Arroyo Mocho Stanley Reach Sedimentation Basin Maintenance
Summary
SCH Number
2023080625
Public Agency
Zone 7 Water Agency
Document Title
Arroyo Mocho Stanley Reach Sedimentation Basin Maintenance
Document Type
NOE - Notice of Exemption
Received
Posted
8/24/2023
Document Description
Zone 7 Water Agency (Zone 7) owns and maintains approximately 37 miles of engineered, modified, and natural channels throughout the Livermore-Amador Valley. The channels also play an integral role in local groundwater management and water supply. Zone 7’s maintenance program includes routine maintenance of, and repairs to, the flood protection facilities.
As designed, the sedimentation basin on Arroyo Mocho adjacent to Isabel Avenue (Hwy 84) needs periodic maintenance (removal of accumulated materials) to remain effective. It was last maintained in 2021 as part of a larger stabilization project. The multiple atmospheric rivers of January 2023 brought in significant amounts of sediment from upstream, and the sedimentation basin is currently exceedingly full and due for maintenance ahead of the next rainy season.
In summer months, the water in Arroyo Mocho typically consists of releases of imported water from the South Bay Aqueduct for the purposes of artificial recharge of the groundwater basin. For this maintenance work, Zone 7 will pause the releases to Arroyo Mocho during the work window. As a matter of increase precaution, coffer dams will be installed such that any unplanned water in Arroyo Mocho will flow only through the low flow channel that circumvents the construction area.
The site is generally accessible to Stanley Boulevard, a major thoroughfare that leads to the nearby Livermore quarries, and to Isabel Avenue (Hwy. 84). More specifically, the site is accessible on both ends, via Rockrose St. on the west and Murrieta Boulevard on the east. The Rockrose entrance is expected to be most heavily used for this project. Equipment will likely stay onsite overnight, on Zone 7 property and outside of the channel.
Approximately 850 truck trips will be required to off haul all materials to Zone 7 property near Cope Lake (El Charro Rd). It is expected that as much as possible of the material will be re-purposed by Zone 7 within our service area for future upland repairs or maintenance, like spreading on maintenance access roads. Construction is expected to take about 3 weeks.
Contact Information
Name
Elke Rank
Agency Name
Zone 7 Water Agency
Job Title
Water Resources Planner
Contact Types
Lead/Public Agency
Phone
Email
Location
Cities
Livermore
Counties
Alameda
Regions
Citywide
Cross Streets
Stanley @ Isabel
Zip
94551
Total Acres
1
Jobs
1
State Highways
Hwy 84
Railways
UPRR
Airports
Livermore Municipal
Schools
Granada HS
Waterways
Arroyo Mocho
Township
3S
Range
2E
Section
1
Base
MDBM
Other Information
Arroyo Mocho flood channel, adjacent to Stanley Blvd. and Isabel Ave. in Livermore
Notice of Exemption
Exempt Status
Emergency Project
Type, Section or Code
Sec. 21080(b)(4); 15269(b)(c)
Reasons for Exemption
The work is required a result of a declared state and federal emergency (#DR-4683-CA, December 27, 2022 - January 31, 2023). There is not a reasonable possibility that the project could result in a significant impact.
County Clerk
Alameda
Attachments
Notice of Exemption
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