The unrealized potential of managing groundwater risk and soil remediation together

Groundwater is a key risk vector for hydrocarbon plumes.   Yet, the majority of hydrocarbons reside in the soil.   Thus, site managers typically use groundwater for risk management and use soil information for remediation modelling.  Here, we will discuss how soil and water sensors can provide insight into risk and liability, providing site owners with a pathway to reducing both.

  • Groundwater is a key vector of risk associated with pollutants.
  • Soils are the source of this risk and need to be remediated.
  • Often technologies are separated into ‘risk’ or ‘remediation’ buckets, leaving the synergistic potential of these technologies unrealized.
  • Real-time remote monitors allow operations to find the right local solution easier, quicker, and cheaper than ever before.

Risk and Remediation

Risk is what keeps operations up at night.  Groundwater is the train that moves your risk from your property over the line into your neighbour’s property.  As pollutants move in groundwater, they pose a risk to humans and ecosystems who might drink or live in the water.   Even if no person or animal is drinking the water, vapours from the groundwater move up the soil into basements and buildings.   For these reasons, operations monitor groundwater all the time.

Is the plume stable?

Are concentrations increasing or decreasing?

Answering these questions allows operators a sound nights sleep.

It is a truism that what we measure is what we manage.   Leading operators down a primrose pathway to site management hell.

Site management hell is when you begin to manage your long-term liability based on groundwater and not on soil.  Long term liability lives in soil.  There is 230 times more benzene mass in soil compared to the water at a site.  Don’t believe me?  Here are some quick calculations based on physical constraints:

(i) 30% of the ground is void volume, and in a saturated soil that means water, and

(ii) 1:99 is the ratio of water:soil benzene concentrations.

Thus, in a volume of ground with 1 ppm benzene in the water, there is 99 ppm in the soil.   The total mass in water is 0.3 * 1 ppm = 0.3, and in soil is 0.7 * 99 ppm = 69.3.

Please forgive the oversimplification but the results are roughly correct.

Thus, you should never evaluate a remediation system based on groundwater.  Instead, evaluate risk based on groundwater.  Evaluate remediation based on soil.

Finances and Operations

If risk keeps operations up at a night.  Liability keeps finance up at night.  Liability lives in the soil.   Financial liability is based on remediation costs.  Remediation costs are ball parked at $120 per cubic meter of polluted soil.  You then need to add in the destruction of the above ground infrastructure, and if you’re experienced, you would likely increase that by 50% to account for unpleasant surprises.

We’ve now defined the hellish box where operations live.  Ops is monitoring groundwater and there is a persistent but manageable risk.   Thus, regulators require annual reporting, and this means that every year operators are doing project management.  A consistent drain on cash flow and team resources.  On the other side, asset retirement obligations never go down, because the soil is not being remediated.

Why doesn’t operations do more remediation?  Disruption and risk.  

Any remediation project is going to disrupt operations, impacting revenue and incurring the wrath of finance.  Risk arises because even with the best planning and best technology, sometimes remediation is not successful.  Not only that, but sometimes remediation projects go overbudget due to plume extents being larger than expected.

Operations is thus faced with a binary choice, manage risk by groundwater monitoring but do not decrease liability – or decrease liability but dramatically increase operational risk and cost.

Sustainable Depletion

Real-time, remote monitoring coupled with predictive analytics means operations no longer has a binary choice.  Instead, by combining groundwater and soil depletion monitoring into an integrated digital site model, operations can optimize their operations risk to benefit ratio.  In other words, reduce liability with minimal operations risk.  This is how you realize the synergies between the “risk” and “remediation” buckets.

Groundwater monitoring as a regulatory backstop

Real-time, remote monitoring of groundwater provides operations with a secure regulatory backstop.   At a typical site with five real-time water sensors, one can estimate dissolved pollutant dynamics 63,000 times per year.  A robust data stream that can be used to monitor if human and ecological risk has altered.  Coupling that data stream to new generation AI tools provides regulators and site owners with the ability to predict groundwater dynamics 10 years in the future with confidence.   I often think of this data stream as the melody of a song that each ecosystem sings to itself through the ages. Operators can listen in to that melody and decide if an ecosystem is happily burbling away or instead has moved into a dynamic drumbeat that heralds disturbance.

Soil monitoring to proactively reduce liability

Now that operations have security, they can move from reactive to proactive and begin reducing liability.  Real-time remote sensors change the fundamental nature of remediation from a binary event – are you remediating or not? – to a gradual process – is the system getting better?

Real-time remote soil sensors provide indicators and direct measures of remediation activity.  The indicators measure site biological activity and can be used to infer how much natural remediation is occurring at a site.  The direct indicators of pollutants estimate current plume extent.  Thus, operations can monitor biological activity and answer the question – is the soil actively cleaning up?  Operations can also estimate plume size every day, and answer Finance’s question – what is our current liability?

The true advantage of real-time remote monitoring is that operations can incrementally change site activity and monitor the response in real-time.  Operations is no longer stuck in binary hell, but can try out approaches that they think might work at their site.

Soil problems are global.  Soil solutions are local.  Real-time remote monitors allow operations to find the right local solution easier, quicker, and cheaper than ever before.