Monitored Natural Attenuation

Natural attenuation can refer to a range of processes already occurring at a site that break down or attenuate compounds of concern over time. Clients often turn to SiREM to understand if and how compounds of concern are naturally attenuating at their sites.

In monitored natural attenuation (MNA), natural physical, chemical, and biological processes are analyzed so clients can prove that compounds of concern are being destroyed, degraded to non-toxic components, or immobilized in a reasonable amount of time, thereby protecting human health and the environment. With reliable treatability testing and analysis, MNA can be a viable and cost-effective solution for remediating many kinds of contaminants.

SiREM’s MNA treatability studies equip clients with knowledge about aerobic and anaerobic biodegradation, abiotic degradation, precipitation, co-precipitation, and sorption, all of which are key processes for MNA.

Because our studies use soil, sediment, rock, and groundwater from your site, we can monitor changes in dissolved concentrations of organic and inorganic compounds of concern and give you robust evidence that conditions at your site are poised to break down or attenuate the compounds you are targeting.

SiREMNA Site Monitoring Package

Consider our customizable SiREMNA package, which adds chemical and Gene-Trac^® testing chosen for your particular site, based on media, contaminants, microbes present, and other features.

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Customized Studies with Dependable Results

SiREM’s experts can conduct MNA treatability studies for a wide variety of compounds in small batch reactors, flow through columns, and custom set-ups to understand how MNA is likely to occur at your site.

Our studies can help you accomplish the following:

Evaluate MNA mechanisms before choosing MNA or another remedy.
Generate sorption constants to model plume stability at the site.
Evaluate the stability of reversible attenuation mechanisms (like sorption and sequestration) under changing site conditions.
Incrementally identify and manage risk from the lab to pilot studies to treatment.
Reassure stakeholders early on that MNA is a feasible remedy.

MNA studies can answer questions about your site, including the following:

Will compounds of concern likely biodegrade under current conditions at my site?
Do geochemical conditions at my site allow for degradation or attenuation?
How much degradation is occurring through abiotic mechanisms?
How long will it likely take for compounds of concern at my site to degrade?
What are the sorption constants for the compounds of concern at my site?
What are the degradation intermediates or degradation pathways?
If we control variables, such as pH and redox, can we speed the MNA processes?

Microbial Activity and MNA: Measuring Aerobic and Anaerobic Microbes

Using specialized protocols and anaerobic chambers, SiREM’s anaerobic studies maintain the activities of oxygen-sensitive microorganisms. In addition to traditional anaerobic studies, SiREM has extensive experience conducting treatability studies to evaluate whether naturally occurring aerobic bacteria are already breaking down compounds of concern.

Abiotic Processes and MNA: Measuring Sorption, Reduction, Mineral Transformation, Precipitation, and other Processes

To investigate abiotic processes, we perform studies that help you understand whether compounds of concern are being sorbed by aquifer materials or precipitated out of solution when exposed to changing aquifer conditions. We develop sorption-coefficient information using geochemical conditions at your site. Further studies can then be completed to assess the stability of sorbed or precipitated materials under changing redox or geochemical conditions.

Actionable Results

All studies are replicated controlled experiments that provide a high level of data integrity and interpretability. You will receive reports that summarize data and place results in the context of your site so you understand whether and how natural attenuation is occurring at your site.

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Documentation

Treatability Cut Sheet

SiREMNA Organics Cut Sheet

SiREMNA Inorganics Cut Sheet

CCR Cut Sheet

CCR Ash Pond Case Study