energy2U Alliance Dewatering Procedure N8603 – North Sydney ZS 2
Signature
CONTENTS 1
Purpose
4
2
Scope
4
3
Induction / training
4
4
Record keeping
4
5
Location of Water Retention Tank(s)
4
6
Monitoring and field measurements
4
7
Water Quality Criteria for Discharge
5
8
Water treatment
5
8.1 pH Levels
5
8.2 Suspended Solids
5
8.3 Hydrocarbons
5
Discharging Water
6
9
10 Maintenance of Settling Tanks
energy2U Alliance Dewatering Procedure N8603 – North Sydney ZS 3
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1
PURPOSE This procedure details the actions to be taken for the dewatering required during the construction of the North Sydney ZS Project (i.e. construction of the Zone Substation, cable vault and other associated cabling works). The procedure does not include dewatering during the demolition of the existing substation as this activity will be covered by a Demolition Management Plan that will be prepared prior to the commencement of demolition. The procedure details requirements for the sediment tank flocculation (if required), pH correction and water discharge to minimise environmental impact on receiving waters and to comply with relevant water quality criteria.
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SCOPE There is no groundwater seepage at the existing North Sydney excavation. Therefore, this procedure applies to stormwater dewatering only. The procedure includes the collection, storage, testing and discharge of stormwater.
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INDUCTION / TRAINING All personnel involved in dewatering will be made aware of the dewatering requirements at the Site Inductions and via regular Toolbox Talks. All personnel involved in dewatering activities will be inducted into the Site Specific Environment and Safety Work Method Statement for the dewatering prior to commencing the task.
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RECORD KEEPING Relevant data will be recorded on the Water Release Approval Form (Appendix A) and submitted to the project environmental representative for review and approval prior to water discharge. All records will be stored on site and uploaded onto Incite.
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LOCATION OF WATER RETENTION TANK(S) Stormwater collected in the base of the excavation will be pumped via a flexible hose and stored in a sediment tank located at street level. The location of the sediment tank is illustrated on the ESCP for the site. Any relocation of the tank will be marked on the ESCPs accordingly.
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MONITORING AND FIELD MEASUREMENTS Water within the sediment tank will be monitored prior to each discharge by field measurements as follows:
an electronic waterproof pH meter and or pH strips; and a turbidity tube.
During initial monitoring, a correlation will be established between total suspended solids (TSS) and turbidity, so that turbidity can be used as a field indicator of TSS prior to discharge. Oil and grease will only be tested for if an oily sheen is visible on the surface of the water.
energy2U Alliance Dewatering Procedure N8603 – North Sydney ZS 4
Samples will be taken from 300mm below the surface of the water at the final baffle and collected in bottles appropriate for the analytes to be tested. Samples will be assessed to confirm compliance with discharge protocol prior to the discharge event. Stormwater collected ZS site will be treated and discharged to the reticulated stormwater system.
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WATER QUALITY CRITERIA FOR DISCHARGE Before any water can be discharged from the sediment tank it must meet the following criteria:
