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v. r� 3.) Septic System Contribution: Data from various sources such as independent investigators, the U.S. EPA, and the Regional Water Quality Control Board estimate nitrogen loadings from domestic sewage to be 12 grams N per person per day (g Nlcapitalday) to a high of 90 g N/capitalday. Hantzche and Finnemore (1992) correlated septic tank effluent concentrations multiplied by water discharge to the septic tank. They formulated a water discharge of 100 gal/capita/day with an effluent concentration of 30-60 mg NIL. It is our opinion that 60 mg NIL is most accurate. The following calculations determine nitrate-nitrogen loading from septic system contributions: 12 people max. on-site x 100 gals/day = 1200 gals x 3.79 L/gal=4545 L/d x 60 mg NIL = 273 grins N/day x 365 days/yr= 100 kg Nlyr x 2.2 lb/kg= 220 lbs Nlyr. 4.) DAIRY NITROGEN PRODUCTION CALCULATIONS It is important to note that the Borba's plan to sell most of the manure solids produced by the dairy for off-site use. However,the following calculations demonstrate the facility is completely self-supporting and may apply both liquid and solid manure forms on all cropland acreage controlled by the Borba's without overload. The total nitrogen excreted from dairy animals is difficult to quantify since the rates of several important nitrogen transformation processes can only be predicted. Secondly, the fact that the animals will be confined under two different housing structures (loafing vs. freestall) during different times of the year creates differences in nitrogen loading. The following calculations incorporate the use of animal units (AU) for the Holstein dairy cow to formulate nitrogen loading. The nitrogen loading calculations for the milk cows is based on exclusive use of freestalls. The nitrogen loading calculations for the dry stock is based on exclusive use of the loafing barns with flushed alleys. This provides a more conservative approach for total nitrogen loading. The animal numbers are the maximum number the facility can support: TOTAL ANIMALS ANIMAL UNIT TOTAL ANIMAL UNITS 1000 Milk Cows x 1.4 = 1400 250 Dry Cows x 1.2 = 300 500 Bred Heifers x 1.1 = 550 270 Heifers 1-2 yr x 1.1 – 297 95 Calves x 0.5 = 48 40 Baby x 0.25 = 10 SUBTOTAL MILK COWS AUs ........................................ 1400 SUBTOTAL DRY STOCK AUs ........................................ 1205 TOTAL ANIMAL UNITS .................................................. 2605 7 —ij Vaffey Ag*.search