20170622km NOPA Draft FactSheet-Santa Fe NEV0097013 · 2017-06-29 · liner overlying a fine-grained subbase compacted to a permeability of 1x10-5 cm/sec. The pad is divided into

FACT SHEET

(Pursuant to Nevada Administrative Code (NAC) 445A.401)

Permittee Name: Gateway Gold (USA) Corp.

Project Name: Santa Fe/Calvada Mine

Permit Number: NEV0087053 [incorporates NEV0091020] Review Type/Year/Revision: Renewal 2017, Revision 00

A. Location and General Description

Location: The facility is located in Mineral County, within Sections 4, 5, and 6,

Township 8 North (T8N), Range 34 East (R34E); Section 1, T8N, R35E; Section

36, T9N, R34E; and Sections 28, 29, 31, 32, and 33, T9N, R35E, Mount Diablo

Baseline and Meridian. Access to the facilities is east from Hawthorne on U.S.

Highway 95 about 24 miles to Luning and then north on Nevada State Highway

361 approximately 7.5 miles.

General Description: The facility consists of the Santa Fe Mine and the Calvada

Heap (formerly Water Pollution Control Permit (WPCP) NEV0091020). The

Calvada Heap is about 1 mile east of the Santa Fe site. The Calvada Heap was

incorporated into the Santa Fe/Calvada Mine WPCP in 2004. Both the Santa Fe

and Calvada mines were conventional open pit operations with ore processed by

heap leach cyanidation and precious metal recovery by carbon adsorption and

electrowinning. Both sites have completed active mining; this 2017 renewal

continues with permanent closure. All structures have been removed and

reclamation activities (regrading and revegetation) have been completed. Aside

from right of ways for roads, telephone lines and material sites, all lands are

administered by the U.S. Bureau of Land Management (BLM).

B. Synopsis

Both sites were initially owned and operated by Corona Gold, Inc. (Corona), a

wholly-owned subsidiary of Homestake Mining Company. The Santa Fe Mine was

the first of the two sites to commence mining activities. It was initially permitted

by the Nevada Division of Environmental Protection (Division) in 1988. Heap

Leach Pad 2 was approved as a minor modification to the Permit in 1989. Heap

Leach Pad 3 and two process ponds were approved as a major modification in 1991.

Mining and crushing ceased in 1992. In its final operating configuration, the Santa

Fe Mine site consisted of one open pit, two waste rock dumps, three heap leach

pads, five process ponds, one run-of-mine stockpile, a crusher site, a plant site, and

haul and access roads.

The Calvada Heap was permitted (as WPCP NEV0091020) in 1991 and begin

operating in 1992. Mining and crushing ceased in June 1993. In its final operating

Gateway Gold (USA) Corp.

Santa Fe/Calvada Mine

NEV0087053 (Renewal 2017, Fact Sheet Revision 00)

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NOPA_Draft_FactSheet-Santa_Fe_NEV0097013.docx

configuration, this site consisted of three open pits, two side-hill cuts, five waste

rock dumps, one heap leach pad, three process ponds, haul and access roads.

Homestake Mining Company became a wholly-owned subsidiary of Barrick

Bullfrog Inc. in 2002. Because the two sites shared many components (e.g. process

water system, power lines, roads) the Division decided in 2002 to incorporate the

Calvada Heap WPCP into the Santa Fe Mine WPCP. Homestake Mining Company

optioned the property to Gateway Gold (USA) Corp., a wholly-owned subsidiary

of Gateway Gold Corporation in May 2008. Victoria Gold Corporation acquired

Gateway Gold Corporation, including Gateway Gold (USA) Corp. and the option

on the combined Santa Fe Mine in December 2008. Victoria Gold Corporation

completed all requirements of the option agreement with Homestake Mining

Company in 2012 to earn a 60% interest in the combined Santa Fe Mine and

purchased the remaining 40% interest in 2013. Gateway Gold (USA) Corp. is a

wholly-owned subsidiary of Gateway Gold Corporation which is in turn a wholly-

owned subsidiary of Victoria Gold Corporation

Geology:

The Santa Fe Mine site is located within the Gabbs Valley Range, a northwest-

trending range typical of basin and range fault block mountain ranges. The oldest

rocks in the region are limestones of the Triassic Luning Formation (blue-gray,

medium-bedded to massive limestone, micrite, and siltstone) that have been

intruded by a Mesozoic granitic complex (primarily quartz monzonite). These

rocks are overlain by, or in fault contact with, Tertiary volcanics. Locally, the sites

are underlain by shallow quaternary alluvium (up to 10 feet thick) overlying high-

strength Tertiary volcanics consisting of dacite and rhyolite tuff to depths greater

than 700 feet. The gold-silver deposits occurred as fracture-controlled and

disseminated bodies in a 50 to 1,000-foot wide breccia in the limestone at its fault

contact with the volcanics.

