DEPARTMENT OF THE ARMY
U.S. Army Corps of Engineers
Washington, D.C. 20314-1000
28 February 1995
Engineering and Design
TREATABILITY STUDIES FOR
1. Purpose. This letter furnishes information and guidance on
scoping a treatability study for solidification/stabilization
(S/S) of contaminated material.
2. Applicability. This letter applies to all HQUSACE/OCE
elements and USACE Commands having Hazardous, Toxic, and
Radioactive Waste (HTRW) investigation and design responsibility.
References are listed in Appendix A.
4. Background. Solidification/stabilization is applicable for
the treatment of contaminated liquids, soils, and sludges. This
ETL will focus on S/S treatability studies for soils and sludges.
S/S refers to treatment processes that are designed to accomplish
one or more of the following: 1) improve the handling and
physical characteristics of the waste; 2) decrease the surface
area of the waste mass across which loss of contaminants can
occur; and 3) reduce the solubility of hazardous constituents in
the waste. The final product of an S/S process may vary from a
granular, soil-like material to a cohesive solid depending on the
amount of reagents added and the type of waste being treated.
S/S can be performed as an in-situ process or the contaminated
material can be excavated and treated above ground in some type
of mixing unit.
a. Definitions. Solidification and stabilization refer to
different processes which occur during treatment. The U.S. EPA
has defined the terms as follows:
(1) Solidification. Solidification refers to techniques
that encapsulate the waste in a monolithic solid of high
structural integrity. The encapsulation may be of fine waste
particles (microencapsulation) or of a large block or container
of waste (macroencapsulation). Solidification does not
necessarily involve a chemical interaction between the waste and
the solidifying reagents, but may mechanically bind the waste
into a monolith. Contaminant migration is restricted by
decreasing the surface area exposed to leaching and/or by
isolating the waste within an impervious capsule.