Alcoa Groundwater Test

Community Update ‐ June 2021 1 Alcoa Anglesea

Alcoa Groundwater Pumping Test COMMUNITY UPDATE JUNE 2021

This monthly update provides a status of groundwater levels and water quality for key monitoring

bores, including total extraction rates, as part of the Alcoa 12‐month groundwater pumping test of

the Upper Eastern View Formation (UEVF) aquifer.

In summary:

This report covers the period of 25 May 2021 to 23 June 2021.

The test is progressing well and all activities were conducted in accordance with the licence

conditions.

The daily pumping rate was increased from 3.45ML per day to 4.32ML per day on 8 June

2021.

118.3ML was extracted and placed into the mine void waterbody, with a total of 171.9ML

extracted since the pumping test commenced on 13 May 2021.

The water level increased to RL ‐19.93m (from RL ‐20.42m) which represents 11.8% of the

proposed full volume of the waterbody. (Relative level, or RL, is the water level in metres

below sea level.)

There is no significant change to groundwater levels in the upper part of the UEVF aquifer or

the unconfined shallow Demons Bluff Group (DBG) and Perched Water Table (PWT) aquifers

which are responding to natural climate variations.

As expected, groundwater levels have declined within modelled expectations at the

pumping bore in the lower part of the UEVF aquifer.

Investigation triggers were reached for three out of the 12 nominated trigger bores. Triggers

are set at conservative levels, and these occurrences do not represent any risk to

groundwater dependent ecosystems or any other users.

o Two occurrences (MW33 and MW64 ‐ refer Figure 1 below) are attributed to natural

climate variability and are not related to the pumping test.

o One occurrence (Bore 116459 ‐ refer Figure 1 below) is believed to be due to

multiple factors including climate variability and bore condition, and potentially also

the pumping test. This will continue to be monitored and the pumping rate will also

be reviewed.

Further information about the 12‐month groundwater pumping test can be found in this fact

sheet.

Water Monitoring Plan

The 12‐month groundwater pumping test commenced on 13 May 2021 and is underpinned by a

comprehensive water monitoring plan approved by Southern Rural Water. The plan will ensure the

groundwater extraction is not threatening groundwater dependent ecosystems that may connect to

the aquifer underlying and surrounding the mine, or adversely impact any other users.

Water extraction rates, groundwater levels and quality, and the waterbody level are closely

monitored by a specialist consultant. Results are reported monthly to the co‐regulator technical


working group (TWG) (inclusive of Alcoa, Southern Rural Water, Department Environment Land

Water and Planning, EPA Victoria, Earth Resources Regulation, Barwon Water and CCMA) for review,

and an update is published for the community.

A total of 1,500ML is permitted to be extracted during the pumping test, with a maximum daily

extraction limit of 5.18ML.

To monitor groundwater levels and quality during the pumping test, 28 bores have been selected

with 12 of those also nominated as trigger bores. The location of the trigger and other monitoring

bores are shown in Figure 1 below.

Figure 1: Trigger and other monitoring bore locations.

Each of the trigger bores has defined water level and/or water quality thresholds, known as triggers,

and defined response actions in the event that a trigger is met. The triggers and responses, known as

trigger rules, were developed in consultation with a specialist consultant and Southern Rural Water.

Each trigger has been set at a conservatively low level to ensure we are alerted early, and, if

necessary, able to act quickly during the pumping test to prevent damage to groundwater

dependent ecosystems. In total there are five separate trigger rules, with these applying in various

combinations to the 12 trigger bores. Each trigger rule has different responses ranging from

additional monitoring to reducing the pumping rate.

Data from key Barwon Water monitoring bores in the vicinity is also included in the water

monitoring plan for analysis. This data is provided by Barwon Water.


