A stinky situation is brewing in South Burlington.
On June 28 and 29, VTrans will replace a culvert liner on Dorset Street near Kennedy Drive. The technique causes a strong odor, like a very pungent epoxy or paint. The state says there is no health risk.
So reads Vermont WCAX news’ almost light hearted report .The situation may be a little more involved. Although the Vermont.gov. website posted a strong smell and odors warning in practically the same don’t worry about a thing language.
This culvert rehab process known as trench-less repairing has in the past raised some legitimate health concerns. Cured-in-place-pipe (CIPP) styrene based technology is a burgeoning repair method for culvert and recently even drinking water pipe rehabilitation. A lining tube is saturated with a styrene based thermosetting resin and installed into the pipe. Subsequent curing with a heat source results in a pipe within a pipe.
No digging, fewer delays and perhaps no problems if done carefully.
The state of Virginia within the last two years revised its procedures and lifted a ban on this repair. In 2007 it was found the process could result in contamination of soils and receiving waters from the release of unacceptably high levels of styrene into the environment.
Water samples collected from pipe outlets at five of the seven CIPP installations showed detectable levels of styrene. Styrene concentrations were generally highest in water samples collected during and shortly following installation. The maximum duration that styrene was detected at any site was 88 days following the CIPP installation.
Although the sites in this study were not directly linked to sources of drinking water, styrene levels at five sites were higher than the U.S. Environmental Protection Agency's maximum contaminant level for drinking water of 0.1 mg/L.
Certain measurements were also found to exceed the concentration required to kill 50% of several freshwater aquatic indicator species.
Possible causes included: poor installation that did not contain styrene condensate
uncured resin escaping from the liner
insufficient curing and a degree of permeability in the lining.
Virginia’s substantial modifications to VDOT's CIPP specifications included;
An inspector training program
Increased project oversight
Water and soil testing prior to and after CIPP installation.
If this becomes a wide-spread practice, it is almost guaranteed to be mismanaged in some locations. Plastics continue to de-gas well after they are cured; and styrene is not a particularly stable plastic, so it would be likely to degrade at a relatively rapid rate. I’m no expert, but my guess is that there is probably no point in the life of styrene when it is not sloughing-off toxic molecules. Perhaps a lurking chemist could weigh-in on this?
I am surprised that the practice is being used in places to stabelize pipes carrying drinking water. Even if the styrene is applied externally (which it doesn’t sound like it is) and, in theory, wouldn’t come in contact with the drinking water, if there are cracks in the conventional piping it is likely that the water flowing through that piping will have at least a passing contact with the styrene.
Which one of these words doesn’t belong?