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Managing Wastewater in Coastal Urban Areas 2 Key Issues Relating to Wastewater and Stormwater Management In addressing the challenges for the future management of wastewater and stormwater in coastal urban areas identified in Chapter 1, the following eight key issues emerge: regional differences, nutrients in coastal waters, pollution prevention and water conservation, levels of treatment, stormwater and combined sewer overflows, detection of human pathogens, development of management alternatives, and evaluation and feedback. Progress is required in each of these areas if the nation is to continue to advance its clean water goals in coastal areas. REGIONAL DIFFERENCES The hydrodynamic and ecological characteristics of coastal zones vary considerably around the country. A description of such variations in the coastal zone is contained in Chapter 1 in Box 1.1. In general, the amount of exchange between coastal waters and the deep ocean is greater in those zones where the continental shelf is narrower. Exchange with deep ocean waters disperses constituents in wastewater and runoff and prevents their concentration in coastal waters. Even along a particular coastline, one can find dramatically different environments and ecosystems. Estuaries, where fresh water rivers meet marine waters, have unique circulation patterns depending on tides, runoff, and the physical geometry of the system. Estuaries, bays, and sounds can be large or small, shallow or deep. Generally, estuaries, sounds, bays, and other semi-enclosed water bodies have less exchange of marine waters than
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Managing Wastewater in Coastal Urban Areas open coastal areas. Internal recirculation in these systems can lead to the entrapment of pollutants in the sediments and increased concentrations in the water column. Tidal fluxes can also have important influences. Depending on the circulation patterns and other physical factors, as well as the different ecosystems present, different coastal systems respond differently to wastewater and stormwater inputs. Thus, it is important that wastewater and stormwater management practices be tailored to the characteristics of the particular receiving environment. Because of the wide variations encountered in coastal systems, it is not possible to prescribe a particular technology or approach at the national level that will address all water quality problems relating to wastewater and stormwater management satisfactorily. Any such approach would necessarily fail to protect some coastal regions and place excessive or ineffective requirements on others. NUTRIENTS IN COASTAL WATERS Perhaps the most pressing problem in many estuarine and marine systems today is that of nutrient enrichment. While not known to be a problem along most of the open Pacific coast, excess nutrient enrichment, or eutrophication, is a persistent problem in many estuaries, bays, and semi-enclosed water bodies and may be of concern over a large scale in some more open areas along the Atlantic and Gulf coasts. (A complete discussion of coastal nutrient enrichment issues is included in Appendix A; the following is a summary of the key points.) Nutrients are essential for primary production, the plant growth that forms the base of the food web in all coastal systems. Nitrogen, phosphorus, and a host of other nutrients sustain the production of phytoplankton. In general, in productive freshwaters of the temperate zone, phosphorus is the most important of these elements. It controls the overall rate at which primary production takes place. In nontropical coastal marine waters, however, nitrogen is the most important factor in limiting primary production. At the interface between marine and freshwater, both of these elements are important. In moderation nutrients can be beneficial, promoting increased production of phytoplankton and, in turn, fish and shellfish. In excess amounts, however, nutrients cause overproduction of phytoplankton, which results in oxygen depletion, which then can reduce the numbers of fish, shellfish, and other living organisms in a water body. Other problems caused by excess nutrient enrichment include nuisance algal blooms, which are aesthetically displeasing and can sometimes carry toxins harmful to fish populations or to humans through consumption of seafood. Nutrient enrichment may also shift the plankton-based food web from one based on diatoms toward one based on flagellates or other phytoplankton that are less desirable as food to
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Managing Wastewater in Coastal Urban Areas organisms at higher trophic levels. The dieback of seagrasses and corals and reduced populations of fish and shellfish have been linked to excess levels of nutrients in coastal waters as well. Unlike solids and many toxic organic compounds, nutrients are highly soluble in water and therefore highly mobile in coastal systems. Compared with concerns associated with nutrients, problems associated with solids and toxics generally occur more locally. Nutrients can be transported much further, and often there is a time lag between the introduction of nutrients into a water body and the adverse effects associated with eutrophication. Thus, problems related to nutrients can occur on a large scale and may be more difficult to discern. Nutrients enter coastal waters from every potential point and nonpoint source including: wastewater treatment plants, agricultural runoff, urban runoff, groundwater discharge, and atmospheric deposition. The relative contribution of nutrients from each of these sources varies from area to area depending on local and regional hydrology, land-use patterns, levels of wastewater treatment, and other management practices. Concerns about nutrient enrichment should be addressed in the development of wastewater and stormwater management strategies. SOURCE CONTROL AND WATER CONSERVATION No one technology or management control will resolve all wastewater or stormwater management problems. An effective management system must include a suite of technologies and controls tailored to the specific needs of the region. In addition, over the past decade, it has become clear that the best approach to pollution control is pollution prevention wherever possible. It is particularly important that the options not be limited to end-of-pipe treatment strategies. In the case of wastewater management, municipal systems have found that industrial source control and pretreatment programs can result in significant reductions of metals, toxic organics, and oil and grease (AMSA 1990). Reduction or elimination of these constituents from municipal wastewater treatment plant influent results in better quality sludge, which can then be used for beneficial purposes. It also reduces the discharge of these materials in the effluent to the environment where they may cause harm. Phosphate detergent bans, for example, have resulted in significant reductions of phosphorus from wastewater effluent. It should be noted that an effectively implemented preventive maintenance program in the industrial pretreatment and/or municipal wastewater treatment plants can limit unexpected shutdowns of critical equipment or systems, which could cause bypass of partially treated or untreated waste to receiving waters. In the case of urban runoff, street sweeping, warnings stenciled on
