June 11, 2007
Vapor Intrusion: Investigations and Mitigation Issues
Brach Eichler L.L.C., Roseland
By Lindsay P. Kern & Frances B. Stella
Contamination of groundwater and soil has long been an issue the New Jersey Department of Environmental Protection (NJDEP) and the United States Environmental Protection Agency (EPA) regulated.
In New Jersey, environmental investigations and/or remediation of property at or near contaminated sites – such as gas stations and dry cleaners – are generally directed by the NJDEP. Recently, NJDEP and EPA have forced responsible parties (RPs) to investigate vapors released from contaminated soils. These agencies are now requiring, as part of many remedial investigations, an investigation into whether indoor air space at a contaminated site or any potentially impacted off-site property is subject to vapor intrusion from a hazardous waste discharge.
Defined
Vapor intrusion is defined as the migration of volatile chemicals from the subsurface into overlying buildings. See NJDEP’s Vapor Intrusion Guidance, dated October 2005 (Guidance). Vapor intrusion into indoor air space can result when chemicals or petroleum products are spilled or discharged on the ground and into the soil or groundwater or as a result of a leak from an underground storage tank. When this happens, depending on the soil type and subsurface formations, the chemical or petroleum products volatize into gas or vapors that move through the soil along the path of least resistance and can enter indoor air spaces through cracks in basements, foundations, crawl spaces, cement slab, sewer lines or other utility openings. Common sources of vapors are gasoline products, dry cleaning solvents and industrial degreasers. The concern is that vapors, which migrate through pathways in the ground and enter buildings, result in indoor air concentrations that may be a health risk to residents or workers in those buildings.
Investigative Process
The vapor intrusion investigations are far more intrusive than soil and groundwater investigations, as access into private homes is usually necessary and property owners generally more hesitant to cooperate with these requests. Access to private property can usually be negotiated between the property owner and the RP, but if an agreement can not be reached, the RP can obtain access through a court order.
RPs and their consultants should utilize the Vapor Intrusion Guidance Manual issued by the NJDEP in October 2005 to conduct their investigations and any necessary subsequent mitigation of vapor intrusion. The NJDEP recommends a conceptual site model (CSM) and/or specific written and illustrated plan be developed to assist with the analysis and possible remediation of contaminated property. After the plan is developed, the NJDEP recommends it be provided to NJDEP – the governmental body responsible for contaminated property – for approval to avoid any future penalties. The CSM or written plan must include suspected contaminant sources; contaminant migration pathways; potential human receptors; and the exposure routes by which these receptors may come into contact with contaminants.
The NJDEP defines a “vapor source” as “the presence, or reasonably suspected presence, of a chemical of sufficient volatility and toxicity in the subsurface with sufficient mass and/or concentrations to pose a possible inhalation risk within current or future occupied overlying enclosures.” It has identified distinct pathways for vapor migration into a structure:
- diffusion of the contaminant vapors from a source underground;
- diffusion of contaminant vapors from groundwater, transport of vapors from air movement underground; and
- transport of the vapors through cracks or holes in underground piping and sewers.
At the area of contamination, diffusion occurs which then releases vapors that may travel through pathways above the surface. The vapor intrusion investigation must locate the source of the vapors and the path by which the vapors are traveling to the surface, along with determining whether any indoor air is impacted to pose a health risk.
In order to determine the pathway of the contaminant vapors, the RP completes the NJDEP Indoor Air Building Survey and Sampling Form with the property owner and conducts soil gas sampling. There are two types: Near slab soil gas sampling and sub-slab soil gas sampling. When sampling and testing are conducted and identify the possibility of vapor intrusion, the RP will conduct near slab soil gas sampling, which will occur on the exterior of the building and/or sampling of the air in the building. This testing will provide readings for soil gas contamination in those sub-surface areas and is minimally intrusive to property owners. Unfortunately, NJDEP’s preference is that sub-slab gas sampling, requiring holes be drilled through the concrete slab in the basement or bottom floor of the building and soil gas samples collected from beneath the structure, before it will be satisfied a structure is not impacted by vapor intrusion. Many property owners prefer near slab sampling be conducted first to determine whether or not any contaminants are found before holes are drilled. The NJDEP generally finds these tests inconclusive and requires the more intrusive testing.
