Posted by: fluoride | September 22, 2010

Solidification and Stabilization COVERUP

*  See latest pictures – Tar Ponds flood during SS – December 2010

See latest videos at   (2010)   (2011)   (2011)

*  See another video below

The North and South Tar Ponds, located in downtown Sydney, N.S., is a tidal estuary which flows into Sydney Harbour.  This estuary contains approximately 700,000 tonnes of sludge contaminated with PCBs, PAHs, semi-volatiles, metals (lead, mercury, arsenic, cadmium, etc.) petroleum hydrocarbons, BTEX, HNCs and dioxins/furans.

This contamination was responsible for the indefinite closure of the lobster fishery in the South Arm of Sydney Harbour in 1982 when fisheries scientists found PAHs from the Tar Ponds in Sydney Harbour lobsters.

Despite a recommendation in a report commissioned by government in 1994 to immediately install a weir at the mouth of the North Pond to eliminate tidal flushing which would then reduce the flow of contaminated sediments to the harbour, government did nothing.  Twelve years later,  in 2006, a barrier was constructed across the mouth of the North Pond “to protect Sydney Harbour from further pollution as the big cleanup proceeds.”  A 50-metre opening was left in the barrier to accommodate a water channel which will run through the Tar Ponds by 2014.

Government’s plan, now underway, to remediate the tar ponds has been promoted as a ‘cleanup’.  It consists of mixing over 100,000 tonnes of dry cement powder into 700,000 tonnes of toxic waste insitu using an excavator.   All of this contamination will be buried in place and capped.

We call this plan a COVERUP as not one molecule of contamination will be cleaned up, including 50,000 tonnes of PCB-impacted sediments.

This crude process of mixing cement powder with hazardous waste is called Solidification and Stabilization (SS) and its purpose is to provide increased structural strength for capping and to decrease the mobility of contaminants. However, concerns have been raised regarding its long term efficacy as well as its effectiveness on organic sediments.  The problem is that the tar ponds sediment is high in organics.

Will this mixing of cement powder with tar ponds sludge turn into a low permeable concrete mass as described by the Sydney Tar Ponds Agency?

Nowhere close to concrete.  The unconfined compressive strength (UCS) of sidewalk concrete is about 3500 pounds per square inch (psi)The minimum UCS requirement for the toxic waste in the tar ponds following SS is a mere 25 psi, reduced from 50 psi, and some areas have already failed to meet that minimum requirement following SS.    We’ve also seen instances where the UCS gets weaker over time instead of stronger.  Unfortunately, due to the Nova Scotia Environment Department’s lax criteria, the UCS need only be tested once and never again, so if there is a weakening trend and/or degradation of this SS toxic waste, we’ll never know, especially once it’s buried under a cap comprised of one million tonnes of trucked-in materials.

Some test results have also shown an increase in contaminant leaching instead of a decrease following SS of this hazardous waste, and some contaminants not leaching prior to SS began leaching following SS.  To accommodate this increase in contaminant leaching, the N.S. Environment Department allows the leachate following SS treatment to be 500 times greater than the leachate before SS treatment, providing it doesn’t exceed site criteria.  So while the purpose of SS is to reduce contaminant leaching, it’s actually having the opposite effect on some contaminants in this high-organic sludge.  To make matters worse, the NSE department only requires there be one leachate test for every one thousand  tonnes of SS treated sludge. To put that number in perspective, that works out to be one leachate test for every 66 dump trucks (15 tons each) full of toxic waste. Far from being protective.

Following an extensive government-led consultation process with the community, from 1996 to 2003, to determine acceptable solutions for the remediation of the Tar Ponds and Coke Ovens sites, the community called for removal and destruction technologies to clean up the sites once and for all.  This solution was completely ignored by governments and they are now proceeding to waste hundreds of millions of dollars in a ‘cleanup’ that cleans up nothing.

View the video below to see how this COVERUP is carried out.


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