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Managing Wastewater in Coastal Urban Areas storm drains, and public education efforts are believed to have resulted in improvements in some cities. In new developments, modern stormwater system designs can significantly slow runoff, increasing infiltration into the ground and improving the quality of runoff waters. Retrofitting of parking lots and other drainage areas with treatment and/or control devices can also decrease the amount of pollutants transported from these surfaces to local waters. Water conservation can achieve benefits in coastal management in several ways. Water conservation reduces the volume of dry weather flows that require treatment, although it does not reduce the mass of pollutants entering the system. Water conservation can, in some cases, delay the need for constructing new treatment capacity for those portions of the plant that are designed on the basis of flow. More significantly, however, water conservation reduces the need for development of new water supplies. Such development can seriously affect the areas where it occurs as well as divert ecologically important freshwater flows from estuaries and other coastal waters. LEVELS OF TREATMENT The environmental and human health concerns associated with different wastewater constituents vary from region to region as well as within a region. It is therefore important that the treatment required for wastewater be appropriate for the particular environment to which the wastewater is released. Wastewater treatment and other management controls should be guided by the ecological and human health requirements of the receiving environment, which, in many cases, may be expressed as water and sediment quality criteria, ecosystem indices, or by some other environmentally-based criteria. In general, suspended solids are of concern because of the metals, toxic organics, and pathogens associated with them. Also, in bays, estuaries, and other shallow nearshore waters sedimentation and shading effects can be a problem. In deep open water, below the depth of light penetration, shading is not a concern; also, outfall diffusers facilitate rapid mixing thereby limiting sedimentation effects to the area in the immediate vicinity of the outfall. Biochemical oxygen demand (BOD) is of concern in bays, estuaries, and semi-enclosed water bodies but is generally not important in the open ocean. Coastal water quality concerns associated with nutrients are discussed above. There is a wide variety of physical, chemical, and biological treatment processes available for removing each of these types of contaminants. Treatment techniques range from simple screening and settling operations to sophisticated biological, chemical, and mechanical operations that produce water clean enough to reuse. Table 2.1 provides some abbreviated performance
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Managing Wastewater in Coastal Urban Areas TABLE 2.1 Typical Percent Removal Capabilities for a Range of Wastewater Treatment Processes1 Conventional Primary2 Chemically Enhanced Primary2 (CEPT) Conventional Biological Secondary Preceded by Conventional Primary2 Biological Secondary Preceded by CEPT2 Nutrient Removal Preceded by Conventional Biological Secondary and Conventional Primary3 Reverse Osmosis3 Low dose High dose Suspended 41-69 60-82 86-98 89-97 88-98 94 99 Solids as mg/l TSS BOD 19-41 45-65 67-89 86-98 91-99 94 99 as mg/l BOD5 Nutrients as mg/l TN 2-28 26-48 NA 0-63 NA 80-88 97 as mg/l TP 19-57 44-82 90-96 10-66 83-91 95-99 99 NA = Not available 1 See Appendix D for more details on the treatment systems and capabilities presented here. 2 Ranges represent one standard deviation on either side of the mean as determined from two national surveys. 3 Based on a synthesis of technical literature and engineering models provided by Glen T. Daigger, CH2M Hill, Denver, Colorado.
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Managing Wastewater in Coastal Urban Areas information for a series of treatment trains listed in order of increasing sophistication. The materials removed from wastewater end up as sludge and other residuals, which may require additional treatment prior to reuse or disposal. The cost of treatment and volume of sludge produced tend to increase with increasing removal capabilities, as do land area and energy requirements. Generally, the practice is to remove solids, plastics, and floatables, then BOD, and then nutrients. Most of the metals and toxic organics are removed incidentally in these systems, with the metals and some of the toxics ending up in the sludge product and other toxic organics being degraded and/or volatilized to the atmosphere. The first stage of any treatment plant consists of screening and grit removal to eliminate sand and gravel and other large or heavy items. The next stage is often referred to as primary treatment. Primary treatment simply uses gravity to separate settleable and floatable materials from the wastewater. Other constituents associated with settleable solids are also removed to some degree in the process. The removal capability of a primary treatment system can be improved with the addition of certain chemicals that enhance the tendency of solids to settle. This technique herein is referred to as chemically enhanced primary treatment. The next level of sophistication in treatment, known as secondary treatment, makes use of both biological and physical processes. Typically, wastewater is first subjected to primary treatment. Activated sludge treatment, the most commonly used biological process, begins by adding oxygen to the system either by vigorous mixing or bubbling. Microorganisms in the mixture feed on organic matter, using the oxygen to convert it to more microorganisms, carbon dioxide, and water. In the second stage, solids, including living and dead microorganisms, are settled out. The solid material produced from both the secondary and primary processes is referred to as sludge or biosolids. Conventional biological secondary treatment is designed specifically to remove BOD and total suspended solids (TSS), but certain amounts of other constituents are also removed incidentally in the process. The next level of treatment is often referred to as tertiary or advanced treatment and covers a wide variety of physical, biological, and chemical processes aimed at removing nitrogen and phosphorus. Phosphorus removal processes involve either the addition of chemicals to precipitate phosphorus or carefully controlled biological reactions to grow microorganisms having a high phosphorus content and then settle them out of the water. Nitrogen removal involves the carefully controlled biological reactions to convert organic nitrogen and ammonium into nitrate (nitrification) and then into gaseous forms of nitrogen (denitrification). In addition to nutrient removal, more sophisticated processes such as carbon adsorption and reverse osmosis may be used to remove remaining constituents of concern. Disinfection using chlorine or other chemicals, or
