20 AUGUST 2010 Mnng engneerng www.miningengineeringmagazine.com

P.T. Freeport Indonesia operates a mining complex located in the highlands of Papua, Indonesia. This district consists of underground and surface operations.

The East Ertsberg skarn system (EESS) is one of the major orebodies in this district. Subsurface caving of the EESS has been carried out in a systematic series of mining lifts dating back almost 30 years. Present production from the third lift deep ore zone (DOZ), has reached 80 kt/d (88,000 stpd) during 2010, with this rate sustained through 2015. The orebody was proven below the existing caving level, with the next vertical block called the deep mill level zone (DMLZ).

This article presents an overview of the DMLZ Mine based on a recent feasibility level study. The mine is being designed for a peak production rate of 29.2 Mt/a (32.2 million stpy), with 1,803 total ore draw points spread over a panel caving footprint of about 1.3 km by 375 m (0.8 miles by 1,230 ft). The present reserves for this mine total 501 Mt (552 million st). Located 1,400 to 1,800 m (4,600 to 5,900 ft) below the original surface, the DMLZ will be one

of the deepest caving operations in the world. Production is scheduled to commence in 2015.

The DMLZ is within the Ertsberg mining district in Papua, Indonesia. The Ertsberg district is operated by P.T. Freeport Indonesia (PTFI) under contract to the Republic of Indonesia. PTFI is currently

A haul truck dumps ore into a crusher

at Freeport- McMoRans

underground operations in

Papua, Indonesia.

Overview of Freeport-McMoRans proposedDMLZ Mine at Grasbergby I. Duckworth, T. Casten and M. Rakidjan

New Mine Development

I. Duckworth, and T. Casten, members SME, are senior project manager and director, underground planning, Freeport-McMoRan Copper & Gold, Phoenix, AZ. M. Rakidjan is superintendent P.T. Freeport Indonesia, Papua, Indonesia, e-mail ian_duckworth@fmi.com.

producing copper and gold ore from the Grasberg openpit (GRS) and DOZ block cave mine. The GRS is scheduled for depletion in 2015-2016. PTFI plans to replace GRS openpit production with ore from the following underground sources (Fig. 1):

DOZ block cave mine: presently producing at 80 kt/d (88,000 stpd) with closure scheduled in 2020.

Big Gossan (BGN) open stope: initial production commenced during 2010 with plans to ramp up to peak rate of 7 kt/d (7,700 stpd) in 2012.

DMLZ block cave mine: early development commenced. Production scheduled to start in 2015.

GBC block cave mine: under development and scheduled for production in 2016.

Kucing Liar (KL): future cave adjacent to the GBC.

The DMLZ block cave reserve totals 501 Mt (552 million st) at 0.89 percent copper, 0.74 g/t (0.022 oz/st) gold and 4.4 g/t (0.13 oz/st) silver. Total payable metal over the mines life is projected to be 3.8 Mt (8.4 billion lbs) of copper and 286 t (9.2 million oz) of gold. The mine is planned as a mechanized block cave operation with a peak production of 80 kt/d (88,000 stpd). Production from caving is scheduled to commence in January 2015. It will reach peak production during 2020, sustained through 2033. The mine will operate at or near 80 kt/d (88,000 stpd) for 13 years and is projected to close in 2037.

MIN_020_038.indd 20 7/20/10 10:53 AM

www.miningengineeringmagazine.com Mnng engneerng AUGUST2010 21

Previous studiesThe reserves that comprise the present DMLZ

were previously split into the mill level zone (MLZ) and the DMLZ, with the MLZ to be developed first and the DMLZ overlapping. Prefeasibility level designs for the MLZ and DMLZ were advanced during 2004-2005.

Since these original studies were issued, further exploration core drilling, updated resource calculations and redefined metal pricing resulted in revisions to the orebody block model and the projected minable footprint. As a result, the MLZ and DMLZ orebodies presented during the prefeasibility study were combined into a single entity referred to in its entirety as DMLZ. The changes involved removal of all MLZ workings and a footprint expansion on the DMLZ 2,590 m (8,500 ft) (extraction level).

The revised DMLZ will provide earlier metal release when compared to twin lifts and a higher peak tonnage and metal production rate.

