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APP 18 1995
rO GIVIL ENGINEERING ANI
TING & McGRAW-HILL COMPA
April 16,1925 .
Plugging a High-Pressure Service Tunnel
Difficult divers’ work in tunnel 8o feet below ground was one of the essential operations of connecting new Buffalo, N.Y., filter plant to city’s distribution system.
/Z
Experience with Wood Grating in Filters
What Sacramento, Calif., can recommend from a year's comparison of wood-grating underdrains with perforated-pipe laterals for its two groups of rapid sand filters,
Garza Dam for Dallas Water-Works
Hydraulic-fill dam will store 63 billion gallons for the water supply of Dallas, Texas. Cost of project covered by a $5,000,000 bond issue voted during 1923.
Dam Floods Danville Water-Works
Hydroelectric dam on Dix River inun- dated Kentucky citys pumping plant and filter. New pumping station must meet 7o-foot variation in level of river.
Every: Day Water-W orks Problems Solved
Twelve pages of short articles on construction, maintenance and operation of plants, and methods in treatment and filtration of supplies. These articles cover as many states as there are articles and represent primarily waterworks practice in small municipalities.
WATER-WORKS NUMBER
wie
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Market—ENGINEERING
—and for waterworks roofs...
So general has the use of Federal Cement Tile become that every industry and every type of public building includes several important installations. It has found favor with officials everywhere for waterworks roofs.
The two photographs reproduced here show a characteristic waterworks instal- lation. There are many such; some larger, some smaller, but all on water- works structures where invariably it is immediately apparant that the effort throughout was to procure the best of materials.
NEWS-RECOR D—Paace Vol. 94, No. 16
Detroit Water Works, Detroit. Mich. Coal Storage roofed with Federal precast channel slabs
Federal Cement Tile are made for all Hat and pitched surfaces in four styles: Interlocking, Glass Insert, Channel and Flat Slabs. Strict supervision of manu- facture in a modern daylight plant and the use of high-grade materials insure uniformity. Scientific design and proper steel reinforcement impart ample strength and durability. Made, laid and guaran- teed by FEDERAL CEMENT TILE COMPANY
608 8. Dearborn Street CHICAGO
FEDERAL Cement ‘Tile The Roof} jor Permanence”
ing.
Interior view Detroit Wate
age. Note that Federal channe roof slabs also serve as the ce:
ENR4-161-RT
— ** Game \
A Consolidation of Engineering News, Engineering Record and The Contractor
NEWS-RECORD
McGraw-Hill Company, Inc. James H. McGrRAW, President E. J. MEHREN, Vice-President
DEVOTED TO CIVIL ENGINEERING AND CONTRACTING
Volume 4 NEW YORK, APRIL 16, 1925
Number 16
Small Town Water-works
HE articles selected in recognition of this year’s
annual convention of the American Water Works Association relate chiefly to the problems of water- works in what for convenience may be called “small towns.” These problems are many, varied and in- teresting, and they require engineering ability of no small kind, especially in view of ofttimes limited financial resources and the frequent need of adapting improve- ments to a conglomeration of plant too costly to be dis- carded entire if even in part. This the articles attest.
Manual of Water-Works Practice
INCE the American Water Works Association has
got down to substantial work between conventions, its annual meetings have improved and the water-works fraternity is being better served. The Louisville con- vention, during the week beginning April 27, will visual- ize a large part of the efforts of its Standardization Council in bringing out a Manual of Water-Works Practice. Material is available for more than 600 pages representing 80 per cent of the text on the seventy-five topics which the Standardization Council outlined as necessary to treat. Not the last word has been said by the numerous workers on the various subjects, and on many of them changes will be brought out by discus- sions at the convention. If nothing else were on the program but discussions of these best-practice chapters of the manual, water-works operators would find the convention worth attending.
Industrial Co-operation
APITAL and labor got together in the first of the
projected series of “Industrial Round Tables” in New York last week. The Secretary of Commerce, the president of the American Federation of Labor and the president of the General Electric Co. spoke, and these representatives of the public, labor and capital, respectively, voiced one sentiment—that co-operative effort must be made to reduce that greatest of national wastes, the once-called irrepressible conflict between employer and employed. This is no new sentiment; it has appeared from time to time ever since labor learned that it had rights and capital realized that it had responsibilities. But there were indications in this latest meeting that something real would be ac- complished by these meetings. Mr. Hoover voiced this something in his introduction, when he made again his familiar plea for a self-correction of the ills of indus- try. Government, in the Secretary’s philosophy, can do little to straighten out business ills, except to pro- vide means for those who might correct those ills to come together. Co-operation is a hackneyed word, per- haps, but Mr. Hoover has made it live and workable, and he proposes here that its force should be applied
to those industrial troubles which reach back to the wilfulness or selfishness of either of the two great elements in industry, capital and labor. And the re- marks of both Mr. Green and Mr. Swope rang true. Neither seemed to be speaking for effect, as too often such leaders speak. They both know, and their words and manner showed it, that to forge ahead or even to keep the pace, American industry must recognize the mutuality of all of its interests and discuss,- and settle, its problems on the basis of that mutuality. One meet- ing does not make a program or settle a problem, but this first one is promising of welcome results.
Legislative Road Maps
LESSON to state legislatures on highway location
practices is repeated again this year by Governoi Smith of New York in passing on new legislation in- creasing the state road system by some 2,400 miles. Designating the bill as being “as near to a perfect plan as we can possibly get under our existing system” the Governor approves the act and says: “Laying out highway routes I do not believe to be a legislative func- tion. It is an engineering problem and while it re- mains a legislative one we will never be able to resist the temptation to lay out new routes as the result of log-rolling projects in the legislature not strictly des- tined to improve the state highway system but rather to promote the interests of some localities.” So rarely has a state chief executive visioned highway system location as clearly as has the governor of New York that his remarks stand out among the official utterances on highway administration of this very active year in road legislation.
Unprofitable Waterways
NLAND waterways advocates will find little consola-
tion in the forthcoming report of the Board of Engi- neers for Rivers and Harbors on the proposed Lake Erie-Ohio River canal. Colonel Kutz, in a preliminary announcement extracted elsewhere in this issue, states that while all three of the proposed routes are feasible from an engineering point of view, they are not eco- nomically desirable, that on two of the routes the fixed charges would greatly exceed the prospective benefits and that the third route when operated to capacity would yield benefits approximately equal to the fixed charges with the present inequalities in competitive freight rates, but that with those inequalities removed, as it is reasonable to expect they will be, the third route also would be economically inadvisable. This cold drench of elemental! fact will not be welcome to our waterways dreamers. They do not or will not understand that the cost of the long distance haul is a relatively small
»part of the. cost of handling freight and that time and
certainty of delivery have a much higher value than 627
FrRaANK C. WIGHT Editor
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628 ENGINEERING NEWS-RECORD Vol. 94, \.. 16 they did in the days when canal and river traffic flour- narily they are not critical, since no previous tr: \}J.
ished in this country. They may not yet be convinced ‘that these conditions are applicable to the canal which they have been advocating for years between the Ohio and Lake Erie, but it is fortunate that Congress, when- ever it comes to consider appropriating money for this canal, will have definite figures placed before it.
Road Form Precision
ORMS for concrete road construction are being more
precisely specified by highway engineers. This fact should be regarded well by contractors—it is the final fraction in precision that costs high in setting road forms. This fraction, too, is getting to be mighty small. In the last revision of the form specification of an im- portant road-building state the allowable deviation in line and level of any 10-ft. section of form top is x in. And “the engineer may require the contractor to oper- ate finishing machine and subgrader over forms prior to starting of construction that they may be inspected to determine whether the same will remain true to line and grade during construction.” In brief it is required not only that forms shall be built to very precise line and grade but that they shall remain exact under the rather strenuous duty of being a track for finishers and subgraders. And in these same specifications the track rail may not have “been in use on more than ten miles of roadway on other projects.” This limita- tion on the working life of forms needs also to be noted by the contractor in making his bids. In urging notice by contractors of the effect on costs of more exacting road form specifications no criticism is implied. If true road surfaces are essential then exact form setting and maintenance are required. As everywhere in construc- tion, however, greater perfection brings greater costs and contractors cannot afford to overlook the fact.
Unexplored Conditions
OMETHING of a mystery presents itself in the case
of the Oklahoma oil tank failure, described on p. 638. A large tank ruptured and its contents burned, the fire spreading over a large area and threatening many other tanks but fortunately wrecking only one besides the tank of origin. Apparently the known facts as to the causation of the fire are that the contents of the first tank burned and that the tank ruptured, the two events occurring either simultaneously or one be- fore the other—no one knows which. Thus the cause is a mystery. Commonly, mystery implies ignorance, and in the present case some of the elements essentially involved in the case are matters about which we know little. One of them is the effect of a large change of temperature occurring very suddenly, as happened in the period immediately preceding the accident. We know that a 60-deg. drop in temperature produces a deformation corresponding to a stress of 10,000 lb. per sq.in. and we can reason that if shell and bottom of tank differ in temperature by 60 deg. a set of forces corresponding to a tension of 10,000 lb. per sq.in. in a small ring along the base of the tank shell will have to be taken up somehow in the form of complex reactions between shell and base. But we do not know much about the resulting stresses. Apparently the stress con- ditions are not susceptible of analysis ’or other than the roughest kind of estimate. -We may infer that ordi-
due to differential expansion or shrinkage of this king has been reported. But it is quite possible that «he, can become critical in some cases, and they ma» by» large in all cases, at least large enough to warran investigation. The mechanical condition of the tank again represents unusual and unexplored condit..\ys:- The combination of welding and riveting, especial): th. welded connection between base of shell and the curb angle around the tank bottom. Such welded connec. tions, and more particularly combinations of welded anq riveted construction, are relatively few, and experience with them is limited. It is not known how they wi] behave under all sets of conditions. Thus, it may he that the welded base connection was subjected to ab. normal service by the tendency to distortion that arose from the temperature drop preceding the accident. The part played by such possible factors in the Ponca City tank failure is likely to remain obscure until experiment and experience improve our knowledge concerning the strength of steel tanks.
Lessons from Weeping Water and Chicago
ERHAPS superintendent who deliberately
wrecks a water-works filtration plant because he is lazy and competent, is less rare than the one who is energetic but incompetent. Into the former class, seems to fall the individual who ran the little plant at Weep- ing Water, Neb., described elsewhere in this issue. No one but a clever genius would think of rearranging the piping to reverse the direction of filtration, punch holes in the strainers to reduce the head, replace the sand by coarser material and consign the coagulant apparatus to the junk pile. To make these chanye: required effort, so he may have been more well-inten- tioned than an off-hand opinion would indicate in his endeavor to make the plant work without attention.
