Elk River Waste Water Treatment Plant Outfall Repair
Summary
SCH Number
2025120666
Public Agency
City of Eureka
Document Title
Elk River Waste Water Treatment Plant Outfall Repair
Document Type
NOE - Notice of Exemption
Received
Posted
12/16/2025
Document Description
The project involves maintenance and repairs to the outfall pipe at the Elk
River W\/S/TP. The outfall pipe runs west from the W\/VTP and discharges into Humboldt Bay. An underwater inspection identified necessary maintenance and repairs for the continued operation of the outfall. Maintenance and repairs will occur at the diffuser section of the outfall pipe. The diffuser section has 90 3-inch ports spaced every 4 feet with neoprene flap style check valves that function to prevent sediment intrusion into the pipe. The primary focus of the repairs is the replacement of 90 existing check valves. These valves are past their useful life span and no longer function properly. As a result, sand, sediment and shell have entered the diffuser pipe from the bay. Sediment that has entered the diffuser pipe will be removed during the replacement of the port valves. The neoprene flap style valves will be replaced with 3-inch elastomeric Tideflex check valves that will prevent sediment from entering the diffuser pipe during low flows. In addition to the port valve replacement, one nut and restraining bolt on the diffuser pipe will be replaced, and one 6-inch-wide area of spalling will be repaired with underwater concrete epoxy. Project work will be conducted during the Summer-Fall 2026 and scheduled to avoid periods of anadromous fish passage or heavy waterfowl use.
Contact Information
Name
Henry Baker
Agency Name
City of Eureka - Planning
Job Title
Assistant Planner
Contact Types
Lead/Public Agency / Project Applicant
Address
Phone
Email
Location
Cities
Eureka
Counties
Humboldt
Regions
Northern California
Cross Streets
Hilfiker Lane
Zip
95501
Parcel #
018-271-005
State Highways
255 and 101
Railways
Great Redwood Trail Agency
Airports
Murray Field
Schools
Eureka Union School District
Waterways
Humboldt Bay
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Class 1 Section 15301
Reasons for Exemption
The project consists of maintenance and repairs to the existing WWTP outfall structure, with no expansion of the structure's former capacity. Therefore, the project qualifies for a Class I categorical exemption because it involves maintenance and repairs of an existing structure with no expansion of use
Exempt Status
Categorical Exemption
Type, Section or Code
Class 2 Section 15302
Reasons for Exemption
The project includes the replacement of 90 3-inch flap-style diffuser valves with 90 3-
inch elastomeric check valves and the replacement of one nut and restraining bolt on the diffuser pipe. These components have the same capacity and serve the same purpose as the components being replaced, and involve a negligible expansion of capacity. Therefore, the project qualifies for a Class 2 categorical exemption because it replaces existing valves with comparable valves that do not expand the outfall's capacity.
County Clerk
Humboldt
Attachments
Notice of Exemption
Disclaimer: The Governor’s Office of Land Use and Climate Innovation (LCI) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. For more information, please visit LCI’s Accessibility Site.