On February 13, the San Diego County Water Authority’s Special Imported Water Committee held a workshop on the BDCP that focused on the governance and infrastructure of the Bay Delta Conservation Plan (BDCP). Engineering Director Bill Rose and Engineering Manager Gary Bousquet gave a follow-up to their previous presentation on January 9. (Click here for coverage of that presentation.)
Bill Rose, Engineering Director
Bill Rose began by reminding the Board members that the review is a high-level review, both because Water Authority staff do not have the time or resources to spend replicating the work that’s been done, and also because the project itself is only at a 5 to 10% design. For the review, they evaluated the conceptual engineering report dated October 2013.
He then presented a slide of the conveyance schematic for the Bay Delta Conservation Plan, and discussed the path the water takes. “On the far left is the Sacramento River where there will be three 3000 cfs intakes, the output of which go into a sedimentation basin, to pumping plants, and then into three tunnels that with either be 20- or 29-feet in diameter. Those three tunnels all feed into a single 40 acre forebay that is about 15 miles south of the intake structures. From there, the water drops into two 40-foot diameter tunnels … the tunnels are gravity fed, and they head south to the Clifton Court Forebay,” he said, noting that Clifton Court Forebay is an existing facility that will need to be modified.
The 40-foot tunnels are 30 miles long and have five tunnel launch and retrieval shafts that will be approximately 100 feet deep, he said. He presented a slide showing the depth of the tunnels. “The twin tunnels are separated by 70 – 75 feet,” said Mr. Rose. “They are about 100 feet down, and there shouldn’t be, other than those intermediate shaft locations, any disruption to the surface.” He also noted that there is about 14 miles of total of the 20- to 29-foot tunnels at the intakes. “So that is not an insignificant part of the project,” he said.
He then discussed how the tunnels would be constructed, noting that one of the significant issues is that the tunnels are below groundwater. He then presented a slide of a picture of the tunnel currently being constructed in Seattle which is also below groundwater. “It is a highway tunnel, and it’s built with segmented concrete … They are bolted together as part of the tunnel boring machine. You can get an idea of the scale of this tunnel – this is the world’s largest tunnel boring machine at 57 feet in diameter, and one of the projects that we’ve been following. The way they do this is by bolting those segments together; they prevent water intrusion into the tunnel, or they minimize it. You’ll notice there is a black line that follows the curve of those panels, that’s a rubber gasket, and by bolting them together, you to create at least a water resistant and structurally sound tunnel interior.”
“The tunnels that we’re talking about for the Bay-Delta will not look like this,” noted Mr. Rose. “They will be lined. The discussion in the documents is that they would be lined with steel or potentially with reinforced concrete.”
San Diego County Water Authority’s process for capital improvements includes a risk management plan that identifies risk to the completion of the project – risks either to cost or to schedule – and then proposes how to manage those risks, he said. “It’s not a one shot deal; it occurs at the beginning of the project and is updated as we go along,” said Mr. Rose. “You analyze it, mitigate, monitor, update, and just identify again and keep going through this until the project is delivered.”
Mr. Rose said they took a look at other large infrastructure projects to see what how they were working out. “The Chunnel between Great Britain and France, we did find out that tunnel costs did exceed what they estimated by, and the numbers I saw were anywhere from 70 to 90% over on the tunnel costs alone,” he said. “The Alaska Way Viaduct where they are taking an above grade highway through the middle of downtown Seattle and putting it in a tunnel – they have currently spent about 75% of the construction dollars and completed 25% of the tunnel. The Calaveras Dam project is being done by the Public Utilities Commission in San Francisco; it is the backup water supply for the Hetch Hetchy Reservoir and that system; it’s an earthen dam that’s being replaced for seismic reasons. During excavation for the keyway for that dam, they discovered geotechnical issues, and the project now has a $200 million adder on top of it to deal with it.”
“A project not so close to home but to the south of us, the Panama Canal has been going through an expansion for a number of years,” he said. “The current contract is a $3 billion between the Panamanian Government and an Italian and Spanish joint venture, and that joint venture is currently asking for a $1.6 billion change order and has threatened to walk off the job. And lastly, in our state, the Oakland San Francisco Bay Bridge. In the mid 90s, it originally started as about a $1.3 billion project, but the idea of it being a statement architectural piece plus the time and design and steel prices and everything else, that project is now a $6.4 billion project.”
He then turned the floor over to Gary Bousquet to discuss the construction schedule and the risk areas that they identified.
Gary Bousquet, Engineering Manager
Gary Bousquet began saying that he examined the construction schedule in the appendix of the conceptual engineering report, and put some of the key dates up on a slide. “One of the things that we noticed in the schedule is that some of the dates were constrained, and that was a little bit of a red flag; typically we would not want to have constrained dates within our schedules,” he said. One of the comments they will be proposing is to remove any constraints within the schedule and take a second look at it, he said, adding that the current end date they are showing in the appendix is December 22, 2028.
