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Disclaimer
This report has been prepared on behalf of and for the exclusive use of Australia
Pacific LNG Pty Limited, and is subject to and issued in accordance with the
agreement between Australia Pacific LNG Pty Limited and WorleyParsons
Services Pty Ltd. WorleyParsons Services Pty Ltd accepts no liability or
responsibility whatsoever for it in respect of any use of or reliance upon this report
by any third party.
Copying this report without the permission of Australia Pacific LNG Pty Limited or
WorleyParsons is not permitted.
Revision 1 dated 19 November 2010
APLN-000-EN-R01-D-00077
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Contents
1.
Introduction ........................................................................................................................ 1
2. Responsibilities .................................................................................................................. 2
2.1 Construction Period ............................................................................................................ 2
2.2 Operational Period ............................................................................................................. 2
3. Stormwater Management Plan .......................................................................................... 3
3.1
Overview ............................................................................................................................ 3
3.1.1
Aims and Objectives.............................................................................................. 3
3.1.2 Stormwater Management Philosophy ................................................................... 3
3.1.3 Uncontaminated Stormwater Management Strategies ......................................... 7
3.1.4 Contaminated Stormwater Management .............................................................. 7
3.1.5 Auditing / Monitoring.............................................................................................. 7
3.1.6
Stormwater System Maintenance ......................................................................... 8
3.2 Construction Period ............................................................................................................ 8
3.2.1
Performance Indicators ......................................................................................... 9
3.2.2 Mitigation Measures .............................................................................................. 9
3.2.3 Monitoring ............................................................................................................ 10
3.2.4 Maintenance ........................................................................................................ 10
3.2.5
Responsibility ...................................................................................................... 10
3.2.6 Reporting ............................................................................................................. 11
3.2.7 Corrective Action ................................................................................................. 11
3.3
Operation Period .............................................................................................................. 11
3.3.1 Performance Indicators ....................................................................................... 11
3.3.2
Mitigation Measures ............................................................................................ 12
3.3.3 Monitoring ............................................................................................................ 13
3.3.4 Maintenance ........................................................................................................ 13
3.3.5 Responsibility ...................................................................................................... 13
3.3.6 Reporting ............................................................................................................. 13
3.3.7 Corrective Action ................................................................................................. 14
3.4
Contaminated Stormwater Management ......................................................................... 14
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3.4.1 Performance Indicators ....................................................................................... 14
3.4.2
Mitigation Measures ............................................................................................ 14
3.4.3 Monitoring ............................................................................................................ 15
3.4.4 Maintenance ........................................................................................................ 15
3.4.5
Responsibility ...................................................................................................... 15
3.4.6 Reporting ............................................................................................................. 15
3.4.7 Corrective Action ................................................................................................. 15
3.5 Erosion and Sediment Control Plan ................................................................................. 15
4.
References ....................................................................................................................... 17
Figures
Figure 3.1 Proposed Stormwater Drainage System ......................................................................... 6
Tables
Table 3.1 Water Quality Objectives for Stormwater Runoff ............................................................. 3
Table 3.2 Stormwater Discharge Quality Objectives for Construction Period ................................. 9
Table 3.3 Stormwater Discharge Quality Objectives for Operation Phase ................................... 12
Appendices
Appendix 1 Sediment Pond Details
Appendix 2 Gladstone Regional Council Erosion and Sediment Control
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1. Introduction
This site-based Stormwater Management Plan (SMP) for the LNG facility on Curtis Island has been
prepared in accordance with the Australia Pacific LNG Project Environmental Impact Statement (EIS).
The SMP specifies works and measures to be implemented during the construction and operational
phases of the LNG facility to mitigate potential impacts on the water quality in Port Curtis due to the
discharge of stormwater runoff from the site.
The SMP also specifies works and measures to be implemented during the construction period to
reduce the impacts associated with erosion and sediment control. These measures are included in
the conceptual Erosion and Sediment Control Plan (ESCP) in Section 3.5 in this SMP.
