Geotechnical Consulting Board Threadlines of Geotechnical and Engineering Geology firms in the Greater Los Angeles Metro-Southern California Area



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Adoption of Excavation and Grading Codes by other agencies (1952-65)

Similar excavation and grading ordinances to that enacted by the City of Los Angeles in 1952 were soon enacted by other municipalities and counties, including: Beverly Hills (1952), Pasadena (1953), Glendale (1954), Burbank (1954), Los Angeles County (1957), Whittier (1957), Ventura County (1958), Alhambra (1958), Santa Barbara County (1959), San Diego (1960), Monrovia (1961), City of San Diego (1962), Orange County (1962), Anaheim (1963), Riverside (1963), City of Orange (1964), Laguna Beach (1965), and San Bernardino County (1965).


Bulletin 170-Geology of Southern California (1954)

The California Geological Survey’s most sought-after references have historically included their bulletins, which contain a great deal of baseline geologic data. Bulletin 170, Geology of Southern California, was released in 1954. The volume’s editor was Caltech Professor Richard H. Jahns. Bulletin 170 contains 10 chapters, five field guides, and 34 map sheets that formed a comprehensive compilation of what was known about the geology of southern California up until that time. Long out-of-print, this bulletin is hard to come by except within university libraries and private collections, but it is a baseline document, absent any more recent work in a given area, this source is usually cited, along with the State Geologic Map (discussed below).


Adoption of National Map showing Zones of Seismic Probability (1955)

During the 28th annual meeting of the Pacific Coast Building Officials Conference in 1950, it was moved to adopt a map of the United States showing zones of approximately equal seismic probablility, compiled by the U.S. Coast & Geodetic Survey. This was eventually adopted in the 1955 Edition of the Uniform Building Code (UBC) of the Pacific Coast. California was divided into three zones: 1 – minor damage; 2 – moderate damage; and 3- major damage. The black dots on the map indicated the locations of of historic earthquakes with shaking intensities between 7 and 10. At that time, the three largest events were the New Madrid earthquakes of 1811-12; the Owens Valley earthquake of 1872, and the 1906 San Francisco earthquake.


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Federal Housing Administration Land Planning Bulletin No. 3 (1956)

In 1956 the Federal Housing Administration (FHA) issued Land Planning Bulletin No. 3, which set forth minimum standards for excavation and grading of residential subdivisions, including: inclinations of cut and fill slopes, requirements for mid-slope drainage terraces, and certification by soils engineers of 95% of Standard Proctor soil compaction. Developers seeking federal assistance had to comply with these standards and present soils & foundation engineering reports.


Portuguese Bend Landslide (1956) and the Los Angeles County Grading Code (1958; 1965)

In January 1956 the first in a series of large landslides occurred in the Portuguese Bend area of the Palos Verdes Peninsula. This came to be known as the 260-acre Portuguese Bend Landslide, which reactivated during the placement of a relatively small (in comparison to the landslide volume) fill for an extension of Crenshaw Boulevard, affecting 150 homes and causing $10 million in damage. These problems led to the County Board of Supervisors amending the County Building Code to include grading and excavation regulations similar to those of the City of Los Angeles, initially adopted in March 1958. The County established its Geology Section of the County Engineer’s Building & Safety Division in November 1959.

The slide at Portuguese Bend brought Los Angeles County into a landmark inverse condemnation suit that ultimately went against the County in 1965, costing them $6 million (Albers vs Los Angeles County; 62 Cal 2d, 263; 42 Cal Rpts 97). In July 1965 the County amended their grading ordinance reducing cut and fill slopes to 1.5:1, permanent provisions for control of surface runoff on slopes and across building pads, began requiring reports from engineering geologists and soil engineers for certain aspects of hillside development and mass grading, which could no longer be approved by a registered civil development work.

The Portuguese Bend Landslide has been under considerable study for many years and it was found to be stratigraphically controlled, but with an undulatory basal slip surface (see P.L. Ehlig, 1992, Evolution, Mechanics and Mitigation of the Portuguese Bend Landslide, Palos Verdes Peninsula, CA: in Proctor and Pipkin, eds., Eng’g Geol Practice in So Calif, AEG Spec Pub 4, p. 531-553). Other large landslides in the Palos Verdes Peninsula began to be recognized in the years since, and many of these have become active as well (see Landslides and Landslide Mitigation in Southern California, Geological Society of America Cordilleran Section Meeting Guidebook, Los Angeles, 1986).

