Porteous - Knoxville Road Landslide Repair Grading Permit
Summary
SCH Number
2026080650
Public Agency
Napa County
Document Title
Porteous - Knoxville Road Landslide Repair Grading Permit
Document Type
NOE - Notice of Exemption
Received
Posted
8/19/2026
Document Description
A portion of the hillside along the existing driveway access to 1705/1710 Berryessa Knoxville Road slid in 2025-2026, as a result of winter storms. This resulted in a landslide that is approximately 120 feet wide from north to south and about 240 feet in length from west to east. The slide extends from the upper driveway down to the lower driveway entrance. The proposed repair for the slide includes the removal of the slide debris and construction of an earthfill buttress with subsurface drainage improvements to restore long-term stability to the hillside and driveway and ensure continued access to the existing residences.
The landslide will be repaired by over-excavation of the slide debris, excavating a toe keyway and benches into the underlying competent materials and bedrock, placing subrainage, and reconstructing the slope using the excavated material in a well compacted engineered fill butress and installation of surface and subsurface drainage improvements to restore the area. A Geotechnical Report prepared by KC Engineering determined that the landslide is a result of hillside saturation from winter storms combined with relatively weak clayey soils; the presence of previously existing older dormant landslide was also identified as a contributing factor to the relatively weak and low-strength soil conditions. After completion of work the disturbed area will be hydro seeded with an erosion control seed mix. Best Management Practices and erosion control measures in conformance with Napa County standards will be implemented during project implementation.
Contact Information
Name
Dana Eleanor Morrison
Agency Name
County of Napa
Job Title
Supervising Planner - Conservation
Contact Types
Lead/Public Agency
Phone
Name
Gregson and Lynette Porteous
Agency Name
Property Owner
Job Title
Property Owner
Contact Types
Project Applicant / Parties Undertaking Project
Phone
Email
Location
Coordinates
Cities
St. Helena, unincorporated area
Counties
Napa
Regions
Northern California, Unincorporated
Cross Streets
Berryessa Knoxville Road and Spanish Flat Resort Road
Zip
94558
Total Acres
1.0
Parcel #
019-180-019-000
State Highways
None
Railways
None
Airports
None
Schools
None
Waterways
Capell Creek and Lake Berryessa
Township
08N
Range
03W
Section
20
Base
MDM
Other Location Info
The slide is located on a private property located off of Berryessa Knoxville Road
at 1705/1710 Berryessa Knoxville Road (APN: 019-180-019-000}. The project is located approximately 0.2 miles southwest of the intersection of Berryessa Knoxville Road and Spanish Flat Resort Road. The project site and project area does not span any mapped blue lines streams or ephemerals, and no work is proposed to occur within stream or ephemeral setbacks.
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Section 15301 Class 1-Existing Facilities and Section 15302 Class 2 – Replacement or Reconstruction
Reasons for Exemption
Pursuant to CEQA Section 15300, the proposed project would be considered Categorically Exempt based on at least one Exemption Class. The project site is not recognized as an important wildlife corridor by any regional or state agency or jurisdiction and is not considered critical to the ecological functioning of adjoining open space areas. The project site is not listed on any hazardous waste sites enumerated under Government Code Section 65962.5. As a result, there is no reasonable possibility that the project will have a significant effect on the environment.
The proposed improvements would be considered Categorically Exempt from CEQA pursuant to Section 15301 Class 1-Existing Facilities, which includes the operation and repair of existing public or private structures or facilities involving negligible or no expansion of existing of former use. The proposed improvements would also be considered Categorically Exempt pursuant to Section 15302, Class 2- Replacement or Reconstruction, which consists of replacement or reconstruction of existing structures and facilities where the new structure will be located on the same site as the structure replaced and will have substantially the same purpose and capacity as the structure replaced. A key consideration in the appropriateness of using these Categorical Exemptions is whether the project would be located on the same site have substantially the same purpose and involves negligible or no expansion of an existing use. Implementation of the proposed project would involve no expansion of existing or former use of the road, and would simply restore the use of the existing road and provide erosion control measures on the hillside above. Implementation of the proposed project would not result in significant impacts based on location and would not impact an environmental resource or any designated environmental resource of critical concern. The project area is not located on a hazardous waste site pursuant to Government Code Section 65962.5 or within a state scenic highway. Implementation of the proposed project would not affect scenic resources, historical buildings, rock outcroppings, or result in a significant effect on the environment due to unusual circumstances. Therefore, it has been determined that the proposed project qualifies for a Class 1 and Class 2 Categorical Exemption and has no reasonable possibility of having a significant effect on the environment.
County Clerk
Napa
Attachments
Notice of Exemption
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