Sub-surface drainage can control waterlogging and salinity of arable land by removing excess groundwater.
There are two broad types of sub-surface drainage: interception drainage and relief drainage.
The cost of drainage will depend on the specific design for the site. For relief drains the prime determinate of cost will be the required spacing. In general, clay soils of low permeability or seepage areas will need narrower spacings and will be harder and more expensive to reclaim than sands or areas only needing drainage of local water.
George, P R.
"Sub-surface drainage methods for salinity control,"
Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 26
, Article 4.
Available at: http://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol26/iss4/4