Re: [CPEO-MEF] TCE in Moffett military housing area

[StellaVB@aol.com]

It is my understanding that there are three general in situ
biodegradation methods of treating chlorinated solvent contaminants in
groundwater: aerobic biodegradation slow to treat PCE/TCE), anaerobic
dehalogenation (breaking down TCE/PCE to slow to treat so-called
'daughter products') and then
aerobic, co-metabolic biodegradation which air is injected into the soil
using horizontal wells to establish and maintain aerobic conditions.  By
injecting a small amount of methane or propane along with the air (about

2-5%  by volume) this serves to feed certain kinds of aerobic microbes
which release an enzyme into the groundwater system as they feed on the
methane/propane.  This enzyme then has the unique ability to chemically
react with TCE/PCE to convert them directly to carbon dioxide, water and
chloride
ion without the generation of the 'daughter products'.  IF these
daughter products are already present from prior anaerobic conditions,
they too are treated by the same enzyme to convert them chemically to
carbon dioxide, water and chloride ion.  Even vinyl chloride is rapidly
bidegraded and will not persist in the subsurface under the such
conditions established.  As a gas, it will rapidly flush out of the
groundwater system.

What I just described above was utilized here in Pinellas County,
Florida.  The site was contaminated with chlorinated sovlents which had
leaked out of 55-gallon drums of mixed solvents waste that had been
formerly buried on the site.  Some time in the past, the drums were dug
up and taken to a secure  landfill, but the material which had already
leaked from the drums was left in place.  As a consequence, there were
two major plumes of mostly TCE/PCE and a little touluene at the 4.5-Acre
site.

For 7 years, the DOE had been trying to address this contamination using
vertical 28 dual-phase extraction wells.  The calculated mass of
contamination removed per year totaled about 6 pounds.  There was about
200 pounds total contamination thought to be still present on
site-giving roughly 30 years to complete cleanup with the current
remediation method.  This facility (now named the STAR Center) sold the
4.5 acre area to an  adjoining land-owner who wanted his new property
cleaned up quicker than 30 years.  3 directionally drilled biosparge
wells, two of them placed in one plume parallel to each other and the
third one placed in the second plume was implemented and cleanup appears
to have successful been completed in 3 months.  There has been a year
waiting period to see if this problem is solved.  I have put in a phone
call to the DOE pm-David Engels (sp?) to see what the status of this 4.5
acre site is today (my understanding is that
it  is 'still clean) and will post this information when I receive it.

I am aware there will be 'naysayers' in the community regarding this
type of remediation but to those who are truly concerned (stakeholders)
about getting their sites cleaned up in a much more effective and timely
manner. I'd say a 3 month vs. 30 years hits that agenda.  I am only
aware of STAR Environmental, Inc. doing this type of work though there
may be other concerned environmental companies utilizing the same type
remediation  methods.  I am not an 'extremely competent fluid dynamics
versed mechanical engineer' so I cannot give the proper answers to
anyone who is interested in this technology.  I can tell you to
contact:  STAR Environmental, Inc. in Chadds Ford, PA @ 610.558.212 and
talk to someone there.  I learned of
them because of the Pinellas site, my moving to Florida, the live fire
training taking place just north of me in Ocala National Forest and my
own frustration over the squabbling done at sites about which method to
use (which waste RAB members time and taxpayers dollars).  Though I'm
sure this method is not cheap to establish (I can hear the complaints
now), it would seem to me that it saves much more money due to the time
factor and in the end protects the  health (and lawsuits) of and by
citizens.

In closing I would like to thank the Governor of Florida, Jeb Bush, for
his part in utilizing this technology that other sites around the nation
are not.  Here in Florida, due to our own low gw table, this remediation
is a
blessing in disguise on many levels.

Stella

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~