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rco ince most of the property is in agricultural production, the forage production land would most ikely show severe stress if there was shallow subsurface contamination. It is usually only after a contaminant plume has impacted a domestic well that buried pesticide containers are discovered. If buried items are discovered during any future earthwork procedures, etc., the San Joaquin. County Environmental Health Department must be contacted immediately. § 3.3, § 3.4, § 3.5 It is a possibility minute volumes of agrichemicals sprayed on surrounding properties may drift onto the subject property. The site can be considered in the predominant downgradient windshed to other agricultural production acreage. In addition, the San Joaquin County Mosquito Abatement District may spray for mosquitoes on and around the property. Available Environmental Fate Data for the herbicide material Roundup applied to the property as documented on the Envirolm ental Questionnaire, are found in Appendix D. Environmental'Fate Data is summarized in the chart found in the next section. The data shows that the material Roundup is moderately persistent with little threat to groundwater contamination. Mixing of this material occurs by filling the illustrated spray rig with water, then adding the-roundup material. Consequently, cross-contamination cannot occur. Photographic Plate J depicts the sprayer used for applications. fAn important concern associated with the environmental assessment of open properties is the issue of buried containers or discarded items. It was an occasional practice to dispose of containers or discarded items by this method many years ago. To detect these types of underground artifacts is difficult even with the use of ground penetrating radar or other types of non-intrusive, subsurface analyses. From previous Nitrate Loading and Soil Suitability Studies done in this area, it is known there are high concentrations of nitrate in the underlying water table and drinking water aquifers. This can be attributed to the intensely farmed region and the relatively shallow water table. ,Static groundwater is found at approximately 12 feet under the property as illustrated on the attached 1999 Lines of Equal Depth to Groundwater map. From the 2003 Lines of Equal Elevation of Groundwater, the groundwater directional flow is indeterminable, but most likely moving toward the San Joaquin River; however, the gradient is most likely very flat and is assuredly influenced by irrigation recharge and tidal action. Due to this shallow water table, impact from serious point source releases, and/or agrichemicals such as pesticides and herbicides can readily occur. The degree of impact from adverse constituents can be mitigated when clay soil exists from the soil surface down to the water table depth. A Soil Suitability Study will be required by EHD for this project. At that time, the irrigation and domestic wells can be sampled, which will reveal the nitrate concentration in the underlying aquifers. i i i Page -4- Chesney Consulting