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F omplex and variable. Environmental models that attempt to predict pesticided transport in the environment are beyond the scope of this investigation. ubject property is proposed to be developed into a three-parcel subdivision,pesticides alf-lives that may have been applied decades ago,primarily DDT, may be of a very ern. It is a possibility that DDT was applied to the subject property in the 1940s, 50s y 1960s before it was banned in 1972. DDT was used extensively throughout the agricultural fields of the San Joaquin Valley and degradates of DDT are found in virtually all of 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 is important to note that the surface soils currently in-place will undergo considerable physical and chemical changes during project development. These alterations include increases in ultraviolet light exposure, moisture content and aeration. Final concentrations of DDT or its degradates in the play areas or garden areas of each new single family residence cannot be predicted, and it is likely that no pesticide residues even exist. It can be reasonably concluded that the 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, et al. Half-lives in the environment: Air: 17.7 -177 h. Surface water: 73.9 h for a pond 1 in 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 in, 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 DDE. Common name: DDE (p,p'-DDE; o,p'-DDE), product of DDT degradation. Half-lives in the environment: Air: Atmos. transformation lifetime est. to he< 1 d. Surface water: Hydrolytic half-life of >120 yr, est. half-life>300 d in lakes. Groundwater:N/A Sediment: N/A Soil: Field half life of 1000 d Biota: Elimination half-life of 340 d(rainbow trout), 300 d for birds. Page -4- Chesney Consulting