R 281.836 Trench excavation.

Rule 26. (1) All pipe trenches shall be excavated to a depth which will provide a minimum cover of 30 inches from the bed of the stream to the top of the pipe. This minimum cover shall control except where special conditions at certain water crossings may warrant a lesser or greater depth of cover. (2) Appropriate trench excavation methods shall be employed to minimize material from the pipe trench flowing into the stream, giving due consideration to the soil, terrain, cover, side slopes and weather conditions involved. (3) The pipe trench excavation shall stop some distance from the stream to leave a protective plug of 10 to 20 feet of unexcavated material at each bank. The plugs shall be left in place until the pipe-laying operation across the stream has begun. Bypassing of water in the trench to the side by diversion ditches or by pumping may be required at certain water crossings. (4) The trench in the stream bed may be backfilled if the material used does not cause excessive siltation. Stone, coarse aggregate or washed gravel shall be used where backfill is required and where use of existing material will cause excessive siltation. (5) Pumping or draining from trench excavations shall be made on either side of the pipeline and not into the waters of the state. The owner shall secure the necessary approval of private landowners before discharging water from the trench excavation onto private lands.