And now, the real test...
We just got significant spring rains over the past week. I think I can safely say that we are onto something here. The pins worked great. They held back the leaves and sticks as planned. What I didn't plan on is the erosion wear.
This test area is a pit scooped out by the backhoe to create an inflow sump. We did this because the outflow side is a couple feet lower as the culvert runs for 40' under my driveway. We dropped the culvert this low as a compromise and trade-off to get it low enough to function correctly, maintain a consistent driveway grade, and avoid a gazillion tons of rock to build up the road bed. So, the only drawback to the culvert installation design was the need to create this inflow sump; not really a biggie. You can see the run-off as it enters from the top of the pic.
2 of the U-shaped pins fell over into the pit when the soil saturated and eroded. For the record, about 12 - 18" of the pins was pounded into the soil, so it probably didn't take much to push them over into the pit. I would say, tho, that this method of containing tree crap has merit. Nope, it ain't the eco-friendly piles of unsightly brush that Dave promotes, but I expect over time that they would probably start a pile of their own.
I'm thinkin' that the next step would be to widen this sump pit slightly and lining it with rocks...then pound in the pins. Whaddayathink?
