tv Treasure Island Sustainability Committee SFGTV April 17, 2021 5:00am-6:36am PDT
>> the hon. london breed: i am sorry. i can't hear you. [inaudible] >> the hon. london breed: i think we're going to have to continue doing some of the things that we're doing. there are a lot of -- i hear restaurants. they're having trouble with hiring people, and we want to make sure a small business owner, that's a mom-and-pop shop, as they expand, they can find people to work in their shop and afford to live in san francisco. it's going to be a balance, so when there are resources available, there will be money in our upcoming budget that i will introduce to allow some additional support for our small business community, but we also have to continue to connect our businesses with the resources -- thanks goodness we have a new president and vice president because that has been so critical in helping to provide more resources to small
businesses who have been struggling the most, so we definitely anticipate we will be doing more. [inaudible] >> the hon. london breed: so part of why we added an additional $10.6 million in grants are for those businesses that are having the most difficult time, where they have to go through a process to access city resources. this is about those who could not get resources, who have, like, six employees or less who are struggling and need support. but also, we're not here to micromanage what they use the money for. we know there's a moratorium against evictions for rent. that moratorium expires for the state at the end of june, i think it is, june 30. we know that rent is still going to come down, and we're going to need these resources,
so our office of economic and workforce development has been working so hard with so many of these businesses. it wasn't a loan pool, it was a grant pool, and we removed so many of these barriers to be able to access this money. all right. don't forget, shop local businesses, #smallbiz, b-i-z, because manny doesn't know how to spell. small business challenge. thank you all so much.
>> this is the april 15, 2021 treasure island development authority sustainability committee meeting. due to the health emergency board members are participating remotely via video conference in the same extent as if present. public comment is available for each item on the agenda. for members who wish to comment the phone number is 415-655-0001. the access code (187)659-2091. then press pound and pound again. when your item of interest is called dial star 3 to be added to speak. please wait until you have been unmuted to begin your comments. you may address the board once per agenda item two minutes. 1. call to order. director kwon. >> here.
>> director tsen. >> here. >> director richardson. >> here. >> thank you. we have a quorum. >> do we start with general public comment? >> yes. >> 2. general public comment. there are no callers for public comment. >> thank you. >> item 3. consent agenda. 3a approving the minutes of the january 21, 2021 meeting. >> i move. >> second. >> roll call vote. director kwon. >> yes. >> director tsen. >> yes. >> director richardson. >> yes. >> three ayes.
>> do we need any discussion? okay. next item, please. >> 4. treasure island sea level rise design and adaptation strategies. >> we have a special guest to do a presentation today which i am excited about. we would love to hear more from our guest. if you would do a brief introduction please. the floor is yours. thank you for being here today. >> am i good to go? i am a coastal engineer. i have been involved with the treasure island project for about 14 years. since the property was culminated. we had over the period of time
the genesis of this work, the sea level rise is different compared to some of the other areas that we use in engineering such as seismic and building designs and those kind of things. what was the design basis for the project itself and the strategy in case that sea level exceed whatever the numbers suggested estimates have been. at the time of the document itself and going to the community meetings, the citizens stakeholder meetings, the issue -- two issues kept coming up. low elevations of the island and the other was the nature of the
soil the compaction and those things. this is an example at the time fema was remapping this is post katrina work. it was remapping and doing digital map modernization which incorporated whatever sea level rise occurred since the last fema maps. this is san francisco basic bay. the wined surges which is the action that comes through the golden gate the pacific swell, and then just normal low pressure anomalies that we get that results in super-tides.
