In Canada, responsibility for the collection and treatment of municipal wastewater, the administration and performance of wastewater facilities, and the control of environmental and health impacts of municipal wastewater is shared across all levels of government.
Municipal governments
Municipal governments have the most direct responsibility for wastewater by having the statutory
mandate to provide sewage treatment. Municipalities also have the power, usually through a
provincial/territorial Municipal Act, to control discharges into the sewer systems. Many municipalities
have taken advantage of these powers to pass sewer use by-laws that are meant to reduce the toxicity
of the effluents and establish source control. For example, the Regional Municipality of Ottawa–Carleton is active in reducing or eliminating toxic inputs to its treatment systems through the
Industrial Waste Sewer Use Control Program. All industrial, institutional, and commercial facilities that
discharge non-domestic wastewater or have their liquid waste hauled to the wastewater treatment
plant are required to comply with the Sewer Use By-law, which sets limits for various pollutants being
discharged into sewers.
Provincial/territorial governments
The provincial/territorial governments are primarily responsible for the regulation of municipal
sewage treatment operations, and most provinces/territories maintain legislative control through
waste control statutes that apply directly to sewage effluent. Operators of wastewater systems
are required to seek approval from their provincial/territorial governments, and these provincial/
territorial permits or licences may specify maintenance and treatment requirements on top of what
is already stipulated in regulations. The approvals may also contain specific limits on the discharge
of effluents. For example, British Columbia’s Waste Management Act requires all municipalities to
have a provincially approved Liquid Waste Management Plan. Discharges without such a plan are
illegal in this province. The provinces/territories also generally have cost-sharing agreements with
the municipalities for sewage-related infrastructure projects.
Federal government
Currently, there is no federal legislation directly governing the deposit of harmful substances
by municipalities into their wastewater. There are two acts, however, that do have the potential to
apply to municipal wastewater. The Fisheries Act is enforced federally by both Fisheries and Oceans
Canada and Environment Canada and addresses a general prohibition against the release of a
“deleterious substance” into waters frequented by fish. The Canadian Environmental Protection Act governs the release of toxic substances to the environment and allows the federal government to create regulations to control or eliminate the use of such substances.
Other
Private industry, research and educational institutions, conservation authorities, and individual
Canadians also have an important influence on decisions concerning wastewater management.
Actions by all of these groups have ensured that the standard of wastewater management in
Canada compares well with that of any other country. However, municipal wastewater is still
a major contributor to the degradation of aquatic habitat, the fouling of recreational waters,
the contamination of shellfish growing areas, and other environmental and health concerns.
Several approaches are being taken to modify our everyday activities and to improve the way in which we deal with these wastes. Actions such as public education and changes in water pricing have resulted in reducing per capita water use by changing attitudes towards water conservation and encouraging water-efficient technology. Another type of action includes the improvement of wastewater treatment capacity by bringing new treatment facilities into operation where none existed and by upgrading existing facilities where they did not provide an adequate level of treatment. Other actions include federal, provincial/territorial, and municipal programs that help communities deal with the local impacts and management of municipal wastewater effluents.
Water conservation: Water metering and pricing, water-efficient technologies
Because excessive water use in Canada increases the need for treatment capacity and reduces
treatment efficiency, a major contribution to improving wastewater quality is simply the reduction
of municipal water usage. Water pricing has been shown to be an effective means of achieving this
objective in Canada and in other industrialized countries (Environment Canada 1994; NRTEE
1996). Generally, as the price of water increases, the amount used decreases and so, in turn, does
the amount of wastewater generated (NRTEE 1996). In Canada, metered households that paid for
water by volume used about 288 litres per capita per day in 1999, compared with 433 litres per
capita per day for households that paid a flat rate (Figure 6).
A municipality was considered “metered” if more than 75% of the population served water was metered and
“unmetered” if less than 25%. The few centres with 25–75% of the population metered were not included in the analysis.
(Source: Adapted from Environment Canada 1999b)
As Figure 7 shows, the percentage of Canada’s municipal population with water meters increased from 52.6% to 57.0% between 1991 and 1999. That means that there is still considerable room for using water pricing as both a conservation and a cost recovery tool. Canadian water prices are currently amongst the lowest in the world. They are less than half those of OECD countries and cover roughly half of the costs of supplying water and treating wastewater (NRTEE 1996; Environment Canada 1998b). These extra costs have generally been paid by federal and provincial/territorial subsidies, but these subsidies are now threatened by tighter budgets and lower grants to municipalities, and many municipalities are likely to place more of the cost of providing water services on the consumer.
