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Rapid Landfill Assessment


Prior to the establishment of the State and Federal PinelandsLandfill in the Pinelands Protection standards, more than 60 sanitary landfills operated in the million-acre Pinelands Area.  With only one exception, all of these facilities ceased operations on or after January 1981 at the direction of the New Jersey Department of Environmental Protection (NJDEP) and as a result of the implementation of the Pinelands Comprehensive Management Plan (CMP).  The Cape May County Municipal Utilities Authority’s Landfill is the only exception to NJDEP’s landfill closure directive. It currently operates under NJDEP oversight and is equipped with leachate collection, gas venting and impermeable capping systems.

The Pinelands CMP requires that landfills that ceased operation on or after January 1981 be permanently covered with an impermeable cap. An impermeable landfill cap prevents stormwater from percolating into the buried refuse, thereby significantly reducing the discharge of landfill leachate into ground water and nearby surface water bodies.

The CMP does not require an impermeable cap on landfills that accepted only vegetative or construction waste, on landfills that are not generating a leachate plume, or on landfills where the public health and ecological risks associated with landfill leachate may be addresses by an equally protective remedial alternative.

To date, very few Pinelands Area landfills have been impermeably capped. In an effort to gain a better understanding of the potential impact that uncapped landfills might be having on Pinelands natural resources and to prioritize remedial actions, in 2010 the Commission staff conducted a proof-of-concept exercise using existing landfill monitoring well data in conjunction with GIS land feature data.

Through this exercise, Commission staff compared concentrations of leachate constituents detected in groundwater surrounding specific landfills to various regulatory standards.  Using existing GIS data layers, staff then established the distance from the landfill boundaries to potential leachate receptors. including wetlands, surface waters, and potential drinking-water well sites. After demonstrating the usefulness of this approach to rapidly assess and rank the relative cause for concern at each landfill, the Commission contracted with the United States Geological Survey (USGS) to refine the landfill screening process, incorporate solute transport modeling to estimate potential contaminant concentrations at receptors and apply the approach to each of the uncapped Pinelands Area landfills.

Screening Tool to Evaluate the Vulnerability of Down-gradient Receptors to Groundwater Contaminates from Uncapped Landfills

In cooperation with the Pinelands Commission, research hydrologists at the USGS New Jersey Water Science Center developed a screening tool that quantifies the level of concern posed by contaminants from landfills lacking leachate reduction and containment controls.

Completed in 2014, the screening tool uses a modified spreadsheet version of the Quick Domenico Multi-scenario (QDM) solute transport model to estimate concentrations of contaminants reaching receptors under steady-state conditions. The screening tool uses the QDM results to categorize landfills as having high, moderate and low levels of concern based on contaminant concentrations reaching receptors relative to regulatory standards.

The Quick Domenico Multi-scenario solute transport model is described in two Powerpoint presentations: USGS Presentation June 2014.pdf and Pinelands Brookhaven Landfill Presentation Oct.pdf.

Important attributes of the model:

- Allows the use of existing (historic and contemporaneous) groundwater monitoring well data collected pursuant to existing New Jersey Pollutant Discharge Elimination System program (NJPDES) monitoring requirements, eliminating the need for new wells and additional analyses.

- Uses existing GIS data layers to identify the location of landfill boundaries, wetlands, surface water bodies and potential sites of drinking water wells, eliminating the need for ground level surveys. 

- Uses existing published aquifer hydrological and geochemical parameter values, eliminating the need for site specific geophysical studies.

- Runs as a spreadsheet application to provide ease of use with limited need for data inputs and parameter-value requirements. 

- Domenico-based models are supported by the U.S. Environmental Protection Agency where contaminant transport is advection-dominated and not dispersion-dominated as is applicable to the highly permeable porous media that comprises the Kirkwood-Cohansey aquifer.

- Model inputs for landfill geometry, aquifer hydrologic and geochemical properties, and leachate constituent concentrations can be modified by the user based upon newly-acquired data and site specific analysis. 

Next Steps

The Commission staff has summarized and categorized the level of concern attributable to each of the Pinelands Area landfills for which landfill monitoring well data was available from NJDEP.

The summary table is shown here.

Out of an abundance of caution, a high level of concern was attributed to Pinelands Area landfills for which no data was available at NJDEP.

Beginning in 2015, the Commission will advise those municipalities in which a landfill with a high or moderate level of concern is located of the results of the USGS’s screening level assessment, for local follow-up. These municipalities are encouraged to work with their local/county health officials to first determine if areas identified with high or moderate levels of concern for drinking water wells are served by onsite wells or are instead served by public water systems. The GIS coverages used in the screening level assessment do not differentiate between onsite and public water systems.

If it is determined that drinking water wells are present, the local/county officials will be encouraged to take action to ensure that the owners of any such wells are appropriately notified so that they might have their wells tested for any analyte that was determined to cause a high or moderate level of concern, or more broadly, for constituents recommended by NJDEP or the local health department.

With respect to ecological concerns, where a landfill with a "high" or "moderate" level of concern was identified based upon NJDEP landfill monitoring well data and the USGS landfill screening tool, Commission staff will ask that municipal officials meet with Commission staff to pursue an appropriate remedial action to abate the ecological concern.

Finally, host municipalities with landfills that were categorized as representing a low level of concern will be encouraged to meet with the Commission to finalize the closure status of their landfills.

For more information about the rapid landfill assessment, please contact Environmental Technologies Coordinator Ed Wengrowski at (609) 894-7300 or