Pro-Mack Mining
Underwater Mining Specialists
Mark Stopher
Acting Regional Manager
California Department of Fish and Game
601 Locust Street
Redding, CA 96001
6 March 2010
Dear Mr. Stopher:
I understand that a presentation was made at the most recent suction dredge PAC
meeting concerning a mercury clean-up pilot project that I personally was involved with
on the South Fork of the Yuba River, Malakoff Diggins, Humbug during 2007 and the fall
of 2008. As I am at somewhat of a disadvantage of not being able to study any final
findings concerning that project, and it sounds to me like some of the results are being
taken out of the proper context, please allow me to go on record in the ongoing suction
dredge CEQA process with a factual basis concerning the project:
I was first contacted about the project on 23 August 2008 by Matthew Wetter of Tetra
Tech EM Inc., which is an environmental services engineering company based at
10860 Gold Center Drive, Suite 200 | Rancho Cordova, CA 95670 | www.tetratech.com.
Mr. Wetter e-mailed me that Tetra Tech was “working with Dave Lawler at the BLM on a
mercury removal treatability study,” and was interested in contracting the services of my
company, Pro-Mack Mining, to provide underwater excavation (dredging work) for the
project. Mr. Wetter asked me to provide a bid for our services. Tetra Tech also provided
the following information:
“Contract Officer Representative (COR): David Lawler is the designated
Contracting Officer Representative (COR) for the project. Mr. Lawler is located in
the California State Office. Mr. Lawler can be contacted at Bureau of Land
Management, CASO, Attn: Dave Lawler (CA-920), 2800 Cottage Way Ste. W-
1834, And Sacramento, CA 95825-1886, Cell phone: (916) 425-3740”
In order to gain a better understanding of the project and make a proper bid, I followed
up in a telephone conversation with Mr. David Lawler. In turn, Mr. Lawler sent me the
following explanation:
BPS Project Title: HUMBUG CK-SOUTH YUBA PILOT MERCURY CLEANUP
PROJECT
BPS Project Number : (#36234)
Description: The Humbug Creek Project site is located at the confluence of the
South Yuba River and Humbug Creek on unpatented BLM administered land within
the North Bloomfield Mining District. Project proposes to remove a mercury “hot
spot” consisting of several hundred pounds of elemental mercury contained within
the Humbug Creek Delta, located at the confluence of Humbug Creek and South
Fork Yuba River. Thousands of pounds of elemental mercury were lost from
historic placer gold sluice box systems at the North Bloomfield Hydraulic gold
mining operations during the 1850’s-1880’s period. Significant amounts of
elemental and amalgamated mercury were than deposited within a hydraulic
tailings dam at the confluence of Humbug Creek and South Fork Yuba River. The
tailings dam has subsequently been destroyed during a series of 100+ year flood
events on the South Yuba, allowing mercury contaminated sediment to discharge
seasonally downstream. BLM manages 7 miles of contiguous watershed on the
South Yuba from 1/2 mile upstream from Humbug Creek to Purdon Crossing. This
site represents an excellent pilot – mercury “hot spot” removal project, since
significant watershed impacts have occurred to the BLM-managed portion
immediately downstream from the hydraulic mine. Project proposes to use
modified suction dredge equipment – combined with conventional placer gold
recovery equipment/technology to recover large quantities of elemental mercury
without undue degradation or impacts to the watershed.
Geographic Description: T.17N, R.9E.,S.14, ,MDBM, NEVADA CO.,
CALIFORNIA (SOUTH YUBA RIVER WATERSHED)
Benefits: The Humbug Creek Delta site is one of the known elemental mercury
“hot spots” known in the Sierra Nevada region with elevated mercury levels in
water and sediment. Removal of high concentrations of elemental mercury
contained in mercury-contaminated stream and river sediments at this site will
eliminate a pollution “point source of discharge” of hazardous materials under the
Clean Water Act and reduce downstream discharge within the South Yuba River
watershed. The California State Water Control Board and other regulatory
agencies require that BLM mandate significant reductions in mercury loads from its
managed lands within the Sacramento River watershed – Bay Delta region, under
its existing basin plan.
