ngukurr water supply evaluation · technical report wrd92041 viewed at 15:07:57 on 29/07/2010 page...

Technical Report WRD92041

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POWER AND WATER AUTHORITY

NGUKURR WATER SUPPLY EVALUATION

REPORT 41/92

Andrew Moretti (Ted Warren & Assoc)

Peter Jolly

Patricia Tyson

A Baker

Water Resources Division

May 1992


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SYNOPSIS

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

1. Introduction

2. Groundwater Source

2.1 Geology

2.1.1 Aquifer Occurrence

2.2 Aquifer Parameters

TABLE OF CONTENTS

2.3 Groundwater Movement and Recharge

2.4 Water Quality

3. Surface Water Source

3.1 Roper River Flow

3.1.1 Flow at GS 9030146 (Wilton River)

3.1.2 Flow at GS 9030102 (Hodgson River)

3.1.3 Flow at GS 9030250 (Roper River) 3.2 Water Quality

4. Comparison of Sources

5. Water Demand

5.1 Water Supply

6. Conclusion

7. Recommendations

8. References

APPENDICES

Appendix A

Appendix B

Appendix C

Ngukurr Groundwater Investigations

Bore Construction

Bore Completion Reports


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S"YNOPSIS

Various groundwater investigations have been undertaken at

Ngukurr (formerly Roper River Mission) in an attempt to locate

a suitable groundwater resource. These investigations resulted

in three production bores, RN 5955 and 6035 drilled in 1967, and

21481 drilled in 1982.

Water for the community's domestic needs is supplied from the

groundwater resource and from Roper River in a ratio of

approximately 85% to 15% respectively.

The production bores have been constructed in the Kookaburra

Creek Formation with the aquifer being at the basal contact of

the Yalwarra Volcanic Member and the underlying sediments. Bore

6035 is used in a standby capacity with bores 5955 and 21481

supplying 6.5 L/s and 7.3 L/s (respectively) when pumped in

conjunction. The groundwater is of marginal quality with high

hardness and NaCl levels. The water quality of the river water

is variable due to physical properties (turbidity and

bacteriological quality) and chemical properties (high salinities

at the end of some dry seasons) and will require treatment for

extended periods.


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2.1

2.4

3.1

3.2

3.3

3.4

3.5

3.6

3.7

5.1

5.2

5.3

Al

Bl

LIST OF TABLES

Ngukurr Groundwater Investigation - Slliumary of Results

Water Quality Data

Flow History for Wilton River

Flow History for Hodgson River

Flow ;.r· t •• l.S Ory for Roper River

Roper River Water Quality 1980

Roper River Water Quality 1986

Selected Water Quality Parameters

Ngukurr

Salinity at Various Tidal Conditions

Ngukurr Population Data

Current and Projected Water Demands

Pumping Rates and Pump Settings

Lithological Logs

Bore Construction Details

Roper River


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1 .

2.l(a)

2.l(b)

2.l(c)

3.1

3.2

3.3

3.4

A2 (a)

A2 (b)

A2(c)

Cl(a)

Cl(b)

C2(a)

C2(b)

C3 (a)

C3 (b)

Location Map

Bore Location Map

Geological Map

Local Geology and Bore Locations

LIST OF FIGURES

Stream Flow Recorder Stations Location Map

Three Year Moving Average Rainfall - Katherine 1873-

1984

Salinity and Tidal Variation 1964

Salinity and Tidal Variation 1966

Constant Discharge Test 21481

Constant Discharge Test 21481 OB 6035

Step Drawdown Test 21481

Composite Log of Bore 5955

Pumping Curve RN 5955






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kPa

L/s

km

m

rmn

ID

kL/d

TDS

R..11J

m2 /d

mg/L

mins

NaCl

co, kL

L

NB

u/m

m3 /s

kilopascal

litres per second

kilometre

metre

millimetre

Internal Diameter

kilolitre per day

Total Dissolved Solids

Registered Number

metres squared per day

milligrams per litre

minutes

Sodium chloride

Carbon dioxide

kilolitre

litre

Nominal Bore

microsiemens per metre

Cubic metres per second

ABBREVIATIONS


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1. INTRODUCTION

Ngukurr, formerly known as Roper River Mission, is located on the

northern bank of the Roper River, approximately 100 kms upstream

of the mouth and some 500 kms east south-east of Darwin (refer

Figure 1). The community is located on a prominent ridge within

the Roper River flood plain and is served by a sealed road from

the Stuart Highway at Mataranka to approximately 30km from Roper

Bar and then a formed gravel road. It is also served by a barge

landing on the Roper River and an airstrip. Ngukurr has a

population estimated at 800 persons, however, this figure varies

throughout the year due to population movements between

outstations and the community.

Domestic water for Ngukurr was originally obtained from the Roper

River. However, this was found to be unsuitable in the late dry

season, due to saline intrusion. Bores were drilled in

groundwater investigations in 1961, 1963, 1967, 1972, 1978 and

1982, in attempts to locate a suitable groundwater resource.

These investigations resulted in production bores 5955 and 6035,

drilled in 1967 and 21481, drilled in 1982. The three production

bores are located within 100m of each other about 3.5km north

northwest of Ngukurr. All other bores drilled around Ngukurr

have yielded little or no water, or brackish water.

Ngukurr currently has a combined surface water and groundwater

supply with the majority of domestic water being supplied from

the borefield in a ratio of approximately 85% groundwater to 15%

river water. The quality of the river water is acceptable for

a large part of each year, with salinity levels exceeding

acceptable li..rnits normally only towards the end of the dry

season. Turbidity also creates a significant problem and

treatment is sometimes needed for extended periods throughout

each year. In 1981 a slow sand filter was commissioned to

remove algae and suspended solids from river water. However,

difficulties were experienced due to the filter media clogging.

The plant has rarely been utilised.

This report was undertaken with the following objectives:

(1) Quantify current water usage and supply source capacity.

(2) Determine a management strategy for Ngukurr water supply

source.


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Adelaide River <I

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Daly River Pine Creek

Oolloo

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Willeroo

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NGUKURR

A THERINE

TENNANT CREEK

ALICE SPRINGS

Matarank

NHULUNBUY

Bulman

Roper Bar

~oes illW

Larrimah

rf:j ~ NGUKURR ~root• Eylandt

Numbulwar

Not To Scale

r-lathaA Rivero

LOCATION MAP

Fig. 1


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2. GROUNDWATER SOURCE

The following is an evaluation of the groundwater source based

on the inteLpretation of the results obtained from drilling, test

pumping and field observations conducted as part of the Ngukurr

Groundwater Investigations (1962, 63, 67, 72, 78, 82) Bores are

referred to by their registered numbers (RN) and the bore

locations are shown in Figure 2.l(a).

2.1 Geology

The physiography of the area surrounding Ngukurr consists mainly

of Proterozoic sediments that have been eroded to a mature

surface. Broad, flat-floored valleys have been formed on

incompetent shale, siltstone and carbonate sediments. Thin-

bedded fine-grained sandstone and greywacke form rounded, rubble

covered hills and the competent sandstone beds occur as long

escarpment-fOL;lled ridges.

Figures 2.l(b) and (c) present the geology of the area. The

producing bores around Ngukurr were drilled in the McArthur

Group. The base of the McArthur Group is formed by a

stromatolite-bearing dolomite at the bottom of the Vizard

Formation. The dolomite and siliceous sediments throughout the

rest of the formation contain some fine elastics and are

interbedded with sandstone beds. The overlying Mount Birch

Sandstone (subsequently renamed as the Smythe Sandstone Me..-nber

of the Balbarini Dolomite - refer reference 5) is feldspathic and

the upper white member is distinctive throughout the area. This

formation is the only dominantly sandstone unit in the Group, but

thin sandstone beds are present throughout the Kookaburra Creek

Formation (renamed as the Balbarini Dolomite) . The sediments in

the Kookaburra Creek Formation consist of silicified dolomites

in part oolitic with stromatolites, chert and ferruginous chert

breccia. The Yalwarra Volcanic Me..-nber (mainly basalt) represents

a period of vulcanism in the middle of the Kookaburra Creek

Formation. The presence of boulder conglomerate within this

member suggests that the volcanics also temporarily upset a

fairly stable period in the erosion of the nearest land mass.

The LLTflillen Sandstone forms the main hills to the north of

Ngukurr, while a superficial cover of sand, laterite and soil


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• 2741 PRODUCTION BORE BORE WITH REGISTERED NUMBER MINOR ROAD OR TRACK CREEK

BORE LOCATION MAP Fig. 2.1(a}


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GEOLOGICAL BOUNDARY FAULi STRJKi'O

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- - - - - - - MINOR ROAD OR TRACK

- - - - - - - CREEK


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LOCAL GEOLOGY AND BORE LOCATIONS

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masks the underlying Kookaburra Creek Formation on the Walmudga

Plain to the east.

The Showell Creek Fault runs north-south through the area. It

is a resultant right lateral fault with most of its activity

occurring after, and possibly during, the deposition of the

Kookaburra Creek Formation and Limmen Sandstone.

2.1.1 Aquifer Occurrence

Stratigraphically the formation of interest is the Kookaburra

Creek Formation. The Yalwarra Volcanic Member represents a

period of vulcanism in the middle of this formation and it is at

the contact between the volcanics and the underlying Kookaburra

Creek sediments where the current production bores struck water.

The formation dips at around 5° north.

Recharge to the aquifer is thought to occur through the weathered

dolomite of the Kookaburra Creek Formation. The Showell Creek

Fault and the fault immediately to the south of the production

bores could be possible sources of enhanced aquifer recharge.

Available data indicates the standing water level in the

borefield is close to the dry season water level in the Roper

River. Under the Walmudga Plain the dolomite is covered by only

a thin alluvial cover.

The Limmen Sandstone forms the main hills to the north of

Ngukurr. It has a very low permeability, therefore no

significant groundwater recharge of the weathered dolomite will

take place through the Limmen Sandstone.

A summary of the results of bore holes drilled in the Ngukurr

area can be seen in Table 2.1.


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TABLE 2 . 1 . NGUKURR GROUNDWATER INVESTIGATION - SUMMARY OF RESULTS.

BORE DATE DEPTH YIELD WATER QUALITY RN DRILLED DRILLED (L/s)

(m)

2735 23/09/61 17.4 nil 2736 25/09/61 3.8 nil 2737 28/09/61 31.7 seepage unpotable 2738 29/09/61 10.2 nil 2739 02/10/61 12.8 nil 2740 03/10/61 10.6 nil 2741 04/10/61 16.2 nil 2742 05/10/61 11.7 nil 2743 06/10/61 21.6 0 .25 unpotable

4219 27/09/63 43. 9 0.3 unpotable 4098 10/10/63 85.3 0.5 unpotable 4099 14/10/63 38.1 4.5 unpotable 4100 17/10/63 19.4 0.25 unpotable

5955 16/11/67 57.9 12.5 potable Pn::ducticn bore 6035 11/12/67 50.9 12.5 potable Pn::ducticn bore

7868 01/06/72 106.7 nil 7869 18/05/72 121. 9 nil 7870 05/06/72 48.8 2.5 unpotable

9323 25/09/78 15.0 nil 9324 05/10/78 35.0 nil 9325 11/10/78 31.5 0. 6 potable

21503 12/06/82 80.0 1.5 potable 21504 13/06/82 27.0 nil 21505 14/06/82 54.0 1.3 potable 21507 16/06/82 43.0 nil 21481 15/06/82 49.0 15 potable Pn::ducticn bore

2.2 Aauifer Parameters

The only bore drilled in the Ngukurr area that has been

comprehensively test pumped is 21481. A 24 hour constant

discharge test was carried out on 2 July 1982 at a rate of 33

L/s. At 1400 minutes the bore forked and maintained a constant

discharge of 30 L/s until the completion of the test. Figure

A2(a) shows drawdown against log time for this test. Analysis

of the results gives a value of 446m2 /day for transmissivity.

