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' Impact to Underlying Groundwater/Impact to Downgrad,.pit Wells: In all considerations to the groundwater,the conclusion from the soil borings demonstrate that the soil profile has layers of clay that have varying percentages of clay content,all being high,which will slow the penetration from surface water percolation down to the water table. This slowing of the percolation allows for a greater impact of drying periods. This dairy system will have a water storage volume that has a capacity greater than the requirements I from both the county and state. The minimum required storage is 180 days.The calculated capacity for this system,which has considered a rainfall year of 22.74 inches(average in the area is 14.74 inches)and a 25 year,24 hour storm of 3.5 inches,and will store 152%of the calculated solids volume in one of two settling ponds and will store 138%of the above average rainfall volume. The storage capacity is 119% considering the inclusion of a 25 year,24 hour storm event. These capacities will allow for containment of a full winter's manure volume,an above average winter rainfall plus a 25 year,24 hour storm water volume. Considering these storage volumes,the waste management system can be managed by plan,not managed by rainfall events. Well managed irrigation and return water flows, along with wet-dry cycles, will cause surface water not to penetrate the approximate 90 feet of the depth to static water table. In order to evaluate future water quality,water wells in the area were tested to establish a baseline of various elements,reference appendix III-B, I to 5 for test results. There were four existing wells at the site.An original well was purported to have been hand dug in the late 1800's. It was approximately 60 feet deep and 48 inches in diameter. The second well was a small 6 inch domestic well near the farmstead.The third well was a 16 inch well near the"Domestic Well #I". The fourth well is the"Domestic well#111. Water samples from the"wet"wells were taken by Howk Systems of Modesto. The hand dug well was dry,consequently,there was no water sample from that well. The other three well samples,TV I,TV2,and TV3 were tested for calcium,magnesium,electro conductivity,pH,nitrate,TDS,total hardness,total coliform and fecal coliform to record there quality for future references. The results are at appendix III-D,1. Three of the four wells were of no value to the new dairy system. They were abandoned under a permit issued to APN#207-12-02 by the San Joaquin County Public Health Services Environmental Health Division,dated 4/26/99.The"Domestic Well#I"is to be used as a water supply to the new dairy site.it will be improved under a permit to be taken in the near future. Note that a test taken from the "Domestic Well#1",appendix III-D,1,had a positive result for the presence of Coliform bacteria. A second water test was taken after extensive pumping from the well for construction grading dust control and moisture applications for proper compaction that indicate an absence of Coliform bacteria,reference appendix III-B, 1-3. There also were samples taken from four surrounding wells.One domestic well(TVW-1)at the Eck ranch to the south west of ground water gradient under the site,one domestic well(TV W-2)at the Trimble ranch to the north east of the ground water gradient under the'site,one domestic well(TVW-3)at the Taro ranch to the up gradient of the site and a OID irrigation well (TVW-5)down gradient to the site. Water samples from these four wells were transferred under chain of custody from American Geological Services to A&L Western Agricultural Laboratories in Modesto. They were analyzed for nitrate,using EPA method 353.2,and tested for TDS,using EPA method 160.1. The results show that nitrate is present in all of the samples. The results taken from four separate wells, including the"Domestic Well 41"having been tested twice, show the results of all wells to be 13 ppm nitrate except for the OID irrigation well(TVW-5)which has only 10 ppm of nitrate. The OID well is at xxxx feet deep. Although the presence of nitrate in the ground water indicate that there may be some agricultural contribution contamination,all of these values are well below the maximum contaminant level for drinking water established for nitrate of 45 mg/Liter(ppm). Furthermore,the consistent level of nitrate in the ground water indicates that the nitrate in these waters is more a result of a regional infiltration into the water table,rather than contribution from the any localized source. It is concluded that the proposed new dairy facility will not impact the downgradient ground water. ' Western Design/David Avila 1999 19 t I