two feet higher than what they predicted tides are with the surge. then the bcdc was the other agency shining the light on the vulnerability of san francisco bay and the urban communities. these were maps they put out after we had already gone through the first round of planning for treasure island. these showed what will happen with 16 inches, which was a number that was the best available by 2050. the level were projected to be 16 inches. by the end of the century 55 inches. coming to treasure island, this is not the best graphic image. this is what the condition that
was delivered by the navy itself to tida. the contours there indicate the magenta is significant. that elevation is about today's 100 year elevation or what fema caused the base foot elevation. it is the extent of flueding f100 year treasure island f100 year tide were to oker. the north west portion would be flooded and a small little tongue at the southeast corner. the other portions were elevated higher than the 100 year tide. in general they were about a foot to two feet above hundred
year tides. when we started looking at the proposed programs there were two choices to be considered. they are going to have to build a levee around treasure island and protect it like redwood city or portions of the delta. to our thinking and working with the development team, it was an extremely progressive group of people that did not want to build a project that would have taken 20 years planning and design and construction and at the end the protected communities. we saw what happened with katrina and others and since then. the decision was made and commitment was made that all of the development parcels are
going to be elevated. not only are those the 100 year floodplain but it will occur a good amount of time in the future. that is where the scientists and the technical analysis ended up focusing on that number that we should design for at a minimum? the next few slides i am showing how curbs do not exist. it is a big plan. it has gone into being a requirement. in many ways the designs are occurring. the numbers we have now still have not been updated for the past 21 years. all of the sea level rise
estimates today in the newspapers or in the publications and usds use data up to the year of 2000. they haven't been updated. low, medium, high we don't know. we will know next year when they update. it is still maturing. the guidance in 2008 was not enough to support the code like the building agency or fema map would be. these are examples for other phenomena. in this instance i am using this how you would typically design and based on the vulnerability and the consequence of the
problem derm where the risk is the consequence of a failure is significant. the low bar for risk tolerance. the numbers down there are probability numbers which we as engineers use in our analysis. this one number here 475 years. what does that mean? the risk of 10% in 50 years. designing to an earthquake that with have a probability of 10% of occurrence over the next 50 years. we don't have that sea level rise. this is information and estimates that existed at the time. with the ipcc and the national
resource council which which develops estimates for the west coast. you can see the danger. the range of 8 inches to a projected estimate which nrc has given of 66 inches. how do we as planners make a decision about what level of sea level rise to put into the plans itself? first thing as social engineers who worked both in the gulf and east coast and west coast, there is a big difference in the way our storms and properties are subject to flooding. that is a problem.
east coast have very large variations in sea level which we don't have. our issue has been height, weight. we explained a typical shoreline around treasure island. what does it look like. this is typical. it is to scale where the elevation around treasure island is 12 to 14 feet elevation. that is the standard data used. it matches the same as low tides. if it was 14 feet buffalo tied, this is 6 feet. someone could say you have 6 and the other 12, no problem. you have strong surges, it all
elevates that to elevation of 9.1 which is what the fema number was when we started doing this. above that is potential for waive energy from the golden gate. what we see is very little left. no allowing for sea level rise. that is what started us to think. build a levee. other communities adopted to move higher, abandon first floor elevations. move to the second floor. that is number 4 create buffers and adaptation strategy along
with high capital investment to raise properties was the method deployed. we went through the consequences and risks, what will happen to the open space. there was a difference if the open space such as city waterfront park were to see a few inches of water 50 years from today, 800 year tied it may be acceptable. it is an open space and we would be okay. we cannot afford to have our streets and parking lots subject to parking. the modeling analysis. this is the summary how we arrived at what is a well established fact of treasure island. this is the basis. 70 years was a time by the
partners, development team and tida. 70 years is a good period of time. beyond 70 years it may be time to do some improvements to the assets that exist there. let's look at the high pest number that existed which happened tube in the year 2017. that was the driving factor. we wanted to ensure beyond 2007, 70 years is not the end of the community. what happens at the end of the century. that would have been two feet higher. what can we do. that is the thinking for the
post project as you see it. the 300-foot set back from the east shoreline -- west shoreline. the open spaces are all around. that became the design criteria this is the initial construction, existing perimeter at the time of development already what has happened phase 1a and b. the perimeter isvationrd. the elevation of the rocks that you see there and the difference between what has been done that you see here. this was also elevated for the
promenade. the setback of 50 feet can now accommodate the sea level rise beyond today. without any improvements needed. in the future beyond three feet of sea level rise, what could be done. niece are potential options we are made of. it is for the western shoreline and this is the northern shoreline. it is a mix of urban and more natural habitat to be utilized. we start out with what exists as you see here. this is being constructed as part of phase 2. the options beyond 36-inch
chess. the community would want to have a say. 70 years from today what should be done. we give them options. you want to set back the open edge and pass, you could c this space more subject to storm related topping. those could be leveraged for weapons and habitat. we could do that. the other options were removing the levee. portions of the island the levee would be taken down. when you take down a steep slope and rocks and replace with a shallow slope, the action is absolved by the flattening of
the scope itself. the beach would be possible, marsh ems would be possible. the overall strategy for the sustainability portion was elevate the development area. in this case so many years at minimum. ensure there is a set back area with numbers exceed what is projected or planning beyond 70 years. the most important part. it was put into place which early in the next presentation i will talk about seeing it.
