I have four culverts on the property. Two of them I have installed - actually I replaced two older original culverts (one that clogged up and one that washed out). They are all fine right now but I see that there is some dirt and such building up in two of them - a 15 inch one and an 18 inch one and both about 20 feet long. I estimate the build up on the bottoms are about 10-20 percent. I don't want it to get worse. What I have done in terms of preventing problems in advance, at least somewhat, is to pile up large rocks/boulders a bit away from the intake side to catch some of the dirt and debris first - much easier to clean stuff out there than in a culvert. It is almost all just dirt that collects in the culverts. Anyway, not having any really good ideas, after the next rain I am thinking of fishing a rope through (using long pvc pipes joined together) and once that is done, attaching a rake like device (think grapling hook like) and weighting that down and dragging it out and repeating to loosen things up. Plus, I can get into both ends a bit with shovels and such to also loosen things up.
It is not a big deal now, and the culverts have been in place for at least ten years, so the problem is gradual. Anyway, whenever I have a dumb idea, I post here seeking better ideas. And I remind my wife that sometimes my dumb ideas have worked. She doesn't remember those as well as those that didn't work quite so well. Suggestions?