. What is needed here and can be provided by imposing adequate sewer service charges is a sufficient and assured funding base for operation and

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URBAN WASTEWATER INFRASTRUCTURE 285 maintenance as well as for additions and replacements to physical plants. What is now general policy for many public water supply systems should be adopted by the wastewater agencies. Many communities have already adopted a service charge policy; whether the charge is adequate depends on the availability and adoption of a rigorous method of auditing system man- agement. Federal funds amounting to nearly $50 billion have been granted to mu- nicipalities since 1972 for the construction of wastewater treatment plants. Still, the job is far from completed. EPA has estimated that another $39 billion will be needed by the year 2000 for plant construction (Journal of the Water Pollution Control Federation, 19851. Congress did not intend that the federal construction grant program be permanent; the 1972 legislation spec- ified its termination in 1982. It is no great surprise, however, that this did not occur because the pressure by states and municipalities to continue the program was too great. Funds are now appropriated year to year, and many observers believe the program will be terminated in the near future. This in fact seems to be the current will of Congress. The 1987 Clean Water Act amendment, which Congress passed over the President's veto, authorizes a fiscal year 1987 expenditure of $1.2 billion for direct construction grants to municipalities but calls for an end to this program by 1990. Physical and Chemical Methods of Wastewater Treatment Until about 1960 the bulk of research and development on wastewater treatment was directed toward improving biological treatment processes. In that year the U.S. Public Health Service, which was then the agency responsible for conducting the federal water pollution control program, undertook an examination of a broad span of physical and chemical prin- ciples that seemed to offer promise in solids separation. A review (Koenig, 1983) of such processes, excluding those already widely used in waste- water treatment, includes the following: Centrifugation Magnetism Surface tension Foam fractionation Froth flotation Solvent extraction Stripping Distillation Osmosis Chemical oxidation Adsorption Electrokinetics Electrophoresis Electro-osmosis Electrodialysis ~ . breezing Hydration Microfiltration and ultrafiltration Ion exchange Reverse osmosis

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286 BERNARD B. BERGER Thus, we have experienced a dual trend in research and development, encompassing on one hand a most efficient employment of the processes occurring in nature and on the other the application of an advanced and presumably more costly technology. This duality, however, should not be viewed as necessarily reflecting competition. The fact is that advanced techniques for separating solids are commonly considered processes that supplement rather than replace secondary treatment, enabling the effluent to meet rigorous standards of water quality. Concern with wastewater treatment is worldwide; yet the industrialized countries exhibit few major differences in approach to the technology of wastewater treatment. Goals may vary, and those of the United States are among the most stringent, but the basic methods for meeting these goals . . . are similar. Therefore, we can foresee that the wastewater treatment infrastructure for urban areas will continue to consist of primary and secondary treatment, modified as experience justifies, in addition to tertiary treatment as re- quired to meet water quality standards for the receiving water body. De- cisions on the design and operation of such systems, including selection and use of major system components, will continue to be based on what has become the customary analysis of life-cycle costs within a context of restricted system funding. The shortcomings in our existing wastewater treatment infrastructure therefore are not the result of an absence of effective technology for pollutant separation or destruction; a broad range of candidate solids- separation processes is available. We can if necessary treat sewage to a degree that meets the most stringent requirement of drinking water. The health effects and public acceptability of such direct reuse as well as the costs of treatment are now being studied by the city of Denver. In that project the biologically treated sewage effluent is being further treated by a complex train of processes for microbial destruction and for separation of solids (Lauer, 19851. The goals are to lower process costs, improve plant operation and maintenance, and develop acceptable ways of dis- posing of sludge. There are additional and equally difficult challenges: the establishment of reasonable water quality standards and the control of wastewater discharges from industry into the public sewerage system. Water Quality Standards The Federal Water Pollution Control Act Amendments of 1972 (33 U.S.C. 1251 et seq.) define pollution as "the man-made or man-induced alteration of the chemical, physical, biological, and radiological integrity