The SMP has been prepared in accordance with recommendations contained in relevant guidelines,including:
Draft Urban stormwater Queensland best practice environmental management guidelines -
Department of Environment and Resource Management (DERM).
Stormwater Quality Control Guidelines for Local Government Department of Environment and
Resource Management (DERM).
Best Practice Erosion and Sediment Control International Erosion Control Association (IECA)
Australasia.
The conceptual ESCP has been prepared in accordance with relevant guidelines, including:
Queensland Erosion Control Guidelines DERM.
Soil Erosion and Sediment Control Guidelines for Queensland Construction Sites - Engineers,
Australia (IEAust).
Gladstone Regional Council (GRC) Drainage Design Standards, Erosion and Sediment Control.
Erosion and Sediment Control Management Plans Healthy Waterways.
The management measures and/or monitoring programs will be reviewed for performance and
amended, if required, on an annual basis.
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2. Responsibilities
The persons responsible for compliance with this Plan during the construction period and operational
phase and their responsibilities are summarised below.
2.1 Construction Period
During the construction period, the Construction Contractor Site Manager will be the Responsible
Person and will undertake the following:
Ensure that the requirements of the Plan are satisfied.
Ensure that the contractors and any sub-contractors engaged in the construction of the facility
are advised of their responsibilities to undertake their activities required by the Plan.
Ensure that the monitoring program is implemented properly.
Prepare incident reports and implement remediation measures.
Ensure appropriate records are kept and maintained on-site.
Retain copy of Plan on-site for reference by appropriate personnel.
Recommend additions or changes to Plan based on experience gained from implementation of
Plan.
2.2 Operational Period
During the operational phase and subsequent de-commissioning period, the Australia Pacific LNG Site
Manager or delegate will be the Responsible Person and will undertake the following:
Ensure that the requirements of the Plan are satisfied.
Ensure that the monitoring program is implemented properly.
Prepare incident reports and implement remediation measures.
Ensure appropriate records are kept and maintained on-site.
Retain copy of Plan on-site for reference by appropriate personnel.
Recommend additions or changes to Plan based on experience gained from implementation of
Plan.
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3. Stormwater Management Plan
3.1 Overview
3.1.1 Aims and Objectives
The stormwater management strategy is to manage the stormwater runoff discharged from the site so
that it complies with the recommendations of the Water Quality Objectives listed in the Queensland
Water Quality Guidelines for Central Coast Queensland Region that includes Port Curtis. The water
quality load reduction objectives are summarised in Table 3.1.
Table 3.1 Water Quality Objectives for Stormwater Runoff
Pollutant Load Reduction
Total Suspended Solids (TSS) 85%
Total Phosphorus (TP) 70%
Total Nitrogen (TN) 45%
Gross Pollutants (GP) 90%
(Source: Qld Water Quality Guidelines, 2009)
The aim of the stormwater quality management strategies developed for the LNG facility is to ensurethe compliance with the load reduction targets recommended in the Healthy Waterways guidelines.
This approach has been adopted in recognition of the on-going issues experienced in many areas with
the use of concentration-based receiving water targets as discharge criteria.
3.1.2 Stormwater Management Philosophy
3.1.2.1 Construction phase
Stormwater management during the construction phase is focussed on minimising the export of
sediment in runoff discharged from the site to Port Curtis. This is to be achieved by directing site runoff
to sedimentation ponds and implementing appropriate erosion and sediment control measures.
A spills prevention and response plan will be prepared to prevent hazardous materials and oils
entering the stormwater system and being discharged to Port Curtis. The spills prevention and
response plan may include the following:
Controls for maintenance activities undertaken within designated areas.
Scheduled maintenance of at risk machinery, control equipment and pipework.
Regular training and refresher sessions for plant personnel.
Provision of appropriate clean-up materials at suitable locations.
Recording of spill incidents.
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Undertaking repairs or remedial work as required to minimise risk of future incidents.
