2.3.5.2.3 Hazard handling and scope


A full list of hazards has been generated for both coal mines and CSG operations, as described in Section 2.3.5.2.1 and Section 2.3.5.2.2. This section describes the scope of subsequent work, which addresses only a subset of the full list of hazards.

The hazards of primary focus from a BA perspective are those that extend beyond the development site and that may have cumulative impacts, as these are consistent with the regional focus of BA, and are where BA will add value beyond site-specific environmental impact statements (EIS). Ultimately, however, BAs need to be able to address all identified hazards by considering the scope, modelling, other literature or narratives, and specifying where science gaps may exist.

BAs are constrained by considering only impacts that can happen via water, and so hazards such as dust, fire or noise are deemed out of scope and are addressed by site-based risk management unless there is a water-mediated pathway.

In general, leading practice is assumed and accidents are deemed to be covered adequately by site-based risk management procedures and are beyond the scope of BA; for example, the failure of a pipeline is covered by site-based risk management. However, for the Maranoa-Balonne-Condamine subregion, hazards associated with the ‘exploration and appraisal’ and ‘construction’ phases of CSG operations are considered in scope -- even those hazards associated with human error and accidents. These hazards are deemed in scope because activities in this phase (such as hydraulic fracturing and drilling) occur at sufficient scale and frequency to require further consideration in this BA.

Hazards that pertain to the development site and with no off-site impacts are important to acknowledge but will typically be addressed by site-based risk management procedures.

For CSG operations, the following hazards are considered out of scope for further analysis as part of the BA of the Maranoa-Balonne-Condamine subregion because they are deemed to be covered by site-based risk management and regulation:

  • abandonment practice
  • hazards addressed by site management, no water-mediated pathway (dust, fire or noise)
  • containment failure due to construction or design
  • disruption of surface drainage network for site-based infrastructure, plant and facilities, roads, creek crossings
  • equipment/infrastructure failure (e.g. pipeline failures)
  • leaching/leaking from storage ponds and stockpiles
  • spillages and disposals (diesel, mud, cuttings, fluid recovery)
  • vegetation clearance and subsequent soil erosion following heavy rainfall.

Figure 31 and Table 15 describe all hazards associated with CSG operations that are considered to be in scope in the Maranoa-Balonne-Condamine subregion. The hydrological effect of an activity such as ‘water and gas extraction’ depends on the impact cause and impact mode. For example, ‘depressurisation’ (impact cause) that causes ‘subsidence’ (impact mode) affects ‘surface water direction’ (hydrological effect) and ‘aquitard leaks’ (impact cause) that cause ‘non-target, non-reservoir aquifer depressurisation’ (impact mode) affects ‘groundwater pressure’ (hydrological effect) (Figure 31).

Hydrological effects associated with CSG operations that are considered to be in scope in the Maranoa-Balonne-Condamine subregion are shown in Figure 31 and listed below:

  • surface water quality
  • surface water direction
  • surface water flow
  • groundwater quality
  • aquifer properties
  • groundwater composition
  • groundwater flow (reduction)
  • groundwater level
  • groundwater pressure.

Figure 31

Figure 31 Hazards (impact causes, impact modes and activities) and associated effects identified for the life-cycle stages of coal seam gas operations that are considered to be in scope in the Maranoa-Balonne-Condamine subregion

Impact causes are underlined, impact modes are bold and activities are bullet points. Arrows indicate the spatial context for each hazard: aquifers, aquifer outcrop areas, watercourses, catchments.

GDEs = groundwater-dependent ecosystems, groundwater composition = mixing groundwaters of different composition (in terms of natural dissolved solids)

Typology and punctuation are consistent with the hazard analysis dataset (Bioregional Assessment Programme, Dataset 1)

Table 15 Hazards identified for the life-cycle stages of coal seam gas operations that are considered to be in scope in the Maranoa-Balonne-Condamine subregion and their associated hydrological effects, spatial context, temporal context, and potentially impacted assets or ecosystems

This table lists each hazard (with its spatial and temporal context) in a chain of logic from hydrological effects to potentially impacted assets or ecosystems. The spatial context includes target and non-target aquifers, aquifer outcrop areas, coal resource development tenements and watercourses. Within the relevant spatial and temporal context, assets and ecosystems are described using landscape classification rule sets (GAB GDEs, non-GAB GDEs), landscape class group (e.g. ‘Floodplain or lowland riverine (including non-GAB GDEs)’) or asset type (e.g. economic = economic groundwater asset).


