ti-tree monitoring bore construction programme. bore ...€¦ · monitoring bores was insufficient...

Ti-Tree Monitoring Bore Construction Programme.

Bore Completion Report

Bore RN 16679 to 16686.

Report No.: 66/1995A

Digital No.: WRA95066

ISBN 1 920772 68 5

PW SNEPP

Land and Water Division

Alice Springs July 2007

WRA95066

SYNOPSIS

Re-assessment of the Ti-Tree Basin in 1994/95 identified areas where the density of

monitoring bores was insufficient for meaningful contouring of water levels and

hence inadequate for calibrating a computer model. Management of the basin’s water

resources requires consideration of processes at the 1 km scale or below. In the areas

of concern separations between monitoring bores were 15 to 30 km. To improve the

monitoring grid eight monitoring/observation bores (RN 16679 -16686) were drilled.

Three bores, RN16680, RN16684 and RN16686, were constructed as monitoring

bores using 100mm PVC while the remaining five bores were constructed using

50mm PVC casing.

Well-yields varied between 0.1 and 10+L/s and conductivities varied from 979 to

5400 μS/cm.

KEYWORDS

SUBJECT Monitoring Bores, Ti-Tree

GEOLOGY Ti-Tree Basin, Cainozoic sediments, Arunta Block

LOCATION Ti-Tree Region

1

CONTENTS

1. INTRODUCTION 4

2. GEOLOGY 4

2.1 Scope of Work. 5

2.2 Bore site selection 5

2.3 Drilling & Construction Schedule. 6

2.4 Geological logging. 8

2.5 Geophysical logging. 10

3. CONCLUSIONS 12

4. REFERENCES 13

TABLES

1. TABLE 1 DRILLING PROGRAMME SUMMARY 8 2. TABLE 2 DRILLING PROGRAMME, HYDROGEOLOGICAL SUMMARY 9

2

FIGURES

1. FIGURE 1 TI-TREE LOCATION MAP 5 2. FIGURE 2 GEOLOGICAL MAP 6 3. FIGURE 3 BORE LOCATIONS 7 4. FIGURE 4 GAMMA LOG OF RN 16679 17 5. FIGURE 5 GAMMA LOG FOR RN 16680 19 6. FIGURE 6 GAMMA LOG OF RN 16681 21 7. FIGURE 7 GAMMA LOG FOR RN 16683 25 8. FIGURE 8 GAMMA LOG FOR RN 16684 28 9. FIGURE 9 GAMMA LOG FOR RN 16685 31 10. 1. FIGURE 10 GAMMA LOG FOR RN 16686 33

APPENDICES

APPENDIX 1, DRILLING SCHEDULE

APPENDIX 2, GEOLOGICAL LOGS RN 16679 -16686.

3

ABBREVIATIONS

AMG - Australian Map Grid

ASL - above sea level

BGL - below ground level

°C - degree Celsius

EC - Electrical Conductivity

EOH - End of Hole

ID - Internal Diameter

km - kilometre

L/s - litre per second

m - metre

mg/L - milligrams per litre

OD - outside diameter

RN - registered number

SWL - standing water level

TD - total depth

TDS - total dissolved solids (in mg/L)

μS/cm - micro Siemens per centimetre

WRB - Water Resources Branch

Distribution

Water Resources Branch Library, Alice Springs 3

Water Resources Division Library, Darwin 1

PAWA Library, Darwin 1

Principal Water Engineer, Darwin 1

Project Manager, Alice Springs 1

Author 1

4

1. INTRODUCTION

The re-assessment of water resources contained in the Ti-Tree Basin undertaken in

1994/95 (report15/1994A) identified areas within the basin where the density of

monitoring bores was insufficient for preparation of meaningful contours of water

levels and consequently also inadequate for calibrating a computer model of the

groundwater resource. Management of the water resources of the basin requires

consideration of processes at the 1km scale or below. In the areas of concern

separations between monitoring bores were 15 to 30 km. To improve the data

density, a programme was proposed to drill 8 additional monitoring bores.

Ti-Tree is located approximately 200 km to the north of Alice Springs on the Stuart

Highway (Figure1). The area is centred approximately at AMG co-ordinates

350000E 7530000N and is covered by the Napperby (SF 53-9) and Alcoota (SF 53-

10) 1:250000 geological maps.

Site selection within area was undertaken by hydrologist Gunther Seidel with

geological supervision of the field programme undertaken by geologist Peter Snepp.

2. GEOLOGY

The Ti-Tree Basin contains a sequence of terrestrial sediments deposited in a number

of depositional regimes and cycles during the Cainozoic. These cycles appear to be

separated by periods of weathering and sometimes erosion.

These sediments overlie much older rocks (Fig. 2) which have a complex

metamorphic and tectonic history, culminating in the development and evolution of

the basin. Detailed descriptions of the geology of the basin are presented elsewhere

e.g. McDonald (1988), Shaw and Warren (1975), Senior et al (1994).

