May 21, 2025 Engineering Criteria Review Board Meeting

Yerba Buena SX80: So thank you, everybody for your patience while we set up here in the Engineering Criteria Review Board.

Yerba Buena SX80: How’s everybody doing on the board?

Yerba Buena SX80: One’s all set up.

Yerba Buena SX80: Okay, it didn’t come down today, I’m afraid. But there is water like, right around the corner.

Yerba Buena SX80: alright, I think we

Yerba Buena SX80: okay, how’s everyone doing today?

Yerba Buena SX80: I’d like to welcome everybody

Yerba Buena SX80: to this meeting of the Bcdc. Engineering Criteria Review Board.

Yerba Buena SX80: This meeting will be recorded.

Yerba Buena SX80: Okay, good afternoon. Welcome to this hybrid in-person and online ecrb meeting. My name is Rod Iwashta. I’m chair of the Ecrb, and I have a few announcements.

Yerba Buena SX80: Our 1st order of business is to call the role

Yerba Buena SX80: board members. Please use the microphones on the table to respond, unmute yourselves to respond, and then mute yourselves again after responding. Jen, can you please call the roll?

Yerba Buena SX80: Yes, Rod Iwashta, chair of the board here.

Yerba Buena SX80: Jim French vice chair. I’m here, Bob Natalia here, Geema Kasali, Chris may here.

Yerba Buena SX80: Ramin Goserki.

Yerba Buena SX80: He’s on vacation today.

Yerba Buena SX80: Nick Sittar.

Yerba Buena SX80: He’s also out

Yerba Buena SX80: team baby. If you’re late. I think he has a commencement exercise this morning. Oh, okay, that’s right. Gail Johnson.

Yerba Buena SX80: you know he’s on vacation.

Yerba Buena SX80: Patrick Ryan here.

Yerba Buena SX80: Those names here.

Yerba Buena SX80: Talia Travisoro.

Yerba Buena SX80: Here, chair washta. We have a quorum of at least 5 present.

Yerba Buena SX80: Okay, thank you, Jen. Since we have a quorum present, we are duly constituted to conduct business. I now call the meeting to order

Yerba Buena SX80: I wanna start with some instructions on how we can best participate in this meeting so that it runs as smoothly as possible

Yerba Buena SX80: for board members. If you have a camera. Please make sure that it is on during the meeting. So everyone online can see you

Yerba Buena SX80: also board members. If you would like to speak during the meeting you may raise your actual hand or your virtual zoom hand, whichever you prefer. Then, when you speak, turn on your microphone and please speak into the mic. So you can be heard clearly in the room

Yerba Buena SX80: every now and then we may have audio visual technology issues that require us to pause the meeting. So please be patient with us if it’s needed.

Yerba Buena SX80: Okay, a little bit about ex parte communications as set forth in Bcdc’s regulations. A member of the Ecrb shall not have any oral or written communication regarding a proposed project or other matter that has been noticed to be considered at an Ecrb meeting with a project proponent permit applicant, prospective applicant or member of the public, except on the record during an Ecrb meeting

Yerba Buena SX80: board members in case you have inadvertently forgotten to provide the staff with notice on any written or oral ex parte communications. I invite you to report on any such communications at this point by raising your hand and unmuting yourself.

Yerba Buena SX80: Okay for the record. No hands have been raised.

Yerba Buena SX80: Okay? So now, agenda, item number 2,

Yerba Buena SX80: we’ll have a staff update from senior engineer and board secretary, Jen Hyman.

Yerba Buena SX80: Jen. Thank you. Chair washta.

Yerba Buena SX80: I just have a few announcements. Today we have one project to review on the agenda, and I would prefer

Yerba Buena SX80: if we could finish. Try to finish up our meeting by 4 o’clock today.

Yerba Buena SX80: We currently have no future Ecrb meetings scheduled

Yerba Buena SX80: the next meetings would have been june 25th and July 30, th and I have canceled those meetings.

Yerba Buena SX80: I am sad to report that this will be my last Ecrb meeting, as I am resigning from Bcdc. It has been a pleasure and an honor to work with such an esteemed smart and fun group of people, and I will treasure my time here. I plan to downshift a bit, to spend more time with family over the summer. But I plan to this fall to jump back into an engineering role, protecting and restoring San Francisco Bay.

Yerba Buena SX80: If needed. Rod knows how to get a hold of me.

Yerba Buena SX80: But you guys are awesome, and it’s just been really fantastic working with you.

Yerba Buena SX80: Bcdc. Hopes to have a new senior engineer on board in August or September, and the job posting should be up on our website in a week or 2,

Yerba Buena SX80: and it’ll be posted for 3 weeks, not very long. So if you know anybody civil or coastal engineer who could be interested in the senior engineering position, please encourage them to apply and check the State of California, Bcdc website for that job posting.

Yerba Buena SX80: Those are all my announcements. Well, thanks, Jen, and I think I speak for the entire board when

Yerba Buena SX80: I say, we’re gonna miss you working with you has been wonderful, and thank you for hurting all of the cats and writing these wonderful skip scripts for me and handling all of the the pre work that has to get done to make these meetings run smoothly. I’m gonna miss you. Yeah. Anybody else have a few words.

Yerba Buena SX80: Yeah, Jen, it’s been a pleasure, and I’m sorry you’re leaving. It was nice having you around. I was looking forward to you.

Yerba Buena SX80: helping Bcdc progress in their coastal engineering capabilities, geomorphology, restoration, and all those things.

Yerba Buena SX80: So thank you.

Yerba Buena SX80: Yeah, there’s there’s a handful of adjectives that apply on dedicated and conscientious and insightful and

Yerba Buena SX80: motivated. It’s been great to be hard to replace.

Yerba Buena SX80: Okay, well, thanks, everybody. And thank you. Jen again, you’re gonna miss you

Yerba Buena SX80: before we move on to the presentation. Are there any announcements from board members?

Yerba Buena SX80: Okay? Hearing none.

Yerba Buena SX80: Let’s move to agenda. Item 3 Caltrans totally Creek Bridge replacement project

Yerba Buena SX80: Now we will move on to the main agenda. Item related to the anticipated. Permit application for the Caltrans, Tolly Creek Bridge Replacement Project.

Yerba Buena SX80: which is phase one of the Highway 37 Sears Point to Mare Island Improvement Project during the presentation. It is fine for board members to ask brief, clarifying questions. I hope you guys don’t mind

Yerba Buena SX80: and I would like to ask board members and presenters to please turn on your cameras for any discussion during or after the presentation.

Yerba Buena SX80: So, Jen, our Board secretary has a few words of introduction.

Yerba Buena SX80: Thank you. Rod Caltrans is undertaking a priority project to widen the section of Highway 37 between Sears Point and Sonoma County and Mare Island, near Vallejo, in Solano County. If you’ve ever been on this section of highway? 37. You’ve probably experienced the terrible traffic which occurs here since the highway next down from 2 to one lane in each direction. Through this stretch of highway. 37.

Yerba Buena SX80: You’re reviewing the portion of phase, one of the project that adds a small amount of fill in Bcdc’s Bay jurisdiction, and that is the replacement of the Tolly Creek Bridge, and to retaining walls right by it.

Yerba Buena SX80: Number 3 and Number 4.

Yerba Buena SX80: I mistakenly gave you the board materials that, said 2 other retaining walls by the bridge were under review number 5 and Number 6. However, these 2 retaining walls do not touch the Bay jurisdiction, and therefore

Yerba Buena SX80: retaining walls 5 and 6 are not under Ecrb review.

Yerba Buena SX80: as Caltrans will explain, besides helping make the highway safer and alleviate congestion. The other purpose of this project is to make the bridge longer

Yerba Buena SX80: and widen the creek at the bridge, so that the creek will no longer be pinched by the small bridge. The wider Creek section here will allow a greater tidal prism upstream which will facilitate tidal marsh restoration projects planned upstream in Sonoma. County.

Yerba Buena SX80: I would like you all to know that Caltrans is required to follow specific design manuals and guidelines in their design of bridges, so please keep that in mind as you review their design approach today.

Yerba Buena SX80: Lastly, due to a tight timeline. For this project, Caltrans is only presenting their design criteria today, not their modeling results.

Yerba Buena SX80: It is the role of the Ecrb to review the design criteria to make sure the bridge and retaining retaining wall design will be adequately protective of public safety.

Yerba Buena SX80: Okay, thank you. Jen.

Yerba Buena SX80: Now the Caltrans team will make their technical presentations and pause for some Ecrb discussion after each topic.

Yerba Buena SX80: We will take public comments at the conclusion of the presentations.

Yerba Buena SX80: So, Caltrans, take it away.

Yerba Buena SX80: Thank you. Chair one second while I share my screen.

Yerba Buena SX80: Alright. So good afternoon. Ecrb. My name is Javier Mendeville. I’m a regional project manager with Caltrans.

Yerba Buena SX80: and today I’ll be presenting on the Sr. 37 Sears point to Maryland Improvement Project

Yerba Buena SX80: sign.

Yerba Buena SX80: We’ll start off with some introductions. I’ve already introduced myself, so I’ll continue on with the Caltrans group. Michael.

Michael Bergman, Caltrans Bridge Design: Yeah. Hi, this is Michael Bergman with Caltrans bridge design.

Yerba Buena SX80: Thank you. Michael, this.

Yerba Buena SX80: Yeah. Hi, this is Louis Chen, with Caltrans bridge design.

Yerba Buena SX80: Olivia.

CT-Design Olivier Mbatchou: Good afternoon, Olivia. Hardware design.

Yerba Buena SX80: Thank you, Olivia John.

Yerba Buena SX80: This is John Moore with Caltrans geotech design West.

Yerba Buena SX80: Peter. Peter Ray, can I turn it to your technical detail with us.

Yerba Buena SX80: Jinping Lee is with hydraulics. I don’t think he was promoted as a panelist. Skylar wasn’t either skylar’s environmental planning. David also David’s our David Weber is our biologist.

Yerba Buena SX80: We can move on with Mcc. I don’t know if Kevin was at it, either. Actually.

Yerba Buena SX80: Kevin Chen is my counterpart with Mcc. So we’re on an integrated Project delivery team. So he’s my co. Pm, if you will.

Yerba Buena SX80: And Jeanette Wiseman is expected to come in in person a little later. But she’s the Sr. 37 corridor manager.

Yerba Buena SX80: We’ll continue on with Aecom. Gary.

Gary Sjelin, Caltrans: Hello! I’m Gary shalin I did the hydraulic analysis for the Tilly Creek bridge. with aecom

Gary Sjelin, Caltrans: Brad, Brad has led the drainage.

Gary Sjelin, Caltrans: I’ll let him introduce himself.

Brad Mays, AECOM: Thanks. Gary, yeah. This is Brad Mays with aecom drainage.

Yerba Buena SX80: Thank you. Brad Dylan.

Yerba Buena SX80: Yeah, I’m Dylan backer. I’m an environmental, an environmental planner with acom supporting the project on its Ceqa and Nepa documentation and environmental permitting.

Yerba Buena SX80: Thank you, Dylan, and I don’t believe Joy was added as panelists. But she’s a project engineer manager with acom.

Joy Villafranca, AECOM: Yeah, I’m here. Javier.

Joy Villafranca, AECOM: Good afternoon, Jordan Villafranco with. I’m the Consultant project engineering manager.

Yerba Buena SX80: Thank you, Joy.

Yerba Buena SX80: Alright! Here’s our agenda, so we’ll start off with the project overview, and I’ll cover purpose and need and then we’ll go ahead and focus in on some of the key project elements which include Solar Creek Bridge replacement. Those 2 retaining walls that Jen mentioned earlier

Yerba Buena SX80: before we get started. I want to spend some time on talking about the program at a higher level.

Yerba Buena SX80: So this is a phase implementation slide that we use to describe or to explain our our near term versus long term projects.

Yerba Buena SX80: So just in case you’re not aware, our long term program is based off of the results of a planning environmental linkages study which recommended raising most of 37 on elevated causeway.

Yerba Buena SX80: So we’re actively, actively working on that right. Now, we actually have one project that’s in the design phase over on the western end in Marin County, where there’s recurring, flooding currently.

Yerba Buena SX80: But as you can imagine that’s a big task. And it’s gonna take quite a while. We’re hoping to get all of this done by 2050. That’s when we’re expecting to put in the causeway where our

Yerba Buena SX80: the project that we’re talking about today. The interim project is Sears Point to my island.

Yerba Buena SX80: Yeah. A big reason for that is, is the high price tag and the extensive engineering work that needs to take place for that.

Yerba Buena SX80: At the same time, we are working on interim projects. Here’s points. Maryland Improvement Project is one of them where we’re

Yerba Buena SX80: where where we will improve travel times and reliability by eliminating that bottleneck

Yerba Buena SX80: hopefully, we’ll be able to incorporate transit and rideshare public access improvements and bailings. Restoration, as I’ll describe in the slides.

Yerba Buena SX80: So the reason we’re doing these near term projects now is the public’s been asking for

Yerba Buena SX80: help addressing the congestion. They’re frustrated with it. So there’s a there’s a real need to deliver this project sooner than later, instead of waiting until 2050 for the long term.

Yerba Buena SX80: All right. So this portion of the project which we call package number one proposes to replace Tully Creek Bridge and provide intersection improvements that will improve the traffic flows, and address recurring congestion at the intersection.

Yerba Buena SX80: If you if you’ve been through here during peak traffic hours, you you probably know what it’s like. You end up getting stuck at that intersection, and you could end up missing multiple signal cycles. So the project will address the the backup in this area

Yerba Buena SX80: the bridge replacement was added to the project as a minimization measure.

Yerba Buena SX80: it’ll add about an acre of new tidal waters and species habitat from existing upland of the project, and it’ll allow for increased tidal prison volumes that are currently constrained by engineering fill. I’ll show that in one of the slides that follows

Yerba Buena SX80: all right. So this here is a map of Bcd, certain waterway jurisdiction

Yerba Buena SX80: and and our key project components so as you could see, the the bridge replacement goes from like around here to here. So that’s

Yerba Buena SX80: partially overlaps Bcdc. Jurisdiction. And then there’s 2 retaining walls on the south side, on the east and west ends of the bridge, retaining Wall number 3 and retaining wall number 4

Yerba Buena SX80: the 2 retaining walls. That aren’t a part of that aren’t in just Ecdc jurisdiction are up on the northern side. So there’s 1 right here, and then there’s 1 on the other side of this levee here.

Yerba Buena SX80: that whole green strip the bridge.

Yerba Buena SX80: Excuse me, no the bridge goes from. I don’t know how well you could see that, but from right there.

Yerba Buena SX80: So where this levy is, the next slide shows it a little better. The green strip in this image is where Vcg jurisdiction occurs in the project area.

Yerba Buena SX80: But there’s a little oh, the existing bridge, the existing bridge!

Yerba Buena SX80: I guess both questions. I mean, I I got a better slide for that.

Yerba Buena SX80: So these are renderings of existing and proposed conditions

Yerba Buena SX80: the existing bridge is right here. It’s only about 60 feet long. If you’re driving along the highway you’ll barely notice it.

Yerba Buena SX80: and then our proposed structure will. We’re expecting will look something like this. It’s about 6 times longer over, 6 times longer, 375 feet.

Yerba Buena SX80: And

Yerba Buena SX80: yeah, like, I said, we’re lengthening it from 60 feet to 375 feet, and that’ll help with habitat restoration.

Yerba Buena SX80: Our our current.

Yerba Buena SX80: Oh, I’m sorry. Can I just ask a quick question is the right photograph Photoshop. So that you’re just showing the new

Yerba Buena SX80: prism.

Yerba Buena SX80: Yes, okay, exactly. Thanks.

Yerba Buena SX80: All right. So the geometry on the proposed structure is constrained by these existing smart tracks over to the west of the approach. So our approach pretty much starts right after the smart tracks. If you’re going in the eastbound direction.

Yerba Buena SX80: We’re complying with highway design manual requirements, and that’s pretty much driving the geometrics of the bridge. Let me let me re ask Rod’s question, he asked. If you had photoshopped that shot. I think that

Yerba Buena SX80: all the water you’re showing in here is actually photographic water, right? No. So you actually have filled that in with Photoshop and altered that image. So what we’re seeing here are visual simulations that were generated by the Caltran shop. So on the left. Most of that is an aerial image that’s existing conditions there. I think they added the rail line in there, because that that train doesn’t run along that line right now.

Yerba Buena SX80: so on the image on the left, that is essentially existing conditions, without any alterations made to the image on the right it is showing the existing bridge removed and replaced with the new bridge being proposed, and the waterway, the channel, and the Tule creek there. That is also a simulation. Assuming that watershed restoration that’s going to be done by others would be implemented there.

Yerba Buena SX80: Okay, got it? Thanks.

Yerba Buena SX80: right? So as you can see, the creek flows are constrained by all this engineering fill in this area. If you see on the on the left hand side photo, and the idea is, once we replace the structure. We’ll be able to remove all of that, and then eventually it’ll it’ll look something like this.

Yerba Buena SX80: Alright. So back to the geometrics. Our geometry, our profile, for the bridge is constrained by the smart tracks

Yerba Buena SX80: in order for the bridge to go higher, the proposed structure to go higher, we’d have to start the approach west of the tracks.

Yerba Buena SX80: But the railroad, the the trains are are limited in the grade that they could climb to 1%. So if we were to raise

Yerba Buena SX80: the approach or the track set about for one foot, we’d have to do a hundred feet of of track replacement on on either end, so that would be completely out of the scope of the project.

Yerba Buena SX80: So that’s why the bridge geometry is the way it is, and there will be a future slide that talks a little bit more about that. You probably will, or somebody will need to raise smart in 2050, I guess at the next stage of

Yerba Buena SX80: correct, and we don’t know what that’s going to look like. They’re very early on their studies for project initiation.

Yerba Buena SX80: So they’re still working that out but once we find out what their proposal is, we’ll be able to come in and and design our future facility accordingly.

Yerba Buena SX80: Alright, and then

Yerba Buena SX80: I’m gonna talk a little bit about staging here, but a future slide will show it in more detail. But since we have the photos here it might be helpful to see

Yerba Buena SX80: The the bridge will be replaced in 2 stages so we’ll require a temporary structure for a temporary bypass.

