Geotechnical Reports / Soils Reports

Determining Report Necessity

Fault MapThese types of reports are typically required for any structure such as main residences, guest houses, additions, barns, detached accessory structures etc. Such reports are also required for most site grading and retaining walls.

The Necessity of Geotechnical (Soils) Reports & Review in Woodside Town

Two of the main reasons is due to the fact that there are two active earthquake fault traces running through the middle of the Town - the San Andreas and the Canada, and due to the fact that Woodside contains some of the most expansive soils found in the region. A third reason is that the Natural Hazards/Safety Element of the Town's General Plan indicates that a basic goal of the Town is to "minimize the risk from identified hazards for the Town and for private individuals."

The Town attempts, through geotechnical review, to ensure that geotechnical design recommendations and plans meet minimum standards of acceptability, in order to reduce the exposure to geologic hazards and the damage resulting from them. Geologic hazards generally of concern in the Woodside area include earthquakes, landslides and expansive soils.

Geotechnical review by the Town involves thorough review of pertinent geologic and engineering reports, maps and other information to reduce the exposure of a site or structure to such hazards, consistent with accepted standards of the geotechnical profession. Additionally, the State of California requires geotechnical review within mapped seismic (earthquake) zones, and is preparing similar requirements for landslide areas. The basic responsibility for design remains with the applicant's consultants.

A geotechnical report for review by the Town is required, but not limited to, where any of the following apply:

  1. The project is a new home, accessory living unit or accessory structure. This review may occur at both the planning (feasibility) and building permit (design-level) stages.
  2. The project adds bedrooms or occupiable space to an existing structure.
  3. The project is a swimming pool or a spa.
  4. Tennis court located on slopes greater than 20%, is a pool located in the Western Hills area of Town or in an area of expansive soils.
  5. The project will require grading greater than 1,500 cubic yards or cuts or fills in excess of 5 feet in depth.
  6. The project will require septic drainfields to be located on slopes greater than 20%.

Special circumstances may also require geotechnical review. These may include close proximity to a creek, seismic zones or landslide areas, repair or replacement of foundations, conversions to increase occupancy, retaining walls, experimental wastewater disposal systems, etc.

The appropriate preparer of an engineering geologic report is a Certified Engineering Geologist (CEG). The appropriate preparer of a soils engineering report is a registered Civil Engineer experienced in geotechnical engineering (preferably a titled Geotechnical Engineer). The Town Geologist can best indicate which specialty (or both) is required for your project.

The following are steps the Town recommends one take for geotechnical review:

  1. Consult with the Town Geologist prior to retaining a consultant to determine the nature and extent of analysis required for your site prior to your investing considerable time and money in a site geotechnical investigation.
  2. Retain a geotechnical consultant to prepare a report, if required, and consistent with any initial recommendations made after consultation with the Town Geologist.
  3. Submit 2 copies of the report (if the report is to be reviewed in conjunction with a proposed habitable structure, submit 4 copies) to the Town's Planning and Building Department.
  4. The fee is a nonrefundable processing charge. The deposit is collected to cover charges by the Town Geologist. Any balance remaining in a deposit account after all billing is completed is refundable. In cases where the deposit does not cover the actual cost of services, an additional deposit amount will be requested.
  5. The Town Geologist will review the report within 20 working days and provide written comments.
  6. If minor revisions are required, your consultant should contact the Town Geologist. Some issues can be resolved over the phone, others require an addendum report.
  7. If significant revisions are required, the Planning Director and Town Geologist will meet with you and your consultant to provide direction regarding additional work required. Further deposits may be necessary to offset subsequent review costs.

After your geotechnical report is approved your geotechnical consultant of record must certify that the design of your structure reflects the recommendations of the geotechnical report(s) by submitting a 'Plan Review' letter to the Town prior to issuance of your building permit.

Subsequent project construction must be done under geotechnical observation and certified as having been done in conformance with the recommendations made in the report(s). Final inspection and occupancy will not be allowed until such certification (Construction Observation and Testing 'Final' Letter) is received.

The Plan Review and Final letters must be prepared by the geotechnical consultant of record. If there is a change in consultant, the new consultant must concur, in writing, with the recommendations made by the previous consultant or provide alternative recommendations. The consultant must assume responsibility for all geotechnical aspects of the project.

Related Documents