Concerned resident says tar ponds recipes weren't tested
By Erin Pottie
Cape Breton Post
Mon., Oct. 20, 2008
Sydney - Several mix recipes being considered to one day cap the tar ponds have never been tested in a lab before, but are now being mixed into a portion of the site.
Marlene Kane, a local resident who has taken it upon herself to review tar ponds agency reports, said at this point the Sydney Tar Ponds Agency and its project experts should be further testing recipes, not creating new ones. Testing at the south pond is expected to begin next week.
"That's one place where you don't want to scrimp. You want to make sure you've done lots of sampling and lots of testing before you move forward (in the field)," said Kane.
At least two dozen recipes were tested in the lab. Only two of those recipes per pond are now being carried over into the field, with eight new recipes introduced and some later modified at the start of testing.
The north and south ponds, located at Ferry Street, are two contaminated areas of sediment with standing water on top.
Kane noticed some of agency's new recipes for the ponds have increased in fly ash, which came as a concern because those levels had never been tested in the lab before. But by the start of initial testing in September, those levels were reduced.
"A couple of them changed because we changed our focus more to look at the cement/ slag additives, because of the logistical problems were having in delivering the fly ash into the mix without having more of a dusting issue," said Earth Tech AECOM project director Don Shosky in a phone call from Romania.
Shosky said their company's new recipes were based on existing data. He said it appeared recipes containing lower cement additives reacted better in the field than in the lab, which was a guiding factor for increasing fly ash amounts in the first place. The decision to reduce fly ash amounts was later made with the full-scale project in mind.
Earth Tech said it did not choose further lab testing, but instead reached an agreement with the Nova Scotia Department of Environment to proceed in the field.
"They're flying off the seat of their pants," said Kane of the changes to the recipes.
She said the agency's pilot-scale goal was to further test recipes in the field. She believes testing new recipes, even those containing varying amounts of the same ingredients, do not fit within their objective.
Kane is also upset with the testing zones, saying the whole tar ponds have wide variations, and those two sites with the ponds are not representative of the whole area. She pointed out comments from Environment Canada in a report issued to Earth Tech from July 6, 2007. The comments state that given the heterogeneity or diversity of materials at the site, it appears questionable as to whether the sample is representative.
Environment Canada recommended Earth Tech conduct a verification testing program as a follow-up to lab testing study before moving into the field.
"All issues pertaining to performance criteria and testing, as well as recipes, should be sorted out at the bench-scale level of testing. The goal of the pilot-scale (field testing) study should primarily be to verify the constructability of the project using the methods and equipment intended for the full-scale project," Environment Canada officials commented.
Earth Tech said the area presents challenges due to the heterogeneity of the site.
"Yes, it's true. But through the mixing process ... that material gets all blended together with the various concentrations of additives, particularly the slag, which acted as an abrasive to break apart the tar and the sediments so they could be mixed more freely," said Shosky.
Terry MacPherson, senior manager of the Sydney Tar Ponds Cleanup Regulatory Branch, Environmental Monitoring and Compliance Division with the provincial environment department, said the branch has been "pretty careful" in looking at what the agency is giving them.
"The language in the approval (issued Jan. 2007) simply staged their work.
We are doing an assessment on the recipes based on the performance criteria and so they were to do most of their work starting off in the lab, or treatability studies," MacPherson said. "We were not necessarily prescriptive, even the day of the pilot-work that is being done. That if they modified a recipe, we weren't going to stop them because - whether it's in a pilot or field test versus the lab setting - they're still simply evaluating the different recipes against the material that's in the ponds."
Kane is also asking why the strength tests for the tar ponds cap recipes are only being conducted up to 28 days. Recipes for the cooling pond were tested up to 50 days. She is also concerned one of the recipes got weaker by the 28th day.