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2.1.1 Construction of a new Pumping Plant/Fish Screen facility on the west side of the Sacramento River, at a site about 1-mile south of Boyers Bend Pumping Plant including Power Lines 2.1.1.1 Project Description The new Pumping Plant/Fish Facility would be constructed on 4.4 acres of land on the levee on the outside of a river bend about 1 mile downstream from Boyers Bend Pumping Plant (Figures 2 and 3). Above ground facilities will be located to the east of the existing levee road. The fish screen facility will be of reinforced concrete, with all construction occurring behind cofferdams to allow construction in dry conditions. 
Figure 3. Aerial photograph of the site of the proposed pumping plant/fish screen facility (Source: USGS 22 August 1998, 1 km N of Howells Landing). The fish screen itself is almost identical to the Wilkins Slough Positive Barrier Fish Screen, with five 15-foot-wide screen bays rated nominally at 60 cfs, contained in full-height stainless steel guides. A 24-foot wide deck will be provided to allow access for a boom truck or crane for the replacement of any damaged screens. Screen deck elevation is 51.6 feet (15.6 meters), equivalent to the 100-year flood water elevation. A jetting system is included in the design to remove accumulated sediment to ensure screen function. The screen was designed to meet CDFG and NOAA Fisheries criteria for salmonids and Sacramento splittail:
To obtain the benefits of replacing existing unscreened diversions with a single diversion screened to meet current standards, CDFG and NOAA Fisheries have previously issued construction period waivers to allow for construction outside of the July 1-October 1 period. For scheduling and impact assessment purposes, construction at any time during the non-flood season has therefore been assumed (April through end of October). Detailed analysis of fish screen performance criteria, based on an analysis of river hydraulics, is provided in Section 3 (Fish Screen Design) and Section 4 (Structural Design) of Appendix C. The fish screen is designed to operate at water surface elevations of 23.3 to 51.6 feet (7.1 meters to 15.6 meters, respectively), with the screen structure sill elevation at 11.65 feet (3.5 meters). The screen will be fitted with a screen cleaner to remove normal loads caused by flowing water and impact loads caused by floating debris. A floating boom system will be installed to protect the facility from damage by large floating debris under high flow and high wind conditions. The screen is therefore expected to perform under conditions exceeding those likely to be encountered during normal operations, because design criteria accommodate storm and high flood conditions unlikely to occur during periods when the screen is actually operational. Under storm, flood, and flow conditions in excess of the 100-year flood, screens that were damaged would be repaired or replaced prior to initiation of the subsequent irrigation season. The approximately 300-foot-long construction site (91 meters) will include permanent access roads (from the levee road) on the south and north, the pumping plant/fish screen facility fitted with a debris barrier (log boom), and five buried discharge pipes through the levee, discharging into an afterbay at the base of the west-facing slope of the levee. There will be a control building on the top of the levee, accessible from the levee road. The design capacity of the facility will be 300 cfs, or 77 cfs less than the design capacity of the three pumping plants to be decommissioned and removed. Although the combined diversion would be 77 cfs less, the total acre-feet of water diverted per year is anticipated to remain the same, based on RD108's demand survey. Demand and the timing of demand vary depending on year type and seasonal conditions such as temperature, but will not exceed RD 108's rights under the Settlement Agreement. The pumping facility will be fitted with flap gates to reduce backflow to the river when a pump is shut down. There is a uniformly deep pool at this point in the river, and the proposed facility has been designed to take advantage of this. The screen will be aligned along the outside edge of this pool, along a uniform 12-foot contour (3.6 meter contour). At this site, maximum scour during high flows is estimated at 10 feet (3 meters). Access roads would be constructed on both the north and south sides of the existing intake forebay and would include a crushed gravel road surface to allow equipment access to the fish screen structure during construction and for routine operations and maintenance. Following site clearing and construction of access roads to the site, the construction area will be isolated from the river with a sheet pile cofferdam, with piles driven into the channel bottom along the 300-foot (91 meter) alignment. Once the site is isolated from the river, it will be drained and facilities can be constructed in the dry. Cofferdams may be overtopped during high winter flows, requiring re-draining prior to renewal of construction activities. Portions of the cofferdam below the channel invert will remain in place following construction to help protect the foundation of the fish screen facility from scour. Following construction of the Combined Pumping Plant and Fish Screen, areas within the 300-foot (91 meter) construction site will be recontoured and may be protected with new riprap similar to that removed during construction along the levee. The fish screen foundation will not be riprapped, but will be formed by the vertical walls of the pilings initially installed for the cofferdams, but cut at the top of the concrete foundation. This portion of the Combined Pumping Plant and Fish Screen will not require riprap. Outside of the cofferdam area, it is anticipated that up to 25 feet of existing rip rap