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S MN | About 10-11' fall to the road crossing, then about 1' to creek outlet- so gets pretty flat. The waterline was installed at 4' depth surprisingly (in MN) directly overtop of original old clay . We elected to have them lower it when we installed the 15", which was meant to supplement the old clay- was the only outlet for about 170 acres. (rerouted a lot of water into the new main- but still need both. The fall comes downstream of a 50 acre perfectly flat area at the top end) Going under may be an option when replacing old main, but was not an option when new main was installed 50' west of it. Waterline exactly where the 15" needed to be.
Catch basins allow backed up water to blow out and cross road through culvert. This hasn't been as much of an occurrence since the addition of the additional main. Outlet really needs to be at or below water level, or we lose cover. In the flat stretch to the creek there is maybe 2' of cover at most on the old clay, hence a lot of suckholes. I was thinking 10" dualwall due to the new main carrying a lot of the original water the clay was carrying, but probably best like you suggested to start with 12" and step down to 10" and 8" as we get toward the top end. About a 3/8 mile run to the road.
Basically, the new main is carrying much of the water from the west side of a quarter and a bit (25 acres) from the quarter to the north. Old main now maybe 70 acres - about a 15 acre sidehill seep on there that is not tiled currently, but will do with new main install. Thanks for your input. I had this idea that we could Y on both sides of the road to save a road bore/watermain issue- but probably not a good idea. Should've bored larger under the road earlier with new main, but hindsight now. | |
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Drainage experts ... Venturi Effect?
