Littlerock Sediment Removal Phase 2, Years 1-5 (FY2022-2026)

The Palmdale Water District (District) is looking for a qualified construction company to remove and dispose of sediment that has accumulated in the Littlerock Dam Reservoir. Sediment removal activities would involve the excavation of material from inside the reservoir, within the general disturbance area shown in Figure B-2. Sediment removal will not alter the Reservoir footprint, but will simply deepen the Reservoir within the excavation area shown in Figure B-2. The excavation area starts just upstream of the Dam and extends approximately 4,500 feet upstream of the Dam. The maximum excavation depth would be approximately 14 feet approximately 800 feet upstream of the Dam. The new channel bottom would taper upstream to the existing grade at the upstream limits of excavation. This disturbance area is contained entirely within the Reservoir inundation area. Detailed areas selected for sediment removal, areas marked for avoidance, maximum excavation depths and other relevant construction and access details are present in the 100 Percent Master Excavation and Phasing Plan. Currently, the District has received the necessary permits to complete the work and completed the Environmental Impact Report (EIR). The EIR has identified several disposal locations with it. However, the District expects sediment to disposed at one of the local quarries. Bidders shall review and agree to the requirements contained in the EIR and permits. Below is a summary of the permits in Table A-1 and more details are found in the link below. Table A-1 lists the federal. State, and local permits and authorizations required for the proposed project. Environmental Impact Report Documents The project consists of three components. The first phase began with the construction of a subterranean grade control structure within Littlerock Reservoir at Rocky Point, also referred to as the Grade Control Structure, which was completed in 2019. The second phase is the removal of 1,165,000 cubic yards of accumulated sediment from within the Reservoir over a 7 to 12-year timeframe, which is summarized in Table B-2. After completion of the second phase, the District will implement Phase III which is the ongoing annual sediment removal of approximately 38,000 cubic yards to maintain the design capacity of the Reservoir. The overall objective is to restore and preserve the Reservoir capacity, which has been substantially reduced over time by the accumulation of sediment behind Littlerock Reservoir during seasonal inflows. In 1992 the reservoir had a storage capacity of 3,500 acre-feet (af). Currently, the Reservoir storage capacity has been reduced to approximately 3,037 acre-feet due to sediment buildup. The construction period is limited to a specific time of year based on permits which allows work to commence on September 15 and continue until seasonal rainfall fills the reservoir (estimated between mid-November and January). During periods of low rainfall work is allowed until March 1st. It is the District's intent to award a three-year contract with two optional one-year renewals. However, the District reserves the right to terminate the contract for any reason including but not limited to the following - extensive extra cost requests, violation of the permit requirements, failure to meet the schedule, and poor performance of the contract.