Geotechnical Investigations for the California High-Speed Rail Program, Palmdale to Burbank
Summary
SCH Number
2015128380
Public Agency
California High Speed Rail Authority
Document Title
Geotechnical Investigations for the California High-Speed Rail Program, Palmdale to Burbank
Document Type
NOE - Notice of Exemption
Received
Posted
12/23/2015
Document Description
A tunnel through the ANF is being considered for a portion of the Palmdale to Burbank Section alternatives (E1, E2 and E3) for the California High-Speed Rail Project. The purpose of the geophysical investigation is to obtain sufficient subsurface field data to help evaluate the tunnel portion of alternative with respect to potential environmental impacts (i.e., groundwater, hydrogeology and surface water resources), design constraints, and construction constraints. The key hydrogeological and geotechnical conditions that could affect tunnel design include hydraulic pressures at tunnel depth, inflows off groundwater into the tunnel during construction, potential surface and groundwater impacts, rock quality at depth, squeezing ground at fault zones, and rock quality at other locations. The purpose of the proposed geophysical surveys in core holes drilled to the depth of the tunnel is to measure in-situ water pressures, the orientations of rock mass, discontinuities and fracture density, hydraulic conductivity, and direction of water flow with in-situ testing methods described below.
Contact Information
Name
Mark McLoughlin
Agency Name
California High Speed Rail Authority
Contact Types
Lead/Public Agency
Phone
Location
Counties
Los Angeles
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
15304 & 15306 C:4 6
Reasons for Exemption
The Project consists of data collection and resource evaluation activities that would not result in a serious or major disturbance to environmental resources because all data collection and evaluation activities would be generally in existing disturbed areas and would be temporary in duration; as such, no permanent effects would occur. Temporary effects have the potential to occur as a result of the subsurface investigation but would not be significant, both because the impacts are in existing disturbed areas and any new disturbance would be restored once investigations are complete, as described in attachment A. Attachment A contains the Preliminary Geophysical/ Geotechnical Investigation Plan for Proposed Tunnel Alternatives in Angeles National Forest which provides a summary of the activities involved with subsurface investigation and a describes the scope and the nature of any potential effects.
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