Fate of Spilled Perc in the Subsurface: Understanding the Basics When it Gets in the Ground

Written By Keith Gaskill, L.P.G, Project Manager and Geochemist, EnviroForensics.

As seen in the July 2011 issue of Cleaner & Launderer.

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Releases of Perchloroethylene (PCE) to the subsurface from drycleaning operations and related PCE handling are not rare.  The result of environmental investigation in response to a confirmed spill is not only to determine the concentration of materials in the ground, but to develop a conceptual site model as to where the contaminant is going.  Once a model of what’s there, where it’s going and how it’s getting there has been constructed, a remedy can be selected and implemented. 

The releases at the surface consist of primarily two types.  Free phase PCE in dense non-aqueous phase liquid (DNAPL) pure form and dissolved phase PCE in water.  Current accidental releases are often spills resulting from the drycleaning process.  Historically, chemical handling practices were not as refined as they are today and there may have been releases related to cleaning of filters; distiller boil-overs; storage equipment failures, or disposal of hazardous process waste as well as spills from older drycleaning machines and operations.  The PCE may be introduced to the subsurface on dirt or gravel, which allows an easy pathway to the soil, or will travel directly, though untreated concrete (and can even dissolve asphalt).  Continue reading “Fate of Spilled Perc in the Subsurface: Understanding the Basics When it Gets in the Ground”

Zero-Valent Iron Shows Promise As a Strong Chemical Reducer of Perc

Written by Steve Henshaw, P.G., President & CEO, EnviroForensics, in Collaboration with Keith Gaskill, L.P.G., Project Manager and Geochemist, EnviroForensics
As seen in the May 2011 issue of Cleaner & Launderer

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Zero-valent iron (ZVI) has been used in the groundwater remediation industry for several decades.  Typically, granular scale ZVI was emplaced in trenches serving as a permeable reactive barrier wall, whereby contaminated groundwater would flow through the wall and volatile organic compounds (VOCs) like Perc would react with the material and breakdown.

This technology worked so well that scientists started applying the ZVI into contamination source areas and hot spots.  Recent advances have produced smaller scale iron particles that can be mixed into a slurry and pumped into the ground through the use of pre-existing injection technologies.  Continue reading “Zero-Valent Iron Shows Promise As a Strong Chemical Reducer of Perc”

Advancements in Fingerprinting Contaminants; Compound Specific Isotope Analysis (CSIA)

Written by Steve Henshaw, P.G., CEO, EnviroForensics

Keith Gaskill, L.P.G., Chief Geologist, EnviroForensics

As seen in the February 2011 issue of Cleaner & Launderer.

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Among the challenges in environmental consulting is determining responsible parties in comingled plumes.  With so much money and liability at stake, confident determination of contaminant sources (fingerprinting) becomes vital to not only our clients’ personal stake, but to the timely cleanup of potentially dangerous contaminant plumes. 

The first and most utilized fingerprinting method is basic compound analysis.  Generally, it is known what hazardous substances were released to the subsurface and what chemical compounds can be associated with that release.  Analysis is completed by comparing compounds detected.  For example, two drycleaners next to each other are located directly upgradient from a residence where one drycleaner has used Stoddard solvents and one has used perchloroethylene (perc) in the drycleaning process.  When laboratory analysis reveals the presence of petroleum compounds (perc contains no petroleum compounds whereas Stoddard solvent does) in groundwater under the residence, it is determined that the Stoddard solvent plant is likely the responsible party.   Continue reading “Advancements in Fingerprinting Contaminants; Compound Specific Isotope Analysis (CSIA)”

Can PERC Releases Be Age Dated and Fingerprinted?

Written by Stephen Henshaw, P.G., President and CEO, EnviroForensics
As seen in the May 2010 issue of Cleaner & Launderer

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For years parties responsible for the costs associated with environmental investigations and cleanups of Perc contamination have been trying to determine when Perc releases have occurred.  This topic has important ramifications when sites have had a series of dry cleaning operations over time, when different insurance carriers insured dry cleaners and property owners, and when several dry cleaning releases have comingled together from different dry cleaning locations.

So, for the past 15 to 20 years, scientists like Dr. Konrad Banaszak with EnviroForensics, have been trying to figure out how to age date PERC releases.  So, can Perc releases be accurately age dated?  The answer is yes, no and maybe.  Continue reading “Can PERC Releases Be Age Dated and Fingerprinted?”

Score One for the Drycleaners in BAAQMD…at least for a little while

By Marti Russell, REA, Western Sales Manager, EnviroForensics

A Steering Committee Meeting was held on Friday, March 5, 2010 in San Francisco.  As if the economy isn’t bad enough for small businesses and depending on the outcome of this meeting, the cleaners in the Bay Area Air Quality Management District in Northern California may have another hurdle in trying to stay open and meet the mandated regulations bestowed upon them.

The BAAQMD staff was directed by the Board of Supervisors last year to come up with a plan to shorten the time frame on phasing out perc in their District.  All perc cleaners in the BAAQMD know the District wants to accelerate the banning of perc faster than the California Air Recourses Board mandated timeframe of 2023. Continue reading “Score One for the Drycleaners in BAAQMD…at least for a little while”