Lower Cherry Aqueduct Emergency Rehabilitation (44896) Scoping Package

Transcription

1 Lower Cherry Aqueduct Emergency Rehabilitation (44896) Scoping Package Groveland Ranger District Tuolumne County, California Introduction The (STF) is seeking initial scoping comments on the proposed Lower Cherry Aqueduct Emergency Rehabilitation Project ( LCAER Project or the Project ). The LCAER Project is located near the confluence of the Tuolumne River and Cherry Creek on the s Groveland Ranger District in Tuolumne County, T. 1N, R. 19E, Section 31; T. 1N, R. 18E, Sections 35 and 36; T. 1S, R. 18E, Section 2. The Lower Cherry Aqueduct (LCA) is in place under right-of-way authorized by the Department of the Interior under the 1913 Raker Act (38 Stat. 242), the Act of Congress granting land use rights to San Francisco for the Hetch Hetchy project. A map showing the general vicinity of the LCA and the locations of its key features is attached. Background The LCA system is operated by Hetch Hetchy Water and Power (HHWP), a division of the San Francisco Public Utilities Commission (SFPUC). Since its authorization and construction in , the LCA has provided water for hydroelectric power generation at the Early Intake Powerhouse (from ) and has also served as a delivery system for backup water supply from Lake Eleanor and Cherry Reservoir (also known as Cherry Lake and Lloyd Lake) for approximately 2.6 million people in the Bay Area. In its current condition the LCA cannot reliably fulfill its intended water supply purpose. Impacts from the Rim Fire of 2013 and the effects of age must be addressed before the LCA can be used to deliver water supply to the Mountain Tunnel serving the Bay Area. The LCAER project would rehabilitate and provide major improvements to restore system functionality and reliability. The LCA system has been assessed as eligible for listing in the National Register of Historic Places (NRHP) under Criterion A, for its role in the construction and operation of the Hetch Hetchy water and power system in the Sierra Nevada. It is anticipated that the effects of the proposed action on the historical significance of the Lower Cherry Aqueduct system would be adverse. Consultation with the California State Historic Preservation Office has been initiated to address these adverse effects. The 1913 Raker Act (38 Stat. 242) authorized HHWP to build the LCA system on National Forest System (NFS) lands on right-of-way issued by the Department of Interior in consultation with the U.S. Forest Service. Following the Rim Fire, HHWP undertook a survey to determine the extent to which the LCAER project would require the temporary use of Forest Service lands outside of the approved right-of-way. The survey disclosed that the as-built location of the LCA did not correspond to the right-of-way maps originally approved by the Department of the Interior. A right-of-way correction is needed to accurately reflect the as-built locations on the right-of-way maps maintained by the Department of the Interior s Bureau of Land Management. Raker Act right-of-way would be corrected to match as-built locations that have been in place for nearly 100 years. Following approval by the Department of Agriculture (as the land managing agency) the right-of-way correction would be processed by the Department of the Interior, Bureau of Land Management as successor to the General Land Office, as required by Raker Act Section 1. This scoping package provides information related to the proposed action, the scoping process and how to submit comments. As the project progresses, other project information will be available online at:

