AD-A090 521 COLO REGIONS RESEARCH ANDNENGINE ERIN4GILAB MHANOVER NH F/6 13/2SNOW PAuIS USED FOR PIPEL INE CONSTRUCTION INALASKA. 1976. CONST--ETC(U)JUL AD P R JOHNSON, C M COLLINS

UNCLASSIFIED CRREL-01 ALDmEEE~EF A An u u n u n u u n uu uuRE

LEVELp!"" E PORT 80-17

Snow pads used for pipeline constructionin Alaska, 1976Construction, use and breakup

" DTICF- L F-C

ON ST ELECT E

Approy'd for puublc release;

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I-IJI• .L.

LZI

For conversion of SI metric units to U.S./Britishcustomary units of measurement consult ASTMStandard E380, Metric Practice Guide, publishedby the American Society for Testing and Materi-als, 1916 Race St., Philadelphia, Pa. 19103.

Cover: Aerial view of the Alyeska Pipeline con-I i structed from a gravel pad (foreground)

and from a snow pad. (Photograph byJohn Zarling.)

I

., I

-

CRREL Report 80-17

Snow pads used for pipeline construction

in Alaska, 1976Construction, use and breakup

Philip R. Johnson and Charles M. Collins

-r.

July 1980 " " "

C

Prepared for

DIRECTORATE OF MILITARY PROGRAMS

OFFICE OF THE CHIEF OF ENGINEERS

' t,

- UNITED STATES ARMYCORPS Of ENGINEERSCOLD REGIONS RESEARCH AND ENGINEERING LABORATORY

21*uIpn e n u S. n Ic i d I . ..hII II n- unl - IId

TITLEOR DOUMNATO PAGEe) -____~ . YEO REPOR PERCIOD COVERE

(~EFR (OPETK FORMDSSD OR

onstruction, Use and Breakup S . PERFORMING ORG. REPORT HUMBER

7. Au~oR~s)S. CONTRACT OR GRANT NUMBER(e)

Philip R./Johnson amdCharles M. Collins.

3. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGVA ME MENT PROJECT, TASKARE A rWKUITN3NMR

U.S. Army Cold Regions Research and Engineering Laboratow- DA PrRc57675T2Hanover, New Hampshire 03755 TaAl ojejA IOAT4 2

11. CONTROLLING OFFICE NAME AND ADDRESS .-. E!O TfTDirectorate of Military Programs j(I JuWlg 'ZOffice, Chief of Engineers '9rUIIt1"AEWashington, D.C. 20314 A~ ~34

tO.MONTORNGAGENCY NAME & ADDI.E54

different from Controind Office) I5. SECURITY CLASS. (of ths report)

Unclassified

'- S-. DECLASSIFICAFi-oN/DOW-NGRADING

16. DISTRIBUTION STATEMENT (of this Repor)~~.~

Approved for public release; distribution unlimited.

17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20. If different from Report)

III. SUPPLEMENTARY NOTES

* 19. KEY WORDS (Continue on revere side If necessary mnd identify by block numnber)

Alaska Snow*Cold regions construction Snow padsjPipeline construction Surface travel* Roads

26, ABSTRACT (Cm te uveuue shl N nemimmy sad Ident ify by block numtber)

-0 Construction pads made of snow were used to build two sections of the Trans Alaska Pipeline and a small gaspipeline during the winter of 1975-76. Construction during the winter has become increasingly common in the

* *1 Arctic. Surface travel and the use of heavy construction equipment on the unprotected tundra have been severelyA restricted, even during the winter, so the use of temporary winter roads and construction pads built of snow and ice

has been advocated and is being adopted. The three snow construction pads mentioned above were the first snowroads and construction pads used on a large scale in Alaska. Snow roads and construction pads have two objectives:to protect the underlying vegetation and upper layers of the ground, and to provide a hard, smooth surface for

DD r, IM E1)3 ONya OF I NOV 65 IS OSOLETE Ucasfe

if SECURITY CLASSFICATIoN OF THIS PAGE (Uben Da 6%4%-Qd

UnclassdfiedSECURITY CLA-IICATIO

N OF THIS PAG.09(fte D81 En0O..,

20. Abstract (cont'd)

2> travel and the operation of equipment. Several types have been built, and a brief discussion is given of their historyand classification systems. The three snow construction pads used in construction of the Trans-Alaska Pipeline andthe small gas pipeline in 1975-76 were visited and observed while in use

The Globe Creek snow pad, about 50 miles north of Fairbanks, was built primarily of manufactured snow hauledto the site and watered. With very high densities this pad withstood heavy traffic and use by heavy constructionequipment except on one steep slope. There, the use of tracked vehicles and vehicles without front wheel

drive disaggregated the snow on and near the surface so that vehicles without front wheel drive were unable to climbthe hill. The Toolik snow pad, just north of the Brooks Range, was built of compacted snow and proved capable of

supporting the heaviest traffic and construction equipment. The fuel gasline snow pad ran from the northern

Brooks Range to the Arctic Coast and also proved capable of supporting the necessary traffic. Both the Tooliksnow pad and the fuel gasline snow pad failed in very early May because of unseasonably warm and clear weatherbefore the associated construction projects were completed. However, the three snow pads must be consideredsuccessful. Common problems were the lack of snow, slopes, unseasonably warm spring weather, and inexperienceon .the part of contractors and construction personnel.

.1 .

