Guidelines for Reviewing Geologic Reports

CGS Note 41

(Similar guidelines were adopted by the State Mining and Geology Board for advisory purposes in 1996.)

These guidelines provide general guidance for geologists who review consultants’ geologic reports on behalf of agencies having approval authority over specific developments. These general guidelines are modified from an article titled, "Geologic Review Process" by Hart and Williams (1978).

The geologic review is a critical part of the evaluation process of a proposed development. It is the responsibility of the reviewer to assure that each geologic investigation, and the resulting report, adequately addresses the geologic conditions that exist at a given site. In addition to geologic reports for tentative tracts and site development, a reviewer evaluates Environmental Impact Reports (EIRs), Seismic Safety and Public Safety Elements of General Plans, Reclamation Plans, as-graded geologic reports, and final, as-built geologic maps and reports. In a sense, the geologic reviewer enforces existing laws, agency policies, and regulations to assure that significant geologic factors (hazards, mineral and water resources, geologic processes) are properly considered, and potential problems are mitigated prior to project development. Generally, the reviewer acts at the discretion or request of, and on behalf of a governing agency -- city, county, regional, state, federal -- not only to protect the government’s interest but also to protect the interest of the community at large. Examples of the review process in a state agency are described by Stewart and others (1976). Review at the local level has been discussed by Leighton (1975), Berkland (1992), Larson (1992), and others. Grading codes, inspections, and the review process are discussed in detail by Scullin (1983). Nelson and Christenson (1992) specifically discuss review guidelines for reports on surface faulting.

The Reviewer


In order to make appropriate evaluations of geologic reports, the reviewer should be an experienced geologist familiar with the investigative methods employed and the techniques available to the profession. Even so, the reviewer must know his or her limitations, and at times ask for opinions of others more qualified in specialty fields (e.g., geophysics, mineral exploitation and economics, ground water, foundation and seismic engineering, seismology). In California, the reviewer must be licensed by the State Board of Registration for Geologists and Geophysicists in order to practice (Wolfe, 1975). The Board also certifies engineering geologists and hydrogeologists, and licenses geophysicists. Local and regional agencies may have additional requirements.

The reviewer must have the courage of his or her convictions and should not approve reports if an inadequate investigation has been conducted. Like any review process, there is a certain "give-and-take" involved between the reviewer and investigator. If there is clear evidence of incompetence or misrepresentation in a report, this fact should be reported to reviewing agency or licensing board. California Civil Code Section 47 provides an immunity for statements made "in the initiation or course of any other proceedings authorized by law." Courts have interpreted this section as providing immunity to letters of complaint written to provide a public agency or board, including licensing boards, with information that the public board or agency may want to investigate (King v. Borges, 28 Cal. App. 3d 27 [1972]; and Brody v. Montalbano, 87 Cal. App. 3d 725 [1978]). Clearly, the reviewer needs to have the support of his or her agency in order to carry out these duties.

The reviewer should bear in mind that some geologic investigators are not accomplished writers, and almost all are working with restricted budgets. Also, the reviewer may be limited by his or her agency’s policies, procedures, and fee structures. Thus, while a reviewer should demand that certain standards be met, he or she should avoid running rough-shod over the investigator. The mark of a good reviewer is the ability to sort out the important from the insignificant and to make constructive comments and recommendations.

A reviewer may be employed full time by the reviewing agency or part-time as a consultant. Also, one reviewing agency (such as a city) may contract with another agency (such as a county) to perform geologic reviews. The best reviews generally are performed by experienced reviewers. Thus, the use of multiple, part-time reviewers by a given agency tends to prevent development of consistently high-quality and efficient reviews. One of the reasons for this is that different reviewers have different standards, which results in inconsistent treatment of development projects. The primary purpose of the review procedure should always be kept in mind -- namely, to assure the adequacy of geologic investigations.

​​Other Review Functions

Aside from his or her duties as a reviewer, the reviewing geologist also must interpret the geologic data reported to other agency personnel who regulate development (e.g., planners, engineers, inspectors). Also, the reviewing geologist sometimes is called upon to make investigations for his or her own agency. This is common where a city or county employs only one geologist. In fact, some reviewers routinely divide their activities between reviewing the reports of others and performing one or several other tasks for the employing agency (such as advising other agency staff and boards on geologic matters; making public presentations) (Leighton, 1975).