Before condemning people as indolent it should be remembered that the automatic shifting of steam en- gine valves was first done by a lazy boy who tired of doing it by hand. Perhaps the Weeping Water super- intendent felt he had fallen on a boon to operators in his attempt to make an upward flow filter, one that would run continuously without washing; but such at- tempts, like revolutions, must be successful to be justi- fied. Unfortunately for the Nebraska “inventor” his scheme was a failure, and some one happened along who saw that influent and effiuent were equally turbid. The washing problem: that irked the operator had been solved at the sacrifice of the main result, and the citizens had to pay for and consume the unsavory product.
As has been said so often in these columns, science— represented here by the filter plant—applied without knowledge too often gives the people a false sense of security. No doubt the local officials continually boasted of their filter plant as affording full protection from water-borne diseases,
In a large city, where so many lives are in jeopardy, competent operation under the watchful eye of the best scientific talent is even more essential than in a small one. Only last year Chicago learned boasting of the purity of its water supply at the intake cribs did not mean a safe supply at the tap. ‘Passage of water through a leaky tunnel system beneath city honey-
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ENGINEERING
NEWS-RECORD 629
April 16, 1925
ec.abed with underground conduits resulted in a bac- terial content higher than that of the original lake rater.
a is not the intention to intimate that the Weeping Water superintendent has a counterpart of incompe- tency in Chicago, but to point out that scientific investi- gators can and do find weak points in a system; weaknesses that come about from changing conditions. So long as Weeping Water got its supply from wells it was safe. Until Chicago, to meet the exorbitant de- mands of an unmetered consumption, got to pulling down the water levels at the pumping station ends of its lake tunnels and the areas surrounding the nu- merous land shafts became congested, the groundwater head of water surrounding the land shafts and tunnels was low and seepage was insignificant. Now the pollu- tion is so serious that to counteract it as much as may be the limit of chlorine dosage of the water before it enters the cast-iron pressure system has nearly been reached. Long ago the chlorine taste limit was passed. So serious is the difficulty that for the first time filtra- tion has been publicly advocated by John Ericson, city engineer.
Both Weeping Water, the town of a thousand, and Chicago, the city of three million, have had lessons as to the danger of incompetent supervision of a water fil- ter and of lack of sanitary supervision and delay in providing filtration when changing conditions demand it. Such lessons may well be heeded not only by those cities but also by towns and cities small and large the coumtry over.
What Is a Water-works Man
HE ten thousand water-works of the United States
and Canada present a number and variety of prob- lems in design, choice of material, construction, as well as in physical, chemical, bacterial, financial and other phases of operating control, that would make a sur- prising category if assembled. Put alongside this cate- gory an outline of the relationship of our water-works to manufacturing and other industrial processes, to the safety of homes, protection of offices, shops and fac- tories against fire, to the comfort, convenience, health and life of some scores of millions of human beings and the exhibit would be still more surprising and sig- nificant. A hamlet too small to have a public water supply is handicapped by that lack and the watered town or city would be crippled in a few hours, decimated in a few days and depopulated in a few weeks if the water supply were cut off with no certainty of speedy restoration.
Who designs, builds and runs the water-works of the country? Many of the smailer ones, and even those of considerable size built in the earlier days, never were designed, as the term is and should be understood. They were built more or less haphazard, or if not they have been extended in that fashion. Today, a large percentage of even the small plants and plant exten- sions are put in the hands of more or ‘ess competent engineers and the percentage is increasing. For the larger works and major extensions most of our city fathers have recognized the necessity of engineering service, either temporary or permanent, from the start, Today, for water-works large and small, there are many more engineers engaged on water-works large. and
small, there are many more engineers engaged on water- works design and construction than in any other branch of municipal work. As for water-works construction, the works or extensions having been designed, the engi- neer is more and more in evidence.
Contractors and manufacturers have always played a large part in water-works design, either for entire plants or their important elements. This was particu- larly true for works in the earlier days, even in places of considerable size, and notably for pumps, filters and, in many of the smaller places, for pipe systems even if not for the entire plant. Much of this designing was well done, even though it did go far towards eliminating competition. In construction it was but natural and as a rule desirable that contractors should build original works and major extensions.
Once built, and taking numbers rather than size into account, by far the larger number of the water-works of the country have been and still are operated by men without engineering education or experience. Happily this, too, is rapidly changing, for whereas thirty years ago only a part of the large cities of the countries and a few progressive small ones employed engineers as superintendents and managers, today hundreds of cities and private companies do so, while numerous cities have a good-sized staff of civil and sanitary engi- neers regularly employed. With these may be men- tioned the small army of chemists and bacterioiogists that could be assembled from the water-works plants of the United States and Canada.
Since the advent of the city manager, the water- works of scores of smaller places have had the benefit of more engineering management than before, either from the managers who are engineers or because of the building up of better technical staffs under the city managers than existed under the old decentralized hap- hazard administration.
What is the job of the water-works man in building or operating works? First of all, he must see that a given city has water from a source that is safe and can be made safe by treatment carefully chosen to meet local conditions. He must see that the supply is always ample in volume and pressure, and above all free from danger of infection, which means safeguards in design, sound construction, never failing supervision, and swift emergency repairs. Whether it be the engineer or some other official, someone must look after a hundred wants and caprices of individual consumers. Someone must provide sound financial control. Essentially the job is an engineering job and as such it can best be done by an engineer, if not as chief administrator, in the larger places, then at least as bureau head.
But whether engineer or not, the waterworks man will be benefited by the contact he gets from member- ship in the waterworks associations. Constantly for half a century. our two major associations have been contributing to the progress of water-works design, construction and operation. They deserve better sup- port than they have received from the municipalities and private water companies of the United States and Canada. Even the larger of the associations has but
2,200 members—small when it is remembered that there
are ten thousand or more water-works which should have from one to a hundred representatives in one or the other association. Those that belong and take active part can handle better their job as water-works men.
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630 ENGINEERING
NEWS-RECORD Vol. 94, No. 16
Garza Dam for Dallas Water-Works Will Impound 63 Billion Gallons
Hydraulic Fill Utilizing Floating Equipment Dredging in Sand, Gravel and Clay Layers Carefully Prospected—Puddle Core Trenches with Steel Sheetpiles—Double Set of Spillways
ALLAS, Tex., has now under construction a
hydraulic-fill dam across the Elm Fork of Trinity River, near the town of Garza, 26 miles northwest of the city. A reservoir of 63 billion gallons capacity will be formed to store water for municipal purposes only. A bond issue of $5,000,000 was voted in April, 1923, for the construction of the project. The reservoir has a drainage area of a little more than 1,100 square miles over which the average annual rainfall is 35 in. Features of this work are the choice of site, decision to utilize a less favorable material near at hand, mixing of sand, gravel and clay or gumbo layers, after diligent
prospecting by an elaborate system of borings, core trenches with a single row of steel sheetpiles encased jp puddle, and two spillways, one of concrete for reyular service and a second for emergency use in a low ridge.
The water-works system of Dallas, which now serves a population of 225,000, together with numerous manv- facturing industries, has a total storage of about 7 billion gallons impounded in five reservoirs, the largest of which has a capacity of about 5.5 billion gallons The Garza reservoir will make available about ten times the present storage and should serve from three to five times the present population, with allowance for in-
gravel roadway grave/ 500 | Wand chay ~~f2" rock riprap Selected ted material’ 4 \e*Gravel blanket asol. ‘Note:Original ground to be Core trench |. Chared of a// tation and Steel A | Furrows p/ 6” deep on (Omit piling south of river) | S’certers parralle! to center of line of alam Typical Section of Dam / service ifs \ tes hs Begining of wise & ( | earthwork WS Scale in Feet 1000 1500 Pian — core gravi Section Top of stee/ sheet pili Apron El. 4570 Bottom of core A £1447 Profile Looking Upstream 100 36
FIG. 1—GARZA RESERVOIR HYDRAULIC-FILL DAM, GENERAL PLAN AND PROFILE
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4
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16
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April 16, 1925
53
ENGINEERING
NEWS-RECORD 631
FIG. 2—THE DREDGE ITS WAY ETTER MATERIA
Launching pit right. The floating line is the waterproof electric cable.
creased consumption due to additional industries and normal increase in domestic per capita consumption.
The Garza dam site lies in the Woodbine beds of the Lower Cretaceous, which are composed of alternating irregular beds of sands, shale and sandstones. In general this formation, on account of its permeability, is not well adapted to the economic construction of dams and as a consequence the total cost of this dam in particular will be considerably greater than is ordi- narily the case for more regularly stratified geological
sites in the vicinity of Dallas as conforming, more nearly than any other site, to the prescribed specifica- tions, which were that the reservoir must impound in excess of 50 billion gallons, and cost not to exceed the proceeds of the sale of the bond issue.
Preliminary drillings at the dam site disclosed a fairly uniform foundation of shale at reasonable depth to which core trenches could be excavated, and subse- quently be filled with puddled clay or interlocking steel sheetpiling. The floor of the valley above the dam site is quite uniformly overlaid with an alluvial clay blanket from 5 to 20 ft. thick.
The clay blanket, however, overlies sand and gravel deposits of varying thickness which, it was decided, would form, with the clay, a mixture suitable for hydraulic filling and hence this class of dam embank- ment was prescribed. An electrically-operated suction dredge was installed, having a capacity of about 250,000 cu.yd. per month. The 20-in. dredge pump is directly connected to a 1,600-hp. 2,300-volt alternating-current motor and discharges through a 20-in. pipe on to the dam. A total of 2,000,000 cu.yd. of embankment will be placed by this dredge.
Material—A strip of ground lying upstream from the dam and adjoining the 300-ft. berm to be left at the upstream toe was investigated for a borrow pit for the hydraulic fill. This strip is about 2,000 ft. wide, par- allel to the river channel, and is about 6,000 ft. long
formations. However, the site selected was chosen after detailed examinations of eighteen other possible across the valley. The borings over this area were l2" gravel Gate and machinery house---- high op of am £1. 540.0 Tike siope drains about 300" centers to toe of dam Above S25 riprap /2" thick _ < ty “6” sewer pipe, intet and outlet to be grouted paving Spillw crest E/ 5c 250 , 2 “ora loP® Sana gravel > 2" and thay Limitsof™ \ Material laced /clay core by the .Jocontform fo 4:kslope 3:1 Gravel blanket selected fill process fort to 6"Dipe left to Finish pouring plugs- Sh Rertition wail 460.0 Direction of flow F1\4580 Gare valves, fittings and to be placed after ‘Valve At | a | Flood nazare’ is pas 4 are valves, and 2~ /8” chambe pipe ains> le Le gate valves. 4 s 48"C pipe ana / line 18"C Lpipe) rave/l Section B-B During _time of placing gate valves and plugs sudden ma be led by the hid stop logs placed at inlet to conduits = Collars? of slope paving --~ > 2 Plan of Conduits crest Construction £i yAspha/t filled
Jonts-- <4
Section of Conduits FIG. 3—CONDUITS FOR CONSTRUCTION OUTLETS AND FUTURE CONTROL, AND SECTION OF SERVICE SPILLWAY
+
“Gravel drains?
