30 Sep 01
and settlement will be a concern.
(2) Standard or Modified Proctor. Proctor tests are used to develop compaction criteria for all
materials requiring compaction.
(3) Hydraulic Conductivity. Hydraulic conductivity tests are typically performed on all barrier
and drainage layer soils when a borrow source is identified and available.
(4) Density. Density tests establish the existing condition of foundation and borrow soils. For
borrow soils, this information can be used to estimate swell and shrinkage potential attributable to
excavation and compaction.
(5) Dispersive Clay. This test, though not common, is used to determine the erodibility of a soil.
In a cover system, dispersive soils can result in excessive surface erosion or clogging of drainage layers.
(6) Consolidation. Consolidation testing is sometimes performed on foundation soils to estimate
settlement resulting from placement of the landfill cover.
(7) Shear Strength. The shear strength of soils may be determined for use in stability analysis of
the cover and foundation soils. Shear strength of the waste material is normally estimated because of
the difficulty in obtaining representative samples.
(8) Direct Shear Tests. Direct shear tests should be conducted on all potentially critical cover
e. Chemical Data Requirements. Chemical testing for site contaminants
is often required for the
design of various landfill cover features. A chemist should be involved in the testing program for these
aspects of the project.
(1) Landfill Gas Composition. Generally, the percentage of methane, carbon dioxide, oxygen,
and other non-methanogenic gases should be determined. This information is used in the design of the
landfill gas collection and treatment system.
(2) Borrow Soil Testing. In addition to the typical geotechnical tests, potential borrow sources
are often tested for contamination to ensure that materials used to construct the cover system are clean.
Quality assurance samples taken by the Government may also be prudent to verify the seller's claims
by analyzing for target analytes. Backfill is commonly tested for the site-specific contaminants being
originating. The specifications should describe what contaminants the soil should be tested for and how
frequently the tests should be done. Backfill should not be used until borrow source test results have
been submitted and approved.