CONSULTING SOILS ENGINEERS & ENGINEERING GEOLOGISTS
FREQUENTLY ASKED QUESTIONS:
Q. - I am in escrow to purchase a residence. Do I need a soils/geology report?
A. - Not by law. However, if the property is hillside, then a soils/geology report should be obtained to evaluate geologic hazards, grading history, code compliance, drainage conditions, and the performance of existing structures. Building codes, grading standards and development techniques have evolved significantly through time in southern California. There may site issues that could prevent or restrict the ability to replace or enlarge existing structures.
Q. - I am building a new structure. Do I need a soils or combined soils/geology report?
A. - Maybe. If the project or property includes slopes steeper than 2:1, basements, retaining walls, very heavy loads, or is located in a Seismic Hazard Zone, a complete analysis and report will likely be required. Ask your architect, structural engineer or local Building Department. For projects in the City of Los Angeles, obtain a GPI (grading pre-inspection) report, which is required for all projects, and the inspector will tell you through the GPI whether a report is required.
Q. - What are the benefits of a soils/geology report?
A. - A thorough investigation and report will likely “pay for itself” by providing more than the “Code-minimum” values for structural design. The subsurface exploration will also discover geologic defects or hazards that will adversely affect structures. This will reduce construction costs and result in a better project.
Q. - Is there a difference between a soils report and a combined soils/geology report?
A. - Yes. A soils report is only prepared by a soils engineer. A combined soils/geology report is prepared by a soils engineer as well as an engineering geologist. Many jurisdictions and almost all hillside projects require a combined soils/geology report. Not all of our “competitors” have both licensed soils engineers and geologists on staff. Check the link to the Department of Consumer affairs to verify the license type.
Q. - What will a soils/geology report cost?
A. - Costs are very site dependent and functions of the project scope, site access, the underlying geologic and groundwater conditions, the seismic hazards and the jurisdictional requirements. Exploration and equipment costs are typically the largest portion of the budget. It is very difficult to provide quotes over the phone due to the potential complexities. Irvine Geotechnical provides free written proposals and costs estimates.
Q. - Is shopping for lowest soils/geology report cost good?
A. - It is good to become knowledgeable and to obtain competitive bids. However, the low bid is not good if the bidder is not providing the information required by the Architect, Structural Engineer, Contractor and reviewing Governmental Agency. Incomplete reports may lead to poor design, over-design, and often corrections or requests for additional information by the Building Department. This industry is not regulated and not all companies and bids are equal. Lower bids to the client almost always reflect lower costs to the soils/geology company, which implies: less exploration, less testing, less engineering analysis and less to no insurance overhead. Ask the Architect, Structural Engineer or your Building Department to review bids for completeness.
Q. - Can I change soils/geology consultants midway through a project?
A. - Sometimes. Other licensed engineers and geologists can accept another professional’s work project and assume responsibility as the engineer of record. But it may be very difficult to change consultants if the initial subsurface exploration and laboratory testing were substandard.
Q. - My property is within a State of California Seismic Hazard zone for liquefaction. What does that mean and how will it affect my project?
A. - Liquefaction may result in strength loss in saturated soils as a result of an earthquake. In order to protect the public, the State has mapped zones in California that may be susceptible to liquefaction. These sites almost always coincide with flood plains and near-ocean environments that are underlain by young soils and have historically high groundwater tables.
A liquefaction study is required for new structures or “significant alterations” to existing structures. The study involves determining the liquefaction resistance of the onsite soils usually using a drill rig to obtain SPT blow counts. The soils engineer will quantify the hazard and present recommendations to mitigate the hazard as appropriate.
Q. - My property is within a State of California Seismic Hazard zone for landsliding. What does that mean and how will it affect my project?
A. - Previous earthquakes in California and elsewhere have caused steep or weak slopes to fail or yield during significant earthquakes. In order to protect the public, the State has mapped zones in California that may be susceptible to earthquake-induce landsliding and ground deformation. These sites almost always coincide with steep hillside environments that are underlain by sedimentary bedrock or fills.
For properties in these zones, seismic slope stability study is required for new structures or “significant alterations” to existing structures. The study involves determining the geologic structure and the strength of the earth materials that comprise the slope. Deep borings and down-hole logging by the engineering geologist may be required. The soils engineer and geologist will quantify the hazard and present recommendations to mitigate the hazard as appropriate.
Q. - Can I use my own work crews or hire my own laborers to excavate test pits?
A. - Generally, no. The excavation subcontractors we use have General Liability and Worker's Compensation insurance, are OSHA certified, skilled in excavating test pits and trained to obtain soil samples.