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Hector Choy, Long-Range Planning Supervisor, Black Thunder Mine, Gillete, Wyoming, United States
CHAPTER 5
Strip Mine Planning 
and Design
Hector Choy
INTRODUCTION
Modern strip mining (which is often referred to as open pit or 
open-cast mining) began with the development of the steam 
shovel used in the excavation of the Panama Canal. However, 
underground mining continued to dominate the extraction 
industries until the early 1900s, when strip mining proved 
itself to be more economical for near-surface, flat-lying 
deposits.
Strip mining is a form of surface mining that uses strip 
cuts to mine generally shallow, flat-lying deposits. Strip mines 
are typically layered deposits—a classic example is surface 
coal mining. This chapter concentrates on considerations in 
the mine planning and design process of strip coal mines. 
The primer for mining engineers is Surface Mining (Pfleider 
1972); see Kennedy (1990) for the updated second edition of 
that text, and SME’s Mining Engineering Handbook, 3rd edi-
tion (Darling 2011).
Mine Planning and Design
There are two general approaches to mine planning. The first 
is the development of a greenfield or new property. Capital 
investments have not been committed; the property may 
already have been acquired or is in the process of evaluation. 
The prefeasibility study establishes the value of the property 
and potential capital commitment. Prefeasibility may require 
a general mine plan to establish if mining is practical and may 
go as far as suggesting what equipment would be used. The 
feasibility study then details the capital commitment and life 
of the property and includes a detailed economic evaluation. 
To develop economics in terms of cash flow, expected net 
present value (NPV), and internal rate of return (IRR), the fea-
sibility study requires a detailed mine plan, equipment selec-
tion, schedules identifying the timing and amount of capital 
expenditures, and estimates of projected revenue and costs. 
Information on mining economics can be found in Stermole 
and Stermole (2019). Table 1 lists items to consider in a mine 
plan feasibility study.
An existing property or brownfield expansion consid-
ers an operation where equipment and facilities are already 
in place and future development is planned. Mine planning 
for existing operations may require a different approach to 
address market conditions and the need to expand, scale back, 
or maintain a steady-state production level.
In an existing property, where equipment and facilities 
are established, the two stages of mine planning are the short-
term mine plan and the long-term or (life-of-mine) plan. These 
stages are significant in that mines often assign designated 
staff and instigate significant mine planning efforts to best 
meet the differing requirements and level of detail for these 
two functions. A list of items to consider in the mine planning 
process is shown in Table 2.
Short-Term Mine Planning
The short-term mine plan (or operating plan) generally relates 
to a period of less than 5 years and is typically broken down 
into monthly, quarterly, and annual operating plans. Each 
stage reflects a level of detail designed to guide the mining 
toward fulfilling annual production and economic budgets 
and capital expenditures. A high degree of planning detail is 
placed on the first 2 years of short-range planning with col-
laboration from other departments such as production, main-
tenance, electrical, and plant. Each of these departments 
provides essential information to the planning process, such 
as mining methods, major equipment outages, preventive 
maintenance and repairs, substation relocation, and railroad 
and power plant outages, and it is the responsibility of the 
mining engineer to incorporate relevant information into the 
mine plan. During the first 2 years of short-range planning, 
sequencing and scheduling is performed on a monthly basis. 
For each month of the plan, the first step is to sequence and 
schedule the removal of soil material (topsoil), either by plac-
ing this into individual piles where it can be stored for later 
use during the reclamation process or laid down directly onto 
previously mined areas in the ongoing reclamation process. 
The second step is the sequencing and scheduling of the over-
burden removal process through conventional drilling and 
blasting, truck and shovel overburden prestrip (if required), 
cast blast, dragline bench (pad) construction, and dragline or 
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
86 SME Surface Mining Handbook
truck and shovel overburden removal to expose the coal seam 
beneath. The final step is the sequencing and scheduling of 
coal removal and blending from different pits if available. The 
process will include coal blasting, loading and hauling, crush-
ing, and storage to meet the production and quality require-
ments necessary to satisfy power plant contract agreements.
Long-Term Mine Planning
The defined planning periods can vary depending on the 
size and life of the reserves, along with the general purpose 
and objectives of the operation. The objectives of the long-
term mine plan include identifying and scheduling labor lev-
els, equipment production levels, and capital requirements 
Table 1 Salient factors requiring consideration in mine planning and feasibility studies
Information About Deposit General Project Information Development and Extraction Economic Analysis
Geology: overburden
Stratigraphy
Geologic structure
Physical properties (highwall arid 
spoil characteristics, degree of 
consolidation)
Thickness and variability
Overall depth
Topsoil parameters
Geology: coal
Quality (rank and analysis)
Thickness and variability
Variability of chemical 
characteristics
Structure (particularly at contacts)
Physical characteristics
Hydrology: overburden and coal
Permeability
Porosity
Transmissivity
Extent of aquifer(s)
Geometry
Size
Shape
Attitude
Continuity
Geography
Location
Topography
Altitude
Climate surface conditions 
(vegetation, stream diversion)
Drainage patterns
Political boundaries
Exploration
Historical (area, property)
Current program
Sampling (types, procedures)
Market
Customers
Product specifications (tonnage, 
quality)
Locations
Contract agreements
Spot sale considerations
Preparation requirements
Transportation
Property access
Coal transportation (methods, 
distance, cost)
Utilities
Availability
Location
Right-of-way
Costs
Land and mineral rights
Ownership (surface, mineral, 
acquisition)
Acreage requirements (on-site, 
off-site)
Location of oil and gas wells, 
cemeteries, etc.
Water
Potable and preparation
Sources
Quantity
Quality
Costs
Labor
Availability and type (skilled, 
unskilled)
Rates and trends
Degree of organization
Labor history
Governmental considerations
Taxation (local, state, federal)
Royalties
Reclamation and operating 
requirements
Zoning
Proposed and pending mining 
legislation
Compilation of geologic and 
geographic data
Surface and coal contours
Isopach development (thickness 
of coal arid overburden, stripping 
ratio, quality, costs)
Mine size determination
Market constraints
Optimum economics
Reserves
Method(s) of determination
Economic stripping ratio
Mining and barrier losses
Burned, oxidized areas
Mining method selection
Topography
Refer to previous geologic/
geographic factors
Production requirements
Environmental considerations
Pit layout
Extent of available area
Pit dimensions and geometry
Pit orientation
Haulage, power, and drainage 
systems
Equipment selection
Sizing, production estimates
Capital and operating cost 
estimates
Repeat for each unit operation
Project cost estimation (capital and 
operating)
Mine
Mine support equipment
Office, shop, and other facilities
Auxiliary facilities
Labor requirements
Development schedule
Additional exploration
Engineering and feasibility studyPermitting
Environmental approval
Equipment purchase and delivery
Site preparation and construction
Start-up
Short-range and long-range 
production plan
Cash flow
Revenue
Capital
Labor
Operating costs
Royalties
Taxes
Evaluation
Risk reward
Net present value
Internal rate of return
Source: Hrebar and Atkinson 1998
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 87
(including major equipment purchases, infrastructure expan-
sion, reserve expansion, acquisition of new reserves, mine 
permit acquisition, and end-of-life reclamation). Long-term 
mine plans usually cover a period greater than a year beyond 
the current active operations, up to and including the point 
when the life-of-mine plan starts. Typically, these long-term 
mine plans are broken down into levels of detail that include 
quarterly plans for up to 5 years, annual plans out to a mini-
mum of 10 years, and general plans out to the life-of-mine 
planning horizon. Other applications of long-term planning 
are to determine production sensitivity to revenues and costs 
(which would affect production rates), capital projects, and 
the life of the reserve. Both short- and long-term mine plans 
are decision tools to help manage the risk and reward opportu-
nities that confront mine management.
Risk and Reward
The successful implementation of a correctly formulated mine 
plan will yield the optimal recovery of the resource, as mea-
sured by optimizing the resulting revenues (reward) and effec-
tively controlling costs (risk). Costs for a new property can 
vary substantially because of unknown conditions. It is the 
mining engineer’s task to identify and characterize key condi-
tions and factors and to assign costs to them that realistically 
represent the risks involved in developing and safely mining 
the reserve. It is also the mining engineer’s function to get the 
most value from the reserve by using proven methods to mine 
and produce the resource in a timely manner. Determining the 
time value of money—or the NPV of a project—is the most 
common method of measuring the economic balance between 
risk (costs) and reward (revenues) for a mine development 
project:
i1NPV cash flows
t=
+^ h (EQ 1)
where
 NPV = net present value
 cash flows = net cash flows at time t
 i = discount rate
 t = time of cash flow
A base-case mine plan is typically developed to identify 
and quantify the costs and revenues associated with develop-
ing the property. Successive planning scenarios are usually 
developed to evaluate the cost/revenue effects of changing 
mine plan layout, sequencing, production schedules, equip-
ment, or other parameters to minimize cost impacts and maxi-
mize the resource recovery and revenues to optimize NPV. 
