July 12, 2024 Sand Studies Commissioner Working Group

Yes.

Well, I see there’s a lot of people joining us.

That’s great.

It looks very hot where Ben is.

They do not yet see Greg up.

There’s Greg, and it looks like Andy Gunther’s having a little

trouble connecting.

Oh, he’s connected now.

He got connected.

Looks like Barry’s there.

So I think we have Erica.

Bill, There’s Bill.

OK, Bill, it feels so long since I’ve seen you saw him yesterday

and the day before.

OK, I think we should probably go ahead and get started.

We got a pack schedule.

So Pat, if you’d like to open the meeting.

Yes, Well, welcome everybody.

My name is Pat Showalter and I’m the chair of the Sand Studies

Commissioner Working Group.

And we are here to review some really new information that has

been put together and, and, and kind of ask questions and, and

absorb as much of it as we possibly can so it can be used

in the policy making process.

And I, I wanna extend a, a just a warm welcome and thank you to

everyone for taking part and particularly to the scientists

who have made this information come together.

I know it’s having worked in the Bay for many, many years.

I know that understanding of the sand budget has has not been

something that there’s a lot of information on over the years.

And so I’m really excited to, to to be here to learn more about

this.

So with that, I think the next item is to just have a roll call

of our, the commissioners who are official members, members of

this group.

We’d really, we’re we’re glad for everybody else to be here

and we, you know, depending on how it works, we’ll run this

fairly informally so everybody can ask questions as we go

along.

If it if that doesn’t work, we’ll we’ll have to change to a

public comment period, but I I doubt that’ll be necessary, but

we’ll see how it goes.

Anyway, I’m Pat Showalter and let’s have a roll call for the

other commissioners, Commissioner Barry Nelson.

Barry Nelson, Commissioner and member of the working group.

Commissioner Andrew Gunther.

Hi, Andy Gunther.

I’m a member of the working group and now in BCDC because

I’m a member of the regional Mariapoli Control Board and

chair Pat Showalter here.

All commissioners are present.

Eight.

OK.

And we’ll just quickly introduce the BCDC staff.

And I think what we will also do is since there’s a fairly large

group of folks, if you can, oh, the BCDC staff and if everybody

else can put their name and affiliation in the chat, that

would be really helpful.

Yes, I think if we went to individual introductions, that

might take us a while.

And so I’m Brenda Gaten, I’m the sediment program manager for

BCDC.

Greg, you want to go next?

Sure.

I’m Greg Scharf.

I’m general counsel for BCDC.

Harriet.

I’m Harriet Ross, the regulatory director.

Pascal, good afternoon.

I’m Pascal Samoy and I work in dredging and sediment

management.

And then Jaime, looks like you are also here.

Yeah.

Hi everybody.

I’m Jaime and I’m also working with the sediment team here.

Great.

And then Kat, of course.

Hi, I’m Kat.

I support the sediment team.

I’m also running the Zoom today, so if you have any technical

difficulties, please feel free to message me.

Yeah, and Kat is our main communicator on a lot of these

things, so if you see emails from Kat on this subject, please

open them.

OK, so everyone else, if you can put your name and affiliation in

the chat as a way of saying hello to your colleagues, that

would be great.

I’m sure we’ll hear from many of you during the meeting today.

We have a couple of independent science panel members here with

us and some members of the S TAC, the SANTAC Technical

Advisory Committee.

We have the Sand Miners industry representative as well as

members of the public.

Oh, and I also missed Mark Zapatella, who’s with BCDC.

Sorry, Mark.

You’re on mute, my friend.

OK.

He’s Mark Zapatello.

He is one of our legal counsel emeritus and still working with

us at BCDC.

Thank you, Mark, for being here.

OK, so there’s there’s a problem with the link I can’t get on.

It says another meeting’s under progress, and that is our friend

Jim McGrath.

Try leaving the meeting and rejoining.

Jim.

I’ve done that.

Oh, I will.

Kat, can you e-mail?

Do you have Jim’s e-mail?

Yes.

Yeah, But you are currently in the meeting, so I think it looks

like you’re here on our end.

Yeah, I’m.

I’m there on phone, but I can’t get on on the Zoom call.

OK, I’ll reach out to you.

Yeah.

Hang tight, Jim.

We’ll see if we can get you into the actual meeting.

Thank you.

Anybody else having problems?

No.

OK, OK, So just I’m gonna briefly give a presentation at

the moment to kind of set the context for this commissioner

working group and for the public, because I recognize that

not everybody came to the last commissioner’s Commission

meeting where we did present briefly on what our plan is

here.

But this commissioner working group is to dig into the science

and understand what we’ve learned over the last three to

five years and give the opportunity for the

commissioners and the public to kind of catch up with the

different studies and hear more in depth from the scientist and

the Independent Science panel what they did to find this

information, What it what implications it has for the Bay

sand system and also potentially for sand mining in the future.

We anticipate having permit applications for additional sand

mining in 20 end of 2024 through 2025.

Their state lands is on the phone and they’re doing a sequel

document currently for the same.

So we’re trying to make sure everybody has an opportunity to

really learn about this new and very interesting science.

What this is not, this is not a meeting about permitting.

It is not a meeting where we’re really focusing on the mining

activity itself, but really the studies to make sure that we’re

all on the same same page to the best of our ability.

So if you do have questions or thoughts about these different

kinds of science that’s been done, we do encourage folks to

ask questions because we want everybody to feel like they

understand.

Well.

And so with that, I’m going to start with my presentation.

And I also I’m having a little bit of an allergy attack today.

So if I’m a little foggy or scratchy, I apologize, but let

me go ahead and share my screen.

Let’s see.

Come on baby, let’s share the screen.

OK?

And should be there 1 moment.

We’ll get into presenter mode.

Maybe we will, maybe we won’t.

OK, and now I can’t see you.

So Kat, if you can work for hands for me, that’d be really

helpful.

So I oh, this is anyways, I’m going to share the screen.

We’ll just excuse the notes.

So sediment program manager for BCDC, basically there’s a bit of

a project history here on sand mining.

So mining has occurred in San Francisco Bay at least back to

the 1930’s.

The BCDC has records on sand mining back through the 1970s.

BCDC was created in 1965 S Prior to that we really didn’t have

any permitting or reports in on what type of mining was taking

place or where.

In the early days of sand mining, prior to the 1990s,

there were multiple small sand mining companies throughout the

sandy areas of San Francisco Bay.

In the 90s, they were consolidated into three

companies.

So Martin Marionetta at that time was Hanson Aggregates.

They consolidated most of the lease areas in the central San

Francisco Bay.

Lind Marine was Morris Tug and Bard’s, also Jericho products,

but they have taken over or changed names.

Reincorporated, not sure exactly which Bill can clarify, but they

are mining primarily in Sassoon and then Sassoon Associates is a

joint venture of the two companies.

Throughout the history where we have documentation from reports

of sand mining from the miners themselves through the 19 four

from the nineteen, 1974 through 2023.

This is basically a histogram of all of the mining that we have

documentation of.

There was some mining off of lease areas that wasn’t

reported, so this may not be all of it, but this is generally

what we have in the reported record.

And you can see that the highest level of mining took place in

the early 2000s, which is primarily the.com years, where

there was a very large amount of construction going on in and

around San Francisco Bay.

It dipped very significantly in the mid 2000s due to the Great

Recession and the change in construction happening.

But also as we’ve noted at other times, there was permitting

going on between 2000 and two, 2013 and 2015 that there was

some related reduction as those permits were getting close to

expiring.

And then you see the sand mining coming up again through 2018 and

starting to drop off again in the last few years.

It’s really important to note that sand is mined in San

Francisco Bay primarily for construction and so construction

aggregates.

So you see a trend that follows the construction industry

because that’s what this material is used for.

In 2013, the miners requested 2.2 million cubic yards of

mining total from the different agencies and they submitted 4

applications, one from Central Bay, one for Sassoon Bay Channel

which is the Sassoon Associates, one at Middle Ground Shoal by

Lind Marine and one at Middle Ground Shoal for Martin

Marionetta and the request for his 410 year permits.

In 2015, the Commission along with the Water Board, State

Lands Commission, the Army Corps of Engineers all issued permits

for sand mining.

BCDC and the Army Corps permits are the most aligned because

BCDC acted third in the in the ranking of the permits being

issued in the Army Corps acted after BCDC.

So we worked very hard with the minors over a three-year and

negotiated a reduction in volume, but the reduction in

volume, so it came out to 1.42 million total throughout the

region.

But there is an allowance within BCD CS permit that if the miners

do not mine their total amount in any given given year, they

can do additional mining within that volume in the following

year.

That has not occurred.

We issued the Commission issued 3 permits, one for Central Bay

to mark Marionetta at 1.14 million, one to Sassoon

Associates for 185,000 cubic yards and the last to Lend

Marine at 100,000 cubic yards.

You know, you’ll note that the one for Martin Marionetta for

Middle Grand Shoal was not issued because that permit was

withdrawn.

There was application was withdrawn.

There was no mining that had taken place on Middle Grand

Shoal for over 10 years.

And so it was determined that that lease, a permit was not

necessary.

The issues the permits were issued for 10 years as

requested.

They required studies which included water quality

monitoring to make sure there wasn’t an impact to the water

quality from mining, a benthic habitat study and the studies

that are subject of this Commissioner working group,

which is the sand transport sand budget and the potential impacts

of mining to the sand system within the Bay.

The miners contributed $1.2 million towards these studies,

which is a remarkable amount and really did allow for us to do

this, pardon the pun, deep dive into the sand transport and

budget within the region.

The permits did require mitigation, which included

removal of a specific amount of Bay fill to make up for impacts

to the subtitle area, but also to address essential fish

habitat issues with NOAA Fisheries installation and use

of fish screens on the intake, water intake lines to the system

and a reduction in volume at 2.

Two of the lease sites.

And I’ll speak to that in just a minute.

So the Central Bay lease areas are these and there’s basically

4 leases, but there’s nine parcels.

So some of the parcels, if you look closely you’ll your screen,

you will see that some say for example, seven O 9 N and there’s

another which is seven O 9 S.

Some parcels make up one lease 3 parcels will make up one lease

area.

For example, this area is deeper than the other two areas.

And the mining here takes place in depths up to 90 feet.

This area right here, this triangle piece.

I think you guys can see my my arrow is considered raccoon

straight.

There is no mining that takes place in this area.

I think that it’s probably too deep and too swift to actually

have mining activities taking place.

These are all state lands Commission leases and there’s

two types of sand that are mined in this vicinity.

The coarse grain sand which you see on the left of the screen,

that is coarser grain material which is often used in concrete,

and this finer grain sand which comes primarily from the

Presidio Shoal area, which is used more for backfilling of

trenches and other uses.

When you break down that overarching graphic of the

mining that’s taken place over time, this shows what’s happened

since 2000.

So different time frame, but 2000 to 2000.

Oh, I’m sorry, the numbers are wrong.

No, the numbers are right, 2000.

So the last 20 years of mining, which is the most relevant.

At this point, 2000 to 2023.

Also notice on the Y axis that the scale changes in the next

three graphs that I’ll show you, but at 1.4 million is about the

maximum shown on this graph.

