September 4, 2024 Sand Studies Commissioner Working Group

Let everyone in, OK?

It looks to me like we have our independent science panel

members who were planning to be here and it looks like we have

the full just double checking complement of the sand mining

community members.

So and then we have quite a few members of the public interested

parties.

Thank you all for joining.

So I think we are ready to get started when you are Pat.

OK, well, I’m, I’m certainly ready.

My name’s Pat Showalter, and I’m ABCDC Commissioner and the chair

of this sand mining subgroup.

And I want to welcome everybody to this educational meeting and

we’re gonna hear 2 great presentations and also have time

for questions.

So with that, I’ll I’ll let Brenda talk about our ground

rules.

Yeah, Thanks, Pat, and welcome everyone.

So for those of you who have been here before, you know the

ground rules, but basically this is a fairly open forum to

discuss and learn about the sand mining studies that we’ve been

working on for the last, I guess, three to five years, a

long time and are grateful for all the work that folks have

been doing.

So if you want to join in the conversation, you’re welcome to

do so.

The way the meeting will run is we’ll have a presentation, we’ll

have a moment for the OR period of time for the sand miners to

provide comments on the presentations.

We will move to commissioner questions or thoughts.

And at that point in time, if you have things that you would

like to add or questions, please feel free to raise your hand and

we’ll call on you.

We do have a schedule we’re trying to stick to so we can get

to both presentations today, but I think we have plenty of time

and there is a public comment period at the very end if you’d

like to make a statement of public comment beyond just

discussion and questions.

And I’m going to quickly just jump into my very quick

obligatory presentation for contact setting for folks who

may not have been here.

I will do that hopefully quickly because I think most of you have

seen this before, but just to make sure everybody is on the

same page and, and I just need to find my presenter mode real

quick, which, ah, there it is.

It’s moved.

OK, All right, so we are here today.

I’ve got the wrong date on my calendar on my cover sheet, but

we are today on September 4th to talk about the sand mining

studies.

Where we’ve been so far is back in 2015 as part of the BCDC

permitting process.

Linden Martin Marionetta, which was formerly Hanson Aggregates,

provided $1.2 million to study sand mining impacts on the

community, excuse me, on the Bay, not the community, sorry.

We formed a Sand Technical Advisory Committee, which was

made-up primarily of the regulatory and resource

agencies.

However, Baykeeper and the Coastal Commission, which is not

a Regulatory agency in this setting, but a commenter, joined

the group because of their high interest in the studies and

potential effects of mining.

So that group looked at management, develop management

questions, did study scope development, posted a request

for proposals and reviewed proposals.

We also have our very esteemed independent science panel, which

three members are here today.

So we have Craig Jones from Integral, we have Bob Battaglio,

formerly of Environmental Sciences Associate.

We have Dave Scholhammer, USGS Emeritus.

And we also had Paul Work, who was also of USUSGS at the time,

and also John Lazier, who’s the Director of Oceanography at the

Bodega Marine Lab, University of Davis.

They reviewed the proposals, revised the scope because

they’re, as the proposals came in, there was some clear ways

that we could make more efficient and coordinated

studies.

We identified this, they identified the science teams and

worked with the teams as they completed the studies.

And then they developed the findings report with Santech.

Currently, we are in a commissioner working group.

We’re on the third of four to try to help the commissioners

ground themselves in science and this group is providing

leadership to the larger Commission.

Our next steps are the Sequa NEPA process with State Lands

Commission and potentially the Army Corps of Engineers on NEPA

and then permitting through the various agencies.

And so the study questions that we were working to address are

listed here.

I’ll just read the overview questions of sand mining at

existing lease areas at permitted levels having a

measurable or demonstratable impact on sediment transport and

supply within San Francisco Bay.

What are the anticipated physical effects of sand mining

at permitted levels on sand transport and supply within San

Francisco Bay in the outer coast?

And are there other feasible alternatives to sand mining or

approaches to consider in San Francisco Bay?

The studies focused on the physical processes.

The biological issues are associated with other studies

and investigations, some of which have been completed and

others are in the literature.

And so I’ll just move on from here to our next slide.

So quickly just reminding us of the lease areas.

So Martin Marionetta is the primary or only minor within

Central San Francisco Bay.

The areas in purple are the lease areas.

There are four lease areas with 9 parcels.

This lease area in Raccoon Strait is not mined.

The leases are from State Lands Commission in this case and the

majority of the sand mined in this area is primarily coarse

grain.

There is also fine grain sand that is mined primarily here.

Presidio Shoals area.

And then the Sassoon lease is the other primary mining site in

this project.

So this is mined by Sassoon Associates, which is a

combination of Martin Marianetta and Linda Marine.

The mining in this area is up to 45 deep feet deep.

It is again a lease from California State lands and it is

primarily fine grain sand.

That’s where most of the mining occurs.

And the last lease area, which has the smallest amount of

mining at this point in time is Middle Ground Shoal lease area.

It is mined primarily by Linde Marine.

This area is up to 30 feet deep.

It’s adjacent to an island, a very small island called Middle

Ground Island.

It’s a private lease.

And this is, again, fine grain sand.

The equipment used is hydraulic dredging.

So Martin Maria has a suction dredge piece of equipment.

Here is the drag head for Martin Marionetta’s equipment.

And Linde Marine uses a suction pipe, slightly different

equipment, both hydraulic and both are equipped with a fish

screen on the outside of the pumping mechanisms to reduce

entrainment.

It’s important to frame the mining activities in that this

mining is done primarily well, actually 100% for construction

aggregate, aggregate.

It is not done for navigation dredging.

So this is not a navigation.

These are not navigation projects.

It’s not generally considered a beneficial reuse because

beneficial reuse is generally considered a waste product

that’s being reused for other purposes.

It occurs year round and there are no work windows, but the

fish screens that I mentioned previously reduce entrainment

with the on the intake pumps.

So the mining basically occurs on an as needed basis in both or

all three projects an order is filled with the grain size that

is required for the jobs.

And so in this industry, the sand mining closely follows the

construction industry and trends and mining tends to be repeated

in the same areas, in the same on the same lease areas because

of this need for a specific grain size.

In the last two meetings, we had four presentations.

The first one was the independent Science panel’s

findings report, the overview of the findings.

And then we had University of Texas at Austin provide San

Providence and Aging report.

Delterra’s last meeting did a volumetric change analysis and

transport presentation and San Francisco Estuary Institute

provided a sediment and sand budget review of their work.

Today we have basically two more.

I think these are our final studies if I’ve got that

correct.

So is sand mining at existing leases at permitted levels

having a measurable or demonstratable impact on sand

transport with San within San Francisco Bay?

So Michael McWilliams, formerly of Anchor QEA and Brian Beaver

worked on this document and they have the sand transport modeling

report and presentation.

And the second presentation today is same question but

looking at more or less sand supply and the changes within

the bethemetery of San Francisco Bay.

And that will be presented by Bruce Jaffe, formerly of US

Geologic Survey and he is retired but back for on demand.

I’ve had a few questions from folks about where to find past

information, so I just thought I’d try to briefly run you

through where you can find this on the website.

Today is September 4th.

Our last planned meeting is November 22nd, right before the

Thanksgiving holidays, so we’ll hope you all be there.

This is a snapshot of BCD CS landing page on our website.

To find the old meetings, you go to meetings and then you toggle

on down.

If I can get my computer to share it to the meeting area and

you can look at it in a list view or a calendar view, but you

go to the date where the meeting was.

And if you click on that, that should get you to this page

where you’ll find the agenda and the presentations.

And for August 21st, we don’t yet have the transcripts up, but

there will be a transcript of all of the meetings.

So you can actually watch the meeting if you missed it.

So that is my quick context setting.

I’m gonna stop sharing and turn it back over to you, Pat.

Thank you.

All right, so next, do we have any?

First of all, do we have any questions related to this

context setting from the commissioners?

This Andy or Barry, do you have a question?

