Inflow/Infiltration Studies

Flow Monitoring

Flow monitoring is essential to any inflow/infiltration study. It is the simplest method of accurately assessing the hydraulic performance of a sewer system. The performance of a flow monitoring program may allow the development of the following insights into the hydraulic performance of the system under study.

• Verify pumping capacity of lift stations in the area of interest. Once the lift station pumping capacity has been verified, the run-time records of the lift station may be used to estimate historic flows.
• Different sections of the sewer system can be isolated, which will allow the flow contributions of different system components to be determined.
• The instantaneous and continuous measurements of flow depth, velocity and discharge can be used:
• To analyze the system hyraulics in detail (is the system experiencing back-flow, is the system surcharging, etc.); and
• To calibrate system predictive models.
• By "overlaying" climatic data (rainfall and snowmelt) and the water level fluctuations of nearby surface water bodies (if applicable) on the measured flows, the effects of these potential inflow/infiltration sources can be assessed.
• The actual system performance can be compared to the expected theoretical population flows. Once theoretical population flows are established, the system performance can be quantified (does the system meet regulatory design and operation guidelines?), and the relative contributions of surface water inflow, ground water infiltration and system base flow can be determined.

"A successful flow monitoring program can lead to substantial cost savings, through the optimization of sewer system construction and rehabilitation."

Flow Monitoring Meters

Hydro-Com Technologies Limited uses state of the art area/velocity meters for measuring flow in storm and sanitary sewer systems. Typically used meters include the ISCO 2150 Area Velocity Module, the American Sigma 950 AV and the Buhler Montec Xytec 7050 surveylogger. These flow meters measure velocity (using an ultrasonic Doppler probe) and flow depth (using a differential pressure transducer) simultaneously.

Flow Monitoring Meters Specifications

	Bühler Montec Xytec 7050 surveylogger Accuracy: velocity -0.1 to 4.0 m/s, ± 2.5% depth 0.05 to 2.0 m, ± 0.001 m Temp: -2°C to +80°C Preferred recording interval: 1 to 5 min

	Accuracy: velocity -1.5 to 6.1 m/s, +/- 2.0%, depth: 0.025 to 3.05 m, +/- 0.008 m/m Temp: 0 to 71°C Preferred recording interval: 1 to 5 min

	American Sigma 950 AV Accuracy: velocity -1.5 to 6.1 m/s ± 2.0% depth 0.005 to 3.5 m ± 0.007 m Temp: -40°C to 74°C Preferred recording interval: 1 to 5 min

Confined Space Entry

Equipment used in flow monitoring is installed by Hydro-Com Technologies Limited personnel, who are fully trained in confined space entry procedures. The project team will supply all equipment for the safe installation of the flow monitoring equipment.