SON-128 Slope Failure Repair DDO (EA 4X040)
Summary
SCH Number
2025090193
Public Agency
California Department of Transportation, District 4
(DOT)
Document Title
SON-128 Slope Failure Repair DDO (EA 4X040)
Document Type
NOE - Notice of Exemption
Received
Posted
9/5/2025
Document Description
Caltrans proposes repairing a slope failure that was caused by a washout at 2560 Highway 128 in Soma County. The slope failure was caused by overly saturated soil. According to Field Maintenance crews, water was coming out of the side of the embankment due to the presence of a possible spring or drainage failure/leak on the private property above the highway. Field Maintenance crews cleared 10 cubic yards of sediment from the roadway to reopen traffic in both directions. The slope failure is about 30 feet wide and 12 feet high. The project will use Rock Slope Protection (RSP) mixed with native or imported borrow materials to prevent more erosion from occurring along the embankment slope. Class VI, 3/8 ton RSP (Type A Placement) will be placed over RSP fabric and fill rock voids with excavated material. The natural drainage ditch within the failed area and about 10 feet easterly and westerly will be reestablished to conform to the existing ditch for a total length of 50 feet. Traffic control will be required during construction.
Contact Information
Name
Juliane Smith
Agency Name
Caltrans
Job Title
Senior Environmental Scientist (NEPA/CEQA Specialist)
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project
Address
Phone
Email
Location
Cities
Unincorporated Sonoma County
Counties
Sonoma
Regions
Northern California, San Francisco Bay Area
State Highways
SR-128
Other Location Info
The project is located on westbound SR-128 in Sonoma County at 2560 Highway 128, east of Geyserville, in Sonoma County (post mile 7.63).
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
PRC 21084; 14 CCR 15301 Class 1(c)
Reasons for Exemption
Class 1(d) Existing Facilities. The project is not anticipated to result in any environmental impacts. The project contains a number of standardized project measures which are employed on most, if not all, Caltrans projects and were not developed in response to any specific environmental impacts resulting from the project.
County Clerk
Sonoma
Attachments
Notice of Exemption
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