Liquid Waste Storage: Underground & Above-Ground Tank Options

Choosing the Right Tank for Liquid Waste Storage

Liquid waste storage requires tanks matched to waste characteristics (hazard class, volume, duration), site constraints, and regulations (EPA 40 CFR 264/265, state UST programs).

Underground Storage Tanks (USTs)

• Applications: Petroleum (gas stations), hazardous waste, wastewater, chemical storage.
• Construction: Double-walled (steel, fiberglass, composite) with interstitial monitoring. Corrosion protection (cathodic, lining).
• Regulation: EPA UST program (40 CFR 280): leak detection, spill/overfill protection, financial responsibility, operator training.
• Advantages: Space-saving, temperature stability, vandalism resistance, aesthetic.
• Disadvantages: Leak detection harder, installation/removal costly, soil/groundwater contamination risk.

Above-Ground Storage Tanks (ASTs)

• Types:
  • Shop-fabricated: Up to 50,000 gal; carbon steel, stainless, polyethylene, fiberglass.
  • Field-erected: >50,000 gal; API 650/620 standards.
  • Portable/Mobile: Totes (IBCs, 275–330 gal), drums (55 gal), tanker trailers, rail cars, frac tanks (21,000 gal).
• Secondary Containment (Mandatory): Impermeable dike/berm holding 110% of largest tank or 100% of total volume. Includes liners, concrete, steel.
• Regulation: EPA SPCC (40 CFR 112) for oil; RCRA for hazardous waste; API 653 inspection; NFPA 30 for flammables.
• Advantages: Visual inspection easy, leak detection simple, relocatable, lower install cost.
• Disadvantages: Space-intensive, weather exposure, vapor emissions, collision risk.

Specialized Systems

• Septic Tanks: Onsite wastewater treatment (anaerobic digestion + drainfield). Not for hazardous waste.
• Holding Tanks: Temporary storage (no treatment); pumped out periodically.
• Double-Walled with Leak Detection: Interstitial sensor (liquid, vacuum, pressure) – best practice for hazardous liquids.

Selection Criteria

Factor	Considerations
Waste compatibility	Chemical resistance (steel vs. poly vs. FRP vs. lined)
Volume & duration	Batch vs. continuous; permanent vs. temporary
Regulatory class	Hazardous (RCRA) vs. non-hazardous vs. petroleum
Site constraints	Space, groundwater depth, seismic, flood zone
Lifecycle cost	Install, inspect, maintain, close/remove