Open Pits:

The Santa Fe site consists of only one open pit (Santa Fe Pit). The ore from this pit

consisted primarily of brecciated and hydrothermally altered limestone, oxidized

volcanics or jasperoid, and smaller amounts of unoxidized Tertiary volcanic rocks.

Ore from the Calvada site was mined from three pit areas (Slab, East Calvada, and

York) and two side-hill cuts (East and West York). The Calvada ore consisted of

approximately 60 percent (%) jasperoid, 40% brecciated limestone and trace

quantities of skarn. No pits were backfilled.

The pit wall lithologies correspond to the waste rock types. There are exposed

sulfides in the Santa Fe and East Calvada pits. None of the four pits, nor the two

side-hill cuts, intersect groundwater; the dewatering of any pit was never required.




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Inspection of project pits has been conducted for twenty years since the completion

of mining with no observations of standing or pooled water.

The Permit requires monitoring of the remaining pits and shall consist of

designating pit surface as dry, damp, or wet (visible flow or ponding). If any

ponded water is present, the Permittee must collect a representative sample and

analyze for Division Profile III constituents. The operator will investigate the

source(s) of ponded water. The pits will also be inspected for stability, safety, and

access restrictions.

Waste Rock Dumps:

Two waste rock dumps were developed at the Santa Fe site - the East and West

Dumps. The total amount of waste rock deposited in these two dumps is

approximately 23.2 million tons. Of the total quantity of waste rock, barren Luning

limestone comprises 40%; oxidized Tertiary volcanics comprise 40%, and

unoxidized Tertiary volcanics 20%.

Waste rock from the Calvada pits was deposited on five waste rock dumps - the

East and West Slab; East Calvada; and East and West York. The total quantity of

waste rock mined was about 4.1 million tons. While the vast majority of material

placed in four of the dumps is oxidized, the majority of the material placed in the

East Calvada Dump is unoxidized volcanics and granite.

The acid generating potential/acid neutralizing potential (AGP/ANP) results of the

three waste rock lithologies (Luning limestone, oxidized Tertiary volcanics -

jasperoid, and unoxidized Tertiary volcanics) indicate that the oxidized volcanics

and the barren limestone are strongly acid neutralizing. The unoxidized volcanics

are not so strongly neutralizing, as would be expected; however, they still show a

limited acid neutralizing effect. Therefore, the Division does not anticipate acid

generation at any of the dumps on either site. The waste rock dumps have been and

will continue to be observed for physical stability and evidence of seeps since

mining ceased and no problems have been observed to date.

Low Grade Ore Stockpile:

A run-of-mine ore stockpile exists at the Santa Fe site. There is not a stockpile at

the Calvada site. The run-of-mine stockpile consists of 63,000 tons of ore, with

some sulfides, from the Santa Fe Pit. The stockpile has been closed and reclaimed.

A 6-foot thick limestone bed was placed under the ore. A compacted clay cap was

placed over the top of the regraded ore pile.

The Permittee is required to inspect the waste rock dumps and ore stockpile semi-

annually for mass and physical stability, and designate surfaces as dry, damp, or

wet (visible flow or ponding). Should a discharge be present from any portion of




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any waste rock dump or stockpile, the Permittee shall collect a water quality sample

for analysis, take photos, and document the event.

Heap Leach Pads:

There are a total of four leach pads within the Santa Fe/Calvada Mine site. Pads 1,

2, and 3 are located at the Santa Fe site while Pad 4 is located at the Calvada site.

Pad 1 (e.g., South Leach Pad) was constructed in 1988 as a single-lined pad with

an 80-mil high-density polyethylene (HDPE) liner overlying a fine-grained subbase

compacted to a permeability of 3.0 x 10-6 centimeters per second (cm/sec). The

pad is divided into eight cells. Pad 1 is loaded with 7.3 million tons of ore, crushed

to minus 1½ inches and amended with lime (6 pounds per ton of ore (lbs./ton)).

Ore was loaded from July 1988 to June 1991. Cyanide addition to recirculated

solutions ceased in December 1994. The heap is 100 feet high and covers 45 acres.

Pad 2 (e.g., West Pad) was constructed in 1989 and 1990 with an 80-mil HDPE

liner overlying a fine-grained subbase compacted to a permeability of 1x10-5

cm/sec. The pad is divided into seven cells. The pad was loaded with about 3.8

million tons of run-of-mine agglomerated ore from October 1989 to June 1992.

