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— Impact to Underlying Groundwater and Downgradient 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 from both the county and state. The minimum required storage is 180 days. The calculated capacity for the existing system is: — RoF S 10 Nutrient Lagoon- 17,092,447 gallons Existing Settling Pond- 2,674,226 gallons Existing Settling Pond- 267,008 gallons =' Existing Settling Pond 1,118,921 gallons Future Settling Pond 2,674,226agallons .izriu Total Storage 23,826,828 gallons These capacities will allow for containment of a full winter's manure volumt 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 10-18 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 appcndix 111i for test results. A water sample was taken from one of the four domestic wells at the Lima Dairy milking facility. A water sample was taken from the domestic well at the Lima heifer facility. A water sample was taken from a domestic well at 4484 West Tredway Road. A water sample was taken from a domestic well at 13151 Neeley Road. A water sample was taken from a domestic well at 5882 West Kingdon Road. Water samples from these five wells were analyzed by A&L Western Agricultural Laboratories in Modesto.The samples were tested for nitrate,using EPA method 353.2,and tested for TDS,using EPA method 160.1. The result show that nitrates is present in all of the samples. The presence of nitrate in the ground water indicates that there may be some agricultural contribution. 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 a localized source. There may be factors contributing to the regional infiltration into the water table from the surrounding area, including the White Slough,and the wildlife area located to the west of the facility,within 2 miles,and ongoing agricultural activity in the surrounding area. The White Slough Waste Water Treatment Facility has one of the only monitoring well programs in the area. Information from those wells may be more useful than information from domestic wells,since they tap the uppermost groundwater aquifers,and five of the wells form a rough circle around the Lima Dairy site. See Ground Water Well Location Map,Appendix QIA. Information from that program shows that one well,well number 5, went above the 45 ppm limit for a two-year period from October 1994 to August 1996,and has stayed below the limit since then. Well number 3 had two readings above the limit,one in May 1993,and once in March 1996. Well no. 5 is located approximately one mile to the south of the dairy facility,and well no. 3 is located about 6/10 of a mile to the south of the dairy facility. Neither well is downgradient of the dairy, since groundwater flow is approximately due west. See Lines of Equal Elevation,Appendix HIM. It is nonconclusive if these sources impact the test results of the dairy facility without further monitoring. With proper management by the dairy in balancing effluent with crop uptake,and annual monitoring of the premises prior to new crop planting,the proposed dairy expansion should not impact downgradient groundwater. 1. Reference San Joaquin Caliomia Flood Control&Water Conservation District Spring 1998 Groundwater Report °Western Design/David Avila 2001 18