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I TEMA VAC Nutrients G a Both organic and inorganic nutrients must be available to support bio-activity in soil and groundwater. Petroleum hydrocarbons and carbon dioxide are examples of organic nutrients. Analytical data from the fourth quarter sampling event indicates the presence of petroleum hydrocarbons in all but three of the monitoring wells. Fourth quarter 1996 analytical data are summarized on Appendix A. Microorganisms that derive their carbon source and energy for synthesis from organic carbon are called Chemoheterotrphs. Analytical data indicate detectable concentrations of several inorganic chemicals that serve as yt g nutrients that promote bio-activity (summarized on Table 1). These include Oxygen, Nitrates, ortho phosphate (the soluble form of phosphorous), and ferrous iron (Balser, p 101). Oxygen, nitrate and ortho phosphate are considered to be the most important inorganic nutrients to support bio-activity. Ferrous iron is also a required nutrient, but to a lessor extent. Microorganisms break down organic compounds (carbon and energy source) by a complex oxidation-reduction series of reactions. The process involves the oxidation of organic compounds 3 coupled with the terminal reduction of inorganic compounds (Baker, p 16). Under aerobic a conditions, oxygen is the preferential terminal reduction acceptor (McAllister, p 162). However, as DO is depleted (anaerobic conditions) from groundwater, nitrate and sulfate become the preferential terminal reduction acceptors. Anaerobic biodegradation has been found to be less efficient and therefore slower than aerobic biodegradation(McAllister, p 163). f Table 2 shows the generalized relationship of benzene to nutrient availability if bio-activityis occurring in groundwater TABLE 2 Benzene Oxygen Nitrates Ferrous Tran Sulfates high low low high low low high high low high FINDINGS and CONCLUSIONS Utility Survey Available data indicate that the storm drain is the deepest of the subsurface facilities, approximately S feet below Country Club Boulevard. The trunk that runs along Franklin appears { to be shallower. Gradient of the storm drain is to the south. The sanitary sewer appears to be shallower than the storm drain piping at Country Club, but becomes deeper going north. Gradient of the sanitary sewer is to the north, along Franklin Ave. Project 30-0212 r April 17, 1997 4