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Under normal circumstances, it would not be possible for the ground- water table to intercept waste directly since depth of waste placement would only be between 30 to 40 feet below the present ground surface. The poten- tial for groundwater degradation is further reduced since on-site borings indicated no evidence of springs or perched waters.• The impact on the ground- water is also related to the amount of "purification" the leachate attains as it percolates through the subsoil beneath the waste. Another possible source of groundwater quality degradation is carbon dioxide (CO2) gas, generated during the waste decomposition process. Carbon dioxide can be dissolved in water and can cause increased hardness or corrosive conditions. Carbon dioxide could enter groundwater below the study area through two mechanisms; (1) directly via movement of the gas from the refuse through the soil to the groundwater; and/or (2) indirectly via dissolution of CO2 in leachate, which in turn moves to mix with ground- water. The extent to which CO2 gas moves through soil to groundwater is related to travel distance, gas concentrations and soil type. Although these mechanisms are theoretically possible, the overall impact of the groundwater from CO2 gas would be negligible because of the travel distance to the water table (around 100 feet) and proposed mitigation measures discussed in the following section. In general, the study area proposed for a sanitary landfill has attrac- tive characteristics of adequate depth to the water table and the potential for sufficient on-site impermeable material of at least 1 x 10-6 cm/sec or slower which meets or exceeds State standards). With certain mitigation measures discussed in the following section implemented, the direction of groundwater movement affords the opportunity for monitoring and collection of degraded groundwater and subsequent treatment, if necessary. Air Quality It is not anticipated that the proposed landfill operation will result in significant degradation of air quality. Operation of the landfill would simply be an extension of the existing landfill located one to two miles west of the proposed site. The only change from the current situation would be that most private and commercial vehicles hauling refuse to the new site would have to travel an additional two to four miles, roundtrip. However, the State EIR Guidelines require that individually minor actions which contribute to a collectively significant impact must be discussed as a cumulatively signifi- cant effect. Estimates were made of the air quality impacts which could result from the additional two to -four miles roundtrip. Assumptions made for these estimates are as follows: Refuse generation would be according to projections in the Solid Waste Management Plan for San Joaquin County, June 1979. The "worst case", or three percent annual increase, projections were used.