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HRP Associates, Inc. is finalizing the installation of what is likely the first vapor mitigation system of its kind in Pennsylvania. The project, now nearly complete, was designed by HRP as a sub-slab de-pressurization system (SSD). HRP incorporated a similar design beneath the floor slab of a new retail building built on a Pennsylvania brownfield site should the system be needed in the future. What makes the current system unique is its size and the fact that it is being installed under an existing building.
HRP’s soil and groundwater investigations led to the discovery of a potential vapor intrusion issue. The SSD uses the same principle as a home radon system, except the system is designed to cover over half of the facility’s 75,000 ft2. In fact, the SSD uses reliable home unit radon fans. The fans are not used to create a strong vacuum or remediate the soil as found in a soil vapor extraction (SVE) remediation system. Rather, they are used to reduce sub-slab atmospheric pressure just enough to cause migrating soil gas vapor to exit the subsurface through the SSD network rather than through the floor slab and into worker occupied areas.
Vapor intrusion risk is relatively new and in the early stages of being understood when compared to our understanding of soil and ground water risk and the pathways associated with receptor risk. HRP’s SSD mitigation system provided the buyer with additional reassurance. In turn, it was a cost-effective solution to help facilitate a $1 million sale by HRP’s client under a Buyer-Seller Agreement within Pennsylvania’s Land Recycling Program, commonly known as Act 2.
For more information, please contact Jim LaRegina, PG at 866-232-9824.