On January 25th, the desalination plant was unstable and discharged 

 6,512 ppb copper. On the following day the remaining echinoids at 

 Station 7 died. One of these animals had been at that station 170 

 days, one 80 days, and two 39 days. The copper concentration more 

 than doubled at Station 7 on that day and there was no assurance 

 that the sample was taken when the highest level of copper reached 

 the station. 



Correlations between copper levels at the stations and echinoid 

 mortalities, however, were not significant (P>.20) suggesting that 

 sampling frequency was not suitable, especially from November, 1970 

 to October, 1971 when the plant was frequently shut down for mainte- 

 nance. 



It became evident that the transient high peaks of copper released 

 when the plant started operations were causing more mortalities of 

 experimental animals than extended exposures to effluent during normal 

 operation of the desalination plant. To test this hypothesis, the 

 dates on which echinoids died were compared with the operation of the 

 desalination plant. The four operating conditions chosen for compari- 

 son with mortalities were; to 2 days following start-up, to 2 days 

 following shut-down, unstable operation, and normal plant operation 

 (+2 days). The results are presented in Table X. Not one echinoid 

 died while the plant was operating normally from October, 1970 to 

 October, 1971. At Stations 3A, 3C, and 7A about 60 percent of the 

 test animals died within two days following start-up of the desalina- 

 tion plant. 



Surprisingly, a large percentage of deaths occurred following shut- 

 downs. The causes of these mortalities are not clear. On one occasion 

 (April 27th, 1971), two echinoids died at Station 3A following low pH 

 discharges from cleaning of the evaporator just prior to shut-down. 

 Plant operators insisted that this was not a common procedure and pH 

 recordings taken during the study supported this. Low pH conditions 

 within the plant were shown to increase copper discharge and this 

 might account for some of the mortalities prior to shut-down periods. 

 In many instances, however, mortalities could not be explained. 



It should be noted that the arrangement of the discharge pipe and the 

 sampling pipe prevented sampling of the effluent when the plant was 

 being shut-down. At these times, the discharge pipe would empty. To 

 avoid damage to the sampling system pump, which was not designed to 

 operate dry for extended periods, the continuous sampling system was 

 shut down when the plant was secured and turned on when operations had 

 started again. 



Many shut-down periods were caused by a blown tube in the boiler and, 

 after the facility was secured the boiler was allowed to cool and then 

 the water in the boiler was released. The boiler water amounted to 

 about 5,000 gallons and had a pH of about 10. It was high in phosphates 



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