investigation of spot treatments for pockets of acidic mine...

Investigation of Spot Treatments for Pockets of Acidic Mine Water, Fire Road Mine Minto, NB

Atlantic Reclamation Conference NBCC MiramichiOctober 16th, 2018

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The STOZA Corp. Team• Members

• Troy Dobson, EIT

• Andrew Floyd

• Zach McDougall, Dual MIT

• Otillia McLaughlin

• Spencer Wastle

• Mentors

• Dr. B. Broster, P.Geo

• Dr. J. Day, P.Geo P.Eng

• Gilman Violette, P.Eng

• Steven Rossiter, Dual MIT

• Dr. K. Butler, P.Geo P.Eng

• Dr. N. Susak, P.Geo 2

UNB Geological Engineering Senior Design

Introduction

• Fire Road Mine opened in 1982

• ~50 000 tons of coal produced

• Coal extracted from seam ~0.5m thick

• Mine active for 4 years until pH levels declined to 3 and was subsequently shut down

• At end of operations, mine was ~120 ha and disturbed area totalled ~300 ha

• Currently being treated with a hydrated lime 3


Introduction• Geological Background

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Introduction

• Acid mine drainage

• Acidic water created by the reaction of sulphide minerals when exposed to air and water

• Naturally formed in common sulphide minerals

• The oxidation of pyrite is the most common producer of acid mine drainage due to its high sulphur content

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Problem Statement

• The purpose of this design report is to investigate possible in situ solutions for areas of high acidity, and perform a cost analysis of the possible solutions.

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• Conduct a site visit to collect

field data and evaluate site

conditions.

• Examine possible in situ

solutions to treat localized

areas of high acidity

• Quantify and incorporate

these solutions with the

current site treatment plan

• No surficial disturbance

• Must be within current solution parameters

• Not interfere with the hydrogeological dynamics

• Work within seasonal constraints on the mine site

• Complete work within the outline of the team schedule

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Requirements Constraints


Field Work • November 4th, 2017

• Electromagnetic geophysical survey using an EM31

• Remarked the geophysical survey lines for reproducibility

• Water level, temperature and conductivity measurements

• 4 water samples collected from standing water on site

• 2 soil samples from problematic areas (wells 3 & 17)

• 1 soil sample from non-problematic area (well 27)

• November 17th, 2017

• Slug testing 10 wells chosen based on pH data from GEMTEC reports

• Delineating standing water on site

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Field School Spring 2018

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• Follow up EM-31 and ERI surveys were completed in April 2018

• ERI – Electrical Resistivity Imaging an array of electrodes connected to a central power supply measures voltage drop across electrodes to create a pseudo cross-section.

• Data is subsequently inverted with software and user defined parameters to create a geologically reasonable cross-section

• Very different groundwater conditions with extensive standing water and high volume recharge of clean meteoric water

Geophysical Analysis• The geophysical survey was done using

a Geonics EM-31 Ground Conductivity Meter, a Juniper Systems Data Logger and a Garmin GPS.

• A total of 7 surveys lines were conducted over the anomalous area of high acidity.

• Standing water delineated with Garmin GPS

• Used for comparison of previous geophysical work

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Geophysical Analysis Suite

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• 2014: Peak of 42 mS/m

• 2017: Peak of 40 mS/m, similar anomaly size, smaller maximum

• Site continues to improve over time

STOZA Corp November 4th, 2017 survey area


Geophysical Analysis Suite

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• Standing water shows no correlation with areas of high apparent conductivity

• Peak near Well #17

• Soil samples taken from anomalously high apparent conductivity zones


Field School Spring 2018, EM-31

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• Results replicated in different environmental conditions across the site.

• Peak value around 40mS/m

• Maximum conductivity centered around well 17

Field School Spring 2018, ERI

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Bench Scale Experiment

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A bench scale testing program was conducted to develop a solution to treat the areas of anomalously high acidity

Choice of solutions based on:• Locally sourced• Economically viable• Previous success with

treating acid mine drainage (AMD)

The proposed treatments included• Biosolids - WWTP• Seafood compost - Envirem Organics Inc.• Hydrated lime sludge



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• Same volume of soil was used for each column

• Same volume of solution was used for each column

• The experiment ran for 3 weeks

• 140 mL of water weekly

• Water collected on a fixed schedule



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Bench Scale TestingThe following tests were performed throughout and at the end of the bench scale experiments:

• pH

• Water chemistry analysis

• Trace element and total dissolved solids analysis outsourced to Research and Productivity Council (RPC)

• Soil chemistry analysis

• Portable X-Ray Fluorescence (PXRF) 18


Bench Scale - Water Chemistry

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0

1

2

3

4

5

6

7

8

0 0.5 1 1.5 2 2.5 3 3.5

pH

Time (Weeks)

pH Analysis from Bench Scale Test

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 0.5 1 1.5 2 2.5 3 3.5TD

S (M

g/L)

