California Dam Safety Act of 1929
In the wake of the St. Francis Dam failure, the state passed a much more comprehensive Dam Safety Act on August 14, 1929. The Act empowered the State Engineer to review all non-federal dams > 25 feet high or which impound > 50 acre acre-feet of water. The act also allowed the State to employ consultants, as deemed necessary. The State Engineer was given $200,000 and instructed to examine all dams in California within three years and issue recommendations. The State Engineer was given full authority to supervise the maintenance and operation of all non-federal dams (exempting those constructed by the Army Corps of Engineers and the Bureau of Reclamation)
Between August 1929 and November 1931 the State Engineer inspected 827 dams. One third were deemed to exhibit adequate safety, while another third were recommended for further examination, such as borings or subaqueous inspection, before a determination could be made. The remainder, roughly, another third, were ascertained to be in need of alterations, repairs or changes; frequently involving spillway capacity.
After this there followed a six-year program of dam safety inspection, which were concluded in July 1936. During this period 950 dams were inspected; with 588 of these dams being under the State’s jurisdiction. One third of these dams were found in need of repairs. New dam construction was also placed under state observance from August 1929 forward.
First lecture notes in English on soil mechanics (1929-30)
In October 1929 Professor William S. Housel in the Department of Civil Engineering at the University of Michigan prepared a 117 page text titled “A Practical Method for the Selection of Foundations Based on Fundamental Research in Soil Mechanics,” released as University of Michigan Engineering Research Bulletin No. 13 (and published by Waverly Press in Baltimore). This volume was primarily focused on the determination of soil bearing capacity for spread footings, and resulted from a cooperative project between the university and the Wayne County Road Commission in Detroit, between 1927-29. This book was used by Professor Fred Converse at Caltech when he taught his forst soil mehcanics course in the spring semester of 1934.
In 1930 Glennon Gilboy, Sc.D., an Assistant Professor of Soil Mechanics at MIT, self-published a 62-page monograph titled “Notes on Soil Mechanics: Prepared for Use of Students of the Msssachusetts Institute of Technology,” which he copyrighted as a first edition. Gilboy had been a doctoral student of Professor Karl Terzaghi while he was as a visiting scholar at MIT, from 1925-29. This work was essentially America’s first English volume on the broader spectrum of soil mechanics, which included chapters addressing soil structure, mechanical analysis, permeability, and consolidation theory. It featured detailed ink drawings of the various laboratory tests then in use, along with example calculations, including Gilboy’s doctoral research on consolidation of the clay core of the massive Germantown Dam near Dayton, Ohio, placed using hydraulic fill technology in the early 1920s.
Evolution of Porter Soil Samplers (1930-47)
In 1930 Omer James Porter of the California Division of Highways began developing a retractable plug sampler, known as the “Porter Type Soil Sampler.” The device then underwent a series of improvements over the next six years, based on experience. This inexpensive sampler was widely employed over the next 50 years to recover 1-inch to 2-inch diameter samples. The device employed a lockable plug at the foot of the sampler, which remained in place while the sampler rings were driven ahead to the desired depth. When the desired depth interval was reached, the plug was retracted up inside the sample barrel, and the open sample barrel advanced ahead of its starting position, to recover between 18 inches to five feet of relatively undisturbed soil sample (depending on diameter).
The device enjoyed much success because a vacuum was maintained during driving, helping recovery of samples. Porter Samplers came in a variety of diameters and lengths. The one inch diameter samplers were designed for manual operations in soft soils and were limited in their application to depths of up to 60 feet. This sampler employed an outside diameter of just 1.25 inches with 1-inch sampler barrel. The one-inch sampler was usually set up by a three man crew using a portable tripod.