In addition, an RP only taking indoor air samples without the sub-slab samples to assess indoor air problems can result in false positives, since indoor air problems can also result from the use of household products brought into the home or industrial cleaning and chemical use buildings. Products that can cause indoor air contamination include paints, paint strippers or thinners, moth balls, new carpeting and furniture, stored fuel, cigarette smoke, air fresheners, cleaning products, dry-cleaning clothing and even vapors from running tap water.
Near slab and sub-slab soil gas collection sampling is a relatively simple sampling procedure that includes drilling a small hole through the surface such as a sidewalk or driveway for near-slab, or basement or crawl space for sub-slab. A tube or probe is then inserted in the ground, sealed and connected by a tube to a small sample container to collect soil gas over a stated period, usually 24 hours. The sample canister is then analyzed for soil gas vapors.
Remediation Reports
The NJDEP utilizes the Technical Requirements for Site Remediation (TRSR) as the regulatory basis for the directives it issues regarding vapor intrusion. The TRSR provides at N.J.A.C. 7:26E-3.5 that “the site investigation of building interiors shall be conducted when contaminants … outside the building have the potential to migrate into the building.” The NJDEP’s primary goal is to remediate the source of any vapor contamination and eliminate the risk of vapor intrusion.
The TRSR require a Remedial Investigation Report/Remedial Investigation Workplan (RIR/RIW) be submitted to the NJDEP providing for the methods that will be utilized to remediate a contaminated property. This RIR/RIW will be reviewed by the NJDEP case manager who will provide comments in response. If it finds problems with the RIR/RIW, the NJDEP will issue a Notice of Deficiency (NOD), requiring a response to each deficiency be provided in the timeframe indicated in the NOD. See N.J.A.C. 7:26C-10.3.
Commonly known as the “Grace Period Rules,” they became effective Sept. 18, 2006, and standardize the procedure by which NJDEP directs site remediation. If an NOD is received and is left uncorrected, the NJDEP will issue a Notice of Violation (NOV) and/or a civil administrative penalty depending on whether the action is considered minor or non-minor.
Thus, if NJDEP finds that a vapor intrusion investigation is necessary, it can direct a party to perform the work under the NOD or the RP will face potential penalties for failure to perform.
Appeals Process
If NJDEP issues a monetary penalty, an appeal can be made to the commissioner of the NJDEP. If the commissioner upholds the penalty, an adjudicatory hearing can be requested pursuant to the Administrative Procedure Act, N.J.S.A. 52:1413-1 et seq., and if the penalty is still upheld, an appeal can be made to the Appellate Division.
Court-Ordered Access
RPs can face offsite property access hurdles complying with NJDEP’s directives when property owners resist or deny access to install probes in the sub-slab and collect gas samples which can result in imposition of monetary penalties. In an effort to make environmental investigations and remediation of contaminated property a priority, legislation was enacted allowing a judge of the Superior Court to issue an access order requiring a property owner allow a RP access to the property to conduct an environmental investigation, including vapor intrusion investigation. Before such an order can issue, the RP must show (1) it attempted in good faith to work out an access agreement with the property owner, and (2) NJDEP and/or the regulations require the investigation. If the court refuses to sign the order, the NJDEP must be advised the required remediation could not proceed so the RP is not issued penalties.
Mitigation
Once access to a property is obtained and the soil gas sampling indicates there is a soil gas vapor in the subsurface that can impact indoor air quality through vapor intrusion, the RP is required to mitigate the vapor intrusion impact. Depending on the construction of a building, there is generally a simple solution of installing a mitigation system that extracts soil gas vapors from beneath the basement or foundation in the subsurface before entering the building. The soil gas is then vented outside before it enters the building; thus, residents are not exposed to harmful air which may concentrate in the basement or crawl spaces of a home. Vapor intrusion mitigation systems are similar to radon mitigation systems and use minimal electricity.
While vapor intrusion has become of interest to regulators and the public as a potential pathway of exposure, a RP or property owner should not be overwhelmed by the prospect of conducting the investigation and, if necessary, mitigating potential impact. Both sampling and mitigation systems are relatively simple to install, once access is obtained.
ROS:1245707.1/BEO002-102001- 1 -