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Re: GBlist: Healthy Homes?-2




In a message dated 7/22/97 11:49:29 AM, you wrote:

<<
This still leaves the problem of cleaning up a contaminated area

primarily soil floored crawlspace and perimeter foundation areas of the

house. Given the fact that you do not want to introduce any more

potential contaminants and you want to reduce the impact of existing

conditions on the sensitized person what options would be preferable?



- Cleanup and sterilization of area: what methods should be employed and

if there is still the potential for air from a basement/crawlspace area

to infiltrate the main living area of a house how can you ensure its

quality over time?



- Isolation of basement/crawlspace area from main living area: how can

this be done effectively (recommended insulating materials and sealants)

and what hvac requirements would an isolated basement/crawlspace area

need.

>>

Hi John,

Back in the late 1980's I did some research for the EPA on radon dynamics in
houses in Tennessee.  Several of the houses in the study had crawlspaces.
 Here's my thoughts:
	1)  in a less than 5 mph breeze all crawlspace vents are air intakes (air
entering crawl from outside and moving into the occupied portion of the house
powered by stack effect or mechanical equipment)
	2)  it is very difficult to make an airtight barrier at the floor between
the crawl and the house (more difficult if air handling ducts run in the
crawl)
	3)  air from the crawl can be kept out of the house by managing the air
pressure relationship between crawlspace air and house air (depressurize the
crawl or pressurize the house)
	4)  depressurizing the crawl is usualy easier and more resistant to occupant
interference
	5)  better yet, roll a polyethylene ground cover out on the crawl earth and
depressurize beneath it.  It takes far less air (and electricity) to
intervene in the transport mechanism this way
	6)  radon makes a wonderful tracer gas because it can be measured at 1 part
in ten to the 19th with charcoal canisters or continuous monitors
	7)  one of the Tennessee houses had been treated with a termiticide by
injection beneath a slab.  we measured for the active ingredient in the house
before and after a soil depressurization system was installed and got a
factor of 5 reduction.  Oak Ridge National Labs later did a follow-up study
in ten houses which had similar results.

Mike and I are currently beginning a difficult remediation in a Manhatten
brownstone where someone spilled at least 2000 gallons of fuel oil.  The
decision has been made to leave the soil and foundation in place.  Collection
wells have been sunk to ground water and fuel oil is being pumped from them
daily.  So far a couple thousands gallons have been pumped.  We will be using
soil depressurization methods to prevent the entry of fumes.  We are
experimenting with degreasers we have used as part of low impact cleaning
systems in schools systems to clean up the concrete slab and stones
contaminanted by oil.  There is an MCS occupant in one of the affected
buildings.  I'll keep you posted on what we discover.  I'd appreciate any
ideas you have too. - Terry Brennan
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