Geology and hydrology The DMLZ orebody is a part of the EESS. The

EESS is a vertically continuous mineralized zone that is developed within diorite with proximal skarns along the northern margin. It is a single copper/gold diorite and sedimentary rock-hosted skarn orebody that has been subdivided into various mining volumes. The EESS was originally discovered through surface mineralization exposures, now no longer visible due to subsidence related to block caving operations.

The mining volumes have been given different names for identification/mining level purposes. The upper part of the EESS, between the 4,000 and 3,626 m (13,000 and 11,900 ft) elevations, constitutes the Gunung Bijih Timor (GBT) deposit. The GBT was mined out by the mid-1990s.

Below the GBT is the intermediate ore zone (IOZ), located between the 3,456 and 3,626 m (11,340 and 11,900 ft) elevations. This has also been mined out. The DOZ is located below the IOZ and is situated between the 3,456 and 3,125 m (11,340 and 10,250 ft) elevations. The DOZ is currently being mined from the 3,125-m (10,250-ft) level.

The DMLZ reserve is located below the DOZ, between the 3,125 and 2,590 m (10,250 and 8,500 ft) elevations hosted in both diorite (vein-style mineralization) and skarn (disseminated and vein style mineralization).

EESS mineralization continues downward from the current DMLZ reserves and is being actively explored for continuity along strike to the northwest.

A hydrologic finite element model was prepared for the DMLZ area (inclusive of DOZ). Results were computed life-of-mine for the

DMLZ. The lateral passive inflow, representing the portion of ground water than can be removed by dewatering programs, is predicted to peak at 785 L/sec (12,400 gpm) by the end of the mine life. The modeling results indicate that there will be a critical inflow increase from the present through approximately 2030, during which time dewatering drilling must be aggressively executed. Up to 29 km/a (18 miles/year) of drilling is required, starting no later than 2015.

In terms of overall quantities, depending on how effectively water can be captured off the DOZ levels following closure of that mine, then the DMLZ water handling is estimated to peak at between 946 and 1,287 L/sec (15,000 and 20,400 gpm).

Mine design General. Development operations at DMLZ

commenced in November 2008, with the start of the DMLZ rail spur leading from the AB adits.

New Mine Development

PTFIs existing and planned underground mines.

Figure 1

Future rail portals to Freeport-McMoRans underground mines.

MIN_020_038.indd 21 7/20/10 10:53 AM

22 AUGUST 2010 Mnng engneerng www.miningengineeringmagazine.com

In January 2009, work started on the DMLZ conveyor and service decline access (Fig. 2). The mine layout focuses on multiple main levels and key infrastructure installations, as indicated in the following list.

All level values are elevations above sea level.

Main mining levels and accesses Undercut level 2,605 m (8,545 ft),

extraction level 2,590 m (8,500 ft), intake level 2,565 m (8,415 ft), exhaust level 2,550 m (8,365 ft), haulage level 2,525 m (8,285 ft), DMLZ terminal 2,525 m (8,285 ft).

Internal ramp between the extraction level and the bottom of the service decline.

Other mine level access ramps.

Key infrastructure Crushing plants: truck dump on haulage

level 2,525 m (8,285 ft), transfer main conveyors 2,453 m (8,050 ft).

Main pump station 2,520 m (8,270 ft), discharge at 2,990 m (9,810 ft).

Incline conveyor No. 1 and access decline: Tail pulley 2,440 m (8,005 ft), head pulley 2,635 m (8,645 ft), length 1,355 m (4,445 ft).

Incline conveyor No. 2 and access decline: Tail pulley 2,625 m (8,610 ft) elevation, head pulley 2,820 m (9,250 ft) elevation, length 1,335 m (4,380 ft).

Incline conveyor No. 3 and access decline: Tail pulley 2,810 m (9,220 ft) elevation head pulley 3,000 m (9,845 ft) elevation - 1,440 m (4,725 ft).

Production plans are centered on a block cave mining approach, similar in many respects to current operations at PTFIs existing DOZ Mine. A departure from the DOZ operation, main 15 percent incline conveyors are planned to transport production ore up to the mill area. The DOZ, being located at mill elevation, required relatively short,

flat conveyors to transfer ore from the crushers to surface stockpiles.

The DMLZ orebody measures roughly 1,300 m (4,265 ft) in length (oriented southeast to northwest) and is between 350 and 500 m (1,150 and 1,640 ft) in width. There are 43 production panel drifts planned. Panel length between the first and last drawpoints varies from 72 m (236 ft) at the southeast end of the level, to 474 m (1,555 ft), with an average of 372 m (1,220 ft).

