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_ If the subject leachfield contains inadequate storage capacity, which is a possibility, it will eventually fail by effluent surfacing during climatic stress. V. NITRATE LOADING To calculate the nitrate loading for the proposed project, it is important that accurate wastewater flow volumes be projected as best they can. With a Church facility, this is difficult to do for the following reasons: It is generally assumed that wastewater flow will be heaviest Sunday mornings _ and somewhat less on Sunday evenings. The initial flow volume when a Church becomes operational can be established, but soon increases as the number of Church Parishioners increases. This is unlike a housing subdivision or industrial/commercial facility where the maximum flow can be determined initially and there is usually not much deviation from this maximum determined flow volume. Additionally, as a Church expands, new programs are usually brought on-line such as �- Children's programs, etc. that meet during the weekdays or evenings. Finally, large programs such as a day care or school may be established, significantly changing wastewater flows on a daily basis. Therefore,by using a flow rate of 5 gallons per person per day for a Parishioner population of 700 establishes a "median" flow rate. Initially the flow will be small, but over time, could increase substantially to well over 700 Parishioners. Therefore, when the life of the septic system is considered from the initial start-up, to the time City of Tracy water and sewer arrive to the site, it is our opinion this median or average flow rate is acceptable for nitrate loading calculations. As sewage enters septic tanks, approximately 25% to 33% is part of fecal protein, with the remaining portion as urea. In the septic tank and the soil environment, ammonia from urea and fecal _ protein decomposition combines with water to form the ammonium ion, the precursor to nitrate. Aerobic bacteria oxidize ammonium to nitrate usually within two to five feet of unsaturated (aerobic) soil. This is called nitrification. Virtually complete nitrification of ammonium nitrogen occurs in the unsaturated zone in well-aerated soils under leachfields or mound systems. The per capita ingestion and excretion of nitrogen can be considered reasonably constant with minor variations. Although there are several estimates of nitrogen inflows based upon per capita intake of total nitrogen per day, a conservative estimate is 17 grams N/capita/day. Concerning outflows, most literature evaluates nitrogen discharged from septic systems in concentration units of mg N/L _ (milligrams of nitrogen per liter of effluent). Again, there are several estimates of nitrogen effluent concentrations, however, the average is generally regarded as 62 mg N/L. 6 .01 Vaffey Ag Ppearch