Metropolitan’s Special Committee on the Bay-Delta hears some of the details on the changes made to the water conveyance facilities since the project’s initial design
In December, the Department of Water Resources announced that new environmental documents were being prepared for the Bay Delta Conservation Plan due to significant changes made to the facilities design in response to comments received by the EPA and others. While all of us eagerly await the new documents due sometime later this year, Metropolitan’s Special Committee on the Bay Delta reviewed the changes that have been made to the facilities from the original design up to present day.
Program Manager Randall Neudeck began the presentation by noting that in the development of the Bay Delta Conservation Plan over the last seven years, the agencies working on the plan have made significant revisions to the conveyance elements. The Department of Water Resources has held public meetings, met with individual homeowners, received input from engineering staff, and working with the federal agencies, has made several changes in order to address local community concerns, reduce environmental impacts, and optimize the conveyance design, he said.
The presentation will focus on three areas: the north Delta, the central Delta, and the south Delta. These portions of the meeting are best understood by watching the video, so here are the segments embedded below, along with notes from the presentation.
The north Delta
Notes:
- In the north Delta, there are the communities of Clarksburg with 400 residents, Courtland with about 300 residents, the town of Hood, and the Stones Lake National Wildlife Refuge.
- Original facilities design was five intakes on the Sacramento River leading to a 750-acre forebay; there was an intermediate pump station that would then push the water to the south.
- One of the initial refinements was to reduce the number of intakes from five to three, and to eliminate the intermediate pump plant and to move the water south by gravity flow instead.
- They moved the tunnels away from local communities and closer to haul routes such as I-5
- They reduced the forebay down to 40 acres and moved it further away from the local community.
- They have now taken out all of the pump stations in the north Delta and consolidated them at the south end or terminus of the facility.
- Design has gone from six pumps (5 intakes + intermediate pump station ) to zero in the north Delta.
- Buildings have been eliminated and the number of high voltage lines needed reduced, although temporary construction lines will still be needed
Central Delta
Notes:
- The tunnel is 150 feet below ground; there is 75 feet between the two tunnels; current inside diameter is 40 feet.
- The original design was to use pumping plants in the north Delta to push water through the tunnels, which causes an outward pressure.
- The tunnel is constructed of bolted concrete segments with gaskets in between; this type of construction is much different than steel welded pipes which can take a lot of outward pressure.
- The bolted concrete segments/gasket tunnel construction method is meant for gravity flow.
- By moving pumps to south Delta, water will be sucked through, much like drinking a beverage through a straw.
- The engineers moved the alignment away from communities, closer to haul routes, and on to Staten Island.
- Staten Island is 9,100 acres, purchased with a combination of Prop 13 & Prop 204 funds; Nature Conservancy owns and operates the island.
- Staten Island is a key sandhill crane foraging and roosting habitats. There is community concern about construction impacts, so DWR has reduced some of the tunnel construction impacts, and eliminated a stockpile, reducing construction impacts on the island to about 50 acres.
- The vent shafts are about 85 feet from edge to edge; construction shafts are larger at 113 to 130 feet.
South Delta
Notes:
- There have been three different alignments/changes.
- The first alignment was to build an extension on Clifton Court forebay and deliver the water to the southern portion to keep the ‘fish-free’ water separate.
- Then they reduced the length of the pipe and put a levee across the existing forebay and realigned the tunnel to the west and under Italian Slough.
- Then they moved the alignment further back to the west, farther away from Discovery Bay, and completely on DWR property.
- They are still working to reduce the height of the southern facilities to reduce visual impacts.
- In this configuration, the water moves from north to south much like a sump pump works.
Mr. Neudeck then reviewed the benefits of these design changes:
- The overall impact of the project has been reduced by one-half.
- The intakes on the river have been reduced from five to three, all pumps have been taken out of the north Delta and placed in the south Delta, reducing the need for some of the high voltage power lines.
- The visual impacts near the town of Hood, and near the town of Courtland have been reduced.
- The size of the forebay has been trimmed down from 750 acres to 40 acres.
- Some of the construction activities and some of the construction impacts on Staten Island have been eliminated.
- System will have enhanced reliability by pulling the water through, rather than pushing.
- The use of DWR-owned properties is optimized in both the north and south Delta
- Some of the tunnel segments have been standardized.
Mr. Neudeck said that the Department of Water Resources is analyzing the changes with a recirculated draft EIR out later this year.
During the question and answer period, Director Griset noted that the forebays at Clifton Court are separate; one that’s free of fish ostensibly and one that’s not. Is there a blending that occurs on that water moving to the CVP pumps and to the SWP pumps, he asked.
“Yes, it will be blended as it moves to the pumps,” relied Mr. Neudeck. “One of the current problems right now is that the fishery agencies, if you catch one fish at the existing screen, which are after the Clifton Court forebay, they actually charge you more for it because they believe some fish got predated in the original forebay. So when they are looking at these impacts, what the fishery agencies would like is to have really a predator free forebay, and so that’s what we’re trying to do by separating those elements of water.”
Mr. Neudeck returned to slide 21 of his power point and said, “The way the forebay operates right now is that there are screens here … how the agencies estimate the amount of impact to the facility, so if you pick up one Delta smelt here [at the screens], they estimate that you’ve impacted 4 Delta smelt in this area. … It’s confusing, but that’s the way the fishery agencies calculate your impact on an endangered species. If you can take this water and go directly to that, they feel you are not going to be impacting any Delta smelt.”
