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. Such activities are directed toward preventing minor problems from becoming major flooding problems, minimizing unnecessary damage to private property through proactive planning, preserving and maximizing flood carrying capacity of existing creeks and channels, and post-storm rehabilitation of damaged flood protection facilities. On occasion, bank repairs such as those defined herein are required to rehabilitate facilities following storm event in order to return the facilities to their expected level of service and safety.
This project involves seven bank repairs in the cities of Pleasanton and Livermore, summarized below.
Site # Waterbody (length of repair) Nearest roadway
1) 873 Tassajara Creek (200 feet) Owens Drive
2) 890 Tassajara Creek (90 feet) Owens Drive
3) 891 Tassajara Creek (86 feet) Owens Drive
4) 892 South San Ramon Creek (79 feet) Amador Valley Blvd. /Iron Horse Trail
5) 893 South San Ramon Creek (40 feet) Amador Valley Blvd. /Iron Horse Trail
6) 894 South San Ramon Creek (145 feet) Amador Valley Blvd.
7) 895 Line G-1-1 (77 feet) Johnson Drive
All repair work will be performed from the top of the bank. No equipment will be operated in the channel. Removal of the bank failure material will require an excavator. The repair areas shall be excavated to undisturbed bank material as determined onsite by the project engineer. The excavation shall continue below the channel bottom into deposited sediments to develop a shear key at the toe of the rebuilt bank. If needed, temporary cofferdams would be installed to divert water around the bank repair sites to avoid work in the wetted channel.
A silt fence will be installed at the toe of the slope to prevent loosened materials from being deposited into the waterway. A water truck will be onsite for dust control and to water the backfill material for compaction. The limits of the work area will be flagged in order to limit the area disturbed. Work will be done in compliance with applicable environmental regulatory permits, including a requirement for a pre-construction biological survey.
Completion of all the bank repairs is expected in 2021 or 2022, depending on contractor availability. All work will be performed in the dry season and all work will be complete by October 31st each season. The work will proceed from one site to another, possibly with two nearby sites being repaired simultaneously
To minimize impacts to nearby residents, construction will generally occur only during normal working hours, or 8 a.m. to 5 p.m., Monday through Friday, or as allowed by city ordinance. All work will be done in accordance with applicable regulatory permit requirements including California Department of Fish and Game.
All equipment and construction would be staged on the access roads adjacent to the channel repairs. Stockpiled rock riprap would be stored at Zone 7’s storage yard near Bernal Ave. in Pleasanton or in a vacant parcel owned by Zone 7 near El Charro Rd. in Livermore.