Draft Environmental Impact Report - California Off Highway Vehicle ...

3.7 Geology and Soils
constructed in compliance with CBC (Title 24), which addresses seismic safety in construction.
Therefore, impacts related to ground shaking and surface rupture would be less than significant.
Mitigation Measures: No mitigation is required.
IMPACT
3.7-3
Soil Erosion or the Loss of Topsoil
At Clay Pit SVRA, erosion can occur from wind and periods of intense rainfall, especially in areas
that have been disturbed. The potential for erosion generally increases as a result of human
activity, primarily through development of structures and impervious surfaces and the removal of
vegetative cover. Some erosion has occurred on‐site in areas where the soil layer has been
disturbed by OHV use. Continued and increased use of OHVs, as envisioned in the General Plan, has
the potential to continue to cause soil erosion. The NRCS provides ratings that indicate the risk of
soil loss from off‐road and off‐trail areas after disturbance activities that expose the soil’s surface.
The soils located on the perimeter of the basin are described as “limited” for crops and other uses
because of ponding, indicating that soils are poorly drained. The soils within the basin are not rated.
Construction and operation of facilities envisioned in the General Plan, including construction and
operation of the headquarters facilities, would result in soil disturbance, the removal of
vegetation, and the creation of impervious surfaces that could increase the potential for erosion.
However, Soils Goal 1 and accompanying guidelines in the Clay Pit SVRA General Plan require the
use of practices which would minimize the potential for erosion and erosion‐related hazards,
including compliance with the 2008 Soil Conservation Standard and Guidelines described in Section
3.7.2, “Regulatory Setting,” above. Soils Guideline 1.3 in the General Plan requires that erosion‐
control measures, including those designed for stock piles, be implemented during the
construction and operation of activities or facilities. Consistency with the OHV BMP Manual (State
Parks 2007) also would be required. Refer to section 3.8 “Hydrology and Water Quality” for
additional discussion of the potential for soil erosion and resulting water quality degradation.
As outlined above, multiple standards and guidelines related to minimizing erosion potential must
be met when implementing actions proposed under the General Plan. With adherence to these
guidelines and requirements, significant erosion impacts would be avoided or minimized, and this
impact would be less than significant.
Mitigation Measures: No mitigation is required.
IMPACT
3.7-4
Risk of Damage to Structures and Infrastructure from Expansive Soils
The presence of moderate to highly expansive clay soils near the surface is the primary
geotechnical constraint at the project site (Geocon 2010; Appendix D of the General Plan). These
Clay Pit State Vehicular Recreation Area
Draft EIR 3.7-7 February 2012