Findings & Recommendations for the Remediation of Historic Pesticide Contamination - Final Report March 1999
Table of Contents

IV.Remediation of Soil Contaminated by Historic Pesticide Use

A. Risk Management

      The management of health risks involves the reduction or elimination of human exposure to a contaminant. The remedial options described below reduce exposure to soil contamination resulting from pesticide residues in surface soil. While all the remedial options presented are protective, the remedial options that employ engineering controls have additional, long term requirements associated with them.

      Remedial actions that cover or contain contaminated soil can reduce risk, provided, however, that these exposure controls are maintained. If these controls are not maintained, contaminated soil can be brought to the surface. Contaminated soil brought to the surface must be properly disposed of or covered on-site.

      Current Department regulations allow for various remedies for sites with contaminated soil. The Department uses two different criteria for soil; the first are residential use remediation criteria that are appropriate for any use, without the placement of restrictions. The second soil criteria are referred to as a non-residential use remediation criteria. A deed notice is imposed at sites where non-residential criteria are applied as the remedy to ensure that the site use continues to be appropriate.

      Sites contaminated by historical pesticide use, such as farmland, can be developed for any site use, including residential use, using appropriate engineering and institutional controls. For example, one foot of clean soil as a cap with a vegetative cover to stabilize the cap and a deed notice may be sufficient at many sites. Residential use remedies can be conducted at sites by excavating and disposing of contaminated soil, replacing with clean top soil or by blending contaminated soil with clean soil from on-site or from off-site sources so that the residential use remediation criteria are met throughout the soil column.

B. Existing Regulatory Framework

      To put the report recommendations into context, the Department presented to the Task Force the following discussion of the Department’s Site Remediation Program procedures. The Site Remediation Program is charged with the identification and remediation of discharges of hazardous substances and pollutants into the environment. With the Department’s oversight, the person conducting the remediation evaluates environmental conditions at a site in relation to applicable environmental regulations.

      When remedial actions have been completed at a site, the Department issues a No Further Action Letter. The Department’s No Further Action Letter is based on an evaluation of the historical use of the site and other investigation deemed necessary to determine that no contaminants are present at the site above the Department’s residential soil cleanup criteria or that contaminants have been remediated. The No Further Action Letter describes the location of the site and the type of remediation that has occurred at a site. It is important to understand that the issuance of a No Further Action Letter does not necessarily mean that no contamination remains at the site. A situation that can result in contamination being left at a site is when the person conducting the remediation chooses to remediate the site by leaving the contamination in place and by controlling human exposure to contaminated media. Exposure control can be a physical mechanism, such as a cap of clean soil, an asphalt parking lot, or a building. Exposure can also be controlled with the imposition of an institutional control, such as a deed notice. An institutional control is a mechanism that serves to control the type and location of activities at a site.

      It should be noted that the Department does not regulate metals that are determined to be naturally occurring and therefore, it does not require their remediation. When naturally occurring metals come to the Department’s attention during the remediation of a discharge, the Department will include information about the concentrations measured at the site within the No Further Action Letter for the property owner’s and county health department’s information.

      A deed notice is required at sites where contamination remains after a remedy is implemented above the Department’s residential soil cleanup criteria. This notice ensures protection of public health, disclosure of site conditions to future owners, and maintenance of required engineering controls. See the Technical Requirements for Site Remediation N.J.A.C. 7:26E for deed notice and biennial reporting requirements.

C. Remedial Strategies

      The Task Force evaluated a wide range of possible remedial actions for reducing or eliminating human exposure to contaminated soil based upon land use. The selection of remedial options should include considerations such as site layout and construction plans. In addition, it may be appropriate to implement more than one remedial option at a site.

Remedial Option 1 - Contaminated soil can be consolidated and covered on-site under buildings, roads, or other areas approved by the Department. Contaminated topsoil may not have the appropriate physical properties to be used under some structures making engineering review of this option important. The use of grass and landscaping as an exposure control should only be allowed for as part of an exposure control strategy when approved by the Department. This option would require the filing of a deed notice.

Remedial Option 2 - Contaminated soil can be capped with clean topsoil (caps are typically one foot or more thick). It may be difficult and costly to find and test sufficient quantities of "clean" soil. See Addendum 4 for the Department’s testing protocol for "clean" soil. The term "clean" soil means that the soil does not contain any constituent/contaminant at concentrations greater than the Department’s residential soil cleanup criteria. Remedial option 2 would require the filing of a deed notice.

Remedial Option 3 - Contaminated soil can be blended with clean soil within the contaminated area (the area of concern). The area of concern is as defined in N.J.A.C. 7:26E. Blending may be done with clean soil from within or outside the area of concern to achieve concentrations at or below the Department’s residential soil cleanup criteria for all contaminants. Blending involves the physical mixing of contaminated surface soil with uncontaminated soil within a given area of concern. This strategy may not be feasible in areas of the state with high background arsenic concentrations. Blending may not be a practical option if contaminant levels are very elevated because large amounts of clean soil would be needed to achieve the cleanup criteria or if there are potential ground water impacts. This option would not require the filing of a deed notice.

Remedial Option 4 – Contaminated soil may be blended with clean soil outside the area of concern, but within the site. The site is as defined the boundaries of the real property under development. Blending may be accomplished by physically mixing contaminated soil with clean soil from within or outside the site. For arsenic, the cleanup goal is to achieve concentrations that exist in the uncontaminated areas of the site within the area of concern and across the site. For the organochlorine pesticide residues, blending outside the area of concern must achieve concentrations at or below the Department’s residential soil cleanup criteria. Blending outside the area of concern involves the physical mixing of contaminated surface soil with uncontaminated soil within the site. Blending may not be a practical option if contaminant levels are very elevated because large amounts of clean soil would be needed or if there are potential ground water impacts. This option would not require the filing of a deed notice.

      Blending represents a significant departure from Department policy but members of the Task Force agree that it may be used to mitigate risk as a practical matter, by helping reduce the cost of remediation at some sites. Blending contaminated soils with clean soil outside the area of concern could increase the concentrations of these contaminants in previously clean areas, but the concentrations will never be increased above the Department’s residential soil cleanup criteria. The Task Force accepts blending as a remedial option and acknowledges the potential for a slight increase in risk that may result from its use.

Remedial Option 5 – Contaminated soil can be removed from the site and disposed of as a waste or reused with the Department’s approval and be replaced with soil that meets the Department’s residential soil cleanup criteria. This option includes additional costs and problems associated with the handling and disposal of contaminated soil. This option would not require the filing of a deed notice.

Remedial Option 6 – The treatment of contaminated soil to the Department’s residential soil cleanup criteria is not considered to be a practicable option for a number of reasons. Treatment technologies do exist, but would be cost prohibitive in that the cost of treatment would in most cases be greater than the value of the land. Treatment technologies would be very intrusive in residential settings and the resulting soil quality would be poor and may even be unable to support vegetation without substantial amendment. If the Department’s residential soil cleanup criteria were met, this option would not require the filing of a deed notice.