In 1933 Porter introduced a three-inch diameter sampler intended to recover undisturbed two-inch diameter soil samples. The sampler was five feet long, allowing a continuous sample to be taken of that length. Two samplers were normally assigned to each rig so that drilling and sampling operations could be sustained, without interruption. The sampler was fitted with segmented brass liners, 2- inches in diameter and two inches high, which after sampling, were separated using a piano wire saw (see T.E. Stanton, 1936, An Improved Type of Soil Sampler for Explorations of Soil Conditions and Soil Sampling Operations, Proc 1st ICSMFE, Cambridge, v.1, p.13-15).
The two-inch sampler required power equipment and was originally developed for the recovery of undisturbed samples of clay for the San Francisco Oakland Bay Bridge project. Between 1933-36 more than 13,000 lineal feet of samples were taken from 232 borings for the Bay Bridge, as well as other highway projects. These samplers were used to a maximum depth of 232 feet on the Bay Bridge. A larger sampler was also fabricated to recover four-inch diameter samples for those situations that warranted larger diameter samples, for shear strength and consolidation testing.
The two and four-inch samplers were used with truck mounted drilling rigs. For subaqueous sampling beneath San Francisco Bay, the drill rigs were tied to barges and steel well casings was inserted through the waters and driven 7 to 90 feet into the seafloor. The depth of penetration depended on the presence of running sands (ENR, June 4, 1936, p. 804-05). Brass caps were used to seal the individual sample segments upon recovery. The four-inch sampler required heavier equipment to operate, so was only used in situations that justified the additional cost.
During World War II Porter developed “all-in-one” truck-mounted drilling rigs with retractable masts and a suitable array of Porter Samplers. These were intended to provide a more robust system of drilling and recovery of continuous soil samples for the Navy out in the Pacific, where they were having difficulties drilling through porous and cavernous coral, causing loss of drilling circulation. These rigs were equipped with three-foot long samplers, intended to recover continuous two-inch diameter samples using three-foot sampling rounds. The rigs could develop 20,000 pounds force to aid sampling at depth. After the war (1946-47) Porter developed even heavier truck-mounted drilling rigs that could exert pressures of up to 30,000 pounds up or down, which doubled as exploration and foundation drilling rigs, which could be used to drill large diameter caissons (see O.J. Porter, Taking Soil Samples by the Soil Tube Method in November 1947 issue of Roads & Bridges).
In the mid-1950s Porter began marketing a 3-inch diameter sampler capable of recovering 2.5-inch diameter samples, which could be used with either 6-inch, 2-inch, or 1-inch high brass rings. This was intended to compete with the Modified California Sampler of Dames & Moore, described later.
Structural Engineer title act (1932)
In September 1932 the California Board of Registration for Civil Engineers begin granting the special title “structural engineer” (S.E.), which required applicants to demonstrate three to five years of responsible charge of structural engineering projects to be eligible to sit for a special examination. But, those individuals who could document more than five years of experience in “responsible charge” were duly grandfathered into the title. The first SE exam wasn’t offered until several years later, in 1934.
In March 1933 the Long Beach earthquake killed 115 people and caused $50 million in damage, mostly to unreinforced masonry structures, such as public school buildings. Within a month of the quake, the California Legislature passed the Field Act (described below), which empowered the Office of the State Architect to undertake whatever measures it deemed appropriate to ensure safe design and construction of public school buildings, which included requirements for plans prepared by a certified architect or structural engineer and set requirements for lateral earthquake loads, which depended on location. The Field Act left a lasting imprint on how structural engineers would be qualified in California; requiring them to demonstrate an understanding of analyses, designs, and consultations involving structural engineering principles associated with the application of seismic loads.
A companion legislation called the Riley Act (described below) was also enacted in 1933, which required local agencies in California to establish their own building and inspection departments (the first Uniform Building Code had appeared in 1927, but only a handful of the state’s largest cities had adopted it). The Riley Act also required all new construction to be designed to withstand an earthquake acceleration of at least 0.02g, but also allowing municipalities the discretion to employ even higher values, as they deemed appropriate.
