SEWAGE POLLUTION IN BRITISH COLUMBIA IN PERSPECTIVE

by Michael Waldichuk

West Vancouver Laboratory Fisheries and Oceans Canada 4160 Marine Drive West Vancouver, B.C. LIBRARY V7V 1 N6 SCIENCES

B.C. .

Presented at the Workshop on Municipal Marine Discharge, Sheraton Plaza 500 Hotel B.C. 14 - 15.February 1984

TD 763 W3 1. I I () :i. l C 1984 Canadian Industry Report of Fisheries and Aquatic Sciences These reports contain the results of research and development that are useful to industry for either immediate or future application. Industry Reports are directed pri­ marily towards individuals in the primary and secondary sectors of the fishing and marine industries. No restriction is placed on subject matter and the series reflects the board interests and policies of the Department of Fisheries and Oceans, namely, fish­ eries management, technology and development, ocean sciences, and aquatic envi­ ronments relevent to Canada. Industry Reports may be cited as full publications. The correct citation appears above the abstract of each report. Each report will be abstracted in A qua tic Sciences and Fisheries Abstracts and will be indexed annually in the Department's index to scientific and technical publications. Numbers 1-91 in this series were issued as Project Reports of the Industrial De­ velopment Branch, Technical Reports of the Industrial Development Branch, and Technical Reports of the Fisherman's Service Branch. Numbers 92-110 were issued as Department of Fisheries and the Environment, Fisheries and Marine Service Industry Reports. The current series name was changed with report number 111. Details on the availability oflndustry Reports in hard copy may be obtained from the issuing establishment on the front cover.

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sciences · TD763 W3 1984 Ces rapports contiennent les Waldichuk, M. utiles l'industrie pour des sewage pollution in !'intention Columbia in perspective de l'industrie des et de la me 145396 0 4 0 15643 c. l reflete la vaste gamme des int : _ Library / MPO - Bibliothequ e 1111111 11111 1111\ 111111111\ 11111111111111111111111 Oceans, notamment gestion des p · ques et environnements Les Rapports tions completes. Le titre e publie dans la revue Aqu, C,::, !'index annuel des publica Library Les numeros de I Institute of Ocean Sciences travaux de la Direction d Fisheries and Oceans Canada Direction du developpeme Box 6000 (9860 W. Saanich Rd .) services aux pecheurs. Les dustrie du Service des Sidney, B.C . V8L 4B2 Le nom de la a C La page couverture po Jes rapports sous couvertu SEWAGE POLLUTION IN BRITISH COLUMBIA IN PERSPECTIVE

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LIBRARY INSTITUTE OF OCEAN SCIENCES BOX 6000 TD763 W3 1984 B.C. Waldichuk, M. by Sewage pollution in British Columbia in perspective 145396 04015643 c.1 Michael Waldichuk West Vancouver Laboratory Fisheries and Oceans Canada 4160 Marine Drive West Vancouver, B.C. V7V 1N6

Presented at the Workshop on Municipal Marine Discharge, Sheraton Plaza 500 Hotel, Vancouver, B.C. 14-15 February 1984 - ii -

TABLE OF CONTENTS

Page ABSTRACT i i i 1. INTRODUCTION 1 2. HISTORICAL PERSPECTIVE 2 3. CHARACTERISTICS OF SEWAGE THAT AFFECT THE AQUATIC ENVIRONMENT AND ECOSYSTEM 7 3.1 Solids 8 3.2 Microorganisms 9 3.3 Dissolved Organic Constituents 10 3.4 Nutrients 11 3.5 Metals 12 4. TREATMENT 13 4.1 Primary 13 4.2 Secondary 14 4.3 Tertiary 15 5. CASE STUDIES 16 5.1 Greater Vancouver 16 5.2 Greater Victoria 18 5.3 Comox - Courtenay 19 5.4 Nanaimo 21 5.5 Other Coastal Areas 24 6. SEWAGE MANAGEMENT OPTIONS AND TRENDS IN THE 80 1 s 25 7. PROBLEMS THAT REQUIRE SOLUTIONS 28 7.1 Specificity of Microbiological Tests 29 7.2 Sludge Disposal 30 7.3 Sewage Treatment Lagoons 30 7.4 Urban and Agricultural Runoff 31 7.5 Viability of Pathogenic Microorganisms from Fecal Matter in Seawater 31 7.6 Epidemiological Studies on the Effects of Bathing in Sewage-contaminated Seawater 32 7.7 Tracing Sewage Chemically 32 7.8 Dechlorination 33 8. CONCLUSIONS 33 REFERENCES 37 FIGURES 1 - 6 45 - iii -

ABSTRACT

The historical development of sewage disposal, in the context of its effect on the environment, is reviewed briefly, starting with unconfined land disposal, then the outdoor privy, through the septic tank and tile field disposal system, and finally, the various forms of municipal sewage collection, treatment and disposal into fresh and marine waters. The characteristics of sewage, i.e., solids, microorganisms, dissolved organic constituents, nutrients and metals, that affect the aquatic environment and ecosystem are discussed. A brief review is given of the three levels of treatment: primary, secondary and tertiary. Then four case studies of sewage treatment and ocean disposal in coastal areas of British Columbia (Greater Vancouver, Greater Victoria, Comox-Courtenay, and Nanaimo) are reviewed in some detail. Other areas are discussed with respect to specific problems. The perceived problems are largely associated with the impact of sewage bacteria and viruses on shellfish and the potential hazard to consumers. Closure of shellfish beds to harvesting, because of sewage pollution, has had a major economic impact. An unanticipated effect of effluent disposal from the Iona Island Sewage Treatment Plant has been depressed oxygen in waters overlying Sturgeon Bank and debilitation of fish exposed to these waters, particularly during the warm months of summer.

The current trend in sewage disposal is toward deep (50-100 m) coastal outfalls, at considerable distance (1-5 km) from shore, with a diffuser designed for rapid initial dilution (1:100-150), and trapping of the sewage/seawater mixture at considerable depth (20-40 m) below the surface. Treatment is often of the primary type, involving only solids removal, although there is argument for disposal of raw comminuted sewage with retention of only the floatables. Disposal of sewage sludge continues to be a problem in some areas. If disposal is far enough from bathing areas and shellfish beds on shore, there is sometimes no compelling reason for disinfection, particularly in view of the toxicity of chlorine to fish-life. 1. INTRODUCTION

I am going to talk about some of my percep,ti ons, as an oceanographer and one who has spent most of his professional career on marine pollution problems as they pertain to effects on fisheries, concerning pollution in this province by domestic or so-called sanitary sewage. _Certain questions emerged during the course of my involvement with sewage pollution from time to time in the last 30 years, and I plan to pose them here. They tell me that rather than

11 11 11 sewage , the more genteel term is "municipal wastewaters • Whatever one wishes to call it, the material we are dealing with originates almost entirely from human wastes, and as our populations increase the world over, so does the amount of sewage. The effects of these wastes are also bound to increase, if we continue to dispose of them untreated into the aquatic environment; and so it is encumbent on us to cope in some way with this increased volume of sewage, if we are not to witness serious ecological and human health damage. Scientists, looking at industrial wastes and sewage in the marine environment on a worldwide basis (GESAMP 1982), have often noted that the effects of sewage are local, and hence, globally inconsequential. The impact, however, is largely in the coastal zone where 90% of our fisheries resources are located and virtually all the water-related marine recreation takes place.

While the volume of sewage discharged is generally increasing with time, the composition of raw sewage and the environmental and ecological effects of discharging a unit volume of it into surface waters, be they freshwater or marine, are not substantially changing. What is changing, however, is the way in which we perceive the effects of sewage on the aquatic ecosystem, human health and aesthetics., The environmental movement of the 1970 1 s has had a great impact on perceptions of pollution by sewage as well as by many other • materials. Some of these perceptions may have been ill-founded, but they have necessitated, nevertheless, a very close look by environmental scientists and engineers at all the environmental and ecological effects of sewage, and have led to designs of systems for treatment and disposal that would minimize these effects as much as possible.

In this review, I plan to take a brief historical excursion through the - 2 -

.. past to examine the ways that sewage has been handled from ancient times; then I shall review the general effects of sewage in the aquatic environment as I perceive them; and finally, I shall touch on a number of sewage disposal problems in British Columbia to show how they were resolved at the time, and then take one particular case study, in the Nanaimo area, and follow it through from my earliest involvement in it some 30 years ago to the present day. I hope that this example will illustrate not only the changing technology and approaches in sewage treatment and disposal during the last 3 decades, but will also show the changing attitudes of people toward this subject.

2. HISTORICAL PERSPECTIVE

It is useful to take a historical glance at the way sewage has been. disposed of since the earliest times. Primitive societies, and some of these still exist today, did not worry much about the way sewage was disposed of; and excreta were deposited almost anywhere, especially in a rural setting. Some more advanced societies even considered excrement as a good source of fertilizer for their crops, and methodically collected so-called ''night soil" for this purpose. This has been particularly true even into modern times in the heavily-populated areas of the Orient. In a less methodical fashion, such "fertilization'' continues in subsistence agriculture of Central and South American countries. A giant step for man in sewage disposal was from 11 just anywhere" to the privy or pit toilet. This type of facility may be found in various forms in less well developed rural areas in Canada, including assorted park campsites. The next major advance in the technology of sewage collection and treatment was the septic tank and the tile distribution system of the disposal field. It continues today in areas not serviced by municipal sewerage systems; and when it is properly designed, and in a suitable area, it can function very well indeed for a long time, without perceptible ill effect to the environment. Some even maintain that it can provide needed moisture and nutrients during dry periods for a lawn covering the tile field.

