A key component of an integrated approach to pollution prevention is to minimize accidental and incidental releases of toxic and hazardous materials to the atmosphere. These releases usually result in not only a waste of material, but also in the generation of contaminated soil, absorbent material, and contaminated product that has to be treated and disposed. A structured plan is absolutely necessary to assure control of systems and to verify that the goal of zero spills can be achieved.

Spills are caused by a number of common factors, but the most likely causes are:

• Mechanical failure
• Personnel error
• Fires and explosions
• Power failures, and
• Natural disasters such as tornadoes, earthquakes, and hurricanes

Since the great majority of spills result from the first two factors, which, to a large extent, also control the third factor, proper design and prevention measures can greatly reduce the incidence of spills. The following suggested measures go a long way toward laying the foundation for a system that will minimize occurrence of accidental spills:

• Good design
• Explicit and detailed operating and maintenance procedures
• Thorough training of all personnel
• Conscientious and timely maintenance of equipment and facilities
• Strict job responsibility and accountability
• Redundant process control and alarm monitoring systems

Other proactive and reactive processes should be implemented to minimize the occurrence, reoccurrence, and severity of spills that do occur. This includes investigating all spills to determine root cause; performing process hazard analyses to look at factors such as chemical interactions, maximum material inventories, materials compatibility, and failure scenarios; and developing spill action plans to be followed in the event of a spill. In addition, physical barriers should be used to contain spills and minimize environmental damage (contamination of soil, groundwater, or leakage into sewers or surface waters) in the event of a release. Such physical barriers include neutralizing agents and containment devices (booms) strategically located to be quickly deployed in the event of a spill.

Monitoring Systems

Knowledge and decision making are critical to taking appropriate action when an unusual circumstance presents itself. Instrumentation is the key to obtaining fast and accurate knowledge of the status of the process. Furthermore, redundancy of instrumentation is a vital component of any good spill prevention system. All critical instruments, such as drum or tank level sensors, should be duplicated, preferably with an instrument using a different means of sensing to avoid a double failure.

Control and accuracy of inventory by material balance may also indicate a spill is occurring. Alarm setpoints should be chosen to minimize false alarms while maintaining adequate response for true failures.

Piping Systems

Pipelines are often the site of major spills, typically because of equipment failure. Guidelines for designing, maintaining, and operating pipelines are as follows:

• A standard identification system should be developed for all pipelines to assure proper and accurate indication of the product flowing within each and every line. All lines should be marked and their markings maintained.
• Any product fill line entering a tank below the liquid level should have a check valve and isolation valve combination located close to the receiving tank in order to prevent massive backflow or siphoning of the material out of the tank. The isolation valve permits easy maintenance of the check valve as well as tight shutoff in the event of a transfer shutoff.
• Underground pipelines should be avoided. If lines must be underground, they should have protective coatings and wrappings, as well as cathodic protection to minimize corrosion. In addition, a section of the underground line should be exposed and inspected annually until the entire length of the line has been inspected over a period of years. Then the process should be continued from the original starting point.
• If a pipeline is taken out of service for an extended period of time, it should be marked, blind flanged, and isolated at both ends.
• Pipelines supported just off the ground, especially those using wood or makeshift shoes, should be avoided. Pipelines should be routed in designated pipe racks with standard pipe shoes at each support point.
• Stress analysis should be done for all piping subject to thermal cycling to avoid overstress and rupture during a cycle.
• Designers should minimize the number of inaccessible valves and flanges. All connects should undergo at least a regular quarterly visual inspection, at which time an assessment can be made of the general condition of the line, its support structure, and other components.
• Elevated pipe bridges should be used for road crossings and designed for the tallest regular vehicle traffic. Exceptional vehicular traffic should be notified of the crossing heights in order to allow time to make alternative arrangements.
• Pumping systems should be located in close proximity to storage tanks.
• Baffles, hard coatings, high alloys, long bends, or other means of abrasion resistant designs should be used for abrasive or erosive liquids.

Bulk Storage

• Underground tank use should be avoided unless adequate measures have been taken to assure integrity of the vessel by a combination of careful design, quality construction, conscientious maintenance, continuous monitoring, and periodic inspection.
• Material storage should only be done in vessels designed and constructed to meet the requirements of the stored material. Additionally, all vessels should be subjected to integrity testing by the most appropriate non-destructive means, e.g., x-ray, dye penetrant, etc. All tanks should also undergo hydrostatic testing as a new tank and following maintenance work.
• Thickness testing should be done periodically and compared to the vessel’s original thickness to track reduction due to corrosion.
• Tank farms for large volume storage should have a spill containment volume (e.g., pits, dikes, or curbs) equal to 110% of the volume of the largest tank.
• Drainage of rainwater from containment areas should be restricted to in-plant treatment, unless assurances such as locked valves, careful analysis of water, and monitoring of pumpouts are carried out.
• Fail-safe engineering designs should be used on all tanks: high and low audible alarms with redundancy directed to a constantly manned control station and high level pump cut-offs or valve shutoffs to stop flow at a predetermined liquid level to prevent overfilling of tanks.
• Visible product seeps or leaks from seams, cracks, or gaskets should be followed by immediate corrective action.
• Analytic devices (e.g., pH sensors) should be installed in wastewater sumps or other collection point for early warning of spilled material.

Implementation of spill prevention can result in a decrease in the generation of contaminated soil, absorbent material, and contaminated product that has to be treated and disposed. This benefit helps facilities meet the requirements of waste reduction under RCRA, 40 CFR 262, Appendix, and may also help facilities reduce their generator status and lessen the amount of regulations (i.e., recordkeeping, reporting, inspections, transportation, accumulation time, emergency prevention and preparedness, emergency response) they are required to comply with under RCRA, 40 CFR 262. Additionally, implementation of spill prevention techniques can decrease the need for reporting spills under 40 CFR 300.405.

The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.

Compatibility of materials should always be checked before putting a pipeline, vessel, or piece of mechanical equipment into service. This includes not only the bulk materials of each item, but also the gaskets, o-rings, coatings, liners, and seals. Consider cleanout conditions, especially high temperature conditions, which may cause two materials compatible at a lower temperature to be incompatible at an elevated temperature.

Consult your local health and safety personnel for assistance in developing a spill prevention plan where needed.

The benefits of spill prevention are:

• Raw materials and finished products are not wasted, lost or disposed;
• Damage to the environment is avoided if product losses are minimized; and
• Treatment and disposal costs are minimized while salable and useable product is maximized.

N/A

Spill prevention systems have definite costs; unfortunately, spill avoidance and the major costs and hazards that never manifest themselves are difficult, if not impossible, to quantify when trying to justify a spill prevention project on its economic merits. Sometimes historical cost data from past spills can be used in cost avoidance arguments. In any event, the costs and benefits of spill prevention systems must be weighed for each individual case.

Approval is controlled locally and should be implemented only after engineering approval has been granted. Major claimant approval is not required.