OK, seeing none what about other people who are participants?

We have 42 right now Wow, that’s great wonderful interest.

I’m looking for raised hands.

OK.

And I’m not seeing any.

So I think Kat, is that correct?

Correct me if that’s not anyway.

So I think that what’s what that means is we want to go on to the

main presentations for this meeting.

What are the impacts of sand mining on on sand and transport?

And Michael McWilliams of Flow W is going to I know Michael

McWilliams is going to make a presentation and after that we

will hear from the sand miners.

So Michael, would you like to get started?

Great, thank you.

Pat, let me share my screen here, hopefully.

OK, does everybody see that?

OK, yes, OK, perfect.

So this is a study that I did a couple years ago while I was at

Anchor QEA with Aaron Beaver, and I’m just gonna give kind of

a high level summary of what we did with the hydrodynamic and

sediment transport modeling.

I think it’s really great that Bruce is following this

presentation with some of his work looking at longer term

bathymetric data sets because we’re both kind of asking and

trying to answer the same question with two different

lines of evidence and really kind of looking at two different

time scales.

So the computer model is really looking at a one year time frame

to understand, you know, what’s happening where the sediment’s

moving on a, you know, shorter time scale.

And then, you know, we’ll see from some of the work that Bruce

is gonna talk about with the longer term cumulative effects

of that is looking at the longer term bathymetric change record.

Because from a, from a modeling standpoint, it becomes not as

computationally feasible to look at, say 30 years of change, but

we can look at, you know, individual years of change.

And so one of the things I think that was really great about

this, the way the Stan study was structured in general, is there

were a whole bunch of different scientific studies using

different approaches to try and answer different parts of the

same question.

And then, you know, we can learn a lot from how those different

approaches corroborate or or don’t corroborate each other.

So the, the focus of the presentation today is going to

be on the sediment transport modeling that we did for, for

BCDC as part of this SAN studies.

So I’ll begin by reviewing the model scenarios and the analysis

approach and then I’ll talk about the results both in

Sassoon Bay and Central Bay.

And then I’ll give kind of a synthesis of what the the

primary findings of the the modeling are.

So first talking about the sediment transport model

simulation.

So we have a A3 dimensional hydrodynamic sediment transport

morphologic wave model that we’ve developed over the last

almost 25 years now of of San Francisco Bay that extends from

Point Reyes out here in the Pacific Ocean all the way

through all of San Francisco Bay and the Delta.

It includes, you know, all of the main Delta tributary

inflows.

It includes the temporary barriers and operable gates in

the in the Delta and includes all the different agricultural

diversions representative of agricultural diversions and

return flows.

And then as part of this study, we used the work that SFBI had

done on looking at all the inflows to the Bay and we added

all these blue arrows around the Bay or different small tributary

with sediment inflows that we added to the Bay because we

wanted to incorporate all of the potential sediment sources.

The model runs with the tides at the ocean boundary and then we

have, you know, water and sediment coming in from from all

of these these tributaries.

We have an initial sediment bed in the Bay that we’ve developed.

I think there’s about 3000 or so different sediment samples

around the Bay that we’ve spatially interpreted, spatially

interpolated to get the initial grain size.

And then we have used various different information on grain

size from the the tributaries to figure out and estimate what the

grain size of the sediment coming in from each of the

tributaries are.

And then lastly, we looked at the data from the sand mining to

understand what the, the sediment properties of the sand

from the sediment mining was.

As all this doc, all this information is documented in

the, the modelling report that we provided to BCDC and the,

the, the, the sand mining panel.

So I think if you want any additional details on, on some

of this, a lot of that is, is documented in that, in that

report.

So we run this model for with a 92nd time step.

So it cycles through, you know, every 90 seconds it calculates

all of the, the transport of water and salinity and sediment

across the whole Bay delta system.

And then this incorporates the effect of winds and tides and

all of that in into the model simulations.

So the goal of the model scenarios was to investigate how

sand mining effects sand transport.

And So what we did to do this is we developed basically 2 sets of

parallel conditions.

The first is basically the existing bathymetry based on the

surveys we have from after the sand mining was completed.

Basically all of the existing bathymetric surveys are

representative of the conditions with sand mining.

And then we wanted to come up with an estimate of what the Bay

would look like if we didn’t have sand mining.

And since we are simulating one year of simulations, what we did

is we developed a kind of an alternative condition where we

added back the amount of sediment equivalent to the

annual volume of sand mined from the Central Bay and from Sassoon

Bay.

So essentially we got all the records from the sand mining for

for where the sediment was mined with the sediment material was

and we basically added that material back into the Bay.

And that does two things that, that that affect the, the

transport #1 any, you know, when you add that sand back, any

depressions or, you know, deepened areas that are there

because the mining occurred, you’re putting sediment back

into that spot.

And #2 you have that sediment then back on the surface of the

bed, which is able to move around.

And so we wanted to look at specifically what happened to

that sediment that was mined when we put it back.

Where did it transport?

And then, so we tracked that sediment different from all the

other sediment.

And then we also wanted to just look at the total amount of sand

transport.

Basically, if we had that sand, that sediment back in the Bay

and we simulated a wet year and a dry year, how how different is

the sand transport?

And you know how big is the signal of where the transport is

different because you added that sediment back or, or you or you

didn’t.

So you kind of have basically 2, two different conditions.

That one is that it’s a little bit, in some ways a little bit

counterintuitive to get to get your head around.

But the existing condition is with site and sand mining.

And then the kind of the artificial condition that we

developed this scenario is the without, without sand mining.

And we tried as as much as we could to represent the grain

size and spatial distribution of the the sediment that we added

back.

So by by running a wet year and a dry year with these two

different geometries, which are only different by, you know,

adding that sediment back into the central Bay and adding that

sediment back into Sassoon Bay, we can evaluate where that

sediment that was mined was transported over that year.

We can compare changes in the in the, the thickness of the

sediment bed between the two scenarios.

And we can also look at it any given cross section, how much

sediment passed through that cross section.

So if we put that sediment back into the mining area, does it

change the transport of sediment, you know, upstream or

downstream from there?

So they’re kind of pretty focused questions looking at you

know on on the time scale of one year what what was happening.

So we looked at two different years.

We looked at a wet year and we looked at the period between

June 2018 to June 2019.

And we looked at a critical year, which is the driest of the

five water year classifications in California between June 14th

and June 2014 and June 2015.

And these periods were picked partly due to the availability

of data on the sand mining that occurred in those years and

partly just to to capture a wet year and a dry year.

So you can see here in the wet year this is showing the delta

outflow in thousand CFS.

We see very high outflows in you know, 175,000 CFS in the the

summer and then in the dry year the the peak was just over

50,000 CFS and it was relatively small.

So we can see a very big difference in the total amount

of of water flow in the wet year and in the dry year.

And then you know, there’s an associated difference in the

sediment supply from those those two different years at all.

So for each of these conditions, we simulated the baseline

condition, which is basically you know how conditions are

right now with the historic sand mining that happened in that

2018-2019 and then the the baseline conditions for the 2014

to 2015.

And then we have the equivalent scenarios for both of those

where we’ve taken the the initial bathymetry and added

back, you know, a one year annual amount of of settlement

that was mine.

So this shows the differences in the two scenarios.

So basically this is an estimate of the amount that was that was

added back for the mining.

I think this is for the wet year.

So you can see basically here that just here in Central Bay

adding sediment back primarily, you know, in in these these two

areas here.

And then there’s some sediment added back here along Ships

Island in Tassoon Bay and a tiny bit here at this middle ground

Shoal lease area.

So from a computer modelling standpoint, everything about

these two scenarios is exactly the same.

The tides are the same, the winds are the same, the waves

are the same.

The only difference is in one of them we’ve added back this

additional sediment to the to the model and the other one is,

is without that sediment.

So we can then run the this computer simulation for a year

and we can understand how the transport of of sediment is

different whether or not that that sediment is put back in.

