Australia Pacific LNG Project App B Stormwater Management Plan

8/11/2019 Australia Pacific LNG Project App B Stormwater Management Plan

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Australia Pacific LNG ProjectAppendix B - Stormwater Management PlanLNG Facility


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AUSTRALIA PACIFIC LNG PTY LIMITED

AUSTRALIA PACIFIC LNG PROJECT

APPENDIX B - STORMWATER MANAGEMENT PLAN

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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


3.4

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


3.5 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.


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.


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.


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.


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.


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.


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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LNG FACILITY

Appendix

Appendix 1 Sediment Pond Details


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LNG FACILITY

Appendix

Appendix 2 Gladstone Regional Council Erosion andSediment Control


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Documents

Australia Pacific LNG Project App B Stormwater Management Plan