Walnut Grove Pump Station Abandonment Project

Walnut Grove Pump Station Abandonment Project

A new 16-inch gravity pipeline would follow the route of the existing 8-inch force main. The new pipeline would begin at Pump Station S064 and continue southeast along the southern boundary of the school property for approx. 1,270 feet. The pipeline would then turn to the northeast for approx. 190 feet and then turn to southeast again and travel approx. 500 feet along the adjacent agricultural land until reaching Pump Station S146. The gravity pipeline would outfall into the influent manhole at Pump Station S146. The total length of the new pipeline would be approx. 2,000 feet, with manholes placed no more than 500 feet apart. Vegetation within the easement footprint would be removed. Open cut trenching would be used for installation of new pipeline. With this construction method, equipment would be used to excavate a trench in which the pipe would be laid. The depth of the pipeline would range from 8 to 15 feet below grade to maintain the needed gravity flow. Portions of the trench would be excavated below groundwater levels, and dewatering of those portions of the trench would be required during construction. The trench base usually requires reinforcement such as sand or gravel and would be required during construction. The trench base usually requires reinforcement such as sand or gravel and would be checked for proper slope alignment. The pipeline would then be placed in the open trench and the trench would be backfilled with material such as Class 2 aggregate base to cover the pipe. The existing 8 inch force main has a 15-foot easement, and the new pipeline would be located within the existing easement to minimize the amount of additional easement required. Due to the proximity of the existing 8 inch force main to the drainage ditch additional easement would be required. The existing 8-inch force main would be abandoned in place. Bypass pumping would be needed to maintain flows during construction.

Sacramento