Re: suggestions to agitate stream flow?

Michael, thank you for your input.  We only did a very preliminary survey
of the site but let me answer your questions as best I can.  Please see
below.  I hope you don't mind if I BCC'd you on this as I don't want the
spam bots to get your proper email addy.  Thank you again for your kind
help.

On Thu, 20 Nov 2003, Herman Family wrote:

> Would it be possible to get a little more information on this problem?  It
> sounds interesting, but it appears to have some pretty serious constraints.
> Where are the VOC's coming from?  Existing ground water contamination,
> natural sources, or a current effluent stream?

VOC's are coming from runoff from a big landfill that was used for
disposal of a number of things about 40 years ago until the mid-1980's.
The site we are looking at had nuclear reactors in operation at one time
and TCE was one of the "miracle solvents" touted back in the 1960's that
was used extensively in the operations and maintenance of these reactors
until some of the nastier health effects became known about it.  Also, PCE
was used a lot and dumped into this landfill along with TCE.

> What is the stream flow rate and dimensions?

We haven't determined actual flowrate yet as this is only in a very
preliminary stage but the water is moving very slowly in this particular
stream, about 1 mph or less.  The stream dimensions vary but I'd guess an
average width of about 6 feet and average depths of about 3 to 4 feet.

> What is the VOC loading and composition you need to mitigate?

We haven't measured the VOC concentrations yet and will collect samples
next week, weather permitting.  But previous studies have shown TCE
concentrations of 5 to 25 ppm in the water, depending on how much runoff
comes down from the landfill from precipitation events.  EPA limits TCE
and PCE to 5 ppb in water.  Of course, the limits are much less stringent
in the air if we can strip these VOC's to the atmosphere.  We would like
to get the concentrations down to 5 ppb or less.

> Are there other locations besides the stream which could be used for the
> mitigation?  Could you just fill a few porous bags with activated
> charcoal and some rocks and make a filtering dam?

The activated charcoal in bags is one of the ideas we have under
consideration.  Of course, these bags would have to be replaced
periodically as sorption sites on the charcoal get filled up, which is why
it would be desirable to come up with a solution that we can completely
forget about once implemented, other than regular monitoring of the water
for VOC's.

The stream is in a heavily wooded area.  About 1/2 mile downstream,
there is no measurable TCE or PCE.  It has been argued that this stream is
not a problem because the VOC's get stripped out in 1/2 mile anyway but
EPA is intent on having something done about this section of stream.  We
just don't want to spend a lot of money on such a small section of stream
if possible, just a waste of tax dollars it would seem.  Because of the
trees and other flora, I don't think we could get a lot of equipment up
and running there without a high price tag.

There are other streams on site besides this one with the same problem.
Those streams of course have different dimensions and different flow
rates, as well as different surroundings.  But I think the stream I'm
describing is the hardest one to do anything with, despite the other
streams having VOC's as well as radioactive contaminants in the water.

> There are some resins which can remove VOC's from water or air without too
> much trouble.  They come in bead form and could be placed into your stream
> between screens or in bags.  A little microwaving will remove the VOC's
> later on.  If this is worthwhile, I can probably come up with a source for
> them.

Absolutely!  If you could please steer me towards some sources, I'd very
much appreciate it!

> One would hate to develop and install a system only to have it made obsolete
> when the paint can up stream was removed.

I wish we COULD just remove the point source, i.e., the landfill.  But
this is, of course, not practical or economical.  At this point, the
contaminationhas leached into the ground to a significant depth below the
ground surface.

> Michael
>
> "Robert Kim" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
> > On Wed, 20 Nov 2003, Mike Halloran wrote:
> >
> > > Yes, but the only head available is the hydraulic gradient of the stream
> bed.
> > > And because the grade is not very steep, the entry to a narrow vertical
> channel
> > > would become quite long.
> > >
> > > Me, I'd try to build the stream bed up, with concrete or plywood, so the
> stream
> > > becomes wide and shallow and the narrow channel is horizontal.
> > >
> > > That would also allow the sun to interact with the VOCs, by increasing
> the
> > > water temperature and raising the evaporation rate, and by exposing them
> to UV
> > > radiation and the possibility of reacting chemically to become something
> else.
> > >
> > > The plywood is also degradable, so the apparatus will eventually
> decompose and
> > > flush itself away.
> >
> > Thank you, Mike.  That's a pretty good idea you have.  Now the sunlight
> > into that area is low since it is heavily wooded but the increase in
> > surface area to enhance evaporation could help a lot.
> >
> > I greatly appreciate your input on this.
> >
> > Bob