Leaching commenced in 1989 and ceased in the summer of 1995. The heap is 80

feet high and covers about 39 acres.

Pad 3 (e.g., North Pad) is a single-lined heap leach pad with an 80-mil HDPE liner

overlying a soil subbase compacted to a permeability of 1x10-5 cm/sec. It was

constructed in 1991. There are four cells. It was initially loaded with

approximately 2.3 million tons of ore (all from the Santa Fe Pit) crushed to minus

1½ inches and amended with lime (4-6 lbs./ton). The remainder of the pad was

loaded with 500,000 tons of run-of-mine ore from the Calvada project. In its final

reclaimed configuration, the heap is about 95 feet high and covers about 30 acres.

Pad 4, the only Calvada pad, was constructed in 1992 with an 80-mil HDPE liner

overlying a 12-inch thick compacted clay subbase with a permeability of not more

than 1x10-6 cm/sec. The pad is subdivided into four 200-foot wide cells, similar to

the Santa Fe pads. The heap was initially stacked with ore from the Slab, East

Calvada, and lastly the York Pit, crushed to minus 1½ inches and lime-treated (4 to

6 lbs./ton) prior to deposition. The final stacked ore mass is about 3.8 million tons

occupying 30 acres with a maximum height of 110 feet.

All leach pad leak detection systems consisted of 4-inch wide wick drains on

maximum 50-foot centers, parallel to the interior berm cell alignments. The wick

drains were in direct contact with the bottom liner and located below the 6-inch

diameter pad drain pipe in each cell. The wick drains were interconnected to a riser

well at the toe berm crest for leak detection monitoring. A slot in the riser pipe

allowed leakage to overflow into the pad collection ditch. The collection ditch also




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contained a leak detection riser pipe. All leak detection ports were buried and

abandoned in-placed during closure activities.

Following rinsing and neutralization, all Santa Fe and Calvada heap leach pads

were regraded to final contours (3Horizontal:1Vertical), covering the collection

ditches and exposed liner material at the heap perimeters. All spent ore remains on

lined containment. The pads were then covered with 8 inches of growth medium

and revegetated.

Draindown management of the three decommissioned heap leach pads consisted of

combining flow from Pads 2 and 3 into a common pipe which flows into the north

end of Pad 1. The combined flow from the three heaps is monitored at the sump

located at the south end of Pad 1 from where it flows to the E-Cell. During

regrading of the pad, a 24-inch diameter vertical riser, leach pad observation port

(LPOP), was installed in the collection channel at the toe of each pad to monitor

draindown flow. The LPOP’s are monitored for a flow/no flow condition.

The vast majority of ore (>94%) on all four pads is oxidized Tertiary volcanics and

barren Luning limestone. As such, the Division did not anticipate future acid

generation and more than twenty years of monitoring has validated this conclusion.

Table 1 provides a summary of the lithologies and approximate quantities of ore

placed on the four Heap Leach Pads.

Table 1 – Heap Leach Pad Ore Lithologies and Quantities.

Lithologies and Quantities of Ore Placed on the Santa Fe and Calvada Heap

Leach Pads

(quantities in millions of tons)

Lithology Leach Pad

1

(South

Pad)

Leach Pad

2

(West Pad)

Leach Pad

3

(North

Pad)

Leach Pad

4

(Calvada

pad)

Oxidized Tertiary

Volcanics

(Jasperoid/Breccia) 2.9 1.5 1.3 2.8

Barren Luning Limestone 4.3 2.2 1.4 0.9

Unoxidized Tertiary

Volcanics 0.1 0.05 0.01 0.1

Total 7.3 3.8 2.8 3.8

Source: Santa Fe Mine Closure Plan, Westec, 1993




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The draindown solution pH on the three Santa Fe heap leach pads are similar and

average between 7.0 and 8.1 standard units (SU) since early 1998. Sulfate is

elevated, averaging approximately 2,000 milligrams per liter (mg/L) over the same

time period. Nitrate+nitrite (as N) concentrations are also elevated, averaging

approximately 350 mg/L. Weak acid dissociable (WAD) cyanide concentrations

average approximately 0.2 mg/L.

The Santa Fe and Calvada heap leach pad draindown chemistries are similar.

The Permittee will monitor leach pad observation ports (LPOP) for flow/no flow

conditions and measure and record heap draindown flows and provide a Division

Profile I solution analysis collected at each respective evaporation Cell (E-Cell)

distribution box .