/ construction every 30' to $0"
““Note: 7unne/ s/opes
2%: | slope~ end of spi//way £/ 470.38 ‘These two drains 14:1 slope “Bottom of end connected every 50’ pi Blue 563" A: Note: foundation of spillway wi/l shale |. 14 be bive shale and sand stone
tile drains land in gravel sloped / per cent from center to pipes through paving at ends
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632 ENGINEERING
NEWS-RECORD Vol. 94, 16
made by hand with an 8-in. post-hole auger and the holes were spaced approximately 400 ft. each way. Where loose sand or gravel that would cave was struck the holes were cased with 6-in. pipe and cleaned out with a 4-in. sand bucket down to the shale or sandstone.
The investigation showed that of 9,000,000 cu.yd. of material available above the rock in this area more than half of it is undesirable for hydraulic-fill con- struction because it is clay containing only a small amount of very fine sand and no gravel. This large body of undesirable material is about in the middle of the valley along the river channel.
On each edge of the valley there is a considerable body of material overlying the rock from 15 to 25 ft. deep running from 25 per cent sand and gravel and 75 per cent gumbo and clay to 100 per cent sand and gravel. The most of this more favorable material is located on the south edge of the valley and is very similar to the material used for the storage dam at Wichita Falls (see Engineering News-Record, Dec. 20, 1923, p. 1004). There is enough of this latter material to build the entire dam but it would require an average pipe line length of about 4,000 ft. and a maximum of more than 6,000 ft. This length would require a booster and would otherwise restrict the output of the dredge and add to the cost. |
The less favorable material can be placed on the dam with an average pipe line about 2,500 ft. long, and it seemed worth while to give this material a thorough trial. It usually runs from 2 to 5 ft. thick of black gumbo on top of a very tough brown clay underlaid by sand and gravel. This gumbo and clay is hard to cut but reaches the fill in balls ranging in size from 4 in. to 10 in. in diameter. Even where there is no gravel mixed with these balls they make a surprisingly com- pact fill, A man can walk over this fill to within a few feet of the core pool while it is being pumped in, but in order to get on to it to build up the outside levees with a crawler-tractor-operated dragline it is necessary to use mats, which is not the case with a gravel or sand fill.
All of this clay contains considerable very fine sand but the pumping has not proceeded far enough yet to say what percentage of it is going to be lost through the core pool. It is evident, however, that there will be considerable surplus core material if a large percent- age of this clay and gumbo is used.
Embankment—The total length of the dam is two miles and the maximum height will be 80 ft. The upstream slope will be 3 to 1, and the downstream slope also 3 to 1, but modified to admit of two 8-ft. berms being placed 20 and 50 ft., respectively, below the top of the dam. A top width of 30 ft. will provide room for a graveled highway. A freeboard of 15 ft. is pro- vided between the top of the dam and spillway crest. The upper slope will be protected throughout with 18 in. of limestone from Stringtown, Okla., hand laid on 8 in. of gravel.
Across the main valley of the river for a distance of 3,500 ft. a core trench, having a bottom width of 12 ft. with side slopes of 1 to 1 and varying from 25 to 30 ft. deep, has been excavated to ground-water level, in which a single line of interlocking steel sheetpiles weighing 35 lb. per square foot has been driven to the under- lying shale. The piling extends up into the trench a minimum distance of 6 ft. and will be encased in the
clay puddle core pumped in by the dredge. A ‘ota! of 121,925 sq.ft. (2,134 tons) of piling varying in |)» yt) from 14 to 45 ft. has been driven.
All core trenches were excavated with a draw line. electrically operated, having a 5-cu.yd. bucket and 100-ft. boom.
For the control of flood water during the cons: ruc.
“4
FIG. 4—BEGINNING THE HYDRAULIC FILL BETWEEN THE WALLS PLACED BY TEAMS
The embankment on each toe was placed from the core trench and conduit excavations and wet down.
tion period, concrete conduits are being installed in the river bank immediately south of the channel, of a total length of 465 ft., including inlet and outlet, and con- sisting of two oval-shaped barrels having a major (vertical) diameter of 19 ft. and minor (horizontal) diameter of 14 ft. These conduits will have a discharge capacity of 12,000 sec.-ft. under 44-ft. head, which will be sufficient to carry normal floods.
After the dam is completed two 48-in. gate valves will be installed in each conduit barrel, and one 18-in. valve in one barrel to pass water from the reservoir through to the river channel below the dam and thence to the city settling basins and filter plant at Turtle Creek for municipal use. These valves will be hand operated from the gate house on top of the dam.
Spillway—On the high ground south of the river channel a concrete spillway 560 ft. long and of ogee gravity-type section will be built with crest at sea-level El. 525, or 15 ft. below the top of the dam. The main body of the spillway will vary in height from 15 ft. to 25 ft. and will rest on hard shale. It will be connected with an apron 68 ft. downstream by a concrete slab 4 ft. thick constructed on a slope 2? to 1 and increas- ing to 1} to 1 at the apron floor. The apron will be at El. 457 and will be protected by a cutoff wall extending into shale 10 ft. below the floor level. The highway will be carried over the spillway on four 139-ft. steel spans.
At the extreme south end of the dam there are two low sections in the ridge through which flood water will be discharged in case of unusual and extraordinary floods. These will begin to discharge when the water is 10 ft. deep on the service spillway crest. For a depth of 10 ft. over the service spillway its discharge capacity will be 58,000 sec.-ft. and for a depth of 14 ft. the combined capacity of all spillways will be 135,000 sec.-ft.
Reservoir Basin—At service spillway level, El. 525, the reservoir will cover about 11,000 acres of land. It will have a length of nearly 11 miles, an average width of a little more than 14 miles and a maximum width of about 1? miles. The miximum depth of water at spillway level will be 65 ft. in the original stream
= A “4 4 44 — 4 x 4 we 4 €
ENGINEERING
NEWS-RECORD 633
April 16, 1925 bed only, and across the main valley will be 40 ft. The average depth over the whole basin will be about ig ft. By using flash boards on the spillway crest it will be possible to increase the depth of water in the reservoir 2 ft. and its capacity to 70 billion gallons at such future date as increased storage may be required.
To provide for policing the reservoir, and for in- creasing the height of water during high water stages the city is purchasing lands adjacent to the reservoir basin up to sea level, El. 535, or 10 ft. above the spill- way crest. In some instances additional acreage has been purchased in order to effect satisfactory settle- ‘ment with land owners, of which there were about 130 in the basin. In a few instances condemnation proceed- ings were necessary in order to acquire title to the lands. The average price so far paid has been about $70 per acre. While the larger portion of the basin is cultivated farm lands, about two-fifths of the area (4,450 acres) has to be cleared of large timber, under- brush and sprouts on abandoned cultivated fields. The clearing work has been begun under contract.
One designated state highway crosses the reservoir basin about midway of its length. There are several minor roads which also cross the basin. It will be necessary to elevate about one mile of the track of one railroad (the Texas & Pacific, east of Denton) about 5 ft. The highways will be taken care of partly by
FIG. 5—POURING THE SIDE AND CENTER WALLS OF THE OUTLET CONDUITS Floor has already been placed. The arched 7 will be the e
next operation. The conduit barrels end at t shoulders,
-— = the shale where the depression extends across the connecting them up with the road across the dam at the lower end of the reservoir and partly by con- structing an embankment across the basin about ten miles above the dam. This embankment will be 12 ft. high and will be surfaced with gravel. There will be a 100-ft. steel span across the stream channel and 1,150 ft. of creosoted-pile bridge opening additional. This valley crossing will be about 14 miles in length. In addition to this and the 2 miles of road on the crest of the dam, 9 miles of new gravel-surfaced con- necting highway must be built and 8 miles of existing roads surfaced with gravel. It will be necessary to take up 2 miles of existing 6-in. gas main located near the upper highway and to relay it so as to carry it across the embankment. About 30 miles of telephone
lines within the basin will have to be taken out, and connecting lines constructed along both the upper and lower highways.
This project has been carried forward by the caty administration, with J. C. Nagle and R. A. Thompson as engineers in charge, O. N. Floyd, principal assistant, J. L. Lochridge, designing engineer, and T. C. Shuler, resident engineer. The contract was awarded to the W. E. Callahan Construction Co. of Dallas, Tex., on Aug. 15, 1924. The Puget Sound Dredging Co. of Seattle, Wash., has the subcontract for the hydraulic fill.
Progress of St. Louis New Water Works on the Missouri
T THE new water-works plant of St. Louis on the Missouri River is being undertaken what is probably the most extensive and elaborate scheme for controlling and directing the flow of a big river ever attempted in municipal water-works construction. For a distance of five miles of river the banks must be protected and the channel forced and kept within the lines best suited to serve the water-works. In high water, which is 35 ft. above low water, there must be waterway enough to prevent the river from cutting away the banks at any point or from making a detour across the low lands. In low water, according to E. E. Wall, water commis- sioner, the river must be confined to a straight and narrow path in front of the shore intake of the water- works. All this requires a system of pile dikes, 26 in number, ranging from 100 ft. to 2,500 ft. in length, requiring more than 600,000 lin.-ft. of piling, over 2,000,000 sq.ft. of woven willow mattress, and 60,000 cu.yd. of stone for sinking mattress and bank revet- ment. There will also be required interlocking concrete sheetpiling along several hundred feet of river front at the intake to prevent bank erosion.
This work was started in August, 1923, and the river channel has already been forced over toward the lines desired. In another year it will probably be where it has been planned for it to run. The cost will approach $750,000 and such is the uncertain behavior of the Missouri River that any year may necessitate spending large sums for changes and repairs.
Construction of the low-service engine pit has given rise to interesting problems. The rock is about 70 ft. below the mean stage of the river and the general land level is some 95 ft. above rock. Above rock almost all the material is sand. The actual area covered by the intake and engine pit is 12,000 sq.ft., its largest dimension being 130 ft., so that the cofferdam had to be of the cellular type. A dredge was floated into the enclosure before the last cells were driven so that the excavation could readily be made over the whole area. More than 500 reinforced-concrete foundation piles, 15 in. square and 48 ft. long, were driven in this pit to rock, their tops, when driven, being 30 ft. under water. |
Work on the first 60-in. steel pump main has started. It will run across country through farms, across and along highways, through real estate subdivisions for 16 miles, from the Missouri River plant to the city. It is astonishing, says Mr. Wall, how valuable the land to be occupied by this pipe line has become. Within the space of a few months it has doubled, trebled and quadrupled in value.
