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4 - � <br /> STATE OF CALIFORNIA—CALIFORNIA ENVIRONME. 'ROTECTION AGENCY PETE WILSON,Governor <br /> DEPARTMENT OF TOXIC SUBSTANCES CONTROL <br /> 400 P STREET,4TH FLOOR <br /> P.O.BOX 806 <br /> SACRAMENTO,CA 95812-0806 <br /> (916) 323-3372 <br /> u <br /> June 5, 1996 <br /> Ms . Laura M. Bazeley, R.G. <br /> WZI Incorporated <br /> 4700 Stockdale Highway, Suite 120 <br /> Bakersfield, California 93309 . <br /> RE : Review and Comment on the Proposed Performance Goals for <br /> Soil Vapor Extraction Systems Dated May 6 , 1996 <br /> Dear Ms . Bazeley: <br /> The Department of Toxic Substances Control (DTSC) has <br /> reviewed your revised performance goals for soil vapor extraction <br /> systems at Lustre-Cal, Busy Bee, and Guild Sites dated May 6, <br /> 1996 . The Department has the following comments : <br /> 1 . Page 2 . Section 2 . "Performance Criteria" . The primary <br /> performance criterion is based on operating the SVE systems until <br /> asymptotic stabilization of VOC concentrations has been achieved <br /> and a rebound assessment period of 12-months has been completed. <br /> DTSC comment : A statement shall be added in this paragraph <br /> to clarify that the 12-months rebound assessment period applies <br /> only when the SVE systems are functional and operational . Any <br /> shutdown of the SVE due to physical, mechanical, any other <br /> problems, or repairment are not included in the 12-months <br /> assessment period. This term should also be defined in the <br /> "Terminology" section. <br /> 2 . Page 4 . Section 4 . 2 . "SVE Full Scale Operation" . The <br /> specified Figure 1 is missing from the document . <br /> 3 . Page 5 . Section 4 . 3 . "SVE System Mass Removal Rate <br /> Stabilization" . The "Stabilization" is to be defined as when (1) <br /> mass removal rates do not vary by more than 2% during four <br /> consecutive weekly monitoring events, and (2) VOC concentrations <br /> in extracted vapor do not vary by more than 20% over four <br /> consecutive weekly monitoring events . WZI cited that a variety <br /> of technical factors such as laboratory tolerance for analytical <br /> error and field sampling technique repeatability are reasons for <br /> proposing the 20% VOC concentration variance . <br /> DTSC' s Comment : The VOC concentrations in extracted <br /> vapor shall not vary by more than 2% as originally proposed by <br /> WZI . The total VOC concentrations in extracted vapor can be <br /> determined by using the field instrument Flame Ionization <br /> Detector (FID) . This data will provide you with an immediate <br /> Ow <br /> .r <br /> Prinleo on P—Cle0 Pao&. <br />