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June 21,2000 Job Number: LGOO-173 Page 6 A hand auger soil boring was drilled on May 30, 2000 to a depth of 10 feet to characterize the soil profile of the proposed septic field as per the requirements of San Joaquin County Environmental Health Division. No ground water was encountered to a total depth of 10 feet. Generally, layers consisting of sand and silt were encountered in boring(Plate 8). A 7 foot thick brown fine to medium sand with silt (slightly moist) is located between the ground surface and 7 feet in depth. This layer was followed by a 1 foot thick brown sandy silt layer between 7 and 8 feet in depth. The previous layer was followed by a 3 foot thick brown silty sand located between 7 to 10 feet in depth. A shallow percolation test was performed adjacent to the exploratory boring. The percolation test was set at 3.0 feet in depth within soils consisting of a brown sandy silt layer (Plate 8). The percolation test casing was a 2 inch PVC pipe with holes drilled on the bottom. Two inches of"pea gravel"was placed in the bottom of hole,the casing was installed, and several feet of"pea gravel"were backfilled in the annular space. The percolation hole was soaked and a short preliminary test was conducted on May 30,2000 to determine if a 1 hour or 4 hour test was required. Based on a preliminary test, a one hour test would be acceptable. A one hour percolation test was conducted on May 31, 2000 in accordance with the requirements of San Joaquin County Environmental Health Division. The last 1/z hour of the test was observed by Adrienne Ellsaesser, R.E.H.S. of that office. The result of the percolation test indicates a satisfactory peculation rate of 4.4 minlin was achieved. VII. NITRATE LOADING STUDY As mentioned previously, nitrate pollution in ground water often originates from agricultural fertilizers, livestock waste, and untreated septic tank waste. A build up of nitrates in the ground-water may lead to health problems and may cause a temporary blood disorder in infants called methemoglobinemia(blue baby). Serious and occasionally fatal poisonings of infants have occurred following the ingestion of water containing nitrate concentrations greater than 10 mg/l nitrate as N or 45 mg/l nitrate as NO,. The existing or potential sources of nitrogen pollution associated with this project are essentially the agricultural application of nitrogen fertilizer and soil amendments to the existing vineyards, the planned use of a new septic system with the boutique winery, washing of winery tanks, nitrate in ground water used for irrigation,and the nitrate level of rain water. The purpose of the nitrate loading analysis is to identify the potential sources of nitrogen pollution and to evaluate the potential impact of those sources to ground water. The nitrate loading analysis helps pE4t0 i