Orepasses are installed along the panel drifts at a maximum spacing of 170 m (557 ft). Twelve of the panels are short enough to require only a single orepass, and the

eastern two panels share an orepass. The remaining 30 panels require two passes, for a total of 72 passes in the current design. Rock breakers are planned on 1 m x 1 m (3 ft x 3 ft) aperture grizzlies located at the top of each orepass.

The DMLZ orebody is to be mined using an advance undercut method as successfully applied in the DOZ. Drawbells are drilled and blasted from the drawpoint drifts into caved material previously broken above on the undercut level (Fig. 3). Drawbells are blasted in one shot using programmable detonators. The undercut blast forms the major pillar apex. The drawbell blast forms the minor pillar apex.

Undercutting will lead drawbelling by a minimum of 15 m (49 ft) horizontally. Undercutting will typically advance beyond this minimum point but, as a general rule, should not lead drawbelling by more than three months. Exceeding this maximum creates an elevated risk of undercut recompaction.

Caving operations are planned to commence at the east side of the minable footprint, sweeping across the ore zone from east to west in a series of production blocks. The orebody has two distinct draw column height regimes, divided roughly in half along the long axis. Draw columns along the north side of the mine tend to be shorter in height, averaging approximately 245 m (804 ft) height of draw (HOD). The majority of production activity will occur in the southern half of the mine where HODs reach 526 m (1,725 ft), as indicated in Fig. 4.

DMLZ primary personnel and material access is through the AB adits, serviced from a surface rail yard using shared rail haulage infrastructure and rolling stock. Secondary access for rubber-tire equipment and service vehicles is through the conveyor access decline, which extends from the DOZ intake adits down to DMLZ. The service decline parallels the conveyor, from existing drifting down to the DMLZ crushing plant, located below the southeastern end of the mine. The service decline also provides a secondary escape route in the event that the AB adit systems are unavailable.

DMLZ Mine development schedule (coded by year).

Figure 2

MIN_020_038.indd 22 7/20/10 10:53 AM

www.miningengineeringmagazine.com Mnng engneerng AUGUST2010 23

Undercutting and drawbelling methodology.

Figure 3

Isometric view of the DMLZ reserve.

Figure 4

Geomechanical. The DMLZ will be the deepest and highest stress block cave mined in the Ertsberg district to date. Feasibility level assessment was carried out to establish key details with regard to the geomechanical aspects of the proposed operation.

Caving and fragmentation. The DMLZ is cavable. Fragmentation is predicted to be similar to the diorite sections of the existing DOZ Mine. Experience gained in the DOZ will assist in refining the DMLZ fragmentation and drawpoint hangup predictions. The DMLZ footprint has a hydraulic radius (HR) of 134 m (440 ft) and based on Laubschers method requires a footprint with a HR of 30 m (98 ft) to initiate caving and 56 m (183 ft) to sustain caving.

Cave and crack limits. The DMLZ cave and crack limits were projected at five-year intervals for the project. On the south side, these limits generally do not extend past the farthest boundary of the expected DOZ cracking (governed by prior caving above). In the other directions, the surface crack limit will expand based on the cave angles (which vary by direction) and the increased depth of the DMLZ.

Interaction with the DOZ Mine. There is a five-year overlap projected between first production in the DMLZ (2015) and final production in the DOZ (2020). Based on numerical modeling, adverse impacts to DOZ facilities are not expected within the first two years of DMLZ caving. Between years three through five, the cave progresses up and will be within 150 to 400 m (492 to 1,312 ft) of certain critical DOZ facilities and related infrastructure. Prior experience within the EESS indicates that some damage to the openings will likely result as the cave progresses up, including rockfalls and increased convergence. The modeling indicates that, during years five through seven of DMLZ caving, changes in the stress field are significant. Heavy support and rehabilitation of DOZ drifts will be required if certain openings have to be maintained.

Fixed facilities and mine layout. Permanent facilities are located at or below the DMLZ extraction level at horizontal distance greater than 150 m (492 ft) to the south of the cave boundary. This minimum distance was recommended based on geomechanical assessment.

The proposed mine layout is considered feasible for the undercut, extraction, fixed facilities and AB terminal. There are concerns associated with certain drifts located in the northern skarns, which are considered at higher risk of collapse.

