Nabarlek Pit decommissioning migration of sulphate, nitrate and radium ions in groundwater - preliminary modelling
E-Publications; E-Books; PublicationNT; Report ; 41/1984
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Dept. of Transport and Works
Report ; 41/1984
Check within Publication or with content Publisher.
Technical Report WRD84041 Viewed at 14:07:09 on 29/07/2010 Page 13 of 34. I I I I I I I I I I I I I I I I I I I I I The concentration of nitrate ion could lie in the range 250-500 mg!L and sulphate ion in the range 9000-1S000 mg/L during the rehabilitation if the pit. Assuming that water seeps from the pit at a rate of 35 m2/day and that water r~eaching Cooper Creek is evaporated for a period of seven months in the dry season then the total nitrate load deposited in Cooper Creek sediments as soluble salts is given by: = 2l7days x 35000 L/day x(250-500) - 1.90 x 10 3 - 3.S0 x 10 3 Kg mg/L Converting to an equivalent nitrogen load: Total N - (1.90 x 10 3 - 3.80 x 10 3 ) x 14 Kg 62 = 430 Kq - 860 Kg Similarly for sulphate ion: 7_ SOi - (9000-18000) mg/L x 35000 L!day x 217 days = 70 x 10 3 Kg - 140 x 10 3 Kg A comparison of these results with total nitrogen and sulpb.ate ion loads normally carried by Cooper Creek indicates that in a single dry season enough sulphate could accumulate in Cooper Creek sediments to equal the load normally carried by the creek in a year. Total nitrogen levels, by contrast, are much lower but are comparable with levels carried in the first month that Cooper Creek _flows each wet season. The above estimates for nitrate and sulphate ion loadings are probably much higher than "ill actually be observed in Cooper Creek for two main reasons: SA2/ll :TJ