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Unclassified: I¢ SECuRITY CLASSIFICATION OF THIS PAOEr(Wen Dae Rnterd)

PREFACE

This report was prepared by Philip R. Johnson, Research Civil Engineer, and

Charles M. Collins, Physical Scientist, of the Alaskan Projects Office, U.S. Army

Cold Regions Research and Engineering Laboratory.

This project was funded under DA Project 4A762730AT42, Design, Construc-

tion and Operations Technology; Task Area Al, Ice and Snow Technology; Work

Unit 006, Expedient Snow Roads and Landing Fields.

The authors express their appreciation to the staff of Alyeska Pipeline Service

Company, who allowed them to observe the snow construction pads during their

construction, use and decay. They also acknowledge the assistance of the staff of

the Alaska Pipeline Office, U.S. Department of Interior, for their support and

assistance during these studies: they are particularly indebted to Rudy Berus and

Arthur Olien, who served jointly as Alaska Pipeline Office representatives on the

North Slope.

E.S. Clarke of Clarke Engineering Co., Fairbanks, Alaska, and C. Abele and F.E.

Crory of CRREL reviewed the technical content of this report.

The contents of this report are not to be used for advertising or promotional

purposes. Citation of brand names does not constitute an official endorsement or

approval of the use of such commercial products.

AccesSO For

NTIS (0FRA&IPTIC TAB L

UnIAva i .tlit y C ods

-. apd/or'D i t PecII

iii

CONTENTSPage

Abstract .... .................. i

Preface ......... iiiIntroduction 1History of snow and ice roads 1Classification of snow and ice roads 2Snow pads used by Alyeska during the winter of 1975-1976 ....... 4

The Globe Creek snow pad 4The Toolik snow pad 11The gasline snow pad .... .. 13

Summary and conclusions ... 28Literature cited .... 28

ILLUSTRATIONS

Figure1 Aerial view of Globe Creek snow pad looking south .. . 62 View of the Globe Creek snow pad looking downslope toward the

north 63 Globe Creek snow pad core .......... 74 Another Globe Creek snow pad core .... 75. Pickup driving up 11% slope on the Globe Creek snow pad .. 86. Caterpillar tractor cleats breaking up the upper surface of the

Globe Creek snow pad ...... 87 Truck being towed up 17% grade on the Globe Creek snow pad.. 98. Completed Globe Creek pipeline and deteriorating snow pad,

April 1976 .. . ........ 109. Globe Creek snow pad has melted through, showing scrub spruce

processed by Hydro-Axe 1010. Initial steep slope at Globe Creek during breakup .............. 1112 Heavy drill rig on the Toolik snow pad and the snowfence used to

collect snow ..... 1212. Pipeline vertical support members installed on the Toolik snow

pad ..... . .1 . 1213. Galbraith Airport temperatures, April-May 1976 ............. 13

J 14. Looking north to the Toolik snow pad during spring breakup .... 1415. Closeup of the south end of the Toolik snow pad as the packed

snow turned to slush, 1 M ay 1976 ... ................ 1416. View of the north end of the Toolik snow pad, 1 May 1976 ....... 1517. Final stages of the disappearance of the north end of the Toolik

snow pad showing where tractor grousers contacted tussockV tops ......... 15

18. Snow trap formed in a roadside drift near Galbraith Lake ........ 1619. Spreading the collected snow to form the fuel gasline snow pad.. 1620. Dragging the gasline snow pad with a timber drag ..... .... 1721. Dragging the gasline snow pad with a blade on a ski-mounted

frame 1722. Smoothing, packing, and leveling the gasline pad 1823. Stringing the pipe on the gasline snow pad ....... 1924. Gasline pad crossing a drainage area .. .... 20

iv

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Figure Page25. Truck loaded with pipe cutting into the snow pad on a moderate

u p g ra d e ... ...... ................................ . 2026. Disaggregated snow pad surface where loaded conventional

trucks encountered a moderate upgrade .................... 2127. Trenching from the snow pad using 3 Roc Saw ................. 2128. Drilling and blasting for the gasline trench from the snow pad .... 2229. Trenching with a backhoe after drilling and blasting .......... 2230. Dumping backfill material for the gasline trench on the snow pad. 2331. Gasline trench partially backfilled by blading in the gravel .... 2332. Final backfilling of the gasline trench after placement of the insu-

la t io n ................. ........................... . 2 433. Backfilling the gasline trench from the road with a clam shell. 2434. Backfilling the gasline trench from the road with a conveyor ..... 2535. Debris on the gasline snow pad .................. ..... 2536. Cleaning the gasline snow pad with a Gradall ................. 2637. Completed gasline .......... ......................... . 2638. Closeup of completed gasline ........................... 2739. Another view of the completed gasline ............ ...... 27

TABLES

Table1. Alyeska snow work pad design criteria .......... . .. . 32. Density profiles of Globe Creek snow cores ......... ...... . 53. Ram hardness of gasline snow pad near the Galbraith Camp

e n tra nce ....... . . ... ......... 18

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SNOW PADS USED FOR PIPELINECONSTRUCTION IN ALASKA, 1976Construction, Use and Breakup

Philip R. Johnson and Charles M. Collins

INTRODUCTION snow pads on the underlying vegetation and per-mafrost are reported in Brown and Berg (1980).

