How do you stop a vapor intrusion?
Sealing openings involves filling in cracks in the floor slab and gaps around pipes and utility lines found in basement walls. Concrete can be poured over unfinished dirt floors. Installing vapor barriers involves placing sheets of “geomembrane” or strong plastic beneath a building to prevent vapor entry.
How does vapor intrusion work?
Vapor intrusion occurs when chemical vapors migrate from contaminated groundwater through the soil into the basements or foundations of buildings. These chemical vapors can degrade indoor air, sometimes to the point of posing risks to human health.
What is vapor mitigation system?
A vapor mitigation system (VMS) is designed to interrupt an exposure pathway. Such a system does not remove contaminant mass. Vapor mitigation systems include a radon-type sub-slab depressurization system as well as other, more site-specific systems.
What is soil vapor intrusion?
Soil vapor intrusion is the process by which volatile chemicals move from a subsurface source into the indoor air of overlying buildings.
What is a passive vapor mitigation system?
Passive vapor mitigation involves barriers installed in existing buildings or pre-construction to prevent the entry of chemical vapors. Retro-Coat™ is an example of a vapor barrier coating system that protects existing structures and can be customizable to fit the unique needs of the structure.
What is a soil gas mitigation system?
Soil gas mitigation systems reduce the exposure to radon either by preventing the radon from entering the building, or by removing it once it has entered. The most desirable method is to prevent the radon from entering the building because it provides for the lowest possible exposures.
How do you test a vapor intrusion?
The vapor intrusion testing is not complicated. It involves drilling holes into subsurface soil, attaching a sealed sampling line to a vacuum cylinder and allows the soil gases to be drawn into the vacuum cylinder over an extended period of time (usually 8 hours to 24 hours).
What are the advantages of tree sampling over the traditional methods for assessing vapor intrusion?
Trees make an excellent initial indicator for vapor intrusion because tree core sampling doesn’t require much equipment, takes less time, and is a lot cheaper than traditional sampling methods.
When did vapor intrusion begin?
To learn more about these products go to EPA’s Volatile Organic Compounds’ Impact on Indoor Air Quality Webpage. Recognition of chemical vapor intrusion occurred starting in the 1980s with concerns over radon intrusion.
What is sub slab depressurization?
A sub-slab depressurization system consists of PVC piping installed through the slab floor and a fan connected with the piping. A subsurface depressurization system prevents vapor intrusion by directing hazardous vapors in the soil to the exterior of the building.
How do you install a soil gas mitigation system?
Steps for Installing Radon Mitigation
- Step 1: Make a hole.
- Step 2: Dig out under the slab.
- Step 3: Run pipe from cellar to attic.
- Step 4: Place and seal pipe.
- Step 5: Run the pipe to a fan.
- Step 6: Install a manometer.
- Step 7: Test the system.
When do you need a Vapor Intrusion System?
Upon the identification of a vapor intrusion concern, a sub-slab depressurization system for the control of indoor air vapor intrusion is likely to be required. The design of these systems can be complicated, especially in existing buildings in old commercial/industrial areas.
How is SSD used for sub slab depressurization?
SSD is widely considered the most practical and effective vapor intrusion mitigation strategy for existing structures. The USEPA defines SSD technology as “a system designed to achieve lower sub-slab air pressure relative to indoor air pressure by use of a fan-powered vent drawing air from beneath the slab.”
What should the water column be for a SSD?
The U.S. EPA has not issued a definite value for SSDS design; however, achieving a pressure differential of -0.004 inch water column (in. w.c.) (1 Pascal) across the slab is generally considered sufficient to mitigate vapor intrusion based on available industry guidance4..
Where does Hull do sub slab depressurization?
Hull & Associates, Inc. (Hull) conducted sub-slab depressurization (SSD) pilot testing events in January, February and April 2016 in the Western Factory Area of the Former Hoover Facility located at 101 East Maple Street, North Canton, Ohio (Site).