Yerba Buena SX80: Which will go over on the north hands northern side, like around this area above the engineer fill, and it’ll cross the existing solid creek.

Yerba Buena SX80: and this is just a different view of both the existing and the proposed. So, as you can see, the existing is very narrow, 60 feet, and then the proposed bridge will have 6 spans, 375 feet, and then we’ll remove all of this engineered fail

Yerba Buena SX80: in between the ends of the bridge.

Yerba Buena SX80: Alright! At this point I’ll hand it off over to Michael.

Michael Bergman, Caltrans Bridge Design: Yeah. So this slide shows the.

Michael Bergman, Caltrans Bridge Design: It shows the elevation view of the bridge. The bridge is going to be. As Javier mentioned 370 foot long, 375 foot long, and it’s going to be a precast

Michael Bergman, Caltrans Bridge Design: Precast pre-stress voided slab, and it’s going to be a continuous superstructure.

Michael Bergman, Caltrans Bridge Design: So we selected that superstructure type to meet the low profile and to still meet the minimum soffit elevation.

Michael Bergman, Caltrans Bridge Design: we’re constrained. We’re constrained on one side of the bridge by the smart tracks as we’ll show in the previous slides. And so that kind of dictated what the profile looks like here.

Michael Bergman, Caltrans Bridge Design: The abutments abutment one and 7

Michael Bergman, Caltrans Bridge Design: are going to be seat type abutments founded on 4 foot diameter. Cidh piles

Michael Bergman, Caltrans Bridge Design: with secant piles in between the main structural piles for the abutments.

Michael Bergman, Caltrans Bridge Design: and that allows for top down construction.

Michael Bergman, Caltrans Bridge Design: The piers, 2 through 6 have drop caps on 4 foot diameter. Civh, pile extensions.

Michael Bergman, Caltrans Bridge Design: The pilot extensions go up to the up to the bottom of the drop cap, and they have a permanent steel casing. That extends with them.

Michael Bergman, Caltrans Bridge Design: And then we’ll also be providing additional cap with here to to help with the fault. Rupture. That we have at the site

Michael Bergman, Caltrans Bridge Design: next slide.

Michael Bergman, Caltrans Bridge Design: So this slide shows

Michael Bergman, Caltrans Bridge Design: it shows the plan view of the bridge, and you can see you can see where the retaining walls tie into the bridge, so the 2 retaining walls at the bottom here number 3 and number 4 that are highlighted.

Michael Bergman, Caltrans Bridge Design: Those are the ones that are within the Bcdc. Jurisdiction.

Michael Bergman, Caltrans Bridge Design: and then at the top, there you can see, retaining all 5, which is not in the jurisdiction.

Yerba Buena SX80: And next slide can I ask a quick question.

Yerba Buena SX80: where does the fault trace track through? On plan?

Yerba Buena SX80: Approximately.

Michael Bergman, Caltrans Bridge Design: That’s a a good question, I think. Our our geotechnical engineers can help answer that.

Yerba Buena SX80: That’s John Moore. I I can’t tell you exactly, but it’s it’s it’s under the. It’s under the current bridge right now.

Yerba Buena SX80: We have a report for it. It’s under the

Yerba Buena SX80: the current bridge. It’s under the existing short bridge. Yes.

Yerba Buena SX80: that’s my understanding. We we do have a report for it.

Yerba Buena SX80: We can forward that to you later on, if if need be, if you need to review it.

Yerba Buena SX80: I think they I think you have the report correct. Yes.

Michael Bergman, Caltrans Bridge Design: Okay, next slide. Javier. Okay, so this, this slide shows our sage construction. Just kind of give you a better idea of how

Michael Bergman, Caltrans Bridge Design: how we expect this, or how the bridge is going to be built. So stage one A is to construct a detour with a temporary bridge that was mentioned. So the temporary bridge is only gonna span the existing creek, which is 60 feet long.

Michael Bergman, Caltrans Bridge Design: A problem, you know, plus or minus. And then the detour in that area is going to use the existing fill on the north end of the bridge

Michael Bergman, Caltrans Bridge Design: stage one B. Then would be to come in and construct the

Michael Bergman, Caltrans Bridge Design: the portion of the bridge you see on the right there and then.

Michael Bergman, Caltrans Bridge Design: and also demo part of the existing bridge.

Michael Bergman, Caltrans Bridge Design: and then stage 2 would be to shift traffic onto that new bridge, remove the temporary detour and the temporary bridge, and construct the left portion portion of the bridge shown there.

Michael Bergman, Caltrans Bridge Design: Okay, next slide.

Michael Bergman, Caltrans Bridge Design: And then here’s a typical.

Yerba Buena SX80: Can I? Can I ask a question.

Michael Bergman, Caltrans Bridge Design: Sure. Yeah, thank you. When does the the excavation of the.

Yerba Buena SX80: Engineered fill that you were talking about happened, is it? Is it? During

Yerba Buena SX80: stage one and 2? You’re also excavating the the the creek bed.

Michael Bergman, Caltrans Bridge Design: So that would be, I believe, after the final final stage of the bridge.

Michael Bergman, Caltrans Bridge Design: So so right now, the way the bridge is designed is that it can.

Michael Bergman, Caltrans Bridge Design: It can be constructed with with that fill in there.

Michael Bergman, Caltrans Bridge Design: And that’s 1 of the reasons that casings were brought up on the on the columns to allow for exclamation afterwards.

Yerba Buena SX80: Okay. Thank you.

Michael Bergman, Caltrans Bridge Design: Okay, so this slide shows what type of retaining walls we’re using here. So retaining wall 3 is a secant pile wall

Michael Bergman, Caltrans Bridge Design: and then retaining Wall 4 and retain. Wall 4 is a type, one wall on class 140 driven piles, and then it’s going to use a lightweight fill behind the wall to allow to allow for a reduction in the settlement.

Michael Bergman, Caltrans Bridge Design: and the lightweight fill is either going to be, you know, Eps blocks or cellular concrete next slide.

Michael Bergman, Caltrans Bridge Design: So this one shows the design criteria that we’re using for the project.

Michael Bergman, Caltrans Bridge Design: So for the bridge, we’re going to be using the Ashto Lrft Bridge design specs. This is the 8th edition, which is from 2,017, with the California amendments, which were last Updated in June of 2024.

Michael Bergman, Caltrans Bridge Design: We’re also gonna be using the standard plans and specs from Caltrans, which are 2024, with the revised standard Plans, dated April 2025.

Michael Bergman, Caltrans Bridge Design: The seismic design for the bridge is going to be done using seismic design criteria version 2.0, which is from April 2019. And that’s

Michael Bergman, Caltrans Bridge Design: the cal, the Caltrans criteria.

Michael Bergman, Caltrans Bridge Design: And then, for the fault rupture. The fault rupture report shows horizontal offset of 1.7 feet and a vertical offset of point 9 feet, so that will be designed for with the bridge

Michael Bergman, Caltrans Bridge Design: on top of the our standard seismic design.

Michael Bergman, Caltrans Bridge Design: We’re including dead load for one inch polyester concrete overlay.

Michael Bergman, Caltrans Bridge Design: and then for the live load. We’re designing for our normal Hl. 93 trucks and our permit design loads

Michael Bergman, Caltrans Bridge Design: for the retaining walls. We’re using the same design criteria for

Michael Bergman, Caltrans Bridge Design: we’re using the Ashdo design criteria, Lrfd.

Michael Bergman, Caltrans Bridge Design: 8th edition, and then the Caltrans standard plans and specs. And then this shows you know what the soil parameters look like. Look like for either the lightweight Eps box or the lightweight fill that we’ve been using

Michael Bergman, Caltrans Bridge Design: next slide. So this this slide shows

Michael Bergman, Caltrans Bridge Design: kind of shows a typical temporary bridge. So this is.

Michael Bergman, Caltrans Bridge Design: you know, the bridge is going to be selected by the contractor. But the bridge that we’ll be using to span Tolly Creek is going to be similar to this. So this one shown here is just an example. But it’s an Acro bridge.

Michael Bergman, Caltrans Bridge Design: and it’s just a modular bridge that can be brought in and used for the temporary detour.

Michael Bergman, Caltrans Bridge Design: Okay, I’m gonna go ahead and turn it over to our geotech team.

Yerba Buena SX80: Hi, this is John Moore again. This is a this slide shows the

Yerba Buena SX80: the layout of the of the new bridge. It’s hard to see, but you see the abovements, the vents.

Yerba Buena SX80: and some of the some of the existing borings that we we have

Yerba Buena SX80: as well as some of the some of the Borings and Cpds that we’ve done

Yerba Buena SX80: the next slide.

Yerba Buena SX80: Our field investigation, which ran from 2023 to 2025.

Yerba Buena SX80: We did 4 motor mud rotary wash soil borings up to about 162 feet.

Yerba Buena SX80: During that time we did field tests of standard patient penetration tests, pocket pens. And then we also did. Additionally, 8 comb penetration tests up to 119 feet in depth.

Yerba Buena SX80: and during those some of those Cpts we did 3 seismic measurements.

Yerba Buena SX80: and also, in addition to that, we did a review of as built logs of test points

Yerba Buena SX80: next slide, please.

Yerba Buena SX80: Here you can see this is a plan view of the Cpts and the the borings that were performed

Yerba Buena SX80: along the this, the center line. You can see here in the stationing the bridge, John, I have a question. All of these cpts and borings.

Yerba Buena SX80: our cpt-twenty, 3 or r-twenty, 3, 2 slides earlier. Everything was dash 22. Are these a different collection of explorations? This is, yeah. This would be a different collection of exploit. This is this is during our our actual investigation.

Yerba Buena SX80: the old, the older slide. Just so. There’s no slides that composite both phases of investigation. We’ve got 2323,

Yerba Buena SX80: I guess. Twenties.

Yerba Buena SX80: Can I say something? Yeah. Did

Yerba Buena SX80: 22. Is that we plan? We will be planning in 22. But actually during the 23. So cash number numberings, which year starts or 23 and dash, dash, dash 0, 0, 1, 0 0 2, actually, during. Yeah.

Yerba Buena SX80: So in our Caltrans drilling Manual.

Yerba Buena SX80: we’re required to come up with a unique identifier for each boring and each Cpt

Yerba Buena SX80: and the discrepancy, you see, which I didn’t see is we originally planned to do the investigation in 22.

Yerba Buena SX80: That didn’t happen until 2324. And so those identifiers are updated to the year that that these boardings were performed.

Yerba Buena SX80: So so 23 dash 00, 2 would be the same as 22 dash 00, 2, but 23 dash 00, 2 is more like an as built location, and 22 00, 2 would have been.

Yerba Buena SX80: Yeah, I mean, I would have to go through each and every one to verify it with you. But yes, okay. So it’s not actually 2 sets of data. It’s not one set of data that has different stages of it’s just different stages of engineering. Okay? Good enough.

Yerba Buena SX80: Next slide, please.

Yerba Buena SX80: Okay, what we’ve you know, this is kind of an overview. But what we found was that our fill thicknesses ranged from 3 to 10 feet

Yerba Buena SX80: prior below that we hit soft to soft clay soils. Younger bay. Mud

Yerba Buena SX80: from 34 to 60 feet in thickness.

Yerba Buena SX80: in mud, increases from west to east.

Yerba Buena SX80: We also encounter, stiff to hard clay soils, with a few layers of medium dense to very dense sand

Yerba Buena SX80: within a consolidated bay mud

Yerba Buena SX80: below below young Bay mud up to the maximum depth drill, which were, what about 162 feet

Yerba Buena SX80: next slide the Fo. The following 9 slides

Yerba Buena SX80: are the actual cpts and lotbs.

Yerba Buena SX80: I don’t know how much time you want to spend on these. But this is the

Yerba Buena SX80: this. These are the results of our geotechnical investigation.

Yerba Buena SX80: and that’s the ads built there.

Yerba Buena SX80: And then what this is. This is a representation. I mean, we’re we’re we’re we’re focused on the Tolly Creek Bridge. So

Yerba Buena SX80: between station, was it 202 50

Yerba Buena SX80: that’s the Tole Creek Bridge. The rest of this

Yerba Buena SX80: display is includes our entire geotechnical investigation, so that whole length is all of 37, and our current bridge is that dense collection of explorations on the left hand quarter, inch or so? Yes, sir, okay.

Yerba Buena SX80: but it it gives you an idea, you know, if you look at the the blue line is the ground surface the brown is the approximate bottom of the young bay mud.

Yerba Buena SX80: and the black line is the approximate termination of each, each boring or each cpt.

Yerba Buena SX80: So it gives you an idea of the thickness of the bay mud out there. It’s pretty thick.

Yerba Buena SX80: May I ask a question about that?

Yerba Buena SX80: I’m sorry.

Yerba Buena SX80: So I understand the piles are gonna be deriving their capacity from the material below the Yang Bay mud. And ha! I saw that in the geotech report, and has it been sufficiently characterized that there’s a sufficient depth?

Yerba Buena SX80: Yeah, yes.

Yerba Buena SX80: okay, just just noticing that there is like in some. For some cases the bottom of the boarding is very close to the bottom of the young demand.

Yerba Buena SX80: Yes, I guess that’s where my comment goes. Yes. So we have appropriate depth of borings below the young V. MoD to characterize the material based on our calculations. Right? Yeah.

Yerba Buena SX80: 30 to 60. So, and our boarding and Cpt went down to about 160 feet. There’s much below the pay mode

Yerba Buena SX80: we are looking. Look at a totally correct bridge. This just add a toll of the hill hillside, you know.

Yerba Buena SX80: So thai side location I see. So it’s to the to the west, to the west. Yes, thank you.

Yerba Buena SX80: So it should be sufficient to get to get capacity.

Yerba Buena SX80: So you’ve done preliminary calculations, at least on your drill shaft capacities

Yerba Buena SX80: and estimated tip depths, tip elevations for those, and then you add a couple of pile diameters or 20 feet, or how much? How far below the pile tips. Are you going for your explorations?

Yerba Buena SX80: Yes, we did. Yes, how much deeper than the tip elevations

Yerba Buena SX80: right now, probably 30 or 40,

Yerba Buena SX80: 30 or 40 feet below the tape below the tape. So 160 feet.

Yerba Buena SX80: Yeah, total depth is maximum depth is 160 feet 62.

Yerba Buena SX80: Hmm!

Yerba Buena SX80: So it looks like you have one or 2 borings that go that deep, I guess, and another several others that go

Yerba Buena SX80: closer to yes, not every reporting, not every board didn’t go that deep. No.

Yerba Buena SX80: In addition, we have the comb penetration tests

Yerba Buena SX80: which is calibrated against the borings

Yerba Buena SX80: because comb penetration test gives you soil behavior type, where you actually get the actual soil.

Yerba Buena SX80: you can identify the soil from the borings themselves.

Yerba Buena SX80: But it looks like there’s only a couple of borings. I think that went down to 1, 90 or so. That’s correct. And the Cpt is all stopped

Yerba Buena SX80: closer to the pilot elevations, I think?

Yerba Buena SX80: Yes, okay.

Yerba Buena SX80: I guess the question is, you know, geologically, you observe any variations between.

Yerba Buena SX80: you know that deep orange that

Yerba Buena SX80: variations

Yerba Buena SX80: we look at the boarding seems that they are pretty consistent. You know. There’s a very clear cut of a line between Soft Bay MoD and Consolidated Bay MoD. In our judgment. We believe the layers will be similar along the bridges, layout, layout, print or footprint or something.

Yerba Buena SX80: Okay? So I mean, what’s the let’s open?

Yerba Buena SX80: Why, it’s red on. Yeah. So you know, I’m just. I’m just wondering whether you have a profile showing.

Yerba Buena SX80: you know, where they are tipped in alluvium or some sort of bedrock.

Yerba Buena SX80: No, we don’t have a specific for the Portuguese side. And

Yerba Buena SX80: those Arrow TV show in more detail

Yerba Buena SX80: of the world. What we encountered in the boring.

Yerba Buena SX80: Okay, let me go back here.

Yerba Buena SX80: Some of the all those uniques.

Yerba Buena SX80: Yeah, you want someone to stop.

Yerba Buena SX80: Well.

Yerba Buena SX80: creating a lot of this stuff.

Yerba Buena SX80: Nice.

Yerba Buena SX80: This one goes down to a hundred 50, or minus a hundred 50 feet.

Yerba Buena SX80: I don’t know if we could zoom in on these or not

Yerba Buena SX80: how they can’t know

Yerba Buena SX80: you can with the Powerpoint. Wow! If you want to stand up at the back of the screen.

Yerba Buena SX80: I was just gonna point out the pocket pens.

Yerba Buena SX80: What?

Yerba Buena SX80: Yeah. 4, 4 and a half.

Yerba Buena SX80: 4 and a half, 4 and a quarter 1,000 square foot.

Yerba Buena SX80: Hmm!

Yerba Buena SX80: Oh, should be should be sufficient

Yerba Buena SX80: next one. Yes.

Yerba Buena SX80: Okay, this this shows a a list of the different lab tests that were performed on the on the soils.

Yerba Buena SX80: You know your typical moisture, content, mechanical analysis, or particle gradation.

Yerba Buena SX80: Attaberga limits for your plastic limit or for your plasticity, index unconfined compression, consolidation undrained triaxial consolidation and corrosion.

Yerba Buena SX80: I think in this presentation, though you don’t have any information about the quantity of tests or about the actual values of the test results.

Yerba Buena SX80: We could give you that if you want it would. It would run probably about 50 pages into the into the presentation

Yerba Buena SX80: we’re evaluating, I mean eventually, whether it’s this stage or another meeting. The engineering criteria part of the engineering criteria doesn’t say, Yeah, we did.

Yerba Buena SX80: Atterberg limits. That means 2 of them. But they didn’t cover the right depths of, and so on. So we’re we’d like to see.

Yerba Buena SX80: Not just you did atterberry limits, or that you did

Yerba Buena SX80: triax tests, or whatever you’ve done. But you’ve done a quantity, and that they they’re representative.

Yerba Buena SX80: I mean, we’re not doing a

Yerba Buena SX80: a peer review calculation. Re, you know, we’re not re retracing all of your calculations. But we like to be able to see the actual

Yerba Buena SX80: extensive data.

