The Dry Cleaner Dilemma, Part 2 – The Phase II ESA

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The Dry Cleaner Dilemma, Part 2 – The Phase II ESA

By: Craig A. Cox, CPG

Published in August 2019 Focus on the Environment Newsletter

There are, or have been, thousands of small commercial dry-cleaning operations throughout the U.S. – nearly every neighborhood had one.  Most of them are, or were, small family-owned businesses that started in the 30s, 40s, or 50s.  Many of these facilities became ‘anchor’ stores of small shopping centers that are now being redeveloped.  In this series of articles, we examine the pitfalls of real estate transactions involving former dry cleaner operations.  The first step in the process should be the Phase I Environmental Site Assessment (ESA), conducted by a qualified environmental professional.  The Phase I ESA is a desktop evaluation and site inspection that provides the prospective new buyer with information concerning past environmental concerns at a property generally known as “recognized environmental conditions” (RECs).  In the previous instalment of the Dry Cleaner Dilemma , we reviewed the potential short comings that could surface associated with the Phase I Environmental Site Assessment (ESA) of a former dry-cleaning operation. 

In this instalment, we will examine potential problems associated with the typical Phase II ESA.  The typical approach to Phase II ESAs is to install a handful of soil borings, collect a soil sample or two from each boring, and potentially a grab sample of groundwater.  The results can be revealing; however, they produce little information concerning the primary exposure pathway, which is vapor intrusion (VI).  So how should we approach these sites?    

Let’s examine the results of a typical Phase II ESA to see if a different approach should be taken. In this example, a former dry-cleaning operation was identified during a Phase I ESA in 2005.  The consultant recommended a limited Phase II ESA which consisted of 4 borings surrounding the building.  The borings were drilled to 15 feet and screened for VOCs using a photo-ionization detector (PID).  Based on the screening, a single sample (having the highest PID reading) from each boring was collected for laboratory for analysis.  The analyses detected tetrachloroethene (PCE) at depths as deep as15 feet; however, the concentrations did not exceed published direct contact standards and the site was deemed suitable for redevelopment.

By 2008, the site had been razed and replaced with an apartment complex.  Your client is considering its purchase and requests that you complete a Phase I ESA.  Materials for your desktop review include the previous Phase I and II ESAs.  The first question becomes – “Has the risk associated with this site been sufficiently characterized?”  The answer is no because an evaluation of VI pathway, which is the primary driver of risk at dry-cleaning sites, has not been evaluated.  A change in site use, from commercial to residential, reinforces the need to evaluate this pathway because the acceptable exposure concentrations are lower.

You report this to your client, but they are a bit confused given the previously established PCE concentrations in soil and the time that has passed since the initial assessments.  The client likes this deal and wants to press forward.  “Given the soil concentrations nearly 15 years ago met the direct contact standard, haven’t conditions likely improved?  Can’t you evaluate the vapor intrusion issues based on these soil results?”

Granted, site conditions may have improved; however, it is not realistic to evaluate the vapor intrusion potential based on analytical results from soils samples.  This may sound counterintuitive, until you consider the following:

  • A soil sample is collected from a specific point in space and only represents the conditions at that point. Unless directed by other data, such as a soil gas survey or other high-resolution site characterization technique, the chances of locating a VOC source (and likely greatest concentrations) through a few scattered borings are low.
  • The results of VOC analyses from soil samples can’t be used to evaluate soil vapor concentrations. This is in part due to the moisture content of the soil which will affect the potential for volatilization. 

In this situation, the only realistic approach to evaluate the potential for VI is to collect soil gas samples.  A full assessment of the VI pathway, including the collection of indoor air samples could take as long as a year to complete in some parts of the country (to account for season variations in building dynamics).  This makes it problematic for real estate transfers.  However, screening a site based on soil gas alone can be completed very quickly.  For instance, a grid of 40 to 50 sub-slab soil gas points can be installed, screened, and abandoned in a single day.  The screening process will rely on a PID or other similar device to locate potential hot spots.  At those hot spots, a soil gas sample from beneath the slab is collected for confirmation and analysis.  The results of sub-slab soil gas sample analyses can then be directly compared to vapor intrusion screening levels published by US EPA or your particular state agency.    

In the example site discussed above, a soil gas survey was recommended.  Due to access limitation, a sample grid of only eight points was completed in the parking areas surrounding the building.  The survey indicated that a PCE hot spot existed beneath the building.  Based on these data, access was granted and a sub-slab sample collected beneath the building.  That sample indicated that the potential for VI existed and money was set aside for a mitigation system as part of the sales agreement.

Dry-cleaning facilities can present an unacceptable risk of exposure to chlorinated solvents through the ingestion of contaminated groundwater, ingestion of contaminated soils, or through the inhalation of vapors.  Of these, the most likely pathway is through the inhalation of vapors.  Because of this, the assessment of a site identified as a former dry-cleaning operation cannot be complete unless a soil gas survey has been completed.

Craig Cox is a principal and co-founder of Cox-Colvin & Associates, Inc., and holds degrees in geology and mineralogy from the Ohio State University and hydrogeology from the Colorado School of Mines. Mr. Cox has over 30 years of experience managing large environmental project implemented under CERCLA and state voluntary action programs. Mr. Cox is the inventor of the Vapor Pin® and has developed a variety of software products including Data Inspector, an internet-enabled environmental database application. Mr. Cox is a Certified Professional Geologist (CPG) with AIPG and is a Certified Professional (CP) under Ohio EPA's Voluntary Action Program.