And you can see the difference over time in that mining trend

for Central San Francisco Bay.

And again, the maximum allowed for mining here is 1.4 million

as of 2015, which is about here.

I put it.

Probably should have put a dash line on there for you.

Moving over to Sassoon Channel, the primary area that’s mined in

this area in this lease is here.

It’s also important to note that BCDC does not have jurisdiction

over this part of the lease area.

So we would not have reports on this, but I don’t believe mining

is occurring in this area.

So in this area, that’s a little shallower mine, mining happens

in two depths of up to 45 feet.

These are again a lease by State lands made-up of two parcels and

this is primarily fine grain sand.

And here’s the histogram for this and notice again, 22,000 to

2023.

the Y axis now is gosh is a little different.

But what we’re seeing here is the trend changing.

So this low point during the the permitting.

And I think this lease was almost out of volume during the

permitting.

But then it ticked up again.

And you’ll notice that this is higher than it is at Sassoon.

You’ll I mean middle ground.

You’ll see middle ground has dropped off quite a bit.

And the reason for this is not only are they the same kind of

sand, there’s more volume authorized on this permit

185,000 per year, but also because middle ground Shoal,

it’s shallower and considered potentially a more sensitive

habitat, the agencies adjusted the volumes to be more volume

available to be mined and Sassoon channel versus middle

ground Shoal.

So here’s middle ground Shoal and this this smaller lease

area, I always think it looks a little bit like a bird head.

One of the important things to note about this lease is that

while it’s a large lease area, you know when you look at it

visually, the mining really only happens in the southern portion

of the lease because part of it is actually intertidal or even

super tidal.

So the area that’s deep enough for the miners to mine is this

southerly portion.

So in this area I think we have up to 30 feet deep, but actually

much shallower in some locations.

It’s an adjacent to an island.

This graphic doesn’t show the island, but it’s right here.

This is a privately held lease, not part of State Lands leasing,

but State Lands has analyzed it as part of the Sequa NEPA, the

Sequa document.

And then again, it’s that fine grain sand very similar to

Sassoon channel.

And here you see the permitting 2015 and the significant

reduction in the mining volume at middle ground less than

50,000 in the last several years.

And a lot of that is due to the pushing the operation more to

Sassoon associates to deal with this potential effect to that

shallower habitat which has potential to be spawning grounds

for smelt.

So briefly moving on to the mining equipment.

There are two sets of mining equipment, Lindh Marines.

Their barge holds about 1400 cubic yards of sand and Martin

Marionetta is more closer to 2100 cubic yards of sand.

Just gonna quickly run through this.

The sand is pumped up onto the the mining equipment through a

drag head.

This is Hanson’s equipment.

This is the drag head.

It has a fish screen on it to reduce entrainment of fish from

the water being pulled in.

The sand is pumped across the chute running down the middle of

the barge and sand is self sorted and comes off over the

side of the chute into the barge and area and sand that is too

large or larger pieces is is pushed off the barge back into

the Bay.

Here is a close up of the Martin Marionetta barge or equipment.

So here’s the hydraulic head again with the fish screen right

there mounted on the pump coming on board.

Here’s the drag head with the grid across the bottom.

These are approximately 6 inches by 6 inches, which helps keep

large items out of the drag head.

This drag head is put 18 to 3 feet into the sand.

This is Lynn’s suction pipe.

So this is more of a stationary dredge where the pipe is

inserted down into the sand.

Here’s the fish screen.

And I always think of this more as kind of like if you’re

drinking a chocolate malt and you drink with a straw, the the

sand kind of goes in like your chocolate malt into that straw.

Versus this is a little bit more like a vacuum cleaner being

dragged until it hits this type of sand that’s desired.

And then the barge does stay stationary for a period of time

to collect that sand.

So some quick notes about the the mining activities for those

of you who are really familiar with navigation dredging, I just

want to note a few differences.

So mining here again is for construction aggregate.

It’s not for navigation, although Sassoon channel

dredging or mining does happen adjacent to and I believe

partially within the federal navigation channel.

That’s not normally dredged for navigation, but it is within a

federal navigation channel.

It’s not generally considered beneficial reuse under the LTMS

lexicon because it’s not a waste product being reused as disposal

of dredge sediment is, but in fact a resource being mined for

its specific use.

Different than navigation dredging mining occurs year

round.

There’s no work windows for sand mining, but there are fish

screens on the intake pumps to reduce impact to listed species

and that was per biological pinions from Noaa’s Fisheries

and US Fish and Wildlife Service with an incidental take permit

from California Department of Fish and Wildlife.

The mining location is based on the leases and the mining

activity is based on the grain size of sand desired.

And again, as I mentioned earlier, Central Bay is

primarily coarse grain sand with some fine grain and certain

Shoals and it’s most appropriate for use in concrete and asphalt.

And then Sassoon and middle ground are fine grain and

appropriate mostly for trench filling and other uses.

And then mining doesn’t occur to like a specific depth or area

like navigation drudging does.

But the mining does occur often and regularly in the same area

because of the the selection of the grain size that is located

in the lease areas in those areas based on sand transport

and the sand system and what is is bound where to make it

simple, just a quick couple of quick slides from some of the

studies which you’ll hear more about I think another day.

But you can see here’s 1997 version looking at some

bathymetry.

And this is the area that was examined for one portion of the

study.

And what you see here in the same area is a bed lowering.

And this is point knock Shoal by 2019.

Another quick look, here’s another example in 1997.

Here’s your examined area 3.

And then here’s the examined area again, bed lowering and

Shoal disappearance was the result of one of the bathymetric

change analysis.

But it is important to note that as I said in the previous slide,

sand tends to sand mining tends to occur in the same area

repeatedly.

And so you would expect to see these localized, excuse me,

effects where that grain size can be found.

I think I’m almost done here.

So on our study process, just real quickly switching gears,

the funds were provided that $1.2 million.

We have the SAN technical advisory committee who developed

management questions, study scopes, worked on a request for

proposals and reviewed proposals.

And then our independent science panel members who reviewed the

proposals, reviewed revised scopes, worked with the teams to

really hone their study development and then reviewed

the completed studies and the findings and they developed the

findings report with Santech who wrote the report with them.

The questions that the I just put the questions up for this

from the Sand Technical Advisory Committee, which was the main

focus of these studies.

So is sand mine, is sand mining in existing areas at permitted

level, permitted levels having measurable or demonstratable

impact on sediment transport or supply within San Francisco Bay?

There’s a question which is what’s a sustainable number,

which I believe is about sustainable number of mining and

what is substantial depletion considered.

The second main question that was asked is what are the

anticipated physical effects of sand mining at the permitted

levels on sand transport and and supply within San Francisco Bay

and the outer coast?

What is the impacts to active sands and the consequences to

beaches and tides that it feeds?

What’s the impact to relic sand, which is how much is the volume

and where is it?

And are there other feasible sand mining approaches to

consider in San Francisco Bay?

And should there be a modification of a volume and

site and site and conditions, sort of a three Fer question.

So the folks who’ve been involved for the last several

years, which I will be eternally grateful to because this has

been taking a village and a lot of people’s really good strong

thinking on this work.

The state Coastal Conservancy managed the studies and tracks

and the funds, which I can’t ever thank them enough.

BCDC was a member of the SANTAC and worked with the Coastal

Conservancy to keep the process on track.

The Coastal Commission, State Lands, Army Corps, Water Board,

National Marine, Fisheries, Cal.

Department of Fish and Wildlife, Bay Keeper Martin Marinetta and

and Marine.

We’re all members of the technical advisory committee,

the Independent Science Panel.

We have a couple of the members here today who will present

next, which included Bob Battaglio from Environmental

Sciences, Craig Jones from Integral, Jean Lazier from UC

Davis, Dave Schulhammer, USGS, and Paul Work from USGS.

So great group of folks doing some really good thinking here.

And lastly, our research teams, I’m not gonna read all the

names, but there are three majors, the sand budget, supply

and morphological chain and transport analysis.

Big team there from actually international team.

So you can see the organizations that were involved with that

one, the sand transport modeling and the sand Providence work.

We have sand Providence where Zach is here today, as is

Matthew.

And they’ll talk to you today about that project or that

study.

And I’m gonna stop pretty much there because Next up after me

is the independent science panel members introducing their key

findings.

And with that, I’m gonna stop sharing my screen.

That was a quick, quick, quick tour.

Well, thanks, Brenda.

Hey, this is Bob Vitaglio.

I’m one of the ISP members that I think are up next, and we’re

gonna try to move fast.

Hey, Dave Schulhamer, are you online?

Am I supposed to share the presentation or are you?

And while you’re working on that, what’s that?

I’m sorry, we’re working on that.

I’ll share it.

OK, Pat, go ahead.

Commissioners, do you have any questions or any items that you

wanted to ask while I ran through that very quickly, I

know you saw a version of it a couple of weeks ago.

Brenda, I do have one question.

I, I’ve been reading the, the briefing documents you sent our

way and one of those key, and maybe this is maybe this is

something that Bob’s gonna get to.

But that briefing document you talked about rates of

replenishment, but it didn’t have time frames for that

replenishment.

And you, your some of your slides kind of got to that.

But I was just trying to get a handle on what the annual

replenishment rates were and I didn’t get that from all the

parts of that document.

So if we’re gonna get to that later, fine.

But I thought I’d throw that question out now.

Yeah, I think the answer is it is variable depending on the

different locations.

And that will be the subject of another meeting when we bring

some other folks in.

Although I don’t know if Bob or Dave, you want to respond to

that at this point.

I’m sorry.

I was trying to figure out how to load my presentation.

So I missed the question.

I, I, I think Dave is, was probably listening and Kat, I’m

going to need help becoming presenter.

I don’t, I don’t think I can do that on my end.

I think I’m not in control.

If, if you look at the bottom and see share screen, it’s a

little green box.

That’s, that’s all you have to do.

OK, starting off very embarrassing.

Now you’ll know why we don’t know which way the sand’s

moving.

I, I, I was, I just had a quick question about really the

difference between fine sand and coarse sand.

How and, and generally not, not just obviously there’s a size

difference, but in terms of the deposit, the the deposit size, I

would just assume that there’s a lot more fine sand and there is

coarse sand.

But I just wondered about that.

Yeah, I, I don’t know if you want us to jump in and I, Barry,

I’m sorry, I didn’t catch your question, but I think that’s

right, Pat, that, that we have more of the finer sands.

The beach sands are kind of in the middle between the two

images that Brenda showed, which I really appreciate.

It’s it’s nice to see those pictures.

Brenda, we, you showed a know if you wanna show it again, the,

the coarse and the fine.

But, you know, the course is really old.

I think the that really coarser stuff.

I I don’t think it’s moving that much through the Golden Gate.

That’s my opinion anyway.

Beach sands are smaller than that.

Yeah, I’m not gonna show it again right now.

I can pull it up again later.

I see Dave’s got his hand up.

And also if the miners want to answer that question from their

perspective too, I think that’s also welcome.

Yeah, Dave, I was going to go back to Barry’s question about

the recovery rates.

They’re expressed, I believe, as in a percentage of recovery,

essentially how much of the remove sand is returned during

the period of time between where we had the bathymetric surveys.

Basically, I think this was done just because there’s sort of

averaging over that period.

