Group 1 : Groundwater sampling

 The date was 24/10/24 and our task was groundwater sampling. The weather was partly cloudy, and the atmosphere temperature was 7 °C. There was no rain. We were participated by Kerkko, Svenja, Antti and Thomas.

Groundwater sampling

This task involved collecting a sample of the water flowing underground to Lake Pieni-Valkeinen. To do this, we went to a site with a borehole. The information we needed about the borehole is shown below.

Figure : Borehole informations

Figure : Pipe's picture

As we were the first group to carry out this task, it was essential to drain the water before collecting the sample. The quality of the water when we arrived was affected by the well, which retains some of the clay soil particles. To drain the water, we had a pump at our disposal. 

Figure : Pump's picture

Before using this pump, we calculated the approximate volume of water present in the borehole. To calculate the volume of water inside the borehole, we first inserted a sensor linked to a tape measure.

Figure : Tape measure with sensor

We found that the water was 2.82 meters below the entrance to the borehole tube. Using the borehole information given above, we were able to calculate the height of water in the borehole tube :

Water level in the pipe = 102.67-94.67-2.82 = 5.18  meters

Knowing the height of the water and the diameter of the 52 mm tube, we calculated the volume :

Volume=π*(0.052/2)^2*5.18=0.011000 m^3

The volume is approximately 11 liters. We then calculated the approximate flow rate of the pump.

Figure : Flow rate of the pump calculations

Pump flow rate is approximately 6.2 liters per minute.

Using the volume and flow rate of the pump, we calculated the time required to empty the pipe. So, we knew we had to wait about 1 minute and 45 seconds for the pipe to empty completely. We drained the tube 3 times to ensure better water quality.

Figure : Color of the water for the first pumping

Then we took the sample that we'll be using in the laboratory next week.

We didn't have time to take the conductivity, pH, oxygenation and temperature measurements, but the next group took them for us. Many thanks to them.

The results for these measurements are as follows:

• Conductivity 130 uS/cm
• Oxygen 5.38 mg/l
• pH 7,17
• Temperature 6,2 Celsius