Canon Boulevard Steep Hillside Grading

We took over this grading plan from another civil engineer. The goal was to redesign the grading and drainage to be as cost-effective as possible while meeting LA County requirements. This is a large 1.46-acre lot near the base of the San Gabriel Mountains with steep topography that required careful analysis.

The existing site had a lot of concrete around it. Some of this the new project could connect into, but other areas needed to be removed and regraded. The original drainage pattern used the driveway to sheet flow stormwater to the street. Our approach was to maintain this pattern where possible and use the existing concrete to our advantage.

The hillside on the north side is complex. To keep things simple, we placed new retaining walls with 2-foot wide swales to collect drainage coming down from the upper mountain. These swales drain into catch basins that connect by pipe to the deck, where area drains collect everything. From there, water gravity-flows down to the front. We tried to minimize piping as much as possible. On the south side, we extended the existing house footprint slightly to create a walkway with sheet flow down to the driveway, matching the pre-fire drainage pattern exactly.