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characteristics are color, texture, structure, consistency, reaction, and mineralogic/chemical
composition. Soil series can have differing surface layer textures, resulting in designation
of soil types, which essentially make up the detailed soils mapping units used in the
1970 USDA survey. The survey also recognized a few soils mapping units that were actually

soil complexes (intermingled soil types) and undifferentiated soil groups (two or more soils
with differences not significantly distinguishable for mapping purposes). Six soil types listed
below are recognized on the project property outside the Angeles National Forest (USDA,

1970):

Gaviota rocky sandy loam
Millsholm rocky loam
Saugus loam
Castaic and Saugus soils
Ojai loam
Yolo loam

These soils mapping units are discussed below, and selected engineering properties are
summarized in Table 2. In addition, expansive soil information for these units is provided
in Table 3.

Gaviota Series: Much of the western portion of the project property consists of soil in the

Gaviota series. These soils are found on slopes of 30 to 50 percent and consist of sandy
loam. These soils range in depth from approximately 12 to 18 inches, with up to 10 inches
of surface material and 4 inches of subsoil underlain by a substratum of hard, coarse-grained
sandstone. Outcrops cover approximately 2 to 10 percent of the area. These soils are
generally excessively to well drained. Permeability is moderately slow to rapid. Surface
runofi is rapid, and sheet and rill erosion are moderate. The erosion hazard of these soils

is high. Limitations for road development occur due to steep slopes and hard sandstone at
a depth of 14 to 20 inches. These soils are rated as generally good for engineering purposes,
such as road base and fill material, by the AASl-IO engineering classification system, and
they have moderate allowable soil pressure ratings (USDA, 1969 and 1970). Gaviota series
soil have a low shrink-swell potential (Table 3).

Millsholm series: Soils of this series are also common in the western portion of the project
property. These soils are found on slopes of 30 to 50 percent and consist of loam. These
soils range from approximately 12 to 18 inches in depth. In a typical profile, the surface

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