Feasibility: This site is one of BLM’s emerging priority AML 1010 sites for pilot
cleanup. Project implementation will include use of modified suction dredge
equipment – combined with a conventional placer gold recovery equipment and
technology to recover large quantities of elemental mercury without undue
significant degradation or impact to the watershed. During FY99-03, USGS
technical specialists have previously collected water, sediment, and biota samples
from selected sites within this watershed. During FY06, USGS technical specialists
and watershed stakeholders (e.g. Trout Unlimited, SYRCL) will coordinate on preremediation
sampling of water, sediment, and biota at this specific site. BLM
coordinators and contractor(s) will also compile all required CERCLA and NEPArelated
environmental documents. Testing of pilot mercury removal methods will
also occur. During FY07, BLM coordinators and contractor(s) will undertake pilot
cleanup of fluvial bedload areas containing elemental mercury concentrations.
During FY08-09, post-remediation monitoring will be undertaken to assess the
watershed benefits of mercury “hot spot” removal.
Support: There is widespread support from interagency Federal partners
(USFS,ACE,EPA), State Partners (DOC AMLU,CWQCB,RWQCB, CA Fish&Game,
Public Health), County Partners (Dept. Envtl Health) and various watershed
stakeholders (Trout Unlimited, NCRCD,SYRCL, Yuba Watershed Institute).Trout
Unlimited has been working on AML partnerships efforts in Utah (American Fork) –
subsequent remediation actions have effectively reduced toxic metal source
loading to downstream watershed environments. Trout Unlimited volunteers can
potentially assist with collecting additional macroinvertebrates and fish from the
project site for bioassessment purposes. The California State Water Resources
Control Board (CA-SWRB) is highly interested in removal of elemental mercury
“hot spots” in priority watersheds. The South Yuba is a 303(d) listed impaired water
body for mercury. The SWRCB will to match funds with BLM on this cleanup
project.
Project Objectives: To develop portable suction dredging equipment that will
effectively recover elemental mercury from submerged sediments.
Subsequently, Pro-Mack’s involvement in the project (hereafter referred to as “BLM
project”) was contracted by Tetra Tech. This evolved into several site visits and a trial
run during the fall of 2007, using a standard 3-inch Keene dredge. The trial run was
mainly to work out how we would do the project during 2008 using an 8-inch dredge.
During one of the site visits, I had a personal opportunity to engage in a substantial
discussion with Mr. Charlie Alpers, USGS Research Chemist, who I understand is a
leading authority on the subject of mercury. Mr. Alpers was directly involved with this
BLM project. As I am an expert in heavy metals recovery, I found Mr. Alpers very
interesting. During our conversation, Mr. Alpers instructed me on several points which
he believed were important in context to the BLM project objective to determine if normal
suction dredges can properly be used to recover mercury from established mercury
waste sites. Here are a few of the points Mr. Alpers made (according to my
understanding, in my own words):
1) The nature of mercury as an element allows it to break down into such small
particles (perhaps smaller than particles), that they can become permanently
suspended in water. Mr. Alpers described this as “colloidal.” This, similar to the
salt in sea water.
2) Through different kinds of physical and biological activity, elemental mercury
can be transformed into different forms and migrate away from the original location
(point source).
3) Mr. Alpers and the other USGS scientists involved in the BLM project made it
abundantly clear that science has shown that very small particles of mercury have
a strong attraction to very, very small particles of light sediment.
4) Mr. Alpers told me that modern science now has the equipment to measure the
presence of mercury in nearly every substance known to man. He told me mercury
is present nearly everywhere. He said the instruments at his disposal would detect
mercury in any of the soils or riverbeds in California.
In view of these revelations from Mr. Alpers, it seemed clear to me without going any
further that standard suction dredges could not be used to remove 100% of the mercury
from established mercury waste sites. Standard suction dredges (use of gravity
separation recovery systems) will be effective at removing all or most of the elemental
mercury down to a certain size fraction. Pro-Mack (and Keene Engineering) has
developed advanced gravity recovery systems on suction dredges that will recover
elemental mercury effectively down to any size fraction within the visible range.
But when you start getting down to capturing colloidal (mercury which has become part
of the water), or capturing extremely fine sediments with mercury attached to them, it is
clear that gravity separation alone (such as the Nelson Concentrator) is not the answer
for 100% results.