So we’ll go through the the two different areas separately,

first Sassoon Bay and then Central Bay.

So this is the the same kind of figure we just looked at here.

For Sassoon Bay.

This is showing the sand that’s added back into the model before

the initial simulation and then this shows at the end of the one

year.

Where that sand was transported.

So in the high outflow year, we can see the sand that was

initially put here is largely transported, you know, back and

forth in the the main ship channel there’s a little bit of

eastward transport.

Past Chips Island, there’s transport in Sassoon Bay and

then generally the, there’s, we weren’t seeing very much

transport at all of that sediment from Sassoon Bay past

the Bulls Head Shoal over here at, at Carquena Straight.

So one of the things that that you do see, you know, there’s a,

there tends to be a convergence area of sediment here because

you have the deeper, the deeper area here in Carquena Straight,

you get some gravitational circulation and, and return

currents near the bed.

And then in the low out flow year, the picture looks pretty

similar.

Generally a lot less transport of that sediment away from the

the sand mining areas.

But one thing that you can see from this is that the, you know,

the effect of the sand mining in Sassoon Bay over this one year.

Is pretty localized to, you know, this, this main channel

area of Sassoon Bay.

It’s not, it’s not having an effect upstream very much and

it’s not having an effect really past, past pull central.

We can look at the predicted bed thickness across the entire

Sassoon Bay between the two scenarios at the end of the

year, basically anywhere that’s white on this map.

This is for the high, high outflow year is less than .1

centimeter, so like 1mm difference.

So basically what you see in most of Sassoon Bay, you really

have very little effect of the sand mining that that’s showing

up.

The biggest effects are, you know, really localized to the

sand mining areas, which which shows that that that the mining

is not having a big effect on, on deposition across the rest of

of Sassoon Bay.

And then if we look at the low outflow year, it looks it’s a

pretty similar picture.

Most of the Soon Bay we have virtually no difference in the

thickness of the sediment bed at the end of the year.

And the primary differences are, are, are still focused in these

areas where the mining occurred.

So, you know, we put that sediment back in, in the the no

mining case and that sediment is still largely, you know, in that

area and hasn’t moved that much.

So that’s telling us that the the effect of the mining is

really very localized into soon Bay to the to the mining areas.

Then we also, and this is pretty similar to the some of the work

that Mick van der Wagen and the the tires group probably showed

at one of the previous meetings.

We wanted to look at the, the sand transport vectors of the

direction and magnitude of sand transport from, from the model

simulations.

And so there are arrows on this figure here on the left showing

the sand transport during the high outflow year.

And they’re color-coded based on the, the direction.

So if they’re red, they’re, they’re basically pointing

seaward.

And if they’re blue, they’re, they’re, they’re pointing

landward.

And so one of the things you can see is there tends to be some

landward kind of back towards Sassoon Bay, transport of

sediment along the bed here in Karkina Strait.

And this is one of the things that we we highlighted in our

report is you do get this convergent zone of sediment

deposition here at Bulls Head Shoal.

That could also be another place where you know, there may be

potential for for sand mining where where you have this

already build up of sediment that’s causing a need for fairly

frequent dredging by the Army Corps of Engineers in this

Bullhead Shoal region.

But it’s another area where the sand is is largely converting.

We can see here the predicted change in sand transport without

mining.

This is basically just the difference in transport.

We can see the Red Arrows here along Chips Island and a little

bit here in the the ship channel.

Those are the areas where we’re seeing the biggest difference

in, in, in sand transport.

And then throughout the most of the rest of Sassine Bay, you

know that you don’t really see much difference.

And this is so real.

This is really telling us the same thing as what that other

picture was showing, which is that the effects of the sand

mining at Chips Island here in Sassine Bay are relatively

localized and they’re not having a big effect on on sand

transport in in the rest of Sassine Bay.

So we looked at a bunch of different cross sections in the

West here starting at Venetia Bridge and in the east, the

Sassoon 1, which is right at the edge of of Chips Island.

And you can see here at the Sassoon cross sections 1-2 and

three, which are the ones very long Chips Island.

There’s a pretty big difference in the amount of sand flux

between the mining and without mining.

In particular at the Sassoon too, which is right in the

middle of the the mining area in Chips Island.

There was, you know, more downstream transport of sand at

at that section in particular without mining than there was

with mining.

The percentage is very high and that’s partly because in the dry

year the the sediment flux was very, very small in the baseline

condition.

So the magnitude of transport increased some, but it ends up

being a high percentage because the baseline value is like very

close to to 0.

So but what you do see here is that Sassoon 4-5 and Venetia

Bridge and Sassoon cut.

So in this whole rest of the portion of Sassoon Bay, the

effects of the sand mining on, on sediment, on sediment

transport on sand transport is, is very small.

So all, all these different ways of looking at it are really kind

of showing the same thing for Sassoon Bay, which is that the,

you know, the effects of the mining is pretty localized here

along Chips Island.

And then the rest of the same Sassoon Bay doesn’t have as much

fact effect of the of the sand mining on transport.

So we do the same analysis for Central Bay.

This is showing the regions where sediment was added back

into the the model to come up with the estimate of what the

without sand mining conditions would look like.

And then we can show basically where that sand that we put back

was transported after one year during a high outflow year and

during a low outflow year.

So that the sand that we we put back in Central Bay is largely

stays within Central Bay.

There’s some transport of that sand out through the Golden

Gate.

There’s some transport of that sand, you know, a little bit

upstream here along Angel Island and between Treasure Island and

Angel Island.

But the effects are, are pretty localized to the Central Bay and

then you know, the, the transport out out the Golden

Gate.

If we look at the predicted bathymetric difference between

the, the, the bed at the end of the one year in the two

different scenarios, most of the difference kind of the red

colors that are up to 10 centimeters are focused in the

areas where the mining occurred, which which makes sense, right.

So we put that sediment back into those areas.

There’s the sediment bed is still thicker at the end of one

year in those areas, most of the areas are you know this white

color is .1 centimeters, so 1mm.

So anywhere that’s white, we’re not really seeing any difference

at the end of of one year.

The Gray is, is .1 to 1 centimeters.

And then so you can see generally the effect of the, the

sand mining is still focused in the, in the the mining areas.

But we do see some, some more sediment moving out the Golden

Gate here and a little bit moving up into this part of

central Bay in, in the high output year.

And then a similar picture here for the, this is for the low

output year.

So we can see in general the sediment staying pretty close to

where we put it, but there’s some of it is, is being

transported out in the Golden Gate.

If we look at the maps of the the sand fluxes, it’s it’s, you

know, it’s relatively complicated circulation

patterns.

We see sediment fluxes from central Bay out the Golden Gate.

We also have these kind of return circulation cells along

the sides that I think you also can can see from some of the

work that that Deltares showed.

And then the difference in in flux between the two different

scenarios.

This is the high output year on the top and the low output year

on the bottom.

The biggest difference we’re seeing is that there’s a little

bit more flux of sediment out through the Golden Gate in both

of these conditions, which is because we have more sand

availability that we we put into the Bay for that year.

We’re seeing more transport out the Golden Gate.

If we look at it as a percentage without, without sand mining, we

do see a larger flux of Westford, Westbrook, westward

sand transport out through the Golden Gate.

It was about 142% higher in the wet year and about 50% higher in

the the dry year in terms of the amount of sediment that that was

predicted to move out through the Golden Gate.

And without sand mining, we see a little bit less sand transport

through Raccoon Straight.

So there’s a there’s less of a net transport through Raccoon

Straight in the scenarios where we have added back the sediment

here.

And then there’s really not very much effect here at this line

here between Angel and Island and Treasure Island or across

where the, the Bay Bridge is.

So this is showing us that largely the biggest effect of

the mining that we’re seeing in the model is without sand

mining.

We see a larger flux through the, the Golden Gate and a a

smaller flux through Raccoon St.

Now I’m gonna move on to just some of the the some of the

primary findings, which is summarizing what we saw from the

modeling in the context of some of the other work that the

studies did.

