Because the existing drain pipes at the Dos Amigos Pumping Plant siphon house are causing ongoing erosion, the Department of Water Resources’ San Luis Field Division will connect six 4-inch diameter corrugated plastic drain lines to the existing drain pipes. Before installing the drain lines, brush and weeds will be removed and six trenches, up to 1.5 feet wide and up to 2 feet deep, will be dug. Four of the trenches will be on the north side of the siphon house, and two will be on the south side.
After the brush and weeds are cleared, the four drain lines will require excavation of a small, approximately 2-foot square and 2-feet deep basin about 200 feet north of the siphon house. The basin will be lined with 4- to 12-inch diameter rock. Once the basin is constructed, the four drain lines will be installed in the trenches and will be buried. Flows from the four drain lines will discharge into the basin; a 10-inch diameter pipe will be connected to the downstream side of the basin allowing the drain flows to discharge into an existing drainage ditch located along Pole Line Road. Four to 12-inch diameter rock may be placed in the ditch at the point where the 10-inch pipe flows into it.
The remaining two lines connected on the south side of the siphon house will be placed in the trenches and buried. These lines will discharge approximately 140 feet south of the siphon house where existing outlets are located.
All trenched areas will be backfilled and compacted to the original elevation and contours.