will be removed for construction purposes on either end of the cofferdam area. Thus, following construction, RD 108 will replace riprap along the area affected. Existing riprap, which is about 2 to 4 feet in diameter, has been sized to protect the levees from anticipated flows and will be replaced with similar-sized rock. In addition, a new power connection will be required for the Pumping Plant/Fish Screen (12 kV), with an above-ground service extending about 1000 feet (300 meters) from Highway 45 to the facility. In addition, short re-connections to existing power will be installed at Boyers Bend and Tyndall Mound. During construction, RD108 would continue to operate the unscreened diversions at Boyers Bend, Howells Landing, and Tyndall Mound. Water deliveries to the service area during Proposed Project construction are anticipated to be similar in magnitude and seasonal timing as historic diversion operations in recent years. Design criteria and parameters for the fish screen are summarized in Table 2-2. Table 2-2. Design parameters for RD108 combined pumping plant and fish screen (From CH2M HILL 2004).
2.1.1.2 Construction Process and Mechanisms for Effect The Combined Pumping Plant and Fish Screen will initially involve placement of sheet pile to isolate the levee construction site from the river and allow construction under dry conditions. The preferred time period for cofferdam construction is late summer to early fall (Table 3-1), when water levels are low, but cofferdam construction has been assumed to occur any time during April through October. Over an approximately 60-day period, piles will be driven into the river bottom using conventional pile driving equipment mounted on a barge. Pile driving with a vibrating driver will disturb the river bottom, with localized plumes of sediment created as the piles are driven. It will remove approximately 0.05 to 0.10 acres (0.2 to 0.4 hectares) of aquatic habitat along the riverbank (piles will form the outer limit of the foundation of the fish screen). Pile driving will create above and below surface noise. Following construction of the cofferdams, the site would be dewatered. Effects on fish and wildlife during cofferdam construction would be related to turbidity/sediment, noise, and trapping of fish behind the cofferdam. With cofferdams installed, the construction of the Combined Pumping Plant and Fish Screen would be isolated from the river except during floods, when the cofferdams could overflow, which would then require dewatering with pumps before construction resumed. If cofferdams are overtopped during construction, fish rescue operations would be conducted during the period when the area behind the cofferdams was being pumped. Construction would involve excavations for roads, for the foundation of the screening facility, for pipelines through the levee, and for the afterbay on the west side of the levee. Construction of the Combined Pumping Plant and Fish Screen will involve removal of virtually all vegetation on the river side of the levee (which is consists of a flat shrub-vegetated bench and a sloped earthen berm with non-native grasses. Following construction, the levee slope will be re-contoured. It may be assumed that the entire construction area of the levee and the afterbay would be disturbed by heavy equipment. This will involve grading to remove vegetation at the site (see Baseline Conditions, Section 5.2.2). Construction of power lines would be confined to agricultural fields to the west of the levee. Construction would create noise, dust, and visual disturbance. The mechanisms by which these activities could affect fish and wildlife would be related to noise, dust, temporary and permanent alterations to the land, and trapping of fish behind the cofferdam (if it is overtopped). 2.1.2 Construction of a new canal system, including 21,250 linear feet (6,500 meters) of new canal to connect the existing irrigation system to the new Combined Pumping Plant/Fish Screen, replacement of 4,210 linear feet (1,280 meters) of existing canal; construction of two low-head lift stations, and construction of canal hydraulic control structures. 2.1.2.1 Project Description The new pumping plant/fish screen will replace the existing unscreened pumping plants at Boyers Landing, Howells Landing, and Tyndall Mound. It will be necessary to construct a new canal system, to link the new facility to the irrigation canals that have historically been served by these three existing facilities (Figures 4-7). An afterbay at the base of the west side of the levee (270 feet long, 95 feet wide, and 14 feet deep; 82 x 29 x 4 meters, respectively) will receive discharge from the pumps, reduce flow velocities, and regulate water surface elevations for gravity feed into the irrigation canal system. As flow velocities are reduced, sediments in the diverted water will settle along the west side of the afterbay, where they may be excavated and then hauled away. RD108 currently provides for disposal of sediment at its Wilkins Slough plant by allowing sediment to be collected by commercial operators for use as fill in various construction projects. RD108 does not anticipate that sediment will need to be hauled to local or regional landfills for disposal at any time. The new canal sections will be constructed along the alignments shown on Figure 4. Typical site conditions are shown on Figures 5 and 6. A siphon under Highway 45 (Figure 7) will also be required. Canals will be concrete lined (a) to reduce seepage and therefore reduce net diversions from the Sacramento River necessary to meet demands and (b) to reduce seepage in the vicinity of flood control levees and therefore ensure that seepage from canals does not create a risk of levee failure. Construction of canals will not affect growers' irrigation canals except at the headworks, which are within the construction right-of-way. 
