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r L� DDD. Common name: DDD, TDE (tetrachlorodiphenylethane), product of DDT deg. Half-lives in the environment: Air: 17.7-177 h Surface water: 2-15.6 yr. Groundwater: 1680-270,000 h based on anaerobic soil study data Sediment: N/A Soil: Field half life of 2-15.6 yrs based on observed rates of biodeg. of DDT Biota: 119 hr in mussels. Environmental Fate Rate Constants or Half-Lives: Volatilization: Aquatic approx. 1 mo. Oxidation: Aquatic half-life approx. 22 yr Hydrolysis: half-life of 570 d @ pH 9 and 190 yr @ pH 5 Biodegradation: Aqueous aerobic half-life of 2-15.6 yr CONCLUSIONS AND RECOMMENDATIONS From visual observations there is no surface contamination on the subject property. The almond trees do not seem to be unduly stressed, other than being at the end of the growing season, which is normal. Unusually stressed, or bare trees at this time of year may be indicative of a subsurface concern. Considering 1.) There is virtually no area to mix agrichemicals and 2.) A pressurized water supply does not exist on the acreage for agrichemical mixing, it is unlikely any mixing was ever done on-site. Therefore, as of the date of this report, it is my opinion that no corrective action is required within the boundaries of the subject property. The probability of subsurface contamination from pesticides, or other types of agrichemicals, can be considered low-to-nonexistent, considering the environmental fate data for DDT and related compounds presented above. The depth to groundwater of 25 feet would make impact from adverse constituents a higher probability in comparison to a deeper groundwater depth. However,the surface and subsurface soil types are a sandy-silt soil with a higher biological activity than in a sandy soil, and therefore, higher mitigation capacity. The probability for nitrate contamination of the underlying aquifers originating from surrounding septic systems is low due to the low density of systems in the study area. If high nitrate concentrations are found in the well water, it may be attributed to agricultural fertilizer inputs. Prospective buyers of the proposed parcels must realize that the subject property is surrounded by agricultural production land. Consequences of this surrounding land use include: Dust, odors, insects, agrichemical sprays, aircraft, machinery, trucks, exhaust and other environmental effects that may be offensive to some people. Page -5- Chaney CmuuhiW