Written by Stephen Henshaw, P.G., President and CEO, EnviroForensics
As seen in the August 2010 issue of Cleaner & Launderer
I frequently get calls from dry cleaners asking for advice and one of the common questions is, “How much is it going to cost to cleanup my site?” Knowing that my dry cleaner friend is looking for an answer better than “depends” and realizing that it is impossible to give him an accurate cost without knowing a lot more about the site conditions, I find myself walking a bit of a tightrope. Environmental cleanups are driven by several factors, but the primary factor is risk. The risk is whether the chemical release could impact the environmental that supports animal life, as an example, wetlands, creeks, streams, lakes and oceans.
Of course, in stating these primary risk factors, one cannot ignore property damage immediately below the cleaners or at the adjacent properties where contamination has migrated. And last but not least, a regulatory agency can bring a third party claim against a dry cleaner to cleanup contamination to the lowest of levels, but in general the primary factors presented apply.
So, how can one determine whether or not a threat exists or is present to human health and/or the environment? We have to determine if the release has reached either people or the environment.
The most common way people could be affected by a release of dry cleaning chemicals is through ingestion and inhalation of the chemical. These routes of exposure are called exposure pathways. The common ingestion exposure pathway would be drinking contaminated water and the common inhalation exposure pathway would be breathing contaminated air. Breathing contaminated air used to focus on the volatilization of organic chemicals while taking a hot shower or bath where contaminated water was used. Today, almost all inhalation exposures are focused on breathing air that is contaminated by the off gassing of volatile organic compounds from soil and groundwater present beneath a dry cleaner or the adjacent impacted properties.
To determine whether these two primary exposure routes (drinking contaminated water or breathing contaminated air) could be impacting people, one needs to determine whether people are drinking or could drink contaminated water in the general area of the dry cleaner. This can be determined by identifying drinking water wells in a ½-mile or 1-mile radius of the site. In most areas, water wells are recorded and tracked by state and local agencies, but this isn’t always the case. Sometimes in older or more rural settings, door to door canvassing must be conducted to determine if drinking water wells are present around a dry cleaning establishment.
To determine whether people might be breathing contaminated air, one needs to determine what residential structures and commercial buildings are located near the release of the chemicals. Residential receptors are the greatest concern because the cleanup levels will be most stringent in protecting children and adults that are considered to live at home 24 hours per day, seven days a week. People working in nearby commercial buildings are also of concern, but the cleanup levels reflect exposure over an eight hour workday, five days per week. Generally speaking, the closer a dry cleaner is to residential and commercial buildings, the greater the concern for exposure of Perc to people.
Following the determination of the ingestion and inhalation exposure routes, the cleanup costs can next be ranked by determining whether or not groundwater is contaminated. Generally speaking, if groundwater is contaminated at a site the cleanup cost could increase from three to 10 times the cost of cleaning up a site where only soil is contaminated.
Other factors that affect the cost of cleanup include the geologic setting where the dry cleaner is located. Is the site underlain by rock or sediments like sands, silts and clays or bedrock? If the dry cleaner sits on bedrock, is the bedrock limestone where groundwater could flow readily through joints and fractures versus very tight and well consolidated bedrock? If the site is located on top of sediments, one needs to know the type of sediments. Sands are more porous than clays and contaminated water can move through sands more easily. While this factor can result in a more extensive environmental problem, the cleanup may be conducted less expensively because the contamination within the soil and water can be removed fairly easily. In tight soils, the contamination may not spread as far or as fast, but pulling contaminated water and air from clays is quite difficult. Imagine sucking on a straw that is inserted into sand or clay, which medium would be easier to draw through?
To put some of this discussion into perspective consider the few generalities. Contamination in the Central Valley of California has been such a big issue for the past few decades because people use the groundwater extensively and the high capacity well pumps can pull contamination into the wells from great distances and across the various aquifers and depths.
Contamination in desert communities may not encounter the groundwater at all and the focus may be on determining how far down the contamination has gone. In several instances we’ve been able to obtain site closure by removing soil down to five and ten feet.
In summary, while it is impossible to know how much a site will cost to cleanup, with some understanding of the physical setting, we can develop some rough numbers which may make you sleep better, or not.
With over 20 years of experience, Steve Henshaw holds professional geology registrations in numerous states. As President and CEO of EnviroForensics, he serves as a client and technical manager on projects associated with site characterization, remedial design, remedial implementation and operation, and litigation support and insurance coverage matters. He has acted as Project Manager or Client Manager on over 200 projects. These projects have included landfills, solvent and petroleum refineries, foundries, metal plating shops, food processors, wood treating facilities, chemical manufacturers and distributors, mines and quarries, heavy equipment manufacturers, computer manufacturers, and transporters. He has experience in a variety of geological settings including soft sediments, fractured bedrock, glacial outwash, wetlands, and landslides. Henshaw has also conducted extensive work in environmentally sensitive areas inhabited by endangered species. His expertise includes a strong knowledge of industrial operations, past and current industry practices and procedures, and a hands-on, practical understanding of the fate and transport of contaminants in soil and groundwater. He has also served as a testifying expert on behalf of individual landowners and facility operators at several sites impacted by industrial activities and continues to provide technical and litigation support services.