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Oil and Gas
13 min read
Areas of Expertise :
Petroleum Engineering, Materials Science, Air Quality, Toxicology, Property Damage
Published Date:
Last Modified Date:
Jurisdiction:
California State
A failed underground storage well at Southern California Gas Company’s Aliso Canyon facility released natural gas into the Porter Ranch area of Los Angeles for nearly four months. The release began at well SS-25 on October 23, 2015, and continued until crews brought the well under control in February 2016. California regulators estimated that about 109,000 metric tons of methane entered the atmosphere. Approximately 15,000 residents temporarily relocated, two nearby schools moved students and staff, and community members reported odors, headaches, nausea, nosebleeds, breathing problems, and residue on homes and outdoor surfaces.
The Aliso Canyon gas leak led to several connected legal proceedings rather than one lawsuit with a single outcome. Residents pursued bodily injury, nuisance, relocation, and property-loss claims, while nearby businesses sought compensation for lost income. State and local agencies brought separate enforcement actions, and the California Public Utilities Commission examined SoCalGas operations, storage practices, and customer-rate treatment. SoCalGas and its parent company, Sempra, later agreed to provide up to $1.8 billion to settle claims involving approximately 36,000 individual plaintiffs.
SoCalGas detected an uncontrolled natural gas release from Standard Sesnon well 25, commonly known as SS-25, at the Aliso Canyon underground storage facility. Gas passed through a damaged section of the well casing and moved toward the surface through the surrounding ground. The company began a top-kill operation the next day in an effort to control the well from above. Seven top-kill attempts made between October 24 and December 22 failed to stop the flow.
The Los Angeles County Department of Public Health directed SoCalGas to offer temporary relocation assistance to area residents affected by odors from the Aliso Canyon site. Residents had reported strong odors and symptoms that included headaches, nausea, dizziness, nosebleeds, and breathing complaints. About 15,000 people eventually moved into temporary housing. Students and staff from two nearby schools were also transferred to other campuses.
As the release continued, residents began filing claims involving bodily injury, nuisance, trespass, emotional distress, relocation expenses, cleaning costs, loss of property use, and reduced real estate values. Some residents also reported residue on homes, vehicles, outdoor furniture, landscaping, and other property. These claims later became part of coordinated civil proceedings in Los Angeles County Superior Court.
Governor Edmund G. Brown Jr. declared a state of emergency in Los Angeles County while the release remained uncontrolled. The proclamation directed state agencies to assist with containment, methane monitoring, public-health measures, resident communication, and underground storage-well oversight. It also called for stronger inspection, testing, and risk-management requirements. State regulators continued supervising containment work and reviewing conditions at Aliso Canyon.
After drilling a relief well, crews gained control of the release on February 11, 2016, by pumping heavy fluids into SS-25. Cement was then placed inside the well to form a permanent barrier. On February 18, the California Department of Conservation confirmed that testing found no continuing gas movement. The confirmation process included temperature and noise logs, fluid-level monitoring, and a cement-bond test.
Hundreds of lawsuits were brought together in Los Angeles County Superior Court under Southern California Gas Leak Cases, JCCP No. 4861. The coordinated litigation included resident claims, property disputes, business claims, and other actions arising from the release. The pleaded causes of action included negligence, negligence per se, public and private nuisance, trespass, strict liability, inverse condemnation, emotional distress, wrongful death, and fraudulent concealment. Common discovery, motions, settlement procedures, and other pretrial matters were managed through the coordinated proceeding.
Before limited injection resumed, California regulators completed safety reviews of wells proposed for renewed operation. Wells returning to service were required to operate through interior tubing rather than through the space between the tubing and outer casing. Pressure limits, testing duties, monitoring requirements, and other operating conditions were also imposed. SoCalGas resumed limited gas injections by the end of July 2017.
The Los Angeles County Superior Court approved a $119.5 million settlement between SoCalGas and several state and local government agencies. The participating agencies included the California Attorney General, California Air Resources Board, Los Angeles City Attorney, and County of Los Angeles. Funds were allocated to methane mitigation, air monitoring, public-health research, community programs, civil penalties, and government response costs. SoCalGas also agreed to maintain fence-line methane monitoring, create an internal facility safety committee, and retain an independent safety ombudsman.
