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Procedures to conduct Fuel Stockpile Inventories

August 26, 2009

ARIPPA 19th Annual Technical Convention

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Items Covered

• Coal Pile Maintenance in Preparation for Stockpile Surveys

• Coal Pile Density Procedures• Coal Pile Volume Procedures• Summary and Questions

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Efficient Management of Stockpiles

• Provide easy access to material• Maximize load distance efficiency factor• Attain stack/reclaim rates• Meet blending requirements• Maintain or improve uniformity, integrity, and

quality• Minimize manpower or equipment• Safety• Be able to deal with stockpile fires• Reduce environmental impacts

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Stockpile Delivery Methods

• Truck dump• Rail dump• Ship or barge unload

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Coal on stockpile

• Delivered and stacked as cone• Rate of delivery determines number or shape

of cones• Kidney shape with moving stackout• Or multiple cones

• All cones need to be moved• For more deliveries• Safety improvement• Segregation reduction to preserve quality

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Kidney Stackout

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Multiple cone stackout

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Effects of Pile Conditions on Accuracy

• Windrows• Gullies• Inconsistent• Uncompacted• Compacted• Coal quality• Excessive

cones

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Working on pile

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Methods to avoid so moisture not increased

• Large flat stockpiles that allow little, if any, runoff

• Possibility of ponding on surface• Pushing coal through low areas that

have standing water while unloading/reclaiming

• Ground water levels higher than the pile or pile base

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Beneficial Practices in controlling moisture

• Keep stable side slopes, while increasing maximum height over smallest area

• Avoid flat tops• Enhance runoff by compacting surface

AND side slopes• Allow good drainage of the pile• Reduce moisture content of incoming

coal

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Pile construction by Rubber-tired

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Improved conditions=improved accuracy

• More consistent density• Less moisture variability• Less water means easier to move and

easier to burn• Consistent quality• Less chance for fire• Smoother surface easier for volumetric

calculations• Better burn rates

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What to do for improving pile conditions

• Work the pile in consistent pattern• Don’t rush due to time or amount of

delivery• Eliminate gullies from erosion• Eliminate windrows• Compact consistently across the pile• Reduce amount of loose coal in cones• Keep berms to minimum

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Conclusions - Questions

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Coal Pile Density Procedures

• ASTM D6347 – Standard Test Method for Determination of Bulk Density of Coal Using Nuclear Backscatter Depth Density Methods

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Methods for Stockpile Densities

• Nuclear Methods• Depth Density• Surface

• Direct Density Methods• Shelby Tube• Water-displacement Method• Continuous Auger Sampling Method

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Depth Density Procedures

• Nuclear Density Procedures• Calibration Procedures• CAST Method Procedures

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Preparation of Access Holes

• Small – diameter Augers• Split – spoon / hollow-stem augers• Hydraulic Push

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Installation of Access Pipe

• PVC Pipe• small – diameter augers• split – spoon / hollow-stem augers

• Steel Pipe• hydraulic Push

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Nuclear – depth density gauge

• Troxler Model 1351• Troxler Model 1352• CPN 501

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Recording density counts

• Gamma readings• Set of 2 each elevation• Not a density YET!

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Calibration of Nuclear gauge

• Same process• Gamma readings• Minimum 4 points• ASTM is 8 points• Linear regression• Forcing curve to a line

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Direct Density Methods

• Sampler• Different problems

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Direct Density Methods

• Sampling interval• Recovery of sample• Weighing the sample• Calculating the density

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Factors that effect density

• Access• Sampling interval• Recovery of sample• Gauge stability• Scale accuracy• Calibration

• Calculations• Stockpile

condition• Moisture• Quality• Pile construction

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Coal Pile Volume Procedures

• ASTM D6172-98 (reapproved 2004) Standard Test Method for Determining the Volume of Bulk Materials Using Contours or Cross Sections Created by Direct Operator Compilation using Photogrammetric Procedures.

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Introduction

• On a continuing basis, coal companies, power generating stations, quarries, aggregate suppliers, and other entities need to know how much material is contained in stockpiles at facilities such as mines, quarries, processing plants, generating stations, landfills and other storage sites.

• Through the use of aerial photography, ground control surveys, and photogrammetric processes, stockpiles can be mapped and the volume of an inventory area can be determined.

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Introduction

• This work usually requires a quick turnaround from the initial flight until the final volumes are calculated. Many times the photography must occur on a certain date or within a specified period.

• Coal stockpiles are usually needed within a short period of time, since they may be needed on an end of month and a mid-month basis.

• Landfills and quarries are usually needed within a month of aerial acquisition.

