Environmental Enlightenment #212
By Ami Adini - Reissued July 17, 2017

This is a SHORT, LIGHT and SIMPLE newsletter. Its purpose is to rekindle in the initiated terminology they have once learned, and enlighten the uninitiated on terms they may have heard but never knew the meaning of.

Power of Simplicity
The EPA’s Citizen’s Guide to Cleanup Technologies

Series 11: Vapor Intrusion Mitigation

See our Newsletter, Environmental Enlightenment #200, for introduction to one highly valuable, plainly written series of Citizen’s Guides published by the EPA at http://www.clu-in.org/products/citguide

With this issue we introduce the EPA’s Citizen’s Guide to Vapor Intrusion Mitigation. You can reach it through the hyperlink under the blue header below


is practiced by intruders who intrude.

To intrude is to come in rudely or inappropriately; enter as an improper or unwanted element.

Copyright: gnurf / 123RF Stock Photo

Intruders are generally not welcome: bugs, pests, noxious vapors, explosive gas, radiation, viruses, and the burglar next door, to name a few.

In Los Angeles, vast developments sit on formations loaded with methane (an odorless, colorless, toxic and explosive gas), and measures are implemented to block the methane from intruding into or accumulating within spaces.

Toxic vapors originate from spills of volatile industrial chemicals into underlying soils. The chemicals emit vapors that travel sideways from the source area.

(DNAPLs stands for Dense Non Aqueous Phase Liquids. It means liquids that are not water and heavier than water. Dry cleaning solvents are one example.)

DNAPL migration

The image below shows a case in which the leaking contaminant has reached groundwater and is migrating far with the movement of the water. Being carried away, it volatilizes (partitions) from the water and moves up toward inhabited structures.


In other cases, the vapors will travel laterally in the form of subterranean “clouds.”

Vapor Intrusion

One practical way to know if vapors are intruding is by placing samplers inside the spaces of interest.

This procedure demands multiple sampling episodes because different spaces are ventilated at varying rates of ventilation, because rates of intrusion vary with the seasons and during days and nights, and the integrity of slabs, floors and walls changes over time.

To overcome these variables, scientists developed theories that attempt to predict rates of intrusion by measuring the levels of the volatile chemicals in the subsurface soils and calculating probabilities of intrusion to the inhabited places.

These models are highly theoretical.



Copyright: sararoom / 123RF Stock Photo

Further, the risk models estimate levels of risks in terms of the number of people that are allowed (by the model) to contract cancer over time. For example, one such number for residences is one in a million in 70 years.

Source: Wikimedia.org

The models are theoretical, but in the absence of better tools they are used in the evaluation of the risks to public health and provide thresholds numbers for regulatory demands to perform cleanup projects.

Models of risks and the theories behind them develop over time.

At the end of the day, a practical tool could be direct sampling of the indoor air in multiple events, comparison of the results with levels of same chemicals in the outdoor environments, and implementation of mitigating means where risks are suspected.

subsurface systems

Go to the EPA’s Citizen’s Guide to Vapor Intrusion Mitigation at http://www.clu-in.org/download/Citizens/a_citizens_guide_to_vapor_intrusion_mitigation_.pdf for the rest. It is simple and fun to read.

You can find past issues of our "Environmental Enlightenment" at amiadini.com Wealth of information about environmental site assessments in the real estate transactions and issues concerning assessment and cleanup of contamination in the subsurface soil and groundwater.

Call me if you have any questions. There are no obligations.

Ami Adini Environmental Services, Inc.
Environmental Consultants & General Engineering Contractors
California Lic. #1009513 A B HAZ ASB
818-824-8102; mail@amiadini.com

Ami Adini is a veteran environmental practitioner with over 40 years of experience. He carries a Bachelor of Science degree (B.Sc.) in Mechanical Engineering including academic credits in Nuclear and Chemical Engineering and postgraduate education in these fields. His career includes design and construction of nuclear plant facilities, chemical processing plants and hazardous wastewater treatment systems. He is a former California Registered Environmental Assessor Levels I & II in the 1988-2012 registry that certified environmental professionals in the assessment and remediation of environmentally impacted land, and a Registered Environmental Professional (REP) since 1989 with the National Registry of Environmental Professionals (NREP). He is a California Business & Professions Code Qualifying Responsible Managing Officer (RMO) in the General Engineering Contractor classification with Hazardous Substance Removal and Asbestos certifications, and president of AMI ADINI ENVIRONMENTAL SERVICES, INC. (AAES), a general engineering contractor and consulting firm specializing in environmental site assessments, rehabilitation of contaminated sites and removal of environmental risks from real-estate transactions. (Contact Ami for a complete resume.) AAES provides practical solutions to environmental concerns using the highest standards of ethics and integrity while providing its clients with maximum return on their investments.