3.1.2.2 Operations Phase
Stormwater from the undeveloped areas of the site will be diverted around the LNG facilitys footprint
where practicable in order to reduce the quantity of stormwater entering the developed area of the
site. Stormwater from external areas will be intercepted near the site boundaries and conveyed
directly to the outfalls via open trapezoidal drains.
Diversion drains will be constructed around the northern and southern sides of the LNG facility to
convey runoff from areas outside the LNG facility site to be discharged to Port Curtis via Outfall #1 and
Outfall #4 shown on Figure 3.1. The diversion drains will be designed to convey the peak flows
discharged from the sediment ponds plus the external sub-catchment runoff in the 100 years ARI
design storm events.
The design philosophy that has been adopted for stormwater management during the operational
phase provides separate strategies for clean and potentially contaminated stormwater and is outlined
below.
The largest volume of stormwater discharged from the site will have a minimal risk of chemical
contamination and is considered to be clean. Most clean stormwater will be routed to sedimentation
ponds, but there are some small areas which may be routed directly to the outfalls. These areas will
be protected during construction in accordance with the site-based ESCP, prepared in accordance
with Section 3.5, and then seeded for permanent erosion control. Some clean stormwater may be
pumped from sediment ponds into water trucks for dust control during the construction phase.
Stormwater that may be exposed to a contaminant will be categorised as one of four types: Likely Oily
Water, Accidentally Oily Water, Accidentally Chemically Contaminated Water, or Amine Contaminated
Water. The contaminated stormwater classifications are defined as follows:
Likely Oily Water (LO) stormwater that is likely to contain oil from equipment; one example is
water from the compressor lube oil skid area.
Accidentally Oily Water (AO) stormwater that may possibly contain oil from equipment during
maintenance or as a result of a small leak; examples include the pig receiver and the boil-off
gas compressors.
Accidentally Chemically Contaminated Water (ACC) stormwater from areas containing acid
and caustic service equipment or waste/chemical storage areas.
Amine Contaminated Water (AmC) stormwater from areas with an amine volume greater than
1m3, or with more than two flanges.
Contaminated stormwater from the LNG facility will be collected and treated, as discussed below, and
then directed to the sewage effluent holding tank for disposal with the treated sewage effluent via
irrigation or discharge to Port Curtis in accordance with the Wastewater Management Plan.
Stormwater from inside the LNG trains processing area will be directed to sumps that will be designed
to retain first flush stormwater that is equivalent to 12.5mm depth of rainfall. The first flush is assumed
to wash contaminants from the designated areas, which are assumed to remain flushed for up to 48
hours following rainfall. Stormwater in excess of the first flush will be diverted around the sumps until
the rainfall ceases and the sumps are emptied. The entire process area (except amine area,
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discussed below) will have the first flush stormwater captured via drains and sumps. The southern
LNG area sump will be equipped with an oil skimmer to send oil to the Corrugated Plate Interceptor
(CPI) separator for treatment. Potentially contaminated stormwater collected in the north area sump
will be sent to the CPI separator for treatment. These two sumps will divert excess stormwater to the
adjacent stormwater swale drains when full (after first flush). The diverted stormwater will flow to a
sediment pond prior to discharge to Port Curtis via rock lined outfalls.
Any areas that may contain amine, such as the amine process area, wastewater tank, or wet flare
knock-out drum pumps will be bunded. The bunded areas required for containment will retain 110% of
the enclosed equipment volume, plus 150mm freeboard. The containment areas will be sloped to a
low point and will be capable of manual release to clean stormwater system or holding for collection
and delivery to the wastewater system.
Where equipment is likely to have oil leaks during normal operation, a bunded area sloping to a lowpoint will be constructed around the equipment. The bunded area will be sized for the greatest of (a)
110% of equipment volume, (b) the maximum expected 10 years Average Recurrence Interval (ARI)
intensity of 96.8mm/hr for 30 minutes storm duration (48.4mm depth of rainfall) or (c) 150mm minimum
height. The bunded area will have a manual valve to drain water to either surface drainage or sump,
based on its water quality. If treatment is needed, water will be sent to the CPI separator using
manually operated fixed pump or sump pump.