Blade Energy Partners completed an independent investigation into the cause of the SS-25 failure. Investigators found that microbial corrosion damaged the exterior of the outer seven-inch casing where the metal was exposed to groundwater. The damage led to an axial rupture in the casing. The review also identified weaknesses in earlier casing-leak investigations, well-integrity risk assessments, external corrosion protection, well-control planning, and continuous pressure monitoring.
In Southern California Gas Leak Cases, 7 Cal. 5th 391, the California Supreme Court considered negligence claims brought by businesses near Porter Ranch. The businesses alleged that resident relocations reduced customer traffic and caused lost income, but they did not claim bodily injury or physical damage to property they owned. The court ruled that SoCalGas did not owe them a negligence duty covering those purely economic losses.
The decision applied to the business plaintiffs’ claims for lost income. It did not resolve resident claims involving bodily injury, nuisance, trespass, loss of use, or alleged property conditions. The court affirmed the dismissal of the business negligence claims.
SoCalGas and Sempra entered into an agreement to resolve approximately 390 lawsuits involving about 36,000 individual plaintiffs. The settlement provided up to $1.8 billion for claims connected to the Aliso Canyon release. Covered allegations included bodily injury, property loss, relocation expenses, nuisance, emotional distress, lost earnings, and related damages. Participating plaintiffs were required to release their claims against the companies and other covered parties.
A separate $40 million agreement addressed claims brought on behalf of certain property owners and lessors. SoCalGas and Sempra also reached a smaller settlement involving the named plaintiffs in the proposed business class action. Each agreement used its own payment and claims procedures.
More than 99 percent of the individual plaintiffs submitted accepted releases and joined the settlement. SoCalGas paid approximately $1.79 billion under the agreement during 2022. Most coordinated individual lawsuits ended through the settlement process rather than through a single trial. A limited number of plaintiffs continued to pursue claims outside the main agreement.
A separate settlement approved by the California Public Utilities Commission addressed SoCalGas operations and practices connected to the release. For purposes of the agreement, SoCalGas acknowledged one violation of California Public Utilities Code section 451. The resolution included a $105.1 million financial assessment, reduced by a $34.1 million credit for earlier methane-mitigation spending. The remaining $71 million was directed to the Aliso Canyon Recovery Account.
The agreement also covered refunds, reimbursements, and expenses that SoCalGas could not collect from utility customers. Those expenses included costs tied to resident relocations, private litigation, government settlements, outside legal work, and the independent investigation. The CPUC closed that regulatory investigation after approving the settlement.
The CPUC decided that Aliso Canyon would remain open while regional gas demand, electric reliability, infrastructure, storage needs, and customer costs remained under review. The decision kept the facility’s maximum storage level below its capacity before the 2015 release. It also created a process for examining possible storage reductions every two years. A projected peak-day gas-demand threshold was adopted for beginning further review of possible closure.
The first Aliso Canyon biennial assessment found that projected gas demand remained above the threshold for considering full closure. CPUC Energy Division staff recommended keeping the facility available for winter 2025–2026 and summer 2026. The assessment also proposed reducing the maximum inventory by 10 billion cubic feet, from 68.6 to 58.6 billion cubic feet. Staff stated that a smaller reduction or no reduction could also be considered because the economic analysis did not fully account for later forecasts of higher gas prices during winter 2026–2027.
A Sempra filing reported that only three individual plaintiffs had not agreed to a settlement in principle as of October 31, 2025. The settlement funded in 2022 had already resolved the claims of more than 99 percent of the approximately 36,000 individual plaintiffs. The filing described the remaining status of the private lawsuits several years after the principal agreement. Regulatory proceedings involving the storage facility continued separately.
In response to the biennial assessment, SoCalGas filed Application 26-01-009 with the CPUC. The company asked the Commission not to reduce the maximum inventory at Aliso Canyon. It argued that a lower storage limit could affect gas-system reliability, electric service, and customer rates. SoCalGas also requested authority to increase inventory if future reliability or rate conditions required additional storage.
The proposed inventory limit drew protests, responses, technical filings, and written comments from participating groups. Some parties supported a 10-billion-cubic-foot reduction and argued that regional demand and system modeling allowed a lower storage level. SoCalGas and others challenged assumptions involving pipeline availability, receipt-point use, weather events, gas prices, and electricity demand. Competing technical and economic analyses were presented during an April 2026 workshop and in later filings.