Urban communities have had to install sewerage systems from the earliest times. Archaelogical finds show that the ancient Greeks had plumbing in their - 3 -

magnificant structures, and it is likely that the collected sewage was piped to some neighbouring stream, lake or-seashore. I would presume that the Romans had developed effective sewage collection and disposal systems two millenia ago. Their aqueducts for fresh water and facilities for baths remain in the historical ruins of Rome. No doubt, sewage collected from populated sections of ancient Rome was discharged raw into such streams as the Tiber and the Po, which are used in some instances for this purpose even today. Other large cities of Europe, such as London, also discharged raw sewage into the nearest large water course, which in the case of London was the Thames River.

Disposal of untreated sewage into rivers, lakes and coastal waters would probably have continued to the present if certain environmental, ecological and human health problems had not arisen. Some of the great epidemics of the Middle Ages were undoubtedly due to improper sanitary practices, particularly in disposal of sewage. There were also ecological problems, but these had low priority compared to effects on human health. In the case of London and the Thames River, the last salmon were seen going upstream around 1823. This did not appear to be cause for alarm at the time. However, when the river went anoxic for periods during the summer in the middle of the last century, and the smell of hydrogen sulfide commenced to emanate from the waters, the offensive odour affected proceedings in the House of Commons nearby; then it was time to do something about it. They draped the windows with sacks soaked in lime water to absorb the hydrogen sulfide before it entered the legislative chambers. The Metropolitan Board of Works was established in 1856 and was charged with construction of a system of main drainage. The Northern and Southern Outfall Works were brought into operation within ten years, and the discharge of crude sewage onto the river banks was abolished by moving the outfalls toward the sea and thus providing more water for dilution of the sewage. Sedimentation channels were introduced by 1889, and the sewage solids were discharged further out into the Thames estuary. This practice of sludge disposal continues to this day and has been monitored quite intensively in recent years.

A serious attempt to correct the low dissolved oxygen situation in the Thames was not sought until after 1950, however, when thorough studies were conducted on the River by scientists from the Water Pollution Research - 4 -

Laboratory at Stevenage. A classical document on this study was published (DSIR 1964), which recommended solutions to ameliorate the low dissolved oxygen problems in the Thames River. Most of these recommendations, involving installation of a substantial number of sewage treatment plants, were implemented. The oxygen concentrations in the Thames River estuary have been largely returned to acceptable levels. At last count, some 57 species of fish, including Atlantic salmon, have returned to the river. The improvement of dissolved oxygen conditions in the Thames River is considered to be one of the great environmental restoration success stories of this century.

Our zeal to modernize and improve sewage collection and disposal has sometimes backfired on us. For example, in some cases where septic tanks have done a reasonably good job in disposing of our sewage, we have decided to replace this 11 antiquated 11 system by a properly designed sewage collection system and an outfall for disposal of the raw sewage into a nearby river, lake or coastal water. Where septic tanks, servicing individual households, had essentially dispersed the sewage over the countryside, the sewerage system now efficiently collected the sewage and discharged it at one point. Needless to say, it was not long before problems appeared, especially if the sewage was not treated, and/or it was discharged into waters where dispersion and dilution were slow.

If the sewer outfall was in a slow-flowing river, the old "oxygen sag" problem occurred somewhere downstream of the discharge. Aesthetic and recreational values were reduced in the vicinity of shallow outfalls almost everywhere. Shellfish harvesting became unsafe. Ecological degradation became evident regardless of where the sewage was discharged, whether freshwater or the marine environment. The ill effects were not only due to untreated sewage. In some cases, even effluent from primary and secondary treatment caused problems, as noted for example, with the effluent from the Iona Island Sewage Treatment Plant in Vancouver (Birtwell et al.1983). Over-enrichment with nutrients by sewage effluent is not necessarily confined to freshwater environments. A few years ago a major problem emerged in the popular recreational waters on the Adriatic coast of Italy, with excessive

11 11 algae and fish kills due to red tides , as a result of input of sewage effluent through the Po River and coastal outfalls (Anon. 1979). I am not - 5 -

sure what final solution was chosen to resolve the problem, but clearly, it appeared at the time that tertiary treatment was needed to remove nutrients from the sewage before discharging the effluent.

People's perceptions have changed about sewage, treatment and the effects of sewage on the aquatic environment, on the ecology and on human health in the last three decades. Before 1950, sewage was something that people generally did not want to talk about. "Out of sight, out of mind" might have been the motto in those days. If unsightly fecal matter was not apparent and if there was no offensive odour, then no one paid much attention to sewage and its disposal. But we have had an environmental revolution since then. Suddenly everyone is concerned and everyone is an instant expert. We have not only had to make sure that any sewage disposal practice applied is safe, but people will often insist on a hefty safety factor. Some will argue that this becomes a clear application of an 11 overkill 11 approach to sewage disposal at great expense to the taxpayer. Others will counter that argument by pointing out instances where sewage treatment and disposal systems became rapidly overloaded, even though they were designed to meet the needs of a municipality over a much longer period of time. They argue further that it is better to over-design a system than to find that it soon becomes inadequate and leads to intolerable pollution.

A big factor in sewage disposal, of course, and this is one that not too many people appreciate or understand, is the behaviour of different aquatic environments in dispersing, diluting and in generally assimilating sewage. There are those who insist on the same degree of treatment for sewage, regardless of where it is discharged. Clearly, there is no need for tertiary treatment to remove nutrients in most coastal waters where there is good mixing and rapid dispersion and dilution. The added nutrients, to a certain point at least, may even do some good in fertilizing such waters and increasing phytoplankton production as a food source for the higher trophic levels in the food chain. The same may apply for a fast-flowing, large river. In the U.S.A., there has been a backlash against environmental legislation of the early 1970 1 s, and many coastal cities and towns are applying for exemption under current legislative requirements to meet the target of secondary treatment for sewage by 1985 {originally 1981 was the - 6 -

target year, but this has been extended at least twice).

In the United Kingdom, which is a relatively small island country, there has always been the attitude that the ocean is there to be used for, among other things, sewage and industrial waste disposal. Fortunately for the U.K., that country 1 s coast is blessed with a comparatively large tidal range, so that tidal mixing and dispersion are rapid, allowing little accumulation of discharged sewage and industrial waste to occur. Early studies (U.K. 1959) indicated that there is no epidemiological evidence that such diseases as typhoid and cholera can be transmitted through bathing in sewage-contaminated seawater. For those more serious diseases at least, the conclusions drawn from this U.K. study have never been scientifically contradicted, as far as I know. Hence, there has been a great deal of pressure in the U.K. to forego treatment, except for the most rudimentary kind (solids removal), for sewage destined for sea disposal. The U.K. authorities have often chosen deep offshore outfalls with diffusers for sewage effluent discharge along the coast (Gameson 1975). They have opted for depuration of such shellfish as oysters eaten raw, in order to remove sewage microorganisms from seafood, rather than disinfecting the sewage. Prevention of contamination of shellfish is still a compelling argument for sewage treatment before disposal into shellfish-bearing waters in Canada, fortunately. This does provide a better basis for maintaining clean coastal waters for recreation than any kind of regulations based on health effects of bathing in sewage-contaminated seawater.

In the U.S.A., particularly along the coast of southern California, sewage disposal into the sea has been practised for a long time. The attitude of early sanitary engineers in California (Rawn 1960) was that one of the resources of the sea is its availability for sewage disposal. Because it can act as a natural treatment system, it should be used for this purpose with respect to sewage. To quote Rawn (1960): 11 To be able to relegate the entire job of secondary sewage treatment to a few holes in the end of a submarine pipe and the final disposal of the effluent to the mass of water into which the fluid is jetted, and to accomplish this without material cost of maintenance and none for operation, presents a picture of such great allure as to capture the imagination of the dullest and justify extensive exploration - 7 -

11 into ways and means of satisfactory accompl i shment •

To some extent, this philosophy prevails today in California and perhaps elsewhere. But it has been moderated considerably by conservationists and scientists who have noted the decline of kelp forests {Clendenning and North, 1960), the presence of fin erosion in bott0m fish {Mearns and Sherwood, 1974), and certain other ecological changes in the vicinity of sewage outfalls. These concerns are reflected in the large amount of research that has been conducted by various state and federal agencies, universities, particularly the Allan Hancock Foundation of the University of Southern California and the Southern California Coastal Water Research Project {Bascom 1983). Emphasis has often been placed on deep ocean outfalls with properly designed diffusers {Rawn et al.1960; Brooks 1960, 1963). Designs of new treatment plants and outfalls for sewage and sludge disposal in Southern California are now fully taking into account environmental considerations {Brooks et al. 1983).

Sewage disposal practices in British Columbia have undergone many changes in the last three decades. There were virtually no treatment plants in 1950. Sewage was generally discharged raw through numerous shallow outfalls. By 1960, various types of treatment plants and sewage lagoons began to be installed or planned in numerous cities and towns. Deep outfalls were replacing shallow outfalls for many sewage disposal systems. By 1980, systems that had been installed during the 1950 1 s and 1960 1 s were being regarded as inadequate, either because they were underdesigned for sewage volumes of the 1980 1 s, or they were not meeting the more stringent pollution control standards for protection of fisheries resources, human health and amenities demanded by authorities through new regulations.

3. CHARACTERISTICS OF SEWAGE THAT AFFECT THE AQUATIC ENVIRONMENT AND ECOSYSTEM

Sanitary sewage, consisting of human wastes comprised of urine and excrement, has a composition that is well known and the components are readily amenable to treatment. Domestic sewage, however, consists of much more than human excreta in that it also contains kitchen wastes, which may be quite - 8 -

substantial if a garburator is used. Add to this metallic leachings, such as iron and copper from the plumbing systems, and we commence adding the metallic load to the sewage. If we consider institutions such as hospitals, dental clinics and laboratories, high school and college laboratories, and photographic processing laboratories hooked into the municipal sewerage system, then we begin to see the addition of assorted chemicals, including more metals, into the sewage. Small industries, such as tanneries, electroplating establishments, photoengraving shops, distilleries and breweries, may also discharge their wastes into the municipal sewer system. Used oil sometimes enters the municipal sewer from automobile garages and service stations. At this point, we must refer to the material in the sewers as truly ''municipal wastewaters", inasmuch as it consists of much more than just sanitary or domestic sewage. It is this added waste of non-human origin that often causes the major problems in sewage treatment plants, and in the receiving waters when the sewage is discharged untreated.

