In search for a more stable and consistent supply of water, we have to look for a second source of water. Fortunately, we found one at an even higher elevation but double the distance. The first dam has been holding up well, but in view of the current dry season, supply from the dam has been intermittent. On some days, there has been zero supply of water altogether, proving this dam unreliable. Since water is essential for growing new plants especially at the early stage and my plans are to stock up 3 ponds, there could never ever be too much water.
The location of this second dam we’re building in partnership with Soilogy lies at the very same oil palm plantation which housed the first dam, but at a more secluded site. It’s a long stretch of creek at a gulley walled in by two steep slopes on either side. The entire sheltered area, rich in vegetation looks like a very good water catchment bowl.
A steep drop made naturally possible by a large boulder served as the rear wall of the dam. From this point onwards, the creek stretches another estimated 25-30 feet before the front dam wall is sited. This is also where the choke point (narrowest part of the creek) is located so as to facilitate the blocking of water which would cause water levels to rise in the dam. It’s imperative to expend as little energy and resources as possible in any construction project especially when it’s this remote. Hence, we have to ensure the wall is the smallest stretch possible without compromising its strength.
Contrary to the first dam’s filters designed and put in place just within 5 meters before the main holding pool, the filters for this current dam are situated more than 12-15 meters (or more) away from the rear dam wall. The geographical layout of the land naturally prevents large volume of silt from entering the main holding pool. This is crucial. Since this dam is more remote, maintenance can be carried out a little more infrequently. And when we do remove the built-up of silt, such maintenance works may prove to yield even more long-term results, before another clearance is required.
We tried to use natural materials as much as possible. That means no cement or gravel trucked in. Instead, we used rocks picked up from the creek bed and surrounding areas. Removal of rocks in the main holding pool also helps increase the volume of water being held. These rocks of various sizes are laid into place in an interlocking fashion and sealed with clay or soil taken from the surrounding area. They are then padded down tightly before stacking more rocks over them. Perhaps the only non-natural materials used are guny sacks (for water proofing) and 4″ PVC pipes (drainage and overflow channels).
The soil shouldn’t be too damp so that compaction can occur naturally once they’re applied in between the cracks. The front wall made up of rocks and compacted earth as sealer is at least 5 feet thick. As the wall rises in height, the relevant pipes are embedded accordingly: drainage pipe (to drain out the silt) first, then 3/4″ poly pipe (intake pipe, subsequently reduced to 1/2″ downstream), followed by three 4″ PVC overflow pipes to drain excess water. The intake pipe has to be above the drainage pipe to keep it up and away from being stuck with mud from the creek’s bed.
To further seal the inner dam wall, a layer of guny sacks are laid on the inside of the front wall, onto the rock surface. A layer of clay is then applied as the final finishing seal which would be stamped down by feet. This water proofing measure is essential to ensure maximum water holding capability of the dam.
Initial tests reveal a very good flow rate and performance from this dam. The front wall’s height will be raised by another 1-1.5 feet. Just outside the front wall, a feet of earth will be poured in to seal the rocks; this layer of earth would be held in place by a line of earth-filled guny sacks.