What we’re seeing in Sassoon Bay is largely episodic westward

sand transport.

So when we have periods of very high elevated delta outflow,

that appears to be responsible for most of the sand transport

through Sassoon Bay to San Pablo Bay.

The sand mining reduced the predicted westward transport of

sand, but those effects were pretty limited to the area right

around Chips Island.

During the one year periods we looked at, we didn’t see any

effects of the mining in Sassoon Bay extending past Venetia

Bridge.

This could be, this could be an artifact of the fact we are only

looking at one year.

And if we had looked at, you know, simulating 2345 years that

could have propagated further West.

But across one year, we largely didn’t see any effects of the

Sassoon Bay sand mining extending past Venetia Bridge.

And part of that may be that there’s another, you know,

there’s a pretty high area of deposition here at at Bulls Head

Shoal where where you have the convergence of of sand

deposition.

And that may be limiting the effect of the the sand transport

propagating further downstream.

But it would probably require a longer multi year simulation to

try and understand how long it would take to propagate that

that mining effect further downstream.

This is the conceptual model from Bob Battaglio here showing

the the transport of sediment out the Golden Gate.

And then you can kind of see these cells moving sediment back

along along the shoreline.

We had a net predicted sand flux from the model out of the Golden

Gate to the Pacific Ocean.

We also had these cells predicting some transport back

into the Bay in in some periods.

We saw that the sand mining was predicted to reduce the

transport of sand out of the Golden Gate and it didn’t have

very much effect, you know, east of the mining at either Angel

Island or, or at the Bay Bridge.

So we, the model is suggesting that that removing sand from

from the central Bay potentially does reduce the sand available

for the San Francisco bar and the other beaches.

But because we’re only again looking at one year and the

transport times and distances are relatively big, you know,

it’s hard for us within the model simulation to to come up

with it a direct relationship between the mine sand volumes

and how that affects, you know, sand volumes that make it to

Ocean Beach.

So I think those are areas where some of the other lines of

evidence such as the bed forms and the longer term bathymetric

change may be more more useful for for answering some of those

kind of longer term morphologic changes.

And that’s what we have for the presentation.

But I’m happy to take any questions that you have.

OK.

Well, first we usually go with Commissioner questions.

So Commissioners, do you, do you have any questions?

If so, please speak up.

Yeah, Pat, I’ve got a couple of questions.

Great.

Can you find my digital hand here too raise it.

So thanks so much for this presentation.

I’m first question is we flip back and forth in our language

between sand and sediment and, and I want to make sure that I

understand that, that when you’re using the term sediment

in this presentation, you were still referring to sediment of a

grain size that we would call sand.

Yeah, yes, that, that was my probably sloppy language in that

context.

But yes, we, we are modeling the full range of sediment sizes,

silts and flocks and fine sediments.

But everything that we’re showing in this is only focused

on the sand grain material.

The one, the one caveat I would say about that though is when

we’re looking at the thickness of the sediment bed and the

difference in the thickness of the bed that includes all the

sediment, but all of the transport is purely just the

sand.

OK.

And then when you say that, all things considered, it looks like

there’s some small, some reduction in the amount of sand

that would have moved out of the Golden Gate, which kind of makes

intuitive sense.

But that number, while the percentage change seems large,

that number relative to be a total amount of sand moved is

pretty small.

Am I right saying that the the the change in sediment mass

going out the Golden Gate relative to the total volume of

sand mining is relatively small?

Is that what you’re asking?

Yeah, yes, I think that’s, I think that’s correct.

OK, great.

And then lastly, the, the, the picture of the model that you

presented with all the inputs from all the different

tributaries into the Bay is very impressive, but it seems to me

it opens up it, it’s a huge challenge to try and like

validate this thing.

I mean, I, is there an underlying sensitivity analysis

that you’ve done to try and look at, you know, how variations in

flow rates in some of these different inputs change the

overall projections of the model?

Yeah.

So one and one of the tricky things for this, the sand study

specifically is there’s not a lot of these repeated

bathymetric data sets to be able to model, you know, what

happened.

The the place we do have those are in some of the the ship

channels and in some of the the harbors that get deepened.

So with this, with this same model, a couple of years prior

to this study, we did a, a study for the Army Corps of Engineers

looking at the Port of Oakland, which I think is pretty directly

relevant to, you know, to this, the Central Bay Area in

particular.

Because we have, we have pre and post dredge surveys across four,

I think 4 different years that we looked at for that project

where we would, we would set the bathymetry to what the post

dredge survey was.

And then we would simulate like one year until they did the next

pre dredge.

And we would look at the amount of sediment that was deposited

and we could look at that, you know, across wet years and dry

years.

So we did do a lot of validation of deposition in in Oakland

Harbor.

And I think one thing that that you know, probably relevant to,

to this is that, you know, in the wet years we were seeing,

you know, more than twice as much sediment deposition at

Oakland Harbor than in the dry years.

So what we were trying to focus on in that study was what they,

they had done the deepening from like 42 to 46 to 50 feet.

And then and they were trying to understand how much the

deepening caused the amount of sediment deposition to go up.

Because as you kind of, I mean, it’s kind of also intuitive.

If you dig a hole, nature’s going to kind of want to fill it

in.

So as you deepen these harbors it, it accelerates deposition.

But, but it was really hard to see that signal because it was

swamped by the signal of, you know, you have a wet year,

there’s twice as much sediment that comes in.

And, you know, the estimate of the, the deepening, you know,

was a, you know, 20% change in, in, in shoaling rates.

And you said there’s twice as much sediment coming in during a

wet year.

That is a sediment of not that’s not just sand, that’s all types.

Yes, yeah.

And, and, and if I understand it, the amount of sand that’s

moving is, is, is small.

See, I come from the kind of contaminant background where I

didn’t really care very much about sand moving because the

contaminants are moving in the finer grain material.

But, but now I’m, I’m trying to make sure I disconnect my, my,

my sediment thinking to really be focusing on the larger grain

materials.

And then my last question was about you mentioned that in Bull

at Bull’s Head Shoal, so that there is some need for dredging

there.

But again, the dredging, if I’m dredging for navigation in the

Bay, I’m not pulling up material that can be commercially

exploited as sand.

Is that right?

I guess it depends on what the grain size of the material is.

I think there is some sand that builds up on that Bull’s head

shoulder Brenda might actually have.

Yeah.

So yeah, Andy, the sand both in Sassoon channel, which is a

federal navigation channel in a different part of Sassoon and

Bull’s Head reach is 95 to 99% sand.

And it’s that very similar fine grained sand that is currently

mined out of this other part of the reach.

So it’s an interesting question as to whether or not mining

could occur on Bulls Head Reach, which actually causes emergency

dredging episodes on a fairly regular basis because it starts

to encroach on the navigation channel.

But it it is sand, right.

So I guess just so, so, so one question I would have, we don’t

need to answer it now, but if the Corps of Engineers is

pulling up sand, what are, are they’re just disposing of it And

then we have the companies pulling up sand and selling it.

And so it would seem to me that we that they’re sort of sort of

economic market questions here, but I’d like us to think about

those a little more.

It seems we should only be extracting from the Bay that

which is, you know, needed seems to me so OK, thanks.

I appreciate that.

So Commissioner Nelson has his hand up, but after Commissioner

Nelson, I’d like us to go to the sand miners to present their

comments.

Sure, Commissioner Nelson.

Thanks, Pat.

I just want to make sure I’m not over interpreting the results

here.

I don’t know if you can skip back to some of the slides that

show changes in sand transport in the Central Bay with and

without mining.

One of the questions that, yeah, one of the one of the questions

we’re asking ourselves is whether there’s an impact of

sand mining there.

There was one that called that that that showed flux and I

wasn’t sure I understood the difference between flux and some

of the other slides There, there that one, this one.

Yeah, yeah.

And and the previous one that shows the that shows the graphic

that that one right.