2 Lower Cherry Aqueduct Emergency Rehabilitation (44896) - Scoping Package The Forest Service values public participation. The Responsible Official is requesting your specific written comments by August 25, 2014 during this initial designated opportunity for public participation. Communications from the public regarding this project, including commenter s names and contact information, will become part of the public record. Page 6 of this letter provides details on submitting comments. Forest Plan Direction The Forest Service completed the Land and Resource Management Plan (Forest Plan) on October 28, The Forest Plan Direction (USDA 2010) presents the current Forest Plan management direction, based on the original Forest Plan as amended.. The Forest Plan Direction includes management direction for forest wide standards and guidelines (p ) as well as management areas direction and land allocations that apply to this project. Management direction is included for Wild and Scenic Rivers (p ); Wildlife (p ); Special Interest Areas (p ); General Forest (p ); Developed Recreation Sites (p ); Developed (Non-Recreation) Sites (p ); Home Range Core Areas (p ); Wildland Urban Intermix (WUI) (p ); General Forest (p. 191); and Riparian Conservation Areas (p ). Purpose and Need Since 2010, drought conditions in California with below normal precipitation and diminished Sierran snowpack s have caused a significant reduction in surface water storage throughout the state. HHWP Tuolumne River watershed reservoirs received 45 percent of normal inflows as of June If drought conditions persist, there may be a need for rationing or other curtailment of water deliveries from the HHWP system. As in the last major drought of , access to the water supply stored at Lake Eleanor and Cherry Reservoir is needed to ensure the reliability of future HHWP water deliveries and provide immediate drought relief for SFPUC s 2.6 million customers. On January 17, 2014 the State of California issued a Declaration of Emergency to address risks to public health and safety and the environment from extreme drought conditions in the State. The Governor found that conditions of extreme peril to the safety of persons and property exist in California due to water shortages and drought conditions with which local authority is unable to cope. The Governor directed the California Department of Water Resources to expedite funding for water supply enhancement projects capable of breaking ground in On February 10th, San Francisco Mayor Ed Lee issued a mayoral executive directive to City departments to reduce water use and develop alternative sources of water supply for both potable and non-potable uses and specifically named Cherry Reservoir as a potential alternative source of supply. The LCA delivers water from Cherry Reservoir into the Hetch Hetchy system. The purpose of the LCAER project is to: Rehabilitate the LCA to provide reliable delivery of water from Lake Eleanor and Cherry Reservoir into the Hetch Hetchy Regional Water System; Extend the water available for delivery to the SFPUC customers during drought, or when there is insufficient storage in Hetch Hetchy Reservoir to meet customer deliveries; Protect water quality from the effects of the Rim Fire while the water is in transit from the Lower Cherry Diversion Dam to Cherry Creek to Early Intake Reservoir; and Restore LCA design capacity of 165 cubic feet per second (cfs). Proposed Action The STF would issue any project-required special use authorizations for use of National Forest Lands as required for the Project. The rehabilitation work would occur along the entire 3.6-mile length of the system, all of which is within Page 2 of 6

3 Lower Cherry Aqueduct Emergency Rehabilitation Project Scoping Package the STF, and would entail the use of and work along National Forest System (NFS) roads, particularly Cherry Lake Road (NFS / 1N07) which is accessed via State Highway 120. The construction work needed for project implementation would begin approximately March 2015 and would require about 26 weeks. The proposal does not include new road construction. The improvements would restore the 165 cubic feet per second (cfs) design capacity of the LCA, such that up to 150,000 acre-feet of water supply stored in Lake Eleanor and Cherry Reservoir can be conveyed reliably into the HHWP tunnel system for gravity transport to the Bay Area. Project Description Existing Lower Cherry Aqueduct System The LCA consists of approximately 9,500 linear feet of tunnels (five segments), 5,500 linear feet of open concrete-lined aqueduct (four segments), 350 feet of elevated pipeline and 4,600 linear feet of buried pipeline. A forebay along the buried pipeline at one time provided the capability to direct the flow to the Early Intake Powerhouse (no longer in existence) or onward to the Early Intake Reservoir. The forebay is a 20-foot diameter reinforced concrete structure that houses a non-operational trash rack. In Early Intake Reservoir, head gates on the Mountain Tunnel can be opened to allow the LCA flows into the tunnel and onward to the Bay Area. The attached map shows the location of the LCA system and its components. The LCA system was operated to deliver water to the Bay Area during the last major drought in1988. Since that time the system has been maintained and tested periodically to maintain readiness for water supply delivery. Some elements of the system, such as the dam and the concrete lining of the canal, require rehabilitation. Other elements, including the elevated section of the pipeline, were damaged in the 2013 Rim Fire. In addition, over time and increasingly since the Rim Fire, tree limbs and other vegetation, rocks, and soil have accumulated in both the open aqueduct sections of the system and also in the tunnels. HHWP plans to relocate bat species that are presently using the tunnels, remove accumulated debris, and conduct required maintenance and minor repairs to the system during summer 2014 so that the system can temporarily be restored for use in the fall of 2014, if needed. Key components of the LCAER Project The LCA Project would restore HHWP s operational flexibility and short- and long-term responsiveness by rehabilitating the LCA and facilitating access to water supplies in Lake Eleanor and Cherry Reservoir. The key components of the LCAER Project follow: Lower Cherry Aqueduct: Install a new large-diameter pipe in the existing open aqueduct. Placement of the pipe in the aqueduct would require partial or complete removal of the existing concrete liner. Native backfill would be placed over the top of the pipe and hydroseeded with a seed mix approved by the Forest Service. Construct new reinforced concrete structures at each of the tunnel portals to transition between the tunnels and the new pipeline. Improve stormwater drainage along the pipeline. Construct a new reinforced concrete cover over the open aqueduct section between Tunnels 2 and 2A. Replace the entire reach of existing above-ground piping and associated supports between Tunnels 4 and 5 with a new large diameter steel pipeline. Cherry Creek Diversion Dam (CCDD): Repair concrete surfaces of the existing concrete dam, sluiceway and tunnel inlet structure. Replace sluice gates and controls with equivalent equipment. Replace head gates and mechanical operating equipment with equipment Page 3 of 6

