Stormwater Engineering Projects

Picture of Live Oak Spreading Grounds


The project was re-advertised for construction on March 29, 2016. Following bid opening on May 3, 2016, the Board of Supervisors awarded the project to Environmental Construction Inc. on June 21, 2016. Construction is anticipated to begin in late summer 2016.


The purpose of the proposed improvements is to optimize groundwater recharge at Walnut Creek Spreading Basin (Spreading Basin) by restoring the percolation rate in the Spreading Basin. This project includes sediment removal within the Spreading Basin, construction of a pump station and pipeline, and upgrades to the existing gage boards.

Over the years, fine sediment containing silts and clays have built up in the Spreading Basin, which inhibits groundwater recharge. This project will remove approximately 7,000 cubic yards of sediment buildup from the Spreading Basin to be hauled and disposed of at Manning Sediment Placement Site in the City of Irwindale. A pump station, consisting of two pumps (each with a capacity of 10 cubic feet per second), a 112-foot long ductile iron pipeline and 30-foot long reinforced concrete pipeline will also be constructed to allow conveyance of water to be delivered to downstream spreading ground facilities with higher percolation rates and greater recharge capacities and to facilitate maintenance of the spreading basin. The existing gage boards will be replaced and supplemented with a data logger and pressure transducer. The pressure transducer and logger system will enhance operations within the Spreading Basin by providing more accurate water level readings.

This project is partially funded by a State Proposition 84 grant through IRWMP, and supported by the San Gabriel Valley Council of Governments.



For more information on the project please contact

Updated on: 07/24/2014