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In addition to the parameters quantified above, the carbon-nitrogen(C:N) ratio was analyzed from the Lawson leachfield soil. The C:N ratio signifies the potential for nitrate formation within the soil environment. Soil organic residues with a low C:N ratio indicate a greater probability of higher nitrate concentrations. A ratio of 4:1 was determined from the soil analyses; however,the nitrate concentration was low. This theoretically indicates that carbon levels which were once at higher concentrations in the soil have now entered equilibrium,thus causing a decrease in nitrate concentration due to microbial uptake. To assess the project from a septic system viability standpoint, "Application for Permit" records at the Environmental Health Department were reviewed. Applications on file reveal there have been 16 permits issued for repairs/additions to existing systems in a one-half mile radius from the center of the project. Sixteen permits in this study area can be regarded as excessive, considering the relatively sandy soil. Explanations for these repairs/additions may be that installed systems were under-designed. However, it is probable the failed leachlines were placed above the referenced hardpan strata without breaching this strata. C. SOIL PERCOLATION Perc tests were conducted on September 2, 1994 by Wong Engineers, Inc. under observation by the San Joaquin County Department of Environmental Health. The test results indicated a perc rate of 13 min/inch. Although it is well documented the surface soils consist of permeable characteristics, a confirmation perc test was performed by our firm in the area of what is now the Lawson Trucking filter bed. This test was conducted under U.S.E.P.A. and Department of Environmental Health guidelines. Since the soil at the test depth of 40 inches is sandy and six inches of water seeped away after one-half hour,the test was conducted over a two-hour period. This ensured complete soil saturation and allowed observation of any influence by the underlying hardpan layer. The perc rate remained relatively constant throughout the test period with the final perc rate of approximately 9 min/in. D. GROUNDWATER INFORMATION Groundwater elevation measurements taken in December 1998 indicate the groundwater elevation is approximately at-0.6 ft mean sea level (MSL). The average elevation of the site is 20 feet above MSL and the east retention basin is at 10 ft MSL. The static water table was measured at 10.6 ft below the floor of the basin. From this elevation,the depth to groundwater is approximately 20 feet below grade. It appears from static water level measurements made of the on-site wells,the groundwater is flowing in a westerly direction. The groundwater in this locale seems to be influenced by Interstate 5. West of the Interstate,the water level is approximately 10 feet below grade based on previous studies. The reason for this influence is unknown without in- depth studies. As with most groundwater tables,there are fluctuations in elevation. The critical issue regarding the groundwater elevation under the subject property is that there is sufficient distance between the soil/effluent interface and the highest anticipated depth to groundwater for adequate treatment of effluent to occur. 3 Nalfey Aa Ppearck