Baldwin Hills Reservoir
Encyclopedia
The Baldwin Hills Reservoir was a water storage basin located on a low hilltop in Baldwin Hills, Los Angeles, California
. It was constructed between 1947 and 1951 by the Los Angeles Department of Water and Power
directly on an active fault line
which was subsidiary to the well known nearby Newport-Inglewood fault
. The underlying geologic strata were considered unstable for a reservoir, and the design called for a compacted soil lining meant to prevent seepage into the foundation. The fault lines were considered during planning but were deemed by some, although not all, of the engineers and geologists involved as not significant.
On 14 December 1963, there were signs of lining failure followed by increasingly serious leakage through the dam at its east abutment. In three hours the dam breached, releasing altogether 250 million USgals (946,353 m³) onto the surrounding neighborhood. In the process, 277 homes were destroyed and 5 lives were lost. Vigorous rescue efforts averted a greater loss of life.
The reservoir is now part of Kenneth Hahn State Recreation Area
.
, were aware of the difficult geologic conditions presented by the site and knew well, from the experience of the sudden collapse of their Saint Francis Dam in 1928, the serious consequences of a failure of even small reservoirs in an urban setting. But this was also an era of new engineering ventures on land, sea, and space, with new technologies boldly advanced to meet what were seen as hostile challenges from both nature and communist ideologies. Dams, like nuclear technologies, were recognized as potentially dangerous but they were also considered by Americans as a showcase technology, a means of fending off danger and spreading progressive American social benefits at home and abroad.
The Baldwin Hills dam designer, engineer Ralph Proctor, who had worked as resident engineer on the failed Saint Francis Dam and had subsequently devised new methods of producing compacted earth fill in building its replacement, aggressively proceeded with the Baldwin Hills project even in the face of safety concerns and disagreements over important design details within his own department.
Late 1963, when the failure occurred, was a time of notable public disasters; only a few weeks before the Italian Vajont Dam
had failed, drowning 2000 people. The failure of the Baldwin Hills Reservoir, which was built to assure safe water for the people of Los Angeles in case of catastrophes such as earthquake, fire, and war, was a blow to engineering confidence, and its failure was the subject of many writings and two professional conferences (1972 and 1987, see references) in the twenty five years following the failure. The failure occurred shortly after the death of the authoritative Harvard engineer Karl Terzhagi whose ideas had long dominated both the engineering science of soil mechanics
and earth dam engineering. Terzaghi had also made significant contributions to understanding subsidence in oilfields. This left the assessment of the Baldwin Hills failure in the hands of his successors, who took on conflicting roles as experts in various lawsuits.
The design and construction of the dam had been inspected and approved by the California Department of Water Resources, and a study published by that agency in 1964, soon after the failure, was meticulously documented but, even while pointing out various connections between oilfield operations in the Inglewood field and ground disturbances in the area, avoided a conclusive finding on oilfield causation, concluding rather vaguely that the failure was due to "an unfortunate combination of physical factors".
The monetary damages resulting from the failure were large and some of the investigations which followed the state study were sponsored by litigants seeking more specific conclusions relevant to legal liability. This drew attention to oilfield operations in the area. From the outset it was clear that ground faulting, including the aseismic fault movements that destroyed the reservoir, were probably related to the many feet of ground subsidence which had occurred a half mile west of the reservoir over decades of oil extraction in the Inglewood field. This oilfield-related subsidence, though generally denied by the oil companies as a legal policy, was documented exhaustively by the US Geological Survey in 1969.
Following the discovery in 1970 by geologist Douglas Hamilton of faulting and surface seepage of oilfield waste brines along the fault which traversed the reservoir, Hamilton and Meehan concluded that oilfield injection for waste disposal and improved recovery of oil, a new technology at the time, was a significant cause of the failure, triggering movements on a fault traversing the reservoir even on the day of the failure.
By 1972, nearly a decade after the failure, the immediate legal issues had been settled out of court and the matter was reopened as a topic of discussion among investigators in a published engineering conference at Purdue University.
