Kew, Kendall Sewerage
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] 1 LAND & WATER 1 CONSERVATION I 1 l I , j , , , j I J NSW Department of Land and Water Conservation I I I I I I Kew - Kendall Sewerage I Camden Haven River Tidal I Modelling Report I I Estuary Management Group I October 1996 I I I I I I I .. I -. ". I I I I I Contents I 1 Introduction 4 2 Methodology 5 I 3 Datasets 7 4 Hydraulic Modelling 8 I' 4.1 Calibration 11 4.2 Verification .... 12 I 5 Transport Dispersion Results 13 5.1 Continuous Effluent Discharge 16 I 5.2 Ebb Staged Effluent Discharge 19 5.3 Retention Time/ Transport Analysis 19 5.4 Region of Influence .......... 20 I 5.5 Interpreting the Model Results as Dilution 20 I 6 Discussion 21 I List of Tables 1 Model Characteristics . 9 I 2 Comparison of Tidal Harmonic Analysis for Amplitude 13 3 Location of Results and Site Descriptions . 15 4 Results of mean Concentration for 50% Base Flow . 17 I 5 Results of Mean Concentrations for Zero Base Flow . 18 6 Results of Mean Concentrations for Ebb Only Release . 19 I 7 Distance Reached by Drogues after Release . 20 I List of Figures 1 Location and Study Area Details 5 2 . Location of Hydraulic Data .. '. 7 3 Model Grid Used ........ 10 4 Location of Effluent Discharge Sites Modelled 14 I 5 Location of Concentration Results. 16 6 Calibration Results - Entrance Water Levels . 26 I 7 Calibration Results - Hanleys Point Water Levels 26 8 Calibration Results ~ Queens Lake Water Levels 27 I 2 I I I I I 9 Calibration Results - Rossglen (Highway Bridge) Water Levels 27 10 Calibration Results - Stingray Channel Water Levels 0 0 28 I 11 Calibration Results - Watson Taylors Lake Water Levels 28 12 Calibration Results - Entrance Discharge 0 0 0 0 29 13 Calibration Results - Hanleys Point Discharge 0 0 0 0 29 I 14 Calibration Results - Stingray Channel Discharge 0 0 0 0 30 15 Verification Results - Watson Taylors Lake Water Levels - Day 13 - 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 I 16 Verification Results - Watson Taylors Lake Water Levels - Day 23 - 34 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 I 17 Verification Results - Watson Taylors Lake Water Levels - Day 33 -44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33 18 Verification Results - Lower Rossglen Water Levels - Day 13 - 24 0 34 19 Verification Results - Lower Rossglen Water Levels - Day 23 - 34 0 34 I 20 Verification Results - Lower Rossglen Water Levels - Day 33 -44 35 21 Verification Results - Kendal Road Bridge Water Levels - Day 13 I - 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 22 Verification Results - Kendal Road Bridge Water Levels - Day 23 - 34 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 I 23 Verification Results - Kendal Road Bridge Water Levels - Day 33 -44 0 0 0 0 0 0 0 0 0 0 0 0 37 24 Concentration Profile - For Site 1 Release 39 I 25 Concentration Profile - For Site 2 Release 39 26 Concentration Profile - For Site 3 Release 40 27 Drogue Tracks - Site 1 Release - Day 0 - 14 42 I 28 Drogue Tracks ~ Site 1 Release - Day 14 - 28 42 29 Drogue Tracks - Site 2 Release - Day 0 - 14 43 30 Drogue Tracks - Site 2 Release - Day 14 - 28 43 I 31 Drogue Tracks - Site 3 Release - Day 0 - 14 44 32 Drogue Tracks - Site 3 Release - Day 14 - 28· 44 I 33 Drogue Tracks - Site 4 Release - Day 0- 14 45 34 Drogue Tracks - Site 4 Release - Day 14 - 28 45 01 I I I I 3 I I I I I 1 Introduction I The villages of Kew and Kendall are located in the catchment of the Camden Haven River system. The Camden Haven River lies approximately 350 km north I of Sydney on the coastal plain with a catchment area of approximately 720 km 2 2 square kilometres and a waterway area of approximately 27.8 km . The Camden Haven River entrance to the South Pacific Ocean is located at North Haven and I is trained with two breakwalls. The river is the tidal connection for two estuarine lakes, namely Queens Lake, through a relatively small side arm from the main river and Watson Taylors Lake located approximately 8 km upstream of the river I entrance. The river continues upstream through Watson Taylors Lake and onto Kendall approximately 10 km upstream from the lake. The tidal limit is located I 3 km upstream of Kendall. Figure 1 shows details of the study area. Tidal characteristics of the river system indicate that Queens Lake behaves as I a