The CPUC issued a scoping memo identifying the issues to be considered in Application 26-01-009. The proceeding will determine whether Aliso Canyon’s current maximum storage level should remain unchanged or be reduced by a specified amount, and whether the biennial assessment process should be modified. The Commission declined to consider SoCalGas’s request for authority to increase maximum inventory because an increase could require a higher operating pressure that CalGEM had not been asked to evaluate. The ruling also established a schedule for testimony, possible evidentiary hearings, and later briefing during 2026.
Court:
Superior Court of California, County of Los Angeles
Case Name:
Southern California Gas Leak Cases
Gas Leak
Methane
Corrosion Engineering
Air Pollution
Environmental Contamination
Environmental Toxicology
Exposure Assessments
Property Valuation
Damages Calculations
Well construction
A failed underground storage well at Southern California Gas Company’s Aliso Canyon facility released natural gas into the Porter Ranch area of Los Angeles for nearly four months. The release began at well SS-25 on October 23, 2015, and continued until crews brought the well under control in February 2016. California regulators estimated that about 109,000 metric tons of methane entered the atmosphere. Approximately 15,000 residents temporarily relocated, two nearby schools moved students and staff, and community members reported odors, headaches, nausea, nosebleeds, breathing problems, and residue on homes and outdoor surfaces.
The Aliso Canyon gas leak led to several connected legal proceedings rather than one lawsuit with a single outcome. Residents pursued bodily injury, nuisance, relocation, and property-loss claims, while nearby businesses sought compensation for lost income. State and local agencies brought separate enforcement actions, and the California Public Utilities Commission examined SoCalGas operations, storage practices, and customer-rate treatment. SoCalGas and its parent company, Sempra, later agreed to provide up to $1.8 billion to settle claims involving approximately 36,000 individual plaintiffs.
SoCalGas detected an uncontrolled natural gas release from Standard Sesnon well 25, commonly known as SS-25, at the Aliso Canyon underground storage facility. Gas passed through a damaged section of the well casing and moved toward the surface through the surrounding ground. The company began a top-kill operation the next day in an effort to control the well from above. Seven top-kill attempts made between October 24 and December 22 failed to stop the flow.
The Los Angeles County Department of Public Health directed SoCalGas to offer temporary relocation assistance to area residents affected by odors from the Aliso Canyon site. Residents had reported strong odors and symptoms that included headaches, nausea, dizziness, nosebleeds, and breathing complaints. About 15,000 people eventually moved into temporary housing. Students and staff from two nearby schools were also transferred to other campuses.
As the release continued, residents began filing claims involving bodily injury, nuisance, trespass, emotional distress, relocation expenses, cleaning costs, loss of property use, and reduced real estate values. Some residents also reported residue on homes, vehicles, outdoor furniture, landscaping, and other property. These claims later became part of coordinated civil proceedings in Los Angeles County Superior Court.
Governor Edmund G. Brown Jr. declared a state of emergency in Los Angeles County while the release remained uncontrolled. The proclamation directed state agencies to assist with containment, methane monitoring, public-health measures, resident communication, and underground storage-well oversight. It also called for stronger inspection, testing, and risk-management requirements. State regulators continued supervising containment work and reviewing conditions at Aliso Canyon.
After drilling a relief well, crews gained control of the release on February 11, 2016, by pumping heavy fluids into SS-25. Cement was then placed inside the well to form a permanent barrier. On February 18, the California Department of Conservation confirmed that testing found no continuing gas movement. The confirmation process included temperature and noise logs, fluid-level monitoring, and a cement-bond test.
Hundreds of lawsuits were brought together in Los Angeles County Superior Court under Southern California Gas Leak Cases, JCCP No. 4861. The coordinated litigation included resident claims, property disputes, business claims, and other actions arising from the release. The pleaded causes of action included negligence, negligence per se, public and private nuisance, trespass, strict liability, inverse condemnation, emotional distress, wrongful death, and fraudulent concealment. Common discovery, motions, settlement procedures, and other pretrial matters were managed through the coordinated proceeding.
