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ShaftSinkingPracticesfor Mining
Chairmen: J.S. Redpath
C. Heever
].S. Redpath Ltd. North Bay Ont. Canada
Cyril Heever Partners Inc. Carletonville South Africa
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Chapter
SHAFT SINKING AT NOSE ROCK
by
Mr. James O. Greenslade
PhillipsUranium Corporation
Vice Presidentof Mining & Milling
Crownpoint,New Mexico
Mr. Cherie Tilley
PhillipsUranium Corporation
DevelopmentManager
Crownpoint,New Mexico
Mr. Gerald G. Griswold
HarrisonWestern Corporation
Vice Presidentof EngineeringServices
Denver, Colorado
Mr. Richard Reseigh
HarrisonWestern Corporation
Manager of Engineering& Administration
Crownpoint,New Mexico
INTRODUCTION
The HarrisonWestern Corporation,a leadingDenver based mine
contractingand engineeringconcern,is presentlyengaged in
sinking two 1,006 m (3,300 ft) shafts for the PhillipsUranium
Corporationat their Nose Rock Project,approximately13 miles
northeastof the small communityof Crownpointin McKinleyCounty,
New Mexico. The Nose Rock Project is the first attempt by the
PhillipsUranium Corporationto tap the deep uranium reservesin
what has become known as the Grants Mineral Belt. (See Figure 1)
ProjectDescription
PhillipsUranium Corporations plan for the large 2700 metric
ton per day (2950 tons/day)mining facilitycalls for a series of
deep access and ventilationshafts ranging from 4.27 m (14 ft) to
5.49
m
(18
ft) in diameterto approximatedepths of 1,006m (3,300
ft). The initialpair of shafts consistsof one productionshaft and
one ventilationshaft separatedby a distanceof
91 m (300
ft).
The
interbedded layers of sedimentary sandstones and shales to be
penetrated by the shafts contain several major water producing
aquifers, the deepest being the mineralized zone called the Westwater
Canyon Member of the Morrison Formation.
955
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956
1981 RETC PROCEEDINGSVOLUME 2
FIGURE 1.
PROJECT SITE
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SHAFT SINKING AT NOSE ROCK
957
A series of temporaryand permanentwater pumping stationsis
planned. Generally,the temporarystationsare located above
major aquifers to facilitatewater removalwhile sinking through
the aquiferand the permanentstationsconstitutewhat, in the
final mode, will be the mine dewateringsystem. In addition,
PhillipsUranium Corporationhas installedand is maintaininga
system of depressurizationwells that temporarilypump the major aqui-
fers and considerablyreduce the water inflows durinq shaft construc-
tion,
The major aquifers are alao chemicallygroutedprior to sinking.
Site work for the project was initiatedin the fall of 1976. Full
scale shaft sinking commencedin November of 1977 on the 4.88 m (I6
ft) diameterventilationshaft and on the 5.49 m (18 ft) production.
shaft by another contractor.
HarrisonWestern Corporationbegan work
on the project on November 4,
1979 with the productionshaft at a
depth of 633 m (2,076 ft) and the ventilationshaft at a depth of 474
m (1,554 ft).
This paper will address only the portion of shaft
sinking completedby HarrisonWestern.
Geology and Hydrology
The Nose Rock Project is located on the Chaco Slope in the
southernextreme of the San Juan Basin in northwestNew Mexico.
The southernSan Juan Basin is generallybound by the Defiance
Uplift to the west, the Zuni Uplift to the south and the
NacimientoUplift to the east.
The Grants MineralBelt occupies
most of the southernportion of the San Juan Basin and this pro-
ject is located on the northernextreme of the Grants Mineral
Belt. The San Juan Basin is comprised of sedimentary rock of
continental, marginal-marine and marine origin, that dip northward
from the Zuni Uplift and Chaco Slope into the interiorof the San
Juan Basin.
(SeeFigure 2)
Major Formations The major geologic formationsto be penetrated
range from mudstoneand shales to ailtstonesand sandstones.
The
sandstonesare highly productiveaquiferswhich, under static
conditions,would flow artesian.