5

Figure 1 Ti-Tree Location Map

2.1 Scope of Work.

The main objective of the programme was to provide additional water level

monitoring wells in the main aquifer, preferably penetrating it completely. All bores

were logged geologically and geophysically, water samples were taken during

drilling. Three bores were completed with 100 mm PVC casing to allow water

sampling in the future. The remaining monitoring bores were completed with 50 mm

ID PVC. Drilling was carried out by rotary rig using air and foam or mud as required.

2.2 Bore site selection

Funds were available to drill 8 of the 12 sites originally proposed (Fig. 3).

Sacred site clearance was obtained from the Central Land Council and local land

owners and also involved inspection of the sacred sites register at the offices of the

Aboriginal Areas Protection Authority. Only minor clearing of vegetation was

6

required on the sites and rehabilitation was undertaken on completion of bores.

2.3 Drilling & Construction Schedule.

Drilling was undertaken by Water Resources Branch (WRB) drilling crew using Rig

16 between 8th and 24th August 1995.

Drilling methods are summarised in Appendix 1.

Drilling details in relation to each bore are summarised in

Table 1.

Figure 2 Geological map

7

!

!!

!

!

!

!!

!

!

!

!!!!

!!

!

!

!

!

!

!

!

!!

!

!!

!

!

!

! !

!

!

!

!

!!

!

! !

!

!

!!

! !

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!!!

!

!

!!

!

!

!

!

! !!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!!! !

!

!

!

!

!

!!

!

!

!

!!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!!!

16686

16685

1668416683

16682 16681 16680 16679

LegendBores in this investigation

! Other bores

Extent of Ti_Tree basin

highways

Major roads

tracks

railway_m94

Cadastral boundaries

Figure 3 Bore Locations

8

Table 1 Drilling Programme Summary

Site Bore AMG TD m Casing Basement No. RN Easting Northin

g

Depth

m

Diam

mm

depth

(m)

geology (1)_

1 16679 358402 7535114 18.2 15.5 50 N/I 2 16680 351323 7535026 77.5 77.5 100 62.5 granite 3 16681 344190 7535044 65.5 52.6 50 N/I 4 16682 326818 7534993 59.5 53.9 100 N/I 5 16683 333321 7536748 71.5 66.9 50 N/I 6 Not drilled due to access difficulty. 7 16685 330692 7517296 107.7 107.3 50 87? regolith 8 16686 318476 7521278 65.6 64.0 50 54 gneissic 9 16684 319615 7534891 106.6 106.2 100 99 weathered

basement

Total metres 572.1 543.6

(1) N/I is Not Intersected

Hydrogeological details of airlift yield, pH and conductivity are summarised in Table

2.

2.4 Geological logging.

Cutting samples were collected during drilling at 3m intervals and logged by a

geologist. Logs are in Appendix 1.

Hard lateritised material at depth was interpreted as a former weathering surface.

Highly weathered clay rich, usually clean white clay, material containing very angular

to crystalline very coarse to granular quartz/mineral grains, beneath it was interpreted

as a buried regolith.

9

Table 2 Drilling Programme, Hydrogeological Summary

RN Aquifer Depth Yield pH Conductivity SWL

No m l/s μS/cm m

16679 1 12.21 Seepage 6.73 2 15.36 0.1 7.41 979

16680 1 17 0.1 7.45 1620 13.03 2 26.9 2.5 7.62 1822 3 35.47 3.3 7.61 1630 4 41.47 3.8 7.74 1664 5 47.47 est. 6-7 7.69 1683 6 53.47 est. 7-8 7.58 1783 7 65.47 est. 9 7.76 1780 8 71.47 8.1 1826 9 77.47 est. 10 7.92 1792

16681 1 29 Seepage 22.34 2 35 est. 1 7.14 2800 3 41 est. 2-3 7.27 2910 4 47 3 7.51 2910 5 65 est. 5 7.73 2730

16682 1 37 Seepage 36.39 2 47 est. 1 7.62 3220 3 53 est. 2 7.67 3110 4 59 est. 4-5 7.75 3110

16683 1 25 Seepage 26.12 2 41 0.2 7.91 1540 3 43 est1 7.95 1733 4 53 1.4 5 65 3.3 7.98 2540 6 68 est. 9-10 7.75 3200

16684 1 59.5 Seepage 2 83.78 0.1 7.94 2170 3 106 0.2 7.73 1740

16685 1 78 Seepage 60.18 2 94 est. 0.3 7.43 2270 3 107 est. 0.3-.4 7.52 2140

16686 1 44 est. 2 28.65 2 50 est. 4-5 7.41 5400

Geological logs for all bore are shown in Appendix 2.

The following observations about the stratigraphy are based on research of historic

data and information derived from the current programme:-

1. The sequence is dominated by coarse to very coarse, sub angular to sub

10

rounded sand sized material, predominantly quartz with subordinate lithic grains.

