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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 remediation activities may cease and the SVEBV system maybe 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 i 9-2. Shutdown Strategy i a Federal and state regulatory media-specific cleanup requirements, voluntary cleanup requirements, or nsk-based requirements established for the particular contanunant(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 in 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 confunctron with other data) • Total emissions or individual VOCs eMing 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(operators decision) • Pulse venting down time greatly exceeds pulse venting operation time(operators decision) Bioventing Respiration Oxygen respiration measurements performed within the area being remediated indicate declining contaminant degradability relative to a background control Soil Gas Analysis (from monitoring probes)Recommended • Soil gas constituents collected from remediation area reach asymptotic conditions and extraction and monitoring system designs deemed adequate • Soil 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 I