Onslow Water Infrastructure Sutitleubtitl Upgrade Project High-Level Risk Assessment on Constituents (excluding NORMs) of the Residual Saline Stream 0 21-March-2014 Issued for Use IB IB IB REV DATE DESCRIPTION ORIG CHK APPR IP Security Company Confidential Total number of Pages (including Cover sheet): 110 Contractor For Contract No Contractor Document No Rev. Contractor Documents C674443 WHST-STU-WA-RPT-0131 0 COMPANY Project Area Disciplin Type Originator Package Sequence-Sht Revision DOCUMENT e CONTROL NO. WS0 9211 RSK RPT URS 000 00006-000 0 a Report Desktop Risk Assessment on Constituents (excluding NORMs) Onslow Water of the Residual Saline Stream Infrastructure Upgrade 21 March2014 Project 42908178/Geo-0739/0 Desktop Risk Prepared for: Chevron Australia Pty Ltd Assessment on Constituents (excluding Prepared by URS Australia Pty Ltd NORMs) of the Residual Saline Stream AUSTRALIA DOCUMENT PRODUCTION / APPROVAL RECORD Issue No. Name Signature Date Position Title Prepared by Ian Brunner 21 March 2014 Senior Principal Ludovic Sprauer Senior Hydrologist Checked by Ian Brunner 21 March 2014 Senior Principal Approved by Ian Brunner 21 March 2014 Senior Principal Report Name: DOCUMENT REVISION RECORD Onslow Water Infrastructure Upgrade Project Issue No. Date Details of Revisions Desktop Risk Assessment on Constituents (excluding NORMs) of Rev A 7 February 2014 First Draft the Residual Saline Stream Rev B 10 March 2014 Second Draft Sub Title: Rev C 21 March 2014 Third Draft Desktop Risk Assessment on Rev 0 21 March 2014 Final Issued for Use Constituents (excluding NORMs) of the Residual Saline Stream Report No. 42908178/Geo-0739/0 Status: Final Client Contact Details: Paul Hoffmann, 0894855654 Chevron Australia Pty Ltd L24, QV1, 250 St Georges' Terrace Perth WA 6000 Issued by: URS Australia Pty Ltd Level 4, 226 Adelaide Terrace Perth WA 6000 PO Box 6004, East Perth, 6892 Australia T: 61 8 9326 0100 F: 61 8 9326 0296 42908178/Geo-0739/0 J:\PER\42908178\6 Deliv\PHASE 3\RSSConstituentsRiskAssessment\Rev0\WHST-STU-WA-RPT-0131_0.docx TABLE OF CONTENTS 1 BACKGROUND .............................................................................................................................. 1 1.1 Introduction ................................................................................................................................... 1 1.2 RSS Volumetric and Constituent Specifications ....................................................................... 2 1.3 Report Objectives ......................................................................................................................... 2 2 SETTING CONCEPTUALISATION ................................................................................................ 5 2.1 Landforms ...................................................................................................................................... 5 2.1.1 Ashburton River and Delta ........................................................................................................... 5 2.1.2 Quick Mud Creek ........................................................................................................................... 7 2.1.3 Supratidal Saline Flats .................................................................................................................. 8 2.1.4 Hooley Creek – Four-Mile Creek Tidal Estuary .......................................................................... 8 2.2 Baseline Range of Water Qualities ............................................................................................ 11 2.2.1 Discussion on Water Sample Collection .................................................................................. 11 2.2.2 Terrestrial Surface Water Qualities ........................................................................................... 11 2.2.3 Tidal Estuary Water Qualities .................................................................................................... 12 2.2.4 Baseline Salinity and Turbidity ................................................................................................. 16 2.2.5 Baseline Dissolved Metals, Non-Metals, Nutrients and Inorganics ....................................... 16 2.2.6 Baseline Water Quality Summary .............................................................................................. 19 2.3 Tidal Creek Productivity and Nutrient Cycles .......................................................................... 20 2.3.1 Mangroves ................................................................................................................................... 20 2.3.2 Primary Productivity and Other Trophic Processes ............................................................... 21 2.3.3 Eutrophication ............................................................................................................................. 22 3 PREDICTED RSS TRANSPORT AND FATES ............................................................................ 23 3.1 Quick Mud Creek ......................................................................................................................... 23 3.1.1 Evaporation-Concentration Influences ..................................................................................... 23 3.1.2 Dissolution and Mobilisation of Salts by Stream Flow ........................................................... 23 3.2 Supratidal Saline Flats ................................................................................................................ 24 3.3 Hooley Creek – Four-Mile Creek Tidal Embayment ................................................................. 25 3.4 Discussion ................................................................................................................................... 26 4 CHARACTERISTICS OF THE RSS CONSTITUENT FOOTPRINTS .......................................... 27 5 CONCEPTUAL MODELS FOR POTENTIAL RISK ASPECTS ................................................... 30 5.1 Salinity .......................................................................................................................................... 30 5.2 Solubility ...................................................................................................................................... 31 5.3 Metals ........................................................................................................................................... 32 5.4 Non-Metals ................................................................................................................................... 33 5.5 Nutrients ....................................................................................................................................... 33 5.5.1 Overview ...................................................................................................................................... 33 5.5.2 Mangrove Responses to Nutrient Enrichment ......................................................................... 34 42908178/Geo-0739/0 5.5.3 Phosphorous Enrichment .......................................................................................................... 38 5.6 Cleaning Agents .......................................................................................................................... 38 6 DESKTOP ENVIRONMENTAL RISK ASSESSMENT ................................................................. 39 6.1 Formalities ................................................................................................................................... 39 6.2 Hooley Creek – Four-Mile Creek tidal embayment .................................................................. 39 6.3 Supratidal Saline Flats and Quick Mud Creek .......................................................................... 46 7 DISCUSSION OF ENVIRONMENTAL RISKS ............................................................................. 47 7.1 Significant Analogies .................................................................................................................. 47 8 CONCLUSIONS ............................................................................................................................ 49 9 REFERENCES .............................................................................................................................. 51 TABLES Table 1-1 RSS Quality Data ........................................................................................................................ 4 Table 2-1 Surface Water Quality in the Headwaters to Quick Mud and Hooley Creeks ........................... 13 Table 2-2 Surface Water Quality on the Supratidal Saline Flats ............................................................... 14 Table 2-3 Hooley and Middle Creeks Estuarine Water Qualities .............................................................. 15 Table 2-4 Indicative Baseline Surface Water Salinity and Turbidity ......................................................... 16 Table 2-5 Baseline Surface Water Quality Ranges for Metals, Non-metals, Nutrients and Inorganic Constituents .............................................................................................................................. 18 Table 3-1 Predicted Discharge Volumes in Quick Mud Creek .................................................................. 24 Table 3-2 Predicted Direct Rainfall and Stream Flow Contributions to the Tidal Creeks