basis. i will open it up to questions. >> thank you so much for the presentation. i have a couple questions. i want to open it up to my fellow commissioners first if they have any questions. >> yes. good afternoon. i had the honor of walking with you on the part of san francisco waterfront planning years ago. i am glad that you are here
today. unfortunately you cannot see me, but i am taking notes. i think the timing of your presence here today at the beginning of the committee is crucial. there has been a lot of conversations among san francisco. again, our commission has not done a great job in actually letting the public know about how the process and the years and years of deliberations of the planning of the treasure island and yerba buena development. you mentioned in your presentation that prior to the establishment of the plan there was extensive adaptability study and it was recommended for the
elevation of development in some of the areas. my question on what you have seen so far is tida actually following the process that the engineering group and your group have suggested? i ask a question. i think i should hear from you your assessment as to how these developments are going. thank you. >> i was trying to cover some of that. whatever the pleasure of the board is. >> those numbers were written into the permit. there is very little room we
have to deviate from the strategy. the strategy became the basis for bcdc to establish climate change addendum that occurred in 2011. the numbers and strategy deployed for treasure island and working a lot during that day with world travelers. they like the idea, the approach. they put it into the statement. that was the very first project approved after the 2011 guidance was issued. whatever we showed you in terms of the numbers, the options, the
commitment for the project generated funding were all written in. these numbers i have shown became minimum numbers on phase 2a as we expand we are acceding the standards we had explained in the department fests. yes, the answer to the question it is being followed. the individual phases developed and the grading plans have all been approved using these numbers themselves and deviate from that. >> thank you very much. >> i would like to ask a question. thank you for the presentation. we have been waiting for this presentation and there is so
much factual information which i really appreciate. i understand the numbers you had in 2008, three feet at that time seemed like a lot. it was a time when we did not anticipate the say level lies. i believe you came up with the master plan was very small. you did have the setback from the edge for development. the development was on higher ground you have a wild wetland that could be inundated. that would not affect the future tree development. my question to you is given the
consequences of climate change and what we know now is three feet adequate? the time for treasure island if the sea level rise is more than 3 feet. now people are talking about five feet becoming standard. if it is 5 feet does that plan we have the developments that we are planning are they employing to be able to be protected? >> one response i would have is at the time when all of the sign assists had come up -- scientists had come up with 69 inches there were any new medical estimates of probability
or certainty assigned. those became model-based. global ocean instruments with no validation as to the risk. what happened in much 2018 was o pc. it was a fundamental objective to have the best availability time and bring in a new body ocean protection council. what they did even these numbers that have guidance the good part and i will tear up the page of strong. they are fine numbers. what is the extra probability
inform a number. 4 feet or 5 feet. this is the sea level rise shown as the guidance they look at the low and high commissions denial. we are not looking to be sure it is trending away. they assigned probabilities. pick a number. 5% probability sea level rise could exceed this number. in 1995, the chance is the sea self-rise. in 2050 he will not exceed 1.4 feet. 9% chance in the year 20/planning was our planning
number. we did not want to make any improvements some is 95% probility the sea level rise is below is 2.4 feet. november the the street for the buildings. the year of 2100 when you look at this. there is a 95% chance in 2100 the sea level rise is below 4.4 feet. >> what is the 2018 number? >> these are 2018 numbers. 95%. if you start looking at the half percent, if there were a school
orsive vision subter. they have be saying 95% is not enough. look at 99.5%. then we look at this column. if we look at 2.5 feet. guidance shows 99.5% probability that the sea level rise projection keeps going underneath the 3.5. >> that validated the initial capture environment. someone could argue it didn't have five feet. can the project accommodate
10 feet? sure. tracking. that is what the department imposed upon the project. every five years they have to tell us what they owe as a footer. it turns out sea level rise has not occurred. >> it gives me comfort. i think the master plan was well designed. we did receive accolades for both bcdc. thank you. >> your third-to-last slide, please pull that up. it showed the concrete barrier
versus the gradual slope. >> a couple questions. you have been to the chicago lake front. it is a fresh water lake that is not exposed to the same conditions. a couple existing grade that is flat with the blocks to break the tie. call in chicago the maintenance of the existing grade was high near. the south side on the southern part of lake how type. it had a lot of benefits. it was able to preliminarily
absorb the waives there. thissy it's more. what is the ideal for the resident 100 years from now between these two? what are the big trade-offs? >> it is property. if you retreat and you flatten the shoreline, the more you flatten the more options you have to put into use more nature base. we are showing sandy beaches. if i look at the exposure off the treasure island to exposure out at the open ocean.
