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ADDENDUM I Attached are the daily inventory reconciliation records for the Tesoro Stockton Terminal . Although the daily inventories are important, the month-to-date at the end on each mon is the most accurate because it should have averaged the inventories over enough readings to be within the acceptable ± 0.25 vol% range. Tesoro uses an inventory re onciliation value of ± 0.25 vol%. An accurate number on the precision of these inventory reconciliations is not practical to determine as long as they fall within the ± 0.25 vol% range. Starting on page 11 of the attached API publication "Chapter 13-Statistical Aspects of Measuring and Sampling ' there is a good explanation of accuracy in tank gauging (length measure) converted to volume (gallons) measurement. As can be seen from this publication, there are various random errors, biases and inaccuracies that will impact the final true results. This analysis indicates a final precision of ± 0.20 vol% for a dead (non-moving) tank volume. Associate this ± 0. Ovol% deviation with those expected from the two meters (receiving and shi )ping) and vapor recovery unit losses, then a total accuracy of ± 0.25% ol% is acceptable. MONTHLY IN ENTORY DISCUSSION September - 1987 Terminal indicates overall g in of 195 gallons. Therefore no further reconciliation is needed. October - 1987 Terminal had net gain of 2,030 gallons on 5,409,535 gallons handled or + 0.037 volume % gain. November - 1987 Terminal had net gain of 6,313 gallons on 5,472,638 gallons handled or + .115 vol % gain. Unleaded premium meter appears to have started drifting during this month. Meter proved on 12-2-87. Meter accuracy was calculated at 99.790% before correction. The meter correction will pull the unleaded premium loss/gain to a gain of + 126 gallons. Therefore there were no losses from the terminal . December - 1987 Terminal reported + 2,906 gallon gain on all products. This is + .0548 vol % on the total volume handled. However, premium meter appears to started acting erratic toward the end of the month as inventories show. The premium inventory monthly deviation is - 0.264 vol%. This is borderline acceptable and needs further watching. January 1988 Terminal reported -2,737 gallons on total of 6,130,637 gallons T handled. his is a deviation of -.0446 volume %; however, premium meter appears to have drifted out of acceptable range on or about 1-21-88. Terminal checks gauging to ensure no losses due to leakage on a regular basis. i I If