Process Ponds:

Five ponds were constructed at the Santa Fe site. Ponds 1, 2, and 3 are located

downgradient of Pad 1. Ponds 4 and 5 were located near Pad 3. Ponds 1, 2, and 4

were utilized as process ponds. Ponds 3 and 5 served as overflow ponds. All five

ponds were double-lined and equipped with leak detection systems. The Division

is not aware of any leakage reporting to the pond sumps. The primary liners of

Ponds 1 through 3 were 40-mil HDPE and the secondary liners are compacted clay.

There is no quality assurance/quality control documentation available to confirm

that the compacted clay subbase met the requirements of NAC445A.438. The

primary liners of Ponds 4 and 5 were 60-mil HDPE and secondary liners were 40-

mil HDPE. Ponds 1 through 3 had capacities of 2.5 million gallons each. Ponds 4

and 5 had capacities of 775,000 gallons each.

Ponds 4 and 5 were subsequently backfilled with a minimum of 4 feet of native soil

over the excised and folded pond liners. Final regrading and

reclamation/revegetation was completed in 2001. Ponds 1, 2, and 3 had remained

as open ponds until December 2016. Santa Fe Ponds 1 and 3 were closed as

described below (see Pond Regrading). Santa Fe Pond 2 was modified as described

below, and currently receives and evaporates all residual heap draindown from the

three Santa Fe heaps.

Two process ponds (Calvada Pond 6 and Calvada Pond 7) and one overflow pond

(Calvada Pond 8) were constructed at the Calvada site. All three ponds are double-

lined and equipped with leak detection systems. The primary liners were 60-mil

HDPE and the secondary liners are 40-mil HDPE. Calvada Ponds 6 and 7 had a

1.25 million gallon capacity while the Calvada Pond 8 had a 2.1 million gallon

capacity. The sludge from Calvada Ponds 6 and 7 was moved into the Calvada

Pond 8 but ultimately buried in Santa Fe Pad 2.




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A passive treatment system (Biopass) was installed into the Calvada Pond 7 and

has since been closed in-place in December 2016. In 1996, the Calvada Pond 6 was

closed in place by puncturing the liner bottom with dozer rippers, and backfilling

the pond with structural fill in 8- to 12-inch loose lifts. All structural fill lifts were

compacted to a minimum of 95 percent of standard Proctor American Society for

Testing and Materials (ASTM) D698 maximum dry density. Calvada Pond 8 was

converted into a backfilled E-Cell in December 2016 and is used to collect and

evaporate heap draindown solution.

Heap Leach Pad Residual Draindown Management:

Since closure began in 1992, residual heap draindown from all three Santa Fe pads

is interconnected and gravity feeds into the Santa Fe E-Cell (formerly Santa Fe

Pond 2) where it evaporates. The combined draindown flows, as of March 2017,

is approximately 0.25 gpm. E-Cell leak detection system has remained dry to date.

Draindown from Pads 2 and 3 was routed to Pad 1 during closure activities prior to

2006 and all drain down from the three pads report to a single collection pipe at the

southwest corner of Pad 1. This solution flows to the distribution box at the Santa

Fe E-Cell.

In 1996, the Permittee constructed a Biopass system in the former barren pond

(Pond 7) at the Calvada site. This Biopass system was constructed as an alternative

to rinsing the heap. The system consisted of an anaerobic biochemical passive

treatment cell that discharged into the Calvada E-Cell (formerly Calvada Pond 8)

to evaporate. The draindown flow, as of March 2017, is approximately 0.10 gpm.

Both the Biopass and E-Cell leak detection systems have been dry to date.

The Permittee updated the Final Plan for Permanent Closure (FPPC) in August

2015. The updated FPPC finalized the design for the permanent closure of the site.

This final long-term closure approach will continue the current zero-discharge of

process solution. The updated FPPC was approved by the Division in March 2016,

and, beginning in August 2016, the Permittee, through SRK Consulting, began

closing the process ponds and other components per the approved FPPC. Closure

activities were completed in December 2016 – the final as-built report was

submitted on 18 January 2017 and approved by the Division on 17 March 2017.

Calvada Biopass Cell Permanent Closure:

The Biopass Cell is a fully encapsulated system, consisting of a drain layer

surrounded by a HDPE geomembrane and covered by growth media and

vegetation. The soil cover protects the liner from UV radiation and extreme

temperature variations thereby extending the liner life greatly. The soil cover and

geomembrane prevent meteoric water from entering the matrix. The geomembrane

liner also inhibits oxygen infusion into the matrix. Neither the leak detection port,




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nor the downgradient monitoring well (MW-4) for the Calvada site indicate any

leakage problems.