National Council of State Boards of Engineering Examiners (1932)
In October 1932 a National Council of State Boards of Engineering Examiners (NCSBEE) was endorsed at a meeting in New York of the National Bureau of Engineering Registration (NBER), headquartered in Columbia, South Carolina. NCSBEE sought to create standardized civil engineering registration examinations and requirements so reciprocity of licenses between the 28 states mandating professional registration could be undertaken more efficiently. NCSBEE changed its name to the National Council of Engineering Examiners (NCEE) in 1967. NCEE developed standardized tests which were gradually adopted by most states, beginning in the 1960s. NCEE broadened its scope to include establishment of a Model Rule for Professional Conduct in 1979, which many courts have considered as national standards for professional engineering conduct. In 1989 NCEE became the National Council of Examiners for Engineering & Surveying (NCEES). Its headquarters remains in South Carolina (at Clemson).
California remained unaligned with the national examination concept until 1975, when they acquiesced to the standardized NCEE examination, which they have since employed. The reason the California board gave for this reticence was the “eastern bias” they perceived in the NCSBEE/NCEE exams, which had less emphasis on transportation engineering problems, as compared to California’s own tests.
First use of wick drains in California (1933)
O. James “Pappy” Porter was also the moving force behind the development of sand wick drains, which were initially employed on the fill approaches to the San Francisco-Oakland Bay Bridge in 1933-36. These are generally regarded as the first successful employment of wick drains in the USA [Porter, O.J., 1936, Studies of fill construction over mud flats including a description of experimental construction using vertical sand drains to hasten stabilization: Proc. Int’l Conf Soil Mech & Fdn Eng, Cambridge, MA, Vol. 1, pp. 229-235]. One of the higher visibility projects Porter employed sand drains for a railroad relocation around Chicago’s O’Hare Field, in 1947-48, which was very successful. George Bertram (MSCE ’39 Harvard) and Reginal Barron of the U.S. Army Corps of Engineers went on to perfect the art of sand drains, building on the pioneering work of Porter in the 1930s and 40s.
Passage of the Riley and Field Acts (1933)
Two significant pieces of legislation came out of the March 10, 1933 M6.3 Long Beach earthquake. Within 30 days of the quake the State legislature passed the Field Act, named after California Assemblyman Charles Field, the key sponsor of the legislation. His bill focused on making public school buildings in California more earthquake resistant (all K-12 and community college school buildings). It was also the first statewide legislation that mandated earthquake resistant construction in the United States. The quake destroyed or rendered unsafe 230 school buildings in Southern California because these were constructed of unreinforced masonry. Fortunately, the quake occurred at 5:55 PM on a Friday, after most everyone had gone home, and thousands of children’s lives were thereby spared.
The Field Act was introduced with the Riley Act, which together, all but banned unreinforced masonry construction, requiring that earthquake forces be included in the design of new structure, and all existing public schools. This included a requirement for base shear calculations, and that school buildings must be able to withstand lateral forces equal to at least 3% of the building total mass. The Act also established the Office of the State Architect (now Division of the State Architect or DSA) which developed design standards, quality control procedures, and required that schools be designed by registered architects and engineers. These professionals are required to submit their plans to the State Architect for review and approval prior to construction. The same professionals were also required by the Act to periodically inspect the construction while underway and verify that the actual work completed is in compliance with the approved drawings. Peer review was also introduced as another quality control procedure.
The other significant legislation that came out of the March 1933 Long Beach earthquake was the Riley Act, which required all cities and counties in California to establish departments to regulate building construction. Roughly 10 to 15 percent of California’s present structures were built prior to 1933, when few cities had building codes (the Uniform Building Code was introduced in 1927, but was only adopted by a few of the larger municipalities, such as the City of Los Angeles). The Riley Act required local jurisdictions to establish building and safety departments and inspect new construction, mandating that all structures in the state be designed to withstand a horizontal acceleration of 0.02g. These requirements applied only to new structures, and California municipalities could add to the Riley Act requirements at their own discretion. The Riley Act has exerted an enormous impact on California because structures built since 1933 have been constructed with some minimal measure of lateral reinforcement and load transfer elements within the framing, and later, between the framing and the foundations. Since the 1960s, California codes have become more uniform across local jurisdictions. The Riley Act includes exemptions for wood frame structures of two stories or less, as well as bi-plexes and single-family residences of all construction in unincorporated areas (only one person was killed inside a single-story wood frame dwelling by any California earthquake during the 20th Century). However, many counties enhance their requirements for such buildings beyond these statewide minimums.
