MNA Lessons from "Big Data" Studies

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From the course by Rice University

Natural Attenuation of Groundwater Contaminants: New Paradigms, Technologies, and Applications

163 ratings

Rice University

Natural Attenuation of Groundwater Contaminants: New Paradigms, Technologies, and Applications

163 ratings

Cleaning up the large number of groundwater contamination sites is a significant and complex environmental challenge. The environmental industry is continuously looking for remediation methods that are both effective and cost-efficient. Over the past 10 years there have been amazing, important developments in our understanding of key attenuation processes and technologies for evaluating natural attenuation processes, and a changing institutional perspective on when and where Monitored Natural Attenuation (MNA) may be applied. Despite these advances, restoring groundwater contaminated by anthropogenic sources to allow for unrestricted use continues to be a challenge. Because of a complex mix of physical, chemical, and biological constraints associated with active in-situ cleanup technologies, there has been a long standing focus on understanding natural processes that attenuate groundwater contaminant plumes. We will build upon basic environmental science and environmental engineering principles to discover how to best implement MNA as a viable treatment for groundwater contamination plumes. Additionally we will delve into the history behind and make predictions about the new directions for this technology. Any professional working in the environmental remediation industry will benefit from this in-depth study of MNA. We will use lectures, readings, and computational exercises to enhance our understanding and implementation of MNA. At the completion of this course, students will have updated understanding and practical tools that can be applied to all possible MNA sites.

From the lesson

Modeling Tools to Support MNA

In this series of lectures, we talk about models and how they can be used to understand MNA. We first start with two key MNA questions: How Long? (will the plume get) and How Far? (how long until the site is clean). Then a review of analytical computer models, remediation timeframe models, the more complex but more powerful numerical models, and even a discussion of the “Fourth Paradigm: Big Data”.

How Long, How Far? Key Questions for Modeling Tools12:11

Fate and Transport Equations for MNA6:29

Analytical Groundwater Models for MNA11:30

Estimating Remediation Timeframes10:49

MNA Lessons from "Big Data" Studies10:05

Numerical Groundwater Computer Models and MNA9:46

Meet the Instructors

Pedro Alvarez
George R. Brown Professor of Civil and Environmental Engineering
Department of Civil and Environmental Engineering
Charles Newell
Vice President
GSI Environmental Inc.
David Adamson
Senior Environmental Engineer
GSI Environmental Inc.

CHUCK NEWELL: OK, well let's continue with the way

to understand our world of sources and plumes and attenuation,

but maybe with a different model, a different way of learning.

DAVE ADAMSON: I think you're talking about big data here, right?

CHUCK NEWELL: That's right.

You sort of think about our domain as starting with that 40 mil VOA

vial that gives us our concentration, right,

and we use this to look at temporal trends

and understand the spatial distributions of our plumes.

In some ways, it's a little bit like the human body,

where we're starting with cells, then organs, and then, well, us.

DAVE ADAMSON: Is there some sort of connection you're trying to make here?

CHUCK NEWELL: Well it's maybe that the medical field is very big data

intensive.

If you want to know a prevalence of some disease

or if they want to know if a treatment will work,

they go to epidemiology studies.

You know, they crunch the numbers.

And in the groundwater field, we've been doing this for a while,

but recently, there's been a dramatic increase in our big data-ness factor,

OK?

DAVE ADAMSON: Big data-ness?

So another made up word from Chuck-- sounds interesting though.

So I'm guessing you might be shifting to paradigms or something like that next?

CHUCK NEWELL: OK, you're really prescient.

You can really see in the future.

So let's go look at this really good book called The Fourth Paradigm

of Science, and it's the idea that science

has sort of gone through these different waves

and so they defined the first paradigm as what?

DAVE ADAMSON: Experimental science, so running experiments.

Think about like Mendel in his lab with beans, doing genetic experiments.

CHUCK NEWELL: Pretty good.

And now the second paradigm, theoretical science and the idea there,

it's Einstein smoking his pipe and he's writing these equations

on his blackboard and thinks and then he writes

E equals mc squared and he's done.

DAVE ADAMSON: Computational modeling, that's the third one in here.

So where you got all this power in these computers,

you can set up these really complex models

to describe stuff like the weather, climate models, things like that.

CHUCK NEWELL: So then the book goes in and says, we're on the cusp

or we're starting to do this fourth paradigm of science

and it's these application of these massive database that you can mine,

and you can learn, and you can understand.

