Nabarlek Pit decommissioning migration of sulphate, nitrate and radium ions in groundwater - preliminary modelling
Appleyard, S.
E-Publications; E-Books; PublicationNT; Report ; 41/1984
1984-04-01
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Date:1984-04
English
Dept. of Transport and Works
Darwin
Report ; 41/1984
application/pdf.
Check within Publication or with content Publisher.
https://hdl.handle.net/10070/228496
https://hdl.handle.net/10070/674076
Technical Report WRD84041 Viewed at 14:07:09 on 29/07/2010 Page 18 of 34. I I I I I I I I I I I I I I I I I I I I I seepage ;vater reaches the highly transmissive zone to the south east of the pit. Diffusion and dispersion processes will reduce concentrations of sulphate and nitrate ions between the pit and this area. As a first approximation, it will be assumed that this effect is negligible and that initial nitrate ion concentrations lie in the range 250 - 500 giro' and initial sulphate ion concentrations lie in the range 9000 - 18000 g/m 3 Sulphate and nitrate icn lcads reaching Cooper Creek in a single dry season vary with grcundwater velocity are equal to: vJhere L == dry season load of N0 3 or so~ p. - area under breakthrough cur',7e o~ a time period corres90ncing to a dry season (assumed 200 days) - Don dispe~sed dry ~ season load of NO~ .5 or At groundwater velocities of about 2m/day, dispersion is unimportant, and so nitrate and sulphate loads are as previously calculated, ie: Nitrate ion load (expressed as N) - 430 to 860 kg A == 7.0xlo":l:kg to ~ 1.40xlO~kg However, if a velocity of 0.03 m/day is assumed, the situation is quite different. The breakthrough curve shown in Fig 3.2(a) is a normal distribution curve with a standard deviation equal to c= (2 DL t)" (t == arrival time (Fried, 1975) at Cooper Creek = 2 x l04 days) SA2/ll :TJ