Multiple Chemical Releases at Silfab Solar
Fort Mill, South Carolina
Incident Summary
Between March 3 and March 5, 2026, the Silfab Solar manufacturing facility located at 7149 Logistics Lane in Fort Mill experienced two distinct chemical releases during its startup and commissioning phase.
March 3, 2026: An estimated 300 gallons of a solution containing potassium hydroxide (KOH) was released. While initial reports suggested a larger volume of 1,500 gallons, the figure was revised downward. The release reached an onsite retention pond.
March 5, 2026: A second incident involved the release of hydrofluoric acid (HF). This leak reportedly originated from a bulkhead fitting on a storage tank. York County officials stated the acid was successfully captured by the facility's secondary containment system.
Due to the facility’s proximity to Flint Hill Elementary School (less than 1,000 feet away), the school district dismissed students early following the March 5 incident. On March 5, 2026, the South Carolina Department of Environmental Services (SCDES) issued a directive for Silfab Solar to cease all operations and stop receiving chemical shipments pending a joint investigation with the EPA.
Facility and Industry Description
The Silfab Solar facility is a high-volume solar cell manufacturing plant. The industry utilizes specialized chemical processes for:
Silicon Wafer Etching: Using hydrofluoric acid to remove impurities and texture the surface of silicon wafers.
Cleaning: Utilizing caustic solutions like potassium hydroxide to prepare surfaces for processing.
The plant is situated in a light industrial zone that has faced local opposition due to its location near residential areas and schools.
Speculation on Cause and Contributing Factors
The specific root cause of the leaks is currently under investigation by state and federal regulators.
The incidents occurred during the startup and commissioning phase, a period typically associated with higher risks of equipment failure as systems are pressurized and chemically loaded for the first time.
A "hazardous condition" warning posted at the site identified a leak at a bulkhead corner of an HF tank, suggesting a potential mechanical seal failure or improper installation of tank fittings.
The recurring nature of the leaks (two within 48 hours) may indicate systemic issues with the facility’s piping integrity or quality control protocols during construction.
Industry Standards Note: NFPA 400
NFPA 400 (Hazardous Materials Code) provides the framework that likely governed the facility's safety design.
Secondary Containment: NFPA 400 requires secondary containment systems to hold the volume of the largest tank plus a freeboard for fire protection water. In this incident, the containment reportedly prevented the HF from migrating offsite.
Mechanical Integrity: The standard emphasizes the need for routine inspections and testing of "highly toxic" and "toxic" material systems (like HF). Adherence to rigorous pre-startup safety reviews (PSSR) as outlined in NFPA 400 or OSHA PSM standards might have identified the weak bulkhead fitting before the system was fully charged.
Top Three Sources
South Carolina Department of Environmental Services (SCDES): Directive to Cease Operations at Silfab Solar (March 5, 2026).
York County Government News: "Silfab Incident Update" official statements (March 3 & March 5, 2026).
WRHI News: "SC Regulators Order Silfab Solar to Cease Operations After Second Chemical Leak" (March 5, 2026).
This report includes preliminary information regarding the specific failure point of the storage tank and speculative links between the two incidents.