August Mack Newsletter | April, 2018

Fate and Transport of Hydrocarbons: Contamination and Its Relationship to Our Lives
by Scott Kalemba and Alex Grissom

Public concern over the effects of chemical releases into the environment through human activity has grown steadily since the inception of the U.S. EPA on December 2, 1970.

What happens when a chemical is released into the environment? It diffuses, disperses, adsorbs, reacts, and/or changes state. The existence of contaminated sites may result in the release of chemicals into air (via volatilization and fugitive dust emissions), surface water (from surface runoff/overland flow and groundwater seepage), groundwater (through infiltration/leaching), soils (due to erosion - including fugitive dust generation/deposition and tracking), sediments (from surface runoff/overland flow), and biota (due to biological uptake and bioaccumulation). Contaminants released into the environment are controlled by a complex set of processes including transport, transformation, degradation and decay, intermedia transfer, and biological uptake. In addition, many toxic chemicals are persistent and undergo complex interactions in more than one environmental medium.

To predict and analyze this process, the mathematics of diffusion is applied to lakes, rivers, groundwater, the atmosphere, the oceans, and transport between these media. A sustainable world requires a deep understanding of the transport of chemicals through the environment and how to address and harness this process.  

Contaminant transport & fate refers to the physical, chemical, and biological processes that impact the movement of the contaminants from point A to point B and how these contaminants may be altered while they are transported. Groundwater contamination caused by petroleum hydrocarbon (PHC) spills is a major environmental concern worldwide. However, infiltration into groundwater is decreasing due to the natural attenuation processes of PHCs in the vadose zone, which acts as a safeguard of invaluable groundwater resource against contamination.

The most highly contaminated soil will be present near the release area which is referred to as the “source area”. Removal of the highly contaminated soil (source area) is more cost effective and timely, if possible. Removal of the source area is also helpful even in situations where all of the contaminated soil cannot be removed.

Beyond source area removal, many viable options are available to remediate petroleum contaminated soil and groundwater. Petroleum products such as gasoline and diesel will naturally degrade over time if the right environmental conditions and microbes are present. Bioremediation involves relying on naturally occurring organisms to breakdown or remove petroleum constituents from the contaminated area. The natural degradation of petroleum contaminants may occur on its own over time or can be enhanced by the addition of fertilizers, oxygen and other substances depending on the naturally occurring microbes in the area and the site conditions.


Scott Kalemba is a Staff Geologist for August Mack’s Closure Group located in the Indianapolis, Indiana office. Scott’s experience in Site closure includes all aspects of field implementation, soil and groundwater sampling, exposure pathway evaluation, underground storage tanks (USTs), in-situ bioremediation and evaluation, and vapor intrusion. Scott earned his Bachelor of Science Degree in Geology from Indiana University. Scott can be reached at 317.721.0693 or via email at skalemba@augustmack.com

 

Alex Grissom is a Staff Geologist for August Mack’s Closure Group located in the Indianapolis, Indiana office. Alex’s experience in Site closure includes all aspects of field implementation, soil and groundwater sampling, exposure pathway evaluation, underground storage tanks (USTs), in-situ bioremediation and evaluation, and vapor intrusion. Alex earned his Bachelor of Arts Degree in Geology from DePauw University. Alex can be reached at 317.460.4255 or via email at agrissom@augustmack.com


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