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Managing Wastewater in Coastal Urban Areas exposure to ultraviolet light can be performed at any stage of the process, although it is most effective when the greatest amount of suspended and colloidal solids, which interfere with disinfection, have been removed. The major concern with chlorination is that it is highly toxic to marine organisms. For discharges to some receiving waters, dechlorination may also be required to protect sensitive species. The solids or sludge removed from these practices must be subjected to another series of treatments. The most commonly used approach for sludge from primary and secondary treatment is anaerobic digestion. This process allows microbes that live in the absence of oxygen to feed on the organic matter, producing more microbes, methane, carbon dioxide, and water. Often, the methane from anaerobic digesters can be captured and used to generate power to operate equipment in treatment plants. Aerobic digestion is used less often because of the high energy costs needed for operation. Composting, a different aerobic process, is used less because of odor problems. Digested sludge contains a large amount of water (typically 95 to 99 percent) and requires dewatering. After dewatering, depending on the content of metals and toxic organics, it may be possible to reuse sludge as a soil amendment with certain crops, on forest land, and for other land-application uses. Otherwise, sludge is generally either landfilled or first incinerated and then the ashes are landfilled. Appendix D contains greater detail on liquid and sludge treatment processes. Identifying an appropriate series of processes for treatment in a specific situation is complicated because there are often cost and technical tradeoffs when optimizing for the control of a particular class of pollutants. Costs for wastewater treatment increase rapidly with increasing removal efficiencies. Figures 2.1a and 2.1b show performance and cost relationships for removal of TSS and five-day biochemical oxygen demand. A further discussion of these relationships and those for other wastewater constituents is contained in Appendix D. Technical tradeoffs can be less straightforward. For example, nitrogen discharged from biological secondary treatment is generally in a soluble inorganic form, while nitrogen discharged from a primary treatment process has a high organic content associated with particles. Thus, while biological secondary treatment serves to remove BOD from the discharge to improve local water quality, it also, in effect, mobilizes nitrogen into regional circulation patterns, which may lead to regional scale eutrophication. In the case of primary effluent, the organic nitrogen in the sediments near the outfall also may solubilize over time, but more slowly. In other cases, nitrogen may be of concern while BOD is not. The most practical existing nitrogen removal processes are variations to biological secondary treatment. However, because of the expense associated with nitrogen removal processes, it may be more cost-effective to seek alternative methods for mitigating other
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Managing Wastewater in Coastal Urban Areas FIGURE 2.1a Total suspended solids performance and cost relationship. NOTE: The 10 different wastewater treatment systems are: (1) primary, (2a) low-dose chemically-enhanced primary, (2b) high-dose chemically-enhanced primary, (3) conventional primary + biological treatment, (4) chemically-enhanced primary + biological treatment, (5) primary or chemically enhanced primary + nutrient removal, (6) system 5 + gravity filtration, (7) system 5 + high lime + filtration, (8) system 5 + granular activated carbon + filtration, (9) system 5 + high lime + filtration + granular activated carbon, (10) system 9 + reverse osmosis. (See Appendix D for further information on the treatment systems and cost and performance ranges presented here.) sources of nitrogen entering the same receiving waters. Another technical tradeoff associated with nitrogen removal is that while better primary treatment enhances biological secondary treatment and nitrification, it can hinder biological phosphorus removal and denitrification. A fourth example of the tradeoffs inherent in optimizing control of different constituents is that of disinfection. Solids interfere with most disinfection methods. Thus, while the primary concern associated with a particular stormwater outfall or wastewater discharge may be pathogens, suspended solids removal may also be required if pathogens are to be controlled adequately. In cases of deep ocean discharge where BOD, pathogens, nitrogen, and other nutrients are of little concern, and contributions of toxics and metals associated with solids are low, treatment for removal of these constituents is
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Managing Wastewater in Coastal Urban Areas FIGURE 2.1b Five-day biochemical oxygen demand (BOD5) performance and cost relationship. See note to Figure 2.1a for key to wastewater treatment systems. unnecessary. At the other end of the spectrum, there may be cases in which wastewater reclamation and reuse are preferable to discharge to coastal waters. For example, as demand for water has increased in some areas or as ecological requirements have led to prohibitions in discharge, wastewater reclamation and reuse have become an important component in water resources planning. Although costly, reclamation and reuse allow water suppliers to supplement short-term needs with reclaimed water while increasing long-term water supply reliability. Reclaimed water is used for landscape irrigation, industrial water supplies, augmentation of ground water supplies, and prevention of salt water intrusion. Depending on the particular needs of a region related to water resources and environmental protection, water reclamation and reuse may play an important role in overall regional strategies for meeting coastal quality objectives. They do not, however, eliminate the need for some ocean discharges. STORMWATER AND COMBINED SEWER OVERFLOWS Urban runoff and combined sewer overflows (CSOs) are major contributors to water quality problems in coastal urban areas. Many older