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URBAN WASTEWATER INFRASTRUCTURE 287 of the water"; they also set a national goal of "elimination of discharges of pollution into navigable waters." Accomplishing this feat will require at least that we know what pollutants reach the sewerage system and what concentrations of such substances may be tolerated with repeated exposure by humans, aquatic life, and wildlife. We have made, and continue to make, substantial advances in techniques for detecting, identifying, arid measuring synthetic organic compounds in extremely low concentrations. As we do so, however, we complicate the problems of assessing risks and determining maximum tolerable concentrations, which are the basis of water quality standards. We make the task even more complex by misrepresenting the real world in which exposures rarely involve single compounds in pure solution but instead entail multiple compounds in mixture. Numerous workers have emphasized the uncertainties associated with extrapolating the results of animal tests, the paucity of useful epidemio- logic knowledge because of the rarity of illness caused by organic com- pounds of industrial origin in water solution, arid the weakness of assumptions of toxicity based solely on chemical structure. For any given pollutant (or mixture of pollutants) the questions remain: How does the level of risk in a given water sample vary with concentration and exposure time? What risk may be tolerated by humans? How is such knowledge to be translated into water quality standards and limits or treatment plant effluent? Such knowledge is essential to municipal acceptance and control of industrial wastewater discharges and to the design and management of the wastewater treatment plant. William D. Ruckelshaus, former EPA administrator, has commented on this issue: "Risk assessment" is the device that government agencies such as EPA have adopted to deal with this quandary. It is the attempt to quantify the degree of hazard that might result from human activities-for example, the risks to human health and the environment from industrial chemicals. Essentially, it is a kind of pretense; to avoid the paralysis of protective action that would result from waiting for "definitive" data, we assume that we have greater knowledge than scientists actually possess and make decisions based on those assumptions.... Despite this uneasiness, there appears to be no substitute for risk assessment, in that some sort of risk finding is what tells us that there is any basis for regulatory action in the first place. The alternative to not performing risk assessment is to adopt a policy of either reducing all potentially toxic emissions to the greatest degree technology allows . . . or banning all substances for which there is any evidence of harmful effect, a policy that no technological society could long survive. Beyond that, risk assessment is an irreplaceable tool for setting priorities among the tens of thousands of substances that could be subjects of control

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288 BERNARD B. BERGER actions-substances that vary enormously in their apparent potential for causing disease. In my view, therefore, we must use and improve risk assessment with full recognition of its current shortcomings. (1985, pp. 26 and 27) In his examination of this issue, Alvin M. Weinberg (1985) emphasizes the practical impossibility of developing clear-cut methods for predicting the health consequences of chemical pollutants present in trace concen- trations. He suggests several ways to provide some assurance of safety despite the uncertainty: by "technological fix," that is, by the inherent character of the design, and by application of the principle of de minimis (Weinberg, 19851. The first method presumably would require specific pollutant sensors in the plant effluent that could feed data back to process controls. The second would be applicable to situations in which there is natural exposure to chemicals of concern and in which man-induced ex- posure is low by comparison. The technological fix presents a challenging assignment to research workers. The de minimis approach presumably could be used only in cases in which the natural background exists; given the synthetic nature of most pollutants of industrial origin, few opportun- ities would be likely. In an earlier day the procedure was simpler, and uncertainties were few and seldom troublesome. Some of our older coworkers will undoubtedly remember the time when "dilution is the solution to pollution" was ac- cepted as doctrine. At that time, one proceeded confidently on the basis that 2.5-4 ft3/second of streamflow could assimilate safely and without nuisance the raw sewage produced by a population of 1,000 people. This primitive procedure was set aside in 1925 with the development of the Streeter-Phelps dissolved oxygen level. This equation, refined and elab- orated, is still used when dissolved oxygen is a critical water quality criterion. Such occasions are less frequent now that all municipal wastewater treatment plants (except for a few waivers for coastal cities) must provide secondary treatment of wastewater. The stream's capacity to assimilate dissolved oxygen-demanding substances is, for all practical purposes, not now available to wastewater dischargers. Pretreatment of Industrial Wastewaters The occurrence of significant concentrations of heavy metals and non- biodegradable, possibly toxic, organic substances in wastewaters reaching the treatment plant presents problems few biological treatment plants are designed to handle. Unless such potentially harmful substances are sep- arated and removed in the sludge, whose utility and value are reduced thereby, they appear in the plant effluent and in the receiving water body. Most of these pollutants are discharged into the sewer by industrial plants

