Dredged material managers frequently face decisions concerning the impact of
contaminated dredged sediment proposed for disposal. One of the first decisions to be
made is answering the question: How should the various methods available for
evaluating sediment contaminant concentrations be used?

Scientists performing research at the U.S. Army Corps of Engineers Center for
Contaminated Sediments have summarized information that helps to select an
appropriate method to differentiate sediments of little concern from those predicted to
be contaminated sufficiently to warrant special management or handling. The work
resulted in Technical Note EEDP-04-29, available online in portable document format
(.pdf) at www.wes.army.mil/el/dots/eedptn.htmI) which provides guidance on the use of
sediment quality guidelines (SQG's) (see box next page) for dredged material
evaluations. Dr. Richard (Dick) K. Peddicord is the lead author of the 14-page technical
note. It includes SQG information for aquatic and terrestrial environments. Funding was
provided under the Long Term Effects of Dredging Operations research program.

Described are technical limitations for Tier 1 or Tier 2 screening of sediments that pose
little concern under specific circumstances, as well as identifying situations when
higher tier, effects-based testing may be used to assess sediment acceptability for a
range of disposal options. Limitations make SQGs by themselves technically unaccept-

able for making definitive determinations of adverse impacts of sediment to the aquatic
environment. SQGs are therefore recommended as a screening tool. Case-specific,
direct biological effects testing provides a more comprehensive and technically sound
basis for determining the acceptability of sediments for aquatic placement.

The EPA once proposed a technical basis for developing sediment quality criteria. But
this and other methods have received varying degrees of attention from the scientific
and regulatory communities and citizen groups. Opinions on the utility of SQGs range
from essentially worthless to stand-alone, pass-fail determinants of the environmental
acceptability of sediments for aquatic placement, according to information presented in
the technical note.

What are SQGs?

The environmental quality of sediments has been judged by chemical concentration
values for more than 30 years. Early on, values were derived primarily on the basis of
geochemical considerations or sewage discharge values that bore little relevance to
dredged material assessment. Approximately 25 years ago, scientists began to
develop methods for deriving values associated with adverse biological effects. All
past efforts were applied with little success because the methods did not account for
the complex biogeochemical interaction of chemicals and sediments. Since then,
several methods to determine sediment contaminant concentration values that
differentiate sediments of little concern from those predicted to have adverse biological
effects have been published. All values used to determine sediment contaminant
concentrations that differentiate sediments of little concern from those predicted to
have adverse biological effects are collectively called "sediment quality guidelines"
even though they have different names. The term SQG was selected because it has
broad and general meaning and has no regulatory connotation as a "pass/fail" criterion
or standard. The term SQG is broad enough to encompass all the methods leading to
sediment quality guidelines, criteria, etc., which are presented in the article.

Dredging Research, Vol. 1 No. 4, U.S. Army Engineer Waterways Experiment Station,
December 1998; edited by Elke Briuer, APR