Yerba Buena SX80: We we can provide that values.

Yerba Buena SX80: We, we were just

Yerba Buena SX80: trying to present an overview for this. It’s a lot of data, but we’ll provide it for you.

Yerba Buena SX80: That’s fine.

Yerba Buena SX80: Thanks next. Okay. Finally, the analysis and soil parameters.

Yerba Buena SX80: our site specific dynamic round response analysis for designed ars. That’s that’s for the bridges.

Yerba Buena SX80: the bridge, younger Bay mud strength. 250 Psf consolidate Bay mud strengths range from a thousand to 4,000 Psf. For the file pile. Foundation analysis.

Yerba Buena SX80: The respective geotech resistance factors used were 0 point 7 and one. They’ll be applied under static and seismic conditions.

Yerba Buena SX80: And we’re using shaft and a pile programs for the pile foundation analysis.

Yerba Buena SX80: And that’s shaft and apal are are standard in the industry.

Yerba Buena SX80: I believe they’re based on api criteria.

Yerba Buena SX80: Is there? Liquefaction, assessment or slope stability assessments is is part of the analyses.

Yerba Buena SX80: There’s a basically soil. And below pay mud also mostly is a clay soil. There’s a notification issue.

Yerba Buena SX80: And maybe I’m not. I’m not a Geo. I’ll get. I’m not a geotech, but I just

Yerba Buena SX80: would think that with young Bay mud there there could be slope stability issues as well, no, there are. The side are pretty flat.

Yerba Buena SX80: Okay, thank you.

Yerba Buena SX80: So alright

Yerba Buena SX80: rod jumped in a couple of questions I had planned. This is. This is a good a time as any, perhaps.

Yerba Buena SX80: I in the Preliminary foundation report, or whatever it was called. It says it’s all clay.

Yerba Buena SX80: No liquefaction.

Yerba Buena SX80: But I think what would be a little bit more standard that we would like to see is, since you have a lot of cpts to just drop the cpts into something like clic

Yerba Buena SX80: and have clich. Make that determination. And then it’s just sort of an easy scan. It’s, you know, a couple of 100 bucks to buy C. Lick, and it’s

Yerba Buena SX80: half an hour of effort to drop everything into clic and print out the results. And we have the Clc. We can do that for you.

Yerba Buena SX80: You have run it, or you have not run it. I don’t know. I don’t think we’ve run it, but we do have it no available, we can run it. That’s fine. Yeah. So I think that it’s valuable to drop it in and have it scan. I mean we can get down there and stare at a whole lot of friction ratios and and sell behavior types and stuff.

Yerba Buena SX80: And say, Well, that looks.

Yerba Buena SX80: you know there’s a bump in the tip resistance, and it looks like it’s probably pretty sandy. But I wonder how dirty it is.

Yerba Buena SX80: It’s definitely easier, and it’s just easy to drop it into Sea Lick, and it does all that.

Yerba Buena SX80: There’s a lot of head scratching for you, and lets you just jump jump to it and say, and then, granted, there will be places probably that see, Lick will say, Yeah, here’s a 18 inch thick layer that shows up as liquefiable. And Clix let let you put in thin layer corrections, screenings? Yes. But then you can also

Yerba Buena SX80: jump on top of that and say, Yeah, you know, we we think that it see, look is showing. Look a file. But we think that it’s a discontinuous lens that’s not gonna have any impact on the design, or whatever you know you use appropriate engineering judgment.

Yerba Buena SX80: But I think it makes sense to do that screening. Oh, you’re correct. We’ll do it.

Yerba Buena SX80: Take. We’ll take care of it. Thanks.

Yerba Buena SX80: Okay.

Yerba Buena SX80: Jim, did you have more more questions? You you asked also about

Yerba Buena SX80: slip stability. So everything is relatively flat. But it would be useful, maybe, to look at some details of you know everything is not completely flat, because

Yerba Buena SX80: least wise. I think that the abutments you have some embankment slopes, or you have some, you know. Maybe you can screen everything out and say the maximum height slope is, I mean, there are slopes out there along the creek banks along the embankment sides.

Yerba Buena SX80: you might be able to say, the maximum height of any slope is 8 feet, and the

Yerba Buena SX80: the average inclination is on the order of 8 to one.

Yerba Buena SX80: Therefore we’ve not done any further analysis, because we think that’s but but just saying that it’s flat is not, quite, strictly speaking, true.

Yerba Buena SX80: Yeah, I think we can write if we pull a retaining wall there and see what we will have. That’d be great. Yeah.

Yerba Buena SX80: I have a few more questions on the geotechnicals items.

Yerba Buena SX80: If we’re staying with the jitter. Okay.

Yerba Buena SX80: just a couple more questions.

Yerba Buena SX80: I was wondering, are the pile lengths controlled by axial demands, primarily or bilateral demands.

Yerba Buena SX80: and then a follow up question on those are you considering for the axial demands?

Yerba Buena SX80: Do you see any possibility for consolidation induced down dragging the young. And are you considering this

Yerba Buena SX80: for the lateral demands? Are you considering potentially cyclic degradation in the young Bay mud. As I see, we’re in an area of very high seismicity. So maybe there is

Yerba Buena SX80: potential for the young Lima to

Yerba Buena SX80: lose some part of its strength.

Yerba Buena SX80: So 3 questions. Sorry, all packed together. But and we can go one by one. I can repeat.

Yerba Buena SX80: I think so far.

Yerba Buena SX80: the vertical load. Control. Yes, because of our pile up to about a 100 feet 110 feet long, and I think lateral load only is on the top portion is only yeah. So vertical load is a control, and down we haven’t include yet, but if they need, we can include it.

Yerba Buena SX80: because the top portion when we did a calculation. We don’t count too much pay model friction.

Yerba Buena SX80: We don’t count too much, so that would that portion we can utilize for us. We haven’t finalized our report yet. So still. In the design phase, we are working with design. So we still final 2 decisions for the foundation

Yerba Buena SX80: and other things for

Yerba Buena SX80: for the, for the lateral. It’s about mainly the reinforcement, and yes, I think they will reduce some the strength will reduce some, but usually for the soft material. You don’t see too much the strength already low. So we we use a 2 50 Epsf for our calculation. So even you

Yerba Buena SX80: down to half this is still very, very low. We don’t count that much for pay model when we calculate a foundation to check the lines or something. File a cheap evaluation, something. We don’t rely too much on the pay mode.

Yerba Buena SX80: Okay? Sure, it’s low. But maybe the the lateral. It provides still some resistance, and it’s increasing with depth.

Yerba Buena SX80: So I guess the comment would be, maybe, or at least assess. Or if you see that these effects are negligible.

Yerba Buena SX80: but I think it’s important to at least

Yerba Buena SX80: see if they are quantify, quantify, or assess. I think we can. We can give the reduce the strength to project design and let them look at it. I think we can do it

Yerba Buena SX80: to Piggyback. On that I guess the question would be. Were you counting on the day mode when you admin your lateral analysis.

Yerba Buena SX80: believe doesn’t matter how solved they always some lateral resistance. And I think we plan to use the K casing right Louis.

Yerba Buena SX80: are we going to casing? Right? So I still permanent casing? Yes.

Yerba Buena SX80: in the bay, Matt section in the soft in the soft layers. Yes, yeah, we’re we’re planning to case that with a permanent casing.

Yerba Buena SX80: Okay? Good.

Yerba Buena SX80: That does permanent casing doesn’t affect lateral. It’s

Yerba Buena SX80: so I think the latter question, yeah, your lateral question has to do with soul not structural. Yeah. Yeah.

Yerba Buena SX80: So for yeah, our permanent casing from the design side is for structural.

Yerba Buena SX80: But your question refers to soil

Yerba Buena SX80: capacity. Lateral soil capacity within the within that soft payment layer. Correct?

Yerba Buena SX80: Yeah, that essentially the bending and the pipe has been designed up with the appropriate lateral loads and the appropriate resistances. So if the resistance of the Yang is further reduced because of the earthquake heating, and the resistance further reduces from the static peak.

Yerba Buena SX80: Has this been quantified, or are you planning to quantify it and consider it in the

Yerba Buena SX80: in the lateral pile. Analysis.

Yerba Buena SX80: I think, for the design of the bridge. Our information does come from the geotech, so whatever soil

Yerba Buena SX80: parameters they dictate, that’s.

Yerba Buena SX80: you know, sufficient for our design requirements. That’s what we follow. So I think that’s probably a question for Peter and John.

Yerba Buena SX80: The behavior on their seismic, you know. Yes, okay.

Yerba Buena SX80: so. But I guess the question is, what’s your

Yerba Buena SX80: incorporation of a steel casing in the subzone dictated by

Yerba Buena SX80: the moments that you were given by geotech.

Yerba Buena SX80: Oh.

Yerba Buena SX80: I mean, I think that that’s part of our design analysis for for seismic a lot of our control at these, with these soft soils is the lateral due to size and the seismic conditions. So it’s it’s really dictated by the analysis

Yerba Buena SX80: and design is currently ongoing. We do utilize the the sole profile for

Yerba Buena SX80: I guess, for in this case will be the Pyz you’re referring to right the Sol Springs lateral soul springs. So we do utilize that information.

Yerba Buena SX80: to design our site for our seismic. And it’s a performance based seismic analysis. Right? So

Yerba Buena SX80: so your preliminary foundation report didn’t say anything about casing. I think it said as as Cidh

Yerba Buena SX80: but it sounds like you have casing going as deep as the bay mud, but not

Yerba Buena SX80: to the bottom of the shaft. Is that correct? Yeah, it does not end at the bottom of the shaft, as I understand it now, but it will go relatively deep. We’re in the design process now, so we’ll make that final. So it’s kind of a hybrid E. Ciss Cidh.

Yerba Buena SX80: it’s we call it a CID for permanent casing. The Ci says, will constitute method of installation, too, which is driving, and we’re not

Yerba Buena SX80: like forcing the contract to drive the permanent casing. So the method of installation could be something other than driving if needed. We just needed to get down to whatever casing tip that is required, based on our structural analysis.

Yerba Buena SX80: you mentioned in this slide here shaft and a pile. What do you? What software are you using for lateral analysis?

Yerba Buena SX80: Sorry.

Yerba Buena SX80: Can you repeat that question? Sorry. What software are you using for lateral analysis.

Yerba Buena SX80: Mike? You wanna go ahead and answer that sorry.

Michael Bergman, Caltrans Bridge Design: Yeah. So so we’re using L pile to develop the py curves. And then for lateral analysis and the seismic design. We’re using Csi Bridge model the, you know, we. We model each frame

Michael Bergman, Caltrans Bridge Design: in the transverse and longitudinal direction.

Yerba Buena SX80: Let’s see. So I I think we’re at the end of the geotech presentation. Is that correct?

Yerba Buena SX80: That’s correct? If so, let me let me back up and ask a couple of questions from earlier as well.

Yerba Buena SX80: or some of them, I guess, are right where we’re at now. Any load testing on the piles planned?

Yerba Buena SX80: No, not this time. No.

Yerba Buena SX80: We let me preface that we might. We might do some restrikes for

Yerba Buena SX80: some of the piles for the retaining walls.

Yerba Buena SX80: Okay, that’s enough. 40 inch. That’s a that’s a big strike. I mean, you can do a Stat stat namic load test potentially. Yeah, you can do an O cell type of of

Yerba Buena SX80: bi-directional load testing.

Yerba Buena SX80: But so far nothing planned on that.

Yerba Buena SX80: Nothing planned, no caltrans frequently with bigger bridges, at least in bigger shafts, likes to have.

Yerba Buena SX80: You know. One exploration per

Yerba Buena SX80: one expiration that goes at least 20 feet below, or some some depth below tip of pile.

Yerba Buena SX80: at least at every bent, if not at every major shaft. Do you have things going

Yerba Buena SX80: at the full depth at each bent you’ve got like 7, 6, or 7 spans, I think, which makes 7 or 8 vents.

Yerba Buena SX80: We’ve we’ve tried our our best to represent the beds, but unfortunately

Yerba Buena SX80: we were relegated to drilling within the roadway itself.

Yerba Buena SX80: which is always fun. You know that that’s where we were restricted

Yerba Buena SX80: simply to the roadway. We could not go any further out

Yerba Buena SX80: It’s the best we could do, considering the permit we got. You’re not getting full width of the beds. That’s why you’re getting at each bent. Yes.

Yerba Buena SX80: and at each bent you’re bent. You’re going to the some depth below anticipated tip elevations. It’s based on the on the loads presented presented to us at the time.

Yerba Buena SX80: I have one question, I guess, just to toss out.

Yerba Buena SX80: not as a ecrb comment, probably not even as a geotech comment. But I think you’re classifying this as an ordinary bridge.

Yerba Buena SX80: Which means that on a major event it’s shut down for undetermined

Yerba Buena SX80: period of time. Seems like 37 being lost would be a pretty big event. I’m wondering if it needs to be higher than ordinary.

Yerba Buena SX80: That’s not a that’s not a ecrb review. You don’t really need to respond. It’s just I’m just thinking out loud.

Yerba Buena SX80: yeah, it’s well, that’s up to somebody else higher than us to determine that.

Yerba Buena SX80: Yeah,

Yerba Buena SX80: you said. I think in the foundation report that there is

Yerba Buena SX80: You’ve designed offset capacity for fault offset.

Yerba Buena SX80: What does that look like?

Yerba Buena SX80: And you have a 1.7 feet of horizontal offset, I think.

Yerba Buena SX80: How is that being accommodated in the

Yerba Buena SX80: I I think Michael Bergman would would better answer that question than than myself.

Michael Bergman, Caltrans Bridge Design: Yeah. So the fault offset is, you know, according to the report, it’s gonna happen in the transverse direction. So that’s where we’re providing that extra width on top of the bank caps.

Michael Bergman, Caltrans Bridge Design: The connection between the superstructure and the vent caps is meant to fuse at the higher offsets that we’re gonna see.

Michael Bergman, Caltrans Bridge Design: So under standard you know, earthquake displacement that we designed for

Michael Bergman, Caltrans Bridge Design: the connection between the superstructure and the drop caps would remain intact. But then, once we get above, you know that offset into the fault. Rupture offsets.

Michael Bergman, Caltrans Bridge Design: we’re gonna have that fuse, and the the superstructure is gonna be allowed to slide

Michael Bergman, Caltrans Bridge Design: where the bents you know, would have that differential offset between them.

Yerba Buena SX80: So

Yerba Buena SX80: The current revision of the Alquis Priolo map shows a a

Yerba Buena SX80: queried or hidden alignment of the actual fault, and then it gives the

Yerba Buena SX80: the hazard zone in yellow. I guess you’ve got some sort of accommodation that you’ve put in where the

Yerba Buena SX80: fault might be given the uncertainties of. I guess the Ap. Map is probably the best source right now.

Yerba Buena SX80: and you can accommodate that at

Yerba Buena SX80: any of the potential locations along there. I mean. It’s not that it’s just between Bench 3 and 4, but it might be between 2 and 3, or between 3 and 4, between 4 and 5, or I’m not sure. I mean you alluded earlier that you weren’t sure exactly where it came through here, which is fine, but at some point that if you’re trying to account for the offset. You have to know

Yerba Buena SX80: where the offset is occurring. I’m just wanting to ask that that’s been accounted for. The uncertainty and the fault alignment.

Michael Bergman, Caltrans Bridge Design: Yes, so it’s we have that extra. With that each of the peers to allow for that. Allow for that movement.

Michael Bergman, Caltrans Bridge Design: From any of the any of the peer locations

Michael Bergman, Caltrans Bridge Design: and and the goal there is to prevent any unseating of the superstructure, so it would be

Michael Bergman, Caltrans Bridge Design: be able to remain seated on top of those piers.

Michael Bergman, Caltrans Bridge Design: For any of those situations that you mentioned.

Yerba Buena SX80: Yeah, I think, in addition to that, just want to make a note that we are designing a continuous superstructure. So that it’s it’s not spam by spam, but it’s it’s continuous from apartment to apartment.

Yerba Buena SX80: And so that’ll help the continuity and and just ensuring that our superstructure is fully supported. So so as a geotech, my question is really not not trying to solve the structural issues for myself, but just to say, the offset could be here could be here could be here, could be here. Can you, with your continuous span

Yerba Buena SX80: continuous design, accommodate that offset at any of those potential locations? Yes, I I think that’s what. Yeah. And the answer is, yes, we are.

Yerba Buena SX80: I have a question then about maybe my final question here. The buoyancy of the can. I just ask a related question about the offset and go ahead. So we’ve talked about horizontal offset. I think you’ve also mentioned that there’s a potential for vertical offset as well, and understanding. It wasn’t clear to me before

Yerba Buena SX80: that

Yerba Buena SX80: the deck is intended to be continuous span to span. How does the vertical component of that get accommodated as well? Or is there a repair consideration that factors into that? If the

Yerba Buena SX80: one foot of vertical has to occur. One of the intermediate stands.

Michael Bergman, Caltrans Bridge Design: Yeah. So we, I mean, we always design, you know, for. And it’s basically a no collapse criteria, right? So we allow damage in designated spots of the bridge. Typically for a normal standard. Ordinary bridge. We’re gonna let it we’re gonna assume hinges are gonna form in the columns. But with that vertical offset you know we have to look at it

Michael Bergman, Caltrans Bridge Design: for hinging in the superstructure, and make sure that the the capacity of the superstructure can handle

Michael Bergman, Caltrans Bridge Design: any of that hinging there without having a significant, you know, collapse or anything like that. So the superstructure is being designed to handle that vertical offset which is definitely a challenge with these shorter spans, however, just based on the preliminary results that we’re looking at now, it is possible to design for that.

Yerba Buena SX80: Thank you. I see that it’s classified as a non standard bridge, which I think triggers on your end. Additional project, specific seismic design criteria and some peer review is that part of your processes ongoing as well?

