Australian Concrete Protects City and Waterways Against Poisonous Leachate.

CEMENTAID EVERDURE CALTITE SYSTEM
Landfill Retaining Wall & Leachate Barrier
Redhill Creek, Hamilton, Canada.
PROJECT OWNER: City of Hamilton, Ontario, Canada

In the early 1950's, a large landfill / garbage dump adjacent to Redhill Creek in Hamilton Ontario, had been opened to serve the needs of the City Hamilton and it's residents In the 60's it was closed and capped..

After more than 10 years of active operation, and 40 years since capping, poisonous leachate from both the industrial and domestic waste had accumulated within the fill, and threatened to seriously contaminate the natural groundwater.

The leachate is considered to be very toxic and unless contained / prevented from entering the groundwater and draining into the adjacent creek Lake Ontario, could pose a significant hazard to the health & safety of the City's residents as well as to the surrounding environment. The decision was taken by the City to construct a retaining wall leachate barrier to provide a long-term solution. However, the retaining wall / leachate barrier structure itself would need to be fully waterproof, AND resistant to the corrosive effects of the leachate.

Conventional membrane-type barriers as used in the past were not considered suitable, not only due to the risk of damage, but also because several of the potential leachate contaminants (e.g. acids, toluene, etc.) are likely to destroy the membranes themselves. Normal absorptive concrete on the other hand, would also be subject to corrosion attack & degradation by organic acids and other leachate contaminants being drawn into the concrete by capillary forces..

Working together with consulting engineering firm McCormick Rankin, the City of Hamilton specified the concrete to incorporate "Everdure CALTITE", a time-proven Hydrophobic Pore-blocking Ingredient with a more than 45-year track record of corrosion-free service under some of the world's most severely corrosive environments. "CALTITE" reverses the normal capillary "wicking" or absorptive action in concrete, producing instead concrete with a uniformly Hydrophobic MatrixT as well as capillary pore-blocking components, which actively expel water and any contained salts or acids and prevent their re-entry. The interior of CALTITE concrete remains DRY in-service, and so unaffected by acids or salts in contact with it. The action of acids is confined to only the extreme outer surface, where only insignificant wear can occur.

The structure itself is in effect a caisson wall with reinforced concrete facing.  The "caissons" are all 39" (1.5m) in diameter, augured into bed rock 15 - 18m from the surface. There are 2 different mix designs for the piled wall structure, the first being a 6mpa mix - mostly a high sand mortar type mix.  These piles were augured into place first, and then the "King Piles", using a 35mpa conventional mix, were augured between the "fillers". A steel cage for the "tie backs" was placed in the king pile casing before filling with concrete.  The face of both piles is cut back by the action of removing the garbage. FInally a 35mpa reinforced Caltite concrete wall of 350mm minimum thickness is to be cast as facing.

The Everdure Caltite ingredient is added to the concrete during batching at the rate of 30 Litres/m3, to replace an equal amount of batch water. The fully waterproofed and corrosion-proofed concrete arrives at the site ready to pour, place and forget!

Dufferin Construction is the Contractor, Dufferin Concrete the Concrete Supplier and Bermingham Construction the Piling Contractor. With a final total of approx. 1,200cu.m of Caltite concrete to place, work commenced in late 2004, with completion anticipated by August 2005.