Engineer Thomas Leps, who had served as consultant on the 1964 state investigation, took on a role as neutral reviewer in this and most subsequent American studies of the failure. Leps concluded that there had been about 7 inches of offset on the fault beneath the reservoir during its life, about 2 inches of which had occurred in the months just before the failure. Leps associated the latter with repressuration of the oilfield. This, along with stretching of the ground due to subsidence of about 12 feet from oil extraction, had caused the lining failure which doomed the reservoir.
Some prominent consultants including those on a team led by Arthur Casagrande, Harvard successor to Karl Terzaghi, held that oilfield operations were not a significant influence at all but that the failure was the result of defective siting and design with the heavy weight of the dam and reservoir being the significant cause of the fatal foundation movement. This view exonerated the oil companies, namely Standard Oil, which had sponsored the study. Casagrande refused to acknowledge any ground movements in the area as being related to oilfield operations and argued that ground movements that affected the dam were found only beneath the reservoir, not in adjoining areas.
Most of these questions were examined once again in 1986 following investigations of a suspiciously similar major failure of the Bureau of Reclamation's Teton Dam
in June, 1976, and a near failure of the Department of Water and Power's Lower Van Norman Dam in the 1971 San Fernando earthquake. By this time the prominent engineer Stanley Wilson, who had worked with Casagrande on the 1972 studies and supported the claim that subsidence was insignificant, now conceded that ground offsets extended well outside the reservoir area and were not caused by the reservoir itself, and were therefore a factor in the destruction of the drain system, thus tacitly attributing at least partial responsibility to oilfield operations. Hence, there appeared to be convergence on the role of oilfield subsidence and repressurization even though there appeared to be some differing views on the exact mechanics of the process and whether the failure would have occurred eventually regardless of this factor.
The issue of oilfield causation was a theme in most of these discussions, with little attention having been directed to the details of the failure. The absolute necessity of a lining for this site was generally taken for granted in these proceedings even as it had been by Proctor himself, regardless of the fact that almost all earth dams perform satisfactorily without linings. Some suggestions as to possible preventive design and construction techniques that might have made the dam safer were raised as engineering consensus reached a state of textbook knowledge in the late 1980s. For example, the character of the compacted earth lining (which had been regularly referred to as clay but must have been substantially silt and sand, having been derived from the local Inglewood formation) was raised, if obliquely, in the suggestion made in the end that improved performance might have come from the use of a different lining material.
In 2001 a new angle on failure analysis was introduced by Mahunthan and Schofield, who concluded that overcompaction of the dam fill and lining was a significant aggravating factor in both the Baldwin Hills and Teton failures. This assertion was based on Schofield's concepts of critical state soil mechanics, a corollary of which was that heavily compacted but lightly confined soils could be dangerously unstable where seepage forces were present. This issue had not been raised in the previous American-dominated discussions and remains in some degree contrary to American ideas in both theoretical soil mechanics and practical geotechnical engineering. In fact the 1964 DWR failure study implied that heavy compaction was a favored technique for earth dam construction. and this assumption appeared not to have been reexamined over the twenty five years of post failure investigation and discussion.
The failure of the reservoir has been a subject of ongoing interest in the field of dam breach studies. A recent study examined the dam failure as a two-stage process and succeeded in modeling the flood in the urban area downstream.
Baldwin Hills, Los Angeles, California
Baldwin Hills is a community and neighborhood in the South Los Angeles area of Los Angeles, within southwestern Los Angeles County, California...
. It was constructed between 1947 and 1951 by the Los Angeles Department of Water and Power
Los Angeles Department of Water and Power
The Los Angeles Department of Water and Power is the largest municipal utility in the United States, serving over four million residents. It was founded in 1902 to supply water and electricity to residents and businesses in Los Angeles and surrounding communities...
directly on an active fault line
Fault line
In geology, fault line refers to the surface trace of a fault.Fault line, Fault Line, or faultline may also refer to:* "Faultline", a song from the 2008 studio album Versus by The Haunted...
which was subsidiary to the well known nearby Newport-Inglewood fault
Newport-Inglewood Fault
The Newport-Inglewood Fault is a right-lateral fault in Southern California. The fault extends for from Culver City southeast to Newport Beach at which point it runs out into the Pacific Ocean. The fault can be seen on the Earth's surface as line of hills extending from Signal Hill to Culver City...
