Document ID: EPA-HQ-OW-2008-0517-0365
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-12-28T05:00Z

MEMORANDUM

TO:	Tom Born, EPA – Engineering and Analysis Division	

FROM:	Christopher Krejci, ERG

DATE:	29 April 2009

SUBJECT:	Summary of TMDL Studies Relevant to the Ore Mining and Dressing
ELGs

This memorandum summarizes ERG’s analysis of Total Maximum Daily Load
(TMDL) documents that are relevant to the Ore Mining and Dressing
Effluent Limitations Guideline Standards (ELGs). This review was
completed under the EPA Office of Water Annual Review of existing ELGs,
as required by Clean Water Act Section 304(m). ERG is supporting EPA’s
annual review of existing ELGs. As part of the annual review, ERG has
been tasked with reviewing and summarizing information from TMDL
documents that may be used to evaluate the effectiveness of the existing
Ore Mining and Dressing ELGs.

To identify and collect TMDL studies for this analysis, ERG used EPA’s
search tools available from the Waters1 website. While these tools are
extremely useful for removing unwanted documents and focusing the
analysis that is being performed, they work off of an incomplete
collection of TMDL documents. At the time that ERG queried data from the
Waters website, EPA’s TMDL Document Search Tool contained 7,670 TMDL
documents; however, EPA has anticipated that more than 36,000 TMDLs will
be completed for water bodies that were identified as impaired as of
2001 (EPA, 2001). The analysis described in the following sections of
this memo applies only to those documents available through EPA’s
databases as of Spring 2009. Because some TMDL documents are not
available through EPA’s database, it was not feasible to do a
comprehensive review of every TMDL document ever written for this
analysis.

In reviewing TMDL documents related to the Ore Mining and Dressing ELGs,
ERG identified many documents that discussed surface water quality
impacts from past and current ore mining operations. However, ERG found
little information specifically describing the effects of current ore
mining operations on surface water quality in the TMDLs reviewed. While
this result does not prove that active ore mining operations are not
contributing significantly to the impairment of surface waters, it does
show that definitive evidence of such water quality impacts is not
available in the TMDL documents that are available through EPA’s TMDL
databases.

Information Extraction from EPA’s TMDL Database

ERG queried EPA’s TMDL document database using the Waters TMDL
Document Search tool, which performs text searches of all TMDL documents
in EPA’s database. ERG searched for all documents containing the terms
“mine” or “mining,” and organized the metadata for those TMDL
documents – along with electronic hyperlinks to their location on
EPA’s website – in the attached tracking spreadsheet (Summary of
TMDL Studies Relevant to Ore Mining.xls). ERG’s query returned 1,668
TMDL documents.

Some of the TMDL documents in EPA’s database that contain the search
terms “mine” or “mining” are irrelevant to the Ore Mining and
Dressing ELGs. For example, a TMDL document may discuss watershed
impacts from coal or gravel mining. To screen out these and other types
of irrelevant documents, ERG developed the system for identifying TMDL
documents relevant to the Ore Mining and Dressing ELGs discussed in the
following section. 

Screening-Level Review of TMDL Documents

To identify information from TMDL studies that could be helpful in
evaluating the Ore Mining and Dressing ELGs, ERG first obtained all
available TMDL documents that contained the search terms “mine” or
“mining ” using EPA’s online query tools (see Section 1). ERG than
performed a screening-level analysis to identify documents that
contained information relevant to the Ore Mining and Dressing ELGs. This
analysis consisted of the following steps:

ERG removed documents from the tracking spreadsheet that did not discuss
impaired waters located in the following states (states with major ore
mining activities): Alaska;

Arizona;

California;

Colorado;

Montana;

New Mexico;

Nevada;

South Dakota;

Utah; and

Washington.



Removing TMDL documents for all states other than those listed above
reduced the number of documents for further review from 1,668 to 158. 

ERG performed a text search using the terms “mine” and “mining”
to determine whether or not the mining operations discussed in the
document were ore mining operations. Documents that did not provide any
detail on the type of mining present in the watershed were removed from
the tracking spreadsheet, because the level of detail on mining
operations provided by these descriptions would not be sufficient for
the purposes of EPA’s annual review. Removing documents that did not
specifically describe ore mining operations reduced the number of
documents for further review from 158 to 42.

