Major Improvement to the Hydroelectric System

A couple weeks ago we had a (literal) gully washer of a storm that dumped several inches of rain in the holler in just a few hours at most (local reports are ~5 inches in five hours, we were in Maryland at the time).  The evidence of the wall of water flowing down the gully was impressive; walking up the creek I could see disturbances six or eight feet(!) above the normal water height.  Sure enough, that much water flowing down the gully wreaked havoc on my hydro system, tearing apart both my dam and the water line itself without permanent damage as the line is designed to come apart, and the rock dam was just a pile of rocks combined with an EPDM membrane.  The dam was completely breached and needed rebuilding.  I decided to take the opportunity of the re-build to install some improvements I have been contemplating since last year.

When I first installed the system many years ago I built a coffer dam a couple hundred feet further up the hill but eventually abandoned that section of pipeline as it was a maintenance nightmare for not many more feet worth of “head” (the height of the waterfall from intake to hydroturbine).  But, my original design for the actual intake configuration worked exceedingly well.  The ten-inch tube was large enough to avoid blockage except in the most extreme conditions, and the screened capturing basin was situated such that the water was wicked down into the tub and the debris washed right on by.

When I relocated the intake to a narrower passage down the creek I changed the intake configuration which worked well enough, but still not as good as the original one.  This one was a screened submerged pipe which had the tendency to clog, requiring a trek a quarter mile up the hill to clean off.  I took advantage of this latest repair episode to make a new intake more similar to the first one which as virtually maintenance-free with (hopefully) nary a clogged nozzle at the business end.

The new unit was a snap to make as I built and installed a “weir” intake, basically a pressure-treated board with a notch and short sluice to steer the water into a screened tub, with the penstock (the pipeline) hooked up to a capturing tub via a shower drain fitting.  Rather than going to the boatload of effort necessary to make the weir water-tight I simply attached a sheet of EPDM rubber to the weir and draped it into the channel I scooped above the dam.  The membrane-lined basin now captures and steers almost 100% of the water to where I want it to go.

To reduce(?) the risk of further storm damage I filled the new basin with rocks, hopefully it will steer any flood-like waters above the weir.  If not, I’ll just track down all the parts downstream and reassemble them.  It only took a couple hours for this assembly.

This was the really easy part of the day’s work.  As I reassembled the penstock descending down the hill I learned that there was a mud impaction somewhere in the line.  Finding the blockage and removing that took way more time than rebuilding the dam,  But finally it was done and the hydroturbine was humming along.

I’m even contemplating putting some electrical heat tape on the nozzle/plumbing at the bottom next to the turbine to see if I can extend the working season for the system.