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URBAN WASTEWATER INFRASTRUCTURE 289 despite the requirements of the Federal Water Pollution Control Act that such dischargers pretreat their wastewaters. This program has generally proved difficult and ineffective. Although control of such pollution is absolutely essential to the success of the national program for water pol- lution control, pollution from these sources continues to be a burden to treatment plants and a potential hazard in water bodies. Perhaps it is unrealistic to expect small industrial plants connected to the urban sewer to provide effective control of their wastewaters as re- quired by the Federal Water Pollution Control Act. Such control would include familiar and difficult tasks, including defining the character of the wastewaters, treating these wastewaters sufficiently and reliably, and mon- itoring dependably the treated effluent before discharging it into the public sewer. Few industrial plants have had to cope with such responsibilities, and few have the experience, staff, and laboratory resources required for this task. It is hardly surprising therefore that compliance by the industry with pretreatment requirements has been poor, despite the availability of private consulting firms to provide the services desired. A bold remedy might be considered: the initiation of a municipal in- dustrial wastewater acceptance program through which the municipality would assume responsibility for industrial wastewater characterization, treatment, and monitoring. This responsibility should not be solely the municipality's, however; industrial plant management must have the op- portunity for adopting in-plant controls that could reduce the pollutional load. The cost of the municipal program must of course be borne by the industry served. The concept of the acceptance plan is not new. Two decades ago the state of Maryland instituted a program providing state acceptance of mu- nicipal and industrial wastewater discharges (Butrico and Coulter, 19721. Even now, many cities provide services approaching those that would be covered by the municipal industrial wastewater acceptance plan. Sludge Management Disposal of sludge satisfactorily and permanently remains a persistent and often frustrating challenge. The use of sludge as fertilizer, an accepted practice in an earlier day, is commonly in disfavor today because of fear that it may contain toxic substances. Sludge can be disposed of in a number of ways: It can be discharged into coastal waters (usually with gross consequences as in Boston'; it may be placed in landfills as a component of the municipality's solid wastes; or it may be incinerated, in which case resulting air pollution must be controlled With few exceptions, current modes of sludge disposal by large cities are temporary, expensive, and

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290 BERNARD B. BERGER productive of complaint and stress. The development of innovative meth- ods for permanent and acceptable sludge disposal for medium-sized and large cities remains a high-priority need in the wastewater infrastructure of tomorrow. COMPREHENSIVE PLANNING The importance of planning in the nationwide program of water pollution control was recognized in the initial federal legislation, which stated the "Surgeon General (of the U.S. Public Health Service) shall . . . prepare or adopt comprehensive programs for eliminating or reducing the pollution of interstate waters and the tributaries thereof, and improving the sanitary condition of surface and underground waters" (U.S. Congress, 19481. In the main, the federal government's procedure was to help the states de- velop or update their river basin plans and to work for national uniformity in setting water quality standards and treatment plant performance criteria. This initial approach contributed to an acceptance of the concept of uni- formity and to the process of cooperation among the states. In other respects the federal program of comprehensive planning proved to be of only limited value. The plans that evolved could not accommodate un- foreseen growth and shifts in population or the relocation of industrial plants. The program did not foresee the federally imposed universal re- quirement for biological treatment of wastewater from municipalities or for "best-available" treatment for industries. It gave little thought to pollution from combined sewer overflows and to nonpoint sources of pollution. In the eyes of many experienced wastewater engineers, an important shortcoming of the program was its primary emphasis on a basinwide approach and its failure to focus adequately on the need to clean up the largest wastewater discharges, namely, those from the cities located at the mouths of interstate river systems. Ironically, cleanup of these latter discharges would have little effect on the pollution in the river system itself. The far-reaching 1972 amendments to the National Water Pollution Control Act shifted the planning focus to those areas where industrial and urban wastewater problems were highly complex and difficult that is, to the large urban areas. The areawide planning programs, the so-called Section 208 programs, were instituted throughout the nation; through them, planners tried to come to grips with problems of regionalization as reflected in the integration of planning by central cities, satellite com- munities, and industries, and they searched for ways to control the non- point sources of pollution. These programs were generally conducted by

