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t Vapor Extraction System Sample Calculations Moore Petroleum,Inc.,5491 'T"Street,Banta,CA t � � i VAPOR EXTRACTION SAMPLE CALCULATIONS j Calculating Daily Extraction Rates Once given the vapor analytical results in ug/1 and the corresponding system flow rate for that sampling event in cubic feet per minute(CFM), a daily extraction rate may be calculated in pounds per day(1b./day). The sample calculations will be focused on the sampling event which occurred on September 19, 1995. This sampling event yielded concentrations of total petroleum hydrocarbons(TPH), as Lgasoline, at 1,500 ug/l, and benzene concentrations at 39 ug/1. The system flow rate on this day h was 10 CFM. i The method for calculating daily extraction rates is to take the analytical concentrations which are reported in ug/1 and, using standard conversions, convert this value to units of pounds per cubic rfoot. This value may then be multiplied by the system flow rate on the day the sample was L collected, in CFM, and then converted to units of days. The result will be the daily extraction rate in lb./day. An example of this method is as follows: i µg 28.3171 1 Ib ft3 1440 min lb concentration ( 7 )" ft 3 x 4.54x10 gµg Xow rate ( )x =extraction rateO Min daIf this method is applied to the TPH, as gasoline, concentrations, the following daily extraction rate results: 1,500 µg x 28.317 l x 1 lb - x 10 ft3 X 1440 min= 1.3 lb TPH,as gasoline l ft 3 4.54x108 99 mm day day This method may also be applied to the benzene concentrations present in the vapor sample: µg 28.317 l 1 lb ft 3 1440 min lb 39 —x x X10 X 0.035 Benzene l ft 3.. 4.54x10 8µg min dam' day Once the daily extraction rates are known,the cumulative quantities of TPH, as gasoline, and benzene can be calculated. It will be assumed that the average daily extraction rate for a i` particular period will lie somewhere between the most recent daily extraction rate and the previously calculated daily extraction rate. It will be assumed that a sufficient approximation of the average daily extraction rate for a particular period of time will be the most recent daily extraction rate averaged with the previously calculated daily extraction rate.