It is well known that standard wheeled ortracked heavy equipment operating on the arc-tic tundra damages the vegetative layer in many HISTORY OF SNOW AND ICE ROADScases. This damage increases the depth of sum-mer thaw and may lead to melting of interstitial Man has recognized the advantage of a pack-ice and segregated ice such as ice lenses and ed trail since he first began to walk in and on thewedges. This, in turn, leads to subsidence of the snow. Packed trails are still used today by cross-surface and may lead to water erosion. Currently country skiers and snow machine drivers.cross-tundra travel is severely restricted during Deliberate packing on a larger scale was athe summer on the Alaska arctic tundra. feature of colonial days when horse-drawn

j In the winter, special types of equipment such rollers and drags were used to pack roads andas the Rolligon are allowed to travel across the trails. Packing also became a standard practicesnow-covered tundra after the active layer is in coping with snow on northern airfields in thepartly or entirely frozen, but most other wheeled early days of aviation and continues in use to-and tracked equipment can operate only if the day.tundra vegetation is protected. Snow and ice A new type of snow travel, requiring more in-roads and pads are becoming fairly common tensive road and airfield preparation, was atypes of protective systems. Alyeska Pipeline feature of the installation of large radar units onService Company first used three separate snow the Greenland Ice Cap in the early 1950's.pads for construction during the winter of Engineering and scientific studies were carried1975-76, and the authors were allowed to ex- out and special equipment and techniques wereamine these pads and observe their behavior, developed to obtain the relatively deep packing

This report is primarily confined to the engin- and strong surfaces required for heavier equip-eering aspects of the snow pads: their construc- ment and aircraft. This work was continued andtion, their ability to support traffic and equip- expanded with the development of research pro-ment, and their breakup in the spring. Studies of grams in the Antarctic in the 1960's. The prin-the impact or lack of impact of the North Slope cipal research organizations concerned were the

f '1-- -•.---. . -- m"

E IF ... - - -no,-- .

U.S. Army Cold Regions Research and Engineer- During the winter of 1975-76, Alyeska used

ing Laboratory (CRREL) and the U.S. Naval Civil snow pads to construct two sections of the large,

Engineering Laboratory (NCEL). The literature 48-in.-diameter pipeline at Globe Creek and

based on this work is too extensive to review Toolik, and another snow pad to construct ahere but Abele et al. (1968) provide an excellent small natural gas pipeline from Prudhoe south to

summary. Pump Station 4 (Keyes 1977).

The concept of using snow and ice roads fortemporary travelling surfaces which protect theunderlying vegetation and permafrost devel- CLASSIFICATION OF SNOW

oped in the late 1960's and early 1970's. Scars AND ICE ROADSresulting from earlier activity in Naval Petro-leum Reserve No. 4 (NPR4) in northwestern A great deal of confusion exists in the termin-

Alaska (Hok 1969) and the development of heat ology used in describing winter roads, trails and

transfer studies (Lachenbruch 1959) indicated pads in the north. In part, this is because many of

the need to maintain the insulation value of the the methods and materials used are new, the

tundra. A study by Knight (1969) demonstrated work is widely scattered, and standard tech-

that heavy tracked and rubber-tired construction niques have not yet been developed.

equipment could be successfully operated on a Adam (1978) defined winter roads and trails on

pad of compacted snow. the basis of the type of material and construc-

During mobilization for construction of the tion used.

Trans-Alaska Pipeline, the "Hickel Highway," a A winter road is any type of road built of snow,

winter trail from Livengood to the North Slope, ice, or a mixture that remains functional during

was built in the winters of 1968-69 and 1969-70. the winter season.

Crossing the Yukon River on an ice bridge at Ste- 1. The winter trail is established by a single

vens Village, this winter road proceeded north- pass of a wheeled or tracked vehicle using a

ward through Bettles and Anaktuvuk Pass to blade if necessary to gain access and can be sea-

Toolik junction. From this point north of the sonal or perennial.

Brooks Range, two winter trails proceeded, one 2. The snow road can be built of compacted

eastward to Toolik and one north and then east snow or processed snow, or ice-capped.

to Sagwon in the Sagavanirktok River Valley. In 3. Ice roads consist of solid ice, aggregate ice,

addition, Alyeska built 90 km (56 miles) of the winter roads on frozen lakes or rivers, and ice

Haul Road from a point on the existing Alaska bridges.

road system near Livengood to the Yukon River. The Alyeska Pipeline Service Company devel-

When Congressional approval of pipeline con- oped a performance classification defining five

struction was given, Alyeska again used much of types of snow pads for pipeline construction.

this road system for mobilization of equipment Types I-IV are for handling traffic of increasingand construction crews during 1974-1975. The weight and impact on the pad. Type I would

Haul Road segment to the Yukon River was used, carry low-ground-pressure equipment while

together with ice crossings on the river during Type IV would carry concentrated construction

the winter, and a ferry system during the summer equipment. Type V is a steep slope snow pad

at the bridge site. A winter trail north to Old Man that requires special design. The minimum snow

I connected with the "Hickel Highway" and the thicknesses, densities and ram hardnesses for

northern portions of this trail were again used. Types I-IV are specified and construction pro-

This trail system was invaluable for mobilizing cedures have been developed. The Alyeska

to build camps and for bringing in equipment Snow Work Pad Design Criteria chart, in part, isand supplies to build the Haul Road. Once the given in Table 1.