Now those numbers could go back to the raw data the

investigators had and come up with an actual number of, you

know, cubic yards per year on average of going back into the

mining area for each of the lease areas, I believe and the

way the day is presented, but I don’t recall it being in the

report, but the results could be presented that way.

I think we were looking more at the percentages, the rates of

recovery as relative to how much is coming in and how much is

going out to compare it that way.

Yeah.

And I will also just add for reference that we have I think 5

depending on the lease area, 5 Series of bathymetric surveys.

So we started, maybe there’s only four, we started requiring

them in 2004 and they’re required every five years.

So we have a series of five year surveys and then we did one

survey between 19 or excuse me, 2018 and 2019 because we have

this really interesting water year while we were working.

I think that was the right time frame where we did one in a very

specific set of bethematry to do a quick analysis at the request

of the independent science panel.

I want to make sure that the miners also have an opportunity

to ask questions.

So are there any questions at this point from from the minors?

I will just I will just this is Eric Aguera with Marty Marietta.

And I will just act a little bit of as a moderator because we

have a big group here and I think it would be good if we

have Mike Bishop from Marty Marietta basically expanding a

little bit more on your question on the grain size and what we

use that sand for.

So Mike, hi everybody.

So, yeah, so the fine sand is is typically mined off Presidio

Shoals on the South side of the Bay.

And as Brenda said, it’s, it’s typically used in foundation and

trench backfill.

It’s a very, it’s a very uniform sized sand.

And and I I describe it as soft and on the north side of the

Bay, which is point NOx etcetera is there is, is our coarse sand

which predominantly as Brenda said goes into into concrete.

You know, there there the the difference in size is really on

the top end of of the sand fraction and on the on the

bottom end, which is what you know would be silts and and fine

sediment.

Neither neither, neither sand has much of that.

You know, we measure it on, on graduation sieves and the 100

mesh is, is still a fairly large Staley fairly large sieve at at

70 microns, 75 microns, something like that.

And you know the the these two sand deposits just don’t have

that really fine fraction that is silts and which, which

generally is, is is dredged in maintenance dredging.

Yeah, the two sands are quite different if if just to the

naked eye and hopefully that will answer your question.

Yeah.

So it sounds like what you’re saying is that the, as somebody

mentioned earlier, the, the, the sands, the fine sands that

you’re, you’re mining are very well sorted so that they’re

already ready for a specific use in construction ’cause I know

you use different, I don’t know too much about this, but I do

remember that you use, you use different grain size for

different uses and sorting sands into different grain sizes is,

is expensive.

So, so I get the impression from what you’re saying that that

these, these are sort of pre sorted, these are very well

sorted.

So that’s, you know, that makes them valuable.

Is that, do I get that right?

That is that is very correct.

Mother Nature does a great job at at sorting out this sand and

the coarse sand basically is a is comes out at a concrete

specked sand.

We have to do very little of it processing onshore and and

fundamentally really onshore.

All we do is is give it a bit of a wash with some fresh water to

try and lower the salt content.

Of the sea water that we mine it out of.

But you know, and and that really lends itself to where we

mine is physically where the currents etcetera allows this

sand to drop out and or to have dropped out in the past.

So you know, there, there is particularly with the coarser

grain which is the concrete sand, which is, is, is the

higher demand of sand is is very specific where we where we can

get that sand from.

We can’t get it from just anywhere in the Bay.

Yeah, no, OK, thank you.

You know that does that’s a great answer.

I appreciate it.

Any are there any other questions?

I’m kind of looking for hands raised and not seeing them.

I I think Ben Butler from the Marine.

Yeah.

And we’re about 10 minutes behind schedule now.

So, Bill, if you can be brief, please.

Oh, OK.

Sorry, Rinda.

Have I ever been anything but brief?

Yeah.

So thanks.

Bill Butler with Lynn Marine.

So thanks, Mike, for your description on the sands.

I would just also like to add as far as uses are concerned, the

the fine sands while while they are indeed a little smaller size

on the top of them, they’re still very clean as Mike

indicated and used not only just for backfill, but our stands

that we mined out of the Sassoon area are used quite extensively

in, in asphalt.

It’s, I think it’s just also important to point out too that,

you know, not not all sand is, is the same.

For example, this isn’t like beach sand that we’re mining.

When you go to the beach and you see, see sand like that, that’s,

that’s very different than than this sand.

Our sand contains a range of sizes that, that make it

valuable for construction as well as being, you know,

durable, durable and and fairly clean.

So I just wanted to make that distinction as well.

Thank you.

OK.

And I see Richard Gunther has a question.

Thanks.

Do we know how much sand in these different categories is

used in the Bay Area?

Commissioner Gunther, I’m going to have to ask you to hold on

that question because this is really about the science and

we’re behind and I would like us to continue and not get into the

use of the sand right now if we can, please.

OK, that sounds good.

Why don’t you keep going?

So who’s next?

I would like to introduce Dave Schulhammer and Bob Battaglio.

OK, I think that’s my prompt.

If it’s OK, then I will push the green button and share my

presentation.

Yes.

OK.

Hopefully I can do this.

This is kind of OK.

Where’s my presentation?

Here it is.

Let me go back to the first slide and you’re all set.

There we go.

OK, OK.

And so as Bob and I agreed to a few minutes ago, I will start

off here.

This is Dave Schollhammer of the Independent Science Panel and

I’ll take care of the first few slides.

Basically, my role here is to be the warm up act for Bob.

We’ll finish up the presentation.

So on the next slide, Bob, the Independent Science Panel is

composed of five of us, myself, Bob, who is a expert in coastal

sediment transport and has been working in San Francisco Bay for

a long time, as have really all of us.

Craig Jones, another coastal engineer, has done quite a bit

of work over the decades with sediment transport and some

modeling work.

John Largier at UC Davis, who’s really the, the, the expert at

what’s going on, especially at, at, at the Golden Gate myself,

my background has primarily been studying fine sediment transport

the the finer material, but with some sand thrown in.

And finally, Paul Work, another coastal engineer with the

formerly with the Geological Survey, who also has spent,

spent a career studying sand transport.

So we are the members of the Independent Science Panel who

all contributed to developing the studies.

We’ll be talking about and writing the summary report that

Bob will be talking about on the next slide.

Bob, we have the list of the studies that’s already been

mentioned and we’re gonna go through these briefly.

So this is sort of an outline of the rest of what you’re going to

hear from us.

The SAN budget study and modeling studies.

I will explain and then Bob will very briefly mention the

fingerprinting study cause Zach and Matt are here to describe

that study in more detail.

Also with these studies, the USGS provided a tremendous

amount of support in various ways to all three of these

studies and Deltares also provided some support through

some analysis that they did for different parts of these studies

also sort of as subcontractors.

Once these studies were completed, we, the ISP, wrote a

summary report that described the studies briefly and tried to

sort of do a sort of a synopsis of the studies and what we felt

it meant in terms of some overall findings on the data

gaps we observed and some suggestions for the next steps.

So those are the list of the studies.

I’ll start in next on the SAN budget presentation.

Think you need to click something else there, Bob?

There you go, one more OK, it’s right back one OK.

So for the sand budget, this was largely to address the first

management question that Brenda had mentioned about is the sand

mining having a measurable or demonstrable impact on the

sediment transport and supply within the Bay.

This was primarily done by the San Francisco Estuary Institute

with Lester McKee as the lead, though as was previously shown,

a number of people helped with this study and also the USGS and

Deltares.

On the next slide, one more Bob, we have the show a picture of

what the basic components of a sand budget and that we take a

volume of the Bay or you can think of this as a bubble.

Engineers give it a fancy word, a control volume, and we look at

everything, all of the sand that flows into that volume and all

the sand that flows out of that volume.

And with the principle of conservation of mass, we can’t

create mass out of thin air.

We know that the change in the storage of sand on the bed must

equal the inflow minus the outflow.

So this is the basic idea of a sand budget and how we can

account for all the factors affecting sand transport and

sand supply.

One note is on the bottom here.

This equation is based on conservation of mass.

Later we’ll be talking some about uncertainty, but there is

no uncertainty in this equation.

You know, mass must be conserved and this equation essentially

expresses that.

OK.

Bob on the next slide, one more please.

For doing the sand budget, generally speaking, we have

ability to quantify what the inflows that they are through

the tributaries as the VI did a tributary watershed modeling for

this.

And we can also quantify other outflows.

For instance, the sand mining is an out in this sand budgeting, a

sand mining is an outflow and we can also quantify the change in

the storage with the that bathymetry work that the USGS

did to look at the change in bathymetry over time generally.

Well, in all cases for our work here, what we don’t know is the

outflow of sand toward the ocean.

So we can take the equation I showed previously and rearrange

it to actually be able to solve that equation for what the

outflow toward the ocean is.

So what Sfei and others did is they estimated what all the

values of the inflows were, what all the other outflows are, and

then also estimated what the change in storage was to compute

what the outflow toward the ocean is for San Francisco Bay

and for some of the seven payments.

And again, I think the analogy here is on the an analogy would

be that this is very similar to being like a checking account.

You write checks, you have an outflow, you make deposits, you

have an inflow and the balance in your checking account changes

over time depending on the outflows and the inflows.

So on the next slide, Bob, one more I believe OK, we have the

some some highlights from the budget.

So SFVI did this for all the major sub embayments in the Bay

and for the entire Bay.

What I’m showing here is the sand budget for Central Bay that

shows all of the inflows that were determined and the

outflows, the change in storage, all to essentially balance the

sand budget for Central Bay.

And they looked at various things, some of which are very

insignificant and some of which are very significant as shown by

the size of the arrows.

What they found was that the San mining was a essentially a very

large term that does in fact, in fact the budget.

And in fact here in this particular case it’s the largest

term hit the one more push Bob, I believe another question that

we frequently had was the sand transport out at the Golden

Gate.

That is what we would call an uncertain number.

The sand budget came up with a value of .25 million metric tons

per year, which is about 200,000 cubic yards per year of outflow.

But there are there is uncertainty and one of the ways

that as if I evaluated that uncertainty is they took all the

inflows and outflows and the change in storage that they did

calculate for each of those.

They have a range of what the possible numbers could be.

And they took those then and sort of set them to their

maximum or minimum possible values to see what the biggest

possible inflow to the Bay is, what the biggest possible

outflow to the Bay of Sand is.

And wound up with a range of .66 to in to 1.1 out of sand

transport at the Golden Gate with the best value being .25

million metric tons per year.

So that’s one way of evaluating the uncertainty is we know these

numbers, assuming they won’t be pegged to their minimum or

maximum values will be between somewhere between the .66 and

the in and the 1.1 number out.

And the best estimate there is .25 out.

So that’s one of the one of the results of the sand budget

again, it’s you know 100 page report with lots of results

packed in there.

Let’s go on Bob to the next slide.

And I think that’s it.

So the numerical modeling study, the second of the major studies

that was supported in this effort.

Go ahead and click once more.

Bob actually addressed that first management question about

the demonstrable impact on sediment transfer in the Bay and

it also looked at at at addressed the second management

question about the anticipated physical effects of sand mining

within the Bay.

This study was done by Anchor QAA, Michael McWilliams and

Aaron Beaver and were the folks doing the modeling here.

