Category: Site Investigation and Remediation

Enhanced Reductive Dechlorination It’s A Matter of Give and Take

Posted on by Jeff Carnahan

Written By: Steve Henshaw, President and CEO of EnviroForensics in collaboration with Keith Gaskill, Senior Geochemist, EnviroForensics

As seen in the February 2014 issue of Cleaner & Launderer

PDF Version

When scientists evaluate how to best cleanup groundwater that has been contaminated with chlorinated solvents, such as perchloroethylene (perc) from a drycleaner or trichloroethene from a manufacturing facility, the option of in-situ treatment is considered.  If the subsurface conditions are favorable, in-situ (or in-place) remediation can have a lot of advantages to other remedial alternatives.

One of the most common in-situ approaches is the use of bioremediation and reductive dechlorination.  The advantages to using in situ bio-remediation or reductive dechlorination technology are that a liquid can be injected into the subsurface using a small drilling rig while there is minimal business interruption. There is no need for an active treatment system involving a trailer or stationary shed with electrical pumps, compressors and treatment tanks.  There is no trenching for conveyance lines and electrical wires.  There are no costs for routine operation and maintenance, electrical power, or monitoring telemetry.  Other advantages to using in situ bio-remediation are that the product is relatively inexpensive, readily available and it is safe and easy to handle.  In-situ treatment is particularly favorable when remediating a contaminated groundwater plume that has migrated away from the Site where the release occurred.

Continue reading “Enhanced Reductive Dechlorination It’s A Matter of Give and Take”

Vapor Intrusion – A Concern, but an Easy Fix

Posted on by Jeff Carnahan

Written by Stephen R. Henshaw, President and CEO of EnviroForensics & PolicyFind

As Seen in the January 2014 issue of the Cleaner & Launderer

PDF Version

Those of you who have read my past articles, have heard me speak, or have ever looked at EnviroForensics’ website, know that we specialize in helping dry cleaners work through the regulatory and insurance maze of investigating and remediating soil and groundwater impacts caused by the release of percholoroethene (PCE).  The EnviroForensics team takes pride in helping to solve environmental problems for the dry cleaning industry; and over the past 18 years, we have helped more than 400 dry cleaners.

So much has changed since I started working with dry cleaners.  The laws and regulations enforced by the regulatory agencies, the cleanup technology, and the perceived human health exposure of vapors, known as vapor intrusion, are continually changing and evolving.   It seems that the only constants are that dry cleaners are targets and continue to be blamed when PCE is found in soil and groundwater. PCE is considered a risk to public health, contaminated soil and groundwater makes property transactions difficult to complete, and cleaning up PCE in soil and groundwater is expensive.  Oh, and old CGL insurance policies continue to be one of the saving graces for dry cleaners when faced with the daunting reality that they have been named as a party responsible for PCE contamination. Continue reading “Vapor Intrusion – A Concern, but an Easy Fix”

Selecting An Environmental Consultant; What Firm Is Best For Your Situation

Posted on by Jeff Carnahan

Written By Stephen R. Henshaw, P.G., President & CEO, EnviroForensics
As seen in the May 2013 issue of the Cleaner & Launderer

Selecting an environmental con­sultant can be a daunting task and for small business owners that do not have day-to-day exposure with soil and groundwater contamination it’s very difficult to know the difference between consultants. This article is meant to shed light on the differences between environmental consultants and to present the different methods for selecting an environmental con­sultant. It’s my goal to show people that selecting the right consultant for your situation is a very important decision and should not be taken lightly. If a business person doesn’t know that there are differences be­tween environmental consultants, countless hours and dollars may be wasted, projects could drag on and site closure could be a distant glimmer.

This article will go through some of the selection and screening meth­ods that small business owners use when selecting an environmental consultant to address environmental liabilities.

Continue reading “Selecting An Environmental Consultant; What Firm Is Best For Your Situation”

Practical Approaches for Remediation of VOCs in Clayey Soils

Posted on by Jeff Carnahan

Written by Stephen R. Henshaw, P.G., President & CEO, EnviroForensics
As seen in the April 2013 issue of Cleaner & Launderer

The question is often posed, “How much will it cost to clean up contamination at a drycleaner?”  Invariably the answer is, it depends.  Factors that come into play include, but are not limited to, the concentration of VOCs present in the subsurface, whether or not the groundwater is impacted, the depth to groundwater, how far the contamination has spread, whether the cleanup will be focused on residential or commercial land use, and the type of geology and stratigraphy underlying the site.  This article focuses on how clayey soils affect cleanup considerations.