The Biopass Cell was designed to remove cyanide and nitrate from the leach pad

draindown prior to reporting to Pond 8 for evaporation. The effectiveness of the

system recently showed a slight decline, and, per design, approached the end of its

design life. Additionally, the Biopass Cell was designed with an overflow that, in

the event of plugging or back-up of solution in the cell, would discharge to the

environment. As such, the system was bypassed as part of the long-term solution

management at the site. This is described in detail below.

Table 2 below provides a summary of the draindown chemistries before (influent)

and after (effluent) Biopass treatment began. This table provides solution

concentrations only for constituents considered of interest or were elevated.

Biopass Influent and Biopass Effluent average concentration range is based on a

simple average of all available analyses (maximum of 34 sampling events –

November 2006 through March 2017). The range reflects the lowest and highest

values from all sampling events.

Table 2 – Calvada Heap Leach Pad Biopass cell influent and effluent

chemistries for selected constituents from November 2006 through March

2017.

Constituent

Units

Nevada

Profile I

Reference

Value

Biopass

Influent

Average

Concentration

(Range)

Biopass

Effluent

Average

Concentration

(Range)

Alkalinity

(Total as CaCO3) mg/L ---

112

(56 – 330)

1,910

(1,700 – 2,600)

Antimony mg/L 0.006 0.611

(0.13 – 1.2)

0.058

(0.02 – 0.16)

Arsenic mg/L 0.010 0.854

(0.23 – 1.1)

1.57

(0.17 – 3.1)

Chloride mg/L 250 573

(520 – 630)

668

(550 – 720)

WAD Cyanide mg/L 0.2 0.159

(0.038 -0.450)

0.023

(0.001 – 0.018)

Iron mg/L 0.6 0.439

(0.2 – 0.9)

18

(1.2 – 47)




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Manganese mg/L 0.10 0.11

(0.04 – 0.35)

5.9

(3.5 – 7.3)

Mercury mg/L 0.002 0.0357

(0.0022 – 0.0820)

0.0004

(0.0002 – 0.0006)

Nitrate+nitrite (as N)

mg/L 10 283

(230 – 330)

5.0

(0.6 – 8.7)

pH mg/L 6.5 – 8.5 7.8

(7.6 – 8.0)

7.3

(7.0 – 7.6)

Selenium mg/L 0.050 0.461

(0.120 – 0.520)

0.056

(0.040 – 0.070)

Sulfate mg/L 500 2,435

(2,100 – 2,800)

1,530

(420 – 2,000)

Thallium mg/L 0.002 0.017

(0.004 – 0.026)

ND* 0.002

Total Dissolved

Solids mg/L 1,000

6,515

(5,600 – 7,100)

5,380

(4,100 – 6,200)

*ND = non-detect at listed minimum reporting limit.

Comparison of effluent to influent concentrations indicate that the Biopass Cell was adding an order of magnitude of alkalinity to the effluent. Additionally, arsenic, iron, and manganese were being desorbed from the Biopass Cell matrix materials, as the concentrations of arsenic, iron, and manganese were lower in the heap influent. All other constituents of interest were either attenuated (metals), oxidized (WAD cyanide), or reduced (nitrate + nitrite) to levels that meet the Profile I reference values.

The permanent closure of the Biopass system was completed in-situ following

conversion of Pond 8 to an E-Cell. Actions consisted of sealing the influent and

effluent pipes after rerouting residual heap leach pad solution flow to the E-Cell.

The influent pipe was sealed off with the installation of the new distribution box

associated with construction of the E-Cell. The effluent pipe remained open to

allow drainage into the E-Cell until flow ceased and then was sealed in April 2017.

As the Biopass system is fully encapsulated with HDPE geomembrane, the cell

matrix will be stable in the current condition in as much as impacts to waters of the

State are not anticipated upon closure of the facility.

Implementation of the FPPC included the following:

At the Santa Fe site, Pond 2 was converted to an E-Cell to manage the combined

drain down from Heap Leach Pads 1, 2, and 3. Sediment, piping, and debris from

Ponds 1 and 2 were removed from the top of the liner and placed in an internment




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cell on Pad 2. Sediments and debris from Pond 8 at Calvada were also placed in the

internment cell. Liner removed and recovered from the ponds was shingled over

the sediments in the internment cell before the cell was covered to limit infiltration

of meteoric water into the sediments. The internment cell was constructed strictly

to allow for the disposal of process-related materials so as to remain on lined

containment.

