“Aerosolizing” Landfill Leachate

May 19, 2017.   A bill under consideration by the N.C. General Assembly,   House Bill 576 , requires the Department of Environmental Quality (DEQ) to allow “aerosolization of leachate and wastewater as an acceptable method of site management” at a lined municipal solid waste landfill and gives DEQ discretion to allow the practice at unlined landfills.  The bill passed the N.C. House and has been sent to the Senate.

A definition of terms.

“Leachate” is the liquid produced by water (including rainfall) percolating through landfilled waste. State rules require landfills to contain leachate onsite or treat the leachate before discharging it.   Treatment may occur onsite; offsite through a municipal wastewater treatment system; or by land-application of leachate to vegetation.  Since leachate would be considered to be wastewater, discharge often requires a Clean Water Act permit.

“Municipal solid waste landfill”  means a landfill — whether operated by a city, a county or a private waste management company — that receives household trash and  other commercial and industrial waste collected for disposal. MSW landfills do not dispose of hazardous waste or medical waste generated by diagnosis, treatment and  research facilities.

“Aerosolization”  involves spraying untreated landfill leachate into the air, allowing solids to resettle and  liquids to evaporate. Land-application systems direct leachate toward the ground for absorption by vegetation;  aerosolization systems direct the leachate high into the air to facilitate evaporation.   In 2016,  Republic Services (a major commercial landfill operator in the state)  made a presentation to the legislature’s Environmental Review Commission describing aerosolization and promoting the systems as a less expensive alternative to both conventional wastewater treatment and land application of leachate.

Scope of the bill. House Bill 576 requires DEQ to allow aerosolization of leachate at lined municipal solid waste landfills and allows DEQ to approve  aerosolization of leachate at unlined landfills.  The bill sets no standards for aerosolization of landfill leachate and does not expressly give either DEQ or the Environmental Management Commission authority to set standards for the practice. The bill also waives water and air quality permitting requirements for the aerosolization system if evaporation  of leachate “results in a zero-liquid discharge and is not a significant air contamination source”.

Questions:

1. Does aerosolization  of untreated landfill leachate from municipal solid waste landfills present a risk of exposure to  viruses and bacteria?    Unlike limited purpose landfills (such as those receiving only construction and demolition debris),  municipal solid waste (“MSW”) landfills receive food waste, diapers, and other personal care products that may carry viruses and bacteria. There does not seem to be readily available  information on  the potential for increased human or wildlife  exposure to viruses and bacteria as leachate becomes aerosolized and potentially wind-borne.

Without more information on the persistence of viruses and bacteria under different conditions, it is difficult to assess the risk of aerosolizing MSW leachate and develop management measures to limit the risk.  An EPA study found that viruses can survive in landfill leachate for weeks or months in moderate temperatures. A Nebraska study found that avian influenza viruses may survive in landfill leachate for up to two years.

North Carolina’s Division of Waste Management has approved four demonstration  projects for aerosolization of  landfill leachate; one involved a small-scale project at a Republic Services landfill.  The process has not been used to scale at a MSW landfill in North Carolina and  I have not found an instance of any other state permitting an evaporation system at a MSW landfill. As a result, data on the potential health risk of  aerosolizing MSW leachate either doesn’t exist or is not readily accessible.

2. Are existing  state rules sufficient to manage risk associated with aerosolization of MSW leachate?  North Carolina’s landfill rules require  a 50-foot buffer between each waste disposal area and the landfill property boundary. Rules that apply to landfills permitted before 2007 require a 50-foot buffer between waste disposal areas and a river or stream.  Landfills permitted since 2007 must maintain a  200-foot buffer between the waste disposal area and a perennial stream or wetland, although DEQ  can approve a narrower buffer (no less than 100 feet) based on local circumstances. See Session Law 2007-550.  A  500-foot buffer must be maintained between the waste disposal area and a home or water supply well.

A 2016  presentation  on leachate management by SCS Engineering noted some considerations in use of evaporation systems including:

♦ Risk of overspray and wind gusts

♦ Worker exposure to aerosolized leachate

North Carolina’s  waste management rules do not address these concerns and the potential risk to landfill workers or to people and wildlife beyond the landfill boundary.  Existing landfill buffer requirements were developed to manage the impact of buried waste and active landfill operations on waters, wetlands and adjoining property owners — not as a safety factor for aerosolization of landfill leachate and possible drift.

State  waste management rules require landfills to comply with air quality standards,  but the cross-referenced standards focus on air pollutants regulated under the Clean Air Act rather than bacteria and viruses. House Bill 576 exempts aerosolization systems from air quality permitting requirements as long as the system would not be a “significant air contamination source”. The bill does not define what would constitute a “significant” air contamination source.

The  knowledge gaps, lack of risk management guidance, and absence of standards for use of evaporation systems at municipal solid waste landfills suggests a need for  more study.

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