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Managing Wastewater in Coastal Urban Areas cities, primarily in, but not limited to, the northeastern United States, have combined collection systems that carry both stormwater and municipal sewage. Even during small rainstorms, these systems can overflow at designated points, discharging untreated sewage, industrial wastewater, and urban runoff into adjacent waterways. The way in which urban runoff and CSOs affect receiving waters is much different from continuous, point source loadings. First, rainfall induced loads are not constant, but intermittent, pulsed loads. Pollutant concentrations in these flows vary dramatically during the course of a runoff event, and the total pollution load from any storm is dependent upon the intensity and spatial variability of the rainfall, and the time elapsed since the last rainstorm. In general, the greatest concentration of pollutants is contained in the first flush of stormwater, with concentrations decreasing dramatically for most pollutants as a storm continues. In addition, precipitation in many areas is seasonal so that urban runoff and CSOs may affect coastal waters more during some seasons than others. In central and southern California coastal areas, for example, almost all of the annual rainfall occurs between the first of October and the end of May. Assessments of the impacts of stormwater and CSO flows on aquatic ecosystems and human health must take into account the variable and intermittent nature of these flows. Fecal coliforms, an indicator of the potential presence of human pathogens (see next section), often can be detected in local receiving waters at levels exceeding health standards for two or three days following a storm event. These levels indicate a potential threat to human health during that period. Heavy metals and toxic organics may be present in toxic concentrations near stormwater and CSO outfalls during a storm but decrease in concentration rapidly as stormwater mixes with receiving waters. They may, however, accumulate in the sediments near stormwater and CSO outlets. Nutrients, on the other hand, pose no immediate threat during a wet weather event but may contribute to the overall loading of nutrients to the region, an issue which is discussed above. Reducing pollutant loads from urban runoff and CSOs is significantly more challenging and potentially more costly than removing pollutants from municipal and industrial wastewaters. Wastewater treatment processes are designed to treat relatively constant and continuous flows, and they perform poorly when subjected to the extreme variations characteristic of stormwater flows. Thus, different types of treatment and control methods are needed. However, relatively little effort has gone into the development of stormwater and CSO treatment and control technologies. The federal government sponsored research on treatment of CSOs in the late 1960s and 1970s, but the results of those efforts were disappointing. Funding for CSO research was greatly reduced by 1974 and had disappeared by 1981. Some research on structural controls for improving stormwater runoff was conducted in con-
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Managing Wastewater in Coastal Urban Areas junction with the Area Wide Planning Studies mandated under Section 208 of the Clean Water Act and conducted in the early and mid-1970s; since then only a limited amount has been done. While, intuitively, runoff source control techniques, such as covering chemical storage areas, spill response and containment programs, elimination of illegal dumping, removal of floor drain connections to storm drains, street sweeping, household hazardous waste collection programs, and public education, are expected to result in reduced pollutant loadings to coastal waters, little quantitative research has been conducted to determine their overall effectiveness in practice. Stormwater and CSO impacts are largely a function of regional and local hydrology and existing system capacity. Thus, while the capture of a one-year, one-hour storm in one city may limit CSO events to four times a year, in another city, the overflow frequency will be more or less. Figure 2.2a shows the percent capture of annual runoff achieved by various-sized detention basins. In addition to showing how variations in regional hydrology affect runoff capture capacities, this figure shows that the most cost-effective facility (taken as the knee of the curve) varies for different regions of the country. Figure 2.2b shows the annual overflow frequency obtained with various sized detention basins. Stormwater and CSO abatement requirements should be based to the greatest extent possible on an understanding of regional and local hydrology. They should also be designed in conjunction with other regional environmental protection programs to achieve the most cost-effective combination of structural and nonstructural controls. Currently, pollutant removal efficiencies of treatment facilities for CSOs and urban runoff cannot be stated with sufficient confidence to design a facility plan that will limit pollutant loads to a prescribed level. The difficulty in making such predictions stems from the high variability in hydraulic and pollutant loadings that a facility will experience from storm to storm and within a particular storm. Given the cost of constructing these facilities on a large scale in urban areas ($20 to $60 million per square mile for combined sewer areas and $0.6 to $3.8 million per square mile for stormwater facilities [APWA 1992]), a serious, well-funded research program of runoff characterization and new technology demonstrations is needed. Descriptions of various CSO and stormwater controls are given in Appendix D. In the absence of the ability to predict pollutant discharge concentrations accurately, there have been proposals to legislate national technology-based requirements mandating the capture and treatment of runoff from all storms up to a certain size and frequency. The difficulty with such requirements is the same as that for technology-based wastewater treatment requirements: they are likely in some cases to result in costly overcontrol, in others undercontrol with continued adverse environmental effects, and in relatively few cases will they likely meet the environmental protection requirements of a particular region in a cost-effective way.
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Managing Wastewater in Coastal Urban Areas FIGURE 2.2a Runoff capture efficiency versus unit storage volume. (Source: Roesner et al. 1991. Reprinted, by permission, from American Society of Civil Engineers, 1991.) NOTE: Basin storage volume is in watershed inches, which is equivalent to acre-in/acre of drainage area. Dividing basin storage volume numbers by 12 converts the abscissa to acre-ft of storage required per acre of tributary area. FIGURE 2.2b Basin overflow frequency versus unit storage volume. (Source: Roesner et al. 1991. Reprinted, by permission, from American Society of Civil Engineers, 1991.) See note to Figure 2.2a.