This process is a daunting one but is nevertheless a necessary 
task, and as multiple plans are developed and evaluated the 
what-if scenario begins to gel into a solid base-case plan.
Table 2 Major steps in surface mine development preceding production buildup and full production
Assembly of 
Minable Coal 
Package
Market 
Development
Environmental 
and Related 
Studies
Preliminary 
Design, Machine 
Ordering NEPA Process Permits
Design and 
Construction
Mining 
Preparation
Lease 
acquisition
Mapping the 
area
Drilling 
program
Surface 
drilling rights 
acquisition
Drilling, 
sampling, 
logging, 
analysis
Mineral 
evaluation 
(determination 
on commercial 
quantities 
present)
Drilling on 
closer centers 
(development 
drilling)
Sampling, 
logging 
analysis
Surface 
acquisition
Market survey
Potential 
customer 
identification
Letter of intent 
to develop and 
supply
Contract 
negotiation
Initial 
reconnaissance
Scope of work 
development
Consultant 
selection
Implementation
Environmental 
impact report
Environmental 
monitoring
Conceptual 
mining 
development
Economic size 
determination
Mining system 
design, 
layout, and 
development
Equipment 
selection
Stripping 
machine 
ordering
Mine plan 
development
Identification 
of lead agency 
for EIS
Draft EIS
EIS review and 
comments
EIS hearing 
and record
Federal EIA 
review
Council on 
Environmental 
Quality filing
Mining and/
or reclamation 
plan approval
State water 
well rights 
appropriation 
permits
State special 
use permit, 
such as a 
reservoir
State mining 
permit
State industrial 
siting permit
Federal NPDES 
permit
U.S. Forest 
Service special 
land use permit
Preliminary 
design and 
estimation
Material 
ordering and 
contracting
Water well 
development
Access road 
and site 
preparation
Railroad 
construction
Power supply 
installation
Facilities and 
coal handling 
construction
Warehouse 
building and 
yards
Coal 
preparation 
and loading 
facilities 
construction
Overland 
conveyor 
construction
Stripping 
machine(s) 
erection
Loader erection
Support 
equipment 
readying
Labor 
recruitment and 
training
Source: Jones 1977
Note: EIA = environmental impact assessment; EIS = environmental impact statement; NEPA = National Environmental Policy Act of 1969; 
NPDES = National Pollutant Discharge Elimination System.
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
88 SME Surface Mining Handbook
OUTLINING RESERVES
Project mapping often begins with a general location map that 
shows geopolitical boundaries, towns, roads, general topo-
graphic features, the mine location, and any nearby residences 
or structures. In addition to the general location map, one 
should also be aware of any old abandoned or active under-
ground mines beneath the surface mine property.
Mapping
Planning starts with more detailed mapping of topography, 
surface drainage features, surface and mineral ownership, 
existing facilities and infrastructure, and potential mine area 
and disturbance boundaries. Commercial aerial mapping 
flights and unmanned aerial vehicles (UAVs or drones) retro-
fitted with GPS and LiDAR lasers can provide accurate digital 
images of the terrain and are now easily obtained and inexpen-
sive. The acquired data can be processed into a digital terrain 
model and subsequently into a surface contour of the property 
to help identify existing structures, facilities, and other sur-
face features. Ground surveys using GPS equipment provide 
additional detail and have, in the short time since its incep-
tion, become the basis for the ongoing process of mapping 
and documenting mining and related activities. Infrastructure 
includes the location of existing features—roads, rail lines, 
pipelines, power lines, communication lines and cell towers, 
wells, buildings, and structures on and adjacent to the mining 
property—that may be used for or affected by mining activi-
ties. It is important to identify not only features related to the 
mining activities, but also features and resources that may 
require special environmental considerations, such as streams, 
ponds, forest land, fire breaks, wetlands, wildlife habitat, and 
other protected or environmentally sensitive areas. Initial geo-
logical maps should include surficial geology (outcrops, sur-
face geologic exposures, structural features) and indications 
of strike and dip of structures. Maps prepared by governmen-
tal research organizations such as the U.S. Geological Survey 
are a typical starting point for new operations. Conversion of 
GPS surveys to a geographic information system format allow 
the ongoing collection and integration of ownership, environ-
mental, geologic, mine, and reclamation planning and opera-
tional information.
Because modern mapping is computerized, map infor-
mation is developed and saved as individual layers that can 
then be selected and combined to produce a range of special-
ized maps. Although it is important to define and establish a 
common mapping datum for compatibility, determining a map 
scale is not critical because the scale can be adjusted later to 
meet map presentation requirements.After a standard map-
ping datum is established, all mapping should be completed 
and input to that datum. The mapping datum and coordinate 
system should be compatible with the maximum area expected 
to be affected by mining and should accommodate both short- 
and long-term planning. Documenting the basis for the map-
ping information (metadata) and preserving original data in a 
digital format with appropriate backups is important. Access 
and ability to change, alter, or delete information on original 
data maps should be carefully restricted, and any such altera-
tions properly and securely logged.
Drill-Hole Coverage
Sufficient drill-hole information is critical for the development 
of geologic and mine planning models. For example, if a com-
pany has a history of drilling in the area, such as oil and gas 
exploration; other mining companies or government research 
agencies have drilled in the area, then all known drilling infor-
mation should be reviewed and evaluated for reliability and 
content. Field geologist data and drilling and geophysical 
information are then consolidated into a geologic computer 
model. In a new operation (or one that is expanding into a 
new reserve area), a drilling program will be required to col-
lect enough information to adequately evaluate the property. A 
resource is typically defined by the level of confidence in the 
occurrence and extent of the minable seams. In open pit min-
ing, the terms measured, indicated, and inferred convey both 
the extent of drilling and the level of confidence in the reserve 
characterization. In surface strip mines, the deposits tend to 
have consistent thickness characteristics; therefore, drill spac-
ing for initial exploration often involves a grid spacing of 
0.4 to 0.8 km (Figure 1). Areas that require more extensive 
drilling (or seismic studies) are seam boundaries, structural 
features, and surface disconformities such as valleys, surface 
displacements indicating faulting, and depositional uncon-
formities. The greater the variation in reserve characteris-
tics, the greater is the need for increased drilling density or 
supplementary data collection. Data quality can be evaluated 
and supplemented using geostatistics techniques, which take 
into consideration variances in the coal seam when drill data 
are being correlated. In operating mines, geologic structure 
and coal quality information from the initial drilling program 
can be supplemented by performing infill exploration drill-
ing ahead of the active pit areas. Infill drilling refers to drill-
ing additional exploration holes within the initial exploration 
drilling grid spacing. Normally, drill spacing for infill explora-
tion drilling is in the range of 122 to 244 m apart (Figure 2). 
Figure 1 Initial exploration drilling spacing: undeveloped 
area
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 Strip Mine Planning and Design 89
This tighter drill spacing will yield a more refined geological 
structure and coal quality model. Some mines prefer to obtain 
structural and quality information from drilling and blasting 
activities in active operating areas. Once a geological model 
is developed, the engineer should use the model to become 
familiar with the reserve and identify structure, thickness, and 
quality issues that may exist in planned mining areas.
Geology to Mine Planning
Using the drill-hole information and surface structural fea-
tures, the geologist develops a geological model. This model 
should include seam identification, structure, thickness, qual-
ity, and characteristics that may affect mining efficiency such 
as overburden or interburden thickness and characteristics, 
fracturing, variations in thickness, washouts, and water table. 
