Bridging the GAPs: Approaches to Treating Water On Farms

How will it be monitored?

When will it be monitored?

Who will perform the monitoring?

What will be monitored? A grower must determine what parameters will be monitored to adequately assess whether the treatment is effective and working as intended. This will depend on the type of the treatment system and the parameters used to control or reduce microbial contamination. Examples of monitoring could include:

• Contact time or flow rate in a UV light system

• Antimicrobial pesticide concentration, such as free chlorine, chlorine dioxide, or peroxyacetic acid

Temperature

pH

percent UV intensity

How will it be monitored? The procedures in which critical limits or operating limits are monitored depends directly on the nature of the control. These methods need to be real-time and accurate, and should be quantitative, i.e., a measurement of an actual value that can be tracked over time. Examples of how to monitor certain parameters include a timer, calibrated thermometer, calibrated pH meter, calibrated scales, test strips, titration, and analytical equipment or a gas analyzer. It is important to note that if the instrument is not working properly or used in the wrong way, there is a significant possibility that the critical limit is not being met. The use of well-written operating procedures and training are crucial for employees responsible for monitoring, as discussed below. When will it be monitored? Ideally, continuous monitoring procedures should be used. This is generally performed by an instrument that continuously measures a parameter and produces a continuous record. In many cases, however, continuous monitoring is not feasible due to cost or the lack of technology. In this case, periodic or non-continuous monitoring is used. The frequency or timing of non ‐ continuous monitoring can be influenced by historical knowledge of the treatment system. Other questions that could influence the frequency of non-continuous monitoring includes the following:

• How much does the process normally vary (e.g., how consistent are the data)? If the monitoring data show a great deal of variation, frequency of documented monitoring should be increased.

• How close are the normal operating values to the critical limit? If the normal values are close to the critical limit, the frequency of monitoring should increase.

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