Haul Road was built, construction began on the The Adam and Alyeska snow road and pad

pipeline, pump stations and other permanent classification systems are complementary.

facilities. Adam provides a descriptive classification based

In addition to the winter trails, Alyeska built a on the type of material and construction used.

snow runway during the winter of 1974-75 at Alyeska provides a set of engineering re-

* Coldfoot Camp that was used successfully by quirements and then describes how these can be

Hercules C-130 and executive jet-type aircraft. met using specified quantities of materials and

2

Llf

Table 1. Alyeska snow work pad design criteria.

Minimum snow thicknessType For equipment at density Construction procedure

I Low ground pressure 3 in. at 32 Ib/ft' Following refreeze of the active layer to 1 ft andRolligons (0.51 g8cm') accumulation of 6 in. of 18 lb/ft' snow, construc-Nodwells tion can begin. Rolligons and Nodwells will notCrawler tractors require any trail preparation except clearing.

Sleds Periodic use of a drag or roller will increase4WD trucks with wide travel speed of Nodwells and Rolligons, remove

tires ruts and create a surface suitable for occasionaltraffic with four-wheel drive trucks with widetires.

1I Light equipment 3 in. at 38 lb/ft' Treatment as above plus 8 passes with crawler-Pickups (0.61 g/cml) type tractors and drags or vibrating rollers with 1Light trucks with axle week of sintering at 15*F, or 2 passes with drags

loadings less than or vibrating rollers with 2 weeks of age hardening8,000 lb at 150F, or 2 passes with crawler-type tractors

and drags or vibrating rollers with addition ofwater and refreezing for immediate use.

III Heavy trucks to axle load- 6 in. at 44 lb/ft ' Treatments as above plus an additional snow ac-ings of 20,000 lb (0.70 g/cm') cumulation of 6 in. Additional compaction until

the upper range of density is achieved, or addi-tion of water until a ram hardness of 600-1.000 isreached.

IV Concentrated construction 12 in. at 50 lb/ft ' Treatment as above plus an additional snow ac-Trucks with axle load- (0.80 g/cmI ) cumulation of 1 ft. and addition of water to satu-

ings above 20,000 lb rate the upper 1 ft of snow.Locked-track turning of

tracked vehicles

V Steep slope construction Special design required.Longitudinal slopes ex-

ceeding 15% for dis-tances greater than200 ft.

Transverse slopes ex-ceeding 5%.

procedures for processing them. An urgent need packed snow. Further, the water increases the

, exists for development of a comprehensive density and reduces the porosity of the snow. Ifnomenclature for winter roads, trails and con- repeated light applications of water are made,struction pads built of ice and snow perhaps an ice cap that makes a strong wear-resistant sur-based on Adam's system but expanded. The face can be formed.

sj Alyeska engineering specifications need to be Methods of testing snow pads generally con-

evaluated in terms of performance. sist of ram hardnesses and density measure-Water applied to a snow pad or road during ments. Ram hardnesses of snow are obtained

freezing conditions serves several functions. If with a Rammsonde Cone Penetrometer (Ueda etnot applied in excessive quantities, it is generally al. 1975). Ram hardness values can be corre-retained in the upper part of the snow pad in the lated, to some extent, with compressive strengthareas of inter-grain contact. Upon freezing, it (Abele 1963) and can be used to determine thegreatly increases the strength of the inter-grain load supporting capability of the snow (Abele etbonds and thus the strength and hardness of the al. 1968). The Rammsonde Penetrometer, using asnow. Such bonds form very rapidly compared 600 cone, was originally designed for naturalwith the rather slow hardening of unwetted snow with ram hardnesses up to 200. A 300 cone

3

for use in processed, age-hardened snow was de- quirements for water haulage or storage. Theveloped and evaluated (Niedringhaus 1965), and snow can be hauled without special care but haul-has proved to be useful in measuring snow with ing water is difficult in severely cold weather. Inram hardnesses up to 1000. addition, although Alyeska had the dump trucks

Density samples for this study were obtained to haul snow, they were not equipped to haulwith a CRREL 3-in. ice coring auger. Samples large quantities of water in insulated, and

were divided into sections; they were then meas- perhaps heated, tankers. Thus, Alyeska seems toured and weighed, and their densities calculated. have made a wise decision to manufacture snow

at the Chatanika River, particularly sincetimeliness was probably more important than

SNOW PADS USED BY ALYESKA economy.DURING THE WINTER OF 1975-1976 Snow was manufactured using a commercial

snow maker and water pumped from the Chatan-The Globe Creek snow pad ika River. A front-end loader stockpiled the new-

About 50 miles north of Fairbanks the Trans- ly made snow and loaded it into dump trucks forAlaska Pipeline crosses Globe Creek and, pro- the trip to Globe Creek. The stockpiling, loading,ceeding south, climbs a moderately steep slope and unloading of the snow helped to pack it and

to reach the top of a ridge. Exploratory drilling speed the age-hardening process.

showed that the lower part of this north-facing A bulldozer was used at the site to spread

slope consisted of ice-rich permafrost. An analy- each load of snow after it was dumped. The

sis indicated that building a gravel pad for con- dump trucks were used to pack the snow and

struction of the pipeline would alter the thermal watraks applied tonal te A moobalace t th sie ad intiae tawin ofthe water tankers applied additional water. A motor

balance at the site and initiate thawing of the grader was used to blade the snow and shapepermafrost, thus threatening the integrity of the and smooth the snow pad. The pad was com-

vertical support members carrying the pipeline. and so th e 75.