Under a full-cost, user-pay system, water users pay a fair price that covers the total cost of water and wastewater services and is based on the actual quantity used. Those who use more water pay more, and those who use less pay less. This method makes water users aware of the true value of water resources and gives them an incentive to use it more efficiently (Environment Canada 1993; NRTEE 1996).
In the past, low consumer prices, along with the belief that Canada’s clean water supply was unlimited,
have resulted in low demand for water-efficient technologies (NRTEE 1996). With rising water prices
and greater social awareness of the need for sustainable development, interest in these technologies
is now increasing. Technologies and methods that could be used to diminish water demand include:
Together, these practices can substantially reduce the amount of water Canadians use and, in so doing, reduce not only the environmental pressures caused by wastewater effluents but also the costs associated with water and wastewater services.
Upgrading wastewater infrastructure and treatment
Because wastewater impacts are caused not only by untreated or inadequately treated sewage but also
by stormwater and CSOs, improvements have been made in the capacity to manage all of these
wastewater types to reduce the release of contaminants and the flow of wastewater.
Sewage treatment
Over the past decade or so, Canada has considerably improved its sewage treatment capacity. As
Figure 8 shows, the percentage of the municipal population on sewers served by wastewater treatment
has increased from slightly more than 70% in 1983 to 97% in 1999. Most of this increase is accounted
for by improvements in Quebec, where the municipal population served by some level of treatment
increased by about 80% between 1986 and 1994.
See Figure 2 for treatment definitions.
(Source: Adapted from Environment Canada 1999b)
The degree of treatment is also improving. In 1999, secondary and advanced (tertiary) treatment were provided to 78% of the municipal population, up from 56% in 1983, and primary treatment was provided to 19%, up from 16% (Figure 9). A recent example of these improvements includes the Annacis Island and Lulu Island treatment plants in the Greater Vancouver Regional District. They were upgraded from primary to secondary level in 1998, serving a combined population of about 1 million people. Another example is the ongoing upgrade of the Gold Bar Wastewater Treatment Plant from secondary to advanced-level treatment with biological nutrient removal. The plant services over 640 000 people from Edmonton and the surrounding area and should be completely functional by 2005.
See Figure 2 for treatment definitions.
(Source: Adapted from Environment Canada 1999b)
The effects of these improvements in sewage treatment are illustrated by the decline in phosphorus loadings that has taken place over the same time period (Figure 10). For Canada as a whole, estimated yearly loadings of phosphorus fell by 44% between 1983 and 1999, despite the 24% increase in the urban population served by sewers during this period (OMOE 1993; Environment Canada 1999b). Loadings of other conventional parameters, such as BOD and TSS, have shown similar trends.
In spite of this progress, many parts of the country continue to discharge untreated or poorly treated sewage into Canadian waters. The problem is significant in Atlantic Canada, where even some larger centres, such as St. John’s, Newfoundland, and Halifax, Nova Scotia, still discharge raw sewage. Across this region, communities without treatment facilities account for slightly more than 40% of the population with sanitary sewers.
(Source: Adapted from Environment Canada 1999b)
Stormwater
Until very recently, stormwater was not considered a serious pollution problem, and, consequently,
few treatment measures were developed. Considerable progress has been made over the past
decade, however, in developing and improving methods for controlling stormwater pollution.
These methods are often referred to as best management practices (BMPs). Many of these practices
aim to control stormwater volume and reduce contaminant loadings by modifying urban
landscapes and existing sewer systems. These practices generally fall into one of the following
categories: policies and source controls, site BMPs, community BMPs, and watershed-level
measures (Marsalek 2000).
Policies and source controls include a variety of non-structural measures aimed at reducing the quantities of contaminants that enter the wastewater system. Public education programs that discourage people from dumping motor oil and other hazardous substances down their drains or from making illicit connections to the sewer system are an example of such measures. So too are urban planning approaches that limit low-density development, reduce the area covered by impervious surfaces, and provide vegetated buffer zones to absorb runoff and protect streams and wetlands. Other examples include the encouragement of procedures to prevent spills during the handling and transporting of chemicals and simple measures such as increased street sweeping and drainage system maintenance, which can greatly reduce the quantities of coarse particles, debris, and other contaminants that are eventually discharged into receiving waters.
