f\-crri&cX.l td

Ililil 1137309-RS SDMS

Sampling and Analysis Plan

Mine Water and Ground Water Sampling

Nelson Tunnel NPL Site Creede Mining District

Mineral County, CO

June 2009

Prepared By:

Mike Wireman US EPA Region 8

Signature Page

Sampling and Analysis Plan

Mine Water and Ground water

Nelson Tunnel NPL Site Creede Mining District

Mineral County, CO

June 2009

Name Date

Mike Holmes - RPM

EPA Lab / ESAT

Table of Contents

List of Tables

List of Figures

List of Appendices

1.0 Introduction 2.0 Monitoring and Sampling and Analytical Parameters 3.0 Ground water sampling 4.0 Health and Safety 5.0 References

List of Tables

Table Title

1 Sampling and monitoring locations 2 Analytical parameters for sampling locations

List of Figures

Figure Title 1 Willow Creek Watershed Location Map

List of Appendices

Appendix Title

1 Sampling and chain of custody for stable water isotopes and trtium 2 Carbon 14 protocols 3 Ground water sampling record 4 Shipping metals samples 5 Sample Water Quality Equipment List 6 Water Quality Sampling Hit List 7 How to collect a blank/duplicate sample 8 Map of underground sampling locations -Commodore Tunnel

1.0 Introduction

This document presents the Sampling and Analysis Plan (SAP) for mine water, ground water and surface water sampling and monitoring to be conducted as part ofthe Nelson Tunnel NPL site in the Creede Mining District, Willow Creek watershed, Mineral County, Colorado.

Willow Creek, formed by the confluence of East and West Willow Creeks, is a tributary ofthe Rio Grande River near it's headwaters in the San Juan Mountains in Mineral County, Colorado (Figure 1). The Creede mining district, one ofthe largest silver mining districts in Colorado, occurs within the Willow Creek watershed. During the period from 1890 to 1950 development and operation of numerous underground silver, gold and base metal mines significantly impaired water quality in the 35 square mile Willow Creek watershed. Concentrations of zinc, cadmium and lead in East Willow, West Willow and the mainstem of Willow Creek exceed the water quality standards put in place by the State of Colorado. The State of Colorado has placed the segment of the Rio Grande River below the confluence with Willow Creek on the CWA 303(d) list which is a formal designation of impairment and requires that concrete actions be taken to restore the water quality to meet applicable standards.

A key mining facility within the Creede mining district is the Nelson / Wooster/ Humphries Tunnel (Nelson Tunnel), which was constructed to dewater the underground mines along the highly productive Amethyst vein and to provide a haulage route for ore from mines operating on the Amethyst vein complex. The Nelson/ Wooster/Humphries Tunnel (Nelson Tunnel) is approximately 11,000 feet long and was constructed between 1893 and 1902. The Nelson is the lowest tunnel constructed along the Amethyst vein system and fimctions as a drain for the underground workings that are connected via winzes and raises. The tunnel portal is located on the west side of West Willow Creek about one mile north ofthe City of Creede. The elevation ofthe tunnel portal is about 400 feet above the City. The tunnel portal currently discharges about 250 -300 gpm and is the single largest source of dissolved zinc and cadmium to Willow Creek. The pH ofthe portal discharge ranges from 4 to 5 and the zinc concentrations (based on nine samples) range from 5550 ug/1 to 89,800 ug/1 (WCRC, 2003). Dissolved cadmium concentrations for the same sampling dates range from 54 to 870 ug/1. Based on concentration and flow data from September 1999, May 2000 and May 2002 the Nelson tunnel contributes from 169 to 375 pounds of zinc per day to West Willow Creek. These zinc loads comprise from 34% to 74% ofthe total zinc load to West Willow Creek. Based on data from the same dates the Nelson Tunnel contributes from 45% to 63% ofthe total cadmium load to West Willow Creek.

The Nelson Tunnel was added to the NPL in 2008. In the fall of 2008, a hydrologic investigation was initiated to: (a) identify the sources of inflow into the mine workings that are drained by the Nelson Tunnel; (b) investigate the chemical fate and transport of water flowing through and out of the Nelson tunnel and (c) help evaluate potentially effective source control techniques which have the potential for tremendous long-term cost savings relative to the prevalent end-of-pipe treatment strategies (Williams, 2009 and Graves, 2008) Work Plans prepared by Williams (2009) and Graves (2008) provide the basis and rationale for collecting and evaluating stable /radioactive isotope data, water quality data, water level data and flow data. Sampling and monitoring activities will be conducted by a team that includes scientific and engineering staff from US EPA Region 8, Colorado DRMS, University of Colorado, CDPHE and members ofthe Willow Creek Reclamation Committee.