• Weather is always a concern.

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What is Topographic Mapping?

• All mapping techniques use data collection points to approximate the mapped surface.

• Aerial mapping uses photographic pairs to determine data collection points.

• Conventional surveying uses horizontal angles, vertical angles, and distances to determine data collection points.

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What is Topographic Mapping? (continued)

• The more data points and the selection of the data points used, the greater the accuracy.

• It is therefore important to have a system that allows for a rapid collection of many data points and coverage for the entire mapped surface.

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Using the data points collected

• Creating a digital terrain model (DTM)• DTM is actually the collection of mass

data points which include spot elevations, and break/fault lines.

• From this a triangulated irregular network (TIN) is generated.

• The TIN is then used to create contours.

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Calculating the volume

• To calculate the volume of data points collected you need to compare the base TIN file with the new TIN file.

• The base contour map is a digital file of the surface below the stockpile.

• The new contour map is a digital file of the data collected and calculated by the TIN.

• The difference of these two digital files is the volume of the stockpile.

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Basic Needs

• Aerial Imagery• Horizontal and Vertical Ground Control• Delineated Limits of Stockpile• Base Map Data

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Aerial Imagery

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Ground Control

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Stockpile Limits

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Base Map

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Base and Control Map

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Control Map

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Standards

• American Society of Testing and Material Standards

• American Society for Photogrammetry and Remote Sensing Standards

• National Map Accuracy Standards• National Coal Weighing and Sampling

Association Needs

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Rockwell Shrike Commander

Aerial PhotographyAerial Photography Needs

• USGS Calibrated Aerial Camera• Black and White or Color Film• Contact Prints or Digital Files• Film Diapositives or Digital Scans• Photo Enlargements

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Aerial photography camera

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Photogrammetry

• The illustration showshow an aircraft fliesalong a flight line(represented on theground by a dashedline in the illustration)and takes overlappingphotographs. Thedark gray area showsthe overlap area.

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Aerial Image

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Aerial Image

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Ground Control

• Permanent, RecoverableHorizontal and VerticalPositions are desired

• Minimum Four Points• Photo Identifiable or Targeted• XY Coordinate System:

State Plane, or a LocalPlant System.

• Vertical Control: North American Vertical Datum,or a Local Plant System

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Ground Control

• Global Positioning System (GPS) is used to obtain the Ground Control for many projects today.

• However, some projects, such as stockpile inventories, often require more conventional methods due to the specific requirements of the project.

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Ground Control

• Stockpile inventory mapping requires accurate points surveyed on the ground to ensure accurate mapping. In addition to photo identifiable points, they can be marked on the ground with plastic targets or markers that are visible in the aerial photographs.

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Stockpile Limits and Base Map

• Stockpile limit Delineation by Client

• Photo Enlargements, Contact Prints or Digital Scanned Images are submitted for Client marking and verification

• Base Map Confirmation by Client

• Client provides Base Map, usually in Digital Format. If not in digital format, it will need to be digitized or created in a mutually acceptable method

Aerial Photo of a Coal Mine with “Raw” and “Clean” Piles outlined.

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Photogrammetry

• Upon review and approval of (1) the aerial photography, (2) the ground control information, (3) the delineated stockpile limits, and (4) the digital base map data, the Digital Stereocompilation begins.

• The aerial photography is stereoscopically introduced to an Analytical Plotter or Digital Soft Copy Workstation.

• The ground control data is used to accurately orient the stereoscopic imagery and a photogrammetric solution is established for the data collection of the imagery.

• The Digital Stereo Mapping Technician compiles the required data according to the project specifications.

• The Technician collects necessary mass points and breakline data, sufficient to generate a Digital Terrain Model (DTM).

• The DTM is used to generate a TIN (Triangulated Irregular Network).

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Photogrammetry

• The stereo technician is using the latest digital synthetic stereo viewing technology to view the overlap area in 3D. This technology allows her to digitally map the terrain in three dimensions.

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Aerial Stereo Pair

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3D Imaging

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Topographic Mapping

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Volume Calculation

• To calculate the volume of the new stereo collected stockpile, the base elevation TIN file is compared with the new stereo compiled elevation TIN file.

• It is important that the new elevation data meets with the base file data at the toe of the pile.

• The difference of these two digital files is the volume of the stockpile.

• The volume is generated and a Report is prepared and delivered.

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Summary

• Aerial Photography• Ground Control• Stockpile Limit Delineation• Base Map Verification• Photogrammetric Stereo Compilation• Volume Determinations

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Thank You

• Summary and Questions