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The concentrations show no significant trends over the period of record. 

 A change from an average of 1,500 mg/L to 660 mg/L was observed for well 

 4 in 1986. The casing was found broken at ground surface allowing sur- 

 face water to enter the well. The 1.5 inch diameter casing makes purging 

 difficult. This well has been dropped from the sampling schedule. 



ASH LAGOON QUALITY AND QUANTITY 



The ash lagoon system at the Poplar River Power Station continues to be 

 operated on a closed system basis with no discharge to surface waters. 

 During 1990, an estimated 577,800 m 3 of ash was deposited to the ash 

 lagoons. Approximately 346,700 m 3 of water was used for sluicing. The 

 sluiced ash was usually directed to the west or east side of Ash Lagoon 

 No. 1 or the southeast corner of Ash Lagoon No. 3. Occasionally, sluiced 

 ash was directed to the west side of Ash Lagoon No. 2. When ash is 

 directed to Ash Lagoon No. 1, the normal series operation is Ash Lagoon 

 No. 1, Ash Lagoon No. 2, and the Polishing Pond. When ash is directed to 

 Ash Lagoon No. 3, water from that lagoon is pumped to Ash Lagoon No. 2 

 where it flows by gravity to the Polishing Pond. When ash is directed to 

 Ash Lagoon No. 2, water flows by gravity directly to the polishing pond. 

 In all cases, water from the polishing pond is returned to the plant for 

 sluicing. 



During 1990, maximum and minimum water depths were 7.0 and 5.3m in Ash 

 Lagoon No. 1, 5.9 and 4.5 m in Ash Lagoon No. 2, 1.93 and 0.8 m in Ash 

 Lagoon No. 3, and 4.1 and 1.7 in the polishing pond. 