Bunded areas will be provided around equipment that contains oil but would only be expected to spill
during maintenance or equipment failure, yielding Accidentally Oily Water. These bunded areas will
be designed to contain the rainfall from the maximum expected 10 years ARI, 30 minutes duration
event or the kerb height will be a minimum of 150mm. The bunding will have a manual valve for
draining clean stormwater to surface drains. Any washdown or spill will be collected manually and
discharged to the wastewater tank for treatment and subsequent disposal with the treated sewage
effluent.
Bunded areas will be provided around all acid and caustic service equipment and waste/chemical
storage areas for Accidentally Chemically Contaminated Water within the processing area and where
necessary outside the processing area. The bunding will have a manual valve for draining clean
stormwater to the surface drains. The bund will be 150mm minimum high or will be sized to contain
the volume of the equipment or the design rain storm. Any washdown or spill will be collected
manually and discharged to the wastewater tank for treatment and subsequent disposal with the
treated sewage effluent.
The swale drains within the process area will be designed to convey runoff from the 25 years ARI
design storm event, while the remaining swale drains will be designed to convey runoff from the 10
years ARI design storm event.
The contaminated stormwater from the LNG facility, following treatment, will be directed to the sewage
effluent holding tank for disposal with the treated sewage effluent via irrigation or to Port Curtis in
accordance with the Wastewater Management Plan.
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3.1.3 Uncontaminated Stormwater Management Strategies
3.1.3.1 Construction phase
The stormwater management strategy for the construction period is focussed primarily on minimisation
of sediment loads exported from the site in storm runoff.
The stormwater treatment system for the construction period comprises swale drains to convey runoff
to sedimentation ponds which will reduce suspended sediments from stormwater runoff. The swales
and sedimentation ponds will be constructed to the dimensions and at the locations required for the
operational period of the LNG facility, as indicated on the typical design drawing included in Appendix
1 . Temporary swales and sediment basins may be constructed as required during the construction
period for erosion and sediment control prior to construction of the permanent works.
3.1.3.2 Operations phase
The removal of suspended sediments and contaminates is to be the focus of the stormwater
management for the operational period. The stormwater treatment system for the operational period
comprises gravel lined swale drains and sedimentation ponds to reduce suspended sediments from
stormwater runoff. The locations of proposed sedimentation ponds are indicated on Figure 3.1,
however the locations may change as a result of subsequent amendments to the LNG facility layout.
3.1.4 Contaminated Stormwater Management
Operators will be advised at regular team meetings of the need to identify and minimise contaminationevents and to report incidents to the Responsible Person.
Stormwater runoff from selected areas within the process area, as described above, will be routed to a
treatment process comprising CPI separator, followed by Dissolved Air Flotation (DAF) and tertiary
filtration, prior to disposal with the sewage effluent.
If monitoring indicates a condition or contaminant level that has caused, or has potential to cause,
environmental harm, the Responsible Person will, as soon as is practicable:
Take the necessary actions to rectify the condition or contaminant level so as to avoid or
minimises environmental harm.
Notify the authority of the condition or contaminant level and the actions taken to rectify it.
3.1.5 Auditing / Monitoring
Any management or monitoring plans will be reviewed for performance and amended, if required, on
an annual basis.
All monitoring results will be recorded and kept for a minimum of five years and made available for
inspection upon request by the administering authority.
An annual monitoring report will be prepared each year and presented to the administering authority,
when requested. This report will include but not be limited to:
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A summary of the previous twelve months monitoring results obtained under any monitoring
programs and a comparison of the previous twelve months monitoring results to both the
adopted performance indicators and to the relevant previous results.
An evaluation/explanation of the data derived from any monitoring program.
A summary of any record of quantities of releases.
An outline of actions taken or proposed to minimise the risk of environmental harm from any
condition or elevated contaminant level identified by the monitoring program.
3.1.6 Stormwater System Maintenance
The stormwater management strategy incorporates structural elements that have varying maintenance
requirements to ensure acceptable pollutant removal performance. The recommended maintenance ofthe stormwater quality system is outlined below for the construction period and long-term operational
period.
