Engineer s Report. Santa Clara Valley Water District California Aqueduct Reverse Flow Project Project No

Transcription

1 17 Santa Clara Valley Water District California Aqueduct Reverse Flow Project Project No Engineer s Report February 2015 Water Utility Capital Division

2 This page intentionally left blank.

3

4 This page intentionally left blank.

5 1. PROJECT DESCRIPTION On September 23, 2014, the Santa Clara Valley Water District (SCVWD) adopted the Engineer s Report for the SCVWD California Aqueduct Reverse Flow Project. The Engineer s Report described the installation of temporary reverse flow pumping systems at up to four check structures; one each at Check Structure 22, Check Structure 20, Check Structure 18, and Check Structure 15 along the California Aqueduct, in Kings and Fresno Counties, to facilitate reverse flow of 18,000 acre-feet (AF) of SCVWD s previously banked water from Semitropic Water Storage District (Semitropic). Since adoption of the Engineer s Report, the project has undergone additional modifications which include a proposed increase in water delivery from 18,000 AF to 50,000 AF and the installation of additional infrastructure, including two 48 inch bypass pipelines, a small vacuum pump and a siphon at the Dos Amigos Pumping Plant in Merced County. The proposed modified SCVWD California Aqueduct Reverse Flow Project (Project) is located at check structures 15, 18, 20, 22, and the Dos Amigos Pumping Plant along the California Aqueduct in the central San Joaquin Valley (see Figure 1 for project location). The proposed Project sites (each of the check structures and the Dos Amigos Pumping Plant) are located on properties owned by the California Department of Water Resources (DWR) and/or United States Bureau of Reclamation (Reclamation). The purpose of the proposed Project is to convey water previously banked by the SCVWD to address impacts of the severe drought. The conveyance will occur by utilizing temporary pumps to be installed at the four check structures to essentially reverse the flow of the California Aqueduct (Aqueduct) from north of check structure 25 to O Neill Forebay. SCVWD has previously banked Central Valley Project (CVP) water and State Water Project (SWP) water with Semitropic. This is accomplished via a banking agreement that provides for at least 31,500 AF of banked water to be pumped into the Aqueduct in any year (later referred to as pump-in capacity). In addition, SCVWD may gain access to another 18,500 AF from Semitropic in 2015 or 2016 that would similarly be conveyed, resulting in total flow capacity of 50,000 AF over a four-month period. Under normal operations, previously banked water is pumped into the Aqueduct for SWP use south of Semitropic, and in exchange, SCVWD is delivered an equal amount of SWP water supply through the South Bay Aqueduct or San Felipe Division (hereinafter referred to as normal operations). However, in critically dry years such as 2014 and 2015, limited supplies in the SWP may result in insufficient capacity within the SWP for exchanges under normal operations, in which case SCVWD would not receive sufficient supplies from Semitropic to meet its needs. SCVWD proposes to install a temporary reverse flow pumping system within DWR and/or Reclamation right-of-way to enable delivery of a portion of SCVWD s banking withdrawals. Temporary pumps would be installed at up to four existing check structures (Check Structures 22, 20, 18, and 15) along the Aqueduct 1 and a vacuum pump, siphon and two bypass pipelines would be installed at Dos Amigos Pumping Plant (Merced County). Of the 50,000 AF that would be pumped into the Aqueduct from Semitropic on behalf of SCVWD pursuant to the SCVWD/Semitropic banking agreement, all of it could be conveyed northerly for the purposes of the proposed Project and: (1) made available to Reclamation as CVP supply and/or DWR as SWP supply, and in return, SCVWD would receive a similar amount of exchange water, as described below; and/or (2) made available to Reclamation as CVP 1 Check structure 22 is on State of California right-of-way; check structures 20, 18, and 15 are on federal right-of-way managed by Reclamation. 1