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634 ENGINEERING
NEWS-RECORD Vol. 94, No. 16
Experience with Wood-Grating in Sacramento Filters
Delicate Hydraulic Equilibrium Requires Refined Calculations—Cemented Gravel Will Help if Strongly Made
By HARRY N. JENKS Superintendent, Pumping and Filtration Works, Sacramento, Calif.
UDGING by the number of inquiries received from
time to time, considerable interest is being shown in the experience with the wood-grating underdrains installed in the Sacramento filters. Lest the impres- sion be gained that the difficulties encountered in this plant in the operation of the filters equipped with false bottoms might be interpreted too broadly to mean that this type of underdrain is unsatisfactory in general, the following notes may be of value to designers who are considering the use of wood-grating or slat-bottom underdrains for rapid sand filters. Because of the somewhat limited experience at Sacramento it is hardly advisable to make any generalized statements, except that in theory the introduction of wash-water through a false bottom is fundamentally sound, though in prac- tice certain evident disadvantages present themselves, unless special care is taken to obviate them.
In the Sacramento plant four filters in the north group are equipped with wood-grating underdrains, while perforated pipe laterals are installed in the south group. Fig. 1 is a construction photograph showing a
‘ partly completed unit. The false bottom consists essen-
tially of 3x6-in. joists laid transversely to the filter on 4-ft. centers, upon which are mounted 2x4-in. stringers separated by spacer blocks so that a clear opening of i in. between the stringers is obtained. All the lumber is surfaced on four sides. In the photograph one of the joists is seen beneath the nearest wash-water gut- ter. Each pair of joists forms a separate compartment, or clear waterway, under the stringers, approximately 4 ft. wide by 12 ft. long by 6 in. deep. Wash-water is admitted into each bay through four 5-in. cored holes from a central header channel built below the wash- water drain trough that divides each filter in half.
From the time these filters were placed in service in April, 1924, it was apparent that what might be termed an hydraulic instability characterized their operation in comparison with that of the perforated-pipe under- drains. In general, due to relatively low resistances, any inequality in static head throughout the system has a correspondingly greater effect in producing uneven washing of the filter, as compared with the perform- ance of the perforated-pipe laterals. Therefore much more refined hydraulic calculations must be made in connection with the main distribution channel and ports through which the water is admitted under the false bottom. It has been found that as little as a 2-in. difference in water head along the main distribu- tion channel, which is 58 ft. in length, may be respon- sible for noticeable inequalities in rates of wash.
In addition to this circumstance, and in the Sacra- mento case of even greater importance, the wood-grat- ing underdrains were at the worst disadvantage because of the large amount of dissolved oxygen which, upon liberation from the water under negative head or other- wise, collected in the open spaces under the false bot- tom and from time to time escaped upward in a single mass. A most disruptive effect was produced on the
top layer of filter gravel, eventually resulting in the
breaking-through of the filter. An idea of the volume of air so liberated may be obtained from Fig. 2 which shows the surface of a filter being jolted to relieve air. binding. At times a 3-in. wash could be maintained for six minutes before all the air in the underdrain system was displaced sufficiently to allow the wash-water to spill over the gutters.
Use of Cemented Gravel Layer—As soon as it was concluded that the displacement of the top layer of gravel (3- to rov-in. size) was due primarily to air. hammer, efforts were made to remedy this condition by cementing this gravel in a manner similar to what has been done in Toronto and elsewhere. Over the lower lavers of gravel in one of the filters there was laid a 3-in. slab consisting of one part of neat cement mixed with nine parts of the top gravel by volume. Due to the exigencies of operation, it was impossible to ex- periment with more than one filter, and even with this one, a thorough test of the value of cemented gravel could not be carried out. However, sufficient informa- tion of an encouraging nature was secured to warrant investigating this matter further with particular refer- ence to the possible use of cemented gravel underdrains in the next group of filters to be constructed by the city. In this connection, the following general conclusions, based on experience already gained through the trial
“4 »* *
FIG. 1—PARTLY COMPLETED FILTER UNIT EQUIPPED WITH WOOD-GRATING UNDERDRAINS
of cemented gravel in one filter, will serve as a guide in future design:
‘1) The use of cemented gravel is thoroughly prac- ticable from the hydraulic standpoint; i.e., giving the required discharge with reasonable loss of head and even distribution through the slab.
(2) Greater mechanical strength is needed than that afforded by a 3-in. layer of 1:9 cement-gravel mix.
; x = fad 3 — = ¢ é J + “8 + be aft ix 4 ay
‘April 16, 1925 ENGINEERING
NEWS-RECORD 635
(3) This additional required strength can probably be obtained by increasing the depth of slab to about g in. and allowing it to act as a beam, with proper re- inforcement with wire mesh near the top face.
FIG. 2—LIBERATION OF LARGE VOLUME OF AIR DURING JOLTING OF FILTER TO RELIEVE AIR-BINDING
The results of the test showed that the cemented gravel layer as constructed would not be satisfactory because of local defects. In the west half of the filter the water broke through in several places, causing an upheaval of the sand bed. Similarly, a large blow hole developed in the east half, the upward rush of water carrying the sand over the neighboring gutter. Prior to replacing the sand bed, the gravel slab had been back-washed; at that time it was observed that in each half of the filter a longitudinal crack developed, indi- cating that the cemented gravel was acting as a beam spanning the 12-ft. width of the filter bed, and broke at the points of maximum bending moment and along a plane extending the length of the filter and roughly midway between the side walls of each half-unit.
Reinforcement Necessary—In using cemented gravel, it is evident that a correct balance must be struck be- tween the depth of gravel slab to secure mechanical strength and the resistance offered by that depth, in terms of the water uplift against the slab and tending to float it. This consideration is of more importance in case the cemented gravel is placed in small slabs or blocks which depend for their stability on their weight in water being greater than the upward thrust of the wash-water passing through them. If the slab is cast monolithically, which has an advantage in decreased cost of construction and a disadvantage in increased diffeulty of securing a uniform layer, it may be de-
signed to act as a floor slab to take upward thrust, so that the depth and consequent resistance may be made enough to secure the desirable property of offering appreciable friction to the passage of the wash-water. This tends to insure stable hydraulic conditions, mainly by compensating for the slight inequalities in static head underneath the whole system. It has been found that the resistance through the cemented gravel is remarkably small, the 1:9 cement-gravel mix at Sacra- mento showing only 0.15 ft. for an 18-in. vertical rise of wash-water per minute and 0.5 ft. for a 48-in. rate. It is considered that these losses are too small and are open to the same objection that the use of the wood- grating underdrains entails.
It is believed that the development of a cemented- gravel layer for use in conjunction with false-bottom underdrains should prove of great value in offsetting the disadvantages these underdrains have under certain conditions where a displacement of the top layer of gravel in the filter bed takes place. If the functioning of the wood-grating filter bottom can be assisted by a cemented-gravel slab, its cheapness of installation as compared with perforated-pipe underdrains will become of more importance than it is now. However, it still remains to be proved whether even this combination can excel the perforated-pipe underdrains for dependability under all operating conditions in respect to the produc- tion and maintenance of a uniform back-wash through- out the filter bed.
Somewhat approximate measurements of the loss of head that may be expected through a wood-grating underdrain system like the Sacramento design have been made and are given below.
—
LOSS OF HEAD WITH WOOD-GRATING UNDERDRAIN SYSTEM
Rate of Wash Loss of Head Vertical Rise Cubic Feet per Square Foot Feet Inches per Minute per Minute of Water 3 0.25 2.53 6 0.50 2.65 9 0.75 2.75 12 1.00 2.82 15 1.25 2.89 18 1.50 2.96 21 1.75 3.03 24 2.00 3.10
The loss of head refers to the static water head in the dis- ‘tribution channel required to produce the given discharge through the slat bottom, a 13-in. bed of graded gravel, and 34 in. of clean sand of 0.42-mm. effective size.
Designers will recognize the fact that, in comparison with the head requirements of the perforated-pipe underdrains, the slat bottom offers an advantage in lower frictional losses, particularly beyond the 12-in. rate of wash. Yet, as already explained, this advantage is of doubtful value in view of the delicate hydraulic equilibrium associated with these low resistances.
- Rheims Plans Canal Port Works Paris Correspondence
The municipal council of Reims, France, has decided to proceed immediately with a project for the construc- tion of a new port on the Aisne and Marne Canal. The city bought the greund involved early in 1914. The general plan calls for an expenditure of 2,400,000 francs, of which the national government is to take half of the charge. A credit of half a million francs has al- ready been passed with the stipulation that 300,000 francs of this amount will be devoted to excavation work to give unemployed labor something to do.
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636 ENGINEERING
NEWS-RECORD Vol. 94, No 1
Dam Floods Danville Water-Works Requiring Replacement
Rearrangement of Works by Putting Filters in City of Danville, Ky., at End of Four-Mile Pipe Line Lengthens Life 20 Years
By PAUL HANSEN Of Pearse, Greeley & Hansen, Consulting Engineers, Chicago
ONSTRUCTION of the high rock-fill dam for
power development in the Dix River Valley by the Kentucky Hydro-Electric Co. forced an unusual problem on the water department of Danville, Ky. This dam, described in Engineering News-Record, April 2, 1925, p. 548, has a total height of 250 ft. and, though 28 miles below Danville, will back up the water to a depth of 50 ft. at the site of the present Danville water-
Proposed highway
River pump- a ing station ip ine i £xisting 12” C-1 pipe- New filter plant ana pumping-station HF Danville Hey Map 1234
FIG. 1—DANVILLE WATER WORKS REARRANGED
works pumping station and filter plant. During flood stages the depth of water at the existing works may be as much as 70 ft. The Kentucky Hydro-Electric Co. was in consequence under the necessity of providing a new water-works for the city of Danville. This work was done under arrangement with the city whereby the city was permitted to select engineers satisfactory to the hydro-electric company and whereby the cost of the works was to be met by it.
The old water-works plant is located in the valley of the Dix River about four miles in a northeasterly direction from the city (Fig. 1). The water is taken from above a 16-ft. dam, filtered, and then pumped to the city through a 12-in. main about 20,000 ft. long. The difference of elevation between the Dix River and the city is 260 ft. Within the city is a standpipe 16 ft. in diameter and 150 ft. high, having a total capacity of 225,000 gal. and an effective capacity within the upper hundred feet of 150,000 gallons.
The population of Danville is about 5,500 and growth is slow. The average water consumption is a little under 1 m.g.d., about half of this being used by the Southern Ry. shops.