All stormwater management devices will be installed and maintained to ensure they are working
properly at all times.
3.2 Construction Period
The removal of vegetation and bulk earthworks activities undertaken during the construction period will
expose large areas of the site to potential erosion during rainfall periods. There is also the potential for
release of contaminants that may be attached to the soils that are conveyed in surface runoff to the
drainage lines and subsequently flow into Port Curtis. The capture of sediment laden water within the
sediment control devices and the sedimentation ponds will mitigate potential impacts to water quality
in Port Curtis.
It is proposed to construct sedimentation ponds and internal swale drains during the initial bulk
earthworks activities. All runoff from the site during the construction period will be directed to the
sedimentation ponds via the swale drains in order to minimise the sediment load in run-off discharged
from the site.
The conceptual ESCP for the construction period, presented in Section 3.5 has been prepared in
accordance with relevant guidelines. The ESCP includes additional temporary sediment control
devices, including the installation of silt fences, vegetated buffer strips and diversion bunds, asappropriate.
A number of site-based ESCPs will be prepared in accordance with the conceptual ESCP to manage
erosion and sediment during the various stages of the construction phase. The site-based ESCPs will
demonstrate that all reasonable and practicable measures will be implemented to minimise erosion
and sediment export. Thus stormwater discharged from the construction site in storms that exceed the
design event for the sedimentation ponds will comply with the objectives listed in the draft urban
stormwater best practice environmental management guidelines.
Earthworks in areas that may have the potential to disturb acid sulfate soils (ASS) are to be
undertaken in accordance with the ASS Management Plan.
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3.2.1 Performance Indicators
Stormwater runoff discharged to Port Curtis from the site at the specified outfalls will comply with theperformance criteria listed in Table 3.2, or as specified in the Environmental Authority issued for the
LNG facility.
Table 3.2 Stormwater Discharge Quality Objectives for Construction Period
Pollutant Objective
Coarse Sediment Retain on site
Total Suspended Solids (TSS)
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Inspection of the stormwater system will be undertaken to identify any failures and, if necessary,
repairs will be undertaken.
Trapped sediment will be removed from stormwater drainage system, as required to maintain
function.
Stockpiles will be managed to minimise contamination to the stormwater system.
Stabilisation of disturbed areas will commence as soon as practicable.
3.2.3 Monitoring
The monitoring of the stormwater management works and stormwater discharged from the site during
the construction period will comply with the following:
Sediment fences will be inspected weekly and following each significant rainfall event to assess
the need for repairs or maintenance.
Stormwater will be sampled during the first significant rainfall event each month that results in
stormwater being discharged from any of the sedimentation ponds.
All stormwater samples mandated by an approval will be sent to a NATA registered laboratory
for analysis.
The monitoring and recording of the performance of the drainage control devices, including
overtopping, scouring or erosion of drains and sedimentation ponds or other damage sustained
by any device, together with details of the rainfall and stormwater discharge will be undertaken
following any rainfall event exceeding 25mm in 24 hours.
Stormwater quality will be monitored at the specified outfalls to Port Curtis.
3.2.4 Maintenance
The following maintenance activities will be undertaken on a regular basis:
Removal of litter and accumulated sediment from swale drains, if required.
Repair erosion damage to swale drains.
Removal of accumulated sediment from temporary sediment basins and permanent
sedimentation ponds when required to maintain performance in accordance with the ESCP.
3.2.5 Responsibility
The Construction Contractor Site Manager will be responsible for ensuring that the actions and
measures specified in the Plan are carried out and implemented.
The Construction Contractor Environmental Manager will be responsible for monitoring the
performance of all drainage control devices and for reporting any failures of the sediment and erosion
control devices to the Construction Contractor Site Manager as soon as practicable.
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3.2.6 Reporting
Drainage control devices will be maintained, with records of inspections, failures and repairs kept foreach device.
