Ramstech- University of Nevada, Reno

Introduction:
Source control deals mainly with the reclamation and remediation alternatives, which help prevent acid formation, which in turn helps in avoiding costly treatments. The objective of source- control strategies is to reduce or eliminate the volume of waste, thereby removing or minimizing ongoing contamination of the ground-water environment. Source-control techniques include removal of the source(s), surface-water controls, ground-water barriers, interceptors, and hydrodynamic controls. Source control measures are always better then treatment since it prevents the formation of contaminated water. Capping the site with a layer of clay is one of the popular measures that is done to prevent acid mine formation. The idea is to reduce precipitation in to the coal waste piles thus reducing acid mine drainage formation. Regrading is another method that can be used. The purpose of regrading is to provide a positive drainage.
Source control of water can be divided in to two types. They are

Surface water control
Ground water control

Surface water control is achieved by constructing water control structures, which regulate the flow of water as desired. The purpose of providing surface water control is to

Protect the site by diverting water from runon (an intermittent water flow, which originates off-site and flows in to a specific area, which may have had contact with wastes and tailings)
To save engineered covers (piling of similar types of wastes and getting them ready for treatments and using technologies to prevent the mixing of water to the contaminated wastes)
Protecting the water treatment system from runon and overtopping.

Ground water control is achieved by forming walls or barriers in the subsurface in such a way that it is at a down-gradient from the contaminant source or at an up-gradient from the contaminated area from where ground water diversion is required. The walls engulf the contaminated area and prevent the clean water from mixing with them. The water that is in-between the walls will be treated. The walls will be placed both up-gradient and down-gradient to prevent water from entering the contaminant zone.

Importance of Source Control:
Source control of water prevents the transport of contaminants offsite by runoff or ground water flow during and after reclamation and also prevents water erosion or flooding of engineered structures due to precipitation and runon after reclamation has taken place. They prevent erosion and contaminant water transport by

Raising water controls to divert water away from the site
Preventing infiltration of precipitation through engineered covers, which can cause groundwater contamination problems
Preventing contaminated groundwater from being transported off-site