On account of heavy friction losses from Dix River to the city, it is often difficult to deliver water in suffi- cient quantities. The maximum rate at which the exist- ing steam pumps can operate is 1.5 m.g. daily. At times the rate of demand exceeds this, principally on account of heavy draft by the Southern Ry. shops. In view of the fact that the new plant is to be electrically operated it was feasible to place a raw-water pumping station at Dix River and build a filter plant and filtered- water service pumps on the edge of the city. By placing adequate storage at the city plant it becomes
possible to pump at a uniform rate through the }jn¢ line from the river during any 24-hr. period, or perhaps even longer, thereby greatly increasing the effec ive capacity of the pipe line with a given friction loss. ‘The permissible friction loss is also increased by redu ng the static head by about the height of the stand) pe. In fact it is estimated on the basis of the presont population growth that the effective life of the »\pe line has been increased not less than 20 years. As a replacement of this pipe line would cost approxima’. $120,000 this simple modification of the plant arranye- ment represented a material economy. There is a further practical advantage in having the main works in the city inasmuch as experience has shown that it is hard to keep laborers contented four miles from the city,
Pumping Station at River—The pumping station at Dix River had to be designed to operate with a water level in the river varying as much as 70 ft. To accom- plish this result a tall pump shaft of reinforced con- crete was built in the river valley just below the exist- ing water-works dam and adjoining an almost precip- itous cliff. Surmounting this shaft is a pumping station building (Fig. 2). Within this shaft are two 5-stage deep-well electric-driven impeller pumps, sus- pended from steel beams in the superstructure. A] bolts and connecting pins are of monel metal. An over- head traveling crane is provided. It is thus a relatively simple matter to raise and disassemble the pumps for repair and inspection. To insure favorable operation of the pumps, extra heavy shafts were used and the pumps and pump casings are supported by thrust bear- ings of extra large size. These precautions will keep the impellers in adjustment and avoid vibration.
— A2 “Discharge /t Stee/ cable. removable : placing rope y i with bronze J for 50-/b per 6 JI, &/b
wafer
“Stee! cable ser in concrete
ine
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Section A-A
Section J-J FIG. 2—RIVER PUMPING STATION TO CARE FOR 70-FT. VARIATION IN WATER LEVEL
bridge New D x \ | | at Y ; x = Pia Ais x | J Sard 720 A A 100 Rock 6 © 10 1? 1
ENGINEERING
NEWS-RECORD 637
FIG. 3—PUMPING STATION AND SHAFT, DANVILLE, KY.
Intake suction pipe passes through dam at right. Two gates . =, to take water at higher elevations when stream is flooded.
Each pump has a nominal capacity of 1.5 m.g.d. against a head of 346 ft., which comprises 260 ft. of static head and 86 ft. of friction head. The combined efficiency of the pumps and motors is approximately 66 per cent. Operating together, the pumps can deliver about 2.25 m.g.d. against a total head comprising the same static head as above and a friction head of 183 ft. There is room in the shaft for a third pump should it ever be desired, though at the present time this space is occupied by an iron stairway which gives convenient access to the shaft. This pumping station is controlled in its operation from the main station in the city.
Pumping Station and Filtration Plant in City—At the city station are a mechanical filter plant with a nominal capacity of 1.5 m.g.d., a 0.5-m.g. clear-water storage reservoir and high-service pumping station.
The filter plant proper comprises the following elements: (1) Chemical feed devices consisting of wooden storage tanks and the usual chemical feed boxes. (2) A mixing chamber with a retention period of about 15 minutes. (3) Two coagulating basins with a combined nominal retention period of 4 hr., so arranged that they can be operated independently in parallel or in series, with or without the mixing chamber. The retention period of the coagulating basin is made rather liberal because with floods in Crab Orchard Creek, a tributary of Dix River, the water does not coagulate and settle readily. (4) Three rapid filter units of the usual type, each with a nominal daily capacity of 500,000 gallons.
Special features of the filter plant are an unusualiy roomy and light pipe gallery and a large, light and roomy filter operating room. The superstructure covers the filters, mixing chamber and the ends of the sedi- mentation basins. The clear-water reservoir is made quite large so that it may tide over any interruption of pumping at Dix River that may result from break- downs at the pumping station or on the transmission lines. Because of the fact that power will come into the city from three different directions, it is believed that 8-hr. storage on the basis of the nominal capacity of the filter plant should be sufficient. Moreover, in a small city of this character it is feasible to check promptly water consumption by signal or otherwise. If the Southern Ry. shops are stopped from using water the consumption rate would be cut in half.
The pumping equipment includes a_ centrifugal wash-water pump operating under low head and capable of creating a rate of wash in the filters amounting to 24 in. vertical rise per minute, and three centrifugal service pumps with capacities of 0.75, 1 and 1.5 m.g.d., respectively. The largest pump, which will generally serve as a fire reserve, may be driven either by an electric motor or a gasoline engine.
An effort has been made to secure a good appear- ance of all buildings without extravagance. Because of the conspicuous location of the plant near the city, some attention has been given to parking and landscaping. A landscaping plan will be carried out during the coming summer.
The new works were designed and built under the supervision of Pearse, Greeley & Hansen, engineers, Chicago. The resident engineer was George B. Prindle. A. J. Authenreith and G. W. Hamilton represented the Kentucky MHydro-Electric Co. as engineers Henry E. Woolfolk, superintendent of water-works, and Anton Rehm, chief engineer of water-works, repre- sented the city. The contractors for construction work, including buildings were Cope & Fisher of Decatur, Ill. The contractor for erection of pumping machinery, piping and filter equipment was the Roberts Filter Manufacturing Co. of Darby, Pennsylvania.
Developed and Potential Water Power
The developed water power of the world in 1920 was about 23,000,000 hp., according to an estimate made by the U. S. Geological Survey in 1921 and, according to the same source, at the end of 1923 the developed power was about 29,000,000 hp., or an increase of 25 per cent in about three years. The increase was about 1,500,- 000 hp. in North America, 3,400,000 in Europe, and 1,000,000 hp. in Asia. The installed capacity for the United States at the end of 1923 is given as 10,000,000 hp. and the potential power as 35,000,000, but the Geological Survey states that with complete development the installed capacity will be about 70,000,000 hp. or more, so that only about 14 per cent of the total re- sources of this country has yet been developed. The estimated waterpower resources of the world are given in the accompanying table.
Horsepower Continent Developed Potential
i
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638 ENGINEERING
NEWS-RECORD Vol. 94, No 16
Oil Tank Fails After Sudden Drop in Temperature
Two Tanks Destroyed in Fire Apparently Caused by Rupture of One Tank—Sudden Cold Snap May Be Responsible
FIRE destroyed two oil tanks of the Marland
Refining Co. at Ponca City, Okla., on Dec. 19, apparently originating through the ignition of escaping oil after the rupture of one tank. The cause of the rupture has not yet been determined. Unusual tem- perature conditions prevailed just before the break, and these may have something to do with the accident.
A long period of mild weather had preceded. A day before the accident the temperature dropped from about 60 deg. F., and on the morning of Dec. 19 it was 4 below zero. About 6 a.m., Dec. 19, one or two light
very slightly, and the roof lay almost covering it. The first ring of the shell was torn from the second ring a distance of about 180 ft. and separated entirely from the other part of the shell, as well as from the curb angle of the base, to which it had been electrically welded. The sheets from the second ring to the roof were torn along an irregular line, offset by distances as much as the length of two or three sheets (each sheet about 18 ft. long). The shell was pushed back, to the south, to the earth dike surrounding the tank. The roof showed no large fissure that would indicate any explosion.
Dimensions of Tank—According to V. T. Moon, chief engineer of the company, the tank was 117 ft. in diam- eter by 41 ft. 10 in. high. It had been filled about a month before. At the time of the accident no oil was being pumped into or out of the tank.
The bottom was made of }-in. rectangular plates and
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“welded bottom ‘Probable point of break on North Side North Elevation
LOCATION PLAN AND SKETCH ELEVATION, PONCA CITY TANK
muffled sounds were heard and it was at once seen that there was a large fire among the group of tanks. This, it turned out, was due to the rupture of one tank (the lower of the two shaded tanks in the sketch plan here- with). So far as any direct testimony is available, the fire, the small explosion and the rupture were simul- taneous, and it cannot be determined which came first. All plant employees on the fire list were at once called. The outrush of oil was so great, especially to the north- ward of the tank, that the earth dike around the tank was overtopped by the flow, as were also the dikes of some of the adjacent tanks. The flooded area is indi- cated in the plan. All tanks were filled with high gravity crude oil, except the one directly east of the ruptured tank, which was only about one-sixth full (containing at the time a depth of 7 ft. 4 in., or about 14,000 bbl. out of the total capacity of 80,000 bbl.). This tank was destroyed during the fire, the entire upper portion and roof being warped and crumpled to the inside, leaving only two or three rings standing. The sag of the shell toward the south, apparently, tore the first ring free of the welded base angle connection along the north side of the periphery.
After the fire, the condition of the tank in which the trouble originated was as follows: Roof, shell and bot- tom were entirely separate. The bottom was disturbed
fs-in. sketch plates, electrically welded on the upper side, and bordered by an angle ring welded to the bot- tom and riveted to lower ring of shell. The shell was riveted. It consisted of seven rings, respectively 3 in., 43 in., 4 in., in., in., in. and in. thick. It was edged with a 3x3x@-in. angle at the top. The vertical joints of the two lower rings were butt joints, the others lap joints. The first ring had §-in. rivets about 2? in. on centers, the others 3?- and 2-in. rivets, spaced 24 in. and 2 in. respectively. The actual joint effi- ciency may have ranged from 65 to 85 per cent.
The roof was made of *-in. plate on structural steel framing, and had about 2 ft. rise from eaves to peak.
The main break in the lower ring of the shell, which is believed to be the starting point of the rupture, was a clean break, practically square to the length of the plating, located about 6 ft. from a vertical joint, and at or near a joint in the curb angle.
According to a report on the accident by H. W. Henry, of the Oklahoma Inspection Bureau, to appear in the National Fire Protection Association Quarterly for April, the best information is that there was no light- ning or similar atmospheric disturbance on the day of the accident, that there was no loud report indicating any considerable explosion, and that the local people
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April 16, 1925 ENGINEERING
NEWS-RECORD 639
consider that no defective welding or insufficient or improper riveting was involved.
A view of the accident held by some of the oil company people is that the accident resulted from a break in the lower shell ring, possibly due directly to the sharp drop in temperature causing contraction of the shell while the oil in the interior and the plating ef the bottom were still at a temperature not much below 60 deg.; and that the outrush of oil through the break or the tearing of the metal created a spark which set fire to the oil vapor.
