Summary

This chapter addressed the important long-term activities that must be followed for the success of a remediation program. We addressed this by showing data that are commonly collected in the field and analyzed to determine remediation effectiveness. While not every remediation technology was addressed, the monitoring and O&M activities described apply to all remediation technologies. Major points addressed were:

• • Definition of monitoring, operation, and maintenance;
• • Soil vapor extraction monitoring and O&M activities, including mass removal determination and cost considerations;
• • In situ chemical oxidation monitoring and O&M activities;
• • Groundwater pump-and-treat monitoring and O&M activities, including hydraulic containment and mass removal determination;
• • Air sparging monitoring and O&M activities; and
• • Monitored natural attenuation (MNA) activities.

Problems and Activities

• 8.1. Calculate the volume that 1 mole of an ideal gas occupies inside a pressurized pipe at a temperature of 55°C and an absolute pressure of 305 mm-Hg (note that since the pressure is less than atmospheric pressure, 760 mm-Hg, then the pressure is considered to be a vacuum).
• 8.2. Calculate the volume that 1 mole of an ideal gas occupies inside a pipe under a temperature of 40°C and an absolute pressure of 2 atm.
• 8.3. Based on your answer to problem 1, convert a concentration of benzene of
• 98.0 ppmV to mg/m³ and calculate the mass flow rate for a standard volumetric flow rate of 0.05 mVs.

• 8.4. Based on your answer to problem 2, convert a concentration of vinyl chloride of 48 pg/m³ to ppmV.
• 8.5. A soil vapor extraction project uses granular activated carbon (GAC) to treat the off-gas concentrations of xylene (MW 106 g/mol) from 800 ppmV (at P=0.9 atm and T = 30°C) to 100 ppmV (at STP: P=1 atm and T=25°C) at an STP flow rate of 0.09 mVs. Calculate the mass of xylene retained in the GAC per day.
• 8.6. Given the graph shown (Figure 8.11) on the cumulative mass of contaminants removed using SVE, at what point should a remediation professional consider optimizing the system? Explain your answer.

FIGURE 8.11 A graph of cumulative mass removal over time (Problem 8.6).

• 8.7. For the graph of COC removal over a period of 20 years (Figure 8.12), which portions of the curve indicate poor efficiency in the system? Where does the curve indicate that a remediation process optimization was performed?
• 8.8. Several monitoring wells located in the direction of the flow of a benzene plume have the concentrations at one point in time shown below, (a) Determine the first-order decay rate constant with respect to distance from the source, (b) Estimate at what distance from the source the toluene concentration is expected to reach 5 pg/L.

FIGURE 8.12 A graph of cumulative costs vs cumulative COC removed (Problem 8.7).

References

NJDEP. (2012). Site Remediation Program Technical Guidance, Monitored Natural Attenuation Technical Guidance. New Jersey Department of Environmental Protection, Trenton, NJ.

U.S. ACE. (2002). Soil Vapor Extraction and Bioventing. Engineer Manual. U.S. Army Corps of Engineers.

U.S. ACE. (2013). In-situ Air Sparging Engineer Manual, EM 200-1-19. U.S. Army Corps of Engineers, Washington. DC.

U.S. EPA. (2002). Elements for Effective Management of Operating Pump and Treat Systems, EPA 542-R-02-009. U.S. Environmental Protection Agency Office of Solid Waste and Emergency Response, Cincinnati, OH.

U.S. EPA. (2017). How To Evaluate Alternative Cleanup Technologies For Underground Storage Tank Sites, Chapter VII Air Sparging. EPA 510-B-17-003. U.S. Environmental Protection Agency Office of Land and Emergency Management, Washington, DC.

U.S. EPA, Huling, S„ and Pivetz, B. (2006). Engineering Issue: In-Situ Chemical Oxidation. EPA/600/R-06/072, U.S. Environmental Protection Agency Office of Research and Development, Cincinnati, OH.

URS Group, I. (2006). Field Pilot Study of In Situ Chemical Oxidation Using Ozone and Hydrogen Peroxide to Treat Contaminated Groundwater at the Cooper Drum Company Superfund Site. Sacramento, CA.

Wisconsin DNR. (2014). Guidance on Natural Attenuation for Petroleum Releases. PUB-RR-614. Wisconsin Department of Natural Resources, Madison, WI.