Before limited injection resumed, California regulators completed safety reviews of wells proposed for renewed operation. Wells returning to service were required to operate through interior tubing rather than through the space between the tubing and outer casing. Pressure limits, testing duties, monitoring requirements, and other operating conditions were also imposed. SoCalGas resumed limited gas injections by the end of July 2017.
The Los Angeles County Superior Court approved a $119.5 million settlement between SoCalGas and several state and local government agencies. The participating agencies included the California Attorney General, California Air Resources Board, Los Angeles City Attorney, and County of Los Angeles. Funds were allocated to methane mitigation, air monitoring, public-health research, community programs, civil penalties, and government response costs. SoCalGas also agreed to maintain fence-line methane monitoring, create an internal facility safety committee, and retain an independent safety ombudsman.
Blade Energy Partners completed an independent investigation into the cause of the SS-25 failure. Investigators found that microbial corrosion damaged the exterior of the outer seven-inch casing where the metal was exposed to groundwater. The damage led to an axial rupture in the casing. The review also identified weaknesses in earlier casing-leak investigations, well-integrity risk assessments, external corrosion protection, well-control planning, and continuous pressure monitoring.
In Southern California Gas Leak Cases, 7 Cal. 5th 391, the California Supreme Court considered negligence claims brought by businesses near Porter Ranch. The businesses alleged that resident relocations reduced customer traffic and caused lost income, but they did not claim bodily injury or physical damage to property they owned. The court ruled that SoCalGas did not owe them a negligence duty covering those purely economic losses.
The decision applied to the business plaintiffs’ claims for lost income. It did not resolve resident claims involving bodily injury, nuisance, trespass, loss of use, or alleged property conditions. The court affirmed the dismissal of the business negligence claims.
SoCalGas and Sempra entered into an agreement to resolve approximately 390 lawsuits involving about 36,000 individual plaintiffs. The settlement provided up to $1.8 billion for claims connected to the Aliso Canyon release. Covered allegations included bodily injury, property loss, relocation expenses, nuisance, emotional distress, lost earnings, and related damages. Participating plaintiffs were required to release their claims against the companies and other covered parties.
A separate $40 million agreement addressed claims brought on behalf of certain property owners and lessors. SoCalGas and Sempra also reached a smaller settlement involving the named plaintiffs in the proposed business class action. Each agreement used its own payment and claims procedures.
More than 99 percent of the individual plaintiffs submitted accepted releases and joined the settlement. SoCalGas paid approximately $1.79 billion under the agreement during 2022. Most coordinated individual lawsuits ended through the settlement process rather than through a single trial. A limited number of plaintiffs continued to pursue claims outside the main agreement.
A separate settlement approved by the California Public Utilities Commission addressed SoCalGas operations and practices connected to the release. For purposes of the agreement, SoCalGas acknowledged one violation of California Public Utilities Code section 451. The resolution included a $105.1 million financial assessment, reduced by a $34.1 million credit for earlier methane-mitigation spending. The remaining $71 million was directed to the Aliso Canyon Recovery Account.
The agreement also covered refunds, reimbursements, and expenses that SoCalGas could not collect from utility customers. Those expenses included costs tied to resident relocations, private litigation, government settlements, outside legal work, and the independent investigation. The CPUC closed that regulatory investigation after approving the settlement.
The CPUC decided that Aliso Canyon would remain open while regional gas demand, electric reliability, infrastructure, storage needs, and customer costs remained under review. The decision kept the facility’s maximum storage level below its capacity before the 2015 release. It also created a process for examining possible storage reductions every two years. A projected peak-day gas-demand threshold was adopted for beginning further review of possible closure.
The first Aliso Canyon biennial assessment found that projected gas demand remained above the threshold for considering full closure. CPUC Energy Division staff recommended keeping the facility available for winter 2025–2026 and summer 2026. The assessment also proposed reducing the maximum inventory by 10 billion cubic feet, from 68.6 to 58.6 billion cubic feet. Staff stated that a smaller reduction or no reduction could also be considered because the economic analysis did not fully account for later forecasts of higher gas prices during winter 2026–2027.