So let’s move on to the next slide, next one, and click a

couple more times to fill up the right side text.

The numerical model they used is called the untrimmed model.

This is again his numerical computer model.

It’s a 3 dimensional model, so it covers what you see here and

the depth within the Bay.

It models the tides, wind, waves, salinity.

For the sediment modeling, they use 4 grain sizes.

The tributary inflows that SFDI calculated for the sand budget

were used in this model so that they’re comparable results.

The model has previously been calibrated by Aaron and Michael

to water level, salinity and suspended sediments.

I know Craig Jones, one of the ISP members, told the RMP

recently that he thought this was the, he’s actually

developing a contaminant model for the RMP and he thought this

was one of the best models for San Francisco Bay.

What Aaron and Michael did to look at the effects of sand

mining is they simulated low and high flow years where there’s

either a little or a lot of freshwater flow into the Bay and

they simulated them with and without sand mining.

Essentially, the sand mining was a term removing sand from the

lease areas as the information from BCDC on those rates.

And they simulated the Bay with and without the sand mining to

be able to compare those results, take the difference and

see what the effect of the sand mining was.

OK, So the next slide, Bob, we have some highlights here.

One is that the net sand transport at the Golden Gate was

toward the ocean at about 80,000 cubic yards per year, which was

a little less than what the budget came up with, if you

recall, about 200,000 cubic yards per year.

Now we have a number of 80,000 and 200,000 in the, you know,

studying sediment.

There’s a lot of uncertainty looking at sediment transport

that as scientists we get used to.

These numbers actually I’d say in the segment world are fairly

close.

The joke we would have in the science circles was if you

agreed within a factor of 2, you should go publish a journal

article about it because that’s good agreement.

So that was one of the highlights here.

Another on the second bullet is that up in Sassoon Bay they

modeled these for one year and the effects of sand mining

through the Bay were really limited to the vicinity of the

mining areas.

In other words, it the effect of the mining dispersed very

rapidly with distance from the mined area up in Sassoon Bay and

it was somewhat true also with Central Bay.

Over down in Central Bay, they found that the total transport

of sand out of the Golden Gate, they predict a decrease by 59

and 32% because of the sand mining during the high outflow

and low outflow years was one of the numerical modeling results

that they came up with.

So those are just some of the highlights from the numerical

modeling study.

Again, it’s a very lengthy detail.

I think that was a 200 page study with all the figures that

has a lot more results in it that you can read up there.

So let’s go look at the next slide, Bob.

And here’s where I’ll turn it over to Bob.

Thanks, Dave.

Are there any objections for me to complete the presentation?

Does does anyone want to ask Dave questions about what he

just said?

While we’re at this pause, I, I, yeah, Barry Nelson here.

Just one simple question where I’m not sure I successfully

understood one of the lines.

There was a note there about .25 metric tons per year and

transport out the Golden Gate and that that translated to

200,000 cubic yards per year.

I’m just trying to get the that that’s the slide and I’m just

trying to get those numbers to line up.

That’s not that, that’s metric ton.

What’s that’s £550 quarter of a metric ton, 550 lbs or so.

Well, it’s actually the the capital M stands for a million

that OK.

And, but it is a metric ton and, and the conversion we’re using

is the one that SFEI used for sand deposits like those mined

by the miners.

There were different conversions, you know, density

conversions.

I think the number is, is right around 180 or maybe 160,000.

It’s about 200,000 cubic yards round numbers.

I, I, I suspected that’s, that was that I misread the M Thank

you.

Bob, if I could ask one question, this might be, you

know, the kind of somebody who knows just enough to be

dangerous here.

And we don’t only go down a rabbit hole, but it’s my

understanding that measuring net transport at the Golden Gate is

a really, really difficult thing to do.

Now, I’m getting the impression from what you’re presenting that

net transport on the bed is not as difficult as net transport of

things that are floating back and forth with the tide.

It’s actually the opposite.

The the bed load transport is well, I don’t know, maybe I

should let was, I would say the bed load transport is a bigger

question mark.

The suspended transport you can get from you know, taking

samples or doing kind of a remote sensing it.

But I guess aren’t we dealing with trying to, we’re measuring

a huge number, which is the transport in during any tidal

cycle and then we’re trying to net out a very small number.

Yeah, right.

So to your point, the net is an estimate of the average over a

time period calculated as the difference between what’s

calculated one way added up and minus what’s calculated the

other way added up.

And so the net is small and less certain.

Yeah.

So if we go back into the last go, just go forward this to the

last slide and then I just wanna then ask you about.

Yeah, here we go.

So, so at the top here, we’re estimating this with one

significant figure.

And as Dave said, you know, hey, that’s pretty close, which I

understand that.

But then when we say we’re talking about 59% and 32% in

different years, I’m, I, I guess I’m trying to get a header at my

header on how we know, know the numbers that accurately.

I’ll let Dave answer that.

That was from the modeling and you know, they’re precise

answers within uncertainty.

So, but it it, it does show that, I mean that was the

conclusion.

Whether it’s 59% or 72% or 32% or 21 percent is is unknown.

But but this was the finding.

But Dave, would you like to jump in on that?

Yeah, as Bobby did an excellent job of answering that.

The last, the 59 and 32% numbers are from the numerical modeling

where all those bell that back and forth transport, they can

add up and calculate a precise number.

Now how accurate that is, if it’s, you know, 70% or 40%, you

know, that could be argued and debated perhaps, but they are

able to calculate the more precise numbers with the

numerical modeling.

In terms of the transport of the gate, remember that 200,000

cubic yard per year number is basically taking the sum of

everything else and moving it down to the Golden Gate because

that’s the number that’s actually being calculated by the

sand budget.

There is no measurement showing 200,000 cubic yards per year

going out the Golden Gate or 80,000 cubic yards per year

going out the Golden Gate.

That’s the result of that equation I showed earlier of

calculating what that outflow is based on the inflows, all of the

other outflows and the change in bathymetry, right?

And so as long as you’re sure you, you know, all the sources

of gain and loss, then you get this is this number is derived.

I, I get that.

So, so I guess what I’m just trying to get my head around,

Dave, is when, and maybe this is just for going forward when we

need to be thinking about precision and when we need to be

thinking about accuracy in, in terms of understanding the

policy implications of these results.

For, for the, for the last thing here, for the 59%, the real

question is not if it’s 59% or 55%, but whether it’s 60% or

point O 6%.

I mean that there’s, there’s and, and I’m just, I guess I’m

just still a little, I’m not sure I have my head around,

around how well we know some of these things.

And, and, and that’s the thing that I want to be.

I, I would really appreciate your help with.

I mean, if, if the model produces a number that’s 60% and

we report that, that’s fine.

But it’s, there’s a lot of uncertainty in that number.

As I understand it.

Yes, there is uncertainty in the, you know, quantification of

the inflows, the quantification of the outflows, the

quantification of the change in the bathymetry and all of that

kind of adds down to the uncertainty in the number going

out, say the Golden Gate.

The reports themselves detail those uncertainties since this

is something we worry about a lot on the ISP about the

uncertainties here.

So I think our summary report that Bob’s about to describe and

the individual reports that discuss the uncertainty delve

into the details of how well these numbers are known.

Great, thank you.

Because it’s hard to answer, give you a one off answer on

that very good question you’re asking.

Thank you.

I will just add that the numbers that were included in the sand

budget on the navigation, dredging, in the sand mining

numbers were actual numbers reported for the last 20 years.

And this this the sand budget exercise was from 2000 to 2020

was the 20 years that were looked at and the dredging,

navigation, dredge mining data were actual reported numbers.

So there is some certainty in those numbers.

Well, there is pretty good certainty in those numbers and I

saw that there was another hand up.

We have time for one more quick question.

McGrath has a question.

Yeah, it’s actually a a comment.

First of all the the science I’ve I’ve read these reports and

the science is great.

There’s two other data sources that I, I’d like to to give you

that, that tend to support this.

And I don’t know that the panels look at it.

When I was at the Coastal Commission, we regulated the

Corps of Engineers dredging of the bar and, and the bar had a a

remarkably narrow band of grain size, all about point 2.21

millimeters.

And our conclusion on that or our theory on that was at the

depth of the bar that was about the maximum grain size that

would be disturbed by the waves passing overhead using

conventional wave theory.

And, and that’s the material I think that that moves around.

All of that data of course is available.

So that’s the first source that that tends to augment the

questions that were asked earlier about fine grained

sediment and why it’s in the Presidio Shoal.

That’s what’s disturbed.

There’s an Eddy current.

There’s another source that we give you some insight into the

rate of transport in that Eddy current.

When the restoration efforts occurred at Crissy Field, there

was no refilling of the inside bar and the outside bar.

And over a period of I think it was five years, about 35,000

cubic yards of material collected there.

So that gives you some augmentation that you should

probably look at to, to, to give a, some real measurement about

what the the countercurrent was.

So I just thought I’d throw that out there before you got to

profits.

Thanks.

Thanks, Jim, really appreciate that.

I, I yes, thank you.

Should should I, I’ve been thinking about this stuff for a

while.

Yeah, no, I I really appreciate you being on the call too.

Actually, that’s, that was very helpful perspective.

I have similar perspectives.

Should I proceed?

Yeah, I think you should.

OK.

Thank you.

No, that was a great discussion.

I, I, I could have said some things, but I’m going to move

on.

We can talk later if we have time.

So this is the, the third study that Dave Schulhammer and I,

this is Bob Battaglio of the ISP are presenting basically big

picture.

We’re doing a brief summary of each of the SAN studies and then

we’re going to provide the independent science panels kind

of distilled findings, if you will briefly.

So this is just going over the fingerprinting study which is

gonna be presented.

I think I’ll just go through this quickly and then I think

Zach is gonna present their study, which is is good because

it’s a little complicated for a lot of us.

But basically the the fingerprinting study looked at

mineralogy, which gives you an idea of which mountain range the

sediment came from.

It looks like at a component zircon, which can be analyzed to

tell you how old the deposit is, which also can help you

understand where it came from.

And then there’s this thing called luminescence, which is a

reaction emanation, if you will, from the grains that the sand

grains that can be detected that tells you how long since it’s

been it was daylighted subject to sunlight.

I think I have that right.

I’m sorry.

I want to go back and just show you this image from the study.

The orange is coarser sand.

The the tan is medium sand and the, the light tan is, is finer

sand.

The Gray is mud.

So you can see the sand mining’s up here around Sussoon Bay and

then down in Central Bay, and you can kind of see where this

is exposed, where there’s strong hydraulics and out here waves

and the like.

This little dotted line is the estimated shoreline of 14,000

years ago, and then this line is around 10,000 years ago.

The idea being that this was a river, sea level rose and now

it’s a drowned river.

Delta’s way up here and this is the tidal exchange area.

Second slide of the fingerprinting study.

Management question Tier 21B.

What is the source of mine sand in the lease areas?

Sussoon Bay deposited from local coast range drainages.

Central Bay eroded from outer Pacific Coast, previously from

Sierran Range and coastal range.

Management Question Tier 21B.

Is it relic sand or new sand transferred in the system?

Sand is relic.

Some relic sand is exposed to hydraulic forcing.

It is in transit.

Some relic sand is below the Bay floor and it’s not in transit.

