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I I I I I I I I I I I I I I I I I I I I
INSPECTION OF WATER RETAINING STRUCTURES
ALLIGATOR RIVERS REGION
OCTOBER 1984
G D BROw~, J G BASTIAS AND B WHITEHEAD
JB:MB:108 1.7 B(l)
DEPARTMENT OF MINES AND ENERGY
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I I I I I I I I I I I I I I I I I I I I
1
Inspection of dams in terms of the Mines Safety Control
Regulations Section 392 paragraph 3 should be carried
out by the Company. Consequently it must be noted that
these inspections in no way relieve the management of
Ranger and Nabar1ek from their responsibilities to
ensure the dams are safe.
JB:MB:108 1.7 B(2)
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I I I I I I I I I I I I I I I I I I I I
cm,TENTS
A. RANGER PROJECT
CERTIFICATE OF INSPECTION
WATER MANAGEMENT STRUCTURES PLAN
NO 1 RETENTION POND
NO 2 RETENTION POND
NO 3 RETENTION POND
NO 4 RETENTION POND
TAILINGS DAI1
TAILINGS PIPELINE CORRIDOR
PLANT RUN-OFF POND
STOCKPILE AREA
RECOMMENDATIONS
LIST OF PHOTOGRAPHS
PHOTOGRAPHS
B. Nl'.BARLEK PROJECT
CERTIFICATE OF INSPECTION
WATER MANAGEMENT STRUCTURES PLAN
NO 1 EVAPORATION POND
NO 2 EVAPORATION POND
STOCKPILE RUN-OFF POND
PLANT Ru~-OFF POND
AIRPORT RUN-OFF DRAINS
TAILINGS PIPELINE CORRIDOR
WASTE ROCK RUN-OFF POND
RECO¥1MENDATIONS
LIST OF PHOTOGRAPHS
PHOTOGRAPHS
APPENDIX "A" TERMS OF REFERENCE
JB:HB:I07 1. 7 B(3)
4
5
6
8
10
10
10
11
12
12
12
14
15-20
22
23
24
25
26
26
27
27
27
28
29
30-34
35
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I I I I I I I I I
A. RANGER RETENTION PONDS
I I I I I I I I I I JB:MB:I07
1.7B(4)
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4
We certify that the nominated dams in the Ranger mine
site were inspected in accordance with the check list
contained in the Appendix of this report. Within the
limits of our visual inspection no major structural
defects occur and in our opinion the ·dams were safe as
at 22 October 1984.
G D BROWN ACSM, C Eng, MlMM, AM Aust IMM
District Inspector of Mines - Jabiru
J G BAST lAS Min Eng M App Sc Env Po:lution Control
MAlME AM AUS lMM
Senior Environmental Engineer - Darwin
B WHITEHEAD (Geol)
Geologist, Environmental Section NTGS - Darwin
JB:MB:107 1.7 B(5)
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SSOlOOON ~- \
"
JABIRU i,
• 750 looom ! r= __ ~~i:i~8~-.~~iClJ
SOLE IN M£TR.e:S
EAST
SPILLWAY j~
!NDUSrrRIAL A~e'A
Djolkmora BillaoQng
j RPI
a5geOOON-+--~--------------+-~~~----------~t-----~-----"--~--~~~-; ____ ==r"-=~,,~----------~-.~~\----No 3
OREW~ \
8S97000N~-------------------I~~~~-----f~S~E~E~pj~~G~E~C~O~L~LE~C;T~O~R~---:~~~~~~r-~;;~i=~~~~ I S!;MP SEE~G£ COJLECTOR C::J
. SUMP TURKEY NES" PONO
I TAIl.INGS DAM EMBANKMENT
,
MAIN SECURITY GATE i
I
! I -+-------~i-~-t_t_--~-t_------1l~~~~~~ .. ~~rJ9u.~-----------~~--8596QOON i
! ,TA1LlNr DAM
I I i I i I
TAIL1NGS PIPELINE CORRIDOR
i '8595000N~------------------~------------------+-------------------~-----------------t-------------------+------
@SEEPAGE COLLECTOR SUMP
'" o o o
" ~ N
w w w 0 0 w 0
" 0 0 0
0 0 0 0 0 ~ ~ N ~ ~ ;: ,. N N N N
22~ge~ Project hrea
~ __________ G __ =~ __ =r __ a __ l __ Ma __ D ________ ~
w 0
" 0 '.0 ~ N
E:S4/002E
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INSPECTION OF DAMS AT RANGER MINE
An inspection of Ranger water retaining structures was
carried out on 22 October 1984 by Messrs Brown, Bastias
and Whitehead.
