Case: Flow measurement in streams

Used equipment:

The challenge:

SGU (Sveriges geologiska undersökning) has hired NIRAS, a consulting engineering company, to investigate the pollution in a watercourse in Hagfors, Sweden. The pollution is due to emissions from an old, state-owned dry cleaner’s, where the solvent tetrachlorethylene (PCE) has been used. The solvent has seeped into into the soil and groundwater, which must be cleaned up. SGU wants to measure the flow in the watercourse, in relation to calculating how much of the solvent flows into it. This is where Danova enters the picture.

The solution:

Before we were contacted, flow was calculated from the overhang structure (flow over a concrete edge), where the water level was measured with a pressure transducer, where data had to be read out manually via USB connector. This presented certain challenges, as the concrete edge was relatively long (approx. 4.5 m) and there was not much difference in level across the edge (often only a few cm). Thereby, a measurement error of just 1 mm will give quite high inaccuracy. Furthermore, problems arose in the winter when the surface of the water froze and a pressure measurement could not be used.

Danova proposed measuring further downstream, in a concrete pipe. Here we could achieve a much higher measuring precision. In addition, with our IoT solution, data could be read online. Furthermore, we installed a D-Eye camera that continuously delivers online images of the measurement, to monitor whether the water is frozen or there is something wrong in general. The camera is powered by solar cell, which operates it all year round.