2. The sands contain a high proportion of fine matrix, predominantly of silt sized

material with lesser clay sized of similar composition to clasts.

3. Granular and/or pebbly bands or gravels are common.

4. Most stratigraphic boundaries are gradational rather than sharp.

5. Examination of diamond drill core from previous programmes and geophysical

logs shows that geological variations occur on scales of 0.1 m rather than metres,

although gross stratigraphic variations are on scales of metres.

6. Lithification within the sequence is highly variable.

7. Laterite (and/or calcrete) is present at several levels, suggesting several periods of

weathering. These may correspond to "palaeo-regolith" and may be mappable

surfaces.

2.5 Geophysical logging.

Wherever possible each bore was geophysically logged before casing. Bores were

logged using Single Point Resistance (SPR)/ Spontaneous Potential (SP); Caliper; and

Gamma sondes. All logs were run from the bottom to top of the hole. SPR/SP and

Caliper logs were run at approx. 6m/min speed and Gamma logs at approx. 3m/min

to improve count rate statistics.

Copies of geophysical log print-outs and digital log data files on disk are held at WRB

in Alice Springs.

Hardware and software problems during logging prevented the acquisition of a full

suite of logs in open hole conditions in all bores. In these cases, either SPR/SP and/or

Caliper logs are not available and Gamma logs were run in the cased bore. In order to

evaluate the attenuation due to 100 mm PVC casing, bore RN16680 was logged

between GL and 66m in both open hole and through the casing. Comparison of these

logs shows consistency of log form but slightly lower response in the cased bore.

11

The following general observations relate to the geophysical logs acquired as part of

the current programme:-

1. Original log files all contain data of quality appropriate for detailed analysis.

2. Some header and other data included in the field required editing subsequently

(this is a flaw in the software as some of the data which must be entered in the

header prior to completing the log is best derived from the log to be run!).

Original field data files were preserved with duplicate (modified) files created

with an alternate file extension.

3. For presentation and analysis purposes, the choice of vertical and horizontal scales

is critical, particularly in respect to SPR/SP logs but also with gamma logs.

4. A useful scale in the current circumstances was 1:300 so that 1cm was one 3m

sample interval, allowing easy comparison of geological and geophysical logs.

5. SPR/SP logs show either two or three distinct response styles which can not be

presented appropriately at one particular horizontal scale. These response styles

are interpreted to correspond to -

a) saturated sequence below water table - relatively uniform porosity and

homogeneous fluid composition giving relatively conductive responses, with low

amplitude due to geological variations;

b) infiltrated zone between Water Table and SWL - somewhat variable

porosity and permeability resulting in variable infiltration by relatively

homogeneous fluid giving somewhat more resistive response with high amplitude

response variations due to geological variations; and

c) above the standing water level a resistive response due to lack of hole

fluid and thus lack of continuous electrical contact with the wall-rock.

6. In view of the variable SPR/SP responses noted in 5) above, it was useful to

present different sections of the bores using a range of horizontal scale

parameters. Presentation of the entire bore using one set of horizontal scale

parameters was misleading with respect to the full nature of the response recorded

in the log.

7. A number of software quirks were identified which could be rectified. A

12

number have now been addressed by the supplier, however the software still is

best described as adequate only.

8. Due to difficulties grounding the surface electrode, SPR/SP responses display

some drift. This drift gradient can be removed to allow analysis of geologically

related variations, but time constraints have not allowed this to be done.

9. Features can be correlated between electrical and gamma logs in individual bores,

but few features can be correlated between bores.

3. CONCLUSIONS

The sequence shows few markers, but laterites and calcretes may be mappable.

It has not been possible to correlate geophysical logs between bores.

13

4. REFERENCES

1. McDonald P., 1988 Groundwater Studies Ti-Tree Basin 1984-1988. Water

Resources Branch, Power and Water Authority, Alice Springs NT (Report 1/90)

2. Seidel G., 1995 Water Resources Branch, Power and Water Authority, Alice

Springs NT(Report 15/1995A)

3. Senior B.R., Truswell E.M, Idnurm M., Cainozoic Sedimentary Basins in the

Alice Springs Shaw R.D., and Warren R.G. 1994 Region: Records of

Drilling and Reconnaissance Geology.

4. Shaw, R.D. and Warren R. G., 1975 1:250000 Geological Series -

Explanatory Notes. Alcoota SF53-10, NT. Bureau of Mineral Resources,

Canberra.

14

APPENDIX 1

DRILLING SCHEDULE

Bores were drilled as follows:

• prepare site

• site and level rig

• drill to approx 5.5m (ñ 0.5m) using 245mm roller bit

• insert 190.5mm steel surface casing and cement in allowing approx. 0.5m above

GL.

