Why is the Banner Cascade Pipeline Project Needed?
The Lower Cascade Canal and Upper Grass Valley Canal are critical links in NID's water system that conveys untreated, 'raw' water from a high elevation diversion on Deer Creek to irrigation customers and to NID's Loma Rica and Elizabeth George water treatment plants. At these two treatment facilities, the raw water is treated and drinking water then distributed to NID's residential customers. Over the years, the upper reaches of the Cascade canal system have been upgraded and replaced with pipelines.
The Lower Cascade Canal delivers water to the Loma Rica treatment plant, while the Upper Grass Valley Canal diverts part of the Lower Cascade Canal flows to the Elizabeth George treatment facility. The Lower Cascade Canal is a miner's ditch over 100 years' old that, when flowing full, is limited to a flow of about 55 cubic feet of water per second (cfs). This flow does not meet the projected demands for water within NID's service area defined in accordance with the County's General Plan. There are serious concerns about the reliability and stability of the old canal and its banks when it is regularly running at full capacity. As a major canal failure could seriously impact NID's customers, NID has decided to construct a new pipeline as its primary conveyance method. The proposed pipeline is capable of conveying about 95 cfs. The canal will remain in service as a local feeder.
History of the Project
NID recognized when initiating the replacement of the Lower Cascade Canal that there were potential impacts on the environment caused by both decommissioning of the Canal and construction of a more-directly routed pipeline. NID also recognized that the Canal was a historical and recreational resource. As part of preparation of a project Environmental Impact Report (EIR) initiated in 2000 under the California Environmental Quality Act (CEQA), NID consulted widely with individuals and organizations within the local community to determine public concerns about both temporary disruption and potential long term impacts caused by the project. When certifying the project's Final EIR in 2007, and approving the Banner Cascade Pipeline Project, the NID Board made a commitment to minimizing these impacts by adopting a detailed Mitigation and Monitoring and Reporting Program (MMRP) associated with the requirements of CEQA.
NID has also committed to maintaining typical flows of between 2 and 10 cfs in the Lower Cascade Canal once the Banner Cascade Pipeline is put into service, recognizing the need to preserve the Canal as a historical, cultural, scenic and recreational amenity.
In November 2007, NID appointed Hatch Mott MacDonald with RMC Water and Environment, Inc as consultants to prepare the Banner Cascade Pipeline design.
Project Features
The Banner Cascade Pipeline Project has the following proposed features described below and shown on the detailed maps below:
- A 48-inch diameter pipeline will connect to NID's existing Clipper Creek Siphon pipeline on Opalite Way, south of Red Dog Road and Banner Lava Cap Road. The pipeline is to be routed via Wings of Morning Drive, Banner Lava Cap Road, Idaho Maryland Road and Lee Lane to the Loma Rica treatment plant. Due to the fall in elevation along the route, the pipeline will flow full under pressures up to 300 psi.
- At the Loma Rica facility, some of the raw water will be diverted for treatment and storage, with the remainder conveyed to the Elizabeth George treatment plant in a 36-inch diameter pipeline. This pipeline will be routed along the northern boundary of the Nevada County Airport (subject to final FAA approval) before turning north to Madrone Forest Drive. After crossing Idaho Maryland Road, the 36-inch pipeline follows property boundaries to the south end of Red Gate Road. The pipeline reaches the Elizabeth George treatment facility from Red Gate Road and Banner Lava Cap Road.
- 8, 10 and 12-inch treated water pipelines are to be constructed concurrently with the larger raw water pipeline along various sections of the route. NID intends to improve its ability to convey treated water around the project area by connecting with existing water mains, and to be able to offer treated water to local residents who currently have a groundwater well supply. Fire hydrants will be provided to improve fire protection for local residents.
- Flow control structures at the intersection of Onyx Court and Red Dog Road, and on Banner Quaker Hill Road with an overflow pipeline from the Banner Quaker Hill Road facility back to Scott's Flat Reservoir.
- Strengthening of the existing Clipper Creek Siphon pipeline east of Opalite Way, and encasement of part of the Upper Grass Valley Canal where it runs parallel to Banner Lava Cap Road west of Old Wood Road.
- A feasibility study to determine the economic and technical viability of a hydro-electric power plant to be located at the Loma Rica treatment plant.
The design aims to maximize the amount of pipeline within roadway and to minimize the need to disrupt adjacent landscaping and remove trees. For the 48-inch diameter pipeline, the construction trench will typically be 8 feet deep and 6 feet wide. For the 36-inch pipeline, the trench will typically be 7 feet deep and 5 feet wide.
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