So this is something that I think a lot of us could easily

get stuck on.

Relic means it’s not being supplied now, but that doesn’t

mean that it’s not moving around and it’s not being mined or, or

it is being mined.

It’s it’s relic and moving around and relic and not moving

around.

This is a, a conceptual model of, of low sea level stand that

I described before and you have the Central Valley rivers going

through what is now the Bay and discharging out in a delta

somewhere around the Farallon Islands.

3rd slide, last slide on the fingerprinting study management

question, Tier 21 E, Does mining in leased areas have the same

effects on sand transport pathways?

Should these areas be examined separately?

They can be treated separately, we think different sand sources

and spatial connections.

And I’ll go over this figure in a minute.

Well, here we go.

Sassoon Bay is in the red.

The mining area is up here.

The red indicates the sand transport vicinity and pathways

that are conceptually interpreted from the mineralogy

analysis, fingerprinting analysis.

And it’s seems to, you know, link to San Pablo Bay, maybe

North Central Bay.

Central Bay is the blue and the sand seems to link very much

with the ocean and, and the Bay and the ocean beaches.

We’ve got tidal exchange going back and forth and then there’s

wave driven transport along the shore here.

Next, I want to talk about the USGS.

They did not author one of the three main studies, but they

sure did do a lot of work.

And of course the US Geological Service, our survey is well

known in the San Francisco Bay Area.

They’ve done a lot of great work in San Francisco Bay and on the

Pacific Coast, including out at Ocean Beach, etcetera.

They provided a a sediment transport boundary condition at

the upstream East End of Sassoon Bay.

They provided bathymetric change mapping and volume calculations.

This is a pretty heavy lift to, to look at how the the Bay floor

has changed, calculate how much the sand and mud and then Add

all that up that, that, that was a, a that’s a really big deal.

And then they also provided they have a, a, a storehouse.

They have core, sediment cores taken over decades and they

provided analysis and, and grain size, etcetera for mineralogy

for the fingerprinting study.

This graphic just shows where some of the cores were taken.

This graphic over here, I hope you can see my cursor is shows

one of the cores from the top down.

Top is younger, bottom is older.

And there’s some interpretation in terms of when the sediment

deposited and how quickly deposited between which periods.

And this is just a generic grain size.

Well, actually it’s from the fingerprinting studies.

Some of these are grab samples and not core samples, but this

this shows you how some of the data were used.

The other major supporting entity is Deltauris, world

renowned technical group out of Delft Institute in Netherlands.

They did what we called a more dynamic interpretation, which

just basically means how the sand moves and how the bed forms

and and deposits change and how do you can interpret transport

direct pathways and and and at some points even rates from from

this kind of geomorphic analysis.

What what we got out of that is the Central Bay sand transport

is driven by tidal exchange to the Golden Gate with sand

migrating between the Bay mining areas, flood tidal Shoals and

the San Francisco Bar ebtitle Shoals in the Pacific Ocean.

Additional sand transport waves along the shore into the Bay.

So this graphic here on the right, the black and white one

shows their interpretation of the main sand transport

pathways.

The thick black lines A is driven by ebb tidal flow, B is

driven by flood tidal flow on the Oceanside.

This dashed line indicates where the San Francisco Bar is.

The waves push against the sand deposit by the tide, so you get

a nice kind of horseshoe shaped feature where the two forces

collide and balance.

Out on the Bayside you get a splay of of of tidal flood

current and a series of Shoals affected by the terrain and

topography.

Shoals behind Angel Island, etcetera.

This is a blow up from the Delft.

A larger image.

The Golden Gate is right here where the purple, deep purple

depth is.

This is minus, you know, 80 meters or so, 100 meters.

And then this is Angel Island, this white area which is over

here, Alcatraz, these black lines are the same as these

black lines over here.

But if you look closely, you see little Red Arrows and you can

also see in this, this is depth bathymetry.

So the tan is is up in the -20 meters or so and the blue is,

you know, much deeper around sixty, 100 meters or 75 meters.

And you can see these bed forms, these sand waves, which you can

interpret based on their asymmetry, which way the net

sand transport is moving.

Here we have convergence, which is kind of almost the definition

of a Shoal, if you will, unless it’s eroding rapidly.

And then so anyway, they, they analyzed all this and it was

very interesting and, and we all looked at it, it was great.

Second slide on Deltares bed changes in mining areas.

So the mining changes bed geometry.

You’re replacing natural bed forms like sand waves with

depressions and a lower bed elevation.

You see in this figure, tan is is higher elevation bed of the

Bay and and blue is lower.

So the and the top is 1997 and the and the bottom is 2019.

Brenda showed another version of this.

Here’s the depth chart over here.

What you can see in 1997 it was shallower, the Tanner color and

then at by 2019 it’s deeper, you know the bluer color.

And you can also see, you don’t really see these sand waves in

here.

You see these kind of irregular geometry, localized geometry.

So what this tells us is that diffusion by currents and

turbulence etcetera, which would smooth the bed depressions is

really kind of limited within the time frame of the study.

These depressions seems to persist.

Infill of the depressions is limited to less than 30%.

So this is the recovery rate if you will.

So in Sussoon Bay and North Central Bay, there’s not much

recovery.

The the sand mining effects persist at least during the time

frames and and locations we had data for and looked at except

for two Central Bay areas.

1 is this one least 2036 point NOx Shoal and it, it had a 55%

recovery between 2008 and 2019.

So that’s a different starting point than the 97.

And then the Presidio Shoal, which is the finer sand that

that was talked about earlier.

I’m just used 100% that it was actually a little bit less and a

little bit more depending on the time frame.

So that one’s really recovering.

This is very useful information.

And this is an analysis that the ISP specifically asked for it.

And just a little bit of an aside, we talked about

uncertainty.

There’s a lot of uncertainty in these analysis.

But if you look at how these studies were structured, we have

a, a sediment budget and a sand specifically also a sand budget.

We have a, a numerical computer modeling based on computation to

sand transport.

And then we have this mineralogical historical

analysis, source analysis tracking, if you will.

And then we also had this geomorphic analysis and all

these other things.

So these are different lines of evidence.

And So what the ISP came up with is where we think these all kind

of agree.

And this is what I’m gonna present now, a pretty distilled

one.

On the local scale, depressions, removal of sand waves and bed

lowering occur where sand replenishment is low.

This is all of the mining areas in Suzun Bay and also the North

Central Bay mined areas where there’s 11 to 28% replenishment,

you know, precisely calculated.

But you see it’s say less than 30% reduced sand transport

occurs we think where sand replenishment is high.

And this is occurs in the South Central mined areas 709 S, which

we talked about earlier, the Presidio Shoal where there was,

you know, I said 100% in the prior slide.

But this is the range that was computed.

And the idea is that if if there’s sand moving into through

an area and you excavate that area and then that sand that

moves through fills it up or whatever drops out in that area

to restore the bed form likely is a reduction to the sand that

moves through the area because the sand transport is thought to

be transport limited plus or minus.

You dig a hole, sand deposits less sand goes out the other

way, and then the currents have to pick that sand up elsewhere.

So that’s an effect.

The Central Bayside I showed you again, even with that depth

change, we computed a 55% replenishment on the regional

scale.

Sand mining exceeds sand supply.

Mine sand is relic delivered to the Bay thousands of years ago.

Sassoon Bay and Central Bay lease areas can be analyzed

separately due to the apparent limited sand transport

connection between them.

A little bit of a surprise.

Sand is exchanged between the central Bay sand mining areas in

the sand Shoals and beaches on the Pacific side of the Golden

Gate.

Exchange is driven primarily by the ebb and flood of the tides

with contribution from wave driven sand transport into the

Bay along the shore.

Erosion of beaches due to sand mining was not investigated in

these studies.

Here are the key data gaps.

We can discuss these if you want later, but first, the exchange

of sand between the Bay and the Pacific Ocean.

We got some good information.

I think we all feel like we could get into this a little

further.

In particular, understand what’s happening on the ocean side.

We kind of split this whole system in half or in parts and

we haven’t looked at the other side, which would, would help us

understand what’s going on.

Secondly, the sand supply to Bay beaches is, is of interest and

we, we didn’t analyze that.

I would say the sand supply to ocean beaches would would go

into item 1 sand transport pathways.

We, we did, we, we did confirm and identify sand transport

pathways in these studies.

But within each of the, let’s say sand budget sub embayments,

there could be sand movement from say a source like say a, a

river mouth or a Creek mouth that just recirculates landward

and forms a beach and doesn’t propagate.

You know that sand may not propagate all the way through to

the, to the ocean.

So those some refinement of the sand transport pathways and in

particular how the the beaches are linked to the deeper sand

offshore sand supply.

4th, the variation of sand transport caused by grain size.

This is I guess one of the first, certainly the most

intense and detailed analysis of sand in San Francisco Bay at a

Bay level.

And so there were some simplifying assumptions as we

discussed at the beginning, some of the questions grain size

matters with sand.

And you know, there may be different answers with the finer

sands and the coarser sands.

I’ll just leave it at that so that that’s something that could

be looked at further.

OK, I just, I think we’re, I’m done with the ISP presentation.

Happy to for all of us to talk or answer questions.

I just wanted to leave you with this picture that I took a

couple years ago thinking about this.

This is looking at, you know, the Golden Gate at the Presidio

from Crissyfield Beach.

You can see some waves here coming in.

These are waves from the ocean.

They’re coming in through the Golden Gate and refracting

around.

You can see this wave breaking.

It’s moving sand along the shore.

That’s called littoral transport and this is a beach with people

on it.

And if we hung out here for a while, we might see some birds

and a few other things, other animals.

This was not studied in the sand mining studies except based on

the limited available references and and Jim mentioned Chrissy

field deposition and I will, I think I’ll just continue to

share.

I don’t know if I did that or did somebody else do that, but

probably me.

But are there any questions or should we go on to the

stratigraphy study?

Well, I think what we need to do now and we are getting very

short of time.

So I don’t know if people have the ability to hang out for a

little while after three.

I’m hoping maybe they do.

But we do need to take down your slides for a SEC, Bob.

OK.

And thank you so much, Dave and Bob, I think we need to have the

opportunity for the sand miners to provide comments.

Yeah, Sorry, Pat, if I stepped on your toes.

No, that’s good.

That was one of the things I was going to say.

And Brenda, just a quick note.

I have a hard stop.

I have another Zoom call at three.

OK, we’ll try to move quickly because we want to get to the

provenance study.

So Erica, I guess you’re still.

Yes, we will have Aaron Holloway from GHC, the consultant for the

miners to present a couple of slides here.

Thank you.

Great.

Thanks.

Welcome, Aaron.

Hi.

Thanks for having me.

Let me hold on a second.

It’s gonna be easier if I share a screen.

So our, the, the comments from the mining team are summarized

in Appendix H Let’s see.

Sorry, bear with me.

There you go.

But I would, I just wanted to highlight kind of the sand

budget.

You know, it, it, it was discussed quite a bit by Dave

and, and Bob and we recognize the value in the sand budget.

But as David said, you know, it’s really looking at inflows,

outflows in the change in storage.

So you know, it’s transactions in a checking account, but what

it doesn’t include is, you know, the size of the savings account

and the size of that sand reservoir.

