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Appendix A 200 milliliters per minute. The purge rate,total purge volume,and measured vacuum will be recorded in the field logbook. • If a vapor flow of 100 ml/min cannot be achieved with a maximum vac uu of 10 inches of mercury or 36 inches of water,work should cease until the cause of the problem is identified and corrected. If the cause of the flow condition cannot be addressed,the vapor probe is to I ie abandoned and reinstalled at a location approximately 5 feet away from the original locati . • After the desired volume of vapor is purged from the system,but before the pump is turned off,the valve on the"T"is then closed to isolate the pump from the sampling line and prevent ambient air from reentering the sampling line. Once the valve has closed,the pump c2 n be turned off. A1.2.5.3 Sample Collection A1.2.5.3.1 VOCs by EPA TO-15 • A completed sample label will first be attached to the SUMMA canister. The SUMMA canister and flow controller IDs(lab serial number)will be recorded on the field data sheets. • Prior to collection of the sample,a pre-sampling vacuum gauge reading w 11 be collected on the SUMMA canister by attaching the vacuum gauge directly to the canister End fully opening the valve. The vacuum reading in the SUMMA prior to the collection of samples should be approximately 25 inches of mercury. Readings of less than 25 inches of mercury indicate t t the SUMMA has a leak, and should not be used for sample collection. The pre-sampling vacuum eading is recorded and the valve is closed prior to removing the gauge. Ambient air pressure and ter aperature will also be collected. • The SUMMA canister will then be fitted with the flow controller using a /4-inch inert tubing equipped with a barbed,quick-disconnect male or female fitting and a f le nut as appropriate. A separate,pre-cleaned,and calibrated stainless steel flow controller from tie laboratory will be used for each SUMMA canister. • The inlet end of the flow controller will then be attached to the third end f the"T-valve" on the sample line using inert tubing,hose clamps or barbed,quick-disconnect I ittings as appropriate. • A rag moistened with the selected leak check compound(butane or isobu tane analyzed by ASTM D1945)will be placed on the ground surface around the annulus of the soil vapor probe. • The valve of the SUMMA canister will then be fully opened,beginning E ample collection at the targeted rate of approximately 150 milliliters per minute. The flow cont ollers will be pre-calibrated by the laboratory for a total sample time of approximately 40 minutes(6 liters of total sample at a rate of 150 milliliters per minute). • After 40 minutes,the valve on the SUMMA canister will be closed and I he canister will be disconnected from the sampling line and the flow controller. • A post-sampling vacuum gauge reading will be collected on the SUMM canister by attaching the vacuum gauge directly to the canister and fully opening the valve. Thepost-sampling vacuum reading is recorded and the valve is closed prior to removing the gauge. KB61125 APPENDIX A MACTEC Engineering and Consulting, Inc. A6 September 28,2005