Hazard

(with syntax ‘Impact cause: (life-cycle stagea) impact mode – activity’)

Hydrological effects

Spatial context

Temporal contextb

Potentially impacted assets or ecosystems

Aquitard leaks:

(P) Aquifer depressurisation (non-target, non-reservoir) water and gas extraction

Change in GW pressure

Aquifers intersected by CSG wells within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Depressurisation:

(P) Subsidence – water and gas extraction

SW direction

Watercourses within and downstream of tenements

Long term

All

Discharge of treated water to river:

(P) Discharge to river (via first or third party) treated co-produced water storage, processing and disposal

SW quality, SW flow, GW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Discharge of treated water to river:

(P) Discharge to river treated co-produced water storage, processing and disposal

SW quality, SW flow, GW quality

Aquifer outcrops within tenements (GAB and alluvial)

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Drilling control issues:

(E, C) Mud pressure imbalance – drilling, coring and logging

GW quality

Aquifers intersected by CSG wells within tenements

Short term

GAB GDEs, non-GAB GDEs and economic

Drilling control issues:

(E, C) Localised watertable reduction – drilling and logging

GW level

Aquifers intersected by CSG wells within tenements

Short term

GAB GDEs, non-GAB GDEs and economic

Drilling control issues:

(E, C) Very localised watertable reduction – drilling and coring

GW level

Aquifers intersected by CSG wells within tenements

Short term

GAB GDEs, non-GAB GDEs and economic

Human error, accident:

(C) Changing non-target aquifer properties hydraulic fracturing

Aquifer properties

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Human error, accident:

(C) Contaminate non-target aquifer (chemical) hydraulic fracturing

GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Human error, accident:

(C) Intersection of aquifer deviated drilling

GW quality, GW pressure

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Human error, accident:

(C) Miss perforation of target aquifer perforation (connecting aquifers)

GW composition, GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Human error, accident:

(C) Miss perforation of target aquifer perforation (aquifer depressurisation)

GW pressure, GW quality

Target aquifer

Long term

GAB GDEs, non-GAB GDEs and economic

Incomplete grouting:

(C, P) Incomplete/compromised cementing/casing (linking aquifers) reinjection well construction

GW composition, GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Incomplete grouting:

(C) Incomplete/compromised cementing/casing (linking aquifers) –groundwater monitoring bore construction

GW composition, GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Incomplete grouting:

(C) Incomplete/compromised cementing/casing (linking aquifers) groundwater supply bore construction

GW composition, GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Incomplete reservoir knowledge:

(C) Connecting aquifers (too much pressure) – hydraulic fracturing

GW composition, GW quality, GW pressure

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(P) Aquifer depressurisation (coal seam) – water and gas extraction

GW pressure

Target aquifer

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(C) Changing target aquifer properties – hydraulic fracturing

Aquifer properties

Target aquifer within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(C) Contaminate target aquifer (chemical) – hydraulic fracturing

GW quality

Target aquifer within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(C) Fluid loss to aquifer – water injection / fall off test

GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(P) Injection of water into aquifer – treated water disposal

GW composition, GW pressure

Aquifers targeted by reinjection wells

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(E) Reduction in pressure head – pump testing

GW pressure

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(D) Seal integrity loss – pressure concrete durability

GW quality

Aquifers intersected by CSG wells within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(C) Accidental intersection of fault – deviated drilling

GW quality

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(P) Aquifer depressurisation (fault-mediated) – water and gas extraction

GW pressure

Aquifers intersected by CSG wells and faults

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(C) Incomplete/compromised cementing/casing – cementing and casing (gas leakage)

GW quality

Aquifers intersected by CSG wells within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(C) Incomplete/compromised cementing/casing – cementing and casing (linking aquifers)

GW quality

Aquifers intersected by CSG wells within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(E, C) Intersection of artesian aquifer – drilling, coring and logging

GW pressure

Aquifers intersected by CSG wells

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(D) Bore leakage between aquifers – groundwater supply bore decommissioning

GW composition, GW quality, GW pressure

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(D) Bore leakage between aquifers – reinjection well decommissioning

GW composition, GW quality, GW pressure

Aquifers intersected by reinjection wells

Long term

GAB GDEs, non-GAB GDEs and economic

Poor design, construction:

(D) Bore leakage to surface – groundwater supply bore decommissioning

SW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Poor design, construction:

(D) Bore leakage to surface – reinjection well decommissioning

SW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Poor design, construction:

(D) Incomplete seal – pressure concrete completion

GW quality, GW pressure

Aquifers within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Production of water:

(P) Aquifer depressurisation water and gas extraction

GW flow (reduction), GW level

Aquifers intersected by CSG wells

Long term

GAB GDEs, non-GAB GDEs and economic

Rising salts and watertable:

(P) Discharge to river: rising watertable – treated co-produced water storage, processing and disposal

GW level

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Unintended consequence of intended action:

(P) Increase discharge to rivers following irrigation treated co-produced water disposal

SW flow, SW quality

Watercourses

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Unintended consequence of intended action:

(P) Raise watertable following irrigation – treated co-produced water storage and disposal

GW level, GW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Unintended consequence of intended action:

(P) Soil salt mobilisation following irrigation – treated co-produced water storage and disposal

SW quality, GW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Unplanned discharge of water to river:

(P) Discharge to river following heavy rainfall – treated co-produced water storage and disposal

SW quality, SW flow, GW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Unplanned discharge of water to river:

(P) Discharge to river following heavy rainfall – untreated co-produced water storage and disposal

SW quality, SW flow, GW quality

Alluvium and watercourses in aquifer outcrop areas within tenements

Short term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Water extraction:

(P) Groundwater extraction – groundwater supply bore

GW level, GW pressure

Aquifers intersected by groundwater supply bores within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

aLife-cycle stage of coal seam gas operations where C = construction, D = decommissioning, E = exploration and appraisal, P = production

bshort term = less than 5 years, medium term = 5 to 10 years, long term = 10 to 100 years

CSG = coal seam gas, GAB = Great Artesian Basin, GDEs = groundwater-dependent ecosystems, GW = groundwater, SW = surface water, GW composition = mixing groundwaters of different composition (in terms of natural dissolved solids)

Typology and punctuation are consistent with the hazard analysis (Bioregional Assessment Programme, Dataset 1)

Data: Bioregional Assessment Programme (Dataset 1)

For open-cut coal mines, the following hazards are considered out of scope in the Maranoa-Balonne-Condamine subregion because they are deemed to be covered by site-based risk management and regulation and do not have cumulative effects on water in the subregion:

  • addressed by site management, no water-mediated pathway (dust, fire or noise)
  • bore and well construction (integrity, leakage)
  • disruption of surface drainage network for site-based infrastructure, plant and facilities, roads, creek crossings
  • equipment/infrastructure failure (e.g. pipeline failures, plant failures)
  • leaching/leaking from storage ponds and stockpiles
  • loss of containment (due to construction or design, slope failure)
  • re-contouring, compaction and settlement following backfill
  • spillages and disposals (diesel, mud, cuttings, fluid recovery)
  • vegetation clearance and subsequent soil erosion following heavy rainfall.

Of those hazards that are in scope, some will be addressed by the BA numerical modelling, while others (e.g. water quality hazards) will be assessed qualitatively, using the logic and rule-sets described in the conceptual model of causal pathways. The hazard priority number or hazard scores indicate the relative importance of the hazard. Hazards with low scores are of lower priority.

Figure 32 and Table 16 describe all hazards associated with coal mining developments that are considered to be in scope in the Maranoa-Balonne-Condamine subregion. The hydrological effect of an activity such as ‘water management structures’ depends on the impact cause and impact mode. For example, the hydrological effect of ‘poor handling / management’ (impact cause) can cause ‘excessive runoff during closure’ (impact mode) that affects ‘surface water quality and groundwater quality’ (hydrological effects) and ‘diverting site drain line’ (impact cause) can cause ‘disruption of natural surface drainage’ (impact mode) that affects ‘surface water volume / quantity, surface water quality and groundwater quantity / volume’ (hydrological effect). Hydrological effects associated with coal mines that are considered to be in scope in the Maranoa-Balonne-Condamine subregion are shown on Figure 32 and listed below:

  • surface water quality
  • surface water direction
  • surface water flow
  • surface water volume
  • change to zero flow days
  • groundwater quality
  • groundwater direction
  • groundwater flow (reduction)
  • groundwater quantity/volume
  • groundwater pressure.

Figure 32

Figure 32 Hazards (impact causes, impact modes and activities) and associated effects identified for the life-cycle stages of open-cut coal mines that are considered to be in scope in the Maranoa-Balonne-Condamine subregion

Impact causes are underlined, impact modes are bold and activities are bullet points. Arrows indicate the spatial context for each hazard: aquifers, aquifer outcrop areas, watercourses, catchments.

GDEs = groundwater-dependent ecosystems

Typology and punctuation are consistent with the hazard analysis (Bioregional Assessment Programme, Dataset 1).