The engineer should be looking for inconsistencies in qual-
ity and thickness to determine the extent of minable seams 
and the mining characteristics that would affect equipment 
selection and productivity. It is also important to understand 
overburden, interburden, and floor characteristics and struc-
tural constraints as indicators of potential stability prob-
lems. Information on highwall angle and spoil angle can be 
estimated by material type and stability characteristics from 
geotechnical analysis. Thickness, strike or dip, strip ratio, and 
quality maps should be developed for all potentially minable 
seams. This can either be a fairly straightforward process, or 
more complex and time-consuming if seams combine and 
split. Transitioning from a geological model to a mining model 
requires the understanding of reserve characteristics, potential 
structure hazards, equipment capabilities, and strip mining 
methods. Geological cross sections, history and knowledge 
of the area, research on similar deposits, and knowledge of 
mining methods are all resources the engineer can use to opti-
mize mine planning.
The basis for a good mine plan is a good understanding 
of the topography and geology of the property. To facilitate 
this, there are numerous geologic and mining computer soft-
ware programs that can produce accurate topographical maps 
based on aerial and land survey data information that cover 
all of the projected mining area along with potential facili-
ties and any significant surface structures. Most topographical 
surfaces are normally stored electronically as a grid or trian-
gulated irregular network (TIN) file. In addition, it is neces-
sary to become familiar with seam characteristics, structure, 
and the quality information for each minable seam (referred to 
as target seams). Contour thickness maps (also known as iso-
pach maps) should be generated for each of the targeted seams 
and should include information on overburden, interburden 
(waste material between targeted seams), and the undiluted 
thickness of the targeted seams. Quality maps (sometimes 
called isopleth maps) should also be created for each targeted 
seam. Geologic structure maps (also known as contour maps) 
need to be developed to identify any structures (e.g., faulting 
and offsets) that would affect the mining method or decrease 
recovery and increase dilution and waste.
Coal loss due to ribs, barriers, top or bottom of coal seam 
dilution, and overblasting can be as high as 10% in eastern 
U.S. operations (Secor et al. 1977).
Reserve Evaluation
Modern mine planning starts with a computer model of the 
resource. The extent, structure, quantity, and quality of the 
resource and the associated burden material should be well 
defined. These data allow the engineer to develop a mining 
model. The mining model will incorporate and consolidate 
data of the resource into a model of minable seams, waste, and 
soil materials (sometimes referred to as suitable plant growth 
material or topsoil). For this purpose, a reserve is identified as 
a resource that is delineated by its economic strip ratio.
Strip Ratio
The economic stripping limit is usually the first factor to 
be determined in establishing the mine plan. The economic 
stripping ratio (ESR) is defined as the cubic meters of waste 
material to be removed to uncover 1 t (metric ton) of product. 
For illustration purposes in this chapter, coal will be used as 
the resource. Developing maps that show the ratio of over-
burden thickness to a minable coal thickness is a good place 
to begin. This ratio can be converted to a strip ratio map by 
mapping the thickness of the overburden and interburden 
converted to cubic meters and divided by the thickness of the 
coal converted to metric tons. This ratio is calculated using 
the cumulative thickness of both overburden/interburden and 
coal seams down to, and including, the lowest minable seam.
For example, for a 61-m cumulative overburden/interbur-
den thickness with a total coal thickness of 6.1 m, and assum-
ing the average density of bituminous coal at 1.28 t/m3, the 
stripping ratio would be calculated as follows:
burden = 61 m × 0.91 m × 0.91 m = 51.0 m3
coal resource= 6.1 m × 0.91 m × 0.91 m × 1.281 t/m3 
= 6.47 t
or
Figure 2 Infill exploration drilling spacing
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
90 SME Surface Mining Handbook
stripping ratio = 51.0 m3 ÷ 6.47 t = 7.88:1 (EQ 2)
These calculations can be used to define an economic 
limit:
• Cost for overburden/interburden mining is $1.63/m3
• Cost of coal mining is $2.76/t
• Estimated revenue is $13.23/t
The economic stripping ratio is defined as
RESR MCO
MCC= − (EQ 3)
where
 ESR = economic stripping ratio (m3/t)
 R = revenue from coal or ore ($/t)
 MCC = mining cost of coal or ore ($/t)
 MCO = mining cost of overburden/interburden/waste ($/m3)
($13.23/t – $2.76/t) ÷ $1.63 = 6.41 or 6.41:1
The ratio becomes the economic mining limit and is the 
first step in establishing the economically minable reserve. 
The formula can become more complex as issues of quality 
affect the economic value of the coal. It is important for the 
engineer to understand the mining economics and contract 
restrictions, including coal quality penalties and bonus provi-
sions (such as lower ash and sulfur, and higher BTU content), 
may affect revenues. Other adjustments to coal recovery (and 
actual minable reserves) would be dilution and in-seam losses, 
which tend to downgrade the stripping ratio by increasing the 
cubic meters of waste and decreasing the number of metric 
tons of resource. Depending on mining conditions and thick-
ness and quality of the seam, losses can amount to several 
percent and have a significant impact on the reserve.
RESOURCE CONTROL
Ownership of land and minerals is a key consideration that 
should be addressed and determined early in the planning 
process because it can affect development time frames, per-
mitting requirements, development cost structure, and project 
profitability.
Land and Mineral Ownership
Land ownership typically consists of two components: the 
surface estate and the mineral estate. Either or both may be 
held by private (fee estate) or public (public estates are gener-
ally managed by federal or state agencies) entities. In some 
cases, the surface and mineral estates may be held separately 
(severed estate).
The rights to access and utilize the surface and to develop 
and produce the mineral resource can be secured through 
direct ownership (purchase of the surface and/or mineral 
estate), lease agreement, or a combination of these legal vehi-
cles. In the instance of federally managed public estate coal, 
a company with a proposed coal lease must submit its request 
to acquire the lease with the Bureau of Land Management 
(BLM) through a lease by application. The BLM then per-
forms an environmental assessment study and establishes coal 
lease market value and sale criteria. Interested companies that 
can mine the coal lease economically must submit competitive 
bids and the BLM awards the coal lease to the highest bid-
der. The successful bidder must pay a bonus bid for each ton 
of coal in the lease. In many cases, the right to develop and 
produce the mineral resource (particularly where public estate 
minerals are involved) carries with it certain rights of sur-
face access and use. However, there may be instances where 
the surface is privately owned and the coal beneath publicly 
owned or vice versa. In either case, lease agreements will need 
to be developed and agreed upon by both parties.
With the exception of direct ownership, other access and 
development rights typically involve structured payments 
to secure and exercise these rights. These typically take the 
form of advance payments to secure the rights, flat-rate annual 
fees for use of the lands, royalty payments based on mineral 
production rates, fee payments keyed to specific activities, or 
combinations of these payment mechanisms.
Secure, well-defined access and development rights are 
an important element of a stable cost structure and are key to 
project cost control and profitability. Also, ownership rights 
for the project area and an adjacent buffer zone can be impor-
tant in minimizing and successfully addressing potential con-
flicts with adjacent landowners and uses.
Other Resources
In Wyoming (United States) during the 1990s and 2000s, gas 
collected from coal seams (i.e., coal-bed methane) became a 
significant consideration relative to permitting and the timing 
for development of coal reserves where both (independently 
recoverable) resources exist. Existing oil and gas (or other 
mineral) leases must be a consideration in the extent of and 
timing for development and production of reserves because 
most of these wells will need to be purchased to mine through 
them or the well bypassed altogether.
PERMITTING
Mine permitting is the process of preparing and submitting 
relevant project information for review and approval by 
jurisdictional government authorities to verify project plan 
compliance with applicable laws and regulations. In general, 
applicable laws and regulations as they relate to mining are 
designed to prevent, control, minimize, or effectively mitigate 
potential adverse mining-related impacts on the environment, 
wildlife, and human health and welfare.
Mine permitting may involve submittal of individual 
permit applications for approval of specific mining-related 
activities (mining and reclamation, air emissions, water dis-
charge, wildlife surveys, facility construction, and so on). 
Alternately, it may involve environmental analysis and plan 
approvals for the project as a whole or a combination of all 
these approval mechanisms may be involved. An outline of 
typical mine permitting requirements is provided later in this 
chapter.
Typically, the process involves a review by national or 
state/provincial agencies that have approval authority over 
land uses or mining and reclamation plans. It may also involve 
review by agencies with authority over specific environmental 
resources such as air, water, wildlife, and other specific project 
aspects. Normally, some provision is provided in the permit-
ting process for input by affected parties and nongovernmen-
tal organizations.