4 Lower Cherry Aqueduct Emergency Rehabilitation (44896) - Scoping Package equivalent in function (would not replicate the historic equipment). Reconstruct the wood-framed Gate House and Control Room with new wood framed structures in approximately the same footprint. CCDD Access Trail: Restore the trail to pre-fire conditions for pedestrian maintenance use, with minor safety improvements (no off-road vehicles). Install new rock retaining walls along the access trail. Construct minor new stream crossing. Install bat gates (metal doors with narrow windows) on the tunnel adits along the trail to replace habitat lost from sealing when tunnels were cleaned and put into service. Forebay: Demolish existing trash rack and repair or replace a 12 inch drain valve. Construct new cap structure to cover the top of the forebay. Construct new access structures to facilitate entering the forebay for inspection and maintenance. Materials and Equipment Staging and Other Off-Site Activity Fourteen areas, totaling 3.2 acres, have been identified for potential use for materials and equipment staging. The proposed staging areas are on the figure in Attachment A. All are currently existing graveled or paved areas, primarily on road shoulders. Soil for burial of the pipeline installed in the aqueduct would be extracted either from existing borrow pits within or imported from other local sources that meet USFS weed-free soil requirement and specifications. The proposed borrow location(s) will be identified in the draft EA. Project design features and resource protection measures included in the LCAER project The proposed action includes detailed design features, actions and requirements to reduce potential impacts to the environment. Specific design features will be identified in the Environmental Assessment. Operation of the LCA System HHWP system operations and the amount of water delivered to customers vary throughout the year based on the seasonal SFPUC customer demand and the availability of water. The availability of water for delivery to customers is affected by numerous factors, including meteorological and hydrologic conditions, the capacity and operating condition of physical facilities and infrastructure, and regulatory/ institutional parameters that regulate and allocate the distribution of water from the various sources. Normal System Operations Water in the Hetch Hetchy system (which includes Hetch Hetchy Reservoir, Lake Lloyd [Cherry Reservoir] and Lake Eleanor) comes from a combination of rainfall and inflow from the melting snow pack in the Tuolumne River watershed. The majority (approximately 80 percent) of the inflow to the reservoirs occurs during the snowmelt period, from April through July. The SFPUC integrates the operation of its three major Tuolumne River reservoirs, Hetch Hetchy Reservoir, Cherry Reservoir, and Lake Eleanor with the operation of the Water Bank Account in Don Pedro Reservoir (Water Bank Account) and the SFPUC local reservoirs in the Bay Area. Operations of Lake Eleanor would continue to meet stipulations agreed upon in 1982 between the Department of Interior and the City of County of San Francisco. The stipulations identify minimum in-stream releases and reservoir storage levels that must maintain Lake Eleanor at the original lake full, which essentially is full drawn down of Lake Eleanor. There are no constraints Page 4 of 6