And so the I’m looking at the the the two graphics on the

right predicted changes to sand mining, sand transport with

without sand mining.

One of the things we’re asking ourselves is whether it’s

potential that Central Bay sand mining could have an impact on

beaches.

I I recognize that asking that question about beaches outside

the Golden Gate is pretty tough given our previous presentation,

the last time we had this call.

But but the Marina Green, the beaches, beaches of the highly

used beach along the Marina green is right there next to

next to the sand mining area.

And this this sand transport corridor, but where this shows

measurable changes in sand transport, it’s very much in the

deep channel.

And as I look at that, it doesn’t give any evidence any,

does any suggestion that there would be erosion off of the the

beach in northern San Francisco along the Marina Green caused by

that sand mining.

Am I interpreting those that this, this graphic correctly?

Yeah.

I think that the difference is really the, you know, the, in

both the low outflow and the high outflow year that we’re

seeing, the difference is these red, these red vectors, which

means, you know, transport out.

There’s a little bit of blue, you know, along the shoreline,

which is a, a reduction of, of land with transport.

But the, you know, the conceptual model, I think is

largely the sediments coming out through the Golden Gate.

But then there’s also these like recirculation, you know, more,

more shore hugging transport back in, in, in that image from,

from Bob Batalo.

I can, I can show you.

I, I have a couple slides that I, I, I have here that, that

show the, the sand flux here at the Golden Gate for, for the

different cases.

So I think if you look just kind of at this bottom panel, this is

showing the blue is the the amount of sand flux going out

through the Golden Gate across the year in the within the the

baseline.

And then the green is the amount of sand flux that’s going out

across the year in the the with sand mining.

And so that’s where that that’s where that percentage comes from

at the end of the year.

You have, you know, this is the the net transport of sand flux

in the baseline and this is the the net transport in the in the

without sand mining.

So that’s how you end up getting the 100 and and something

percent there and the the high output year.

So I’m just going to take a moment and note for folks that

BCD CS jurisdiction goes from Point Bonita to Point Lobos.

It does not stop at the Golden Gate Bridge.

And just as a reminder, we do have a bit of jurisdiction in

the outer area of the Bay because I know not everyone on

the call knows that.

Bob, are you on the same topic?

Yes, I just wanted to clarify something for Commissioner

Gunther and while Michael McWilliams was on the line.

It’s my understanding that the model results that we’re looking

at does not include longshore sand transport.

We call littoral transport driven by waves along the

intertidal shore and that’s a a known thing and we we all

understood that.

The other point I wanted to make is that it looks like there’s

more than one travel path.

There’s the ebb and flow, ebb and flood exchange that

transports sand out and in, out on the ebb and on the flood.

But there’s also a wave driven transport from Ocean Beach

around Point Lobos, past Baker Beach, etcetera, around Fort

Point and then along Crissy Field.

So the model didn’t show the transport along Chrissy Field or

the effect that the sand mining might have on this other

transport path.

Thanks, Bob.

Yeah, thank you.

Thanks, Pat.

Do you want to go to Aaron?

Yes, Aaron Holloway is here and he is going to present some

information from the miners.

Erin, are you?

Thank you, Pat.

Yeah, I’m ready, available.

I’m gonna share my screen here.

OK.

Thank you, Michael, for the presentation.

I know that was quite an undertaking to model sand

transport throughout the Bay.

Sorry.

Let me losing my navigation here.

What I wanted to just talk about too is kind of linking the

findings from the anchor model to some of what you’ve already

heard in the in the previous presentations.

So some of the key findings from the model was that there wasn’t

a consistent westward transport of sand from the delta through

the Bay and out out through the Golden Gate.

So that, you know, sort of consistent with the disconnected

system that was presented by the stratigraphy team.

And so that also sort of contrasts with what the sand

budget study looked at, which was assuming kind of this whole,

all these embayments are connected and if you have a

surplus of sand in one area, it’s going to flow to the next.

So we want to kind of bring attention to that.

And then the other important finding we thought from the

anchor modeling was that the sediment transport from local

tributaries was negligible and that there wasn’t much sand

transport, you know, past the head of the tide from these

local tributary sources.

And that was a that’s a, you know, substantial source of sand

to the Bay given that there’s not much coming from the delta

anymore.

And so in the sand budget, the local inflows were, you know,

the 0.36 million metric tons per year is what went into the sand

budget.

So we just a quick comparison of, you know, on the left is the

the disconnected conceptual model presented by the strategic

team where you have kind of different sources in Central Bay

versus Sassoon Bay and that, you know, they’re not necessarily

connected in terms of supplying sand to one another.

But then when the when the sand budget assumed all them payments

are connected, you get kind of this this flow of sand from

Sassoon Bay through San Pablo Central Bay and out.

And so it seems to me the anchor model is implying a more, you

know, complicated sand transport system that’s not necessarily

connected, you know, from the delta through the ocean.

And so we think that’s an important conclusion to

highlight.

And then the second one is just talking about kind of the scale

of impacts that I think Commissioner Gunther was hinting

at is that, you know, the, the effects of sand mining in

Central Bay were found to decrease, you know, if mining

had not occurred.

So the, the order of magnitude there was, you know, 30 to

40,000 cubic yards.

But again, there’s, it’s a very complicated system and the model

has limitations.

And so it’s important to to discuss those.

And, and I think that Michael and Aaron did a great job in

their report.

They have a whole section on kind of model limitations.

They did the sensitivity analysis.

So there’s a lot that goes in to such a dynamic system and

evaluating sand transport.

So I know they’re, they’re not entirely confident in the

magnitudes, but we think it’s, it’s worth, you know, comparing

that to the prior numbers that we just talked about in the last

working group meeting with the sand budget.

So in looking at the flux at the Golden Gate again, the the net

flux predicted in the model is just a fraction of the total

flux.

So with a large amount of sand moving each way, the the net is

a much smaller amount of that you know.

So if the net goes in and out of the Bay in this predicted range

from the sand budget, the model result is a a net flux out of

the Bay of about 80,000 cubic yards.

So less than the sand budget estimate of 2000 cubic yards a

year out of the gate.

So we just thought it’d be helpful to kind of bring the

numbers together from the different studies.

And then the last or the some of the key limitations, I think

I’ve already been discussed, but but there’s lack of data on sand

transport in these areas that make it difficult to to validate

the model.

And then it, the model doesn’t include simulation of ocean

waves and swell propagation through the Golden Gate, which

is obviously a key part of the dynamics in that system.

And then the other item is the, the mine sand was represented

with a single grain size.

But in the central Bay, you know that we’ve demonstrated that

the, there’s coarse sand fractions which are mined more

extensively in the, in the northern lease sites.

And then the southern lease site, which is a more dynamic

system is a finer grain size, the finer sand size.

So that’s as expected.

But our concern is that if you’re going to apply a fine

grain size where they’re mining coarse sand, you’re going to see

a greater impact than may actually occur.

So that that’s could be one of the reasons why there’s, there’s

this kind of distribution of sand, you know, in this central

Bay Area, which is actually quite coarse and may not, may

not behave the same way that the model predicts this other, you

know, this finer sand to move.

And that’s, that’s all for the, the discussion we had.

Well, thank you.

That’s great.

Appreciate that.

So I don’t see any more questions.

So I hope we don’t have we’ll have them toward the end of the

meeting.

So now we can go on to our next our next presentation which is

from Bruce Jaffe and he is going to be answering the questions or

working on answering the questions.

What are the impacts of sand mining on the Bay bottom?

And we really appreciate Ruth coming out of retirement to

share these findings with him and take away Bruce right now.

Well, Bruce is sharing his screen.

If folks could take a minute and put their name in the chat just

so we can make sure that you are captured for the interested

parties list, please.

Thank you.

I’m still making some edits to my presentation.

So anyway, let let me say that it’s a pleasure to be able to

share the work that that we did on this study.

The the key people I should say are Teresa Frigoso and Amy

Foxgrover.

And I just finished my edit so I can share.

You take the cake, Bruce.