Adoption of seismic loads recommended by the UBC (1933)
Following the March 1933 Long Beach Earthquake, the State of California required every municipality to adopt a building code (under the Riley Act, described above). 114 California municipalities adopted the 1933 Edition of the UBC, including most of the larger cities in southern California. Prior to 1933 only Palo Alto and Santa Barbara had adopted more restrictive codes for seismic loading.
Due to the poor performance of unreinforced masonry structures during the Long Beach earthquake, the 1933 UBC required all school of two stories or more in height to be built of reinforced concrete or structural steel frame construction. Single story schools were required to have fire-resistant walls and floors, and fire-retarding roofs. All public buildings, including schools, were required to provide for lateral forces from earthquake motion, and the use of lime mortar was altogether outlawed.
School districts and local municipalities complained, but a vigorous program of retrofit and school reconstruction, as well as new construction, soon ensued, providing work for architects, structural engineers, and contactors. It also bolstered the prestige and respect of licensed structural engineers, and their organizations, such as SEAOSC and SEAOCC. San Francisco adopted their own more restrictive version of this code in 1948 (described below), based on input from the Structural Engineers Association of Central California.
U.S. Soil Conservation Service established (1933-35)
In June 1933 Congress passed the National Industrial Recovery Act, which included appropriations to combat agricultural soil erosion. This action was prompted by ‘The Dust Bowl’ conditions brought on by extended drought conditions in the Southwestern and Midwestern states. In September 1933 the federal Soil Erosion Service (SES) was established within the Department of Interior with Hugh H. Bennett as its Chief. Bennett had formerly served as a surveyor with the old U.S. Bureau of Soils. The SES established demonstration projects in critically eroded areas across the country to publicize the benefits of soil conservation.
In April 1935 Congress passed Public Law 74-46, which established the Soil Conservation Service (SCS) as a permanent agency within the U.S. Department of Agriculture, again under the direction of Bennett. In 1929 Bennett wrote a book titled “Soil Erosion: A National Menace,” which influenced the decision to establish federal soil erosion experiment stations in 1929.
Bennett instituted a seven-fold increase in demonstration projects for local farmers and SCS began publishing County-wide report “separates,” which included color overlays on then-existing USGS 15-minute (1:62,500 scale) topographic map mosaics. One example would be: E.J. Carpenter and S.W. Cosby, 1939, Soil Survey, Contra Costa County, California: USDA Bureau of Chemistry and Soils, Series 1933, No. 26. A check of this original map not only reveals the soil assignments, but in most instances, also provides an assessment of the undeveloped topography. These were usually prepared by local soil scientists attached to the SCS or in cooperation with the U.C. Agricultural Experiment Stations.
In the late 1930s SCS set about developing more reliable and scientifically-based maps of soil deposits with extensive compendiums of soils properties. In 1920 Professor Curtis F. Marbut of the University of Missouri began developing an agricultural soils classification scheme. In 1927 he translated Glinka's The Great Soil Groups of the World and their Development from German. His classification scheme was unveiled in the 1938 Yearbook of Agriculture, Soils and Men: the 1938 USDA soil taxonomy. He divided soils into pedocals (carbonate rich soils in the drier climates) and pedalfers (soils developed in more humid climes and rich in aluminum and iron. Alfer became the root term for Alfisols. This new scheme met with mixed success.
The decade following the Second World War saw Congress increased appropriations for soil conservation programs. Between 1945-48 a new classification system was developed, culminating with the “7th approximation,“ introduced in 1960, which became the national standard in 1965. This was tweaked slightly to include 10 distinct soil orders in 1975, and expanded to include 12 soil orders in 1999. These details are included here to make the reader aware that soil surveys performed in different decades use differing descriptive terms. In 1994 the name of the agency was changed to the Natural Resources and Conservation Service (NRCS).
