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KEY TQ IAB

Soil'l‘m
(A) Soils mapped within National Forest boundaries. Source: Forest and Soil Conservation
Service, Soil Survey of Angeles National Forest Area, California (USDA, 1991)
(B) Soils mapped on private land. Source: Soil Conservation Service, Soil Survey of Antelope
Valley Area, California, (USDA, 1969 and 1970)

Description of Hydrologic Soil Groups Mapped within Site Boundaries
Moderately low to moderate runofl' potential. Soils have moderate infiltration rates when
thoroughly wet. They are mostly moderately deep, moderately well drained to excessively
drained, moderately fine to moderately coarse textured and have moderately slow to moderately
rapid permeability.
Moderately high to high runoff potential. Soils have slow infiltration and water transmission
when wet. Mostly belong to one of two general categories. First category are mostly well
drained and moderately well drained soils that have a low permeability layer at moderate depth
(20 to 40 inches). Second category soils generally have moderately fine or fine textures or a
moderately high water table and may be somewhat poorly drained. This group also includes
shallow soils over hard but highly fractured bedrock that allows moderate water transmission.
High to very high runoff potentials. Soils have very slow rates of infiltration and water
transmission when wet. Mostly fine textured soils that have shrink - swell potential, soils that
have a high water table, soils that have a low permeability layer near the surface, or shallow
soils over an impervious layer.

Permeability Rating: Descriptions

ashram I . . u
<0.06 very slow
0.06 - 0.20 slow
0.2 - 0.60 moderately slow
0.6 - 2.0 moderate
2.0 - 6.0 moderately rapid
6.0 - 20.0 rapid

Maximum Erosion Hazard Ratings (EHR)

Qw EHR - Accelerated erosion is unlikely, except during periods of above average precipitation, and
in soils bordering on moderate EHR. Erosion control measures are usually not needed.

Mggeroto EHR - Accelerated erosion is likely to occur. Need for erosion control should be evaluated.
High EHR - Accelerated erosion will occur in most years, especially during periods of above average
storm occurrence. Erosion control is necessary.

Vog High EHR - Accelerated erosion will occur in most years, even during periods of below average
storm occurrence. Erosion control is essential.

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