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Managing Wastewater in Coastal Urban Areas It is important that regulatory programs for various wet weather sources be coordinated and that management programs for urban runoff, CSOs, and wet weather overflows in sanitary systems be integrated. Where integration is lacking, coastal quality objectives may not be met by the sum of the activities of the individual programs. If they are, the cost is likely to be much greater than would be for an integrated program. For example, the study of CSOs in Boston showed that even if overflow events were reduced to one per year, Boston Harbor would still have periods of high coliform levels due to stormwater discharge (and likely wet weather overflows from sanitary systems) from communities having separated stormwater and sanitary sewers (CH2M Hill 1992). Milwaukee, on the other hand, having jurisdiction over both the combined sewer area and the separate sewered areas, was able to use a single, integrated facility plan to solve both CSO problems and sanitary sewer overflow problems at considerable savings in comparison to possible independent solutions (MMSD 1980). The current permitting structure at the federal and state levels provides the opportunity to address CSOs and sanitary system overflows simultaneously, provided both systems are owned by the same permittee. Stormwater discharges, however, are regulated under a different permit and, at least at the federal level, by different entities within the Environmental Protection Agency. The permitting process should be improved to provide flexibility that would allow for and encourage the development of integrated regional solutions for all components of wet-weather pollution sources. DETECTING HUMAN PATHOGENS Over 100 different human enteric pathogens, including viruses, parasites, and bacteria, may be found in treated municipal wastewater and urban stormwater runoff. Many of these pathogens can survive for up to several days in water, and even longer in fish and shellfish. The transmission of disease to humans from consumption of contaminated fish and shellfish has been well documented. In addition, several epidemiological investigations have demonstrated recreational contact with contaminated waters through activities such as windsurfing, surfing, swimming, and diving in polluted waters is associated with increased diarrhea, skin, ear, and respiratory infections (Cabelli et al. 1983, Richards 1985, DeLeon and Gerba 1990, Balarajan et al. 1991, Alexander et al. 1992, Fewtrell et al. 1992). More detail on the risks associated with microbial pathogens in coastal waters is contained in Appendix B. While effective disinfection methods can greatly reduce the number of pathogens in wastewater treatment plant effluent, they may not inactivate them completely. The efficiency of disinfection technologies depends on the concentration of the disinfection agent, contact time, and the character-
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Managing Wastewater in Coastal Urban Areas istics of the water being disinfected. In addition, pathogen inputs to coastal waters from uncontrolled nonpoint sources may result in pathogen concentrations more than sufficient to impair human health. Intestinal bacteria have been used for more than 100 years as indicators of fecal contamination in water and of overall microbial water quality. These bacteria normally live in the intestinal tract of humans and other warm-blooded animals without causing disease. If found in significant concentrations in water, they are considered to indicate the potential presence of human and/or animal fecal waste. The most commonly measured indicators are total coliforms and a subset of this group, the fecal coliforms which are considered to be more predictive of fecal contamination. Generally greater than 90 percent of the coliforms found in feces of warm blooded animals are a specific fecal coliform Escherichia coli (E. coli). In addition to the coliform bacteria, fecal streptococci and enterococci have been used to monitor water quality and are also natural flora of the intestines of animals, including humans. In the United States, bacteriological standards for shellfish harvesting waters and recreational waters are set by each state. Standards for shellfish growing waters are generally more consistent nationally and reflect the Food and Drug Administration requirement for interstate transport of harvested shellfish with less than 14 fecal coliforms per 100 milliliters and with no more than 10 percent greater than 43 per 100 milliliters. Recreational water-quality standards vary from state to state. About 50 percent of the states use a standard of less than 200 fecal coliforms per 100 milliliters; some use a total coliform standard in lieu of or in addition to the fecal coliform standard (Kassalow and Cameron 1991). The EPA's ambient water-quality criteria document for bacteria recommends a using an enterococcus standard based on epidemiological evidence of the relationship between enterococci and gastrointestinal illness (EPA 1986). However, only about 30 percent of the states now use enterococcus standards. The EPA recommended criterion is 35 enterococci per 100 milliliters; state standards range from 3 to 52 enterococci per 100 milliliters. Although bacterial indicators have been used extremely successfully in the development of strategies for controlling bacterial diseases such as cholera and typhoid, they have limited applicability in the control of many nonbacterial pathogens and some waterborne bacterial agents in both seafood and recreational waters. In the United States, for example, outbreaks of illnesses continue to occur due to enteric pathogens (e.g., hepatitis A) as a result of consumption of shellfish taken from waters near wastewater discharges but meeting coliform standards. The state of Florida recently issued a statement to the public advising that the state could not guarantee the safety of raw shellfish. No epidemiological study to date has concurrently evaluated the association between disease incidence and the presence of
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Managing Wastewater in Coastal Urban Areas both bacterial indicators and nonbacterial pathogens, such as viruses and protozoa. The use of a single bacterial standard for determining either marine water quality or seafood safety is inadequate for several reasons (Gerba et al. 1979, Cheung et al. 1990, NRC 1991). Indicator bacteria cannot be used to distinguish between human and animal fecal contamination. When used in marine, particularly tropical, waters, current methods may enumerate primarily non-E. coli and nonsewage-related bacteria. In addition, low levels of bacteria may be less of a health concern than low levels of viruses and protozoa because of the higher infectious dose needed to initiate an infection. Current indicator bacteria enumeration methods use relatively small sample volumes (i.e., 100 milliliters). Thus, viruses and protozoa may be present at levels of concern although indicators are absent from the sample. Finally, indicator bacteria have patterns of survival in the environment that differ from those of nonbacterial pathogens. The survival of pathogens in the marine environment is influenced by several factors, including temperature, sediments, nutrients, light, dissolved oxygen, and the type of microorganism. Die-off rates for enteric microorganisms are higher in saline waters than in freshwaters. In general, the survival of coliforms in marine waters is shorter than that of other enteric microorganisms. For this reason, the absence of coliforms does not guarantee the absence of pathogenic microorganisms in marine waters, sediments, shellfish, or fish. Studies have found limited correlation between indicator bacteria and the presence (or absence) of enteric viruses (Gerba et al. 1979). A study of virus levels in shellfish from shellfish beds meeting bacteriological standards on Long Island found virus counts ranging from 10 to 200 virus plaque units per 100 grams shellfish. (Levels that might be associated with risks of acute illness range from 0.001 to 0.1 virus plaque units per 100 grams.) A more detailed discussion of the survival of enteric microorganisms in marine waters can be found in Appendix B. The need for a new surrogate to determine the presence of pathogenic organisms in water is apparent. Efforts to overcome the deficiencies of the current system for virological water-quality protection, have been directed toward the investigation of the coliphage as an indicator of recreational and marine water quality (O'Keefe and Green 1989, Borrego et al. 1990, Palmateer et al. 1991). Coliphage are bacterial viruses that infect E. coli as their host. The coliphage are easily assayed and results are obtained more rapidly than for bacteria assays. They are similar in size and structure to the human enteric viruses and thus mimic their fate in the environment. Methods are being developed to examine large volumes of water for coliphage to eliminate the disadvantage of the 100-milliliter sample size used in bacterial assays.