A Sempra filing reported that only three individual plaintiffs had not agreed to a settlement in principle as of October 31, 2025. The settlement funded in 2022 had already resolved the claims of more than 99 percent of the approximately 36,000 individual plaintiffs. The filing described the remaining status of the private lawsuits several years after the principal agreement. Regulatory proceedings involving the storage facility continued separately.
In response to the biennial assessment, SoCalGas filed Application 26-01-009 with the CPUC. The company asked the Commission not to reduce the maximum inventory at Aliso Canyon. It argued that a lower storage limit could affect gas-system reliability, electric service, and customer rates. SoCalGas also requested authority to increase inventory if future reliability or rate conditions required additional storage.
The proposed inventory limit drew protests, responses, technical filings, and written comments from participating groups. Some parties supported a 10-billion-cubic-foot reduction and argued that regional demand and system modeling allowed a lower storage level. SoCalGas and others challenged assumptions involving pipeline availability, receipt-point use, weather events, gas prices, and electricity demand. Competing technical and economic analyses were presented during an April 2026 workshop and in later filings.
The CPUC issued a scoping memo identifying the issues to be considered in Application 26-01-009. The proceeding will determine whether Aliso Canyon’s current maximum storage level should remain unchanged or be reduced by a specified amount, and whether the biennial assessment process should be modified. The Commission declined to consider SoCalGas’s request for authority to increase maximum inventory because an increase could require a higher operating pressure that CalGEM had not been asked to evaluate. The ruling also established a schedule for testimony, possible evidentiary hearings, and later briefing during 2026.
Petroleum Engineering Expert Witness
A petroleum engineering expert could reconstruct the operation and condition of SS-25 by reviewing its casing and tubing configuration, pressure history, storage activity, failed top-kill attempts, and relief-well procedures. That review could address how gas escaped and whether available inspection, monitoring, or well-control measures might have detected or limited the failure.
Materials Science Expert Witness
Materials testing could focus on the seven-inch casing rupture, exterior metal loss, groundwater contact, microbial corrosion, and the corrosion-control practices in place before the release. The expert could also evaluate whether wall-thickness testing, coatings, cathodic protection, or other inspection methods were capable of identifying the developing damage.
Air Quality Expert Witness
An air-quality expert could use methane readings, odorant data, wind patterns, weather records, emission estimates, and monitoring results from Porter Ranch and nearby communities. Atmospheric modeling could then estimate where released substances traveled, how concentrations changed over time, and which locations may have experienced measurable exposure.
Toxicology Expert Witness
A toxicologist could compare reported symptoms with estimated exposure levels, medical histories, treatment records, prior conditions, and other possible causes. The assessment could examine whether the substances, concentrations, locations, and exposure periods supported by the evidence are consistent with individual health complaints.
Property Damage Expert Witness
A property-condition assessment could document residue, staining, odor retention, and other reported effects on homes, exterior surfaces, landscaping, vehicles, and personal property. The expert could also evaluate cleaning methods, restoration needs, repair costs, loss of use, and whether the observed conditions are consistent with substances released during the Aliso Canyon incident.
JCCP No. 4861 Coordinated Common Pretrial Issues
The Southern California Gas Leak Cases, JCCP No. 4861, placed numerous Aliso Canyon lawsuits before one Los Angeles County Superior Court for coordinated management. The court could address common discovery, motions, settlement procedures, and other pretrial matters without converting every plaintiff’s allegations into one claim. Individual issues involving exposure, medical history, property conditions, relocation costs, and damages remained separate.
Each Plaintiff Group Pursued Different Claims
Residents, property owners, businesses, and government agencies sought different forms of relief. Resident claims included alleged bodily injury, nuisance, trespass, relocation expenses, and property losses, while nearby businesses sought income allegedly lost after customers relocated. The California Supreme Court’s ruling on purely economic business losses did not decide the resident bodily injury or property claims.
The Private Resolution Was a Settlement, Not a Single Damages Verdict
The agreement covering approximately 36,000 individual plaintiffs created a process for reviewing and allocating claims rather than awarding the same amount to every person. Payments depended on the procedures and categories established under the settlement. Because the claims ended through negotiated releases, no single jury verdict determined liability or damages for all participating plaintiffs.
