Sediment Remediation Questions

[rtkp@ptialaska.net]

I'm looking at options for remediation of marine sediment contaminated
by dioxin and metals.  If anybody has info that might be helpful
please send.  Here's the lowdown.

Ketchikan Pulp (KPC) has spent 42 years dumping effluent into Ward
Cove Alaska, a few miles from Ketchikan.  It is a shallow waterbody
with very little flow. Over the years the destruction of the ecosystem
in the cove has been pretty well characterized in studies.  Each one
showing further degradation.  Superfund screening was done, but never
followed up (politics got in the way).  The most recent reports show
that the sediment is contaminated with dioxins/furans, cadmium,
arsenic and methyl-mercury.  In addition there are many other more
acutely toxic, but shorter lived, contaminants.  Taxa in the cove have
decreased from 40 or so in the 50's to 2 in the 90's, pollution
resistant tubeworms.  Bottom sediments are generally anaerobic with
high levels of reduced sulfur, oil, grease and phenols.  Fiber mats
are present which float to the surface and out-gas Hydrogen Sulfide. 
A recent dive survey was unable to collect any samples within 1.2km of
the outfall adequate for use in a bioaccumulation study. Despite this,
transient species move through the cove.  Coho and other Salmon
species, as well as Steelhead Trout spawn in Ward Creek.  Other fish
observed in the cove include Sole and Rockfish.  Crabs and various
shellfish live at the mouth of the cove. Over the years KPC has
dredged sediment from in front of its dock to allow ships and barges
to enter.  This material is dewatered (into the cove) then trucked to
an unlined landfill bordering the cove. Leachate from the landfill
runs into the secondary treatment basins and is returned to the cove.

Now KPC is shutting down.  A cleanup is part of a US Justice
Department settlement for felony convictions of the Clean Water Act. 
The question is what could we do that won't make matters even worse? I
have real concerns over more dredging. It seems to me to be likely to
release more bioaccumulatives into the marine environment.  Are there
other removal techniques that get a higher percentage of the sediment.
 (I have thought of "dive dredge" but that seems likely to put peoples
health at risk.  Most divers I have talked to will not dive in Ward
Cove, especially if they have been there before.)  Furthermore, there
is the issue of what to do with the sediment once it has been removed.

 Non-removal would only be better if it there was a reliable way of
 containing the persistent and bioaccumulatives.  There has been
 discussion of capping with clean fill.  Will this really contain the
 long lived things?  I could use some accurate info on anaerobic
 ecology and how material moves from anaerobic zones to aerobic zones.
  Are there creatures that live at the interface and transport
 nutrients from one to the other?

This is getting pretty long.  I'll send more questions in a future 
message!

I'm interested in all ideas.
Eric Hummel
rtkp@ptialaska.net
PO Box 23151
Ketchikan, AK 99901
tel: (907) 225-5827