​Conflict of Interest

In cases where a reviewing geologist must also perform geologic investigations, he or she should never be placed in the position of reviewing his or her own report, for that is no review at all. A different type of conflict commonly exists in a jurisdiction where the geologic review is performed by a consulting geologist who also is practicing commercially (performing geologic investigations) within the same jurisdictional area. Such situations should be avoided, if at all possible.

​Geologic Review

​​The Report

The critical item in evaluating specific site investigations for adequacy is the resulting geologic report. A report that is incomplete or poorly written cannot be evaluated and should not be approved. As an expediency, some reviewers do accept inadequate or incomplete reports because of their personal knowledge of the site. However, unless good reasons can be provided in writing, it is recommended that a report not be accepted until it presents the pertinent facts correctly and completely.

The conclusions presented in the report regarding the geologic hazards or problems must be separate from and supported by the investigative data. An indication regarding the level of confidence in the conclusions should be provided. Recommendations based on the conclusions should be made to mitigate those geology-related problems which would have an impact on the proposed development. Recommendations also should be made concerning the need for additional geologic investigations.

​​Report Guidelines and Standards

An investigating geologist may save a great deal of time (and the client’s money), and avoid misunderstandings, if he or she contacts the reviewing geologist at the initiation of the investigation. The reviewer should not only be familiar with the local geology and sources of information, he or she also should be able to provide specific guidelines for investigative reports and procedures to be followed. Guidelines and checklists for geologic or geotechnical reports have been prepared by a number of reviewing agencies and are available to assist the reviewer in his or her evaluation of reports (e.g., DMG Notes 42, 44, 46, 48, and 49). A reviewer also may wish to prepare his or her own guidelines or checklists for specific types of reviews.

If a reviewer has questions about an investigation, these questions must be communicated in writing to the investigator for response. After the reviewer is satisfied that the investigation and resulting conclusions are adequate, this should be clearly indicated in writing to the reviewing agency so that the proposed development application may be processed promptly. The last and one of the more important responsibilities of the reviewer should be implementation of requirements assuring report recommendations are incorporated and appropriate consultant inspections are made.

The biggest problem the reviewer faces is the identification of standards. These questions must be asked: "Are the methods of investigation appropriate for a given site?" and "Was the investigation conducted according to existing standards of practice?" Answers to these questions lie in the report being reviewed. For example, a reported landslide should be portrayed on a geologic map of the site. The conclusion that a hazard is absent, where previously reported or suspected, should be documented by stating which investigative steps were taken and precisely what was seen. The reviewer must evaluate each investigative step according to existing standards. It should be recognized that existing standards of practice generally set minimum requirements (Keaton, 1993). Often the reviewer is forced to clarify the standards, or even introduce new ones, for a specific purpose.

​Depth (Intensity) of Review

The depth of the review is determined primarily by the need to assure that an investigation and resulting conclusions are adequate, but too often the depth of review is controlled by the time and funds available. A report on a subdivision (e.g., for and EIR or preliminary report) may be simply evaluated against a checklist to make certain it is complete and well-documented. Additionally, the reviewer may wish to check cited references or other sources of data, such as aerial photographs and unpublished records.

Reviewers also may inspect the development site and examine excavations and borehole samples. Ideally, a field visit may not be necessary if the report is complete and well-documented. However, field inspections are of value, and generally are necessary to determine if field data are reported accurately and completely. Also, if the reviewer is not familiar with the general site conditions, a brief field visit provides perspective and a visual check on the reported conditions. Whether or not on-site reviews are made, it is important to note that the geologic review process is not intended to replace routine grading inspections that may be required by the reviewing agency to assure performance according to an approved development plan.

