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The PPM Blog

Missed Mass in Site Remediation – PPM Simplifies

When environmental site assessments and remediation become necessary, there’s no reward for doing half the job. “Due diligence” is literally the name of the game, and any corner-cutting—purposeful or accidental—could cost you and your site down the road.

As the site owner, buyer, or operator, you’re left with the difficult task of bringing a site’s soil and groundwater up to exact standards. But remediation across a large area and at certain depths can be inexact by its very nature. The testing, meanwhile, allows no gray areas or room for error. You’re left with performing a difficult task across a wide plot of land while trying to hit immovable standards.

Naturally, some remediation jobs result in “missed mass.” But what is missed mass, and how can a trained team of environmental consultants bolster your remediation efforts to ensure the job gets done?

In the most recent episode of PPM Simplifies, PPM Principal & Senior Geologist L. Todd Perry sits down with Project Manager Jared Saterfiel to discuss remediation, methodology, and missed mass.

What is Missed Mass?
A precise definition for missed mass can be difficult to articulate, but in essence, Jared Saterfiel says, “Missed mass is an area of concern for petroleum hydrocarbons or anything else you’re trying to clean up in the subsurface.”

Throughout the remediation process, you and your team are looking for Contaminants of Concern (CoCs). A “missed mass,” therefore, can be defined as an “area that’s not been addressed by active remediation.” In other words, a missed mass area can still contain harmful CoCs that will need to be discovered and remediated to bring a site up to standards.

How Common Is Missed Mass?
Depending on the method of remediation you and your team employ (more on that later), missed mass can be more or less common. Certain natural oversights in the chosen method for remediation can create different blind spots, resulting in missed mass.

According to Jared Saterfiel, “1 in 10 [remediation efforts] would probably be a good number for leaving missed mass. There are a variety of reasons why you have missed mass at a site.”

This 10% of assessments resulting in missed mass may not seem like much, but for that 1 in 10, additional expenses, penalties, and remediation efforts can lead to delays and other financial impacts.

How does Vacuum Extraction Risk Missed Mass?
Because different remediation methods search for, identify, and remediate CoCs differently, each has its aforementioned blind spots. One such remediation method is known as vacuum extraction.

“So with a vacuum extraction system,” Jared says, “whether it be DPVE (dual-phase vacuum extraction), or SVE (soil vapor extraction), you have CoCs in the soil in a saturated zone, which is below the water table, and you can’t really pull air across that area, which is what volitolizes to the CoCs.”

But that’s not the only risk for missed mass that can result from vacuum extraction. According to Jared, “You can also have your wells spaced too far apart, and that won’t allow for the radius of influence or the cone of depression—depending on your remediation technology—to overlap and really remediate the entire area. It’s a donut-remediation, per se.”

How About the Risk for Injection System Remediation?
This method, too, comes with blind spots of its own. “So with your injection systems,” Jared says, “two of your most common technologies are air sparge and ozone sparging.”

“Again, with the well spacing horizontally, you may be able to have the overlapped radius of influences there, which are generally tighter, [and a] smaller radius of influence on the injection rather than the extraction.”

Can a Pilot Study Prevent Missed Mass?
It’s not all bad news where missed mass and remediation are concerned. A little initial study and examination goes a long way.

“Investigation on the front end is a big part of that, seeing what’s in the subsurface. Pilot studies are also a big part of that. That way, we go in and see what the extraction rates are. We can see the radius of influences by taking readings on surrounding wells before we actually install [wells].”

Listen to PPM Simplifies for More
Phrases like “missed mass,” “contaminants of concern,” and “radius of influences,” can make any average head spin on its shoulders. But to the experts at PPM Consultants, these are the phrases, principles, and industry language of expertise in environmental remediation, site assessments, and all things compliance.

To hear more of L. Todd Perry’s discussion with Jared Saterfiel, listen and enjoy the full podcast here.

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