ERG reviewed the sections containing the search terms “mine” and
“mining” to determine whether the document identified abandoned or
closed mines. ERG recorded this information in the tracking spreadsheet,
but did not use it to screen documents for further review.

ERG reviewed the sections containing the search terms “mine” and
“mining” to determine whether the document identified large-scale
(non-recreational), active mines. Removing documents that did not
specifically describe large-scale, active mines reduced the number of
documents for further review from 42 to 9.

ERG performed a text search using the terms “waste rock” and
“tailing” to identify documents that discuss water quality impacts
from waste rock and tailings piles, and recorded this information in the
tracking spreadsheet, but did not use it to screen documents for further
review.

ERG verified that TMDLs listed mining activities as a source of
impairment. In cases where it was not clear that mining was a source of
impairment, ERG removed these from further analysis. Removing documents
that described ore mining activities but did not list them as a source
of impairment reduced the number of documents for further review from 9
to 7. 

TMDL Studies Identifying Active Ore Mining Sources

ERG identified 7 TMDL studies that described impacts from mining
operations that were active/recently active at the time the studies were
written. ERG reviewed in detail the relevant information in these
studies as part of the TMDL analysis.  Table 1 summarizes information
from these 7 TMDL studies. 

Table 1. TMDL Studies with Information on Active and Recently Closed
Ore Mines1

TMDL Study	Pollutants of Concern	Active and Recently Closed Mines2
Summary of Data Available	Additional Comments

Pinto Creek	Cu	Gibson Mine (closed);

BHP Pinto Creek Mine (active); and

Carlota Copper Project (active).	Appendix A (data and figures) not
included; some data is provided in the text of the report.

	None.

French Gulch	Cd, Cu, Zn	Zonia Mine (closed)	Document includes extensive
in-stream monitoring data for metals and load estimates for all stream
segments.	None.

Pena Blanca	Hg	St. Patrick Mine (closed)	Study provides concentration
data from sediment and fish tissue samples and some concentration data
from water column samples	The TMDL study identified other past mining
projects and current exploratory projects, but it does not provide
information on their relative potential mercury loads.

Red River (Rio Grande to Headwaters)	Al, turbidity, and sediment
Molycorp Questa Mine (active)	Document includes in-stream monitoring
data for aluminum, benthic macroinvertebrates, stream flow, turbidity,
and TSS; it does not provide data for any mine sites.	None.

Bryant Creek	As, Cu, Fe, Ni, temperature, turbidity, TSS	Leviathan Mine
(closed)	Document includes statistical summary of stream flow, arsenic,
iron, turbidity, and TSS measurements in creek. No data are provided for
mine sites.	Although mining impacts are referenced throughout the TMDL
document, the study describes only the Leviathan Mine. 

Lower Similkameen River	As	Similco Mine (active);

Dankoe Mine (active);

Corona Nickel Plate Mine (active); and

Cadorado Mine (active).

(All in Canada)	Document includes in-stream monitoring data for arsenic.
No data are provided for mine sites.	The TMDL study acknowledges that
active mining occurs in the U.S. portion of the Similkameen watershed,
but it does not specifically mention any mine sites in the U.S.

Trinity River	Sediment	Deiner Mine (closed); and

La Grange (closed).	Study estimates sediment loads from major sources.
None.

1Listed in order of probable relevance to the Ore Mining and Dressing
ELGs.                                                                   
                                                                        
 2Mine status in parenthesis. “Closed” means both inactive and
permanently closed.                                                     
                                                                        
                                                                        
                                        TSS: Total Suspended Solids

The following sections summarize information obtained from the 7 TMDL
studies summarized in Table 1.

