Planning Commission approves hillside exception for new home at 22346 Regnaught Road

The Cupertino Planning Commission voted to approve a hillside exception (EXC2023001) to permit grading greater than 500 square feet on slopes steeper than 30% for a proposed single-family residence at 22346 Regnaught Road.

The motion adopted the staff recommendation to find the project exempt from the California Environmental Quality Act and to approve the hillside exception and associated site design as outlined in the staff report.

Why it matters: The lot is within the Residential Hillside (RHS) zoning district and has an average site slope the staff described at about 45%, with the majority of the developable area near 36% slope. The commission’s approval allows construction on a steep hillside where special exceptions and geotechnical conditions apply.

What staff reported: Amy Sugiyama, planning staff, said the lot was created in a 1979 subdivision (Regnart Ridge) and that most lots in the subdivision were previously developed. She said the applicant proposes a 6,436-square-foot residence sited in the flattest portion of the lot, two non-protected trees would be removed and two oak trees added, and a septic system with a leach field would be located behind the residence. Sugiyama said the project proposes "12 54 cubic yards" of cut and fill, which the staff presentation characterized as less than the allowable 2,500 cubic yards for the site. She noted the property is within the city’s slope-instability geologic hazard area; the applicant prepared geologic and geotechnical reports that were peer reviewed by the city’s consultant and, according to staff, showed no evidence of landslides in the proposed development area. The Santa Clara County Fire Department asked the applicant to widen the private roadway frontage and improve a turnaround; the affected neighbor and HOA provided consent for that off‑site work.

Public comment and questions: Jennifer Griffin, speaking during the public hearing, raised concerns about septic systems’ long-term viability and asked whether the city has explored extending sewer lines up Regnart Road in the future. Commissioners pressed staff on the geologic reports’ dates and whether borings and peer review were recent; staff said original reports dated to February 2019 with supplements in 2021 and that a supplemental geotechnical report will be required at building-permit stage. Staff said peer review requested borings and that the borings did not find evidence of a landslide within the proposed disturbance area though some indications existed elsewhere on the larger property.

Commission discussion and vote: Commissioners asked about the frequency of hillside exceptions; staff noted about 21 such exceptions have occurred for development since the requirement began, and that two adjacent lots in the same subdivision previously received exceptions. Commissioners also asked about liability; staff said an indemnification agreement is in place with the developer and that additional geologic review is required before building permits are issued. The commission carried the motion; the meeting record states the motion carried with Commissioner Linscott absent.

Next steps: Staff condition the project’s building permit review on updated geotechnical documentation and compliance with the fire‑department roadway improvements and the resolution’s conditions.