Figure 1 -Willow Creek watershed

2.0 Monitoring and Sampling Locations and Analytical Parameters

2.1 Monitoring and Sampling Locations

Monitoring and sampling locations include: 9 underground stations accessed by the Commodore tunnel; discharge from the Nelson Tunnel portal; West Willow Creek below the Nelson tunnel discharge; a domestic well located on the Emerald Ranch and a spring located along in the upper part of West Willow Creek watershed. These 13 stations are included in Table 1 along with the location coordinates. Water samples will be collected from all 13 locations. Water levels will be measured at 4 locations and flow will be measured at the Peak Drift borehole and at the temporary flume installed at the Nelson tunnel portal. Appendix 8 is a sketch map showing the underground sampling locations.

Table 1 - Sampling and monitoring locations

Sample Location

Bachelor Shaft Corkscrew Raise Nelson Portal Peak Drift Borehole Noname Winze (#1) -Lower Pool Noname Winze (#2)-UpperPool Discharge Del Monte Raise Berkshire Shaft Decline Park Regent West Willow below flume Emerald Ranch Well Upper West Willow Springs

XUTM

329830.6 329732.9 330304.3 329599.9 329586.6

329537.4

329493.1 329301.9 329231.0 328968.8 330316.9

328620.0 328613.2

YUTM

4193505.7 4193381.7 4193141.4 4193583.8 4194299.3

4194400.5

4194527.0 4195066.0 4195262.8 4195846.8 4193097.2

4197635.0 4197064.1

Water samples X X X X X

X

X X X X X

X X

Water level

X

X X X

Flow

X

X X

X

All coordinates are given in UTM zone 13, NAD83.

2.2 Water chemistry analytical parameters

Water samples for analysis of total recoverable metals, '̂ O and tritium will be collected at all 13 stations. Water samples for analysis of DOC, alkalinity and carbon 14 will be collected at 5 locations (Table 2). Field parameters (pH, DO, T, SC) will also be measured at each location using

a Hydrolab multiprobe. Total recoverable metals samples will be analyzed at the EPA lab in Golden using the ESAT contract. All isotope samples (̂ *0, tritium, C^) will be analyzed through INSTAAR.

Table 2 - Analytical parameters for sampling locations

Location

Bachelor Shaft Corkscrew Raise Nelson Portal Peak Drift Borehole Noname Winze (#1) - Lower Pool Noname Winze (ny Upper Pool Discharge Del Monte Raise Berkshire Shaft Decline Park Regent West Willow below flume Emerald Ranch Well Upper West Willow Sprmgs

Total recoverable metals X

X

X

X

X

X

X

X

X X

X

X

X

18^

X

X

X

X

X

X

X

X

X X

X

X

X

Tritium

X

X

X

X

X

X

X

X

X X

X

X

X

Field parameters

X

X

X

X

X

X

X

X

X X

X

X

X

DOC/Alkalinity

X

X

X

X

X

Die (for

X

X

X

X

X

DOC (for

X

X

X

X

X

2.3 Sample Collection Procedures

2.2.2.1 Collection of Water Samples for Metals Analysis

All samples for total recoverable metals analyses are collected in 250 ml HDPE sample containers that have been certified as clean by the laboratory (if possible). Sample containers and collection devices are rinsed three times with sample water before the sample is collected. The samples v^ll be preserved in the field with nitric acid -either immediately upon collection or when the sampling team retums form the underground.

Sample collection procedures for stable water isotopes (180 and D) are included in Appendix 1. Sample collection procedures for carbon 14 are included in Appendix 2.

Sample collection procedures for DOC and alkaluiity are per INSTAAR. No filtering or preservatives with the 250-mL bottles. INSTAAR staff v^ll filter a subset of water for DOC and store in special DOC bottles. INSTAAR uses special filters for the DOC.

