Ecosystem

Children Playing at Sauble Falls
Family Fun at Sauble Falls

The estimated low flow in the Sauble River as per the consultant’s Assimilative Capacity Report is 287 L/s. The October 2009 system design has a maximum planned discharge rate of 14 L/s and an estimated peak flow of 95 L/s.

About 5% of the river volume would be treated effluent under normal operation during low flow conditions. However, an adverse event during low flow conditions could trigger effluent discharge of up to 95 L/s which is about 33% of the river volume.

One option being considered in the re-opening of the EA would see the collection area increased to an estimated 2,333 connections. This would create a larger peak flow of perhaps 140 L/s and an adverse event under these conditions could result in nearly 50% of the river volume being treated effluent.

In Ontario there have been cases of overflow of partially treated or untreated sewage effluent to receiving water bodies. This can happen during a plant breakdown or when plant capacity is exceeded on a peak flow day. Sometimes a combination of factors can lead to a sewage discharge incident including human error.

Overflow ponds or surge holding facilities can leak into the groundwater aquifer if an impervious boundary is breached. The property purchased by the Town for the site sits on a designated recharge zone for the Amabel-Sauble municipal water system and is designated as a hazardous location. Any upcoming design for a Sauble River wastewater treatment plant will very likely not include an overflow holding pond because the location is under source water protection. It is far from an ideal location.

As time passes there is a temptation to add more hookups to the system through development within the serviced area. The plant operates closer to capacity and can be more susceptible to surge events which may lead to an overflow. Once the plant is built very little can be done to prevent this type of risk.

Lack of a holding pond will increase the risk of a potential untreated sewage discharge event. Such an event could result in damage to the river habitat and a possible beach closing. The following passage is a direct quote from the Environment Canada website:

The Effect of the Release of Wastewater Pollutants
on Ecosystems and Human Health

Releases to surface waters

Several environmental and health impacts resulting from insufficient wastewater treatment have been identified in the scientific literature and actions need to be taken to reduce these impacts. These impacts can include negative effects on fish and wildlife populations, oxygen depletion, beach closures and other restrictions on recreational water use, restrictions on fish and shellfish harvesting and consumption and restrictions on drinking water consumption.

Some examples of pollutants that can be found in wastewater and the potentially harmful effects these substances can have on ecosystems and human health include:

  • decaying organic matter and debris can use up the dissolved oxygen in a lake so fish and other aquatic biota cannot survive;
  • excessive nutrients, such as phosphorus and nitrogen (including ammonia), can cause eutrophication, or over-fertilization of receiving waters, which can be toxic to aquatic organisms, promote excessive plant growth, reduce available oxygen, harm spawning grounds, alter habitat and lead to a decline in certain species;
  • chlorine compounds and inorganic chloramines can be toxic to aquatic invertebrates, algae and fish;
  • bacteria, viruses and disease-causing pathogens can pollute beaches and contaminate shellfish populations, leading to restrictions on human recreation, drinking water consumption and shellfish consumption;
  • metals, such as mercury, lead, cadmium, chromium and arsenic can have acute and chronic toxic effects on species.
  • other substances such as some pharmaceutical and personal care products, primarily entering the environment in wastewater effluents, may also pose threats to human health, aquatic life and wildlife.

The following is from a news item that appeared in the Toronto Sun - May 25, 2010:

Dozens of cities in the U.S. and Canada — including Vancouver, Montreal, Winnipeg, Calgary and several communities in southern Ontario — have been tested for a wide range of drugs, including legal pharmaceutical prescriptions.

The Canadian cities produce a chemical cocktail of everything from anti-epileptic drugs to psychiatric medication.

Experts say we’re just now starting to understand the impact these chemicals, that bypass most of the filtering, have on the environment. Scientists have found male fish are being horribly altered — including carrying eggs in their testes — by high levels of the female hormone estrogen.

“The question of chemicals in sewage is complex,” says William Oldham, an expert in biological wastewater treatment at the University of British Columbia. It’s now, he adds, the number one concern among those who have to deal with what we flush behind.