Case Study – Groundwater Level Monitoring
Groundwater removal on a tunnel construction site required precise monitoring of water level to allow for safe tunneling and shaft construction under unstable ground.
Some 2.78 million trillion gallons of groundwater, 30.1 percent of the world’s freshwater, are estimated for the planet. It is a significant water supply source and provides drinking water for much of the world’s population. In a time when population growth, economic development and urbanization pressure water resources, groundwater monitoring has become a necessity.
Typically, groundwater monitoring involves drilling a well to access the aquifer. Sensors are then lowered into the well to measure the water level and quality. Heron Instruments’ dipperLog SMART Remote Monitoring System offers a permanent wireless monitoring installation for long-term well monitoring. As it is extremely low power and can communicate from remote locations, it provides reliable real-time measurements in rugged environments that can be posted directly to the Cloud.
Heron Instruments’ dipperLog SMART Remote Monitoring System has been installed on the Eglinton construction site. The construction is part of the largest infrastructure investment in Ontario’s (Canada) history. Once constructed, it will run across Eglinton Avenue, in the heart of Toronto, on a 19 kilometre long corridor that includes a 10 kilometre underground portion and 25 stations.
The deployment involves dipperLog SMART Detection Sensors to monitor multiple parameters of the critical dewatering process. As the city of Toronto is sitting on unstable sandy soil, groundwater has to be removed adequately to prevent any water infiltration which would result in a ground collapse. Vacuum pumps are running 24/7 and the aquifers are being monitored closely by several teams around the globe.
Vacuum sensors were installed on the pumping lines to monitor the dewatering operation, current sensors were placed on electrical panels to monitor pump failure. Flowmeters were also installed to keep track of the water being removed, temperature sensors were deployed to prevent freezing lines during the cold Canadian winter. Water level sensors were dropped into several wells to make sure that the groundwater level was below the tunnels being constructed.
Overall, more than 200 sensors were deployed on the Eglinton Crosstown line. Real-time data was gathered using the Spidermesh cooperative mesh technology, to the main gateway where data was being logged and then sent to the Cloud. Several sensors were monitoring underground, in the tunnels and connected to the Spidermesh network, at the surface, through the ventilation shafts.
Data were analyzed on a daily basis, by the workers on-site and by several engineering teams throughout the world, using the software provided with the monitoring system. Additionally, with the tools provided, reports were generated including the logged data and charts of the dewatering process.
Using the dipperLog SMART Remote Monitoring System, the level of management efficiency was significantly increased as it eased collaboration from multiple teams. Real-time monitoring of the construction site help prevent critical failure that can endanger workers and incur significant delays and costs.