The Sea Won't Take It Away

Filling Halifax's harbour with pyritic slate is an environmental disaster hidden in plain sight

This weekend I got to read the STANTEC final report for Halifax council on dumping pyretic slate into the harbour. All those harbour infilling projects you see with your eyes but never hear about in government or media… it’s that stuff.

This is an update on an earlier article on the subject.

On May 31, 2022, Regional Council passed a motion requesting “a staff report on what the Halifax Regional Municipality, the Port of Halifax and other relevant stakeholders should undertake to situate pyritic slate disposal sites.” Notice the question was not IF, but WHERE.

Staff engaged Stantec Consulting to prepare a report on the overall issues, regulations, and alternatives for SBM management to help guide further policy planning. The report is titled ‘Sulphide-bearing Material Management Issues and Alternatives’.

Dartmouth Cove and the Northwest Arm are areas within the municipality that the City is contemplating as potential for Pyritic Slate disposal. The Stantec report provides a broad overview of SBM management and does not offer recommendations specific to these areas.

As of November 2024, Staff are reviewing the Stantec study “Sulphide-bearing Material Management Issues and Alternatives” (see linked above). A report to Council will be prepared to summarize the Stantec report contents and recommend the next steps for Council direction. Staff anticipates returning to council with this report in early 2025. More than three years, and thousands of tons of infilling later.

How did it come to this and what’s really going on?

Stone steady on mission, the Halifax Examiner ran an article a year ago this week revealing what is obvious to any of the 50,000 plus people who cross the McKay Bridge every day. Someone is filling in the harbour at Africville on an epic scale.

Does it not seem astonishing after all the years and all the fighting for Africville rights and recognition that it is now being bulldozed in and its foreshore, once a thriving local fishing ground, is being completely obliterated - undersea, on the water, and in the view planes - an aside from this article from The Examiner, not a single word of fuss is being made.

Where is the Africville movement? Where are the advocates and allies?

Were they paid off? Is this part of some larger backroom deal?

One thing is for sure. Someone somewhere must have signed off on all these harbour mega fills. But who is really qualified to do that?

When council asked staff what was really going on in 2022 the City Staff answer was to contract a consulting company to find out… and it looks like they’re still working to figure out what the consultants said.

But I can summarize the report for you!

Short version… Not much.

Longer version…

The document explores pyritic slate (sulphide-bearing material, SBM) and its environmental risks, including acid runoff that harms watersheds. Marine disposal in Halifax Harbour, a longstanding practice, is said, in theory without much evidence, data, or comparative study, to mitigate (not eliminate) acid generation but faces regulatory and public challenges. While it outlines disposal options globally and locally, it doesn’t fully address the potential environmental impacts or alternative solutions. Some gaps in cost-benefit analysis and site-specific risks could limit its conclusions.

In other words, the consultants just repeated back the questions that the Council asked in long form with bigger words.

We’ll have to watch City Staff and the new mayor and council pretty closely to see if they return to this in any meaningful way in 2025. And if they don’t it’s doubtful anyone will take responsibility for asking any questions.

The surface of the sea is still a great dividing line to a mysterious other world. The light glances off it. It’s a forbidden and foreboding place. Few among us can comprehend the post-apocalyptic wasteland that lies beneath our harbour’s waters.

We’ve filmed much of it. Here’s a short more hopeful and positive view.

Who is dumping it?

It’s one of those governmental shell games done in such a way that once the jig is up no one is going to be identified as responsible. It’s obvious that the fill is most notably pyritic slate short hauled by developers in the city and that The Port of Halifax is enabling and permitting the work. But our foreshores are among our most complicated jurisdictions. The city, the province, and the federal government all weave in and out of interests in the waterfront in such a way that no one in government is losing sleep about who is responsible.

Why does it matter?

There are two main problems with this situation and they will both be looked back on in the future as among the most major errors of our time.

First, we all agreed that one of the biggest mistakes of the last generation in Halifax is destroying the community of Africville and displacing its residents. Over the last years government and Halifax has made a BIG show of making amends: apologizing, creating a park, rebuilding the church, and generally trying to celebrate and remember what was lost. Promising not to do anything like that again. But we are doing that again. And worse. What was once a traditional fishing ground and waterfront for the Africville community is now being infilled in a dramatic way. Not even the view will be saved, let alone the actual ocean and what lies beneath. When the Africville descendants finally balk at what is happening - which will likely happen when the big giant cranes, ships, and infrastructure of the port come to tower over their little park, we will be held responsible, meaning literally legally liable for the devastation government is creating right now today.

