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Earthen
lining techniques
Earthen lining is a common and proven method of channel remediation.
Soil additives and imported materials may be used. Soil properties,
subgrade preparation and compaction are important. Costs vary with
conditions of the project. Compacted earthen liners are an efficient
means of controlling seepage. Suitable materials for compaction
are discussed and examples are provided.
Hard surface lining techniques
Hard surface lining is constructed of materials such as cement
concrete, mortar, soil-cement, brick and stone, to form a hard
impermeable surface that reduces seepage. Pipes and flumes are
included here. General considerations covered are channel prism,
foundation, under-drainage, joints, hazards and performance
Flexible membrane lining techniques
Flexible membrane liners are thin, flexible, impermeable liners
which, combined with the strength of the base soil, are used to
reduce seepage. They may be exposed or covered, and are available
in a wide variety of materials. Desirable properties are listed.
Installation methods, site preparation and weather considerations
are discussed.
Groundwater intervention techniques
Groundwater intervention techniques aim to change the groundwater
flow outside the channel prism rather than prevent seepage. The
aim is usually to reduce the impacts of seepage such as waterlogging
and land salinity on adjacent land.
Techniques overview
Each section contains a general description of the type of liners,
followed by more detailed descriptions of specific applications.
Where available from the project trials, specific detail on installation
issues and costs is also provided. A summary of all techniques
trialed as part of this project is provided in Table
1 Trial data.
A comparison of the key factors of channel seepage remediation
techniques and a summary of the suitability of techniques to particular
situations are provided in the tables below. These tables provide
an overview of the general techniques to enable a quick comparative
assessment of which method may suit the site conditions and meet
RWA objectives and criteria for seepage remediation, prior to further
investigation of techniques in Channel
seepage remediation techniques.
For more information on channel seepage remediation techniques
refer to Table 1 Channel seepage remediation decision matrix.
The table below ranks the performance of each category of seepage
remediation technique, according to a range from low, to medium,
high and very high, against cost, durability, seepage reduction
and maintenance requirements. To identify which of these rankings
is desirable, the colours of green, yellow and red have been superimposed
to indicate whether a technique is more suitable, suitable, or
less suitable respectively.
Table 1 Channel seepage
remediation technique summary
Note:
*Durability is estimated for new techniques/products on the
market. Durability assumes liners are appropriately maintained
and minor repairs made when required. Durability of exposed flexible
membranes is highly dependent on UV stabilisation of materials.
**Costs will vary with site conditions and availability of materials.
The table below lists a number of site conditions and factors and assesses the
suitability of each technique in those conditions. Once again colours or green,
yellow and red have been used to highlight which techniques are more suitable,
suitable, or less suitable.
Table 2 Channel seepage remediation technique
suitability chart
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6 Select potential
techniques |
