Board affirms Planning Department categorical exemption for 2142 20th Street project after geotechnical concerns raised

The San Francisco Board of Supervisors voted 11-0 April 15 to affirm the Planning Department's categorical exemption under the California Environmental Quality Act (CEQA) for a proposed six‑unit residential project at 2142 20th Street in Potrero Hill and to table motions that would have required additional CEQA findings or a reversal of that exemption.

The board's decision came after an hourlong public hearing in which the appellants said unusual site conditions — a steep slope, mapped seismic landslide hazard, and underlying serpentine bedrock — create a reasonable possibility of significant environmental impacts that require an initial study under CEQA.

Why it matters: Appellants and an independent geotechnical expert argued that planned excavations of up to about 30 feet and limited shallow borings to 2–5 feet leave key site hazards uncharacterized; the Planning Department and the project sponsor said those issues are addressed through routine building permit processes, local codes and state law.

Appellant Emily Brough, representing the neighboring homeowners association, said the question before the board was not whether the building should be built but “whether…