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principles of Hantzsche-Finnemore Equation are still valid, but a rearrangement of terms and <br />calculations is needed to more reasonably estimate the resultant nitrate -nitrogen percolation <br />value. I recommend revising the analysis per the methodology outlined in Attachment 1. <br />2. Other Comments. Other comments that may or not be pertinent following recommended <br />adjustment the methodology (Comment 1) are: <br />a. Wastewater Flow. On page 7, the wastewater flow projection used for the analysis is <br />stated as 600 gpd. This does not agree with the information from Siegfried, which <br />estimates the wastewater flow to be 960 gpd. <br />b. Precipitation Data (Table 4). The values for monthly precipitation values for the Tracy <br />area in Table 4 (page 6) are labeled "2 years in 10" data from the Soil Survey of San <br />Joaquin County. They are stated to be "conservative" (i.e., lower) as compared with <br />average precipitation amounts; but they are actually significantly higher than average <br />monthly precipitation amounts for Tracy. The total of the individual monthly amounts <br />equals 19.54 inches, well above the annual average precipitation for Tracy (10 to 11 <br />inches). The total given at the bottom of Table 4 is correctly copied from the source <br />document (Soil Survey), but I believe it represents the "2 in 10 years" annual total, which <br />is different from the total of the individual monthly values list. The average monthly <br />precipitation values should be used in the nitrate loading analysis instead of the "2 in 10 <br />years" values listed in Table 4. <br />c. Annual Rainfall -Recharge Value. In Table 4 the estimated value for rainfall -recharge <br />("deep percolation') is given as 2.21 inches per year. However, in the calculations that <br />follow (bottom of page S), a value of 9.5 inches per year is inserted for R, without any <br />rationale or reference. <br />4 <br />