there is a big difference. do you see 25, 0-foot waves do not see it because of the beach. the sandy beach 20-1. our navy created the slope of about two horizontal to one vertical. that is the slope. ocean beach is 20 to 1. marshes about 90 horizontal. the flatter i go, same exposure. the material is changed. is it possible to do this? yes, it is space. that is the reason for 303.
maybe there is a happy medium. 5-1 can be accommodated. just laird bamthe renovation of the perimeter bracelet need to go as high and looks like this. we could do exactly the same or .it is the thing above the tide. it is the tsunami and the surge that can be accommodated by flattening the shoreline. the tides with 6 feet of sea level drive which is essentially.
from 6 to plus 12. tidal flooding did not occur. strong flooding would occur. >> if i wear hat. it is a boom for biodiversity, for the ecosystem itself. if treasure island wins the lot to, thank you very much. it is very insightful. any other comments or questions from this body. >> yes. >> i know this is an irony comparing treasure island and we
know the group studied not only treasure island but san francisco in general. what will you say to people listening how safe treasure island is. i read in the data that you are better off on treasure island and san francisco. from your assessment to let people know we are having all the recommendations. that is great. how do you assess the risk of treasure island compared to mainlands san francisco? >> treasure island will be the model for a lot of the studies and plans that are going on not
just in the bay area but beyond. fortunately, they are not comparable. 150 is 150 years old. middle of 19th century we are creating ashore line going to be sure for the next 20 years there will be flooding. 100 year tide, you might see a lot of emergency services and starting to build up. >> any other questions or comments here?
thank you for all your work and educating us on this project yourself. we hope to be interacting with you a lot more as we move ahead. thank you very much. public comment or questions. >> we have two callers in the queue. i will open the line. >> hello, commissioners and staff. eric brooks with our city. commissioner, it is good to see you even though you can't see me. >> it is good to hear your voice. >> i don't know how many minutes i have got. i have a lot to cover. the key thing i am not hearing discussed at all is toxic and radioactive waste which has recently been discovered to be
sure pricingly worse and cleanup scandals that have arisen around the cleanup contractors that worked on the island. you can talk about your projections for sea level rise how high you need to build things. you need to build to 60 feet, not 20. that doesn't account for after a couple feet of sea level rise water mixes with the toxic and radioactive chemicals in the ground water and will spread those chemicals around. then if you add an second an eae and you have a tsunami from alaska. you have a katrina disaster on treasure island.