Please keep in mind that this explanation is in context to the BLM Project
Objective, which was to determine whether or not standard suction dredges can
be used to effectively recover the mercury from an established mercury waste site
located at the bottom of a flowing waterway.
Sometime during the summer of 2008, the California Water Quality Control Board made
a formal objection to BLM and USGS. In view of the 98% recovery results (of mercury
from an established mercury waste site in another location) by Mr. Humphreys using a 4-
inch dredge, the Water Board did not want us to use an 8-inch dredge at the confluence
of the South Yuba River and Humbug Creek. While I was not privy to all the
communications involved, I was informed by Mr. Wetter that the potential of a 2% loss of
mercury into the water column might be considered a water quality violation by the State
of California.
Consequently, BLM formally revised the purpose of the project to the following (please
see attached Revised Scope of Work for agreement between the USGS and the BLM
which is dated June 27, 2008):
Purpose:
Because dredge operators have collected and recovered large amounts of Hg from
the South Yuba River near Humbug Creek, the BLM wishes to remove and recover
these Hg-contaminated sediments, thus removing a potential environmental hazard
from the ecosystem. However, it is unknown what impact the removal process will
have in the immediate vicinity of the dredge operation or downstream. The BLM
initially proposed to remove the Hg from the confluence using a suction dredge.
Although suction dredging has been shown to recover as much as 98% of the
mercury from contaminated river sediments, qualitative evidence suggests that the
dredging may, through “flouring” of the Hg during the suction dredging, actually
enhance Hg transport and reactivity and ultimately increase Hg uptake in
downstream biota (Humphreys, 2005). Before suction dredging or any other
removal technique can be used, the hotspot will need to be characterized to
determine the potential impact of the removal on downstream environments.
Since dredging within the active waterway was no longer going to be part of the project,
another site visit was scheduled so that we could locate a place(es) to take samples
outside of the active waterway. Matt Wetter may have a record of who participated in
that visit to the site. I was there, along with several participants from the USGS. We
found a gravel bar out in the S. Yuba River that was located near the confluence of
Humbug Creek. We also found some dry riverbed just downstream from Humbug
Creek. As dredging was not going to be allowed, these were pretty-much the only two
remaining options to obtain samples. We decided to sample the gravel bar (located out
in the river) first, and then follow with the riverbed gravels alongside the river.
As I had originally bid the project to provide an 8-inch dredge, and we were not going to
be able to use that, Matt Wetter asked me if there was some other type of gear that Pro-
Mack could provide to assist with the project. So my Pro-Mack team went to work in our
shop to create a suction excavation system that would contain all of the material, using
recirculated water, so that there would be zero discharge back into the active waterway.
This system used the same principle as a normal dredge to create suction at the nozzle.
But this was different because water and excavated material were pumped into a holding
tank, and the water was then pumped out of the holding tank to provide suction to the
nozzle. We were using the same water over and over again within a closed system to
create our suction-power at the nozzle (please see attached images).
Because Mr. Alpers voiced concern about colloidal mercury, and very small particles of
mercury that attach themselves to sediment, Pro-Mack devised a suction recovery
system that would capture 100% of the sediment, along with 100% of the water used in
the excavation process. I ran this idea by the BLM project team in a phone conference,
and the participants (USGS, BLM, Tetra Tech) expressed interest and encouragement.
My understanding is that BLM (Dave Lawler) ran the idea by the Water Board and they
decided to send Rick Humphreys out to observe our project. He was present when we
operated Pro-Mack’s self-contained suction system, and Mr. Humphreys, along with
everyone else present, agreed that we made no discharge into the river using our self
contained suction system.
To my knowledge, this is the only system -concept in existence that will provide 100%
recovery of hazardous materials in all forms from waste sites (mercury or otherwise),
either above or below the water.
Here follow some very important observations which should not be ignored:
1) The gravel we were excavating from the bar out in the South Yuba River was
above the river during late fall flows. They will be underwater during winter flows,
or at least during storm events. This was mostly loose gravel. It was not a hardpacked
streambed; it was not compacted or armored. This means that those
gravels likely get swept downstream during storm events; especially large storm
events. Therefore, any mercury recovery we obtained within our closed system
is the same mercury that will be washed down the river system during storm
events. Since our excavation was small in comparison to the whole area of the
South Yuba that is identified as a waste site, it is reasonable to assume that huge
volumes of mercury are moving downstream during storm events.
