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• tnnedy/Jenks Consultants ' • Percolate moves downward from the bottom of the root zone, which is assumed to be at approximately 5 feet below ground surface, at a rate dependent on irrigation rate and properties of underlying soil/sediment layers. Ultimately, this water reaches groundwater ' at a depth of approximately 85 feet. • The primary protective features of the proposed irrigation program are the low percolate flux projected for the site(s); depth to groundwater and the quality of the reclaimed water. • While land treatment of the reclaimed water is not necessary for full beneficial use, nitrate and other inorganic dissolved solids are partially removed by crop uptake. Concentrations of inorganic constituents, including nitrogen, sodium and chloride, are altered during flow through the root zone. Some inorganic dissolved solids may be temporarily stored in root zone and upper vadose zone soils. Nitrate loss typically occurs via plant uptake and denitrification and/or volatilization. Nitrate concentrations may have ' to be supplemented. • Inorganic constituents move through the vadose zone with some change due to natural geochemical calcium and carbonate cycling. ' A series of subsurface layers were encountered at the Jepsen Webb Ranch and presumably exist at the Valley View Thoroughbred Farm. Soil characteristics corresponding to the soil types encountered at different depths were entered into the model. The distribution of soil types with depth in Table 4 was used to represent the entire Jepsen Webb Ranch site. Soil hydraulic properties were used in model calculations to demonstrate the possible range in vadose zone flow at the site. An assumed boundary condition was a near-saturated constant head boundary established at a depth of 5 cm below the surface. The surface boundary consisted of time varying soil percolate flux of 5.3 inches per year. For the purpose of this ' evaluation, calculations were made for a period of twenty years. Initial conditions used for the model are predicated on past use of the site for agriculture ' purposes. Soils were initially assumed to be at or slightly above field capacity; a water potential of-118 crn was used as an initial condition. ' 6.2.3 Model Results A sensitivity analysis was made for the variable of soil types using two sets of soil configurations ' to evaluate the range in soil types and layer depths. Results from the two cases were very similar, indicating the results are fairly insensitive to these factors. Results for one of the cases are discussed here. ' Figure 7 shows model results estimating the subsurface hydraulic conditions. The upper graph shows the water content distribution in the different soil layers with depth and time. The pattern of water content highlights the subsurface layering present under the reclamation areas. A clay ' layer at approximately 8 feet (238 cm) impedes water flow resulting in higher water content (0.36 cm/cm)just above that layer. Once soil water builds up so that the hydraulic conductivity of the clay equals that of the underlying layer, water flows through that sandy loam material at a ' water content of approximately 0.09 cm/cm. Similarly,water content increases just above the silty clay layer at approximately 22 feet (665 cm) until the hydraulic conductivity of the layers match and flow is initiated into the silty clay. The sandy loam water content is lower because the ' clay layer"smoothes"the pulses of percolate so that flow can occur under partially saturated Reclamation Report, Page 18 ' Musco Family Olive Company q:`asryov�uMNnyoE1g202fitiN.q�mrscoGire`A4repoikY=damaticn N"rnuttoreGamaEort repaRiext B.120.1.dx