NO. 1 RETENTION PO~~
Inspection of this pond was made by walking on the
crest, downstream and upstream embankments, all of
which were in sound condition. No structural defects
were noted.
The downstream wall was covered by heavy, almost dry
vegetation but no sign of important erosion was evi
dent. Only small channels of no immediate consequence
were noted.
Some fine material had been dislodged due to wave
action on the upstream face. This does not require any
remedial action.
Three 300 rom pipes have been installed over the spill-
way to discharge water by siphoning this from the pond
to the culvert and Coonjimba Creek. This operation is
necessary, before the onset of the wet season, to
increase the capacity of the pond for the reception of
the first storms run off which generally contain a
large proportion of suspended solids.
JB:MB:107 1.7B(7)
Some settling
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essential before overflow occurs.
Gabions and concrete wings of the spillway were re-
paired prior to the onset of the last wet season and
are in good shape. However, some cracks in the wings
are appearing again.
Sagging of gabions in the spillway reported in 1983 is
still evident and getting worse. The company intends
to repair these within the next few weeks.
The seepage collector sump was in a satisfactory
condition.
The irrigation system has been installed and appears in
satisfactory condition.
The company carried out test lining on the east side of
the pond to protect the edge of the pond against
erosion by wave action and rain. Pieces of lining
material has been used in the test. The results appear
to be satisfactory.
The two piezometers installed on the downstream side,
east and west of the culvert have been used for moni-
toring piezometric pressures to assess the conditions
and stability of the embankment. This investigation is
now complete and a report prepared by P J Burgess and
Associates, Consultant.
JB:MB:107 1.7 B(8)
This report has not yet been
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submitted. At the time of inspection piezometer RPl/l
read 0.01 m and piezometer RPl/2 was reading below the
datum level.
NO. 2 RETENTION POND
A visual inspection was carried out by walking along
the crest, upstream and downstream faces of the embank-
ment. Also the toe of the north wall and adjacent area
was inspected.
Some erosion reported in April 1984 is still evident
near the north west corner of the upstream face. No
rubbish inside the pond was noticed this time.
Minor erosion was evident near the pumping station.
Erosion by the switchboard and by the seepage discharge
pipe has been repaired. The seepage discharge pipe has
been replaced.
Rip Rap continues to be in good condition throughout.
The downstream wall appears to be in good condition
except for some minor erosion.
The irrigation system is no·... complete and in good
working condition.
JB: ME: 107 1.7 B(9)
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Trees more than five feet in height exist along the
downstream embankment as reported before, but these
will be cut within the next few weeks.
Seepage collector and pump appeared in good working
condition.
The company ..has successfully completed the grouting
operation. This ensured the stability of the embank-
ment and significantly reduced the seepage from the
pond. Water still evident in the area downstream of
the embankment and in Djalkmara Creek apparently has
come from sources other than RP2. These sources may be
the orebody No 3 hill and other higher areas.
Readings from the piezometers were as follows:-
RP2/l Nil
RP2/4 0.15
RP2/5 0.47
RP2/6 Nil
RP2/7 Nil
RP2/8 Nil
RP2/9 Nil
Spillage of grout material is still evident in two
places on the downstream embankment and at the toe.
The removal of this material is not considered
necessary.
JB:MB:I07 1.7B(lO)
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The east side is in good order.
The south side showed minor erosion of no importance.
The wall around RP3 and the western wall were in good
condition.
Oil discharge is still evident on the inner walls of
this pond.
NO 3 RETENTION POND
Crest and wall of embankment were inspected and found
in good order. Spillway aprons were in good condition.
