Dredging of Onondaga Lake was completed in November 2014, a year ahead of schedule. Covering and capping the consolidation area began in spring 2015 to permanently isolate drying lake material. The cap will consist of layers of soil, a plastic liner sealed around the entire perimeter, and additional protective layers of soil and vegetation. An initial layer of soil, with an average thickness of four feet deep, has been placed over the entire consolidation area. Beginning in spring 2016, a polyethylene liner and additional layers of soil will be put in place to permanently encapsulate the geotextile tubes. The top will be planted with vegetation. The project is scheduled to be completed in 2016.
System Designed to Protect Air Quality and Minimize Odors; Air Monitoring Results Significantly Below State-Established Site Criteria
Honeywell is undertaking the Onondaga Lake cleanup under the supervision, and at the direction of, federal and state regulatory agencies.
A key part of the cleanup is the Community Health and Safety Plan, which was reviewed by the New York State Department of Environmental Conservation (DEC), the U.S. Environmental Protection Agency (EPA), and the New York State Department of Health (DOH), and approved by DEC.
In June 2010, EPA released its human health risk assessment, which looked at “potential health impacts to people who live near the facility which will contain sediments removed from the lake and determined that all resulting risk and hazard estimates were within the range or below levels identified by EPA as acceptable.”
According to DEC, “total VOC levels detected at the perimeter monitoring locations comply with the standard established for protecting public health.”
Even though the potential for odors has been greatly reduced because dredging is complete, Honeywell has maintained odor control measures, where appropriate. Sealant was reapplied as appropriate to the drying geotube bags, misting systems operated, and large fans run depending on wind direction, wind speed, and weather conditions such as temperature and precipitation.
Water storage basins have been cleaned and are no longer used to hold water from drying bags.
Air Quality Monitoring Protects Health and Safety
Real-time, short-term air monitoring data is submitted to the agencies on a daily basis during construction activities. In addition, Honeywell has an air monitoring team that investigates air quality at the work site. The Community Health and Safety Plan is available at: lakecleanup.com and www.dec.ny.gov.
Air monitoring is conducted to ensure that levels remain below established government criteria for the site. Results are collected in real time. To provide an additional level of protection and ensure that the criteria are not reached, Honeywell set an even lower level for early warning. If this lower level is reached, it immediately triggers notification to a technician. An evaluation would be conducted, the emission source(s) identified, and operations closely watched to determine if controls are necessary. If the government criteria are reached, operations related to the source(s) would be restricted or stopped until the work is reassessed.
In 2016, under the direction of DEC, real-time, short-term air monitoring has taken place during construction activities. Short-term air monitoring is now complete for the season. Long-term air monitoring remains active throughout the winter months, consistent with the Community Health and Safety Plan.
Operations Continuously Improved in 2012, 2013, and 2014
Over the course of dredging activities, Honeywell looked to continuously improve operations to minimize, to the extent possible, potential off-site odors. Several actions were taken to improve odor controls.
In September 2012, we took the following actions to improve odor controls:
- Installed the misting system
- Significantly reduced temporary standing water in the active water basin
- Installed a cover system for active work areas in the water basin
- Enhanced the capture of vapors from the thickeners by installing a stand-alone carbon filtration system
- Covered geotextile bags with plastic when full. (This practice was superseded by a more effective covering process developed in 2013.)
Although these mitigation measures were effective, fall 2012 and winter 2013 some odors were reported. While air quality at the work site perimeter continued to comply with the standards established for protecting public health, DEC and Honeywell worked with engineers, scientists, and odor experts from across the country during the winter to identify additional measures to further reduce the potential for odors.
In 2013, the following additional measures were deployed:
- Substantial upgrades to geotube cover system:
- An alternative cover system was developed that is integrated into the geotubes’ manufacturing process. A prototype was successfully tested, and unused geotubes were sent back to the manufacturer for retrofitting
- Covers over channels between the geotubes
- Applying a sealant on drying geotube bags to more effectively minimize emissions and improve worker safety by reducing the potential for worker slips, trips and falls on site
- Enhanced water management to reduce the flow of water to the geotubes
- Improvement and expansion of the misting system to intercept potential odors
- Containment during transportation and stockpiling of oversized material to reduce potential odors
- Windscreens to enhance the performance of the misting systems by interrupting airflow from the sediment dewatering area
- Installed fans along the northern work site perimeter to increase air flow
Building on the system upgrades, which were implemented in the previous dredging seasons and proven to be effective, DEC and Honeywell continued evaluating additional measures to further reduce potential odors.
In 2014, the following additional measures were deployed:
- Installing additional fans along the western work site perimeter
- Increasing the height of the misting system along the western work site perimeter