Any lot that sits on the North side of the block or sideways in Altadena is likely going to require drainage plans. Some South lots might require drainage plans as well.
After seeing a lot of different corrections over the last few months for Altadena fire rebuild plans, we are going to try to not use stormwater sump pumps and instead use plastic lined rain gardens at the low points in the rear yard for any drainage plans. A stormwater sump pump will trigger a set of street plans which we are trying to not do because everyone rebuilding is going to be cost sensitive. We had our pump distributor spec out a generic enough pump for the rough sized houses we are seeing on the sloped lots to get an idea on current pricing, which will be about $15-20k in unit costs for a duplex pump. If Altadena will allow the lined rained gardens instead, this would be an effective cost savings to home owners.
LA County prefers to use infiltration pits that are no closer than 15 ft from structures and 5ft from the property line. But I recently learned we could rebuild our garage on the lot line, which if someone next door decided to do an infiltration pit they would be infiltrating right under a potential garage structure. This is why I asked about plastic lined rain gardens.
From this point on this is what we will try to get approved. If LA County ends up not wanting these, then we go the pump route. We are prioritizing any fire rebuilds and going to turn them around as fast as possible. The last drainage plan to get approved went into plan check and was approved the same week, and that was in September. Let us know if you need any help as we know its starting to become very confusing.