3.0 Groundwater Monitoring

Four water samples will be collected from the domestic well at the Emerald Ranch (Table 2). This is an active domestic water well and the sample will be collected prior to any home treatment. Before collecting a groundwater sample, the well ID, current and previous weather conditions, field personnel and the sampling date and time should be recorded. Listed below are general preparatory steps followed by subsections on specific measurements and analyses.

Prior to sample collection, the depth to water in the well will be measured and recorded. The depth to water will be measured from a designated measuring point with an electronic water-level instrument. All water-level measurements are recorded to the nearest 0.01 foot. The volume of water in each monitoring well is calculated based on the depth to water, total depth, and diameter ofthe well.

Prior to sampling three to five well volumes will be purged from the well. Temperature, pH, and conductivity are monitored during the purging process and recorded.Groundwater samples are not collected until these parameters have stabilized (e.g. +/-10%), and a minimum of three well volumes have been removed from each well. Ifthe well yield from any well is low and the well is purged dry, the well is allowed to recover for up to 24 hours. Ifthe well does not recover within a 24-hour period, the three volume minimum requirement is waived and the well is sampled using

the second purged volume.

All groundwater sampling equipment (e.g., bailers, bailer cord, pump tubing) that comes in contact with a groundwater sample is either disposable or dedicated equipment which is only used at one sampling location to prevent cross-contamination. Possible parameters to be analyzed in the laboratory are listed in Table 2 and discussed below.

8.0 Health and Safety

All work described herein should be conducted consistent with applicable Occupational Safety and Health Administration (OSHA) requirements. If necessary, personnel involved in the work will be current with respect to the required OSHA training and refresher courses.

9.0 References

Graves, Jeff, 2008, Preliminary Scope of Work - Commodore Mme Investigations

Hermann, K.A., Wireman, M, editors, 2005, Aquatic Resources Assessment ofthe Willow Creek Watershed, USEPA

McCulley, Frick & Gihnan, Inc. (MFG), 1999a. Preliminary Characterization ofthe Willow Creek Watershed: Existing Conditions and Recommended Actions. April 1999.

McCulley, Frick «& Gilman, Inc. (MFG), 1999b. Site Specific Health and Safety Plan, Willow Creek Reclamation Project. July 1999.

Williams, Mark, 2009, Isotope Tracing Analysis Work pain for the Commodore and Nelson Mine Shafts near Creede, CO

Wireman, Mike 2008, Restoring a Watershed in a Colorado Mining District, Regional Geographic Initiatives, USEPA

Appendix 1

Sampling and chain of custody protocols for stable water isotopes and tritium

Wireman -October 2008

Stable Isotopes of Water

The stable isotopes of water are oxygen-18 (180) and hydrogen-2 (2H) or deuterium(D). These isotopes are used by hydrologists for a variety of applications because theyare naturally occurring, do not decay over time to other isotopes, and are considered conservative in reactions with catchment materials (Kendall and Caldwell, 1998).

Sample collection and analvsis. Isotope samples are collected in 30-mL borosilicatevials with airtight caps. Isotope analysis of water for 180 content are conducted at the Stable Isotope Laboratory located at the Institute of Arctic and Alpine Research, University of Colorado, Boulder. The d 180 values are obtained using a C02/H20 equilibration technique on a SIRA Series II mass spectrometer with a nominal precision of DO.P/o per mil following the protocol of Epstein and Mayeda [1953]. The 180 values are expressed in the conventional delta (d) notation as the per mil (0/00) difference relative to the intemational Vienna-Standard Mean Ocean Water (VSMOW) standard: d (0/00) D(Rx /Rs 1 )jclOOO where R denotes the ratio of heavy to light isotope in a sample Rx and the standard Rs .The 1 s precision is n0.05 0/00 and accuracy of analysis based on replicate samples is n0.09 0/00.

