The proposed method of repair was bentonite injection. Bentonite is a material with very unique properties. It is a naturally occurring material found in the earth - a clay - which can swell up to 16x its original size when it comes in contact with water. This property makes it a useful material for sealing leaks, waterproofing buildings, and many other applications where water flow needs to be stopped.
While bentonite would help us fix the leak, we had a minor problem to overcome - where could it be purchased in Cambodia? We soon found out - nowhere! So, we looked to our closest geographic neighbors - Thailand and Vietnam. Through a material supplier located in Siem Reap, we were able to make a purchase from a Thai supplier. After the purchase, two weeks later, the bags of bentonite powder were delivered to HT's office.
Center: Things get real! Dirty, that is
Right: The setup - Filtering water, the mixing barrel, pumps and hoses
With the fluid slurry mixed, we started pumping by inserting a length of typical 1.5" diameter flexible hose as far into the inflow point as possible. Things were going well - messy, wet, dirty, but so far so good.
To finish the repair, a layer of bentonite powder was spread over a 3-meter long strip, covering the three inflow points. This area was then backfilled with clay and protected with a layer of rip rap.
The downstream area has been dry since the bentonite was injected. The real test will be the upcoming rainy season, which will start in May/June. We'll keep you posted!