Pinto Creek TMDL for Copper

The Pinto Creek watershed drains approximately 180 square miles in Gila
and Pinal Counties of Central Arizona. It flows 32 miles northward from
the Pinal Mountains, and discharges into a man-made reservoir known as
Lake Roosevelt. Pinto Creek was first listed as an impaired water body
in 1992 based on elevated dissolved copper concentrations related to
discharges from the Pinto Valley and Gibson Mines. The listing was for
the section of the creek from its headwaters to its confluence with
Spring Creek. The watershed contains natural copper deposits that have
been targeted by past and present mining activities. Both point and
nonpoint sources from these activities may be contributing to the
elevated copper concentrations found in the creek. Three major mining
projects may be currently affecting water quality in Pinto Creek (status
as of 2001 in parenthesis):

Gibson Mine – AZU000093 (recently closed);

BHP Pinto Valley Operations – AZ0020401 (active);

Carlota Copper Mine – AZU000094 and (proposed).

The following subsections briefly describe these mines and their effects
on Pinto Creek.

Gibson Mine (Closed)

The Gibson Mine is identified by the TMDL study of Pinto Creek as the
most significant individual source of impairment. The mine has operated
periodically since 1906, and was most recently worked in 1992.  The mine
is located on several acres of disturbed areas at the headwaters of
Pinto Creek, and includes the following facilities: 

Adits and mine shafts;

Waste rock dumps;

Leach pads;

Concrete precipitation launders;

A mill foundation; and

Lined pregnant and barren leach solution ponds.

Stormwater runoff from waste-rock and low-grade ore dumps, the leach
pad, and other unreclaimed mine facilities contribute copper to the
Pinto Creek watershed. A series of samples collected by the Arizona
Department of Environmental Quality (ADEQ) shows that dissolved copper
concentrations in the Gibson Mine tributary increase from 0.11 mg/L
above the mine workings to 16.6 mg/L below the mine workings. The acute
water quality criteria established by the state for Pinto Creek is
0.0387 mg/L.

In addition to copper transport due to normal stormwater runoff, heavy
rainfall events in 1990, 1992, 1993, and 1995 caused the pregnant leach
solution bond to either breach or overflow. These events resulted in
discharges if copper-laden water to a tributary of Pinto Creek. Although
these discharges led to a Consent Judgment between the state of Arizona
and mine operators that mandated stormwater run-on control and periodic
inspection of the leach pad liner and solution ponds, these steps were
not effective in halting periodic discharges of copper-laden water to
Pinto Creek.

The TMDL study concluded that the copper load from the Gibson Mine would
need to be reduced by greater than 99 percent to meet the Load
Allocation assigned to it during the TMDL study. 

BHP Pinto Valley Mine (Active)

As of 2001, the BHP Pinto Valley Mine was active; however, ore
extraction ceased in February of 1998. BHP announced soon thereafter
that all mining activities will be suspended. The facility maintains the
following outfalls:

Four process water outfalls (001, 002, 003, and 005) which are designed
to discharge only in response to flows associated with 100-Year, 24-Hour
storm events; and 

Eight stormwater outfalls which are covered by the Arizona NPDES
Multi-sector General Permit for stormwater discharges. 

At the time of the TMDL study, insufficient information was available to
characterize the expected copper loads associated with discharges from
these outfalls.

A combination of extreme storm events and design exceedances has
resulted in significant contributions of copper to Pinto Creek from
BHP’s Pinto Valley Mine. These incidents have resulted in releases of
copper bearing sediments and liquids by the following transport
pathways:

Partial tailings dam failures;

Pipeline breaks;

Seepage flows;

Conveyance blockages; and

Stormwater overflows.

Significant release events occurred in 

August 1989 (preceded by high precipitation event)

July 1990;

January 1991;

August to September 1991; 

January to February 1993 (preceded by high precipitation event); and 

October 1997 (partial tailings impoundment failure during covering with
waste rock).

Carlota Copper Mine (Active)

At the time of the TMDL study, the Carlota Copper Mine was a proposed
mining project still in the planning phase. The study used information
from the Final Environmental Impact Statement for the Carlota Copper
Mine as well as the NPDES Permit and Fact Sheet issued by EPA Region 9
to estimate the discharges expected from the new operations. The Carlota
Copper Mine has agreed to carry out remedial actions at the Gibson mine
site prior to initiating any new discharges from the Carlota Copper
Mine.

The Carlota Copper Mine will have the following facilities:

Open pits;

Solvent extraction and electrowinning plant;

Heap leach pad;

Leach solution ponds; 

Waste rock disposal areas; and 

Ancillary facilities.

