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153 Egbert silty clay loam,partially drained, 0 to 2%slopes—This very deep,poorly drained,nearly level soil is
<br /> on flood plains. Permeability is slow in the Egbert soil. Available water capacity is very high. The shink-swell
<br /> capacity is high. Most areas are used for irrigated crops, and a few areas are used for homesite development.
<br /> 160 Galt Clay, 0 to 2%slopes—This moderately well drained,nearly level soil is on basin rims and in basins, and
<br /> is formed in alluvium derived from mixed rock sources. The surface layer is grayish brown and dark grayish
<br /> brown clay about 25 inches thick, and the upper 9 inches of the subsoil is dark grayish brown clay. The lower part
<br /> to a depth of 60 inches is a variegated light yellowish brown, dark grayish brown, and white,weakly cemented
<br /> hardpan. Permeability is slow, and the shrink-swell potential is high. Depth to the water table is more than six
<br /> feet,but water may be very briefly perched above the hardpan. Runoff is slow, and the hazard of water erosion is
<br /> slight. Most areas are used for irrigated crops, and a few areas are used as irrigated pasture or for homesite
<br /> development.
<br /> 169 Guard clay loam, drained, 0 to 2%slopes—This very deep,poorly drained,nearly level soil is formed in
<br /> alluvium derived from mixed rock sources. Permeability is slow in the Guard soil and available water capacity is
<br /> high. Most areas are used for irrigated crops.
<br /> 254 Timor Loamy Sand, 0 to 2%slopes—This soil type is found on low fan terraces, and formed from alluvium
<br /> derived from granitic rock. Timor loamy sand grades downward from a grayish brown loamy sand to a light gray,
<br /> strongly cemented to indurated hardpan at depths ranging from 30 to 60 inches below the surface. Water may be
<br /> perched above the hardpan following winter storm events, and during years of heavy rainfall,the soil is subject to
<br /> periodic flooding. The soil is moderately well drained,runoff is slow, and there is only a slight hazard of water
<br /> erosion. However,the wind erosion hazard is severe. This soil type has a low shrink-swell potential. The
<br /> extremely rapid permeability rate makes this soil unsuitable for septic systems. The primary use of this soil type
<br /> in San Joaquin County is irrigated crops or irrigated pasture.
<br /> 255 Tinnin Loamy Coarse Sand, 0 to 2%slopes—Tinnin loamy coarse sand is a deep,well drained soil found on
<br /> alluvial fans, and is derived from granitic rock sources. The soil grades downward from a grayish brown loamy
<br /> coarse sand to a pale brown mottled loamy coarse sand at depths of 75 inches. Runoff is slow and there is only a
<br /> slight hazard of water erosion. However,the wind erosion hazard is severe. This soil type has a low shrink-swell
<br /> potential. The extremely rapid permeability rate makes this soil unsuitable for septic systems. The primary use of
<br /> this soil type in San Joaquin County is irrigated crops, orchards,or vineyards.
<br /> 260 Urban Land—Urban land consists of closely built-up areas in cities where streets,parking lots,buildings, and
<br /> other structures cover more than 85 percent of the surface.
<br /> 266 Veritas Fine Sandy Loam, 0 to 2%slopes—This moderately well-drained soil is found on low fan terraces,and
<br /> formed from alluvium derived from mixed rock sources. The soil grades downward from a brown fine sandy loam to
<br /> a grey,cemented hardpan at a depth of approximately 70 inches below the surface.A hardpan is present at depths of
<br /> 40 to 60 inches below the surface. Water may be perched above the hardpan following winter storm events,and
<br /> during years of heavy rainfall,the soil is subject to periodic flooding. Runoff is slow and there is only a slight hazard
<br /> of water erosion.Wind erosion poses a moderate hazard. This soil type has a low shrink-well potential. The primary
<br /> use of Veritas fine sandy loam in San Joaquin County is irrigated crops,orchards,or vineyards.
<br /> SHRINK-SWELL POTENTIAL
<br /> Shrink-swell potential is the potential for volume change in a soil with a loss or gain in moisture; soils swell when
<br /> wet and shrink when dry. If the shrink-swell potential is rated moderate to high,volume changes can result in
<br /> damage over time to building foundations,underground utilities, and other subsurface facilities if they are not
<br /> designed and constructed appropriately to resist the changing soil conditions. Soils with high clay content tend to
<br /> be most affected by shrink and swell. The potential for soil to undergo shrink and swell is greatly enhanced by the
<br /> presence of a fluctuating, shallow groundwater table. Volume changes of expansive soils can result in the
<br /> Manteca WQCF and Collection System Master Plans EIR EDAW
<br /> City of Manteca 4-7.11 Geology,Soils,and Seismicity
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