Sacramento Filter Plant Report Advises Extensive Repairs
Settlement and Cracking Attributed by Structural Engineer to Faulty Original Design— Eight New Filters Advised
MMEDIATE repairs and reconstruction of the Sacra-
mento filter plant to cost $100,000 are recommended in the report of H. D. Dewell, consulting engineer, San Francisco, made to the Sacramento City Council on April 2. Dewell also recommends that construction be started at once on a bank of eight new filters to cost about $330,000. These new units are to replace old ones the cost of repair of which would be excessive, and at the same time to provide needed additional capacity.
As reported in Engineering News-Record, Sept. 4, 1924, p. 375, attention was called to deficiencies in the filter plant by the failure, on June 24, 1924, of the concrete wall between the grit basin and sedimentation basin 3. This break was made the subject of a report to the city authorities by Charles Gilman Hyde and George J. Calder, chief consulting engineer and resident engineer, respectively, on Sacramento’s water filtration project. The Hyde-Calder report stated that an exam- ination of the original plans and subsequent tracings showed that although the wall was properly designed to take unbalanced load from either direction, an error was made by the tracer who copied the original plans in the process of making up contract drawings. For one side of the wall he showed only 25 per cent of the amount of steel called for on the original drawing.
This simple explanation apparently was not con- cluded to be sufficient by Mr. Dewell, who was retained by the city some months ago to make an analysis of the causes of structural failures and settlements in the plant and to recommend needed repairs. His report states: “The filtration plant is far from satisfactory from a structural standpoint.” All structures, with the exception of the intake pier, the bridge abutment and the central portion of the pumping station, have settled since they were completed. Just how much settlement is uncertain on account of faulty records; the maximum in structures on piles may be as much as six inches and in those on spread footings possibly as much as one foot.
Some of the damage from this settlement is listed as follows: (1) Both banks of filters have cracked away from the main building and are out of level. (2) Certain walls of the pumping station are cracked. (3) Walls of the areaway of the coagulant building have settled and are out of line. (4) The walls of
the sedimentation basins are cracked and cracks occur also in the roof over the sedimentation basins and in the floors of the grit basins. (5) The central conduits in the filters are cracked. (6) There is some evidence for the belief that the 36-in. bypass along the west wall of the sedimentation basins has cracked.
The report places blame for this settlement squarely upon those who made the structural design, stating that there were improper assumptions, a failure to give
proper consideration to ground conditions and faulty —
design of beams and walls. Dewell’s report states: “With the uncertainties which exist as to the ability of the structure to withstand further possible settle- ment and the deficiencies in design, the writer cannot guarantee its future stability or take any responsibil- ity for its future behavior.”
The report further states, however, “Outside the actual failures including cracking and settlement the plant appears to be functioning satisfactorily after approximately a year’s service. If no further settle- ment occurs it is extremely probable that with the re- pairs recommended the plant will give satisfactory service for many years to come.”
Recommendations for repair include a temporary pumping plant during the reconstruction to bypass the water from the head house to the pumping station through a 60-in. corrugated steel pipe to be laid for this purpose. They also advise that the 36-in. bypass of the sedimentation basins be paralleled by a similar line and that the bypass gate structure at the northwest corner of the grit basin be raised.
Practical difficulties in renewing the foundations under certain parts of the filter beds where settlement is serious would make the repair cost practically equal to the original cost of these units, hence the recom- mendation for a new bank of filters which would replace these and at the same time provide needed increases in capacity. The $100,000 recommended for expenditure on repairs is about 4 per cent of the initial cost of the work.
Simultaneously with the submission of the Dewell report the Sacramento city manager announced that the repairs, to cost $100,000, will be started at once, but ‘that construction of additional filters, which would require a bond issue, will not be considered for some time at least.
Industrial Simplification in Sweden
Simplification of practice is progressing well in Sweden, according to a note in a recent bulletin to sus- taining members from the American Engineering Standards Committee. The Swedish Committee on Industrial Standardization has adopted 71 mechanical standards. The number of railroad coach screws has been reduced from 200 to 19. Army lamps have been reduced from 200 to about 75 types, resulting in an annual economy of some $2,400 for the army. Stand- ardization of pipe and fittings is now under study. The committee has asked a government credit of $19,000 for the coming year’s operations. Standards for tolerances of cylindrical parts have been drafted, and a draft standard for rivets with countersunk flat and spherical heads has been issued. These heads have countersunk
angles of 70 deg. for diameters from 6 to 13 mm., and |
60 deg. for diameters of 13 to 38 mm.
1 (
—
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640 ENGINEERING
NEWS-RECORD Vol. 94, No 16
Minneapolis Building 210-Ton Garbage Incinerator Plant By J. A. JENSEN
Engineer, Water-Works, Minneapolis, Minn.
HE CITY of Minneapolis has recently let a contract
for a garbage incinerator with a rated capacity of 210 tons per 24 hours. The plant will consist of three 75-ton units of a modified brick type. There will be employed cast-iron tuyere plates instead of the usual grates. The furnace section of each unit will have three tuyere-plate fireboxes separated by two tilting drying grates. Forced draft is used and the air is partially heated in ducts passing through the combus- tion chambers and also by contact with the grate and tuyere plates before entering the fire. This will keep the plates at temperatures designed to prevent their injury by the fire.
The fireboxes are 5} ft. deep, which renders stoking easy. The drying grates are made to tilt to the right or left to deposit the drying garbage in any firebox desired. The gases are passed through a combustion chamber at the rear by means of two openings in the rear wall. In the flue a part of the heat can be by- passed through a heating boiler.
Clinkers, ashes and soot are removable by means of tunnels below the operating floor. The combustion chambers have bottom gates for the purpose. The ashes are delivered to a skip hoist which deposits them in a 15-cu.yd. hopper.
The fan suction is taken from the clinker pits through a dust chamber for sedimentation, from hoods over the furnace doors and through funnels from the charging floors. By this means foul air or smoke will be passed through the fire.
The garbage will be handled by overhead cranes and discharged into hoppers with controlled gates, one tank to each charge of 4cu.yd. The gates permit the garbage to descend through a pocket against a second gravity door above and back of the fire. These two sets of doors form an air lock, so to speak, between the furnace and the charging floor. The garbage is hauled in re- movable steel tanks which may either be stored on the charging floor for night burning or be dumped into the fire. A 175-ft. radial brick chimney will carry the gases well into the atmosphere.
The garbage to be burned is delivered in the wrapped
form, which is a method popular with the housewife in
this climate. By this treatment it is drained of water at the kitchen sink, wrapped in paper and placed in a 20-gal. can at the alley. In this condition it does not freeze fast to the sides of the can in winter, nor stick to the can or foul it in summer, thereby eliminating
odor and flies which is very desirable, and fulfills the
first requirement of sanitation. The garbage is of a quality between free garbage and the usual mixed refuse and garbage of most eastern cities.
No attempt is made to utilize waste heat, except to apply it to the process involved. Drying and incinera- tion, by employing as much retained heat as possible, will be the principle involved. The analysis of the garbage indicates that not more than 50 Ib. of coal should be necessary per ton of garbage in this furnace. In the present plant the average coal consumption per ton in 1923 was 100 lb. and in 1924 it was 71 lb. The reduction was due largely to the use of a locally de- signed brick furnace serving a vertical steam boiler.
In the incineration of garbage the combustible © re. sent must produce sufficient heat units for the elim ina- tion of moisture. If there is a deficiency of © .™m.- bustible, coal or other fuel must be supplied to prod icc a proper heat balance. Where an attempt is mad: to utilize “‘waste heat” it results in robbing the inciner::',y furnace of its heat and interfering with combus' ijy due to lowered temperatures. It becomes necessary to add coal to “make up” and properly destroy the garbave. It appears that if heat is to be used for power it jis preferable to utilize it directly in properly designed boilers than to saddle this duty upon a garbage in- cinerator and thereby disturb its proper functions.
For these reasons this plant was adopted to reduce garbage incineration to its simplest terms, and permit the destruction by proper utilization of its own heat as far as it is possible to do so, and add fuel only when it is necessary to restore a proper heat balance.
The new plant is three miles closer to the center of the city than the old one which will result in a con- siderable saving in hauling costs. An effort is being made to enjoin the city from constructing the plant at this location and a hearing has been ordered.
The contract was awarded to the Goder Incinerator Co., of Chicago, for $204,100, which includes the in- cinerators, building, chimney and all necessary equip- ment needed for operation. The contract guarantees that complete and satisfactory incineration will be ac- complished with 14 man-hours per ton or seven men per shift not including supervision. On an August
- analysis of wet garbage as a basis it is guaranteed that
not more than 75 lb. of extra fuel will be required per ton of garbage. Two other bids were received for this plant, the amounts being $352,612 and $352,400 respectively.
The Goder Incinerator Co. has built an 80-ton plant at St. Louis, Mo.; a 50-ton plant at Joliet, Ill., and a 40- ton plant at Whiting, Ind., besides plants at Army and Navy Stations in the United States and Canada. The company also has numerous industrial incinerators in hotels and apartments, and has done considerable work in waste heat boiler work. The experience of the company in garbage and refuse disposal is based to a large extent on German practice.
It is hoped that the new plant at Minneapolis will be ready for preliminary testing by the middle of August.
Instruments for Airplane Mapping
Two new instruments, a magnifying stereoscope and a camera lucida, have been designed and built by the Bureau of Standards, Department of Commerce, as aids in map making by means of airplane photography. The stereoscope, built for the Coast and Geodetic Survey, is to be used in picking out triangulation stations when airplane photographs are used to supply details for a map based primarily on a ground survey. Such stations are generally flagstaffs, church steeples, and other high objects. The stereoscope makes high objects stand up in aconspicuous manner. The camera lucida is used for transferring points to the map in cases where a line map is to be made and not a photograph. It is especially designed to correct for the variations in scale and for the distortion due to roll and pitch of the plane which are unavoidable in airplane photography. The photo- graph, horizontalized and brought to the proper scale, is projected upon the map and the desired points and lines are traced in with a pencil.
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ENGINEERING
NEWS-RECORD 641
April 16, 1925
Plugging a High Pressure Tunnel, Buffalo Filter Plant
Water Bearing Shaft to Tunnel Under 66-ft. Head —Balancing Pressures Difficult—Third Trial Method Successful
By C. S. RINDSFOOS Secretary-Treasurer, Jarrett-Chambers Co., Inc., New York City
The construction of the Buffalo filter plant, described in “Engineering News-Record” Feb. 19 and 26, pp. 322 and 358, involved some trouble- some underground construction to deliver the filtered water into the old raw-water distribution system. The largest of these operations was to plug the old Massachusetts Ave. tunnel 80 ft. below ground and 66 ft. below lake level, as indicated on Fig. 1, and sink a new shaft (Shaft 4) to connect the high-level filtered water conduit from the pump well with the low-level Massachusetts Ave. tunnel. This operation is described in the following article. —EDITOR.
