Pacific Palisades Fire Rebuild: Basement, Pool, and Sump Pump on Chapala Drive

We recently wrapped up a fire rebuild on Chapala Drive in Pacific Palisades with basement-level lightwells and a pool. The pre-fire house had been excavated into the slope with drainage patterns that flowed from NorthWest to SouthEast across the property. The previous driveway apron’s southwest side was being closed as part of the new development.

This was a corner lot, which meant tighter constraints on driveway placement and drainage routing.

Existing Conditions

The existing 3D model shows what we were working with. The pre-fire house was set into the slope, which meant the drainage patterns had been established around that configuration. On a corner lot, you typically have two street frontages, which gives you more options for access but also more constraints on where you can put driveways and how you handle drainage outlets.

The existing driveway was on the southwest side of the property. That would be closed as part of the new work.

The Project Requirements

The new house would have a basement with two stories above. There was a proposed pool. The garage sat on the northeast side of the property with a relocated driveway apron.

The lot was somewhat flat, with only about 2 feet of drop from rear to front. That is not much slope to work with, especially when you have basement lightwells and a sunken pool cover that need to be below the street flowline grade.

When basement lightwells and sunken pool covers are below the street flowline, you cannot gravity drain them. That is when you need a pump.

How We Handled the Drainage

The basement lightwells and the sunken pool cover required a stormwater sump pump. We designed the pump system and provided the calculations for it.

For the rest of the site, the drainage was handled by downspouts collecting roof runoff into underground pipes. From there, sheet flow was directed to area drains that all connected to a catch basin on the southeast side of the property. The catch basin gravity flows under the sidewalk and out to the curbface on Chapala Drive.

No pump needed for the main site drainage. Only for the lightwells and pool cover that sit below the flowline.

Services Provided

This corner lot project with a basement and pool required:

• Grading plan — worked with the 2-foot slope drop while accommodating lightwells that extended below street grade
• Excavation plan — mass excavation for basement with 2 stories above, plus pool and lightwell locations
• Erosion control plan — standard for LA hillside construction
• Stormwater sump pump design and calculations — required because the basement lightwells and sunken pool cover sit below the street flowline and cannot gravity drain

Plan Check Timeline

This was not a like-for-like rebuild. The new house was substantially different from what existed before, which meant it required a full plan check rather than the streamlined ministerial review that applies to like-for-like replacements.

The first plan check took 6 months.

For fire rebuilds in Pacific Palisades and Los Angeles City where the new construction differs from what existed pre-fire, expect longer review timelines. LA City reviews each change from pre-fire conditions and requires documentation that the new work does not worsen drainage onto adjacent properties.

Key Takeaway

On flat lots with basement construction, if the lightwells and pool features sit below the street flowline, a sump pump becomes necessary. The pump handles only the below-grade elements. The rest of the site can often drain by gravity if the grade allows.

If you have a fire rebuild project in Pacific Palisades or Altadena with a basement, get us involved early. We can tell you whether the site will require a pump and what the drainage strategy needs to be before the architect finalizes the building design.