5 Lower Cherry Aqueduct Emergency Rehabilitation Project Scoping Package after September 30 th in any given year. Operations during Drought Periods The Cherry Reservoir and Lake Eleanor system also serves as a standby water supply for the SFPUC for drought periods. In an extremely dry year or after several dry years that compromise the SFPUC carryover storage, it may be necessary to use water from Cherry Reservoir or Lake Eleanor to meet SFPUC customer deliveries. During these events, water is released from Cherry Reservoir or Lake Eleanor and diverted from Cherry Creek through the LCA to Early Intake where the water is diverted into the Mountain Tunnel for transport to the SFPUC customers. Historically, the SFPUC used this supply to meet the SFPUC customer deliveries during drought periods in and The Cherry Reservoir /Lake Eleanor water supply requires filtration. This water is filtered at Sunol Valley Water Treatment Plant (SVWTP). The maximum rate of Cherry Reservoir /Lake Eleanor water to be filtered is about 80 million gallons per day (mgd). The SFPUC anticipates using the Cherry Reservoir /Lake Eleanor water supply for about three months annually, during drought periods, as necessary to optimize all Tuolumne River supplies to meet SFPUC customer deliveries. Operational Maintenance The SFPUC historically has conducted periodic maintenance activities to ready the LCA for possible annual operation. Annually, during the spring runoff when flows in Cherry Creek are above the minimum in-stream release, water is briefly diverted into the LCA, delivered to Early Intake Reservoir and released to the Tuolumne River. Maintenance typically requires one to two days. Following project completion, the SFPUC would continue regular maintenance activity/ system testing from one to three times per year. LCA debris removal, maintenance and temporary repairs are being conducted during the summer of 2014 to enable short term use of the system, if necessary, during fall Bats in the tunnels will be relocated under a California Department of Fish and Wildlife Incidental Take Permit. The Groveland Community Services District, which extracts potable water from the Mountain Tunnel before it reaches SFPUC s Sunol Valley Water Treatment Plant, plans to add filtration equipment to its system to accommodate the potential use of water from the LCA. Scoping Process Public participation is important throughout the analysis. The Forest Service seeks information, comments and assistance from the federal, state, and local agencies and individuals or organizations that may be interested in or affected by the proposed action. We would like your comments on the proposed action, specifically those that would help in the decision-making process. Your comment will be used to help (1) determine the scope of the issues to be addressed; and (2) identify the need for alternatives to the proposed action. Timeline The Responsible Official is requesting your specific written scoping comments by August 25, Scoping comments will be accepted at any time. However, the STN may not be able to give full consideration to scoping comments received after the end of this designated opportunity for public participation. The Forest Service intends to prepare an environmental assessment (EA) for this proposal. The EA is expected to be available for a 30-day opportunity to comment in fall A final decision is expected in winter How to Comment This project is subject to comment pursuant to 36 CFR 218, Subparts A and B (rule). The Responsible Official is requesting your specific written comments during this initial designated opportunity for public Page 5 of 6

6 Lower Cherry Aqueduct Emergency Rehabilitation (44896) - Scoping Package participation (through August 25, 2104). Names of commenters will be part of the public record. Specific written comments are those submitted to the responsible official or designee during a designated opportunity for public participation (36 CFR 218.5(a)) provided for a proposed project. Written comments may include submission of transcriptions or other notes from oral statements or presentation. For the purposes of this rule, specific written comments should be within the scope of the proposed action, have a direct relationship to the proposed action, and must include supporting reasons for the responsible official to consider. Individuals or representatives of an entity submitting comments must sign the comments or verify identity upon request. Comments may be mailed, faxed, or delivered during business hours (M-F 8:00am to 4:30pm) to the :, Groveland District Attn: LCAER Highway 120 Groveland, CA FAX (209) Submit electronic comments, in common formats (.doc,.pdf,.rtf,.txt), to: comments-pacificsouthwest-stanislaus-groveland@fs.fed.us Subject: LCAER Information Contact For additional information regarding this project, contact Michael Jow at the ; Highway 120, Groveland, CA or, call (209) Page 6 of 6