He then presented a slide of the summary table from the Executive Summary. “In the summary table of the schedule, they talk about start up and commissioning being completed in year 9, so they are showing a 9 year evolution of the construction. Also down at the bottom they are showing that year 1 is 2017, so when we add 9 years to 2017, it would appear that this is indicating a completion date of 2026, or 2 years prior to what was included in the appendix. So again, our comment is for them to reconcile the differences and try and present a clear picture of what the schedule for this project is.”
There are a number of construction risks on this very large and complex public works project, he said. “First is property acquisition, and what we didn’t see is a comprehensive property acquisition plan that takes in the full scope and scale of all the work,” said Mr. Bousquet. “That would include the 30 miles of twin tunnels, the forebays, the pumping plants and the connecting tunnel work, also there’s a significant amount of electrical work to bring power, both temporary and permanent, to the different sites that need it; there are also a couple of sections of highway that need to be relocated. All of these activities will involve appraisals and contacts with property owners, potentially condemnation considerations, and this will tax the right-of-way environment and potentially the courts associated with all of these activities. They didn’t’ provide a list of all the different properties, but given the magnitude of this, we can only imagine it’s a very long list.”
The second area is tunnel methodology. How the excavated tunnel material is removed – by fuel-driven cars, electric trains, cars or conveyor system – will affect many things, he said. “It affects the rate at which you can excavate the material out of the tunnel and ultimately dispose of it. Also the ventilation system design is going to be a function of if there are gas fumes and it would need to be a more robust system; that’s going to affect cost and potentially time to set that up. Where all of this material that is being excavated from the tunnel is going; for example, they’ve estimated about 3200 acres between 6 and 10 feet high at the different locations. That’s a lot of material that needs to be transported and then you have to make sure that you’re not impacting the locations at which you’re disposing of it. So it’s a major concern that still has yet to be worked out.”
“They are proposing 11 tunnel boring machines, which all need to be manufactured, so you’re going to have to make sure that you have that manufacturing capability at the given time that the schedule calls for each of these pieces of equipment,” he said. “You need to extend your look beyond just this project; you need to look at what other projects are going on that might also want to compete for those resources.”
In regards to power requirements, there are three potential electric service providers, so these providers will need to be looked at in terms of their transmission system, he said. “To get that power to the different locations, there may not be currently a way to do that so you’re going to have to go in and build infrastructure, lines and poles, to get the power to the different locations,” he said. “Also, there may have to be upgrades within their system, such as substations, in order to allow that power to flow to the sites that need it.”
“With regard to permanent power, one of the items they looked at was system reliability,” he said. “Is it a good idea to have one source of power that supplies the power to these big pump stations that are going to be providing our water. They’ve indicated that they think that’s probably okay but should be looked at further. They’ve also indicated that if its determined that if a second independent power source is needed, that’s going to be a very expensive and potentially time consuming endeavor to bring that in to these different locations, so that’s another item that is a potential risk factor and a threat to the schedule.“
They don’t anticipate a lot of conflicts with utilities because the tunnel is below the majority of where other utilities are located, he said. “However, there are two sections of highway that need to be relocated associated with the pumping plants, and those are going to have right-of-way relocation issues and there potentially could be utilities that get impacted associated with that. You have to obtain the property, and then once it’s all done, the highways are going to be returned to their original location.”
Another potential when tunneling are natural gas wells, he said, presenting a map showing known natural gas wells and fields in the Delta region. “You can see this map is just covered with purple,” he said. “Each of those purple circles is either an existing or an abandoned natural gas well, so this region is covered with them, and the plan there is that you hope that they have all been abandoned in accordance with state standards. However if they come across one that hasn’t been or if there’s any kind of a leak, obviously that is going to shut down everything until you can properly deal with that before you can resume construction, so that’s another risk factor that’s out there.”
The geotechnical report was issued in April of 2013 and covered work that was done between 2009 and 2012, he said. “One item that it doesn’t account for is the recent change in alignment, so they didn’t go back and do additional borings,” he said. “And what that means in areas where the boring was right on top of the pipe, if you move the alignment, now your boring is one to two miles away and the value of that boring is reduced. The report indicates that as they move into the design phase, that they are going to do a more robust boring plan and collect even more data with the ultimate goal of identifying the ground conditions so a contractor can properly bid this project.”