For the duration of the constant rate test bore 6035, which is

55m from 21481, was monitored. The plot of drawdown against log

time for this can be seen in Figure A2(b). The results of the


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test were analysed and a value of 324m'/day was calculated for

transmissivity.

On 5 July 1982, a series of step tests were carried out on bore

21481 at rates of 27 L/s, 30 L/s and 33 L/s. The results can be

seen in Figure A2(c)

2.3 Groundwater Movement and Recharge

Very limited data exists on the recharge mechanism for this

aquifer system. It is expected, however, that recharge will occur

through the weathered fractured basalts and dolomites that occur

in the broken and fractured zone of the east-west trending fault

irrcrnediately to the south of the production bore (refer Figure

2.l(b)). Water levels in the borefield are similar to water

levels in the Roper River during the dry season, indicating that

these two water bodies might be closely interconnected. Seasonal

groundwater water level variations have never been ascertained.

For the purpose of this work, a seasonal variation of 3m a year

has been assumed. Insufficient data exists to estimate the

sustainable yield

equivalent to a

sustainable.

of the borefield.

continuous yield

2.4 Water Quality

However, current extraction

of 11 L/s appears to be

Water quality data available for the bores drilled at Ngukurr is

summarised in Table 2.4.

Bores 4099, 4100 and 7870, are all located on the low-lying

Walmudga flood plain. Their waters are brackish and are unfit

for human consumption. The salinity of these bores is due to

recharge from the Roper River during periods of low flow v1hen it

is subject to saline tidal influences. This occurs at the end

of the dry season.

The water quality for production bores 5955, 6035 and 21481 is

within the drinking water guidelines adopted by the Nt Department

of health (Reference 7) with the exception of the sample taken

on 10 August 1982 from bore 5955, which indicated a total

hardness of 626 mg/L. This sample would have been affected by

drilling and workover activities that took place in the borefield


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in June and July 1982. However, the water from the borefield is

generally hard and many chemical parameters marginal. The

hardness of the water is due to the limestones/dolomites of the

Kookaburra Creek Formation. The water will be corrosive due to

the high C02 levels. This can be alleviated by degassing

techniques (once the water has been pumped to storage

facilities), but this may in turn lead to scaling problems.

Further study of these problems is required.

Diesel was spilled down production bore 6035 in 1982. Although

the bore was subsequently cleaned out, there is a possibility

that this was not 100% successful due to the properties of diesel

(ie it floats on water) This being the case, further work

should be undertaken to determine the extent of the

contamination.

Technical R

eport WR

D92041

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age 18 of 70.

TABLE 2.4 WATER QUALITr DATA

QUALITY (mg/L)

BORE DATE pH SPEC TDS Na K Ca Mg TOTA!, TOTAL Fe Si02 Cl so, N03 HCO, F NaCl COND HARDNESS ALKAL

4098 10/10/63 7.3 360 312 2200 310 4950 4098 17/10/63 6.7 2500 330 6500 4099 10/10/63 7.3 1800 340 3000 4099 10/10/63 7.8 1650 260 3000 4099 17/10/63 7.5 1900 410 3000 4100 17/10/63 7.3 5100 350 1600 5955 20/11/67 7.7 1500 1027 95 10 90 82 565 338 1. 3 40 0 184 0 -5955 20/12/67 8.0 535 8 6 4 69 298 282 4 10 0.3 172 0.4 -5955 16/11/68 7.7 1500 840 103 7 66 78 560 332 0.2 300 19 <1 203 0.9 -5955 10/08/82 7.1 1610 920 88 9 106 88 626 340 1.4 24 320 35 1 115 0.3 530 5955 06/06/85 7.6 1330 710 66 5 94 74 538 367 0.1 29 220 22 1 448 0.3 370 6035 12/12/67 7.9 1159 707 82 14 13 101 455 338 0.1 55 0 1.5 206 0.2 -6035 12/12/67 7.7 1008 700 70 11 7 104 450 304 2.6 40 0 0.4 185 0.2 -6035 08/12/67 7.7 1153 705 70 10 12 116 515 352 0.6 55 <.1 <.1 215 0.2 -6035 lQ/08/82 7.0 1230 690 58 8 91 70 515 384 0.3 166 29 1 468 0.2 274 7870 26/05/72 7.5 26490 8000 88 1010 107 1664 7870 26/05/72 7.3 27000 8000 75 1036 92 1697 7870 26/05/72 7.2 26490 8000 85 1020 104 1681 7870 16/01/76 8.0 1200 435 294 189 359 311 7870 12/03/76 8.0 1220 495 361 181 440 298 9325 07/02/79 8.2 870 520 23 13 60 80 478 <.1 52 14 22 1 0.7 -

21503 12/06/82 7.7 1090 610 so 39 38 81 427 372 0.9 20 140 28 2 543 0.3 230 21503 12/06/82 7.5 1150 630 53 9 60 81 482 343 0.3 19 175 24 1 418 0.2 290 21505 14/06/82 7.4 760 430 25 10 59 44 328 290 27 70 14 4 354 0.3 112 21506 14/06/82 7.4 1330 790 78 10 86 79 539 352 4.0 24 224 42 2 429 2.0 368 21481 15/06/82 7.3 1200 670 75 12 81 56 433 281 24 200 34 9 343 0.6 330 21481 02/07/82 7.0 1360 720 70 8 96 74 543 370 1.3 25 230 24 <1 451 0.3 370


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3 • SURFACE WATER SOURCE

This section outlines the available surface water data for the

Roper River at Ngukurr. It analyses available data and makes a

preliminary evaluation of the river water source.

3.1 Roper River Flow

The catch.~ent area of the Roper River at Ngukurr is some 75000

km2 and its flow behaviour is influenced by three main streams,

all of which have a streamflow recorder situated on them. These

are the Roper River at Red Rock (GS 9030250), the Wilton River

at Qualari Waterhole (GS 9030146) and the Hodgson River at Wulli

Pulli (GS 9030102) (refer Figure 3.1) Available low flow data

for each station is shown in Tables 3.1, 3.2 and 3.3.

3.1.1 Flow at GS 9030146 (Wilton River)

This station is situated on the Wilton River some 20kiu from its

confluence with the Roper River. A sUiumary of available data at

this site is shown in Table 3.1. According to the flow record

at the gauge, the Wilton River at GS 9030146 ceases to flow

during most years and normally ceases to flow before the Roper

River at GS 9030250. The quality of water in the Wilton is

good and features low salinities and low hardness (refer Tables

3.4 and 3.5).

3.1.2 Flow at GS 9030102 (Hodason River)

This station is situated on a large pool approximately 20km from

the Hodgson River confluence with the Roper River.

available flow data at this site is shown in Table

A summary of

3. 2 .

As can be seen from the flow data, the Hodgson River ceases to

flow for an extended period during every dry season. Therefore

the Hodgson river has little or no bearing on the dry season base

flows in the Roper River.

3.1.3 Flow at GS 9030250 (Roner Riverl

This station is situated on the Roper River upstream of Roper Bar

and hence upstream of the confluences with both the Hodgson and


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Wilton Rivers. Wet season flows at this site reflect seasonal

rainfall patterns over a large catchrnent area. Dry season flows

are maintained by groundwater outflow from the Mataranka area in

most years.

The magnitude and length of dry season flows is controlled by the

availability of groundwater. The extent of base flow variability

can be represented by way of correlation to the moving three year

rainfall for the upper catchment as shown in Figure 3.2. As can

be seen from Figure 3. 2 and Table 3 . 3, the cease of flow in

1966/67, 70 and 71 can be related to the low moving average of

rainfall for the same period. The data tabulated in Table 3.3

indicates that no-flow periods of at least four months have

occurred previously.

A study of water quality above and below Roper Bar in 1980 and

1986 highlighted discontinuities in the salinity levels between

the sites (refer Tables 3.4 and 3.5). Decreases in salinity

levels downstream of Roper Bar to a site near Ngukurr suggest

that either a volu.me of low salinity water is being introduced

to the river systa~ in this area or the storage of low TDS flood

water held in pools in this section of the river is extremely

large compared to the base flows.

Whilst some flow may occur into the Roper River downstream of the

GS 9030250 recorder site after ceasing to flow at GS 9030250, it

is doubtful that this would be of sufficient volume to greatly

affect salinity levels in the Roper River.

Storage of low salinity flood waters (refer Table 3.6) in the

river within large pools between Roper Bar and Ngukurr represents

a possible explanation of the lower salinities in this section

of the river. However, further analysis of the flow mechanisms

in this section of the river is required before a complete

understanding of the salinity reduction between Roper Bar and

Ngukurr will be possible.

3.2 Water Quality

The chemical quality of river water adjacent to Ngukurr is

acceptable most years with salinity levels going above acceptable

limits normally only towards the end of some years where the


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01 :& 1_,,/ ~~ :2 M: ~ ~ , ..... ~ ~ l ~.-_. I

; ~ /i ~1~~ :, : / : .... '\[~ I t I / I I

- -_ J_ - - - - --- - -- ---~~ - - - ----- - --- - ~ - -Butmet:a - - - - J_ ----- - - --------1---- ------ ------~ --- --------- - _j_ -i : ~"' i // j l l- ffl!o'S: : } : / : l i g¢.la_...," ', ',' ', I I t -......::, ~ -, , I ... , ' , "' , I I ~I I 9si, I

I 1 f ~I J : "$> : : ~ l ' Mountain : / : .s.e : : "i - ' l ' Valley sa .~ : I

' '6 I 'Ci ' • - 11'.1ainoru 1 • ~ 1 ........ 1 I \'!:. - I I 1 , . ..., ! ---:-- --- --- g-----~- --\.~'=G~o3Crf0a-- -------s1 -:- ------ ---------:-- ------- ----- ~ -~~;---- ------: ~--..J'..,.--/~ : : .. 11 l : I f l '-. 1t; I 1 I I -

GS9i030089 / l ", "" : 1 .Ji": : ,,.. ~umbu!wa I ..e.. I \ I <., L 'II I / I 1 / <"'0 _ , I 1 1 .~ ""'~ , .,,.. 1

: ,,. ..... ..,.. : ~~-f" : :"# j/ ~ ,,,. : 1 ,, / ~.,. : : ;.:... - ... ~ GS9030250 Bt;; ~' ' -<:: j 1

