Old Landfills
Leachate Management 2006
Tompkins County is required by New York State and Federal law to provide post-closure monitoring and maintenance at the Hillview and Caswell Road facilities. The Hillview facility operated from 1970-1992. capping activities were conducted in 3-phases.
- Phase I occurred in 1989,
- Phase II in 1992-93 and
- Phase III in 1996.
In total over 35 acres of landfill capping was installed during the 3 phases. The cost to complete capping activities at Hillview are in excess of 6 million dollars.
The Caswell Road facility began operation in 1970 and closed operations in 1985. Construction activities to cap the landfill occurred during 1986-87. Approximately 32 acres of landfill cap were constructed at a cost of approximately 4 million dollars.
The landfill cap at Hillview consists of 3-1/2 fee of constructed said materials, 1 foot gas vent material, 2 feet barrier protection, ½ foot top soil and a 40 mil geo membrane moisture layer.
The landfill cap at Caswell is composed of 18-inches of low-permeability clay and 6-inches of topsoil.
The monitoring network at Hillview is comprised of 32 sites. At Caswell the monitoring consists of 18 monitoring points.
The largest post-closure expense at the landfills is leachate management. Leachate, or the liquid that has percolated through a landfill, is collected at both facilities in a perimeter collection system. The leachate is then conveyed to on-site storage tanks. A private trucking company under contract to the County services the leachate tanks.
The leachate is transported to the Ithaca Area Wastewater Treatment Plant for proper treatment. Hauling costs currently are $28.55/1000 gals and treatment costs are $6.00/1000 gals. In 2006 expenses for this service totaled $39,000 compared to $40,000 for 2004.
Several times since closure completion at Caswell there have been areas of cap settlement that required filling. In 2002 a phased capital project, Phase I, was started at the Caswell site costing approximately $650,000, was completed to address surface water drainage off the cap and replacement of the original leachate collection system. The cap enhancement covered about 8 acres of the landfill cap. These areas were filled and graded to promote positive drainage of surface water off the cap. Several surface water drainage swales were constructed on the landfill surface to further promote surface water drainage off the cap.
The existing leachate collection system was replaced to address several deficiencies in its effectiveness since the original placement of the system. In many places the pipe was far away from the landfill foot print and was under or in close proximity to surface water swales. The new collection system was moved so that it would collect more leachate and less surface water.
As a result of the improvements, the volume of leachate collected was reduced approximately 70% for an annual savings of $80,000.
Phase II of this landfall leachate management study will investigate various options to manage the leachate captured. Currently leachate is pumped onto tractor-trailer tanks and trucked to the Ithaca Wastewater Treatment Plant. Options evaluated include filtering technologies, on-site wetland treatment as well as conventional on-site treatment (i.e. package plant). This work will be conducted over the course of the coming year.