Environmental Baseline
At the start of the permitting process, it is important to effec-
tively characterize environmental resources and values as they 
exist in the project area (this is the baseline) prior to min-
ing disturbance. Generally, baseline characterization involves 
field studies by qualified professionals of all resources and 
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 91
values that may be affected. The following resource values 
are typically characterized:
• Land use
• Cultural, archaeological, and paleontological resources
• Geology
• Meteorology and air quality
• Surface and groundwater hydrology
• Soils
• Vegetation and wetlands
• Fish, wildlife, and related habitat values
• Aesthetics and noise
• Socioeconomic conditions
Baseline characterization then forms the basis for devel-
opment of specific measures to prevent, control, minimize, or 
mitigate the potential impacts and for the evaluation of poten-
tial mining-related impacts with consideration of planned con-
trol and mitigation measures.
Mitigation Plans
At the point in a project at which permitting activities are 
initiated, mining and reclamation plans are generally well 
defined, including the locations, extent, and nature of surface-
disturbing activities. Comparison of the extent and nature 
of mining activities with information from environmental 
baseline characterization provides the basis for development 
of project mitigation plans. In many cases, required mitiga-
tion measures are defined to some extent by specific regula-
tory requirements. A common example is the requirement for 
the collection and treatment of runoff from mine disturbance 
areas to comply with effluent standards before water is dis-
charged to natural drainages. To address site conditionsand 
constraints or enhance postmining land use, the mine operator 
may have an opportunity to develop site-specific mitigation 
plans or to modify mitigation plans within the limits of regula-
tory constraints.
Impact Analysis and Monitoring
Environmental impact analysis is an integral part of the per-
mitting process, whether it is the evaluation of regulatory 
compliance as part of a permit review or of the significance 
of potential impacts.
In the context of a permit review, impact analysis focuses 
on whether the proposed mining and related activities (and 
planned mitigation measures) meet specific regulatory require-
ments and performance standards.
For environmental factors, impact analysis typically 
includes the evaluation of direct, indirect, and cumulative 
impacts and assesses whether potential impacts meet an objec-
tive, or indeed the subjective measure of significance.
Prepared and evaluated as part of the permitting process, 
monitoring plans provide a mechanism for the direct mea-
surement of impacts on specific environmental resources. If 
properly designed and administered, monitoring can identify 
significant changes in resource conditions. It can be used to 
assess the effectiveness of mitigation measures and the accu-
racy of impact assessments and to modify operating and miti-
gation practices.
Timing
It is critical to allow sufficient time in the project schedule 
for project permitting. It normally takes between 12 and 18 
months to collect adequate information for the environmental 
baseline characterization. Depending on project complexity, 
permit preparation may require between 6 and 24 months. 
Required agency reviews and approval may extend the over-
all permitting schedule by another 6–24 months. Important 
factors in minimizing permitting time frames include ensur-
ing adequate and timely baseline characterization, conduct-
ing effective ongoing communication with stakeholders, and 
coordinating closely with jurisdictional agencies.
INFRASTRUCTURE
Existing infrastructure (i.e., roads, water wells, oil or gas 
wells, pipelines, phone lines or power lines that run through 
the property) must be identified and mapped. The landowners 
must be contacted and be informed of the intent and potential 
impacts of mining.
Existing Infrastructure
Where existing infrastructure may be affected by mining, mit-
igation action may be necessary, either in the form of compen-
sation or relocation/replacement of the structures.
Mine Infrastructure
The necessary infrastructure to support mining and related 
operations will need to be planned, developed, and accounted 
for in the economic evaluation process. This infrastructure 
will include roads and utilities, office and change-house facili-
ties, warehouse and maintenance facilities, material handling, 
processing and product transportation facilities, drainage and 
sediment control systems, and so forth.
Infrastructure Mapping
Maps showing both existing and planned mine infrastructure 
are typically developed as part of the mine planning process. 
Features that will be mined around or that are not within the 
mining area are not shown on the reserve map. Some struc-
tures require economic analysis to determine whether min-
ing around or compensation, relocation, or replacement is the 
better economic approach. These areas may be included in 
the reserve, but until the status of the areas is resolved they 
should be excluded in the base-case mine plan as non-minable 
reserves.
PIT DESIGN
For surface strip mines, the choice of mining method is dic-
tated by the terrain, geology, and depth of the resource. The 
terms contour mining and area mining are used to describe 
mining methods that are suited to specific geologic and topo-
graphic conditions.
Mining Methods
Where the terrain is variable and multiple seams are present, 
contour mining may be the best option. In the Appalachian 
mines of the United States, thin seams, undulating topography, 
and sometimes steeply dipping seams require equipment that 
is highly adaptive and mobile and can move material relatively 
long distances. These conditions favor contour mining using 
large-tracked dozers, rubber-tired scrapers, truck and shovel 
or loader-truck equipment fleets, and occasionally small drag-
lines (23–35 m3). As the ESR increases, contour mining may 
be coupled with follow-up to auger, highwall mining or with 
conventional underground methods.
Where the terrain is relatively uniform and the seam 
or seams are flat lying, area mining is often the preferred 
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
92 SME Surface Mining Handbook
approach. Relatively large flat-lying deposits such as the coal 
reserves of Wyoming’s Powder River Basin (PRB), phosphate 
deposits in Florida (United States) and the Middle East, and 
the Canadian tar sands are well suited to area mining meth-
ods using large draglines (46–120 m3), fleets of large-scale 
shovel trucks (shovel capacity 46–76 m3; truck capacity 
140–230 m3), or even bucket-wheel excavators (BWEs) and 
cross-pit conveyor systems. Using large stripping equipment 
and moving large quantities of material keeps unit operating 
costs to a minimum. The PRB mines initially commenced in 
the mid-1970s because of the Organization of the Petroleum 
Exporting Countries (OPEC) oil embargo. They started at the 
coal seam outcrop and were typically mined at a 1:1 stripping 
ratio up until the 1980s; however, by the 1990s the stripping 
ratio had increased to more than 2:1 and at present the strip-
ping ratio is more than 3:1. As mining progresses to the west, 
the stripping ratio increases as the coal seams dip between 1% 
and 2% to the southwest and the overburden gets thicker. This 
increase in strip ratio is also reflected where split seams occur. 
Coal quality also increases from north to south, which can 
have a significant effect on the ESR. Changes in geology must 
be taken into consideration in pit design and equipment selec-
tion. Bise (2003) gives several examples of equipment selec-
tion. Bucyrus-Erie Company (1979), Caterpillar Performance 
Handbook (Caterpillar, Inc. 2018), and Specifications and 
Applications Handbook (Komatsu 2013) are good sources of 
information on shovel and truck selection and operation.
Large electric shovels are used in both contour and area 
mining. They offer good flexibility, reasonable mobility, and 
moderate to high loading capacity, and they can be used for 
both stripping overburden and ore loading. However, electric 
shovels do require a truck fleet, along with associated support 
equipment (dozers, blades, and water trucks) and haulage-
road requirements, which can increase production costs.
Draglines are high-production machines used to strip and 
move overburden over short distances. Draglines have limited 
mobility and are generally not suited for loading product. It 
can take up to a year to construct a dragline, and its cost can 
range from $50 to $100 million. Nevertheless, draglines are 
dominant in the large surface coal mines in the United States 
and in other large flat-lying deposits throughout the world 
(Cassidy 1973).
In the lignite mines of Europe and the U.S. Gulf Coast, 
large BWEs and conveyor-belt systems are used to excavate 
and move large volumes of overburden and product economi-
cally. The BWE is a continuous-excavation machine capable 
of removing up to 240,000 m3 of material per day. BWEs are 
found mostly in coal mining in Europe, Australia, and India. 
A BWE can cost more than $100 million and take 5 years to 
construct.
A compilation of equipment application and various 
mining scenarios as applied at operating properties can be 
found in Chironis (1978) and Kirk (1989). Support equip-
ment including drills, dozers, scrapers, loaders, graders, water 
trucks, and—depending on individual mine requirements—a 
multitude of other equipment required to complete the min-
ing cycle is a significant capital and operatingcost. Sources 
for accounting for this equipment include vendor publications 
such as the Caterpillar Performance Handbook, Edition 48 
(Caterpillar, Inc. 2018) and vendor websites.
Cast blasting is a technique generally used in combination 
with dragline operations to increase overburden production 
capacity and reduce costs. Occasionally truck and shovel, 
dozers, and scrapers are used in lieu of draglines. Cast blast-
ing utilizes the blast energy and gravity to move a portion of 
overburden from the highwall side of the pit into the previous 
empty pit and against the previous spoils. The portion of the 
overburden that is not casted onto the empty pit is then moved 
onto the spoils using the dragline effectively, thereby reduc-
ing overall dragline production and rehandling requirements. 