Water temperaturesin the aqui-
fers are high and thereforeare a force to be dealt with. Temper-
atures range from 18C (65F)in the upper aquifersto 48C
(118F)in the lower. The mudstonesare generallybentonitic.
(SeeFigure 2)
GALLUP SANDSTONE: The Gallup Sandstoneis the first major
regressivewedge in the San Juan Basin of the Cretaceus era and
at this project is about 35 m
(115
ft) thick.
It is medium
grainedand prior to depressuriation carrieda hydrostaticwater
3
pressureof over 72.5 kg per cm (1,031psi) whi~h is artesian.
Compressivestr ngthranges from 334.7 kg per cm (4,760psi) to
421.8 kg per cm (6,OOOpsi).
Water temperatureis approximately
30c (860F).
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958
1981
RETC PROCEEDINGSVOLUME 2
C.EOLCC,C ~.w.. o. COLUMN
T-
*
M, N, F.,
MLLATO TONG.,
OF . . .
MA.cos
MC,t.lcos
812
26s
w, ,W.R w...
w..,.
,
,6 )
WCI),.OUJCTION SHAFT No,, v,r4T,.AT,ON SHAFT
,_L_EPT.
.m. . .
= :
..s.O ,
.....
.
m,,
, ,...,,
i
FIGURE 2. SHAFTSVERTICAL CROSS SECTION
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SHAFT SINKING AT NOSE ROCK
MANCOS SHALE:
The Mancos Shale comprisesthe bulk of marine
depositsin the San Juan Basin and representsdepositionin
deeper, quieter water in offshoreareas where energy levelswere
lower and finer elasticscould settle out. At Nose Rock, the
Mancos Shale is roughly 207 m (680 f~) thick. Compressive
st engths range from 188.4 kg per cm
5
(2,680 psi) to 400.7 kg per
cm (5,700psi).
It is not water bearing.
DAKOTA SANDSTONE: The Dakota Sandstoneand its corresponding
Twowellsmember is approximately98 m (322 ft) thick at Nose
Rock. The main body of the Dakota Sandstoneis a fine grained
sandstonewith the so calledTwowells sandstonetongue actually
being a siltstone. Prior to depressurization,wate~ ;: ;;yI)) ta
was under a hydrostaticpressure of 108.1kg per cm ,
also artesian.
2
Compressivest engthsrange from 386.okg per cm
(5,490psi) to 562.4 kg per cm (8,OOOPsi). Water temperatureis
approximately43C (109F).
BRUSHY BASIN SHALE: The Brushy Basin Member is the upper-most
member of the MorrisonFormationwhich marks the approximate
boundry between the Cretaceus and Jurassic eras. Locally, it is
composedof a sequenceof fine grained sandstones,siltstonesand
mudstoneswhich grade into one another,althoughdisconformities
are sometimesdistinguishable.
The mudstonesand siltstones
constitutethe greater part of the section. Overall, it is Q4 m
(143 ft) thick and some of the sandstonesare wa er bearing.
3
Compressivestr ngths range from 456.3 kg per cm (6,49o psi) to
5
954.8 kgpercm (13,580Psi).
WESTWATER CANYON MEMBER: The WestwaterCanyon Member of the
MorrisonFormationwas depositedin a continentalenvironment
during the Jurassic era and is the ore bearing sandstonefor the
Nose Rock Project. It is actually comprisedof three submembers
called Upper, Middle and Lower.
The WestwaterCanyon Member is a
classic example of an artesianaquiferwith water being recharged
from topographicallyhigher outcropson both the Zuni and Defiance
uplifts. Prior2todepressurization,the hydrostaticpressurewas
120.2 kg per cm (1,710psi). Grain sizes range from mediu~ to
coarse,and compressivestreng~hsrange from 94.9 kg Per cm
(1,350psi) to 348.7 kg per cm (4,96opsi). Note that the lower
range for compressivestrength is lower than the originalhydro-
static pressure,indicatinga possiblerunning sand conditionif
sinkingshould be attemptedin the absence of de ressurizationor
8
grouting. Water temperatureis approximately48 C (118F).
