# 9.4.5 Operational monitoring frequency

Operational characteristics throughout the system should be monitored often enough to reveal any failures and trigger a response within a timeframe that is appropriate to how critical the monitored activity or process is. This applies to both measurements and observational monitoring. Online and continuous monitoring should be used wherever possible, particularly at critical control points. For operational characteristics that are deemed less critical or are more stable, grab samples or regular inspections may be sufficient.

Frequency of observations may be increased at times of increased risk; for example, inspections of reservoirs for algal blooms may be more frequent during summer, or floc blanket observations during the coagulation process may be increased when there are higher flow rates through the treatment plant.

Operational monitoring requirements and frequency of monitoring will vary for each water supply, depending on the key characteristics identified through analysis of the water supply system and risk assessment. Table 9.2 provides an example of how selected operational characteristics can be used within a catchment-to-consumer operational monitoring program.

### Table 9.2 Example of an operational monitoring program (characteristics and frequencies) <a href="#table-9-2" id="table-9-2"></a>

<table data-full-width="true"><thead><tr><th>Location</th><th>Characteristic</th><th>Monitoring frequency</th><th width="309">Rationale</th></tr></thead><tbody><tr><td><strong>Catchment</strong></td><td></td><td></td><td></td></tr><tr><td><em>General catchment</em></td><td>Rainfall</td><td>Daily</td><td>Understand impact of rainfall on water quality – to help predict challenge under range of rainfall intensity.</td></tr><tr><td></td><td>Inspection</td><td><p>Monthly -> Daily</p><p>Frequency depends on level of access and use permitted in catchment.</p></td><td>Detect human and animal activities that could cause contamination; confirm that fences and signs are effective.</td></tr><tr><td><em>Feeder streams in catchment</em></td><td><p>Turbidity</p><p>Colour</p><p><em>E. coli</em></p></td><td><p>Monthly</p><p>plus events</p></td><td>Early warning of changes to raw water quality to allow timely changes to treatment processes. Detect local contamination and disturbances.</td></tr><tr><td></td><td><em>Cryptosporidium</em></td><td>Risk-based</td><td>Assess if treatment barriers are needed to effectively remove or inactivate <em>Cryptosporidium</em>.</td></tr><tr><td><strong>Source Water</strong></td><td></td><td></td><td></td></tr><tr><td><em>Storage dam or</em><br><em>raw water reservoir</em></td><td><p>Temperature Profile</p><p>Dissolved oxygen<br>profile</p></td><td>Monthly -> Weekly</td><td>Information for management of water quality in storage with existing or new management systems.</td></tr><tr><td></td><td>General water quality profile</td><td>Weekly -> Event based</td><td>Allow best quality water to be selected for supply.</td></tr><tr><td></td><td>Inspection</td><td>Weekly</td><td>Detect human and animal activities that could cause contamination.</td></tr><tr><td></td><td>Algal cell counts</td><td><p>Monthly -> Daily</p><p>Risk-based</p></td><td><p>Early warning to activate management actions to prevent algal blooms in storage and forewarning of need for additional monitoring, observational surveillance.</p><p>Information for changes to water treatment processes in order to maintain effective removal of algae and algal metabolites.</p></td></tr><tr><td></td><td><em>Cryptosporidium</em></td><td>Risk-based</td><td>Information for changes to water treatment processes in order to maintain optimal <em>Cryptosporidium</em> removal.</td></tr><tr><td></td><td><p>Turbidity</p><p>Colour</p></td><td><p>Continuous</p><p>Weekly -> Event based</p></td><td>Information for changes to water treatment processes in order to maintain optimal turbidity and colour removal.</td></tr><tr><td><em>River intake</em></td><td>Rainfall</td><td>Daily</td><td>Understand impact of rainfall on water quality to help predict challenge under range of rainfall intensity.</td></tr><tr><td></td><td>Inspection</td><td>Weekly -> Daily</td><td>Detect sources of contamination and activities that could cause contamination.</td></tr><tr><td></td><td><p>Turbidity</p><p>Colour</p></td><td><p>Continuous</p><p>Weekly -> Event based</p></td><td>Inform changes to water treatment processes in order to maintain optimal turbidity and colour removal.</td></tr><tr><td></td><td><p>Iron</p><p>Manganese</p></td><td><p>Weekly</p><p>(risk-based)</p></td><td>Inform changes to water treatment processes in order to maintain optimal iron and manganese removal; forewarn of water quality that may cause customer complaints.