However, the effective design and control of blasting is impor-
tant to maximize overburden movement while preventing loss 
of the underlying resource, particularly in multiple-seam pits.
Highwall mining is a method of increasing coal recov-
ery in a pit where the stripping ratio has reached its economic 
limit and surface operations are no longer cost-effective. Two 
types of highwall mining are commonly used: auger min-
ing, in which a large-diameter auger bores parallel holes into 
the exposed coal seam; and conventional mining, in which a 
remote-controlled continuous miner, coupled with an exten-
sible conveyor, extends parallel entries into the exposed coal 
seam. For highwall mining to be effective, the key criterion is 
that the coal and surrounding rock must be competent to be 
self-supporting when a portion of the coal seam is removed. 
Geotechnical calculations determine the size and allowable 
depth of the auger or miner entries. Recoveries above 50% 
are possible with augers as large as 2.4 m in diameter, and 
conventional methods can result in slightly higher recover-
ies. Experience has shown that highwall mining is not well 
adapted to steeply dipping seams.
Pit Geometry
After the boundary of the minable reserves is established, the 
geometry and structure of the reserve dictate pit orientation 
and configuration. When the pit orientation is laid out, the 
mapped dip and strike of the seams and any geological struc-
tures such as faulting or discontinuities should be taken into 
consideration. Geotechnical evaluations provide additional 
valuable information for determining highwall and spoil slope 
angles, slope angles for waste and soil stockpiles, pit-end and 
interbench slope angles, and the overall highwall angle for 
multiple-seam operations.
For both planning and operations tracking and reporting, 
a standard naming convention should be established for desig-
nating and referring to specific mining areas, pits within each 
mining area, and cut sequencing within each pit. This nam-
ing convention should designate and explain mining units to 
be used in the scheduling process. The width and length of 
the pits are typically constrained by the pit geometry, physical 
limitations of the equipment (e.g., dragline reach), and the tar-
geted production rate required. Pits are generally broken down 
into strips and mining blocks based on both production sched-
uling considerations and the accuracy required for reporting 
volumes. Each mining block should contain information such 
as area, overburden thickness and volume, coal thickness and 
tonnage, and coal quality. Short-term planning often requires 
smaller blocks (i.e., 60 × 60 m), depending on drill spac-
ing and quality variations. A smaller mining block provides 
increased accuracy relative to production volumes and qual-
ity. Long-term planning does not require the same accuracy, 
so larger mining blocks may be acceptable (i.e., 250 × 60 m), 
thereby reducing data requirements and the amount of time 
required to input and analyze the data for mine scheduling.
Points to consider when developing the design of mine 
pits include the following:
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 93
• Orientation of the pit with respect to the strike and dip 
of the seam and site topography. Pits with inside curves 
result in insufficient spoil room and additional rehandle 
and should be avoided. Outside curves create additional 
spoil room and provide for spoil-side access to the coal 
seam. Similarly, mining up-dip creates more spoil room 
and reduces the potential for spoil failure. If the terrain 
is relatively flat, straight pits usually give better control 
over the pit and tend to result in better productivity.
• Prominent structural features, such as faulting, 
along with intersecting drainages and groundwater. 
A groundwater dewatering system, such as drilling wells 
ahead of the active pits, may be required to reduce the 
impact on highwall stability. The water produced from 
dewatering wells can later be used for dust suppression 
on haul roads and while drilling on blast patterns.
• Length and width of the pit. Generally, a maximum pit 
length of 1.6 km (1 mi) is a good rule where ramp access 
to the pit floor is sufficient. Most ramps are spoil side, but 
there are occasions when highwall ramps and drilling and 
blasting ramps are required. Minimum pit width is driven 
by the depth of the pit and equipment clearances needed 
in the pit bottom. There generally needs to be sufficient 
width in the bottom of the pit to operate coal-loading 
equipment with truck and drill access. Keeping the pit 
width to a minimum is necessary to minimize rehandling.
• Haul access. This consideration of pit design should provide 
sufficient room for drilling, blasting, and coal extraction. 
Intermediate spoil ramps, usually at least one per pit, are 
required to access the pit bottom from either side of the 
main haulage ramp. Pit-end ramps are also a consideration, 
so that coal extraction, drilling, and blasting are not cut off 
by overburden operations. Haulage access design becomes 
more complex for multiple-seam operations.
• Highwall and pit-end ramps. These are used when spoil 
material is unstable. The disadvantage of highwall ramps 
is that the ramp must be re-established after each cut, 
and the main haul road requires relocation when mining 
advance encroaches on the existing haul road.
Rehandle
Rehandle is defined as material that is moved more than once 
to uncover the same amount of resource. A normal amount 
of rehandle for a dragline is 10%; however, this depends on 
the dragline mining method. Some circumstances require 
increased rehandle, such as when pit width and/or overbur-
den depth is greater than the average design for the equipment 
being used. In such cases, rehandling material may be more 
cost-effective than purchasing additional equipment or using 
equipment that is more costly on a unit production basis. When 
rehandle costs and volumes for major production equipment 
increase beyond normal limits, the availability and effective 
productivity of the equipment for stripping is decreased. 
Utilizing truck and shovel prestripping on a dragline pit may 
decrease rehandle significantly, resulting in additional strip-
ping capacity but increasing total stripping cost. Managing 
rehandle becomes a trade-off between production capacity 
and lowest-cost utilization of the equipment.
Another source of high-dragline rehandle occurs when 
draglines have to mine across a coal ramp. As the dragline 
approaches the ramp, it becomes difficult to spoil the overbur-
den material in front of the ramp to its final spoil destination 
in a single pass. This material must temporarily be dumped 
on the ramp and subsequently rehandled for final spoiling. In 
many cases, this inefficiency is reduced by removing some of 
the rehandle material with truck and shovel or loader-truck 
assistance.
Unnecessary rehandle can occur when stockpiles are 
placed too close to the active pit or when production schedul-
ing requires rehandle of stockpiled material. Spoiland high-
wall failures, which can also result in unnecessary rehandle, 
may result from poor maintenance of the pit bottom (i.e., large 
amounts of standing water), stacking spoils too high, high-
wall/spoil angles that exceed design parameters, or weak floor 
structure. An elevated water table, water in the pit, and poor 
surface-water drainage can all greatly influence highwall and 
spoil stability. Unplanned rehandle is an unnecessary cost that 
can have a direct impact on production cost.
Mining Sequence
For a new property, the mine planning process comprises set-
ting a target production, selecting the equipment necessary to 
meet that production rate, and running a projected production 
schedule to determine the economics of the plan. Production 
sensitivities are then run to determine if the plan can be 
improved by changing the production level, equipment, pro-
duction sequence, or other preselected parameters. It is not 
uncommon, and indeed it is acceptable, to run several itera-
tions to produce an economically optimized mine plan.
For an operating mine, production targets and equipment 
fleet may be preset. In such situations, meeting the target pro-
duction rate becomes the focus of planning runs to best fit 
adjustments to pit configuration and sequencing to the equip-
ment for a given production rate. In this case, planning options 
may include supplementing, replacing, or idling existing 
equipment to meet the required production rate. The mining 
sequence is considered in the pit design phase.
A typical example of mine sequencing is a dragline oper-
ation initiated with a box cut. In a dragline operation, the box 
cut is typically the initial excavation, which creates sufficient 
spoil room for the first dragline pit. Figure 3 illustrates three 
box-cut scenarios.
A typical mining sequence would involve topsoil removal, 
overburden removal, coal removal, backfilling of the resulting 
Cut
End Cut
Spoil
A
Seam
A
Overburden
Cut
End Cut with Rehandle
Spoil
Borrow Pit
Spoil
Spoil
A
Seam
A2
A1 Overburden
Cut
Borrow Pit
Spoil
A
Seam
A
Overburden
Source: Skelly and Loy 1975
Figure 3 Box-cut methods
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
94 SME Surface Mining Handbook
pit with overburden spoils, and grading of the spoils to the 
final reclamation configuration, followed by reclamation grad-
ing, replacement of soil materials, and revegetation. For most 
regulated operations, unless there is a variance in the permit, 
soil materials and, in some cases, underlying weathered mate-
rials are stripped and stockpiled for future replacement on 
regraded spoil materials. In some cases, these materials can be 
directly replaced on existing regraded spoil areas, avoiding the 
need for stockpiling and often resulting in better reclamation.
