Site screening and modeling
Using a site’s historical data, O’Brien & Gere can evaluate whether your site is a candidate for potential vapor intrusion. This screening assessment is usually quick and cost-effective, and has resulted in many “no further action recommended” conclusions. 

Soil/sub-slab vapor sampling 
Soil vapor samples may be collected to evaluate whether the environmental medium is impacted, to characterize the nature and extent of contamination, and identify possible sources of the contamination. Sub-slab soil vapor samples may be collected to characterize the nature and extent of soil vapor contamination immediately beneath a building with a basement foundation and/or a slab-on-grade. 

Soil and ground water investigations 
When evaluating the severity of contamination, we will look at several characteristics of soil and ground water. For ground water, we will consider a number of factors including: water depth for shallow and regional aquifers, ground water flow direction, evaluate potential seasonal variations, ground water chemistry and identify cultural features that may affect shallow ground water behavior. When investigating soil, we will look at soil types, including clay, sand, gravel, fractured rock, and sediments; the extent to which preferential pathways may be present; and other geological considerations that may have the potential to cause vapor intrusion. 

Indoor air sampling 
Indoor air samples may be collected in order to characterize potential exposures, identify the extent to which vapor intrusion is contributing to existing indoor air quality, or to verify previous hypotheses or models. 

Building surveys 
There are several building factors that may affect vapor intrusion, including: operation of HVAC systems, fireplaces, mechanical equipment; heated buildings, air exchange rates, foundation types, foundation integrity; and subsurface features that penetrate the building’s foundation. We evaluate each of these factors during investigation of the vapor intrusion pathway. 

Indoor source identification 
Our technical approach allows us to differentiate vapor intrusion impacts from normal background concentrations. This expertise is critical in states that promote a “no discernible impact” endpoint for vapor intrusion matters. 

Health risk assessment
With the use of several specialty tools, our trained toxicologists and risk assessors can prepare a site-specific risk assessment, if required. These efforts are often used to reduce the size of mitigation projects, saving our clients time and money.

Community air monitoring & modeling 
In extreme instances, ambient air quality impacts resulting from vapor intrusion mitigation systems can represent a concern to the general public and the regulatory agency. Our air quality experts can use computer software to simulate the dispersion of these vapors into the atmosphere and, when needed, design an ambient air monitoring network to provide real-time measurement of these contaminants.