Figure 4. Location of proposed new canal for the RD108 Combined Pumping Plant and Fish Screen Project. 
Figure 5. Photograph showing typical conditions along the new canal alignment at the base of the Sacramento River Levee, South Canal, RD108 Combined Pumping Plant and Fish Screen Project.
base of the Sacramento River Levee, North Canal, RD108 Combined Pumping Plant and Fish Screen Project.
and Fish Screen Project. New canal segments will be constructed on lands currently used for agriculture. Where the new canal segments parallel the Sacramento River levee, they will be constructed a minimum of 10-feet (3 meters) from the levee base, and the existing unpaved levee maintenance road will be sloped to provide for positive drainage away from the levee. Canals will be 6 feet (1.8 meters) wide at the bottom and from 21.5 to 28.5 feet (6.5 to 8.6 meters) wide at berm crest, with variable depth depending on location. Water levels will not exceed 10 feet (3 meters) above the toe of the levee. They will be fully lined with concrete and designed for maximum flow velocity of 2.5 feet per second (0.76 m/sec). In addition to the new canal sections, about 4,210 linear feet (1,280 meters) of existing concrete-lined canal will be replaced and canal elevations will be raised by from 6 to 18 inches (0.15 to 0.45 meters). The lining of the existing canal sections would be removed, broken up and used in the foundation for the modified canals. Canal segments to replace the existing canals would be constructed along the existing alignment in accordance with the description above. The right-of-way for canal construction will be approximately 90 to 110 feet (27 to 33 meters), with a permanent right-of-way for these new facilities of 40 to 60 feet for canal and required maintenance roads. The new canal system (and marginally expanded rights of way for some elements of the existing canal system), will require a total of 28 acres (11.3 hectares) of permanent right-of-way and up to 25 additional acres (10.1 hectares) of temporary construction right-of-way. Within the permanent right-of-way, the new canal will include construction of check structures, turnouts to existing irrigation canals, the Highway 45 siphon, and operations and maintenance roads and bridges. There will also be minor structural modifications to existing facilities where they are joined by the new canals. The new and expanded canal sections for the Proposed Project will deliver water to existing facilities, but water will need to be lifted several feet into the existing irrigation system for subsequent distribution. Two lift stations will be constructed: at Boyers Bend and Tyndall Mound (Figure 8). These facilities will be constructed within the existing facility site or canal right-of-way. 2.1.2.2 Construction Process and Mechanisms for Effect New canal sections will be constructed on actively farmed agricultural lands and along the rights-of-way of local roads bordering agricultural lands. Construction will involve grading of access roads (where none exist), excavation, contouring of lands and levees, and the placement of concrete linings. There will be year round (but intermittent) construction traffic and activity along the 8 canal segments. Canals are outside of the riverine zone (on the west side of levees), so their construction will not affect fish. Mechanisms for effects to wildlife species include noise (blocked by levees and thus confined to the west side of the project area), dust, construction traffic, temporary loss of about 25 acres of agricultural lands, and permanent loss of about 28 acres of agricultural lands. 
