Olympic Dam Expansion Supplementary Environmental Impact Statement 2011 201

10 tOpOGrapHy anD sOils

10.1 sOil ErOsiOn

issue:

Clarification was sought on the management strategies that would be implemented to control soil erosion, particularly wind

erosion, on disturbed sites.

submissions: 2 and 106

response:

Management strategies would be developed for disturbed areas where the potential for soil erosion has been identified.

Section 10.3.3 and Figures 10.5 and 10.6 of the Draft EIS identified the areas of low, medium, high and very high erosion potential

in the EIS Study Area.

Given the relatively flat terrain and the small, contained catchments in most of the area, standard management practices would

control erosion in those sections with low and moderate erosion potential (i.e. predominantly the southern infrastructure corridor

and the southern route for the gas pipeline corridor options). Such practices include minimising the area of disturbance and

stockpiling topsoil and cleared vegetation for subsequent re-spreading over disturbed areas to promote vegetation regrowth

(refer Section 10.5.1 of the Draft EIS).

Where project infrastructure is to be located in soils of high and very high erosion potential, such as along sections of the northern

route for the gas pipeline corridor options, an Erosion and Sediment Control Plan (ESCP) would be developed before disturbance

works began. Depending on which gas pipeline option was chosen, the ESCP would address dunefield areas associated with the

Strzelecki, Collina and Hope land systems, undulating downs and rolling hills in the Mumpie soil unit, and the bed, banks and

overflow channel areas of the main watercourses. These areas are most susceptible to erosion caused by wind and rain if surface

cover is disturbed (as discussed in Section 10.5.1 and Appendix U of the Draft EIS). Erosion control measures may include

minimising the disturbance footprint; minimising the length of pipeline trench open at any given time; reinstating ground cover

as soon as practicable; watering disturbed surfaces, particularly during periods of high wind; and limiting construction traffic

movement over disturbed areas. Monitoring of disturbed areas and erosion control structures (if installed) would occur during

construction activities, particularly after high rainfall and wind events, and would continue after construction until the disturbed

areas were stabilised.

While soil types in the areas proposed for the landing facility and desalination plant only have a ‘low’ erosion potential, additional

erosion control measures and site-specific ESCPs would be implemented at these sites to ensure that sediment generated from

construction activities did not enter the marine waters (refer Section 10.5.1 of the Draft EIS). As for the high and very high

erosion-prone areas discussed above, the ESCP for the landing facility and desalination plant would be prepared before disturbance

works began (as was shown in Figure 24.4 of the Draft EIS).

Olympic Dam Expansion Supplementary Environmental Impact Statement 2011202

10.2 aciD sulfatE sOils

issue:

It was requested that additional investigations be undertaken and a draft Acid Sulfate Soil Management Plan be prepared

and submitted before any construction activity at the proposed landing facility and water supply pipeline began.

submission: 2

response:

As discussed in Section 10.3.3 of the Draft EIS, risk mapping of acid sulfate soils (ASS) suggests that coastal ASS may occur in

some sections of the EIS Study Area (refer to Figure 10.7 of the Draft EIS, reproduced in the Supplementary EIS as Figure 10.1).

Field sampling and analysis were undertaken at 14 sites that were considered most likely to support ASS. Section 10.5.2 of the

Draft EIS discussed the potential disturbance to ASS near the proposed landing facility and adjacent to Port Bonython Road (for

linear infrastructure). Investigations undertaken for the Draft EIS indicated that these soils have a low acid-generating potential

and could be effectively managed. As noted in Section 10.5.2 of the Draft EIS, and confirmed again here, further investigations

would be conducted during the detailed design phase (i.e. once the final disturbance footprints had been determined) to further

quantify the acid-generating potential of these soils.