The road along the crest was found in good condition.
Generally, this pond is always in good condition. Only
upgrading of the crest is required from time to time.
NO 4 RETENTION POND (Waste Dump Settling Pond)
Some erosion is evident in the south end of the
dividing wall between RP2 and RP4, but generally both
sides were in good condition. The size of this pond
continues to be reduced significantly by dumping of
waste material.
TAILINGS DAM
The crest, upstream and downstream faces of all four
walls were visually inspected.
spots were observed.
JB:MB:I07 1.7 B(ll)
No seepage or damp
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Permanent power is now available to pumps at each
seepage collector. New permanent pipe lines have been
installed. All four seepage collector pumps and
pipelines are working satisfactorily.
New drilling investigation is being carried out near
the north wall of the dam for stage 3 construction.
Two diamond drill holes have been completed, one at
chainage 372 m and the other at 730 m and at about 50 m
north of the centre line of the Stage II embankment.
TAILINGS PIPELINE CORRIDOR
The corridor was inspected and found in good condition.
The bund on the west side of the sump removed to allow
traffic of heavy machinery has been replaced.
The company will upgrade the bunds in the whole
extension of the corridor within the next few weeks.
The concrete lining of the collector sump has collapsed
and further work is necessary. Also the discharging
channels need repair. Several trees of more than five
feet are evident around the sump.
The company will remove these trees within the next few
weeks.
JB:MB: 107 1.7 B(12)
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PLANT RUNOFF POND
The situation in the pond is still the same as reported
in October 1983 and April 1984, but the works requested
will be carried out within the next few weeks.
STOCKPILE 'AREA
Retaining bunds are in good condition.
RECOMMENDATIONS
To repair the gabion wall at the spillway of RPl
(reported in October 1983).
To repair and regrass areas damaged by grouting
works on the downstream walls of RP2.
Repair any
action to
premises.
damage
pond
made by runoff or any
embankments throughout
other
the
To cut trees more than five feet tall growing in
the embankment faces of all water retaining
structures.
To avoid the discharging of oil into RP2 or any
other water retaining structure within the
premises.
JB:MB:107 1.7B(13)
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To clean up the bottom of the plant run off pond
and construct a retaining wall on the south side
to protect the access road to the pipeline
corridor. (First reported and requested in
October 1983) .
To repair concrete surfaces at the collector sump
of the tailings pipeline corridor. The use of
wire mesh is recommended to protect the new
concreted surfaces.
JB:MB:107 1.7 B(14)
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I I I I I I I I I I I I I I I I I I I I
No
1.
2.
3.
4.
5.
6.
7.
8.
9.
14
RANGER WATER RETAINING STRUCTURES INSPECTION
22 OCTOBER 1984
LIST OF PHOTOGRAPHS
Description
Downstream side of the spillway of RPl showing vegetation covering the embankment.
Pipes used for siphoning water from RPl to Coonjimba Creek.
Gabion on east culvert showing repaired.
side of the spillway near the heavy sagging which needs to be
Lining material used in the test to prevent erosion by wave action and rain at the east side of RP1.
RP2 pump station showing repair works carried out during the last dry season.
RP2 west of embankment and sealed_ road where the grouting operation was carried out. Also showing the new irrigation system.
General view looking down towards RP2 downstream embankment showing spillage of grouting material.
General view looking north east from the top of RP2, showing some surface water in the Dj alkmara Creek bed.
Encased returning seepage pipeline from north central seepage collector to tailings dam.
10. Diamond drill investigation for Stage 3 of the tailings dam construction.
11. Tailings corridor sump showing need for repairs to concrete lining.
12. Discharging channel from the tailings pipeline corridor into the sump showing need of repair.
JB:MB:107 1.7B(l5)
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1. Downstream vegetation
side of covering
15
the spillway of the ernbankmen t.
=""'- ~ ~~ - ~ .. -
~ -:~;i7ii;;{i:l;:,~_-;'::i;.~-.
