The erected steel framework is all that exists on the site of the future Martin Luther King-Jefferson Elementary School, one of a number of schools that the School Construction Corporation (SCC) plans to build on a contaminated site.  But the SCC isn’t alone.  Across the country thousands of buildings are being constructed on sites that are less than pristine.  The types of structures built on these sites range from single-family homes and townhouses to commercial warehouse space and office buildings, as well as numerous schools. The key component of all of these redevelopments is that a gas vapor membrane was used to prevent harmful vapors from intruding into the structures.

Gas vapor barriers are an integral part of building on any brownfield, or former landfill sites.  They limit the possible migration of vapors and contaminants into the indoor environment that is occupied.  The New Jersey Department of Environmental Protection (NJDEP) and the New York State Department of Environmental Conservation (NYSDEC) are both implementing stringent guidelines for vapor intrusion. Placing a vapor barrier below the slab will eliminate vapor intrusion and keep the building owner in compliance with standards, in addition to keeping them out of litigation. 

A recent project evaluation performed at the Seaview Mall in Ocean Township, which was built on a former landfill, showed that methane levels were lowered to non-existent levels by placing a vapor barrier below the foundation in conjunction with a sub slab depressurization system. This site is one of many “big box” developments that have used a similar system to mitigate vapors.

Vapor barriers are no longer an expense that can be overlooked.  Vapor barriers range between $4 and $8 per square feet depending on the application, complexity, contamination, and region.  But considering the potential health risks, the regulatory climate, and the litigious nature of brownfields, vapor barriers are literally cheap insurance.  Initially developers and builders did not use vapor barriers on projects unless a regulatory body required it, now even large builders are being proactive and using vapor barriers on their buildings.

In New Jersey, due to the industrial history, brownfields or former manufacturing sites are often some of the most valuable land in your township. Whether the site is left as is, or soil is removed and there is residual contamination, a vapor barrier can be used to maintain a safe site and allow for occupancy of the buildings.  It can also provide peace of mind for a township, developer, or other concerned parties knowing that the building(s) will be safe for use.

This type of liner can be termed a brownfield liner, an environmental liner, a gas vapor barrier, or membrane.  While used primarily on new construction, these products can often be applied onto existing structures as well.  Vapor barriers used for environmental protection are typically either a sheet liner such as high-density polyethylene (HDPE) or a fluid applied product such as Liquid Boot®.

Both sheet liners and fluid-applied liners have been in use for well over 15 years providing applications on or underneath the foundation of new or existing structures.  While both products are considered to be of the highest standard, fluid applied products such as the Liquid Boot® Gas Vapor Membrane are extremely beneficial because they speed up the installation process (time does equal money) and they can seal better around the foundation because the product adheres to concrete, wood, and metal surfaces.  The Liquid Boot® product has been used in New Jersey for developments involving Lowe’s, Wegman’s, Pathmark, commercial warehouse space, and townhomes.  For more information, try using the Google search engine to look up key words “gas vapor membranes” or visit www.liquidboot.com. It is key for a qualified engineering or consulting firm to design a system that is right for your site.  The great thing is the technology exists and can be utilized, and has been used by some of the largest, high-profile builders and developers on the most prime pieces of real estate in New Jersey. 

 The use of the gas vapor membrane to make brownfield or former landfill sites safe for a redevelopment project is common, and it is important to note the precedent across the country.  In Southern California, Liquid Boot® vapor barriers are used on numerous single family homes built on the methane zones for builders such as Toll Brothers, Centex, and KB Homes.  Additionally, many schools in the Los Angeles area are also built on methane zones that are made safe by the use of vapor barriers, typically in conjunction with a sub-slab vent system (to relieve methane gas pressure underneath the slab).  The New York City School Construction Authority [NYCSCA] has been using vapor barriers for a number of years, but has just recently made them a mandatory part of new construction whenever a potential for environmental issues exists.