Diagnosis of in Situ Air Sparging Performance Using Groundwater Pressure Changes During Startup and Shutdown.

摘要

In the past few years it has become increasingly common to use pressure transducers (rather than water level tapes) to measure groundwater pressure changes during In Situ Air Sparging (IAS). Pressure measurements allow nearly continuous data collection and, when used in conjunction with piezometers with short screens provide data with increased freedom from artifacts. Groundwater pressure measurements provide a number of insights into IAS operation. For example, the time required for pressure to return to pre-sparge levels (within a few cm of water) is a good estimate of the time required for sparging air flow to reach steady state. This measured time then can be used to determine frequency of pulsing cycles for air injection during IAS as recommended in Johnson et al. (2000). Pressure measurements can also be used to identify sites at which significant volumes of air are becoming trapped below the water table. In that context, the data can be used as a red flag during pilot tests to indicate whether IAS may be infeasible at a site.