Potential Liability from High-Pressure Injection of Powdered Activated Carbon
  As environmental firms take on more responsibility in the cleanup of impacted sites, it is important to understand the liability facing firms when it comes to recommending and implementing remediation approaches. Recently at a national conference, a state regulatory agency presented the results of a scientific study regarding the use of high-pressure applied powdered activated carbon (PAC) products, highlighting a potential liability with sites where PAC was high-pressure injected. According to the study, the technique of fracturing PAC-based products into the subsurface has a high probability of compromising existing monitoring wells (presumably by the injection fractures intercepting the well and irreversibly pressure-filling the well and filter pack with PAC particles).
False Positives in Monitoring Wells
 As a result, groundwater samples collected from these monitoring wells appear clean, while the subsurface may in fact remain highly contaminated. In the study, new monitoring wells drilled between the high-pressure PAC injection locations and the original monitoring wells indicated that >72% of the original monitoring wells were not reading the true conditions of the treated subsurface due to the effects of the high-pressure applied treatment upon the original wells themselves. This calls into question the efficacy of this remediation technique and the validity of data collected at high-pressure fractured PAC treated sites.
Potential Liability Facing Environmental Firms
Given the potential liability that environmental firms face for claims of negligence, negligent misrepresentation and violation of state and federal environmental statutes, firms employing high-pressure PAC injection techniques and/or signing reports containing representations and conclusions based on this technique of fracturing PAC products should be very cognizant of this study. Regulators may “close” a site based upon data from monitoring wells. However, if the data in the wells is showing false-positive results for cleanup, when the site has not actually been fully treated, the environmental professional’s representation of the remedial performance may be called into question by land owners and third parties. This circumstance would then expose the environmental professional to potential liability related to remaining site contamination.
Key Differences Between Liquid Activated Carbon and Powdered Activated Carbon
 Not all activated carbon products are alike. As many know, carbon is used in many processes including water purification, air purification, purifying sugar cane, and even in applications of nuclear medicine. Its use dates back as far as 2000 B.C. when Egyptian cultures employed carbon for purification and medical purposes. Until the introduction of PlumeStop Liquid Activated Carbon (LAC) in 2014, the use of activated carbon for remediation had been limited to powdered activated carbon (PAC) suspensions with average particle size of >30 µm, which is impossible to flow into most geological settings as the average pore throat diameter of aquifer materials is <5 µm. Instead, applying PAC suspensions to the subsurface required expensive and often random high-pressure fracturing of the formation.
Activated Carbon the Size of Bacteria (1-2 µm) vs. >30µm
In contrast to PAC, PlumeStop is composed of activated carbon milled down to the size of bacteria (1-2 µm) suspended in water through the use of unique organic polymer dispersion chemistry. Employing PlumeStop, remediation experts can now effectively disperse purifying activated carbon into contaminated aquifers through simple gravity feed or by flowing the material under low pressure into the subsurface, where it removes pollutants from groundwater on contact and stimulates their rapid degradation in situ. Our product development team has developed a list of frequently asked questions (FAQs) to assist in identifying key differences between LAC vs. PAC.
|
National Regulatory Changes and Practical Assessment Strategies for Navigating the Vapor Intrusion Pathway