Extraction rates

Month Volume extracted

(ML) Maximum daily

volume extracted (ML)

Total volume

extracted to date (ML)

May 2021 (from 13/5) 53.6 ML 3.45ML 53.6 ML

June 2021 118.3ML 4.32ML 171.9ML

Figure 2:: Daily extraction rate and cumulative total extracted

Waterbody level

Date Waterbody level RL (m) Monthly Rainfall (mm) Waterbody % Full

26 April 2021 ‐20.93 N/A 10.3%

24 May 2021 ‐20.42 163.2 11.1%

21 June 2021 ‐19.93 65.8 11.8%

Figure 3:: Pit waterbody level and rainfall

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

09‐Apr‐21

16‐Apr‐21

23‐Apr‐21

30‐Apr‐21

07‐M

ay‐21

14‐M

ay‐21

21‐M

ay‐21

28‐M

ay‐21

04‐Jun‐21

11‐Jun‐21

18‐Jun‐21

25‐Jun‐21

02‐Jul‐21

09‐Jul‐21

16‐Jul‐21

23‐Jul‐21

30‐Jul‐21

06‐Aug‐21

13‐Aug‐21

20‐Aug‐21

27‐Aug‐21

03‐Sep‐21

10‐Sep‐21

17‐Sep‐21

24‐Sep‐21

01‐Oct‐21

08‐Oct‐21

15‐Oct‐21

22‐Oct‐21

29‐Oct‐21

05‐Nov‐21

12‐Nov‐21

19‐Nov‐21

26‐Nov‐21

03‐Dec‐21

10‐Dec‐21

17‐Dec‐21

24‐Dec‐21

31‐Dec‐21

07‐Jan

‐22

14‐ Jan

‐22

21‐Jan

‐22

28‐Jan

‐22

04‐Feb‐22

11‐Feb‐22

18‐Feb‐22

25‐Feb‐22

04‐M

ar‐22

11‐M

ar‐22

18‐M

ar‐22

25‐M

ar‐22

01‐Apr‐22

08‐Apr‐22

15‐Apr‐22

Cumulative Volume Ectracted

(ML)

Maxim

um Daily Extraction Rate (L/sec)

Max Daily Flow Rate (L/sec)

Accumulative Volume Extracted (ML)

Daily Extracton Rate and Cumulative Total Extracted

Maximum rate permitted

Maximum volume permitted

0

20

40

60

80

100

120

140

‐45

‐40

‐35

‐30

‐25

‐20

‐15

‐10

Mar‐16

Apr‐16

Jun‐16

Aug‐16

Oct‐16

Dec‐16

Feb‐17

Apr‐17

Jun‐17

Aug‐17

Oct‐17

Dec‐17

Feb‐18

Apr‐18

Jun‐18

Aug‐18

Oct‐18

Dec‐18

Feb‐19

Apr‐19

Jun‐19

Aug‐19

Oct‐19

Dec‐19

Feb‐20

Apr‐20

Jun‐20

Aug‐20

Oct‐20

Dec‐20

Feb‐21

Apr‐21

Jun‐21

Aug‐21

Oct‐21

Nov‐21

Jan‐22

Mar‐22

May‐22

Jul‐22

Sep‐22

Nov‐22

Rainfall (Aireys Inlet (m

m/d)

Pit W

ater Level (mAHD)

Pit Lake

Rainfall Trigger Rule 5

Pit Water Body and Rainfall


Groundwater level monitoring and trigger status

Table 1: Groundwater level monitoring and trigger status.

Bore Overall status Action / Comment

WB05 No trigger reached Continue to monitor

SOBN 116459 Trigger 1 reached Level 1 (investigation) trigger reached. Believed to be as a

result of multiple factors including climate variability, bore

condition and also potentially the pumping test. As a

result of this the pumping rate is being reviewed with the

Technical Working Group.

UEVF MB3 No trigger reached Continue to monitor




DBG MB3 No trigger reached Continue to monitor




MW33 Trigger 1 reached Level 1 (investigation) trigger reached. A result of climate

variability. Continue to monitor.

MW64 Trigger 1 reached Level 1 (investigation) trigger reached. A result of climate

variability. Continue to monitor.

Barwon Water Anglesea borefield monitoring data

The Anglesea borefield is one of a number of water sources that can supplement the existing

Greater Geelong water supply system for Barwon Water. Access to groundwater from the Lower

Eastern View Formation (LEVF) is governed by a bulk entitlement, issued by the Victorian

Government.

During operation, Barwon Water reports monthly on the status against the threshold level for two

key bores. They have recommenced these monthly updates for the duration of the Alcoa pumping

test. The Anglesea borefield groundwater level trigger components (P8 or P19) were not reached

during this reporting period.

For more information on the Anglesea borefield and the monthly updates please see the Barwon

Water website.

Documents

Alcoa Groundwater Test