Time (Weeks)

Total Dissolved Solids from Bench Scale Test



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Comparing Trace Elements of Problematic Soil to Treatments at Week 3

Element

Problematic Soil -Seafood Compost

Problematic Soil -Hydrated Lime

Problematic Soil -Biosolids

Removed(ppm)

Added(ppm)

Removed(ppm)

Added(ppm)

Removed(ppm)

Added(ppm)

Aluminium - 3.71 - 2.53 0.31 -Boron 0.15 - 0.25 - 0.21 -Cadmium 0.10 - - - - -Calcium 430.00 - 407.00 - - 31.00Copper 73.01 - 73.61 - - 4.50Iron 1653.80 - 1469.00 - 150.00 -Lead 3.70 - 3.73 - - 0.67Lithium - - - - 0.10 -Magnesium 32.30 - 28.50 - - 1.30Manganese 9.10 - 4.74 - 1.20 -Nickel 2.20 - 2.21 - 0.82 -Potassium 63.30 - 63.80 - 18.10 -Sodium - 81.00 38.80 - - -Strontium 0.52 - 0.49 - 0.15 -Zinc 190.93 - 189.07 - - 14.00

Note: Detection limit for analysis was in ppb. To be considered for added and removed columns, the ion's concentration must be greater than ±0.1 ppm to be significant.

• Water chemistry tested by RPC using Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

• Columns are a comparison of elements in the problematic soil sample minus the elements in each of the solutions



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• Absolute concentration of metal ions reported in each solution at Week 3

0 100 200 300 400 500 600 700 800 900 1000

Al

Fe

K

Ca

Pb

Mg

Mn

Zn

Concentrations (ppm)

Effluent Water Chemistry Comparison

Seafood Compost Hydrated Lime Sludge Control

Fe ≈ 1680 ppm

Problematic Soil


Bench Scale - Soil Chemistry

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0

10000

20000

30000

40000

50000

60000

70000

80000

Al Fe K S Si

Co

nce

ntr

atio

n (

pp

m)

Problematic Soil Pre and Post Leaching

Pre Leach Post Leach

• PXRF data from the problematic soil pre- and post-leaching• Post-leaching shows lower concentrations of elements as they have been

mobilized and carried out by the waterUNB Geological Engineering Senior Design

Bench Scale - Soil Chemistry

• PXRF data comparing the soil columns of the solutions to the problematic soil

• Post-leaching shows an improvement in soil chemistry as a higher concentration of elements remained in the soil with treatment

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0

10000

20000

30000

40000

50000

60000

70000

80000

Al Fe K S Si

Co

nce

ntr

atio

n (

pp

m)

Problematic Soil and Solutions Post Leach

Problematic Soil Pre Leach Problematic Soil Post Leach Hydrated Lime Sludge Post Leach

Biosolid Soil Post Leach Seafood Compost Soil Post Leach


Hydrogeology Models

• 3D Surface Topography

• Water table topography (unconstrained)

• Vector plots

• 1st Derivative water table plots

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3D Surface Topography Map

1:6400

250m 100m 200m 300m

Water table elevation set at 125m above CGVD2013 (Geodetic Sea level)


Water Table Topography

Contours marked at 1m elevation change.

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N

EUTM NAD 83 NB Stereographic


125m

Flow Direction

Water table slopes assuming homogeneous site conditions.Significant shallowing in troubled regions.

UTM NAD 83 NB Stereographic

27Em/m

N


1st Derivative Water Table

Visualizes the change of the water table slope. Colour variation showing greatest rate of change in slope.

UTM NAD 83 NB Stereographic

28E

N


Conclusions • The goal of the project was to find a viable

solution that is economically feasible and can be locally sourced.

• Seafood compost is the best practical spot treatment based on its results in the bench scale tests and the analysis of the data collected in the field.

• Slope of the water table is relatively flat at the two hotspots, allowing direct application of solution to soil.

• The application method assumes vertical infiltration for spot treatment through permeable soil.

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Cost Analysis

Costs Associated with Applying Seafood Compost Treatment to Problem Areas on Site

Apparent Conductivity

Cut-off for Area Calculation

(mS/m)

Area(m2)

Cost of Compost $10/ton

($)

Cost of Hauling

$21.08/ton($)

Cost of Equipment

($)

Total Cost($)

12 24800 $37,855 $79,798 $1,118 $118,770

20 9427 $14,390 $30,334 $732 $45,456

26 1796 $2,741 $5,778 $539 $9,057

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Solution Source Locations

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Fire Road Mine

Envirem Compost

Bio-solids


Environmental Considerations • In terms of the addition of seafood compost.

