Water Resources, Department of
(California Department of Water Resources)
California Aqueduct Slope Armoring
NOE - Notice of Exemption
Slope armoring will be performed to re-establish some of the design capacity lost due to subsidence and to prevent overtopping and potential failure of the Aqueduct liner. Armoring will be done by installing Geosynthetic Concrete Composite Mat (GCCM). A smooth slope will be created along the entire upper length of the repair sections by removing vegetation and unsuitable material from these areas; the Contractor will dispose of this material at an appropriate location. The slopes above the liner will be graded, and compacted backfill will be placed above the concrete liners. Once the area is prepared, the GCCM will be installed in up to two rows with an overlapped horizontal seam; vertical seams would also occur every 100 feet. The GCCM will be secured using sealant, stainless steel self-tapping screws, and "percussion" anchors. An up to 12-inch wide by 6-inch deep trench will be dug along the uppermost edge of the GCCM to anchor it in place and to reduce migration of surface water between the GCCM and subgrade.
As a contingency plan, sections of liner may be replaced. An excavator will remove the concrete liner panels and portions of Aqueduct embankment. Voids beneath the removed liner will be filled with soil or low strength concrete, compacted backfill, or gravel. New concrete panels will be poured and installed. High mobility grout (HMG) will be utilized to fill the voids between the concrete panels and Aqueduct embankment and below the removed panels and between the adjacent panels.
California Aqueduct mileposts (MP) 130.00 to MP 133.00 left and right sides and MP 160.40 to MP 167.27 left and right sides.
Notice of Exemption
Type, Section or Code
Reasons for Exemption
Work consists of armoring existing Aqueduct slopes to re-establish some of the design capacity lost due to subsidence and to prevent overtopping and potential failure of the Aqueduct liner. This work will serve to help recover some of the original Aqueduct capacity and will not increase the design capacity or expand the use of the facility. Categorical Exemption 15301 (Existing Facilities) applies.