I’m usually doing it the last 10 minutes.

Well, on Zoom, you can do it as it’s going.

No, it’s just.

OK.

So let me see if I can share screen.

Yeah, this should be the right.

Oh, wait, not that one PowerPoint share.

We can see it.

It’s not in presenter mode yet.

There you go.

All right.

OK.

And I’m gonna move some people off the screen.

All right.

So Lester McKee presented to an earlier working group meeting

and about an approach to look at the effects of sand mining using

a sentiment budget and he showed this slide and circled in red is

what our group contributed to that study.

I will point out that we are also part of the stratigraphy

study, which is interesting on how they’re, they do have

different approaches and different conclusions.

So let me let me tell you how we, we came up with a number for

the, the change in storage for for sand in the system and that.

So it was very fortuitous that we had just finished the study

on bathymetric change in the system and that it was in in

large part funded by the the settlement work group for the

Bay and what’s shown here.

Let’s see, do you can you see my pointer or not?

I don’t think so.

OK, Upper left is 1980s survey.

It’s color-coded by depth.

You can see the channels.

Lower left does 2010 surveys.

So this allowed us to do a time step that we hadn’t done.

We’ve been looking at historical changes from the 18, mid 1800s

to the 18 to the 1980s.

And what’s shown is that the the areas where there’s erosion of

the bed and a potential source of sand to the system are in in

blue colors.

And the areas where there is deposition to the bed or gain in

the bed were areas where sand might be sequestered.

So pretty simple outline talk about the methods, the results

uncertainty analysis cause uncertainty’s key to to to

determining whether you can trust what what the study

results are in a summary.

And if time allows, I could talk a bit of that said trails,

although Mike McWilliams talked a little bit about it on how

it’s looking at the connections between different parts of the

Bay in terms of the sand transport.

And that was a pilot study funded by USGS.

OK, So the methods gravity cores were taken, this is not San

Francisco Bay in the picture.

Obviously there’s ice and we we’re not on such a big ship,

but it shows the gravity core well where it’s just, it’s like

a dart that has hundreds of pounds of weight on it that just

free falls and goes into the sediment.

And these cores were taken between 1990 and 2016.

And in total there were 186 cores.

And the length of these cores varied from about 50 to 360

centimeters.

So we’re looking at it collects sediment, depending on what the

depositional and erosional history is, that could be recent

if it’s in a depositional area with some older scent beneath it

or sediment that’s hundreds or even hundreds of years or even

older than that.

And on the right you can see the distribution of the the the

cores and you can also see in yellow where the mining areas.

OK, So with the as geologists, what we do when we get the

cores, as we split them open, we take a look at them and we log

them.

And these are just a couple paper logs.

The symbol for sand are dots.

So you in in this with this, the core log on the right, you can

see lines of dots and we then took the information from these

cores and that’s a paper log.

This is now interpreted.

These are published in open file reports and you can see the

symbols and again there is some sand in in this core in the blue

on the left.

So we take all this information and I won’t bore you with the

trying to describe this, this slide.

But basically what we needed to do to be able to determine

whether the the bed of the Bay was a source or a sink of sand

is we needed to to look in the the sediments to see whether or

not, you know, see where the sand was located.

And we did this at 10 centimeter intervals and it involved

correcting for the fact that when the core is collected so

that we we had a, a common vertical datum and we shifted

them.

And then this is all on the report the details.

But what what became apparent very, very quickly was that the

cores alone just didn’t have the coverage that we needed.

So we then augmented the the core data with surface samples

and we evaluated what what the error introducer, the

uncertainty introduced by doing that.

And surprisingly it wasn’t as large as we anticipated.

It’s about a 10% uncertainty by augmented, but that allowed

another 700 locations where we could then create a 3D map of

the sand content or 3D model of the sand content of the

subsurface sediments.

So we had done something similar to this in Alviso Slough where

we use cores and instead of trying to estimate the sand

distribution in the in the subsurface settlement we we

used, we were looking at Mercury remobilization.

This was work with Amy Foxgrover published in 2019 and there’s

Mark Marvin Day bus quality was was lead on the Mercury part of

that.

He’s from the USGS as well.

So we did this approach where we created this, the 3D model for,

for the subsurface sand content and we did it in the embayment

scale and it was a significant amount of work.

Again, Teresa Fragoso and Amy Fox Grover did a fantastic job.

Each of these sub embankment models had about 3010cm layers.

And this is just an example of one layer, 110cm layer.

And it’s, it’s actually an amalgamation of, of different

sub embankments and you, you can see this is from zero to 10

centimeters.

And you can see the, how heterogeneous the Bay is in

terms of sand.

The more yellow, the colors, the higher the sand content.

So interesting pictures, but that we have we have to analyze

it then to get our answer whether the Bay is a source or a

sink of sediment of sand.

Sorry, I want to point out that Sassoon Bay because there were

not the themitry surveys there in all of 2010 and San Pablo Bay

in the shallows.

We’re not when, when I talk about the the Bay, I’m talking

about the, our study here, which includes most of the Bay, but

not the entire part of the Bay.

And then I, when we for initial analysis, we excluded mining

areas shown in yellow here, dredging footprints and orange

and disposal sites in a in a kind of a pinkish color.

We did go back later on and account for those separately in

a later phase of our analysis.

So the results different sub embayments were either a source

or a sink of sediment of sand.

Sorry, the blue shows the sub embayments that were a source.

These were places where there was sand in the, in the bed that

was eroded.

And so more sand is available then for other parts of the Bay

or to go out the Golden Gate, the red and it’s primarily

central Bay is a place where there was deposition of sand so

that the bed was a sink.

And Michael McWilliams talked about his his time scale of a

year limited by computational times.

So we normalize to a, to a rate per year.

And this is the normalized rates and the in total it was about

1/4 of a million cubic meters of sand that was supplied by

erosion of the bed per year.

And this is for all the areas excluding where the human

activities were.

So might not be a surprise to anyone that the human activities

were significant.

So here’s a comparison of the rates of change and sand volume

and the bed for the the two mining areas, Central Bay and

Sassoon Bay.

These are the lease areas and Central Bay alone is quarter

million cubic meters per year so soon as about a tenth of the

1,000,000 cubic meter per year and all the other areas we’re

about a quarter million cubic meters per year.

Now this is lost from the bed.

Obviously the mining material what’s been mine is a different

beast than the areas outside the human activities where it’s it’s

not gonna be available for other either to go out to Golden Gate

or other parts of the Bay.

And these are just from bathymetric change.

So the this does not account for the amount of my materials that

was reported in as mined.

It’s just from for that 1980s to 2000 tens.

There was a lowering of the bed in in these these two mining

areas.

So uncertainty analysis, I could go into this salon for quite a

while, but I won’t it’s in the report.

So the three sources of uncertainty that we addressing

the report was uncertainty from interpretation of the core logs,

uncertainty from augmenting core data with surface at sent and

samples and then uncertainty associated with bathymetric

change analysis.

So the first two uncertainties are easy to quantify.

The third is not the uncertainty interpretation core log.

It did change the magnitudes of the of the sand volume in the

bed, the rate of change the sand volume in the bed, but it was it

on, you know, 20% change from going from conservative minimum

sand content to our best estimate or from a maximum sand

content to our best estimate.

Augmenting with surface sentiment samples which assume

that it was a representative of the of the sentiment below did

not have a large effect.

It was about a 10% and like the interpretation of the core data

of the core logs it it didn’t have an effect on the direction

that is the the bed in the areas away from human activities was

still a source of of sand.

The uncertain in the bathymetric change is potentially

significant and so it depends on the degree of randomness and

survey errors.

So if the survey errors are random, they cancel out and the

uncertainty is and mathematic change is low.

So, and if the survey areas are systematic, the uncertainty in

bathymetric change could is is large for a large area?

For the small areas like sand mining leases which the

uncertainty from bathymetric change is low.

And So what we presented in the report was what the these

uncertainties translated to.