Table 16 Hazards identified for the life-cycle stages of open-cut coal mines that are considered to be in scope in the Maranoa-Balonne-Condamine subregion and their associated hydrological effects, spatial context, temporal context, and potentially impacted assets or ecosystems

This table lists each hazard (with its spatial and temporal context) in a chain of logic from hydrological effects to potentially impacted assets or ecosystems. The spatial context includes target and non-target aquifers, aquifer outcrop areas, coal resource development tenements and watercourses. Within the relevant spatial and temporal context, assets and ecosystems are described using landscape classification rule sets (GAB GDEs, non-GAB GDEs), landscape class group (e.g. ‘Floodplain or lowland riverine (including non-GAB GDEs)’) or asset type (e.g. economic = economic groundwater asset).


Hazard

(with syntax ‘Impact cause: (life-cycle stagea) impact mode – activity’)

Hydrological effects

Spatial context

Temporal contextb

Potentially impacted assets or ecosystems

Diverting site drain line:

(D) Change to natural surface drainage – creekline diversion

SW directional characteristics, SW volume/quantity, SW quality

Watercourses within and downstream of tenements

Medium to long term

All watercourses

Diverting site drain line:

(D) Change to natural surface drainage – rainwater and runoff diversion

SW volume/quantity, SW quality, GW quantity/volume

Watercourses within and downstream of tenements

Medium to long term

All watercourses

Diverting site drain line:

(D) Disruption of natural surface drainage - creek diversions, levee bunds, creek crossings

SW directional characteristics, SW volume/quantity, SW quality

Watercourses within and downstream of tenements

Medium to long term

All watercourses

Diverting site drain line:

(D) Disruption of natural surface drainage - dam construction for freshwater storage

SW volume/quantity, SW quality, GW quantity/volume

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Diverting site drain line:

(D) Disruption of natural surface drainage - dam construction for mine water storage

SW volume/quantity, SW quality, GW quantity/volume

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Diverting site drain line:

(D) Disruption of natural surface drainage - dam construction for tailings storage

SW volume/quantity, SW quality, GW quantity/volume

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs) GAB GDEs (riverine, springs, floodplain or non-floodplain)

Inevitable, deliberate:

(C) Artificial point of recharge - post-closure water filling the pit

GW quantity/volume, GW quality

Aquifer outcrops within tenements (GAB and alluvial)

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(P) Deliberate - pit wall (stabilisation) dewatering

GW flow, GW direction, GW quantity/volume, GW pressure, SW flow

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Inevitable, deliberate:

(C) Enhanced aquifer interconnectivity - post-closure water filling the pit

GW quality

Aquifer outcrops within tenements (GAB and alluvial)

Medium to long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(D) Groundwater extraction - groundwater supply bore (GW pressure)

GW pressure

Aquifers intersected by groundwater supply bores within tenements

Long term

GAB GDEs, non-GAB GDEs and economic

Inevitable, deliberate:

(C) Groundwater sink - post-closure water filling the pit

GW quantity/volume, GW direction

Aquifer outcrops within tenements (GAB and alluvial)

Medium to long term

GAB GDEs, non-GAB GDEs and economic

Physical disruption of river boundary or channel:

(P) linking aquifers, preferential drainage - mine expansion too close to river/lake

SW flow, GW quantity/volume, GW pressure, GW quality, change to zero-flow days

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Poor handling/management:

(C) Change to natural surface drainage - water management structures (dams, levee bunds and diversions)

SW directional characteristics, SW flow, SW quality

Watercourses within and downstream of tenements

Medium to long term

All watercourses

Poor handling/management:

(C) Excessive runoff during closure - water management structures (dams, levee bunds and diversions)

GW quality, SW quality

Alluvium and watercourses in aquifer outcrop areas within and downstream of tenements

Medium to long term

Floodplain or lowland riverine (including non-GAB GDEs)

GAB GDEs (riverine, springs, floodplain or non-floodplain)

aLife-cycle stage of coal mine where C = mine closure, D = development, E = exploration and appraisal, P = production, R = rehabilitation

bMedium term = 5 to 10 years, long term = 10 to 100 years

GAB = Great Artesian Basin, GDEs = groundwater-dependent ecosystems,GW = groundwater, SW = surface water. Typology and punctuation are consistent with the hazard analysis (Bioregional Assessment Programme, Dataset 1).

Data: Bioregional Assessment Programme (Dataset 1)

Last updated:
4 January 2019
Thumbnail of the Maranoa-Baloone-Condamine subregion

Product Finalisation date

2016
PRODUCT CONTENTS