Clay is a naturally occurring material composed of very fine-grained particles.  Clayey soil is a term used for soils containing at least 30% clay.  When clay comes in contact with liquids, it swells and becomes plastic.  When it dries out it shrinks and cracks. Clay is very porous and can hold liquids (e.g. water) between the fine-grained particles, but it is not very permeable, meaning liquids won’t move through the material rapidly.  Clayey soils can hold water and moisture, but water does not move through it very fast.  Likewise, air doesn’t move through clayey soils very well.

Continue reading “Practical Approaches for Remediation of VOCs in Clayey Soils”

PREFERENTIAL PATHWAYS; UNDERGROUND PIPES AND UTILITY LINES CAN BE CONDUITS FOR THE MIGRATION OF CONTAMINANTS

Posted on by Jeff Carnahan

Written by Stephen R. Henshaw, P.G., President & CEO, EnviroForensics

As seen in the March 2013 issue of Cleaner & Launderer

PDF Version

You can imagine that if wastewater is discharged into a sewer line with cracks in it that the wastewater could contaminate the soil and groundwater.  After all, sewer pipes can be very old and made of a variety of material such as transite, clay, concrete, plastic, or steel.  Of course, leaks are not uncommon in sewer lines.  Sewer lines can crack or break, they can corrode, or the couplings, where pipes are fitted together, can leak and result in “point source” areas of contamination.  Sags and low points are common when a sewer line goes underneath streets and structures.  These low areas can result in sediment and dense chemical liquids pooling in these sag points, resulting in contamination source areas.  Sewer pipes can become blocked and clogged and result in backups that can create points of leakage. 

Historically speaking, sewer pipes were not designed to be leak proof.  The first sewers were essentially brick lined tunnels.  Later, short sections of clay pipes were coupled together to create long lengths of sewer.  The clay sections consisted of a male end and a female (bell) end and the lengths of clay pipe were coupled together.  Gaskets were hopefully placed in the bell end to minimize the leakage, but of course those gaskets would degrade over time.  Transite pipes and concrete pipes similarly had male and female ends and were coupled together.  Continue reading “PREFERENTIAL PATHWAYS; UNDERGROUND PIPES AND UTILITY LINES CAN BE CONDUITS FOR THE MIGRATION OF CONTAMINANTS”

Risk Based Closures Require Long Term Monitoring; What is the True Cost of Implementing Institutional Controls?

Posted on by Jeff Carnahan

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

As seen in the February 2013 issue of Cleaner & Launderer

PDF Version

 I’ve been involved with a number of environmental site cleanups where the chemicals in the soil and groundwater were not believed to be a significant threat to human health or the environment.  There are a number of situations where this scenario applies, such as an old light-industrial manufacturing site in the middle of a blighted industrial urban area.  In such a case, the surrounding sites were identified as being the cause for the majority of the groundwater impacts in the near vicinity and if we were to remediate the groundwater beneath our site, the contamination from neighboring sites would continue to migrate beneath our property essentially re-contaminating it.  Another example would be when a site exhibits soil impacts, but the groundwater does not indicate significant impacts, even though the contamination has persisted for 20 plus years.  The site is capped with an asphalt or concrete parking lot and building.  

There are many, many scenarios where it would appear that a risk-based closure with no physical remediation is warranted.  The assumptions are that the site has been adequately characterized so the extent of the contamination is known in the soil and groundwater.  The contamination is not reaching the groundwater and that an inventory has been conducted to determine that no wells are located nearby and that no person is drinking from nearby wells. Finally a risk evaluation is conducted to determine what pathways might exist where by contaminants from the site could have an adverse impact on people or the environment.  That is to say that no person or animal (including wildlife and marine organisms) would come into physical contact with the contamination, breathe vapors emanating from the contaminants, or drink contaminated water.   Continue reading “Risk Based Closures Require Long Term Monitoring; What is the True Cost of Implementing Institutional Controls?”