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Managing Wastewater in Coastal Urban Areas New methods are also being developed for the rapid examination of waters for individual pathogens. Immunological approaches as well as molecular techniques using gene probes and polymerase chain reaction are being investigated and their application to environmental samples is progressing (Richardson et al. 1988, Bej et al. 1990, Abbaszadegan et al. 1991). These methods will be useful in the performance of sanitary surveys and the development of a risk based approach for determining acceptable levels of specific pathogens in shellfish, recreational waters, and effluents from wastewater treatment plants. Methods for directly measuring the presence of bacteria, viruses, parasites and other pathogens associated with sewage have been developed and are available (Bendinelli and Ruschi 1969; Van Donsel and Geldreich 1971; Goyal et al. 1979; Ellender et al. 1980; Vaughn et al. 1980; Schaiberger et al. 1982; Wait et al. 1983; Rose et al. 1985, 1988, 1991; Volterra et al. 1985; Richardson et al. 1988; Perales and Audicana 1989; Bej et al. 1990; Colburn et al. 1990; DePaola et al. 1990; Knight et al. 1990; Abbaszadegan et al. 1991; and Desenclos et al. 1991). Depending on the type of organism and detection method used, costs may range from $50 to $1,000 per sample. Public health agencies, wastewater management agencies, environmental engineers, and others responsible for monitoring wastewater treatment impacts have been slow to use them because they are more expensive and more complex than traditional methods and because coliform monitoring has such a long tradition. As described in detail in Appendix B, however, the risk of disease transmission related to wastewater management practices is potentially large, and needs to be better understood. The Environmental Protection Agency, public health agencies, and wastewater treatment agencies should vigorously pursue the development and implementation of improved techniques to measure more directly the presence of pathogens, particularly in marine and estuarine waters. DEVELOPING MANAGEMENT ALTERNATIVES Wastewater and stormwater management strategies should be developed in the context of each other and of other important sources of perturbation in the coastal zone. Environmental regulation in the coastal zone should be flexible, encouraging the development and implementation of innovative alternative strategies which promise greater overall efficiency and efficacy than existing approaches. In most areas it is a combination of sources and human activities that leads to degradation of coastal waters. Successful management strategies must take into account the full range of sources. In the process of identifying approaches for controlling inputs, it also will be possible to identify and explore the full range of potential alternatives for controlling those sources. A management plan
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Managing Wastewater in Coastal Urban Areas should then consist of a combination of alternatives that can achieve desired results in the most cost-effective manner. For example, there may be cases where it is more effective and/or efficient to control agricultural and other nonpoint source runoff rather than upgrading wastewater treatment systems. In some cases, the cooperative efforts of stormwater agencies, wastewater agencies, water supply agencies, and other agencies concerned with the region's resources can result in the development of efficient and mutually beneficial solutions. In order to assure continued public support for environmental protection and coastal resource management programs, it is important to develop strategies that make effective use of public funds. If the costs of proposed programs are perceived to be too high or unfairly allocated in relation to the benefits gained, public support will erode and may be lost, particularly for future programs. Strategies that take into consideration cost-effectiveness are more likely to be supported by the public and foster support for future protection programs. EVALUATION AND FEEDBACK The effectiveness of management approaches can only be determined, and corrected if necessary, if there is adequate monitoring, evaluation, and feedback. Monitoring of water and sediment quality and other ecosystem parameters is important not just for determining compliance with regulatory requirements but also for developing a better understanding of the coastal system that management efforts aim to use and protect. Monitoring data, research results, and other information about management systems requires careful evaluation to determine if predictions are accurate, whether unanticipated problems have developed, and where improvements may need to be made. Evaluation efforts should take into account the effectiveness of specific efforts as well as that of the whole integrated management effort. They should focus on lessons that can be learned from implementation experiences in order to improve the potential for success of future efforts. For example, the ability to use mathematical models to predict the behavior of sewage effluent in coastal systems has advanced dramatically over the past 20 years. Comparatively little effort has been put toward the verification of these model predictions, however. To make good use of these tools and identify where they need improvement, it is important that follow-up monitoring studies be conducted. Feedback of information from monitoring, research, and evaluation indicates how management strategies should be revised to meet the goals and objectives of the region. It is important that management approaches be sufficiently flexible to be able to make changes and improvements in response to new information. Evaluation of the effectiveness of management
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Managing Wastewater in Coastal Urban Areas efforts should be an integral part of the overall approach and should take place on an ongoing basis. Monitoring studies that are performed often limit evaluations of trends on a year-to-year basis and do not look at long-term (10 to 20 year) trends. Some preliminary evaluations of data for southern California indicate that long-term improvements are occurring despite dramatic increases in wastewater flows due to population growth (SCCWRP 1989, 1990; LADPW 1991; Mearns et al. 1991). Source control programs have been very effective in reducing toxicant loads. Predictive models used for developing source control programs need to be linked to environmental monitoring data so that the loads and indicators can be correlated and success or failure measured quantitatively. SUMMARY The eight issues identified above form a snapshot of current needs in wastewater and stormwater management in coastal urban areas. Coastal systems around the United States are complex and diverse; environmental processes and human activities within these systems are dynamic and interconnected. Addressing these issues in a comprehensive manner will require some innovation and some change. Ideally, coastal resources and the human activities that affect them should be managed on a thoroughly integrated basis in the context of the complex functions and interrelationships that form the coastal environment. Ultimately, this integration should be done across the spectrum of pollutants and other sources of stress, between the various environmental media, and over the time and spatial scales of impacts. Many coastal areas, particularly those in the National Estuary Program (see listing in Table 2.2), have developed or are in the process of developing integrated programs focused on water quality protection. In addition, efforts throughout the country to develop watershed management plans and waste-load allocation programs are structured to take into account the diversity of pollution sources. Because of their relative importance and the degree of experience and extent of related physical and institutional structures already in place, the management of wastewater and stormwater is often a good place to begin the development of an integrated coastal management program. The following chapter discusses the principles and methodology on which such a program should operate. Chapter 4 provides a technical description and examples of how the methodology for such a management system should be applied.