• drilled on circulating air (ñ water/foam injection) with 140mm down hole hammer

(RN16679) or 171.4mm blade bit (other bores), either to EOH (monitoring Bore) -

[EOH determined by either basement lithologies identified in returned cuttings;

maximum programmed depth reached -approx 100m; or caving precluded return

to bottom of hole on rod change;] or depth where caving precluded further

penetration by this drilling method (Sampling Bore).

• tripped drill string out of hole.

• geophysically logged open hole for Single Point Resistance (SPR)/ Spontaneous

Potential (SP); Caliper; and Gamma where possible.

• then either

a) completed construction of bore with appropriate sized PVC casing (50mm

monitoring, 100mm sampling); or

b) changed drilling fluid to bipolymer mud and continued drilling to EOH

(predetermined maximum depth was reached; lack of fluid circulation; or

basement lithologies identified in cuttings),then

• completed construction of bore with 100mm diam. PVC casing.

airlifted bore to flush bipolymer mud- cake from bore and develop aquifer.

15

APPENDIX 2

GEOLOGICAL LOGS RN16679 - 16686

16

WRB Borehole Geology Log: Project: Ti-Tree Monitoring Bore

Bore: RN 16679 Logged by: P Snepp Date: 11/8/95

Page 1 of 1 Location: E 358402 N 7535114

Method: GPS RL 550m asl

Depth

Water Info Geological

Description:

From To

0 3 Red clayey sand/soil & pebbly medium/coarse sandstone

(lithified with minor Fe staining.)

3 6 Fine/medium buff/orange sandstone (lithified) with silty matrix,

minor pebbles (rounded) & minor white calcrete.

6 9 Largely white/buff clay with rare sand. moderately well lithified.

9 12 Light brown/golden clay with very minor sand.

12 15 as 9 - 12m.

15 18 Wet Light brown/golden clay passing into coarse

sand/granules/pebbles of sub-rounded to sub-angular quartz.

Conductivity 979μS/cm

pH 7.41

Comments: Hole caved @ ~15.36m in gravel unable to drill on with air.

Constructed with 50 mm PVC as monitoring bore. Geophysically logged with

Gamma sonde only through PVC casing.

17

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m

Figure 4 Gamma log of RN 16679

18


Bore: RN 16680 Logged by: P Snepp Date:


Method: GPS

Depth Water Geological Description: From To Info

0 3 Ochre - red medium to fine grained quartz sand & silt, aeolian with very minor golden mica & Fe coated quartz grains.

3 6 Buff coarse to very coarse granular sandstone, lithified sub-angular & crystalline quartz, Mn coated, lateritised in parts with substantial clay & silt matrix.

6 9 Buff coarse to very coarse sandstone much as 3 - 6m. Lithified granular ~40% matrix. Dark red more sandy with depth. quartz sand. finer zone ~7m (hard zone~8.5m - less porous looking chips)

9 12 Buff medium to coarse quartz sandstone, minor silicreted sandstone ~11m, moderately lithified 12 15 damp 13m Khaki/golden silty sand, poorly lithified coarser at start, still Mn & Fe stained with nodular laterite. 15 18 wet 17.5m Brown/golden medium quartz sandstone, poorly lithified with abundant silty/clayey matrix. 18 21 Very soft, easy drilling with some harder bands ~20m. red silty sand with minor mica, sand quartz

sub angular to sub-rounded medium to coarse est. ~70% silt/fine sand 21 24 very soft easy drilling. Red brown silty sand. sand quartz & lithics, bimodal fine/silt and

med/coarse quartz. 24 27 increased

water Very soft easy drilling as 21 - 24m. Mn/Fe stained gravel ~26.5m otherwise red brown medium to coarse sand with minor fine sand/silt.

27 30 Blue grey buff silt - clay with clean medium to coarse quartz sand. 30 33 Dark red brown coloured soft & hard bands. ~32m buff coloured then red/brown quartz/lithic

medium to coarse sandstone then buff calcreted quartz sandstone all moderately lithified. 33 36 increased

water 34.5m Red/brown medium grained quartz/lithic sandstone with minor milky vein quartz chips & minor buff coloured medium grained sandstone.

36 39 Mottled brown & cream medium sandstone, moderately lithified possible minor weathered biotite schist(?). Water very clean with little silt or clay suspended.

39 42 very soft as 36 - 39m increased % buff coloured material. 42 45 increased

water 45m Very soft clayey buff coloured poorly lithified medium sandstone. colour becomes slightly orange at base.