Source Removal: The Key to Effective Site Remediation

Posted on by Jeff Carnahan

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

As seen in the January 2013 issue of Cleaner & Launderer.

PDF Version

Risk-based cleanup approaches to obtain environmental site closures are becoming more and more acceptable to the regulatory agencies.  In general, if it can be demonstrated that contaminants left in soil and groundwater won’t cause an adverse impact to people or the environment (animals and their habitat), they may be able to be left in place and allowed to degrade over time.  To evaluate risk-based cleanups, the exposure pathways need to be indentified and evaluated.  Exposure pathways are the avenues or ways in which the contaminants could affect human health or the environment and include ingestion or uptake of water, direct contact with water or soil, and the inhalation of vapors or dust.

Risk assessments are now a routine part of determining appropriate cleanup approaches.  If the risk assessment can demonstrate that no one is drinking untreated groundwater (well water) in the area, that pathway is considered closed and can be checked off in terms of its risk to human health and the environment.  More specifically, the assessment could state the groundwater ingestion pathway is incomplete and there is the risk for cancer due to exposure to contaminants in groundwater is less than1 in 1,000,000.  The other exposure pathways are evaluated in a similar fashion to evaluate the likelihood that an exposure pathway is or is not complete.  Continue reading “Source Removal: The Key to Effective Site Remediation”

Using Conceptual Site Models To Direct Investigations and Cleanups

Posted on by Jeff Carnahan

Written By Steve Henshaw, President & CEO, EnviroForensics

As seen in the October 2012 issue of Cleaner & Launderer.

PDF Version

In the early 1980’s, when the field of environmental consulting was just starting, the United States Congress was busy developing guidance documents to direct how site investigations and cleanup would be conducted.  The science was new and there wasn’t a lot of data to draw from with respect to how chemicals “behaved” in the subsurface.  Everything from our understanding of the fate and transport of chemicals in groundwater to our ability to remediate and contaminated aquifers was in its infancy. Continue reading “Using Conceptual Site Models To Direct Investigations and Cleanups”

Risk Based Closure; What Is It and Is It Right For Your Situation?

Posted on by Jeff Carnahan

Written by Steve Henshaw, P.G., President & CEO, EnviroForensics, in collaboration with Jeff Carnahan, L.P.G., Vice President – Director of Technical Services, EnviroForensics
As seen in the June 2012 issue of Cleaner & Launderer

PDF Version

More and more often, people are talking about “Risk Based Closures”.  It sounds ominous and complicated, but because so many people are throwing the term around, it seems like everyone is supposed to know what it is.

In general terms, a “Risk Based Closure” is nothing more than the process of getting the regulatory body that is overseeing the cleanup of a contaminated property to agree with the responsible party that the contamination on the property no longer poses a risk to human health or the environment.  The result of this process is the issuance of a letter by the regulatory agency stating that “No Further Action” is necessary on the property.

“Risk Based Closures” are nothing new and have been used for decades.  After all, in most instances, some amount of contamination will still remain after remedial actions have been completed.  It is unrealistic, if not impossible to remove every molecule of contamination at a site. Continue reading “Risk Based Closure; What Is It and Is It Right For Your Situation?”

Do You Know Your Company’s Most Valuable Assets?

Posted on by Jeff Carnahan

Written by Steve Henshaw, P.G., President & CEO, EnviroForensics
As seen in the May 2012 issue of Cleaner & Launderer

PDF Version

When executives talk about a company’s assets, they generally refer to people, property, buildings, equipment, clients, job contracts, and intellectual property.  I’m sure there are more, but how often do executives think that some of their greatest and most valuable assets are old insurance policies that were purchased 10, 20, even 50 years ago?  It’s true – old insurance policies, normal commercial general liability (CGL) insurance policies, that were purchased to protect and cover against claims of bodily injury, other physical injury or property damage and to protect your businesses against incidents that may have occurred on your premises or at other locations where you conduct business could be worth millions of dollars.

If you already know this, then I’m sure you have all of your old insurance policies stored safely and securely.  You also have a summary that shows the coverage by year, along with the names of the insurance companies that issued the coverage, the policy numbers and the policy limits.  If you don’t have this information safely stored, protected from fire and water damage, then you should read on. Continue reading “Do You Know Your Company’s Most Valuable Assets?”