The general effects of sewage in the marine environment are illustrated by a schematic block diagram in Figure 1. In the following, the effects of the different components of sewage on the marine environment and ecosystem are briefly discussed.

3.1 Solids It is the solids in sewage, consisting of fecal matter, paper and other floatables, that render sewage aesthetically offensive. The solids may also contain pathological organisms, which may pose a human health hazard through possible contamination of seafood or transmittal of disease through sea bathing. There may be an ecological effect from solids, in that turbidity created by particles suspended in the water column reduces light penetration and inhibits photosynthesis. Eventually, the solids settle to the bottom and modify the benthic habitat. Undigested solids from sewage undergo decomposition and reduce the oxygen present in the sediments and overlying water. There may also be a toxic effect of substances leached from solid materials of non-human origin added to the municipal sewage. Clearly, it is the solids from raw sewage that can have the most detrimental long-term ecological effect in a marine area used for disposal. - 9 -

3.2 Microorganisms The potential health hazard of ·pathogenic microorganisms in sewage causes the greatest concern about inadequate treatment and improper disposal of sewage. The spectre of typhoid, cholera and polio being transmitted through improper sewage disposal is forever present, even though it rarely occurs in our modern society. It is more likely that hepatitis and gastroenteritis might be transmitted through sewage contamination, and this more often occurs as a result of malfunctioning septic tanks and sewage-disposal tile fields than from sea disposal of sewage.

The greatest hazard of pathogenic organisms in the marine environment lies in the possible contamination of shellfish beds, which are harvested for human consumption. Filter-feeding bivalves can concentrate bacteria and viruses originating from sewage. Oysters are often consumed raw on the halfshell. Other bivalves may be eaten only partially cooked. Obviously, it is essential that either contamination of these shellfish be avoided, or some form of depuration of the contaminated animals be applied, if the health of consumers is to be protected. In British Columbia, regulations exist under the federal Fisheries Act that require shellfish-bearing waters to be comparatively free of sewage contamination, by prescribing upper limits on total and/or fecal coliform counts. Shellfish meat that exceeds certain coliform counts is banned from the marketplace. While these regulations have done much to protect the shellfish consumer against the dangers of pathogenic organisms in shellfish, they have also been effective in closing substantial shellfish-producing areas in the province to harvesting of oysters and clams. Your convenor (see Kay, These Proceedings) is better qualified than I am to talk about that subject. Protection of oysters against sewage contamination, nevertheless, has been a strong line of defence against sewage pollution in this province in that it has demanded measures for sewage treatment and/or improved effluent disposal techniques that may not have been required otherwise. This has helped to preserve water quality for purposes other than shellfish, such as bathing and other water-contact recreation.

There are also regulations in this province under the British Columbia Health Act on the maximum permissible coliform count in bathing waters. Areas where the coliform count exceeds this level may be posted as polluted by - 10 -

health authorities. Bathers may heed the warning and avoid such areas. But o.ther than that, regulations on bathing water quality do little to improve the situation, except where public pressure may be applied politically to clean up an area.

Again, as with many aspects of pollution by sewage and other substances, the impact of microorganisms in the marine environment may be overplayed. Their effect is greatest in nearshore waters, especially in areas with shellfish beds. Further offshore the impact is comparatively minimal, especially if the sewage effluent has undergone substantial initial dilution. The marine environment is a hostile one to human intestinal flora. There is a rapid decline in the concentration of fecal coliforms in the sea, not only because of dilution, but also due to sedimentation, predation by marine protozoa and zooplankton, destruction by solar ultra-violet light and possible antibiotic effect of seawater and planktonic algae (Zo Bell 1936; Duff et al. 1966; Mitchell 1968; Carlucci and Pramer 1959, 1960a, 196Gb, 1960c, 1960d). Moreover, the rate of growth of enteric organisms in seawater is greatly suppressed (H. Seki, personal communication). Therefore, one must conclude that there is little compelling evidence to suggest that even a moderately high coliform count above an outfall at some distance from the shore (>1000 m) would pose a threat to either shellfish or the quality of the bathing waters along the shore, unless there is an onshore current or wind for a high proportion of the time.

Sewage microorganisms have little known impact on marine organisms themselves. A particular virus that affects a specific fish or invertebrate could conceivably be introduced with sewage. For example, Bonamia sp., a blood-cell parasite, has recently devastated stocks of the native English oyster, Ostrea edulis, in southern England. It is highly unlikely that this parasite was introduced through sewage, but more likely, it moved across the English Channel from Holland and France with seed oysters or imported adults brought to the south coast of England for fattening.

3.3 Dissolved Organic Constituents Sewage, by the very nature of its source, is generally characterized by its high organic content, both in solid and dissolved form. Much of the - 11 -

organic material is still partially undecomposed when it reaches the sewer. It forms a suitable substrate for bacteria. Whether the raw sewage is discharged directly into natural waters or whether it is piped into a treatment plant, bacteria begin immediately. to decompose the biodegradable organic components. In natural waters, this decomposition leads to uptake of dissolved oxygen, which can have a serious impact in waters where replenishment of oxygen is slow. In a sewage treatment plant, the action of bacteria is a vital component of the treatment process, both in sludge digestion and in stabilizing the effluent. Generation of methane from sludge digestion is basically due to decomposing bacteria.

An important ecological effect of sewage is the reduction of dissolved oxygen in receiving waters and the stress this causes aquatic animals. The 11 oxygen sag 11 downstream from an outfall is typical of the impact of sewage discharged into a river. Depression of dissolved oxygen in the vicinity of a marine outfall is not uncommon in coastal areas, where the seawater is confined and not rapidly flushed by the tides. The degree of treatment accorded the sewage makes a big difference in the oxygen depletion that eventually occurs in receiving waters. Primary treatment with removal of solids is a big step in reducing oxygen depletion. However, problems may still arise, even though they may be less sustained and less acute (Birtwell et al.1983). Secondary treatment further diminishes the oxygen uptake in receiving waters by the sewage effluent. If sewage is not subjected to these treatment processes in a plant, it essentially undergoes the same degradation process in nature, but in a less accelerated way. If the receiving waters are rapidly replaced, and oxygen replenishment is adequate to meet the needs of bacteria in decomposing organic matter, as well as being high enough to sustain animal life present in the water, then no ecological pamage is anticipated. Even if dissolved oxygen is not depressed to a lethal level, however, low oxygen concentrations can exert a stress on aquatic animals and cause an overall ecological impact.

3.4 Nutrients Sewage contains a relatively high concentration of both nitrogen- and phosphorus- containing nutrients. It is particularly high in urea, ammonia, nitrates and other nitrogenous constituents. Most of these materials are - 12 -

assimilated quite readily by aquatic algae. Unfortunately, nuisance organisms such as blue-green algae sometimes bloom in profusion. In waters where there is a good exchange, the addition of nutrients from sewage may be quite inconsequential pollutionwise, and could even provide some needed nutrition for phytoplankton, and thereby, increase production at the higher trophic levels. If the exchange is poor, however, and the volume of sewage is large in relation to the volume of the receiving water, then problems of nutrient over-enrichment can arise (Ryther and Dunstan 1971; Waldichuk 1969, 1979). The resulting excessive growths of algae exhibit aesthetically unpleasant conditions in coastal waters, as well as all the other associated problems of eutrophication more commonly observed in lakes. Moreover, toxic algae, such as the dinoflagellates Gonyaulax sp., may be stimulated and lead to paralytic shellfish poisoning or fish mortality. Dissolved oxygen may be diminished in bottom waters when large blooms of algae die, settle to the bottom and decay. Certain animal species may be eliminated. In Portage Inlet, near Victoria on Vancouver Island, for example, there was a substantial population of the native oyster, 0strea lurida, during the 1930 1 s (Elsey, 1933). By the 1960 1 s, these oysters had disappeared, and it is believed that pollution by sewage was at least in part responsible.

There has been considerable debate about eutrophication due to sewage in the Strait of Georgia (Stockner et.!!_. 1979, 1980; Parsons et.!!_. 1980; Clark and Drinnan 1980). While the assimilative capacity of the Strait of Georgia for sewage is not limitless, it seems rather unlikely that the amount of sewage the Strait of Georgia receives through the Fraser River and from the cities and towns located on its shores, in relation to the volume of water in the Strait and the comparatively high rate of exchange, would cause any trend toward eutrophication in the foreseeable future. By the nature of the mixing processes that occur in the Strait, however, it is conceivable that higher production of phytoplankton, reflecting greater input of nutrients from sewage, could occur along the periphery of the Fraser River plume, where the impact on the Strait of Georgia of any changes in the nutrient loading of the Fraser River could be the greatest (Waldichuk 1983).

3.5 Metals As noted earlier, metals are not normally associated with ordinary - 13 -

domestic sewage. There are so many other commercial, industrial and institutional inputs of wastes, with substantial metal concentrations, into a municipal sewerage system, however, that metals ultimately become a significant component of the total municipal wastewaters. The metals in municipal wastewater may enter in dissolved form, but they usually end up being sequestered by the particulate material, and are found associated with the solid organic phase. In this form, the metals are not readily released into the water to become biologically available to marine organisms. There is some evidence from work conducted in the United Kingdom, however, that silver may be an exception (Bryan in press).