And then it’s really depending on what your use for the data is

you can, you can and how random you think the survey errors are,

you can assign a a value to it.

So in summary, the question whether bed sediments in San

Francisco Bay are sources sand is answered.

So that’s this is the change in the storage.

So bed sediments are a source of sand, not too surprising because

a lot of the Bay is eroding and so if sand is in the sediments,

it’ll be a source.

But it, it, it hadn’t been shown till this this study.

And then how certain are we of this answer the interpretation

of sand content in the core logs or from augmenting the data with

surface sediment sample data doesn’t affect our our

certainty.

And the answer the the uncertainty of bathymetric

change could be potentially significant.

So additional studies could be made done on on how random this

this error is.

From my experience, random that the errors are random, but I I

can’t rule out that there are systematic errors.

But the systematic errors would have to be systematic over many

different separate surveying events.

So in my way of thinking the likelihood of that is not as

great.

And then how does sand volume changes in mine years compared

to areas without human activities?

I’m just reiterating the result that that the sand volume change

in the bed in the mining areas and this is from bed lowering as

a net I said is either greater than or similar to the sand

volume changing areas in the areas without human activities

in the Bay.

So as I said before, there’s publication Center, publications

group and there’s also two USGS data releases of the data used

in the analysis.

So with that questions and discussion.

Thank you, Bruce.

So first, we’ll go to.

I have a couple questions, but first we’ll go to the other

commissioners.

Andy or Barry, do you have some questions here?

No, no, nor do I.

OK.

Well, yeah, I just wanted to reiterate Bruce that.

So basically as I understand your summary and thank you for

being so clear about this that you know, going to the question,

I think that’s always really helpful.

So basically you’re saying that that from the bathymetric

investigation, the change in the sand mining areas and the change

in the other areas isn’t really statistically different.

Is that what you’re saying?

I wouldn’t be as as direct on statistically different, but I

would say that there’s same order of magnitude, same order.

I said that’s what you said.

You’re right, statistically.

So it’s just and I, I would, I’d say that this is not a a after

all this work, I would say it’s not a, an earth shaking result.

It, it fills in, you know, missing data and you know, it

allows a sediment budget to be calculated.

But to me that the results from the stratigraphy team, those I

think are, are more profound, especially the results that the,

the material being mined is, is old order, 1000 years old.

And I’m glad that the, you know, that the study was able to

accommodate them, that the way they they were able to to date

the material.

And the sand miners were incredibly helpful in, in, in

allowing a collection of material on a moonless night

with no lights, red lights, so that they didn’t reset the the

quartz screens for optically stimulated luminescent dating.

So I think that I think that’s a a very key, key result.

OK, thank you.

Yeah, I, I think you’re right.

Sometimes confirming what everyone has theorized over many

years with real data.

It it it’s just very, very important.

And and that’s seems to be what this study that you’ve done has

done.

We people have talked about this for a long time, but you’ve

actually collected data to show that indeed the standard

hypothesis is, is is correct.

So that’s, that’s a big, at least from my point of view that

that’s a big contribution.

OK.

And that’s a perfect segue.

Your comment about the sand miners being productive, very

productive members of this investigation team is is really

right on.

So we will go to Aaron Holloway.

Would you is there anything you’d like to share with us

right now, Aaron?

Yeah, sure I do.

I have a question for Bruce.

But before I get there, I wanted to bring up a topic that was,

you know, at I think Commissioner Gunther and Nelson

asked it in the prior topic about sand transport and the

city of Golden Gate and in Bay beaches.

And I just wanted to note that the, the beaches that were in

question, I think Crissy Field Marina Green, those have have

been experiencing accretion.

And so there’s a, there’s a clearly a supply of sand

arriving at those beaches.

And I don’t think that transport pathway was, was resolved in the

model, but I think I think that was a point Bob was making as

well.

But just wanted to clarify that.

My question for Bruce is the in looking at the results in your

report and then the results from the stratigraphy team, the one

thing I noticed was that the strategic free team said that

San Pablo Bay was they had a hard time finding any sand when

they were looking at the cores throughout San Pablo Bay.

But I noticed in your study there’s quite a bit of sand, you

know, in the cores or the surface sample.

So I’m just wondering, I assumed you were kind of looking at the

same cores, but maybe not.

Do you have any thoughts on why that kind of those different

conclusions could be reached?

We were looking at the same cores.

The stratigraphy team’s ability to look at multiple cores was

limited, as it’s the case in all scientific investigations, but

especially in their case.

So, yeah, the, the cores that we, we were able to, you know,

these are course from 1990, the course we were able to, to, to,

you know, look at did not have a lot of sand in them.

So it’s not, it’s not that the result is not that the

conclusions are different.

It’s just a matter of limitations of the study.

If, if there was, you know, if there was a, a desire to

continue the studies, the, you know, a better effort could be

made to, to find those, those cores with the sand.

And I think one of the limitations of the study was as

they were doing it during COVID, so they had very limited ability

to be at USGS.

So I, I know that COVID is starting to sort of feel like

it’s in the rearview mirror a bit, but it, these studies were

all ongoing during COVID.

So there was some challenges associated with the pandemic as

well as time limitations.

That’s entirely true.

This we had a it was even more limited because we were working

at the USGS core facility and difficult to get access.

So during COVID.

Well, another thing I’d just like to thank you for is kind of

talking a little bit about the connection between the work you

did at Alvesa Slough related to deposition there.

That was that’s that, you know, that was really so revealing and

how we do the marsh restoration and it’s a it’s a really, really

learned a lot from that.

And you know, we don’t often getting to do basic science

associated with these problems is is really important and

you’ve been part of that for a long time.

But so I just wanted to put a shout out again for the LV so

slow work.

If we if we hadn’t done that LV so slow work, we would have

never undertaken this work ’cause we developed techniques

there and and applied them here.

Oh, well, that makes me feel good because we did wrangle

quite a while for that contract, didn’t we?

Yes, it was not a it was not an easy process administratively.

OK, well, I think this, this is my understanding is now we need

to have questions from anyone who is interested.

So I would look forward to people, participants raising

their hands with questions.

Please use the raised hand.

And I think if there’s no questions, I’m kind of scrolling

through myself.

I don’t know, Bruce, if you wanted to share the said trail

slides since we don’t have questions and we have half an

hour unless people have questions, of course.

I, I, I get that, that this type of study is different than

what’s normally done.

And perhaps if there’s questions that come up when, when either

looking back over the presentation or the report, feel

free to to contact me or Teresa Frigosa or Amy Fox River.

So let’s see.

So I just have a few slides on said tools, said trails.

Sorry.

So this was a very late thought of of, of something that could

be helpful for understanding sand mining and and its effects.

So had the leeway to do a pilot project it it this is so this is

a tool set trails.

It’s a tool developed by Deltares.

There’s a group there, Mick van der Wagen, floor rolls ink are

are the two of the people who worked on this.

And the, the, I think Pearson is the is the, the set tool set

trails developer.

So it visualizes sediment transport pathways and

connections.

And so it starts with a a model with model output, which is

hydrodynamic output and the models that Deltares uses Dell

3D four and D4 little FM.

And then that’s in Eulerian that that means the output is its

first sells for fixed points.

And then it uses formulations to get Eulerian sediment transport

fields.

And then it takes that data.

And then instead of looking at the those, those vectors in A at

a fixed point, you go into the Lagrangian framework where it

follows points or follows particles and sees where they,

they end up in a system like San Francisco Bay.

It’s, it’s not intuitive because it’s, it’s tidal.

So depending on when the particles started, when the sand

grain here starts moving, it could either go into the Bay or

out of the Bay.

And as well, if there’s a flood event, that’ll definitely have

an effect.

And then the part that and is was developed that I was

particularly interested in, I mean the, the, the visual

visualizations of of sediment or sand pathways is I think it’s

very interesting.

Michael McWilliams showed some of those from from his model,

but they they’ve the people at Deltares have developed an

assessment of sediment connectivity.

