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With So Many Solvents, Why is it Called Dry Cleaning?
If you have visited your local drycleaner lately, consider this… estimates show that approximately 75 percent of dry cleaning operations have experienced some kind of release of solvents into the environment, and estimates for older facilities operating before 1990 are even higher.
With more than 30,000 dry cleaners currently operating in the United States and an estimated three to five times as many former cleaners, this industry represents the second most common source of contamination in the U.S. Unlike manufacturing plants, landfills, and other sources of contamination, dry cleaning sites are unique in that they are typically found in urban areas among residential and retail properties.
Dry cleaning sites are in close proximity to many people and property development projects that may be impacted by contamination. The convenient urban locations of dry cleaners also makes them good candidates for redevelopment, and because of this, Terracon often encounters them when conducting Phase I Environmental Site Assessments (ESAs) and subsequent Phase II investigations for property transactions.
Rapid Site Assessments
Time is of the essence in most environmental investigations related to property transactions. In order to obtain the data needed to accurately assess potential impacts, Terracon utilizes state of the art field screening technologies. While assessing an active dry cleaner in the fall of 2013, our field staff analyzed soil and groundwater samples using a Color-Tec™ kit, which provides real-time test results. This rapid field analysis technique allowed Terracon to deliver our client immediate feedback on impacts and make adjustments to the scope of services. These adjustments allowed the client to obtain the information necessary to evaluate the site within their allotted due diligence period without extending the sale closing date.
Another example of a rapid assessment occurred in 2006 when Terracon completed a Phase I ESA at a former dry cleaning property slated for redevelopment. Although the cleaner operated only four years during the early 1970s, it was responsible for a contaminant plume that extended a half of a mile toward a creek.
To rapidly investigate the potential for surface water impacts, Terracon used a thermal imaging camera to identify the exact locations of groundwater migration into surface water. Thermal imaging provided the client immediate feedback to our staff and focused their future investigations, which saved our clients both time and money.
An Understanding of the Contaminant
Before an investigation begins, we need to know the timeframe the dry cleaner operated. This will help us identify the correct solvents. Dating back to the late 1800s, several different solvents were used, all of which are hazardous.
Tetrachloroethene (or PCE) is the most common dry cleaning solvent and has been used over the past 50 years. This solvent is slowly being phased out due to concerns over its toxicity. A release of just over 10 drops of PCE into groundwater is enough to contaminate an area of 100 square feet by 20 feet deep to concentrations above PCE’s legal limit. California was the first state to establish a sunset date in 2023 for elimination of PCE dry cleaning machines.
Dealing with DNAPLs
Several dry cleaning solvents are characterized as dense non-aqueous phase liquids (DNAPLs), which are a group of compounds that are relatively insoluble and denser than water. The resulting dissolved phase plume that emanates from a DNAPL release is typically larger and deeper than similar plumes. These compounds are resistant to degradation and can persist in the environment for decades.
Another challenge related to many of these compounds is their potential to migrate into a building’s indoor air (known as vapor intrusion), where toxic vapors can be inhaled. When investigating hazardous vapors, Terracon uses a variety of innovative approaches in addition to traditional sampling. To evaluate the source of vapors at one former dry cleaner, helium was injected beneath the building and a hand-held detector was used inside to identify the exact locations where vapors entered the building and needed to be sealed.
Unique Sites Require Unique Solutions
Despite the challenges posed by DNAPLs and other conditions found at many dry cleaning sites, Terracon’s technical staff has successfully completed hundreds of investigations. In many cases, our success is rooted in our flexible approach and use of innovative methods.
We take this same approach when identifying clean-up strategies for these sites. At a former dry cleaner now being used as a restaurant, an approach was developed that utilized angled wells to target contamination directly beneath the building. A single injection of nano-scale zero valent iron was able to reduce contamination to below clean-up goals.
At another site with chlorinated solvents migrating into surface water, we designed and installed a phytoremediation system. Phytoremediation uses plants to cleanup the contamination. The system consisted of several rows of willow trees planted in a riparian area. After installation, the phytoremediation system was responsible for reducing contamination to safe levels.
As highlighted in the previous examples, Terracon has both the knowledge and experience to overcome challenges associated with dry cleaning contaminants and the complicated circumstances presented at former dry cleaner sites. Whether the project requires an initial screening prior to a property transfer or full-scale cleanup, Terracon possesses the expertise to cost-effectively achieve your project goals.