Knights Landing Outfall Gates Rehabilitation Project

Knights Landing Outfall Gates Rehabilitation Project

The California Department of Fish and Game is executing Lake or Streambed Alteration Agreement number 1600-2011-0109-R2, pursuant to Section 1602 of the Fish and Game Code to the project applicant, California Department of Water Resources The project will replace all gate flaps, seals, and assemblies on the 20 flow control devices at knights Landing Outfall Gates. Each gate is flanked by concrete wing walls, which when blocked with stop-logs on either side of the structure, can be dewatered if water levels are below to top of the stop log. Cofferdams will be utilized during construction to dewater the Colusa drain side of the structure to facilitate repair of the stop log supports, and on the Sacramento River side if the water level is too high to use stop logs. The gate assemblies on both sides of the structure will be removed and replaced while allowing at least half of the gates to remain operational during construction. The 42" gate at bay number 1 on the Sacramento River side of the structure does not have a wing wall on both sides and cannot be dewatered utilizing a stop-log, so will need to have a cofferdam constructed. If cofferdams are used for all of the dewatering then 2280 square feet will be dewatered utilizing approximately 254 linear feet of material. The material used will be clean and free of any potential contaminants. Loose material, such as soil and sand, shall be fully contained so it cannot enter the water. The cofferdams will be in place as long as there is work in the channel. The project will repair a crack in the concrete where the abutment and outfall structure meet at bay number 1 on the Sacramento River side of the structure. The crack repair will be contained within the cofferdam at bay number 1. A new metal stop-log will be fabricated to replace an outdated wooden one. This new stop-log will be taller to allow for dewatering at a higher stage. The overhead track that supports the winch that places and removes the stop-logs will also be replaced. A working pad for equipment will be constructed on the south bank of the Colusa Drain side of the channel. An excavator is used to remove debris from the channel. Sheet-piles will be installed to support the weight of the equipment and stabilize the sloughing bank. The existing lumber trash barrier will be renovated with new logs and stronger connections.

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