As noted in Section 10.6 and Appendix U (Environmental Management Program ID1.1) of the Draft EIS, an ASS Management Plan

would be prepared before construction began in areas where the disturbance of potential acid sulfate soils was confirmed by

field investigations. The Plan would detail the required soil handling methods and lime dosing rates. As shown in Figure 24.4 of the

Draft EIS (reproduced here as Figure 10.2) ASS Management Plans would be prepared six months before construction activities for

the water supply pipeline (areas adjacent to Port Bonython Road), landing facility and transmission line began.

10.3 fOssils

issue:

Further information was requested on the potential impact on fossils in the vicinity of the proposed gas pipeline corridor

options, particularly in relation to the Lake Palankarinna and Lake Callabonna fossil reserves.

submission: 1

response:

There would be no direct disturbance to these fossil reserves as a result of the project.

As discussed in Section 10.3.4 and shown in Figure 10.8 of the Draft EIS (reproduced in the Supplementary EIS as Figure 10.3),

both the Lake Palankarinna and the Lake Callabonna fossil reserves are outside the EIS Study Area. The Lake Palankarinna reserve

is 30 km north of the nearest gas pipeline corridor option, while the Lake Callabonna reserve is about 1 km from the study corridor

of the nearest gas pipeline corridor option – and therefore at least 6 km from the proposed centre-line of a gas pipeline easement

(the study corridor was 5 km wide on each side of the proposed centre-line).

Any potential indirect impacts would be managed by locating temporary construction camps away from the fossil reserves, and,

if deemed desirable by the Department of Sustainability, Environment, Water, Population and Communities (SEWPaC), appropriate

information about the importance of the fossil reserves would be included in the contractor induction programs. As concluded in

Section 10.6 of the Draft EIS, the likelihood of encountering fossils in the EIS Study Area is low and the residual impact was

categorised as negligible.

Olympic Dam Expansion Supplementary Environmental Impact Statement 2011 203

OLYMPICDAM

See inset 2

See inset 1

Areas of potentialdisturbance to

inland ASS

LakeWindabout

PointLowlyWhyalla

Pimba

Woomera

Andamooka

Roxby Downs

Port Augusta

LakeMacFarlane

Lake Dutton

IslandLagoon

Lake Torrens

UpperSpencer Gulf

BH7BH6

BH5

BH4

BH3BH2

BH1

BH17

BH16

kp80

kp60

kp40

kp20

kp320

kp300

kp280

kp260

kp240

kp220

kp200

kp180

kp160

kp140

kp120

kp100

ASS sample locations

Kilometre point (kp)

Gas pipeline alignment options

Water pipeline alignment

Transmission line alignments

Rail alignment

Access corridor

Existing Olympic Dam Special Mining Lease

Existing Roxby Downs Municipality

EIS Study Area

Coastal Acid Sulfate Soil risk (CSIRO)

Low

Moderate

High

BH14

BH15

BH13BH12

BH9

BH8

BH10

KP10

0 5 10 15 20 25km

Inset 2Point Lowly

Investigation AreaInset 1

Port AugustaInvestigation Area

Moomba

Whyalla

Adelaide

Port Pirie

Port Augusta

Roxby Downs

Figure 10.1 Coastal acid sulfate soils (ASS), risk mapping and areas of potential disturbance to inland ASS

Olym

pic Dam

Expansion Supplementary Environm

ental Impact Statem

ent 2011204

PROJECT COMPONENT

EMS review and update

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10

Q3 Q4

Removal of overburden

Mining of first ore

Desalination plant

Metallurgical plant

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

EMS documents including EM Program and:

Greenhouse Gas Management Plan

Weed Management Plan

Native Vegetation Management Plan

Heritage Management Protocol

Social Management Plan

Aboriginal Engagement Plan

Traffic Management Plan

PREDICTED CONSTRUCTION PERIODBased on government and BHP Billiton Board approval Q1, 2010