National Society of Professional Engineers (1934)
The National Society of Professional Engineers (NSPE) was founded in New York City in 1934 as the national society of engineering professionals from all disciplines, which promotes the ethical and competent practice of engineering, professional licensure, and enhances the image and well-being of the professional of engineering. NSPE established the celebration of National Engineers Week in 1951, in conjunction with President George Washington's birthday (February 22nd). President Washington is considered as the nation's first engineer, notably for his survey work. NSPE has worked with ASCE to establish uniform standards for professional engineering of civil engineers in all 50 states and territories of the United States, which went into effect in 2003. NSPE now serves more than 54,000 members and the public through 53 state and territorial societies and more than 500 chapters.
Downhole Logging of Large Diameter Borings (1935 – onward)
Around 1935 consulting foundation engineer R. V. Lebarre, PE, SE (1871-1944) of Los Angeles began excavating vertical shafts between two and three feet in diameter with a mobile power auger (described in “Test Pit Exploration Kit for Foundation Study” in the August 6, 1936 issue of Engineering News Record). These borings were of sufficient size and depth (60 to 70 ft deep) to allow a geologist to descend the unshored holes for purposes of evaluating the geologic conditions and making measurements and taking soil or rock samples. These men also used soil penetrometers to record soil stiffness with depth, creating detailed subsurface logs.
The art of downhole logging was lost when Lebarre died in 1944, but was revived in the early 1960s by F. Beach Leighton, PhD, CEG and Robert Stone, PhD, CEG in the Los Angeles area, who used the same techniques, but with flexible Boatswain’s Mate rope ladders, which Leighton had used in the late 1940s to descend into glacier crevasses in Alaska. Two excellent articles describing the use of using bucket augers have been published, both by San Francisco Bay area consultants: C.M. Scullin, 1994, “Subsurface exploration using bucket auger borings and down-hole geologic inspection,” AEG Bulletin v. 31:91-105; and P.L. Johnson and W.F. Cole, 2001, “The use of large-diameter boreholes and downhole logging methods in landslide investigations,” Engineering Geology Practice in Northern California, CDMG Bulletin 21-/AEG Spec Pub 12, pp. 95-106. No one has ever been killed while performing downhole logging, although Frank Dennison lost one of his legs after passing out and having to be dragged up out of the hole (down in the Los Angeles area).
Soil Mechanics & Foundations Division of ASCE (1936)
At the annual ASCE meeting in July 1936 the society’s Board approved the formation of a new Soil Mechanics & Foundations Division from the Committee on Earths and Foundations, which had been established in 1929. The first Executive Committee of the new division was comprised of: W.P. Creager of Buffalo, Carlton S. Proctor of New York City, J. F. Coleman of New Orleans, Frank A, Marston of Boston, and R.V. Labarre of Los Angeles. Proctor served as the first Chairman and Theodore T. Knappen of the Army Corps of Engineers, as the division’s first secretary.
Ted Knappen was a 1917 graduate of Berkeley High School and attended Berkeley’s CE program in 1917-18 before receiving an appointment to West Point, where he graduated with the Class of 1920, receiving a commission in the Corps of Engineers. In 1923 he resigned his commission and began a notable civilian career, working on projects in California until the Great Flood of 1927 along the Mississippi River, when he was hired by the Corps of Engineers for a supervisory civil service position. After working on the Mississippi River & Tributaries Project, Knappen built the Corps of Engineers’ first soil mechanics laboratory for the Muskingum Valley Project in 1933. In 1942 he started his own firm, Theodore Knappen & Associates, in New York City. A few years after his death in 1951, the surviving partners (all former Corps of Engineers officers or Corps civil service employees) renamed the firm Tippetts-Abbett-McCarthy-Stratton, since known by the acronym TAMS.