Yerba Buena SX80: Yeah. So I think the bridge is really classified as ordinary non-standard. And really the non-standard aspect of it is the fault rupture. That’s the only aspect that’s I think I also saw there was some high ductility demands. Yes, so we’re yes, that’s right. So we’re able to get a design exception, increasing our ductility value from

Yerba Buena SX80: 5 to 8. And that was in consultation with our click engineering group. Okay, yeah. So we were able to. And and part of the reason is because of the probability of fault rupture occurring

Yerba Buena SX80: in conjunction with seismic. We thought it would be beneficial to allow a higher ductility value. Based on our research. We understand that really our bridges are designed to actually perform much higher than what we’re actually designing for. So so we asked for that additional

Yerba Buena SX80: higher ductility to design our bridges from, and that that approval was given by our departmental heads.

Yerba Buena SX80: So you’re considering that as as a concurrent load case of the

Yerba Buena SX80: the physical displacement offset plus yes, the site, the

Yerba Buena SX80: the the peak induced ground acceleration on the peak correct. So I think the part of the analysis is to do a ground shaking as well as a fault. Rupture combination.

Yerba Buena SX80: That’s part of the analysis that we’re actually running. Thank you. Okay.

Yerba Buena SX80: so I have a question related to the fault displacement. The fault rupture report

Yerba Buena SX80: talks about the mapping uncertainty. Yes, 43.5 meters.

Yerba Buena SX80: How is that accounted for in the design?

Yerba Buena SX80: I didn’t write that report, so I I can’t give you a firm answer. But

Yerba Buena SX80: I can always ask and try to

Yerba Buena SX80: get get more information for you.

Yerba Buena SX80: Yeah, I’d have to talk to our geologist who wrote that. Okay.

Yerba Buena SX80: yeah, I mean, I I mean, I am interpreting it as meaning that.

Yerba Buena SX80: you know, if the fault is assumed to be along a certain alignment. It could be 43 point

Yerba Buena SX80: 5 feet off.

Yerba Buena SX80: You may be right.

Yerba Buena SX80: yeah, or it could be 20 feet off either way, you know, like a instead of

Yerba Buena SX80: you could have a width of 43 feet. Yeah, or you could be 43 feet off this way or this way, exactly 80 feet. Let’s say, yeah. But somehow, how would you? If that’s the case, how would you incorporate that in your

Yerba Buena SX80: structurally? Yeah, I think I think that question goes back the other gentleman’s question, Are we design the fault rupture for each support location? And we are, so, I think, based on the fault rupture report. It’s pretty much saying that the fault is going to be under our new bridge somewhere along, you know, within the entire width of sorry, entire length of our bridge, and it says that it’s perpendicular. I believe we’re pretty close to being perpendicular, so we are designing all of our

Yerba Buena SX80: bridge element to withstand at every single support location. Yeah. So if that fall rupture, let’s say, happens between Piers 6 and 7, we’re kind of for or between peers or apartment one and

Yerba Buena SX80: sorry about my 2, then it’s also being accounted for. So, anyway, in between what about the abutment, though, I mean, you know, it could be

Yerba Buena SX80: beyond the abutness

Yerba Buena SX80: on the other side, too, if it’s beyond the bomb, and then it’s just in the approaches. So it’s not, you know. That’s that’s something on the roadway side.

Yerba Buena SX80: We don’t usually account for that on the bridge side, but we.

Yerba Buena SX80: you know, if and we do have an approach lab just to let you know. I believe we have a 30 foot approach lab on each side, and hopefully, that provides some sort of a ramp. Typically, if that material. The approach fill does settle. Beyond that. I think it’s kind of a roadway prism. So we don’t handle that from a structural perspective or a bridge perspective.

Yerba Buena SX80: Okay?

Yerba Buena SX80: But I think I think in that report it does define that the fault rupture is occurring under the limits of the new proposed bridge. I believe.

Yerba Buena SX80: I believe that’s how it’s stated in that report.

Yerba Buena SX80: Well, I mean, it’s it kind of puts in this thing about uncertainty. So

Yerba Buena SX80: it’s basically it could be 43.5 meters off. Still, meters or feet meet us.

Yerba Buena SX80: Hmm.

Yerba Buena SX80: should we move on to the hydraulics portion? Yeah. Okay. One pretty minor comment. I think. Somewhere in the text you talk about

Yerba Buena SX80: stiff to hard clay soil, with a few layers of medium dense to very dense sand

Yerba Buena SX80: parenthesis Consolidated Bay mud, I think

Yerba Buena SX80: Consolidated Bay mud is probably an unusual terminology for the material that underlies the younger Bay mud. It’s just older alluvium.

Yerba Buena SX80: You’d always use the vernacular. Older Bay mud was older bay mud, older bay mud, or older bay clay has a specific designation that’s a very fine grain uniform, right pretty clean silty, you know. Very silty clay

Yerba Buena SX80: that’s different than all of the sandy, yellowish brown material that you’ve been describing here. And it I don’t think that what you’ve described, or what you’ve encountered, is consistent with what is normally termed

Yerba Buena SX80: Old Bay Clay or Old Bay mud. Well, we can always change the descriptions

Yerba Buena SX80: we can also rule that out with using select, too, in

Yerba Buena SX80: using the Cpt data, we can look at that more, if need be. It’s just that when you have old bay clay is typically a dark, bluish gray. Yeah.

Yerba Buena SX80: uniform, pretty uniform clay, silt, silty clay. And I think that what you’ve described here is not really that. I think it’s a different formation.

Yerba Buena SX80: So check with the geologist. Maybe. Yeah, we’ll check and see it. It doesn’t necessarily affect the design. I hate to say this, but we were doing most of this at night.

Yerba Buena SX80: Little bit dark. Well, if that’s true, then you need to re-log it in the daylight and get the colors correct.

Yerba Buena SX80: We couldn’t drill during the day. I understand that, but you need to reopen your samples during the day. We can always do that. If that’s an issue, you need to get the colors right? Yeah, I mean, it makes a difference, just because it can make a difference. Yes.

Yerba Buena SX80: I think these are older alluviums, not

Yerba Buena SX80: old baked clay per se. Okay, anyway, I’ll check with our geologists. Yeah. So that that’s a minor question. I’m kind of intrigued, though, if you go back, I think it’s slides 12 and 13. You have some stuff about the Eps.

Yerba Buena SX80: yeah. So go.

Yerba Buena SX80: Let’s see, I think I think slide 12. Maybe

Yerba Buena SX80: it’s gonna have. There go. We have some pictures of the Eps there the blocks, and I’m trying to understand the dimensions on this. If you’re putting

Yerba Buena SX80: expanded polystyrene Styrofoam in there. It

Yerba Buena SX80: It’s a little bit buoyant. Right it weighs, it weighs between half and 2 pounds per cubic foot.

Yerba Buena SX80: And it’s got substantial

Yerba Buena SX80: compressibility also. And I’m not. I’m I’m trying to understand in this cross section. Where is groundwater? Where is bay water? You know you’re not. I mean, it looks kind of like you’re placing this down pretty close to to tidal depths.

Yerba Buena SX80: It it it doesn’t show it in that figure. But what we can do is we can. We can show in a

Yerba Buena SX80: subsequent figure that we can accommodate any

Yerba Buena SX80: any changes in groundwater by using a lightweight aggregate under that.

Yerba Buena SX80: and then we could the rest. We could place either lightweight, sailor concrete, or or the Eps block

Yerba Buena SX80: and then on the next stay next slide. I think you have an interesting

Yerba Buena SX80: Eps parameters. Phi equals 27. Gamma equals 35. I know somewhere you have an explanation that says this is a composite weight, counting the Eps plus the soil above it.

Yerba Buena SX80: A little bit of a interesting non standard.

Yerba Buena SX80: Type of description. Eps doesn’t really have a fee angle, whatever the strength is, is kind of a funny, compressible, soft phenomenon. I know, Caltrans, you guys have used Eps a lot.

Yerba Buena SX80: It’s pretty compressible. If you have a big, thick layer, maybe if it’s down deep enough. Your pressure bulb spreads everything out enough. But

Yerba Buena SX80: You know I’ve looked at trying to put this under caltrain rail, and if you have, you know, 30 feet embankment. You’ll get a 4 inch compression every time the train goes over it. Sure. So I assume you guys have done this enough. You’re you’ve you’ve figured out the compressibility

Yerba Buena SX80: the compressibility, for one thing, but also the constructability is where I was looking for. There.

Yerba Buena SX80: That says, you know, if it rains the stuff float. If you fill up your excavation hole, if the tide comes in, if you have a king tide

Yerba Buena SX80: every everything floats

Yerba Buena SX80: Just wanted to make sure you guys got all that?

Yerba Buena SX80: Yeah, I I understand what you’re saying. Right now, we’re still design in design

Yerba Buena SX80: that that’s more of a concept. Right now, I think we need to

Yerba Buena SX80: go back and and look at. Look at how things are gonna perform. Like I said, I I think the lightweight aggregates gonna be

Yerba Buena SX80: part of the composite that we’re gonna put behind those retaining walls. In addition to like, I said, lightweight aggregate being 70 pounds a cubic foot, or something like that. Something like that. Yeah, dry density. Yeah. Which a wet density is

Yerba Buena SX80: 30 pounds higher than that right? So that’s gonna it’s gonna change with with the change in the elevation of the groundwater. Right?

Yerba Buena SX80: And that’s going to accommodate that that rise and fall. Okay, so this is pretty conceptual at this point, it’s more conceptual. Anything to add, Peter.

Yerba Buena SX80: yeah, we’re still looking at how much power we will have, and how much sickness will be required. Yes, we’re still doing that right now. Just say either Eps blocks or lightweight shell or concrete something like that. And this Phi and C is just used for calculating Earth pressures. That’s average you will consider for planning, but it’s used in calculating Earth pressures. I guess

Yerba Buena SX80: I can use it. Yes, I already. Why, you even give a fee angle or a

Yerba Buena SX80: for for this purpose. Yes, what’s what’s listed here on? This is the pressure for the retaining wall. Yes.

Yerba Buena SX80: and I’ll just remind them to take sea level rise into account in your groundwater levels for the life of the project.

Yerba Buena SX80: Yeah, I’m done.

Yerba Buena SX80: Okay. Another question. As long as we’re talking about the the abutments there and the foam. Can you describe one more time how the fault displacement is being accommodated. I heard you say that there’s extra width in the pile caps.

Yerba Buena SX80: Is there? Is there a joint at at the abutments

Yerba Buena SX80: between the deck and the abutment. Is that where that’s being accommodated? Or can you describe, you put the picture of the abutment back up, or or the elevation of the bridge.

Yerba Buena SX80: maybe the one

Yerba Buena SX80: or or the plan of the bridge. Yeah, that’s a good one, either of those 2. How? How? Where? Where is that being accommodated.

Michael Bergman, Caltrans Bridge Design: Yeah. So the abutments are seat type abutments. And there’s

Michael Bergman, Caltrans Bridge Design: I I think I also didn’t mention there’s a extra width at the buttons as well for the bridge to be able to slide transversely.

Michael Bergman, Caltrans Bridge Design: So at the abutments it sits on top of the bearing pad.

Michael Bergman, Caltrans Bridge Design: Just a typical seat, and then on the bank caps. There’s a joint between the drop cap and the if we go to the previous slide, Javier.

Michael Bergman, Caltrans Bridge Design: You can see it uses a drop cap where the continuous superstructure sits on top, and then there’s there’s gonna be dowels between the drop cap and the superstructure that will fuse

Michael Bergman, Caltrans Bridge Design: at higher, higher displacements.

Yerba Buena SX80: So when you say extra width, the so in the transverse to bridge direction

Yerba Buena SX80: the pile, the drop caps are are wider than the superstructure by 1.7 feet, or whatever, so that the abutment can move relative to the bridge deck. Once those dowels fuse. Is that what you’re saying?

Michael Bergman, Caltrans Bridge Design: Yeah, that’s correct. So the the drop caps and the abutments, are one foot 8 inches wider than

Michael Bergman, Caltrans Bridge Design: than the superstructure. So it would allow for that extra seat with for it to slide.

Michael Bergman, Caltrans Bridge Design: for the the peers, you know.

Michael Bergman, Caltrans Bridge Design: Say the fault rupture happens right in the middle of the bridge for half the peers to shift that one foot 8 inches without without having any issues.

Yerba Buena SX80: And are there dowels at the abutments, or only at the intermediate fence?

Michael Bergman, Caltrans Bridge Design: There’s only dowels at the bench, at the piers. So at the abutments they’re sitting on top of bearing pads, so it’s free to slide.

Yerba Buena SX80: Okay. So if if movement happens in the longitudinal to bridge direction, what keeps the the bridge deck on the abutment.

Michael Bergman, Caltrans Bridge Design: So in the longitudinal direction. The only displacement that we’re looking at is for just a standard earthquake.

Michael Bergman, Caltrans Bridge Design: So in that direction the dowels that we’re designing are not? They’re not going to fuse

Michael Bergman, Caltrans Bridge Design: so just it would behave like a standard. Ordinary bridge.

Yerba Buena SX80: Okay. So the dowels only fuse in the transverse direction.

Michael Bergman, Caltrans Bridge Design: Yes, so the fault rupture report

Michael Bergman, Caltrans Bridge Design: shows that the the rupture is in the would be in the transverse direction.

Yerba Buena SX80: Okay. And what capacity do those fusing dowels have in the transverse direction after they fuse? Do they literally break? Or do they have a residual shear capacity.

Michael Bergman, Caltrans Bridge Design: No, once they break, there’s no, there’s no additional capacity. So you know there could be a repair done where you come in and you know, dial back into the supports

Michael Bergman, Caltrans Bridge Design: through the deck.

Yerba Buena SX80: Okay. So once once dowels, let’s say the the fault happens in the middle of the bridge.

Yerba Buena SX80: half of the bridge becomes disconnected from the abutments, and those abutments are presumably wide enough that it won’t fall off.

Michael Bergman, Caltrans Bridge Design: Yes, beyond that one foot 8 inches we have sheer keys in place to

Michael Bergman, Caltrans Bridge Design: so hold the superstructure in place like a how we would for our standard bridges.

Yerba Buena SX80: Okay, thank you.

Yerba Buena SX80: Okay.

Yerba Buena SX80: and and thank you for answering all our questions.

Yerba Buena SX80: Our pleasure.

Yerba Buena SX80: Alright. So Brad or Gary.

Gary Sjelin, Caltrans: Hello! Gary, shalin with a com and the hydraulic study aecom. Prepared a 2D heckras model of the

Gary Sjelin, Caltrans: To Lake Creek area, the, in fact, the entire marsh upstream north of Sr. 37

Gary Sjelin, Caltrans: and the lagoon downstream of the bridge.

Gary Sjelin, Caltrans: the bridge not being exactly on San Pablo Bay. It is some distance inland.

Gary Sjelin, Caltrans: the the modeling that we did included Sonoma Creek as well, and the Napa River. The 2D modeling did not cover the entire watershed of

Gary Sjelin, Caltrans: Napa or Sonoma. We developed

Gary Sjelin, Caltrans: hydrographs for those watersheds and input those into the 2D models at the marsh limits. Roughly, the 2D model did cover the entire Toloy Creek watershed, including the lake in the very upper part of the watershed that reduces some flow down

Gary Sjelin, Caltrans: to the marsh.

Gary Sjelin, Caltrans: We found that there’s a significant peak reduction and totally creek flow at the railroad bridge roughly, and the peak flows, dissipate rapidly as it enters the marsh before it gets to the Tolay Creek Bridge. So the bridge design winds up being largely a tidally influenced design.

Gary Sjelin, Caltrans: I think we could probably. Oh, cross sections here. It, figure 29 is taken from our report. That’s the existing bridge section, roughly 60 foot long bridge structure.

Gary Sjelin, Caltrans: With the existing ground survey below that the opening, and then we have the wider 375 foot long bridge structure. In the lower right. This was based on preliminary

Gary Sjelin, Caltrans: bridge design

Gary Sjelin, Caltrans: When we did, the modeling

Gary Sjelin, Caltrans: and the structural design has evolved a bit since then. But since the superstructure of the bridge is above the high water mark. It doesn’t affect the hydraulic analysis. So we, this is still useful in determining maximum water surface elevations and free board at the bridge. Okay, let’s move on

Gary Sjelin, Caltrans: sea level rise. Question our our modeling. We. We looked at that 12 different scenarios for existing condition

Gary Sjelin, Caltrans: for future condition or post project condition, and then for future condition that would include sea level rise.

Gary Sjelin, Caltrans: none of the analysis that we did in the 2D model included future Mars restoration. That might be a question for that. We relied on the previous

Gary Sjelin, Caltrans: Marsh Restoration report that was prepared by Esa to give us an idea of what some future Marsh Restoration project might look like. But it was not included. As part of our analysis here.

Gary Sjelin, Caltrans: So for that future condition that we’re designing to

Gary Sjelin, Caltrans: we need to consider sea level rise and there was a significant change in California guidance on sea level rise from 2018 to 2024. We’re using the 2024 guidance now,

Gary Sjelin, Caltrans: and the previous lifespan of the bridge was

Gary Sjelin, Caltrans: determined to be 2046 20 years after a 2026 completion date.

Gary Sjelin, Caltrans: That’s how that number was arrived at so we interpolated between the 2040 elevations and 2015 to determine

Gary Sjelin, Caltrans: sea level rise. In addition. At at the 2050. I I will say that now it seems that we are moving more towards a 2050.

Gary Sjelin, Caltrans: But

Gary Sjelin, Caltrans: timeframe for the bridge life rather than 2046 as we assumed in the design report.

Gary Sjelin, Caltrans: But for a 2050 sea level rise we can see from this table, from the California State guidance. That

Gary Sjelin, Caltrans: sea level may be as low as point 5 feet, or as high as 1.3 feet.

Gary Sjelin, Caltrans: and depending on different forecasts of what the future might entail. For

Gary Sjelin, Caltrans: design you have to select. Do a risk analysis on your structure and determine if it’s low, intermediate, low, intermediate, intermediate, high or high. Based on the guidance.