4. TREATMENT

It is not proposed to deal with sewage treatment here in any detailed way (there are various handbooks on the subject), but only to point out the general levels of treatment available and what they accomplish in rendering sewage less harmful in terms of its characteristics described in the previous section. The three levels of treatment considered here may be regarded differently, in the amount of treatment involved in each, by different authorities. Every degree of treatment has a cost associated with it, and planners must decide what level of treatment must be sought under given environmental conditions in receiving waters, to adequately protect marine organisms and ecosystems, human health and amenities.

4.1 Primary The most rudimentary form of treatment that can be applied to sewage is comminution, which merely macerates the sewage to break up the larger solid pieces of fecal matter and paper. This creates a less offensive condition at an outfall than absolutely raw sewage. What is normally considered as primary treatment, however, is solids removal from the sewage before discharge into receiving waters. The effluent may or may not be disinfected with chlorine, or some other agent such as ultra-violet light, ozone or bromine. It is this form of treatment that is applied at both the Iona Island and Lions Gate Sewage Treatment Plants in the Greater Vancouver area. At the former, the sludge is digested and then stored in lagoons for future use as a soil - 14 -

conditioner; while at the latter, the digested sludge is discharged into the .turbulent waters of the First Narrows in Burrard Inlet. Sludge digestion at both plants provides methane as an energy source for the operation. Chlorination of effluent is applied at the Iona Island Sewage Treatment Plant, if high coliform levels on the beaches of Spanish Banks and other recreational parts of English Bay dictate it.

4.2 Secondary What is normally termed secondary treatment renders the sewage effluent virtually potable water, with a comparatively high mineral content. It involves solids removal through settling, coarse screening, and filtration through sand and gravel and possibly through other filter media. Charcoal may be used for removal of dissolved organic substances and colour in the effluent. The BOD (biochemical oxygen demand) of the effluent may be reduced by ponding and aeration. Other advanced techniques of 11 polishing 11 the effluent may be used. Before discharge, the effluent is normally disinfected with chlorine, but this is not always the case. Chlorine is toxic in comparatively low concentrations to aquatic organisms, and it has been found necessary to eliminate the residual chlorine with sulfur dioxide in some treatment plants, such as the Annacis Island Sewage Treatment Plant.

Needless to say, secondary treatment~is much more costly than primary treatment. There are many more stages in the treatment operation, so that malfunctions are more likely to occur, and greater attention from plant personnel is needed to maintain the plant in proper operation and to prevent such malfunctions. Planners examine very carefully the need for secondary treatment, in relation to the environmental and resource values that must be protected, before opting for secondary treatment, because of capital and operational costs involved.

4. 3 Tertiary This level of treatment is usually only required when there is a danger of nutrient over-enrichment of inland waters of great recreational or other resource values. Basically, it is applied where there is a threat of eutrophication, as has been apparent in the lower Great Lakes and in the Okanagan lakes. Few marine areas are threatened with eutrophication, except - 15 -

in poorly flushed inlets and confined embayments.

Tertiary treatment involves the removal of nutrients. It can be carried out in a number of ways, by physical, chemical or biological processes, or by some combination of these. The most primitive form of biological treatment involves the growth of algae in sewage treatment ponds, and removal of the algae by grazing fish. This technique has been utilized in Europe with carp ponds. This fish is in great demand, as a normal source of protein and for festive occasions in various European cultures. Efforts in the U.S.A. to utilize raw sewage for enhanced growth of edible molluscs and fish in aquacultural practices (J.H. Ryther, personal communication) were thwarted by the U.S. Food and Drug Administration, which banned the sale of seafood produced in this way, because of the risk of transmittal of pathogenic organisms from sewage contaminated shellfish to consumers. The algae, of course, could also be filtered from the effluent, thereby effecting a reduction in nutrients.

The more commonly used technique in North America for nutr.ient removal from sewage effluent is coagulation and scavenging of nutrients with lime treatment. It means, of course, that there is a great deal of lime sludge from such treatment for disposal. Incineration plants or lime kilns are probably capable of recovering the lime used in such treatment, but I am not sure if this is the common practice.

A third technique that is rather attractive, but has been more experimental than actually widely used in practice, is electrolysis of sewage effluent, using brine or seawater added to the effluent as an electrolyte (Føyn, 1960). With an iron cathode and a graphite anode, hydr.ogen and chlorine are produced when a direct current is passed through the dilute brine solution. As the gases bubble through the effluent, scum is formed at the surface with a large proportion of the nutrients in it. The chlorine disinfects the sewage effluent when it bubbles through it from the anode. Unfortunately, the system is a heavy electrical energy consumer, and presumably for that reason, never met with wide acceptance in the sewage treatment community. - 16 -

5. CASE STUDIES

There has been a host of interesting municipal sewerage developments in this province during the last three decades, which represent trends in technology, attitudes and degree of environmental protection. In each there has been as element of controversy, with some groups or individuals advocating high levels of safety against environmental degradation, while others have been more liberal in their approach to the problems, hoping that costs could be curbed and the public purse protected. The sites discussed here are shown in Figure 2.

5.1 Greater Vancouver 1 By the late 1940 s, the Vancouver and District Joint Sewerage and Drainage Board (VDJSDB) decided that something should be done about an overall, long-term sewerage plan for Greater Vancouver. Numerous sewers throughout this part of the Lower Mainland discharged raw sewage through individual outfalls into the Fraser River, Burrard Inlet, False Creek, and Port Moody. A study was commissioned by the VDJSDB from A.M. Rawn, who had had a great deal of experience in design of sewerage systems and ocean outfalls in southern California. Out of this study emerged the so-called 11 Rawn Report" ( Rawn et �- 1953), which gave a long-term plan for a sewerage system in Greater Vancouver, with several major treatment plants and outfalls into the Fraser River, the Strait of Georgia and Burrard Inlet. This plan is still being followed in a general way today.c

The first phase of the Rawn Plan was collection of sewage from the core of Metropolitan Vancouver, elimination of various outfalls into Burrard Inlet and the Fraser River, and installation of a major sewage treatment plant on Iona Island. The process of selection of an outfall site for this treatment plant led to extensive surface current studies by the Greater Vancovuer Sewerage and Drainage District (GVSDD, successor to the VDJSDB) and oceanographic studies by the Pacific Oceanographic Group at the Pacific Biological Station in Nanaimo during 1949-1950 (Fjarlie 1950; Pacific Oceanographic Group 1951). Much was learned about the movements of the Fraser River water into and out of Burrard Inlet on different tidal ranges during periods of small and large Fraser River flow. Aerial photography of the silty - 17 -

Fraser R. water gave useful pictorial displays on how sewage effluent would drift, and it was this information that was largely used in the design of the effluent discharge system, (Fjarlie 1950, Waldichuk 1967). On the basis of these studies,the decision was made to discharge the effluent from the Iona Island Sewage Treatment Plant through on excavated channel on Sturgeon Bank, with a jetty flanking the north side of the channel to prevent sewage from flowing directly onto the beaches of English Bay. The objective in the design of the treatment plant for sewage and of the effluent disposal system was mainly protection of the recreational beaches and not the protection of shellfish or other living resources.

The Iona Island Sewage Treatment Plant was opened in 1963. Beaches in English Bay were considerably improved by elimination of outfalls in both English Bay and False Creek, although there were occasional high coliform counts which necessitated chlorination of the effluent from the treatment plant. Shellfish harvesting in the Fraser River estuary, Boundary Bay and Burrard Inlet has been banned for a long time because of sewage pollution, and is not expected to be reinstated even with more treatment plants and a higher degree of treatment. There are other non-point sources of coliforms, such as urban and agricultural runoff, which are much more difficult to control than municipal wastewater discharged through outfalls.

With the passage of time, accumulation of organic and inorganic materials from the Iona Island Sewage Treatment Plant effluent began to manifest itself in certain undesirable conditions. Sturgeon Bank in the vicinity of the sewage effluent channel exhibited ecological changes from depositon of organic material (Otte and Levings 1975; McGreer 1979a, 1979b, 1982). High metal concentrations appeared in the sediments (Grieve and Fletcher. 1976) and in the organisms (Parsons et al.1973). In more recent years, low oxygen concentrations have been found in water overlying the sediments near the sewage effluent channel in summer, and this has led to incidents of considerable numbers of distressed fish under certain tidal and weather conditions (Birtwell et al.1983). To correct this situation, the Greater Vancouver Regional District is considering installation of a submarine outfall and a diffuser at considerable depth off Sturgeon Bank, following a public hearing conducted on the matter by the British Columbia Pollution Control - 18 -

.. Board in Vancouver during February 1980 (Birtwell et al. 1981).

Other treatment plants in the Greater Vancouver area followed the Iona Island Sewage Treatment Plant and these include: (1) The Lions Gate Sewage Treatment Plant to serve the North Shore of Burrard Inlet, with discharge of sewage effluent and sludge into the First Narrows off Burrard Inlet; (2) The Lulu Island Sewage Treatment Plant to serve Richmond, with discharge of effluent into the mouth of the main arm of the Fraser River; and (3) the Annacis Island Sewage Treatment Plant, serving Burnaby, Coquitlam and Surrey, and discharging into the Fraser River just west of New Westminster. The latter plant has been controversial for a long time, because of the potential impact on salmonids from metals and chemicals contained therein, such as copper, zinc, residual chlorine and chlorinated organic compounds.