• Pros:

1. Aids vegetation growth

2. Create a stable organic soil horizon

3. Prevention of future soil erosion

4. Reduce the amount of water infiltrating in the ground

• Cons:

1. Slight odour

2. Increased presence of rodents, birds, and deer to the site

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Recommendations

• Conduct a hydrogeological investigation to assess the possible water escape along the hanging wall

• Assess the drainage ditch to ensure its efficiency to prevent possible groundwater stagnation in problem areas on site

• Further geochemistry and vertical permeability assessments to confirm the viability of the proposed seafood compost solution

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ReferencesMonenco Consultants Limited . (1991). Stabilization Plan for the Fire Road

Site . Fredericton, NB: Monenco Consultants Limited .

Monenco Consultants limited . (1991). Use of Chatham Coke Ash at the Fire

Road SIte . Fredericton, NB: Monenco Consultants Limited .

NB Coal Limited . (1996 ). Acid Mine Drainage Cover Options and Their

Considerations at the Fire Road Mine . Fredericton, NB : NB Coal Limited .

NB Coal Limited . (1997 ). Investigation of Metal Hydroxide Solubility from

SLudge in Acid Mine Drainage . Minto, NB: NB Coal Limited .

NB Coal Limited. (1996 ). Investigation on the Placement of Lime

Neutralization on Acid Generating Waste Rock . Minto, NB : NB Coal

Limited.

New Brunswick Power Coroporation Development Division . (1993 ).

Review Of Acid Mine Drainage at NB Coal Ltd.'s Fire Road Site .

Fredericton, NB : New Brunswick Power Coroporation Development

Division .

Phinney, K. (1987). Acid Mine Generation at NB Coal Ltd's Fire Road

Operation. Minto, NB.

Phinney, K. (1989). Reclamation Study Fire Road Minesite . Fredericton,

NB: K.D Phinney.

Piercey, S. e. (2014). Analysis of Powdered refrence materials and known

samples with a benchtop, field portable X-ray Fluorescence (pXRF)

spectrometer: evaluation of performance and potential applications for

exploration lithogeochemistry. The Geological Society of LOndon .

Ryan Leblanc, A. S. (2014 ). Environmental Characterization of the Fire

Road Coal Mine Using Hydrological and Geophysical Investogation

Techniques . Fredericton, NB: University Of New Brunswick .

Taylor, J. (1996). The Microbiology of Acid Mine Drainage.

Three - D Geoconsultants Limited . (1984). The Fire Road - Bog Camp

Road 1983-1984 Percussion Drilling Program . Fredericton, NB: Three - D

Geoconsultants Limited .

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Al, T., & Butler, K. (2001). Environmental Geoscience, Acid mine

drainage in the Minto Coal Fields. Fredericton: Department of Geology.

Al, T., & Butler, K. (2001). Environmental Geoscience, Acid mine

drainage in the MInto Coal Fields. Fredericton: Department of

Geology.

GEMTEC . (1988). Surface and Groundwater Hydrology of the

Fire Road Mine Site . Fredericton: GEMTEC .

GEMTEC. (2014 ). Groundwater Sampling and Analysis June

2013, Former Fire Road Mine SIte . Fredericton : GEMTEC.

GEMTEC Consulting Engineers and Scientists. (2010).

Groundwater Sampling and Analysis June 2010, Fire Road Mine

Site . Fredericton, NB : GEMTEC Consulting Engineers and

Scientists.

Grace Dearbon Inc. . (1996 ). Evaluation of Options for the

Control of AMD Generation at NB Coal Ltd.'s Fire Road Mine

Site . Fredericton, NB : Grace Dearbon Inc. .

Ian Bragdon, K. H. (2014 ). Fire Road Coal Mine, NB AMD

Effects Assessment . Fredericton : University of New Brunswick .

Kawatra, S. K., & Eisele, T. C. (2001). Coal Desulfurization:

High-efficiency Preparation Methods. Taylor & Francis.

Kelsey Cheverie, L. E. (2014 ). 2014 Fire Road Mine Site

Preliminary Geochemical & Geophysical Report . Fredericton,

NB: Univeristy of New Brunsiwck .

LeBLanc, B. R. (2014). Geophysical & Geochemical

Investigation on Fire Road Mine ESCI 3713. Fredericton:

Univeristy of New Brunswick .


Acknowledgements

STOZA Corp. would like to thank Michele Coleman of NB power for the opportunity to work on this project, and to the mentors who have helped us throughout its duration.

• Dr. Broster

• Dr. Day

• Mr. Gilman Violette

• Dr. Butler

• Dr. Susak

• Steven Rossiter

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Questions?

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investigation of spot treatments for pockets of acidic mine...

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