The area below the limnetic zone
where light does not penetrate.
This area roughly corresponds to
the hypolimnion layer of water and
is home to organisms that break
down or consume organic matter.

Unprocess natural substances, such
as wood and metals, used in the
manufacture of products.

Material that still has useful
physical or chemical properties
after serving its original purpose
and can, therefore, be reused or
remanufactured into additional
products. Plastic, paper, glass,
used oil, tin and aluminum cans
are examples of recyclable
materials.

The process of collecting
materials from the waste stream
and separating them by type,
remaking them into new products,
and marketing and reusing the
materials as new products.

Cleanup actions taken, such as at
Superfund sites. Also referred to
as RA.

The design of a cleanup system. It
may include developing engineering
plans and specifications, and
bidding documents for construction
of the system.

A soil, ground water, surface
water and/or air investigation to
determine the extent of
contamination present at a site.

A naturally occurring raw material
or from of energy derived from an
endless or cyclical source, such
as the sun, wind, falling water,
biofuels and trees. With proper
management and wise use, the
consumption of these resources can
be approximately equal to
replacement by natural or human-
assisted systems.

Something that remains, or is left
over. Residues of toxic materials
left in empty containers can pose
a threat to the environment

Businesses, local governments and
individuals responsible, as
defined by Superfund law, for
contamination at a site because of
past or current activities. Also
call PRPs for potentially
responsible parties.