your projections of sea level rise need to bereorganized dramatically to introduce the concept. especially in light of the fact they are not properly cleaned up. at the hearing on february 8, held at the board of supervisors land use contamination. even the stated department of public health admitted there were problems with the cleanup records. until we get a real school on that, this is not add -- until we get a rescoop on that, this is not applicable. >> your time is up. next caller. >> bradley angel executive
director of green action for health and environmental justice. thank you for discussing this important issue. it is very timely. since i just have a short time. i want to flag a couple of things. there is a set back and how to protect the building and environment. there is radioactive and toxic waste on the island. some removed and some kept by the waterfront. this is a train wreck of a disaster. by failing to that's this in the presentation. i heard buildings. how about the radio use active waste our government thinks it is okay to leave by the waterfront. it can set back everything else
but unless the toxic waste is properly testrd removed it is a disaster for all of san francisco bay. the sea level rise projections discussed are wrong r.i refer you to calcoastal -- california coastal commission and documents that say there is a significant risk of sea level rise at 7.6 feet quite. i appreciate you discussing this. i would like to hear and not just in san francisco but the mill unions want to know to prevent sea leveling rise from gobbling up the waste.
>> good afternoon. members of the committee i am with mgm incorporated. we have been the geotechnical engineer on this project for a long time. we first started studying it in 003. -- 2003. what we are looking to present is an update on the program. we will start with a little bit of history and move to sort of what the implementation has been of the plan that was many years in the making how to stabilize this island to make it suitable to support the proposed development and of course assure the life and safety of the occupants.
a bit of brief history. treasure island was built by sand that was around the bay. we will get into the source of that sand. off the base floor and placing it in this shape on the island. where did that sand come from? this is the proposed development. it was a good exhibit to show that exact laying there before the island was built was the result of natural giomophic process of what was occurring on yerba buena island. it was larger. after the sea level came up it
was waive erosion and land slights out of in and depossit is on the baseboard. the island was built with the sand around here on to the shoulder existed. there was a big sandy possit is here. that was pay good foundation to build the island on. how did they do that? they put a dies on the floor that was the natural floor or the base floor that exists because of the depositions. then they were to pump the sand behind it until they got to the top of the dike and another dike
and another stage of fill until they achieved the elevation that was 13 or 14 feet above sea level. which they armored is the before. it should be noted in 1987, two years before the u.s. army corps of engineers placed another layer of rock which is what is there now on top of this. it was larger rock. that rock was very helpful in containing the island without slows into the bay. here are exhibits of the construction. this is a dike, pump dresses, they are pumping it in the
baseboard and tossing it. beef april. -- there are buildingsbeing bui. before we began the workout there, before we started, this is what it looked like. much of what we are talking about is related to the work done to date in the first stage. give us a perspective of the size relative to togom footprint.
the oils that exist the layering of the soil is very complex. there is work to identify precisely as to elevation and soil type. one thing to note on this exhibit if you can see this red line. that wobblevation of the floor before this yellow stuff is the pill. the base floor was here. because of the addition of that waste, the weight of the fill it squeezed this gray stuff such that the old surface went from this red line to about right there. for the purpose of this
presentation we oversimplified all of this. think of the layers of treasure island three categories. we have the fill placed on top of the show. we combined that to one thing. this is the natural bay deposit that is everywhere on the bay. they have the same mud that is less than 50,000 years. beneath that we have a stiff clay. this is suppressible. this is liquefiable.
what is the difference? this material will be in response to dynamic energy like an earthquake. it won't dense fifor static loads. we could pile dynamic tory range the article. this is just the opposite. you can shake it all you want. if we add any new loads it will squeeze the water out and go down. that is why on the previous exhibit this line went down as it added the weight of this fill. for the first stage of development, mavof this is
drudge trail and lower help. they are both home. what is the cure? we developed a program to identify this which we will go into. we developed a need to dense fior consolidate this through static loading. the situation before we started the work was that most of the settlement on the right side which is the you are babanena side. at the north ends where it is thicker to up 22 fit. it is still settling will 5
years after contradiction. the objectives of the program are to identify the sandy sale. to make it earthquake proof. to compress the layer underneath, the mud. when we add the fill we are elevating the island to guard against sea level rise. we are going to add weight. we are going to pre-compress so that we had no longer have to said you proceeds. we need to strengthen the shoreline so in an earthquake it does not laterally deform to the
bay. here is a graph cal depiction of the program. everything in the light yellow color is dense fid through dynamic energy which we will go through. everything that is cross hatched will be sure charged. temporary static mode to squeeze water out of that layer to precompress it. along the shore lime we have a very robust strengthening tram to protect the edge we have proposed near the edge such as the ferry terminal and marina
and only bites closer than the edge than the rest of the development. this is a lot of thought and collaboration went into this. we originally convened a blue ribbon panel in 2007 to validate the concepts that had been proposed. during the very long studty period and design process there were many collaborators and of course many public agencies reviewed and ultimately permitted. we each had to go back. the sequence of ground
improvement. first, we install bricks into the ground. a generic name. i thinksy better name would be straws into the ground. either is right. it is like a straw that has holes in it wrapped by a fiber. it goes into the ground and its only purpose is to fasilsaid sessescape of the water. it doesn't provide long-term benefit. it speeds the process. at the north ends we are 80, 85 years down the road and we don't want to wait decades. to speed it up we put in the huge witch.