Groundwater is another issue, he said. “Groundwater in the Delta area averages around 5 feet below the surface, so that’s a problem on a couple fronts,” he said. “One is that when you’re building something like a pump station, you’ve got to get the groundwater out of that area in order to construct it. The other item as it relates to a tunnel is that when you put in a big massive pipe that they are proposing, and there’s groundwater above it, it’s going to want to float, so even though you’re putting a tunnel in, they have to do an analysis that takes into consideration the buoyant forces that want to push the pipe up if it’s empty. Even with the weight of the soil on top of it, you can push the pipe right out of the ground if that isn’t engineered properly, that’s a consideration when they look at piping alternatives.”
The project delivery method can pose risks as well. “During our discussions with the engineering team, they indicated that current state law prohibits them from using design-build; they will have to use design-bid-build,” he said. “Our suggestion to be included in the comment letter is to look into potentially changing that, at least to give them the option of pursuing a design-build scenario. That may save some time on the schedule; it certainly would reduce risk associated with claims down the road by being able to keep all of these activities under one common responsible party,” noting that bonding and labor requirements are issues to be considered as well.
Available resources need to be considered, things like the manufacturing of the tunnel boring machines, or transporting the steel liner, he said, noting that currently the maximum size that can be transported is 20 feet in diameter, so how the 40-feet rings will be delivered to the construction site is going to be a big challenge, he said. Despite the fact that the tunnel excavation will generate large amounts of material, they are going to need borrow material up front to lay pads down for the pumping structures and tunnel shafts, so they will have to find and transport that material, he said. He pointed out that this is highly specialized construction, so it’s going to take all kinds of technical experts to deal with a multitude of issues, he noted. Lastly, other competing projects going on in the region with the potential to pull resources away need to be considered.
He noted that all of these notes, observations and comments will be included in the draft letter that will be presented to the Board for consideration, and with that he turned the floor back over to Bill Rose.
Bill Rose
Bill Rose then discussed the construction estimate. He said that the conceptual engineering report and the documents didn’t break anything down in great detail. “It was very general, didn’t provide a great deal of input,” he said, noting that the estimates do include a contingency of 36%.
He then presented a slide of the costs of the various options the Water Authority is evaluating, noting that these are the best cost estimates they were able to obtain. “The proposed project has a total cost of $14.3 billion, of which $1.9 billion is soft costs – engineering, construction management, etc. The 36% contingency is contained in the $12.4 billion of the cost estimate,” he said. He noted that there is a standard process for indicating the accuracy range of cost estimates. “The BDCP has indicated that their cost estimates have an accuracy range that would yield either a plus 50% increase or a minus 25% decrease. That results in a range of $11.2 billion for this project, up to $20.6 billion just based on their stated range,” he said, noting that it wouldn’t be difficult, given other major projects, to see an accuracy range that was wider than that.
So what are the greatest risks and impacts? “We clearly believe that unknown sub surface conditions pose the greatest threat to the project,” he said. “Absent that geotechnical information, you’re flying blind on your estimates and you’re using information that is not anywhere close to the project. They’ve got borings that are miles away, and they have very few of them. So they need an extensive geotechnical program to be able to dial this in even better. They proposed it; it’s included in their environmental document, but we were not able to get any greater detail on what that plan is.”
How the project is going to be delivered is significant as well. “The Water Authority has made strides to move away from the design-bid-build to design-build under certain circumstances,” said Mr. Rose. “We would certainly hope the state could explore that; that is probably the primary way that they are going to be able to transfer some of the risk of this project away from the state water project contractors.”
“They are going to have 35, 40 miles of pipeline tunnels to acquire and right of way acquisition,” he said. “They have already had very significant push back from the property owners there in that region. I don’t expect that that’s going to get any better. They have 5 years in their project schedule right now for that work; that is going to be a challenge, and given that they’re going to be in counties that don’t have a particularly large court activity, they are probably going to drop a whole lot of condemnation cases into that court system. It’s going to be very challenging.”
And lastly the resources, he said, noting that Mr. Bousquet had mentioned several already. “With 10 or 11 large diameter tunnel boring machines operating simultaneously … I did a back of the envelope estimate. You would need at least 60, qualified tunnel boring machine operators on the project through the entire time of tunneling in order to be able to complete the project according to their schedule. That’s a bare minimum. Where are they going to find 60 qualified tunnel boring machine operators to run 24/7 six days a week, which is what their stated schedule is.”
“Those risks are the ones that we would focus on, though the others are still very important and could have significant impact to the project, so how do you deal with that at this stage of the project at a 5-10% design?” Mr. Rose said. “They really only have two choices. You increase contingency and you increase the amount of time that you allocate. There was no extra time in the schedule available for completion of the project. It was a zero for start up. In a term of art, ‘float’, in that schedule. None. So they need to consider time, and they need to consider their contingency. Our recommendation is that they at least go to a 50% contingency which matches what they believe the accuracy of their current estimate.”
“And they need to be active and proactive with the risk registry and managing these risks on an ongoing basis which is standard practice in the engineering world,” Mr. Rose concluded.
For more information …
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