typical coastal lake at the end of an inlet channel with a very small tidal range. Watson Taylors Lake, although with a surface area similar to Queens Lake, maintains a significant tidal range which is then maintained throughout the I upper reaches of the river to Kendall. Because of the relatively shallow nature of Watson Taylors Lake (approximately 1.0 m depth), and a tidal range of half that depth, the lake is quite well flushed in terms of volume of water exchanged. I The river system as a whole though, exhibits ali unusual mix of different tidal hydraulic characteristics. The inlet channel up to Watson Taylors Lake behaves as a typical lake/inlet channel system where the velocities (and discharges) occur I in phase with the tidal water levels. However the upper reach from the Lake to Kendall (and the tidal limit) behave as a typical tidal river system where the I velocities occur 90 degrees out of phase with the water levels. This results in a situation which occurs every tide, ,,,here the upper reaches are ebbing irito the Lake while the inlet channel is still flooding into the lake. Under this situation, I the period of time where both the upper reach and inlet channel are flowing in the same direction is reduced considerably. This means that hydraulically the actual flushing of the upper reaches to the ocean will be of short duration and I very dependent on the tidal phasing of these different sub-systems of the river I system. It has been proposed to implement a sewerage scheme to cater for the villages of Kew and Kendall, and possibly take effluent from the expanding development I around Queens Lake, which currently is processed by the Dunboggan treatment plant. In conjunction with a treatment plant for Kew-Kenda11, effluent manage ment options under consideration include the discharge of treated effluent (either I totally or in part) to the Camden Haven River. I 4 I I I I I I I I I I I Figure 1: Location and Study Area Details I This Report outlines the results of a study into the characteristics of effluent discharge, for a number of discharge site options on the Camden Haven River. The study uses computer models to simulate the tidal and baseflow conditions of I the river and conservative tracers 'injected' into the model, along with simulated I drogues, to determine the movement and dilution of effluent in the river. I 2 Methodology I' A computer model was developed for the whole of the Camden Haven River covering its region of tidal influence. The model used is Flo2D - a 2D mod elling system using curvilinear coordinate grid system, supporting calculation of I hydrodynamic characteristics, and transport dispersion processes amongst other features. This model has been used extensively in Estuary Management for more. I than ten years. Using this model, complete tidal cycles are run to generate water velocities and I water levels throughout the tidal extent of the model. In effect these results are generated solely by defining an ocean water level (which is ·varying with time). Using these calculated velocities and water levels, a transport dispersion model I can be run which then simulates pver time the movement and dispersion of any I 5 I I .............. ~ .. I I I effluent that is released into the river. These model results can be used to show the expected dilution and regions of influence of effluent from given effluent discharge locations. The transport dispersion model is run with a conservative tracer. That I is, this tracer does not decay with time and helps to define the actual regions of influence clearly, giving a picture of worst case concentrations. The chemical I interaction that occurs in nature is not modelled. Another tool that is used, is the modelling of the movement of numerical drogues. Drogues are used extensively in field studies and are small floats whose locations are monitored and is recorded I over a period of time. This can be done in numerical models as well. The use of numerical drogues defines the flow paths and retention time in the estuary. I The model must be calibrated against measured tidal data (1979 Gauging), and then verified against another set of independent data (1995 Water Levels). The I model geometry was based on a combination of survey data from different years, with the bulk of the data from the 1979 Camden Haven Survey.