959
Depressurization Wells The Phillips Uranium Corporation has put
into operationand maintaineda series of depressurizationwells
in the area of the shafts to reduce the hydrostaticpressure in
the major aquifersin order to facilitateshaft sinking.
Six
wells were drilled through the Gallup Sandstone,four wells in the
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980 1981 RETC PROCEEDINGSVOLUME 2
Dakota Sandstone and six wells in the Westwater Canyon Member.
The casing was slotted throughout the total length of each aquifer
and the pump settings were generally just above each aquifer.
Number Months
lni.tial Residual
Formation
Wells Pumped Yield
Pressure Pressure Effect
Gallup
6 17
1080 gpm
1038
psi
135 pai 82
Dakota
4 14
1120 gpm 1537 psi
350 psi
77
Westwater
4- 6
6 1760 gpm 1711 psi 238
pSi
86
Table 1. Summary of Results of DepressurizationWells
As can be seen from the results summarizedin Table 1, the program
has been highly effective. More perspectiveconcerningresidual
formationpressurescan be gained by the followingestimates,
preparedby PhillipsUranium Corporationgeologists,of potential
inflows to both shaftswith and without the repressurization
wells.
With Without
Formation Wells Wells
Gallup 1,080 gpm
2, 307 gpm
Dakota
1, 120 gpm 2,562 gpm
Westwater 2,212 gpm
5,020 gpm
Table 2. PotentialInflowEstimates
Althoughthese potentialyields with the benefitof the wells
would by no means prohibitshaft sinking,the water inflow from
the upper
aquifers was further reduced by chemical grouting of the
formations prior to sinking.
Grouting
Carrying large volumes of water on the shaft bottom during
sinking probablypossessesthe greatestsingle detrimentto high
shaft sinking productivity.
For the most part, the system of
depressurizationwells had the effect of reducingpotentialin-
flows from the upper aquifersduring sinking to around 4,I6o
liters per minute (1,100gpm). As mentionedabove, these inflows
would not necessarilyprohibitsinking,although carryingthese
volumes of water would have the dual effect of increasingcapital
expenditurescaused by slower shaft sinking rates and increasing
future operatingexpensescaused by pumping larger quantitiesof
water over a significantportion of the mine life.
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SHAFT SINKING AT NOSE ROCK
961
From the above, it was apparent that further reduction of
potential inflows from the major aquifers would be beneficial if
the reductions could be obtained at a reasonable cost.
Owing
largely to the success of Harrison Westernts chemical grouting
program at the Gulf Mineral Resources Companys M.. Taylor Pro-
ject, it was decided to instigate a similar program at the Nose
Rock Project for the upper aquifers.
No grouting is planned for
the mineralized Westwater Canyon Member since any potential in-
flows will be fully realized during mine development.
I t should be recognizedthat the groutingprocess itself is
expensiveas it is not uncommon to spend one to two months treat-
ing 30 m (100 ft) of shaft.
In addition,initialapplicationsare
highly beneficialbut time spent attemptingto obtain a Iperfect
curtainis subjectto the law of diminishingreturns.
Theoret-
ically, the right amount could be determinedby adding the cost of
groutingto the incrementalsavingsof shaft sinkingcosts due to
grouting,and comparingthe totals to the after tax discounted
cash flow savings of incrementalmine life pumping expense.
Supposedly,if this comparisonyielded a positivenet present
value, further groutingwould be warranted.
The extreme diffi-
culty of estimatingaccuratevalues for the above parametersis
obvious and therefore,the outcome of any attempt must be viewed
with suspicion.
Grout Materials The grouting agents used at Nose Rock were
selectedprimarilyon the basis of successfuluse on other similar
projectsin the Grants Mineral Belt.
CEMENT: All of the sandstoneaquifersrequiringgrout treat-
ment were of fine enough porosityto preclude the use of suspen-
sion type groutingagents.
Cement grout was used primarilyto
stabilizethe rock mass around the concretegroutingpad and to
seal leaks where the pad joined the shaft lining.
Pumped cement grout was mixed with water in water to cement
ratios that varied from 12:1 to 1:1 by weight.
