Project Name: CBWCD Spillway Replacement

Location: Montclair CA, North and South sides of Moreno Street

Job Type: Civil Demo, Grading, Drainpipes, Concrete


The old spillway had deteriorated with age and several areas behind the spillway that had formed hollow voids due to water seepage through the soil under the street when Basin 2 would fill up with stormwater. The scope was to tear out the old concrete, grade per the new plan, install an under-slab drainage system, and construct a new spillway and inlet structures. As part of the corrective measures, holes were cored through the floor of the culvert connecting the two structures to explore the soil for signs of voids, seepage, erosion, etc. No voids were found. E&E offered an option to excavate and recompact a cutoff trench in the top section of Basin 2 running east to west, parallel and below Moreno Street, spanning the entire width of the Basin.  



The soil was extremely rocky making it very difficult to  grade.  The cut/shaped sections under the spillway which were required to contain the drainage system, would fall apart when dry, not holding the required cut shapes needed for the drainpipes. It created many trip hazards which complicated the hand/fine grading, and installation of concrete forms and rebar reinforcement. The trenches needed to be cleaned out daily to maintain the required separation between rebar, concrete forms, drainage pipe and soil.


Working on a long, steep slope (with much of the project being completed during a heatwave in a wind-protected basin) presented significant physical challenges to the crews. With careful review, planning and implementation of various controls, including giving special attention to High Heat Procedures, E&E was able to complete the project safely and to the client’s expectations.

(714) 897-8705