Tritium (3H)

Tritium is the only conservative tracer that can be used to determine the age of water older than one year. Tritium is a radioisotope of hydrogen with a mass of three and a half-life of 12.3 years. Tritium is produced both by cosmic-ray spallation and by atmospheric nuclear weapons testing. The steady-state level of tritium on the earth from natural processes is about 3.5 kilograms (Lai and Peters, 1966). However atmospheric testing of nuclear weapons in the 1950s and 1960s produced several hundred kilograms of tritium (Michel, 1976). About 80 kilograms of this isotope are still present on the earth's surface at this time. As a result, the tritium input fimction is a large spike, with highest concentrations in the early 1960s. Water deposited on the earth's surface prior to nuclear weapons testing has low tritium concentrations and most of that tritium will have decayed m the intervening years. Thus, if no tritium is present in a water sample, that water can be presumed to be greater than 50 years old. If detectable tritiimi is present, it indicates that some fraction ofthe water has been derived from precipitation since the early 1950s. Present day tritium concentrations in precipitation are about 12-15 Tritium Units (TU). Using the historical tritium record, it is possible to use tritium concentrations to put some limits on the ages of water sampled. Tritium's useftil timescale is on a decadal level with a maximum range of about 50 years.

Sample collection and analvsis. 1-L samples are collected in high-density polyethylene bottles. The bottles are sealed and then analyzed for tritium using liquid scintillation counting by Dr. Robert Michel at the US Geological Survey facility in Menlo Park, CA.Distilled sample water is reduced electrolytically in Ostlund style electrolysis cells from an initial volume of 200 mL to about 10 mL in a cooling bath. The tritium is retained preferentially to hydrogen in this system, resulting in an increase ofthe tritium concentration ofa factor of 16. The remaining water is mixed with a scintillation cocktail and counted in Packard scintillation counters ofthe CA 2000 series. Our detection limit at the one sigma level is about 0.3 TU with an uncertamty of about 3 % ofthe sample concentration.

Sample Handling

Chain-of-custody. All samples are subject to normal EPA guidelines on chain-ofcustody. EPA chain-of-custody tags are placed on each sample by EPA field personnel.

Perservation methods. All water samples are refrigerated at 5°C prior to sample analysis. No additional preservation is needed.

Maximum holding time. Samples are shipped to analytical labs within one-week of collection. Sample analysis for all samples is generally initiated within four weeks of being received by the analytical laboratory. Stable water isotopes and tritium samples have a maximiun storage time of several years when refiigerated.

Appendix 2

Carbon 14 protocols Dr. Mark Williams University of Colorado June 2009

C14 DOC

2-3L (i.e. > 1 mg C)per sample. Stabilize the sample by freezing soon after collection.

1 am not sure whether you will want to take steps to exclude POM by filtration (that's effectively a science question). Send to Scott Lehman's lab at INSTAAR for analysis.

C14 PIC

Our preferred DIC sample collection vessel is a 500 ml borosilicate glass bottle with a high-quality ground-glass stopper.The stopper is lubricated prior to collection with Apiezon grease to prevent exchange with the atmosphere.

In order to handle a water sample, we must know the DIC concentration. We need to know whether there will be too much C02 evolved for our vacuimi system to accommodate. The water stripping lines are automated and T\m unattended ovemight. They were designed to accommodate a range of concentrations typically found in a liter of seawater (approximately 2 mmol/kg). One ofthe highest concentrations we've handled (from groundwater) was about 14 mmol/kg and that required some creativity (one liter of water weighs 1 kg).

DO NOT FREEZE. Send to Woods Hole Oceanographic Institute (WHOI) for analysis.

jJMETHODS (describe):

Cleaning Equipmeni:

Purging:

Disposal of Discharged Water:

JlNSTRUMENTS (indicate make, model, i.d.):

Water Level:

pH Meter: •

Conducjtivity Meter:

Other.

Thermometer:

Field Calibration:

Field Calibration:

Field Calibration:

Date / Purg« Char seleriitics

Cumul. Vol. (9a<)

Purge Rate

SAMPLING MEASUREMENTS

Water Quatly Data

Temp. pH

SpKilic CofitiKtwin lunOMMm)

e Flak] Temp e2>c

Appcaranca

Color Turbidity & Sediment

Intake Depth (ft. BMP) Remarta

. . .

-SAMPLE INVENTORY

Wator Level (n. BMP) Before Sampling: Recovery %: Sampla Intake Depth (fl. BMP):

Bottles Collected

Time Volume Composition (glata, plaitic) Quantity

Fiflration(y/N) Praaarvation (type) Analysis Ram arks

Remark) (quality control sampis, other)

JChain-of-Cuslody Record No

BBREVIATIONS: UBMP • below measuring potnl I B G L - Bekiw ground level

Cumul. Vol. • Cumulative voluma removed

10 • Inside Diameter

C - Celsius

gal. - gallons

gpm. gallons par minute

in. - inches GW SM>OI« F9(m MACfCAO R«v«te4 WK

MFG, Inc.