The sheer magnitude of the landslide problem at Portuguese Bend and the liability potential posed to public entities triggered intense interest in the State taking a new role in “urban hillside development.” At a conference on that subject held at UCLA in February 1960, the Division of Mines laid forth their plan for mapping the geology of the Palos Verdes Peninsula, at the bequest of the City of Los Angeles. At the UCLA conference the absence of any engineering geologist on the staff of the Division of Mines was brought out and recognized, and efforts were then made to hire people qualified to address urban geologic hazards (see I. Campbell, 1960, 56th Report of the State Mineralogist: California Division of Mines, 219 p).
California Association of Engineering Geologists (1957); Association of Engineering Geologists (1963); Association of Environmental & Engineering Geologists (2005-present)

In June 1957 13 engineering geologists met in Sacramento to discuss the formation of an organization or society specific to the emerging field of engineering geology. The founders were employees of the U.S. Geological Survey, U.S. Bureau of Reclamation, Army Corps of Engineers, California Department of Water Resources and Division of Highways, and two consultants (including Ray Taber of Moore & Taber). Over the next eight months they drafted the Constitution and Bylaws as the California Association of Engineering Geologists (CAEG), with three sections in Sacramento, Los Angeles, and San Francisco. CAEG vigorously promoted certification of engineering geologists in southern California (in Los Angeles, Orange, and Ventura Counties) and then professional registration of geologists in California (and later, nationwide).

AEG was also the organization primarily responsible for the development of “modern” [second generation] grading and excavation codes, adopted in southern California in the early 1960s and by the International Conference of Building Officials for inclusion in the Uniform Building Code in 1964. As interest in affiliation spread beyond California, the prefix was dropped and it became the [national] Association of Engineering Geologists, or AEG, in January 1963, and was accepted as a member society in the American Geological Institute in 1964.

In 1963 AEG began publishing a referred journal titled “Bulletin of the Association of Engineering Geologists,” released quarterly. Management of this journal was conjoined with the Geological Society of America in 1995 and the name changed to “Environmental & Engineering Geoscience,” released six times per year. In January 2005 members voted to change the name to the Association of Environmental & Engineering Geologists to better describe the geoenvironmental work many of its members specialized in. The new name was formally adopted in September 2005, although the organization still calls itself “AEG.”


Pacific Palisades Landslide Study (1958-59)

On March 31, 1958, flowing heavy rainfall, the Via de Los Osas Landslide buried the Pacific Coast Highway (PCH), between Rustic and Temescal Canyons. It was the largest landslide ever to occur along the Pacific Palisades, and required more than a year to mitigate and restore the coast highway. Serious landslide s closures had previously occurred in 1956, and the California Division of Highways wondered if the cost of maintaining PCH was unjustified. In an unprecedented move, the State Department of Public Works (which over saw the Division of Highways) contracted with the prestigious geotechnical consulting firm of Moran, Proctor, Meuser & Rutledge (MPMR) of Manhattan to make a comprehensive study of the slide problems along the Pacific Coast Highway, which dated back to 1889. MPMR classified more than 100 landslides along the highway and investigated and analyzed 34 of those. Their work included recovery of Shelby Tube samples, and the installation and long-term monitoring of piezometers and slope inclinometers. Residual strength tests on landslide slips surfaces developed in the Modelo and Martinez shales were performed under contact by Professor T.W. Lambe at MIT for MPMR. These test revealed that the overconsolidated clay shales tended to lose shear strength through strain softening by creeping for many years previous to actual rupture, similar to the shales exposed along the Panama Canal. These results were summarized in a massive three volume report by MPMR entitled “Final Report, Pacific Palisades Landslide Study,” submitted in July 1959. The findings are summarized in an article by the project’s manager James P. Gould, titled “A Study of Shear Failure in Certain Tertiary Marine Sediments,” in the ASCE Research Conference on Shear Strength of Cohesive Soils in June 1960. This article, more than any other, shaped the approaches by which subsequent assessments of “bedrock landslides” were analyzed in Los Angeles County for the next four decades. The slide was converted into the Pacific Palisades Park, saving the homes on the north side of Via de Los Osas Drive.


