Slug test on pilot recharge wells at Ferns Residency

Ferns residency near Konathur is layout spread over 30 acres. This layout is divided into 250 plots, out of which 110 plots are built up. This layout does not have BWSSB connection and hence they are presently using water from bore well or tanker. As few bore wells are already dried up, there is strong need of recharge of the same. Hence this project of recharge wells has been undertaken. In which around 50-60 recharge well will be dug which will help in return to recharge the aquifer and thereby assures the continuous water yield through bore well. Similarly every household has rain water harvesting, which is another source of water to them.

To first understand the behavior of soil as how water is percolating through soil and recharging aquifer, slug test is conducted on three pilot wells (newly constructed) and one on old well. The location of pilot wells is decided on majorly two factors, first being the entire area of layout must be covered and other it is possible if the location of recharge well is near the bore well, as this will help to understand the behavior of recharge on bore well. BIOME team gathered at the club house of Ferns residency along with manager of the residency at around 9. Around 9.30 we head out to test our first pilot recharge well in layout. Uma mam explained, what and how we have to record the readings. We were team of five along with manger and his team. We started the test around 9.45. First diameter and depth of the well is recorded.

First diameter and depth of the well is recorded. Diameter is standard that is around 3 feet, where depth is varying from 19 ft to 20 ft. 

Measuring the depth of the well 

After recording the diameter, the tanker water is emptied in the well and time to fill the well is recorded.

Filling up recharge well with tanker water 

It is observed that, in the start, the water is percolating through soil, the water level is not rising. The total time taken by the first well to empty tanker is around 9 and half minutes. The time would be dependent on soil saturation and porosity of soil. Now once well has filled, the water level is recorded. Stop watch has started to measure the water level at various time intervals. Reading have been recorded at every minute for 10 minutes and then after 15 min and then on hour level. Few readings we have to do on next day. The same procedure we have done for all remaining recharge wells. We have divided the wells among us to assure the readings are taken at proper interval.

Measuring the water level at various interval 

Water level after few hours

Now, to kill the time in between the readings, we have one found bore well near first recharge well. So Aditi put the stone in it and record the time and sound, to understand the water is there or not and what will the depth. Time taken roughly around 3 sec to reach the bottom and echo of water splashing has heard. As per assumption, the bore well depth would be around 30 m. 

  

  Bore well near first recharge well 

The jelly which is put around the recharge well, started collapsing. The reason would being, soil below is getting saturated and settling. But since this was the first time, such event is recorded and would be analysed to avoid any such further cases.

Jelly around the recharge well has collapsed 

By 

Kavina, Kruthika, Milan, Shimoli, Surabhi