5.2 Greater Victoria As in the Greater Vancouver area, the City of Victoria and the adjoining municipalities of Esquimalt, Oak Bay and Saanich were served by a series of shallow outfalls for raw sewage disposal. Noteworthy locations of such outfalls were Clover Point, Macaulay Point, McMicking Point and Finnerty Cove which were, in some cases, quite unsightly with visible sewage plumes and scavenging sea gulls over the outfalls; the beaches were sometimes posted with I signs warning bathers against swimming there because of sewage pollution. The I extension of the Inner Harbour of Victoria, consisting of the Gorge and J' -1.l: Portage Inlet, received seepage from septic tanks and discharge from small I sewage treatment plants on the Colquitz River, a small tributary of Portage Inlet. The problem in Portage Inlet was high coliform counts, over-enrichment with nutrients and excessive algal growth, which tended to be aggravated by poor flushing in the system (Waldichuk 1969).

Plans for the Capital Regional District called for consolidation of some of the sewers into larger trunk sewer systems and discharge of sewage through outfalls that would extend into deeper water further from shore than some of the early outfalls. Diffusers would be installed on the outlets of the discharge pipelines to effect rapid initial dilution and dispersion. Often the length of submarine _pipeline and depth of outfall became an issue because of the high costs involved, and a number of studies were commissioned (e.g., - 19 -

CH₂M Hill Canada Ltd. 1979) to determine cost-effective lengths of outfalls. The objective in a suitable design was to have the sewage trapped at some depth between the outfall and the surface, where the sewage could disperse rapidly without appearing at the surface. ·One of the problems with outfalls producing a surface sewage field in Juan de Fuca Strait at the approaches to Victoria and Esquimalt is that the prevailing winds are from the southwest and transport surface water, along with sewage contained therein, onto the beaches. This was clearly shown by surveys using large sheets of paper, along with other markers, for time-lapse aerial photography, during June 1965, as described for a similar earlier study (June 1964) in Cordova Bay (Keenan et al. 1966; Waldichuk 1967). The one advantage that exists in sewage disposal from the Greater Victoria area into Juan de Fuca Strait is that tidal mixing and currents are comparatively strong and sewage becomes rapidly diluted and dispersed. A subsurface sewage field would tend to become dissipated rapidly through the actions of turbulent mixing and tidal currents, so that it should not manifest itself at the surface.

5.3 Comox-Courtenay Sewage disposal in the Comox-Courtenay area has been a problem for some time, because of the effects on the prime oyster production area of Baynes Sound and Comox Harbour. As early as the 194O 1 s, the oyster leases in Comox Harbour were considered to be contaminated by sewage seeping from septic tanks and shallow outfalls serving groups of residences or commercial establishments. Plans were developed by the late 195O 1 s to install an improved sewage collection and disposal system for Comox. Oceanographic studies were conducted in Comox Harbour and at its approaches in Baynes Sound during January-February 1958, May 1961, and August 1962 (Waldichuk et al. 1968). The oceanographic conditions there have been described,by Waldie (1951), Waldichuk (1962) and Morris et al.(1979).

The early studies showed that sewage could be discharged from Comox into the northern end of Baynes Sound, without having it transported by currents back into Comox Harbour, provided it was discharged far enough away from Goose Spit. Depending on the direction of the tidal current, sewage at the surface would be transported either seaward over the Comox Bar (ebb tide) or into Baynes Sound (flood tide). An outfall was subsequently installed at a depth - 20 - of 22 metres (12 fathoms), about 0.8 km (0.43 n. mi.) from shore, in northern Baynes Sound. Initial testing for coliforms above the outfall showed low counts. These probably increased somewhat with time, as the volume of sewage discharged from Comox increased, but it is doubtful that coliforms from this source reached oyster leases in significant numbers at any time.

The City of Courtenay chose to put in a sewage lagoon, adjacent to the mouth of the Courtenay River, to treat its sewage. While the system was considered to be comparatively effective in reducing the solids and dissolved organic constituents in the sewage effluent, as well as substantially reducing the coliform count, there was still a significant contribution of coliforms to j Comox Harbour. A 99% reduction in coliforms from an MPN (most probable 6 number) of 10· per 100 ml still leaves a count of 10,000 per 100 ml in the lagoon effluent. Any reduction in coliforms effected by the deep outfall in Baynes Sound was counteracted by the increase from the Courtenay lagoon. Moreover, seepage from septic tanks in communities south of Courtenay continues to introduce effluents with high coliform counts. Hence, oyster leases in Comox Harbour have never recovered sufficiently from high coliform counts to be reopened (see Kay, These Proceedings).

The latest development for the Comox-Courtenay area has been a consolidation of the sewage from Comox, Courtenay and the Canadian Forces Base Comox into one system for treatment and ocean disposal. After various oceanographic and fisheries resource studies in the area, numerous deliberations among the municipalities, consultants and environmental agencies, and finally a public hearing before the B.C. Pollution Control Board, the decision was taken to install a conventional secondary sewage treatment plant, and to discharge the effluent through a pipeline running due east from Cape Lazo at a depth of 61 m (200 ft) at 2743 m (9,000 ft) from shore. I understand (M.J. Stewart, personal communication) that the treatment plant is almost complete and the outfall two-thirds installed at present (February 1984). The cost is expected to be $13 million for the treatment plant and nearly $4 million for the outfall. While this treatment and disposal system might be regarded by some as a clear case of 11 overkill II for the job that has to be done, and a shear waste of energy and other resources, it may yet prove to be a wise investment in the long term. The history of - 21 - sewage treatment and disposal systems in British Columbia has been generally one of short-sightedness and underdesign for anything except the immediate and short-term needs.

5.4 Nanaimo By 1952, there was realization in Nanaimo that the municipal sewage disposal system had shortcomings to say the least. There were three main outfalls discharging raw sewage on the shore (Fig. 3). At the south end of Nanaimo, one sewer discharged into the log booming area of the Nanaimo River estuary tideflats. A second outfall served the core of Nanaimo and discharged into mid Nanaimo Harbour. The third outfall discharged into the south end of Newcastle Island Channel at the Nanaimo Yacht Club (a recreational section of the waterfront there was referred to by the local users as "sewer beach"). The proposed new outfall would have discharged into the north end of Newcastle Island Channel at Pimbury Point (locally known as Brechin Point).

Needless to say, the three outfalls were aesthetically offensive and interferred with the recreational uses of Nanaimo Harbour, as well as having led to the closure of shellfish harvesting. Workers involved with sorting of logs in the log booming area of the Nanaimo River estuary found the presence of sewage in their "work place" not only unpleasant but of concern for health reasons. There was a need for corrective action.

By 1953, the City Council of Nanaimo decided to take action to improve sewage collection and disposal. A survey was needed in Nanaimo Harbour and Departure Bay to determine where the best sites should be located for sewer outfalls. A community effort was organized to do this. Two weekends, 23-24 May and 30-31 May, 1953, were utilized for surface float observations, with observers working through different tidal stages from dawn to dusk. The Nanaimo Yacht Club provided the vessels to deploy and follow floats. CNAV EHKOLI served as a mother ship anchored in Nanaimo Harbour. INVESTIGATOR No. 1 was anchored for the same purpose in Departure Bay. Floats consisted of wooden pegs, 5 cm x 5 cm (2 in x 2 in) by 46 cm (18 in) long, weighted at one end with a steel spike to keep them floating vertically with only the tip of one end exposed above the sea surface. Float data were collated on the two mother vessels. Current observations with current meters at different depths - 22 -

were also made from these vessels.

The results of these two weekend surveys showed that the surface waters in both Nanaimo Harbour and Departure Bay responded to winds for movement (Fig. 4). Southeast winds caused surface water to flow northward from Nanaimo Harbour into Departure Bay. Northwest winds usually generated a southward flow. Variable or confused surface currents arose from calm conditions or small local winds. Deeper currents were tidally generated and appeared to follow the rise and fall of the tide (Fig. 5). Coliform counts also varied at given locations with wind and tide (Fig. 6), suggesting that it would be prudent to sample on the same stage of tide and under the same wind conditions, when sampling on a weekly or monthly basis, if there'is to be consistency from one sampling period to another.

The information obtained in these surveys is more fully given in other reports (Tully and Waldichuk 1953; Waldichuk and Tully 1953). It was presented to the City Council of Nanaimo in the autumn of 1953, with the recommendation that the City abandon its plan to install an outfall at Pimbury Point, and instead, put a deeper outfall into the Strait of Georgia on the northeast side of Newcastle Island, to serve the northern part of Nanaimo, and off Jack Point into Northumberland Channel for sewage from south Nanaimo. An alternative option suggested was a secondary sewage treatment plant including chlorination, with no specific location given for an outfall to discharge the sewage treatment plant effluent.

The Nanaimo City Council accepted the recommendation for outfalls off Jack Point (actually Duke Point) and off the northeast coast of Newcastle Island. These were installed by about 1957 for comminuted raw sewage disposal. At the time, we felt that this was indeed a "quantum jump" in improvement of disposal facilities for Nanaimo's sewage. Ten years later it was considered archaic. As the City's population began to increase to the north, it was not long before the northern outfall began to show signs of being overloaded. It was a comparatively shallow outfal 1, being no more than about 5 metres (16.3 m) below lower low tide, and rather close to shore. A greyish white sewage plume could be seen almost always at the surface, with the usual flock of gulls scavenging assorted floating organic materials. - 23 -

Under certain tidal and wind comditions, there was movement of sewage from this outfall into Departure Bay. A concern was noted about sewage entering Nanaimo Harbour from the outfall in Northumberland Channel. About 10 years after the two outfalls were installed, the. Regional District of Nanaimo began to look at ways of making further improvements in sewage treatment and

1 11 11 disposal. This was in the late 1960 s during the environmental revolution , when there was a great deal of pressure to provide the ultimate in sewage treatment, as well as discharging the effluent far offshore for rapid dilution and dispersion to avoid nearshore environmental degradation.