__ es~~~GSS~09Qj- ___ ------~·~~- ________ l __ ~_[_ __ti ____ -~ ________ ---- --~--: \_~ I .,. ' : .... ' S4 I GULF ' : ~ : .,.~~ -C'"~1tl' 13 12 _ 1q l ~ ~ ~ : 14 ,- 11 Pb.t::?T Of ~

<1" 1 -:.it-' Roper 1· RdPER : ~ ;01s ROPD 19~ot"· Bar A6pt. , 4 'i I

; i A3 ~1 \~ CARPE1'lTARIA~ ; A4 <J; }-. I

l ~ : A7 Ai5 I ' ~ :

--,;;(lt'ii~~ l GS90301Q2 ~ ' , ~-... :

1 _ • is9oi~;~;t---r~ -------------r-~~----------T~~~f--------~;------- ~~------·-- ------------T-

~ J!--. AS: :r ~Af-1 \ : : Hodgson Downs : ~O : \ 1

\ 1

1 1: : I ~ ., I I I ' I I ;;_, I , l I \, :

~. l - ~ '~ I I -~ I 'to\i ~ ; I\ I i m I i ---t -- -----------1 --- ------------p~ ---~%¢"- ---1------- ---------i--~ --------~ -~a~h;~ -RJ,;;r------~- -i "\. Larrlmati ;J ~ : 1111; \ : I N I I :. \.I I 1 Q)r 1 1 a:; 1: '

UJ4 I I ...... I~ lW

EJ : JI A { •,'oE 01 I l ~ ·~ I

g l : Nutwood Oowhs 1..": :g

--~:e2ooooom01 ~---i- ---------,,.::: / \ _____________ _.: ------- ~~~---f---------- ~ -__ ;\ ___ 825oooom~.Jl~ I ::C I / ! I \ I

j ~ ~ ,// ~ : : I ~ I § l \ : : "<---l- ~/ I \

Dal.} Waters / i '4 ~.a1Jhin1~ Oo\'lns

I I ·- - -..,\

km 50

&BS

~GS9030001

0

SAMPLE WATER

GAUGE

MINOR

50 100 km

POINT 1986 WATER QUALITY SURVEY

STATION

ROAD

STREAMFLOW RECORDER STATIONS LOCATION MAP

Fig. 3.1

Technical R

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E E

_J

1800-

1600

1400

------RAINFALL KATHERINE ------LOWEST FLOW AT GS9030250

ROPER RIVER (m 3 /s)

;;! 1200

LL z <( a:

.,, -· cc . ('..) •

1000 MEDIAN

-1.5 800

1.0

600

0.5

400-l-----~---~---~---~---~---~---~---~---~-~L-'t---L--~---+-o

1870/71 80/81 90/91 1900/01 10/11 20/21 30/31 40/41 50/51 60/61 70/71 80/81 90/91

YEAR

THREE YEAR MOVING AVERAGE RAINFALL KATHERINE 1873 - 1984

Technical R

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-E n n

0 ., z

,, -· (Q • (,) .

------SALINITY LEVELS AT NGUKURR

------TIDAL VARIATION

800

600-

400-

200-

HIGH TIDE

LOW TIDE o+-L---"----'---'L-.--'---"-----'---"o--'---''----'---'--.------'---+----'---'----'----."---'---'-----'-----,--'-----"-'--'---~-..i

9/11/64 11/11/64 13/11/64 15/11/64 17 /11/64 19/11/64

SALINITY AND TIDAL VARIATION 1964

21/11/64 23/11/64

Technical R

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E u u

0 "' z

-· (Q • (.)

.i:a.

------SALINITY LEVELS AT NGUKURR ~----TIDAL VARIATION

- - - - - - - - - SALINITY LEVELS AT WILTON RIVER

800 8

600 6

400 4

,_ Q) Q) -,_ .c: Ol Q) .c:

z 0 f-<(

er: <(

> w 0 f-

o+--------.-------~-------~------~-------.--------t-0"---------J~ 11/11/66 13/11/66 15/11/66 17 /11/66 19/11/66 21/11/66

SALINITY AND TIDAL VARIATION 1966

23/11/66


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TABLE 3.1

1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986

FLOW HISTORY FOR WILTON RIVER

SUMMARY OF LOW FLOWS AT GS 9030146

MINIMUM FLOW (m3 /s}

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.13 0.10 0.24 0 .21 0.0 0.0 0.0 0.0 0.0 0.0

PERIOD OF NO FLOW

19/06/64 - 25/11/64 13/10/65 - 14/12/65 16/07/66 - 27/01/67 17/08/67 - 18/01/68 12/09/68 - 21/12/68 20/09/69 - 20/12/69 07/06/70 - 06/12/70 05/08/71 - 07/11/71 28/07/72 - 09/12/72 16/09/73 - 19/11/73 18/11/74 - 13/12/74

11/10/79 - 03/01/80 16/10/80 - 08/12/80 10/11/81 - 21/11/80 22/09/82 - 11/12/82 13/08/83 - 01/12/83 09/10/84 - 26/12/84

approx approx approx approx approx approx approx approx approx approx approx

approx approx approx approx approx approx

5 months 2 months 6 months 5 months 3 months 3 months 6 months 3 months 4.5 months 2 months 1 month

3 months 2 months 11 days 2.5 months 3.5 months 2.5 months

0.0 27/09/85 - 05/11/85 approx 1.5 months 0.0 03/07/86 - Station closed 30/10/86


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TABLE 3 .2.

1965 1966 1967 1968 1969 1970 1971 1972 1973

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986

FLOW HISTORY FOR HODGSON RIVER

SUMMARY OF LOW FLOWS AT GS 9030102

MINIMUM FLOW (m3 /s}

No record 0.0 0.0 0.0 0.0 0.0 No record 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

PERIOD OF NO FLOW

No record 27/03/66 - 05/12/66 25/05/67 - 30/12/67 05/07/68 - 26/12/68 09/05/69 - 19/12/69 02/05/70 - 13/11/70 No record 01/06/72 - 15/01/73 09/05/73 - 16/06/73 11/08/73 - 20/11/73 30/07/74 - 06/12/74 01/08/75 - 12/11/75 29/06/76 - 14/01/77 26/06/77 - 11/01/78 No record 01/06/79 - 04/01/80 24/05/80 - 21/11/80 01/06/81 - 20/11/81 14/06/82 - 14/12/82 06/06/83 - 22/11/83 06/06/84 - 16/11/84

approx approx approx approx approx

approx and approx approx approx approx approx

approx approx approx approx approx approx

8 months 7 months 5.5 months 7 months 6.5 months

7.5 months

4.5 months 4.5 months 3.5 months 6.5 months 6.5 months

7 months 6 months 5.5 months 6 months 5.5 months 5 months

0.0 08/07/85 - 04/11/85 approx 4 months 0.0 02/05/86 - Station closed 29/10/86


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TABLE 3.3

1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

FLOW HISTORY FOR ROPER RIVER

SUMrA"..ARY OF LOW FLOW AT GS 9030250

MINIMlJM FLOW (m3 /s)

0.00 0.00 0.29 0.09 0.00 0.00 No record 0.00 0.09 0.70 1.30 1.00 1.00 0.50 0.66 0.79 0. 75 0.60 0.80 0.90 No record 0. 35 0 .25 0.30 0.08 0.40 0.40

PERIOD OF NO FLOW

08/09/66 - 13/01/67 127 days 14/09/67 - 01/12/67 79 days

25/09/70 - 25/11/70 62 days Missing record approx 60 days

Missing record approx 30 days Missing record

Missing record

Missing record

Missing record

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T AB L E 3.4

l\Ol'MR RIVER WATER QUALITY 1966 ALL VALUES EXCEPT PHOSPHA'l'E IN mg/L-1

SITE DISTANCE DATE TIME SAl<!P- SPEC pH 00 TURB Na K ca Mg HARD ALK Fe SiO~ Cl so, NO, PO, HCOJ F NaCl UPSTREAM LING COND ~ IN FROM bEPTH NTU MOUTH(km) ( rn)

Ngukurr 106.0 OB/10 1400 0.5 450 8.5 96 11 35 4 34 22 145 0.4 1 54 28 1 177 0.2 89 116. 0 09/10 1430 0.5 566 B.5 96 12 46 5 40 28 174 0.4 6 75 50 1 212 0.2 124 125. 0 08/10 1345 0.5 654 B.5 95 12 52 6 43 29 107 0.6 8 82 60 1 228 0.2 135

Mouth of 134. 0 Hodgeon 137. 0 08/10 1140 0.5 903 8.4 94 3.5 82 9 50 43 219 0.2 15 122 96 1 267 0.3 201 River

l'.iouth of 142. 0 08/10 1100 0.5 1090 8.4 97 0.5 101 11 52 48 230 -<0. 1 17 159 120 1 281 0.3 262 Wilton River

Roper 147.0 08/10 0955 0.5 1440 B.5 117 0.4 157 16 58 63 249 0.1 18 117 180 1 304 0.4 193 Bar

GS9030520 158.5 10/10 1130 0.5 1610 8.4 103 171 18 70 57 261 --:0.1 16 261 212 1 318 0.5 430 at Red Rock

Technical R

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TA B L E 3.5

ROPER RIVER WATER QUALITY 1986 ALL VALUES EXCEPT PHOSPHATE IN mg/L-1

S!'l'E DIS'l'ANCE DATE TIME SAMP- SPEC pH 00 TURB Na K Ca Mg I!ARD ALK >'e SiO.a Cl so, NO, PO, HC03 F NaCl OPSTREAI>l LING COND % IN FROM DEPTH NTU MOUTH(km) (m)

Near 113.5 25/06 1345 0.5 280 8.5 96 54' 15 4 16 11 85 83 2 .2# 3 20 12 1 <5 101 0.1 33 Ngo.kurr 122.5 25/06 1310 0.5 270 8.3 95 41' 16 4 1B 12 94 90 1. 7tt 4 22 13 1 <5 110 0.1 36

133.0 13/06 1330 0.5 3;l0 8.4 120 35' 19 4 23 13 111 107 1.6# 6 25 16 1 <5 131 0.1 41

Mouth of 134. 0 Hodgson 138. 0 13/06 1710 0.5 390 0.4 94 25' 27 4 27 17 138 130 0.9 10 35 22 1 ,5 159 0.1 58 River

Motlth of 142.0 15/06 1545 0.5 520 8.3 16 40 5 32 21 166 157 0.9 13 55 32 1 <5 192 0.2 09 Wilton 145.0 26/06 1030 0.5 690 B.2 3 55 7 ·16 29 217 189 0.2 16 80 49 2 <5 231 0.2 133 River

GS9030520 153.5 20/06 0955 0.5 830 8.3 2.1 78 9 44 35 254 210 0.3 18 110 63 2 -<5 250 0.2 175 at Red Rock

* - DENOTES BXCBBSIVB TURBIDITY LEVELS

# DENOTES EXCESSIVE IRON LEV:BLS


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TABLE 3.6

SELECTED WATER QUALITY PARAMETERS - ROPER RIVER NGUK!JRR

D.l\.TE

12/11/74 14/11/74 19/11/74 21/11/74 25/11/74 05/12/74 09/02/75 04/03/75 13/03/75 26/03/75 24/04/75 08/05/75 22/05/75 19/06/75 03/07/75 24/07/75 14/08/75 09/10/75 09/10/75 20/10/75 06/11/75 21/11/75 05/12/75 20/01/76 13/02/76 27/02/76 23/04/76 06/05/76 20/05/76 03/06/76 01/07/76 24/07/76

CONDUCTIVITY us/m

210 290 380 430 450 510

am 570 pm 590

630 600 650 720 180 100

73 360 410 490 550 700 790

SUSPEl'JlJED SOLIDS mg/L

83 23

2 12 16

5 16 26 33 23

8 5 5

46 72 74 11

5 108

8 113

17

TURBIDITY NTU's

0.8 5.2 14 5.4 7.8 5.3 83 66 54 93 57 26 7.7 1.7 0.5 3 6.5 8 9.7 7 1.5 1.5 10 44 77 84 7.6

56 5

3.2 3.8


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Roper River ceases to flow relatively early in the dry season.