So I’m just gonna show one place in Central Bay where they did

this as part of the pilot study.

There is a memo on this and I can contact Mick Vanderwagen and

and team about sharing that memo.

I have no problem with sharing it.

I think it’s a great tool and can be used in many different

applications where modeling of particles is is is one of the

parts of the study.

So here we go.

So this is for lease area 779 W and on the left are the

trajectories.

So these are of particles that are moving through the lease

area.

So you can see that they come from different places and there

are places where within the lease area where there’s more

particles moving through and places where they’re, you know,

less, less particles.

And this was done for sand.

So I should say more sand or less sand on the right.

I think it’s, it’s another, another application where the

sand particles that were within the lease area where they go and

you can see it’s a different pattern, but this tool and

connectivity, it’s the same.

This is the, I do believe it’s the same area, mining area 1.

And so for the, the red circles is where the sand is coming from

that goes into that mining area.

And the larger the, the, the larger the dot, the larger the

circle, the greater the strength of connectivity.

And then on the right is let’s see.

Oh, I see these are different title cycles, 55 on the left and

50 on the right.

So you can see there’s more connections.

The part the sand’s coming, the red is it’s coming from farther

away, it’s entering the area and then the yellow dots are where

the sand leaving the area and and the connections are

strongest nearby and to the north, which is interesting.

There’s not connections to the South as that are strong and the

open coast as well.

So just wanted to share that that this was this was a pilot

project.

It didn’t do the entire Bay and it wasn’t as sophisticated the

models that can be applied.

So there’s limitations, but it illustrates the concept.

So thanks, Bruce.

And if you do want to share that memo, I think it would be great.

We could pop it up on the website for people to peruse.

The other thing I just want to note for the group is that in

the the Sand study reports are all in Appendix G of the Overall

Findings document.

On our website, however, Bruce’s report is not in there.

So if you’re going to go look for it, it’s not there.

And that’s because USGS has not released it yet as final, final

peer reviewed.

But as soon as it gets released, which I understand from Bruce is

coming very soon, we will post it to the website.

Sure.

OK.

OK.

So thank you very much.

Bruce, are there any questions from commissioners on Bruce’s

last few slides?

OK.

I don’t see any and any comment from Aaron, the minor

representing the minors.

No, no, nothing else.

Pat, thank you.

OK.

Thank you very much.

Well, well, Brenda, we do have a few more minutes.

And so I always like if there’s time to understand what the next

steps are.

I know you went through that at the beginning, but perhaps you

could refresh our memories.

So what’s happening next?

Sure.

So we’re taking a little break between this meeting and the

next.

So the next one is November 22nd, which I believe is the

week before Thanksgiving.

So you all should still be in town, hopefully, fingers

crossed.

And I believe at this point we’ve completed the suite of

studies, the overview presentations of the studies.

And so I haven’t developed the agenda for the next meeting.

Pat, you and I will probably sit down and chat some more, of

course, with Greg and talk about what we’d like to cover.

There’s a few options we can pull up in the policies.

We can pull some literature for biology pieces and or we can

also talk about some of the questions that the Commission

had at the Commission meeting, which were more related to

economics and uses of sand.

So it’s to be determined what the next agenda item is.

Our next agenda is for the next meeting.

We’ll probably do a little bit of pulling together of these

studies as well, but we’ve got some time this time to pull

through that.

Well, that’s excellent.

And then after that, we will be getting together information for

the policy question, right?

Yeah.

OK.

So briefly, what’s the policy, what’s going to come before the

Commission?

Yes, OK.

Want to go over what that is real quickly, What the policy

question is.

Well, I don’t know that we’ll be asking the policy question of

whether or not to permit mining, mining, ’cause this is not that

forum, right?

So this forum has really been about providing the science to

the commissioners so that they can help support the other

commissioners.

And understanding that, I guess that’s what I was getting at, is

where that’s what really this is about.

This is about supplying the science so that we can make a

much better informed decision.

Yeah.

And that’s, yeah, if we do talk about policy, we would just go

over what policies apply to this world, but we would not try to

reach any conclusions or discuss the proposed project because we

don’t actually have the proposed project at this time for the

next.

Well, the other, the other reason I bring that up is

because the policies that BCDC has, although some of them,

they’ve been many of them have been around for many years.

They, there’s a lot of them and so often so, so understanding

the policy contact context of different issues is, you know,

is, is, is not a a small task.

So that, you know, that will be kind of this scientific data

will be useful for us to do that.

And I really appreciate everybody’s involvement in

getting this information.

This has been a huge effort and we we’ve gotten some very

valuable responses.

OK, so last call for then, then I guess we, we always have to

have in in these public meetings a public comment forum.

So formally, I would like anyone who would like to make a public

comment who’s here on something.

These are typically things that are not on the agenda.

But if you’d like to make a public comment to this group, we

would be glad to hear it.

Are there any hands raised?

I have Jen, see you and I also have Andy, Commissioner Gunther.

So maybe we go to Jen first, then Commissioner Gunther next.

Great.

Thank you, Brenda.

Thank you, Commissioner.

These are amazing.

This is an amazing forum to learn more about science and I

really appreciate all the work.

Of course, I guess my question or my comment rather, is I’d

love to see, I’d love to know more about how the science is

applicable to our outer coast areas.

We, you know, we did hear some and mention of Ocean Beach and

the main ship channel and, and that there was a figure that was

shown looking at transport.

It really there’s a lot of resiliency work that of course

is happening and has been for a long time.

I would really love to either get a list of the studies that

have been done that that, you know, would be helpful to figure

out what’s happening on the coast or understand from these

very big brains what additional science is needed to to

understand our our ocean transport, you know, the coastal

sediment transport issues and littoral zone issues.

I’ll stop at that.

Thank you.

Thank you.

OK, Andy.

Yeah.

Thanks, Pat.

So two things I want to just congratulate the staff and the

science committee.

This is, this is the right way for us to do things.

I want to thank the, the, the industry developing this kind of

information over the time we’ve had is gonna make our next

decision about permitting just so much more intelligent and,

and it it’s really important that we do this kind of thing.

I really happy to see this.

This has been an approach that the Regional Water board has

used with its permittees for years and years and it’s been

really, really valuable for focusing our discussions.

That being said, this is a lot to get our heads around and it’s

a very, it’s very complex and the uncertainties are are

difficult to understand and and yet could have a profound

influence on how we frame the the our findings to the full

Commission.

And so I would really look forward over the next couple of

meetings for those of us, those who are the the experts to

really help pull together kind of where, where the agreement

is, where we need to know more and how we might learn that it.

It wouldn’t surprise me to see a structure of a permit where

there’s, you know, there’s ongoing monitoring and invest

joint investigation, this sort of joint fact finding.

I received a letter sent to Brenda by Jim McGrath, who has

studied these issues for years.

That was really helpful to me.

So as we pull this stuff together, I, I think we need to

be, we need to accept that there’s gonna be, to really make

the most of it.

We’re going to, we’re going to need to synthesize it in a way

that really gives a, gives the full Commission an understanding

of where we really think we’ve figured things out and where we

think there’s other questions.

And, and it’s incredibly valuable to have Bob and Bruce

and others contributing in this way.

And that’s going to be is hugely beneficial as well.

So, so there’s just a lot here.

And, and I and I hope that we’ll be able to, to organize it in a

way that can really educate the full Commission when it comes to

that.

And of course, Brenda, that’s your job.

Hey, very well said, Andy.

Well, I think that brings us to adjournment.

One last call for questions.

OK, seeing none.

Thank you everyone for your participation.

I’ve been really impressed with how everyone involved in this

has stuck to it that I mean, we still have pretty much the same

number of people we did at the first meeting.

And that tells me that the presentations have been

fascinating and also that the material that is being shared is

information that people are very anxious to get a hold of and and

really appreciate learning about.

So thanks.

And with that, the meeting is adjourned.

We will re adjourn on November 22nd.