that is the fell that was displaced. then we placed the static load on it and let it it is there for a while and monitored that. finally the edge treatment to arden the em prevent it from receiving that or -- to the edge to prevent it from receiving that. this is the wick rig. it pushes these 150 feet to the ground. the bottom of that young bay must then we follow with this program. there you have what vibrates the four columns and displaced the sand so you can see in this
cartoon make up sand is placed in there to create the suppression. in 2015-16 we mobilized this proprietary advanced technology from japan where they had experience, good experience, for many years. we needed to validated so we chose a test site for a series of sets. the test side is the four quadrants. we installed many, many strums in this area. we apply liver present edges of
energy to fine tune and two days the result. this is the test area. this is displacement and densification. it is hard to get a sense of the scale here. this piece of equipment is a large expediteter. you can get a sense of it a little bit. this was out of the winter of 1819, i believe. we were just going along doing this improvement over vast areas just to give you a sense that we had 50,000 of these probe elements just in phase one.
we have 7 million linear feet of wicks. end to end they would reach halfway across the country. then we followed up with the chaplain. 16,000 of he's. we followed with the tamper. the process leaves the surface loose. we had to prepare the surface to receive the new fill. you might note by the time we were finished. the elevation of the ground had dropped significantly. it was up here when we started. now we are down here. which was expected. then we surcharged. you can see the two large
temporary. we monitor with extensive instrumentation. different garths with instruments to monitor but also to the efficacy of the sale matter. the predictions were spot on because of the analysis we defor years before that. it was accurate. these surcharge with the amount of time necessary to achieve the settlement targets. again, we removed that material down to wherever we want the finish elevation of island to
be. you can imagine when we placed these they start out at certain elevation then settle down and we remove the upper portion and leave behind the elevation we want. if h the last step is deep soil mixes to protect the edge. this is on the causeway. the causeway got personal treatment. it is the ingress and egress point for the island and major utility corridor. we did the compaction extensively on the causeway. this particular machine has four augers each five feet in diameter. it mixes down to as much as 90 feet to give us that extra
protection that we need. the soil is now in place. we are not removing the soil. we are mixing it in place. that is the end of the major part of the presentation. we can entertain questions or talk about the other things that have come up. >> thank you. this was terrific. bob, did you have something to add to this? >> no, that is the presentation for now. >> director richardson has some questions? >> yes, thank you. we should make it a point to invite you regularly and at some point this topic is so important
that i think we have to let the education process so that everyone in san francisco can understand. in the last presentation, he mentioned that treasure island development sea level rise is a model for the entire country. that was very significant. your presentation you went through this lengthy process of the state-of-the-art technology that is not used anywhere in the country and world and outlined the des fiction, deep soil and you hear about the community concerns about what is going to happen. how do you say how safe is the
development of treasure island? i am reading the data but hearing from you and the experts, i think, is very helpful. if you could just answer those questions. >> yes, thank you for the question. the standards here are the highest standards that are promulgated today for safety and stability. there is a new building code that went into effect january 1 of 2020 which among other things increased the seismic demand on new construction. this meets all of those standards.