6 supply and/or DWR as SWP supply for direct delivery to O Neill Forebay. All water that is conveyed northerly, and not required to be bypassed at the Dos Amigos Pumping Plant, would be distributed through existing conveyance facilities pursuant to normal operational delivery procedures. CVP exchange CVP water would be pumped through metered discharge piping around the sides of the existing control gates at up to four check structures (22, 20, 18, and/or 15), and/or siphoned from Pool 14 to 13 to bypass the Dos Amigos Pumping Plant to meet scheduled CVP demands out of San Luis Reservoir 2. Reclamation would deliver an equal amount less potential conveyance losses, if any, of CVP supply to SCVWD in San Luis Reservoir or O Neill Forebay, depending upon conditions at the time of exchange (see Figure 2); SWP exchange SWP water would be pumped through metered discharge piping around the sides of the existing control gate at one check structure (22) and delivered to SWP contractors between check structures 25 and 20 to meet scheduled demands. DWR would deliver an equal amount less potential conveyance losses, if any, of SWP supply to SCVWD via the South Bay Aqueduct and/or in San Luis Reservoir or O Neill Forebay, depending upon conditions at the time of exchange (see Figure 2). Direct delivery CVP water and/or SWP water would be pumped through metered discharge piping around the sides of the existing control gates at four check structures (22, 20, 18, and 15), and siphoned from Pool 14 to Pool 13 to bypass the Dos Amigos Pumping Plant, allowing for direct delivery to O Neill Forebay (see Figure 2). In general, the Project would include rental of pumps, high-density polyethylene (HDPE) or steel pipes, diesel-driven power units, pump watch and security, and operation and maintenance. Potential types of pumps to be used include axial flow, submersible pumps or skid-mounted, horizontal pumps of various sizes, with the capability to pump at the various flow rates required to meet SCVWD demands at the time. 2. ZONE BENEFITS The proposed Project work would benefit customers of both Zones W-2 (North County) and W-5 (South County). 3. PROJECT RIGHT-OF-WAY As work on the proposed Project would occur within DWR and Reclamation right-of-way, SCVWD is entering into agreements with both DWR and Reclamation to allow for the installation, operation, maintenance, and de-mobilization of the temporary pump stations and siphon to occur. 2 The District may not need to install and operate the temporary pumps at all four check structures to complete this exchange.

7 4. MAPS AND FIGURES See attached Figures 1 through 4 at the end of this Engineer s Report. Figure 1 shows the location of each of the facilities. Figure 2 shows an overview of facilities and locations associated with the exchange of CVP and SWP water, including SCVWD, San Luis Reservoir, O Neill Forebay, the San Felipe Division, and the South Bay Aqueduct. Figure 3 shows a typical check structure and a conceptual layout of the project features, including intake pipes, nurse tanks, pumps, discharge pipes, fuel tanks, and a portable containment berm. Figure 4 shows a conceptual layout of the siphon at the Dos Amigos Pumping Plant. 5. PROJECT COSTS The estimated costs to plan, design, install, and operate the proposed Project are as follows: External Services Planning and design phase costs $435,100 Installation and operational costs $6,000,000 Subtotal $6,435,100 Internal District labor costs $300,000 Total Project cost (in 2015 dollars) $6,735,100 The proposed Project costs would be funded by the Water Utility Enterprise, with 88.2 percent of the costs allocated to Zone W-2 (North County) and 11.8 percent of the costs allocated to Zone W-5 (South County). The cost allocation is based on each zone s average Municipal and Industrial (M&I) water use versus total M&I water use. 6. PROJECT SCHEDULE Environmental review o CEQA Final IS/MND adopted: October 2014 Addendum to IS/MND completed: February 2015 o NEPA Supplemental environmental assessment completed by Reclamation staff: April 2015 Reserve equipment: April 2015 Mobilize/install project and operate or stand-by: September 2015 through March 2016 De-mobilize: April 2016 (note: with appropriate amendments, the project may be continued in 2016 if the drought continues)

8 7. LIST OF MAPS AND FIGURES Figure 1 Project Location and Vicinity Map Figure 2 Other Associated Facilities Figure 3 Check Structures Conceptual Site Plan Figure 4 Siphon Conceptual Site Plan (Remainder of page intentionally left blank)

9 Figure 1. Project Location and Vicinity Map

10 Figure 2. Other Associated Facilities

11 Figure 3. Check Structures Conceptual Site Plan

12 Figure 4. Siphon Conceptual Site Plan