Direct Injection of Reclaimed Water Into an Aquifer

The changes in water quality that occur when reclaimed water is injected into a confined aquifer are being studied. The major objectives are: (1)To determine the quality changes; (2)to identify the chemical, physical, and biological processes; (3)to determine their effects on the aquifer; (4)to develop a generalized mathematical model; and (5)to evaluate the direct injection of reclaimed water. The research is being conducted using the 2-mgd (0.09-m³/s reclamation facilitybeing constructed by the Santa Clara Valley Water District in Palo Alto, Calif. The reclaimed water will be used to create a salinity barrier by injecting into a well field consisting of nine injection/extraction well pairs. It has been found that ammonia, trace metals, and many trace organic compounds move slowly compared to chloride ion. The arrival of ammonia, for example, is attenuated by a factor of 40 compared to chloride.