CHEMICALRESIN GROUT: A water soluble resin prepolymerwas the
primarygrouting agent used at Nose Rock. The resin is supplied
as a fine powder which readily dissolvesin water, and in the
presenceof catalystsand accelerators,forms an irreversible,
impermeablegel.
The mixture normallyhas a viscosityclose to
that of water and can thereforebe injectedinto formationsof low
porosity.
The set time or gel time is the time elapsed to form a stiff
gel after the chemicalsare mixed.
For the most part, gel times
can be predictedand controlledby varying the concentrationof
the solutionandlor the addition of a sodium silicate
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1981 RETCPROCEEDINGS VOLUME 2
accelerator.
Gel times are also a functionof temperaturewith
the relationshipbeing inverse.
Two
variations of chemical grouting agents were
used at the
Nose Rock Project.
The first type was characterizedby the resin
and caustic soda catalystbeing packagedseparately.
The second
type is packagedtogetherwith other modifications. Care in
transportationand storageof the second type must be exercisedto
preventthe reactionfrom taking place in the bags prematurely.
GroutingEquipment The equipmentselectedwas based on successful
experienceon similar projectselsewhere.
PUMPS AND MIXING TANKS: A double-actng recirculationtype
pu~p capable
3
of pumping at
345
kg per cm (4,900psi) at 8 kg per
cm (100 psi) air pressurewas used.
The pump is modeled after
the South African type grout pump.
Two mixing tanks were equipped
with air poweredmixing and agitationpaddles with one tank
elevatedabove the other.
The tanks were sized to mix the con-
tents of one 23 kg (50 lb) bag in the most dilutedmix of 129 1
(34
gal). One bag was mixed in the upper tank while a solution
was being pumped from the lower tank.
JUMBO AND DRILLS: The grout jumbos consistedof two drill
buggies which circled the shaft on a single track from a pivot in
the center of the shaft.
High speed,air powered, chain fed
rotary drills with 1.5 m (5 ft) feed were used with EX diameter
drill rod.
MISCELLANEOUSEQUIPMENT: Schedule 80 pipe of 5 cm (2 in)
diameterwas used for stand pipes.
These were coupledwith drill
through ball valves of similar diameter. Blow-outpreventers
capable of closing an EX drill rod were also used for added
safety.
GroutingProcedure Normally,one or more probe holes were drilled
into each aquifer from a safe distanceabove. The probe hole
served the dual purpose of determiningthe exact locationof the
aquiferand finding suitablestrata to pour the groutingpad.
Normally the pad was located from 6 m (20 ft) to 9 m (30 ft) above
the aquifer.
GROUT PAD: When the predetermineddepth was reached, the
excavationwas done for the grout pad. The curb or lower ring
of the shaft form was removedand the pad poured, forminga solid
concreteplug poured tight againstand keyed under the shaft
lining. The plug was designedto withstand the anticipated
grouting pressure. While the pad was curing, the jumbo was set up
and the standpipesinstalled.
Before grouting commenced,every
standpipewas tested to full groutingpressure.
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SHAFT SINKING AT NOSE ROCK
Upon completionof the above, the holes were drilled 3 m
ft) to 6 m (20 ft) and the rock mass between the pad and the
aquifer was injectedwith cement to consolidatethe mass and
leaks between the pad and the shaft lining.
963
10
seal
GROUTING:
Due to widely varying porositiesand local fractur-
ing conditions,experiencehas shown that precalculatedgrout
quantitiesfor a given aquifer are unreliable. As a result, holes
were pumped to refusal at a predeterminedpressureinstead of a
predeterminedquantity.
The groutingpressurewas determinedby
the amount of residual formationpressureto be overcomeand the
acceptabilityof the formationdue to grain size, porosity,
fracturesand other characteristics. Normally, this pressurewas
approximatelytwice the hydrostaticpressurecalculatedfrom the
surface,and many times the residualhydrostaticpressure due to
the effect of the depressurizationwells. A curtain length of
30
m (100 ft) was
the
approxi mate
maximum depth that could be grouted
from one pad.
