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IVw3 Soils that may be used for some crops, but have very severe limitations that restrict the choice of plants and/or require very careful management. Excess water is the dominant limita- tion. There is also a limitation caused by slow permeability or very slow permeability of the subsoil. Commonly referred to as marginal land. The agricultural productivity ratings just presented all assume that only traditional land management practices are employed. Historically, traditional land management practices have been determined largely by economic incentives to make a profit. However, due to changing economic pressures, the agricultural productivity of these soils should be reevaluated in terms of what could be accomplished using advanced land management practices. The major limiting fac- tors for the soils on-site have been identified to be shallow soil depth over hardpan, slow permeability of subsoil, and erosion hazard. Advanced land management practices could overcome these obstacles. According to the Soil Conservation Service, "These soils, if properly managed by ripping, fertiliza- tion, irrigation, and other practices, are capable of significant production levels." (See Appendix B). During the course of their geotechnical investigation, Kleinfelder and Associates drilled 16 test borings on the property. Figure 5 shows the approx- imate location of each. In general subsurface soils encountered were inter- bedded layers of clayey silt and silty clay with interbedded stringers of sand. Various laboratory tests were conducted at selected depths and soil samples were classified according to the Unified Soil Classification System. A brief summary of relevant test results are included in Table 3. Table 3 shows that the undisturbed 40 to 50 -foot deep soil layer beneath the cells would consist mainly of SM, CL, and ML classes of soil. From Appendix C, the following descriptions may be obtained. SM Silty sands sand -silt mixtures, compacted permeability as slow as 10-� cm/sec. ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with slight plasticity, compacted permeability as slow as 10-6 cm/sec. CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays, compacted permeability as slow as 10-8 cm/sec. For more comprehensive descriptions of subsurface materials, the reader should refer to the detailed boring logs included in the preliminary geotechnical report prepared by Kleinfelder and Associates, July 23, 1980. Based on their investigation, Kleinfelder and Associates concluded that soil conditions were "suitable for development of the Class II -2 sanitary landfill site." 15