Second, we’re not the only place dealing with pyritic slate. But we are the only place that made up fake science, which has become folklore of Halifax to justify dumping pyritic slate continuously into our own harbour in vast quantities.

Pyritic Slate Revealed

Pyritic slate, a type of rock, lurks beneath the earth’s surface with a deceptive allure. This sedimentary rock, rich in iron sulfide (pyrite), is a chameleon—its true nature hidden until exposed to the elements. Predominantly found in regions with a history of ancient marine environments, like The East Coast and parts of the United Kingdom, pyritic slate tells a tale of deep-sea sediments compressed over eons.

The Problem Emerges When Rocks and Air Collide

The tranquility of pyritic slate's underground existence is disrupted once mining brings it to the surface. Exposed to oxygen and water, a chemical reaction ensues, transforming the innocuous pyrite into a caustic concoction of sulfuric acid and iron oxide. This process, known as acid mine drainage, wreaks environmental havoc, tainting waterways with acidity and heavy metals. A silent menace, it's a stark reminder of nature's latent power.

Transport Canada (Federal Government) constructed the Halifax International Airport (HIA) near Halifax, in the late-1950s. Site location criteria were primarily; direct access to the city and a raised flat topography. Unfortunately, the site chosen was located on shallow Meguma group pyritic slate bedrock.

The initial solution to this problem was simply the idea of keeping the slate underground, covered, or underwater. The thinking was if the slate wasn’t exposed to air it would not become hazardous. This solution, given the experience of thousands of mines around the world dealing with the same problem, was unique to Halifax, wilfully naive, or intentionally corrupt. The fact is that there is air in the water and in the soil and neither will mitigate pyritic salte exposures.

In 1982, during the construction of an airport taxiway, it became very apparent that acidic run-off from excavated bedrock at the site was having a negative impact on adjacent aquatic habitat. The ensuing 20 years involved many efforts to rectify the acidic drainage problem with mixed results. Some of the techniques that have been implemented at HIA to address the acid rock drainage (ARD) issue include: dry covers, wet covers, wetlands, electrochemical treatment, open limestone channels, limestone gravel polishing beds, agricultural limestone application, and two hydrated lime [Ca(OH)2] addition treatment plants, the first producing low-density sludge and the new one that creates high-density sludge. Based on over 20 years of water quality monitoring data it is apparent that only certain acid drainage mitigation methods have been effective at HIA. In 2000 when the Halifax International Airport Authority took control of the operation and management of the airport, including the ARD issue, it was decided to construct a modern, high-density sludge, hydrated lime treatment system. This new $7 million system is now in operation and is achieving compliance with water quality guidelines. Due to high operating costs, a review of methods to optimize the system is being carried out. The HIA ARD problem, though minor by comparison to most mine sites, has provided unique challenges and may provide valuable insights into this urgent environmental and financial issue.

In spite of all this cost and experience the folklore of the old ‘just bury it’ solution continues to this day and you can hear almost any city councilor parrot this old saw when they are asked about the problem of pyritic slate dumping.

Saltwater Disposal: A Seemingly Simple Solution

It’s a solution that’s fast, cheap, easy, and wrong. Faced with this acidic adversary during the development boom, Halifax used the early airport thing and turned to the ocean as a means of disposal. It started in the 1960’s. The rationale is beguiling in its simplicity: vast, saltwater bodies can dilute and neutralize the acidic effluence. This practice, while seemingly straightforward, is fraught with ecological complexities. And it’s not true in bounded bodies of water where toxic materials settle before diffusing.

Aerial View of lost harbour

The solution to pollution is not dilution.

The Science

When pyritic slate is exposed to seawater, a series of chemical reactions can occur, influenced by the interaction of the pyrite (iron sulfide) in the slate with water and oxygen. Here's a breakdown of what happens:

1. Oxidation of Pyrite: Pyrite, when it comes into contact with oxygen and water, undergoes oxidation. This reaction produces sulfuric acid (H2SO4) and iron hydroxides (like Fe(OH)3) or iron oxides. In simpler terms, the pyrite reacts to form acid and rust-like substances.

2. Acidification and Metal Release: The sulfuric acid generated can lower the pH of the surrounding water, making it more acidic. This acid can also leach other heavy metals present in the slate into the seawater, potentially leading to metal pollution.

3. Dilution in Seawater: However, seawater has a vast capacity for dilution due to its volume and its inherent buffering capacity (its ability to neutralize acids). This means that the acidic and metallic pollutants from a small amount of pyritic slate might be significantly diluted in a large body of seawater, reducing their impact.

4. Impact on Marine Life and Ecosystems: Despite dilution, the introduction of acidic and metal-laden water into the marine environment can still have detrimental effects, especially if the amount of pyritic slate is large or if disposal is continuous. It can affect marine life, particularly those sensitive to changes in pH or heavy metal concentrations.

5. Potential Long-term Environmental Impact: The long-term environmental impact depends on various factors, including the amount of pyritic slate introduced, the rate of acid and metal release, the ocean currents, and the local marine ecosystem's resilience. Over time, continuous disposal can lead to cumulative effects that might be more significant.

In summary, while the immediate effects of pyritic slate disposal in seawater might seem mitigated by dilution, the potential for environmental harm, particularly with continuous or large-scale disposal in confined areas, remains a concern. It highlights the need for careful consideration and management of such practices to protect marine ecosystems.

The Ripple Effect: Ecological Consequences Unfold

The immersion of pyritic slate into saltwater ecosystems is not a tale of harmless dissolution. Instead, it's a narrative of unintended consequences. The acidic runoff, albeit diluted, can still alter the delicate pH balance of marine environments; especially in the confined space of the harbour which is also brackish - mixed with fresh water from rivers and streams. These shifts can cascade into a series of ecological disruptions, impacting marine flora and fauna. The harbour bottom has been a near-apocalyptic wasteland for generations, but the resilience of waterways is astonishing, requiring really only one thing from us - to stop polluting.

Global Perspectives: Diverse Approaches to a Common Foe

The disposal of pyritic slate is a global problem, with solutions as varied as the landscapes it affects. In Appalachia, efforts focus on land reclamation and water treatment to mitigate acid mine drainage. Across the Atlantic, the United Kingdom grapples with its legacy of mining, employing regulations and rehabilitation projects. And right here in Halifax, the airport continues to invest in new ideas along with careful measurement and monitoring. Each approach reflects a unique blend of geographical, environmental, and cultural factors.

Caution and Hope

The story of pyritic slate dumped at Africville, from its silent slumber beneath the earth to its problematic presence above, is a story about our broader interaction with the natural world and our social structures. It’s a continuation of the Environmental Racism that long marked the area. It’s also ultimately an economic mistake. In economics the biggest mistake is looking at a problem and considering the impact of solutions only in the short run and only for a narrowly defined group of stakeholders. In truth, good economics, social, and environmental thinking, considers the impact of the problem for all people and in the long run.

The current mess at Africville serves as a cautionary tale of unintended consequences, reminding us of the intricate balance that governs our environment, our economy, and the duty of care we have toward all people.

Yet, within this narrative lies a thread of hope—a testament to human ingenuity and resilience in the face of environmental challenges. As we navigate this complex relationship with our planet and people, the saga of pyritic slate underscores the need for thoughtful, sustainable practices in our ongoing dialogue with the earth, the ocean, and everything in it.

We can’t continue with a mistake just because it cost a lot of money and we spent a long time making it. We just have to stop, admit there is a problem, and begin again with new goals in mind.

Meanwhile in BC. A reader pointed out that BC Hydro was charged, and ultimately fined $1.1m this year, for allowing water that had flowed over potentially Acid-producing rock to flow into the Peace River.

Post Script: I’ve continued to research the Nova Scotia government’s position on ARD. There are good people who work in government and they are well-educated and informed. I actually found this published Nova Scotia government web page that spells out the best ARD solution pretty clearly.

”The best way to prevent ARD from developing is knowing where sulphide-bearing bedrock is located and avoiding activities that expose or break it up, such as blasting, quarrying and excavating.”