2. Pipes used for Coonjirnba Creek.
siphoning water
"B'MB-107 ,...... • * .. -
1.7B(16)
RPl showing
~_~~!FA~~-' t.;.:.-':':..I~·II&>·"~~
from RPI to
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3. Gabion on east side of spillway near the culvert showing heavy sagging which needs to be repaired.
4. Lining material used in ~he test to prevent erosion from wave action and rain in the east side of RP1.
JB:MB:I07 l.7B(l7)
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~ ~.,
' .... , "e
-~ ".. , .' ~,
5. RP2 p~~ station showing repair works carried out during the last dry season.
6.
- ~ ,
,,,,,"-" " :-.-,:--"" ';':-"", ,~.';'-.;--:;;~ -'.-:,' = ~ -.};:~ ::~--<:.
"',.;::-- .,~ ~ . ,," _. -
RP2 crest of embankment and sealed grouting operation was carried ou~. the new irrigation system.
JB:MB:I07 1. 7 B (18)
road where the Also, showing
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7. Ga~eral view looking down RP2 ~~ankrnent showing spillage of grout;ng
do",-nstream material.
8 • General showing bed.
JB:MB:I07 1. 7 B(19)
view looking north some surface water
east =rom top o£ RP2, in the Djalkrnara Creek
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9.
10.
19
--~. :-: ....... --" .~ <, .. ~
--Encased Central
;":.'. -','-~-
<.-- ... ~.:-~. ,,~.,
returning seepaae seepage collector to
Diamond drill investigation tailings dam construction.
JB:MB:I07 1.7 B(20)
pipeline +---il;n ..... s ""'c:._--~-':::l
from datu.
for stage 3
North
of the
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11. Tailing corridor surr~ showing need for repairs to concrete lin;ng.
.-"0- , .• -:,,...~._.
t ~... ""' ~ic~:':':':':i<~';': .. _-.L' .. ~ ~ .~'''''.
12 .. Discharging chap_~el from the corridor into the sump showing
JB:MB: 107 1.7 B(21)
tailings pipeline need of repair.
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B. NABARLEK RETENTION PONDS
JB:MB:I07 1. 7 B(22)
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We certify that the nominated dams on the Nabarlek mine
site were inspected in accordance with the check list
contained in the Appendix of this report. Within the
limits of our visual inspection no major defects occur
and in our opinion the dams were safe as at 23 October
1984.
G D BROWN ACSM, C Eng, MIMM, AM Aust IMM
District Inspector of Mines - Jabiru
~1: J G BASTIAS Min Eng M App Sc Env Pollution Control
MAIME AM AUS IMM
senior Environmental Engineer - Darwin
B WHITEHEAD Geol
Geologist, Environmental Section NTGS - Darwin
JB:MB:107 1. 7 B (23)
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I 23
I I I I I I I I I I I I I I I I I I I
~----------------------------I
/
I \ \ \
"
EVAPORATION POND (2.)
/
---1--------
-----
00
>OOs
-+---+-----:------'~~~tf_-IOOOS
QLD MINES LTD
Nabarlek Project
General Map
E83/009E
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INSPECTION OF DAMS AT QML, NABARLEK
An inspection was carried out on 23 October 1984 by
Messrs Brown, Bastias and Whitehead and included the
following dams.
No. 1 Evaporation Pond (EPl)
No. 2 Evaporation Pond (EP2)
Stockpile Run Off Pond (SPROP)
Plant Run Off Pond (PROP)
Airport Run Off Drains
A visual inspection for the first three ponds, which
are adjacent to each other, was along the crest of .the
out embankment. Upstream and downstream walls were
inspected from the top of the embankment. The dividing
structures were inspected in the same way.
NO. 1 EVAPORATION POND
This pond has no function within the water management
system at present. Only rain water has been collected
in the pond during the 1983/84 wet season. At the time
of the inspection the lower level of the pond was
covered by water. In October 1983 the pond was dry.
Water from this pond is being used as partial
irrigation water in the land application test being
carried out by the company.
JB:MB:I07 1.7 B(25)
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This pond could be used for storage of treated water if
treatment of waste water is included in the final
decommissioning and rehabilitation proposal for this
mine.