Figures 4A–4G illustrate the steps in a typical dragline 
sequence. Figure 4A shows the pit as it would look at the end 
of the previous cycle. The coal is extracted and the pit is ready 
for the next cut, which is shown by the vertical dashed line. 
Figures 4B and 4C illustrate the results of cast blasting on both 
the upper and lower seams. Figure 4D shows the upper bench 
being graded in preparation for the dragline bench. Figure 4E 
illustrates the several phases of stripping that a dragline would 
perform; the first is extending the bench to allow the dragline 
to walk out far enough to cast the next cut of spoil to build a 
spoil-side bench for the dragline to sit on. In Figure 4F, the 
dragline is moved to the spoil side, where the bench has been 
graded to an elevation that allows the dragline to uncover the 
coal seam. Finally, Figure 4G shows the section immediately 
before removing the coal, which is the last step in the cycle. 
When the coal has been extracted, the cycle is repeated.
The purpose of generating range diagrams (Figure 5) is 
to determine the amount of material moved by the production 
equipment in each sequential step. These volumes are then 
used to determine the productivity of the equipment for that 
specific pit geometry. Overburden thickness and changes in 
the coal seam geometry can affect the production levels and a 
different configuration may be required.
The trade-off with the cast-blasting technique is the loss 
of coal and dilution due to fracturing of the coal seam at the 
exposed highwall of the pit, sometimes referred to as the wedge 
(Figure 6). Other configurations that could be compared to cast 
blasting would be a pre-bench truck and shovel or scraper fleet, 
depending on the depth of the material above the first seam.
Computer programs that simulate dragline scenarios are 
used to generate the equipment volumes needed for scheduling. 
By using the volumes and tonnages from the mining blocks and 
adjusting the equipment configuration and rate of production 
for different geometries and sequencing, a database of schedul-
ing volumes can be generated by pit and equipment type with 
rehandle quantities and expected coal production tonnage. Each 
scheduled scenario produces operating hours for each piece of 
equipment. By using the equipment operating hours and apply-
ing an estimated or historical equipment cost per hour through 
an economic model, scenarios are compared to evaluate the 
impacts of each on NPV. This process is used in both proposed 
and ongoing mine projects to provide justification for equip-
ment purchases and modifications to the mine plan.
Specialized Blasting Techniques
For strip (open-cast) mining, overburden must often be frag-
mented by blasting so it can be efficiently and economically 
excavated. For many years, mining engineers have consid-
ered cast blasting (explosives casting) of overburden both to 
take advantage of the explosive energy used to fragment the 
overburden and to reduce material excavation and handling 
costs (Brealey and Atkinson 1968; McDonald et al. 1983). 
The low cost and high gas pressures of ANFO explosives 
make cast blasting more attractive as a production tool. The 
advantages of cast blasting become increasingly significant 
for thick overburden with resistant layers requiring high 
powder factors (kilograms of explosives per cubic meter of 
overburden blasted)—0.65 kg/m3 is typical for some very 
strong sandstones, for example, in the United States, South 
Africa, and Australia. Applications have shown that in certain 
circumstances, cast blasting in deep overburden can be more 
economic than conventional stripping. This method, which 
is based on reducing the primary overburden removal by the 
(A)
(B)
(C)
(D)
(E)
(F)
(G)
Source: Hrebar and Atkinson 1998
Figure 4 Dragline pit sequence cross section
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 95
dragline (Figure 7), has the added advantage of promoting 
gravity segregation of the cast material. Large rock fragments 
come to rest near the pit floor to form the base of the spoils, 
thereby improving spoil drainage and stability. Figure 8 illus-
trates a typical cast blasted profile.
Presplit blasting may be used in conjunction with cast 
blasting to dewater permeable overburden and create stable 
highwalls. Additionally, in strong ground, a vertical face can be 
created in conjunction with cast blasting, rather than the irregu-
lar sloping face produced by conventional blasting (Figure 9). 
It is obvious from Figure 9B that the vertical face, with greatly 
reduced distance from the front row of blastholes to the toe 
of the highwall, will result in far more efficient cast blasting. 
However, cast blast patterns using angled blastholes (Figure 10) 
tend to produce more casting distance (projectile effect) than 
cast pattern using vertical holes (toppling effect). In cast blast-
ing, rows of blastholes parallel to the highwall are detonated 
sequentially, initiated from the highwall progressively from 
front to back, resulting in maximum overburdencast across 
the pit. Experience shows that marginally more overburden is 
Figure 5 Dragline range diagram
Cast Pro�le
Coal
Wedge
Cast-to-Final
Coal
Overburden
Figure 6 Potential coal wedge loss
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
96 SME Surface Mining Handbook
cast using this design, but a section of overburden between the 
presplit line and the last row of blastholes may remain in place 
(Figure 11). Typically, the first three front rows of a cast blast 
pattern will move the most volume of material the farthest to 
its final resting location (i.e., cast-to-final). The fourth row and 
up to the last row tend not to cast and subsequently the mate-
rial is moved by stripping equipment. Cast blast patterns are 
usually designed using a square or staggered pattern. Choosing 
which pattern to use is site specific and will need to be tested to 
determine which will achieve the lowest blasting cost and the 
greatest cast-to-final volume movement.
The geometry of the spoil after cast blasting must be con-
trolled to provide a section suitable for dragline operations 
while moving as much overburden as possible across the pit. 
The best results appear to occur with about a 30° offset using 
a staggered V pattern with relatively long, interrow delays. 
Figure 12 illustrates a typical section and the desired sec-
tion. The throw depression can be greater than desirable, and 
some minor rehandling of the thrown spoil is necessary to 
establish a bench for dragline operations. Depending on the 
type of overburden (such as mudstone, sandstone, shale, coal 
stringers, or a combination), the spacing-to-burden ratio of 
the blasting pattern should be determined using site-specific 
geologic factors and requires detailed consideration to control 
the trajectory of the thrown spoil. For example, a porous sand-
stone layered with several coal stringers will degrade the blast 
energy and not cast as well as a solid hard sandstone, which 
will yield a more efficient cast. The presence of coal stringers 
and weak layers in the overburden allows the blast energy to 
escape rather than confine the blasting gas in the borehole and 
may result in a violent blast with undesirable flyrock.
A means of evaluating the feasibility and effectiveness of 
cast blasting is the use of the linear relationship of cast volume 
to depth/width (d/w) ratio. This is a ratio varying from 0.4 to 
0.9, where d is the pit depth from the highwall crest to the bot-
tom of the lowermost seam and w is the width of the exposed 
pit bottom (toe of highwall to toe of spoils). Generally, the 
Interburden
38 m (125 ft)
Lower Coal Seam
Main Coal Seam
Prime Dragline Burden
Truck and Shovel Prestrip
Blast P
ro�le
27.5 m (90 ft)
30 m (98 ft)
11.5 m (38 ft)
 Section Width 305 m (1,000 ft)
Prime D/L Truck and Shovel Total Spoil
 822,045 358,209 463,837
Spoil Handled Once: 760,254 92%
Rehandled Once: 61,791 8%
822,045 100%
Bank Cubic Yards
Dozer Extended Bench
Courtesy of Mincom, Inc., Denver, Colorado
Figure 7 Typical pit section
Saving in Dragline
StrippingProfile After
Blast B
Profile After
Blast A
Dragline Seat
Spoil Heap
Large Fragments in
Base of Spoil Heap
New Profile
Blast B
Blast A
Source: Hrebar and Atkinson 1998
Figure 8 Blast cast profile
(A)
(B)
Source: Hrebar and Atkinson 1998
Figure 9 Blast cast profile: (A) conventional blasting profile, 
(B) presplitting profile
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 97
greater the d/w ratio value, the greater the cast-to-final volume 
into the empty pit.
A potential negative side effect of large cast blasts is the 
unintended development of ground vibration (depending on 
the size of the cast pattern), airblasts, and fumes. If the mine 
is located in a remote area this may not be a problem; how-
ever, if the mine is located near towns, inhabited dwellings, 
industrial facilities, and such, it may pose an issue. One must 
adjust several parameters to resolve such issues; for example, 
blast smaller cast patterns (which decreases efficiency), adjust 
blast-delay timing (longer delays), avoid cast blasting on 
cloudy days to reduce airblasts, or use highly water-resistant 
bulk product (to reduce fumes).
