DBI Updates Requirements
for Geotechnical Reports
In order to implement the Seismic Hazards Mapping Act based on the CDMG Seismic
Hazard Zones map released in November 2000 showing areas of potential liquefaction
and landslide in San Francisco, the Department of Building Inspection (DBI) requires
that two (2) copies of geotechnical reports be submitted for projects requiring
geotechnical seismic hazard mitigation. These projects include:
1. All new buildings and all horizontal additions to buildings that increase the ground
floor area more than 50% or 2500 square feet and that have any portion within the
potential landslide areas and/or the potential liquefaction areas on the CDMG
ASeismic Hazard Zones Map.@
A copy of this map is located on the wall to the left of the DBI Plan Check Service
Division counter on the second floor at 1660 Mission Street. Maps have been made
available by CDMG for purchase from BPS Reprographic Services, 149 Second
Street, San Francisco, CA 94105, phone 415-512-6550. Seismic hazard maps and
information regarding mapping legislation are available on the internet at
http://www.consrv.ca.gov/dmg/shezp/maps/m_sf.htm.
2. Buildings with foundation design exceeding the limitations of SFBC Section 1805
regarding allowable foundation and lateral pressures.
3. Sites where the maximum cut either exceeds 10 feet in vertical height, or where the
finished cut slope is steeper than 2 horizontal to 1 vertical, or where the top of the cut
bank is less horizontal distance from any structure than the depth-to-bank height.
4. Buildings with any special foundation design such as piles, piers, or base isolation.
5. All structures that use the Dynamic Lateral-Force Procedures of SFBC Sec. 1629.
Following its review of geotechnical reports for projects in seismic hazard zones to
determine the adequacy of the hazard evaluation and proposed mitigation measures,
DBI now forward one copy of these approved reports and any waivers to CDMG.
The main impact of Seismic Hazards Mapping regulations on the general public is the
requirement that property sellers or agents disclose to prospective purchasers the fact
that a property is located within a seismic hazards zone. To find out whether or not a
building at a specific address is located in a Seismic Hazard Zone, call 558-6205.
Any general questions about the map can be addressed to Zan Turner at 415-558-6104.
EQ\General\Map-2-req.wpd - 2/5/01