There is an aqueduct from the 1800s which runs through our property. Over time, land use changes resulted in a road across the aqueduct. The road is actually an easement through the north end of our property. So, there’s a culvert under the road (thankfully, aluminum — if it had been steel it would have rusted and collapsed by now). Culverts are notorious for leaking around the entrance. Water has a way of finding holes and making them bigger.
For the past six years, we have watched half the water coming through the aqueduct return to the creek before it goes into the culvert under the road.
A little excavation today (or a lot — shoveled by hand) revealed the problem.
Someone had put concrete at the entrance, but didn’t bother to do it properly. So, the water was basically running under the concrete. About half was going away before entering the culvert.
The culvert on the right is an overflow/discharge culvert that we leave open in the winter and shut in the spring. The culvert on the left is the aqueduct conveyance.
The picture on the right is after adding two, 80lb bags of concrete mix and properly “keying” the concrete in. A key is a small trench filled with concrete (sort of like a foundation) under the concrete. This “key” makes it harder for the water to just run under the edge of the concrete.
When people make dams, they also “key” the dam into the soil so water doesn’t just start running under the dam and wash it away. Anyone who builds a dam without a key is creating a big, future problem.