It was determined that a snow pad could be used pleted by mid-December, 1975.Water was applied to the Globe Creek snowfor construction with less effect on the thermal pad to increase its strength and density, but an

regime and the permafrost. The snow pad was i cras it sre d nsi u t a

760 m (2500 ft) long, and 20 m (65 ft) wide, and ice cap was not formed. An ice surface on aslope such as that at Globe Creek may be of neg-

was built on longitudinal grades ranging to 30% ative benefit because of traction problems.anv benefi becauss ranin trcto probemsand cross slopes ranging to 20%. Figure 1 gives an aerial view of the Globe

The snow pad was built in November and Creek snow pad looking south. Figure 2 gives aDecember 1975 and pipeline construction, using view from the snow pad. Figures 3 and 4 showthe snow pad, was carried out in January cores taken from the pad with a CRREL 3-in. ice-through March 1976. The black spruce was coring auger. Densities of these and other corescleared with a Hydro-Axe. Because snowfall was are shown in Table 2. It can be seen that thelight during the early winter, the amount of natu- natural snow at the site was compacted from a

ral snow available was not adequate to build the natural in situ density of less than 0.20 g/cm to

snow pad. No lakes were available in the area values of 0.40 to 0.60 glcm3 . The artificial snow,from which snow could be collected, although compacted when piled and loaded at the Cha-some snow was collected from portions of the tanika River, further compacted at the snow padnearby gravel pipeline construction. Therefore it and then watered, had densities ranging fromwas decided to manufacture snow at the Chatan- 0.65 to over 0.85 g/cm' . Snow becomes a porousika River over 30 miles to the south and haul it to ice somewhat above 0.60 g/cm' , and solid icethe site. has a density of 0.92 g/cm 3. Thus the Globe

The decision to manufacture snow at the river Creek snow pad was more like ice than snow.and haul it to the snow pad site involved a num- Rammsonde tests were attempted but theber of factors. Trucks carrying snow weighing m ove too har adense t teless than 600 kg/ml (1,000 b/yd ) are under- material proved too hard and dense to penetrate

lesstha 60 kg/n 1 1,00 l/yd3 ar uner- with the standard Rammnsonde, again testifyingloaded and compaction at the site further re-

duces the effectiveness of the haul. On the other to its ice-like nature.Figures 5-7 show some aspects of the traffica-hand, wca ma ufacted at er bility of this snow pad. Figure 5 shows a pickup

' source with maximum efficiency without re-

4

7

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r- co CN m

40

r4 Ca, M 4 mr mC

NNp CNU m 4 a

0 0jY

%- r -N

GaD -r EaG -

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Figure 1. Aerial view of Globe Creek snow pad look-ing south. A = Buried pipeline. B = Built fromsnow pad. C = Globe Creek.

, Figure 2. View of the Globe Creek snow pad looking downslope toward thenorth.

6

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J

4IoB.r- CRE-Ek9 NOW CoRr

Figure 3. Globe Creek snow pad core.

Figure 4. Another Globe Creek snow pad core. Packed snow can be seen

next to the moss. ice inclusions and packed and watered artificial snow can

be seen to the right.

'Ii 7

-K,.

Figure 5. Pickup driving up 11 % slope on the Globe Creek snow pad.

Figure 6. Caterpillar tractor cleats breaking uip the uipper sur-face of the Globe Creek snow pad.

8I

figure 7 Iruck being towed tip 17% grade on the

€;lohe Creek snow pad

driving up an 11% slope The first few inches of tical support members are each equipped withthe snow pad consist of loose granular material two thermal piles for ground-cooling purposesFigure 6 illustrates the reason for the surface tex The pipeline had been fully insulated and wasture: cleated caterpillar tractors used on the complete The initial steep slope out of Globesnow pad broke up the surface Figure 7 illus- Creek can be seen in the curve of the pipeline Attrates one reason for use of these tractors A the time the photo was taken, the spring thawsteeper slope at the beginning of the snow pad was well underway and wood and similar debriswas 17% and, although light 4-wheel-drive littered the surface, although the snow pad hadtrucks could climb this slope, conventional not melted through in most places One pointtrucks such as dump trucks and busses experi- where it had melted through can be seen inenced difficulty. In this situation, inexperienced Figure 9, which shows the black spruce that haddrivers would spin their wheels, cutting more been processed with the Hydro Axe Figure 10deeply into the snow pad. It was then necessary shows the initial steep slope where the snow padto pull the trucks up the slope as shown in Figure had melted at the top of the slope, while several7. feet of snow remained toward the bottom of the

Alveska guidance pointed out that adding slopesawdust or wood chips to the upper layers of a The Globe Creek snow pad provided an ade-pad increases strength and improves traction on quate surface for pipeline construction understeep slopes. Whether using such additives and difficult conditions It apparently did not undulykeeping tracked vehicles off the pad would have compact the moss and destroy its insulation

made it possible for dump trucks and busses to value, although further evaluation of the area isnegotiate the slope shown in Figure 7 is not necessary It demonstrated the utility ofknown. manufactured snow when natural snow is not

Figure 8 shows the completed pipeline and the available in adequate quantities It also il-

deteriorating pad on 20 April 1976 The snow lustrated the problems of using snow pads onpad begins in the valley in the foreground and steep uphill slopes, particularly when cleated,

9 proceeds part way up the distant hill The ver- tracked vehicles are allowed on the snow pads

9

I ,iure R (umpieted (Jobe (reek pipeline and deteriorating snow pad, April

I igure 9 (Jlohe (reek %no w pail hais melted through. %hovtwng ',(rti sprucepro( esse( hy !lydro-Axe

10(

-~~~ - .r.-4 -. g-

Figure 10. Initial steep (17%) slope at Globe Creek during breakup.

The Toolik now pad tempted with a standard Rammsonde but theNorth of the Brooks Range most of the ele- hardness of the pad exceeded the capability of

vated oil pipeline was built on insulated gravel the instrument. The density ranged from 0.50 toconstruction pads. In this case, extruded polysty- 0.60 a/cmI. No water was added to the snow padrene insulation ("Board Stock") was laid on the but a glazed surface developed from thetundra and then gravel was placed on the insula- wheeled traffic. Vehicles with cleated trackstion. However, Alyeska was forced to build five tiieled over the snow pad and tended to chipmiles of the 48-in.-diameter elevated pipeline the surface but did not cause serious damage.between the Kuparuk and Sagavanirktok Rivers The pad was graded as required to maintain afrom a snow pad during the winter 1975-76. smooth, level surface. Grades were moderate,Snow for this pad was accumulated with a snow never exceeding a few percent. No failures in thefence. Figure 11 shows a drilling rig on the snow pad were observed or mentioned by others be-pad; this photo was taken from the nearby Haul fore the breakup period. Traffic consisted ofRoad. Figure 12 shows the vertical support light and heavy drills, trucks, cranes, loaders,members of the pipeline in place, the snow side boom tractors and other standard pipelinefence, and another snow drift formed to the right construction equipment.

* of the snow fence. The cuttings from around the In late April, the weather at Toolik warmedvertical support members were removed, and rapidly. Clear skies and more than 12 hours ofthis snow pad was kept relatively free of dirt, oil sunshine accompanied the warm air tempera-and other materials that would absorb solar radi- tures; then the Toolik snow pad began to fail.

* ation and lead to early deterioration of the snow Temperatures during this period at Galbraithpad. Airport are shown in Figure 13. Conditions at the

The Toolik snow pad varied from 30 to 60 cm Toolik snow pad were probably somewhat(12 to 24 in.) in thickness but was generally near- warmer since, by the end of April, temperaturesly 45 cm (18 in. thick.). Irregularities of the under- were no longer freezing at night on this pad. Thelying ground surface caused the irregularities in Toolik snow pad was closed on 2 May 1976; thesnow pad thickness. Ram hardness tests were at- temperature reached 9.5 0C (490 F) on that date.

11

.-A

Figure 11. Heavy drill rig on the Toolik snow padand the snowfence used tocollect snow, Photo taken from the nearby state highway.

* Figure 72. Pipeline vertical support members installed on the Toolik snowpad.

12

(*C) (*F)10 50 T T T

40-

0 1

20-

.10-

10 -

-20 -L10 5 10 15 20 255

Apri 1976 My

Figure 13. Galbraith Airport temperatures, April-May1976.

The Toolik snow pad exhibited two types of ern end of the pipeline, large quantities of natu-

failure during this period, as demonstrated in ral gas are available, it was determined thatFigures 14-17 Figure 14 shows the south end of natural gas would be supplied to Pump Stationsthe snow pad beinning in the middle distance at 1-4, which lie north of Brooks Range. A small (8the Kuparuk River A closer view of this part of to 10 in.)diameter fuel gas pipeline was designedthe snow pad, given in Figure 15, shows that the to carry this gas. According to an agreementsnow had turned to slugh While a considerable with the Alaska Department of Highways (ul-thickness of snow still remained, it had no timate owner of the Haul Road), in most areas,strength and wheeled vehicles sank deeply into this 237-km (147-mile) pipeline was installed onit At the north end of this pad, five miles to the the downhill side of the Haul Road, 4.6 m (15 ft)north of the section shown in this photo, the fail- from the toe of the grade except at cross-

ure was different and the snow pad turned to ice drainage locations where the pipeline would bethat melted away. Figure 16 shows the snow pad placed further from the road.in this area as the ice was thinning. At one point, The gas pipeline design called for installationshown in Figure 17, the pad had thinned so that of the line from a snow pad. Snow was in limitedtractor grousers were contacting the tussock supply at the south end of the line, but easterlytops, this resulted in the closure of the snow pad storms had deposited some drifting snow alongThis appeared to be the total extent of the the west shoulder of the Haul Road. Part of thisdamage to the vegetation at the tW-ne the pad snow was pushed further from the road, leavingwas closed a snow trap. This system is shown in Figure 18.

Because of the early thaw, the pipeline was The snow pad was built by spreading and pack-not completed in this section before the snow ing the snow (Fig 19), dragging it with variouspad was closed. No other means of reaching the types of drags (Fig. 20 and 21), and leveling andsnow pad across the tundra was available, so fur- further smoothing it with tractors and motorther work was delayed until the following winter graders (Fig. 22).

The thickness of the snow pad varied from 10

The gasline snow pad to 36 in and was controlled, in large part, by the

Oil is pumped along the Trans-Alaska Pipeline cross slope An effort was made to measure the

by large gas turbines driving centrifugal pumps hardness of the completed snow pad but, where

The aircraft-type gas turbines can burn certain the pad had age-hardened, it proved impossible

grades of oil or natural gas Since, at the north-

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Figure 14. Looking north to the Toolik snow pad during spring breakup. Thesnow pad begins in the valley in the middle distance.

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dFigure 15. Closeup of the south end of the Toolik snow pad as the packed"l snow turned to slush, 1 May 1976.

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Figure 16. View of the north end of the Toolik snow pad, 1 May 1976. Thesnow had turned to ice and was thinning as it melted.

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Figure 17. Final stages of the disappearance of the north end of the Tooliksnow pad showing where tractor grousers contacted tussock tops.

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Figure 18. Snow trap formed in a roadside drift near Galbraith Lake.

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Figure 19. Spreading the collected snow to form the fuel gasline snow pad.

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Figure 20. Dragging the gasline snow pad with a timber drag.

Figure 21. Dragging the gasline snow pad with a blade on a ski-mountedframe.

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figure 22. Smoothing, packing, and leveling the gasline pad.

to measure the snow properties with the Ramm- that this snow was from the upper part of thesonde and standard snow density equipment. snow drift and such snow tends to be harder thanConsequently, it was decided to test a section that below. Much of this snow had been pro-that had not yet fully age-hardened. cessed previously, as shown in Figure 18. The

The snow pad 200 ft north of the Galbraith snow in the outer portion of the pad consisted, inCamp entrance was selected for testing. The large part, of hard snow "boulders" that hadsnow in this section had been spread with a bull- been pushed and rolled to the outer side of thedozer on the evening of 26 February 1976, and snow pad. Voids between these snow "boulders"the snow pad was further shaped and graded on were partially filled with loose snow that hadthe morning of 27 February. The geometry and also been pushed outward into this area.ram hardnesses were obtained on the morning of28 February 1976, one day after the pad wasfinished

The ram hardness values obtained on thesnow pad 200 ft north of the Galbraith Camp en- Table 3. Ram hardness of gasline snow padtrance on 28 February 1978 are shown in Table 3. near the Galbraith Camp entrance.Several points are apparent. First, ram hardnessvalues near the top of the snow pad were rela- Depth fromtively high and some additional time would pro- pad surtace Distance trm east edge ot %r7o(% pad

vide a snow pad that would handle the expected On ) Icm) 45 ft ?5 ft 2S it 15 it 5 fttraffic Second, the underlying snow near the toeof the roadway was relatively soft This could be 2 5 462 2812 462 61 860

expected as this was the original snow accumu- 6 15 61,) 149 274 214 274lation area Snow was removed from this area 1u 25 484 49 2 19 154 214

14 16 ;7() I4 t154 139and the surface snow was worked and packed; 18 46 M4 1n 154 124however, the packing did not penetrate enough 22 si, 25) 42 t1

) 108to seriously disturb the snow at the toe of the 2, f6 199 214slrpe Third, hard snow was found near the outer to 76 114 79

14 816 124edge of the snow pad The reason for this was ______1_4

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Figure 23. Stringing the pipe on the gasline snow pad.

Generally the snow pad in the southern area, large trailer dump truck bringing backfillwhere construction began, was formed shortly material to the site. The contractor chose tobefore it was used for trenching, stringing pipe spread this material as a gravel pad on the snowand other early construction activities. Despite pad and then blade it into the trench. Figure 31the lack of adequate time to harden and the fact shows the partially backfilled trench; Figure 32that no water was applied, it generally perform- shows the final backfilling after insulation haded well. Two cases where problems were en- been placed in the trench.countered are described below. As the season progressed and the snow pad

Pipe stringing and welding preceded trenching began to soften, other methods of backfillingin some sections. The pipe was strung on the were employed from the road rather than fromsnow pad using conventional truck-trailer rigs the snow pad. Figure 33 shows a clam shelland side boom crawler-tractors to handle the equipped crane being used from the Haul Roadpipe (Fig. 23). and Figure 34 shows a conveyor system picking

Figure 24 shows the gasline snow pad crossing gravel from the road and dropping it into thea drainage area with a fairly long and moderate- trench.ly steep grade. In this area loaded conventional Difficulties were encountered in cleaning thetrucks were pulled uphill by crawler tractors, dirt and gravel from the snow pad after construc-Figure 25 shows a truck loaded with pipe cutting tion was completed. Figure 35 shows a pointinto the snow pad on a moderate upgrade in where the head of a culvert was dug out; theanother area. Figure 26 shows this area after ad- covering of dirt and gravel was several inchesditional traffic. Most vehicles were able to drive thick. Figure 36 shows a Gradall being used tothrough; these photos, however, do indicate that clean the pad at another site.

special care and perhaps special treatment are The environmental impact of the snow pad isrequired on upgrades. not yet completely assessed (Johnson 1980).

Trenching was carried out from the snow pad Figures 37 and 38 show a section of the pipelineeither by cutting with a Roc Saw (Fig. 27) or by that had been installed in a trench cut by a Rocdrilling and blasting (Fig. 28). The blasted area Saw The location of the snow pad is clearly evi-was then trenched with a backhoe (Fig. 29). dent in Figure 37 but Figure 38 indicates that

Part of the backfilling was carried out from much of the visual alteration is due to smallthe snow pad. Figure 30 shows a conventional quantities of dirt and gravel on the tundra

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Figure~~~~~~~ ~ ~ ~~~ 24 al adcosn dang ra Tena rdewsln n

Figure 24. Trcsload wihp crss a dange ar. n T he snear gadeonaamonerand

uipgrade.

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) Figure 27. Trenching from the snow pad using a

Roc Saw.

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Figure 28. Drilling, and blasting for the gastne french from the snow pad.Photo tAken from the adjacent ,tate highway.

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$ 4I igiire 219. Irenching with a hack hoe after drilling and blasting. See Figure28

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Figure 30. Dumping back fill material for the gas line trench on the snow padThe trench is at the near edge of the gravel.

Figure Pt. Casline trench partially back filled by blading in the gravel.

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figure f2. final back illing of the gashne trench after placement of the in-s ula tion.

f figure I J. flack filling the ga'iline trench from the road with a clam shelf.

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Figure 34. Back filling the gas line trench from the road with a conveyor.

Figure 35. Debris on the gas line snow pad.

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Figure .16. Cleaning the gas/mne snow pad with a Gradall.

figure .17. Completed gaslin. Mhe only indication of the snow pad is theslight discoloration of the tundra. The gasline is near the road.

26

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/ wire ?8 losellp oii onilefl-d gd% line

f igure ;9 A not her i ee. f the onipIt -ted g~i% It1 n Inflite /m at ion the gra'.(0* hac& till exter)d% %ltghf/ thow i'te Niarrhinding, tindha

27

Figure 39, a photo taken nearby, shows the snow. Part of this drift was then pushed out topipeline backfill somewhat elevated above the improve the effectiveness of the snow trap andtundra surface and limited quantities of dirt and an adequate supply of snow was captured atgravel on the tundra. None of these pictures moderate cost. It seems probable that lack ofshows any sign of wheel or tractor tracks on the snow will be a problem in the Subarctic and Arc-tundra and very little compression of the vegeta- tic wherever snow roads or pads are planned.tion.

The snow pad used to build the gasline, likethe nearby Toolik snow pad, failed earlier than LITERATURE CITEDexpected due to the warm, clear weather in lateApril and early May. The contractor was not able Abele, G. (1963) A correlation of unconfined compressiveto complete the gasline during the winter con- strength and ram hardness of processed snow. CRRELstruction season of 1975-76; therefore, the Technical Report 85. AD 299263.

Abele, G, R Ramseier and A. Wuori (1968) Design criteria forbalance of the line was scheduled for construc- snow runways CRREL Technical Report 212. ADtion, also from a snow pad, during the winter of 6812201976-77. Adam, KM. (1978) Building and operating winter roads in

Canada and Alaska. Indian and Northern Affairs Envi-ronmental Studies No 4. Ottawa (QS-8162-000-EE-Al)

SUMMARY AND CONCLUSIONS Brown. I and R Berg (1980) Environmental engineering in-vestigations along the Yukon River-Prudhoe Bay HaulRoad. Alaska CRREL Report (in press)

The three snow pads used by Alyeska Pipeline Hok, 1 (1969) A reconnaissance of tractor trails and relatedService Company during the winter 1975-76 were phenomena on the North Slope of Alaska USDI, Bu-

generally successful in providing a surface for reau of Land ManagementJohnson, L A (1980) Revegetation and selected terrain

construction while protecting the underlying disturbance observations along the Trans Alaska Pipe-vegetation and permafrost line. 1975-1978 CRREL Report (in press)

Snow shortages were encountered at all three Keyes, D E (1977) Ice and snow construction, workpads,locations of the snow pads At the Globe Creek roads, airfields, and bridges Proceedings of the Se-

site, Alyeska manufactured snow at a water cond International Symposium on Cold Regions En.gfmeermng 72-74 August 7976 Fa,,bank s Alask a, p

source and hauled the snow to the pad. The cost 369182

of manufacturing the snow was probably Knight. G (1%9) Pipelines in permafrost interim report Tun-moderate, but the cost of hauling was un- dra studies for TAPS, IAEE, University of Alaska. Col-

doubtedly substantial. However, it appears that lege. Alaskathis system was the best of the several alterna- Lachenbruch. A (1959) Periodic heat flow in a stratified

medium with application to permafrost problems U Stives at that time and place. At the Ioolik snow Geological Survey Bulletin 1083-Apad, Alyeska captured adequate snow with a Niedringhaus. L (1%5) Study of the Rammsonde for use insimple snow fence and thus obtained the hard snow CRREL Technical Report 153 AD 615997material on site for a very moderate cost. The Ueda. H. P Sellmann and G Abele (1975) USACRREL snow

gasline snow pad used an existing snow trap, the and ice testing equipment CRREL Special Report 146Haul Road itself, to obtain part of the required

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A facsimile catalog card in Library of Congress MARC

format is reproduced below.

Johnson, Philip R.Snow pads used for pipeline construction in Alaska,

1976. Construction, use and breakup / by Philip R.Johnson and Charles M. Collins. Hanover, N.H.: U.S.Cold Regions Research and Engineering Laboratory;Springfield, Va.: available from National TechnicalInformation Service, 1980.

v, 34 p., illus.; 28 cm. (CRREL Report 80-17.)Prepared for Directorate of Military Programs -

Office, Chief of Engineers by Corps of Engineers, U.S.Army Cold Regions Research and Engineering Laboratoryunder DA Project 4A762730AT42.

Bibliography: p. 28.

Johnson, Philip R.Snow pads used for pipeline construction in Alaska...

1980 (card 2)i. Alaska. 2. Cold regions construction. 3. Pipe-

line construction. 4. Roads. 5. Snow. 6. Snow pads.7. Surface travel. I. Collins, Charles R., co-author.II. United States. Army. Corps of Engineers. III. ArmyCold Regions Research and Engineering Laboratory,Hanover, N.H. IV. Series: CRREL Report 80-17.

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