Engineers design sewage treatment facilities to ensure that certain criteria will be met in the receiving waters. These are set by doctors and scientists to ensure pollution is prevented. Monitoring is to ensure that the criteria are in fact being met and to assist predictions about future needs more accurately than theory allows.
So long as one is limited to theoretical considerations in designing a long outfall, as is the case before one is installed, one can only go on the mathematical criteria developed over the preceding years and from the study of other outfalls already existing.
To apply such criteria many factors must be fed into the formulas to be used and they follow from an examination of the conditions of tide, sea-bed, weather and the like that apply at the proposed discharge site. In the case of Victoria, the engineers knew when they predicted that long outfalls alone would suffice that their work would come under under intense scrutiny. No risk could be tolerated and they therefore opted for factors which were conservative. As an example, the initial dilution of the sewage with sea water as it rises from sea-bed to surface is commonly set at 100:1 under the worst conditions. In our case a figure of200:1 was practical and that was the figure adopted.
When the original permit for the long outfall at Macauley Point was issued, an important condition was that there be a monitoring program. Such a requirement tends to be a two-edged sword because if one is sure enough that pollution will not be caused as to issue the permit in the first place, why is it necessary to monitor it afterwards? However, it was considered that it was necessary to prove to the public that the discharge was doing no harm. Furthermore a treatment site had to be set aside in case the engineers were proved wrong or in case treatment might be found necessary at some time in the future.
To ensure that the results were independent of politicians and engineers alike (for both were under attack for allowing the discharge to take place), the monitoring program was to be done under the auspices of the university. The two university scientists most involved have been Dr.Derek Ellis and Dr.Jack Littlepage. They are referred to in the chapter Who knows What.
Initially, the most dramatic finding was that "the effects of the sewage effluent on the marine environment were insignificant." This referred to conditions soon after the Macauley outfall was installed in the early '70s. The views of the medical health officer that there was no evidence of adverse environmental impact once one was removed from the proximity of the diffusers and no evidence of human health effect either, has already been stated.
There has been other monitoring done over the years in connection with both the Macauley and Clover Point outfalls but nothing has been found to contradict these findings; nor does theory suggest there should be.
It is frustrating that such an overwhelming justification for the predictions of the engineers have received so little publicity. That omission has certainly been contrary to the public interest.
No better overview of the results of the monitoring program could be given than the one encompassed in the chapter entitled ‘Biological Oceanography’ and readers are referred to that and also to the many reports on the subject published by the CRD.
Additional information at Macauley is that nutrient levels were not elevated between '73 and '79; coliform levels reasonably attributable to the outfall have never been detected along the shoreline at any level; heavy metals in sediments and organic levels in fauna were determined to be insignificant according to a study conducted by the Federal Environmental Protection Agency ten years after the discharge had begun.
A 1980 study by J. Hoff showed enrichment of carbon, nitrogen and sulfide in sediments. He predicted that benthic fauna could be affected in an area of 20 to 30 hectares around the Macauley Outfall but whether beneficially or adversely it does not say. In view of evidence of prolific organic growth near the outfall, it seems probable that any change is beneficial.
Dilution is commonly 1000:1 before horizontal dispersion and never less than the 200:1 design figure.
Less information has been obtained at Clover Point but once again no shoreline coliforms reasonably attributable to the discharge have been found.
To properly assess this matter it is important to understand the significance of discharges other than those at Clover and Macauley Points. There are 139 of them between Macauley and Gordon head, nearly all discharging at the shoreline. The impact of the wastes they carry is discussed elsewhere but it has never been monitored, save for a limited number of coliform samples. As it is those outfalls and those only that have led to elevated coliform levels and as this criteria is the most sensitive of all, it seems evident that any other conceivable adverse criteria would arise from these outfalls rather than the two long outfalls.
Whilst routine monitoring continues, Dr. Ellis considers that a more detailed program is needed to update the original work that was done at Macauley, in view of there now being two outfalls and since discharge quantities have increased. Also monitoring technology has improved since the earlier work. Dr.Kendall also recommended that monitoring should continue.
Once again, theory indicates that there should be no problem, but certainly an updated program is warranted based on the same logic that justified one in the first place.
When the recent CRD Liquid Waste Management Plan study began it had not been agreed that such additional monitoring was to take place. That decision was not taken until part way through the program. The CRD was working on the details of what ought to be done as this book was under preparation. It seems likely that the outcome of this work will not be known until late in 1991 or more likely some time in 1992.
The agreement to undertake this work had great significance for the plan. In essence it recognized that it would have been better for the program to have been delayed until the information from the new monitoring was available. How can one decide what is to be done if one has already decided that more information is needed? What is the purpose of the monitoring if there is no chance that the recommendations from the plan will be affected? The CRD was urged to defer further work on the plan until results were known but that was not done. It well illustrates the problem of bringing a bureaucratic machine to a halt once it has steam up. On went the Commissioner's preliminary report and on went his final report. The 'summary and conclusions' it embodies make no mention of monitoring.
If monitoring should ever indicate that a pollution problem is possible, then one could rationally study what steps to take. That might happen in 20 years or in 50 years and the construction of a plant or the lengthening of the outfall would be the two natural alternatives to consider. In either case, to ensure the money was being best spent, one would also compare the environmental benefit to be achieved with the environmental benefit that could be achieved by using the money in other ways.