USDA Soil Conservation Service county reports (1960-94)

Around 1960 the Soil Conservation Service (SCS) began publishing reports contain summaries of engineering properties for the mapped soils on aerial photo mosaics published at 1:24,000 (same scale as 7.5 min. quadrangles). The post-1960 SCS reports also contain tabulations of test data and engineering classifications, according to the American Association of State Highway Officials (AASHTO) and Unified Soil Classification System (USCS) used by most consultants. The SCS has published and updated these reports from 1960 to present, though they are often out-of-print. In 1971 SCS issued their Guide for Interpreting Engineering Uses of Soils (USDA, Soil Conservation Service, Washington, D.C., 86 p.), which lays forth the rationale by which engineering classifications of soil are tabulated in the individual county reports they publish.


Los Angeles County-USGS-CDMG Cooperative Geologic Mapping Program (1960)

In 1960 the office of the Los Angeles County Engineer (John A. Lambie) entered into a cooperative contract with the U.S. Geological Survey and the California Division of Mines & Geology for geologic mapping of “critical hillside areas,” including: Palos Verdes Hills (by Prof R.H. Jahns at Caltech and the CDMG); San Gabriel Mountains (initially covering the Mt Baldy, Azusa, Glendora quads, and later the Pasadena and Mt Wilson quads, in cooperation with LACFCD, USFS, and CDMG); Santa Monica Mountains (Topanga, Malibu Beach, and Point Dume, Calabasas, and Trufino Pass quads, working with the USGS); Puente and San Jose Hills (working with Prof. John Shelton at Pomona College, Beach Leighton at Whittier College, and Robert F. Yerkes of the USGS). This work was carried out in the early 1960s and completed by 1964.


Division of Mines & Geology Landslide Mapping in the Palos Verdes Peninsula (1961-65)

While the Division of Mines embarked on their first landslide and urban geologic mapping effort in the Palos Verdes Peninsula, beginning in 1961, the loss of the Portuguese Bend suit was the catalyst for new ordinance by Los Angeles County in 1964 requiring geologic reports in any area proposed for subdivision in which a certain degree of “geologic hazard” was presumed to exist (see I. Campbell, 1976, The influence of geologic hazards on legislation in California: Bulletin of Int’l Assn Eng’g Geol, n. 14, p. 201-04). The late 1950s and early 60s were a period of relative calm before the storm, due to lower-than-normal rainfall (H.E. Thomas, et al, 1963, Effects of drought along the Pacific Coast in California: USGS Professional Paper 372-G). In early 1963 things began to change when a sequence of destructive storms struck all of coastal California (see S.E. Rantz and E.E. Harris, 1963, Floods of January-February 1963 in California and Nevada: USGS Open File Report,74 p.).


CAEG’s Recommended Practices for Hillside Grading and Development (1961-62)

Authored by Douglas R. Brown Chair, with assistance of C. Michael Scullin (1961) and Dennis A. Evans (1962), respective chairmen of the Committee on Building Codes of the Los Angeles Section of CAEG. The CAEG Committee that wrote the first grading & excavation code was comprised of: Doug Brown, John T. McGill, Douglas E. Moran, William Schlax, James Slosson, William Waisgerber, R. Bruce Lockwood, Allan Bailey, Joe LoBue, Russell Hood, and Blase Cilweck. Their report on “Hillside Grading and Development” became the basis for the “modern grading codes” adopted by Los Angeles County (1962), the City of Los Angeles (1963), Orange County (1964), and Chapter 70-Excavation and Grading of the 1964 Uniform Building Code.


Mt. Soledad Landslide in La Jolla (1961)

Los Angeles was not the only area to take the brunt of landslide problems attendant to hillside development. The Mt. Soledad landslide in La Jolla occurred in 1961, shortly after a fill embankment was placed above a 1.5:1 cut slope, both for residential development. Fortunately, the 8 homes that were destroyed were not yet occupied (described in M.W. Hart, 1989, Engineering Geology in San Diego, CA: in Keaton and Morris, eds., Engineering Geology of Western United States Urban Centers: 28th Int’l Geol Congress, Field Trip Guidebook T181, American Geophysical Union, p. 22-30). Similar failures befell the Malibu area and other hilly parts of Los Angeles and Orange Counties. By the late 1960s there existed new awareness of landslides in the urban environment, and the state of the practice at that time was pretty much summarized in Beach Leighton’s classic 1966 article titled Landslides and Hillside Development, which appeared in the AEG publication Engineering Geology in Southern California.


