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The PPM Blog

More SPCC Myths & Facts – Part 3 of 5

a man wearing a suit and tie smiling at the cameraContributed by Zane Hood, Principal, PPM Consultants

This is the 3rd episode of SPCC Myths and Facts. If you recall we’re addressing certain misunderstandings related to the long storied history of the Spill Prevention, Control, & Countermeasure (SPCC) Rule’s storied history reaching all the way back to 1974—a nearly 50 year history! SPCC regulations were revised in 2002 with amendments made in 2006, 2008 and 2009. Furthermore, EPA has issued some interpretive iterations along the way with various levels of clarification issued in the form of memorandums and guidance documents.  Almost all of this can be found in EPA’s massive SPCC Guidance for Regional Inspectors, dated December 16, 2013.

In a nutshell, it seems as though spill prevention should be a simple thing, unfortunately there are many topics, issues and interpretation of the rule which are often misinterpreted due to the “gray areas”. This blog article we will cover a few more of these topics (Myths #5 and #6) and hopefully provide some brief insight into some of these myths and truths.

Myth # 5

The discharge from my secondary containment flows through an oil/water separator (OW/S) so I don’t have to visually inspect/monitor discharges from my secondary containment system.


First lets take a look at what the rule specifically says and then we can dissect where and how this operational philosophy can create noncompliance.

Let’s begin by narrowing this discussion to “onshore storage facilities.” In this scenario, 112.8 gives two different scenarios to consider: 1) When using dikes/berm the “sized secondary containment” required is sufficient to contain the largest container plus sufficient freeboard for precipitation (generally the statistical 25-year 24-hour rain event in inches); and 2) when facilities drainage controls are used to satisfy secondary containment requirements.

For the conventional method 1) – the rule clearly implies water being discharged should be visually inspected for a visible sheen prior to discharge in 112.8(b),(c)3 and 112.12 (b),(c)3. This is pretty simple and straight forward: the containment must be securely valved off, the discharge inspected for a sheen (a jar test, or other visual inspection method) and if none is present it can then be discharged.

For method 2) – if you are allowing precipitation to flow unabated through an OW/S from a bulk storage containment area, the capacity of the containment area becomes irrelevant. Instead, now you are relying on “facility systems” to drain the separated water and to recover and store the worst-case discharge of oil. This type of system warrants that the professional engineer certify “environmental equivalence” to achieving environmental control. There are MANY factors that the engineer must consider in this scenario including but not limited to: the capacity of the OW/S to handle both the precipitation of the drainage area and the volume of the worst-case scenario release. Simply put, the larger the tank (worst-case scenario), the more difficult and/or detailed the demonstration of environmental equivalence becomes.

For example, if a bulk containment area has multiple 30,000 gallon tanks in a containment area that has a flow-through OW/S discharging water from the basin and that separator has a 500-gallon oil recovery compartment, it will be easily overcome in the event of a worst-case scenario release. This will not satisfy “environmental equivalence” as oil would likely be discharged to the environment. The system would need to be automated to convey the recovered oil to another tank and it would need to be able to do that a rate sufficient to ensure it isn’t overcome allowing a discharge of oil in the process.

Also, on occasion facilities may have the philosophy that routine “dribs and drabs of oil” are considered normal operation since they have an operating oil/water separator which “treats” the effluent discharge. This operating philosophy is flawed from several aspects.  For starters, it creates a culture of poor housekeeping and an oily facility. Often loading areas or loading racks will drain into the secondary containment, which also exacerbates the poor housekeeping issue. If there is an area of oily operation, those areas should be covered by canopy so that precipitation doesn’t comingle, and directed to either an oil/water separator which directs recovered oil to a used oil bulk storage container (for recycling) and petroleum contact water (PCW) to bulk storage for 3rd party permitted disposal.

Beware also of cleaners used occasionally in “oily areas” which may emulsify the oils and render the OW/S as useless, discharging emulsified oily water. An oil/water separator must have a detailed routine and effective preventative maintenance, particularly if there is a heavy presence of oil. Without it, there will most likely be a noncompliant discharge.

Myth # 6

I have double-walled steel tanks so I don’t have to concern myself with secondary containment requirements.


It is true enough that double-walled tanks can make things much simpler than dealing with secondary containment systems, burdensome inspections, and the worst part managing discharges of precipitation and potentially collection and analysis of samples related to NPDES discharge permit requirements.

However, you are not totally “off-the-hook” when it comes to double wall tanks as a means of secondary containment.

Section 112.8(c)(6) also requires that the owner or operator frequently inspect the outside of the container for signs of deterioration, discharges, or accumulation of oil inside diked areas (for a double-walled tank, this inspection requirement applies to the inner tank). To comply with the requirement to frequently inspect the outside of the tank, an owner or operator must inspect the interstitial spaces of a shop-built double-walled aboveground storage tank (AST). Typically, this is accomplished by an inspection port (which can be visually inspected or used in conjunction with a dip stick, camera, or visual leak indicator), a drain plug, sensors or other equivalent means to detect a discharge into the interstitial (annular) space from the inner primary container. EPA recommends the use of automatic detection devices to detect discharges into the interstitial space. Once a discharge is discovered in the interstice, corrective action is typically required by industry standards. After a discharge to the interstitial space has occurred, the system is no longer operating as a double-walled tank (because the external tank is serving as the primary container unless and until appropriate repairs are made in accordance with the applicable industry standard).

These requirements are often missed and if your friends from the state agency or more likely your EPA Regional SPCC inspector show up they may ding you for not having this in order.

The coming issues will cover other topics that often get misinterpreted, misconstrued, or just missed altogether. Stay tuned!

The prior blogs can be found here:

If you have any questions regarding these or other topics as they relate to your facility or want to reach out with questions always feel free to reach out directly to me at

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