CANANDAIGUA — A consulting firm hired by Ontario County to analyze the odor mitigation report issued by a Casella Waste Services consultant is mostly in agreement with the report.
However, SCS Engineers do disagree in some areas and make their own recommendations.
The two reports — from SCS and Civil and Environmental Consultants — now will by read and questions prepared by members of the Board of Supervisors Planning and Environmental Quality Committee, which met Monday. The questions and observations will be addressed by county staff and if significant enough, representatives of the two consulting firms will be asked to return for questioning and clarification.
CEC was hired by Casella, operator of the landfill for the county. In the firm’s report, it said that the major source of off-site landfill odors at the Ontario County Landfill are landfill gas, primarily emanating from the active Stage 9-C1 waste disposal area that accepted waste from January 2018 to March 2019. The area took in a high percentage of biosolids from wastewater treatment plants as sludge and had a limited number of gas collection systems.
CEC said since waste disposal has moved to the Stage 9-C2 area, allowing for upgrades to the gas collection and extraction system. It also moved waste disposal from a high point on the landfill working face to a low point where it is less impacted by winds.
CEC officials said the landfill’s increased acceptance of biosolids in recent months — since reduced — has contributed to the odors’ intensity. In 2018, biosolids accepted at the landfill as a percentage of total waste was 14.1 percent. In November 2018, that rose to 35 percent. Construction and demolition waste deposited at the landfill also contributed the odors.
CEC made four major recommendations:
• Installing an interim temporary geomembrane liner on the exposed east side slopes, which would have an immediate impact on the control of emissions and odors.
• The timely installation of additional horizontal landfill gas collector trenches and odor extraction wells on exposed side slopes and non-capped areas with closer spacing. The de-watering of landfill liquids and installation of a leachate storage tank also are recommended.
• Significantly reducing the amount of wastewater treatment plant biosolids.
• Requiring wastewater treatment plants to pre-treat biosolids before taking them to the landfill. That can be done by adding calcium oxide or lime and calcium hydroxide, delaying the generation of sulfur compounds.
CEC also recommended numerous operational modifications they said would help reduce odors.
SCS agreed with the recommendation to more aggressively install temporary geomembrane covers. But their recommendation to more aggressively install final cover systems was removed from the report by CEC, SCS noted. The company recommended that biosolids acceptance be limited to a total number of tons per year, independent of the total annual waste placed in the landfill. They also agreed with DEC on pre-treatment of the biosolids.
SCS also said those trained to respond to odor complaints should be better trained and should use a field olfactometer.