All physical components of this pond ie: walls, crest,
spillway, measuring gauge and rip rap covering are in
good order.
The top of the embankments of this and all other ponds
are in very good condition.
NO. 2 EVAPORATION POND
All walls are in good order. No significant erosion on
the embankments were observed.
Rip Rap in all walls is in sound condition.
The fail safe spillway and the measuring gauge
associated with it are in good order.
No surface water was observed to the north side of this
pond.
No rain water in the silt trap at the north of the pond
was observed. The silt trap is in good working
condition.
JB:MB:I07 1.7 B(26)
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STOCKPILE RUN-OFF POND
No damp spots were observed in the outer wall. There
was no erosion on either the outer walls or inner walls
of any significance.
The embankment was generally in good order.
The irrigation system to enhance. evaporation installed
on the top of the ore stockpile is working satis
factory. Water used in the system is pumped from this
pond.
PLANT RUN-OFF POND
The embankment was inspected and found in good
condition.
No damp spots were seen in the outer wall. The crest
and inner walls were sound. Bunds to guide plant run-
off water into the"pond were in good order.
Flygt pumps were in position at the pumping station.
They were in good condition. The power supply was also
in good order.
Some cleaning of the bottom of this pond is desirable
but not essential.
JB:MB:I07 1.7 B(27)
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=
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AIRPORT RUN OFF DRAINS
This drain system is in satisfactory condition.
Cleaning of silt traps and some repairs have been
carried out.
TAILINGS PIPELINE CORRIDOR
Bunds and concrete walls of the corridor are in
satisfactory condition.
WASTE ROCK RUN OFF POND
This pond was decommissioned in 1983.
Rehabilitation works are now been carried out in
accordance with the approved program. Revegetation of
this area is expected to be carried out during the
1984/85 wet season.
A new silt trap has been built at the south of the
former waste rock run off pond.
Some works on the top of the embankments, such as the
installation of pipelines, pumps, water treatment
plant, etc, have been carried out in relation to the
JB:MB:I07 1.7 B(28)
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=
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decommissioning and rehabilitation proposals. These
works have not affected the structures of the dams or
the water management system.
RECOMMENDATIONS
There are no special recommendations. The maintenance
of~ the water retaining structures has been carried out
satisfactorily.
JB:MB:I07 1.7 B(29)
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NABARLEK WATER RETAINING STRUCTURES INSPECTION
23 OCTOBER 1984
LIST OF PHOTOGRAPHS
No Description
1-
.2.
EPI showing lower level covered by water.
General view showing the crest of wall dividing EP1 and the SPROP.
3. EP2. embankment and north area accumulated during the wet season. now totally dry.
4. Silt trap at north west of EP2.
5. Plant run off pond and pump station.
6. Airport run off drain system.
where water The area is
7. Rehabilitation of the ex waste rock run off pond area.
8. New silt trap located south of the ex WRROP.
9. Pipelines and valves located on the embankment between EPI and EP2 for land application purposes.
IO. Reverse osmosis test treatment plant located on the north east wall of the stockpile run off pond in relation to decommissioning works.
JB:MB: 107 1.7B(30)
I
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1. EPl showing lower level covered by water.
2. General EPl and
JB:MB:I07 1.7 B(31)
-~-!:~,'~; .. ~:" '7 ,,,
- -7"'''--':''.'"~ ,-'''"/
-~---:'-';:;7;;: --- _.-.-;-
view showing the crest of wall ~ . '1 -& S~OCKP~ e r~nor~ pond.
dividing
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31
EP2 embankment and accumulated during the now totally dry.
north area wet season.
4. Silt trap at north west of EP2.
JB:MB:I07 1.7B(32)
where The
water area is
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5. Plant r~~ off pond and pump stat'on.
6. Airpol. L run off drain system.
JB:MB:107 1. 7 B (33)
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7.
8.
Rehabilitation area.
New silt trap
JB:MB: 107 1.7 B(34)
of
33
...... . :~;: -, .....
