Stringfellow Acid Pits Superfund CA

// Risk Intelligence

// Strategic Context

The Stringfellow Acid Pits emerged from the rapid industrialization of Southern California during the post-World War II economic boom, when environmental regulations remained minimal and industrial waste disposal options were scarce. Located in the unincorporated community of Glen Avon in Riverside County, this 17-acre site became operational in 1956 as a private industrial waste disposal facility owned by James Stringfellow. The location was strategically chosen for its proximity to the expanding aerospace, chemical, and manufacturing industries of Los Angeles County while being situated in a less populated area where land costs remained affordable. The facility existed to serve a critical industrial need during California's explosive growth period, accepting liquid industrial waste that would otherwise have no legal disposal pathway. The geological characteristics of the site, including its position above fractured bedrock and seasonal drainage patterns, made it fundamentally unsuitable for long-term containment of hazardous materials, yet these same features made it attractive to operators seeking inexpensive disposal options.

// What This Facility Does

The Stringfellow Acid Pits operated as a liquid industrial waste disposal facility from 1956 to 1972, accepting over 34 million gallons of hazardous chemical waste during its operational lifetime. The site received a deadly cocktail of industrial byproducts including chlorinated solvents, pesticides including DDT, chromium compounds, sulfuric acid, heavy metals such as arsenic and lead, and various organic chemicals from aerospace manufacturing processes. Companies throughout Southern California, including major defense contractors and chemical manufacturers, transported their liquid waste to Stringfellow for disposal at rates significantly below alternative treatment options. The facility operated using unlined evaporation ponds, essentially large earthen basins where liquid waste was deposited with the expectation that evaporation and seepage would eliminate the volume. During California's rainy seasons, these ponds would overflow, and operators deliberately discharged the contaminated contents into Pyrite Creek and the Santa Ana River watershed to prevent complete inundation of the facility. This discharge practice continued for years, creating a direct pathway for industrial toxins to reach downstream communities and groundwater supplies throughout the region.

// Why This Location Is Strategically Important

Glen Avon's position in the Santa Ana River watershed places the Stringfellow site at a critical juncture for Southern California's water resources and population centers. The facility sits approximately 50 miles southeast of downtown Los Angeles and 20 miles northwest of the city of Riverside, positioning it within the rapidly developing Inland Empire region that now houses over 4.6 million residents. The site's location above fractured bedrock formations allowed contaminants to penetrate directly into groundwater aquifers that serve multiple municipalities across Riverside and San Bernardino counties. Pyrite Creek, which received direct discharges from the facility, flows into the Santa Ana River, a major watershed serving millions of Southern Californians. The proximity to Interstate 15, a critical north-south transportation corridor connecting Los Angeles to Las Vegas and beyond, means that any major incident requiring evacuation or emergency response would directly impact one of the region's most vital transportation arteries. The surrounding area has transformed from rural agricultural land in the 1950s to dense suburban development, with thousands of residents now living within a mile of the contaminated site and its ongoing remediation operations.

// Real-World Risk Scenarios

Seismic activity represents the most severe immediate threat to the Stringfellow site, given its location within 15 miles of the San Andreas Fault system and numerous smaller fault lines that regularly generate earthquakes throughout the region. A major earthquake could compromise the existing containment systems, including the slurry wall and cap that currently prevent direct surface contact with contaminated soil, potentially releasing concentrated toxic materials into Pyrite Creek during the critical hours when emergency response resources are stretched thin across the region. Flash flooding during intense winter storm events poses another significant risk scenario, as the site's drainage systems could be overwhelmed by rapid runoff from the surrounding hills, potentially carrying contaminated sediments into downstream communities that experienced similar toxic flooding in the 1970s. Deliberate sabotage of the remediation infrastructure, including the groundwater treatment systems and monitoring wells, could go undetected for weeks while contaminated groundwater continues flowing toward municipal water supplies, creating a delayed-onset public health crisis affecting hundreds of thousands of residents. Climate change-driven extreme weather events, including prolonged drought followed by intense precipitation, could destabilize the site's engineered containment systems, causing differential settling of contaminated materials and creating new pathways for contaminant migration into previously clean groundwater zones.

// Impact Radius

A catastrophic failure at Stringfellow would immediately threaten the 15,000 residents of Glen Avon and Jurupa Valley who live within three miles of the site and rely on local groundwater wells for their drinking water supply. The contamination plume already extends several miles from the original facility, and any major breach could accelerate the spread of toxins throughout the regional groundwater system that serves over 200,000 residents across multiple water districts in Riverside County. Agricultural operations in the surrounding area, including dairy farms and crop production that contribute to California's food supply, would face immediate shutdown orders if contamination spreads beyond current containment boundaries. The economic impact would cascade through the Inland Empire's logistics and distribution network, as the region serves as a critical hub for goods movement between the ports of Los Angeles and Long Beach and consumers throughout the western United States. Recovery time from a major contamination event would span decades, similar to other Superfund sites where groundwater remediation requires 30 to 50 years of continuous treatment. The psychological and social impacts on affected communities would persist even longer, as residents face ongoing uncertainty about long-term health effects from exposure to the complex mixture of carcinogens and toxic substances that characterize the Stringfellow contamination.

// Historical Context

The Stringfellow disaster parallels other catastrophic industrial waste sites across the United States, most notably the Love Canal incident in New York where residential development occurred directly atop buried chemical waste, forcing the evacuation of hundreds of families and spurring the creation of the federal Superfund program. The Berkeley Pit in Montana demonstrates the long-term challenges of toxic waste remediation, where a former copper mine filled with contaminated water continues to threaten regional water supplies more than 40 years after mining operations ceased. The Lipari Landfill in New Jersey, another early Superfund site, showed how improper industrial waste disposal in fractured bedrock formations can contaminate groundwater across vast areas, requiring ongoing treatment systems that operate for decades at costs exceeding hundreds of millions of dollars. These precedents demonstrate that sites like Stringfellow represent permanent additions to the nation's infrastructure burden, requiring continuous monitoring and active remediation that cannot be abandoned without catastrophic public health consequences.

// Risk Assessment

Among EPA Superfund sites nationally, Stringfellow ranks in the highest risk category due to its combination of extremely hazardous waste types, fractured geology that accelerates contaminant transport, proximity to dense population centers, and location within a seismically active region. The site's position in an arid climate creates unique challenges compared to Superfund sites in other regions, as prolonged drought conditions can concentrate contaminants while intense storm events can mobilize toxins rapidly across large areas. The facility's risk profile exceeds that of many industrial Superfund sites because residential development occurred adjacent to the contaminated area before the extent of the contamination was fully understood, creating ongoing exposure pathways that cannot be eliminated through engineering controls alone. The age of the contamination, dating back over 50 years, means that many of the original industrial chemicals have broken down into secondary compounds that may be equally toxic but more difficult to detect and treat using conventional remediation technologies.

// Bottom Line

Every American should understand that Stringfellow represents the true long-term cost of inadequate environmental oversight during our industrial expansion. This site will require active management and millions of dollars in annual treatment costs for the remainder of this century and beyond, while thousands of families continue living with the health consequences of decisions made decades before they were born. The facility serves as a critical reminder that environmental contamination creates permanent national security vulnerabilities that cannot be eliminated, only managed, making it essential that we prevent similar disasters rather than simply budgeting for cleanup efforts that span multiple generations.

// Evacuation & Shelter Guidance

// Counties Within Risk Zone