Ground conditions are considered generally good to fair for all areas on the main mine levels, although further characterization drilling is required to improve confidence. Extraction panel drifts are oriented at N35E in the direction of the regional stress field and with respect to rock fabric. This orientation is consistent with the IOZ and DOZ mines.

Mining schedule and sequence. There are some concerns identified during the feasibility study that are being examined during the next phase of engineering.

Based on convergence observations in the

MIN_020_038.indd 23 7/20/10 10:53 AM

24 AUGUST 2010 Mnng engneerng www.miningengineeringmagazine.com

A 6-m- (20-ft) diameter raisebore.

DOZ Mine, the active portion of the cave width should advance at a rate of at least 80 m/a (262 ft/year). During certain periods, the DMLZ feasibility schedule does not meet this criterion. The cave front advance rate averages approximately 65 m/a (213 ft/year) for 2019 through 2025.

The undercut should be at least one drawbell in advance of drawbell completion but no more than three drawbells ahead. The DMLZ schedule meets this criterion.

The active cave width should not exceed some limit that is expected to be on the order of 400 m (1,312 ft). This cave width criterion is a function of the rock mass properties, cave geometry, depth and associated stresses based on parametric modeling and experience at other caves. It is noted that DOZ has exceeded this criterion in 2009. However, operational complications have been identified associated with the long cave front.

A linear to convex-shaped cave front should be maintained (cave shape criterion). DMLZ meets this criterion.

Rock stress. Stresses in the proposed extraction and haulage levels start at approximately 50 to 60 MPa and are predicted to increase due to mining. High stresses of 80 MPa in diorite and up to 100 MPa in skarns and limestones are expected in the 80 m (262 ft) zone in advance of the undercut, extending down to the haulage level. These stresses remain through mining on the northern fringe drifts of the extraction level. Stress results were analyzed with both elastic and Mohr-Coulomb models. Openings in diorite and skarn are expected to be serviceable but are predicted to have increased potential for bursting events when compared to the DOZ. It is felt that some of the stress effects on the northern fringe of the extraction level can be reduced by maintaining a linear cave boundary on the north.

Monitoring. Monitoring is required to assist in draw control and to understand how the stresses will be transferred in front of the cave and progress to the surface. Monitoring methods should be redundant

and include, but not be limited to, microseismic, time domain reflectometry (TDR), drift convergence, multiple-position borehole extensometers, load cells, and measurement of fragmentation distribution and drawpoint hangup frequency.

Oreflow. DMLZ crushing infrastructure is planned similar to DOZ, using twin FLSmidth FFE Minerals Inc. 54 x 77 gyratory crushers. These are to be fed by trucks operating above on the DMLZ haulage level. Ore is transported to the surface stockpile over a series of 1,829 mm (72 in.) conveyor belts totaling approximately 4 km (2.5 miles) in length. This conveyor system raises the ore 550 m (1,800 ft) vertically from the crusher discharge up to an existing conveyor near the surface.

The crusher chamber is a multi-level facility designed to accommodate crusher installation, operation and maintenance efficiently within a minimum excavated volume. Access to the crushers is by the lower extension of the internal ramp. The top level is the truck dump, crusher inlet, crane bay and control room area. An eccentric access level is 16 m (52 ft) below the dump elevation. This level not only provides access to the eccentric for maintenance and replacement, but also houses the crusher electrical bay and the hydraulic system reservoirs and cooler, as well as the crusher station transformers and high-voltage switchgear. The eccentric level initially serves as excavation access to the top of the crushed ore bin.

Ventilation and refuge. The DMLZ Mine will be developed below the existing DOZ. Much of the DOZ ventilation infrastructure will be unavailable for ventilating the DMLZ operation due to the impact of caving. However, a section of the horizontal ventilation drifting accessing the DOZ Mine can be used by connecting primary ventilation raises up from the DMLZ Mine.