The final plan for sewage disposal from Nanaimo (Dayton & Knight Ltd. 1972) called for a primary treatment plant in Hammond Bay, north of the City proper, and disposal of the effluent through a submarine outfall with a diffuser at a depth of 84 m (275 ft), near the Five Finger Island. The system commenced operation in 1974. The diffuser was installed in 1975. From what I understand, the sewage effluent field is always submerged, and there is little or no evidence of sewage at the surface above the outfall or at more distant points. Pictures taken in dives of the submersible PISCES IV indicate some accumulation of organic particulate material in the Y formed by the two diffuser legs. Analyses of the sediments, adjacent to the outfall showed higher-than-background organic content (6-9%) by 1979 (see Pomeroy, These Proceedings). Metals have apparently increased in the sediments of the zone of impact to concentrations that are not high enough to cause concern, but rather serve as a signal that the situation merits watching. Fish can usually be seen apparently attracted by either the sewage effluent or the invertebrates colonizing the outfall pipeline. Monitoring of the water quality has not disclosed any serious adverse effects, although the visibility from PISCES near the outfall had been reduced from 2 - 3 min 1979 to less than 1 min 1983 (Pomeroy, These Proceedings). How long conditions remain acceptable at the outfall will be determined by how rapidly Nanaimo grows and on the design capacity of the treatment plant and the outfall. But is it not anticipated that a new sewage treatment and disposal system will be needed as soon after the 1974 installation as after the 1957 outfalls. The environmental awareness prevalent in the 1960 1 s and 1970 1 s ensured that a substantial safety factor was included in the lastest design. - 24 -

5.5 Other Coastal Areas Almost every urban community in British Columbia has had to modify existing facilities or install new treatment plants and outfalls in the last two decades to meet the needs of growing populations and new requirements for environmental protection. Some have gone ahead quite routinely. Others have met with considerable controversy. Towns like Crofton, Chemainus, Ladysmith, Parksville, French Creek and Qualicum on the east coast of Vancover Island, bordering on the Strait of G�o�gia (Fig. 2), have had to consider the needs to protect oysters as well as bathing areas. There are few oyster-growing areas, where installation of a sewage treatment plant and improved disposal facilities have succeeded in reopening leases that had been closed owing to high coliform counts. The notable exception is Parksville Bay. Prior to 1978, Parksville discharged unchlorinated septic tank effluent through an outfall 21m (69 ft) deep, extending 640 m (2100 ft) offshore into Parksville Bay. In 1978, the town of Parksville diverted_its sewage to the secondary treatment plant at the French Creek Water Pollution Control Centre, which discharges its effluent through an outfall at 61 m (200 ft) depth, 2438 m (8000 ft) offshore, outside of the French Creek Boat Basin. A resurvey of the Parksville Bay area in 1979 showed a significant improvement in coliform counts (see Kay, These Preceedings). There was such a dramatic reduction in coliform count following diversion of the Parksville sewage to the French Creek secondary treatment plant that oyster leases could be reopened.' Obviously, urban and agricultural runoff had not contributed substantially to the high counts that led to the orginal closure.

In other areas, it is sometimes puzzling why designers chose the kind of treatment and disposal systems that were installed. The sewage lagoon for Courtenay, as already mentioned, certainly did not improve the coliform situation for oyster culture in Comox Harbour. As another example, a primary sewage treatment plant was installed in Ladysmith Harbour, a prime oyster 1 producing area, during the mid 1960 s. The sewage sludge that is collected in this plant is periodically discharged into Ladysmith Harbour, rather than being dumped on land or into deep waters of Stuart Channel or the Strait of Georgia. It contributes to high coliform counts on the oyster leases in Ladysmith Harbour (see Kay, These Proceedings). In Pender Harbour, another prime oyster area on the mainland shore of the Strait of Georgia, sewage - 25 -

pollution seemed to be a major problem in oyster culture for many years. Whether it was eventually resolved or· whether the oyster growers finally gave up, I am not sure.

Recent plans for a new sewage system and marine outfalls for Prince Rupert call for essentially raw sewage discharge into Prince Rupert Harbour. Existing discharges of raw sewage have contributed to high fecal coliform counts (>100,000 per 100 ml) at some locations in the harbour. While there may be no molluscan shellfish to be concerned about in the harbour, crabs and fish are held in live wells by some fishermen. There is always a risk of contamination, not only in such live-holdinq facilities, but also in using harbour water to flush fish holds after discharging the catch, and not disinfecting or sanitizing afterward. The use of harbour water to flood fish holds to facilitate off-loading by syphon pump can lead to contamination of the catch. Ice-dispensing pipes and chutes, submerged in the harbour during high tides, result in subsequent contamination of ice used to chill fish. Fisheries and Oceans in Prince Rupert advise fishermen against fishing for herring and smelts that come into the harbour, because of the presence of sewage pollution.

A great deal of controversy continues to surround the sewage disposal scheme, either still in the planning stage or now under construction, in Ganges Harbour on Saltspring Island. The opponents feel rather strongly that the sewage effluent will not be adequately carried out of the harbour and dispersed by tidal currents, while the proponents point to the high cost of further extension of the outfall. Economics and cost-benefit now enter rather strongly into design considerations for sewage treatment plants and outfalls, such as the ones planned for Ganges Harbour.

6. SEWAGE MANAGEMENT OPTIONS AND TRENDS IN THE 80's

For those charged with management of municipal wastewaters, the objective is to dispose of them in the most inexpensive way without undue degradation of the environment, either aesthetically or by destruction of living resources and habitats. Protection of recreational values of coastal waters is a prime - 26 -

consideration. The presence of shellfish and sensitive fish habitats that have to be protected in the receiving waters must also be an important element in the planning strategy. It is vital to know whether oysters are at risk or whether herring spawning grounds could be vulnerable to sewage pollution. It makes little sense, for example, to install a sewage treatment lagoon if there are oyster beds in the vicinity of the lagoon outlet. A further consideration must be the nature of the aquatic environment into which raw sewage or treated effluent is to be discharged. It makes a vast difference if such effluents are discharged into exposed coastal waters, where wave action, tides and currents can rapidly disperse and carry away the material, or whether they are discharged into confined inshore waters where flushing action is poor. The physical characteristics of receiving waters play an important role in the way the discharged effluent will behave and the impact it will have on the aquatic environment (Waldichuk 1968). Planners have to take such factors into account when designing treatment facilities and/or outfalls for sewage from coastal municipalities (Waldichuk 1974).

Treatment plants are costly in both capital and operating expenditures. While municipal authorities are cognizant of the need to protect recreational and resource values in coastal waters, there is strong resistance against 1 11 1 gilding the 1 ily as it were. They want to provide treatment and disposal facilities that will meet current needs, and possibly for 20 years into the future, but are reluctant to cover off the problems that may arise half a century hence. Past experience suggests that we have generally underestimated the increase in sewage input with time, and systems have tended to become overloaded earlier than predicted. Perhaps those systems that are providing 1 11 an enormous safety factor with what appears at first glance to be 1 overkill for treatment and outfall design may be financially ahead in the long term.

11 1 After the environmental revolution 1 of the 1960's and 70's, when nothing short of tertiary treatment would do for the environmentally sensitive sector of the public, it seems that we are now into a more environmentally realistic era in the 1980's. We are beginning to look again at the marine environment as having a certain assimilative capacity for sewage. This means that the ocean is being regarded once again, in the way it was perceived by sanitary engineers of 30 years ago, as providing a certain degree of treatment without - 27 -

cost that would otherwise be a burden on the taxpayer. To some extent, one has difficulty in arguing against this attitude. The problem lies not so much in basic domestic sewage but in those many other substances, such as metals, that are added to the municipal sewerage system. Some of these added substances, along with those that are created by the process of chlorination, may be bioaccumulated by marine organisms. Other organic substances that may arise from sewage, industrial wastes and urban runoff tend to accumulate in the substrate in the 11 zone of impact", adjacent to an outfall, and degrade habitats. The goal in any sound municipal wastewater treatment and disposal system, to avoid these problems, is to prevent some of the extraneous substances, such as metals and toxic organic chemicals, from entering the municipal sewerage system, and to make certain that the outfall allows for rapid dilution and dispersion of the effluent. The degree of treatment required will be determined by the volume of sewage, the recreational and resource values to be protected and the physical characteristics of the receiving waters.

The trend in sewage disposal from coastal communities appears to be toward deeper and longer outfalls to deliver the effluent into waters that are rapidly exchanged. By proper design of a diffuser, the sewage effluent field can be kept below the surface, which has both its aesthetic and ecological advantages. Providing there is no build-up of sewage effluent, and such unfavourable effects as depression of dissolved oxygen in the subsurface waters, this approach seems acceptable. Primary treatment to remove solids is generally adopted as being desirable both aesthetically and ecologically. An unresolved problem is still the matter of disposal of sewage sludge. Sanitary engineers would prefer to dispose of it into the sea. There is some argument for keeping it on land for future use as a soil conditioner. fhis practice is generally more costly, and the sludge has limited use on land because of its high metal content.

Disinfection of sewage with chlorine is now being reexamined, not only from the point of view of cost, but also because of the toxicity of residual chlorine and the production of toxic chlorinated organic compounds. Sulfur dioxide appears to effectively eliminate residual chlorine, at additional cost of course. What is not eliminated, however, are the highly stable, toxic, - 28 -

chlorinated organic compounds, e.g., chloramines. The ecological effects of the dechlorination with sulfur dioxide or sulfur-dioxide-releasing compounds is virtually unknown. Ozone and ultra-violet light are viewed as alternative disinfecting agents with less harmful side effects. There is limited experience, however, in the use of these agents. The question is often raised whether disinfection is really needed, if sewage is discharged into the sea at considerable depth and at some distance from shore. The presence of commercial shellfish beds and recreational beaches near the outfall continues to be used as an argument for disinfection of sewage effluent in Canada. In the United Kingdom, these marine uses are no longer used as arguments for sewage treatment or disinfection. Oysters are subjected to depuration if they are excessively contaminated by coliforms. Bathing has not been considered as a basis for sewage treatment to maintain low coliform counts on recreational beaches, since publication of the white paper on the subject (U.K. 1959). Aesthetics are more important for bathing beaches, and every effort is made to prevent floatables, scum, and discoloration from sewage appearing in recreational waters.