However, turbidity creates a problem and treatment is needed

sometimes for extended periods throughout each year. (Refer to

Table 3.6 for turbidity data for the period from November 1974

to July 1976). Limited data currently exists on the

bacteriological and liirL~ological quality of water in the Roper

River at Ngukurr.

River water adjacent to Ngukurr settlement has been sampled

continuously at various times, specifically to determine levels

of saline intrusion when river flows cease towards the end of the

dry season.

Salinity level variations with tidal levels are shown for periods

in the 1963 and 1966 (river ceased to flow in September) dry

seasons in Figures 3.3 and 3.4 respectively. As shown, there is

a direct correlation between the level of salinity in the river

water and the height of the tide in the river. Similar analysis

carried out between 30 July 1964 and 17 August 1964 at Ngukurr

displayed no correlation, with salinity levels being maintained

at 50 to 60 ppm irrespective of tidal variation (ie this being

earlier in the dry season when the river was still flowing) .

Laboratory analysis of various samples taken during December 1966

and January 1967 are shown below in Table 3.7.

TABLE 3.7 SALINITY AT VARIOUS TIDAL CONDITIONS

DATE TIME CHLORIDE(ppm) NaCl TIDAL CONDITION

21/12/66 1340 710 1172 High tide 28/12/66 0653 1125 1856 30 mins after high tide 02/01/67 0930 1380 2277 1 hr after record high

tide 03/01/67 1230 1270 2096 1 hr after high tide 24/01/67 0630 198 327 High tide outgoing 24/01/67 1530 328 541 Low tide 24/10/67 2210 298 492 After turn of small tide

* the samoles taken on 24/01/67 are affected by wet season flow beginning in the Roper river on 13 January with a flow of 121m3 /s occurring at GS 9030250 on 24 January. The reasonably high salinities still present may be due to the initial flushing of saline water at the start of the wet from upstream of Roper River.

From available flow data (Table 3.3) it can be seen that the

Roper River ceased to flow for 127 days from 8 September 1966 to


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13 January 1976. For the 1964 dry season, whilst there is no

recorded flow data, the three year moving average shown in Figure

3.2, together with gauge board readings at Roper Bar, indicate

a no-flow period of similar magnitude.

The data shown in Figures 3 .3 and 3 .4 indicate that salinity

levels in November 1964 reached a stage (NaCl greater than 400

ppm) where PU!uping of potable water would not have been possible

at even low tide. In the case of the 1966/67 dry season shown

in Figure 3.4, pumping of potable water would only have been

possible at low tides in November. This would be expected to

continue at least intermittently until the wet season flows

occurred in the middle of January. Correspondence from the

mission indicates a requirement to carry water from the Wilton

River for drinking water purposes during this period.

Correspondence also indicates that carrying of water from the

Wilton River was required during the 1962/63 dry season, although

there is no indication of how long a period it was needed.

A study of the data contained in Figure 3. 2 and Table 3. 3

indicates that for the 27 year period from 1966 to 1992, problems

with the che..-nical quality of the river water only occurred during

six of those years and then only for a period of two months per

year at the end of the dry season. This equates to less than 4%

of the 27 year period. It is possible that a detailed study of

the storage characteristics of

Ngukurr may provide a means

identifying the flow dynai-nics

the pools in the Roper River near

of alleviating this problem by

of the salt water and identifying

rock bars that may naturally (or with minor modifications) reduce

the effects of this late dry season intrusion of salt water on

high tides.


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4. COMPARISON OF SOURCES

From Sections 2 and 3 it is obvious that accurate analysis of the

two water sources at Ngukurr is difficult due to the lack of

suitable data.

The chemical quality of the groundwater source could best be

described as marginal with high hardness and NaCl levels. The

groundwater is corrosive unless facilities are provided to enable

degassing of the dissolved C02 • There is also a problem which

has resulted from the spilling of diesel down production bore

6035. Further work is required to determine the extent of

pollution and what clean-up work is required.

The physical properties of the groundwater are superior to those

of the river water and require no treatment.

Insufficient data exists to estimate the sustainable yield of the

groundwater resource. However, current extraction equivalent to

a continuous yield of 11 L/s appears to be sustainable.

Available data indicates that the chemical quality of the river

water source is superior to that of the groundwater source for

in excess of 95% of the period of record (1966-1992).

Insufficient data exists to adequately describe the physical

properties - turbidity, limnology and bacteriological quality -

of the river. It would be expected that more detailed studies

of these properties, in combination with the dynai-nics and storage

characteristics of the Roper River upstream and downstream of

Ngukurr, would minimise the problems being encountered with this

source.

The presence of lower salinity water in the Roper River below

Roper Bar suggests that either recharge of the river with low

salinity water may be occurring between Roper Bar and Ngukurr,

or the storage of low TDS flood waters held in pools in this

section of the river is extremely large compared to the input of

water from river base flows.

Section profiling and sampling of the river from Roper Bar to

Ngukurr in October would answer this question, as well as

identifying if more suitable sites exist for location of the pump


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intake for Ngukurr.

Quality and depth profiling at the present pump intake site would

provide information as to the possibility of varying pump intake

depth, with a view to avoiding pumping from the saline wedge when

it is present. The provision of a shut-off system for the river

Plli~ps dependent on salinity levels could also be incorporated.

Based on the chemical quality of the two sources, the water

supply should be sourced from the Roper River except for extended

periods of 'no flow' when the groundwater source would need to

be utilised in the latter months of the year.

Insufficient data exists to accurately describe the physical

properties of the river water source. However, problems with the

operation of the slow sand filter (and its low level of usage

since corrnnissioning) have been attributed to these properties.

Until further work has been undertaken to accurately describe the

properties (and hence recommended means of adequately treating

the water), it appears that usage of the groundwater source for

most of the year will be required.


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5. WATER DEMAND

Water demand is a function of population and per capita

consumption. The available population data for Ngukurr is listed

below in Table 5.1.

TABLE 5. l. NGUKURR POPUL.l'.TION D.Z\.TA

YEAR POPULATION SOURCE

1976 1981 1983 1985 1986 1991 2000

250 391 391 540 660 794 908

Australian Bureau of Statistics Australian Bureau of Statistics Dept of Community Development .1'.boriginal Development Commission Australian Bureau of Statistics Australian Bureau of Statistics Assumed population (for 1. 5% growth rate)

The present population of Ngukurr is approximately 800. However,

this figure varies due to the nomadic nature of some of the

population and the increasing decentralisation trends to

outstations. The population is likely to be highest during the

wet season when mobility decreases and supply to outstations

becomes more difficult. During this period there tends to be a

shift of population back to the main community at Ngukurr.

Water consu.~ption figures for the 161 day period from 29 August

1991 to 5 February 1992 indicated a total consumption of 179656

kL. This figure consisted of 152624 kL which was supplied from

the borefield and 27032 kL which was pumped from the Roper River.

The average consurr~tion for this period equates to 1390

L/person/day (assuming a population of 800) During this time

the peak 28 day consumption was 34160 kL or 1520 L/person/day.

The current

size. The

consumption at Ngukurr is high

recommended supply to cater

for a community if its

for col!lIIlunities with

populations over 200 (reference 6) is 800 L/person/day and 1200

L/person/day to cater for the peak demand.

From the above data, current and figure demands have been

calculated. This can be seen in Table 5.2.


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TABLE 5.2. CURRENT AND PROJECTED WATER DEMANDS

YE.AR

1992 2000

5.1

POPULATION

800 908

Water Supply

AVERAGE DEMAND (kL/d)

640 720

PE..l\.K DEV.LAND (kL/d)

960 1090

Water is supplied to Ngukurr from a borefield to the north

northwest of the corrrrnunity, as well as from the Roper River.

The borefield consists of bores 5955, 6035 and 21481, all located

within 100m of one another, approximately 3.5km north-northwest

of Ngukurr. Production bores 5955 and 21481 are serviced by

electrical reticulation, while 6035 is equipped with a 2 cylinder

diesel Lister motor and used as a standby bore.

Production bore 5955 is equipped with an electrified 720 Mono

pump and is currently supplying 6. 5 L/s (when pumping with

21481). This bore is cased with 140rrrrn NB steel casing and has

a recorrrrnended maximum continuous pumping rate of 12 L/s (pumping

alone). The bore is also fitted with a remote telemetry system.

Bore 21481 is equipped with an electrified submersible pump and

currently pumps at about 7 .3 L/s (together with 5955) with a

borehead pressure of approximately 400 kPa. However, it is

reported that when pumping alone, this pressure drops to

approximately 200 kPa, due to reduced friction losses and its

discharge rate increases to about 11 L/s.

Bore 6035 is equipped with a diesel driven borehole Plli~P unit

which has a rated supply capacity of around 4 L/s. The bore is

cased with 140rrrrn NB steel casing and has a recorrrrnended continuous

pumping rate of 12 L/s (pumping alone) . However, a 115rrrrn ID

perforated liner has been set inside the casing limiting the size

of pu.~p with which the bore can be equipped and thereby limiting

the rate at which the bore can be pu..-nped.

Table 5.3 shows current and recommended Plli~ping rates and pump

settings.


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. Tll.BLE 5 . 3 PUMPING Rl\.TES AND PUMP SETTINGS

RN

5955

6035

21481

PUMPING RATE L/s

6.5

4

7.3

CURRENT

PUMP SETTING (m)

48.7

36.6

36. 0

PUMPING RATE L/s

12

4

11

RECOMMENDED

Pu"MP SETTING(m)

!;8.7

36.6

36.0

The only bore comprehensively pump tested was 21481. Bores 5955

and 6035 should be retested using 24 hour constant rate tests and

multirate test to enable confident predictions of performance.

Water is trarcsferred from the borefield to the community storage

tanks by 3900m of lOOmm NB rising main. The main is generally

constructed of PVC below ground, but has several sections of

galvanised steel with victaulic coupling above ground on concrete

plinths along sections where hard rock outcrops occur. It is

thought that by increasing the diameter of the mains, friction

losses would drop thereby increasing the yields from the pu_~ped

bores.

