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1 <br /> reaches maximum air flow. In this case, the air-flow curve can be <br /> interpolated to estimate the expected vacuum at higher air flows. When <br /> specifying remediation system parameters, the manufacturer of the blower <br /> will need to know the vacuum load that the system will be operating under <br /> so the most efficient blower motor can be applied. <br /> This test segment will continue until the VOC concentrations stabilize. <br /> VOC Concentration Curve <br /> This test segment begins with the blower at the maximum flow rate, or break over <br /> point, as applicable. The VOC concentrations are monitored by hexane-calibrated <br /> FID in ppmv as the air flow rate is decreased from the maximum in increments of <br /> 25 cfm. A curve is plotted with VOC concentrations on the Y-axis and air flow in <br /> CFM on the x-axis. The VOC concentration curve is used to determine the <br /> optimum air flow to match the volatilization rate of the VOC. The air flow curve <br /> will indicate where the air flow rate surpasses the maximum volatilization rate of <br /> the VOCs. If excessive air is drawn through the soil, the soil vapor is diluted by <br /> the air, concentrations of VOC will begin to drop and efficiency will decline. <br /> Average Well Yield <br /> The purpose of measuring the average well yield is collect an air sample for <br /> analysis and subsequent determination of SVE emissions per day. Once the VOC <br /> concentrations have stabilized and an optimum flow rate determined, the well yield <br /> will be monitored by hexane-calibrated FID for one hour at 15 minute intervals. <br /> The variables to be monitored are: <br /> i o Intake vacuum (V) <br /> o Intake temperature (Tz) <br /> o Exhaust pressure (P) <br /> o Exhaust temperature (T,) <br /> o Exhaust air flow rate (Q) <br />• o Exhaust VOC concentrations (PPM) <br /> At the last monitoring interval, an air sample will be taken for analysis at a State <br /> certified laboratory. The results of this analysis will be used to project the average <br /> rate of VOC extraction per day. <br /> Air Flow Calculations: <br /> Basis <br />• Air flow calculations are based on information provided by the pitot tube <br /> . manufacturer. <br /> • <br />