Clearly, higher degrees of treatment, including removal of nutrients, are needed if sewage effluents are discharged into confined coastal waters, such as Portage Inlet, that are poorly flushed. Authorities now avoid such areas for sewage disposal and will often instead develop a plan to extend a pipeline into better flushed waters. This applies to semi-enclosed harbours, where a pipeline may be required to take the sewage beyond the barrier islands or protective promontories of land. The costs of both the installation and operation of a secondary or tertiary sewage treatment plant, as well as the problems of operation connected therewith, make such a venture an option only when others that depend on marine environmental dispersion and assimilation are not possible.

7. PROBLEMS THAT REQUIRE SOLUTIONS

As perceived by me during the course of the past three decades in oceanographic studies that were often only on the periphery of investigations into the.effects of sewage pollution in the marine environment, there are - 29 -

still certain unresolved problems that require solutions. The following are some that seem to persist perennially, without solutions appearing on the horizon.

7.1 Specificity of Microbiological Tests The microorganisms chosen for testing ·seawater and shellfish for contamination by human sewage continue to present difficulties of specificity and the meaning of the data. Ideally, one would prefer organisms that are specific for certain pathogens of human origin. The standard total coliform test, as I understand it, takes account not only of human intestinal flora that are present but also the bacteria excreted by other mammals and even birds, such as sea gulls. The fecal colifprm test is more specific for human feces, but even it is believed to include fecal bacteria from dogs and wild animals. It might be reasonably argued that there is a threat to human health from diseased animals, and that there is merit in monitoring bacteria and viruses that arise from feces of such animals. Nevertheless, some health authorities maintain that better protection to human health would be provided by tests for certain specific microorganisms that cause such human ailments as gastroenteritis and hepatitis, contracted through contaminated water and food, than by a less specific group such as coliforms.

Some bacteriologists and virologists propose that specific ailment­ causing microorganisms, e.g., Salmonella sp., be used for a more diagnostic test for the presence of human pathogens. The traditionalists favouring the coliform group counter with the argument that such specific tests are much more difficult and more time-consuming to carry out. Moreover, they may miss other pathogens that high counts of total coliforms or fecal coliforms would at least warn against. On the other hand, there have been illnesses attributed to contaminated shellfish taken from waters where the fecal coliform standard was met. There is a growing body of literature that questions the relationship between enteric viral levels and the total coliform and/or fecel coliform counts in water, sediments, and shellfish. Sources, distribution and fate of enteric viruses in shellfish and their habitat are central to this problem, but are not fully understood, at least in coastal waters of British Columbia. - 30 -

7.2 Sludge Disposal It would seem that after the expense and effort of removing the solids from sewage, land would be a better place for their disposal than the sea. After all, sewage sludge contains organic matter and nutrients that could provide a benefit to agricultural land and lawns as a soil conditioner. Some enterprising sewage treatment plants even package a fertilizer from sludge, e.g., Milorganite from the Milwaukee, Wisconsin, sewage treatment plant. Unfortunately, the presence of metals in the sludge in comparatively high concentrations often makes it unsuitable for agriculture. There is only a limited outlet for residential and park landscaping. Incineration seems hardly the route to go, in view of the energy required to dewater and burn the sludge and the potential for atmospheric pollution.

The one solution for producing a sewage sludge more acceptable for agriculture is to control the input of metals and other toxic substances into the municipal sewerage system at source. Treatment of sewage to remove the metals seems hardly likely to be economically feasible, but one should not totally discount the possibility of technological developments along these lines. If there are absolutely no alternatives to ocean disposal of sewage sludge, then efforts should be made not to dispose of it into valuable shellfish and other fisheries areas, and to seek instead, turbulent and well-flushed waters, where fisheries habitats would not be endangered and shellfish contaminated.

7.3 Sewage Treatment Lagoons It is clear that while sewage treatment lagoons are effective for settling of solids from sewage, reduction of biochemical oxygen demand and reduction of coliform count, they yield an effluent which is still comparatively high in microorganisms. The use of ordinary, single-cell lagoon systems should be confined to areas where there are no shellfish to protect, e.g., Alberni Harbour. Lagoons in tandem might produce an acceptable effluent from the bacteriological point of view. Assuming an MPN of 10,000 fecal coliforms per 100 ml in effluent from the first cell of a lagoon system, a 99% reduction in the second cell would yield an effluent with an MPN of 100 fecal coliforms per 100 ml, which might be regarded as acceptable for shellfish areas, provided there is some dilution in receiving waters. - 31 -

7.4 Urban and Agricultural Runoff Such non-point sources of pollution as urban and agricultural runoff continue to create problems that are not easily amenable to solution. Improved agricultural practices might assist in reducing the drainage of leachates from barnyard manure. The control of coliforms from drainage of fields grazed by farm animals, however, is virtually impossible.

Urban drainage can be collected in storm sewers and treated at considerable cost. There will always be some urban and suburban drainage, however, that enters the sea without being intercepted by sewers. This component of drainage can still provide a substantial contribution of coliforms in estuarine and coastal waters ..

It is the urban drainage that causes waters in harbours of larger towns and cities, such as Vancouver, to continue to be closed to shellfish harvesting, even after treatment plants and deep-sea outfalls have drastically decreased the input of coliforms from sewage. Boundary Bay was closed to shellfish harvesting because of the high coliform count in the waters, probably due to bacteriological input from drainage of agricultural areas, introduced by such streams as the Serpentine and Nicomekl rivers. It remains closed.

7.5 Viability of Pathogenic Microorganisms from Fecal Matter in Seawater. There are indications that there is a rapid die-off of fecal coliforms in seawater for various reasons noted earlier. The important point is whether such a rapid die-off represents the fate also of those pathogenic organisms that cause gastroenteritis, viral hepatitis, respiratory infections, and other sewage-borne maladies. How significant is the presence of low'concentrations of these pathogens 1 km from shore or from a shellfish bed? It seems that better knowledge on the viability of these bacteria and viruses in seawater would do a great deal in providing designers of outfalls a better basis for the minimum length and depth of outfall required, and the amount of initial dilution that should be achieved by the diffuser. - 32 -

. ie.s on the Effects of Bathing in Sewage-Contaminated 7.6 Epidem10. 1 og1ca. 1 stud Seawater While the British studies (U.K. 1959) showed that there is no epidemiological basis for the transmittal of the serious, sometimes fatal diseases, such as typhoid, cholera and polio, through bathing in sewage-contaminated seawater, there was no indication in those studies that the usually non-fatal but distressing afflictions, such as gastroenteritis and hepatitis, are not transmitted through bathing in such waters. Attempts have been made by the World Health Organization to identify sewage-related diseases contracted through sea bathing in heavily used resort areas, such as those on the European coast of the Mediterranean. Recent studies tend to support the contention that bathing in sewage-contaminated seawater can result in disease, especially in areas where there is a high incidence of endemic enteric disease (GESAMP 1982). Epidemiological investigations in the high-density bathing area of the northeastern U.S. seabord, near New York City, generally bear this out (Cabelli 1978; Cabelli et.!!__. 1976, 1979). Studies done in Alexandria, Egypt, on bathers at beaches of the Mediterranean Sea coast, showed that the incidence of disease (eye, nose, throat infections and gastroenteritis) was directly related to the distance from a sewer outfall (S. Keckes, personal communication).

No such epidemiological studies have been reported for British Columbia, or indeed for Canada, as far as I know. It would seem that bathing standards could have a sounder basis, if results were available from such research. At present, there appears to be some doubt as to whether the present bathing standards, based on total and fecal coliform count, are valid.

7.7 Tracing Sewage Chemically The movement and distribution of sewage have been determined in the past by coliform counts. This technique fails, however, if the sewage or effluent from a treatment plant are disinfected, so that the resulting coliform count is very low, or if there has been a rapid die-off of coliforms in the receiving seawater. A more stable constituent, not affected by chlorination, is required. Coprostanol, one of the fecal sterols, has been used as a tracer for sewage by some investigators. It would be useful to map distributions of coprostanol in seawater and sediments adjacent to some of the major ocean - 33 - outfalls for sewage in British Columbia. If concentrations of coprostanol were related to ecological effects observed in such areas as the vicinity of the Iona Island Sewage Treatment Plant outfall on Sturgeon Bank, it might be possible to develop an early warning system on the ecological impact of sewage discharged from coastal outfalls.

7.8 Dechlorination Chlorine is used to kill bacteria and reduce algae in wastewaters, but residual chlorine can be toxic also to aquatic life. Dechlorinating agents include activated graphite, hydrogen· peroxide, sodium thiosulphate, and several sulfur-dioxide-yielding compounds. Better control of the application of sulfur dioxide ts needed. The effects of continuous release of sulfur compounds, at least downstream in rivers, must be investigated. There should be an evaluation of the way metals are compounded by sulfur and their persistence in this form. What are the sublethal effects on marine organisms of dechlorination processes?