NEUMATIC shaft sinking and difficult divers’ work
in a water-filled tunnel 80 ft. below ground were the essential operations in connecting the new Buffalo filter plant, through the old tunnel, to the city distribution system. The structures built are shown by Fig. 2, which also indicates the general method of construction.
Shaft Sinking—A hole was first excavated, by a half- yard orangepeel bucket, to a depth of 14 ft., or to a point just above water level. The ground consisted of an ash and clay fill and was allowed to take a natural slope leaving a space some 18 ft. in diameter at the pit bottom. This afforded room to set the cutting edge and forms for the circular concrete caisson. Then 3-in. planks were laid on the bottom of the open cut and on these the cutting edge was assembled. The concrete caisson was then molded with removable wooden forms, to a height of 24 ft. The plank and forms were then removed and the caisson was sunk by open dredg- ing, 8 ft. to El. 566. The caisson was then built up to about its final required height and again ditched to rock at El. 554. No attempt was made to pump or exclude the water during this period.
After reaching rock it was found impracticable to unwater the shaft sufficiently to drill and blast, as water came through seams in the rock in considerable volume. A timber deck, for which slots had been left in the cais- son walls, was then placed, an air lock installed and air pressure applied. The space between the cutting edge and the rock was then packed with clay in bags and the bottom dried, after which the clay was replaced, bit by bit, with concrete, to effect a permanent joint between the caisson and the rock.
Rock excavation began 12 ft. in diameter to allow for a concrete lining 1 ft. thick. The rock is a flinty limestone, dulling steels quickly and requiring more than the average amount of dynamite to break it, but when blasted it breaks very fine. Moreover, the rock is very seamy and, after the first 34-ft. cut had been made, a 24-in. seam was uncovered which made it exceedingly difficult to hold the air pressure. Constant “mudding up” with clay and cement mortar was neces- sary so that, after this cut had been cleared, the first section of the lining was put in to make the shaft tight down to this point. Excavation proceeded for
another 34 ft., when another and similar water-bearing seam was encountered. This was grouted and this so effectually stopped the water that the air pressure was removed and drilling and blasting were resumed “in the open.” The blasting, however, soon opened up the seam
Present intake
Raw water condurt-- plugs
Pumping Station
water conduit
j
FIG. 1—LOCATION PLAN OF SHAFT AND TUNNEL
to such an extent that it was found advisable to cement it and re-apply the air pressure. At El. 542 the rock appeared harder and less seamy,
so a second ring of shaft lining was put in place, to
secure the work above, and the air pressure was again removed. Work in the open now continued for some 10 ft. when a third seam was struck through which the water came in volume and under a head that caused it to spurt up 8 ft. Grouting of this seam was unsuc- cessful, and pneumatic work was resumed, the seam plugged with mortar and another section of concrete shaft lining placed, thus securing the work down to El. 530.
Rock excavation was now continued as_ before, under air, to El. 522, at which point test holes were drilled and the concrete arch of the Massachusetts Ave. tunnel was located.
It should be observed that the exact location of this old tunnel, into which the shaft was being sunk, was not accurately known either as to depth or position in plan. The water in this old tunnel was under a head of 66 ft. and hence a pressure of about 30 Ib. was anticipated. The pressure we were using in the shaft was at times much less than theoretical except when a bad seam was met. Therefore, to break into the old
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ENGINEERING
642
NEWS-RECORD
tunnel unexpectedly might have caused the shaft to fill almost instantaneously and trap the workmen. For this reason as the work approached the old tunnel it was prosecuted with great caution and the test borings referred to above were made.
Having located the tunnel, the arch was broken through, an air pressure of 26 lb. sufficient to hold the water at 6 in. over the roof being maintained mean- while. The air pressure and lock were next removed, the shaft allowed to fill with water, and such material as had fallen into the tunnel was taken out by clamshell.
Plugging Old Tunnel—The next step was to build two bulkheads, one of permanent character to exclude the raw water from the intake side of the Massachusetts Ave. tunnel, marked A on Fig. 2, and a temporary one, marked B on the opposite side of the shaft, the two making a cofferdam in which to make the permanent connection between shaft and tunnel.
Divers, working two men at a time in two-hour shifts, built the bulkheads, a gate on the intake side being first closed as otherwise they would have been swept along with the current. Air was furnished direct from the motor-driven air compressor located above ground. The divers regulated the air pressure themselves by a needle valve on the hose within reach of the right hand. The helpers above also had a valve and gage on the line on which they maintained 40-lb. pressure, which was reduced by the diver to about 32 lb.
The concrete bag bulkhead A was first started, this being on the intake side of the tunnel. Bags were filled and thrown down the shaft during the half hour be- tween shifts. One diver placed the bags which the other passed to him. When the bulkhead had been built to within 1 ft. of the roof, a strong flow of water, due probably to inability completely to close the intake gate above referred to, prevented closing the opening and work was temporarily stopped while the sand-bag bulk- head B was begun on the opposite side of the shaft. The current which prevented making a closure of the one bulkhead was of some assistance in placing the bags in the other. The sandbag bulkhead was carried to the tunnel arch or roof, the final space next to the arch being packed with small bags of clay and oakum.
Work was then resumed on the concrete-bag bulkhead but without success, due to the flow of water and, as it appeared that this might go on indefinitely, the divers were withdrawn and the air lock replaced. The water was blown down to the tunnel arch, a timber working- raft constructed, and the plugging of the concrete-bag bulkhead again attempted. This also proving unsuccess- ful, the entire space between the two bulkheads was filled with sand and gravel (concrete aggregate) as high as the tunnel arch and the sand-hogs began working back through this sand and gravel to the bulkheads, mudding-up as they went.
This method was successful and the top of the con- crete-bag bulkhead was packed tight against the roof. As the sand and gravel which had been dumped between the bulkheads were removed, the face of each bulkhead was covered with 3x12-in. breast-boards, working from the top toward the bottom. The face of the sand-bag bulkhead B behind the breast-boards was packed with clay, and a space 1 ft. thick between the concrete-bag bulkhead A and its breast-boards was packed with concrete. The breast-boards were held by vertical tim-
bers which in turn were secured by dowels set in the In addition to the dowels, one
side walls and floor.
Vol. 94, No. i¢
Position of concrete Caisson before sirking--y
ee
Ground /eve/-,
Ash and clay
Jem lar 7 ; ch $74 /é | & conduits SS /st Ring & ‘ 2nd 3"Stream 546 £ S4 /2°- > & 3ra Ring 532 JStream $30 4th king § > &
A “Old tuanel lining Pipes bag, bu/khead B FIG. 2—SECTION OF SHAFT SHOWING SINKING AND PLUGGING OPERATION
line of horizontal timber braces on the center line helped hold this timber facing as shown in Fig. 2.
The installation of this timber work and the breast- ing down was extremely ticklish. Work could be done on only one bulkhead at a time, since by reason of a 4-ft. difference in head on the two ends of the Massa- chusetts Ave. tunnel, one side would dry up sooner than the other, and hence the breasting of one side had to be carried about 2 ft. ahead of the other.
It should also be remembered that this shaft and caisson, unlike those usually employed in city and bridge work, was a closed vessel. Air could not be pumped into it regardless. The 3-in. pipes put in one bulkhead were for the purpose of acting as relief or safety valves and likewise an automatic relief valve, set at 30 Ib., was mounted on the deck above. The object of these measures was to avoid a catastrophe should the gage tender fail in his duty for any cause, in which case, without such a device, the box might be subjected to too high a pressure. Likewise the supply line was carried
> —~ 2 El 588 A A OCKk ~ a ad ~ ° 0 Pos FON oF Concretvé caisson after sinking Pg {? x — Ola tunnel /ining | >. \ ¢ Cay oakum 4 u-/ S >
April 16, 1925 ENGINEERING
NEWS-RECORD 643
to a point near the bottom for purposes of ventilation. of course in the early stages of the building of the bulkheads, when they were leaky, these precautions were unnecessary but the tighter the bulkheads became the more sensitive became the balance between air and water pressures on the two sides of either bulkhead and the more necessity was there for extreme caution.
After the bulkheads were finally completed, the per- manent concrete plug C and the balance of the shaft lining were put in place. The forms and timber braces were removed and, since the sand-bag bulkhead then began to leak there was a consequent loss of air pres- sure, and finally the face of this bulkhead fell down, and water came in as high as the roof of the tunnel in a few seconds. This, of course, had been anticipated and the men had been withdrawn. The air pressure was finally taken off entirely and the shaft allowed to fill.
The sand bags were then speedily removed by a clamshell bucket, divers working meanwhile throwing the bags within reach below. The opening in the side of the shaft was then cut through from conduit EF at the upper level, and the connection was complete.
George C. Andrews, engineer, and C. D. Parsons, associate engineer of the Filtration Division, had charge of this work for the city, Fuller & McClintock of New York City being the consulting engineers. The caisson was designed and the contract executed by Jarrett- Chambers Co., Inc., New York City, W. E. Bush having charge in the field. .
Rib-Arch Concrete Bridge Over Rock River, Ill.
Twelve Open-Spandrel Arches—Repair of Cracked Rib—Unfinished Spans on Falsework in Winter—Brick Parapets
By WALTER S. Topp Resident Engineer for Whiteside County, Sterling, Ill.
TWELVE-SPAN reinforced-concrete arch highway bridge over Rock River, which was opened to traf- fic Dec. 5, 1924, and connects the cities of Sterling and Rock Falls, Ill., presents some points of design and con- struction which are worthy of note: (1) The sim- plicity of design and similarity of construction of the
FIG. 1—CONCRETE ARCH BRIDGE AT STERLING, ILL.
various units in the structure, (2) the conditions to be met at the north or Sterling end of the bridge due to the proximity of the tracks of the Chicago & North- western Ry., (3) the method of supporting the arch ribs during the winter season to minimize the amount
of falsework in the stream, and (4) the settlement of
falsework under one arch rib during construction.
This bridge consists of twelve double-rib open span- drel arches having a clear span of 80 ft. 6 in. and a rise of 10 ft. 9 in.; the width of piers is 6 ft. at the springing line, making a total distance of 1,032 ft. between abutments. A roadway 28 ft. between curbs and two 7-ft. sidewalks make a total width of 42 ft. between handrails. The sidewalks extend 4 ft. 6 in. beyond the outside faces of the arch ribs and are supported by cantilever beams. Fig. 1 is a view of the
completed bridge and Fig. 3 shows the details of the
design.
