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FALL CREEK ENGINEERING,INC. capacity. It must be assumed that typical agronomic practices to maintain optimal pH conditions for nutrient availability will also prevent these soils from becoming increasingly acidic and certainly never close to or lower than pH=-S. Typical agronomic practices such as liming, drive the reactions: CaCO3 +H2O 4 Cat++HCO3"+OH- 4 H-soil + OH' 4 H2O 2 Al-soil+ 3CaCO3 +3H20 --> 3 Ca-soil +2A1(OH)2 + 3CO2 2 Fe-soil + 3CaCO3 + 3H20 4 3 Ca-soil +2Fe(OH)2+ 3CO2 These reactions lead to the consumption of excess protons (H+), exchangeable and soluble aluminum and iron. Additionally this tends to favor the presence of manganese in relatively insoluble forms in various oxides (MnO2), rather than as soluble Mn2+. Again it is not in the best interest of crop production managers to allow increased acidity as manganese toxicity has been shown to be possible in certain coastal soils in California and Oregon at pH levels of 4.8 or less. The displacement of other cations (Na, K, and Mg) from mineral and organic matter exchange sites into the soil solution will occur to an extent. However, in an active cropping cycle, this simply represents a shift and increase in the easily absorbed nutrient pool in soil solution. Attention to and determination of the potassium fixation capacity of these soils may reveal an additional significant natural mechanism to "strip" soluble potassium (assumed to be a significant fraction of FDS) introduced with wastewater and/or displaced due to liming. In conclusion,maintaining the buffer capacity of the LTU will not only be important for the disposal of wastewater, but for the vigor of the crops grown in these areas. This finding should be revised to recognize that the Winery will prepare an operation and maintenance plan and conduct routine soil testing to assure that the LTU is operated to maintain the buffer capacity of the soils to protect groundwater quality and the cropping systems grown in these areas. 41. This finding notes that shock loadings of acidic or basic waste can interfere with microorganisms responsible for oxidation of organic waste constituents. FCE has reviewed wastewater discharge analysis reports for samples dated 10/27/2000 to 11/5/2002. Among 32 samples there were only 5 samples with pH less than 5.0. The mean of all samples was close to 6.4, suggesting there will not be a significant direct "Pressure"on the soil's inherent pH buffer capacity. It should be noted that this effluent acidity is due to the presence of weak and poorly buffered organic acids. There must be a clear distinction between the active and potential acidity arising from poorly dissociated weak organic acids and highly dissociated strong acids and their potential short- and long-term impacts on soil pH and buffering capacity. Clearly a soil's capacity to resist acidification due solely to the introduction of weak acids is greater and longer-lived than is the capacity to resist pH changes resulting from the addition of fertilizers (e.g. ammonium sulfate)that result in the formation of sulfuric acid. The pH buffering capacity of each land treatment field should be estimated(by 5