Connecticut Department of Energy & Environmental Protection

General Guidance on Development of Former Agricultural Properties

The Department of Energy & Environmental Protection has become aware of a number of site development projects on former agricultural land in which persistent pesticides (primarily dieldrin, DDT and breakdown products, chlordane, arsenic) remain in soil at concentrations that approach or exceed the Connecticut Release-Based Cleanup Regulations (RBCRs) criteria. While such development projects do not specifically fall under the RBCRs, concerns have been raised that the residual pesticides constitute a health risk. In light of this, DEEP offers general guidance for such sites as described below. This guidance is meant to provide an approach that is protective of public health and that also leaves a degree of flexibility. We expect municipal officials and site developers to consider our input together with other factors in deciding how best to handle site re-development projects.

  1. Evaluate site history and sample surface soil (ideally 0-3 inches depth) in areas where pesticides had been applied, handled, and stored. A limited number of deeper samples are also recommended, particularly in areas of soil staining and at storage and handling areas. Total mass concentrations and leaching tests should be performed, with consideration given to analyses for newer pesticides if the site had been used for agricultural purposes in recent years.
  2. If higher levels are found in areas where pesticides were handled or stored, in deeper soils, or in areas with staining, this indicates that pesticides were spilled, not applied, which must be reported as an existing release in REACT and remediated under the RBCRs.
  3. Evaluate detected pesticide concentrations against RBCR Direct Exposure Criteria [Appendices 2 (ResDEC), 11 (MMF DEC), and 12 (PR DEC)] for the planned use of the site. If the concentrations are below the RBCR criteria in all cases, there is no need for further consideration of pesticide contaminant issues at the site. If some concentrations in application areas are above RBCR criteria, the following options for managing the affected soil should be considered:
  • Keep affected soil separate from other soils and use it on-site as fill under buildings, parking lots, or access roads or dispose of the soil in an approved landfill off-site.
  • Mix it with unaffected soils to decrease the effective soil concentration. In this case, representative samples should be taken from the mixed soil piles following RCRA protocols regarding the number and location of samples from soil piles. If the mixed concentrations are below the RBCRs, the soil pile can then be used anywhere on-site. If the mixed concentrations are still above RBCR criteria, then the soil pile could be used as fill material below grade (but not topsoil) in parts of the site where digging will not occur (i.e., areas where children will not play; non-residential areas; uses as described in the first bullet.
  • If affected soils are in some manner kept on-site, an additional precautionary step would be post-construction surface soil sampling to ensure that the practices described above have successfully reduced the potential for direct exposure.
  • If any soils containing pesticides above RBCR criteria remain on-site, it is prudent to record the location of those affected soils on a site map and provide that map to the local health department and DEEP.

Site-specific data can be provided to DEEP (860-424-3705) to make sure that a particular site does not present unique risks and that the data are suitable for comparing against RSR values.

 

Content Last Updated: October 16, 2026