The hole pattern was designedto interceptas many fracturesas
possiblewith the distancebetween holes at the base of the cur-
tain not exceeding 1.4 m (4.5 ft). The aquiferwas grouted from
the top down in stages of 3 m (10 ft) and all holes in the pattern
were grouted to refusalbefore deepeningthe holes to advance the
cover.
(SeeFigure 3)
Generally,75 -
90% of the potentialinflowswere sealed off
by the grout curtains.
SHAFT SINKING
For the most part, the shaft sinkingmethods used at the Nose
Rock Project can be classifiedas conventional. Methods and
techniquesemployedon any project depend, to a large extent, on
safetyand health regulationspromulgatedby appropriateregula-
tory agencies at both state and federal levels. At the federal
level, the project falls under the Federal Mine Safety and Health
Act of 1977 (PublicLaw 95-164) and is administeredby the newly
createdMine Safety and Health Administration of the Department of
Labor.
subsequent to enactment of the ~977 Act, the New Mexico
Mine Safety Code has adopted the federal standardsas their own.
In addition,the state of New Mexico periodicallydevelops
stricterstandards,mostly as a result of previousserious acci-
dents. The most importantof these to the shaft sinker is a
requirementlimitingunsupportedground in verticalshafts to 3 m
lo f ).
The two shafts are generallyscheduledto be sunk together.
The resultingplan representsthe earliestpossiblecompletion
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964
1981 RETC PROCEEDINGSVOLUME 2
VERTICMSCME
FMMATION
mri
LUG
WTER BEMINC
SANDS
I
1
I
\__ ..51,00
VERTICALCROSS SECTION
OFDRILLOLE
PLAN TYPICALDAKOTA GROUT COVER
FIGURE 3. PLAN-TYPICALDAKOTA GROUT COVER
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SHAFT SINKING AT NOSE ROCK
965
date and allows the fresh air base to be lowered when connecting
stations are reached in order to counteract the high temperatures
caused by hot water emanating from various aqui-fers.
Sinking Equipment
The permanentproductionhoist and headframeare used for
sinking the 5.5 m (I8 ft) diameterproductionshaft. The hoist is
a 1,119kw (1,500hp) double drum, double clutch unit, capable of
610 meters per minute (2,000 fpm) line speed. A temporaryhoist
and headframeare used for sinking the 4.9 m 16 ft) ventilation
shaft. The hoist is a 1,007kw (1,350hp) double drum, single
clutch unit capable of 579 meters per minute (1,900 fpm) line
speed. Hoist ropes are 38.1 mm (1.5 in) diameterand are of 18 x
7 non-rotating right lang lay construction.
Compressed alr is supplied to both shafts by seven electrically
powered rotary compressors located on the surface. A portable
concrete batching plant is used to supply concrete into transit
trucks that mix and deliver it to t e respe tive shafts. Concrete
9?
is transported underground in 2.7 m 95 ft ) buckets.
Galloway stages are suspended by four 25.4 mm 1 in) locked
coil ropes and are
used in each shaft as work platforms.
Each
Galloway consistsof four decks and weighs approximately31,070kg
(65,000lb).
The locked coil ropes serve as crossheadguides for
the counterbalancedbuckets.
The Galloway stagesare raised and
loweredby four winches that are electricallywired to operate
together,although any winch can be clutchedout by hand in order
to periodicallybalance tensionbetween the ropes. The rope speed
of the Gallowaywinches is about 2.4 meters per minute (8 fpm).
The Crydermanshaft mucker anchoredto the liningwith brackets
is used for mucking (excavationof blastedmaterial). Invented
and developedin Canada, the mucker is essentiallyan air powered
clamshellmounted on a telescopingboom.
Positioningcylinders
and the telescopingfeaturesof the boom itself allow positive
crowd at any locationon the muck pile.
The machine is controlled
by levers actuatingtwo four-wayvalves, with the left hand con-
trollingboom positionand the right hand controllingthe
clamshelland the telescopingfeatureof the boom.
Two units are
used in the larger productionshaft and a single unit in the
ventilationshaft.
In all cases, the units are suspendedon cable
winches located on the surfacewith the rail and bracketanchoring
39
ystemsal owing v rtical movement only. Muck bucket izes ran e
Y l
from 2.7 m
95 ft ) in the ventilation shaft to 3.5 m 123 ft )
in the production shaft.
