Leakage from a Cooling Pond Monitored by Temperature Measurements

Andrews and Anderson (1978) applied temperature measurements to trace leakage from a cooling pond. The pond served two 500-MW electric power plants of the Columbia Generating Station, located on the floodplain of the Wisconsin River, near Portage, Wisconsin, USA. The cooling pond was constructed of 5-m-high dikes, covering an area of 200 ha. The bottom, a silty sand, was partially lined with bentonite. The area is a discharge zone of marshes and wetlands. The geology of the area was studied with 100 borings, the water table was monitored by 80 small-diameter observation wells, and heat profiles were measured in 19 observation wells. Figure 16.15 provides an example of temperature data obtained in the extensive monitoring operation. The summer temperature peak reached well B (60 m from the pond) 60 days after it reached well A (3 m from the pond). Thus the water leaking from the pond traveled 60 m in 60 days, or 1 m/day. A network of 47 boreholes of 10-m depth were equipped with thermistors for extensive monitoring.

1975 1976 1977

Fig. 16.15 Temperature variations in well A (4m depth, 3 m west of the dike) and well B (2.5 m deep, 60 m west of dike). The summer temperature peak reached well B 60 days after it reached well A, indicating a flow velocity of 1 m/day. (After Andrews and Anderson, 1978.)

1975 1976 1977

Fig. 16.15 Temperature variations in well A (4m depth, 3 m west of the dike) and well B (2.5 m deep, 60 m west of dike). The summer temperature peak reached well B 60 days after it reached well A, indicating a flow velocity of 1 m/day. (After Andrews and Anderson, 1978.)

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