The dyke area refers to the specific footprint or perimeter encompassed by a protective barrier, commonly known as a dike or berm, which is constructed around tank storage areas. Its primary purpose is to provide secondary containment, ensuring that any spills, leaks, or ruptures from the primary storage tanks are safely confined within this designated space.
Understanding Dike Areas
A dike (or dyke) area is fundamentally a safety and environmental protection measure. It's the region specifically included within the protective dike around tank storage areas. This design is crucial for facilities handling hazardous liquids, fuels, chemicals, or other materials that could cause environmental damage or safety hazards if released. The term "dike area" defines the spatial extent of this critical containment zone.
Why Dike Areas Are Essential
- Environmental Protection: Prevents spilled substances from contaminating soil, groundwater, and surface water bodies. This is vital for preserving ecosystems and public health.
- Safety: Reduces the risk of fires, explosions, or exposure to hazardous materials by containing spills and preventing them from spreading to other areas or igniting.
- Regulatory Compliance: Many government agencies and environmental regulations, such as those overseen by the U.S. Environmental Protection Agency (EPA), mandate secondary containment for bulk storage of certain materials.
- Asset Protection: Confines spills, preventing damage to adjacent equipment, infrastructure, and property.
Key Components and Design Considerations
Effective dike areas are engineered with several critical components and design principles in mind to ensure their functionality and integrity.
Barrier Construction
The dike itself can be constructed from various materials, depending on the stored substance, site conditions, and regulatory requirements:
- Earthen Berms: Common for large, outdoor tank farms, these are cost-effective but require a larger footprint.
- Concrete Walls: Offer high durability, less footprint, and can be prefabricated or cast-in-place.
- Steel Walls: Used for specific applications, often where space is limited or for temporary containment.
- Combination Systems: Dikes may integrate different materials or technologies, including impermeable liners (e.g., geomembranes, compacted clay) beneath the dike area to prevent seepage into the ground.
Containment Capacity
A fundamental design requirement is that the dike area must be capable of containing a sufficient volume of spilled material. Regulations often stipulate that the secondary containment system must hold:
- 110% of the volume of the largest single tank within the dikes, plus any precipitation that could accumulate.
- Alternatively, for multiple tanks, it might be 110% of the largest tank or 10% of the aggregate volume of all tanks, whichever is greater, depending on local regulations.
Drainage Systems
Accumulated rainwater within the dike area must be managed without compromising its containment function. This typically involves:
- Manual Drainage: A valve-controlled sump or drain that allows stormwater to be released after inspection, ensuring no contaminants are present.
- Automated Systems: Pumping systems that activate when a certain water level is reached, often equipped with oil/water separators and monitoring to prevent hazardous discharge.
Access and Safety
Safe access for personnel and equipment within the dike area is crucial for inspections, maintenance, and emergency response. This includes:
- Ramps or steps for easy entry and exit.
- Gates or openings designed to maintain containment integrity.
- Adequate lighting and ventilation, especially for enclosed dike areas.
Here's a summary of key design elements:
| Element | Description | Importance |
|---|---|---|
| Barrier Type | Earthen berm, concrete wall, steel wall, combination with liners | Determines structural integrity and space utilization. |
| Capacity | Typically 110% of largest tank's volume (or aggregate volume) plus rainfall | Ensures complete containment of spills. |
| Liner (Optional) | Impermeable layer (geomembrane, compacted clay) below the contained area | Prevents soil and groundwater contamination. |
| Drainage | Manual valves, sumps, or automated pump systems for rainwater removal | Manages accumulated precipitation without releasing contaminants. |
| Access Points | Ramps, stairs, gates for personnel and equipment | Facilitates routine operations and emergency response. |
| Materials | Resistance to stored chemicals, UV, weather conditions | Ensures long-term effectiveness and prevents material degradation. |
Regulatory Compliance and Importance
Adhering to regulations concerning dike areas is paramount for any facility storing bulk liquids. In the United States, the Spill Prevention, Control, and Countermeasure (SPCC) rule is a cornerstone. It requires facilities to develop and implement plans to prevent oil spills, and secondary containment, including dike areas, is a core component of these plans.
Key benefits of robust regulatory compliance include:
- Reduced Liability: Minimizes fines, penalties, and legal action associated with environmental contamination.
- Enhanced Public Image: Demonstrates a commitment to environmental stewardship and community safety.
- Operational Continuity: Prevents costly shutdowns and cleanup operations resulting from uncontrolled spills.
- Improved Safety Culture: Fosters a proactive approach to risk management and employee well-being.
Practical Insights and Maintenance
Effective maintenance is crucial for the long-term integrity and functionality of dike areas.
Best Practices for Dike Area Management:
- Regular Inspections: Conduct routine visual checks for cracks, erosion, vegetation growth, or signs of compromise in the barrier or liner. Inspect drainage systems for blockages.
- Vegetation Control: Keep the dike area free of excessive vegetation, which can compromise barrier integrity or obscure potential issues.
- Prompt Spill Response: Have a clear, practiced plan for responding to spills within the dike area, including appropriate cleanup materials and personnel training.
- Proper Drainage Management: Regularly check and safely discharge rainwater, ensuring it's free of contaminants before release or treatment.
- Structural Integrity: Address any signs of structural weakening in concrete or earthen dikes promptly to prevent failure.
By integrating well-designed and maintained dike areas, facilities can significantly mitigate risks associated with bulk liquid storage, safeguarding the environment, personnel, and assets.