Site BMPs are intended to confine runoff within the area in which it occurs. Many communities are now encouraging the adoption of lot-level source controls such as enhanced detention of water on rooftops, disconnection of downspouts from storm sewers, and reduced lot grading to slow down the flow of the runoff.
Other effective approaches for stormwater management include biofiltration by grass filters and the use of swales (broad, shallow channels with dense vegetation on the sides and bottom) as an alternative to gutters and sewers. These measures promote infiltration into the soil, retard the flow of runoff water, and enhance runoff quality by removing pollutants through settling, filtration, adsorption, and biological uptake.
Some communities are installing infiltration trenches or drain fields that allow stormwater to percolate into the subsoil through crushed stone or sand filters, and filter through fabric liners. These systems not only reduce the volume and rate of runoff but also remove pollutants and recharge the groundwater. Stormwater quality can also be improved by the installation of water quality inlets in the sewer system. These are essentially storage tanks that provide some stormwater treatment through sedimentation and skimming of floatables (oil and grease). Oil/grit separators installed downstream of the sewer inlets perform a similar function.
Community BMPs treat larger volumes of stormwater collected over a wider area before final discharge to a receiving water. The most commonly used community BMPs are stormwater management ponds and constructed wetlands. Stormwater management ponds provide a storage area to reduce flow peaks and permit the settling of suspended solids and attached pollutants such as phosphorus. Constructed wetlands use a marsh environment to reduce the levels of particles and dissolved pollutants through physical, chemical, and biological processes that occur naturally in wetlands. Ponds and wetlands are often used in tandem to maximize treatment capacity. Some municipalities may also use community infiltration facilities. These consist of infiltration trenches and basins that are similar to those used in site-level BMPs but are constructed on a larger scale.
Watershed-level measures apply an integrated approach that recognizes the multiplicity of stresses that affect stormwater quality in a given watershed area. These measures try to control such impacts through restrictions on land use, implementation of site-level BMPs, and the protection of natural features and resources, such as wetlands, floodplains, buffer zones, meadows, and soils. Watershed planning can also assist in the selection of suitable sites for facilities such as stormwater ponds and wetlands.
Combined sewers
About 6.7 million Canadians, mostly in older parts of larger municipalities, were serviced by
combined sewers in 1969 (Waller 1969). The present number is likely somewhat smaller because
of population declines in older city areas and the replacement of some combined sewers with
separate storm and sanitary systems. Sewer separation, however, is an extremely expensive way
of solving the combined sewer problem, and it creates an additional stormwater problem in the
process. To reduce separation costs, some local governments, such as the City of Vancouver, have
implemented combined sewer separation programs on a replacement of aging infrastructure basis.
By dealing with approximately 1% of the system per year, this program will result in the elimination
of combined sewers in Vancouver by 2050. Some communities have opted instead to build large
underground storage tanks or storage tunnels to hold CSOs and stormwater for later treatment and
disposal. Although less expensive than sewer separation, this alternative is also costly.
Much attention is now being given to more innovative and cheaper approaches to CSO control. The city of Hamilton, for example, has been experimenting with a sophisticated computerized control system that redirects heavy stormwater flows to underutilized parts of the sewer network, where wastewater can be held until such time as it can be redirected for treatment. High-rate satellite treatment systems, such as one being tested in Toronto, can provide an adequate level of primary treatment for heavy flows that cannot be sent to the main wastewater treatment plant and would otherwise be discharged as raw sewage (Kok et al. 2000). Integrated management approaches that combine a variety of controls at different levels also offer a cost-effective way of dealing with stormwater and CSO problems (Ellis and Marsalek 1996).
Source control
Municipalities have a key role to play in reducing the number, quantity, and concentration of
substances entering sewer systems and MWTPs. Source control will improve the success of
treatment processes and will improve the quality of MWTP effluents. This requires that municipal
wastewater system managers know which substances are likely to be present in sewer systems in
order to effectively remove them from the effluent. A useful management tool that has been
developed for these purposes is the Directory of Sources of Contaminants Entering Municipal Sewer
Systems (CWWA 2000).
