Vapor Intrusion Mitigation Systems in Strip Malls
Vapor intrusion issues in strip malls is an unfortunately common occurrence due to the probability of the building having businesses that can accidentally cause soil and water contamination from the chemicals they use. Gas stations and dry cleaners being near or inside of a strip mall can release harmful VOC’s such as trichloroethylene (TCE) and perchloroethylene (PCE) (PERC), or potentially explosive gasses such as gasoline, diesel, and methane. These chemicals have a high probability of turning into vapors when present in the soil and when those vapors rise and make their way into a structure, this is known as vapor intrusion. There are a few ways of testing for vapor intrusion issues inside of a building such as a strip mall depending on what type of building is being tested, whether or not the building is under construction or existing, and who is conducting the test. Vapor intrusion sampling should always be done by a professional and reported to the proper environmental authorities if an issue is found in the area. There are two main goals of vapor intrusion sampling which are to determine if the pathway for vapor intrusion into the structure is complete, and if it is, then to examine whether or not the vapor contaminants pose a health risk to the occupants inside of the structure. Once an issue has been identified, and the testing has shown that the occupants inside of the building are at risk, a vapor intrusion mitigation system will need to be implemented to remove that risk. Lifetime Environmental Solutions has been in the mitigation industry since 1995 assisting homeowners, business owners, and environmental consultants alike with their vapor intrusion and radon removal projects. Lifetime Environmental Solutions will guide you through the process of removing harmful vapors from your strip mall and will design and install a custom mitigation system to keep harmful vapors and radon out of the property indefinitely. Give us a call today for a free, no obligation consultation.
Active Soil Depressurization Systems
By far the most proven and effective technique to remove and deter vapor intrusion issues within a property is with the installation of an active soil depressurization system (ASD). Active soil depressurization works by drawing air from under a structure to create negative pressure that will draw harmful gasses rising up from the soil into a pipe to be vented to a safer area. The gasses and vapors that are not drawn into the piping are deterred away from the building because of this pressure as well. In strip malls, the most common method of ASD is sub-slab depressurization (SSD).
Sub-slab depressurization systems are installed by coring a hole or multiple holes into the slab of the building. Underneath the drilled holes, soil is removed from underneath the building to create an area for collection of the vapors. A PVC or stainless steel pipe (pipe material is chosen depending on the type of vapors present) is then sealed to the collection point and run up and out of the building. An in-line fan is added to the piping to actively create the desired negative pressure in the soil, and then a manometer is added to measure the effectiveness of the fan. If you are familiar with how a radon mitigation system looks on a residential home, then you may already have an idea of what this type of system looks like. Strip malls are typically very large in terms of footprint, so multiple collection points and systems are usually needed to mitigate the entire property.
If the building has a dirt or gravel crawlspace or basement underneath the ground floor, a technique called sub-membrane depressurization (SMD) will need to be applied for proper vapor removal. Sub-membrane depressurization systems involve the addition of a vapor mat to the open soil that is to be sealed air tight to trap the rising vapors. After the vapor mat is applied, collection points are dug underneath the mat, and the piping for the system is sealed to the collection points. The rest of a sub-membrane depressurization system looks identical to a sub-slab depressurization system.
Other less commonly used, but effective (when used correctly) methods of depressurization include block wall depressurization and passive system depressurization. Block wall depressurization is utilized when gasses are entering a structure through the inside of the block walls. This method is performed by sealing the tops of the blocks, and adding an active pipe to the wall to draw out the trapped vapors. Block wall depressurization is typically used in-tandem with SSD or SMD.
Passive systems are almost exclusively used for new construction and work with stack effect to draw out rising soil glasses without the use of a fan. If a vapor intrusion issue arises after the building is finished, a fan can be added to the passive system to work as a typical SSD system. The implementation of a passive mitigation system can be very tricky, as improperly installed passive systems will not do anything to prevent harmful vapors from entering a structure. As with the other ASD methods mentioned above, passive mitigation systems should be installed by a certified professional like Lifetime Environmental Solutions.
Lifetime Environmental Solutions has decades of experience designing and installing all types of active soil depressurization systems and are eager to help your business with any indoor air quality issues. Give us a call today for a free vapor intrusion mitigation estimate!
Vapor Intrusion Mitigation Cost
The costs associated with the design, installation, and proper pre and post testing procedures is largely dependent on the size of the building, the type of toxic vapors present, and the aesthetic requirements from the building owners. Strip malls typically have a larger footprint, so multiple systems and collection points are usually necessary to cover all of the businesses inside. Obviously with vapor mitigation it isn’t “one price fits all”, however the price of a mitigation system may be less than you think. Lifetime Environment will draft a detailed and competitive proposal for your building and walk you through each cost to make you feel comfortable with your decision. Give us a call today to start the process.