Gary Sjelin, Caltrans: we’ve selected the intermediate range. So we’re talking about A sea level rise between point 6 in 2040 and point 8 in 2050 the intermediate is considered

Gary Sjelin, Caltrans: most likely sea level rise. That terminology is used for that condition. And

Gary Sjelin, Caltrans: The determination of risk is largely based on the lifespan, and that’s where a low level of risk is associated with this project because it is expected to have a short life and be replaced. And therefore that’s where the intermediate selection for a more typical bridge that would have a longer life. You might move up to the intermediate high or even high

Gary Sjelin, Caltrans: levels. But when discussions with Caltrans we’ve

Gary Sjelin, Caltrans: zeroed in on the intermediate and a 2050 date of 0 point 8 sea level rise. In the

Gary Sjelin, Caltrans: information to the left of the table. Here, we show that we are basically starting with a 9.9 100 year maximum water surface elevation. And that is.

Yerba Buena SX80: Can we go? Sorry. Can we go back a little bit on the sea level rise since? I think some of

Yerba Buena SX80: what you have is potential like misinformation a little bit.

Gary Sjelin, Caltrans: Okay.

Yerba Buena SX80: Yeah. Group. Yeah. So,

Yerba Buena SX80: yeah. Point 8 would be the likely value for 2050.

Yerba Buena SX80: But the low and the intermediate low, are extremely unlikely to occur.

Gary Sjelin, Caltrans: Agreed.

Yerba Buena SX80: Yeah. So it’s it’s either gonna be intermediate or higher, that value. And you don’t select.

Yerba Buena SX80: You’re kind of talking about a timeframe to select for the lifespan of the project, and intermixing that with risk across intermediate intermediate, high and high. So you would think about the importance or criticality of your bridge to select between intermediate intermediate high and high

Yerba Buena SX80: and that’s independent of the lifespan of your bridge. So, by selecting intermediate and 2050 which I know you selected 2046, and earlier. Someone said they were hoping

Yerba Buena SX80: to complete the long term project by 2050, which makes me think that it’s

Yerba Buena SX80: Not likely. And I know it’s gonna be expensive. So it’s hard to say, like, these assumptions would point to a a non-critical structure. If you’re selecting the intermediate and at at 2050, so does that sound.

Yerba Buena SX80: It’s a non, I know from the geotech. It’s also a an ordinary bridge, so does that allow it to fall into that.

Yerba Buena SX80: It’s not a critical structure.

Gary Sjelin, Caltrans: Yes,

Gary Sjelin, Caltrans: My idea is that the the risk assessment level, which is part of the analysis necessary to determine the the appropriate

Gary Sjelin, Caltrans: sea level rise for design based on the State guidance.

Gary Sjelin, Caltrans: Does consider.

Yerba Buena SX80: The State guidance lists, critical transportation corridors, recommending using high.

Yerba Buena SX80: That’s what’s in the State guidance.

Gary Sjelin, Caltrans: Yes, agreed, for for a typical

Gary Sjelin, Caltrans: highway design bridge, which has a a longer life than 20 years expected, typically and.

Yerba Buena SX80: Again, you’re we’re mixing up lifespan and criticality, which are different things. Just you consider those completely, separately.

Gary Sjelin, Caltrans: Well,

Gary Sjelin, Caltrans: If I could read a statement from the guidance.

Gary Sjelin, Caltrans: Therefore, if an adaption action is part of a short lifespan adaptation pathway, a development type that might otherwise fall into a higher risk. Aversion category could be considered low risk. In this situation low aversion projects could be resilient or resilient to the intermediate scenario.

Gary Sjelin, Caltrans: for an adaptive short lifespan in the range of 2050 to 2075. That’s from the guidance for the low risk aversion

Gary Sjelin, Caltrans: in.

Yerba Buena SX80: And I would assume they are not talking about a highway.

Gary Sjelin, Caltrans: Well, it does mention

Yerba Buena SX80: There’s not a lot of difference between the values of point 8 and 1.3. So it is kind of semantics. But it’s.

Gary Sjelin, Caltrans: Well, yes. Yeah.

Yerba Buena SX80: Throughout the throughout the analysis and the report, it consistently airs on the low end of all numbers, which is why

Yerba Buena SX80: I’m just bringing this up, that it’s just the selection of point 8 rounding it down to point 7,

Yerba Buena SX80: I think just might underestimate the criticality and importance of this structure, because it is important enough that we are building a temporary bridge to build a temporary bridge to get to a long term solution, which to me points to the fact that this is really an important project for this corridor.

Yerba Buena SX80: Yeah, could I? Could I jump in? I you know, Chris, I thought those were really good comments. And I

Yerba Buena SX80: I agree with you.

Yerba Buena SX80: which leads me to to my question. I have kind of 2 basic questions while we’re on this

Yerba Buena SX80: is it. Could you raise the

Yerba Buena SX80: bridge a foot or 2 or no in your design? Could it be constructed a foot or 2 higher or no, not without significant railroad work. So that’s really the constraint is matching grade, vertical grade, vertical curve with the railway?

Yerba Buena SX80: What about raising?

Yerba Buena SX80: What about raising 6 inches? Which is what Chris is talking about, that if you use high for 20,

Yerba Buena SX80: 47, or whatever you’ve got

Yerba Buena SX80: high at 2050 would be 1.3 instead of point 7. If you round it down to

Yerba Buena SX80: the year 2047, then maybe 1.3 becomes 1.2 instead of point 7 so 6 inches

Yerba Buena SX80: 6 inches still doesn’t fit with smart

Yerba Buena SX80: yeah, or even just making it clear in the the hydraulic report.

Yerba Buena SX80: What the maximum elevation is that can be achieved based on the constraints.

Yerba Buena SX80: So that you’re making it clear. It’s not based on necessarily a sea level rise number or a water level. But for this project you have a significant constraint, and then making it clear what that maximum

Yerba Buena SX80: kind of elevation is. That’s possible that I think would would be a better way, I think, to

Yerba Buena SX80: to document and defend the number.

Yerba Buena SX80: I think these are all really good points, and I’m I’m thinking Gary is probably gonna get to the second half of the project. Assumptions.

Yerba Buena SX80: what those will kind of spell out is the assumptions that made by the project would actually accommodate the higher sea level, rise even the high of 1.3 there they started with that maximum water elevation of 9.9 feet, and our current mean higher high water out there is 6.4 2 right? So if we take that existing.

Yerba Buena SX80: add the Opc guidance of 1.3.

Yerba Buena SX80: Just the projects assumptions alone already accommodate that. And then they’ve taken wave height into that as well. So I think we want to clarify, because I agree with what you’re saying about the report. And I I completely agree it wasn’t.

Yerba Buena SX80: It should have assumed the higher level, I think. But I also believe that the project assumptions.

Gary Sjelin, Caltrans: We should move up to the interim high level? Or are you just saying that we should move up to 2050.8.

Yerba Buena SX80: I’m saying that what was assumed to define the project soffit elevation already accommodates high.

Yerba Buena SX80: Yeah, if I could jump in, I think this is a really important discussion, and I

Yerba Buena SX80: sorry to interrupt your presentation, but I think this is

Yerba Buena SX80: important for us to get out before we run out of time.

Yerba Buena SX80: So I think that the point that Chris made was where I was gonna go. Is that really what’s constraining? This is the matching the grade at the railway.

Yerba Buena SX80: and you got the numbers to work. But you made some what I would consider non-conservative assumptions about sea level rise, design criteria.

Yerba Buena SX80: and that’s what Chris is reacting to. And I agree. I agree with her on that

Yerba Buena SX80: and maybe that being.

Gary Sjelin, Caltrans: Selection of intermediate for the sea level as opposed to the 2046, 2050 controversy.

Gary Sjelin, Caltrans: I think it’s yeah.

Gary Sjelin, Caltrans: The interim high.

Yerba Buena SX80: The selection of the intermediate scenario, instead of intermediate high or high scenario, is dubious, in our in my opinion.

Yerba Buena SX80: For a structure like this, and I think

Yerba Buena SX80: that it’s not like you don’t believe in sea level rise, or anything, or necessarily misinterpreted the guidance. I think you had to match grade at the railway, and that’s what I’m trying to understand.

Yerba Buena SX80: Fair.

Gary Sjelin, Caltrans: Yeah, yes. So we do have the constraint to the railroad. And we do have the

Gary Sjelin, Caltrans: unusual short life span of the bridge in the factor. And again I go back to the guidance which says additionally, the lifespan of a project or adaption action is a major factor in its risk profile. So it is a consideration in my mind. And again, but again, it’s very subjective whether or not.

Gary Sjelin, Caltrans: thank you.

Gary Sjelin, Caltrans: Intermediate or intermediate. High should be used but it it is a factor in the analysis.

Yerba Buena SX80: Yeah, that’s significant.

Gary Sjelin, Caltrans: Factor. It seems.

Yerba Buena SX80: I don’t think we want to get into an argument. I think we want to have a discussion. And I think we’ve we’ve covered this. I think there are other factors which I think we should get to before we.

Gary Sjelin, Caltrans: Well, yeah. Beyond this, again, we have moved into

Gary Sjelin, Caltrans: using the point 8 rather than the 0 point 7 but that, again, is based more on the 2050 date as opposed to a shift towards interim high.

Gary Sjelin, Caltrans: Okay? And.

Yerba Buena SX80: Thank you for that. I. The point one foot makes a difference. If I could ask some questions, is that okay?

Gary Sjelin, Caltrans: Okay. Sure.

Yerba Buena SX80: Or do you? I mean, do you feel like you’ve not answered my question about the

Yerba Buena SX80: the railway being a constraint, I I don’t want to cut you off, but it seems like we’ve we’re kind of go going over things more than once.

Yerba Buena SX80: can I can. I just ask real quick just on that point is, is the bridge as high as it can possibly be given that constraint like, is there another inch or 2 that you haven’t

Yerba Buena SX80: taken advantage of.

Gary Sjelin, Caltrans: Is that directed at me, or.

Yerba Buena SX80: Whoever knows the answer.

Gary Sjelin, Caltrans: I I will defer

Gary Sjelin, Caltrans: to other members of our team who set the profile of the bridge and the constraint on the

Gary Sjelin, Caltrans: the vertical.

Gary Sjelin, Caltrans: I just set the water surface.

Yerba Buena SX80: We’ve maximized the vertical elevation without doing any track work. It’s as high as it can go. Okay, thank you. Yeah. Thank you. Thank you for that clear answer. I appreciate it. And and, by the way, I think it’s great that Caltrans is looking at State Route 37, and I think it’s

Yerba Buena SX80: It’s nice to see the bridge being raised and the ecology and habitat being improved. So

Yerba Buena SX80: we’re just trying to get into the criteria and sea level rise criteria, which is our job.

Yerba Buena SX80: I was a little confused about the term soffit, and where the free board is measured to and from

Yerba Buena SX80: or 2, I guess, to the top

Yerba Buena SX80: the soffit I usually assume is the bottom of the deck, and that maybe that’s a a pier or wharf kind of thing, but

Yerba Buena SX80: I think the free board is measured to the

Yerba Buena SX80: top of the pile cap or the the beam. The transverse beam above the piles is but below the girders. Is that is that right?

Yerba Buena SX80: And the reason why I’m asking is because if the free board isn’t sufficient or the water level goes higher than the elevation.

Yerba Buena SX80: then I think the water is against the girders, which means that there’s an increased load

Yerba Buena SX80: lateral load in the direction of flow. So I was just trying to understand that the

Yerba Buena SX80: you know, there’s a statement that the soffit elevation is 12.6 or higher

Yerba Buena SX80: Navd and I just was wanted to be clear is that the bottom of the deck or the top of the

Yerba Buena SX80: pile cap theme.

Gary Sjelin, Caltrans: That’s the bottom of the deck at the

Gary Sjelin, Caltrans: The lowest point of the deck, which tends to be not at the profile grade the center line of the road, but at the face of the bridge, either upstream or downstream, depending on the width and the cross slope of the bridge.

Gary Sjelin, Caltrans: which you know, tends to lower the grade from the profile grade of the bridge. So yes, the free boards measured from the low cord of the bridge that extreme low elevation, and in this case our bridge does slope up from the west end to the east end. So we do have more free board provided at the east end of the bridge, the critical point being the

Gary Sjelin, Caltrans: the bottom of the bridge deck superstructure at the west end of the bridge above, up one.

Yerba Buena SX80: Okay, so, but but the free board is is not measured to the soffit.

Gary Sjelin, Caltrans: To the software. Well, the bottom of the deck versus the.

Yerba Buena SX80: Bottom of the girders, which is.

Gary Sjelin, Caltrans: I don’t know.

Gary Sjelin, Caltrans: Well, we have slab girders.

Gary Sjelin, Caltrans: our slab deck and and that’s what we’re measuring from structures. Yeah.

Yerba Buena SX80: Oh, you don’t have girders. You have a a like a box girder deck. Okay, I’m sorry that maybe that’s why I was confused. So it’s really the top of the transverse beam. The pile cap

Yerba Buena SX80: is what we’re talking about when we talk about so soffit or free board.

Gary Sjelin, Caltrans: Right free board is not measured to the bottom of the pile cap the either the girders or the the box girders of the bridge are supported on the pile cap, and it’s that

Gary Sjelin, Caltrans: longitudinal surface on the bottom of the bridge that’s considered the low court of the bridge. That we measure preport to.

Yerba Buena SX80: Okay, so the soffit and the top of the pile caps are the same thing. Thank you. I I think I got that. Some of the drawings showed curves.

Yerba Buena SX80: so what are the implications of the water level being higher than the criteria that you have.

Gary Sjelin, Caltrans: Well, let’s run through the the numbers here a bit for a second. We’re starting with

Gary Sjelin, Caltrans: a 9.900 year maximum water surface elevation which includes surge the bay. It’s basically the water surface elevation of San Pablo Bay. It’s not the elevation at the bridge which tends to be slightly lower because of the losses that take place as flow goes through the lagoon downstream and the channel. But because of the uncertain

Gary Sjelin, Caltrans: restoration project of the future. We opted to just go with the the elevation of the bay as the controlling water surface, even though our previous hydraulic modeling said it might be lower because of the losses through the lagoon.

Gary Sjelin, Caltrans: so 9.9 is our starting water surface. And again, that’s taken from an ae Acom, 2,016. Analysis of the entire San Francisco Bay to establish extreme high waters. It includes surge. It does not include wave heights. We add a 1 foot wave crest to that

Gary Sjelin, Caltrans: above that still water elevation. That’s not the total wave height. That’s just the elevation from the Stillwater to the crest of the wave, and then we add

Gary Sjelin, Caltrans: point 7.8

Gary Sjelin, Caltrans: 1.0 sea level. Rise to that, and then we’d like to achieve a 1 foot free board above that to the low court. And that’s how we’re setting the minimum soffit elevation of the bridge. And it in in these numbers here. We’re still using the 0 point 7 2046 number for intermediate risk level. And

Gary Sjelin, Caltrans: that set the soffit at 12.6 the current soffit at the west end, the the low cord

Gary Sjelin, Caltrans: of the bridge deck.

Gary Sjelin, Caltrans: The flat surface on the bottom of the bridge.

Gary Sjelin, Caltrans: That is at elevation 12.8

Gary Sjelin, Caltrans: so we have actually not one foot of free board. We have 1.2 feet of free board based on the point 7.

Gary Sjelin, Caltrans: If if we bump it up and say, okay, it could be point 8, then we’ve got 1.1. We still have more than the one desired.

Gary Sjelin, Caltrans: We could go up to point 9 and still meet the desired free board of one foot

Gary Sjelin, Caltrans: and at the east abutment rather than 1.2 feet of freeboard. I’m going back to the 0 point 7 foot sea level rise. We have 2 feet of freeboard. On the

Gary Sjelin, Caltrans: east end of the bridge. So

Gary Sjelin, Caltrans: Considerably more

Yerba Buena SX80: And I think it would be really helpful in the report

Yerba Buena SX80: to present it that way. That

Yerba Buena SX80: your actual soffit top of pile cap elevations are.

Yerba Buena SX80: you know, 12.8 at that lowest member

Yerba Buena SX80: and then show that you can meet up to X amount of sea level rise instead of trying to like, build up with point 7. Since sea level rise

Yerba Buena SX80: or the water levels any of the different water levels you’re looking at are not like the primary design factor. It’s really that constraint of the rail. And you have the design. And it’s kind of showing what you’re able to accommodate, I think, would make it

Yerba Buena SX80: It would make it a I think, a stronger report or a stronger defense for the approach.

Yerba Buena SX80: I also just wanted to comment, and I’m you might be covering this on later slides. I think that the

Yerba Buena SX80: the one foot wave crest is taken from the fema study, basically in part.

Yerba Buena SX80: Okay? So the in some of the Fema transect modeling over the marsh.

Yerba Buena SX80: it will list it instead of an ae 10, it’ll list it as an ae 11

Yerba Buena SX80: and so that’s where it’s not clear in the report, but that’s where I was thinking you were getting, you could have a 1 foot wave on top of that 1% still water elevation. But that’s actually not the way that ae 11 was calculated. If you look at all of the background information that’s

Yerba Buena SX80: with the fema study, and I know I saw in the this is a draft of the report, and it hasn’t been like signed and reviewed by Justin. And I think Justin Vandiver would catch that, since he and I worked together on this fema study. So we’re very familiar with all of that analysis.

Gary Sjelin, Caltrans: Yes, the the base flood elevations on the firm show

Gary Sjelin, Caltrans: elevations ranging from 10 to 11 and 12 throughout

Gary Sjelin, Caltrans: the marsh area. The project area. And at

Gary Sjelin, Caltrans: Surprisingly odd locations, I guess one might say on on. Why,

Gary Sjelin, Caltrans: In some cases elevations got up to 12 versus 11. In one area or 10. The base flood upstream of the bridge under existing conditions is 10

Gary Sjelin, Caltrans: and 11 on the downstream side.

Gary Sjelin, Caltrans: a little farther to the east that bumps up to 12

Gary Sjelin, Caltrans: and a lot of that is consideration of the

Gary Sjelin, Caltrans: The potential wave heights the fetch length whether or not levees are overtopped or not.

Gary Sjelin, Caltrans: how sheltered they are! By levees!

Gary Sjelin, Caltrans: The yeah.

Yerba Buena SX80: Not. Marsh can help dissipate the wave energy or whether it’s you know, deep enough that waves can regenerate. Yeah, that’s why it

Yerba Buena SX80: yeah, may look. It’s also

Gary Sjelin, Caltrans: Well the depth. I’m sorry I didn’t follow that. What was the.