Funding for programs to improve municipal wastewater infrastructure and address municipal
wastewater issues comes from all levels of government. An important example of these programs
is the regional ecosystem initiatives, involving the collaboration of the federal, provincial, and
territorial governments, communities and community groups, industry, and Aboriginal peoples to
remediate targeted ecosystems across the country. A major issue that has been targeted through
these initiatives is the effect of municipal wastewater effluent on the environment. There have been
several significant accomplishments in this regard, many of which are highlighted below:
Among the areas where such needs have been identified are the Fraser River estuary in British Columbia, the Athabasca and Wapiti rivers in northern Alberta, and the Canadian shores of the Great Lakes. With the support of regional ecosystem initiatives in these areas — namely, the Fraser River Action Plan, the Northern Rivers Ecosystem Initiative, and the Great Lakes 2000 program — some important improvements in wastewater treatment have been achieved. Two large sewage treatment plants in the Fraser River estuary serving approximately 1 million people, for example, have been upgraded to secondary treatment, and tertiary treatment is being implemented in plants at Grande Prairie and Jasper in Alberta.
Because of the very substantial costs involved in upgrading sewage treatment plants, however, many communities have been slow to implement much-needed improvements. The Great Lakes 2000 program has attempted to deal with this problem by identifying and promoting new technologies that will perform more effectively at lower cost. The program has also promoted the extensive use of process audits to identify ways in which plant capacity and performance can be improved by changes in operating procedures or small modifications to facilities. In several cases, such modifications have made it possible for municipalities to achieve their pollution control targets without resorting to expensive upgrades. For example, an optimization study evaluated ways to reduce the phosphorus release from the Collingwood, Ontario, sewage treatment plant without expanding the existing facility. The innovative use of existing technology provided an estimated $6 million in cost savings.
Another key program is Canada’s National Programme of Action for the Protection of the Marine Environment from Land-based Activities, which intends to prevent marine pollution and protect coastal habitat, such as shellfish growing areas, from land-based human activities, including municipal wastewater effluents. This program is based on existing federal, provincial, and territorial programs, including the regional ecosystem initiatives and Environment Canada’s shellfish programs. Various levels of government in Nova Scotia have also contributed to a project to investigate the true costs and benefits of sewage treatment and source control in Halifax Harbour (Box 8).
In the spring of 2000, the federal government announced a six-year investment in Canada’s physical infrastructure totalling $2.6 billion. A portion of this is to be set aside for “green infrastructure” projects, such as municipal wastewater and domestic sewage initiatives. The federal government has also announced a $100-million Green Municipal Investment Fund and $25-million Green Municipal Enabling Fund to encourage investment by municipalities in best practice and innovative municipal environmental projects. These projects are to include improvements to water and wastewater treatment centres.
In addition to providing funding for water and wastewater projects, the federal government is showing leadership in the management of wastewater effluents through the adoption of sound environmental protection and engineering practices for wastewater management at federal facilities. Final effluent limits have been specified for many pollutants found in wastewater, and, in the event that non-specified materials are found in sewage, a rational approach for determining permitted effluent limits is used. These effluent guidelines are equal to or more stringent than the established standards or requirements of any federal or provincial/territorial regulatory agency (FCEMS WWWG 2000).
| Halifax Harbour, home to the largest urban population in the Atlantic provinces, has long been
plagued by poor water quality and contaminated sediments from the ongoing disposal of
untreated municipal wastewater effluents. Consequently, the harbour’s ecosystem, aesthetic
appeal, and urban quality of life (i.e., recreational value, commercial value, and well-being of its inhabitants) are being seriously impacted. A recent study by GPI Atlantic (Wilson 2000b) has evaluated the costs and benefits of installing four new wastewater treatment plants in the harbour, as proposed under the Halifax Harbour Solutions Plan (HRM 1999a, 1999b). Although the construction of the infrastructure has an estimated price tag of $315 million over 10 years, followed by an operating cost of about $8.8 million per year, the treatment plan could actually generate between $38.5 and $392 million in net benefits over a 60-year period. The ensuing improvements in water quality and aesthetics would result in:
Although the proposed “advanced primary treatment plants” are not expected to remove all the contaminants from the municipal wastewater, significant reductions in suspended solids, oxygen-consuming material, bacterial contaminants, and nutrients should result. In addition to this treatment plan, source control programs, including education, legislation, and enforcement directed at households and industrial and commercial operations, are also recommended. These programs would limit or ban the discharge of many toxic contaminants in the sewer systems, thereby reducing water and wastewater treatment costs and potential future cleanup costs. |
This report has discussed what are currently the most visible issues involving wastewater management, but a variety of other problems also need to be addressed, and other potentially important issues are lurking in the wings. There is a growing awareness, for example, of the need to bring sewage treatment to small and isolated communities in rural areas and in the north, although doing so will involve a number of special problems. In the heavily populated regions of the south, much of the water and wastewater infrastructure is aging and in need of replacement or major repairs. Other, more recent concerns include a group of substances known as endocrine disrupters that appear to have considerable potential to harm wildlife and human health. These can enter the environment through a number of pathways, but urban wastewater is one of the most important.