</td></tr><tr><td></td><td>Algal cell counts</td><td><p>Monthly -> Weekly</p><p>(risk-based)</p></td><td>Forewarn of possible algal risk and need for additional monitoring, observational surveillance.</td></tr><tr><td></td><td><em>Cryptosporidium</em></td><td>Risk-based</td><td>Inform changes to water treatment processes in order to maintain optimal <em>Cryptosporidium</em> removal.</td></tr><tr><td></td><td><p>Turbidity, <em>E. coli</em></p><p><em>Enterococc</em>i</p><p><em>Cryptosporidium</em></p><p>Pesticides</p><p>Colour</p></td><td><p>(Rainfall-related monitoring)</p><p>Risk-based</p></td><td><p>Understand rainfall effects.</p><p>Identify high challenge periods and forewarn downstream processes; identify local point source of contamination. Intervene in catchment before reservoir affected.</p><p>Feedback to industry and source of contamination.</p></td></tr><tr><td><strong>Treatment Processes</strong></td><td></td><td></td><td></td></tr><tr><td><p><em>Coagulation</em></p><p><em>(inlet to flocculation tank)</em></p></td><td>pH</td><td>Daily -> Continuous</td><td><p>Optimise pH for effective coagulation of selected coagulants when raw water quality changes.</p><p>Provide alarm if pH is outside set limits.</p></td></tr><tr><td><p><em>Flocculation</em></p><p><em>(last compartment)</em></p></td><td>Floc characteristics</td><td>Daily -> Event based</td><td>Optimise floc characteristics for effective clarification or filtration when changes occur to raw water quality or operating conditions.</td></tr><tr><td><p><em>Clarifier</em></p><p><em>(clarified water outlet)</em></p></td><td><p>Turbidity</p><p></p><p>Colour</p></td><td><p>Daily -> Continuous</p><p>Daily -> Event based</p></td><td><p>Confirm coagulant dose, pH correction, flocculation and clarifier operations are optimised when changes occur to raw water quality or operating conditions.</p><p>Provide alarm if turbidity is above set limit.</p></td></tr><tr><td></td><td>Visual observation of floc or floc blankets</td><td>Daily -> Event based</td><td>Assess if adjustment needed to process to improve stability of clarification process.</td></tr><tr><td><p><em>Filtration</em></p><p><em>(Individual or combined filtered water)</em></p></td><td>Turbidity</td><td>Continuous</td><td>Provide alarm if filtrate turbidity is above set maximum. Trigger for initiating filter cleaning.</td></tr><tr><td></td><td>Filter Headloss</td><td>Continuous</td><td>Trigger for initiating filter cleaning to avoid turbidity breakthrough.</td></tr><tr><td><p><em>Filtration</em></p><p><em>(Combined filtered water post pH correction)</em></p></td><td>pH</td><td>Continuous</td><td><p>Confirm target pH range is maintained.</p><p>Provide alarm if pH is outside target limits for effective disinfection and corrosion control.</p></td></tr><tr><td></td><td><p>Aluminium</p><p>(If aluminium-based coagulant used)</p></td><td>Weekly</td><td>Assess inadvertent carry-over of aluminium from sub-optimal flocculation pH.</td></tr><tr><td><p><em>Chlorine Disinfection</em></p><p><em>(Chlorine >30 minutes after chlorine injection)</em></p></td><td>Free chlorine residual</td><td>Continuous</td><td>Provide alarm if chlorine residual is outside set limits for maintaining integrity of water quality during reticulation and for reticulation hygiene.</td></tr><tr><td><em>UV Disinfection</em></td><td>UV dose rate</td><td>Continuous</td><td><p>Confirm UV system is operating satisfactorily.</p><p>Provide alarm if below minimum set dose.</p></td></tr><tr><td><p><em>Fluoridation</em></p><p><em>(Downstream of fluoride dosing)</em></p></td><td>Fluoride</td><td><p>Daily</p><p>Continuous (if provided)</p></td><td><p>Confirm target dose is maintained.</p><p>Provide alarm if fluoride is outside set limits.</p></td></tr><tr><td><strong>Distribution System</strong></td><td></td><td></td><td></td></tr><tr><td><p><em>Disinfection</em></p><p><em>(At various locations in the reticulation system selected by careful monitoring design)</em></p></td><td>Chlorine residual</td><td>Continuous -> Daily</td><td>Confirm total chlorine target or free chlorine residual target range are achieved.</td></tr><tr><td><em>Service Reservoirs</em><br><em>and tank</em></td><td>Integrity from contamination</td><td>1 to 5 yearly</td><td>Confirm roof/hatches are effective against ingress of contaminants.</td></tr><tr><td><em>Consumers</em></td><td>Customer complaints</td><td>Ongoing</td><td>Clusters of complaints of turbidity, objectionable taste and odour, illness allow investigation to identify cause(s) of water quality problems.</td></tr></tbody></table>


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