Water is also obtained from the Roper River by way of three

submersible pumps housed in 150mm diameter pipe. River water is

used mainly as a backup supply or to top up the tanks. The river

supplies about 15% of Ngukurr's domestic water, with only one or

two of the river pumps pumping for about twelve hours a day.

The presence of algae during low flows and turbidity during high

flows, decreases the quality of the river water. In 1981 a slow

sand filter was commissioned to remove algae and suspended

solids, however, difficulties were experienced due to filter

clogging and the plant was abandoned. The seasonal variation in

the quality of river water also is a problei""Tl. However, it is

acceptable for most of the year, only rising above acceptable

levels towards the end of the dry season. S~bsequently, it is

considered the best practice to only use river water when the

borefield is unable to meet demand and when turbidity and saline

levels are acceptable (readily determined by sight and taste by

the operator) .


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The river pumps discharge to the community distribution storage

tanks by way of a 150mm NB galvanised steel pipeline with screwed

joints above ground on concrete plinths. Water from both the

river and borefield is pumped to a 450 kL ground level tank.

Water is transferred from the ground level storage to a 90 kL

elevated tank by two electric motor driven centrifugal pumps.

A chlorination dosing plant treats water as it is transferred

from ground level to elevated storage.

Water gravitates to the community by way of a 150mm NB PVC main.

Water is reticulated through the community in lOOmm NB and 150mm

NB PVC mains. 54 Millcock type fire hydrants are provided at

approximately 90m centres along the mains.


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6 • CONCLUSIONS

Ngukurr's domestic

approximately 85%

water supply is currently co.cr~osed of

groundwater and 15% river water. The

groundwater is supplied from three production bores; these are

RN 5955, 6035 (used as a standby) and 21481. The aquifer is at

the basal contact of the Yalwarra Volcanic Member with the

underlying sediments of the Kookaburra Creek Formation.

Current extraction rates show that a continuous yield of 11 L/s

appears to be sustainable for the borefield. The water quality

of the groundwater is marginal, with the waters having high

hardness and NaCl levels. Water quality from Roper River is

variable, depending on the time of year.

gone above acceptable limits only towards

Salinity levels have

the end of some years.

However, turbidity can be a problem and treatment is sometimes

needed for extended periods throughout each year.

The current supply rates for the production bores are 6.5 L/s for

5955 and 7.3 L/s for 21481 when puzrrping in conjunction with 5955.

The rate for 21481 increases to approximately 11 L/s when it is

pumping by itself (due to reduced friction losses). Bore 6035

is capable of supplying 4 L/s, however, contamination has

occurred due to the spillage of diesel down the borehole.

Therefore, 6035 should not be used until the extent of the

contamination has been determined and any subsequent clean up

work has been undertaken.

Water from Roper River is supplied via three axial flow pumps.

Insufficient data exists to accurately describe the properties

of the river water. Until further work has been undertaken and

adequate means of treating the river water (physical and

chemical J are being utilised, usage of the groundwater source for

most of the year will be required.


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7. RECOMMENDATIONS

It is recommended that:

( i) The pumping rate and pumg settings be in accordance

with table 5. 3. However, the regime of borefield

extraction should not exceed 11 L/s until such time

that work leading to an assessment of the sustainable

yield of the resource indicates that this is feasible.

(ii) Production bores 5955 and 6035 be retested to

ascertain the performance characteristics.

(iii) Water quality analysis be taken from bores Rl~'s 5955,

6035, and 21481 biannually.

(iv) Section profiling and sampling of the river from Roper

Bar to Ngukurr in October be undertaken. This will

determine where the low salinity water is coming from

at this time of the year and also identify a more

suitable site for the location of the pump intake.

(v) A provision for a shut-off system for the river pumps

dependent on salinity levels should be incorporated.

(vi) Further work be undertaken to determine the extent of

the contamination due to the spilling of diesel down

RN 6035 and what cleanup work is necessary.

(vii)

(viii)

A rain gauge be set up and daily rainfall readings

taken.

All existing bores be surveyed to a common datum.

(ix) A water use study be undertaken to determine the

causes of the high consumption rate. Efficient water

usage practices should be encouraged and consumption

and wastage reduced where possible.


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Water Resources Division

PAWA

B Smith

Kinhill Stearns, 1985

Pietsch, B.A. et al 1991

8. REFERENCES

Roper River 1980 and 1986 Water

Quality Surveys

"Water Supply Investigations,

Roper River, Yugul Cartle Co."

Registry File No 4/68/36, Parts I

and II.

"Badaarka Surface Water Sources",

Water Resources Division, PAWA, NT.

"Bamyili, Bulman, Lajamanu,

Ngukurr, Investigation for Water

and Sewerage Service".

"McArthur River Region 1: 100 000

Geological Map Series" , Northern

Territory

Explanatory

Geological Survey,

Notes. 6065-6165.

National Health and Medical Research Council and Australian Water

Resources Council G . d 1 . f' D . k . '"' . " ui e ines _or rin ing ,,ater in

Australia, 1987". Australian

Publishing Service, Canberra.

Northern Teritory Government, 1991

Wallis, D. 1984

"Interim Guidelines on the level

of Essential Services to

Aboriginal Communities".

"Tecli.nical Report on the Status

of Ngukurr Water Supply", Water

Resources Division, PAWA, NT.


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APPENDIX A

NGUKORR GROUNDWATER INVESTIGATIONS


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APPENDIX A

1. Drilling

Various groundwater investigations have been conducted around

Ngukurr. Drilling programmes were undertaken in 19 61, 19 63,

1967, 1978 and 1982 and have resulted in a total of 27 bores

being drilled, including three production bores.

The first attempt to locate groundwater supplies around Ngukurr

was carried out in September 1961, in which bores 2725 to 2743

were drilled. All were dry holes, except 2743, which yielded

0.25 L/s, however, the water was high in NaCl and was

unacceptable for drinking purposes.

In September 1962, four bores were drilled in the flood plain to

the east of Ngukurr. The bores, 4219, 4098, 4099 and 4100,

produced yields ranging from 0.25 L/s to 4.5 L/s, however, high

NaCl content made the water unacceptable for conslli~ption.

Further drilling in November 1967, approximately 3.5km north

northwest of Ngukurr, resulted in two bores - 5955 and 6035 - in

close proximity to each other. The bores had estiwated yields

of 12.5 L/s when pu..-rrped separately and produced water suitable

for drinking. Both bores were subsequently constructed as

production bores.

From May to June 1972, bores 7868, 7869 and 7870 were drilled.

Bores 7868 and 7869, which were approximately 12km and 21km north

of Ngukurr respectively, were dry, whilst bore 7870, located on

the flood plain to the east of the community, produced a yield

of 2.5 L/s. However, the water was not suitable for drinking

purposes.

A further drilling programme was undertaken in September 1978.

The drilling resulted in bore 9325 which produced 0.6 L/s of

potable water, as well as two dry bores, 9323 and 9234.

In July 1982 a further drilling programme was conducted in which

bores 21503 to 21507 and bore 21481 were drilled. Bores 21503,

21504, 21505 and 21506 were drilled in the vicinity of the

Showell Creek fault. Bores 21503, 21505 and 21506 produced


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yields of potable water of 1.5, 1.3 and 0.8 L/s respectively,

whilst bores 21504 and 21507 were dry holes. Bore 21481, which

was drilled as a replaca~ent for production bore 6035, produced

a yield of 30 L/s when pumping alone and was constructed as a

production bore.

The Ngukurr borefield currently comprises bores 5955, 6035 and

21481, which are all located within lOOm of one another in a

small area 3.5km north-northwest of the community. All other

bores surrounding Ngukurr have either no water, water of an

inferior quality or water of insufficient quantity.

Table A1 provides interpretive logs of all bore holes drilled

around Ngukurr.


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TABLE Al LITHOLOGICAL LOGS

REG'D NO

2735

2736

2737

2738

2739

TOTAL DEPTH(m)

17.4

3.8

31.7

10.2

12.8

INTERVAL (m)

0.0 - 3.4 3.4 - 9.1 9.1 - 11.6

11.6 - 12.2

12.2 - 15.5 15.5 - 16.5 16.5 - 16.8 16.8 - 17.3 17.3 - 17.4

0.0 - 0.6 0.6 - 3.7

3.7 - 3.8

0.0 - 2.4 2.4 - 3.7

3.7 - 5.6 5.6 - 31.7

0.0 - 3.7 3.7 - 6.1

6.1 - 7.0 7.0 - 7.6 7.6 - 10.1

10.1 - 10.2

0.0 - 3.7

3.7 - 9.8

9.8 - 10.4

10.4 - 12.4

12.4 - 12.7 12.7 - 12.8

LITHOLOGICAL DESC..."R.IPTION

COMMENTS

Brown clay No water Fine drift clay struck Coarse sand & gravel Grey & yellow clay with gravel Grey clay Sand & silt Grey clay Grey silty clay Fractured quartzite too hard to drill

Sandy top soil No water Ironstone conglom- struck erate Hard conglomerate, unable to drill further

Yellow clay & silt Seepage Conglomerate & boulder water worn gravel Clay Red brown shale with odd pieces of grey shale & yellow mudstone. Drilling became harder with depth.

Yellow clay No water Grey sandy clay struck with ironstone gravel Red brown shale Grey & red brown shale Very hard red brown shale Undrillable strata

Solid red sandy No water clay, soft yellow struck clay with calcareous sandstone pebbles & boulders Fine yellow drift sand & weathered sandstone boulders Coarse sand - white & yellow Coarse sand & gravel, some white & yellow clay Boulders Hard fractured quartzite


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REG'D NO

2740

2741

2742

2743

4098

4099

TOTAL DEPTH(m)

10.6

16.1

11.8

21.6

85.3

38.1

INTERVAL (m)

0.0 - 0.9 0.9 - 4.9

4.9 - 10.6

0.0 - 4.9 4.9 - 7.3

7.3 - 8.5 8.5 - 9.1 9.1 - 9.8 9.8 - 16.1

0.0 - 2.7 2.7 - 4.6 4.6 - 9.8

9.8 - 11.8

0.0 - 9.1

9.1 - 10.7 10.7 - 17.4

17.4 - 18.0 18.0 - 19.2 19.2 - 21.6

0.0 - 30.5

30.5 - 32.0 32.0 - 33.5 33.5 - 36.6 36.6 - 41.1

41.1 - 57.9 57.9 - 79.3 79.3 - 85.3

0.0 - 27.4

27.4 - 30.5

30.5 - 32.0 32.0 - 35.1

LITHOLOGICAL DESCRIPTION

COMMENTS

Solid yellow clay No water Grey, yellow & pink clay White & brown rubble basalt quartzite, jasper & clay too hard to drill at 10.6m

Red sandy clay No water Fine yellow drift sand Sand with some clay Coarse sand & gravel Boulders & broken rock Hard & soft bands of porcellanite with odd pieces of quartzite & jasper