Pimba intermodal

Transmission line

Gas power plant/pipeline

Roxby Downs expansion

Hiltaba Village

Airport

Darwin Port

Rail

Landing facility

Sulphur handling facility

Access corridor

Water supply pipeline

EMM, EM Program and MPs – 3 year regulatory review

Baseline dust monitoring

Dust Management Plan

Acid Sulfate Soil Management Plan

Stormwater Management Plan

Erosion and Sediment Control Plan

Noise Management Plan

Radioactive Waste Management Plan

Ballast Water Management Plan – Marine

Silt and Sediment Management Plan – Marine

Blasting Management Plan

Marine F/F and WQ MP

Marine F/F and WQ (Baseline)

Figure 10.2 Schedule for environmental management documentation

Olym

pic Dam

Expansion Supplementary Environm

ental Impact Statem

ent 2011205

OLYMPICDAM

Lyndhurst

Leigh Creek

Marree

Finniss Springs

Murnpeowie

Lake Eyre North

Lake Torrens

Lake Frome

Lake Eyre South

Lake Blanche

LakeGregory

Moomba

Andamooka

Roxby Downs

kp80

kp60

kp40

kp20

kp440

kp420

kp400

kp380

kp360

kp340

kp320

kp300

kp280

kp260kp240kp220

kp560

kp540

kp520

kp500

kp480

kp460

kp440

kp420

kp400

kp380kp360

kp340

kp320

kp300

kp280kp260

kp240kp220kp200

kp180

kp160

kp140

kp120

kp100

Lake CallabonnaFossil Reserve

Lake PalankarinnaFossil Reserve

Moomba

Whyalla

Adelaide

Port Pirie

Roxby Downs

Port Augusta

0 10 20 30 40 50km

Kilometre point (kp)

Gas pipeline alignment options

Fossil Reserve

Eyre Formation

Bulldog Shale

Existing Olympic Dam Special Mining Lease

Existing Roxby Downs Municipality

EIS Study Area

Figure 10.3 Geological units known to contain fossils along the gas pipeline corridor options

Olympic Dam Expansion Supplementary Environmental Impact Statement 2011206

10.4 sOil cOntaminatiOn

issue:

Concern was raised that mining and processing activities associated with the proposed expansion could result in localised

impacts on the soil in the vicinity of Olympic Dam.

submission: 62

response:

As described in Section 10.5.4 of the Draft EIS, the potential for mining and processing activities to contribute to soil contamination

in the Special Mining Lease (SML) was assessed and categorised as low. In the area outside the SML the potential was categorised as

negligible. While elevated concentrations of metals and other potential contaminants (including radionuclides) present in

stormwater run-off from on-site facilities such as the metallurgical plant, hardstand areas and the rock storage facility (RSF) may

lead to localised soil contamination, stormwater would be controlled in defined management areas and there would be no

discharge of stormwater from the SML (refer Section 11.5.1 of the Draft EIS and Section 11.1 of the Supplementary EIS for details).

Post-closure, Section 23.8.3 of the Draft EIS noted that potentially contaminated soils in the SML would be assessed and

remediated as specified in the amended site contamination provisions (2007) of the Environmental Protection Act 1993, the

National Environment Protection (Assessment of Site Contamination) Measure 1999 (NEPC 1999), and/or other relevant legislation

at that time that addressed contamination.

Accidental spills of fuel and other hazardous materials have the potential to result in soil contamination. As discussed in Section

22.6.8 of the Draft EIS, transport, handling and storage of fuel and other hazardous materials in the SML would be in accordance

with the relevant state and Australian statutory requirements. As a minimum, the South Australian Environment Protection

Authority standards would be used (EPA Guideline 080/07) (EPA 2007), which require bund sizes and volumes to be 120% of the net

capacity of the largest tank and 133% for flammable material. The objective, as with the current operation, is to prevent spills from

occurring and, if they do occur, to contain the spillage. Current spill management and reporting procedures would continue to be

implemented and updated as required for the expanded operation.