For the DMLZ, the air will enter the mine through a combination of the DOZ intakes (~70 percent of the intake volume), the service decline and the AB adit spur. The primary intake system is completely open with no regulators or booster fans required. The majority of the intake air is routed down three 6-m- (20-ft) diameter raisebored shafts. This air is then transferred across the 2,565 m (8,415 ft) intake level to the main mine levels. Intake air flows through a free-splitting network to ventilation raises along the north and south fringes, leading up to the extraction and undercut levels, and down to the haulage level. Other minor splits are directed into various infrastructure and facilities areas. In all, approximately 7 km (4.3 mile) of ventilation drifting is required on the intake level. In addition, 1.6 km (1 mile) of 6-m- (20-ft-)

MIN_020_038.indd 24 7/20/10 10:53 AM

www.miningengineeringmagazine.com Mnng engneerng AUGUST2010 25

diameter raises, and approximately 400 m (1,312 ft) of 3-m- (10-ft-) diameter ventilation raises will be necessary.

All of the air exhausts the mine by the 2,550 m (8,365 ft) exhaust level, then up through five 6-m- (20-ft-) diameter smooth raises. These raises connect to the DOZ exhaust system, expanded to comprise five drifts and five parallel Howden-Australia 3.5-m- (11.5-ft-) diameter mixed-flow axial fans. All mine exhaust is through these primary fans, inclusive of the ore flow allowance. The exhaust level serves multiple functions as primary exhaust ventilation and haulage level development access. Early development of exhaust ventilation headings is critical to the development plan. One of the first development priorities was gaining access to the top and bottom of the first exhaust ventilation raise to facilitate raise excavation.

The DMLZ Mine will have two separate intake air splits for emergency egress. The first is the AB adit spur that will connect the lower mine to the portals. In the event of a fire anywhere but the actual AB tunnels, this will remain clean of smoke and serve as an intake escapeway. The second escapeway is by the service decline. In the event of a fire in the AB adits, this route will remain clear of smoke and serve as an escapeway.

Within PTFIs existing underground operations, egress is considered to be the first priority. However, since both escapeways are lengthy and would involve transportation to fully evacuate the mine, permanent refuge stations are planned at each main level, allowing all personnel from those levels to wait in safety. PTFIs standard for refuge specifies a system incorporating oxygen generation, scrubbing and refrigeration, with a rated capacity of 36 hours. In addition mine worked are required to wear oxygen generating self-contained self-rescuers.

Pumping. Water will report to the DMLZ mining area in increasing flow volumes as the mine transitions from preproduction to full production. The expanded subsidence area will increase surface collection and broaden the volume in which subterranean sources may be intercepted. The majority of the water will be collected from sources throughout the DMLZ by a series of ditches on the various mining levels that will report to a drainage pipe on the intake ventilation level. Any inflow entering the mine workings below the intake level elevation (namely the exhaust and haulage levels) is directed to a drainage level by a system of ditches and drain holes. Flows are directed through the drainage level to a sump pump station installed at the lowest point in the DMLZ.

Approximately 505 L/sec (8,000 gpm) of the DMLZ water capture will be pumped up to provide water for milling operations. The remainder will

flow by gravity out of the AB adit. The main pump station will consist of two operating banks of dirty-water pumps in parallel. In the event that a bank of pumps should go offline, the water bypasses the pump station and joins the overflow volume out the AB adits. The main pump banks each comprise five centrifugal slurry pumps in series driven by 373-kW (500-hp) motors. The first pump in each operating bank is equipped with a variable frequency drive to regulate discharge flow. This feature provides the ability to limit the number of main pump motor starts per hour.

Schedule, costs and manpowerSchedule and costs. The project schedule was

prepared using Datamines Mine 2-4D and Enhanced Production Scheduler (EPS) software. Vulcan was retained as PTFIs primary mine design tool.

The project schedule is driven primarily by excavations. Underground construction activities must wait for excavations to be completed. Construction time requirements are developed on a case-by-case basis and are entered into EPS as a hard duration.

A comprehensive coding structure was developed for the DMLZ. The full code is a 19-digit series comprised of four sub-codes, as follows:

Facility code (two places). Asset group (AG) code (four places). Work breakdown structure (WBS) code

(four places). Estimating code (nine places).

The facility code is derived from the layer names in Vulcan and allows costs to be cleanly grouped according to facility. An example would be a crusher with costs from excavation, fixed equipment, construction, EPCM, indirect and contingency grouped under one facility code. The next two codes, the AG and WBS, incorporate project and financial control coding. Applied in combination, these codes ensure that costs are forecast and tracked correctly and reported into the appropriate cost centers. The last nine digits represent the estimating code. The estimating code is divided into six sublevels based on; (1) class, (2) type, (3) description, (4) single/multi-task, (5) material and (6) ground support.

