Emergency Bank Repair Project - Thunderbird Wellfield & WAter Treatment Plant

Summary

SCH Number
2018068634
Lead Agency
Paso Robles, City of (City of Paso Robles)
Document Title
Emergency Bank Repair Project - Thunderbird Wellfield & WAter Treatment Plant
Document Type
NOE - Notice of Exemption
Received

Document Description
This emergency project is needed to address erosion that is resulting in rapid loss of river bank adjacent to the City's Thunderbird Wellfield and Surface Water Treatment Plant (WTP) which are essential sources of drinking water for the City of Paso Robles. Rapid erosion of the western bank of the Salinas River adjacent to the well field and WTP has resulted in mass failure of native soil bank and threatens the City's use of multiple wells. Continued erosion also threatens WTP facilities. The emergency project will install rock slope protection (RSP) to address rapid erosion and failure of the western bank of the Salinas River adjacent to the City's Thunderbird Wells and Water Treatment Plant (approx. 540 linear feet of the lower bank fronting the southern portion of the City's Well Field and Water Treatment Plant by Method A placement of multiple rock layers. This portion of bank (roughly 540 linear feet) was severely eroded in March, 2018 and is now subjected to increasing impinging flow due to natural changes in upstream morphology, and exhibited very limited resistance to erosion during the 2018 wet season (a year of below-average precipitation). Shortening the length of continuous RSP to less than 540 linear feet would leave a portion of the severely eroded bank exposed allowing flow to breach around/behind the RSP and would increase the likelihood of failure. To prevent loss of mature vegetation immediately downstream of the RSP, boulders will be interspersed non-continuously on the bank over approx. 125 linear feet.

Contact Information
Susan DeCarli
City of Paso Robles
1000 Spring Street
Paso Robles, CA 93446

805-237-3970

Location

Cities
Paso Robles
Counties
San Luis Obispo

Notice of Exemption

Exempt Status
Emergency Project
Type, Section or Code
S:21080(B)(4),15268(b)(c)
Reasons for Exemption
Protection activities conducted with the project are necessary to prevent and mitigate an emergency, and are necessary to maintain service essential to public health, safety and welfare (potable water service).
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