Stormwater runoff from the waste rock dumps will be managed in seven
stormwater retention ponds which discharge through seven separate
outfalls. Six of the ponds are designed to discharge only in response to
10-year, 24-hour events, and one pond is designed to discharge only in
response to a 100-year, 24-hour event. In addition to these outfalls,
Carlota expects to discharge pumped water from a wellfield to another
outfall. Copper loads from this outfall are expected to be small (EPA,
2001).

French Gulch TMDL for Cadmium, Copper, and Zinc

The French Gulch is a tributary to the Hassayampa River located in
west-central Arizona. It flows eastward from the Weaver Mountains in
Yavapai County approximately ten miles to its confluence with the
Hassayampa River. The French Gulch was first listed as an impaired water
body in 1994. It is currently listed for exceedances of surface water
quality criteria for cadmium, copper, and zinc. The listing is for the
section of the creek from its headwaters to its confluence with
Hassayampa River. The major sources of pollutant loading for the
watershed include inactive and abandoned mine workings (only nonpoint
sources).

Zonia Mine (Closed)

Zonia Mine, which began operations in the 1870’s, is a copper mine
that has been exploited using both heap and in-situ leaching techniques.
Prior to 1973, copper ore was extracted using open-pit techniques and
processed on heap leaches. In 1973, the mine operators constructed two
in-situ basins for sulfuric acid leaching located at the headwaters of
Zonia Gulch. Due to declining copper prices and unsuccessful ore body
fragmentation, production ceased at Zonia Mine in 1975. 

Arimeco, Inc., the current responsible party, began pumping from
production wells in 2000 to eliminate the drainage from the site, which
had previously been identified to be causing exceedances of surface
water quality criteria down-gradient from the mine. Samples taken by
Tetra Tech in 2004 show that water pumped from multiple wells
down-gradient from the mine exhibits extremely high concentrations of
cadmium, copper, zinc, and sulfate. 

Placerita Gulch (Active)

Past and present mining activities occur along the Placerita Gulch;
however, current activities are mostly recreational in nature (dry
panning). As of 2005, there is one permit holder with a notice to
conduct placer mining in the Placerita Gulch. The Placerita Gulch
watershed contains many inactive mine adits which may discharge during
precipitation events; however no discharges from adits were observed
during the study.

Peña Blanca Lake TMDL for Mercury

Peña Blanca Lake is a man-made surface impoundment located only a few
miles from the Mexican border in Santa Cruz County of south-central
Arizona. The lake was first listed as an impaired water body in 1994 due
to elevated concentrations of mercury found in the tissue of fish
collected from the lake. The TMDL study for Peña Blanca identifies
runoff from a tailings pile associated with a past gold mining
operation, St. Patrick’s Mine, as the most significant source of
mercury contributing to the lake’s impairment. The study also
identifies atmospheric deposition and nonpoint sources from other ore
mining operations as possible contributors of mercury to the lake. 

ADEQ suspects that mercury loads from past gold mining operations may be
significant due to the use of mercury in the processing of gold. Prior
to the introduction of cyanide leaching in the early 1900s, mercury was
frequently used in precious metals processing to separate valuable
material from waste material.  At gold mines, mercury was commonly added
during the ball milling process. After milling the crushed ore would be
mixed with water and mercury would form an amalgam with gold, causing it
to settle out of solution. Residual mercury from this process may be
found in very high concentrations at mine sites, particularly in
tailings material.

The author’s of the TMDL study used the most recent information from
the U.S. Bureau of Mines Mineral Availability System/Mineral Industry
Location System (MILS), to identify recent mining activities in the
area. The system contained information for three exploratory projects
and four past producing mining projects in the area. The TMDL report
does not provide information on the relative potential mercury
contribution from these sources (ADEQ, 1999). 

Red River TMDL for Aluminum

The Red River originates in the Santa de Cristo Mountain Range of
north-central New Mexico. From there it flows eastward to the Texas
border, draining approximately 190 square miles of Northern New Mexico.
The stretch of the Red River flowing through New Mexico was first listed
as an impaired water body by the New Mexico Environment Department
(NMED) in 1999, due to elevated aluminum concentrations. The Red River
was listed for the section from its confluence with the Rio Grande to
its headwaters, including its tributaries. Inactive mines and mine
tailings are listed among the many sources of impairment. Numerous
inactive and abandoned mines are located in the Red River Watershed, as
well as one active mine – the Molycorp Questa Mine. 

