Re: Solvent-laden rag transport

Mon, 12 Feb 1996 09:17:57 -0500

I have some information in response to part of Bill Bilkovich's first
question - What kind of laws were passed in MN to promote centrifuge
use? I obtained this information a few years ago while searching for some
information needed to correct an erroneous statement in the EPA Design
for the Environment (DFE) case study write-up on John Roberts Company
experience with centrifuging shop towels and moving to lower vapor
pressure cleaning solvents. The erroneous statement in the EPA case
study was that (approximate quote) "...the solvents from the shop towels
were discharged by the laundries into the sewer system in such quantities
that the lower explosive limits were exceeded."

This statement appeared incorrect to me for two reasons. First, I had
never heard this from Jeff Adrian of John Roberts in several presentations
on his company's experience. Second, had this been the case, we
probably all would have heard and heard about a big bang in Minnesota.

I called Jeff and he referred me to someone at the local water and sewer
authority. (I am certain I could find the name and phone number of the
person I spoke to if anyone needs it.) This person told me more of the
history of the problem. In the early 1980's there was a labor dispute which
led to a strike and the eventual hiring of replacement workers at a number
of the larger printers in Minnesota. (Minneapolis, I believe to be more
specific.) New workers at several printers began to use large quantities of
"type wash" (a very volatile and aggressive solvent previously used only
for certain very specific and infrequent cleaning tasks) for routine blanket
and roller washing. This led to a heavy loading of this solvent in dirty
shop towels which were sent to laundries. The laundries in turn began to
discharge "large" quantities of this solvent in their wastewater into the
municipal sewer system. (I do not believe this practice led to any truck
explosions or flying sewer covers as no one told me about either of these
occuring.) This went on for several (perhaps 5 or more) years during
which time there were frequent complaints from sewer workers about
uncomfortable or dizzying amounts of solvent, and pedestrians about
odors from the sewer system. The sewer authority had a rule that
monitors in the sewer system were never supposed to show more than 10
percent of the LEL on any one reading and never supposed to show more
than 5 percent LEL on any two consecutive readings. The solvents from
the laundries from the shop towels were causing this rule to be broken. I
do not recall the details of how the source of the problem was traced back
to the laundries and the printers, but eventually it was. This led to some
work practice changes at the printers - centrifuges and less volatile
solvents for cleaning, and probably some work practice changes at the

I am not aware of any law adopted in MN to encourage the use of
centrifuges. I think the use of a centrifuge was one of the steps identified
for solving the sewer odor problem and therefore it was generally
encourage or facilitated (i.e., not prohibited when someone asked for a
permit to install a centrifuge). I am also not aware of any law passed in
Minnesota prohibiting the laundering of solvent laden shop towels. I
believe that the printers in MN still send their dirty shop towels to
laundries, but with a lot less solvent in them than they did in the early to
mid 1980's.

I hope some of the printers or others in MN will provide more information
on the current practice and regulations.



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