1, polyethylene pipe laying under the ditch, should immediately ver with fine soil or sand pipe, the thickness of not less than 30cm, to ensure that the polyethylene tube from external damage. 2, trench backfill, should first fill the bottom of the tube, and then backfill both sides of the pipeline, and then back to the top of the tube to the top 50 cm, such as ditch water, must line up after the backfill. 3, the support of the groove should ensure that the nstruction of the security