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Managing Wastewater in Coastal Urban Areas TABLE 2.2 Estuaries Participating in the National Estuary Program Convened 1985-1987 Puget Sound, Washington Buzzards Bay, Massachusetts Narrangansett Bay, Rhode Island Long Island Sound, New York and Connecticut Albemarle-Pamlico Sound, North Carolina San Francisco Bay, California Convened 1988 New York-New Jersey Harbor, New York and New Jersey Delaware Inland Bays, Delaware Santa Monica Bay, California Galveston Bay, Texas Delaware Bay, Delaware Convened 1990 Casco Bay, Maine Mass Bays, Massachusetts Indian River Lagoon, Florida Tampa Bay, Florida Barataria-Terrebonne Bays, Louisiana Convened 1992 Peconick Bay, New York Corpus Christi, Texas San Juan Harbor, Puerto Rico Tillamook Bay, Oregon REFERENCES Abbaszadegan, M., C.P. Gerba, and J.B. Rose. 1991. Detection of Giardia with a cDNA probe and applications to water samples. Appl. Environ. Microbiol. 57:927-931. Alexander, L.M., A. Heaven, A. Tennant, and R. Morris. 1992. Symptomatology of children in contact with seawater contaminated with sewage. J. Epid. Commun. Hlth. 46:340-344. AMSA (Association of Metropolitan Sewerage Agencies). 1990. 1988-89 AMSA Pretreatment Survey Final Report. Washington, D.C.: Association of Metropolitan Sewerage Agencies. APWA (American Public Works Association). 1992. A Study of Nationwide Costs for Implementing Municipal Stormwater BMPs. Final Report. Water Resources Committee, Southern California Chapter. Chicago, Illinois: American Public Works Association. Balarajan, R., V.S. Raleigh, P. Yuen, D. Wheller, D. Machin, and R. Cartwright. 1991. Health risks associated with bathing in sea water. Brit. Med. J. 303:1444-1445. Bej, A.K., R.J. Steffan, J. Dicesare, L. Haff, and R.M. Atlas. 1990. Detection of coliform bacteria in water by polymerase chain reaction and gene probs. Appl. Environ. Microbiol. 56:307-314.
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Managing Wastewater in Coastal Urban Areas Bendinelli, M., and A. Ruschi. 1969. Isolation of human enterovirus from mussels. Appl. Microbiol. 18:531-532. Borrego, J.J., R. Cornax, M.A. Moringo, E. Martinez-Manzanares, and P. Romero. 1990. Coliphages as an indicator of faecal pollution in water: Their survival and productive infectivity in natural aquatic environments. Water Res. 24:111-116. Cabelli, V.J., A.P. Dufour, L.J. McCabe, and M.A. Levin. 1983. A marine recreational water quality criterion consistent with indicator concepts and risk analysis. Journal of the Water Pollution Control Federation 55:1306-1314. Cheung, W.H.S., K.C.K. Chang, and R.P.S. Hung. 1990. Health effects of beach water pollution in Hong Kong. Epidemiol. Infect. 105:139-162. CH2M-Hill. 1992. Final Combined Sewer Overflow Facilities Plan and Final Environmental Impact Report. Volume II, Recommended Plan. Prepared for the Massachusetts Water Resources Authority, Boston, MA, September 20, 1992. Colburn, K.G., C.A. Kaysner, C. Abeyta, Jr., and M.M. Wekell. 1990. Listeria species in a California coast estuarine environment. Appl. Environ. Microbiol. 56:2007-2011. DeLeon, R., and C.P. Gerba. 1990. Viral disease transmission by seafood. Pp. 639-662 in Food Contamination from Environmental Sources, J.O. Hriagu, and M.S. Simmons, eds. Somerset, New Jersey: John Wiley & Sons, Inc. DePaola, A., L.H. Hopkins. J.T. Peeler, B. Wentz, and R.M. McPhearson. 1990. Incidence of Vibro parahaemolyticus in U.S. coastal waters and oysters. Appl. Environ. Microbiol. 56:2299-2302. Desenclos, J.C.A., K.C. Klontz, M.H. Wilder, O.V. Nainan, H.S. Margolis, and R.A. Gunn. 1991. A multistate outbreak of hepatitis A caused by the consumption of raw oysters. Am. J. Public Health. 81(10):1268-1272. Ellender, R.D., J.B. Map, B.L. Middlebrooks, D.W. Cook, and E.W. Cake. 1980. Natural enterovirus and fecal coliform contamination of Gulf coast oysters. J. Food Protec. 42(2):105-110. EPA (U.S. Environmental Protection Agency). 1986. Ambient Water Quality Criteria Document for Bacteria. EPA A440/5-84-002. Washington, D.C.: U.S. Environmental Protection Agency. Fewtrell, L., A.F. Godfree, F. Jones, D. Kay, R.L. Salmon, and M.D. Wyer. 1992. Health effects of white-water canoeing. Lancet 339:1587-1589. Gerba, C.P., S.N. Singh, and J.B. Rose. 1979. Waterborne viral gastroenteritis and hepatitis. CRC Crit. Rev. Environ. Control 15:213-236. Goyal, S.M., C.P. Gerba, and J.L. Melnick. 