Appendix 4

SHIPPING METALS SAMPLES

How to Ship

1. Make sure all bottles being shipped are tightly closed and are labeled correctly.

2. Put one frozen blue ice in the cooler with the samples and fill the empty space with packing paper or newspaper so the samples do not roll around.

3. DO NOT FORGET to enclose the CHAIN OF CUSTODY forms. Place these forms in a Ziploc storage bag in the cooler. Samples are not valid without a chain of custody form.

4. To close and secure the cooler, tape it shut with the strapping tape provided. This will inhibit tampering during shipment.

5. To mail, use the mailing labels provided in the back of this chapter ofthe sample plan. Use a photocopied label and tape it to the cooler.

6. We will ship through UPS. If a problem arises with UPS, please notify Barb Hom. When ever asked by anyone "What are you shipping?" reply "Water samples. " Do not say acid or chemicals. Trust us - you are not doing anything illegal.

Where to ship:

EPA Region 8 Lab Golden, CO

Appendix 5

SAMPLE WATER QUALITY EQUIPMENT LIST 1

Large Action Packer Tub Containing:

filters (and container)* 1, HN03 (and container) for acid j 2, filter holders ;; li themiometer | 2, permanent marker -j 2, syringes* 1, filter forceps* ;i 1, deionized water wash bottle ' 3, droppers/bulbs 1, organizer tray -? 2, 32 oz. deionized water bottle 1 , 16 oz. acid rinse bottle 2, pairs of goggles 3, pH buffers (4,7, 10) peristaltic pump with tubing in-line filters sample bottles | gloves ; paper towels garbage bags Ziploc bags waders/boots.

. * The number of supplies varies by river according to sampling plan. :•

Additional Supplies: il

1, pH meter carrying case, pH probe, ATC probe and carrying solutions 1, dissolved oxygen meter •..:••' 1, conductivity meter 1, cooler with ice 1, carboy for pure deionized water.

Appendix 6

WATER QUALITY SAMPLING HIT LIST

Sample Preparation 1. Check to see what stations you are sampling that day. Check to see if you need to collect a

duplicate and/or blank sample today.

2. Prepare data sheets for each station. Complete the top portions including crew members, date, sample number, and river.

3. Prepare, two-ounce bottles. Label the bottles properly and put in 12 drops of nitric acid. If this is a blank/duplicate day, prepare two more two-ounce bottles with the appropriate label. Prepare the filter holders.

4. If collecting an equipment blank sample today, do so now.

5. Gather the rest of equipment to take in the field, including sample bottles, field meters, a cooler with ice, deionized water, and so on.

In The Field

1 . Data recorder can fill in such information as time of sample, weather, and comments on the Field Data Sheet.

2. Flush the syringe twice with 60 mL of deionized water. Rinse the buckets (if applicable), 16 oz. bottle and syringe with river water.

3. Collect composite sample by wading, if possible. Otherwise, collect a "grab" sample from the bank if unable to do a composite.

Note: Safety is #1, you make the call!

4. First, collect your metals sample. Follow instructions on how to collect a metals sample (not filtered and/or filtered).

5. Collect any other samples (filtered and/or unfiltered), and place them in the iced cooler.

6. Someone can be taking field measurements of pH, conductivity, temperature and dissolved oxygen after the grab/composite sample has been taken from the stream. Dissolved oxygen should be taken at the bank in running water if possible. If you do analyze for dissolved oxygen from the bucket, do it first and right away. DO NOT stick your hands in the water.

7. If using a HACH kit for dissolved oxygen analysis, do the test at the site with the 60 ml BOD bottle. If analyzing dissolved oxygen by the Winkler titration method, collect sample using a 300 ml BOD bottle.

8. Fill the 16-ounce sample bottle by pouring the water from the bucket to the bottle, if you collected a composite. This will be for laboratory pH, alkalinity. Fill the 16-ounce bottle in running water offthe bank if you collect a grab. Be sure to rinse the bottle and take the sample in front of you. Remember pH and alkalinity samples must be analyzed within 14 days and kept refiigerated to be valid.

9. Neatly complete every blank line/box on the field data sheet.

At the Laboratory

1. Take the pH ofthe sample ifthe temperature is appropriate.

2. Perform the alkalinity and dissolved oxygen (if doing the Winkler method) titrations, following the instruction and completing the data sheets correctly.

