Containment and Diversionary Structures for SPCC Regulated Facilities

This section addresses the requirements of  40 CFR 112.7 (c) that requires containment related to storm water drainage.  For secondary containment of spills follow the link to Secondary Containment.   

The SPCC regulations require containment of storm water drainage from the operating areas of a facility to prevent oil spills and contaminated runoff from reaching storm drains, streams, ditches, rivers, bays, and other navigable waters.

Secondary containment and diversionary structures should be in place to prevent storm water contamination and to contain storm water that has been oil-contaminated from leaks around fuel dispensers, pipelines, valves, joints, transfer connections, and tanks.  Facilities should use dikes, berms, curbing, gutters, trenches, absorbent material, retention ponds, weirs, booms, and other barriers or equivalent preventive systems. 

Performance Based    SPCC requirements are performance-based, which permits facility owners and operators to substitute alternative forms of spill containment if the substitute provides substantially equivalent protection against discharges to navigable waters to that provided by the systems listed in 40 CFR 112.7(c).

Substantially equivalent containment systems may be possible for AST systems (e.g., small double-walled ASTs equipped with spill prevention devices) that generally have capacities of less than 12,000 gallons. Alternative containment systems may not be appropriate for tank systems larger than 12,000 gallons or for systems that consist of several tanks connected by manifolds or other piping arrangements that would permit a volume of oil greater than the capacity of one tank to be spilled as a result of a single system failure.

The secondary containment structure must be impervious and must prevent water and fuel from percolating through the soil, contaminating the soil and groundwater and possibly surfacing aboveground into navigable waters or adjoining shorelines.

Diked Areas  Facilities with outside operations most often use poured concrete walls or earthen berms to contain drainage and provide secondary containment for storage tanks and curbing and catchment basins for truck loading/unloading areas. These contained areas are referred to in the regulations as diked areas. Concrete and earthen dike containment structures around storage tanks may accumulate significant amounts of water. Drain lines, which must be watertight, are usually installed through the dike walls and are used to drain accumulated storm water from the diked area. These lines should be fitted with valves or other positive means of closure that are normally sealed closed and locked to prevent any oil discharges from escaping the diked area. The valves must be open-close manual valves; flapper valves are not acceptable.

The accumulated rainwater must be examined and determined to be free of oil contamination before diked areas are drained. If any oil sheen or accumulation of oil is observed, an alternate method of draining the diked area must be employed. The contaminated water may be diverted to an onsite treatment plant or oil-water separator; however, the adequacy of these systems is determined on a case-by-case basis for each one's adherence to good engineering practices and ability to retain a spill in the event of a system malfunction.  These valves must be opened to drain storm water and resealed following drainage by trained and authorized facility personnel only. Adequate records must be kept of each drainage event,  (i.e., date, time, personnel names) and made part of the SPCC plan.

Bulk storage facilities may employ many different types and designs of drainage control systems and oil-water separators. Facilities must implement a system that is consistent with good engineering practices, based on the size and complexity of their operations.

One design may consist of a sump located inside a containment area, which may be a blind sump (no drains) or a sump restrained by a normally closed valve. Facilities may remove the floating oil product by manual skimming or using sorbent materials. These materials must be disposed of properly or recovered for reuse. Any oil removed from skimming or the sorbent material must be disposed of as a waste oil. The remaining water in the sump must be inspected before discharging it outside the containment areas. Once sufficiently inspected and found to be free of oil, the water may be discharged by authorized personnel as long as the discharge is supervised and documented.

Other facilities may use a completely or partially buried oil-water separator system equipped with an inlet valve and a weir and baffle system, which directs the oil to one compartment and the water to another. The oil-water separator must never automatically discharge treated water to a sanitary sewer or anywhere outside a contained area.

Another alternative is to pump out diked areas with a manual pump or vacuum truck. Any oil-contaminated water must be transported to an appropriate waste-handling facility for disposal or treated on site.

Undiked Areas   Operating areas of a bulk storage facility that do not have secondary containment systems specifically designed for those areas are considered undiked areas. Drainage must be controlled for these areas which may include: tank car and truck loading/unloading areas, piping and manifold areas, garage bays, and fuel islands.   All undiked areas can be designed to control drainage through a combination of curbing, trenches, catchment basins, and retention ponds, as necessary to retain a spill. These structures must be inspected and examined for integrity and their effectiveness. For example, if a paved area is improperly graded or if a curb is deteriorating, contaminated water may escape from the facility. For this reason, a professional Engineer must certify the SPCC plan to ensure that the drainage system is adequately designed and properly maintained in accordance with good engineering practices.

Truck or engine washdown areas are a separate issue and should not be a part of the SPCC.  Waste water from these activities is an industrial waste stream and must be (1.) pretreated and disposed of in a sanitary sewer, or (2) treated and recycled, or (3) disposed of by evaporation or at a permitted waste water disposal facility.

BACK TO SPCC BULK OIL STORAGE REQUIREMENTS

BACK TO SPCC HOME PAGE

Call or e-mail us for more information and pricing for SPCC Plans and oil spill contingency plans.  SPCC must be certified by a Registered Professional Engineer.

Wilson Environmental Management, Inc.

Call us toll free in the U.S.  1-800-469-0799 

International callers, dial U.S. Country Code 1,  Area Code 713,  Number 468-3323

e-mail 

Office hours are 8 to 5, U.S. Central Time

   Texas                                           Utah                           North Carolina                                      Georgia                      

Austin, San Antonio, Houston                Provo                             Charlotte                                          Atlanta                                  

©2008 Wilson Environmental Management, Inc.

Established 1993,  A veteran owned company.