2) This was just a trial run of a closed circuit suction excavation system to
determine if it would work. It was only the first phase on a small scale. Tetra
Tech, BLM and USGS agreed to analyze samples of the collected water to see if
our closed system will recover and concentrate mercury; specifically the very fine
mercury that they are so concerned about. Since it was just a beginning-test, I
don’t believe that anyone kept close track of the volume of gravel that we
excavated. More importantly, we did not measure how many times the same
water was recirculated to excavate the waste materials.
While I have not seen the test results on our recirculated water, I understand that
Mr. Alpers stated in the recent PAC meeting that the mercury levels were very
high. This is good. It means our system worked very well to recover and
concentrate the small particles of mercury from the waste site which Mr. Alpers
and other scientists are concerned about; particles so fine in size that no gravity
system alone can be expected to provide adequate recovery if 100% results are
desired.
Note: Before using our closed suction system, after carefully sanitizing the tank
(with a solution which USGS brought along specifically for that purpose), we
carefully filled it with water from the South Yuba River. I am certain that the
USGS team captured and analyzed water samples from the South Yuba to
create a baseline. Therefore, any increase in mercury in the water from our
closed system will be mercury that we recovered and concentrated from the
waste material at the site. The higher the concentration of mercury within our
closed system, the more mercury we removed from the environment!
3) In a closed system such as this, the longer we operate it in the waste site, the
more times the very same water is exposed to the waste, and the more
concentrated the mercury will become in the water. We ran the system for
perhaps two hours or longer. The pump we used produces 350 gallons per
minute. This means the water was recirculated through the waste material more
than 100 times. I understand that during the PAC meeting, Mr. Alpers reported
that suspended sediment and mercury was present in the water from our closed
test seven days afterwards. That is exactly what you would expect to see with
recirculated water that was used 100+ times to excavate mercury-contaminated
material!
4) Very important: While anti-mining activists are sure to try, the results of this
test (concentration of mercury in the water used within our closed system) cannot
be correlated or compared to normal suction dredging in California’s waterways.
Here is why:
A) First of all, we were doing the project in an established mercury hot
spot. Please read David Lawler’s BPS Project description above. This
site is so contaminated, the California Water Board refused to allow BLM
and USGS to operate suction dredge there for the BLM project. Even
while we were conducting our tests, Rich Humphreys was swimming
around the area with mask and snorkel and finding visible mercury on the
bedrock. We were panning mercury from the bedrock just upstream from
where we performed this testing. This place is loaded with mercury
contamination!
It would be grossly unfair to compare the average stretch of California
waterway to this established waste site where “Thousands of pounds of
elemental mercury were lost from historic placer gold sluice box systems”
(BPS Project description).
B) To my knowledge, California’s average waterways have not been
quantified as to the amount of mercury which exists in them. If present at
all, the amount of mercury is sure to vary from one location to the next.
According to Mr. Alpers, some level of mercury can be located anywhere
(everywhere). Therefore, for the purpose of dredge regulation, we
should be concerned with hazardous levels of mercury. We should
not be comparing normal suction dredge activity to an isolated extreme
condition! For the purpose of dredge regulation, it would be highly
indefensible to use the results of a toxic cleanup test as a baseline
average for all waterways in California!
C) The water from our closed system that was recirculated through
mercury waste at least 100 times cannot be compared to the water
discharge from a normal dredging system in an average waterway. Our
closed system exposed the same water over and over to pre-established
mercury waste (continuous exposure for hours). The water flowing
through a normal dredge will have been exposed to gravel only once (for
several seconds), likely in a location which does not contain hazardous
levels of mercury in the first place. Any attempt to compare normal
dredging conditions with a concentrated solution used to clean up a
heavily contaminated site would be completely lacking in intellectual
integrity.
D) Our closed system design appears to have confirmed Mr. Alper’s (and
the California Water Board’s) concerns about potential losses of fine
particles of mercury if standard suction dredges are used to clean up
established mercury waste sites. That is, if California’s policy is to
proceed with mercury recovery only if 100% results can be obtained.