Drilling is done with 28 kg 62 lb) hand-held. sinkers with a
piston diameter of 67 mm 2-5/8 in). Drills are lowered in a
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966
1981 RETCPROCEEDINGSVOLUME 2
speciallydesignedbasket containingall materialsrequired for
the operation.
The concreteforms are of all steel construction of the appro-
priate diameter with a length of 3 m 10 ft). The forms are
constructed of four vertical sections of .75 m 2.5 ft) length to
enable any multiple of .75 m 2.5 ft) pour to be made if ground
conditions are poor.
The curb ring is of blast proof construction
and contains the ring blockoutnecessaryto enable pouring the
subsequentpour below.
The top Pmatcherting laps the previous
pour and containsthe guillotinedoors that are closed after the
form is filled with concrete. The form itself is suspendedfrom
the previouspour by six hanging rods.
TypicalSinking Cycle
Due in most part to the wet conditions,the benchingmethod of
excavationis used. This techniqueprovidesa lower area for an
electricsubmersiblepump to be placed after each blast.
More-
over, the blowovernprocess of cleaningthe bench in preparation
for drillingallows a thoroughexaminationfor misfires and the
rock mass thrown by the blast is directed at the shaft walls
instead of the Galloway, thus minimizing damage.
The cycle describedbelow may vary in duration from as little
as 14 hours to as much as 34 hours, dependingon conditions.
Sinking rates for both shafts are comparable. The larger produc-
tion shaft has an advantagewith the additionalCrydermanmucker,
but this seems to be offset by the lesser volume of muck and a
somewhatfaster concretecycle in the ventilationshaft.
Drill and Blast This segment of the cycle begins with a thorough
blow over of loose muck into the sump created by the preceding
bench. Forty to fifty 2.4 m (8 ft) holes are drilled and charged
with a semigelatindynamite.
The dynamiteselected is a reason-
able compromisebetween the desired characteristicsof adequate
strength,low fumes, good water resistanceand cost. A non-
electricdelay blastingcap systemhas been used for detonating
explosiveswith reasonablesuccess. The crews remain on the
surface for a few minutes while the smoke clears.
(SeeFigure 4)
Mucking,
The Cryderman mucker s) are lowered and mucking begins.
Normally, the bucket chains remain attached to the hoist hook and
swivel during loading.
Since the boom llft (not in or out) opera-
tion is the most time consuming,Crydermanoperatorssoon learn to
excavatea hole for the next bucket which tends to save time.
While the loaded bucket is hoisted and dumped, the Cryderman
operator(s)can move muck from hard to reach to convenientplaces
which also conservestime. Buckets are dumped with a lazy chain
controlledby a toplanderfrom the crowqsnestn in the
headframe.
(See Figure 5)
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SHAFT SINKING AT NOSE ROCK
967
FIGURE 4. DRILLINGTHE BENCH
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9 8
98 RET PRO EEDINGS VOLUME 2
FIGURE 5 MUCKING
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970
1981
RETC PROCEEDINGSVOLUME 2
FIGURE 6. SETTING CONCRETEFORMS
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SHAFT SINKING AT NOSE ROCK
971
that attaches the weep pipe to the form. After the curb ring is
lowered, the pipes are attached to the form with a fastening
device that threads into the couplingand allows the water to come
throughthe form.
The curb ring is then filled with concrete
forming a tight seal for the bottom of the pour. After the
remainingform is loweredand poured, the water flows freely
through the weep pipes.
These are later connectedto a 10.2 mm
(4) drain line which carries the water into a pump station or a
super water ring discussedfurtherbelow.
Super Water Rings The in-shaft pumping system consisted of 43 kw
58 hp) submersible pumps on the bottom and staged up the shaft
wall in distancesnot exceeding
61 m (200
ft). The electric
submersiblepumps of this type require frequentmaintenanceand
normally this must be done on the surface.
To facilitatepump
changeoutand providea sump for staged pumps, HarrisonWestern
engineersdevelopedthe fsuperwater ring.