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URBAN WASTEWATER INFRASTRUCTURE 291 regional planning agencies that were strongly imbued with the ideal of environmental quality restoration and preservation. The programs aspired to the development of coherent plans for integrating regional point and nonpoint wastewater collection, treatment, and disposal systems and for realizing effective programs of urban hygiene. These goals could seldom be reached, however, because the impediments were too great. Solutions to existing problems remained elusive. And institutional barriers could not be effectively removed: agencies responsible for design, construction, and operation of wastewater collection and treatment systems differed in training, experience, and outlook from those engaged in Section 208 planning. Even so, in many areas these programs gave impetus to com- prehensive wastewater management planning; unfortunately, with the ter- mination of these programs, such positive improvements seemed to weaken. CONCLUSION This chapter focuses on physical structures, policies, and practices that represent weaknesses in many urban wastewater management systems. Wastewater discharges that are still poorly controlled include overflows from combined sewers, storm-water runoff, and contributions from other nonpoint sources. To these must be added, in many areas, treatment plant effluents, which too often fail to meet minimum performance conditions and moreover may contain toxic substances that conventional treatment processes are not intended to remove. The sources of pollution and the problems they present may be readily visualized; their solutions, although apparent in many cases, are often difficult to achieve. Chicago's Tunnel and Reservoir Plan, although enormously costly, may be a prototypical solution for large urban areas that experience frequent and protracted overflows from combined sewers and excessive pollution from storm runoff. Other remedial measures can also be described, but at this time they do not justify a high level of enthusiasm. The task of setting maximum allowable concentrations of toxic sub- stances by balancing the costs and benefits of reducing or eliminating them, if in fact such balance is sought, will continue to challenge us as long as basic essential information is lacking. In the absence of reasonable and protective maximum allowable concentrations, questions about equity, as in requirements imposed on industrial waste dischargers, will persist, as will questions about the adequacy of the wastewater management pro- gram. Four additional aspects of the urban wastewater management infra- structure require improvement: (1) pretreating industrial wastewater dis- charges, (2) upgrading the operation and maintenance of treatment plants,

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292 BERNARD B. BERGER (3) strengthening metropolitan areawide systems of wastewater manage- ment, and (4) disposing of sludge. The fourth problem is ubiquitous, persistent, and, in view of the large quantities produced, almost always an awkward, temporary, and costly operation. The efficiency of urban wastewater infrastructures depends on our abil- ity to solve the problems of system structure, standard setting, funding, management, and planning. The utility of long-range planning is of course influenced by the extent to which we can rely on predictions of population and industrial growth and shifts, and on management of service area extensions and annexation. This statement propounds nothing new, but it is worth repeating because the urban system is not static and the urban picture changes from generation to generation. Population grows, moves into and out of, and shifts within the area. New industries move in, often at the periphery of urban areas, and many exert an unanticipated demand for sewerage service. Isolated communities in the metropolitan area expand or fuse their wastewater treatment systems and in the process create needs for regional systems. Regulations on water uses and standards are not necessarily fixed in perpetuity and may be altered to reflect new knowledge and reasonable compromises with regard to equity, resource use, and protection of en- vironmental quality. Still, change is slow and, to a degree, manageable; plans can be modified in timely, realistic ways. There are few major surprises, and those there are usually arise from a failure to perceive what is there to be perceived. Adherence to a soundly conceived and frequently updated plan would ensure the usefulness of the wastewater infrastructure for the indefinite future. REFERENCES Butrico, F. A., and J. B. Coulter. 1972. Statewide management what does the future hold? Journal of the Sanitary Engineering Division, Proceedings of the American Society of Civil Engineers. 98(February):247-256. Dalton, F. E., and R. R. Rimkus. 1985. The Chicago area's Tunnel and Reservoir Plan. Journal of the Water Pollution Control Federation 57(December):1114-1121. Horsefield, D. R. 1968. Deep Tunnel Plan for the Boston area. Journal of the Boston Society of Civil Engineers (October):231-251. Journal of the Water Pollution Control Federation. 1985. 1984 needs survey U.S. En- vironmental Protection Agency. The Journal 57(May):355. Koenig, L. 1983. Fundamental considerations in the removal of organic substances from water a general overview. Pp. 1-25 in Removal of Organic Substances in Water and Wastewater, B. B. Berger, ed. EPA-600/8-83-011. Washington, D.C.: U.S. Environ- mental Protection Agency. Lauer, W. C. 1985. The current status of Denver's potable water reuse project. Journal of the American Waterworks Association 77(July):52-59.

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URBAN WASTEWATER INFRASTRUCTURE 293 Ruckelshaus, W. D. 1985. Risk, science, and democracy. Issues in Science and Technology 2 (Spring):l9-38. Trevelyan, G. M. 1942. English Social History. New York: David McKoy Co., Inc. U.S. Congress. 1948. Federal Water Pollution Control Act. Section 3, Comprehensive Program for Water Pollution Control. P.L. 80-845. Weinberg, A. M. 1985. Science and its limits: The regulator's dilemma. Issues in Science and Technology 2(Fall):59-72. (Also pp. 9-23 in Hazards: Technology and Fairness. Washington, D.C.: National Academy Press, 1986.)