Yerba Buena SX80: Oh, the the wave analysis over all those transects also considered like marsh vegetation, and how that could dissipate wave energy, or if you had deep enough water to like regenerate waves.

Yerba Buena SX80: I would also highlight that it’s

Yerba Buena SX80: based on historical conditions between 1973 and 2,004. So it’s not really representative of like today’s conditions. We saw much stronger winds, bigger waves in 2022, 2023 in a lot of places. So it’s

Yerba Buena SX80: it’s hard to rely on

Yerba Buena SX80: flood insurance rate maps for design, and especially design criteria. But yeah, and just wasn’t

Yerba Buena SX80: sure where the one foot wave crest.

Yerba Buena SX80: How that was defined

Yerba Buena SX80: I and my assumption was, it was taken from like the fema maps between the Ae. 11 and the ae 10.

Gary Sjelin, Caltrans: We did do some wave fetch analysis. In fact, we’re it’s still ongoing along the whole project to determine how much

Gary Sjelin, Caltrans: rock, slope, protection or other erosion control measures are necessary along the roadway, not just at the Lake Creek bridge. So yes, we have calculated wave heights along there, and they are

Gary Sjelin, Caltrans: coming up between one and 2 feet typically and for this analysis that seemed to

Gary Sjelin, Caltrans: correspond well with Fema’s previous assumption of bumping up a 10 base flood elevation to 11 in the neighborhood of the bridge.

Gary Sjelin, Caltrans: Again, it’s

Gary Sjelin, Caltrans: little different with sea level rise, considerations when depths increase and waves that might have break broke in shallow water can continue further inland.

Gary Sjelin, Caltrans: so that that all plays into the analysis. But we we have

Gary Sjelin, Caltrans: perform some of that analysis again, much of it’s subjective.

Yerba Buena SX80: That’s that’s great, though. I’m glad that that’s being looked at. Yeah, it just wasn’t documented in this in the report that we had to review. But yeah, fema did county wide studies, so they were not, you know, extremely detailed. The transects are pretty far apart, so it’s good to know that you’re doing more more detailed analysis of the corridor and not just simply relying on Fema. So that’s great.

Gary Sjelin, Caltrans: Okay?

Gary Sjelin, Caltrans: So shall we continue then, with the

Gary Sjelin, Caltrans: or you want to stay on the sea level, rise, discussion or.

Yerba Buena SX80: Yeah, I hadn’t finished my comments. But why don’t you go ahead and make your present complete your presentation, and we’ll get into it. After that.

Gary Sjelin, Caltrans: Backtrack a bit. Yeah, down the road. Let’s

Gary Sjelin, Caltrans: I think we beat this one to death. Let’s move on to the next slide.

Gary Sjelin, Caltrans: These are our future condition. Model scenarios.

Gary Sjelin, Caltrans: again, this is largely based on caltrans criteria

Gary Sjelin, Caltrans: in the highway design manual. There is a figure that shows that the north coast of San Pablo Bay is in a province that should be based on a design, or should be designed based on the Pinole Point gauge, which is on the south side of the bay.

Gary Sjelin, Caltrans: and so in this analysis we were using those number numbers for mean high high water and mean sea level, and then adding a 2 foot surge to that

Gary Sjelin, Caltrans: and then adding point 7 foot sea level, rise on top of those numbers.

Gary Sjelin, Caltrans: there’s another figure within the highway design manual that suggests that

Gary Sjelin, Caltrans: to determine a 100 year event. You don’t necessarily take 100 year rainfall and make it concurrent with the worst case. Extreme high tide. That’s a greater than 100 year event. So for 100 year. Precipitation we

Gary Sjelin, Caltrans: match the peak flow into Lake Creek with mean sea level level.

Gary Sjelin, Caltrans: and consider that combination of events 100 year event, and then for

Gary Sjelin, Caltrans: a 50 year precipitation. We consider that against a mean high high water elevation, starting point, or

Gary Sjelin, Caltrans: coincident elevation, and that is, even though it’s 50 year precipitation considered a hundred year event.

Gary Sjelin, Caltrans: and then for no precipitation, you might have extreme high water, 7.1 2, and that is a hundred year events. So there’s 300 year events that we look at based on different combinations of precipitation and tide levels. And then we do a 50 year analysis as well, the 50 year being the mean sea level, and

Gary Sjelin, Caltrans: the scenarios are similar for existing condition, but without the sea level rise and then post project conditions. Similar to the existing but change in bridge length in the analysis. And then for scenarios 9 through 12. That’s where we add in sea level, rise on the new bridge structure.

Gary Sjelin, Caltrans: So that’s a quick synopsis of the the 12 scenarios that were looked at in the 2D Hec Ras modeling but again pretty much all superseded by our later analysis of just going with

Gary Sjelin, Caltrans: the extreme high water in San Pablo Bay,

Gary Sjelin, Caltrans: And making sure that we have enough free board above that elevation, with sea level, rise and wave action.

Yerba Buena SX80: Can I just ask a clarifying question, so

Yerba Buena SX80: event, frequency? Is that event frequency

Yerba Buena SX80: of the Stillwater elevation? Or is that event frequency of a coupled precipitation and.

Gary Sjelin, Caltrans: That’s.

Yerba Buena SX80: I don’t want a little.

Gary Sjelin, Caltrans: Combination of events. So 9, 10 and 11 scenario are all considered to be a 100 year. Frequency, event.

Gary Sjelin, Caltrans: the precipitation that takes place for those 3 scenarios is not 100 year.

Gary Sjelin, Caltrans: In every case it is in the 1st one scenario 9, but only 50 year. Rainfall is assumed for scenario 10, and then no precipitation for scenario 11. And then those.

Yerba Buena SX80: And what is the where are you getting the precipitation values? Are they from? Like Noah Atlas, 14 or another data source.

Gary Sjelin, Caltrans: Yes, we the heckras model

Gary Sjelin, Caltrans: within the 2D area, we are using a rain on grid type of analysis. So we input rainfall based on Noaa Atlas, 14

Gary Sjelin, Caltrans: frequencies.

Gary Sjelin, Caltrans: and then for Sonoma and Napa, that’s a little bit different analysis. But again based on noaa rainfall.

Yerba Buena SX80: Okay, which is also historical and and quite out of date. I would note.

Gary Sjelin, Caltrans: So yeah. I. It does not account for a future climate change, scenario.

Yerba Buena SX80: Correct. Yeah. And it’s

Yerba Buena SX80: It doesn’t account for like existing conditions. It’s still

Yerba Buena SX80: we’re unfortunately not going to get Noaa Atlas 15. Since the funding for that was cut again. But that would provide the update for today’s conditions and future conditions for precipitation. But we do have other information available in the Bay area to look at how to change Noa Atlas 14. But

Yerba Buena SX80: the tied up peak flow. What how did you decide on 2 feet of surge to add on to the

Yerba Buena SX80: The different water levels.

Gary Sjelin, Caltrans: The 2 feet of surge.

Gary Sjelin, Caltrans: We looked at

Gary Sjelin, Caltrans: title records from other gauges in the area previous studies, and it seemed like that was a

Gary Sjelin, Caltrans: rather round 2 feet but a a reasonable value that got us into the ballpark of the

Gary Sjelin, Caltrans: 9.9 elevation. Again, this is a little bit lower, because we’re following the Caltrans guidance of using Pinoli Point, which has a a lower.

Gary Sjelin, Caltrans: extreme high water surface. But the 2 foot surge assumption is

Gary Sjelin, Caltrans: a a kind of an average of other gauges in the neighborhood. And I think we discussed that

Gary Sjelin, Caltrans: a little in greater detail in the report, but

Gary Sjelin, Caltrans: it is a very subjective number, as well.

Yerba Buena SX80: Yeah, that’s what scenario 11 looks like. It should be a hundred year.

Yerba Buena SX80: Considering like the 100 year event in the bay. So then it would be

Yerba Buena SX80: like the 9.9 point 9, which already considers surge. And yeah, so it’s.

Gary Sjelin, Caltrans: Yes, the the 7.1 2

Gary Sjelin, Caltrans: actually 7.1 2, I believe, was King tide

Gary Sjelin, Caltrans: elevation that we had record for

Gary Sjelin, Caltrans: gotta go back. We we looked at a lot of different number numbers. I must admit this is a few months ago. So

Gary Sjelin, Caltrans: I would definitely recommend going back and reading the report to make sure. That what I’m saying here is completely accurate. And

Gary Sjelin, Caltrans: to fully understand what all it includes.

Yerba Buena SX80: Yeah, I admit that I struggled in reviewing the report because there is a there’s a lot of data presented a lot of fema data, different tide gauge data. And so it’s hard. It was hard for me to wade through.

Yerba Buena SX80: What information was actually used, and why so and there were also a lot of references cited, but then there’s no reference list at the end, so it was hard for me to kinda check sources, so it would be great to add

Yerba Buena SX80: and like an upfront section that makes it really clear, like what the design criteria is and and like where it was derived, and.

Gary Sjelin, Caltrans: Yes. Again the the report was prepared. Earlier in the design of the bridge and looking at possibilities, and we recognize that we had

Gary Sjelin, Caltrans: less than desirable free board for given scenarios, and we were constrained with

Gary Sjelin, Caltrans: the railroad tracks on the the roadway profile. So this was a report that looked at possibilities on you know what might be the best we could hope for or the worst. So we were looking at a lot of different

Gary Sjelin, Caltrans: values and and guidance, Fhwa and Caltrans and other documents.

Gary Sjelin, Caltrans: to establish what would be a reasonable number to design to

Gary Sjelin, Caltrans: and yeah, and admittedly, it does become confusing as far as which numbers where they came from. And if when we update the report, we’ll try. And

Gary Sjelin, Caltrans: now that we have a a better bridge design and know, and closer where we’re at, we can

Gary Sjelin, Caltrans: make it a little less confusing. Hopefully.

Yerba Buena SX80: That would be. That would be great.

Gary Sjelin, Caltrans: Okay.

Gary Sjelin, Caltrans: Oh, shall we move on then? Or

Gary Sjelin, Caltrans: the bridge profile here we show. I guess the the most important thing is the bottom soffit elevation of the bridge at the left side abutment one is 12.8 that’s our current design and 13.6

Gary Sjelin, Caltrans: and and that the best design that we have

Gary Sjelin, Caltrans: today given the constraints of the profile, the economics of the bridge and the the girdered deck thicknesses and where we think

Gary Sjelin, Caltrans: future water surfaces might be, and the desired free board. So this is where we are today again, it’s been a moving target here.

Gary Sjelin, Caltrans: So let’s move on to the next one.

Gary Sjelin, Caltrans: This is just showing some figures from Fhwa design documents. We’ll start with the middle one in the center. This shows a bridge

Gary Sjelin, Caltrans: that’s being loaded by a wave exceeding in this case the top of the bridge deck. And the big Black Arrow there are wave forces that tend to be induced under the structure, the superstructure, and in the lower right we see a graph of the how that load varies with the wave, and we see that when the wave rises and hits the bottom of the deck. It tends to

Gary Sjelin, Caltrans: slap the bottom of the deck a bit, and you create this very high impact loading short duration. And

Gary Sjelin, Caltrans: those are the things that we recognize are possible at the bridge. It, and it is possible to design a bridge to be submerged. Under these conditions. But the

Gary Sjelin, Caltrans: preferred method is to provide free board above the top of the

Gary Sjelin, Caltrans: wave crest, which is the lower left example and in this case, Fhwa is providing guidance that the best method is to provide one foot of free board above, below the girders to the wave crest that doesn’t include the pile cap.

Gary Sjelin, Caltrans: If you’re looking at the wave crest relative to the pile cap, it looks like there’s no free board at all. But the free board is actually being measured to the low cord elevation, the bottom of the girders, and in this particular example it is girders as opposed to a box, girder, slab bridge.

Gary Sjelin, Caltrans: Which is what we’re proposing. So you don’t have the individual girders projecting down from the deck. It’s more of a smooth, flat concrete surface on the bottom of it.

Gary Sjelin, Caltrans: Bridge deck between file caps.

Gary Sjelin, Caltrans: and again, yeah, the the lower left is how we’re trying to avoid the wave forces and the impact forces and again.

Gary Sjelin, Caltrans: the loading of the bridge would take. If it did occur, it would happen 1st at the west end of the bridge.

Gary Sjelin, Caltrans: without being loaded at the east end of the bridge.

Gary Sjelin, Caltrans: unless wave heights got up another foot or so.

Gary Sjelin, Caltrans: Okay, let’s I I think that was the last one for me.

Gary Sjelin, Caltrans: Next slide. Oh, no, we do.

Gary Sjelin, Caltrans: present some water surface elevations here.

Gary Sjelin, Caltrans: These were the results of our scenario 9, 10, and 11 and

Gary Sjelin, Caltrans: the maximum discharge through the Tulay Creek bridge. We have negative discharges and positive discharges positive being in the downstream direction and negative in the upstream direction, the tidal

Gary Sjelin, Caltrans: flood, as opposed to the the ebb. Then these either have precipitation included in the runoff. For the analysis or not the in the case. 11. It’s predominantly tidal.

Gary Sjelin, Caltrans: and the velocities through the bridge that resulted from our modeling were very low on the order of one foot per second.

Gary Sjelin, Caltrans: Recognizing that that may change with Marsh Restoration project where the invert is lowered down to

Gary Sjelin, Caltrans: potentially minus 8 and a half elevation, and

Gary Sjelin, Caltrans: more of a defined channel created. And we’ve looked at the velocities from the Esa analysis for that marsh restoration.

Gary Sjelin, Caltrans: But again, that’s still I

Gary Sjelin, Caltrans: bit of a moving target. We think in that that design has not really been finalized yet.

Yerba Buena SX80: Hey, Gary, can I? Can I ask you a question about this.

Yerba Buena SX80: So.

Yerba Buena SX80: this is probably this might not be a very intelligent question. But am I gathering that? Really it’s the coastal

Yerba Buena SX80: flood source that’s governing the maximum water level and the minimum clearance, and not the fluvial flows

Yerba Buena SX80: in Tulay Creek.

Gary Sjelin, Caltrans: Yes, we have set it based on San Pablo Bay. Extreme tide elevations and sea level rise rather than the maximum water surface that resulted from our this analysis, in which case the maximum water surface was 9.4 5

Yerba Buena SX80: Oh, okay, yeah, I think it would. That’s

Yerba Buena SX80: thanks for clarifying that, I think.

Yerba Buena SX80: And the end.

Gary Sjelin, Caltrans: Yeah, the the 9.4 5 is based on the

Gary Sjelin, Caltrans: 7.1 2 king tide plus the 2 foot of surge assumption plus the 0 point 7 foot sea level rise. So you know that number is also a number that.

Yerba Buena SX80: Is a little.

Gary Sjelin, Caltrans: Fuzzy plus or minus couple of tenths.

Yerba Buena SX80: But but your your maximum fluvial flood level the tule Creek

Yerba Buena SX80: flood profile at the bridge. Elevation is less than the coastal flood source.

Gary Sjelin, Caltrans: I think.

Yerba Buena SX80: I think, cause you use. You used a mean sea level.

Gary Sjelin, Caltrans: Yeah, the the 100 year precipitation against mean sea level. The maximum water surfaces at the bridge occurred

Gary Sjelin, Caltrans: that occurred was the 8.9 5

Gary Sjelin, Caltrans: less than the situation where we had extreme tides in scenario 11

Gary Sjelin, Caltrans: but again scenario 11 also included losses through the to Lake Creek lagoon from the bay to the bridge.

Gary Sjelin, Caltrans: and those we decided to eliminate and say, Let’s just go with the elevation and the bay.

Yerba Buena SX80: Yeah, no, I appreciate that. I know I appreciate that. And it’s just it’s a little funny to me that to hear that the water levels might be lower, farther in. Normally on a stream, channel.

Yerba Buena SX80: or title tidally influenced creek.

Yerba Buena SX80: The water level at the bay is the lowest, and if there’s any flow.

Yerba Buena SX80: Yes.

Yerba Buena SX80: increasing flood profile water surface profile, because they’re slow in the channel. So usually the water surface profile goes up as you go up the channel, and not down, and.

Gary Sjelin, Caltrans: That.

Yerba Buena SX80: There must be a constant, a constant head for the bay that they set like away from the bridge.

Yerba Buena SX80: Yeah, I don’t know but I it so it’s a little counterintuitive to me. Some of the things I read, and I I’m not sure I

Yerba Buena SX80: well, I follow it sufficiently to support the some of the statements.

Gary Sjelin, Caltrans: Clarification. We don’t have a constant elevation in the bay. In this analysis we have a a tidal

Gary Sjelin, Caltrans: profile.

Gary Sjelin, Caltrans: So we we have high tide. We have mean sea level. We have a low tide. We have a diurnal tide with different tide elevations within the model. So we are modeling the tide going up and down within the 24 h period.

Gary Sjelin, Caltrans: That the storm occurs at. The question is, what’s the tide level at the time of the peak flow.

Gary Sjelin, Caltrans: and that’s where.

Yerba Buena SX80: And no, I get that. But what I was talking about is, what’s the tide level at the bridge?

Yerba Buena SX80: And I’m not. That’s what I’m not sure we know, because the bridge is upstream

Yerba Buena SX80: from the bay, and normally the water level goes up. When you go upstream. If there’s any flow it doesn’t go down.

Yerba Buena SX80: So that’s 1 thing I’m a little confused about. I’m not sure how significant those statements are in the report or to your design, but that confuses me.

Gary Sjelin, Caltrans: Well at the when. When the tide in the the bay goes up it it reaches the maximum tide elevation

Gary Sjelin, Caltrans: and and that’s instantaneous, and then it immediately starts to go down towards low tide. So when

Gary Sjelin, Caltrans: the maximum water surface in the bay reaches that elevation, what is the water surface in the marsh? Is it higher or lower?

Yerba Buena SX80: Yeah, you should see.

Gary Sjelin, Caltrans: Our analysis says that it’s slower, that it hasn’t had time to equalize with the bay.

Gary Sjelin, Caltrans: No, I, still

Gary Sjelin, Caltrans: flowing into the bay, and you have a lower water surface. In the marsh, I should not in the bay.

Yerba Buena SX80: Gary, I understand what you’re saying, and that’s.

