Patent ID: 8178356

Claim:
A method for evaluation of a percolation tank comprising the steps of: (i) determining a relationship between water level in the percolation tank at a given time and volume of water in the percolation tank at the given time, wherein the determining comprises conducting a topographic survey of a bed of the percolation tank and using the survey to generate a rating curve that allows a determination of the volume of water in the tank from measurement of a level of water in the tank; (ii) measuring the water level in the percolation tank at each of times t 1 and t 2 and ascertaining the volume of water in the percolation tank at each of times t 1 and t 2 from the relationship determined in step (i); (iii) measuring the chloride concentration in the percolation tank at each of times t 1 and t 2 ; (iv) computing average chloride concentration in the percolation tank during time interval t 1 and t 2 , and (v) calculating a mass balance of total chloride in the water in the percolation tank during time interval t 1 and t 2 to ascertain the fraction of water that percolated from the percolation tank to groundwater during the time interval.