Existing Conditions

Although the air quality in the city leaves something to be desired, conditions improve mightily in the bush. Daily temperatures have been topping out below 90 on most days, and the humidity is tolerable, provided you never get more than a few feet from a bottle of water. The real challenge is the vertical. Although we’re only 50 feet above sea level on the floor of the power house, we need to go down two and three levels to get to the locations we’re trying to measure, and then back up again, a score or more times in a day. From the floor of the power house to the top of the intakes is about 70 feet, and then down another 100 feet to the water, scrambling down course embankments and even courser rock… then back again… and again.


The other day, I accompanied our two dirt and rock guys to the main spillway to assess conditions on that side of the current rivercourse. We made multiple trips down to the embankment toe and back up again, looking for scour holes and other signs of erosion. Throughout the excursion, we were accompanied by anywhere from three to six local men, who may have been contracted to assist us, but could just as easily had nothing better to do than watch the white guys poke at rocks.

As we moved about, we conferred and consulted, and eventually walked down to the forebay canal to ascertain what might have happened when the impoundment drained through it all at once. There was even more severe scrambling there, as the flows had removed all of the smooth surfaces from the old channel, scouring it down to clumps of the hardest rock. It’s beautiful, really, from a post-disaster mindset, but required a huge amount of climbing, all with light packs full of tools and water, lots and lots of water.

Trying to find the forebay canal was a little confusing, as the only consultant in our little group was there only once nearly twenty years ago, and the bush tends to change the looks of trails and buildings in a short amount of time. Fortunately, Liberians are a very friendly and helpful people, and an elder from the tiny village where we were stymied immediately volunteered to show us the trail to the canal, the same trail used nearly twenty years ago. When we got to the bottom, I figured that he’d head back home, but was mistaken. He kept with us throughout our conferring and consulting, and then showed us the shortcut back to the main dam.

Ultimately, it was a shorter route, but first involved heading directly away from our destination, and further downstream along the rocky and broken shore of the canal. There, our tiny group, changed shape, as our earlier group of hangers on crossed the river at the shallows and went home, but we and our elder were joined by a few more returning to their village after doing their laundry on the rocks. One of these was a girl, still a teenager, with a three month old strapped to her back and a basket of clothes balanced on her head. She led us to the shore where we headed up an almost vertical trail to the top of the bank forty feet above, where a relatively flat trail led us back to the van.

Before, after, and simultaneous to this event, we’ve been working to measure the roundness and plumb of the turbine pits. This is one of our primary tasks, and one we’ve been working on since our arrival. You see (or perhaps you don’t, because you aren’t here), there is an apparent gap between the powerhouse structures of Unit Three and Unit Four, a gap that doesn’t appear at any of the other interfaces. If the gap was caused by the great flood event, and has somehow tilted the powerhouse and turbine pit, then retrofitting Unit Four will become exceedingly difficult. By taking the appropriate measurements, we can ascertain if the turbine pit is still a true vertical cylinder. We’re hoping so, but need to make sure.

To do so, we turned carpenter, turning a big pile of hand milled 2x8’s and 1x4’s into a working platform twenty feet below the powerhouse floor founded on what’s left of the wicket gate spindles and operators. Then we built a second platform ten feet below the first, balanced on the unsalvaged vanes at the bottom of the gates. A couple of feet below that is water. There’re large holes in the center of each platform so that we can run a 20 pound plumb bob to just above the water, suspended on thin piano wire from a simple bridge we use to span the upper rim of the turbine pit. To dampen the movement of the plumb bob, we’ve suspended it in a flimsy galvanized bucket full of motor oil, which is tied to a couple of points on the pit walls. It took a day and a half to build the first one, but we should get all four finished within the five days we have before our turbine guy bugs out.

Of course, we don’t do any of this by ourselves. Our typical powerhouse crew is close to a dozen, with two or three local carpenters mixed into the labor. Over 150 were used to clear the vegetation from the main dam embankment prior to inspection. There’re usually a few more accompanying the geo-scientists as they poke around the rocks nearby. And we have our drivers, of course, and Liberian Electricity Corporation security personnel. It’s quite the entourage.

The first day we were working on site, we were also visited by another hundred locals, who would move up to the hole in groups and watch and comment for a time. It’s obvious that we’re working in the powerhouse, but it’s not clear at all why we would be cutting and assembling all of this lumber in a dank concrete pit. I think it helps, though, for at least the labor to know what we’re trying to do, so in my best Pigeon English, I simplify.

Ultimately, when we’ve centered the plumb bob, it should run down the axis of a vertical cylinder (the turbine pit). Measurements from the wire to the walls at various elevations will let us know if the pit is still true and round. If not, adding a turbine to Unit Four will be more difficult.

But I’m okay with more difficult, as long as I can enjoy the view.