Gary Sjelin, Caltrans: We see the lower water surface elevation at the bridge rather than what’s

Gary Sjelin, Caltrans: The absolute high tide in the

Yerba Buena SX80: Yeah, hey? So, Gary, I understand what you’re saying, and that that reinforces what I thought I read in the report. And what I’m telling you is, I don’t think that makes sense to me. It doesn’t. It’s not something that I’ve observed.

Gary Sjelin, Caltrans: It is

Yerba Buena SX80: Water levels higher as you move up, and I think part of it may be your starting conditions, or perhaps running a continuous simulation where you do have runoff

Yerba Buena SX80: and you you usually end up getting a higher water level farther in. So let’s just leave it as that. At that that I have a.

Gary Sjelin, Caltrans: Yeah.

Yerba Buena SX80: I would say.

Gary Sjelin, Caltrans: The typical hydraulic analysis. You would see water surface rise as you go upstream in in the channel when it gets impacted by a tidal situation.

Gary Sjelin, Caltrans: Now, you know, you not only see water moving downstream at the bridge, you see water moving upstream, so it’s a different

Gary Sjelin, Caltrans: situation. And in this particular instance we have a a very large

Gary Sjelin, Caltrans: storage area in the marsh upstream of the bridge, and that’s what’s really dissipating all of the flow

Gary Sjelin, Caltrans: not only from to Lake Creek.

Gary Sjelin, Caltrans: but Sonoma and Napa, which are all interconnected by

Gary Sjelin, Caltrans: channels and slews and the impact of all of those flows. That’s what we wanted to

Gary Sjelin, Caltrans: get a feel for by modeling Sonoma and Napa. I was concerned that Napa might have a significant influence. By the time it got over to to Lake Creek, Esa’s modeling said, No, we we won’t even model Napa. We don’t. Our our experience is that Napa doesn’t have an effect. So we did try to

Gary Sjelin, Caltrans: make sure we had all the bases covered and and understood what was going on, but there is, a lot of different combinations on timing. And but then you

Gary Sjelin, Caltrans: got to. Also considered the the frequency of that event. And are you creating?

Gary Sjelin, Caltrans: You know, a a worst case nightmare.

Yerba Buena SX80: Okay.

Gary Sjelin, Caltrans: Her gear can.

Yerba Buena SX80: Gary, can we move on? Can we move on, please? Yeah, can we move on? I mean, I’m I am somewhat familiar with that area. I was involved in the modeling and the restoration of the Napa Salt Ponds, where we did model the entire Napa Sonoma Marsh complex. So I I do have some understanding of the situation. Yeah.

Yerba Buena SX80: the velocity.

Yerba Buena SX80: Would you agree that Napa does not have a great influence?

Yerba Buena SX80: on Tolly Creek? Probably not, but I do think the Sonoma Basin does, and they are linked

Yerba Buena SX80: Sonoma Creek

Gary Sjelin, Caltrans: Agreed, yeah.

Yerba Buena SX80: Okay, can we move on?

Gary Sjelin, Caltrans: Yeah. Yes.

Yerba Buena SX80: Yeah. So the table with the maximum velocity you have here of, you know, somewhere around a foot per second or less doesn’t appear to be an equilibrium velocity in a marsh in my experience through a creek channel, and so I would expect that you would get sedimentation over time, and

Yerba Buena SX80: so I’m not sure I believe these velocities, and I think that

Yerba Buena SX80: perhaps Esa can help with the evolution of the system

Yerba Buena SX80: over time, and and get a better feel for the, for the velocities. There’s there’s still enough sediment floating around in the bay that if you have low velocities like this, especially on extreme events that implies that the sediment from the bay

Yerba Buena SX80: we’ll get we’ll deposit and and the grades, and you’ll get aggregation of the bed, and then higher velocities until it reaches equilibrium.

Gary Sjelin, Caltrans: So I’m not sure I I believe these velocities as design.

Yerba Buena SX80: Conditions.

Yerba Buena SX80: So with that, I’d like to go back to my question, what what are the implications

Yerba Buena SX80: of water levels a foot or so or 2 higher, then your design water level.

Yerba Buena SX80: What? What are the implications I can the bridge handle that structurally.

Yerba Buena SX80: Would the bridge be closed?

Yerba Buena SX80: Could it be repaired. What have you looked at that.

Gary Sjelin, Caltrans: Oh.

Gary Sjelin, Caltrans: I guess I should defer to structures. I I do not believe we’ve looked at hydraulic loading on the bridge. Because of the

Gary Sjelin, Caltrans: consideration that we’ve provided freeboard on the expected water surface elevations.

Yerba Buena SX80: Yeah, well, I, the risk of water levels being higher than what you’ve computed or or used for design criteria, I think, is that risk is less than

Yerba Buena SX80: where it’s. It’s it’s a higher risk than I than I think is acceptable, based on what I’ve seen. So it’s probably worth looking at that.

Yerba Buena SX80: And then how does what? What is the adaptation plan for? For the bridge at the end of it’s I think it’s like a 20 year life.

Yerba Buena SX80: And and you know, with sea levels getting higher, what? What is the adaptation plan for that? Is that

Yerba Buena SX80: determined yet? Or is there one.

Gary Sjelin, Caltrans: Oh, my God!

Yerba Buena SX80: Have you raised the bridge, or.

Gary Sjelin, Caltrans: Is it the the future bridge design.

Yerba Buena SX80: Yeah. So your design bridge. Now for for what looks to be a sea level rise amount that’s less than tip would typically be used for this type of project.

Gary Sjelin, Caltrans: Yeah, we

Yerba Buena SX80: So what happened our report today?

Yerba Buena SX80: See? You.

Gary Sjelin, Caltrans: Have not answered.

Yerba Buena SX80: Why is that?

Gary Sjelin, Caltrans: That future project, yet.

Yerba Buena SX80: You know, often for permitting a a project like this. There’s a request for an adaptation plan. When

Yerba Buena SX80: the sea level rise criteria are likely to be exceeded.

Yerba Buena SX80: And the question is, what happens next after they are exceeded. So that’s something that might be worth looking at as well as, and I think within that you would look at what the implications of higher water levels are

Yerba Buena SX80: to the bridge structure, to the facility operation.

Gary Sjelin, Caltrans: It’s it’s my understanding that the the future bridge is a much higher, wider bridge

Gary Sjelin, Caltrans: and and would probably involve modification of the railroad tracks at that point.

Yerba Buena SX80: Okay, thanks for that answer.

Gary Sjelin, Caltrans: And I I

Gary Sjelin, Caltrans: I’m not committing to any design of that future project. That’s not what we’ve looked at at this point.

Gary Sjelin, Caltrans: at least not what I’ve looked at at this point.

Yerba Buena SX80: Okay.

Yerba Buena SX80: So I have some general comments in discussion that we can get to and

Yerba Buena SX80: So I I don’t think, let me just check. I thought I had more questions. But

Yerba Buena SX80: this is taking too long. So

Yerba Buena SX80: I think, what I’ll I’ll do is

Yerba Buena SX80: just check my questions real quickly.

Yerba Buena SX80: Okay, yeah. So those are all my questions. And hopefully, we’ll have a discussion. The board will have a discussion.

Gary Sjelin, Caltrans: Okay.

Yerba Buena SX80: Thank you.

Gary Sjelin, Caltrans: Can we want to scroll down? Then one more, are we? That’s it. Thank you. I guess I wrap it up.

Gary Sjelin, Caltrans: Anyone else want to wrap

Yerba Buena SX80: Well, there’s there’s a a few things we we have to do.

Yerba Buena SX80: so thank you very much for your presentations. And thank you for answering our questions. Sounds like there is

Yerba Buena SX80: a bit of documentation or clarification that’s gonna have to happen.

Yerba Buena SX80: moving forward. So now we’ll go to public comment before concluding

Yerba Buena SX80: the Ecrb discussion. So for members of the public, if you would like to speak today, we request that you only provide comments or questions specific to the presentations given today.

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Yerba Buena SX80: during the public comment period.

Yerba Buena SX80: Starting with anyone present in person.

Yerba Buena SX80: Okay.

Yerba Buena SX80: seeing none, we’ll move on to the Zoom portion

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Yerba Buena SX80: but as always, we ask that everyone act in a civil manner.

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Yerba Buena SX80: No, okay, no, we don’t see any hands raised. Okay, thank you.

Yerba Buena SX80: Okay, so I think that’s the end of public comment. And now let’s

Yerba Buena SX80: return to board. Discussion.

Yerba Buena SX80: Where to start.

Yerba Buena SX80: I think we either start with hydraulics or geotechnical

Yerba Buena SX80: topics. Yeah. And well, your microphone is on Bob. Let’s let’s, is that okay, yeah, okay, appreciate it.

Yerba Buena SX80: so it seems like the analysis relied on fema flood studies to to some extent.

Yerba Buena SX80: and that those flood studies were not

Yerba Buena SX80: completed for this purpose, bridge design.

Yerba Buena SX80: Having said that, I know there are codes that use the base flood, elevation and the like, but

Yerba Buena SX80: it seems to me that a project. Specific study really needs to be made.

Yerba Buena SX80: which you’re partly the Caltrans is partly into.

Yerba Buena SX80: And there was a a nice review of all the available information, which

Yerba Buena SX80: was a little hard to follow, and led me to believe that there’s a lot of uncertainty

Yerba Buena SX80: and what the water levels are.

Yerba Buena SX80: At the bridge location and what they will be.

Yerba Buena SX80: So I think a site specific analysis

Yerba Buena SX80: is needed, and and I think maybe more than what’s been done is I would recommend more than what’s been done.

Yerba Buena SX80: One of the things I didn’t see was actual water level measurements. One of the 1st things I would do on any project

Yerba Buena SX80: would be to install a water level recorder, get good vertical control

Yerba Buena SX80: with a land-based data and tied the local tied

Yerba Buena SX80: datums to that land datum control, so that you know where

Yerba Buena SX80: your structure is relative to the tidal waters. Now, that sounds like it’s something you can do by going online. But I can tell you. You can’t

Yerba Buena SX80: do it as well as I think you might want to

Yerba Buena SX80: for bridge design, or even a March design, which is more my experience.

Yerba Buena SX80: Further, the tide information in the North Bay is not real strong.

Yerba Buena SX80: Sonoma Creek tide gauge was in for a while, but it’s no longer operating

Yerba Buena SX80: the tide gauges don’t pick up some of the surges.

Yerba Buena SX80: and it’s not clear to me that the 2 foot surge estimate or selection.

Yerba Buena SX80: which I think, was based on the tide. Gauges

Yerba Buena SX80: is adequate. One of the things we’ve seen in the North Bay and in other locations, but in particular in the North Bay

Yerba Buena SX80: is that the wind and waves can set up the water level pretty high.

Yerba Buena SX80: and the tide gauges don’t often pick that up, depending on where they’re located.

Yerba Buena SX80: depending on, you know which way the wind’s blowing and where the gauge is, and whether or not it’s

Yerba Buena SX80: in a deep channel or whatever.

Yerba Buena SX80: So I’m a little concerned that this extra surge, due to high winds and wave.

Yerba Buena SX80: induce mass transport of the water

Yerba Buena SX80: maybe higher than the 2 feet that that’s been allowed.

Yerba Buena SX80: So I I would recommend that Caltrans. You know this project. Maybe it’s a little too late, but I think for the Highway 37. Project Caltrans really needs to install some water level recorders. Get them tied in to a land-based vertical datum that you’re going to use for your your roadway

Yerba Buena SX80: and consider things like vertical and motion which has happened

Yerba Buena SX80: and may still be happening

Yerba Buena SX80: and then actually measure the water levels where you are because we have here not a separate

Yerba Buena SX80: fluvial runoff and a separate coastal

Yerba Buena SX80: flood. We have a compound or combined flooding situation.

Yerba Buena SX80: And it’s it’s a joint probability problem. The analysis done is what we call event selection, which is something engineers do with their engineering judgment, and those in responsible charge

Yerba Buena SX80: can do that.

Yerba Buena SX80: However, nowadays, with the ease of collecting data

Yerba Buena SX80: and the longer timeframes, we have to kind of Bootstrap collected data to observe data elsewhere.

Yerba Buena SX80: We can get 30 years of time series relatively easily both real and synthetic

Yerba Buena SX80: And then with you have that, you can actually start to compute 30 years or more, you can compute the joint probability or actually the probability of the water level at a particular location.

Yerba Buena SX80: So I think a joint probability analysis building upon water level data

Yerba Buena SX80: is really needed for this highway corridor, and the sooner Caltrans starts the better. So

Yerba Buena SX80: I’m I’m gonna recommend that it. It’s not that hard to do, put in a tide, gauge.

Yerba Buena SX80: tie it in to good control, and measure these things, and start to and and do that, not just

Yerba Buena SX80: at Chile that do it at Sonoma.

Yerba Buena SX80: and maybe some of the intermediate slew. So you can really get a handle on how well your modeling is working, and what the actual statistics are rather than rely on events, event, selection.

Yerba Buena SX80: Usually for event selection. I would use a hundred year fluvial and a 10 year bay water level and add, surge the event. Selection parameters that were done for this project are a little lower than what I would have used, and then I would also do a hundred year water level with a 1 to 10 year

Yerba Buena SX80: rainfall event. It’s so a little more conservative than what I saw here, and I I wonder what the Sonoma

Yerba Buena SX80: County Water Agency Flood Manual says, and maybe there’s some guidance that can be provided there.

Yerba Buena SX80: Further, as Chris pointed out, there is a future precipitation change with climate change. I know that you only have 20 year life.

Yerba Buena SX80: I’m not an expert on this. I don’t know how much precipitation, intensity, and flow. Rates will increase.

Yerba Buena SX80: river flow, rates will increase in this watershed in that timeframe. But again, I think the Sonoma County

Yerba Buena SX80: Water Agency Manual might be helpful or other state resources.

Yerba Buena SX80: So, in my opinion, the analysis done is not really adequate for

Yerba Buena SX80: defining criteria and the criteria are kind of

Yerba Buena SX80: not real clear in this case.

Yerba Buena SX80: but I recognize that you have a project that you need to build. And I you know I support.

Yerba Buena SX80: I think it’s a good project, and you have to match grade.

Yerba Buena SX80: But I think there is a risk

Yerba Buena SX80: that the water levels are high will be higher than your design at the design recurrence interval.

Yerba Buena SX80: So I think that’s that’s that’s my concern. And I don’t know if if Chris would like to

Yerba Buena SX80: correct me on anything or add to that because I really would appreciate her input

Yerba Buena SX80: okay, I just wanted to. Yeah, I

Yerba Buena SX80: thanks, Bob, for for your comments.

Yerba Buena SX80: what are the implications of having a water level

Yerba Buena SX80: higher than and like you were saying like, What is, what is that? Are you shutting down the roadway? Are you potentially damaging

Yerba Buena SX80: the bridge, so that it’s unusable.

Yerba Buena SX80: you know, for a significant amount of time after this event, or is it? Oh, we’ve we’re shutting it down while the tide is high.

Yerba Buena SX80: 4 h later tides out.

Yerba Buena SX80: We’re okay.

Yerba Buena SX80: And is that something that gets addressed in your your risk mitigation plan?

Yerba Buena SX80: Well, I could speak to the 1st part of your question. We’re currently facing that on the western side. I mean, you’ve probably seen. So yeah, we we end up closing the highway and and using a detour. Lately our field maintenance folks have gotten really good at preventing it using pumps. So we do have

Yerba Buena SX80: mitigation measures for that as far as the integrity of the bridge. I don’t know, Louis. Could you speak to that? Or Michael?

Yerba Buena SX80: Well, I mean not really, because we’re not designing for

Yerba Buena SX80: a title of wave action as

Yerba Buena SX80: recommended to us now, based on hydraulic recommendation.

Yerba Buena SX80: Okay, thank you.

Yerba Buena SX80: Yeah. Thank you, Bob. I think you’ve covered some really great comments. I

Yerba Buena SX80: I’m glad to hear that you’re doing additional analysis than what was documented in the report.

Yerba Buena SX80: it sounds like this report is probably a a draft, and out of date based on where you are today. So it would have been really helpful to review the analysis that’s actually been

Yerba Buena SX80: done today. I agree that the the combination of scenarios

Yerba Buena SX80: we’re all I think, lower than what I would typically assess I didn’t see how the Bay water level elevation, 100 year event of like 9.9 feet plus 0 point 7 feet, like how that was used

Yerba Buena SX80: as like the Bay boundary condition in the Hecras or Hec. Hms. Modeling

Yerba Buena SX80: the highest one that I saw was 9.4 5 feet, which was is significantly lower, you know, over a foot lower.

Yerba Buena SX80: yeah, there’s a lot of references in the report to the Fema data, both for coastal and for riverine.

Yerba Buena SX80: It’s not clear how all of that information was used.

Yerba Buena SX80: particularly for the riverine. There were often 3 different kind of Cfs values that could be

Yerba Buena SX80: in the different creeks, including the fema value, but no reference to what year that fema study was actually done, because a lot of the riverine analysis is much more out of date than the coastal analysis.

Yerba Buena SX80: So yeah, I kind of struggled when reviewing the report, and it would be great to see it clarified, and to frame it more in terms of that constraint at the rail, and and looking at a broader range of scenarios to look at the risk on. If that water level is higher to frame it more based on a risk framing approach of like

Yerba Buena SX80: what’s that?

Yerba Buena SX80: What is the maximum sea level rise? You can accommodate under an actual 100 year event. And what is the risk? If we get things higher?

Yerba Buena SX80: I would definitely recommend trying to use existing precipitation conditions, and kind of bumping up Noaa Atlas 14 for 2050, so that you are kind of doing an apples to apples with sea level rise and precipitation.

Yerba Buena SX80: I mean, it seems like your risk is primarily at that Western abutment. That’s your your low side and not along the whole bridge. So hopefully, it’s not

Yerba Buena SX80: like too much work to consider

Yerba Buena SX80: And then I would also encourage to maybe also try and collect some wave data

Yerba Buena SX80: in addition to the water level information that Bob recommended.

Yerba Buena SX80: Particularly along this whole corridor. I think you’re going to have some wave issues and wave information is so limited in the bay.