i would say in regard to your question earlier about how this compares to the embarcadero there is no comparison. the embarcadero was built a long, long time ago. similar to treasure island it has fill, it has fill that was placed on the bay floor. these techniques and safeguards were not in place. they didn't know about it back then. it is much more seismically susceptible than treasure island. treasure island is built to the very highest standards today in terms of building codes and regulatory requirements. the work that has been done here
to stablelize the island and analyze this, you can imagine i love to talk about this. i could talk for longer than anyone is interested. it is published and well recognized internationally. >> thank you, sir. >> i don't have any questions, but i have praise. thank you for making it so clear, especially to lay people like us. it was a very clear presentation. it gives us insight on all of the different things going on geotech nickly. thank you very much. >> thank you very much. i will make one more point.
very quickly. it is valuable to note that all of these activities are extremely well recorded and documented and there is a database that tida has access to. this green area is where they were. it is not a solid green area. it is made up of hundreds of thousands of dots. every dot if we click on any dot, what we have is information on that particular wick.
lots of data on everyone of these dots. each one represents a wick that went into the ground. there are 70 million feet of these wicks. you can see all of the various attributes of each wick. this is something that will be kind of a living record for the future so that we know where everything is and we know a lot about everything. similar to the wicks, we have one for the compaction. same sort of thing. we can go in here and click and learn a lot about when it was done and many pieces of information about it.
lastly, just to give a sense of the mixing which is that which hardens the edge and gives us protection about sea level rise and wave action. let me turnoff this layer and go to this one. we have multiple methods of stabilizing. in some areas there was no room so we did resort to structural solutions. you can see we are nearly complete now at 98% complete
with that work. if we want to know where each of these are, these are sheer walls buried in the ground to give rigidity to the edge. to stabilize it from lateral movement. with that i will stop sharing and stop talking. >> i think there was a question. >> this is so impressive to see the great work you have done. if you could have done something
different or the money to allow you to do something with new technology, what would it have been? >> that is a great question. i think in terms of the methods applied, i don't think we would have done anything different. further sequencing in terms of sort of preparation for unknowns, we did have some delays related to the inability to install the deep soil mixing. i hate to do this but i am going to pull it up again. these columns, as i said there are 10,000 of them. see where they are red here? that is because when we drilled down, when the contractor did,
we hit that old dike that we talk about in the very beginning. it was very difficult. in some cases we couldn't get through it. we had to sort of quickly design and implement a structural solution which is much, much more costly to take the place of the deep soil mixing that didn't get to the design depth. i think that we lost a lot of time in that. we probably would have been better off having some designs in our back pocket. there is nothing you can do. it is what it is. if we would have anticipated it we could have johnny on the spot and implemented that.
i can't think of anything else. i will tell you that when we had the rig from japan to do this. we learned an awful lot. that is one thing we would do again on every project. in terms of which laters were identifiable and what amount of energy was optimal for densifying the sand? that was a god send. we had the luxury of things that tida and the project developer and the area was carved out for us and we had free reign to do what we wanted. being able to do a full-scale test like that is just invaluable. >> thank you.
>> any other questions from this body? >> i would just like for you to maybe summarize for us without these geotechnical improvements, without any improvements to the island, in fact, the island would be forward in being exposed to the geotechnical events? >> very much so. there are two distinct issues, geotechnical concerns here. both of which would have not been mitigated would result in unacceptable performance.
one is as you mentioned the liquid. that is seismic, not static. when the big one comes, which it will, that fill layer would liquefy. it turns into a liquid. it would have certainly slowed laterally into the bay. the improvement with the vibration is to eliminate that concern. the second concern is when we plan for sea level rise, we have to elevate the island a bit. more so as we go northward. that adds weight to the island
and would induce a new round of settlement. that compressed layer under the under theliquid layer. that would be static settlement. all of the surface improvements would settle. you could put every building on piles and the buildings wouldn't settle. plaza, utilities, park facilities would settle. with this comprehensive mitigation program to address both of those concerns. related concern is the lateral stability of the shoreline. it would only be triggered in a seismic event. that is yet a third concern that
we have to mitigate. >> thank you. >> anyone else? >> thank you. we need to bring you back again. >> thank you, board members. i have to say, you know, i appreciate the kind words. i just get to be the mouthpiece. there is a whole team that did the real work. they are very, very passionate about this project. i wish they could all be here. >> we are passionate, too, and you made a great presentation which is clearly understandable. thank you again. >> please give our thanks to your team on our behalf. thank you very much for this.