Essentially,the
super water ring is the enlargementof a 3 m (10 ft) vertical
section of the shaft by .6 m (2 ft) in radiuswith a .6 m (2 ft)
steel dam installedflush with the shaft lining.
Submersible
pumps in these rings eventuallytransferwater to temporaryor
permanentpumping stations.
FiberglassWater Rings The purpose of the fiberglasswater ring
is to collect water running on the inside of the shaft lining.
The rings are installedabove pump stations,super water rings or
periodicallywhen needed,and are connectedwith hose or piping to
the drain line, super water ring or station. They are fabricated
to attach to the concreteform and are easily installed.
Bonus and Incentives
In
recent years, industrial managers have gravitated towards
the theories of motivation espoused by such management theorists
as Fredrick Herzburg et al.
These theories stress job
enrichment or other such enlargementof an individualstask or
area of responsibilityas a motivatingforce in order to otherwise
offset the boredom and dissatisfactionthat often accompaniesthe
modern industrialwork setting.
For the most part, these theorists would deny that additional
remuneration is a motivating factor per se, although admitting
that substandard pay scales can be a source of considerabledis-
satisfactionamoung a work force.
Undergroundconstructionand
mining in the Rocky Mountainsand in a large portion of Canada are
some of the last bastionsof the piece work system still existing
in North America, albeit in modified form.
Seeminglyin defianceof modern managementtheory, the Nose
Rock Projecthas successfullyapplied two forms of bonus
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972
1981 RETC PROCEEDINGSVOLUME 2
incentivesaffectingall contractorpersonnelon the project. The
first is a direct bonus which is paid only to those working below
the shaft collar.
This bonus is basicallya piece rate system
applied to the crew as a whole with a guaranteedminimum base rate
for each man.
The second form of bonus is paid to all others not
receivingthe first and is based on a review of the overall pro-
ject status comparedwith the originalproject schedule. This
bonus is paid (if earned) every calendarquarter as a percentage
of the base wage rate.
Sinking Rates Attained
Shaft sinking rates of 3 meters per day (10 ft per day) were
regularlyattained,even throughmost major aquifers,and rates of
30 meters per week (100 ft per week) were regularlyattained
throughmuch of the Mancos shale.
The productionshaft crew
achievedan area record of 36.3 meters (119 ft) of completedshaft
in one week of seven days.
The ventilationshaft crew achieveda
one month productionof 132.6meters (435 ft) of completedshaft,
also believed to be an area record.
PUMPING SYSTEM - TEMPORARYAND PERMANENT
Dependablepumping systemsare an absolutenecessityto the
constructionand operationof a mine such as this one with the
shafts penetratingfive major aquifersand the ore itselfhaving
been depositedin the matrix of the fifth, the Westwater Canyon
Member.
Extensiveplanningwas requiredby both the Phillips
Uranium Corporationand HarrisonWestern Corporationto insure
that the systemwas reliable for sinking,mine developmentand
later for ore extraction.
The two permanentpump stationsrepre-
sent the system requirementfor mine developmentand ore extrac-
tion. Unfortunately,this system is not entirelyadequate for
sinking the shafts and as a result, the permanentsystem was
augmentedby a series of temporarypumping stationsfor sinking.
Of prime considerationwhen locatingpumping stationsis the
capabilityof the equipmentitself and the selectionof suitable
strata in which to locate the station.
The sandstonesto be mined
can be expectedto yield a certain amount of sand particulateto
the dischargewater and even with the benefit of a desanding
facility,the pumps must be able to pump water containingsand
particulate.
For this reason and the fact that desandingequip-
ment is not availablefor sinking,less efficientslurry type
centrifugalpumps were selected.
These pumps enjoy wide popu-
larity at other mines in the Grants Mineral Belt, mainly for their
ability to pump water containingabrasivesolids over long periods
of time with low maintenancecosts.
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Permanent Pump Stations
SHAFT SINKING AT NOSE ROCK
973
The two permanent pump stations at the Nose Rook Project were
des@ned for a sustained pumping capability of Z2,700 liters per
minute, 6OOO gpm) with an additional11,350liters per minute
(3,000
gpm
backup.