Single-Seam, Cross-Pit, Chop-Down Operation
A dragline used in the chop-down mode is about 60% efficient 
compared with the conventional drag mode. Bucket mainte-
nance costs are also higher (although this is considerably alle-
viated by the better fragmentation achieved in cast blasting). 
The depth/width ratio of the pit should exceed 0.4 for cast 
blasting to be considered (i.e., this method is best suited to 
deeper pits).
Figure 13 shows the method of operation. The dragline 
bench height in Figure 13C can be fixed so that the spoil crests 
are essentially level, virtually eliminating the need to grade 
the spoil peaks during reclamation. This advantage can only 
be fully realized, however, if the height of the dragline bench 
above the top of the seam does not exceed the optimum dig-
ging depth. Where this height exceeds the optimum digging 
depth, the bucket must be cast and dragged prior to the swing 
cycle, thereby increasing cycle times. In these circumstances, 
it is usually more economic to level the spoil peaks with either 
the dragline (rehandle) or conventional mobile equipment.
The single-seam, chop-down method may be used to strip 
seam partings in multiple-seam operations. This operation 
results in a reduction of dragline productivity of up to 50%, 
but if the ratio of parting to lower seam thickness is low, this 
approach can be an economical option.
Two-Seam Method
The steps utilizing cast blasting are illustrated in the following 
sequence (refer to Figures 4A–C, and as described previously 
in the “Mining Sequence” section):
1. The pit section prior to blasting (Figure 4A).
2. Interburden blasted into the void left after extracting the 
mineral from the previous strip. Large rocks will form the 
base of the spoil heap and are not handled by the dragline 
(Figure 4B).
3. Blasted overburden. The throw depression of the inter-
burden blast is filled by overburden spoil (Figure 4C).
This method results in an increase in dragline productivity 
above that of conventional dragline stripping, but insufficient 
experience is available in comparable conditions to quantify 
this increase. However, other marked advantages include:
• Both seams are exposed, allowing simultaneous seam 
recovery. The upper seam can be dozed over the side of 
Remains
In Situ
Presplit
Line
Last Row
of HolesProfile
Before BlastProfile
After Blast
Source: Hrebar and Atkinson 1998
Figure 11 Blasting with parallel tie-up
Angled
Drill Hole
Empty Pit
Spoils
Coal
Overburden
Figure 10 Example of a cast blast pattern profile with angled drill holes
Highwall
X-delay
Presplit
Line
Dragline Seat
Rehandle
Actual
Profile
Desired
Profile
Throw Depression
40%
60%
Percentage
Blast Over
1
2
4
6
1 2 3 4 5 6
Source: Hrebar and Atkinson 1998
Figure 12 Blasting method
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
98 SME Surface Mining Handbook
the bench (or by other suitable means) onto the lower 
seam, thereby concentrating and simplifying mineral 
loading operations and improving blending. The volume 
of in-pit exposed reserves is increased, allowing greater 
flexibility in operation.
• Spoil stability is enhanced by gravity segregation of the 
cast blast materials, with larger durable rock forming a 
base for the spoils.
• With both seams exposed simultaneously, additional drag-
line moves and dead-heading can be eliminated or reduced.
• Reduced need to handle durable rock materials with the 
dragline can result in reduced bucket maintenance costs.
This method can also be used for single-seam, thick-
overburden applications to eliminatechop-down operations 
for upper overburden benches. Where weathered material 
exists near the surface, the upper bench can be presplit with 
more closely spaced holes than for the lower, more competent 
overburden. Provided weathering is not too deep, the upper 
bench slope can be increased, up to a maximum of 90° (verti-
cal), because presplitting will limit blasting effects and reduce 
drainage concerns.
Highwall
a b c
a
d
b c
Edge of Seam
Throw Depression
Blasted Profile
Optimum Bench Height
Presplit
Line
(A)
(B)
(C)
Source: Hrebar and Atkinson 1998
Figure 13 Cross-pit, chop-down with single-seam method of 
operation
Stripping Previously Worked Deposits
In some situations, thick coal seams that have been previously 
partially extracted by underground methods (e.g., room-and-
pillar mining) can be economically recovered by strip mining. 
In these situations, stability and the safe operation of the drag-
line can be in question where conventional dragline stripping 
is proposed. Cast blasting provides an alternative stripping 
method for suspect areas where the dragline is not located 
over the pillared coal, thereby minimizing stability and drag-
line safety concerns.
Equipment Selection
The following criteria are among those that should be con-
sidered when selecting equipment for a new or expanding 
operation:
• The life of the project. Certain capital and operating 
cost considerations should be evaluated. Smaller equip-
ment (e.g., scrapers) has lower capital costs but much 
higher operating costs, depending on the haul distance 
and the unit volume moved. In comparison, draglines 
have much higher capital costs and much lower unit 
operating costs. For example, a scraper may have a capi-
tal purchase cost of $2 million, with a recurring replace-
ment cost every 5 years, a unit capacity of 23 m3, a life of 
35,000 hours, and an operating cost of $0.98/m3 varying 
with the haulage cycle. A 115-m3 dragline might have a 
capital purchase price of $50 million, an operating cost of 
$0.20/m3, and a life of 150,000 hours. It typically will last 
for the life of the project, which could be 30 years, with a 
single major rebuild costing $10 million.
• Depth and thickness of the seam(s) overburden and 
coal, with total depth to last minable seam. Typically, 
pits up to 150 m in depth can be surface mined.
• Strike and dip of the property. Is the deposit type more 
suited to area mining or contour mining?
• Comparison with similar operations. Consider similar 
operations, but do not restrict the decision by existing 
convention. In the 1980s, there were only truck and shovel 
operations in the PRB. The first dragline was introduced 
in 1982, and since then draglines have dominated U.S. 
surface mines in Wyoming, Montana, Colorado, Texas, 
and North Dakota.
• Combinations of mining methods. This may require an 
array of equipment types.
• Equipment type and size. For draglines, evaluate the 
equipment type and size by generating range diagrams 
from cross sections across the length of the reserve. 
Figure 7 (or Figure 5) illustrates a typical range diagram 
and the volume distribution. Choose typical cross sec-
tions that represent variations in the reserve. For truck 
and shovel operations, bench height and passes per cycle 
help to determine equipment matching. Three to five 
bucket passes by a shovel to fill a truck is considered a 
good match. It will be important to select equipment that 
can handle changes in pit geometry.
• Dragline capacity. Multiple-seam operations require 
handling of intermittent coal and interburden, which 
will impact the productivity of a dragline and require 
loader-truck equipment to handle the smaller seams. 
Dragline capacity must take into account such production 
interruptions.
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
 Strip Mine Planning and Design 99
• Haulage scenarios. Evaluate haulage scenarios for truck 
and shovel and scraper operations.
• Cast blasting. Look at the possibility of augmenting pro-
duction with cast blasting.
• Used draglines. Evaluate the market for used draglines 
that are currently idle. Finding a dragline that can be relo-
cated for half the cost of a new dragline may fit the mine 
plan needs.
All options should be evaluated for the highest NPV and 
IRR.
Ground Control and Pit Slope Stability
Effective ground control and planning for pit slope stabil-
ity comprise a two-step process. First, geological structures 
and groundwater conditions that may affect stability need to 
be identified and characterized. The planning process then 
focuses on the proper layout and design of the pit geometry 
and mine structures to address site-specific structural and 
groundwater conditions.
In addition to adequate exploration drilling, sampling, 
and logging to characterize geology, lithology, general struc-
ture, water levels, and reserve characteristics, seismic stud-
ies can prove invaluable in delineating structural features and 
characteristics. Groundwater studies can also provide supple-
mental information on groundwater occurrence and flows.
Proper pit layout minimizes exposure of structural uncon-
formities in the pit highwall, provides for effective drainage 
of both surface water and groundwater, and avoids geometries 
that tend to adversely concentrate ground forces (i.e., noses 
or notches). Similar considerations are appropriate for mine 
structures, including mine spoils, overburden and waste piles, 
tailings facilities, water impoundments, and mine buildings.
For pit slopes and spoil piles, as well as engineered 
structures such as tailings facilities and water impoundments, 
geotechnical analysis by qualified professionals is appropri-
ate. These analyses assess both static and dynamic (seismic) 
stability and are often required by applicable regulations. In 
the case of engineered structures, foundation testing is often 
a component of the geotechnical analysis and specific recom-
mendations for foundation preparation and drainage measures 
are incorporated into project construction plans.
