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Diesel Tank Spill Recovery Systems
1. Core Components of Spill Recovery Systems
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Containment Basins/Dikes: Perimeter barriers (e.g., concrete or steel walls) around
aboveground tanks (ASTs) that act as secondary storage.
For example, a 10,000-gallon tank requires a dike with a capacity of at least 110% of the tank’s volume (API 650 standard) to hold accidental spills.
- Sump Pumps and Drainage Systems: Low-point collection sumps within the containment area, connected to pumps or gravity drains. These channels direct spilled fuel to a recovery tank or treatment system.
- Automatic Shut-Off Valves: Sensors (e.g., float switches or pressure sensors) that trigger valves to close if fuel level in the containment basin rises above a threshold, preventing overflow.
- Absorbent Materials: Passive components like booms, pads, or granules (e.g., polypropylene) that soak up diesel from spills, often used in conjunction with mechanical systems.
2. Mechanisms During a Spill Event
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Stage 1: Initial Containment
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Dike/Secondary Containment: When diesel leaks from the tank (e.g., through a
faulty valve or ruptured pipe), it flows into the containment basin. The basin’s walls
physically block outward spread.
For instance, a spill from a fill port leak will pool within the dike, preventing soil or water contamination.
- Gravity-Driven Drainage: In sloped containment areas, fuel flows toward sumps via gravity. A typical sump might be a 50-gallon pit with a grated cover, positioned 6–12 inches below the basin floor to collect liquid.
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Dike/Secondary Containment: When diesel leaks from the tank (e.g., through a
faulty valve or ruptured pipe), it flows into the containment basin. The basin’s walls
physically block outward spread.
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Stage 2: Active Recovery
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Manual or Automatic Pumping
- Manual Operation: Personnel use portable submersible pumps to transfer spilled diesel from the sump to a recovery tank. This is common in smaller facilities.
- Automatic Systems: In larger installations, float-activated pumps (e.g., rated for 100 GPM) switch on when the fuel level in the sump reaches a preset height (e.g., 4 inches). The pump sends fuel through a pipeline to a dedicated recovery tank, which may include filters to remove debris.
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Oil-Water Separation (If Required): If the spill mixes with rainwater, the
recovery system may include a coalescent filter or clarifier.
For example, a cartridge filter with oleophilic media traps diesel while allowing water to drain to a separate retention pond, complying with EPA stormwater regulations (e.g., NPDES permits).
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Manual or Automatic Pumping
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Stage 3: Secondary Mitigation
- Absorbent Deployment: Workers deploy booms around the perimeter of the spill within the dike to prevent fuel from spreading to hard-to-reach areas. Granular absorbents (e.g., diatomaceous earth) are sprinkled on small spills to solidify the diesel, which is then swept up and disposed of as hazardous waste.
- Sealing Leaks: While recovery occurs, the source of the spill (e.g., a damaged fill hose or corroded tank fitting) is isolated. Valves are closed, and temporary repairs (e.g., epoxy patches or clamps) are applied before resuming operations.
3. Design Standards and Regulatory Compliance
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API 650 (Aboveground Storage Tanks):
Requires containment dikes to have a minimum capacity of 110% of the largest tank’s volume, with slopes directing spills to sumps.
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EPA SPCC Rule (USA):
Mandates spill prevention, control, and countermeasure plans for facilities with aboveground tanks storing ≥1,320 gallons of oil. Systems must include secondary containment and automated shut-off valves for fill lines.
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EN 13160 (Europe):
Specifies that marine fuel tanks on vessels must have spill recovery systems capable of handling 100% of the tank’s capacity within 30 minutes of a leak.
4. Maintenance and Testing
- Routine Inspections: Sump pumps are tested quarterly to ensure they activate at the correct liquid level. Absorbent materials are replaced annually or after use.
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Simulated Spill Drills: Facilities conduct drills (e.g., releasing 50 gallons of
water into the containment area) to test pump response times and drainage efficiency.
For example, a drill might measure if a 1,000-gallon spill is fully recovered within 2 hours, as required by OSHA.
5. Environmental and Safety Benefits
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Prevent Soil and Water Contamination: By containing diesel within the dike, they
reduce the risk of fuel seeping into groundwater or nearby streams,
which can cost $10,000–$1 million to remediate.
- Minimize Fire Hazards: Diesel vapors in an uncontained spill pose an ignition risk. Containment reduces vapor dispersion and limits exposure to ignition sources like static electricity or hot surfaces.