. The underlying geologic strata were considered unstable for a reservoir, and the design called for a compacted soil lining meant to prevent seepage into the foundation. The fault lines were considered during planning but were deemed by some, although not all, of the engineers and geologists involved as not significant.
On 14 December 1963, there were signs of lining failure followed by increasingly serious leakage through the dam at its east abutment. In three hours the dam breached, releasing altogether 250 million USgals (946,353 m³) onto the surrounding neighborhood. In the process, 277 homes were destroyed and 5 lives were lost. Vigorous rescue efforts averted a greater loss of life.
The reservoir is now part of Kenneth Hahn State Recreation Area
Kenneth Hahn State Recreation Area
Kenneth Hahn State Recreation Area or "Hahn Park" is a state park and recreation area in the California Department of Parks and Recreation system...
.
Significance and Diagnoses of the Failure
The failure of the Baldwin Hills Reservoir received an exceptional amount of attention from the civil engineering community and remains a subject of continuing interest. The reservoir had been conceived, designed, and built during and after World War II when the pace of dam building was accelerating even as some disastrous dam failures were indicating a need for improved technologies. The builders, Los Angeles Department of Water and PowerLos Angeles Department of Water and Power
The Los Angeles Department of Water and Power is the largest municipal utility in the United States, serving over four million residents. It was founded in 1902 to supply water and electricity to residents and businesses in Los Angeles and surrounding communities...
, were aware of the difficult geologic conditions presented by the site and knew well, from the experience of the sudden collapse of their Saint Francis Dam in 1928, the serious consequences of a failure of even small reservoirs in an urban setting. But this was also an era of new engineering ventures on land, sea, and space, with new technologies boldly advanced to meet what were seen as hostile challenges from both nature and communist ideologies. Dams, like nuclear technologies, were recognized as potentially dangerous but they were also considered by Americans as a showcase technology, a means of fending off danger and spreading progressive American social benefits at home and abroad.
The Baldwin Hills dam designer, engineer Ralph Proctor, who had worked as resident engineer on the failed Saint Francis Dam and had subsequently devised new methods of producing compacted earth fill in building its replacement, aggressively proceeded with the Baldwin Hills project even in the face of safety concerns and disagreements over important design details within his own department.
Late 1963, when the failure occurred, was a time of notable public disasters; only a few weeks before the Italian Vajont Dam
Vajont Dam
The Vajont Dam is a disused dam, completed in 1959 in the valley of the Vajont river under Monte Toc, 100 km north of Venice, Italy...
had failed, drowning 2000 people. The failure of the Baldwin Hills Reservoir, which was built to assure safe water for the people of Los Angeles in case of catastrophes such as earthquake, fire, and war, was a blow to engineering confidence, and its failure was the subject of many writings and two professional conferences (1972 and 1987, see references) in the twenty five years following the failure. The failure occurred shortly after the death of the authoritative Harvard engineer Karl Terzhagi whose ideas had long dominated both the engineering science of soil mechanics
Soil mechanics
Soil mechanics is a branch of engineering mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids and particles but soil may also contain organic solids, liquids, and gasses and other...
and earth dam engineering. Terzaghi had also made significant contributions to understanding subsidence in oilfields. This left the assessment of the Baldwin Hills failure in the hands of his successors, who took on conflicting roles as experts in various lawsuits.
The design and construction of the dam had been inspected and approved by the California Department of Water Resources, and a study published by that agency in 1964, soon after the failure, was meticulously documented but, even while pointing out various connections between oilfield operations in the Inglewood field and ground disturbances in the area, avoided a conclusive finding on oilfield causation, concluding rather vaguely that the failure was due to "an unfortunate combination of physical factors".
The monetary damages resulting from the failure were large and some of the investigations which followed the state study were sponsored by litigants seeking more specific conclusions relevant to legal liability. This drew attention to oilfield operations in the area. From the outset it was clear that ground faulting, including the aseismic fault movements that destroyed the reservoir, were probably related to the many feet of ground subsidence which had occurred a half mile west of the reservoir over decades of oil extraction in the Inglewood field. This oilfield-related subsidence, though generally denied by the oil companies as a legal policy, was documented exhaustively by the US Geological Survey in 1969.
