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VI. CONCLUSIONS AND RECOMMENDATIONS From visual observations, there is no surface contamination from hazardous materials or hazardous t environmental conditions. Section 9-905.12 of San Joaquin County Development Title states "Corrective Action: If the report indicates there are surface and subsurface contamination, corrective action shall be recommended in the report and concurred with by Environmental Health prior to the issuance of the building permit." Although no visible surface contamination was observed, investigating the concrete structure that might be a septic tank is prudent. This should be done with a backhoe or excavator. It is my professional opinion that this is the only"corrective action" required on the subject property. The septic system density can be considered comparatively high in the Morada area, and surrounding areas. As referenced, nitrate impact from this source may not be an issue at this point in time. The soils under the subject Parcels have historically had limited surface and subsurface percolation. Therefore, it will be a requirement of EHD to install sumps and seepage pits to manage septic effluent from future residential structures. Given that agricultural irrigation J) recharge is the largest single contributor to groundwater nitrate concentrations, and since the surrounding land has been farmed for several decades, it is assumed that the nitrate concentrations in the underlying groundwater would be in much higher concentrations than what has been observed in this area. Consequently, attenuating factors must be significant. As noted on the 1999 Lines of Equal Depth groundwater map, the static groundwater depth is approximately 65 feet. The lines of Equal Elevation map shows the groundwater directional flow to be in a southeasterly direction. The frontage road bordering the property and the areas in the "back"of the property should be patrolled on a regular basis to ensure there is no dumping of hazardous materials such as drug manufacturing chemicals. The ASTM E-1527-00 Document referenced on Page 2 refers to de minimus environmental conditions. De minimus conditions generally do not present a material risk to public health or to the environment and generally would not include an enforcement action if observed by the appropriate governmental agencies. Household hazardous materials may be considered de minimus concerns if there has been no spillage or dumping. Spillage and dumping of any hazardous substance was not observed. The subject site is surrounded by properties to the north that engage in production agriculture. Noise and air pollution emanate from the Highway 99 Freeway. Consequences of this land use include: noise, dust, odors, insects, machinery, crop dusting aircraft, trucks, exhaust and other environmental effects that may be offensive to some people. 7 Chesney Consulting