45 48 Very soft silty buff to orange medium grained poorly lithified sandstone. very minor milky quartz. 48 51 Very soft green/grey fine to medium grained sandstone, moderately lithified sub-rounded quartz

with orange coating. 51 54 Very soft grey/green fine to medium grained sandstone, moderately lithified becomes orange at base,

minor mica and milky quartz. 54 57 as 51 - 54m but slightly coarser. medium grey/green sandstone, moderately lithified but soft to drill.

quartz sub-rounded & coated. 57 60 Lighter colour with moderately abundant milky quartz, greyer near base then red/brown with rare

fresh granite chips. 60 63 Red @ 62m, orange 62.5m soft as 57 -60m to 62 then oxidised weathered granite. 63 66 extremely oxidised weathered micaceous granite. red/pink colour with abundant silver mica. 66 69 red/pink soft to 67.5m then buff granite. 69 72 buff very soft weathered granite. 72 75 buff very soft weathered granite 75 78 buff then pink @76m very soft weathered granite. EOH

Comments: Granite contact @~62m, quartz greenish colour crystalline with no

rounding evident, abundant white/silver mica. Above 62 quartz sub-rounded with

oxidised coating on chips does not show signs of granitic textures but shows

quartz grains in finer matrix moderately well sorted. Above 62m possible thin

weathering profile?

19

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m

Figure 5 Gamma log for RN 16680

20


Bore : RN 16681 Logged by: P Snepp Date: 10/8/95


Method: GPS

Depth Water Geological Description: From To Info 0 3 Red aeolian sand & soil with abundant fine clayey material. approx 2.8m buff/orange clayey ironstone nodules & rounded quartz & lithic

granules. 3 6 Clayey buff quartz gravel & iron lateritised material. rounded pebbles/granules 6 9 Orange/buff coarse quartz sandstone - rounded to sub-rounded grains to pebble/granule size. 9 12 Pebbly buff/orange coarse quartz sandstone with rounded quartz pebble bands - moderately lithified chips 12 15 Coarse quartz sandstone with buff clayey silty matrix & minor pebbles - moderately lithified. 15 18 very

slightly damp

buff/green clayey medium grained sandstone. Clasts, sand to granules of sub-rounded quartz.

18 21 damp 21m

silty medium sandstone large % matrix of mixed buff/green and buff/orange; weakly lithified; minor rounded granular material.

21 24 Silty medium sandstone. large % buff/green/orange matrix; poorly lithified; minor rounded quartz granules usually Fe coated. 24 27 damp,

balling up Sandy clay orange/buff silty sandy clay with minor coarse quartz sand

27 30 29m seepage inject

Brown clay with very minor silty sand.

30 33 Red/brown medium-coarse clayey sandstone with minor quartz granules - moderately well lithified. 33 36 36m

increase flow

as 30 - 33m with increased brown clay & ~30% light grey/green claystone Conductivity 2800 microS/cm.

36 39 Coarse red/brown lithified sandstone. ~38m coarse gravel associated with slight increase in flow. 39 42 Cond.

2900 microS/cm

Sandy gravel till 39.5m then mixed red/brown & light grey/green clayey silty fine sandstone.

42 45 as 39 -42m but coarser & with minor gravel/granule clasts. 45 48 3 L/s Red/brown/grey medium - coarse sand. little evidence of lithification. minor grey/green siltstone & abundant silty matrix & clay. 48 51 as 45 - 48m with increased lithification apparent from abundant lithified chips. 51 54 Red/brown & grey silty fine - medium sandstone with common coarse quartz sand & lesser granules. minor lithification apparent. 54 57 Buff & red fine - medium silty sandstone, some coarser quartz sand. Mn stained coarse sand common. 57 60 Cond.

2900 microS/cm

as 54 - 57m

60 63 as 57 - 60m + 50% coarse golden sub-angular to sub-rounded quartz sand appears un-lithified. 63 66 5 L/s Golden coarse quartz sand, unconsolidated as evidenced by continual caving SWL

22.6m bgl

Sample Conductivity microS/cm

pH

Comments: Increased groundwater inflow @~66m estimated at ~5L/s causing

continual caving of golden quartz sand horizon.

21

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m

Figure 6 Gamma log of RN 16681

22




Method: GPS

Depth Water Geological Description: From To Info

0 3 Red silty soil to ~1.5m, clayey sandy to ~2.5m then mixed red/brown & buff lateritic sandy claystone

3 6 Coarse silty sandstone, mainly buff but some red/brown, minor very coarse sand/granules. sand mainly quartz, some lithics generally lithified, sub-angular/sub rounded.

6 9 Coarse silty sandstone as 3 - 6m @~6.5m pebbly very coarse granular sandstone @~7.8m silty coarse sandstone all buff coloured. sand quartz & minor lithics moderately well lithified

9 12 Buff granular & pebbly coarse sandstone with abundant silty matrix, sand mainly quartz & minor lithics, moderately well lithified.

12 15 Damp as 9 - 12m 12.5m pebble gravel green/buff. 13.5m golden silt with moderately abundant coarse sub-angular quartz.

15 18 as 13.5m on, 16m red/brown layer ~30cm thick then orange silt. abundant coarse sub-angular quartz sand & minor granules/pebbles. some golden/green silt.

18 21 Mixed orange, golden/green silt with abundant coarse quartz sand. very minor granules and pebbles.

21 24 Damper Orange/golden green silt with abundant coarse quartz sand. ~22.5m red/brown fine - medium grained silty sand with a little coarser sand.