These stationsconsist of three banks of five
pumps per bank with each bank being capable of pumping 11,350
liters per minute (3,000 gpm). Provisionswere made in each
station to install a fourth bank of equal capacitysometime in the
future,should conditionsdictate.
The primary pumps of each bank are 313 kw (500 hp) electrically
powered,direct driven centrifugalslurry pumps, each capable of
11,350
liters per minute (3,000gpm) at a total dischargehead of
137 meters (450 ft]. These pumps are connectedin series to
attain the desired system head and in all cases are force fed with
high volume, low head feed pumps, to minimize the effects of
cavitation. The last pump of each bank is equippedwith a fluid
couplingwhich, in conjunctionwith electricmetering and feed
back of sump water levels, can automaticallyregulateoutput to
allow continuousoperationat levelsas low as 6,o5o liters per
minute (1,600gpm).
The upper permanentpump station is located 457 meters (1,500
ft) below the surface.
Each bank of pumps on this station con-
sists of three main pumps connectedin series and force fed by two
feed pumps, also connectedin series. The lower permanentpump
station is located at 957 meters (3,140 ft) below the surface and
when completedwill dischargeinto sumps on the upper station.
The typical bank on the lower station consistsof four main pumps
in series force fed by a verticalcentrifugalpump which will be
located in a sump on the haulage level 23 meters (75 ft) below.
TemporaryPump Stations
Temporarypump stationsare normallylocated above major
aquifersin order to minimize the less reliablein-shaftsuper
water ring system describedearlier.
These stationsare equipped
with either the primarypumps describedearlier or a smaller
version capable of 7,570 liters per minute (2,000 gpm) at a total
dischargehead of 98 meters (320 ft). The maximum lift for a
temporarystationwas 305 meters (1000 ft).
Five temporarypump stationswere used for shaft sinkingat the
Nose Rock Project. These stationseither dischargedinto higher
temporarystationsor permanentstations. As permanentstations
were completedand became available,they were incorporatedinto
the system.
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974
1981 RETCPROCEEDINGSVOLUME 2
CONCLUSION
The Nose Rock Project is currentlyrunning approximatelythree
months ahead of schedule. Althoughno methods or techniqueshave
been used that could be classifiedas unconventional,through a
combinationof experiencedmanagement,proven water control
techniques,well structuredbonus incentiveplans, and a positive
overall relationshipbetween owner and contractor,record sinking
rates have been attained.
When completed,the Nose Rock Project will unlock for public
use a considerableamount of uraniumore from deep underground.
Combinedmanagmentand technicalachievementsof both Phillips
Uranium Corporationand HarrisonWestern Corporationare
responsiblefor this success.
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SHAFT SINKING AT NOSE ROCK
975
REFERENCES
chenowith, W.L. , 1977,
tUraniumin the San Juan Basin - An
Overview,WNew Mexico GeologicalSociety Guidebook,28th Field
Conference,San Juan Basin III, pp. 257-262.
Greenslade, W.M., Sprouls, E.P., 1977, Geotechnical and
Hydrologic Investigation, Production Shaft, Mining Unit 1,
Nose Rock Project, Dames and Moore, Phoenix, Arizona.
Griswold,G.G.,
White, L.G., 1980,tWaterControlDuring Shaft
Sinking UtilizingDepressuringWells and Resin Grouting
Techniques,nHarrisonWestern Corporation,Denver, Colorado.
Kelly, T.E.,
1977,
W3eohydrology of the WeStWaterCanYon Member~
MorrisonFormation,of the SouthernSan Juan Basin, New
Mexico,nNew Mexico GeologicalSociety Guidebook,28th Field
Conference,San Juan Basin III, pp. 285-290.
Molenaar, C.M., Y3tratigraphy and Depositional History of Upper
Cretaceus Rocks of the San Juan Basin Area New Mexico and
Colorado, with a Note on Economic Resources,n New Mexico
Geoloj@cal Society Guidebook, 28th Field Conference, San Juan
Basin IIILPP 159-166.
Vanderwoude, M.D., 1980,
Mine Geologist,PhillipsUranium
Corporation,Private Communication.