Like one of the examples in some of these books was that by mining

big data, that Walmart knew if a hurricane was in the Gulf of Mexico,

people wanted to buy strawberry Pop-Tarts

and so they would stock those in there, getting ready for the hurricane.

So we can learn some of the same things except for plumes and things like that.

So let's go back in time.

We've been doing some of this for a while

and they've been very important studies for us,

but this is a particular study done by the Lawrence Livermore Lab.

David Rice was the author and he looked at a couple of hundred

of these benzene BTEX plumes.

How long are they, is what they asked.

So this was a drawing that we did for the American Petroleum Institute,

but looking at this, we're looking at different buckets

or different lengths of the plumes.

So what's the key point here?

DAVE ADAMSON: Well, I mean if we're looking at plume lengths

there on the left, it looks like most of them are sort of in the under 200

foot range.

CHUCK NEWELL: And this was an amazing revelation.

These plumes aren't really long, but what was perhaps even more important

was these temporal trends.

They took all their sites where they had some data

and they put them in these four buckets.

Is it expanding, stable, shrinking, or exhausted?

Dave, what was the big news out of this?

DAVE ADAMSON: Only eight of these, in this case,

were in the expanding category.

CHUCK NEWELL: So some good learning just from sort of mining those databases

and doing this fourth paradigm of science.

Now they've also did some plume-athon studies back around the year 2000.

This is, again, from the Lawrence Livermore guys.

Walt McNab's the key author.

But looking at chlorinated solvent plumes

and they're seeing how long are they.

Let's look at this median line, in terms of the median length

for these-- 10 part per billion plumes.

What was that medium length?

DAVE ADAMSON: About 1600 feet and it decreases a little bit as you expand.

After 1,000 ppb, it might be 650 feet, so pretty long plumes.

CHUCK NEWELL: And just much longer than the BTEX plumes, right?

So that was in there.

They were also interested in this question,

is we do the daughter products to get way ahead of these plumes.

So they looked at that and what were their conclusions here?

DAVE ADAMSON: Well here it's sort of interesting

that the parent plume in these cases was the longer

one in the majority of them, 73%.

Only 27% was that daughter plume actually out beyond the parent plume

CHUCK NEWELL: Yeah.

So gives some insights.

Maybe we don't know the exact processes, but this

is what was out there and so an important learning.

Let's go to another study.

This is concentration versus time.

This was a study that I did.

Dave, what's on the graph on the left?

DAVE ADAMSON: We got normalized concentration

for a bunch of different wells so each of those red lines

is sort of an individual well and you're plotting that concentration over time.

So as concentration goes down, it might-- it gets lower.

It's going to fall below that blue line.

As it gets higher, falls above the blue line.

CHUCK NEWELL: OK and a lot of scatter on that data.

If you really want to know the trends, what do you do?

DAVE ADAMSON: You ask the man.

Do the Mann-Kendall trend analysis that we talked about it in another lecture.

CHUCK NEWELL: So we did this, and if you look at the table there,

let's look at all of these plumes.

Of the 23, only three of them had expanding plumes.

And the rest, there are two no trend, but most of them

were stable, probably decreasing, or decreasing itself.

So you can look at these things.

So that was an important application of data mining and seeing what was done.

Now let's move on to sort of more recent times

and the emergence of this really amazing database called GeoTracker.

Every groundwater sample that's been collected in California since about

2001 gets into this database.

There are a total of 60,000 sites out there.

There's 12,000 of them with this electronic data, is that right?

And then this was used for this paper, "Progress

in Remediation of Groundwater at Petroleum Sites in California,"

by our colleague, Tom McHugh.

But each dot there is a site where they did the sampling in GeoTracker.

And so we can-- want to blow this up a little bit more,

get a sense of what we're looking at?

So we're to go by-- each month is a sample that's taken

and so you can go through here and just sort of see these things move.

Each one of those is the field crews are going out there.

They're collecting those samples, or sending them to the lab

and then that data makes its way into this big database that you can do.

And that's what Tom McHugh did to sort of understand this.

Of course there's some things there.

You can get a sense of what's going on.

Let's look at this slide here.

It looks like that there's this dot out in the ocean.

DAVE ADAMSON: Those guys did some extra effort to go get that data point,

I guess.

CHUCK NEWELL: I guess.

I have in my mind, the field guys go to the boss.

He gives them those GPS coordintes and they say, but boss.

He says, just do it.