24 27 red/brown as 22.5 - 24m. ~25.5m buff medium to coarse grained sandstone sub-angular quartz with abundant silty matrix.

27 30 Buff/orange coarser to very coarse quartz sand, little evidence of lithification. minor pebbles & granules abundant silty matrix.

30 33 as 27 - 30m 33 36 as 27 - 33m 36 39 v damp

soft drilling

Pebbly coarse to very coarse silty sandstone, brown quartz sub-rounded to sub-angular.

39 42 Light brown very coarse sand, sub-rounded quartz with moderately abundant granules & pebbles. rare finer sand & silt. no evidence of lithification.

42 45 inject Light brown very coarse sand as 39 - 42m. 45 48 making

water Orange/buff medium to coarse grained sub-rounded silty sand with grey siltstone. little evidence of lithification except in silts.

48 51 Red/brown medium sandstone & orangey granular coarse to very coarse sandstone, poorly lithified. 51 54 Orange coarse to very coarse quartz sandstone, poorly lithified. 54 57 as 51 - 54m ~ 56.5m very gravelly with pebbles to 30 mm. 57 60 ~5-6 L/s

3100 microS/cm

as 56.6m coarse to very coarse pebbly sand, unconsolidated caving in, pebbles up to 45 mm

Conductivity 3100 μS/cm SWL 36.4m bgl

23

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m


24





Depth Water Geological Description: From To Info 0 3 Orange/brown sandy soil 3 6 Orange & grey weakly lithified fine to very fine sandstone 6 9 Orange buff pebbly clay & silt 9 12 Buff/orange granular coarse quartz sand, moderately abundant pebbles. silty matrix 12 15 as 9 - 12m with less pebbles and more silty matrix 15 18 as 9 - 12m but coarse to very coarse sand 18 21 as 15 - 18m 21 24 Golden/orange coarse sand 24 27 red/brown clayey very coarse to granular sand 27 30 damp Red brown coarse clayey sand 30 33 wet as 27 - 30m 33 36 1700

μS/cm Buff brown clayey coarse sand, no evidence of lithification

36 39 as 33 - 36m 39 42 as 33 - 39m 42 45 Orange/brown/buff coarse silty sand, rare very coarse quartz sand. all sand sub-angular to sub-

rounded & mainly quartz. 45 48 Orange buff coarse silty sand, no evidence of lithification, minor very coarse quartz sand. 48 51 as 45 - 48m 51 54 2100

microS/cm

Orange silty medium to coarse sand with minor very coarse granular sand

54 57 as 51 -54m 57 60 as 51 -57m with reduced very coarse sand & granules. ~ equal sand & silt. 60 63 Orange/buff coarse silty sand, mixed sub-angular & rounded quartz. no evidence of lithification 66 69 68m

3300 microS/cm

Unconsolidated clean very coarse to granular buff/white sand with moderately abundant pebbles. Sub-rounded & rounded quartz & minor lithics.

69 72 approx 10 L/s

Unconsolidated buff coarse to very coarse sand, sub-angular to sub-rounded quartz with moderately abundant lithic component.

Sample Conductivity microS/cm

pH Comments:

Unconsolidated sands caved to 66.3m el log & caliper in open hole to 66.3m. Tried to drill on using mud to stabilise hole. Unable to get returns with 3 tanker loads of water. Abandoned attempt. Basal sand re-cements on surface heaps on drying out.

25

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m


26





Depth Water Geological Description: From To Info 0 3 Red/brown soil then into buff/orange red clay & coarse sand 3 6 Grey/golden fine silty sand & clay, moderately well lithified, Mn staining on surfaces, minor pebbles. 6 9 Red/brown lithified coarse silty sandstone. ~equal matrix & clasts. harder band @ 8m. moderately

abundant very coarse sand/granules. strong Mn & Fe staining. grey clayey at base. 9 12 Grey/buff lithified coarse silty sand (sand dominates). red & black Fe/Mn staining at top. 12 15 Grey/buff coarse sand, silty matrix ~50/50, sub-angular/sub rounded quartz, minor granules, little

lithification evident. 15 18 as 12 -15m, some red/brown silty sand then ~16m golden clayey with rare sand, ~17m pebbly very

coarse quartz sandstone, moderately lithified, grey/buff colour 18 21 harder

drilling Grey/buff very coarse silty sand; lithified Fe/Mn stained red/brown - black sandstone and golden/brown lithified sandstone

21 24 as 18 - 21m then @22.5m pebbly very coarse granular sandstone. 24 27 damp

sample balls up

Orange/brown coarse to very coarse silty sandstone - minor pebbles. golden silty coarse sandstone. @26.5m red/brown coarse silty sandstone with minor pebbles.

27 30 Orange brown coarse silty sand, sub-angular quartz with minor lithics grading down into more golden orangey brown silty coarse sand with minor granules.