Molycorp Questa Mine (Active)

The Molycorp Questa Mine is a molybdenum mine that operates along 10
miles of the Red River just west of the town of Questa. Mining began in
1919 and has included underground (historic), open pit, and block-caving
techniques. More than 100 million tons of tailings material generated by
open pit mining was disposed in two unlined tailings ponds on the site.
Numerous spills have originated from the 8-mile pipeline that transports
the tailings to the ponds in slurry form. During pit development,
approximately 320 million tons of waste rock were placed in Capulin
Canyon, Goathill Gulch, Sulpher Gulch, Spring Gulch, Blind Gulch, and
many unnamed drainages. Acidic leachate from these piles reaches the Red
River through seeps, springs, and groundwater recharge to the Red River.

The Molycorp Questa Mine has four permitted outfalls, only one of which
discharges continuously (NPDES Permit #NM0022306). This outfall
discharges seepage from the mine’s tailings dam. Due to the low
discharge limits and compliance monitoring associated with these
outfalls, the TMDL study concluded that nonpoint source areas (e.g.,
disturbed land) are likely the primary cause of aluminum impacts to the
Red River. The study refers to nonpoint sources that include alteration
scars associated with the Molycorp Questa Mine (NMED, 2006).  

Bryant Creek TMDL for Arsenic, Iron, Nickel, Turbidity and Total
Suspended Solids

Bryant Creek is a tributary of the East Fork Carson River, originating
in the Sierra Nevada Mountains of east-central California. It drains
approximately 35 square miles of land ranging from 9000 to 5100 feet
above mean sea level. Bryant Creek was first listed as impaired water
body in 1998, due to elevated concentrations of copper, iron and nickel.
The current listing also includes arsenic, temperature, total suspended
solids, and turbidity. The most significant, single source of impairment
referenced in the study is natural seepage from waste rock at the
Leviathan Mine, a historic mining site that is now in the remediation
phase. Although the TMDL study acknowledges ongoing mining activities in
the Bryant Creek Watershed, detail is provided only on the water quality
impacts from the Leviathan Mine site.

Leviathan Mine (Closed)

The Leviathan Mine is a copper mine located in between Markleeville,
California, and Holbrook Junction, Nevada, off California SR-89. Mining
operations have occurred intermittently since 1863 and have included
underground (historic) and open pit techniques. Complex sulfide
minerals, poor structural geology, and extensive groundwater
infiltration have made the economical recovery of copper resources from
the local ore body difficult.

Approximately 22 million tons of overburden and waste rock were spread
over 200 acres when the historic underground mine was converted into an
open pit mine beginning in the 1950s.  Some of this material was
disposed in the canyon bottoms of Leviathan and Aspen creek, causing the
diversion of stream flows from their natural courses.

In the 1980s, the Lahontan Regional Water Quality Control Board took
steps to begin remediating the site, obtaining $2.3 million from ARCO to
cover some of the remediation costs. The State of California
subsequently acquired the site to obtain additional grant money for
remediation.

Remediation measures have included the following:

Channelization of Leviathan Creek to prevent contact with mining wastes;

Re-grading and compaction of the mine pit to reduce acid mine drainage
(AMD); 

Construction of lined evaporation ponds to reduce AMD from underground
workings; and

Installation of a lime neutralization treatment unit for AMD evaporation
ponds.

Site remediation measures have not successfully ceased the impacts of
the Leviathan Mine on the Bryant Creek Watershed. The most significant
problem identified in the remediation phase has been the overflow of
storage ponds. EPA designated the Leviathan Mine as a Superfund site in
May of 2000.

Lower Similkameen River TMDL for Arsenic

The Similkameen River originates in the Cascade Mountains along the
international border between British Columbia, Canada, and Washington
State, USA. The river flows through southern British Columbia before
crossing the border into northeast Washington. The Similkameen River was
first listed as an impaired water body in 1998 due to elevated
temperature and concentrations of arsenic. Over 90 percent of the
river’s watershed is in British Columbia. 

