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Chevron Products Company 3 Chevron Ternunal 1001621 22888 Kasson Road Banta CA February 28 2002 • Dissolved oxygen concentrations are generally higher than the baseline levels measured in August or October, 2001 and in some cases over an order of magnitude greater, • Temperature in groundwater has declined in all wells since the test inception Changes in temperature may be related to seasonal atmospheric temperatures • Conductivity (specific conductance) of groundwater has generally decreased since the beginning of the test, • Oxidation-reduction potential (ORP) exhibits a general downward trend following a distinct rise in early to mid-October in most wells, • pH has generally increased, ranging from 6 7 to 7 5 in August 2001 to 7 2 to 7 93 in January 2002, • Depth to groundwater has generally increased (groundwater elevation decrease) which may be attributable to seasonal precipitation/infiltration Groundwater samples are routinely collected from wells MW-24A through MW-32A Review of Iaboratory test results between August 17, 2001 and January 24, 2002 suggest • In MW-24A TPHd concentrations have generally increased while the MtBE concentrations remain about the same, (figures D-1, D-2), • TPHd concentrations have decreased in MW-25, after consecutive TPHd concentration increases MtBE concentrations have remained less than the methanol detection limit, (Figures D-3,D-4), . • In MW-26A, TPHd concentrations continue to decreased while MtBE concentrations remain about the same, (Figures D-5, D-6), • After a distinct increase in MW-27A, TPHd concentrations have decreased After a distinct decreasing trend MtBE concentrations have increased, (Figures D-7, D-8), • TPHd concentrations increased in MW-28A during the January 24, 2002 sampling event while MtBE concentrations continued to decrease, (Figure D-9 and D-10), • MW-29A,TPHd and MtBE concentrations both increased this period, (Figure D-11 and D-12), • MW-30A through MW-32A exhibited an MtBE decreases and a TPHd increase, (Figure D-13,D-18), • General inorganic parameters collected included manganese, alkalinity, nitrite, total organic carbon, sulfate and chemical oxygen demand No obvious trends or remarkable results are observable, • Methanol and ethanol were reported below laboratory detection limits, MtBE concentrations vs time plots of monitoring wells MW-24A through MW-32A are presented in Attachment D, Test wells TW-5 and TW-6 appeared to operate continuously during the period and the nearby local monitoring wells had measured dissolved oxygen levels between 5 30 milligrams per liter (mg/1) and 7 99 mg/l All wells sampled in this month except for MW- I\Chevron\100162APertodtc MonrtonngUSO GEN MonthlyUan 02 ISOGEN status report doc