East Alligator district centre water supply assessment : Kakadu National Park
D . Pidsley
Jamieson, M.; Pidsley, D.; Paiva, Jerome
E-Publications; E-Books; PublicationNT; Technical Report ; 26/1991
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Water-supply -- Northern Territory -- Kakadu National Park; Groundwater -- Northern Territory -- Kakadu National Park; Kakadu National Park (N.T.)
Power and Water Authority
Technical Report ; 26/1991
1 v. : ill., maps ; 30 cm.
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Technical Report WRD91026 Viewed at 15:07:48 on 29/07/2010 Page 46 of 107. drilled close to the river, but found hard sandstone at about 5 m depth and no water was able to be produced from these bores. The most likely extraction is a buried satisfactory infiltration mechanism for river water gallery Itrench which will require regular maintenance to ensure satisfactory operation. Due to the extreme corrosivity of brackish or saline waters and the need to separa'ce potable from non-potable waters, a separate reticulation network would be required for the non-potable waters. This is a relatively expensive exercise and it is not considered a feasible option to reticulate non-potable waters throughout the district. For the current state of development of the district centre the most feasible use for non-potable waters would be in the Obiri ablutions block. A 50 mm diameter Class 12 PVC supp:cy line about 1 km long would be required to cater for the estimated demand in 10 years time with a 10% pa growth in demand. The estimated cost of this reticulation along is $35,000. An infiltration gallery will require routine maintenance due to the possible sili:ing up of the filtration material in the gallery. This mat-erial may need cleaning or flushing at monthly or 6 monthly intervals, and this adds significantly to the. cost of such a structure. It is also possible that the filter material may be l<lst on occasions due to scouring by the river flow during flooding. Avoiding this problem will contribute significantly to the cost of design and construction of the gallery. The current state of development in the district precludes practical consideration of the use of non-potable water for ablution purposes, either to Obiri or throughout the district centre. However, should visitor growth occur at 30% pa, the cost of providin9 water from the East Alligator Riv',r is estimated to apPl:oach that of providing water from potable sources, given that the potable groundwater source is probably limited. For this reason all existing reticulation should be kept in place and in good order, even after its replacement with 100 mm PVC, so that it may act as part of a dual reticulation system if necessary in the future. 005MJ