Monitored Natural Attenuation Calculator

Estimate MNA cleanup timeline from contaminant half-life and monitoring network costs.

Initial concentration (µg/L)

Cleanup target (µg/L)

Contaminant half-life (years)

Plume length (m)

Plume width (m)

Monitoring events/year

Cost per well per event ($)

Groundwater velocity (m/yr)

Tab to move between fields

Estimated cleanup time (years)

19.9

Monitoring wells needed

Total monitoring cost ($)

$1,275,620

Decay constant (per year)0.35

Annual concentration reduction (%)29.3

Concentration at 5 years (µg/L)883.9

Concentration at 10 years (µg/L)156.3

Concentration at 20 years (µg/L)4.9

Annual monitoring cost ($)$64,000

Steady-state plume length (m)86.6

Plume Migration M597.95%

How to Use This Calculator

Enter initial concentration (µg/L) and cleanup target from your remediation action levels.
Set the contaminant half-life in years based on site-specific attenuation rates or literature values.
Enter plume dimensions to estimate total mass and monitoring network size.
Review the estimated cleanup time and projected concentrations at 5, 10, and 20 years.
Use annual concentration reduction to confirm attenuation rates meet regulatory requirements.

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