3. Clean all equipment, such as Erienmeyer flasks, acid rinse and wash syringe, etc. Store all your equipment clean.

4. Place samples in a refrigerator.

Shipping

Gather up your metals samples to be shipped and get a blank Chain of Custody form. Complete the form- include ALL required information or your samples are invalid. Place the samples in the cooler, be sure the lids are on tight. Put the ice on top ofthe samples. Stuff the cooler with paper. Put your Chain of Custody in a Ziploc bag on the top. Tape the cooler shut. Put the mailing label on the cooler and send it via UPS.

Sample Holding Times

Metals 6 months if preserved with nitric acid. pH 24 hours if kept refrigerated. Test should be done at room temperature

(20-25 °C). Temperature None Alkalinity 14 days if kept refrigerated. Test should be done at room temperature if

possible. Hardness 24 hours if kept refrigerated. Test should be done at room temperature if

possible. Dissolved Oxygen Hach kit None Dissolved Oxygen Winkler If "fixed" immediately with first three chemicals, 4-8 hours refrigerated

in a dark place during this time

Appendix 7

i HOW TO COLLECT A BLANK/DUPLICATE SAMPLE

These two types of QA/QC samples test the procedure you follow to collect for metals. This data ; - validates your metals samples. jl

Blank Sample l l -

•; A blank sample is a sample of deionized water, treated as a normal sample. This blank is collected to test the chemicals and procedures used as well as the person conducting the test. Specifically, a blank sample tests "how" the procedure of putting river water into a normal sample is done. A blank sample can detect sources ofcontamination.

i 1 . Label an additional set of bottles as you normally would for one of your stations. I Add " 10" to the end of the station name. For example: the label for station, I "below Sth Street Bridge" would read "below Sth Street Bridge 10" for a blank I sample. A blank sample has the same sample number as the normal sample it is i associated with.

2. Prepare sample bottles as if you are taking a normal sample. • i . i l l - . . '

•I 3. Rinse the syringe (or pump tubing) with sample water (deionized water, in this • instance). Even through this seems redundant, it is now "river" water.

j 4. Now you are ready to collect the blank sample. Collect samples in the same j; manner as you collected the normal samples. Be sure to fiH all sample bottles. il i!" 5. Clean all equipment as you would after a normal sample collection.

v 6. Check the box on your field data sheet to indicate a blank sample was taken for this station.

Duplicate Sample i f A duplicate sample is two samples containing the same "slug" of water. This sample is I also a quality control sample. A duplicate checks the lab and the field crew. The lab I does not know it is identical to another sample. Results should be the same for both 'I samples ifno contamination occurred.

iU-

1. Label an additional set of bottles as your normally would for one of your stations. Add the number "20" to the end ofthe station name. For example: the label for station, "below Sth Street Bridge" would read "below Sth Street Bridge 20" for a duplicate sample. A duplicate sample has the same sample number as the normal sample it is associated with.

2. Prepare sample bottles in the same manner as you would for a normal sample.

3. Collect enough stream water in your composite sampling container to fill two sets of bottles.

4. Fill the bottles for the normal and duplicate simultaneously, by adding water to each bottle in 1/4 volume increments, alternating bottles, until both bottles are filled. Repeat this procedure for each set of bottles to be filled at that station.

5. Clean all equipment as you would after a normal sample collection.

6. Check the box on your field data sheet to indicate a duplicate was taken at this station.

Note: Bottle blanks will be performed by the laboratory, so the field team will not be collecting them. Preservation blanks will not be collected because documentation ofthe laboratory analysis of each preservative will be requested from each laboratory. The blanks described on page A- 1 2 include equipment blanks which will be collected for all equipment that is used at more than one sample site (filtering apparatus, collection buckets, etc.).

Appendix 8

Commodore Mine Complex and Sampling Locations

jPark Regent Shaft]

toeclinel

ierkshire Shaft|

pelMonte Raise

iNonafne-Discharge from upper pooH

Woname Winze-Lower Pool

ICorSscrew Raisef

Sampling Locations

• Commodores

' Nelson Tunnel

0 0.040.08 0.16 0.24 0.32 •Miles

C O L O I L A D O

RKXAMATION MINING — &—