We could argue over whether or not the dredge system is causing
flouring, or if the mercury is already present there in a form that is too
small to recover using gravity methods. But it doesn’t really matter. If our
closed system concentrated suspended mercury in the water, it seems
reasonable that recovery systems (used in established waste sites) must
be developed that contain all of the water which is used during the
excavation and gravity separation process. Then the water will need to
be treated.
E) Because the mercury that is not removed from active river systems is
sure to migrate downstream, and we have already developed the
prototype of a closed excavation system, I would encourage the various
State and federal agencies to continue the important work which BLM and
USGS has been doing in this area. I would be pleased to participate, as
long as the process is intended to clean up California’s waterways, rather
than put suction dredgers out of business.
F) Anyone who would attempt to use the important results we have
obtained in a very serious waste site to reflect upon conditions in a
normal dredging setting is probably more motivated by political gain, than
in cleaning up California’s waterways.
The truth is that suction dredging is the only workable way of discovering
where the mercury hot spots are located in California’s waterways.
According to the BLM BPS Project description above, it was suction
dredgers who discovered the waste site at the South Yuba River and
Humbug Creek. And it will require suction dredges (modified into closed
systems) to remove the contamination. Mercury that is not removed will
haunt California for the foreseeable future.
This very same scenario could be playing out in other locations. Suction
dredgers are the solution to this problem. Shutting them down because
mercury is proven to exist within isolated locations would be
counterproductive. This is because Mother Nature will just keep
pounding that mercury down into more-broadly distributed, smaller and
smaller particles while we do absolutely nothing about it.
5) Most important: Based upon all of the results we obtained in this BLM
project, along with all of the concerns expressed by BLM, USGS, DFG, California
tribes and environmental organizations, there may be some serious problems
with the Nevada Irrigation District’s (NID) plan to clear toxic Gold Rush mercury
from Combie Reservoir (they also intend to use a suction dredge).
According to the press release at
http://www.theunion.com/article/20100227/NEWS/100229808/1066&ParentProfil
e=1053:
“NID had Canadian firm Pegasus Earth Sensing Corp. demonstrate the system
last fall and managed to extract six grams of mercury per ton of sediment
dredged from the bottom of the reservoir. NID routinely dredges the reservoir to
extract silt and keep water capacity as high as possible for customers.”
“Pegasus designed their centrifuge to extract gold from ancient river rock, but
company officials found it did a better job of trapping mercury, according to
Monohan.”
A centrifuge is a gravity separation device. And while very effective at
concentrating heavy metal particles down to a certain size, it will not be effective
at recovering the colloidal mercury which Mr. Alpers is concerned about. Even
worse, a centrifuge is designed specifically to discharge (as tailings) the very fine
particles of light sediment which USGS scientists are so concerned about
(because micro-particles of mercury attach to them).
Perhaps the largest concern should be that all of the colloidal mercury and fine
sediment which is stirred up in the water during the excavation process (“NID
routinely dredges the reservoir to extract silt and keep water capacity as high as
possible for customers.”) will most certainly be creating a water quality violation
of huge proportions — for all the reasons which are being expressed by PAC
participants in the suction dredge CEQA process. The NID Project description
on line shows a diagram of the planned dredge system. More than just a suction
dredge, the NID dredge will employ a cutter head at the nozzle (see
http://evereadymarineservices.com/downloads/Eveready%20Marine%20Services
%204.pdf ). A cutter head is a powerful grinding machine that is designed to
break up solids and force oversized material out of the way. A cutter head will
create enormous disturbance down in the contaminated sediments.
Consequently, some substantial portion of the disturbed water and light
sediments within the contaminated material will be greatly disturbed, pushed out
of the way and not be sucked up as dredged material.
