Hydrogeologic impact analysis of new water uses in Section 7, T. 10 N. , R. 28 EWM. , of the Hanford Reservation

An evaluation was made of the hydrologic impact upon the Hanford ground water regime of removing 1.7 million gallons per day, MGD (6.4 million liters per day, MLD) from the unconfined aquifer in the north half of Section 7, T. 10 N., R. 28 EWM., and recharging to the aquifer within the same area 1.0 MGD (3.8 MLD). The hydrogeology of the specific area was characterized by examining data obtained from nearby wells. A preliminary well yield analysis was performed which verified that one well could supply 6.4 MLD at the study site. Several reasonable, simplifying assumptions were made which permitted the determination by means of an analytical equation of the water table changes resulting from projected water uses. The results of the analysis show minimal impact upon the water table as a result of either the withdrawal or recharge of water. The estimated size of a pond for recharging the used water would be about three to six acres. If the proposed groundwater use activity is implemented, one step-drawdown and one pump test are recommended to verify the withdrawal well water yield