Attenuation of cement kiln dust leachate by clays soils

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20002232

Peters, C S

The EPA's anticipated rule for managing cement kiln dust (CKD) contains technical and performance standards for disposal of CKD. The landfill liner component of the technical standard includes a geomembrane and clay composite and a full leachate collection system. The EPA is contemplating such stringent controls primarily based on the presence of high pH in CKD leachate. The apparent rationale is that if such leachate were released into the environment, secondary leaching of metals in the underlying soil and groundwater, such as lead and cadmium, is possible. The EPA also believes that the leachate could have adverse effects on the clay structure. Presented herein are field, laboratory, and literature data that demonstrate that the above-referenced technical standards are unnecessary, and that a clay liner is the maximum level of control needed. The authors have considerable field experience addressing CKD disposal. Few adverse impacts to groundwater have been seen. One case involved disposal of leached CKD into a settling basin that was abandoned over 25 years ago. The settling basin is underlain by clay soils, and a groundwater mound developed inside the basin where the groundwater pH was greater than 13.5. Undisturbed soil samples collected along the sidewalls and underneath the basin exhibited laboratory hydraulic conductivities of 1 x 10{sup {minus}7} cm/sec or less, similar to background values despite years of continuous contact with high pH leachate. Monitoring wells were installed immediately adjacent to the basin within the clay, and the pH levels measured in these wells were near neutral, evidence of the buffering effect of the clay. There were no other groundwater impacts other than slightly elevated dissolved solids. Laboratory studies were performed demonstrating the buffering capacity of clay soils if exposed to CKD leachate.

• Research Organization: RMT, Inc., Okemos, MI (US)
• OSTI ID: 20002232
• Report Number(s): CONF-990608--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CEMENT INDUSTRY
CLAYS
ENVIRONMENTAL IMPACTS
GROUND DISPOSAL
GROUND WATER
LEACHATES
LINERS
METALS
POLLUTION CONTROL