​​Review Records

  • For each report and development project reviewed, a clear, concise, and logical written record should be developed. This review record may be as detailed as is necessary, depending upon the complexity of the project, the geology, and the quality and completeness of the reports submitted. At a minimum, the record should:

  • Identify the project, permits, applicant, consultants, reports, and plans reviewed;

  • Include a clear statement of the requirements to be met by the parties involved, data required, and the plan, phase, project, or report being considered;

  • Contain summaries of the reviewer’s field observations, associated literature and aerial photographic review, and oral communications with the applicant and the consultant;

  • Contain copies of any pertinent written correspondence; and

  • Include the reviewer’s name and license number(s), with expiration dates.

The report, plans, and review record should be kept in perpetuity to document that compliance with local requirements was achieved and for reference during future development, remodeling, or rebuilding. Such records can also be a valuable resource for land-use planning and real-estate disclosure.


In cases where the reviewer is not able to approve a geologic report, or can accept it only on a conditional basis, the developer may wish to appeal the review decision or recommendations. However, every effort should be made to resolve problems informally prior to making a formal appeal. An appeal should be handled through existing local procedures (such as a hearing by a County Board of Supervisors or a City Council) or by a specially appointed Technical Appeals and Review Panel comprised of geoscientists, engineers, and other appropriate professionals. Adequate notice should be given to allow time for both sides to prepare their cases. After an appropriate hearing, the appeals decision should be in writing as part of the permanent record.

Another way to remedy conflicts between the investigator and the reviewer is by means of a third party review. Such a review can take different paths ranging from the review of existing reports to in-depth field investigations. Third party reviews are usually done by consultants not normally associated with the reviewing/permitting agency.


Berkland, J.O., 1992, Reviewing the geologic review process at the county level, in Stout, M.L., editor, Association of Engineering Geologists Proceedings, 35th Annual Meeting, p. 333-336.

California Department of Conservation, Division of Mines and Geology, DMG Notes:
DMG Note 42 -- Guidelines to geologic/seismic reports, 1986.
DMG Note 44 -- Recommended guidelines for preparing engineering geologic reports, 1986. [Being revised; not currently available.]
DMG Note 46 -- Guidelines for geologic/seismic considerations in environmental impact reports, 1986. [Being revised; not currently available.]
DMG Note 48 -- Checklists for the review of geologic/seismic reports for California public schools, hospitals, and essential services buildings, 1992. [Being revised; not currently available.]
DMG Note 49 -- Guidelines for evaluating the hazard of surface fault rupture, 1998.

California Department of Conservation, Division of Mines and Geology, 1997, Guidelines for evaluating and mitigating seismic hazards in California: Special Publication 117, 74 p.

Hart, E.W., and Williams, J.W., 1978, Geologic review process: California Geology, v. 31, p. 235-236.

Keaton, J.R., 1993, Environmental and engineering geology practice from the technical-professional society perspective: AEG News, Fall 1993, v. 36, no. 4, p. 19-21.

Larson, R.A., 1992, A philosophy of regulatory review, in Stout, M.L., editor, Association of Engineering Geologists Proceedings, 35th Annual Meeting. p. 224-226.

Leighton, F.B., 1975, Role of geotechnical consultants and reviewers for the County of San Mateo: California Geology, v. 28, p. 178-181.

Nelson, C.V. and Christenson, G.E., 1992, Establishing guidelines for surface fault rupture hazard investigations -- Salt Lake County, Utah, in ​Stout, M.L., editor, Association of Engineering Geologists Proceedings, 35th Annual Meeting, p. 242-249.

Rogers, J.D. and Olshanksky, R.B., 1992, Science versus advocacy -- the reviewers role to protect the public interest, in Stout, M.L., editor, Association of Engineering Geologists Proceedings, 35th Annual Meeting, p. 371-378.

Scullin, C.M., 1983, Excavation and grading code administration, inspection, and enforcement: Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 405 p.

Stewart, R.M., Hart, E.W., and Amimoto, P.Y., 1976, The review process and the adequacy of geologic reports: Bulletin of the International Association of Engineering Geology, no. 14, p. 83-88. (Reprinted in California Geology, October 1977, v. 30, p. 224-229).

Wolfe, J., 1975, More on registration: California Geology, v. 28, p. 155-156.