REDUCTION OF MICROSCOPIC PARTICULATES BY AQUIFERS

Many water utilities operate collection devices constructed in alluvia l-valley aquifers. Pumping groundwater from these systems may induce i nfiltration of surface water containing pathogenic protozoa. However, the porous sand and gravel of this kind of aquifer can significantly r educe the number of microscopic particulates that pass through the aqu ifer media. A method is proposed for evaluating the natural reduction efficiency of porous-media aquifers, taking into consideration the tra nsport of particulates through the aquifer during a period of maximum infiltration. The method allows regulators to estimate the risk of pat hogenic protozoal determine the log reduction credit warranted by the water's transport through the aquifer, and determine the type of treat ment needed for the source.