Adoption of “Model” Excavation and Grading Codes (1963-70)

During the first two weeks of February 1962 about 24 cumulative inches of precipitation fell on downtown Los Angeles, and more in the highlands surrounding the Los Angeles Basin. A great number of hillside fill embankments failed, usually sliding on un-keyed contacts with the underlying soils. The large number of failures pointed to a definite need for engineering geologic input in design and construction of hillside subdivisions, leading to the establishment and adoption of deep benching and keying with continuous inspection by the soils firms.

The newly re-vamped Los Angeles Grading Ordinance was adopted in April 1963. Orange County consulted with their Grading Board of Appeals and Geology Qualifications Boards to revise their new grading code, and this newer code, requiring full-time grading and engineering geology inspection, was adopted by Orange County in June 1964. Los Angeles and Ventura counties passed similar revisions a short while later. Contractors liked the new statutes because they felt the soils engineers were forced to shoulder more of the liability burden that had been the case previously, maintaining that “their work was being directed by the soils engineers.”
Geology Registration by the American Institute of Professional Geologists (1963)

Prior to 1963, geologists were not accountable with respect to public responsibility, regulation, and business practice, and no established guidelines or no national representation existed in behalf of those engaged in private practice. That year a small group of geologists met in Golden, Colorado, to compose the Constitution and Bylaws for the American Institute of Professional Geologists (AIPG), which was chartered on November 14, 1963 as a nonprofit corporation. Consulting petroleum geologist Martin Van Couvering of Los Angeles was elected the first President, and the institute’s headquarters was established at the Colorado School of Mines. Members who went through an established process of verifying their formal education and professional experience could qualify to use the title "Certified Professional Geologists," abbreviated by the letters "CPG" after their name. This was fairly common practice in California prior to the state’s adoption of a geologist registration act a few years later, in 1969.

AIPG drew a significant number of its members from AEG, who were the most concerned about geology registration (most geologists employed in the mining and petroleum industries were ambivalent about professional registration). AIPG worked diligently to secure model registration acts in those states where a significant number of geologists worked in the private sector, usually working with the local organizations operating in those areas.

AIPG become a national organization with a membership of nearly 850 by 1965, little more than a year offer its’ founding. By 1974, AIPG had more than 2,000 members, and moved its headquarters to 622 Gardenia Court in Golden, where it remained for eight years. By the mid-1970s it had attracted a broad spectrum of geoscientists, including geophysicists, geochemists, and engineering geologists. In 1982 the AIPG headquarters moved to Arvada, Colorado, where for many years John W. Rold (from the Colorado Geological Survey) served as the society’s executive director. Today, AIPG has over 5,000 members and affiliates, which are organized into 36 sections.


AEG Building Codes Committee (1962 – 2002)

AEG was instrumental in pushing through the Grading and Excavation provisions of the Uniform Building Code through the International Conference of Building Officials, headquartered in Whittier until national consolidation of building codes in 2002. That committee was originally chaired by Douglas R. Brown in 1960-62, followed by Jim Slosson (1962-64), Don Michael, in 1964-66, and Mike Scullin in 1966-69. From about 1973-85 Jack Rolston served as chair of the AEG Building Codes Committee, when he was succeeded again by Mike Scullin (1985-92), then by J. David Rogers (1992-2000), who was followed by Betsy Matheson (2000-onward).

AEG’s Building Codes Committee received input for their model excavation and grading code from separate committees formed in the association’s three active sections at the time: Los Angeles, San Francisco, and Sacramento. This input culminated in the preparation of Appendix Chapter 70-Excavation and Grading of 1961, which was submitted with that name for review at CAEG’s annual meeting in Oct 1962, when Slosson was the committee chair.

A revised version was then submitted to ICBO in Whittier in the spring of 1963 for consideration of inclusion in the 1964 Uniform Building Code (UBC). The ICBO Code Changes Committee was comprised of Jerry Wilson from the City of Glendale (chairman), Ed O’Connor of the City of Long Beach, Ventura County Building Director Robert O’Bannion, and a Mr. O’Brien, the Building Director for the City of Thousand Oaks. Non-voting members who attended all of the ICBO meetings included Doug Brown, who represented AEG’s national Building Codes Committee and Mike Scullin, representing the Los Angeles Section’s Building Codes Committee. The ICBO committee originally envisioned using a mark-up of the revised 1962 Los Angeles County Grading & Excavation Code, but ended up using the draft AEG Code, which was less prescriptive in terms of required engineering geology input, which the committee feared would be rejected by most ICBO members outside of southern California. Surprisingly, the main opposition to the adoption of UBC Appendix Chapter 70 came from structural engineers, not the Building Industry Association (BIA).