And we think that’s an important consideration in terms of how

much sand is out there and available for mining.

And so that’s, that’s a key item that’s missing from the sand

budget.

The other one I think is, was was was discussed, but I feel

like is is not given enough attention is that the

uncertainty in the direction at of sand flux at the Golden Gate,

it’s the most significant, you know, it has the highest, it’s

the most uncertain term of the sand budget.

But I think a lot of the results we just saw, you know, jump to

the best guess that it’s, you know, oriented out and sand

fluxes out toward the ocean.

But if you look at the uncertainty, it could go either

way.

And and comments on the ISP report from Lester McKee, you

know that I have quote from him at the bottom.

Due to the, the computation by difference and accumulative

uncertainties, the direction of flux at this location is

uncertain.

So we would caution, you know, the, the, the commissioners from

viewing that as a certainty.

You know, it’s, it’s not.

And I think that’s, that’s described in the studies.

But sometimes, you know, when trying to summarize things, you

know, we leap, leap beyond this uncertainty.

The other concern we have in terms of the sand budget is the,

the way mining was accounted for in addition to bathymetric

change.

So the USGS team studied the bathymetric change.

Their methods excluded the human disturbed act areas which were

mining and dredging, largely because those were going to be

accounted for separately.

You know, as as Brenda indicated, there’s there’s

detailed volumes and records of the mining and the dredging.

So those were going to be accounted for separately in the

budget that so the bathymetry change should not have included

those areas.

That was the methods and that was kind of the the direction

that was shared by Bruce Jaffe during the quarterly review

meeting on this topic.

But when the SFEI team prepared their budget, they included

both, they included the mining areas in the bathymetric change

volume and then they accounted for them separately as well.

So while we acknowledge the sand mining is a large term in the

sand budget, to double count it, you know, is going to have

significant error in the results.

So an example of that at Sassoon Bay here, Sassoon Bay did not

have a lot of transport.

You could see the bathymetric change in this location outside

of the mined areas is, you know, relatively shallow, plus or

minus half meter, you know, maybe 1m at most.

But the large black area there you see in that graphic, this is

the mined area.

So that’s where a lot of the change is happening and the

change is due to mining.

But in the sand budget, it’s accounted for once in the

bathymetric change volume and it’s accounted for again as a

mining volume, essentially double counting it.

So that that ripple effect carries throughout the sand

budget because the sand budget assumes the system is all

connected.

If that is corrected and the sand budget bathymetric change

is, is kind of accounted for separately than the mining as

intended by the USGS team, the results are significantly

different.

You know, we have a different direction and a much greater

magnitude of inflow of sand to the Bay.

And then comparing the conceptual model that Bob

described from from the UT Austin team where we have sort

of two distinct sources of sand somewhat disconnected that

doesn’t align well with the sand budget as currently presented.

The sand budget, you know, indicates this flow of sand

throughout the Bay, which if that were the case, you would

expect there to be some more consistencies between the the

type of sand and the source of sand.

So if the corrections are made in the way the mining is

accounted for, these arrows change significantly.

So Pacific Ocean becomes a source of sand for the central

Bay and then the flux between Sassoon Bay to San Pablo and the

flux to central Bay become a lot lower.

And that looks a lot, a lot closer to the conceptual model

described here.

So we’ve got other comments about speculation of mining

impacts and, and, you know, the lack of prior research

conclusions that were brought in from the environmental teams,

but I’m not gonna go into those.

I’ll, I’ll turn it back over to the team.

Thank you.

Do the miner, do the miners have anything else they wanted to

present or was that the end of it?

No, Greg, we’re, we’re just keeping it brief in the interest

of time.

Oh, I totally appreciate that.

I I wanted to say that I think that we should have any

discussion and we can always do the next presentation at a

different meeting.

I want to make sure that the commissioners get a chance to

discuss anything they need to discuss or want a questions they

have at this point.

And if there aren’t any, then obviously we can move on to the

next presentation.

But I, I did think that was probably the point of all of

this.

Yeah, yeah.

I would just want to say, sorry to jump in, out of place here,

but we’re, we’re very fortunate to have the, the UT people

online.

So I think it would be a shame if after they did all this

without getting paid that we didn’t let them speak.

So it wouldn’t be easy for them to speak at the next meeting.

They would have to, need to speak now.

All right, Well, I don’t know.

I, I just, that’s my opinion.

For what it’s worth.

I, I probably spoke out of turn, But no, no, it’s a good question

’cause obviously we want to hear from them.

I was just thinking we could hear from them next.

But if that’s what that’s what we need to do, yeah, I’ll have

to ask them.

I’ll ask them indirectly, I mean, in the chat while you guys

talk.

Well, if there’s a question from the commissioners, I was just, I

I do have a question.

Yeah.

My question is, was anything, did you look at what those

depressions were filled in with?

Were they filled in with the same kind of sand grains that

they were taken or were they filled in with silt?

I always think of this that the Bay is a very silt rich

environment.

So So what were those holes filled in with?

I’ll jump in on that and maybe Dave or somebody else can help

me.

Those areas are hydraulically too active to contain much mud.

Let’s just use that.

Silt would be the coarser side of that, in my opinion.

There were some attempts to look at cameras and, you know, camera

shots, but it’s it’s a very active area.

It’s very hard to see.

It’s pretty deep.

Yeah.

You know, if you are a hard hat diver with big heavy boots, you

probably fall over and get buried.

I’m not quite sure.

I mean, it’s a pretty tough place to to see, but I don’t

know if anyone else has more, you know, better, more specific

information.

David, would you wanna help me out with that?

Did I?

Do you agree with me?

Yes, I agree, Bob.

The basic of the current pad, the currents are so strong there

that the silts and the clay material does not settle there.

So it is the course of material settles in those depressions.

Thank you.

That that that’s what I wanted to know.

Appreciate it.

So we can move on as are are there do any other commissioners

have a question?

Andy Gunther.

Yeah, I have a question.

But maybe we wanna push this discussion to the next meeting,

Brenda.

But but yeah, I think well, I think one of the important

things.

Let me just pass up my question please.

The question is again about the uncertainty at the Golden Gate

and the, the and this I’m now unclear about the double

counting.

I thought that we had a quote from he saying that we’re not

gonna include the dredging site so there won’t be double

counting.

But it sounds like we have another presentation suggesting

there was double and therefore the numbers in terms of the

Netflix at the gate look very different, which again, I

thought was uncertain anyways.

And so it’s a I, I’m not sure how Brenda, I’ll defer to you

about to how we, we, we work on this issue.

But I need some more time to kind of understand the debate

here and then its implications for how, what what we we are

thinking about in terms of permitting additional sand

mining and and what the various benefits and risks are.

Yeah.

And what I was going to say, and I apologize, apologize for the

interruption, is that this was the ISP findings for findings

overview.

We will have Lester McKee.

He’s agreed to come.

I don’t have the date right now, but he has agreed to present on

the SAN budget, which perhaps where is where this conversation

would be better had because then Lester who developed the budget

would be here to have that conversation.

But yeah, can I, can I jump in real quick?

So the ISP was aware of the, of the, this comment and it’s our

judgment that the, the budget was done correctly.

Several of us have a lot of experience with budgets and we

feel that it was done correctly.

I would suggest that it’s great to get pushed back or you know,

critical review.

I, I, I, I would suggest a process to reconcile these

concerns and then report back.

I think there might be a need for additional study to, to

specific analysis to reconcile these perspectives.

And I think it’s a healthy process, even though I know it’s

frustrating when you have to make a decision.

Well, no, I mean, I, that would be my preference would be that

you and Mr.

Holloway talk this over and, and, and help at least clarify

for me whether whether you have found areas of agreement and you

still have areas of disagreement or whatever.

So that, that, that I don’t have to take my limited knowledge of

this and somehow make my own faulty decision.

Yeah.

And I and I, you know, Aaron and I know each other and we all

know.

So this, this it’s fine.

I don’t really feel bad about the, the challenges and I, I, I

just don’t right now.

You know, we’ve been working on this for a while.

So everyone’s out of money except, I don’t know, maybe

Aaron has more money than the rest of us.

But yeah, but I think we could all work together and, and come

back with this resolved.

In my opinion.

I, I, I would prefer to do it that way rather than, you know,

argue about it, frankly that, that I hopefully I didn’t speak

out a line again.

I’m sorry, I’m getting older.

No, not at all, but I thought that was great that you spoke.

Thank you.

I, I can just wrap it up.

I, I agree.

I think if we can talk with Lester and the team, that’d be

helpful.

This comment was made sort of after all the quarterly meetings

were held.

And so there wasn’t ever a venue to really kind of talk this

through.

So the results that were prevented at the last quarterly

meeting were much different than this final version.

And so part of it was we just haven’t had that chance to talk

that through, ask our questions and and understand the rationale

behind the final budget.

So we look forward to that happening.

That sounds to me like a great suggestion.

Brenda, can you kind of help that happen?

I can help that happen.

I will note that I’ve been chatting with Zach, our next

presenter in chat, and he does, as does Matthew, teach classes.

And so our next several meetings are scheduled during periods

where he is teaching.

So we have 20 minutes now we could have him do the

presentation or I can try to.

Let’s have him do the presentation.

Yeah, let’s do that.

That sounds great.

OK, Zach, with that, you’re on.

Sorry for the.

No problem at all.

This is an important discussion.

And hopefully what I have to, to present here will will provide

some context as well.

So let me get my screen shared and OK, yes, presentation.

Yep, OK, everybody can see this.

Yes, great.

OK, well, again, I’m very happy to to be able to to speak to you

all about the research that we’ve been doing.

And since we’re a little short on time, I’ll just go ahead and

hit the high points.

I’ll also note that I’ve made my slides hopefully pretty

self-explanatory.

So anybody that wants to look at them later, please feel free to

do so.

And then Matt and I have also, we’re in the process of

publishing a lot of this work as well.

So that will be available and we’ll make people aware when

things are published.

So we’re gonna have to start with some kind of sedimentology

101 background here and explain what a fingerprinting study is.

And so a sedimentary system is comprised of some source region

where sediment is being produced by erosion, some area where that

sediment is being transported.

So for source regions, think mountains, transport regions,

think rivers, and then some area where that sediment is being

deposited either along the river or somewhere out in the coast.

And so I’ve, I’ve kind of conceptualized fingerprinting

here by illustrating blue source regions, red source regions and

yellow source regions.

And if we go into any point in a sedimentary system and we take a

sample of the sand, we can use the composition of that sand

that’s inherited from the unique geology and its source region to

say something about where it came.

So we go here, we see red here, yellow here, where they mix in a

delta combination of red and yellow.

And so there’s many different ways that we can do this with

natural sediment and we use several different methods for

this study, but I’m only gonna talk largely about one of them.

So it’s also important to note that processes like climate and

tectonics can change where sediment comes from in the same

system through time.

So, you know, maybe in our baseline here, we’re producing

more red sediment out to this delta ’cause it’s raining more

on the red mountains.

Maybe in time too, we shift and we’ve got more rain in the

yellow.

Maybe we’ve diverted the blue into the into the red.

And so now we go out to the delta and we see, OK, we’ve got

a combination of dominantly yellow, red, blue, so on and so

forth.