Following an inspection, the results of stormwater discharge following rain events will be
communicated to the Construction Contractor Site Manager (or delegate) as soon as practicable.
The results of the inspection of drainage control devices, including a record of failures and repairs for
each device, will be provided to the Australia Pacific LNG Site Manager (or delegate) on a monthly
basis.
The inspection and maintenance reports and will be available on site for inspection by relevant
statutory authorities.
3.2.7 Corrective Action
Any failures in the stormwater system during rainfall events will be repaired as soon as practicable to
prevent uncontrolled discharge, erosion or scour.
Any failures during significant rain events will necessitate a review of the design and/or replacement of
drainage control devices. The repair/replacement of damaged devices will be the responsibility of the
Construction Contractor Site Manager after receiving approval from the Australia Pacific LNG Site
Manager.
In the event of a failure in the stormwater system, appropriate remedial work to restore any disturbed
areas will be undertaken by the Construction Contractor Site Manager in consultation with theAustralia Pacific LNG Site Manager.
3.3 Operation Period
Contaminated stormwater will be captured and treated prior to disposal with treated sewage, as
discussed in Section 3.4.
The primary pollutant of concern in the uncontaminated stormwater run-off from the LNG facility will be
suspended solids. Thus, the removal of suspended sediments is to be the focus of the stormwater
treatment system for the operational phase. All drainage swales will include rock check dams to
reduce velocity and facilitate sediment deposition where considered appropriate. The bulk of the
sediment removal will occur in the sedimentation ponds which will have been constructed during the
initial bulk earthworks and site clearing activities in the construction phase.
Stormwater that may be contaminated by process chemicals or other hazardous or toxic materials
from process areas will be collected in a separate drainage system and directed to a dedicated
treatment facility comprising the CPI separator, followed by DAF and tertiary filtration and disposal with
treated sewage effluent, primarily by irrigation. The management of contaminated stormwater is
outlined in Section 3.4.
3.3.1 Performance Indicators
Stormwater runoff at the specified discharge points will comply with the performance criteria listed inTable 3.3, and as specified in the Environmental Authority issued for the LNG facility.
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Table 3.3 Stormwater Discharge Quality Objectives for Operation Phase
Pollutant Limit
Temperature Background 2C
Total Suspended Solids (TSS) 15mg/L
Hydrocarbons 10 mg/L and no visible sheen, oil or objectionable material
pH 6.58.5
Dissolved Oxygen 4mg/L (Minimum)
Cadmium 5.5g/L
Chromium (Cr III) 27.4g/L
Chromium (Cr IV) 4.4g/L
Cobalt 1g/L
Copper 1.3g/L
Lead 4.4g/L
Mercury (inorganic) 0.4g/L
Nickel 70g/L
Silver 1.4g/L
Tributlytin 0.006g/L
Vanadium 100g/L
Zinc 15g/L
(Source: C-G report, November 2010)
3.3.2 Mitigation Measures
The following measures/actions will be undertaken in order to minimise the generation and export ofpollutants in storm runoff discharged from the site:
Inspection of the stormwater drainage system will be undertaken following any rainfall event
exceeding 25mm in 24hrs to identify any failures and, if necessary, repairs will be undertaken.
Accumulated sediment will be removed from swale drains when required.
Accumulated sediment will be removed, if necessary, from the sedimentation basins prior to
October each year at a time when basins are empty.
The accumulated sediment removed from the swale drains and sedimentation basins will be
disposed of using appropriate methods and at suitable locations.
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The treatment facility for contaminated stormwater will be maintained in accordance with
manufacturers recommendations or adopted maintenance plan.
Any spillage of wastes, contaminants or other materials will be cleaned up as quickly as
practicable by using approved methods and materials to prevent contaminants or materials
being transferred to the stormwater drainage system.
3.3.3 Monitoring
The monitoring of the stormwater management works and stormwater discharged from the site during
the operation phase will comply with the following:
Inspection of the stormwater drainage swales will be undertaken following any rainfall event
exceeding 25mm in 24hrs and at intervals not exceeding one month to identify any failures and
to assess sediment accumulation.