The AEG Building Codes Committee also prepared a brochure titled “Recommended Practices for Hillside Grading,” which many firms included in their consulting reports and a number of individuals have taken credit for developing. After 1963, revision and improvement of this document was carried out by another committee, described below. In the late 1970s-early 1980s the committee was co-chaired by Joseph W. Cobarrubias, CEG and James P. Krohn, PE, CEG.

The most substantive changes made to Chapter 70/33 Appendix Excavation & Grading of the Uniform Building Code occurred in 1967, 1970, 1985, 1991, 1994, and 1997 (which introduced sweeping changes in codifying simplified seismic design procedures in California). The single biggest change to UBC Appendix Chapter 70 was in 1970, when the maximum inclination of fill slopes was dropped from 1.5: 1 down to 2:1 (horizontal to vertical). This was because so many failures had occurred in the Jan-Feb 1969 storms, which witnessed sustained rainfall intensities between 0.25 and 1.0 inches/hr. By employing an infinite slope stability analyses, local soil engineers learned that an angle of internal friction of 40 degrees would be required to guarantee short-term stability for the saturated face of a 1.5:1 slope, so they agreed to flatten the slopes to 2:1, which would remain stable with a friction angle of 30 degrees and an assumed cohesion of 100 psf. Everyone seemed comfortable with these figures until the early 1980s, when a number of local jurisdictions in the San Francisco East Bay dropped their maximum slopes to 3:1.

The substantive additions in the 1990s were ascribable to the 1989 Loma Prieta and 1994 Northridge earthquakes, combined with a down-turn in development in the Los Angeles area, which precluded vociferous objections by the Building Industry Association (BIA), who had opposed proposed code changes during the two previous decades.
Development of UBC Expansion Index Test No 29-2 (1965-68) and ASTM D 4829 (1995)

In the early 1960s there were no standardized test procedures for quantifying or predicting the behavior of expansive soils, which were widespread in most of the inland valleys of southern California. Most of the soils engineers employed their own tests, yielding answers in expected “percent swell.” A conflict developed between these engineers in regards how to best, using either “wet” or “dry” tests (wet test procedures had been pioneered by O.J. Porter and the California Division of Highways in 1928, described previously). Doug Lehman of International Soils Engineering favored the “dry test” procedures. Newly promoted Orange County Engineer Floyd McClellan decided to resolve the conflict by requesting input for AEG’s Building Codes Committee and the Soil Mechanics Group of the Los Angeles Section of ASCE. These groups nominated the following representatives: Len Krazynski of Woodward-Clyde-Sherard was named Chairman, assisted by Stan Gizienski (MSCE ’48 Harvard) of Woodward-Clyde-Sherard, Rhett Moore of Moore & Taber, J. Robert Davis of Converse-Davis Foundation Engineers, and Dennis Evans of Evans, Goffman & McCormick. When they convened other soils engineers also attended the meetings and provided useful input. The importance of geologic input in regards to clay mineralogy was brought to bear in the wake of the La Jolla Landslide in 1970, which was studied by Jack Eagen of Moore & Taber.

In the end, the “wet testers,” who preferred pre-soaking specimens in the soils lab, won out, and the UBC Expansion Index Test No. 29-2, resulted. It requires pre-soaking of specimens under varying levels of effective confinement, then measuring the percent swell. This procedure was the one favored by Len Krazynski, Stan Gizenski, and Louis Lee of Woodward-Clyde-Sherard & Associates and summarized in Krazynski and Lee (1966) “Identification and Testing of Expansive Soils,” in AEG’s Seminar on the Importance of the Earth Sciences to the Public Works and Building Official,” at AEG’s annual meeting in Anaheim in 1966 (organized by Orange County Geologist Mike Scullin). In 1967 the Orange County and San Diego offices of Woodward-Clyde-Sherard also prepared a series of reports on expansive soils testing for the Portland Cement Association (PCA), which came to be regarded as national benchmark standards.

UCLA Prof. Poul Lade and his graduate student James M. Anderson undertook a thorough assessment of the Expansion Index Test in the late 1970s because so many geotechnical engineers had been complaining about it. Lade and Anderson found it to be a very reliable test, summarized in the article: "The Expansion Index Test," ASTM Geotechnical Testing Journal, (Vol. 4, No. 2, June 1981, pp. 58-67). The Expansion Index Test was formally adopted as ASTM Test Standard D 4829 in 1995.

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