with that do we have any public comment? >> yes, we have two callers in the queue. i can open one. >> welcome, please go ahead. you have two minutes. >> i am james pepper. i am looking at the 1994 u.s. geological survey deep instrumentation array at the treasure island naval station. the lateral stress was six times that of -- because of the sand. the effect of the earthquake was six times that of other areas in the bay area. i hope you all address that. it is in the name of the overall report as being the october 17,
1989 earthquake. ground motion and ground failure report. the other thing when you were pounding away on the causeway. did you all file a permission to do that with the fish and wildlife and the marine mammal commission? that is the area where the seals feed. >> sure. may i address the question? >> yes, please. >> with regard to the postponement. the u.s. gs seismic array north of the stage one area and towards the west age of the island. it recorded ground motions and other less significant
earthquakes. the seismic response, lateral acceleration that occurred at the surface of treasure island was significantly greater than yerba buena island because of the amly fiction from the bedrock. in perspective, the peak down acceleration recorded if i recall correctly was .12g. that is .12 times acceleration of gravity. in that range. the design that we design to is four times that. .460 because we are designing for a much higher intensity see haven't. we are between the hayward and
san andrea fault. we are beyond the measured ground motions in the bay area. as to the second question about the causeway. we have said in the beginning that sand needed to be dense fid with dynamic energy. there are two ways. one is impact which is what the caller is referring to. the other is vibration. we chose vibration and not impact. a significant part of the region is what we stated. we didn't want to have effects beyond the soil that was being improved. to put that in perspective did he have cassie of that system is
only about 6 feet away from the vibratory recolumns in the presentation. it only improves the specific area where it is applied. unlike impact energy which has waves that propagate much further out. >> one more caller. i will open the line. >> good afternoon, commissioners and staff. eric brooks with our city san francisco. i respectfully have to take issue with the idea that this plans is a model for the united states. i think that if that is the case that is the fact the infrastructure plan anything the united states is bad and lacking. i will use sea level rise which
affects this item as an example. what i was not able to say in the previous item the projections of sea level rise of bradley angel of 7.5 feet are exceeded by those of former nasa scientist james hansen who said we could get five to seven meters of sea level rise by 2100. meters, not feet. what that brings to crystallize all of this. in none of the projects that i have done comment on the environmental impact reports have i seen the standard engineering practice for project safety of 100% margin of error beyond worse case scenario. that is standard practice by engineers. if we use 100% margin of error
on sea level rise your standard would be your 5 feet plus possible 8 feet of inundation from tsunami you need to build for 26 feet. under bradley angel 31 feet. james hansen it is up to 6 feet -- 50 to 60 feet. the fact in regard to sea level rise the plans is dramatically inadequate even by bradley angel's standards which are a safe metal ground. i have to assume 100% margin of error is not in item 5 either. the sea level rise what level of permanent intundation would change the assumptions in item 5 and make them have to beredone. a lot io more work needs to be
done not including the toxic and radioactive chemicals. >> thank you your two minutes is up. thank you. there are no more callers in the queue. >> i think that mike had to leave for another meeting. this brings to the end this committee meeting. any other item on the agenda? >> item 6 discussion of future agenda items by directors. >> the directors have any future agenda items to bring up? hearing none. >> i would like to circle back to the work we are doing with the requirements of san francisco county and the state permitting energy zero and some of the other districts that we
have spoken about before. >> for me to be clear it is on the the energy you want to bring up the san francisco standards on energy? >> the county use of not just energy but the entire sustainability goals, energy zero. >> if that could be a future topic. how we compare to the san francisco requirements or goals. >> anything else? hearing none. we can add june. this was very informative session. really appreciate this. you did a wonderful job. thank you so much. >> thank you everyone.
>> thank you. >> the hon. london breed: good morning, everyone. let's get right to it. this is not unfamiliar territory for us. many of you remember, when i started at supervisor for district 5, 4-20, although it has been a tradition in san francisco for many, many years, there was one year in particular that was a little different than most years. we saw thousands of people come from all over the bay area to robin williams