Yerba Buena SX80: So a lot of all of these transit space models are

Yerba Buena SX80: probably wrong. They’re kind of best sketches. But, like so far. Ocean, San Francisco. Big business makes pretty small little wave buoys that you can deploy to collect wave measurements.

Yerba Buena SX80: you know a lot of places around the bay are starting to do that. So I think

Yerba Buena SX80: I don’t think this information would be available to inform this project, but it would definitely be, I think, really helpful to inform that that longer term project. So it is based on more real

Yerba Buena SX80: data.

Yerba Buena SX80: Okay, thank you, Chris. Thank you. Bob.

Yerba Buena SX80: Do we have some more geotech comments or

Yerba Buena SX80: the logic comments we already kind of covered that, or do you want to? Feels like we’re kind of summarizing our our comments here. Patrick has his hand up awesome.

Yerba Buena SX80: Oh, Patrick, yes. Sorry. Yeah. Okay. Well, then, let’s if there’s no geotechnical, let’s let’s move. So I think there’s something to talk about, geotechnical about. What are we going to ask them to do? Going forward in summary, but nothing new that I have to add. Okay, okay.

Yerba Buena SX80: we’ll we’ll get to. Yeah. We’ll we’ll summarize and get our comments in soon. Patrick.

Yerba Buena SX80: I I don’t think that we have sufficient information right now to evaluate the design criteria around the joints and fuses specifically and how those

Yerba Buena SX80: interact with the loading on on the lateral system of the bridge. You know the piles or the the vents themselves, so I guess I would like to ask for additional information around that there are. There is at least the the fault, displacement, fault, rupture, displacement that you guys have discussed. I also see mention of fault creep that may or may not, because of a slip rate of 9 a year

Yerba Buena SX80: that may or may not be adding creep to the site

Yerba Buena SX80: over the 20 year design life. There’s also the inertial loads that will happen during the earthquake. Possibly after the the rupture, displacement has happened. So all of those things. How are you combining those? How are you

Yerba Buena SX80: addressing those at the joints and the fuses? And I don’t think that this board needs to, you know, review in detail necessarily, the structural details of the joint or the fuse, but I think it would be helpful.

Yerba Buena SX80: as we evaluate that criteria if you gave us at least a sample of you know a possible detail that you might use, so that we can understand what happens to the fuse when it fuses in one direction. It doesn’t fuse in the other direction.

Yerba Buena SX80: Where exactly are the additional widths that you’ve given to the pile caps or the ledges. So I’d like to ask for sort of a clear description of of the design of the joints and the fuses, and how that then impacts the loads on the piles.

Yerba Buena SX80: Okay, thank you. I see. Bill, you have your hand up.

Yerba Buena SX80: Thank you. And I think related to Patrick’s request. I had a

Yerba Buena SX80: a couple of follow up notes that I think would be helpful to see

Yerba Buena SX80: in any updated design criteria that we have to look at, and I think.

Yerba Buena SX80: along the lines of what Patrick was requesting. I think it would be helpful. There’s some pretty significant components that I understand are driving the design, the seismic design of the peers, and

Yerba Buena SX80: the sizing of events to accommodate the seismic demands whether that’s

Yerba Buena SX80: the dynamic ground motion component that drives the inertial loads and also just the physical displacement of the fault rupture.

Yerba Buena SX80: And to that end I think it would be helpful to understand. I think the acceleration response spectra is a probabilistic

Yerba Buena SX80: hazard. But just to get any comment on that. It would be helpful to understand whether there’s a from a if that’s deaggregated, what component of that hazard is driven by

Yerba Buena SX80: the Rogers Creek fault, which is where the fault rupture is going to occur versus the other hazards contribute to that. And then, in terms of the structural component demands when you’re looking at some of those big, bigger

Yerba Buena SX80: ductility demands that you have requested an exception, for that’s pushing from the typical, I think, of 5 to requesting 8. Because you’re looking at combined actions. It would be helpful to understand in the criteria, roughly, what proportion of that ductility demand on

Yerba Buena SX80: the

Yerba Buena SX80: The peers is coming from the seismic head or the the ground motion

Yerba Buena SX80: from the acceleration response. Spectrum versus the physical offset from the fault. Rupture.

Yerba Buena SX80: I think would be would be helpful. For for our understanding on the structural side of things.

Yerba Buena SX80: And I did have one other.

Yerba Buena SX80: And and I realize this is, it sounds like this is outside of this, the the scope of perhaps of what we ought to consider and what you on the design team side have considered. But I

Yerba Buena SX80: it was a question that came occurred to me as I started looking at the documentation presented, and this was around the classification or the selection of ordinary.

Yerba Buena SX80: I am interested to understand. Along the length of

Yerba Buena SX80: route 37, there are a number of bridges on the route. Are they all considered ordinary? Or are there other bridges along that route that are in the that are classified as recovery? Or

Yerba Buena SX80: there’s there’s very few, I think, in the Bay Area that are considered important.

Yerba Buena SX80: But it would just be helpful, for certainly, for my understanding of the context of the selection of ordinary for for the bridge

Yerba Buena SX80: for this workshop. Thank you.

Yerba Buena SX80: Just the comments it possible. Get all that information in writing is, would that be possible? All the questions that you have put it down in writing, so we can respond to it

Yerba Buena SX80: exactly per.

Yerba Buena SX80: The questions being asked. Yeah, I’ll follow up with a written letter. And also this meeting’s being recorded. And it will, the recording will be posted on our website. Yeah, I just, there’s a lot of technical information there. And we want to make sure we address it.

Yerba Buena SX80: Yeah, okay, thank you.

Yerba Buena SX80: Okay. Well, so, Jim, I think

Yerba Buena SX80: maybe now is the time for your your comments. Sure I can start. Yeah,

Yerba Buena SX80: So just having again nothing that we haven’t talked about already, I think

Yerba Buena SX80: I’ve been interested in seeing an update of your Eps or other lightweight fill

Yerba Buena SX80: parameters and design assumptions, design approaches. How you’re handling that.

Yerba Buena SX80: And I think you also talked about providing

Yerba Buena SX80: some information about dimensions and construction sequences with respect to tides, and so on, making sure you’re not putting Eps below high tide level, for instance, whatever, anyway. So just some construction approaches.

Yerba Buena SX80: I think it would be

Yerba Buena SX80: appropriate to provide a summary of a clic evaluation.

Yerba Buena SX80: Pretty straightforward.

Yerba Buena SX80: I’m not anticipating there’s going to be any big problems that are going to show up there.

Yerba Buena SX80: I will be surprised if they’re not some liquefiable zones that C lick will say this is liquefiable, and I think you need to respond to that.

Yerba Buena SX80: Not necessarily change your whole design, but but but take a take a

Yerba Buena SX80: a serious look at it.

Yerba Buena SX80: Minor! It’s not gonna affect the design, but I think you should relook at the the

Yerba Buena SX80: term Consolidated Bay mud. I think it’s an old. I think it’s an older alluvium

Yerba Buena SX80: And then I

Yerba Buena SX80: give us a little bit of approach. How you’re dealing with lateral analysis, lateral pile analysis. I think we’ve talked about some lateral loads, but just give us some L pile parameters, or whatever you’re going to be doing on that.

Yerba Buena SX80: And then we talked about stability also. And again, kind of like liquefaction, not sure that stability or or lateral deformation is going to be an issue, but I think it needs to be looked at a little more than just saying, it’s flat.

Yerba Buena SX80: Does that make sense? Jutex? Yeah.

Yerba Buena SX80: yeah, that’s that’s that was my summary. Yeah. I mean, I just wanted to talk about a couple of things. I mean, there are reports.

Yerba Buena SX80: The foundation report is

Yerba Buena SX80: describe as a preliminary foundational report. So I’m anticipating that there would be a more detailed design level type report. Right?

Yerba Buena SX80: That’s correct. Okay? So you know, hopefully.

Yerba Buena SX80: we’ll be able to see that in the foundation reports

Yerba Buena SX80: regarding ground motion it talks about.

Yerba Buena SX80: There’s going to be a ground response analysis.

Yerba Buena SX80: I think the spectrum that we have here is based on map. Spectrum.

Yerba Buena SX80: Right?

Yerba Buena SX80: Yes, it’s based on our Caltrans ars. Okay? So you’ll be doing a ground response analysis type.

Yerba Buena SX80: Yes, ground motion.

Yerba Buena SX80: So I think that would be

Yerba Buena SX80: good to see. I don’t know what the time is on all of these things.

Yerba Buena SX80: When are you supposed to issue a more detail geotechnical report?

Yerba Buena SX80: I think we have the size specific response.

Yerba Buena SX80: I think we did. Yeah, okay.

Yerba Buena SX80: alright. So that would be good to see and then the final comment I have relates to the fault rupture reports.

Yerba Buena SX80: There’s a talk about this uncertainty with respect to the fall trees.

Yerba Buena SX80: I think maybe an explanation of what that means, and the implication for the design.

Yerba Buena SX80: I will contact the geologists and get get a good explanation for you. Yeah.

Yerba Buena SX80: Okay. There was a reference here to.

Yerba Buena SX80: You know how the medical offset is estimated. It seems to be based on

Yerba Buena SX80: displacement for 49, 75 return period.

Yerba Buena SX80: Yes. So I mean that displacement is not mentioned the it mentioned the vertical offset.

Yerba Buena SX80: but I was thinking that the horizontal displacement was based on

Yerba Buena SX80: the 49, 75, or 10 period.

Yerba Buena SX80: Think that I’ll I’ll get clarification from the from the geologist that wrote the report

Yerba Buena SX80: address all the questions. Yeah. So if

Yerba Buena SX80: whether it’s related or not, because I was taking 10% of the horizontal displacement, and this

Yerba Buena SX80: less than what is stated here. So it will be good to know what the displacement for the 49 75

Yerba Buena SX80: for the time period is, we’ll take care of it. Alright. Thank you, Zalia. Did you have?

Yerba Buena SX80: Let’s see one follow up question on the fault, hazard and displacement, and so building upon Patrick’s question on the longitudinal direction.

Yerba Buena SX80: So I was wondering you mentioned that the fault is essentially perpendicular to the alignment. Is it exactly perpendicular? And can can you provide information if there is any longitudinal component? Is it accommodate? Basically I think that’s given the uncertainty. That’s that’s my follow up comment on the fault.

Yerba Buena SX80: I can’t say myself like I said. I’ll have to get clarification from the geologist that wrote the report. So we’ll address your questions.

Yerba Buena SX80: Yeah, I think in the report it did say is essentially transverse to the bridge, to the new proposed bridge. Correct in the file in the fall rupture report.

Yerba Buena SX80: Yeah, I think that’s what it says. That’s what it says. But given the uncertainty. So my comment essentially is that, is there any uncertainty on the orientation with respect to the alignment? And is this taking consideration, the design we can confirm? Well, I will have to confirm that with the geologist that wrote the report.

Yerba Buena SX80: So I I think, the bigger question is regardless of whether we think it’s exactly perpendicular to the bridge, it’s not.

Yerba Buena SX80: And so is there some detailing in the bridge that accommodates a little bit of displacement in the longitudinal direction? And if so, you know, how much are you accommodating there? I think that’s what we’d be interested in. Yeah, I think the important thing is that noting that our superstruct is continuous, and we are increasing our band cap with. And really our guiding mechanism is a no collapse mechanism.

Yerba Buena SX80: So really, even if that super does move, due to fault, rupture not exactly perpendicular, we should still be able to support that right well. But you have a fuse that you said does not fuse in longitudinal direction it so if 2 2 adjacent abutments move closer together by some number of inches.

Yerba Buena SX80: and the deck will not, and the deck, and the non fusing fuses will not allow the tops of those abutments to move together, you know. Has the has the abutment been designed with enough robustness that it can accommodate that.

Yerba Buena SX80: Yeah, the abut. So so the so the important factor in the abutment is the overall seat with correct in order to for it to unseat. Is that what you’re referencing? I couldn’t hear what you said there. The overall, what the overall seat with

Yerba Buena SX80: is the is the controlling factor, not in the longitudinal direction. If the fuse does not yield in the longitudinal direction, the extra width is not going to matter, because the deck won’t move with respect to the pile Cap, if I’m understanding this right? Yeah. So the fuse is is supposedly for the purpose of fall lecture. So when does when fall lecture does occur it will fuse right in the perpendicular to bridge direction.

Yerba Buena SX80: Correct, we’re designing in the longitudinal direction, you said. It does not fuse, it does not. But the longitudinal well, well, we could probably explain that. But the longitudinal component it could be a partial to the transfers. We need to determine. We need to take a look at what the maximum

Yerba Buena SX80: controlling factors are for size, because it’d be longitudinal or transfer. Yeah. And I think that’s what Kelly’s asking for. Okay.

Yerba Buena SX80: okay.

Yerba Buena SX80: I had one follow on to Jim’s Jim’s question about I think the pile Embedment criteria. I think you kind of covered it. But just I’d like some clarity on how you are selecting

Yerba Buena SX80: pile tip elevations, you know. Given lateral

Yerba Buena SX80: loading plus the vertical I just

Yerba Buena SX80: I I guess I didn’t read that part of the report, but if there’s some

Yerba Buena SX80: clarification that I can get, I would I would appreciate that.

Yerba Buena SX80: What’s the exact question you’re asking, how how are you

Yerba Buena SX80: selecting or figuring out what your pile tip elevation is.

Yerba Buena SX80: and describe the criteria.

Yerba Buena SX80: the pirate tip based on the load that we have. Yeah, basically. So we use skin fraction and ignore the end bearing. So mostly, we use a program shaft that we mentioned that. So we use a shaft program to calculate.

Yerba Buena SX80: Do you also check against the lateral the applied lateral? We provide the soil parameter to a bridge design, they will run the lateral analysis using as high. Okay? And that confirms that

Yerba Buena SX80: the the vertical load tip elevation for specified elevation for construction. Okay, yeah, thank you.

Yerba Buena SX80: Okay, so it sounds like there is a there are some clarifications and some extra information

Yerba Buena SX80: that’s required. And I guess the question to the, to the board here is, it is, is it

Yerba Buena SX80: necessary to have another meeting to go through the clarifications and additional information? Or do you think that

Yerba Buena SX80: you know email or whatever you know, the information provided and review by individuals is, is adequate.

Yerba Buena SX80: Basically, do we need another meeting to to to consider this

Yerba Buena SX80: 1. 1 thing I would say is, it sounded like the comments came from all 3 disciplines, and it’s

Yerba Buena SX80: It’s cumbersome to handle that in a subcommittee format.

Yerba Buena SX80: Okay, Jim, you were. Gonna say, I think that I think there’s enough

Yerba Buena SX80: still open questions related to design criteria that it makes sense for us to look at it again.

Yerba Buena SX80: Anybody anybody on the board disagree? Yeah. Okay.

Yerba Buena SX80: okay, so, Jen, I’m sorry to do that to you. But do we need to make a motion for that recommendation? Yeah, yeah, I think that I would move that we request that Caltrans return to provide responses to the questions that we’ve raised. Second, can I, before you vote? Can I just check in with Caltrans to see if that’s

Yerba Buena SX80: if that can work with their schedule. Do you know that can work with your schedule to come back with

Yerba Buena SX80: with to present some of the questions they’re asking for information on?

Yerba Buena SX80: Yeah. Okay, when we anticipate the next meeting to be scheduled.

Yerba Buena SX80: just canceled June, July. So we have August.

Yerba Buena SX80: You could potentially uncancell those. I think right. I could potentially uncancell them.

Yerba Buena SX80: Yeah, we typically have a standing space held each month, excepting December and

Yerba Buena SX80: sometimes August for Christmas summer holidays. Okay? So when and when would we anticipate getting a summary of the comments that were presented

Yerba Buena SX80: by the by the board today?

Yerba Buena SX80: In a week? Okay.

Yerba Buena SX80: I guess I would turn to the team here and ask like, how fast can we respond? Knowing what we kind of have a preview of what those comments are gonna be.

Yerba Buena SX80: would we be able to get a response written back and then be able to summarize that within July.

Yerba Buena SX80: August timeframe?

Yerba Buena SX80: See how it is for me.

Yerba Buena SX80: Okay.

Yerba Buena SX80: cause we would want to have the materials. You know, 3 or 4 weeks ahead of time, too.

Yerba Buena SX80: I I wouldn’t know that I would anticipate submitting a permit application before that time. So if that’s okay with, I think I don’t know Brown, if it’s you or Julie that would be mainly handling as the analysts.

Yerba Buena SX80: you know our anticipation is that you would be getting an application

Yerba Buena SX80: concurrent with our response to the the Ecrb, and if that’s acceptable to Ecdc, then, I think.

Yerba Buena SX80: move on that pathway.

Yerba Buena SX80: Yeah, we we have Ecrb meetings many times after permits are submitted. Applications are submitted.

Yerba Buena SX80: So you’re probably submitting the application in July.

Yerba Buena SX80: Soon as we get all the design details pinned down, I can finish my impact analysis for you. I mean, as soon as I can. There’s there’s a few

Yerba Buena SX80: there’s a few things that I’m still trying to think about. So, okay.

Yerba Buena SX80: okay, so we have a motion and a second to

Yerba Buena SX80: ask Caltrans to come back again and and present clarifications and information for Toll Lake Creek Bridge.

Yerba Buena SX80: all those in favor. Aye, aye, any opposed?

Yerba Buena SX80: Okay, so that motion carries okay.

Yerba Buena SX80: that concludes the Board’s consideration of the topic for today.

Yerba Buena SX80: So that concludes our meeting agenda, and I would entertain a motion to adjourn.

Yerba Buena SX80: It’s moved. Second, okay, it’s been moved and seconded that we adjourn.

Yerba Buena SX80: I would maybe suggest that we we all again thank Jen, for we we adjourn, and you know, appreciation of Jen and all of the

Yerba Buena SX80: the work and effort that she’s put in to help us move forward smoothly.

Yerba Buena SX80: Okay, so anyway. Yeah. Thank you. Jen, okay, all those in favor.

Yerba Buena SX80: Aye, aye, any opposed?

Yerba Buena SX80: Okay, we are adjourned. Thank you. And have a very good rest of your day.

Yerba Buena SX80: Yeah, thank you.

Yerba Buena SX80: And we get out. Yeah.