So processes can change where sediment is coming from in a

sedimentary system on the scale of of thousands of years,

hundreds to thousands to 10s of thousands of years.

And so if we have information both on the age of the

sedimentary deposit that we’re that we’re looking at and we

have the sediment fingerprints, we can develop kind of a from

where and when model for the history of sediment sources in a

specific sedimentary system.

And that’s what we’ve done for San Francisco Bay.

So it turns out that California geology is particularly well

suited to doing this kind of study.

So here on the right, I’ve illustrated the Sacramento and

the San Joaquin catchments and their major tributaries.

These are the dominant sediment sources for most of the sediment

at least over longer time scales into San Francisco Bay.

And so up north, we have volcanics, metamorphic rocks,

we’ve got granite and the Sierra Nevadas.

Down here in the South, we’ve got some metamorphic rocks,

mostly a lot of this granite.

And then in the Coast Ranges, we have a mix of sedimentary and

volcanic rocks.

So we have different source geologies in these different

regions.

The sediment that is being produced by each of these

regions is going to have a different compositional

fingerprint that we can use to talk about where sediment is

coming from and how that might change through time.

So the specific method that I’m gonna talk about is using

uranium, lead aged dating of a mineral called zircon.

And this is a particularly useful tool in California

specifically in large part because California was once a

subduction zone.

So 10s of millions, hundreds of millions of years ago, there was

an oceanic plate subducting into California.

It was glomming on a bunch of metamorphic rocks here in the

water.

Now the Sierra Nevada, there was an active magnetic arc that was

in placing all the granite that is now in the high Sierras.

And so one of the minerals that forms in these settings is this

mineral zircon.

So zircon is very important here because it incorporates a little

bit of uranium into its crystal lattice.

And so once that zircon crystallizes in cooling magma

chamber down here that will eventually become granite, we

set a uranium lead age decay clock.

And so we can we can examine the specific age of crystallization

of that zircon.

And that age of crystallization is gonna be different in

different places along the Sierra Nevadas.

And so once those plutons get uplifted, these zircon get

eroded and transported out into the rivers carried out in the

San Francisco Bay.

We can use these age dates to get a fingerprint that’s pretty

unique to the source region from which sand is eroding at any

given time.

And so as a specific example of this, we can look at Half Dome

and Yosemite.

So Half Dome and Yosemite is made of granite that’s about

84,000,000 years old.

So when a zircon erodes from Half Dome, it falls into the

Merced River.

The Merced River carries it out into the San Joaquin River, that

carries it out into San Francisco Bay.

So if we go out into the sand to San Francisco Bay, we separate a

lot of zircon into the sand.

We analyze the ages.

If we see a lot of 8084 million year old zircon, we know that

there’s a lot of sediment coming from this part of the Sierras.

And so California is very good for this because a lot of these

basement, a lot of these rocks have been dated.

People have been studying Sierra Nevada geology for many, many

decades now.

So we have a very good understanding of where zorcon of

different ages are coming and being fed into this system.

And Matt and I have been working for 10/10/12 years or so at this

point on generating these uranium lead age spectre, these

fingerprints for different sediment sources that feed into

San Francisco Bay.

And so the rivers that are carrying sand out of the

northern Sierras up here in the Sacramento catchment are very

enriched in this 140 ish million year old age beat.

And So what I’m showing here is we took a sample of sand or we

took multiple samples of sand.

We separated a lot of zircon out of them.

We dated them individually.

And this is the Spectra of ages that we got out of the zircon.

So the sand up here coming from the north has a lot of zircon of

this age.

The sand coming out of the South, the San Joaquin catchment

has a lot of zircon of this 80 to 100 million year old age.

And the sand that’s coming out of the Coast Range is here has

kind of a mix of these ages, but importantly it has a lot of

these younger zircon ages as well.

And so these are coming from younger volcanic material in

like the Napa and Sonoma Valley.

So each one of these regions has a very distinct fingerprint that

sand that is derived from that region is going to have, is

going to inherit.

And so we can use that leverage to talk about where sand in

different parts of San Francisco Bay might be coming from.

And so for this study, we got dredge samples from the mining

company.

So some of these in Sassoon Bay are actually dredged from the

lease blocks.

And we also got some older core samples from older academic

studies.

Same here in Central Bay.

We got a dredge sample from the deeper part of Central Bay,

dredge sample from Presidio Shoal.

We also have some samples from Crissy Field.

We’ve got samples from the outer coast beaches.

And then we’ve also got samples from the far offshore.

And so we took all the sand from these samples.

We separated all the zircon out of it.

We dated those individuals zircon to look for those age

fingerprints to say is it coming from the Northern Sierra,

Southern Sierra Coast Range.

And so this is what that looks like.

And so here we’ve highlighted the Bay head.

So the Bay head here is the Sassoon and San Pablo Bay

samples shown here in blue.

The central Bay samples are those that are in the Golden

Gate Strait and Central Bay dredge blocks down here.

And then the yellow samples from the outer coast beaches.

And so very importantly from these fingerprints, we see that

the Bay head samples are dominated by this 140 ish

million year old age peak, consistent with derivation from

the northern Sierras, whereas Central Bay and the outer coast

are much more strongly related to the southern Sierras.

And so if you haven’t seen sediment fingerprint data like

this before, maybe this seems like kind of a subtle

difference, but we can we can very rigorously statistically

demonstrate that these two regions, the Bay head region and

the central Bay and outer coast region cannot be derived from

the same source.

The the source of the sand that was depositing that sand that we

sampled must have been different between those two regions.

So back to this conclusion figure.

So these are just the basic conclusions from this work from

just that data.

These two regions have different sand sources.

The Bay head is probably largely northern siren derived with

maybe some local drainages.

Central Bay and the outer coast have a much stronger southern

siren affinity.

And it’s also important to note that I’m talking about the

zircon data here, but this is also supported by other

fingerprinting methods like sand photography and geochemistry.

The same, the same trends hold.

I’ll also note that these trends hold over grain size as well,

right?

So the the sample from Presidio Shoal is indistinguishable by

these methods from the sample in the deeper part of Central Bay

and all of the samples across the Student Bay are

statistically indistinguishable from each other as well.

OK.

So we don’t just have the fingerprint data here, which is

very useful.

We also have some information about the likely age of the

sand.

And so when I’m talking about age of the sand here, I’m not

talking about the age that that sand last moved.

I’m talking about the age of when that sand came into the San

Francisco Bay system originally.

So not the last time tides moved it, but the time at which it was

carried from the Sacramento, San Joaquin drainage into the San

Francisco Bay system.

And so we’ve been able to directly date that kind of

residence time in two places here.

So these are from dredge samples provided by the miners here in

Central Bay.

So these are optically stimulated luminescence age

dates.

So the date the last time at which the sample was exposed to

sunlight.

And so that could be the time at which it got into water deep

enough to block sunlight or the time at which it was buried by

other sediments, preventing it from being exposed to sunlight.

And so very interestingly, the the sand here in Central Bay

seems to be younger than the sand here in Sassoon Bay.

This sand is three, 4000 years old.

This sand is a couple 100 to maybe 1000 years old based on

our preliminary results.

And I’ll talk about how we can improve this going forward.

The other data that we have here is we know the history of sea

level rise since the last Ice Age across this part of the

system from independent work that was done on sediment cores.

And so we know that the shoreline during the last Ice

Age was somewhere out here at the at the what is now the

modern continental shelf.

Slip break and sea level pushed what would have been a combined

Sacramento, San Joaquin Delta from this position back across

what is now the continental shelf through Golden Gate Strait

and back to its modern position up here in the Bay Head over the

last 18,000 years or so.

So from this we can interpret our kind of transport age into

the Bay.

So it looks like most of the sand, at least the sand that

we’ve been able to date is somewhere between a few 1000

years old to there is some new sand in Sassoon Bay.

Anybody that’s been to the lower Sacramento River knows that

there is some sand still moving in the lower SAC.

But at least what we’ve dated from the dredge samples, it’s

probably a couple of 1000 years old.

The sand out here in Central Bay and the outer coast was probably

largely originally transported into the system several thousand

years ago when sea level was much lower.

And subsequently maybe it’s been reworked and sloshed back and

forth by waves and tides.

But the original date that it was transported back into the

system is several 1000 years.

OK.

So we can combine all this into kind of a model for transport of

sand into San Francisco Bay through time.

So 18,000 years ago, we’re in a global Ice Age.

Sea level is 150 meters lower than it is in the modern.

And at this time, a combined Sacramento, San Joaquin Delta

sits at the shelf edge.

This is largely sand that’s being derived predominantly from

the Southern Sierras based on the fingerprints.

And it’s probably leaving kind of a blanket of sand in a delta

that’s sitting out here.

As global sea level begins to rise, this delta gets pushed

back across what is now the continental shelf, probably

leaving a blanket of largely southern Sierra and derived sand

across what will become the continental shelf.

As sea level continues to rise, sometime between about 8 and

6000 years ago, this delta gets forced back through the Golden

Gate Strait.

Simultaneous to this, for climate reasons that we’ll talk

about in a second, the dominant source of sand coming into the

San Francisco Bay system shifts to the northern Sierras and

perhaps other smaller local drainages over the next couple

thousand years.

Sea level continues to push the Delta back to its modern

position.

The Bay head delta was about here at Browns Island about 4000

years ago, which is consistent with our residents time dating

the ages from those dredge samples.

And then out here we don’t have any active sand input from the

delta in all likelihood based on this residents time history and

on our fingerprints.

Instead this sand is probably largely being kind of reworked

relic sand via tides and waves from sand that was carried

several thousand years ago, plus active coastal erosion.

Obviously sea cliffs all over California are eroding via wave

action and so active coastal erosion is also probably

inputting a little bit of sand here.

But largely by the time we get to a few thousand years ago, we

have these two disconnected sand transport systems.

OK, so why does the source of San Francisco Bay sand shift

from South to north of time?

Well, during the last Ice Age there was an Alpine ice sheet

across the southern Sierras.

It turns out having an ice sheet on top of granite is a very

efficient way to mechanically erode sand.

And so during the last glacial period up until about 13,000

years ago, this ice sheet was probably doing a lot of work

mechanically eroding and producing a lot of sand out of

the southern sea eras through natural climate cycles.

Over the subsequent 13,000 years or so, and this is evidenced by

a number of other independent climate proxies, the southern

sear and ice sheet starts to melt.

The southern Sierras get warmer and drier and regional

precipitation patterns shift more moisture to the northern

Sierras.

And so we start raining more on the northern Sierras.

We melt all the glaciers.

We dry up the southern Sierras and so this is likely the reason

that the sediment sources shift towards the northern Sierras

over the last couple 1000 years.

OK, so back to the conclusions real quick.

We can come back to these in a second, but there is one more

thing that that I want to note in terms of this luminescence

dating.

And so this type of luminescence dating, luminescence dating

these dredge samples from the sea floor was something that we

had thought from the literature was conceptually possible, but

this was the first time that had been demonstrated to be

particularly effective.

No one had ever done this kind of thing before, at least in

terms of dredging up sand and trying to date, you know, sand

in a sand mining lease block.

And so we think that a broader expansion of this OSL dating

would be a very valuable thing to potentially add to future

understanding of sand transport.

