Line A will consist of two segments; an underground storm drain segment, and an open channel segment.
Two 36 inch diameter corrugated steel pipe (CPS) culverts convey the flow tributary to Line A under the Freeway.
From the culvert outlets on the west side of the Freeway, the flow will be conveyed in an existing low to the intersection of Lakeview Terrace and Sylvester Road.
Neighbors have taken to directing downhill flow with their own form of rip-rap.
At this point, inlets provided on the upstream side of Lakeview Terrace will allow the 10 year flow of 50 cubic feet per second (CFS) to enter Line A while at the same time forcing the balance of the 100 year flow to cross Lakeview Terrace to be conveyed in Sylvester Road. The reach of Line A between Lakeview Terrace and Mission Trail will be a 24 inch diameter reinforced concrete pipe (RCP) located in Sylvester Road.
Just upstream of Mission Trail, catch basins will be provided to pick up the remainder of the 100 year flow and the storm drain size will increase to a 33 inch diameter.
(No catch basins can be found near the intersection of Sylvester Road and Mission Trail)
Near Malaga Road is the only catch basin picking up the sheet flow coming downhill.
The open channel portion of Line A will be a concrete lined, trapezoidal channel. It will serve as the outlet for the underground portion of the Line, extending from just downstream of Mission Trail to the 1260 foot elevation where it will daylight. The 100 year peak flow of 95 cfs will be conveyed in a trapezoidal channel section having a 3 foot bottom, 2.5 feet deep.