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EM 1110-1-4001 3 Jun 02 Chapter 9 System Shutdown and Confirmation of Cleanup 9-1 Introduction The attainment of agreed-upon conditions under which remedtation activities may cease and the SVEBV system may be decommissioned is the ultimate objective of the remediation effort This requires a series of steps to demonstrate that the air being processed and the soil in the treatment area have met established criteria 9-2. Shutdown Strategy a Federal and state regulatory media-spectftc cleanup requirements,voluntary cleanup requirements, or risk-based requirements established for the particular contammant(s)to be remediated drive the shutdown of a remediation system Site-specific cleanup objectives are usually established by the Federal and/or state agencies,if no generic cleanup levels exist In many cases,the cleanup requirements are determined based on a need to protect the quality of the underlying ground water As the initial step to determining the shutdown strategy,the design team must be familiar with all Federal and/or state soil cleanup objectives Table 9-1 lists factors that may influence one to commence shutdown Table 9-1 Possible Criteria to be Considered in Evaluating Shutdown of SVEIBV System Offgas(Analysis(Continuous and Pulse Venting-MUST be considered in conjunction with other data) • Total emissions or individual VOCs exiting blower exhaust are not evident • Total emissions or individual VOCs exiting blower exhaust reach predetermined levels • Total emissions or individual VOCs exiting blower exhaust reach asymptotic conditions and design deemed adequate • No rebound is observed in influent concentrations upon system restart following reasonable system shutdown period • Operation costs greatly exceed value of continued vapor removal(operator's decision) - Pulse venting down time greatly exceeds pulse venting operation time(operator's decision) Bioventing Respiration • Oxygen respiration measurements performed within the area being remediated indicate dedining contaminant degradability relative to a background control Soil Gas Analysis (from monitonng probes)Recommended • Soil gas constituents collected from remediation area reach asymptotic conditions and extraction and monitoring system designs deemed adequate • Sod gas constituents collected from the remediation area indicate levels of nondetection with reasonable detection limits and concentrations • Soil gas constituents collected from the remediation area indicate levels of residual mass that is no longer threat to ground water • Soil gas concentrations do not significantly rebound following reasonable system shutdown period • 9-1