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Two sources of information which attempt to document and define on-site and surrounding past land use were also utilized. The first is the use of aerial photographs. Aerial photographs of the area from 1970 through 1977 found on USDA Soil Maps reveal the property to be open land with the oak trees near Clements Road visible. No buildings, or changes in the land surface are noted. The USDA Soil Map shows the soil to consist of a Redding gravelly loam (#221). Typically, these soil types are moderately well-drained with very slow permeability. A indurated hardpan can be found in the subsoils which will impede septic effluent management in this soil type. The second source of 3. information can be found on USGS maps. The property is on the Clements Quadrangle map, which is found in the Appendix. Again, no buildings are noted on this USGS map, which dates back to 1963. Mr. Lange has provided a list of the agrichemicals applied to the subject vineyard. Applicable Environmental Fate Data that was available for materials that have been applied for the past three years can be found in Appendix C. The wine grapes are irrigated with water from a well north of Stampede Road. This well is located in the middle of a wine grape vineyard. The listed fertilizers are applied through the drip line irrigation system. This is referred to ass fert�n, which is a highly precise method of dosing fertilizers in prescribed amounts so that there is no runoff. There are backflow prevention devices on the wells and pressure breakers to prevent water with fertilizer concentrations from flowing back into the irrigation well. The science of pesticide residues in soil, air, surface water and groundwater is extremely complex and variable. Environmental models that attempt to predict pesticide behavior and transport in the environment are beyond the scope of this investigation. However;pesticides with long half-lives that may have been used or drifted onto the property decades ago,primarily DDT, may be of an extremely slight concern. DDT was used extensively throughout the agricultural fields of the San Joaquin Valley and degradates of DDT can be found in nearly all these soils. Previous Exposure Assessments made on typical San Joaquin Valley soils suggest an extremely low probability of adverse health effects from soil DDT/DDD and DDE concentrations (if the concentrations even exist). It can be reasonably concluded that any DDT, DDE and DDD concentrations will continue to degrade as reported in the published environmental fate data. The environmental fate data for DDT and its degradates DDD and DDE are illustrated below: DDT. Common name: Agritan, Anofex, Azotox, ct al. Half-lives in the environment: Air: 17.7 -177 h. Surface water: 73.9 h for a pond 1 m deep. Degradation half-life of about 10 yr-average from loss rates determined in Lake Michigan. Groundwater: 16 d to 31.3 yr. Sediment: 3 to 5 yr Soil: 2-15.6 yrs based on observed rates of biodegradation in aerobic soils under field conditions. Avg. half life of-12 yrs in 3 different soils for -50 ppm in soil. (conversion of p,p'-DDT to p,p'-DDE). Environmental Fate Rate Constants or Half-Lives: Volatilization: Half-life of 3.7 d for water depth of 1 m, from soil w/h-1 of.578 h Oxidation: Photooxidation half-life of 168-8400 h in water, 17.7-177 h in air Hydrolysis: Estimated first-order half life of 22 yr Biodegradation: Aqueous aerobic half-life of 2-15.6 yrs Page -4- Chesney Consulting