PA DEP Publishes Act 2 Cap Guideline
On March 26, 2021, the Pennsylvania Department of Environmental Protection (PA DEP) published an addendum to the Land Recycling Program Technical Guidance Manual (TGM) that provides guidance on the use of caps at Act 2 sites. The guidance is titled “The Use of Caps as Activity and Use Limitations” (Cap Guidance) and is included as Appendix II-A of the TGM. While the use of caps for pathway elimination has been a part of Act 2 since its inception, this is the first time that PA DEP has issued any written formal guidance. The Cap Guidance is only applicable to attaining a standard under Act 2 and is not applicable to non-Act 2 sites or programs (solid waste [landfills], Resource Conservation and Recovery Act [RCRA] sites, or other remediation programs).
A cap is defined as a barrier over contaminated media that eliminates an exposure pathway or controls contaminant migration. Caps are generally used to address contamination at concentrations resulting in unacceptable risk. There are three general situations for which caps are used: protection from direct contact to contaminated soil; prevention or the reduction of the migration of contamination throughout the subsurface (vapor intrusion, contaminant migration from water infiltration); and prevention of contaminant migration to surface water by means of stormwater runoff.
The Cap Guidance addresses various cap materials, including soil, pavement, building or structures, and other materials (gravel or stone, geomembranes, and geotextiles). Depending on the intended use of the cap and the capping material, the Cap Guidance provides site‑specific factors to be considered during design, construction, and maintenance of the cap. The site-specific guidance is divided into two general categories: Protection from Direct Contact with Contaminants and Prevention of Migration of Contaminants.
Guidance is also provided for inspection and maintenance of the cap. When the use of a cap is selected to attain a Site-specific Standard under Act 2, there are also post-remedial care plan and environmental covenant requirements that accompany the use of a cap. The post-remedial care plan and environmental covenant must outline the appropriate conditions to ensure the integrity of the cap is maintained. A recommended routine frequency of inspections is not identified in the Cap Guidance, but inspections should take place during and after any activities that disrupt or penetrate the cap. Any disruptions of the cap (penetrations, trenching, construction) should be repaired within 30-days of the date of discovery, and the discovery and repair should be reported to PA DEP within one month of discovery.