30 33 softer drilling

Golden then orange medium to coarse brown sandstone, lithified & pebbly at top then @31m golden/greenish coarse sandstone. moisture associated with pebble zone at top.

33 36 Dry Orange grey coarse to very coarse sand, pebbly/granular in parts, silty matrix pebbles sub-rounded to rounded, sand sub-angular to sub-rounded, largely quartz.

36 39 Mixed orangey & grey coarse sand with abundant lithics together with more common quartz sub-angular, no carbonate present.

39 42 Grey silty coarse sandstone, very minor red/brown Fe staining. part of interval damp (sample balls up) minor orange intervals.

42 45 Damp 43m

Grey/green coarse silty sandstone at top, pebbly & damp deeper with very coarse sand/granules.

45 48 Very Damp

Green grey coarse silty sandstone with minor granule, sand quartz & lithics ~80/20. no carbonate, abundant very coarse sand

48 51 green grey silty sandstone, rare granules as 45 - 48m 51 54 49 poor

sample return

as 45 -51m, sand comprises milky, granitic & orange varieties. angular to sub-angular. coarse material moderately well lithified.

54 57 extremely damp

as 51 -54m, 55m (wetter) pebbly lithified sandstone, porosity of chips does not appear high.

57 60 58m dry as 54 - 57m but finer; 58.5m orange golden clayey silt with coarse sand. 60 63 orange golden clayey silt with abundant coarse sand. 63 66 as 60 - 63m 66 69 as 60 - 66m 69 72 70m

making water

grey & brown coarse clayey silty sand with granules.

27

Bore : RN 16684 Page 2 of 2

72 75 as 69 - 72m 75 78 Sandy grey clay (coarse quartz sand) 78 84 Combined sample - sandy grey clay passing down into clayey silty grey medium grained sandstone by

~83-84m. 84 87 Clayey silty grey medium sandstone, moderately well lithified; ~86m grey to red/brown sandstone. 87 90 ~ 87.5m very hard drilling. as 84-87 grey medium to coarse lithified sand, possibly top of weathering

profile above granite basement. some brown "lateritic" nodules. @~88.5m softer - probable weathered granite (?) medium to coarse clayey quartz sand well lithified angular .

90 93 cond. 2170 microS/cm

Light grey/white well lithified clayey medium to coarse angular to sub-angular quartz sand. very minor Fe oxide "lateritic chips. some crystalline quartz some with black inclusions. interpreted as weathered basement.

93 96 mixed as 90 -93m with red/brown medium to coarse lithified quartz sands (slightly softer with rare rounded pebbles.

96 99 coarse quartz & lithic sand crystalline and angular some milky quartz, some with black inclusions. black heavy mineral tail on panning, common Fe oxidised chips. ~97m hard orange brown layer (ferricrete?) some milky quartz with red (jasper?) veining possible white feldspar sand grains.

99 102 as 96 -99m 102 105 white & clear crystalline quartz sand 105 106.

6 soft large crystalline milky, smoky, green & clear (included) quartz grains - interpreted as weathered

granitic basement. SWL

75m

Sample

Conductivity microS/cm

pH Comments:

Interpret weathering profile developed on granitic basement from 87.5 m on.

28

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m


29





Depth Water Geological Description:

From To Info

0 3 Red sandy soil

3 6 Pebbly gravel & sand with minor silt

6 9 golden orange buff angular coarse sand with pebbles

9 12 golden & orange buff angular coarse to very coarse sand, Mn & Fe stained in parts. silty matrix

12 15 Pebbly very coarse angular sand - gravel with silty matrix.

15 18 buff/orange - golden sub-angular very coarse sand, silty matrix with little evidence of lithification

18 21 as 15 - 18m, slight increase in silt/clay

21 24 as 18 - 21m

24 27 as 21 - 24m but more orange clay & thus colouration

27 30 Green/buff coarse to very coarse sandstone, some Mn & Fe staining

30 33 damp

sample

balls

up

Coarse to very coarse dark golden brown sub-rounded - sub-angular silty quartz sand minor

granules/pebbles.

33 36 orange/buff coarse to very coarse sand with silty matrix.

36 39 buff - orange coarse sub-rounded silty sand, little evidence of lithification.

39 42 greyish buff/orange as 36 - 39m.

42 45 as 39 - 42m with minor rounded granules/pebbles.

45 48 Orange/grey coarse to very coarse sub-rounded quartz sand with silty matrix & little evidence of

lithification.

48 51 as 45 - 48m coarse sub-rounded silty sand.

51 54 Green/grey/buff moderately lithified coarse silty quartz sand.

54 57 Mixed green & orange/grey buff moderately lithified coarse silty sub-rounded quartz sandstone.

57 60 Brown & gold/orange coarse silty sand, tending to very coarse.

60 63 Damp Brown & golden/orange coarse to very coarse silty sand, no evidence of lithification.

63 66 Buff/green silty very coarse sandstone, moderately lithified, sub-angular to sub-rounded quartz sand.