Active mining operations continue at a number of locations in British
Columbia; the following is a list of the major mines (mine type in
parenthesis):

Similco Mine (copper);

Dankoe Mine (silver/gold placer);

Corona Nickel Plate Mine (gold); and

Candorado Mines Ltd. (gold).

The TMDL study acknowledges that active mining occurs in the U.S.
portion of the Similkameen watershed, but it does not specifically
mention any mine sites. The TMDL document does not contain any
information about impacts from mine sites on either side of the border.
In the public comment section of the TMDL document, the following report
is referenced: 

Screening Level Investigation of Water and Sediment Quality of Creeks in
Ten Eastern Washington Mining Districts, with Emphasis on Metals 

(Available online at   HYPERLINK
"http://www.ecy.wa.gov/pubs/0003004.pdf" 
http://www.ecy.wa.gov/pubs/0003004.pdf ; date accessed 13 April 2009).

This report contains extensive in-stream monitoring data for metals and
general chemistry data for some point source discharges from mining
operations.

Trinity River TMDL for Sediment

The Trinity River is located in northwestern California. It flows from
the southern Klamath Mountains to the Klamath River, draining
approximately 3,000 square miles. The Trinity River was first listed as
an impaired water body in 1992 due to elevated sedimentation. EPA has
identified ore mining as a major source of impairment, along with timber
harvesting, roads, and natural sources. In the TMDL study, EPA discusses
mining in the Trinity River, beginning with the Gold Rush in 1848.
According to the study, hard rock, placer, and hydraulic mining
techniques have all been used extensively in the area. During some
periods, hundreds of mines operated in the watershed at one a time. The
La Grange Mine near Junction City, one of the largest hydraulic mines in
the world, operated for a number of years in the watershed. At the time
of the TMDL study, insufficient information was available to estimate
surface erosion from disturbed mining areas in the watershed.

Although no active mines are mentioned in the TMDL study, it does refer
to a USFS channel survey published in 1991 observing “a high degree of
disturbance in the form of historic or active mine tailings” in the
Trinity River watershed.  The study refers repeatedly to mining impacts,
but does not generally discuss mines in particular. However, in
discussing water quality data, EPA identifies water samples from the
Diener Mine drainage which exhibited turbidity more than 10 orders of
magnitude higher than background levels (EPA, 2001).

References

EPA, 2001. The National Costs of Implementing TMDLs. Washington, D.C.

ADEQ, 1999. Total Maximum Daily Load And Implementation Plan For Mercury
Peña Blanca Lake, Arizona. 

NMED, 2006. Total Maximum Daily Load for the Red River Watershed: Rio
Grande River to Headwaters.

ADEQ, 2005. French Gulch TMDLs for Cadmium, Copper, and Zinc: Headwaters
to Hassayampa River.

EPA, 2001. Trinity River Total Maximum Daily Load for Sediment.

EPA, 2001. Total Maximum Daily Load for Copper in Pinto Creek, Arizona. 

EPA, 2003. Bryant Creek: Total Maximum Daily Loads – Arsenic, Iron,
Nickel, Turbidity, and Total Suspended Solids.

Washington State Department of Ecology, 2003. Colville River Watershed
Bacteria Total Maximum Daily Load. Olympia, Washington.

Washington State Department of Ecology, 2004. Issaquah Creek Basin Water
Cleanup Plan for Fecal Coliform Bacteria: Total Maximum Daily Load.
2003. Bellevue, Washington.

Washington State Department of Ecology, 2004. Lower Similkameen River
Arsenic Total Maximum Daily Load. Olympia, Washington.

Available online at   HYPERLINK
"http://iaspub.epa.gov/waters10/text_search.tmdl_search_form" 
http://iaspub.epa.gov/waters10/text_search.tmdl_search_form . Accessed
on January 22nd, 2009.

 Ore mining operations will commonly close and re-open periodically
according to the fluctuating prices of the metals they produce. Few
mines are continually operational over spans of time long enough to
identify them as sources of impairment while they are still active. In
light of these observations, ERG selected TMDL studies that included
discussion of recently closed mines. These studies may potentially
contain information about the effectiveness of the Ore Mining and
Dressing ELGs

Memorandum

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Memorandum

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