Wednesday, December 24, 2008

Strange Geology

I honestly cannot figure the watershed surrounding our property out. The wet-weather spring and watershed have been flowing non-stop since December 12th (though the rate of flow has diminished). The strange thing is trying to answer the question of how a day of rain prior to the 12th can result in that much continuous water flow since. From where is this water coming? We have had prior rains that seemed comparable, and the watershed and spring did not respond in the same manner. It really has me baffled.

Before starting the pond project I ordered a soil survey for this county. It mapped out soil compositions pretty good and has elevation maps. It is written so that laymen like myself can get an idea of what is going on.

My best theory is that the Weikert shale is uniformly present across the watershed (which the survey supports), regardless the depth of silt, clay, or soil above it. This shale is largely impermeable--something the locals call "black shale" (i.e., it turns black over time when water sits on top of it). There must be a tipping point for soil moisture saturation in the soil above this shale, and once it is reached, the water flows until the whole thing drains. That also explains why previous rains were not resulting in any activity, and then all of a sudden it let go and has continued for two weeks straight. That is the best I can make of it anyway.

While it did result in a full pond, the down side is that I have not been able to do any more work on the second pond excavation during Christmas break. I had hoped to finish it during this time. Oh well. I learned long ago that with this type of project it is best not to get attached to a definite time schedule since the weather has the final say. Otherwise a fun and enjoyable project becomes stressful--the exact opposite of the entire point in doing it.

The full pond, however, looks good and continues to flow the incoming water right back out:

The excavation-in-process of the second pond is full of water that will need to be pumped out before I resume work. Once the water stops flowing, I am debating whether to buy a 1/3 hp electric utility pump (as I may have more occasions for pumping it before I am done), or just renting it this one time. They are $80-$100 depending on which model. Either way, I will probably need to run it off an inverter from the truck, which should be able to handle it (ca. 10 amps).

I will report on more progress as soon as this bizarre watershed stops flowing water.

On a different note, we recently had a large flock of turkeys come through. It was the largest group I have seen to date--I counted 20 in all. Anyway, they entered our property at the base of the pond dam, came across the side hill, and then flew across the road. I was a little surprised that almost all of them decided it was best to fly instead of walk across the road. I imagine that somewhere in their bird consciousness is this image of colleagues exploding in a burst of feathers under similar circumstances:

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