1979. Human enteroviruses in oysters and their overlying waters. Appl. Environ. Microbiol. 37:572-581. Kassalow, J., and D. Cameron. 1991. Testing the Waters: A Study of Beach Closings in Ten Coastal States. New York, New York: Natural Resources Defense Council. Knight, I.T., S. Shults, C.W. Kaspar, and R.R. Colwell. 1990. Direct detection of Salmonella spp. in estuaries by using DNA probe. Appl. Environ. Microbiol. 56:1059-1066. LADPW (City of Los Angeles, Department of Public Works). 1991. Marine Monitoring in Santa Monica Bay, Annual Assessment Report for the period July 1989 through June 1990. Los Angeles, California: Environmental Monitoring Division, Bureau of Sanitation, City of Los Angeles, Department of Public Works. Mearns, A.J., M. Matta, G. Shigenaka, D. MacDonald, M. Buchman, H. Harris , J. Golas, and G. Lauenstein. 1991. Contaminant Trends in the Southern California Bight: Inventory and Assessment. Administration Technical Memorandum NOS/ORCA 62. Seattle, Washington: National Oceanic and Atmospheric Administration. MMSD (Milwaukee Metropolitan Sewerage District). 1980. MMSD Wastewater System Plan Planning Report. Milwaukee, WI: Program Office, Milwaukee Water Pollution Abatement Program.
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Managing Wastewater in Coastal Urban Areas NRC (National Research Council). 1991. Seafood Safety. Washington, D.C.: National Academy Press. O'Keefe, B., and J. Green. 1989. Coliphages as indicators of faecal pollution at three recreational beaches on the Firth of Forth. Water Res. 23:1027-1030. Palmateer, G.A., B.J. Dutka, E.M. Janson, S.M. Meissner, and M.G. Sakellaris. 1991. Coliphage and bacteriophage as indicators of recreational water quality. Water Res. 25:355-357. Perales, I., and A. Audicana. 1989. Semisolid media for isolation of Salmonella spp. from coastal waters. Appl. Environ. Microbiol. 55:3032-3033. Richards, G.P. 1985. Outbreaks of shellfish-associated enteric virus illness in the United States: Requisite for development of viral guidelines. J. Food Protec. 48:815-823. Richardson, K.J., A.B. Margolin, and C.P. Gerba. 1988. A novel method for liberating viral nucleic acid for assay of water samples with cDNA probes. J. Virol. Methods 22:13-21. Roesner, L.A., E.H. Burgess, and J.A. Aldrich. 1991. The hydrology of urban runoff quality management. InProceedings of the 18th National Conference on Water Resources Planning and Management/Symposium on Urban Water Resources, May 20-22, 1991. New Orleans, LA. New York, New York: American Society of Civil Engineers. Rose, J.B., H. Darbin, and C.P. Gerba. 1988. Correlations of the protozoa, Cryptosporidium and Giardia with water quality variables in a watershed. Water Sci. Tech. 20:271-276. Rose, J.B., C.N. Haas, and S. Regli. 1991. Risk assessment and control of waterborne Giardiasis. Am. J. Public Health. 81:709-713. Rose, J.B., C.P. Gerba, S.N. Singh, G.A. Toranzos, and B. Keswick. 1985. Isolating viruses from finished water. Journal of the American Water Works Association 78(1):56-61. SCCWRP (Southern California Coastal Water Research Project). 1989. Annual Report 1988-89, P.M. Konrad, ed. Long Beach, California: SCCWRP. SCCWRP (Southern California Coastal Water Research Project). 1990. Annual Report 1989-90, J.N. Cross, ed. Long Beach, California: SCCWRP. Schaiberger, G.E., T.D. Edmond, and C.P. Gerba. 1982. Distribution of enteroviruses in sediments contiguous with a deep marine sewage outfall. Water Research 16:1425-1428. Van Donsel, D.J., and E.E. Geldreich. 1971. Relationships of Salmonellae to fecal coliforms in bottom sediments. Water Research 5:1079-1087. Vaughn, J.M., E.F. Landry, T.J. Vicale, and M.C. Dahl. 1980. Isolation of naturally occurring enteroviruses from a variety of shellfish species residing in Long Island and New Jersey marine embayments. J. Food Protec. 43(2):95-98. Volterra, L., E. Tosti, A. Vero, and G. Izzo. 1985. Microbiological pollution of marine sediments in the southern stretch of the Gulf of Naples. Water, Air and Soil Pollution 26:175-184. Wait, D.A., C.R. Hackney, R.J. Carrick, G. Lovelace, and M.D. Sobsey. 1983. Enteric bacterial and viral pathogens and indicator bacteria in hard shell clams. J. Food Protec. 46(6):493-496.
Representative terms from entire chapter: