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Mr Chuck Carmel August 15, 1994 . Page 2 All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-G) and benzene, toluene, ethylbenzene, and xylenes (BTEX) by U S Environmental Protection Agency (EPA) Methods 5030/8020/DHS LUFT Quarterly Monitoring Results and Discussion The general groundwater flow across the site is to the south with an average hydraulic gradient of 0 002 Water level data are listed in Table 1 Table 2 shows past and present hydraulic gradients and groundwater flow directions Figure I illustrates groundwater contours and the groundwater flow direction Well W-2B was not used for contouring, as this well is completed in a deeper zone than the other wells Well W-2A was not used in contounng because this well contained only a small amount of water that likely has collected in the end cap and is not representative of the water table surface The current southerly flow direction and gradient of 0 002 are within the ranges previously reported On March 22, 1994, the depth to water ranged from 59 27 feet to 62 29 feet Water levels in the monitoring wells increased an average of 3 82 feet between November 16, 1993, and March 22, 1994 . Current and historical analytical results are summarized in Table 3 The complete laboratory reports, including chain-of-custody documentation, for the quarterly sampling are presented in Exhibit B BTEX and TPH-G were not detected in any of the sampled wells except well W-3 The detection limits for the BTEX constituents and TPH-G are 0 3 to 0 5 and 10 micrograms per liter (pg/1), respectively Well W-3 contained 0 4 µg11 of both benzene and toluene, and 0 5 µg/1 of xylenes Ethylbenzene and TPH-G were below detection limas The presence of BTEX constituents in this well is new since February 1993 However, the detected values are very close to laboratory detection limits which are lower than previous quarterly events Status of Site Remediation This section provides a description of the remediation system and discusses the effectiveness of the remediation system operation Description. The remediation system at ARCO Station 434 consists of a groundwater extraction and treatment system (GWETS) and soil vapor extraction and treatment system (SVETS) The GWETS consists of one groundwater extraction well (E-1) with a designed pumping capacity of 1 gallon per minute Treatment of the extracted groundwater is accomplished with two granular activated carbon vessels, each having 1,000-pound capacity Groundwater is extracted from the well via a submersible pump Discharge of the treated Use or disclosure of data contained on this sheet is subject to the restrlctton specified at the beginning of this document 1318%REPORTSM Sr94QTR RPC