CPUC Cost Restrictions Were Separate From Plaintiff Compensation
The CPUC proceeding addressed utility compliance, financial assessments, refunds, and the treatment of leak-related expenses in customer rates. SoCalGas was not permitted to recover several categories of costs from utility customers, including expenses tied to resident relocations, private litigation, government agreements, outside legal work, and the root-cause investigation. These restrictions were separate from payments made to individual plaintiffs.
Facility Operations Remain in a Separate Regulatory Proceeding
The permanent sealing of SS-25 did not close the entire Aliso Canyon storage facility. Other wells later returned to limited operation under testing, pressure, monitoring, and inventory requirements. The continuing CPUC proceeding concerns storage capacity, regional gas demand, pipeline conditions, electric reliability, customer rates, and possible future reductions in the facility’s use.
The Aliso Canyon matter produced several separate legal and regulatory outcomes. An independent investigation attributed the SS-25 failure to microbial corrosion that caused an exterior casing rupture, the California Supreme Court held that the business plaintiffs could not recover purely economic losses through negligence claims, and SoCalGas paid approximately $1.79 billion to resolve nearly all individual plaintiff lawsuits. Regulatory attention later turned to the future of the storage facility, with the CPUC adopting biennial reviews, considering a lower maximum inventory, and reviewing SoCalGas’s 2026 challenge to the proposed reduction. SS-25 remains permanently sealed, while the larger Aliso Canyon facility continues to operate under testing, storage, and monitoring requirements.
Was the $1.8 billion Aliso Canyon payment a court verdict?
No. SoCalGas and Sempra agreed to provide up to $1.8 billion through a negotiated settlement covering approximately 36,000 individual plaintiffs. The agreement resolved most claims without a jury deciding liability or awarding one uniform amount to every claimant.
What did the California Supreme Court decide in the Aliso Canyon litigation?
The court ruled that nearby businesses could not recover lost income through negligence claims when they did not allege bodily injury or physical damage to their own property. The decision did not resolve the separate bodily injury, nuisance, trespass, relocation, or property claims brought by residents.
Did every Aliso Canyon plaintiff join the private settlement?
More than 99 percent of the individual plaintiffs submitted accepted releases and participated in the settlement. A small number of plaintiffs remained outside the main agreement and could continue pursuing their claims separately.
Why did Aliso Canyon reopen after well SS-25 was sealed?
SS-25 was permanently sealed, but it was only one well within the larger underground storage facility. Other wells later returned to limited operation after safety testing, pressure restrictions, monitoring requirements, and regulatory approval.
What remains unresolved in the Aliso Canyon proceedings?
The principal private lawsuits have largely ended, but the future storage capacity of the facility remains under CPUC review. The current proceeding addresses whether maximum inventory should be reduced and how any change could affect gas supply, electric reliability, and customer rates.
Petroleum Engineering Expert Witness
A petroleum engineering expert could reconstruct the operation and condition of SS-25 by reviewing its casing and tubing configuration, pressure history, storage activity, failed top-kill attempts, and relief-well procedures. That review could address how gas escaped and whether available inspection, monitoring, or well-control measures might have detected or limited the failure.
Materials Science Expert Witness
Materials testing could focus on the seven-inch casing rupture, exterior metal loss, groundwater contact, microbial corrosion, and the corrosion-control practices in place before the release. The expert could also evaluate whether wall-thickness testing, coatings, cathodic protection, or other inspection methods were capable of identifying the developing damage.
Air Quality Expert Witness
An air-quality expert could use methane readings, odorant data, wind patterns, weather records, emission estimates, and monitoring results from Porter Ranch and nearby communities. Atmospheric modeling could then estimate where released substances traveled, how concentrations changed over time, and which locations may have experienced measurable exposure.
Toxicology Expert Witness
A toxicologist could compare reported symptoms with estimated exposure levels, medical histories, treatment records, prior conditions, and other possible causes. The assessment could examine whether the substances, concentrations, locations, and exposure periods supported by the evidence are consistent with individual health complaints.
Property Damage Expert Witness
A property-condition assessment could document residue, staining, odor retention, and other reported effects on homes, exterior surfaces, landscaping, vehicles, and personal property. The expert could also evaluate cleaning methods, restoration needs, repair costs, loss of use, and whether the observed conditions are consistent with substances released during the Aliso Canyon incident.