Black & grey clay No water struck

& chocolate Red clay Blue grey clay Sand seam at 9.lm Red brown shale, hard at ll.8m no penetration

too

Grey yellow & chocolate 0.25 L/s

clay, some silt at 19 .2m Sand & silt, some clay Grey & chocolate clay, some silt Sand seams Grey clay Boulders & sand, water worn gravel

Reddish brown Dolerite 0.5 L/s Dolerite & brown shale Dolerite Limestone & red shale Reddish brown shale, calcareous shale, limestone & dolerite Dolerite

li:µ:tab le

from 85m uq:otable

Dolerite & fawn limestone Fawn & white limestone

Dolerite with brown grey clays, calcareous clay Pink, cream & fawn limestone Green & brown Dolerite Yellowish-brown limestone

4. 5 & L/s from 33m

unpot able


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REG'D NO

TOTAL DEPTH(m)

4099 cont'd

4100 19.4

4219 44.0

5955 57. 9

6035 50.6

INTERVAL (m)

35.1 - 38.1

0.0 - 3.0 3.0 - 9.1

9.1 - 11.0

11.0 - 11.6

11.6 - 12.2 12.2 - 13.7

13.7 - 15.2 15.2 - 19.4

0.0 - 1.5 1.5 - 22.9

22.9 - 36.6 36.6 - 38.1 38.1 - 39. 7 39.7 - 41.2 41.2 - 42.7 42.7 - 44. 0

0.0 - 3.1 3.1 - 12.2

12.2 - 13.7 13.7 - 18.3

18.3 - 21..3 21.3 - 41.. 2 41.2 - 48.8 48.8 - 54.9 54.9 - 57.9

0. 0 - 3.0

3.0 - 12.2

12.2 - 13.7

13.7 - 18.3


COMMENTS

Yellowish-brown & fawn limestone

Brown clay Fine brown sand Brown sand & grey clay, laterite mudstone Laterite, siliceous oolitic material, black to grey clayey sandstone Pink quartzite Brown siltstone & sandstone, clay Brown sandstone Black & fawn banded siltstone & fine brown sandstone

Yellow clay Feldspathic sandstone with purple siltstone Reddish brown Dolerite Dolerite & limestone Fawn limestone

0.2 L/s

from 17m unp;:table

0 . 2 5 L I s from 37m unp;:table

Green & red calcareous Fawn & grey limestone Reddish brown Dolerite

shale

Soil & basalt Basalt Brown shale Shale with hard basalt ledges No returns Clay & loose basalt Loose basalt

Production yielding 12.5 L/s

Firm to hard basalt Slightly softer basalt

Top soil: red clay- Productey, sandy fragments, ion bore very weathered red yield-basalt ing Basalt: soft, red, 12.5 L/s very weathered. Also present is sandstone (4.5 - 6.lm) fine quartz sand in a 20% clayey ferruginous matrix; claystone (7.6 - 9.lm) white, sandstone (9.1 - 10.7m) red & yellow & chert; claystone (10.6-12.2m) red Silty clay, red, containing red & yellow siltstone Sandy shale - sandstones red


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REG'D NO

TOTAL DEPTH(m)

6035 cont'd

7868 106.7

7869 122. 0

7870 48.8

9323 15.0

9324 35.0

9325 31.5

INTERVAL (m)

18.3 - 22.9

22.9 - 27.4

27.4 - 32.0

32.0 - 37.1

37.1 - 38.1 38.1 - 39.6

39.6 - 41.1 41.1 - 44.2

44.2 - 50.6

0.0 - 24.4 24.4 -106.7

0.0 - 0.9 0.9 -109.7

109.7 -122.0

0.0 - 9.1 9.1 - 48.8

0.0 - 1.0 1.0 - 4.0 4.0 - 15.0

0.0 - 9.0

9.0 - 12.0

12.0 - 22.0 22.0 - 30.0 30.0 - 32.0 32.0 - 35.0

0.0 - 8.0 8.0 - 13.0

13.0 - 16.0

16.0 - 19.0

19.0 - 20.0


CC1YJMEN'TS

Basalt, weathered, has chlorite vesicles, pink, red & grey. Also present - red sandstone & siltstone & quartz Basalt: red/grey, red siltstone & sandstone, also pink-green feldspathic sandstone Basalt: red, red comglomerate sandstone & red siltstone Red weathered basalt & red siltstone Red fresh basalt Blends of impure chalcedonic silica. Also quartz & a yellow sandstone containing dendritic Mn02 No sample available Yellow impure sandstone bands, also some yellow grey banded chalcedonic silica Pale pink & white crystalline limestone. Yellow sandstone & yellow-grey chalcedonic silica

Sandy clay Shale

Sand Shale & sandstone Red shale

Clay Siltstone

Clay & siltstone Red siltstone Grey siltstone

No water struck

No water struck

2.5 L/s from 44m unpotable

No water struck

Brown clay & mud- No water stone siltstone struck Brown clay, siltstone, mudstone & limestone Grey siltstone & clay Grey siltstone & limestone Grey siltstone Grey siltstone & limestone

Brown clay & gravel Brown clay, gravel from mudstone

0.6 L/s from 23m

Clay, gravel, mudstone & limestone Brown siltstone & mud-stone Brown siltstone & limestone


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REG'D NO

TOTAL DEPTH(m)

9325 cont'd

21503 80.0

21504 27.0

21505 54.0

21506 43.0

21507 49.0

2148l 49.0

INTERVAL (m)

20.0 - 23.0 23.0 - 26.0

26.0 - 27.0 27.0 - 28.0 28.0 - 3l.O

3l.O - 3l.5

0.0 - 3.0 3.0 - 9.0 9.0 - 30.0

30.0 - 57.0

57.0 - 80.0

0.0 - 3.0 3.0 - 27.0

0.0 - 3.0

3.0 - 54.0

0.0 - 6.0 6.0 - 30.0

30.0 - 43.0

0.0 - 12.0

12.0 - 18.0

18.0 - 49.0

0.0 - 36.0 36.0 - 43.0

43.0 - 49.0


CCMJJENTS

Grey siltstone & mudstone Grey & brown siltstone & limestone Grey & brown siltstone Mudstone & limestone Grey & brown siltstone & muds tone Brown siltstone

Clay Gravelly clay Grey/greenish silicif ied fine sandstone

l.5 L/s from 76m

Pink silicified sandstone

fine

Black silicified brown silicified

Clay Grey silicified fine to medium sandstone, minor green micaceous siltstone

siltstone, sandstone

No water struck Hole abandoned Drill bit broke off

Clay, sand & chert 1.3 L/s chips from 24m Dark grey massive chert

Clay 0.8 L/s Sandy clay from 24m Weathered intermediate volcanic - andesite

Gravelly clay, siltstone sandstone & limestone Yellow sandstone & pink siltstone/shale Dark grey limestone

Clay & gravel Broken basalt & sandy clay Gravelly quartz

No water struck

Production bore

15 L/s


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2. Test Pumping

Bore 21481 was the only bore comprehensively test pumped. This

entailed a 24 hour constant

1982 at a rate of 33 L/s.

discharge test carried out on 2 July

At 1400 minutes the bore forked and

maintained a constant discharge of 30 L/s until completion (1440

minutes). One observation bore (6035, 55m to the east) was

simultaneously monitored. No residual readings were taken.

On 5 July 1982 a step drawdown test consisting of three rates each

of 100 minutes duration was performed on 21481. The rates were 27,

30 and 33 L/s.

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 51 of 70.

,, -· cc • )> I\) -f.\I -

s

6

I/)

~ 7 ~ ., E

z ~ 0 CJ ~ ~ 8 0

9

x

x

x

10 1

PUMPED BORE 21481

DISCHARGE 33l./s

DATE 2/7/82

x

X Xx x

x v ---

10

x x x xx x

x x

"x x x x

x x x

x xx

'X x x ~-PUMPING ON FORK

AT 30 Lis 100 1000 10000

TIME (minutes)

CONSTANT DISCHARGE TEST 21481

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 52 of 70.

,, -· (Q • )> I\) -CT --

z 3 0 0 3 <( a: 0

10

1.0

0. 1

0,0 1

PUMPED BORE 21481

OBSERVATION BORE 6035

DISCllARGE 331./s DATE 2/7 /82

10

;<xx xx '

)(

x

x

--

x

'I':

100 1000 10000 TIME (minutes!

CONST ANT DISCHARGE TEST

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 53 of 70.

,, -· (Q • )> I\) -0 -

z: s 0 0 s

5

6

"/

~ 8 0

9

10

x

x

1

PUMPED BORE 21481

DATE 517/82

x-x-x---x-x I'~ A J< --,; ,.

·-

10

Q - 27 L/s ,. , ,.

> Q - 30 L/s

~

x x

x x ~ ~

Q - 33 L/s

\

' 100

TIME (minutes) 1000 10000

STEP ORA WDOWN TEST 21481


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APPENDIX B

BORE CONSTRUCTION


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Bore Construction

Details of the construction of the bores drilled in the Ngukurr

area are given in Table Bl.

Three production bores were drilled in two separate investigations

(two in the 1967 investigation and one in the 1982 investigation).

These three bores are within lOOm of one another, approximately

3.5km north-northwest of Ngukurr, and have all been constructed in

the Kookaburra Creek Formation at the contact of the Yalwarra

Volcanic Member with the underlying sediments.

Investigation drilling indicates that this is the only area that

yields potable water in the immediate vicinity.


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BORE RN

2735 2736 2737 2738 2739 2740 2741 2742 2743 4098

4099 4100 4219 5955

6035

7868 7869 7870

9323 9324 9325 21503 21504 21505 21506 21507 21481

TABLE B1

COMPLETION DATE

23/09/61 25/09/61 28/09/61 29/09/61 02/10/61 03/10/61 04/10/61 05/10/61 06/10/61 10/10/63

14/10/63 17/10/63 27 /09/63 16/11/67

20/11/67

11/06/72 28/05/72 05/06/72

28/09/78 05/10/78 11/10/78 12/06/82 13/06/82 14/06/82 14/06/82 16/06/82 15/06/82

BORE CONSTRUCTION DETAILS

DEPTH DRILLED (m)

17.4 3.8

31.7 10.2 12. 8 10.6 16.2 11.7 21.6 85.3

38.1 19.4 43. 9 57.9

50.6

106.7 121. 9

48.8

15.0 35.0 31.5 80.0 27.0 54.0 43.0 43.0 49.0

CASING DTAILS

STATUS

None installed " " " " " " " "

0-5.0m 140mm casing & 140mm shoe Casing retrieved

" None installed 0-51.6m 140mm casing Production 140mm casing shoe Bore 0-24. Sm 140mm ID Production casing Bore 24.5-37.6m 140mm ID perforated 0-29.4m 115mm ID liner 29.4-37.6m 115mm ID perforated liner 0-22.9m 203mm casing None installed 0-18.3m 203mm casing 0-44.Sm 152mm casing None installed

" "

0-2m 203mm collar None installed 0-2m 203mm collar None installed

" 0-36m 2 03mm ID Production steel casing Bore 36-49m 203mm ID perforated steel casing


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APPENDIX C

BORE COMPLETION REPORTS


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BORE COMPLETION REPORT

1. Introduction

A number of groundwater investigations have been undertaken at Ngukurr.