Once the sediments, debris, and liner were removed, the pipe to the existing Pond

2 leak detection sump was cut off as far as practical into the slope before backfilling

commenced. The existing leak detection sumps and manholes for the Santa Fe

ponds were backfilled with alluvium and the upper 5 feet of the concrete manhole

was removed before burying the remainder in place. Pond 2 was filled with

alluvium placed and compacted in lifts to approximately 8 feet below the pond

crest. Each lift was moisture conditioned as needed and compacted to 90 percent

of maximum dry density as determined by ASTM D1557. Compaction was

achieved with a vibratory smooth drum roller and by wheel rolling with loaded 40

ton articulated haul trucks.

The bottom and side surfaces of the backfilled Pond 2 were compacted for

installation of the new lining system. The new lining system consists of a 60-mil

HDPE secondary liner, a geonet and a textured 80-mil HDPE primary liner. A

drainrock-filled sump was constructed in the bottom of the northwest corner of the

pond between the liners to collect any leakage. An 8-inch diameter standard

dimension ratio (SDR) 17 HDPE pipe was installed in the leak detection sump to

serve as an access port for depth measurements and a pumping port if needed.

Once the liner installation was completed, the distribution box was installed in the

northeast corner of Pond 2 on a shelf built into the pond slope. The distribution box

is completely contained within and above the pond lining system. The bottom of

the distribution box has 12 inches (23.5 gallons) of dead storage to collect

sediments to prevent them from entering the perforated pipes and clogging them.

An 8-inch inch diameter SDR 17 HDPE pipe was installed on the north slope of the

E-Cell to serve as a piezometer to measure the depth of solution. A pressure

transducer with data logging capabilities was installed in the piezometer pipe to

record water depth in the E-Cell. After the distribution box and observation port

were positioned, alluvium was placed over the lining system in a single 2-foot lift.

The material was screened to remove rocks larger than 4 inches to prevent damage

to the liner during fill placement.

A 6-inch layer of protective rock cover consisting of screened alluvium blended

with 4- to 6-inch rock was placed over the alluvium. The design concept includes

enough rock in the blended material to discourage burrowing animals from digging

in the E-Cell but to contain enough fine-grained material to provide capillary action

and promote evaporation. The distribution pipes were installed in the E-Cell by

excavating 6-inch deep trenches in the protective cover, placing the 4-inch diameter




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perforated corrugated plastic tubing (CPT) and then covering with the material from

the excavation.

Once the distribution piping was in place, the pipeline from the leach pad was

connected to the distribution box. The tie-in consists of a 4-inch diameter SDR 17

HDPE pipe that connects to the existing pipe with an electrofusion coupler just

below the leach pad and extending to the inlet of the distribution box.

The total as-built “open air” volume of the E-Cell is 2,421,522 gallons and the

volume with 2 feet of freeboard is 1,507,155 gallons. This is slightly more than the

design volume and will hold the volume (624,285 gallons) resulting from the 500-

year/24-hour storm without overtopping leaving plenty of room for existing

inventory (maximum estimated at 168,216 gallons under average conditions),

average monthly flow, and additional storm events. The 500-year/24-hour event is

estimated to be 3.80 inches from the online NOAA Precipitation Frequency Data

Server, Atlas 14 Point Precipitation Frequency Estimates. The volume resulting

from the 500-year/24-hour event includes direct precipitation into the pond and 4%

infiltration through the cover. The methodology is consistent with the approved

FPPC.

At the Calvada site, Pond 8 was converted to an E-Cell to manage draindown from

Pad 4. Once the sediment and debris were removed, Pond 8 was filled with

alluvium to approximately 10 feet below the pond crest and placed and compacted

in lifts to 90 percent of maximum dry density as determined by ASTM D1557. The

FPPC called for leaving the existing lining system in place in Pond 8 to act as a

secondary liner; however, during initial backfilling the existing liner pulled out of

the anchor trench on the west and south sides of the pond. It may have been possible

to repair the liner by adding an extension and re-anchoring but it was decided

instead to install a new secondary liner (60-mil HDPE smooth) and geonet before

the primary liner was installed. A leak detection sump and port were also

constructed in the northwest corner of the E-Cell. The completion of a new

secondary liner, rather than repairing the existing liner expedited construction and

provided greater confidence in the secondary liner integrity under the authorized

quality control program.

