Sampling Locations
Automated and manual sample stations are located at various points within the treatment process. These locations have also been described in other chapters of this manual. The samples allow the operator to conveniently perform measurements in addition to the online measurements, or to check online instruments, at these key points in the process train. Sample stations include the following:
- Raw water sample station 1 – located in High Lift Pump Area. Automated sample pump for turbidity, temperature, and pH. Manual sample collection with valve.
- Raw water sample station 2 – located in Lower Raw Water Corridor. Automated sample pump for temperature and pH with provisions for future instruments. Manual sample collection with valve.
- Treated water sample station – located in Filter Gallery. Automated sample for turbidity, temperature and pH. Manual sample tap.
- Individual filter effluent sample station – located in Filter Gallery for each filter train. Automated sample for turbidity and differential pressure element and transmitter. Manual sample collection with valve.
- Combined filter effluent sample station – located in Filter Gallery for combined filter effluent. Automated sample for turbidity. Manual sample collection with valve.
- Finished water sample station – located in High Lift Pump Area. Automated sample station for chlorine residual, temperature, and turbidity. Manual sample collection with valve.
- Chlorine sample station – located in Lower Raw Water Corridor. Automated sample station for chlorine residual. Manual sample collection with valve.
Sampling Methods
An analytical method is a procedure that determines the concentration of a contaminant in a water sample. Analytical methods generally describe:
- How to collect, preserve, and store the sample.
- Procedures to concentrate, separate, identify, and quantify contaminants present in the sample.
- Quality control criteria that must meet.
- How to report the results of the analysis.
The analytical method must be suitable for measuring the drinking water contaminant in the concentration range of interest. It must also provide data with necessary accuracy and precision to demonstrate compliance or meet monitoring objectives.
Since decisions regarding treatment processes and chemical shipments are based upon the results of the analytical method, it is important that samples accurately represent the water or chemical shipment being tested. Observing the following points will help ensure samples accurately represent:
- Sample containers that are cracked, or caps that are defective, should be discarded and replaced. Glasgow Water Treatment Plant Chapter 8- Plant Sampling, Operation and Maintenance Manual Laboratory Analysis, and Reporting 8-3 Samples containers should be clean and free of residue from previous samples. Where possible, sample containers should be labeled so that the same containers are used routinely to sample the same unit process. For example, the sample container used to sample raw water on Monday is the same container used to sample raw water on Tuesday.
- When collecting a sample from a faucet in the laboratory, the sample may be taken at any time from a continuously running faucet. If the faucet has been turned off, turn the faucet on and allow to run at least five minutes before collecting a sample.
- If a weight is needed to sink a sample bottle in a process basin, the weight should not contribute to the turbidity.
- When collecting a sample from a chemical shipment, the sample should be taken from only one shipment (i.e. tote, tanker truck, etc.) before cleaning the sample container.
- If a test result diverges greatly from what is expected, collect a second sample to confirm the abnormality before investigating or changing plant processes.
For general purpose and industry specific methods approved by the EPA please visit the EPA website. In addition, the certified laboratory used for analysis are able to provide guidance for sample collection, storage, and shipment.