Sediment accumulation in the sedimentation basins will be assessed prior to October each year
at a time when basins are empty.
Stormwater will be sampled during the first significant rainfall event each month that results in
stormwater being discharged from any of the sedimentation ponds.
All stormwater samples will be sent to a NATA registered laboratory for analysis.
Stormwater quality will be monitored at the outfalls to Port Curtis (Figure 3.1).
3.3.4 Maintenance
The following maintenance activities will be undertaken weekly from September to March (inclusive)
and monthly for the remainder of the year:
Removal of litter and accumulated sediment from swale drains, if required.
Repair erosion damage to swale drains.
Removal of accumulated sediment from sedimentation basins as specified in 3.3.2 above.
3.3.5 Responsibility
The Australia Pacific LNG Site Manager will be responsible for ensuring that the actions andmeasures specified in the Plan are carried out and implemented.
The Australia Pacific LNG Environmental Manager will be responsible for monitoring the performance
of stormwater management plan including the ESCP and for reporting any failures and necessary
repairs to the system to the Australia Pacific LNG Site Manager.
3.3.6 Reporting
The results of the inspection of stormwater devices, including a record of failures and repairs for each
device, will be communicated by the Australia Pacific LNG Environmental Manager to the Australia
Pacific LNG Site Manager on a monthly basis.
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The inspection and maintenance reports will be kept on site for inspection by relevant statutory
authorities.
3.3.7 Corrective Action
In the event of a failure of stormwater treatment devices, a review will be conducted to assess the
cause of the failure, capacity of the devices and efficacy of the stormwater management program and
identify strategies or augmentations required to improve stormwater management.
3.4 Contaminated Stormw ater Management
The contaminated stormwater classifications are defined as follows:
Likely Oily Water (LO) stormwater that is likely to contain oil from equipment; one example iswater from the compressor lube oil skid area.
Accidentally Oily Water (AO) stormwater that may possible contain oil from equipment during
maintenance or as a result of a small leak; examples include the pig receiver and the boil-off
gas compressors.
Accidentally Chemically Contaminated Water (ACC) stormwater from areas containing acid
and caustic service equipment or waste/chemical storage areas.
Amine Contaminated Water (AmC) stormwater from areas with an amine volume greater than
1m3, or with more than two flanges.
Areas that may generate contaminated stormwater will have first flush stormwater captured andLikely Oily Water will be directed to the CPI separator and DAF for treatment prior to disposal with
treated sewage effluent by irrigation or to Port Curtis.
3.4.1 Performance Indicators
Contaminated stormwater discharged from the site following treatment will comply with the
performance criteria listed in Table 3.3, or as specified in the Environmental Authority issued for the
LNG facility.
3.4.2 Mitigation Measures
The following measures/actions will be undertaken in order to minimise the generation and export of
contaminated runoff discharged from the LNG facility:
Inspection of the first flush capture systems will be undertaken following any rainfall event
exceeding 25mm in 24hrs to identify any failures and, if necessary, repairs will be undertaken.
The satisfactory operation of automated and manual control equipment will be checked prior to
October each year.
A record of these inspections will be kept, as required in Section 3.4.6.
Any accumulated contaminated waste, litter or other materials will be removed from within the
kerbed areas on a regular basis.
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3.4.3 Monitoring
Inspection of the contaminated stormwater drainage systems will be undertaken following any rainfallevent exceeding 25mm in 24hrs and at intervals not exceeding one month to identify any failures and
to assess first flush capture and accumulation of contaminants. A record of these inspections will be
kept, as required in Section 3.4.6
Contaminant accumulation within the kerbed areas and sumps will be assessed monthly and as
necessary during the wet season.
3.4.4 Maintenance
All mechanical and electrical equipment, first flush system, and CPI and DAF units will be inspected
and maintained in accordance with manufacturers recommendations and/or the equipment
maintenance schedule.
3.4.5 Responsibility
The Australia Pacific LNG Site Manager will be responsible for ensuring that the actions and
measures specified in the Plan are carried out and implemented.