The remaining Calvada E-Cell construction was completed in the same manner as

the Santa Fe E-Cell as described above. The distribution box for the Calvada E-Cell

is identical to the Santa Fe distribution box. Connection of the 4-inch diameter

HDPE pipe to the E-Cell distribution box to the leach pad draindown pipeline was

made just upstream of the existing concrete cisterns that feed the existing Biopass-

Cell. The cisterns were backfilled with alluvium and the inlet pipe to the Biopass-

Cell was sealed with an end cap. The outlet pipe from the Biopass-Cell was left in

place and the new liner was booted around the pipe as the Biopass-Cell continued

to drain after the inlet was sealed. The Biopass-Cell will continue to drain for

several months due to the fine nature of the substrate. Seepage from the Biopass-




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Cell ceased in early April 2017. The outlet pipe from the Biopass-Cell to the E-

Cell was plugged with grout and the downstream cistern between the Biopass-Cell

and the E-Cell was backfilled with alluvium in mid-April 2017.

The total as-built “open air” volume of the E-Cell is 1,408,651 gallons and the

volume with 2 feet of freeboard is 971,204 gallons. This is slightly more than the

design volume and will hold the volume (204,314 gallons) resulting from the 500-

year/24-hour storm without overtopping leaving plenty of room for existing

inventory (maximum estimated at 66,629 gallons under average conditions),

average monthly flow and additional storm events. The volume resulting from the

500-year/24-hour event includes direct precipitation into the pond and 4%

infiltration through the cover. The methodology is consistent with the approved

FPPC.

Backfill of Open Areas on Santa Fe and Calvada Leach Pads

At five locations, two locations on Pad 1 and one on each of the other leach pads,

after closure activities in the late 1990’s, a small section of each leach pad was left

uncovered at the toe where the collection pipes exit the pad to allow observation of

the flow from each pad. It was noted in the development of the FPPC that

stormwater ran off the leach pad cover and could have reported to the collection

system and ultimately to the process ponds. Thus, at each location, a 24-inch

diameter HDPE pipe was placed over the existing collection pipe to allow for future

observation. Each open area was then backfilled with alluvium to act as a cover

similar to the rest of the leach pad and to prevent stormwater runoff from directly

entering the collection system. This design was used at all five locations.

Pond Regrading

Ponds 1 and 3 at Santa Fe were regraded by breaching the west embankments of

each and placing compacted fill in the bottoms to prevent any impoundment of

stormwater. The elevations of the pond bottoms are higher than the existing

drainage to the west, therefore complete backfill of the ponds was not required. The

finished grade of the pond backfill is approximately 1.4 % from the northeast corner

to the southwest corner in both ponds. By not completely backfilling Pond 1 the

open space creates a large buffer to keep stormwater runoff emanating from the

covered leach pad from entering the E-Cell during a large event. Rip-rap was placed

along the toe of the common embankment between the E-Cell and former Pond 1

to prevent erosion.

Removal of Site Fencing

A total of 54,000 lineal feet of perimeter fencing consisting of 3- and 4-strand barb

wire was removed from both sites and recycled for reuse or disposed of.




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During closure activities, it was noted that that the three site power poles had been

cut down sometime between September 2013 and August 2016 (based on Google

Earth photos) by unknown persons apparently to facilitate removal of copper from

the transformers. As a result, approximately 90 gallons of mineral oil were released

to the nearby soils. Consultants sampled and analyzed the contaminated soil for

polychlorinated biphenyls (PCBs) and Total Petroleum Hydrocarbons – Extractable

(TPH-E). The analysis determined no PCBs were present. The soils were

subsequently excavated, resulting in the removal of approximately 45 tons of

mineral oil-impacted soils which were transported to Nevada Thermal Services for

thermal treatment. Confirmatory sampling indicated that TPH was below the 100

milligram/kilogram remediation limit. The final spill report was received on 19

December 2016 and the spill report was closed by the Division on 29 December

2016.

C. Receiving Water Characteristics

The elevation of the two sites is approximately 6,000 feet above mean sea level.

The nearest climatological data recording station to the mines is located in Mina,

approximately 18 miles southwest of the sites and about 1,000 feet lower in

elevation. On average, annual precipitation at Mina is about 5 inches evenly

distributed throughout the year except for summer. Precipitation at the site would,

therefore, be expected to be higher, approximately 6 to 8 inches annually. The

annual pan evaporation rate in the area of the mine site is approximately 55 inches.

The two sites are located in different hydrological basins. The Calvada site is

located in the Gabbs Hydrologic Basin while the Santa Fe site is located in the East

Soda Springs Hydrologic Basin.

There are no perennial surface water bodies or streams within a 5-mile radius of the

site. There are no known surface springs or seeps within the site boundary. The

nearest spring is the York Spring which is located about 1.5 miles to the south and

downgradient of the Calvada pad.

The production wells that supplied both sites are situated in the Soda Springs

Valley, 2 to 3 air miles west of the Santa Fe mine site. The wells encountered a

regional productive aquifer at depths of 800 to 1,395 feet below ground surface

(bgs).