These have resulted in three production bores, 5955, 6035 (drilled in

1967) and 21481 (drilled in 1982).

2. Geology

The production bores have been constructed in the Kookaburra Creek

Formation at the contact of the Yalwarra Volcanic Member and the

underlying sediments.

12 L/s.

3. Water Quality

Individual bores are capable of yielding up to

The water from the groundwater source has high hardness (450-550 mg/L)

and high NaCl (300-500 mg/L) levels. These are considered marginal in

terms of drinking water standards.

The hardness is due to the limestones/dolomites of the Kookaburra Creek

Formation~

4. Barefield Performance

Three main factors contribute to drawdown in all production bores :

( i)

(ii)

(iii)

Well lossess occurring in the first ten minutes of pu.~ping.

Aquifer losses, and

Seasonal water level decline of 3m a year (assumed).

The borefield to date has peformed at a rate equating to 14 L/s.

However, the sustainable yield of the aquifer has not yet been assessed

and this work should be undertaken before the yield from the boref ield

is increased.


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WATER RESOURCES DIVISION

TEST REPORT - BORE RN. 59 5 5

Bore Location: NGUKURR. Map: URAPUNGA 1:100,000 Sheet: 5868. Grid Reference: 696 - 740.

Client Purpose

AES. COMMUNITY.

RECOMMENDATION. Pumping Rate: 12 L/s. Pump Setting: 48.7 m. For alternative pumping rates or settings contact Water Resources. General recommendations are on the reverse side. Sasco House, In all correspondence please quote bore RN 5955. Darwin NT.

************************** .. ""**-.':******** .. ':** .. '::*********1:*-.':*-.':-.'::**~':**"i<**-:~*i<********i:*

BORE DATA. Finished depth: 57.9 m. Completion Date: 16.11.67. Standing Water Level: 30.4 m on 9. 10.68. Construction details:

Test Date: Test Rate:

Test Duration:

Interva 1. Description.

0 -51. 8 -

51. 8 m 57.9 m

140 mm ID 140 mm

steel casing. open hole.

Notes: 1. Top of casing as constructed was 0.3 m above ground. 2. All depths are measured from natural ground level.

9.10.68. 12 L/ s.

100 mins.

3. Test rates are not indicative of safe long term pumping rates.

WARNING: MINIMUM INTERNAL BORE DIAMETER IS 140 mm. MINIMUM INTERNAL BORE DIA..'lETER TO RECOMMENDED PUMP SETTING IS 140 mm.

COMMENTS.

1. The above recommendations are based on previous testing and use and assume hydrological conditions remain constant.

2. Provision to monitor water levels and obtain water samples should be incorporated in the headworks.

3. The pumping rate is for bore pumping on its own.

*********************************~'(i<*****1«•'::*******"'-**'k't.:."/.:."'l.:.~'(·k*~':*~'::***"k****'l~*1~**

WATER ANALYSIS. No. 82/1353.

Prepared by: P Tyson. 20/7/93.


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RECOMMENDATIONS FOR FINISHING, OPERATING AND PROTECTING GROUNDWATER BORES.

Attention to the following points will ensure a long and safe life for the bore supply and help prevent pollution of the groundwater resource.

1. Construct a concrete apron around the bore head to prevent surface flow, seepage and weste from entering the bore.

2. Seal the space between the casing and pump equipment to prevent entry of vermin, dirt and pollutants.

3. Maintain pumping equipment i~ good order to prevent pollution. Prevent spillage of fuel and oil on the ground around the bore. Store fertilizer and other chemicals at least 50 m. away.

4. Keep stock away from the bore head. bore.

Discourage domestic ac~ivity at the

5. Pumping the bore at higher than recommended rates may fork the bore leading to instability or pum~ mai~~enance problems. Seek the professional advice of an hydrogeologist or groundwater engineer.

6. !f the bore is no longer requi~ed, the casing is to be removed or securely capped and the bore backfilled wi:h clayey material. A cement plug may be required in some instances.

I~ ADDITION, please ensure that ~he BORE IDENTIFICATION TAG is retained securely a~ all times. The registered bore number ia Water Resources Division's only reference to the scientific and engineering data on this bore and hence important to WE.D's further advice to bore owners.

30RE LOCATION ~.A?.


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DEPTH BORE GRAPHIC STRATA AQUIFERS (ml CONSTRUCTION LOG DESCRIPTION (WATER STRUCKl

0.3m

0 L,,;:

0 •{.f.i;:!~~ Soil and basalt \~f?-1:(;.~t

- ~R'.!*~;{. I-

-;,-. ..:-: ... -~ ":t..:-~::'.t'<.

5- •{.G.-;"1~~} I- 5 ~i,!~:r~.;,:t :;:? ... :: ... _:;::-\~}},~I!~ Basalt I-- ·~YJ~~ {~"'}~@

10 - ~.t~7C* 1-10 G;'>'l'-{if{. ~fi~k.s; " - "'' - =~ Brown shale I-

15 - ~~ '-15 =~ =~ Shale with hard basalt ledges =~ - :;;:

I-- -=-----=-

20- "" No returns 1-20 :z u:i .. '''.' «'. <.''.' - (.) .. ' .. ' I-

... '' .. -' •••• <.'

LU ..... '

25- LU ..... ' 1-25 ,_ ... '.' u:i .. ' ...

. . . ''. - Cl '. '.' I-

.. ' ... '

E ... ' .. ' ... ' .. ' LL SWL 30.4m 30- E '. ' .. ' Clay and loose basalt 1-30

0 .. '' '.' 9/10/68 :;!: .. '''.' .. '''.' - • <., •• ' I-•• '< ••• . . . . . . . . '.' .. '

35- .. '' ... I- 35 • . <'.'' ..... ' .. ' .. '

- .. ''.' I-... ' .. • • • < •• ' .. ' .. '

40- .. ''.'' I- 40 ... '' .. -fe::::t~.:r::

, ... - ...... -(.:! ... - w -tG~t'l,::~ I-

0 -~!efE'.'.~ :c -:Yd~f1:7J 45-

u:i Loose basalt -45 '0-{:""-{'"'

"" -i ::::t~.r~ ;.-_~ ... -{:--{•

:z -N:::t'1~'J' - u:i -7-?!e~tx -

«'. .!~-(;;{~

(.) .i.-j;':.i, ... 50-

-M' .. t~:M -50 -~"'r~J'.~

I -~}t;;_t.;, - -?frtft~ ... -

-~il~~ Firm to hard basalt 55- -~1~"iZ """ 12.5 L/s -55 ,.._-{;"-{'"

-ffc:LVt_...j\1 ~""-:1--.".'" -"J<';~ci...tr

- ~{~:{~ -

COMPOSITE LOG OF BORE 5955

Fig. C1{a)

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 62 of 70.

,, (Q • () ...... -CT --

0

2

4

6

(/)

~ 8 ~

" E

z ;:;: 10

0 a 5 <( 12 Cl'. 0

14

16

-

DRAWDOWN VITHOUT

--~--"-----·---------------

AVAILABLE Di AWDOWN 20.4m !PUMP ET AT ASS JMED: SEASONAL DRAWD lWN 0.3m 1 MONTH (DRY SEASON ( NL YI

SWL 28.3m 100 1000 10000

TIME (minutes)

' I I I I I I I I

' I I I

SEASONJ.\L...C~G I

-INE-Pl:JM/O/ • ~ I\ I '12 Lis ----- -. , __ I -- I ....

'· DRAWCJOWN ',AT 1_f L/s +

'SE~SONAL ',D CLINE ,,

..,-. -----I I I I

I I I I

I I I I

I I I I

48.7ml I I I I I

100000 1 YEAR 1000000

PUMPING CURVE RN 5955


Viewed at 15:07:57 on 29/07/2010 of 70.

WATER RESOURCES DIVISION

TEST REPORT - BORE RN. 6 0 3 5

Bore Location~ NGUKURR. Map: URAPUNGA 1:100,000 Sheet: 5868. Grid Reference: 696 - 740.

Client. Purpose

AES. COMMUNITY.

*****************************};:*************t.:;~~**~"*'f.::*i'-J.::*i:**1<*-1<'k*i:****1:*-i:i.:;*'f.::*'i.:;~'(**

RECOMMENDATION. Pumping Ra~e: 4 L/s, Pump Setting: 36. 6 m. For alternative pumping rates or settings contact General recommendations are on the reverse side. In all correspondence please quote bore RN 6035.

Water Resources. Sasco House, Darwin NT.

BORE DATA. Finished depth: 50.6 m Completion Date: Standing Water Level: 29 m on 16.9.68. Construction details:

Interval.

0 - 24.5 m 140 mm

13.12.67. Test Date: Test Rate:

Test Duration:

Description.

ID steel casing.

16.9.68. 9. 4 L/ s.

7 hrs.

24. 5 3 7. 6 m 140 mm ID perforated steel casing. 0 - 29.4 m 115 mm ID steel liner.

29.4 - 37.6 m 115 mm ID perforated liner. 37.6 45.7 m 140 mm open hole. 45.7 50.6 m 120 mm open hole.

Notes: 1. Top of casing as constructed was 0.4 m above ground. 2. All depths are measured from natural ground level. 3. Test rates are not indicative of safe long term pumping rates.

WAR..~ING: MINIMUM INTERNAL BORE DIAMETER IS 115 mm. MINIMUM INTERNAL BORE DIAMETER TO RECOMMENDED PUMP SETTING IS 115 mm.

COMMENTS.

1. The above recommendations assume hydrological conditions remain constant.

2. Bore has been relined with a 115 mm steel liner.

3. Note pump setting is inside the perforated liner.

4. The bore is currently equipped with a pump with a capacity of 4 L/s.

5. The maximum pumping rate is based on the limitation of the liner~s internal diameter.

6. Recommended rate is for bore pumping on its own.

************************************)"'l::*******)':*****}':*****)':**~'::'!::*****~':**-l<l~~':**i::

WATER ANALYSIS. No. 82/1344.

Prepared by: P Tyson. 20.7.93.


Viewed at 15:07:57 on 29/07/2010 of 70.

RECOMMENDATIONS FOR FINISHING, OPERATING AND ?ROTECT!NG GROUNDWATER 30RES.

At~entior. t:o t.~e :cllowing Pcints will ensure a lo~g and sa:e :i:e SL!;"pl31 .a:ld. hel~ pre,le::t: :;iol~ucion. c:: thf: g:r::n.z.n.C..-;.;a.te!" :-escurce.

fer t:he be:- e

" .

.'.:..

Cccst:=~c= a ==~c=e:el a;ron aroucd :~e bore hea~ t:: see?ag~ an~ ~as~~ ~=km e:::.~ering t:~e bc=e.

a::C. equi:;::ne:::.:

:n gooC crier :o prevent: s~illa&e cf :~el a::d oil or. the grounC arcu::d t:he bore. and other che=~ca:s a: leas: 50 m. awey,

Kee? st:cck away ==o~ t:~e bcre he~d. :icre.

su?."face.

e ,..i""-·· .. ..... -~~

?t~::i.pi.:ig t:!:e ~or~ .a: hig:her :.=ia:i re~cc.menC.ed :-at:es :nay f:::':<. t:ie. bar~

of

:eadi~g t:= i~st:~b::::y er pu~p main:~nance prco~e~s. Seek :~e ;r=::ss~o~a: aCvice of an ~yd=ogeclogist: er gro~nd~a~~r engineer.