Following the discovery in 1970 by geologist Douglas Hamilton of faulting and surface seepage of oilfield waste brines along the fault which traversed the reservoir, Hamilton and Meehan concluded that oilfield injection for waste disposal and improved recovery of oil, a new technology at the time, was a significant cause of the failure, triggering movements on a fault traversing the reservoir even on the day of the failure.
By 1972, nearly a decade after the failure, the immediate legal issues had been settled out of court and the matter was reopened as a topic of discussion among investigators in a published engineering conference at Purdue University.
Engineer Thomas Leps, who had served as consultant on the 1964 state investigation, took on a role as neutral reviewer in this and most subsequent American studies of the failure. Leps concluded that there had been about 7 inches of offset on the fault beneath the reservoir during its life, about 2 inches of which had occurred in the months just before the failure. Leps associated the latter with repressuration of the oilfield. This, along with stretching of the ground due to subsidence of about 12 feet from oil extraction, had caused the lining failure which doomed the reservoir.
Some prominent consultants including those on a team led by Arthur Casagrande, Harvard successor to Karl Terzaghi, held that oilfield operations were not a significant influence at all but that the failure was the result of defective siting and design with the heavy weight of the dam and reservoir being the significant cause of the fatal foundation movement. This view exonerated the oil companies, namely Standard Oil, which had sponsored the study. Casagrande refused to acknowledge any ground movements in the area as being related to oilfield operations and argued that ground movements that affected the dam were found only beneath the reservoir, not in adjoining areas.
Most of these questions were examined once again in 1986 following investigations of a suspiciously similar major failure of the Bureau of Reclamation's Teton Dam
Teton Dam
The Teton Dam was a federally built earthen dam on the Teton River in southeastern Idaho, set between Fremont and Madison counties, USA, which when filling for the first time suffered a catastrophic failure on June 5, 1976. The collapse of the dam resulted in the deaths of 11 peopleand 13,000 head...
in June, 1976, and a near failure of the Department of Water and Power's Lower Van Norman Dam in the 1971 San Fernando earthquake. By this time the prominent engineer Stanley Wilson, who had worked with Casagrande on the 1972 studies and supported the claim that subsidence was insignificant, now conceded that ground offsets extended well outside the reservoir area and were not caused by the reservoir itself, and were therefore a factor in the destruction of the drain system, thus tacitly attributing at least partial responsibility to oilfield operations. Hence, there appeared to be convergence on the role of oilfield subsidence and repressurization even though there appeared to be some differing views on the exact mechanics of the process and whether the failure would have occurred eventually regardless of this factor.
The issue of oilfield causation was a theme in most of these discussions, with little attention having been directed to the details of the failure. The absolute necessity of a lining for this site was generally taken for granted in these proceedings even as it had been by Proctor himself, regardless of the fact that almost all earth dams perform satisfactorily without linings. Some suggestions as to possible preventive design and construction techniques that might have made the dam safer were raised as engineering consensus reached a state of textbook knowledge in the late 1980s. For example, the character of the compacted earth lining (which had been regularly referred to as clay but must have been substantially silt and sand, having been derived from the local Inglewood formation) was raised, if obliquely, in the suggestion made in the end that improved performance might have come from the use of a different lining material.
In 2001 a new angle on failure analysis was introduced by Mahunthan and Schofield, who concluded that overcompaction of the dam fill and lining was a significant aggravating factor in both the Baldwin Hills and Teton failures. This assertion was based on Schofield's concepts of critical state soil mechanics, a corollary of which was that heavily compacted but lightly confined soils could be dangerously unstable where seepage forces were present. This issue had not been raised in the previous American-dominated discussions and remains in some degree contrary to American ideas in both theoretical soil mechanics and practical geotechnical engineering. In fact the 1964 DWR failure study implied that heavy compaction was a favored technique for earth dam construction. and this assumption appeared not to have been reexamined over the twenty five years of post failure investigation and discussion.
The failure of the reservoir has been a subject of ongoing interest in the field of dam breach studies. A recent study examined the dam failure as a two-stage process and succeeded in modeling the flood in the urban area downstream.