JCCP No. 4861 Coordinated Common Pretrial Issues
The Southern California Gas Leak Cases, JCCP No. 4861, placed numerous Aliso Canyon lawsuits before one Los Angeles County Superior Court for coordinated management. The court could address common discovery, motions, settlement procedures, and other pretrial matters without converting every plaintiff’s allegations into one claim. Individual issues involving exposure, medical history, property conditions, relocation costs, and damages remained separate.
Each Plaintiff Group Pursued Different Claims
Residents, property owners, businesses, and government agencies sought different forms of relief. Resident claims included alleged bodily injury, nuisance, trespass, relocation expenses, and property losses, while nearby businesses sought income allegedly lost after customers relocated. The California Supreme Court’s ruling on purely economic business losses did not decide the resident bodily injury or property claims.
The Private Resolution Was a Settlement, Not a Single Damages Verdict
The agreement covering approximately 36,000 individual plaintiffs created a process for reviewing and allocating claims rather than awarding the same amount to every person. Payments depended on the procedures and categories established under the settlement. Because the claims ended through negotiated releases, no single jury verdict determined liability or damages for all participating plaintiffs.
CPUC Cost Restrictions Were Separate From Plaintiff Compensation
The CPUC proceeding addressed utility compliance, financial assessments, refunds, and the treatment of leak-related expenses in customer rates. SoCalGas was not permitted to recover several categories of costs from utility customers, including expenses tied to resident relocations, private litigation, government agreements, outside legal work, and the root-cause investigation. These restrictions were separate from payments made to individual plaintiffs.
Facility Operations Remain in a Separate Regulatory Proceeding
The permanent sealing of SS-25 did not close the entire Aliso Canyon storage facility. Other wells later returned to limited operation under testing, pressure, monitoring, and inventory requirements. The continuing CPUC proceeding concerns storage capacity, regional gas demand, pipeline conditions, electric reliability, customer rates, and possible future reductions in the facility’s use.
The Aliso Canyon matter produced several separate legal and regulatory outcomes. An independent investigation attributed the SS-25 failure to microbial corrosion that caused an exterior casing rupture, the California Supreme Court held that the business plaintiffs could not recover purely economic losses through negligence claims, and SoCalGas paid approximately $1.79 billion to resolve nearly all individual plaintiff lawsuits. Regulatory attention later turned to the future of the storage facility, with the CPUC adopting biennial reviews, considering a lower maximum inventory, and reviewing SoCalGas’s 2026 challenge to the proposed reduction. SS-25 remains permanently sealed, while the larger Aliso Canyon facility continues to operate under testing, storage, and monitoring requirements.
Was the $1.8 billion Aliso Canyon payment a court verdict?
No. SoCalGas and Sempra agreed to provide up to $1.8 billion through a negotiated settlement covering approximately 36,000 individual plaintiffs. The agreement resolved most claims without a jury deciding liability or awarding one uniform amount to every claimant.
What did the California Supreme Court decide in the Aliso Canyon litigation?
The court ruled that nearby businesses could not recover lost income through negligence claims when they did not allege bodily injury or physical damage to their own property. The decision did not resolve the separate bodily injury, nuisance, trespass, relocation, or property claims brought by residents.
Did every Aliso Canyon plaintiff join the private settlement?
More than 99 percent of the individual plaintiffs submitted accepted releases and participated in the settlement. A small number of plaintiffs remained outside the main agreement and could continue pursuing their claims separately.
Why did Aliso Canyon reopen after well SS-25 was sealed?
SS-25 was permanently sealed, but it was only one well within the larger underground storage facility. Other wells later returned to limited operation after safety testing, pressure restrictions, monitoring requirements, and regulatory approval.
What remains unresolved in the Aliso Canyon proceedings?
The principal private lawsuits have largely ended, but the future storage capacity of the facility remains under CPUC review. The current proceeding addresses whether maximum inventory should be reduced and how any change could affect gas supply, electric reliability, and customer rates.
Gas Leak
Methane
Corrosion Engineering
Air Pollution
Environmental Contamination
Environmental Toxicology
Exposure Assessments
Property Valuation
Damages Calculations
Well construction
Oil and Gas
Electrical Engineering, +4
Oil and Gas
Pipelines, +4
Oil and Gas