Figure 8. Location of lift stations for the RD108 Combined Pumping Plant and Fish Screen Project. 2.1.3 Excavation of borrow materials at two sites 2.1.3.1 Project Description About 134,000 cubic yards (102,000 cubic meters) of fill material will be required for construction of the Combined Pumping Plant and Fish Screen structure and the canal system. This material will be obtained from two sites shown in Figure 9. Approximately 5,000 cubic yards (3,800 cubic meters) of material will be removed from a 6-acre (2.4 hectare) farm field located northwesterly of the intersection of the North Canal Tie-in and State Highway 45 (Figure 10). This field, which is used for a variety of field crops, is in close proximity to the existing Boyer Canal that will require fill material in order to raise the lining. The farmed field is in need of leveling and this will be accomplished by removing an average of 9 inches (0.23 meters) of material from the field. Most of the borrow material (129,000 cubic yards; 98,000 cubic meters) will be obtained from a borrow site located along (adjacent to) the north side of the District’s Main Drain approximately 4 miles southerly of the Tyndall Mound Pumping Plant (Figure 11). Material at this site is an accumulation of sediment removed from the Drain over many years by routine dredging operations. The site is intermittently dry-farmed in oats or wheat and/or annually maintained by discing and herbicide application to reduce weed development and potential for invasives to affect crops. The material along this section of the Drain is presently stockpiled to a height of about 8 to 10 feet (2.5 meters) and about 100 feet (30 meters) wide at its base on the south and east sides of a 160-acre farm field. As dredged material has been removed from the Drain, the stockpile has encroached on the farmed area. Excavation at this site will be accomplished by scraping stockpiled soil from along the field side down to the original field level thereby allowing the ground to be returned to active farming. Excavation will extend only to within 15-18 feet (4.5 to 5.5 meters) of the Main Drain, leaving the existing berm intact. There is adequate material from these two sites to supply the fill requirements of the Proposed Project. Removal of the material will level the fields at these sites and will not affect adjacent land uses or structures. It is anticipated that growers at the two sites will continue to plant a range of typical field crops (the 6-acre site is currently in wheat; the borrow site near the Main Drain was not plowed for planting at the time of EA/Initial Study preparation). 
Figure 9. Location of borrow sites for the RD108 Combined Pumping Plant and Fish Screen Project. 
Figure 10. Photograph showing borrow site 1, Highway 45. 
Figure 11. Photograph showing borrow site 2, southeast of Tyndall Mound along the Main Drain. 2.1.3.2 Construction Process and Mechanisms for Effect Borrow site excavations will generally coincide with canal construction. Excavation of borrow sites will remove soil and bring the excavated area to the same level as the rest of the fields. At the borrow site adjacent to the Main Drain, this will allow about 5 to 8 acres of land currently dry-farmed, used for dredge spoil disposal, and/or treated for weed control to be used for field crops. At the Highway 45 borrow site, this will allow for more efficient irrigation of the existing crops by providing for more even distribution of irrigation water. The process of excavation will involve scraping the land, placement of soils in trucks, and conveyance of soils to the proposed levee sites. There is no permanent wildlife habitat at either site, and loss of habitat is thus not a mechanism for effect. The mechanisms for effects to wildlife would be noise, dust, and on-site traffic. 2.1.4 Construction Traffic 2.1.4.1 Project Description The Proposed Project will require approximately 12,800 cubic yards of concrete and 134,000 cubic yards of fill, as well as other construction materials. Concrete will be obtained from regional sources and delivered to the various construction sites via Highway 45. Over the 2-year construction period, combined delivery of materials will generate from 10 to 60 truck trips per construction day (1 to 8 per hour), depending on conditions and construction schedule. The main haul route will be Highway 45; access from Highway 45 to construction sites will be via local farm and levee maintenance roads, which are generally unpaved and are not through roads. Access to the combined pumping plant/fish screen will be via the levee road, which has limited public access, but may be accessed via the existing road at the Boyers Bend Plant or via the Howells Landing access. Access to the Boyers Bend and Tyndal Mound sites will be via existing paved and unpaved roads. Access to canals, associated facilities, and borrow sites will be via existing paved and unpaved roads, as well as new unpaved roads developed as part of canal construction. 2.1.4.2 Construction Process and Mechanisms for Effect Construction traffic at the Combined Pumping Plant and Fish Screen will be on-going for about 2 years, including mobilization, site preparation, cofferdam construction, screening facility construction, and installation of screens and brushes. Construction traffic in support of canal construction and construction of connections between canals and existing facilities will be continuous but intermittent from site to site during two consecutive summers. Mechanisms for effects to wildlife from construction traffic would be noise, dust, soil compaction, and potential for traffic-related injury or death. |
