ARCHIVED REPORTS XR0011741 - Laserfiche WebLink

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�. Site Otaracterivation and Soil Remediation Plan: 7500 West Eleventh Street, Tracy, C,4. Page 20 designated on-site treatment area. The proposed treatment area is shown on Figure 10. When the total volume to be spread on any given day has been extracted from the stockpile, the cover will be restored over the area of the pile from which it was removed. The loader and an agricultural tractor equipped with a rototiller will be used to mix thoroughly and spread soil though its full thickness. As each daily batch of soil is taken from the stockpile and added to the soil spread, the spread will be re-tilled- The spread soil will be rototilled daily and periodically gathered into a ' local stockpile and re-spread using a loader. Aeration of the spread soil will continue until the treated material is free of olfactory indicators of the presence of fuel hydrocarbons or it is judged that any remaining olfactory or visual indicators of hydrocarbons remaining in the soil are due to the presence of non-volatile components that cannot be removed by aeration alone. At that point, the spread-of soil will be sampled according to the procedures discussed below under the heading, "Sampling of Treated Soil-" Bioremediation of Contaminated Soil The process of aeration of hydrocarbon-affected soil, in addition to volatizing short-chain fuel hydrocarbons such as gasoline, also, by virtue of introducing oxygen into the soil, accelerates the natural processes of bioremediation. By this mechanism, the concentration of longer-chain fuel hydrocarbons, such as diesel, can also be reduced by the aeration process. In addition, bioremediation of soil affected by diesel will continue to occur if sufficient oxygen is infused through it to stimulate biotic action. However, if the moisture content of the soil falls when the temperature of the spread soil is raised in hot weather, bioremediation slows and may cease until water is re-introduced into the soil. I � Thus, in climates where there may be long periods between rainfall, as is the case in the San Joaquin Valley, the required reduction in the concentration of diesel in treated soil may not be achieved for a long time. Where it is necessary J or desirable to accelerate the process of bioremediation, moisture content of the soil must be periodically increased to a level approaching full saturation in r order to maintain vigorous biotic activity- The rate of remediation may also be } accelerated by introduction of nutrients into the soil. If the results of analyses of samples recovered from the soil after aeration show that diesel remains in the spread of soil at concentrations above the established cleanup criterion for that analyte, the remediation program will be extended to include treatment methods that will enhance the natural process of bioremediation. Should bioremediation be required, the land-farming method will be used. This method employs native biota in the soil to convert the hydrocarbon compounds into innocuous water and gases. The activity of the native biota is stimulated by providing access to oxygen by tilling the spread soil, moisture by irrigating the spread soil, and nutrients in the form of common agricultural fertilizers sic li