The estimate code is used to link schedule quantities with estimate productivities, unit costs and resources (manpower and equipment). An example of an estimating code would be contractor capital (level 1), lateral development (level 2), 5.5 m x 5.5 m (18 ft x 18 ft) drift (level 3), single heading (level 4), waste development (level 5) and medium ground support classification (level 6). Resources and consumables consistent with contractor crews driving a single-heading 5.5 m x 5.5 m (18 ft x 18 ft)

MIN_020_038.indd 25 7/20/10 10:53 AM

26 AUGUST 2010 Mnng engneerng www.miningengineeringmagazine.com

drift with medium ground support would then be allocated against this quantity in the cost model.

A significant effort was made to develop flexible and accurate cost models for the DMLZ. Although zero-based procedures were used almost exclusively in preparing the capital and operating portions of the estimate, components were modified, as necessary, to reflect actual PTFI key performance indicators.

Manpower. As PTFIs underground operations continue to branch out, the provision of manpower becomes an increasing commitment. Attracting, training and retaining a competent workforce for the various operations and projects is an ongoing challenge.

DMLZ manpower was estimated using ratios consistent with current DOZ direct and support staffing. Manpower is forecast to peak at 2,550 employees during the 2009-2021 preproduction and production rampup years, with a range of 1,950 to 2,400 for the full production period.

As development activities taper off, manpower drops to about 1,550 people by 2030. This number is maintained for the following few years, after which the workforce gradually drops to 750 people by the end of the mine life in 2037. A graph showing life-of-mine manpower by job category is presented in Fig. 5. The numbers are inclusive of all rotation crews, indirect manpower, vacation and sick leave, absenteeism and training.

Risk The DMLZ represents the continuation of

caving of the EESS. The caving design and peak tonnage are consistent with the present DOZ and, as such, there is considerable confidence associated with caving of the DMLZ. PTFI is one of the world leaders in block cave mine production, having successfully constructed and extracted three previous caves, all within the EESS. The operational risks are, therefore, considered to be manageable. However, insufficient data in some areas raises concerns that elevate risk profiles.

During the feasibility study, 119 risks were

identified associated with the development and operation of the proposed DMLZ Mine. Out of the highest 22 risks, 10 of these related to geomechanical concerns such as high stress, knowledge of structures, burst potential, wet drawpoints and early dilution.

A number of the risks, both geomechanical and operational, were connected with the undercutting sequence and the concern that the cave front stresses and abutment loading will result in damage, or rock conditions that impact upon development and caving schedules and costs. Recent resequencing during basic

engineering has resulted in a reduction of the effective cave width and improved confidence with this aspect of the design.

Operationally, one of the key risks is associated with the ability to handle tramp steel from old mine levels above, that can result in nuisance shutdown of the ore handling system or, in extreme cases, damage. In the DOZ, this is an ongoing issue and one worthy of further study.

Five of the higher level risks are connected with staffing, manpower, and associated housing and support facilities. It is recognized that the timely sourcing and training of sufficient personnel (at all levels) represents one of the highest risks to successful on-time completion of the DMLZ project. The combination of the remote location, coupled with multiple large projects peaking at similar times, will stretch resources.

Conclusions The DMLZ is technically and financially feasible

and PTFI has made the decision to move forward with the development of this new mine.

As with most large projects, a number of areas have been identified where additional data or further studies are necessary to improve knowledge and understand/mitigate risk. These technical studies and design work are presently ongoing in order to advance knowledge beyond the level of the feasibility study. Early development of critical openings started late 2008, and development will ramp up significantly during the next four years, peaking at about 15 km (9.3 miles) during 2013.

At this time, the first drawbell tonne is schedule for January 2015, with peak production of 80 kt/d (88,000 stpd) achieved during 2020. n

Acknowledgments The authors thank the management teams of

PTFI and Freeport-McMoRan Copper and Gold for permission to prepare and publish this paper.

References P.T. Freeport Indonesia, Jan. 2010 Deep MLZ

Mine Feasibility Study, Final Report, 482p.

DMLZ manpower by department.

Figure 5

MIN_020_038.indd 26 7/20/10 10:53 AM

MIN_020MIN_021MIN_022MIN_023MIN_024MIN_025MIN_026