This project consists of a new pump station within Rossmoor Retarding Basin. The pump station was constructed such that incoming flows into the basin upstream of the Rossmoor Storm Channel are pumped to the San Gabriel River. Two local storm drains which currently drain into Rossmoor Retarding Basin were extended to outlet into C01 downstream of Rossmoor Retarding Basin.
Although design will be of the entire pump station, construction is expected to be in two phases. Phase I consists of the ultimate pump house and discharge lines and installation of one-half the required pumps and engines. Three of the existing five weir structures will be removed in Phase I and flows not being pumped will continue to flow downstream via Los Alamitos Channel (C01) to the Los Alamitos Basin (C01B01).
The remaining pumps and engines, removal of the remaining two weir structures, and construction of a dam and spillway at the downstream end of Rossmoor Basin will be in a future Phase II. Also in Phase II, approximately 2000 LF of pipe conduit to divert Bostonian and Piedmont Storm Drains downstream of the Rossmoor Basin will be constructed. Re-grading of Rossmoor Basin will be needed to drain flows to the new pump station and approximately 700 feet of the eastern bank of Rossmoor Retarding Basin will need to be raised to provide freeboard.