Site characterization and remediation monitoring using in situ subsurface sensors
- Unocal Corp., Brea, CA (United States)
Site characterization and remediation monitoring using in situ sensors is potentially a more effective and inexpensive alternative to current methods of sample collection and analysis. Gaseous components of a system are the most mobile and easiest to monitor. Soil gas measurements can not only indicate the presence of hydrocarbon contamination, but also provide important quantitative information regarding the progress of bioremediation efforts and the area of influence of air sparging or soil venting. In situ subsurface sensors can provide potentially more accurate data by minimizing disturbance of subsurface conditions and allow continuous and unattended measurements over a long period of time. Tests of in situ soil gas sensors show that the sensors provide rapid and accurate data on soil gas pressures and vapor phase concentrations. The sensors perform well in permeable, unsaturated soil environments and recover completely after being submerged during temporary saturated conditions. The pressure and subsurface oxygen sensors are well suited for monitoring gas flow and oxygen consumption in the vadose zone during air sparging and bioventing. These sensors have been used to develop a new dynamic technique of evaluating in situ respiration rates during air injection or vapor extraction which has several advantages over the traditional static oxygen uptake method. By using a subsurface oxygen sensor, the dynamic technique offers continuous monitoring capability during the bioventing process. Unlike the traditional respiration test that measures localized respiration rates, this method determines an average respiration rate in the air flow path. Because the measurements can be made at the startup of a remediation process, the operation can run without interruption.
- OSTI ID:
- 122454
- Report Number(s):
- CONF-9510211-; ISSN 0017-467X; TRN: IM9547%%34
- Journal Information:
- Ground Water, Vol. 33, Issue 5; Conference: 1995 Association of Ground Water Scientists & Engineers (AGWSE) educational program, Indianapolis, IN (United States), 28-30 Oct 1995; Other Information: PBD: Sep-Oct 1995
- Country of Publication:
- United States
- Language:
- English
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