Table 1. Information Used to Demonstrate Conformance with Performance Standards for CDF Liners

ERDC TN-DOER-R6

December 2004

Table 1

Information Used to Demonstrate Conformance with Performance Standards for CDF

Liners

Information

Typical Parameters

Description of Liner System

Description of:

Material type and source

Thickness

Hydraulic conductivity

Recompacting and amendment requirements

Location of borrow area and any amendments

Material Testing Data

Test results for:

Index tests

Hydraulic conductivity

Strength, puncture resistance, etc.

Consolidation

Shrink-swell properties

Potential for dispersion/piping of dredged material due to liquid flow

through liner

Liner Compatibility Data

Results of hydraulic conductivity testing of liner material with representative

leachate

Liner Thickness

Demonstration that the liner system thickness is sufficient to retard liquid

flow-through during operating life and post-closure period

Construction Specifications

Procedures for liner installation, including:

Method of compaction

Degree of compaction; water content to be achieved

Lift thickness

Methods to alter water content

Scarification requirement between lifts

Method of amending soil or dredged material, if applicable

Construction Quality Assurance

Description of quality assurance program and testing procedures

Compacted Subsoil. CDFs will normally be constructed near or within water bodies in an effort to

reduce dredged material transportation distance. Siting in the vicinity of water bodies further offers a

potential advantage in that many candidate sites possess naturally occurring low-permeability materials

due to the depositional environment of rivers, lakes, and harbors. For example, in areas dominated by

sluggish streams and rivers, alluvium typically consists of clayey silt (Rahn 1986), where the reduced

flow velocities restrict the bed load of the stream to the finest fractions. Similarly, during high flow rates,

overbank flooding may occur, allowing for deposition of silt, silty clays, and clays in the floodplains.

Oxbow lakes, formed from meander cutoffs characteristic of the lower Mississippi River Valley, often fill

with fine-grained clays. Relatively thin clayey lacustrine deposits are often associated with areas of the

Great Lakes, while marine clay deposits are common in many coastal areas such as Boston (Rahn 1986).

Low-permeability materials that may be considered potential liner element candidates are identified in

Table 2 as those possessing permeabilities of 10-6 cm/s or below. Qian (1995) notes that in most cases the

hydraulic conductivity must be less than or equal to 10-7 cm/s for soil liners. In some cases (e.g., a lightly

contaminated dredged material), materials possessing slightly higher hydraulic conductivities may be