Frost Resistance of Cover and Liner Materials
for Landfills and Hazardous Waste Sites
EDWIN J. CHAMBERLAIN, ALLAN E. ERICKSON, AND CRAIG H. BENSON
INTRODUCTION
tify cover and liner materials or conditions that
The common method of preventing the con-
would be frost resistant and at the same time in-
tamination of groundwater by landfill and haz-
crease productivity and save costs.
ardous waste is to encapsulate the waste material
We developed a field and laboratory program
in a compacted clay liner and cover system. The
under a U.S. Army Corps of Engineers CPAR (Con-
Environmental Protection Agency has proposed
struction Productivity Advancement Research)
guidelines for the design of disposal sites under
their jurisdiction. These guidelines generally call
private companies involved in the waste manage-
for a system of components that includes com-
ment field. The CPAR program was implemented
pacted clay layers and geosynthetic membranes
to advance the productivity of the U.S. construc-
encapsulating the waste material. The EPA usu-
tion industry. The U.S. Army's research laborato-
ally requires that the hydraulic conductivity of
ries were to join forces with private industry to
the compacted clay be less than 1 107 cm/s, and
conduct research on issues important to the Army
that the clay be protected from freezing.
and the Nation. The lead in the private sector was
The frost resistance of compacted clay covers
taken by CH2M Hill, a leading consulting engi-
and liners for landfills and hazardous waste sites
neering firm in the environmental geotechniques
has been the subject of controversy for many
field. The other partners were WMX, Inc., one of
years. Laboratory studies have frequently shown
the largest owners and operators of landfills in
that freezing and thawing significantly increase
the U.S., and James Clem Corporation, Colloid
the hydraulic conductivity of compacted clay
Environmental Technologies Company, and Gun-
soils. However, there has not been any corrobo-
dle Lining Systems, Inc., three companies that
rating field evidence. Moreover, when "undis-
produce geosynthetic soil layer systems and pro-
turbed" samples from clay liners, which have fro-
mote their use as alternatives to compacted clay
zen and thawed in the field, have been examined
soils.
in the laboratory, little or no change in hydraulic
This report describes a study that examined
conductivity has been observed. Nonetheless, the
how freezing and thawing affects the hydraulic
persistent laboratory evidence of freezing and
conductivity of two compacted natural clay soils,
thawing has led the EPA and other regulatory
one compacted sandbentonite mixture, and
agencies to set guidelines requiring frost protec-
three geosynthetic clay liners (GCLs). The clay
tion for compacted clay covers and liners.
soils were typical of those used for landfill covers
Our intent here was to more closely examine
and liners, with low and medium plasticities. The
this problem. Since it appeared that careful study
bentonite in the sandbentonite mixture is a
would confirm that frost action was a problem for
highly swelling clay that hydrates on exposure to
compacted clay soils, we decided to also look at
water and plugs the channels in the sand. GCLs
alternatives to the standard clay cover and liner
are made up of one or more geosynthetic material
materials. The purpose of this study was to iden-
and a thin layer of bentonite clay. The bentonite in
Previous Page