If we know things like how frequently is sand in Central

Bay being recycled through beaches?

How totally is sand that’s coming in from the river being

bleached?

How long has sand in different parts of the system or different

depths within the subsea floor sand reservoir, how long it’s

been there?

That’s potentially a very valuable thing to understand to

our broader understanding here.

And so with that, I’ll, I’ll just stop.

And I, I will also end with a picture of Chrissy Field because

we also took a sample there.

And I’m very happy to, to answer any questions.

And Matt Malkowski, I think is still on the call too, so he can

add some perspective if he wants.

OK.

So do the miners have any comments at at this point that

they’d like to share?

Erica Yes, just real quick, we’re going to provide a couple

of comments on this study and Aaron again will be doing that

for us.

Thank you.

Yeah, thanks, Erica.

I, I don’t, I don’t have a whole lot to add to to the study.

I think I’ll just use this time and let the commissioners ask

questions.

I, I didn’t see any major concerns or we don’t have any

questions or issues with the methods applied.

OK, well, I do have a question and it’s, I think this is just

one of those things for years I’ve heard about.

It’s sort of like the, the, you know, the folk history of

sediment in San Francisco Bay is that it all came from the gold

rush.

So what happened to the sediments that worked through

the system into the gold rush?

I remember reading an article by Patrick Bernard maybe 10-15

years ago where he said they were all worked through, but you

didn’t mention them.

So where do they fit in this?

Zach, you’re, you’re asking all the good questions today.

You’re nailing it.

Yes.

So that is definitely true.

And there’s demonstrated evidence that the Bay floor rose

particularly with fine sediment after the gold rush.

And so there’s a, there’s a couple of, there’s a couple of

reasons.

So this is, this was this was a question that we entertained and

we’re still entertaining.

There’s a couple of reasons why we don’t think that that is the

specific explanation for what we’re seeing here.

The most important of which is that this sediment at least a

lot of what we’ve dated is thousands of years old or

hundreds of years old based on the residents times.

And so it’s way, way, way before the gold rush.

And so this was something that we originally incorporated and

have incorporated into subsequent proposals about

taking sediment cores and actually seeing if we can see

that effect of gold rush sand coming in.

But from everything that we’ve seen in the sand size fraction,

the sand that we’re looking at probably predates most of the

gold rush.

A lot of the sediment that was washed out and started to fill

in parts of San Francisco Bay during the hydraulic mining.

Was fine silt and mud.

A lot of the sand that was produced there is still probably

sequestered up in the upper parts of the Sacramento River

and the tributaries.

Some of it probably made it down.

But we think that the broader climate effect over the last

couple thousand years is what we’re seeing as opposed to the

much shorter time scale effect of the hydraulic mining, which

definitely puts sediment into San Francisco Bay.

But everything that we see seems to indicate that the sediment

that we’re looking at is older than that.

Thank you.

So in other words, the glaciers, the machines of the glaciers

were just really what dominated the systems that you found.

OK, Great.

Commissioner Gunther.

Yeah.

Following up on that, I wanted to ask a question about

transport and about the whether we know.

So for example, in 1862 with the great flood, do those, does a

winter like that have the ability to pick up a whole bunch

of that sand that’s still hanging out in the Sacramento

River in the wherever the Merced River slows down and things drop

out, pick it up and throw it into Sassoon Bay in one fell

swoop?

I mean, so that that that the horizontal transport across the

landscape can be very episodic.

And so do we know anything about to be able to say something

about that?

So that the ’cause it would seem to me, I guess I’m trying to

understand whether there could be an overlay that’s on the

scale of decades based upon major storm events against this

thousand year story that you just told us, right.

Yes.

So, so that is definitely the case that there should be pulses

of, of sand sized sediment into the Bay.

But I, I think the kind of perspective to take here is the

fact that anything that does come into the Bay here is gonna

be mixed with anything that’s already there via title action.

And what we’re talking about in terms of these time integrated

thousand year time scale changes in sediment history is gonna

swamp out any very short time scale introduction of new

different sand.

And so the bulk of the sand that is sitting here seems to be

probably thousands of years old.

It’s been there, it’s been there for quite a while.

And so that’s thousands of years of volume of sand being in

there.

That if we’re looking at a dredge sample in particular,

that’s not just sampling the upper, you know, couple

centimeters of the sea floor, but it’s integrating, you know,

meters down deep.

That 1000 year integrated signature is not gonna pick up

those shorter time scale pulse events, at least not with the

the methods that we’re using here, right.

But if you’re facing questions about regulating or not

regulating sand mining on the scale of, of these activities,

on a scale of a decade, I’m very impressed by the fact that Fort

Knox show you can dig a hole and it’s still there and you go down

just over across the channel of the Presidio, you dig a hole and

it disappears.

It’s filled back in and, and, and it sounds like up at Sassoon

Bay, we dig a hole and it stays there.

But does it stay there until we have a great flood and then it

fills up completely?

I’m trying to understand whether we can anticipate, you’re right.

How does that this is the problem when you have biologists

talking sediment?

It’s like that the rate at which the change occurs in the

environment is a key thing for us to understand and assess

impacts, right.

So I, I think that in part your question is probably better

answered by a sediment transport modeler.

But one thing that I will say is that when we were doing this

study, we actually had a really hard time finding sand in

shallow cores in this area.

And so a lot of the, a lot of the cores that we had access to

were old USGS cores and maybe a meter, maybe a little bit more

than a meter if we’re lucky in, in total depth.

And we had a really hard time finding near surface sand.

And so the sand samples that we got here are dredge samples that

were provided from the lease blocks from the mining companies

where they’re going, you know, deeper than what a three inch

aluminum pipe from the USGS was going, you know, a meter or so.

We were anecdotally surprised how little near surface sand

there was in these areas when we were trying to find samples of

sand to analyze.

Thank you.

Hey Zach, do you wanna take your slide down?

Maybe?

Oh, yeah, yeah.

Thanks.

Sorry.

We can see you better that way.

Brenda, could I try to answer or, or throw in my 2 bits for

Commissioner Gunther’s question?

I, I, I think that in the, over the past few years, and I forgot

the exact war year 2018-2019, there was a very large, you

know, you’ve had some really large flow events during this

sand mining study.

That have not filled in the Sassoon Bay mining areas with

sand.

Now some things have changed geologically very recently, such

as construction of lots of dams on the Central Valley rivers,

construction of, you know, the use of like the yellow bypass

for trapping sand or that’s the net effect of it.

And also that the the the glaciers that Zach mentioned

that we’re producing a lot of the sand are no longer present

in the Sierras.

So there have been some changes like that also.

That would all account for that now when we have.

But for us in our highly regulated Central Valley

watershed, when we have a big flood event, it just isn’t

delivering that sand anymore to to Sassoon Bay like it did

perhaps 102 hundred, 500 years ago.

I don’t know if that helps.

Yeah, obviously I’m being influenced as well by the

changes in the fines and how that’s affect the phodic depth.

Just Wednesday at the water board, we made a huge decision

about nutrient, future nutrient treatment in the Bay because

we’re not getting the the we’re we’re getting a lot more

production because we have a lot less turbidity in the system.

So, but this then makes it so, so I’m getting the impression

that that that, you know, sort of what we see is what we get on

on the scale of thousands of years that we’re not seeing

short term fluctuations.

And and and and Zach, I just got to say this was fascinating.

Thank you so much.

I this is really great stuff.

I I everything.

Every time I think I know something about the Bay, I

learned something more.

And thank you, Brenda, for putting this program together.

It’s really great.

Yeah.

I’m just also going to to query the slides will be available on

the website or will they not be available on the website?

What’s to do with the slides?

Yes, so we, I put it in the chat a little earlier.

All of the three presentations that were given today will be

combined in are combined into one PDF and they will be on the

website.

We actually tried to post them this morning.

I looked, they’re not there yet, but if you go under the

Commission tab and look for commissioner working group,

you’ll find this sediment study or SAN studies Commissioner

working group.

Look there, that’s where they’ll be.

And I just chatted Aaron separately and he said he would

provide his slides as well.

So we can add those to the available slides so that the

commissioners and members of the public, other interested folks,

if you’re not a member of don’t know who you are and take a look

at those slides as well and kind of compare apples to oranges.

And as I, as I mentioned, we will do it.

We will likely have Lester McKee at one of the next meetings to

talk more about San budget and we can have a fuller

conversation about that as well there.

And then Brenda, we will also have a chance in the future to

learn more about some of the nuts and bolts of what it means

to mind sand from the Bay and hear more from the industry.

Yeah.

So what the, what the plan for this working grip?

It’s a very short, short lived.

Now we’ve had the Providence report and we could time stamp

this commissioner working group.

It is scheduled to last through November.

There’s a total of 4 meetings.

The next one is August 21st and it’s a 11:50, so not quite as

late in the day.

Thanks for everybody who’s hung out with us this long on a

Friday.

And the concept that we’re working with is the

commissioners asked a series of questions, the studies responded

to those questions, also the management questions.

And so we’re going to structure the agenda around having a study

or two, depending on the breadth of the study and what we think

the conversation will take over the next two meetings.

The fourth meeting that we have, I think we’ll probably talk and

I don’t have this all completely laid out, but we’ll talk about

some of the Bay Plan policies.

We will, I think, get to some of the commissioners questions from

the Commission meeting and yours, Andy, like how much of

the sand is used in the Bay region?

Are there alternatives, some of that as long as we’re all

efficient and get through the sand studies, we’ll have those

or at a meeting or something.

Anyways, so that’s the plan.

We’re going to hit the studies you grounded in the science and

then talk about broader.

I’m going to say societal and policy issues.

So I also want to say, commissioners, that it is your

working group, Yes.

And if there are questions that you want answered and if you

wanna have another meeting or are there topics that you think

absolutely have to be covered or needed to be covered.

I mean, I would definitely encourage you to tell staff

because I view this as yours not run by staff.

Well, I for 1:00 AM really glad that we’re gonna have these

slides to look at because particularly those graphs, I

need to think about them some more before I finish with my

list of questions.

So I’m glad they’re going to be available and but they really

are fascinating science.

So this is a wonderful opportunity for all of us.

Do the minors.

I know we want to make sure that that group is represented in

questions and comments.

Do you have any things that you would like to share at this

point?

We’ve appreciated what you’ve had so far.

Not not right now that I would be remiss to if I don’t say

that.

You know, we also are very excited about a lot of the

science work that was done here and all the effort that was put

into all the, the numerous, numerous meetings and the

numerous discussions.

So you know what, there are things that are still need to be

addressed, and that’s why we had those points, you know, being

part of the appendix of the report.

But overall, we feel very pleased with, you know, all the

effort that was put into these.

Great.

OK.

Well, I think that brings our meeting to a close.

Pat, before that, you need to just legally ask for public

comment.

That’s right.

Of course we do, yes.

Do we have any public comment?

If there’s anybody who would like to make a comment at this

point, please raise your hand and zoom and we will give you 3

minutes.

Seeing none, I’ll move to adjourn.

And thank you everyone for your attention and for the great work

that you’re sharing with us.

It’s it’s much appreciated.

OK, bye.

Bye.

Thanks, everybody.

Thank you.

Thank you so much.