What’s meant by “sufficiently impervious” under the SPCC rule?

As a regulatory geek there are some rules I really enjoy working on with clients and some that are more onerous and less enjoyable. The Spill Prevention, Control, and Countermeasures (SPCC) regulation is one I have always really enjoyed providing insight on. For the most part it’s pretty black and white – or at least if you’ve spent nearly two decades studying it, it is. However, with any regulation there are some parts that are somewhat grey and may cause confusion.

One question that comes up consistently during conversations when working on SPCC Plans is, “What is meant by the term sufficiently impervious?”. Moreover, Witt O’Brien’s is currently working through this with several clients who recently acquired new assets, and, in each case, a previous consultant had sealed the original SPCC Plans stating the facilities earthen dikes were sufficiently impervious.

However, when we asked for proof backing these statements up so we could reseal their SPCC Plans we got the deer in headlights look. Unfortunately, many plan developers who don’t spend a lot of time working with SPCC Plans state dikes are sufficiently impervious with blanket statements but fail to provide proof in the final plans. Proof is not required to be in the plan; however, per the guidance documents it must be available if asked for. Hence, why it’s smarter to keep in the SPCC Plan. We always preach to our project managers to think like an auditor and ensure nothing is left to question in order to expedite audits.

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Witt O'Brien's will be hosting Troy Swackhammer, Mark Howard and Chris Perry, EPA Region SPCC Plan and Facility Response Plan (FRP) Coordinator in Houston for an all-day Free SPCC Plan and FRP workshop. Click here to RSVP.

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A good place to start this conversation is with what the EPA notes in their SPCC Guidance for Regional Inspectors published on December 1, 2013 under chapter 4.4.2, “Sufficiently Impervious” (linked below).

Section 112.7(c) states that the entire secondary containment system, “including walls and floor, must be capable of containing oil and must be constructed so that any discharge from a primary containment system ... will not escape containment before cleanup occurs.” With respect to bulk storage containers at onshore facilities (except oil production facilities), §§112.8(c)(2) and 112.12(c)(2) state that diked areas must be “sufficiently impervious to contain oil.” The purpose of the secondary containment requirement is to prevent discharges as described in §112.1(b); therefore, effective secondary containment methods must be able to contain oil until the oil is cleaned up.

If you have been in the SPCC world for a while, this is not a new requirement, or even something you haven’t dealt with in the past. However, over the past several years we have seen this to be a hot topic with both agency and client auditors alike.

Before I go too far remember the SPCC rule does not specify permeability, hydraulic conductivity, or retention time performance criteria (i.e., “sufficiently impervious” does not necessarily mean indefinitely impervious). Instead, the owner/operator and/or the certifying Professional Engineer (P.E.) has the flexibility to determine how best to design a containment system to prevent a discharge to navigable waters or adjoining shorelines. This determination is based on a good engineering practice evaluation of the facility configuration, products being stored and their properties and other site-specific conditions.

 Three scenarios for conversation:

1.  Client A purchases a terminal from Client B, and shortly after the ink dries on the contract, a small release happens in one of the containments. In less than 24 hours, the release migrates through the soil into a neighboring waterway. After release, local officials request containment improvements and proof that containment is “sufficiently impervious.”

2.  Client C has a release in one of their containments. Containment does its job by holding back the release; however, after Client C reports release as required, the EPA requests a statement from a P.E. that the containment is “sufficiently impervious.”

3.  Client D is inspected by the EPA; while the EPA is on site it begins to rain very hard. While waiting for the rain to subside, the EPA continues their review of the SPCC Plan. When the rain finally stops, the EPA begins their rounds of the facility. Most of the containments on site are holding water due to the heavy rains; however, one containment is empty with no visible standing water. As a result, the EPA requests proof that the containment is “sufficiently impervious.”

Without using physical studies, i.e., ASTM D2434 - 19 Standard Test Method for Permeability of Granular Soils (Constant Head), how does one determine retention capabilities on earthen containments?

One can use the Fetter tables, FetterC. W. (1994). Applied Hydrogeology, 3rd ed. Upper Saddle River, NJ: Prentice Hall, Inc., based on data pulled from the Natural Resources Conservation Service’s (NRCS) Web Soil Survey tool. 

Based on the snipped soil report below would you consider this sufficiently impervious based on the table above?

Drainage logs are also a helpful tool and can help make the case a containment holds back fluids and must be drained whenever it rains. 

Another option might be to use containment construction reports that show compaction techniques and materials used to determine retention capabilities as well.

Answer to above: With most of the soil types in the area being clay one could lean towards yes, sufficiently impervious; however, drainage logs and containment construction should also be reviewed to finalize a “yes”. Develop a full package of supporting documents to back up your claim.

However, none of these may suffice if you have had a release as illustrated in the examples. Physical soil surveys may also be required, or, if you have sufficient monitoring wells you could show there has been no horizontal migration from a containment area should you have to prove “sufficiently impervious” from an existing release.

What does all this mean? Why is it important today? 

Companies are required to do more due diligence these days. Gone are the days of just stating “sufficiently impervious” in an SPCC Plan. Today you must be able to prove that containment is indeed sufficiently impervious. Again, although not new, read below, but more emphasis is being placed these days on such conversation by EPA auditors.

The preamble to the 2002 SPCC rule amendments states that “a complete description of how secondary containment is designed, implemented, and maintained to meet the standard of sufficiently impervious is necessary” (67 FR 47102, July 17, 2002). Therefore, pursuant to §112.7(a)(3)(iii) and (c), the Plan should address how the secondary containment is designed to effectively contain oil until it is cleaned up.

When buying new properties, one should not just rely on a statement that plainly states “sufficiently impervious” in an existing SPCC Plan, but ensure proper poof is also provided. Where proof is not provided, consider spending the time and money to ensure containments can hold back fluids. The alternative can be dealing with a release that makes it outside of containment, which costs a lot more than several soil surveys. This is a step which would have also provided advance warning. When building new containments, ensure proper documentation is generated and if necessary, testing, in order to address any such concerns in the future. 

What does one do if they have an existing facility and no proof?

There are several options; however, initially a risk assessment or hard review of one’s inventory should be considered. What is the appropriate level of sufficient permeability at your facility (i.e., 10-7 cm2/s)? Again, this requires a thorough review of the unique conditions of your facility. Some states, like Pennsylvania, have actual regulatory standards one must meet.

A final thought. Though the guidance states “sufficiently impervious” does not necessarily mean indefinitely impervious; you should aim for as close as one can for indefinitely impervious. Soil clean up is costly, so the more vertical and/or horizontal permeation that happens as a cause of a release adds to the overall finical burden.

Need to read more? The current bible for all things to reference regarding SPCC regulations can be found in the EPA’s SPCC Guidance for Regional Inspectors website.

For a complete listing of archived blogs and compliance insights, click here. Past blogs cover training requirements, clarification on additional confusing elements within the above rules, and much more.

We are here to help solve your compliance questions and challenges. Need some compliance assistance, or just have a question? Please email John K. Carroll III ([email protected]) Associate Managing Director – Compliance Services or call at +1 281-320-9796.

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