Cement recipes next on list for tar ponds
By Tanya Collier Macdonald
Cape Breton Post
Mon., Mar. 12, 2007
SYDNEY - Tenders to solidify and keep toxic tar pond sludge from
travelling should be ready in September, says the engineering
company hired to manage the project.
Earth Tech will identify three cement recipes that offer the best
unconfined compressive strength, says Joe Sullivan, Earth Tech
project manager. Those mixes will be tested at the tar ponds in May.
Concurrently, the engineering firm will meet with Nova Scotia
Department of Environment and Labour to get proper approvals and
permits needed before work begins.
The effort builds on bench-scale testing program completed by
Jacques Whitford in May, 2006. At that time, samples were taken from
the south pond to identify which mix would be suitable for the
During that program, engineers tested portland cement, fly ash from
Lingan Generating Station and slag from Sysco. The report shows that
all mix designs met the minimum unconfined compressive strength
requirement. However, the mixture using 15 per cent of portland
cement mix was the only one that met the hydraulic conductivity
performance criteria, which will work to prevent groundwater from
moving through the cement. Sysco slag is also proving to be