So they rent a boat and they go out there and they do their sample

and get the slug test, high permeability.

What do you think?

DAVE ADAMSON: Yeah, yeah.

Probably.

CHUCK NEWELL: OK.

So that's GeoTracker and so then Tom McHugh took this data

and he said sort of what is the typical median concentration

of benzene in California?

How did it change from 2001 to 2010?

DAVE ADAMSON: The expectation, it's going down over time, right?

CHUCK NEWELL: Let's see if that really happened.

What does the big data tell you?

So here's this graph, median of the maximum concentrations

at all these different sites.

About a 10 year time interval on the bottom, and yeah, it goes down a lot.

It's going from about 2000 to, what do you think,

about 200 micrograms per liter?

DAVE ADAMSON: Yeah, something like order of magnitude.

So each individual point is the representative concentration

for that sort of 1,128 benzene sites.

CHUCK NEWELL: Yeah.

And this was-- the same sites were used, so this analysis,

they kicked out sites that were closed halfway through

or new sites that came in.

But this is what these trends say at these sites that were open.

Now let's look at MTBE.

You think you'll see the same thing?

DAVE ADAMSON: Well, yeah, MTBE was starting to get phased out,

so it should decrease.

CHUCK NEWELL: Looks like it's even a bigger increase, maybe 2,500

micrograms per liter to something that's well

below-- what do you think-- 50 or 25?

DAVE ADAMSON: Yeah, yeah.

So a couple orders of magnitude in this case over that relatively

short, short period of time.

CHUCK NEWELL: And then he was able to go in there

and look at the degradation product from aerobic degradation MTBE.

And so what did he see with this?

There was an increase and then a decrease?

DAVE ADAMSON: Yeah, so I guess you could expect to see some TBA

formed while MTBE was being degraded, but then eventually seeing

a decrease in that as well.

CHUCK NEWELL: So some remarkable stuff that he finally actually

put a model to this, right?

And he says, I can fit this curve by turning these dials, which

is the two inputs or what is the half life of MTBE, and that's creating,

basically, this TBA.

And then how quickly does the TBA itself go away?

What are the decay coefficents?

DAVE ADAMSON: Yeah, we about a two year half life for MTBE

and 3.5 years for TBA.

CHUCK NEWELL: Yeah. so some really amazing stuff

that's coming out, looking at this big data from GeoTracker.

Now you actually use GeoTracker for a different question, 1,4-dioxane.

DAVE ADAMSON: Yeah, a lot of people interested in 1,4-dioxane relative

to chlorinated solvents.

There's a lot of co-occurrence of those at sites

and there's a big worry that the dioxane plume, because of the way

it could potentially migrate, would be way out ahead

of the chlorinated solvents.

So what we did was go into GeoTracker, tried to take what the data really

showed to us.

And it's pretty interesting stuff because if this

is a graphic from a paper that we publish, really, only 21% of the sites

fell into that sort of common conceptual model,

where the dioxane plume was longer.

17% of sites, they were about the same length

and what is really interesting then is 62% of the sites, the majority of them,

were actually able to say that the chlorinated solvent plume itself was

longer than the dioxane plume.

So sort of positive news in terms of dioxane.

CHUCK NEWELL: Now part of that may have become the dioxane

may have been newer than some of these solvents or used at a later date,

but also you went to GeoTracker and the GeoTracker data said,

hey, this stuff's attenuating, right?

DAVE ADAMSON: Yeah, and we have a lot of interesting information on attenuation,

but one of the things that we're also able to do

is then say, what's important for promoting attenuation?

And so some of this data, we also got from Hunter Anderson at the Air Force

and he did some great analyses with these, and that's what's shown on here.

But the basic message is that dioxane attenuation was positively

correlated with the presence of dissolved oxygen,

so promoting that aerobic biodegradation,

and negatively correlated with the presence of metals and CVOCs.

So good indication that the field data is

sort of matching up with all those great lab

studies that we've seen at various research institutions and so forth.

CHUCK NEWELL: OK, and what metals are you talking about here?

DAVE ADAMSON: We're talking about things like chromium and things like that.

CHUCK NEWELL: Very cool.

OK, well let's wrap up these big data studies,

give insights on how big plumes are and how fast they change and what they do.

DAVE ADAMSON: And we've got numerous studies that are out there looking

at a variety of different contaminants.

CHUCK NEWELL: And finally this GeoTracker sort of a database,

really an important resource for understanding how plumes work.

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