Injection, storage, and extraction of water, Roseville, California Completed

Some regional regulatory agencies in California responsible for the protection of ground-water quality have adopted the policy that potable water injected, stored, and later extracted from aquifers used for public supply should be regulated as a waste discharge. Beginning in November 2005, the City of Roseville will inject surface water from the American River into the Mehrten Formation at a depth of 310 to 450 ft below land surface. The movement and quality of the water injected into the aquifer will be monitored at three, 4-inch diameter monitoring wells 117, 196, and 1,417 ft from the injection well. The injection/extraction wells and the monitoring wells are screened through the entire injection zone. Under the terms of the City's discharge permit, injection will cease and extraction will begin immediately, without the proposed storage period, if injected water reaches the furthest monitoring well during the test. Preliminary calculations suggest that injected water will move about 800 ft from the injection well. Movement of injected water may be greater if the aquifer is heterogeneous rather than homogeneous and contains higher permeability layers that allow movement of water greater distances through the aquifer.

The purpose of this study is evaluate how vertical variations in aquifer properties and well hydraulics may affect the injection, storage, and extraction of water and the transport of associated disinfection by-products in the Mehrten Formation underlying the City of Roseville.