PADEP Releases Draft Cap Guidance for Public Comment

June 8, 2020
Thomas M. Duncan
MGKF Special Alert

Last month, the Pennsylvania Department of Environmental Protection (PADEP) released draft guidance entitled, “The Use of Caps as Activity and Use Limitations” (Cap Guidance), with a comment period that ends on June 22, 2020.  The Cap Guidance applies solely to the use of caps in attaining an Act 2 cleanup standard, and does not apply to caps used at landfills, RCRA sites, or other non-Act 2 sites.  Caps are common components of site-specific standard remedies at Act 2 sites, especially in connection with redevelopment projects, and therefore it is critical to ensure that the design requirements, coupled with the associated inspection and maintenance requirements, are appropriate and continue to allow for feasible and cost-effective remedies. 

The Cap Guidance provides site-specific factors that must be considered when designing, constructing, and maintaining caps.  With limited exceptions, the guidance specifies that soil caps should generally consist of two feet of acceptable soil including a vegetated cover to prevent erosion and deterioration, and should not be used where slopes exceed a 3:1 horizontal-to-vertical ratio.  Specific requirements relating to pavement covers, the use of buildings or structures, and the use of gravel or stone, geomembranes, and geotextiles are also addressed.  The Cap Guidance requires consideration of how a cap’s design may influence the migration of contaminants and also provides factors to consider and recommended best practices relating to inspections and maintenance.  Finally, the Cap Guidance requires that the discovery and repair of cap disruptions must be reported to PADEP within one month of discovery. 

The extent to which the Cap Guidance is intended to apply retroactively to existing caps is currently unclear.  The draft guidance also marks the first time that PADEP has sought to impose specific requirements on capping requirements at Act 2 sites, and therefore this document may raise significant issues of concern for Act 2 projects.

For questions about the Cap Guidance please contact Tom Duncan at or 484-430-2358.