66 69 as 63 - 66m

69 72 as 66 - 69m with mixed orange silty finer sand.

30

Bore : RN 16685

Page 2 of 2

72 75 Orange buff silty coarse to very coarse weakly lithified sandstone, sub-angular quartz sand.

75 78 Orange buff/red brown coarse weakly lithified sandstone

78 81 wet Orange brown white & red/brown medium to coarse lithified sandstone with clay matrix, minor rounded

very coarse sand/granules, generally sand sub-rounded to sub angular.

81 84 Lithified white & red/brown coarse sandstone, minor rounded granules & abundant clay in matrix.

84 87 small

sample

heap

Golden orange with dark brown "ironstone" (possible regolith). Some chips show possible relic

"granitic" texture. + well lithified cream medium to coarse sand. rare rounded granules.

87 90 Golden sample light brown & white clay with angular to crystalline quartz sand & dark brown & golden

"ironstone" (possible regolith) vague "granitic" texture evident. moderately well lithified.

90 93 Golden heap, dark brown/golden oxidised clay (probable regolith on basement). some granitic chips.

very weathered white & light brown clay.

93 96 Red brown oxidised weathered clayey granite. white & pink clay dominate with crystalline quartz sand

& "ironstone".

96 99 Clayey salmon pink very weathered sample with rare coarser crystalline quartz.

99 102 Clayey Fe red/golden weathered sample shows some "granitic" texture & composition free angular &

crystalline quartz, rarely megacrystic size (porphyroblasts ?)

102 105 Golden brown Fe stained weathered granite comprising quartz & white clay with some Fe stained chips

showing "granitic" texture & composition.

105 107.

5

EOH no sample.

Sample

Condu

ctivity

microS

/cm

pH

Comments:

31

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m


32




Method:

Depth Water Geological Description: From To Info 0 3 Red sandy pebbly soil with abundant quartz pebbles. 3 6 Pebbly silty buff soil, pebbles lateritised. 6 9 Buff/green moderately lithified porous medium to coarse quartz sandstone, minor

silty matrix. 9 12 as 6 - 9m 12 15 Buff green moderately lithified porous medium to coarse quartz sandstone with

minor orange silty sandstone and granules. 15 18 Buff green moderately lithified coarse to very coarse quartz sandstone. silty matrix

with rare carbonate coatings on some grains. rare sub-rounded quartz granules/pebbles.

18 21 Damp Mixed as 15 - 18m & orange coloured material with abundant sub-rounded pebbles and silty matrix. moderately well lithified.

21 24 Damper sample balls Orange buff very coarse pebbly sandstone with abundant silt in porous matrix. evidence of moderate to good lithification.

24 27 very damp Orange buff as 21 - 24m then grey green pebble gravel with abundant silt/sand matrix. rounded pebbles.

27 30 Grey green sandy pebble gravel rounded with silty matrix, sand sub rounded. 30 33 very soft & damp Grey green sandy clayey pebble gravel as 27 - 30m. 33 36 water on rod change as 30 - 33m till ~35m then coarse clayey sand grey green colour & sub-angular. 36 39 inject as 35 -36m. 39 42 Very coarse to granular sand including sub-rounded lithic clasts of gneiss in very

clayey matrix. 42 45 est. 2 L/s @ 44m Clayey medium to coarse red brown quartz sandstone with abundant sub-rounded

granitic and schistose chips/pebbles ? 45 48 caving use mud Coarse to very coarse to granular semi consolidated pebbly & clayey sand. 48 51 Golden orange coarse to very coarse quartz sand with rare sub-angular to sub-

rounded granules and pebbles. 51 54 to 51.8m as 48 - 51m. then white clayey coarse sand with rare sub-angular gneissic

granule/pebbles & granite derived sand grains.. minor golden brown clayey "ironstone" (regolith?)

54 57 Orange/black flecked white clayey coarse sand (possibly very weathered granite(???)

57 60 Light grey clayey medium quartz sand with abundant crystalline xenocrysts of quartz. Balled sample with gneissic texture/appearance. possible relic gneissic foliation preserved in clayey chips.

60 63 as 57 - 60m, rare quartz granules (crystalline) with abundant black inclusions. 63 66 as 60 - 63m with moderately abundant gneissic chips to pebble size, angular &

stained angular quartzite chips. EOH SWL 28.65m Conductivity 5400 microS/cm pH 7.41 Comments: Hole drilled using bi-polymer mud from 47.57m depth due to continual caving. Bore constructed using 100 mm diam. PVC slotted between 40 to 46m and 58 to 64m. Bore developed after construction to produce approx 4-5 L/s.

33

0 50 100 150 200Gamma in cps

0

20

40

60

80

100

Dep

th in

m

1. Figure 11 Gamma log for RN 16686

ti-tree monitoring bore construction programme. bore ...€¦ · monitoring bores was insufficient...

Documents