Design changes presented at the Delta Stewardship Council
Later that week at Thursday’s Delta Stewardship Council meeting, Gordon Enas, Principal Engineer with DWR’s Delta Conveyance and Habitat Conservation Program, gave much the same presentation, also using video animations. Due to the difference in the systems that archive and play the meeting videos, I cannot in this instance embed sections of the Delta Stewardship Council meeting. Although Gordon Enas had some additional diagrams and animations, the majority of the videos were the same. Full versions of available conceptual animations of the facilities are embedded at the end of this post.
During his presentation to the Council, Mr. Enas did give some additional details:
Different path for tunnel construction
They are now proposing reorienting the path for the boring machines; the new proposal will eliminate many of the impacts on Staten Island. Instead of starting on Staten Island, they will start on Bouldin Island and drive the boring machines north to Staten Island; they will also start in the north and drive the tunnel boring south. They will retrieve the tunnel boring machines at Staten Island.
Mr. Enas explained how by redirecting the tunnel drives, they will eliminate putting any material onto Staten Island. “All the material that comes out of the tunnel boring machine comes out from where you start the operation,” he said. “It’s also where there is a significant amount of construction effort taking place. You bring all of your equipment, all of your supplies, your power – everything comes into where you launch your tunnel boring machines so by reorienting the way we drive the machine, we will significantly reduce the amount of impacts on Staten Island.”
Other changes have been made to minimize impacts on Staten Island. “We will still need to have permanent access, but only for operation and maintenance purposes or if there’s an emergency down the road,” Mr. Enas added.
Changes at Clifton Court
The terminus point of the tunnels has been moved from the northwest corner of Clifton Court Forebay to the northeast corner. Part of the project will be rebuilding a significant portion of Clifton Court Forebay, including rebuilding the embankment around the whole forebay. “Since we’re operating in what we call a dual operation mode, water that’s diverted from the north will end up in the northern cell, but we’ll also continue to operate as we do today, so the southern cell will operate as the State Water Project currently operates today, still using the existing intake.”
The changes will benefit both the tunnel construction and the power requirements. “What we’ve done here is we’ve made the system a pretty much a pure gravity system, so water will flow by gravity from where its drawn in at the northern intake, flow through 40 miles of tunnels, and then be picked up at these pumps in the south,” he said. “In order to make this work we had to drop the well, so what we do is we lower the hydraulic grade line by lowering where the pumps take the water out, so we have a deep well where the pumps will be inserted and that will draw the water out of the well and then discharge it into the forebay.”
Reduction in pressure on the tunnels
The original system required a much more robust liner system; in that system, the internal pressure inside the tunnel itself is greater than the groundwater pressure on the outside, so there is a net pressure in the tunnel. “By dropping the grade line and by moving the pumps to the south, we were able to reduce the internal pressure,” he said. “The benefit is that the way they construct these liner segments, they are in segments around the circumference of the tunnel, so when you have a higher internal pressure, the higher than the groundwater, it tends to over time want to open up the joints between the segments, so by reducing the pressure, we believe it will minimize the amount of opportunity for water to open those joints up and seep out through them and create a piping around the tunnel itself, so we think over the long term of the project, we think this will be a great benefit.”
Recirculated documents
Mr. Enas says the plan is to have recirculated documents around the end of March, with likely a 60-day comment period.
Visual simulation videos
Public comment: Osha Meserve
During the public comment period, Osha Meserve spoke on behalf of Friends of the Stone Lakes National Wildlife Refuge and also Local Agencies of the North Delta. “Unfortunately, these changes really don’t address the things that local folks have been concerned about with respect to the project, whether it’s actual local impacts and interference with economic and the communities and things like that, and also the environmental issues, water supplies and water quality locally. … The aesthetic impacts of additional buildings and massive intakes in an agricultural area that is proposed to be turned into an industrial water project, that’s not been the focus of our comments. It’s just a tiny little thing which may be a tiny improvement but it’s still a terrible project from a local perspective.”
“What we were looking for from DWR with their process to go back to the drawing board is to respond to the public and agency comments and look for alternatives that would not worsen water quality, violate water quality standards, violate the Clean Water Act and stretch the ESA beyond its limits, which this project still does,” she said.
They still have many concerns over the power lines. “We’re not sure at all that ten years is temporary and moreover that anything would be in place to make sure that the power lines would be removed,” she said. She also expressed concern regarding habitat destruction versus creation, noting that there is no stay-ahead provision in this HCP.
She noted that when the recirculated draft EIR/EIS and revised plan is released, there won’t be responses to comments from the public yet. “We think that’s unfortunate because it’s going to make it very difficult to review the who knows 30,000 pages of documents that still won’t’ show us how the comments that have already been received have been responded to. They are going to defer that out until the final document is released. In addition to that, the project proponents have refused to post any of the comments that have been received thus far. … Friends of the River is in the process of raising enough money to go put it up on their website in order to facilitate that public debate.”
“I would urge the Council to exercise whatever authority you feel you have to get this project on track and to force them to make the BDCP follow the coequal goals including protection of the Delta as a place,” Ms. Meserve concluded.
Coming up next …
- Tomorrow, coverage of the Metropolitan meeting will continue with a presentation on the recent report from the State Treasurer’s office, The Bay Delta Conveyance Facility Affordability and Financing Considerations.
- More to come from the January Delta Stewardship Council meeting in the next few weeks.
For more information …
- Watch the entire Metropolitan meeting video and access all meeting materials here: Metropolitan Bay-Delta Special Committee Meeting January 27, 2015
- Watch Gordon Enas’ presentation to the Delta Stewardship Council here: Delta Stewardship Council January meeting
- Click here for Gordon Enas’ power point.
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