Reading more about the NID project at
http://www2.newsvirginian.com/wnv/news/local/article/old_technology_new_soluti
on/42961/961/
“Tim Crough, assistant general manager with the Nevada Irrigation District, who
is overseeing the project, said the district wants to remove the mercury in its
elemental stage, where it is less harmful.” He said, “Knelson Concentrators’
mercury-removal process combines traditional dredging technology with a “spin”
process, using the company’s Knelson Mercury Recovery Concentrator, to
separate and remove the mercury from the sediment and out of the water. “If we
can remove 95 percent of it, which the Knelson Concentrator is expected to
do, we can free up that much of the river system from having the contamination
of methyl mercury,” Crough said.
http://www.sacbee.com/2009/03/24/1723627/nevada-irrigation-districtplans.
html:
“Tim Crough, the district’s assistant general manager, said the Combie project
would combine dredging with a centrifuge process to “spin” the mercury out of
water extracted from the lake. ‘”It’s a pretty novel approach,” said Charles
Alpers, a research chemist with the U.S. Geological Survey in Sacramento
and a consultant for the project.”‘
“The elemental mercury that would be removed, according to Ryan Jones, a
Knelson Concentrators representative, is relatively simple to recover and
inexpensive when using the company’s device. ‘“The important thing is to get
the elemental mercury out of the material so that it can’t convert to methyl
mercury,” ‘ Jones said.”
The press release goes on to say: “The consultant (Carrie Monohan) is also
on the staff of the Sierra Fund in Nevada City, which has been educating
Californians about the mountain range’s toxic mining past in recent years.”
At http:// www.conawayranch.com/content/mercury-rising
“Elizabeth “Izzy” Martin, CEO of the Sierra Fund, is quoted as saying ‘”The
state’s rules are forcing Sacramento into that mode. They’re a hundred miles
down from the problem and trying to filter it out. Sacramento would very much
like to come up here and clean up the mercury because they think it will
probably be cheaper to clean up four hundred pounds of mercury up here
than it will be to filter out two pounds of mercury down there.”‘
While I personally would not disagree with these statements, there appears to be
two different standards being applied here. The Water Board is objecting to normal
suction dredges because Rick Humphries measured a 2% loss of mercury from a
standard 4-inch dredge. Mr. Alpers and the Sierra Fund are objecting to normal
suction dredges because of the potential of not recovering colloidal mercury and
extremely fine particles of mercury that have evolved out of the elemental stage
and attach themselves to fine sediments which can remain suspended in water for
long periods of time.
Yet both Mr. Alpers and the Sierra Fund are directly involved as consultants
in this NID project which is only targeting 95% of the elemental mercury.
How can this be?
DFG can do the math on six grams of mercury per ton of sediment. There is no
doubt that this should be classed as a mercury hot spot, hazardous waste site.
That amount of mercury will exceed the average amount of mercury in California’s
rivers by thousands or millions of times. Yet the Sierra Fund , who is working so
hard to put suction dredgers out of business in sections of California waterways
where hazardous levels of mercury are not even present, is completely ignoring the
science which has been developed in the BLM project, the very science which they
are now attempting to use against suction dredgers.
All you need to do is look at Charles Alper’s data on the amount of mercury in the
water that we concentrated in Pro-Mack’s closed tank system, and you will know
that the NID project and Sierra Fund are stirring up the very same kind of
contaminated water and sediments at the bottom of the Combie Reservoir with the
use of a cutter head devise (powerful grinding machine) — which is a source of
drinking water for Californians.
Mr. Alpers and the Sierra Fund cannot have it both ways. If it beneficial for NID (at
a cost of $8+ million) to recover 95% of the elemental mercury from an established
waste site within a drinking water supply, while stirring up and spreading around
particles of mercury which are too small to recover, then it is also beneficial to have
suction dredgers recovering 98% of any mercury they happen to encounter while
assisting the State to locate new hot spots (at no cost to the State or federal
governments).
The CEQA process is designed to flush out real problems using the best available
science. There is supposed to be integrity in the process. If you are allowing
gravity separation equipment to process mercury from a mercury hot spot inside of
a reservoir, then you certainly cannot object to gravity concentration technology
being used by suction dredgers in areas which are not known to contain any
hazardous levels of mercury.
I hope this helps place Mr. Alper’s test results in a more balanced perspective, and
would be pleased to provide more information upon request.
Sincerely,
Dave McCracken
27 Davis Road, Happy Camp, California 96039
(530) 313-5378 Fax: (530) 493-2095 www.promackmining.com