~G~~;ii;1£_L"'·'·:·:'~ . ~-'
,:",,,,_.-,
the ex' waste rock run off pond
':--'~'<
:::.- ;. .~. ~"
located at south of the ex w~OP.
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34
9. Pipelines and valves located on the embankment between EPl and EP2 for land application pULposes.
10. Reverse osmosis test. treatment plant located on the north east wall of the stockpile run off pond in relation to decommissioning works.
JB d.ffi: 107 1.7B(35)
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APPENDIX A
TERMS OF REFERENCE FOR PERIODIC SURVEILLANCE
INSPECTIONS OF WATER RETAINING STRUCTURES IN THE
ALLIGATOR RIVERS REGION
1. The ultimate responsibility for the operation,
maintenance, monitoring surveillance and safety of
the water management system and structures rests
with the mining company holding a Special Mineral
Lease under the Mining Act or an Authority under
Section 41 of the Atomic Energy Act.
2. During the operational, decommissioning and
rehabilitation phases of the mining operation,
periodic surveillance inspections will be carried
out on mine site water management structures by
the Department of Mines and Energy assisted by the
other Supervising Authorities.
3. As far as practicable, the safety and surveillance
team shall include at least one Engineer
experienced in modern dam technology and a
hydrogeologist.
4. Where necessary, the services of an experienced
geologist, soils engineer or other specialist may
be utilised
inspections.
JB:MB: 107 1. 7 B(36)
to assist with surveillance
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I I I I I I I I I I I I I I I I I I I I
36
5. The mine operators shall compile a record of data
obtained in the operation of the water management
system which shall include:
•
•
•
•
•
•
•
JB:MB:I07 1.7 B(37)
observations on conditions of water
management structures~
any repairs carried out on water management
structures~
rainfall, pan evaporation and meteorological
data~
use of water from various structures~
water levels in all storages,
water quality in all storages,
water levels in observation bore holes,
quality of water from bore holes~
quality and quantity of water from leakages~
accurate pumping rates for each unit,
total dry weight of tailings placed and total
volume of tailings held~
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I I I I I I I I I I I I I I I I I I I I
6.
37
dry densities of tailings at various tailings
depth,
findings of resistivi ty surveys if carried
out;
established availability and quality of earth
and rock materials for new construction
and/ or repair and maintenance for existing
works.
A technical representative of
shall accompany the team
the mine operator
during all site
inspections and provide additional information as
required.
7. Periodic surveillance inspections shall include
assessments on the following aspects of each water
retaining structure:
•
JB:MB:I07 1. 7 B (38)
Upstream Faces of all embankments
stability
erosion
face protection;
Downstream Face of all embankments
structural integrity - face
leakage, seepage and damp spots
erosion
-::: -"
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I I I I I I I I I I I I I I I I I I I I
•
•
•
JB:MB:I07 1.7 B(39)
38
condition of protecting material
structural integrity - downstream toe
seepage
toe erosion or undercutting
vegetative cover,
Crest of 'all embankments
general condition
roadway condition
drainage
if no roads - vegetative cover;
Spillways
general condition
apron condition
wingwall condition
weep drains,
Culverts and other structures
general condition
inlet and outlet condition
seepage,
Drainage
silt accumulation
vegetative growth
general condition,
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I I I I I I I I I I I I I I I I I I I I
39
• Assessment
condition and effectiveness. of previous
repairs and maintenance
redesign proposals or modifications.
8. After each inspection, the Department of Mines and
Energy will report to the Periodic Surveillance
committee on its assessment of each water
retaining structure including:
• the overall safety of the structures
• the remedial action proposed to remedy any
faults or deficiencies
• recommendations for any action which may be
necessary to ensure the continued safety of
the structures
recommendations for any changes in the
surveillance procedure
• other relevant comments and conclusions.
9. Surveillance inspections shall be carried out each
April and October and reports presented to the
Periodic Surveillance Committee within two weeks
or such further period as becomes necessary.
10. Where an unusual event occurs at a mine site in
relation to the water retaining structures the
Periodic Surveillance Committee may request the
Department of Mines and Energy to inspect the site
and evaluate and report on that event.
JB:MB:107 1.7 B(40)
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