New testing shows that Chittenden Solid Waste District’s herbicide-tainted Green Mountain Compost may contain only one, and possibly two, herbicides. Also, it appears that reimbursements to customers will be less than the $1 million initially estimated.
In July, the CSWD recalled thousands of cubic yards of compost that contained traces of herbicides — under 16 parts per billion — that stunted some vegetable plants. Because the concentration of herbicides is so small, health effects on humans is not a concern.
More extensive and finely tuned testing by several independent national labs and by Dow AgroSciences has shown only one herbicide, clopyralid, definitely present, while aminopyralid, an herbicide which breaks down even more quickly than clopyralid, possibly present. Both are considered “reduced risk herbicides” because their toxicity is so low.
Earlier testing had indicated the presence of picloram and DuPont’s Imprelis (aminocyclopyrachlor). Cary Giguere of the Vermont Agency of Agriculture’s pesticide division says both turned out to be false positives.
Now that the Sept. 30 deadline for customers to apply for refunds has passed, it appears the district will be dealing with costs much lower than the $1 million initially estimated. CSWD has paid approximately $333,000 to customers who had documented damage from the compost.
“Most people took the standard offer,” Tom Moreau, CSWD’s general manager reports.
That was $100 per cubic yard or $8 a bag and delivery costs if those were involved. Customers had to provide receipts and field investigators established that plants were damaged. In the case of one business, where multiple client gardens were affected, CSWD paid out an additional sum for labor and related costs. Customers who had amended their gardens with GMC compost have been offered oat seeds to plant this fall as a way of monitoring the effects of contamination.
Green Mountain Compost, which will have a greenhouse of its own by next month, has been using a University of Vermont greenhouse for plant growth tests on old compost, with the goal of determining how long it takes to fully break down the persistent herbicide residues. The CWDS has 6,500 cubic yards of this year’s compost remaining.
“If the culprit turns out to be aminopyralid, then perhaps after the second set of growth trials — November through January — we will feel comfortable selling it at some sort of ‘lawn sale,’” said Moreau, adding “that’s a pun for selling it for lawn use only.”
But even if the compost is sold to fertilize lawns rather than gardens next spring that still leaves the CSWD with a shortfall in income from the $2.3 million invested in the Williston facility in 2011. An insurance claim has been turned down by the Vermont League of Cities and Towns, though that is being appealed.
“As for new, non-exposed compost that we are making without horse manure, we should have the first batch available in June 2013 — perhaps a thousand yards,” says Moreau, adding that it will be sold only after both a reliable chemical analysis and growth tests have been done, which won’t be until late this winter. There is unlikely to be much bagged material for sale next spring.
For the future, compost will be made from chicken rather than horse manure and go through a cooler, slower process that should allow, as it has at other composting facilities in Vermont, the breakdown of any persistent herbicides and the survival of the mesophilic bacteria that a hotter process kills. The new greenhouse will be used for regular bio-assays of both feedstocks like manure that have been a source of herbicides and the compost as it matures.
Compost from other facilities which may use horse manure, the apparent source of most of the clopyralid — whose original source is animal feed — has not led to stunting of beans, peas, tomatoes, peppers and related plants just as they begin to flower.
