Philippines

Here is a brief article I wrote for our company newsletter…

I hadn’t travelled to the Philippines before so when the opportunity arose for Kate Mackay and I to give John Grimston and Robin Dawson a hand with some dam safety evaluations for a few weeks I was quite excited. It proved to be a great experience culturally and since the dams we were inspecting are some of the highest rock fill dams of their time, the water engineer in me was constantly inspired.

We stayed in Manila for the weekends and during the week travelled out to the dam sites, roughly 200km north of Manila. Crazy driving and crazier traffic meant some blurry photos of the scenery, but the Filipino countryside is beautiful and very green (even coming from NZ).

In the first week we visited the Ambuklao and Binga dams which form part of a cascade down the Agno River near the city of Baguio. These were impressive dams; both rock fill and over 100m in height, set against amazing backdrops in narrow valleys, although in both cases the structures themselves had not been maintained quite so well. The inspections in hot weather, the frustrating search for documentation and the personalities we encountered made the work quite an experience.

On the third day it fell to me to do some of the reservoir inspections which made for a great day outside. We made record time getting to site over the winding road dropping 900m from Baguio where we were staying into the Agno river valley shaving half an hour off the 1.5 hour journey. We surveyed the Ambuklao reservoir in a powerboat observing the large sections of hillside that had dislodged during the Baguio earthquake in1990. The Ambuklao Dam power inlet is covered by 10m of sediment that was mobilised by the earthquake and along with 40m of water on top of that, it proved too difficult for the last contractor. At present the scheme just spills water.

We jumped back in our van for a journey over even worse and unsealed roads to the Binga reservoir where there was no powerboat in sight. Instead, for 600 pesos (NZ$20) we hired a few local fishermen and paddled their outrigger canoes the 3km or so to the head of the lake. The level of sedimentation in these reservoirs was remarkable and rounding a bend that should have been only half way to the top of the reservoir we encountered the sediment fan slowly advancing, eating up the reservoir volume. Total sedimentation is projected to take only another ten years at which point the schemes are likely to become run of river.

The second day of inspections found Robin Dawson and I at the Binga Dam ready to inspect the spillway galleries. No, there were no galleries through this dam, we were informed by the dam manager after an hour of driving. After a bit of asking around, fortunately a gallery was ‘found’ thanks to the maintenance contractor. The entrance was in the centre of the spillway road and covered with a deep steel cover that had to have weighed a ton and obviously hadn’t been opened for years. No way of removing the cover presented itself but eventually a ute was sent for ‘strong men’ from the power station down the road. The ute returned full and after gathering up some steel bars we headed up to tackle the gallery. The strong men heaved away while the international consultants, well, consulted. Finally we made some progress and cracked the lid open to reveal the gallery shaft dropping deep underneath the spillway. We discovered another opening that provided ventilation and the following inspection didn’t show anything out of the ordinary except some rather large stalagmites forming as the calcium leached from the concrete joints.

The next week we travelled to the Pantabangan Dam scheme where we were scheduled to inspect the two main dams and a regulating dam downstream. Two other small dams (Canili and Daiyo Dams) were added to the schedule by the client at the last minute and after an unsuccessful search for any documentation covering them, we found ourselves travelling out find them.

The winding road took us through some beautiful countryside, complete with rice and banana plantations and the Pantabangan Township relocated to make way for the Pantabangan Dam Reservoir. After an hour or so of travel we arrived to find that the small dams were only small in comparison to the main dam. The dams were 72 m and 64 m high and heavily overgrown. We carried out the inspections were in the sweltering heat to the disbelief of the group playing a casual game of chess and sitting around in the shade by the road that traversed the dams. We stopped for a drink, watched the game and were joined by local checkpoint guard complete with automatic rifle and keen on a game. After questioning the caretaker who was accompanying us we discovered that his father in law, the previous caretaker was one of those involved in the construction and still lived just around the corner. It turned out that he had even kept a few souvenir documents he was kind enough to let us borrow – some of the only original documents we managed to source.

The dams turned out to be part of a trans-basin diversion scheme built in the 70s to divert water through a saddle and into the main reservoir. Both dams seemed to be doing the job but badly in need of maintenance.

Inspecting the remainder of the dams took us till midday the next day. At times the only way to inspect a spillway or dam toe was by machete while on the watch for ‘deadly’ insects or the huge pythons we were constantly warned of.

After the inspections we headed back to the Manila office to begin pulling it all together. It was great to be able to work alongside some of our Filipino colleagues and we were grateful to be introduced to such a diverse and fascinating country.

Other highlights during our stay included: Open air banquets of local fish raised in dam reservoirs, riding Jeepnees, eating balut (fertilized duck egg), Volcanos, SM malls and Manila traffic jams. The last I would not recommend but if balut doesn’t get you on a plane, don’t worry, the rest of the food is exceptional as well.

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