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After project development, a percentage of the land surface will be impermeably covered with structures, concrete, etc. This will have an attenuating effect on the, downward migration of nitrate molecules currently "in-transit" and on nitrate yet to be formed. These impermeable surfaces will be traded for potential point sources of nitrate: on-site septic systems, lawns, and landscaping Domestic irrigation recharge can account for 250 to 1,500 gallons of water/day/residence during the spring and summer months (approx. 6 mos. out of the yr). Excessive].awn and landscape watering can lead to nitrogen leaching, and runoff to open areas. However, conversely, the groundwater pumped either by the CSA-44 wells, or by on-site domestic wells, and used for domestic irrigation can reduce the mass balance of nitrate since all plants readily use nitrate as a food source. This is provided of course,that fertilizer is carefully applied to lawns, gardens and landscaping, if at all. For example: 38 ppm NO3 as tested for the Cole well=38 ppm x 0.00 13 6= 103.4 lbs of NO3/Ac ft of water. If an average of 750 gallons of domestic irrigation water is used each day for six months= 180 days x 750 gals/day= 135,000 gals (roughly '/2 ac-ft of water). 133.4 lbs NO3 x 0.5 = 52 lbs NO3 applied by %z ac-ft of domestic irrigation water. Kentucky blue grass requires 124 lbs N/ac/yr, or if 1/3 of a parcel is planted in blue grass=42 lbs N/'/s ac/yr for optimum growth. Therefore, 1/z ac- ft of domestic irrigation at 38 ppm NO3 supplies 124% of the nitrogen required by this grass. C. WASTEWATER FLOW CALCULATIONS AND CHARACTERISTICS Domestic wastewater flows managed by on-site septic systems have been studied for decades with variable data published in the scientific literature. Wastewater flows for this project will be assessed on a "future" basis whereby it will be assumed the existing household and future households will have 4 persons per house (husband, wife and two children). There is a mother- in-law unit to the east of the existing house. It is assumed that one person will occupy this unit and has therefore, been added to the calculations. The total daily water use is a combination of household and personal uses, as itemized below: HOUSEHOLD PERSONAL USE 25 gal for laundry 2 gal for drinking and cooking 10 gal for dishwashing 3 gal for oral hygiene 5 gal for mise. use 14 gal for bathing 16 gal for toilet flushing/sink washing FLOW RATE in gals/home/day= 40 gals/household/day+(35 gal/person/day x number of persons/home). The daily wastewater flow rate can be estimated at: 40 gals+ (35 gals x 4 people/home) = 180 gals/day for an average flow per resident of 45 gals. As a safety factor, the total daily wastewater flow per house and average daily flow per resident will be increased 1.5x to 270 gals/day and 68 gals/resident, respectively. The peaking factor for individual residences on septic tanks will vary with the day of the week and usage. Peak hourly rates are normally associated with the discharge of clothes wash machines, dishwashers and shower/bath water. The ratio of the peak day to the average day can vary from 1.5 to >5, depending upon the time of the year and usage. I Page -5- Vaffey Ag Research 4