Table 6-2-Summary of Liner Types-Continued
Attacked by many organics,
Good resistance to inorganic;
Produced in roll form in various widths
good tensile, elongation,
and thickness; polymerization of
solvents - and oils; not
puncture, and abrasion
recommended for exposure
resistant properties; wide
to weathering and ultraviolet
ranges of physical
light conditions -
Excellent oil, fuel, and water
Relatively new class of polymeric
resistance with high tensile
materials ranging from highly polar
strength and excellent
resistance to weathering
Hydraulic cement of silica, lime, and
Excellent base for waste
to installed costs per sq yd in 1981 dollars; M- to per sq. yd.; H- to per sq. yd.
Adapted from Technologies and Management Strategies for Hazardous Waste Control, Office of Technology
Assessment, Congress of the U.S1983.
sired membrane, both material resins are mixed with
chemical and mineralogical properties may be remolded
monomers under controlled temperature and pressure
to specified moisture content and maximum dry density
conditions in a polymerizer.
specified by ASTM D1557 to determine the permeability
companies utilize these basic resins in combination with
of test specimens. Test methods acceptable to EPA are
their own compounding to produce specialty
contained in appendix A of the draft RCRA guidance
membranes. A list of the producers and suppliers of raw
documents for waste piles and surface impoundments.
material polymer can be found in the EPA SW-870.
Both water and representative chemical wastes would be
(b) Specifications for individual sheet materials
used for the permeant.
can be obtained from the producer. Suppliers are also
(b) Figure 6-4 shows the moisture content
able to provide specifications for the base polymers and
versus dry density curve for a clay liner, as well as the
their individual synthetic membrane sheet.
relationship between moisture content, relative
(c) To increase tensile strength, to provide
compaction and permeability for a clay liner subjected to
resistance to shrinkage, punctures and tears and to
water and aqueous hazardous waste. All clay liners
permit easier handling and seaming, a fabric
must have a permeability of 10-7 cm/sec or less.
(2) Synthetic Liners. Proof of the chemical
reinforcement (scrim) may be laminated between two
synthetic membrane sheets. When installing reinforced
resistance of the selected synthetic membrane liner is
liners, care must be taken to ensure that all exposed
required by RCRA regulations. In recent years, all
edges are sealed. Failure to do so could result in the
manufacturers of synthetic liners, as well as most
scrim acting like a wick and drawing in moisture,
suppliers, have operated testing facilities and developed
resulting in eventual liner breakdown.
f. Compatibility and physical testing. Since the
respective products. Reference to chemical resistance
prime purpose of a liner is to prevent liquids from leaving
guideline sheets or compatibility charts that classify a
a hazardous waste facility, the physical integrity and
generic flexible membrane liner will not, however,
chemical compatibility of the liner with the waste
provide sufficient data on which to base a final liner
constituents must be ensured.
selection, since the manufacturer's compounding can
(1) Soil liners. Permeability tests, in which soil liners
produce significant differences in liner properties and
performance in the field.
Furthermore, since the
are brought into contact first with water, then with
chemical characteristics of both liners and wastes are
leachate or chemical waste, are the most important
extremely variable, it is difficult to generalize concerning
indicators of the compatibility of soil liner materials with
Data currently available, however,
the waste they are to contain. Permeability is a function
of many variables, including pore size, pore space
liner materials can be incompatible:
tortuosity, particle shape and size, and mineralogy of the
* Polyvinyl chloride (PVC) tends to be dissolved
soil material, the permeant characteristics, and
by chlorinated solvents.
temperature. The permeability of a soil liner can be
* Chlorosulfonated polyethylene can be dis-
affected by waste types that are incompatible with the
solved by aromatic hydrocarbons.
liner material. For example, clay soils may exhibit high
* Asphaltic materials may dissolve in oily
permeability when exposed to concentrated organics,
especially organics of high and low pH.
* Concrete- and lime-based materials are dis-
(a) To test the permeability of soil materials,
solved by acids.
samples which have been tested for their physical,