::i. !t :::e ~c!"2 is ::c :o:-:.g~r :-equ.i::-ed, :.!"~e c.asi::g :.s !"" .... be :-emcved or sec"..:.:-e:.y ca~;ed ~cc =~~ =c~e backf~lled w~~~ clayey m~:e=ia~. A ce~e~c ~l~g ~ay Ce :e!:.uirec. .:..n sc~e i~s"Ca::.ces.

' . . . . o~ c~~s :c:e ano ne~ce

"·;-· ;-:-~

: .... _;?-.:.:l~~- ~~-:! '


Viewed at 15:07:57 on 29/07/2010 of 70.

DEPTH BORE GRAPHIC STRATA AQUIFERS (ml CONSTRUCTION LOG DESCRIPTION (WATER STRUCK)

0.4m

0 ~

0 ...... Topsoil, clay and weathered basalt . . . . . . - e'~ml.!'!.. ~

elW~{.

5- e~$77~~ f- 5

c:> e~~.;...;.rer, :z i§!..!.~<tr,~ Basalt, sol! red minor sandstone <Z>

_..:-~.._.::,,._..:-- t.!~~f.~£~ -<: er274~£ (_)

10 - --' er2~~{: -10 UJ tr2~~ UJ I- e~-;J;<tr,

- "' a: -- , .. --- f-LU Siltstone and clay 0 z _, -~ 15 - E ~- f-15

"" =--E z =-- Sandy shale and sandstone red =--0 <: ~~~

- .... _, E -=::; -l co c:> 0

:(,~&!Z~ :z ~!ill~; 20 - (/.; - 20 <: E ~!i?""J~} (_) E Z!eiJY,~ - "' ---~11..f.''r-:'\ -_, - l,~ct~:::. UJ :r!t't]Z; LU ~ ~

1-0 ~f<..!.----1 25- II II l'..'-~ -25 <r.l LU ~a:~? I-

O<: II II w--{., ... - Basalt, weathered siltstone and sandstone -a: ..!t!~fo::.' - EO II II rti,~7?,} -Eu... 1&f.7J} '1- SWL 29.0m oCC II I I I I I II :<l~!..!.>-:1 16/9/68 30- .... L .::.:...:;,:~..:'..::- -30

II I I I I I II ~-'t':''•' .::,.. __ {~..:'..:: ~!---,.,_\

- II I I I I I II .. -,,..?.r..:'..:: -::h:~~'N::.'

II I I I 11 II ~}l~70} 35 - II 11 11 II

0;<z;rJ:-jZ;1 - 35 ---"t{{.'"-.._I~-/.,:>

• N.

I I 11 I ;;'~'<:-7"/!:' Fresh basalt -- ...... '' .... vvv 12.5 L/s . . . ' ..

cc ...... 40- UJ

...... Chalcedonic silica and sandstone - 40 ...... zo ..... '

:J~ ...... . . . . . . . . . . . ' - o< ...... --a: ......

EO ...... Eii:

...... 45- ...... -45 . . . . . . .,., UJ ...... Crystalline limestone, yellow sandstone and ::= "- ...... . . . . . .

- ...... chalcedonic silica -...... . . . . . . . . . . . . . . . . . . 50 -

. . . . . -50

- -

55- -55

- -

COMPOSITE LOG OF BORE 6035 I Fig. C2(a)

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 66 of 70.

.,, -· (Q • () l\) -er -

0

2

4

6

"' ~ 8 -" E

z ;;: 10

0 0 5 <( 12 0: 0

14

16

18

_______ .. ______

' DRAWDOWN Vi ITHOUT

I SEASONAL DECL NE PUMPING I -- AT 4 Lis ------- I ...... I ...

'-..,DRAWD{:JWN ' AT 4 1 L/s +

',,,SE8SONAL ',DIECLINE ,,

~ I ' I I I I I I

,_ ______ 9"1!!!- 8._V.AIL(l~ ].!,; ....QElA ~QQ_WN _ le.LJ.MP _ ~ ';I _llJ_3_6Jl.roL ______ I --- - - - - - - _,_ - --

I ~·-·

I ASS !MED: SEASONAL DRAWD lWN I 0.3m 'MONTH IDRY SEASON C NL Yl I

SWL 27.2m I

' I I I I ' I I I I

----------·. - --------' I I I I

--·~ - I I I I I

100 1000 10000 100000 1 YEAR 1000000

TIME !minutes)



Viewed at 15:07:57 on 29/07/2010 of 70.

POWER 'I\ --AND-~ WATER RESOURCES DIVISION

WATER~~ AUTHORITY ~

TEST REPORT- BORE RN. 21481

Bore Location: NGUKURR. Map: URAPUNGA 1:100,000 Sheet: 5868. Grid Reference: 696 - 740.

Client Purpose

RECOHMENDATION. Pumping Rate: 11 L/s. Pump Setting: For alternative pumping rates or settings contact General recommendations are on the reverse side. In all correspondence please quote bore RN 21481.

BORE DATA.

AES. COHMUNITY.

36 m. Water Resources. Sasco House, Darwin NT.

Test Date: 2.7.82. Test Rate: 30 L/s.

Finished depth: 49 m. Completion Date: 15.6.82. Standing Water Level: 28.3 m on 2.7.82. Construction details: Test Duration: 24 hrs.

Interval.

0 -36

36 m 49 m

Description.

203 mm ID 203 mm ID

steel casing. perforated steel casing.

Notes: 1. Top of casing as constructed was 0.8 m above ground. 2. All depths are measured from natural ground level. 3. Test rates are not indicative of safe long term pumping rates.

WARNING: MINIMUM INTERNAL BORE DIAMETER IS 203 mm. MINIMUM INTERNAL BORE DIAMETER TO RECOM!1ENDED PUMP SETTING IS 203 mm.

COMMENTS.

1. The above recommendations are based on previous testing and pumping and assume hydrological conditions remain constant.

2. Provision to monitor water levels and obtain water samples should be incorporated in the bore headworks.

3. The pumping rate of 11 L/s is for bore pumping on its own.

4. Finished depth was 49 m but measured depth on 2.7.82 was 47 m.

WATER ANALYSIS. No. 90/91/0329.

Prepared by: R Setchell. 20.7.93.

Checked by: P Tyson. 20.7.93.


Viewed at 15:07:57 on 29/07/2010 of 70.

RECOMMENDATIONS FOR FINISRING, OPERATING AND PROTECTING GROUNDWATER BORES.

Attention to the following points will ensure a long and safe life for the bore supply and help prevent pollution of the groundwater resource.

1. Construct a concrete apron around the bore head to prevent surface flow, seepage and waste from en~ering the bore.

2. Seal the space between the casing and pump equipment to prevent entry of ver~in, dirt and pollutants.

3. Maintain pumping equipment in good order to prevent pollution. P~event

spillage of fuel and oil on the ground around the bore. Store fertili2er and other chemicals at least 50 m. away.

4, ~eep stock away from the bore head. Discourage domestic activity at the bore.

5. Pumping the bore at higher than recommended rates may leading to instabili~y or pump maintenance problems. advice of an hydrogeologist or groundwater engineer.

fork the bore Seek the professional

6, If the bore is no longer re~uired, the casing is to be removed or securely capped and the bore backfilled with clayey material. A cement plug ~ay be required in some instances.

!~ ADDITION, please ensure that the BORE IDENTIFICATION TAG is retained securely at all times. The =egistered bore number is Water Resources Division's only reference to the scientific and engineering data on this bore and hence important to WRD's further advice to bore owners.

BORE LOCATION MAP.


Viewed at 15:07:57 on 29/07/2010 of 70.

DEPTH BORE GRAPHIC STRATA AQUIFERS (ml CONSTRUCTION LOG DESCRIPTION (WATER STRUCKJ

0.8m

0 ~

0 ...... '' ' ... '' .... '' ' ... - -'. ' ... '.' .. ' .. ' ...

5- '.'' .. '' ' ... -s '. ' ... . . '' .. ... ' .. - -.. '' .. ' .. ' .. . ' ....

10 - '.' ... -10 . . . ' .. ' ... '' ' ..... .. . ... ' .. - -'' .... . . . . . .

0 '' ....

15 - :z ...... -15 .... '.

"' ...... <C .... '.

Glay and 9ravel - 0 ...... -.. '''. __, ...... LU '.'.'.

20 - w '.'''. -20 I- . ' .. '. "' ...... . ' ....

- a .. ' ... -... ''. E ... '' . . . . . '.

25 - E ...... -25 ""' ...... = "' ...... ''' .. '

- ... ' .. SWL 28.3m -, ..... _y__

0 ...... 2/7/82 :z . ' ....

30- (f) '' .... -30 . . . . . .

<C ...... 0 ... ' ..

- __, . ''.'. -LU . ''.'. LU

...... . ' .... 35- l-o . ' .. '. -35 '-"w ......

1111111 ol- :,j.71,~~·J -<C - 11111111 a: ~~:Yd'i!~ -

EO

11111111 EU.. r~74y~~ Broken basalt and sandy clay .,., a: ~{.\ .. ~I.,;.-~{. 40-

11111111 =w ~~~c~ 'IVY 7.5 L/s - 40 L]a_ ~{.l~:~~ ;~~~ -~

11111111 i}J.f(rfirJ: - ••• -

11111111 ••••••• ••• 11111111 • • • • 45- ••• Gravelly quartz

-45 •••• 11111111 • ••• ••• ••• - 111111 I • • • • -........

50- - 50

- -

55- -55

- -

COMPOSITE LOG OF BORE 21481

Fig. C3(a) -- __ .....--

Technical R

eport WR

D92041

View

ed at 15:07:57 on 29/07/2010P

age 70 of 70.

"Tl -· (Q •

() (..) -C" -

0

2

4

6

"' ~ 8 -" E

z $ 10

0 0 $ <i: 12 a: 0

14

16

18

,_ _____________

-

2~0

' I I I I I I

DRAWDOWN VITHOUT SEASONAL DEC I

/NE PUMPING AT 111 L/s ----- :'!L--------- I

-- ... DRAwoqwN -',AT 11 1 L/s +

'· SEASONAL ' DEjCLINE

'\ ,, ... 1'

9m AVA/LA LE DRAWDOWN !PUMP ET AT 36m) I ........ __. .. ___________

~- --- -- ____ .. ___ ..... ___ .. _ .. _______ - - --- -------1- - - -

I I

ASS IMED: SEASONAL DRAWD WN I

0 3m/MONTH !DRY SEASO ) I I

SWL 27m I ' I I I I

I I I I

-I I I I

-~-

' I I I I

100 1000 10000 100000 1 YEAR 1000000

TIME !minutes)


ngukurr water supply evaluation · technical report wrd92041 viewed at 15:07:57 on 29/07/2010 page...

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