MINE SAFETY
As a critical element of modern mining operations, safety 
must be a key consideration in planning all aspects of mine 
operations: layout and design of pit geometry and mine struc-
tures and facilities, road design, equipment selection, and 
operations planning and scheduling.
Applicable regulatory requirements often factor in safety 
as well as environmental considerations. However, effective 
protection of worker safety and health requires thought and 
effort well beyond the scope of regulations. For this reason, 
the planning phase should address both engineered safety con-
siderations (i.e., pit design and equipment safety features) and 
safety systems (i.e., worker training, safety awareness, equip-
ment inspection and maintenance, and health monitoring).
LAND RECLAMATION
On completion of active mining operations, whether for an 
individual mining area or for the mine as a whole, mine dis-
turbance areas should be returned to a stable condition. The 
potential for any short- or long-term adverse environmental 
effects or hazards to wildlife and human health and safety 
should be minimized, and productive postmining land use(s) 
should be supported. After completion of the initial phase 
of mine planning and prior to mine permitting, a postmin-
ing topography (PMT) of the mine is developed. A rigorous 
review of the PMT is performed by regulatory agencies where 
several rounds of revisions and amendments are normally car-
ried out prior to approval.
Once the PMT is approved and the mine has progressed 
a few years, the reclamation process of the mine can start by 
backfilling the voids with overburden using truck and shovel 
material and grading mine pit areas using dozers or scrapers 
to near the approved PMT surface. The backfilled elevation is 
controlled using a GPS survey crew or equipment fitted with 
GPS guidance system. The PMT surface shouldblend with the 
surrounding terrain to promote effective drainage.
Once the overburden material is graded to near PMT level 
(e.g., 0.6 to 0.9 m below final PMT) the overburden must be 
sampled and analyzed for pH levels and other natural occur-
ring elements. If the analysis meets acceptable limits imposed 
by the regulatory agencies, replacing stockpiled soil materi-
als (topsoil) can begin. If the overburden sample analysis is 
not satisfactory, then overburden material must be removed, 
replaced, resampled, and reanalyzed. This process is repeated 
throughout all backfilled areas.
Topsoil material for reclamation generally comes from 
two locations: stockpiles or topsoil removal ahead of the active 
pit mining. If there are no areas available to receive topsoil 
directly from pit advancement, then it needs to be stockpiled 
for later use. Topsoil stockpile slopes are graded with shal-
low sides (i.e., 3:1 slopes) to avoid erosion due to heavy rain 
runoff. Berms and ring ditches are also constructed around 
the perimeter of the stockpile to contain the topsoil and avoid 
contamination with the surrounding overburden. Seeding of a 
topsoil stockpile is required to grow vegetation and maintain 
its organic composition.
After a graded area is spread with topsoil, the topsoil 
depth and location are measured and recorded. (Generally, 
topsoil replacement depth is determined in the approved recla-
mation plan.) Once topsoil replacement depth is achieved, the 
topsoil is disked and seeded. A seed mixture that is compatible 
with native vegetation species is designated in the approved 
reclamation plan and normally targets a higher vegetation 
yield than what was originally present during premining. Once 
seeding is complete, the vegetation in the area must grow and 
thrive on its own without further human intervention (i.e., 
no fertilizers or watering). After a few growing seasons, the 
process of monitoring vegetation growth and animal popula-
tion begins: this can take several years. The reclamation of the 
postmining land conserves and attracts indigenous and nonin-
digenous animals to the area, hence promoting a sustainable 
ecosystem.
As part of the planning process, it is sometimes possible 
to enhance the natural conditions and land uses that existed 
prior to mining or to make land modifications that may facili-
tate higher and better land uses.
Effective land reclamation can minimize the potential for 
any short- or long-term liabilities and maintain or increase 
the value of mined lands. Land reclamation is important in 
promoting a positive perception of the operator and the min-
ing industry as a whole as being environmentally aware 
and responsible.
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.
100 SME Surface Mining Handbook
RECENT MAJOR CHANGES
Major changes and developments over the last few years in 
terms of strip mining can best be summarized as follows:
• Improved mine planning software on a year-to-year basis. 
Most mine planning software programs of today are com-
puter-aided design (CAD) driven with three-dimensional 
modeling and visualization. In the past, planning was 
more of a two-dimensional modeling system consisting 
of data input, black-box calculations, and results.
• Better computers to handle the graphics and calculations 
needed in mine planning software.
• Refined data acquisition using GPS survey systems, 
LiDAR laser scanners, UAV (drone) with laser or pho-
togrammetry data-acquisition system (although this pro-
duces large electronic files).
• Improved cast blast software design using a CAD system 
as well as usage of electronic detonators for precise blast 
timing as compared to pyrotechnic systems.
• GPS-controlled equipment with onboard electronic 
design plan (for draglines, shovels, dozers, drills, etc.), 
which reduces surveyor assistance.
Future Changes for the Next Generation
Major changes and developments for the next generation in 
terms of strip mining include:
• Major technological advances for mining equipment 
(GPS guidance and tracking systems)
• Introduction of fully functional autonomous/remote-
operated equipment (haul trucks, dozers, drills, blades, 
etc.)
• Quicker surveyed field-data acquisition using drones 
(field to office)
• Equipment/personnel proximity detection systems (colli-
sion avoidance)
• Equipment operator fatigue monitoring systems (eye 
detection/safety)
• Improved equipment communication systems to handle 
all equipment monitoring and data gathering
• Opposition to strip mining (coal) due to climate change
ACKNOWLEDGMENTS
The majority of this chapter is based on the excellent chapter 
by Jerry M. Nettleton and the late Ernest T. Shonts Jr., which 
appeared in SME’s Mining Engineering Handbook, 3rd edi-
tion (Darling 2011).
ABOUT THE AUTHOR
Hector Choy began his career in coal mining as a haul truck 
operator and working in the drilling and blasting crew for Teck 
Corporation at the Bullmoose Mine in British Columbia. Choy 
then attended the British Columbia Institute of Technology 
and graduated with a Technologist Certificate in Mining, fol-
lowed by a Bachelor of Science (Mining Engineering) with a 
minor in Business Finance from Montana College of Mineral 
Science and Technology in Butte, Montana. Thereafter he 
joined Shell Mining Company and worked for 3 years in 
underground coal with duties including feasibility studies, 
underground short- and long-range planning, longwall and 
continuous miner panel design, ventilation, roof control, and 
hoisting. Choy then transitioned to surface coal mining for 
Trapper Mine in Craig, Colorado, where his duties included 
haul road design and long-range dragline planning before 
he moved to Arch Resources at Black Thunder Mine near 
Gillette, Wyoming, where for 28 years he has held a number of 
significant positions including pit and engineering supervisor, 
and later, short- and long-range planning supervisor.
SUGGESTED FURTHER READING
Brealey, S.C., and Atkinson, T. 1968. Opencast mining. 
Mining Engineering 123(12):147–163.
Hrebar, M.J., and Atkinson, T. 1998. Strip mine planning and 
design. In SME Mining Engineering Handbook, 2nd ed. 
Edited by H.L. Hartman. Littleton, CO: SME.
Kennedy, B.A. 1990. Surface Mining, 2nd ed. Littleton, CO: 
SME.
Pfleider, E.P. 1972. Surface Mining. New York: SME-AIME.
REFERENCES
Bise, C.J. 2003. Mining Engineering Analysis, 2nd ed. 
Littleton, CO: SME.
Brealey, S.C., and Atkinson, T. 1968. Opencast mining. 
Mining Engineering 123(12):147–163.
Bucyrus-Erie Company. 1979. Shovel/truck. In Surface Mining 
Supervisory Training Program. South Milwaukee, WI: 
Bucyrus-Erie Company.
Cassidy, S.M. 1973. Elements of Practical Coal Mining. New 
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Caterpillar, Inc. 2018. Caterpillar Performance Handbook, 
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Chironis, N.P. 1978. Coal Age Operating Handbook of Coal 
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Darling, P.G. 2011. Mining Engineering Handbook, 3rd ed. 
Littleton, CO: SME.
Hrebar, M.J., and Atkinson, T. 1998. Strip mine planning and 
design. In SME Mining Engineering Handbook, 2nd ed. 
Edited by H.L. Hartman. Littleton, CO: SME.
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and Investment Decision Methods. Golden, CO: 
Investment Evaluations Corporation.
Copyright © 2023 Society for Mining, Metallurgy & Exploration Inc. All rights reserved.