As part of the overall closure process, a borehole was drilled near to and

downgradient of the Santa Fe process ponds. This borehole was drilled to a depth

of 400 feet bgs and did not encounter groundwater. The actual pit floor elevations

also confirm groundwater depths are great. The floor of the Santa Fe Pit is about

400 feet bgs. The floors of the Slab, East Calvada, and East York Pits are 200, 250,

and 230 feet bgs, respectively. None of the pits at the Santa Fe and Calvada sites

intersected groundwater.




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As part of the closure process at the Calvada site, a borehole was drilled

downgradient to a depth of 452 feet. This borehole was then converted into a

monitoring well (MW-4). Currently, the static water depth is 15 feet bgs. Analysis

of water samples taken from this monitoring well indicate that the groundwater is

of good quality and meets all Division Profile I reference values. This monitoring

well will continue to be monitored.

D. Procedures for Public Comment

The Notice of the Division’s intent to issue a Permit authorizing the facility to close,

subject to the conditions within the Permit, is being sent to the Mineral County

Independent News for publication. The Notice is being mailed to interested

persons on the Bureau of Mining Regulation and Reclamation mailing list. Anyone

wishing to comment on the proposed Permit can do so in writing within a period of

30 days following the date of public notice. The comment period can be extended

at the discretion of the Administrator. All written comments received during the

comment period will be retained and considered in the final determination.

A public hearing on the proposed determination can be requested by the applicant,

any affected State, any affected intrastate agency, or any interested agency, person

or group of persons. The request must be filed within the comment period and must

indicate the interest of the person filing the request and the reasons why a hearing

is warranted.

Any public hearing determined by the Administrator to be held must be conducted

in the geographical area of the proposed discharge or any other area the

Administrator determines to be appropriate. All public hearings must be conducted

in accordance with NAC 445A.403 through NAC 445A.406.

E. Proposed Determination

The Division has made the tentative determination to renew the Permit.

F. Proposed Limitations, Schedule of Compliance, Monitoring, Special

Conditions

See Section I of the Permit.

G. Rationale for Permit Requirements

This site is in permanent closure. The final closure of the site consisted of

converting remaining process ponds, relative to the Santa Fe and Calvada heap

leach pads, into back-filled E-Cells. Both the Santa Fe and Calvada sites have




Page 15 of 15



always operated as zero discharge facilities and, with the E-Cells, these conditions

will be maintained and continue into the long term.

The facility is located in an area where annual evaporation is greater than annual

precipitation. Therefore, it must operate under a standard of performance which

authorizes no discharge(s) except for those accumulations resulting from a storm

event beyond that required by design for containment.

The primary method for identification of escaping process solution will be placed

on required routine monitoring of leak detection systems and monitoring well MW-

4. Specific monitoring requirements can be found in Part I.D. of the Permit.

Facilities will be monitored and operated in accordance with the Permit conditions

and the operating plans.

H. Federal Migratory Bird Treaty Act

Under the Federal Migratory Bird Treaty Act, 16 U.S. Code 701-718, it is unlawful

to kill migratory birds without license or permit, and no permits are issued to take

migratory birds using toxic ponds. The Federal list of migratory birds (50 Code of

Federal Regulations 10, 15 April 1985) includes nearly every bird species found in

the State of Nevada. The U.S. Fish and Wildlife Service is authorized to enforce

the prevention of migratory bird mortalities at ponds and tailings impoundments.

Compliance with State permits may not be adequate to ensure protection of

migratory birds for compliance with provisions of Federal statutes to protect

wildlife.

Open waters attract migratory waterfowl and other avian species. High mortality

rates of birds have resulted from contact with toxic ponds at operations utilizing

toxic substances. The Service is aware of two approaches that are available to

prevent migratory bird mortality: 1) physical isolation of toxic water bodies through

barriers (e.g., by covering with netting), and 2) chemical detoxification. These

approaches may be facilitated by minimizing the extent of the toxic water. Methods

which attempt to make uncovered ponds unattractive to wildlife are not always

effective. Contact the U.S. Fish and Wildlife Service at 1340 Financial Boulevard,

Suite 234, Reno, Nevada 89502-7147, (775) 861-6300, for additional information.

Prepared by: Karl W. McCrea

Date: 22 June 2017

Revision 00: 2017 Permit Renewal

Documents

20170622km NOPA Draft FactSheet-Santa Fe NEV0097013 · 2017-06-29 · liner overlying a fine-grained subbase compacted to a permeability of 1x10-5 cm/sec. The pad is divided into