In the first two installments of the Flow Monitoring Webinar Series, Civica aimed to provide a greater understanding of natural phenomena (e.g., rainfall) and assess built systems (infrastructure) and how they perform against design expectations. The webinars also examined available technology and how to effectively operate and maintain it.
Now, this third webinar explores the critical importance of accurate flow and rainfall data. An overview of the webinar will be provided in two parts.
Field-Based Activities to Ensure Flow and Rainfall Monitoring Data Quality
Below are a few field-based activities that can help ensure high-quality flow and rainfall monitoring data is collected.
One of the most important aspects of getting good quality data is site selection, which refers to where the monitoring equipment is installed. Before a location is determined, the following factors must be considered:
- Purpose: Consider the end goal and the type of data that needs to be collected to reach this end goal. For example, the reason for selecting a specific site might be to develop dry weather flow and wet weather flow patterns.
- Safety: Some locations may not be the safest (e.g., in the middle of an intersection). There may be other locations, however, that are safer and provide the same type of data.
- Site Layout and Hydraulics: Some sites might look good initially but might have a lot of offsets that might affect the hydraulics at that location.
- Desired Accuracy: Locations with a smooth laminar flow are the best for getting good quality data.
- Ease of Installation: Installations can be done in anything from three-meter-deep to ten-meter maintenance holes. It’s important to consider how easy it will be to get equipment into the maintenance holes for testing.
- Debris/Ragging/Maintenance: If there is potential debris, ragging, or maintenance issues, such as a lot of silt buildup or chunks, it may be indicative that it is not a good location to use expensive equipment.
- Duration of Monitoring: The equipment used needs to be appropriate for the specific location. For example, if the location has a very high wet weather flow response, a sensor that measures just 30 centimeters (about 12 in) may not be appropriate.
- Range of Values Required: If a couple meters of surcharging is expected or if there is a CSO (Combined Sewer Overflow) or SSO (sanitary sewer overflows) at that location and overflows are expected, adjustments might be needed in the methodology used to install the equipment.
Equipment Operations and Maintenance
This refers to simple steps that can be taken to operate and maintain the equipment, such as:
- Check Battery Levels: Some types of equipment have alarms that indicate when the battery levels are getting too low.
- Test Telemetry: This makes sure that data is being sent on a near real-time basis, whether that is every hour or a few times a day.
- Clean Logging Equipment: Oftentimes, maintenance holes allow muddy water to get in, so it’s important to clean the dirt and debris off the equipment.
- Have Manual Downloads of Data: This is to ensure there is always a backup of the data when monitoring flow conditions.
- Check Flow Conditions: Pictures and videos of the flow conditions should be collected to note any changes with the flow conditions.
- Check Air Quality Conditions: Every time someone enters a confined space, the air quality needs to be tested for oxygen, H2S, and other explosive gases.
- Clear Dirt/Debris from Sensors: If there is inflow or contact sensors, sometimes a bit of debris gets caught on them and they need to be cleaned.
- Replace Desiccant: If there is a pressure sensor, it usually has a desiccant tube, which needs to be normalized to the ambient air pressure because water will affect the pressure readings.
Site Calibration and Spot Checking
Whenever there is a flow meter installed, it’s important to ensure site calibration and spot checking is performed.
- Depth: This includes measurements where depth is recorded by the sensor using a staff gauge. Typically, at least 5-10 separate measurements are taken, and the average is calculated.
- Velocity: A velocity probe is used to record the velocity of the flow. It is recorded by a sensor. Multiple measurements are taken across the flow profile (depending on how big the pipe is).
NOTE: The goal is not to change any logger offsets onsite. Only adjust as necessary as part of post-processing data if trends are apparent.
Why Choose Civica?
Part two of the webinar recap will highlight the remote activities, as well as the latest analysis tools and techniques used for effectively managing flow monitoring programs.
Learn More at: