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The bearing strength of ice
S e r
~ 2 8 t 2
n o .
NATIONAL RESEARCH COUNCIL
ASSOCIATE COMMITTEE ON SOIL AND SNOW MECHANICSr -\-
THE BEARING STRENGTH
A SYMPOSIUhi SPONSORED BY THE ASSOCIATE COM-
MITTEE ON SOIL AND SNOW MECHANICS HELD AT
BUILDING RESEARCH CENTRE, NATIONAL RE-
SEARCH COUNCIL, OTTAWA, 16 and 17 APRIL 1958
TECHNICAL MEMORANDUM NO. 56
TRANSACTIONS, ENGINEERING INSTITUTE OF CANADA VOL. 2 NO. 3, OCTOBER 1958
President: K. F. T u p p e r vol. 2
3P u b l i s h e d b y T h e E n g i n e e r i n g I n s t i t u t e of C a n a d a 2050 Mansfield S t r e e t , M o n t r e a l 2, Que. Cables: Enginst-Montreal T r e a a u r e r : T. W. E a d i e G e n e r a l S e c r e t a r y : G a r n e t T. P a g e
Editor Garnet T. Page Technical Editor Peter C. &I1
Chairman H. A. Mullins. Memhm W. Bruce, W. H. Gauvin, R. E. J. Layton, D. W. R. McKinley.
T h e Associate Committee on Soil and Snow Mechanics is one of about thirty special committees which assist the National Research Council in its work. Formed in 1945 t o deal with an urgent wartime problem involving soil and snow, the Committee is now performing its intended task of co-ordinating Canadian research studies concerned with the physical and mechanical pro- perties of the terrain of the Dominion. I t does this through subcommittees on Snow and Ice, Soil Mechanics, Muskeg, and Permafrost. T h e Committee, which consists of about fifteen Canadians appointed a s individuals and not as representatives, each for a 3-year term, has funds available t o it for making research grants for work in its fields of interest. Inquiries will be welcomed and should be addressed t o : T h e Secretary, Associate Committee on Soil and Snow Mechanics, c/o T h e Division of Building Research, National Research Council, Ottawa, Canada.
'I'his publicalion is one oJ a series being produced by the Associale Cornmiltoe on Soil and Snow Mechanics oJ the National Research Council. IL should no1 be reproduced zn whole or i n part, withoul permission oJ the original publisher. The Associate Cornmiltee u~ould he glad to he o f assistance i n ohlaining such permission.
PRINTED IN TORONTO The Ennineerinn Institute of Canada sub-
Price to non-members of The Engineering scribes t o the Fair Copying Declaration of t h e of Canada, 51.00 a copy. Authorized Royal Society. and reprints of any portion of as second class mail, Port ORirr Department, this publication may be made provided t h a t
Ottawa. exact reference thereto be quoted.
Indexed in The Engineering Index The Institute as a body is not responsible either for t h e statements made or for the
CONFERENCE ON THE BEARING STRENGTH OF ICE
Division of Building Research, National Research Council, Ottawa,
16 and 17 April,
F.Legget M.E.I.c., Director, Division
ofBuilding Research, National Research Council
sNOW AND ICE are materials which have long been of special concern in Canada. Despite the tropical heat of Canadian summers in all but the coaetal and northern regions Rudyard Kipling's poetic description of Canada a s "Our Lady of the Snows" is a title which Canada cannot disclaim. Since all parts of Canada are covered with snow for a t least part of almost all winters, the economic im- portance of snow and ice has been increasing concurrently with the steady development of the physical resources of the country, and in particular with the remarkable growth of transportation systems during the present century.
I t is not surprising, therefore, that some of the pioneer work on the scientific study of these frozen forms of water has been carried out in Canada. Quite recently the writer had drawn
tohis attention an unusually intereating record of some early work in this field of research. This was a record of experiments carried out in Quebec City by a Major Williams of the Royal Artillery a t the Citadel in Quebec City ae early as
1784.1There must be a continuing record of such experiment31 work and it is hoped that some day a careful study can be made of the historical background of current resaarch activity in Canada on snow and ice. I n any such a chronicle the name of Dr.
H.T. Barnes of McGill Univemity will have a special place of honour, his well-known textbook being one of the truly pioneer volumes in this branch of scientific investigation.'
The National Research Council, in keeping with its research service to the people of Canada, included experi- mental work in snow and ice in its early program. I t was, however, the demands of the last war that emphasized the need for more research on the properties of snow and ice. One particular investigation arose from the need
toknow something of the properties of snow in order
tofacilitate the development of better designs of skis for the winter opera- tion of aircraft. Mr. George
J.Klein, of the N.R.C. Division of Mechanical Engineering, was responsible for this work and his contributiom to the study of snow as a material have become well known.'.'
The National Res2arch Council operates not only through its working research divisions, but through the media of about 30 Associate Committees. These are committees
appointed by the Council, each to undertake the encourage- ment and coordination of research in a particular field. Membership of the Associate Co~nmittees is always on an individual baais, members being drawn from all parts of the country and from organizations having interest in the field of work of the respective committee.
One special war-research task, that of investigating the operation of tracked vehicles over poor ground, was assigned in 1944 by the Council
toa small group which was given the name of the Associate Committee on Soil and Snow Mechanics. This was done with the intention that, after the war and the completion of its initial task, this group might then be responsible for the furthering of research in Canada into the physical and engineering properties of soil and snow.
Mr. Klein was associated with this group from the start of its work but the association of soil mechanics and snow mechanics was the personal contribution
J.Mackenzie, then President of the Council, who saw clearly not only the importance of the necessary study of snow and ice as materials, but also the desirability of associating such study with the scientific study of soils, a branch of in- vestigation founded in the years preceding the war.
In association with the Meteorological Division of the Department of Trwsport and based on Mr. Klein's pioneer work, the Associate Committee in 1946 initiated the snow survey of Canada, which has been in continuous operation since that time and which has already yielded most valuable results.'~a.7-~ In connection with this work, early contact was made with Swiss reeearch workers and it was found that they, through their research experience, had also associated snow and ice mechanics with soil mechanics.
The Swiss had truly pioneered modern research into snow and ice as materials. It is Interesting and significant to note that this work was done under the Swiss Forestry Department in order to develop means for controlling avalanches primarily for the protection of forests, but naturally also for the protection of human lives. Through the co-operation of the Swiss Forestry authorities it was possible for Dr. Marcel de Quervain, now the Director of the Swiss Institute for Snow and Avalanche Research, at Davos,
t o spend one year in Canada as a guest worker with the newly formed Division of Building Research of the
tional Research Council, in 1949. The new Division of Building Research had appreciated, from the start of its work in 1947, that the scientific study of snow and ice must be one of its special responsibilities in view of the importance of these materials to buildings and to civil engineering con- struction generally, with all of which the new Division was
tobe concerned. On the basis of his year in Canada Dr.
deQuervain prepared a comprehensive program for snow and ice research in Canada and this ha8 proved
tobe a most useful guide in the development of recent Canadian work. Prominent among the problems noted by Dr. de Quervain and presented by him as worthy of study, was the bearing capacity of ice. This confirmed suggestions which had already been made to the Division of Building Research regarding the urgency of this problem. From the sttart of the work of the Snow and Ice Section of the Division, the bearing strength of ice has therefore had high priority as
a research project. Desk study was made of the available literature which was found to be limited. Experimental etudy had to 'wait the completion of the special snow and ice laboratory in the Building Research Centre in Ottawa, which was put into operation in 1054.O
As the experimental research work into this problem developed with the Division of Building Research, contact waa maintained with other workers known to be engaged on correeponding studies. Through the Associate Committee on
Soii and Snow Mechanics, which has a special subcommittee on snow and ice research, liaison was developed with many of those in Canada who are concerned with the economic and human effects of the lack of knowledge of the bearing strength of ice. This is evidenced, unfortunately, every winter by the loss of human lives, animals, and machines through ice on riven and lakes which is put
touse for transport purposes without assurance that it is strong enough
tocarry the loads imposed.
From these two direction-the experimental research work of the Division of Building Research, and the aware-
ness of the need for further advance through the Associate Committee on Soil and Snow Mechanics-the desirability of bringing together workers in this special field for the purpose ,of sharing of knowledge became evident. The Associate Committee on Soil and Snow Mechanics, in keeping with its responsibilities from the National Reeearch Council, convened a special conference on this problem and invita- tions were extended to those in North America known to be .engaged in this branch of research.
The Conference on the Bearing Strength of Ice, believed
tobe one of the first such mcetings ever held, was convened in Ottawa on 16 and
17April, 1958. The symposium was arranged by
L. W.Gold, head of the Snow and Ice Section of the Division of Building Research, N.R.C., with the assistance of his colleagues. Nine. pupcrs were presmkd and they formed ttie basis for much stimul~~ting discussion. The papers ranged from a description of the operating problems of pulp and paper companies
tothe elastic theory upon which the calculation of the bearing capacity of ice sheets must be based.
I t was evident that the papers, as a group, provided a useful review of this problem which is of such vital im- portance in Canada. The opportunity of publishing eight of the papers as a group, in a special issue of the Transac- tions of the Engineering Institute of Canada, was therefore welcomed. These papers follow: it is hoped that all who can do so will contribute
totheir further discussion. The Associate Committee on Soil and Snow Mechanics here records its appreciation of the co-operation of the Engiceer- ing Institute of Canada in making this publication possible.
1. "Experiments on the expansive force of freezing water
. . ."Annual Register, vol. 32, pp. 71-74, 1790. First published in vol. 2, T r w . Royal Society of Edinburgh.
2. BARNES, H. T. Ice Engineering. Renouf Publishing Co., Montreal, 1928. 364p.
3. KLEIN, C. J. The snow characteristics of aircraft skis. Aeronautical Report AR-2, Division of Mechanical Engineer- ing, National Research Council of Canada, Ottawa, 1947. 4. KLEIN, C. J. Aircraft ski research in Canada. Re rt No. MM-225, Division of Mechanical Engineering, Ktional Research Council of Canada, Ottawa, 1950.
5. KLEIN, C. J. Canadian survey of physical characteristics of snow-covers. Tech. Memo. No. 15, Associate Committee on Soil and Snow Mechanics, National h e a r c h Council, Ottawa, April 1950. 19p.
6. KLEIN, C. J., PEAECE, D. C. and COLD, L. W. Method of measuring the significant characteristics of a snow-cover. Tech. Memo. No. 18, Associate Committee on Soil and Snow Mechanics, National Research Council, Ottawa, November 1950. 22p.
7. PEARCE, D. C. and COLD, L. W. The Canadian snow survey Tech. Memo. No. 21, Associate Committee on Soil and Snow Mechanics, National Research Council, Ottawa, August 1951. 39p.
8. COLD, L. W. and WILLIAMS, C. P. Some results of the snow survey of Canada. Research Paper No. 38 of the Division of Building Research, National Research Council, NRC 4389, Ottawa, June 1957. 15p.
9. COLD, L. W. New snow and ice research laboratory in Canada. Reprinted from J. of Glaciology, vol. 2, no. 19, March 1956, pp. 635-637. Division of Building Research, NRC 3852, Ottawa.
This paper outlines in general terms the thinking o j logging operators on the strengthening o j ice sheets. E~uipment and prw- tiws are described. Loads aUowed on different iac thickneewe are m t i o n e d .
HEPULPWOOD INDUSTRY in Canada annually places millions of corda of pulpwood on ice landings. Within the industry a "landing" is
anarea where pulpwood is tiered or piled in quantity for temporary storage on its way to the pulp or paper mill. An ice landing is such a tem- porary storage area made on the ice of a lake or river. Ice landings on rivers are hazardous because the river currents weaken the ice unpredictably, hence the lake site
ispreferred. An ice landing may be required to hold from 10,000
to100,000 cords of pulpwood. The quantity of wood that can be landed per acre will vary with the type of operation. Wood in Pfoot lengths can be dumped, but 8, 12-, and 1 6 foot logs should be piled if the drive is to proceed smoothly in the spring. A rule of thumb is to provide landing area on the basis of 500 cords per acre. This provides piling area and room for "roads" between the piles. Ice landings thus vary in size from 20 to 200 acres. Maintenance of an
ade-quate ice landing costs about 30 cents per cord ; for 50,000 cords $15,000 will be spent to prepare and maintain an area of 100 acres ($150 per acre). These costa accumulate over a three-month period roughly Christmas to Annunciation.
Itwould, however, not be correct to set a cost of $50 per acre per month. Except for severe snowfalls the original dump preparation is more expensive than the maintenance. Par- ticularly since only that area still to be used is maintained. Once an area
isfilled with wood it is neglected.
Construction and Maintenance
Ice landings are constructed and maintained by flooding on top of existing ice and rolling any snow that falls. I n certain cases the roadways on the landing are plowed after snow. This last is not a popular practice since the windrows of snow take up dumping area.
Flooding is started as soon as the natural ice is strong enough to support men and pumpa, say 3 inches. The first flooding is often limited to an inch since the ice cannot yet support the men and equipment plus 2 inches of water, which is the usual flooding depth.
The nominal '2-inch depth of flooding is fixed by the two major considerations :
( a ) 2 inches of ice mill form overnight even if the tempera- ture is a little above OD
(b) with depths greater than 2 inches there is a real
Canadian Internstional Paper Company,
danger that a layer of supercooled water will be held between the old ice surface and the new layer of ice.
On a very cold windy afternoon the depth of
floodingmight be increased. I t is believed, though experimental evidence is not available, that the supercooled water ie left between the layers of ice on calm nights. I t is logical
consider that agitation by the wind will eliminate the layer of water and the practice probably stems from such thinking. Where snow is lying on the ice sheet it is, if a t all possible, compacted by rolling before flooding. At this stage there are two schools of thought on the depth of flooding needed. One says that the area should be flooded until the snow is uniformly "dark" but that there should be no free water visible. The other school floods until n thin film of water lies over the snow, i.e. water is visible. Both systems are used, both work. No experiments have been made.
No particular temperature conditions are set down for flooding. "Make ice when you can" is the motto. Adjust the depth of flooding to the conditions but keep on making ice.
Methods of Flooding
Flooding is done in two ways. If there is a driving dam a t the outlet of the lake, holes are cut in the ice, stop logs are put into the dam gates, and the water is allowed to
riseto the desired depth. Where there is no dam the holes cut in the ice are used for the suctions of gasoline-powered pumps.
The holes are cut in the ice with axes, more commonly, ice chisels, and, increasingly today, by power-driven ice augem.
Itis thought that only the larger dumps justify the expense of the power-driven auger. The ice chisel is a field tool made up to the foreman's specifications by the black- smith. Old files or a broken leaf from a truck spring are given a chisel shape and fastened to poles.
The pumps used are the common contractor's p u m p a single centrifugal pump driven by an air-cooled gasoline engine. The usual size is 3 inches suction and 3 inches dia- charge delivering about 12,000 imperial gallons per hour. Such a pump weighs around 100 pounds. The use of 6-inch pumps has been advocated but what they gain in speed they lose in portability.
Trials have been made with a Swedish patent power ice auger and pump combined. The auger cuts a hole in the ice and then "worms" the water to the ice surface after Archimedes' classic pattern. The auger is excellent but the delivery of water was found to be too slow for large dumps (60 acres and up).
b l l e r s for snow compaction are commonly job built. Usually 8 feet in diameter they are from 6 to 8 feet wide.
The rolling surface of 2 by 4's on edge
icovered with 1/8- inch steel or iron plate. The steel plate
ieadded to increase roller weight and protect the 2 by 4's against breakage.
Today the roller is pulled by the model 5-5 Bombardier tractor. With these, 60 acres can be rolled in 24 hours. Care must be taken to install a frame of logs around the tractor EO that if it goes through the ice it will be supported
by the frame and BO can be recovered easily without
damage to the motor or danger to the operator. After the ice has increased to over 16 inches a truck can be used to pull the roller. The truck
ienormally twice aa fast as the 5-5.
m e n the ice is not thick enough to support the roller a single log drag is used behind the 5-5 or even behind a horse. The drag h usually a nominal l@inch diameter log 8 feet long, just a big stick of pulpwood. Although such a log does not do much compacting it does break up the snow suffic- ciently to improve frost penetration.
Slush always seems to form after a enowfall. The weight of the snow cover depresses the ice aheet and free water comes up through crack^ or the insulating blanket of snow
allows a current, probably a thermal in lakes, to weaken the ice sheet from below. Rolling immediately after a snowfall, or during a storm if it is
asevere one, improves frost pene- tration and lessens the slush problem.
The ice thickness uscd varies with the job. Horses and loaded sleighs are safe with 8 to 12 inches of good ice. The smaller trucks do start dumping with 16 inchcs of good ice though 24 inchcs arc preferred. Twenty-four inches of ice and over is reasonably safe for trucks of up to 50,000 pounds
G.V.M.This does not mean trucks rated a t 50,000 pounds by the manufacturer. Logging practice is to put on a big load: 9 cords or 40,000 pounds on a truck weighing
10,000 pounds for chassis, cab, and body.
Adescription of the pulpwood industry's practices with regard to ice landings is contained in the publication "Pulpwood Landings" by
R. D.Collier and C.R. Silversides of the Pulp and Paper Research Inetitute of Canada.
The Preparation of
Pulp and Paper Companies in
B. Rose* a n d C. R. Silversides*
The Woodlands Operating L)epartmenla of lhe pulp and paper cmpaniea in E a a l m Canada have found lake and river ice landings very advantageous aa alorage areas and as transfer points in their p u l p w d transport operalions. Considerable empirical ezperience has been gained in the preparation and muintenance of landing areas as well as ice roads and bridges. The main problem ia to greatly increase the ice lhickneas and its bearing capacity early in lhe winter season. Another aspecl of operating vehicles on ice is that of salvaging those that break through and are submerged.
APULPWOOD LANDING may be defined as that place where pulpwood is stored while waiting further transportation and/or that place where the method of transportation is changed or modified.' Within this definition, ice landings may be either a storage area or a point of transfer.
Ice landings are advantageous because when wood is placed upon such an area, it
isin position to be transported by a different method (river drive or lake tow) with no further effort on the part of the logger. When the ice melts, the wood is on its way; it does not require any further handling or placing as in the case with landings on land. Here the wood is placed on the ground after being handled and transported by one method and must be rehandled and loaded onto the next system of transport.
We are concerned with lake and river ice landings. In the course of pulpwood logging operations in Eastcrn Canada, over 20,000,000 tons of pulpwood are transported each year over distances up to several hundred miles. I t is not known with any degree of accuracy what portion of this total is placed on pulpwood ice landings but it must run between 50-75%.
Water transport of pulpwood through river drive and lake tow is still the major method and the most economical means of transporting pulpwood in Eastern Canada.
When considering the use of lake or river ice as a landing, the following factors should be considered :
(i) Quantity of wood
tobe landed. (ii) Landing area available. (iii) Type of hauling units. (iv) Unloading methods.
(v) Ice conditions.
Lake ice landings have advantages over most river land- ings in that
(a) Usually almost unlimited area is available.
(b) Scheduling of unloading is simplified.
(c) No further rehandling is necessary.
River ice landings are not usually as satisfactory as lake
ice landings but are used where circumstances permit, usually because no further handling of the wood is required. This is compared with the placing of the wood along the banks of a river and aftcr the ice goes out, throwing or pushing the wood into the watcr.
Regarding the use of ice landings by the pulp and paper industry, four aspects will be discussed.
(1) Preparation of ice landings. (2) Maintenance of area during use.
(3) Ice roads and bridges.
(4) Vehicle drownings and their salvage. Preparation of Ice Landings
The purpose of any preparatory work on an ice landing is to produce the required thickness of ice in as short a time
as possible. Usually conditions for winter hauling of p u l p wood on land are satisfactory before lake or river ice is of a sufficient thickness to support loads being placed on it. Because our winter hauling season is short under the best of conditions (60-75 days) it is imperative that ice landings
available as early in the season as possible.
The ideal situation exists in early winter when there is a continuous cold spell with little or no snow.Z This permits a ready build-up of ice thickness, sometimcs to the point where traffic is possible with little assistance from man.
The usual situation, however, is the formation of a rel- atively thin covering of ice over which there is a generous covering of insulating snow.
Under these conditions, the first step is often to put men on snowshoes to tramp the area of the dump. The men each carry a long pole to aid them if they break through. The purpose of tramping the dump is, of course, to pack down the surface snow and reduce its insulating value.
dary value of this tramping and later of dragging, is to per- mit better and faster distribution of water when slushing begins.
After tramping, when the ire is sufficiently thick, a horse pulling a log broadside, or, more commonly today, a small light snowmobile with drag, further packs and levels the snow. Here, too, the horse generally has a long pole fastened to it and the snowmobile has a wide rack fastened to it,
prevent a complete break-through and to facilitate salvage. The risks inherent in this work are well recognized and guarded against as far as possible.
After tramping or compaction of the surface snow by rolling takes place, the next step is slushing of the dump. The relative strengths of clear ice and slush ice are recognized and are sornetimcs used as an argument against slushing the landing. However, the period required to freeze water on the surface of the ice is much shorter than that when the
Woodlande Development Engineer, Abitibi Power and Paper Company ice thickness is built up through normal freezing. Figure 1
Limited. 'I'orol~ro. Unt. shows a comparison. I t is based upon the formula for the
ratc of growth of an icc- s h w t on still water when the ~ u r f a c e of the: icc is frect from snow, after Dr.
H. T.Barnes.8 This r a k of growth i~ shown graphically in Fig. 2. Thin graph is
further conlirmcd 1)y I5c.wkow . a
Figurc 1 shows thttt,
start in^with a layer of icc 12 inches thick in -20"
F.weather, if 5 lnclles of water are added on the surfacc i t will takc approxirnatc,ly 15 hours for it t o freeze anti give us a total of I 7 inches of ice. If the Ice surface is bared and ice is t o be formed on the under-surface of t h e 12-inch i c ~ sheet, i t will take 60 hours t o a d d a n additional 5 inches. This is 4 timcbs a s long.'
The slushing operation consists of cutting holes in t h e i c l with axrs or ice chisels a t approx~mately 100-ft. intervals. A collar of packcd snow or slush 6 t o 8 inches high is built around each holo t o prevrnt water from escaping bark down the hole. When slushing, water 15 generally put on t o the
depth of the snow and not t o too grrat n depth above the snow, as this results in thc formation of shrll ire. Flooding is usually not carrird out until the ice is 4-5 inches thirk. If thinner, the weight of water on the surface m a y sink it. Pumps used t o flood dumps vary with local operators. The most common arc rentrifugal pumps about 40,000 gallons per hour capacity, powered with an air cooled engine. These are generally mounted on a sled and are capable of being moved around the dunip by snowmobile or small tractor.
A recent Scandinavian drvc>lopnic.nt is a unit called the Tyfon ice auger and water pump. This is a light pump of about 130 lb. total weight and can be rradily moved on a hand sled or with carrying handles. I t consists of a powered ice auger w l ~ i r h in turn acts a s a pump impeller after a hole has been drillrcl through the ice. I t can put o u t about 30,000 gallons an hour and has been found vcry effective.
Onc location in an ice landing which requires special attention is t h a t point or points whercb roads come down off thc shore on to the ice. Somctimrs thesr locations are rein- forced s i n ~ p l y by rxtra slushing to build up the ice t o a thic-kness whcre brrak through is very unlikely. Often they are reinforcard by t h r frtbrzing of tlnlbcrs into the ice or, altcrnativcly, ~ t r a n . and brush.
This material :tc,ts in two ways : ( I ) i t distributes the load Fig. 1-Compnrison of two methods of ice thickening (a) Freezing of water on surface take8 estimated 15 hours, while in (h) equivalent thicknene of ice requires 60 hours
THICKNESS OF ICE (INCHES)
Fig. 2-Rate of growth of ice sheet on still wnter when the surface of the ice is free from snow"
.'.over a wider area, and (2) i t increases the shearing strength of the ice (Fig. 3 ) .
Where the situation is criti(:al, it is often feasible t o make a pole m a t held together by interwoven cables a n d freeze this into the ice, ancahoring one end on shore.
Maintenance of Area During Use
Like many operations, it is oftcn difficult to establish when construction (:cases and maintenance begins. I t is assumed herc: t h a t the construction phase is completed once the delivery of pulpwood is started.
I t will bc seen from the appentliccs t o this pspcr t h a t t h e operation and maintrnnnce of a n ice landing varies regionally and particularly with t h e hauling equipment used. In general, maintc,nnnce of a landing will consist of rolling or ploughing and in the rep:rir to damaged areas on t'he dump. If a dump is maintaincd by rolling. the roller is usually on the go all d a y cvrry d a y t o maintain the surfacc. The roller is used during and :tftrr snow falls t o prevrnt a n y considrrable depth of loosca s ~ i o w from building up.
If a d u m p is ploughetl, usually the ice is ploughed t o its surface a n d a co~isidcrnblc a r r a is kept ploughed ahead of the haul to permit some ico build-up or thickening.
The main argument against ploughing is t h a t the snow thus accumulated takes up landing room and, by its con- centrated weight, creates tlepressions in the ice which result in flooding or causr thin arras in t h e ice beneath them due t o their insulating effect. I n practice, the snow is usually ploughed up over wood on the landing, the ploughed area advancing across th(! landing a s the wood advances so t h a t loss of area is not critical.
If possible more than one road should exist down on to
the landing. This is the bottleneck through which all the wood passes a n d no interferencc with the haul can be tol- erated.
The practice when dumping wood on the ice is t o havr two or more locations on the landing t o which the hauling vehicles can go. Tho wright of wood on thc ice tends t o sink it a n d cause watcr to cornc up. If this ~ v a t c r gets too deep, the unloading point is c:hangctl. ( T h r writer has seen horses well above their k ~ ~ c e s and trucks well above thcir axlcs in water, still unloading woocl in r l flood(:d nrca.)
Some indication of th(: loatling on thc ice is shown by the rule of t h u m b volume of 500 cds. per acre of ice landing. We
have instances of 900 cds. per acre. These are the equivalt.nt of 1125 tons
to2025 tons pc3r acre.
Loads of wood arc usually d u ~ n p r d around tire pc?rinreter of the landing. This sprcxads out thc loading on thc ice and if flooding rc!sults from the irc loading, it will be on the pcri- phery of landing and the centre and approaches will remain dry.
Another reason for thc above pattern of unloading is t h a t the wood piles will tend to act a s a snow break and reduce rnaintenancc within the landing area proper.
This pattern also results in lower road maintenance as the landing progresses inward, reducing road length on the landing.
Because of the nature of its occurrence, ice tends t o be self healing if caracks or holes appear. Often brush or straw or poles are uscd t o add reinforcement or t o speed up the refreezing procc'ss.
I t has bvcn tliscovc.rcd t h a t air holes can be made t o freeze by d r o r ~ ~ i n e : a uulr, stick in them.
Ice Hoada and Rriclgew
Refercncc is made hew to roads or bridges over ice because they often form a part of a p u l p ~ o o c i landing.
'l'hcre is little diffcrcnce betwec.n thcir construction and t h a t of a pulp\cood 1;rntling. Usually trc-ause of more con- centratcd traffic, ice roatls a n d bridges arc built up t o grrater thicknesses than landlngs and the surface is kept ulouahed
-down to 2 t o 3 inches of snow over the ice for better traction. Roads are generally ploughed up t o 150-200 f t . in width t o permit alternating the traffic along it, working gradually from one side ac.ross t o the other before starting over again.
Fig. 3-Relative strength of various methods of reinforcing ice. METHOD OF REINFORCING I C E - O R I G I N A L ICE T H I C K N E S S 6 " C L E A R I C E E Q U I V A L E N T
This rc.tlucc,s da11gc.r of tic*tc~~.ior:~tio~i of the, ic-c,. It also n1akc.s possiblca a clroic~cu ol' r o ~ ~ t o ~ if t h ~ r c ~ is 11 Orcv~k tlrroclgll.
I tis recognizc,tl t)y our ~)c~rso~irlc~l tlint tlrc. J):LHS:IKI~ of 21 loading truck scbts up :L Hclxr~ral ivt~vc. arrtl t h a t tr:~volli~rp, nt too high spcc~ds nray rcbsult i r r 1)rcb:tk t l i r o u ~ h .
At our main Inrltlllrg 011 I,ake Bbitil~i, s p c ~ d s are lield t o
5 m.p.h. early in thc scwon a ~ i d 1:~tc.r : ~ t 10 1rr.p.h. 011 the
ice bridge across tlrcl AIattagalnl Rivclr. y ~ c ~ r t l s arc held to
10-15 m.p.h. with icc thicknc~sscbs u p t o 36 inches and gross loads of 40 tons. On our L a k e h ~ : ~ d opc-ration, speeds are held t o 10 m.p.h. on the* icc landings. At Pinc Falls on the Winnipeg River, sprcrls :Lrv cuontrollcd t o 10 m.p.h. or less. At this location they have, ohscrvrd t h a t with he:~\lily loaded trucks wllic.11 arcs nloving too rapitll!,, a wave is scbt u p in the ice in front of the. raw whec~ls, whic.11 of eourscl are carrying the load. This wave has not 1)cc.n obscrvcd with thc. semi- trailer units.
Thcy have observed t h a t this aavcl artion tcbntls t o c~rac~k the ice in a chcckcrl~oarci pattern, often rc~sulting in trucks breaking through road\vays whic-h arc considc~rc~tl safe.
Ihcrc is a psyc~hologic~:il facltor \vhicth clnters into control of vc.hicsl(b sptcd on ic-ct :IS tlrivcbrs, if thcuy have a fcbar of breaking through, Iiavc. :I c.ornpulsion to tlrivcb too fltst. This
is tllc. worst thing t11c.y c.oultl (lo. Vehicle Drowning and Salvage
I3crnuse of the \rid(, usirgc. of I(.(% as a trimsport mc.tliutn
by the pulp and papcbr intlustr) , ~cbhic*le dro\vrringand salv:tgc, has become a son~c~what routincb I~usincss. .i s others nray riot b r so familiar with this ~)rol)lcm and various solutions t h a t have been found for it, a variety of c.xan~plcs have bccn brought together :rnd illustrittc~d. where possilde. for the rc.rord of this ~rrc~eting.
A study was tirade of the equiprnc.nt dronr~inga for the. past
five. y t w s in our difTrrc.nt divisi011s. 'Sllcby totallc*tl 58 in number and may I)(: scpar:~ted as follo\vs :
Truck and truck trailer 2(i
Of thv abovcb. the distriI)ution of sinkings is 34 o ~ i I:lk(: and 24 on river 1:lndings.
Whilc not stricbtly c ~ o n s i d ~ ~ n ~ t l a vc%liic.lc*. tlrt' first c~xarrlplr deals with the saving of a horse t h : ~ t Iras gonct tliror~glr the icc.& 111 thr cwly stngcbs of landilig ~)~.c.par:ttio~r, Irorsc~s :ire often used t o pull tlrags t o pack sno\v. In such cascBs, a ltaather strap is oftc.11 att:tc.lrc.d t o one of tlrtr hint1 Ivgs :tt the a n k h . r l ropcb :rlmost 12 ft. long is nttacbhc~rl to this str:tp and is passed o\.c:r tl~c. aninral's hack. LVhc-n tlrc. horse, goes through tllc ic.o, thv tc~rnrster plllls on this roprS to givc the horse suffiritmt purc*husc. t o c:laml)c>r out onto solid irv, as shown in Fig. 1. Y1.t anotlrc,r tlc\,icaca is shown i l l Fig. 5.6
Thr polcs can be attac*lrclci to the, hltrncss in such a way t h a t they can bc reatlily rc.n~ovc.ci when t h e horsc. 1eavc.s the ice t o go on a ro:rd or irlt'o thc~ hush. Thv tr:~iling log can also be easily rcnloved.
A method of Iroist.ing arltl rc~moving a tractor t'hat has gone through the. ice. is sho\v~r in Fig. 0 . 7 In tht. diagra~rr,
two water tanks arcs used ant1 tht,ir hcight is hrlilt rip b y timber cribbing. i f h(.:lvy tluty slvighs :trc3 :~vailal)lc~, the cribbing c:ould also I)(, built ul) tlirc-c8tly on t l r ~ n r . LVhc~r the tractor is hoistcrl c~ltaar of t h r \r:~tc,r, tlrcb slcighs and tr:rc*tor can be skidded to slrorc~.
A t many lantli~rgs a s : ~ l v : ~ g i n ~ frt~~rrcb is kcyt in rc:acliiic~ns.
,.1 his frame can I)(- of tirrrl)cbr or stcbctl, skit1 rnountc~tl SII :LS to
be rradily movc.11 I)? :L trac.tor. Skc.tc.lrcbs of two of thvst* tLrcb shown in Fig. 7.
Figurc i a is a stclc.l-fra~nc: 3% ft. long, It; It. wid(, anti I!) ft.
high. I t is equipped with two five-ton hand winches and a large triple block with which a tractor winch can be brought to bear. Figure 7b is of a lighter timber frame 12
ft.wide, 30 ft. long, and 18 f t . high.8
When using tractors on ice, some operators fasten a 50
tothe rear drawbar or hook a t the front and have a water-tight drum or buoy on the end. This cable is coiled 1oosc.l~ and the drum is cnrricd in such a manner that if the tractor gocs tiown, the buoy will float free and mark the unit. This hit of forcbsight can savc a great deal of trouble when ~alvaging opc-rations t)c.gin.
Vvry oftt!n whc.11 trucks :rntl t~.uc.k tr:iil(:r combinations go through thv it:(!, or~ly the. rcbrir chlltl I)rc~rkn through. One routinch for salvage* wt1c.n
t l ~ i ~h:q)pc.ns is :
( I ) Snub the truck to a deadman in the ice.
(2) Unload the pulpwood and remove chunks of ice from the hole.
(3) Set up salvage frame. This may be of the type shown in Fig. 7 or may be a standard A-frame jammer, normally used for loading sleighs or transferring loads of wood from sleighs
(4) Raise the front end of the truck out of the water sufficiently
toskid a long (30 ft.) timber under it.
(5) Move the frame
tothe rear of the truck, raise the rear
Fig. 4-Method of saving a horse which g a e through the ice6.
Fig. 5-Safety rack for horaes7.
S I Z E O F T R A C T O R NUMBER O F P O L E S / V A R I E S W I T H W E l G n T OF T R A C T O R D I S T A N C E B E A N D T W E E N
Fig. 6-Hoisting and removing tractor which has gone through the iceB.
end clear of the water and place a long timber under it as for the front.
(6) Jack up the timbcw and put sleigh runners under each end.
(7) Pull the truck and timbers clear of the hole.
Another brief outline of a mtlthod and equipment required
tosalvage drowned equipment
(I) Take soundings of water depth.
(2) Clear hole of ice and crllarge it necessary so that drowned equipment has room
toemcrge, regardless of its position as it comes up from the bottom.
(3) Freeze long timbers into itc on (bither side of the hole, about 13-15
(4) A tripotl is assemblc~l. Two l ~ g s of it arc, anthored to
the long timbers by means of a (TOSS piwe. A hoisting htoc.k is attached
tothe top of the tripod. ti cross tinher is fas-
tened to the third leg of thc. tripod and the tripod is raiwd up into position over thc hole in the ice, the threc legs Securely anchored to cross bars which, in turn, are fastcnctl t o the timbers frozen into the ice.
A quadrapod is generally used in place of a tripotl if the ice is less than 9 inches thick.
(5) From the top of the tripod a 3/4-inch diameter cable is suspended, with one m d hanging loose. The submerged vehicle is hooked by some major part of its frame. The vehicle is raised to the limit of travel of the pulley blocks used and the grappling line is clamped to the safety cable. The hoisting cable is slackened off
tolet the safety rablca carry the load. A new eye is made in the free end of the grappling line and it is hooked onto lower block which is brought down again from the top. This operation is rclpeated until the vehicle is brought up to the surface.
(6) When the vehicle is raised clear of the water, a deck of poles is slipped underneath it. The vehicle should be drained immediately and if this is not possible, the vehirle should be left immersed until this is possible.
Figure 8 shows a method of removing a truck, the rear end of which has broken through the ice.10
An 8 ft. long pulpwood stick is notched into the ice a t the rear of the front wheels. This blocks the unit to prevent it slipping back into the hole. The pulpwood is removed from the truck. Four poles 20 ft. long with a minimum top of 4 inches are obtained. A pole is placed under the centre of each dual wheel, placing it butt end foremost into the water. Then using the other two poles as a pry on either side, the truck is pulled forward by means of another truck or team of horses. The engine of the truck in the hole should not
be run, a s this will kick o u t the poles under the wheels.
I n Fig. 9, another method of salvaging a partly submerged
truck i~ shown.lL After the pulpwood is unloaded from the truck, a long heavy timt)car is pllrced across and parallel to
t h ~ rcxar of the vc:hic:le trnd fustc.ncd in place with chains.
clr~nll) tr~rc:k iti I)~~c:kc:d u p to c~ac.h cbntl of and in line with t h i ~ c:rosn tirr~l)cbr. l ' t ~ c : nlck of oach of ttirsc trucks ie set in the: r~nload ponition and fastc%nc!tl
tothe c-roua timber. On a signal k i n g given, the dumping hoivtu are lowered and the trucks are gunned t o lift u p and o u t the psrtly submerged truck
1. (:~I.~.IP:R, lt. I). and S~I.VE:R~IDEB, C. It., "Pulpwood Land-
ing". Pul and Paper lteaearch institute of Canada,
Wtrotllantl~ kctrearc:ll Index No. 04, 67 p., 1054.
2. I ~ E N A U I ) , Hrinrr, "Icr 1,andin Preparation". Pulp and
Paper Magazine o/ Catmda, vo!. 57, No. 1, January 1056,
3. HARNES, DR. H. T., "Ice Ehgineering". Montreal, Renouf Publishing Co., 1028, 364 p.
4. RESKOW, G., "Scandinavian Soil Frost Research of the Past
Decade". Proceedings, 27th Annual Meeting, Highway
Research Board, December 1947, p. 372-383.
5. SAVARD, J., "Method of Saving a Horse Which Goes
Through the Ice". Canadian Pulp and Paper Association, Uroodlands Section Index No. 1180. Suggestion Note No. 47, 1 P.
6. EAST. R. A,. "Safetv Rack for Horses". Canadian Inter- natiohal paper coGpany Cooperator, Bulletin No. 29, 10 March 1948.
7. SIDEEN, A., "Hoisting and Removin Tractor When
r17hrough the Ice". Canadian Pulp and fiaper Association, Woodlands Section Index No. 1262, Suggestion Note No.
90, 1 P.
8. CARREAU, G., "Lifting Frame for Trucks and Tractors in Case of Accidents on Ice". Canadian International Paper Company Cooperator, Bulletin No. 71, February 1949. 9. I A ~ ~ . ~ ~ r , ~ ~ , R. R. and LOPONEN, T. A., "Salvage of Drowned
Vehicles". Canadian Pulp and Paper Association, Wood-
lands Section Index So. 1450. Suggestion Note No. 162,
Fig. 7-Salvaging frame*: (a) steel, (b) timber.
- . BRACES TRUCK UNLOAOEO
-/ O N T O ICE LONG P O L E S W I T H 4 " TOP D I A M E T E R
Fig. 8-Method of removing pulp truck from hole in ice".
(01 TRUCK THROUGH I C E
I b l LARGE T I M B E R P L A C E 0 ACROSS R E A R OF S U N I E N TRUCK A N 0 F A S T E N E O TO I T WITH CHAIN. BACK A O U Y P TRUCK TO EACH END OF TIMBER, I N UNLOAD POSITION AND F A S T E N TO T I M B E R .
E DUMPERS A N 0 GUN AHEAD. U P A N 0 OUT.
Fig. 9-Use of dump trucks to salvage a submerged truckla.
10. SIDEEN, A., "Method of Removing Pulp Truck from Hole in the Ice". Canadian Pulp and Paper Association, Wood- lands Section Index No. 1253. Suggestion Note Xo. 8 1 , l p. 11. BERTRAND, W. D. and REMILLARD, li., "HOW t o Salvage
a Partly Submerged Truck". Canadian Pulp and Paper
Association, Woodlnnda Section Index N o . 1 106. Suggestion Note No. 1, 1 p.
A COMPANY-WIDE SURVEY of local practice in the preparation of
maintenance and operation of ice landings was made from
Manitoba through to Eastern Quebec. Summaries of these reports are included here t o show the effect of climate, logging method, and hauling equipment upon local practice.
The Manitoba Paper Company, Iimiled, Pine Falls, Manitoba
Three main landings on the Winnipeg Itiver are used:
( a ) 40,000 cords landed over 100 acre area, water depth 60 ft., current 1 mile per hour.
(b) 17,000 cords landed over 35 acre area. water depth 40 ft.,
current 1/2 mile per hour.
(c) 20,000 cords landed on 48 acre area, water depth 50 it., still water.
As soon as ice forms a complete cover flooding is begun from
the shore with 3-in. and 4-in. pumps. When ice is &in. thick and capable of carrying a horse these purnps mounted on sleds are moved out onto the ice. When ice is Bin. thick a Bombardier 5-5 or John Deere tractor is used to pull a drag over the snow covered ice. The drag is a 6-in. I-beam 20 ft. in length. With 10 in. of ice a 3-ton truck is used t o pull two similar drags in tandem over the landing.
Snow is compacted by dragging prior to flootling to a density that will support a 1/2 ton truck. Usually 4 in. of new ice is made a t a flooding and 24 in. of ice is the minimum thickness before loaded trucks are allowed on the ice.
'I'here are usually three or four roads onto the landing. When hauling first starts loads are dumped around the perimeter of the landing to form a snow fence and reduce snow drifting on thr landing. If water roincs up during the operation the un- loaditrg of wood on to the ice is shifted to a different location until the fl(~odrd nrr~r frec.xcs.
'roo 11e:rvy trtrffil: in ~ x t r e i r ~ c (-old w~~trt.ll~!r (-30' 1'1.) will cause tr road to (,rir(-k :LIIII chul~ks of i(:c to break out. 'rruck
speed aBects thc life of ttlc ive. If trucks travel faster than 10 miles per hour it ha8 heerr observed that a compression wave is set up in front of the hac4i wheels of chassis loaded trucks. This is not so apparent with loaded semi-trailers. This wave action tends to crack the ice in a checkerboard pattern.
Roads across the ice should be 200 f t . wide with equal dis- tribution of traffic for the full width so that through constant use a single track will not become weakened. A 3-in. to 4-in. layer of packed snow on top of the ice gives a cushion. Glare ice breaks up very rapidly under traffic in extreme cold.
C:rac*ks in the ice arc filled with snow by the grader or the drag arrd are then filled with water to freeze. This is not done in extreme (bold weather as the best ice seems to be made near 0" F. Where lollg cracks appear in roadways an attempt is mrrdc to havt: tllc trucks straddle the crac!k. Local experience shows tlltrt IO~LIIH no st o f t c ~ ~ break tllrougtt when they are a t tt~c! jut~c-tiol~ of two I-nicks and not straddle of either of them. 13cfore 1a11tli11gs are drclared open the ice thickness is tested by drilling. An air compressor with a 255-in. pneumatic drill is used for this purpose.
Atrilibi Patuer 82 I'aper Company, Litnited Lnkehead Woodlands I)ivision, Port Arthur, Ontario
Two landings are described, both north east of Lake Nipigon.
( a ) 9,000 cords landed over 10 acre area on lake ice.
( 6 ) 28,000 cords landed over 95 acre area on lake ice. When ice is 6 in. thick, 3-in. pumps mounted on hand sleds are used to flood dump. When ice reaches 8-10 in. thickness, 4 i n . and &in. pumps mounted in pump houses are used. These are moved around by snowmobile or light truck.
Flooding and rolling is continued until the ice is 24-30 in. thick, a t which time hauling begins. Once the ice thickness is sufficient flooding is stopped and the dump surface is maintained by ploughing.
Sometimes when the ice is 12 in. to 14 in. thick the landing will be ploughed into windrows generally 60 It. to 90 ft. apart. As the weight of windrowed snow increasm the ice beneath sinks and (.racks and flooding occurs for a distance of 15 ft. to 25 ft. from the windrow. Through use of the windrow method the cacntre area can ~enerally be counted on to be dry as the ire is lightly convex between the rows of snow. If cracks appear in this centre arca parallel to the windrows the cracked area is flooded to sen1 the breaks.
Cracks which bring up water generally seal themselves. Dry c1.ac.k~ are considered more dangerous as it is not possible t o determine how much solid ice remains. In this case the cracks are sealed hy flooding with pumps or tanks of water.
Speed of trucks on ice is limited to 10 miles per hour. Air holes that appear early in the seasons (Dec. 15-Feb. 1) were sealed by inserting a pulpwood stick in the hole, after which it would freeze solid. Air holes that appear nfter February 1st are almost impossible to seal.
Abitibi Power & Paper Company, Limited -Saul1 Sle. Marie L)ivisia, Regan, Ontario
The major ice landing for this operation is on White Lake. Some 15,000 cords of wood are placed here each year. Loads of pulpwor~d are 65,000 Ib. gross combination weight for truck and semi-trailer units, and 50,000 Ib. gross vehicle weight for large tandem axle trucks with chassis load.
Due to physical co~~ditions it is necessary to build and use 1,000 It. of haul road across the lake ice t o the pulpwood landing, ant1 1,400 ft. of go-back road.
I t hns been found possible to get on the ice earlier with p u m p ing equipment if the ice is broken up once or twice before it rent-Ires a thic+kness of 4 inches. The purpose is to get rid of the nnow on the first thin layer of ice. The cost of this particular project is almost negligible uince a tug is left in the water late for tllis ~ ) u r l ~ ) ~ + r and it only takes 3 or 4 hours of running around
Fig. 10-Plotting of ice: Loadingn from summary sheet showing range in loading for various ice thickneaaer.
to break up the ice. I t is importnllt that the ice lays reasonably flat after it is broken up. Timing of this operation is important and if the last run through the ice can be made a t the beginning of a clear cold period the area will freeze sufficiently in a couple of cold days to carry lighter pumping equipment.
At the beginning of flooding %in. or 3-in. pumps mounted on hand sleighs are used. This past season a Typhon pump was used which has the capacity of a 4-in. pump.
The procedure is to concentrate on the 1,000 ft. long haul road. Pumps of 4 i n . size are used and the ice is built up to a thicknesv of 30 in. to 36 in. for a width of 150 ft. to 200 ft. While the main haul road is being concentrated on with pumps the main area of the dump is dragged with a snowmobile and later with a roller.
The unloading procedure consists of unloading the wood on the inshore portion of the dump working the wood out in rows up to 8 ft. high parallel to the shore. If flooding occurs from the weight of the wood the unloading point is changed but the flooded area is returned to as soon as possible to continue filling the landing area from the back.
Compacted snow is graded into the wood so that after each grading there is a 50 ft. width of cleared dump for the trucks to work on.
Abilibi Power & Paper Company, Limited
-Smooth Rock Falls Fibre Llivision, Smooth Rock Falls, Ontario
At this division no pulpwood landings are used but several ice bridgea are constructed across the Mattagami River.
The approaches to the river are bulldozed to give as gradual a slope as possible. Shell ice formed early before the water level dropped must be broken down. If the approach from the bank is too steep a log ramp is. built up and frozen into place with water and snow. At least 6 in. of frozen slushed snow is placed over the top of the log ramp to prevent wheeled vehicles from loosening the logs.
The width of the ice bridge will depend upon usage. If to be used with loads up to 15 tons it is made 75 f t . wide. If the maximum load is 50 tons it is made 200 ft. wide. If the ice bridge is t o be used as a crossing as late as possible in the spring the bridge should be 100 ft. to 150 ft. in width. If only to be used in January and February the width is reduced to 50 It. to 75 ft.
Snow from the surface of the river ice is shovelled u p into retaining walls a t the required spacing. The snow is then wet down and allowed to freeze. If there is not sufficient snow present to form walls 8 in. to 10 in. logs are frozen into the ice.
When flooding the ice bridge a 4-in. pump is used. A 30 ft. to 40 ft. hose is used. The intake holes for pumping are cut well back from the ice bridge.
The depth of flooding a t one time depends upon the prevailing temperature. If the temperature is -0" F., 2 in. t o 3 in. can
be pumped on. S o flooding is done ur~til the water pumped on the surface the previous day is frozen solid.
Ko reinforcements are used in the ice bridges.
One ice bridge 200 ft. wide with ice thickness ranging from
28 in. to 38 in. was used to haul some 25,000 cunits of wood in truck trailers with average gross loads of 40 tons a t speeds from
10-15 miles per hour.
Abitibi Power & Paper Cornpnrt y, Lilrritrti -Iroquois Falls, Ontario
Two main ice landings are usc,d: (a) a landing located in the northeast corner of the most northerly hay in Lake Abitibi; (b) a landing on the Mistango I t i v ~ r .
(u) T h e average depth of I.ake Abitibi is 7 ft., and there is no place in the entire landing nrea where the depth of water exceeds 15 ft.
Extra work is involvetl in the lake d u m p as there is a river outlet netlr the point where the hauling road comes down onto the ire. A wooden b r i d ~ e of logs is placed in position prior to freeze up ant1 is frozen ~ I I by flooding with pumps.
T h e first step in preparing the landing is to flood the ice, surfac-e with water using light sled mounted pumps. As soon as the ice can support it, a large pump of 40,000 gallons per hour capacity is used.
T h e areas to be utilized early in the season are treated by flooding. Ijmgging and rolling prepare the rest of the dump for t h e latter part of the season. This latter technique is as follows: (i) When there is 4 in. to 6 in. of ice or more, a light snow- mobile is used t o pack the snow and have the water come up through it.
(ii) When the slush has frozen the operation is repeated with the snowmobile pulling a light drag.
(iii) T h e snowmobile next pulls a light wooden roller over the d u m p surfacae; n roller 4 ft. in diameter and 8 ft. in length.
(iv) At this stage the ire is of sufficient thickness t o support a light tractor of the 1)-4 class pulling a large roller, 8 ft. in diameter and 15 ft. long.
When the ice is 18 in. thick, trucks with half loads are allowed to go out on the ice. These units would have a G.C.W. of 71,000 Ib. As the ire thickens up to 24 in. the loads are increased up t o
In t h e early stages of the haul the trucks are kept to a speed of five miles per hour or less. Later in the season this is increased t o 10 m i l a per hour
Sometimes equipment breaks through the ice in extremely cold weather. As the (:old inc~reases the ice contracts and causes cracks to appear in the surface of the landing. Great care is taken t o make sure t h a t heavy loads d o not pass over p1:icel; where two or more cracks come together.
A problem is sometimes caused by the formation of a 1:tyer of ice during a thaw and rainy period so t h a t the ice formed was full of long vertical bubbles. This ice lacks strength so t h a t with the normal thickness of ice it is unable to stand up t o loading and equipment breaks through.
Cracks in the ice have been mentioned above. The policby followed a t this division is to avoid them as soon as they appear.
If water seeps through a crack it is considered serious because the crack extends right through the ice layer. If no water is present the crack is not regarded with alarm.
Snow drifting is not a problem. A pile of wood is dumped right around the edge of the landing to serve as a snow fence. (b) The river pulpwood landing covers some 200 acres, holds
48,000 cords of wood and is located where the river is normally very sluggish. T h e channel is from 30 ft. to 50 ft. deep.
When the ice is 6 in. thick a snowmobile is used t o pull light
rollers. 'I'he first 1.011er used is mado from a 24-in. diameter culvert, 16 ft. long, :trtd reinforced with %in. discs every 2 ft.
Next a larger roller 4 ft. in diameter. 16 ft,. long, reinf0rced with a 4-in. wooden disc every 2 ft. 'I'his roller is (:Overed with a heavy gauge galva~~izeti iron.
When the ice has attai~lctd a thic~kncss of 13 in.. a 1)-3 trac*tor is employed to tow i~ 6 ft. diameter, 10 ft. long roller. 'I'his
roller is sl~rfaced wit,h :I double thickness of 2 x 4 I r ~ n ~ b e r ,
reinforcted wit,h &in. \vood(.n discs spaced a t 2 it.
St. . l n n e Power Co~npatr!j, Hranprr, (Jti~bcc
"The years follow one after the other, hut they are never the same". I n other words, the local prac-tires are affected to a marked degree by the weather caonditions prevailing during any particular season
I t is not lo(-a1 pracbtic~e to prel,al.e lake la~ldirlgs for heavy wheeled vehicles. 13ecause of heavy sr~owfall the hauling of pulpwood is scheduled t o finish February 1st. I:sually con- ditions prohibit thv po~liibilit~y of getting on lakes with trucks before .January 1st and by t.hat time there is so much snow it cannot be re~noved
In general no tra(:tors over 50 h.p. 01. \veighing I I ~ ~ I I . ~ t,har~
12,000 Ih. are taken out on lake ice.
T h e preparation of the landing for various e'li~liatic~ (*o~l(iiti(~~ts is as follows:
2 in. ice; no snow Floodir~g ro:td\vays in ~ , r d r r t,o start.
2 in. ice with snow, dry Flooding road\vays.
2 in. ice with snow and Breaking down snow- YO water will
water freeze, done with men on sn~~wshoes.
4 in. ice with snow, dry Flooding roadways.
4 in. ic-e with mow and Breaking d o w ~ l snow so svater will
water freeze, done by holne anrl dragging
5 in.-6 in. ice with snow, Flooding ~~oaciways.
6 in. ice with snow ant1 Breakins down snow with snow-
water mobiles or J-5's equipped with racks
and 6 gasoline drum outriggers, so machine will float if ice gives \ray, completely.
7 in. plm ice, wit.h Breakir~g down sno\v with srrow-
snow7 and \ v ~ t , e r mohiles or J-Ti's usually equipped
with a single long pole c-l,ossnrays at, the rear, so if the rear cud of t,he machine go= through the ice the pole \\-ill keep the motor from water damage. 'I'he hmt method for hreak- down snow and slush with a .J-5 or sno\rmobile is in reverse with a mini- mum amount of power, so lugs d o not, spin. If going is too heavy, stop and :tdvanc*e. Sever force lugs to hreak t.hrough slush t o solid ice bvneath. All annwmot~iler: used in preparing Inndings have top t r a p doors.
Most sinkings of hauling equipment occLur on the secor~d or third day of the haul. 17sually the weather is cold and there is no water on top of the ice \\here the unit goes down. [ t is usually very sudden and the hole quite large, and it is usually the first trip in t h e morning near where wood had heen dumped the previous evening in apparent ~ a f e t y . Attempts are made t o avoid these sinkings by changing the dump locations so water will come u p on the ice which seems to relieve the stresses started wit11 same loading on dry brittle ire.