TREATABILITY STUDIES FOR SOLIDIFICATION/STABILIZATION OF CONTAMINATED MATERIAL

DEPARTMENT OF THE ARMY

ETL 1110-1-158

U.S. Army Corps of Engineers

CEMP-RT

Washington, D.C. 20314-1000

Technical Letter

No. 1110-1-158

28 February 1995

Engineering and Design

TREATABILITY STUDIES FOR

SOLIDIFICATION/STABILIZATION OF

CONTAMINATED MATERIAL

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.

3.

References.

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.