8. CONCLUSIONS

Perceptitns by the public of the effects of sewage pollution have changed in the last three decades. From the post World War II period prior to the 1950 1 s, when there was little concern about sewage except in its grossest aesthetic effects, to an increasing awareness of the human health and ecological effects during the 1950's, through the "environmental revolution" of the 1960's and ?O's,. when the ultimate in treatment and techniques for effective disposal to ensure rapid dilution and dispersion were being demanded, we have arrived in the harsh economic realities of the 1980's. There are still those who insist on a high degree of treatment and long, deep outfalls; but there are also those who equally vociferously point out the high cost of such treatment and disposal systems Municipal authorities express their willingness to install treatment plants and outfalls to adequately protect the marine environment and ecosystem, as well as human health, but they generally resist any proposed scheme to exceed the requirements of the intermediate-term future of 20-30 years. Experience has shown that most systems in the past have been underdesigned even for 20 years. - 34 -

The trend appears to be away from costly secondary treatment plants for coastal. municipalities. Primary treatment for removal of solids is customary for the larger sewerage systems. There is a tendency, however, to discharge raw sewage that has been only comminuted through long, deep outfalls with diffusers into waters with good tidal fushing, where currents can rapidly carry away the diluted sewage. Some authorities maintain that there is little point in removing sewage solids only to introduce them into the sea at a later stage. Floatables are still an unsightly manifestation of raw sewage, and environmental engineers advocate the removal of such floating substances before discharge. Total solids removal is not regarded as essential. Chlorination for sewage discharged in this way is now being considered as unnecessary; indeed, if it is used, it could create a toxic condition because of the residual chlorine. Dechlorination with sulfur dioxide adds cost to treatment, and the sublethal effects of by-products are unknown.

Whereas sewage treatment plants and outfalls installed during the 1950 1 s were designed mainly to protect recreational beach areas from high coliform counts, the current priority is protection of living resources. For this reason, dechlorination was instituted at the Annacis Island Sewage Treatment Plant. A deep-sea outfall is being planned for the Iona Island Sewage Treatment Plant, in order to prevent further adverse effects on fishes frequenting Sturgeon Bank.

It is rarely the case that installation of sewage treatment and improvment of sewer outfall facilities lead to sufficient reduction of coliform counts in adjacent coastal waters to warrant reopening of shellfish beds for harvesting. Urban runoff often continues to introduce high bacteriological loads. There is at least one example in British Columbia, however, where bacteriological conditions in coastal waters were so vastly improved following initiation of secondary sewage treatment that shellfish areas could be reopened. This was Parksville Bay, in which shellfish harvesting was restored, after sewage from Parksville was diverted to the secondary treatment plant at the French Creek Water Pollution Control Centre. Judging by these results, the secondary treatment plant and deep-sea outfall for Courtenay - Comox should eventually also effect a reduction in coliform counts on oyster grounds in Comox Harbour and northern Baynes Sound. There - 35 -

may still be sufficient input of coliforms from urban runoff and seepage from septic tanks, however, that the fecal·coliform level required for reopening the oyster leases will not be achieved.

Domestic sewage, without the extraneous materials added to the municipal sewerage system from small industries, laboratories and hospitals, is amenable to assimilation in the marine environment. Metals and certain organic compounds tend to accumulate in both sediments and tissues of marine organisms. Treatment for these substances in a conventional sewage treatment plant is not only difficult, but their presence may interfere with certain biological processes on which treatment depends. Therefore, it is widely recognized that a system of source control must be instituted to prevent these substances from entering the municipal sewerage system. If these special wastes are segregated, they can be subjected to specific treatment to either remove or destroy the offending substances.

The 11 zone of impact 11 of sewage in the vicinity of a well-designed outfall is comparatively small, of the order of tens of metres in radius. The ecological and human health significance of a small zone of impact has not been established. Clearly, if edible marine organisms enter this zone and become too contaminated for human consumption, the impact is significant. If, on the other hand, there is only transient passage of fishes and invertebrates through this impacted zone and contamination of the animals is small, causing no concern for consumers, then the effect of the sewage on living resources as a source of food might be regarded as insignificant. The ecological effect within the zone of impact, however, could be high. Some value judgement has to be assigned to the importance of the size of area impacted for a rational approach to environmental impact assessment of sewage oufalls.,

In spite of a long history of research and monitoring on the effects of sewage in the marine environment, there are still many unresolved problems. These include: (1) a test for sewage pollution that can detect pathogenic enteric viruses; (2) elimination or reduction of constituents, e.g. metals, in sewage sludge that make it undesirable for agriculture; (3) unequivocal results on the ecological effects of sewage sludge disposal in the sea, and better alternative options for sludge disposal; (4) development of lagoon - 36 -

systems that are more effective than lagoons in present use for eliminating undesirable characteristics of sewage; (5) control of pollution in coastal waters from urban and agricultural runoff; and (6) human health effects (acute and chronic) of bathing in sewage-contaminated seawater. - 37 -

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ENVIRONMENTAL EFFECTS MARINE BIOLOGICAL EFFECTS ENVIRONMENT

I I I I I I I I TOXICITY TO STRESS TO DISSOLVED INCREASED BIOTA DUE TO CONCENTRATION HABITAT NUTRIENT ALTERATION FIRST- ORDER OF FECAL AQUATIC INCREASED OXYGEN ORGANICS OF BOTTOM RESIDUAL ANIMALS DUE DEGRADATION TURBIDITY ENRICHMENT (DISSOLVED AND CHLORINE AND COLIFORMS BY DEPRESSION SUBSTRATE EFFECTS TO ANOXIC IN WATER AND PARTICULATE) OTHER TOXIC FILTER FEEDERS ON BOTTOM CONSTITUENTS CONDITIONS

AT EXTREME I I I I I

GENERATION UPTAKE OF EXCESSIVE PATHOLOGICAL LOWERING SECOND -ORDER UPTAKE OF pH AND Eh IN OF METHANE METALS BY CHLORINATED ALGAL GROWTH EFFECTS ON SEDIMENTS AND HYDROGEN EFFECTS BIOTA ORGANICS BY (EUTROPHICATION) FISH AND SULFIDE BIOTA "RED TIDES" INVERTEBRATES

Figure 1. Schematic diagram illustrating the effects of sewage in the marine environment. - 46 -

124°

-

MILES 20

--50° 0 20 40 KILOMETRES

100-tathom depth contour �r,r,rn Depths ;reater than 200 I<::/.../..::'.£.d fathoms (366 metres)

. ·········· .,,,_ _,.. .. ) ·.-PORT:·__. ·.: ANGELES· .

Figure 2. Chart of the southern coast of British Columbia, giving locations of some coastal communities that discharge sewage into the sea.

;ee;;,,. __ -- - 47 -

\ -�·.

-- ...... / ... ·· � c� , - BRANDON IS ,:,:::;,

��---:- ;- . . / .; -;-.;�.:-:.:� - -.,..._.�:. Departure Bay Resort " F " DiPART URE BAY � � ::, BEACH SEWER DEPARTURE BAY OUT FALL (0 ::, AF TER 1957 G"I � oj,-1 . ' 0 \ 0 J,-2 -,::i : ' \ . ) ' \ ·.. "? ' ': ''' J ', , ', ' ', I

' ',, I NEWCASTLE ISLAND : PROPOSED SEWER ' ·. OUTFALL I ',

' l'

I •, I • PROTECTION I I: ISLAND I ' ,: --'POINT Millstone \ \ ·.. I : I. : .. C \ ', \: SATELLITE : \ ,· , ·.. REEF ·.. I: I '. I. LEGEND ,: ··.HARBOUR ... . I ·. HWL ,1?, B ·. LWL : ··., GALLOWS , ·· POINT 3-Fathom Line SEWER _. BEACON ROCK OUTFALL . ,- \ "INVEST IGATOR I" POSI TIONS A .. . J,-1 May 22-24, 1953 .. i,-2 May 29-31, 1953 ·.Ground "EHKOLI'' POSITIONS Nana/mo River j:,-3 May 27-28, 1953 :· SEWER OUTFALL May 23-27 Ground j,-4 May 29-31, 1953 MUD FLATS

Figure 3. C hart of Nanaimo Harbour and Departure Bay, showing the locations of actual sewer outfalls and proposed outfall i n 1953, with subsequent northern outfall after 1957. Subdivisions A - G represent sectors set up for float surveys in May, 1953, with anchor stations for current observations by INVESTIGATOR I and EHKOLI, as shown by the anchor symbols. - 48 -

Jesse 5 f-0 0 0 6 12 18 24 MAY

s WINO VELOCITY IN MPH

a 0 50 b CURRENT SPEED CENTIMETRES PER SECOND 0 1.0 2.0 KNOTS ······· Low Water Line

DEPARTURE 15

... ! 5

°o 6 12 18 24

s s WIND VELOCITY MPH WIND______VELOCITY IN MPH _ C d

Figure 4. Typical current patterns in Nanaimo Harbour and Departure Bay, under different tidal conditions, during: (a) northwest winds; (b) southeast winds; (c) and (d) calm to small local winds. - / �---- I£:! --,' I'-: 0 IO "-. r<) 6 WIND NW 5-8 WIND WIND NW 8-1 KM/HR I NW5-8 KM/HR I KM/HR CHANGING NW0 5 '\ SE I1 11• KM/HR- \D ... / I I o 0 •········ ..!J,,. r<) " -----... 6 . I / · " " 7. M (25 FT.) DEPTH�.. - ·· A / · . I \� \ !. ■■ I ■ 0 0 j::: u \·. . : I __,,,,. z \ -■--:•--■----i----=----- w ·�.. \ '\-- ■ ::cc-- j ■ I ■ ■ ■ 0 IO .a.; I \\ ■ \ ! I ci ..._ _. . SE · ·. \ I �\ �/ I N •• . I 0 , ..._ I I \' I • \ I 0 I '� \ I / \

I- I 0

WIND IN NANAIMO HARBOUR WIND IN NANAIMO HARBOUR

DIRECTION NW SE SE SE DIRECTION NW NW N N SPEED KM/HR CALM 5-8 2-3 8-11 SPEED - KM/HR CALM-2 3-6 5-13

Figure 6. Coliform counts at various shore 1ocat ions in Nanaimo Harbour and Departure Bay (see Fig. 2)' under different tide and wind conditions, during 24 and 31 May 1953.