One concern I hear often is groundwater contamination. The ground water on our property is non-potable and must be removed before any work begins.
In our geothermic process ground water is first removed from the target formation through a process called “dewatering”. The dry formation can then be heated. As part of dewatering, formation is cut off from ground water infiltration with underground dams called “grout curtains”. After shale oil has been removed and the remaining char has been gasified for additional energy recovery, the formation is secured and left dry. This is accomplished through a combination of processes.
The first line of defense is complete surface reclamation through a process called “phytoremediation”. Phytoremediation involves planting a dense community of trees, shrubs, and grass, on the surface overlying the treated formation. As the plant community grows it forms an increasingly dense network of roots in the topsoil. These roots absorb moisture, which is then filtered through the plant’s metabolism and is then released to the atmosphere through plant respiration. Phytoremediation reduces water infiltration into the underground by 90%. Typical rates of percolation into the subsurface in the Piceance Basin are less than an inch a year. Phytoremediation will reduce this to less than a tenth of an inch. If nothing else were done, it would require over a hundred years to accumulate one foot of water in the dry aquifers. The dry oil shale formation in the Piceance will be over a thousand feet thick.
Through use of guard wells and addition of grout curtains, and possibly the installation of drainage passages under the formation, water will be entirely prevented from accumulating in the treated zone. Water removed from the formation either through guard wells or through the drainage system will be monitored for pollutants and treated to drinking water standards prior to being released into streams or being reinjected into the existing aquifers. In any case the process will be carried out by methods that prevent any degradation of ground water quality.