The Australia Pacific LNG Environmental Manager will be responsible for monitoring the performance
of stormwater management plan and for reporting any failures and necessary repairs to the system to
the Australia Pacific LNG Site Manager.
3.4.6 Reporting
The results of the inspection of contaminated stormwater devices, including a record of failures and
repairs for each device, will be communicated to the Australia Pacific LNG Site Manager (or delegate)
on a monthly basis.
The inspection and maintenance reports will be kept on site for inspection by relevant statutory
authorities.
3.4.7 Corrective Action
In the event of a failure of any contaminated stormwater treatment devices, a review will be conducted
to assess the cause of the failure, capacity of the devices and efficacy of the contaminated stormwatermanagement program and identify strategies or augmentations required to improve contaminated
stormwater management.
3.5 Erosion and Sediment Control Plan
The soils within the LNG facility site have been assessed as having a moderate erosion potential
based on field observations and Emerson Dispersion Class testing undertaken for the Geology,
Topography, Geomorphology and Soils Assessment (Australia Pacific LNG EIS, Vol 5, Attachment 8).
The hills surrounding the site were found to have a high erosion potential.
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A site-based ESCP will be developed by the Construction Contractors appropriately qualified erosion
and sediment control team. The plan will be developed and implemented prior to the commencement
of any construction activities.
The implementation of appropriate erosion and sediment control measures will be crucial in achieving
the objective of minimal export of sediment in storm runoff discharged to Port Curtis, particularly during
the construction period when large areas of the site will be exposed. Once construction of the LNG
facility is completed, the erosion potential will be reduced to low due to sealing or planting of the areas
between buildings and other facility structures.
The required volume of temporary sediment basins has been calculated to be 438m3per hectare of
area drained, based on design rainfall intensity-frequency-duration (IFD) data for Curtis Island and the
recommendations contained in the IECA guidelines. The guidelines recommend the sediment settling
zone depth should be greater than 600mm and the length to width ratio should be between 2:1 and3:1.
The guidelines also recommend that a sediment storage volume not less than 50% of the settling
volume be provided below the low level drainage outlet.
The following permanent erosion and sediment control works will be constructed in accordance with
the design drawings included in Appendix 1 and as amended, as early as practicable in the
construction period:
Sedimentation basins.
Swale drains including check dams at appropriate locations.
The following temporary erosion and sediment control measures are to be implemented at appropriate
locations when required in accordance with the site as:
Diversion drains or bunds to direct surface runoff around exposed areas.
Silt fences to capture sediment from exposed areas.
Temporary swales to collect and convey surface runoff..
Temporary sediment basins, designed in accordance with IECA Best Practice Erosion and
Sediment Control guidelines.
Stockpiles will be managed to prevent erosion by wind or water.
The temporary erosion and sediment control works will be constructed in accordance with indicative
drawings contained in Gladstone Regional Council Drainage Design Standards, included in Appendix
2 , or Soil Erosion and Sediment Control Engineering Guidelines for Queensland Construction Sites
(Engineers Australia) or other suitable guidelines.
Monitoring and maintenance of erosion and sediment control works will be undertaken as specified in
the Stormwater Management Plan.
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4. References
Australia Pacific LNG Project, Coordinator Generals report on the environmental impact
statement Coordinator-General, 8 November 2010
Australia Pacific LNG Project, Emissions, Discharge and Disposal Plan Bechtel, 4 October 2010
Best Practice Erosion and Sediment Control International Erosion Control Association (IECA),
Australasia, November 2008
Queensland Water Quality Guidelines 2009 Department of Environment and Resource
Management, September 2009
Queensland Water Recycling Guidelines Environmental Protection Agency, December 2005Soil Erosion and Sediment Control Engineering Guidelines for Queensland Construction Sites
Institution of Engineers, Australia (Engineers Australia) (Qld), 1996
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Appendix
Appendix 1 Sediment Pond Details
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Appendix
Appendix 2 Gladstone Regional Council Erosion andSediment Control
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