Aging infrastructure
It has been suggested that more than half of the water pipes in Canada need repair, at a cost of
roughly $6.1 billion. For example, the Ontario Sewer and Watermain Contractors Association
indicated in 1992 that 25% of the water system in Ontario must be replaced and 50% of it must
be restored within the next 60 years. Deteriorating water storage and distribution systems result in
major water loss, sometimes comprising up to 30% of municipal water use in communities across
Canada. Wastewater treatment plants are also deteriorating and being overused by growing
populations, affecting their treatment efficiency. This leads to the release of inadequately treated wastewater or even raw sewage when equipment malfunctions or when volume capacity is
exceeded.
Endocrine disruption
Endocrine systems coordinate and regulate communication between cells by releasing hormones
that act as chemical messengers. Hormones play a number of important roles in the development
of the human body and in the control of bodily functions. The sex hormones testosterone and
estrogen, for example, have a critical influence on the development of the sexual characteristics of
the fetus, while thyroid hormones influence brain development. Another hormone, insulin, controls
the amount of sugar in the blood. Some synthetic chemicals, however, interfere with the normal
functioning of endocrine systems in a variety of ways, often by mimicking the effects of natural
hormones or blocking the cell receptors to which hormones attach. When this happens, important
biological processes are upset and a variety of effects can result, some of them dramatic, others quite subtle.
Substances that can cause these effects include organochlorine compounds, which are widely used in pesticides and industrial chemicals, alkylphenolics such as nonylphenol, which are used in surfactants (a constituent of some detergents), and chemical contaminants such as dioxins and furans. Since these substances tend to be persistent and bioaccumulative, their effects typically show up in birds and fish, which are at the upper end of the food chain.
Endocrine-disrupting chemicals most commonly affect the immune system, the brain and nervous system, and the thyroid gland, but the greatest concern in recent years has focused on chemicals that mimic the effects of the female hormone estrogen and interfere with sexual development and reproduction. Birds exposed to chemicals and insecticides such as PCBs and DDT, for example, are much more prone to reproductive problems and physical deformities. In fish, exposure to endocrine disrupters has been linked to the appearance of female characteristics in males, reproductive problems, enlarged thyroid glands, and depressed thyroid and immune functions. Hermaphroditism has also been well documented in snails exposed to tributyltin, an antifouling agent that, until recently, was used in paints for boat and ship bottoms (Environment Canada 1999f).
Endocrine disrupters that typically occur in municipal effluents include a wide range of industrial chemicals and pesticides as well as natural estrogen and other hormones from human and animal wastes. Synthetic estrogens, such as estradiol, that are used in oral contraceptives are also present. Studies of fish collected downstream of sewage treatment plants in the United Kingdom have shown some evidence of endocrine disruption.
In Canada, the extent of estrogenic effects attributable to sewage effluents has not yet been established. Although some chemical analysis of effluents is currently being undertaken, it is still too early to conclude whether endocrine disruption in wildlife or humans is occurring as a result of chemicals present in municipal wastewater effluents. If municipal wastewater effluents are shown to be a significant source of exposure to endocrine disrupters, however, we will then have to face the major task of devising ways of controlling their entry into the wastewater system and removing any residues from the effluent. Since these substances are usually present only in extremely minute quantities, this will be a considerable challenge. It is also a challenge whose implications go well beyond the technology of wastewater treatment and could force major changes in the kinds of chemical substances we use and the way we use them.
 |
 |
 |
||||
|
||||||
|
|
 |
 |
 |
 |
 |
|
|
  |
 |
 |
 |
 |
|
||||||
 View in print format |
 Previous
| Next 
|
|
|
| | What's New | About Us | Your Environment | Information/Publications | Weather | Home | |
|
|
| Français
| Contact
Us | Help | Search
| Canada Site
|
|
|
| The Green LaneTM, Environment Canada's World Wide Web site | ||
| Last updated: 2005-04-11 | Important Notices and Disclaimers | |
