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drainage patterns of the site,and would not connect to the existing MHCSD storm drain system,this alternative would result in minor impacts in terms of sedimentation/erosion and flooding/exceedance of storm drain capacity. By comparison,the proposed project would include development of the entire project site,off-site infrastructure sites,and Grant Line Village;include grading of the project site;increase impervious surfaces at the site from 15% to 47%;increase 100-year runoff from 930 cubic feet per second(cfs)to 1,206 cfs;increase the velocity of runoff _ from the project site;and increase the demand for capacity in the existing and proposed MHCSD storm drain system.Although these project-related changes would result in less-than-significant sedimentation/erosion and flooding/exceedance of storm drain capacity impacts(with implementation of existing San Joaquin County and MHCSD policies,requirements,and standards with which the project must comply),the proposed project would still — result in an incremental increase in sedimentation/erosion and consumption of storm drain capacity that would not occur under the No-Project Alternative.[Lesser] Water Quality The No-Project Alternative would include the development of 18 new residences on approximately 7 acres of the 815-acre project site.During construction of the new residences, grading, earth moving, excavation,exposure of unprotected soils,erosion,and deposition of fuels from construction equipment and chemicals from construction activities would be expected to be extremely limited because it is likely that only one or two residential units _ would be under construction at any one time(given that the units would be developed on separate parcels and at the discretion of each property owner,rather than as an organized development).Also,little if any urban runoff would be expected to be generated and discharged to Mountain House Creek and Old River associated with these residences given the type and scale of the new development and the fact that most of the project site would remain pervious(resulting in infiltration rather than discharge to surface waters).However,existing agricultural discharges to surface waters would continue unabated and without best management practices(BMPs)to remove agricultural pollutants.Therefore, although this alternative would result in less-than-significant construction and — urban operational water quality impacts,it would allow continuation of agricultural-related water quality impacts. By comparison,the proposed project would include grading and substantial construction activities that would result in the discharge of contaminants to surface waters during project construction,which would represent a significant impact before mitigation but a less-than-significant impact after mitigation implementation.The proposed project would also convert 815 acres from primarily agricultural uses to mixed urban uses that,because of the considerable BMP requirements of San Joaquin County and MHCSD,would be processed through existing expanded and proposed water quality basins and BMPs before being discharged to Mountain House Creek and Old River,thus resulting in less-than- significant operational impacts on water quality. Both development scenarios would generate less-than-significant construction-related water quality impacts.With respect to operations-related water quality impacts,this alternative would not generate the urban runoff that would be generated under the proposed project,but at the same time it would continue the generation of agricultural runoff that would be discontinued under the proposed project.Therefore,this alternative would generate pollutants in runoff from the project site that would not occur under the proposed project and vice versa; thus, these two scenarios are not comparable with respect to operational water quality impacts.[Not comparable] — Public Health and Safety The No-Project Alternative would include 18 new residential units on 7 acres of the 815-acre project site,but it would otherwise not disturb the project site or off-site infrastructure sites. Like the proposed project,this alternative would result in: a significant potential for exposure to preexisting hazardous materials because this alternative would include soil-disturbing activities that could unearth or disturb hazardous materials, EDAW College Park at Mountain House Specific Plan III Draft EIR Alternatives to the Proposed Project 5-6 San Joaquin County