A camber of 18 in. in the length of the bridge is introduced by increasing the height of the spandrel columns which carry the floorbeams. The roadway slab is 9 in. thick with a span of 9 ft. 1 in. between center lines of floorbeams. It is designed as a simple
FIG. 2—FALSEWORK UNDER UNFINISHED BRIDGE - IN WINTER Temporary footbridge supported on arch ribs.
slab, and is made to act as a simple beam by placing construction joints over the centers of the floorbeams. These joints extend from top of slab down to the rein- forcing steel, and are filled with bituminous felt. The wearing surface consists of 2 in. of concrete of a slightly richer mix than the remainder of the slab, and was poured monolithically with the lower 7-in. portion.
The conditions at the bridge site were favorable for construction operations and no serious difficulties were encountered. Over the rock bed of the stream is silt up to 3 ft. in depth, but the elevation of the rock varies
_only slightly, so that the methods of constructing piers
and abutments were almost identical in every case. Rock River is fed by numerous lakes in southern Wis- consin which act as reservoirs and cause a very uni- form stream flow throughout the year, while about 500 ft. below the bridge site there is a dam which aids in maintaining the water level at a uniform stage. Due to these facts, there was very little delay caused by high water, and the contractor was assured of ample depth of water to care for floating equipment at all times. . The usual depth was 7 to 8 ft.
The main line of the Chicago & Northwestern Ry. crosses the street at grade about 260 ft. from the north end of the bridge and in order to provide a suitable grade to a subway it was necessary to lower as much as possible the crown of the roadway on the first span. For this purpose the floor of the bridge was lowered 187 in. by the use of a vertical curve extending 62 ft. from the end of the bridge toward the first pier. The amount to which the floor could be lowered was limited to an elevation where the bottoms of the floor- beams coincided with the under sides of the ribs. In
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644
ENGINEERING
NEWS-RECORD Vol. 94, Ni 14
this case, the main reinforcing steel in the floorbeams was placed before the ribs were poured, and the floor- beams were notched into the ribs with a series of steps. Additional short dowel bars were added to strengthen the beams for shear at their junction with the ribs. By thus lowering the floor, a grade of slightly less than 5 per cent was obtained for the approach to the subway.
A Brick rail ( flemish bord)
settlement cracked that portion of concrete in th: »j} which had obtained its initial set. Due to the sett) ny and cracking of the arch rib, it was thought that °}, bond between the concrete and reinforcing steel m) -h; have been destroyed, and the strength of the conc, +. was somewhat doubtful. Consequently, it was deci od to remove a portion of the rib for a distance extending
| 9 shrb ‘Slab ~
12
Class B concrete used below copiiig if! plers. Proportior7s,—1: 3:5
Half Elevation
“se
Half-Section A-A
FIG. 3—TYPICAL SPAN OF ROCK
During the fall of 1923, it became apparent that all of the arch ribs would not be constructed before winter and that the falsework under the ribs of the last two spans poured would have to remain in place in order to minimize the unbalanced arch thrust at the last pier. No abutment piers were provided, and analysis showed that the last pier was unstable with the arch ribs in place. It was necessary to leave a minimum amount of falsework in place, as shown in Fig. 2, to decrease the danger of an ice jam. The upstream side of the false- work bents ended in a V-shaped frame with a steel beam acting as an ice breaker. Fortunately, there were no serious ice jams and when the ice went out the false-
FIG. 4—REPAIRING A CONCRETE ARCH RIB
work was not disturbed. Fig. 2 shows also the tem- porary sidewalk which was used to maintain pedestrian traffic during the winter. This was later removed and
placed in the stream on wooden bents, beyond the limits of construction activities.
During the pouring of one of the arch ribs, the piling of one falsework bent settled about 54 in. due to failure to drive one of the piles to refusal.
The
to be made.
Class A concrete used throughout 1 except as shown. Proportioris, - 1:2: 44 Section on C.L.
RIVER BRIDGE
from the construction joint at the pier to a point about 18 ft. from the face of the pier, as shown in Fig. 4. The concrete was removed by a steam drill and plugs and feathers.
While the work of removal was in progress, levels were taken daily at numerous points on the remainder of the rib to assure that no injurious settlement oc- curred in that portion of the original pour of concrete which was to remain in place. The falsework was strengthened by additional struts and diagonal braces and a new bent was driven where the former bent had failed. The reinforcing steel originally placed in the rib was cleaned and réplaced.
The joint between pier and rib was identical with similar joints at other points in the bridge, but the joint between the original pour and the new portion of the rib was different, since all other ribs were poured continuously. This joint was given careful attention. In removing concrete, the work was done entirely by hand chiseling adjacent to the point where the joint was The joint was placed at right angles to the main reinforcing steel in the rib, and a horizontal groove was chiseled in the concrete to provide some additional strength at the joint for shear.
This bridge was built at the joint expense of the city of Sterling and Whiteside County. The design was made by the bridge department of the Illinois Division of Highways and is based on a live-load equal to a 24-ton tractor, as required by the state specifications, or a uniform live-load of 125 lb. per sq.ft. on roadway and sidewalk surface. Parapet walls of rough-faced brick, laid in Flemish bond, have copings and bases of concrete 12 in. wide. There are twenty-six boulevard lights of 400 cp., two at each pier and abutment. These lights are on two.circuits, so that after a designated hour all but five may be put out. They are mounted on posts of precast reinforced concrete, with the center of the light approximately 10 ft. 3 in. above the roadway.
The contractors were John Moroff & Son, of Kanka- kee, Ill. The total cost of the bridge was about $178,500.
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ENGINEERING
NEWS-RECORD 645
April 16, 1925
Testing and Placarding Roadside
Waters in Pennsylvania Less than Half of 841 Supplies Examined Approved by Engineer and Traveling Laboratory Making Tests on Ground
By EARLE L. WATERMAN AND UH. P. DRAKE Associate Professor of Sanitary Sanitary Engineer, Pennsyl- icsngineering, University vania Department
of lowa of Health
OR the purpose of answering the question as to
the safety of roadside water the Pennsylvania State Department of Health inaugurated a state-wide survey of the water supplies along the highways of Pennsyl- vania during the summer of 1924. More than 2,000 miles of main highways were covered by the survey and 1,200 different sources of water supply were in- spected by a sanitary engineer. Samples of water from 841 of these sources were examined in a traveling laboratory. As a result of the sanitary survey and laboratory examination, 407 “Safe Drinking Water” signs (Fig. 1) were posted on approved supplies.
The field work was done by a party which consisted of a sanitary engineer, a bacteriologist and an inspec- tor from the Restaurant Hygiene Division. The road equipment (Fig. 2) consisted of a Ford roadster, which was used by the engineer, and a field laboratory. The engineer worked ahead of the laboratory, making a sur- vey of every source of water supply along the highway which might be used, These sources were found at garages, filling stations, tourists’ camps, tourists’ lodg- ing places, refreshment stands, private homes or simply natural sources of water supply which might or might not be developed for supply purposes. The inspection was made to determine whether the- supply was prop- erly located with respect to possible sources of con- tamination and whether it was properly protected. The facts in regard to each supply were recorded on a
ih ads AT. LEE
>
in “APPROVED
FIG. 1—SAFE DRINKING WATER SIGN
special report blank and an identifying number was assigned. If the source of supply was satisfactory from an environmental and structural standpoint the engineer put up a signal indicating that the laboratory men were to take a sample of the water.
The field laboratory was equipped to make bacterial examinations with the same care that would be exer- cised in the State Department of Health laboratories. Total counts of bacteria at 37 deg. C., the presence of gas-producing organisms in 1 c.c. and 10 c.c. quantities and the identification of B. Coli were determined. Ex- amination of the samples collected was always started within seven hours after the collection of the sample.
For this reason the results obtained were much more reliable than those which might be reported on a sample which had been sent to a central laboratory. High bacterial counts were rare.
The. results of the laboratory examination were re- corded on the report of the sanitary survey. As sam- ples were taken only from those supplies which were satisfactory from a structural and environmental stand- point, the question of approval of the supply was set- tled by the results of the bacterial analysis and previous history. The reports were studied by the engineer and the bacteriologist*‘and marked “Placard” if the source of supply was satisfactory from all standpoints.
The reports were then sent to the Bureau of Engi-
we
FIG. 2—FIELD EQUIPMENT: ENGINEER'S FORD AND TRAVELING LABORATORY
Engineer cruised ahead and examined supplies from struc- tural and environmental standpoint. Laboratory tested only supplies passed by engineer.
neering in Harrisburg where they were reviewed by the Department’s sanitary engineer, and instructions for the posting of approval signs sent to the health officers in whose districts the supplies were located. Each approval sign bore the identification number originally assigned by the engineer and a number indicating the year for which the approval was granted. The signs were posted near the source of supply where they could be seen by any one seeking water. In some instances the owner of the supply put up a large sign calling attention to the fact that the water had been approved (Fig. 3).
The work done in Pennsylvania covered | many dif- ferent types of country varying from thickly settled agricultural districts to sparsely populated mountainous districts. The itinerary included the Lincoln Highway from Philadelphia through to the Ohio state line; the National Pike, running across the southwestern corner of the state; the William Penn Highway running east and west across the center of the state; the Chicago-Buffalo Road along the shore of Lake Erie in the northeast corner; the Lakes-to-Sea Highway running diagonally across the state from Erie to Philadelphia; the Perry Highway, running north and south in the western part of the state; the Susquehanna Trail running north and south through the center; the Lackawanna Trail, run- ning north and south in the eastern end; and several less well-known connecting highways. These roads trav- ersed all sections of the state and furnished examples of almost every known type ot water supply.
The sources of supply found were dug, driven and drilled wells, springs, small streams and cisterns. A detailed study of the final reports on the 841 sources of supply which were examined from an environmental, structural and bacterial standpoint shows that the fol-
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646
ENGINEERING
NEWS-RECORD Vol. 94, No. 16
lowing actions were taken on these supplies: “Safe Drinking Water” signs posted, 407; approval refused and owners notified, 278; public supplies—not placarded, 55; not permanently safe—not placarded, 90; action pending, 11.
“Safe Drinking Water” signs were posted on those sources of supply which met the requirements of both the sanitary survey and the bacterial examination. Signs were refused and the owners notified that the water should not be used by the public in those in- stances where the bacterial results indicated some source of underground contamination which did not appear in the sanitary survey. In these cases the bacterial results were very bad. Resampling of the supply with minor improvements was asked for in cases where the sample from the supply gave bacterial re- sults which were slightly lower than the required
WATER HERE
aum | ~
FIG. 3—OWNERS USED THE APPROVAL TO LURE TOURISTS
Official placard is on tree but this enterprising owner has utilized the full advertising value by making an enlarged fac-simile.
standards. No action was taken on certain sources of supply, usually for the reason that these sources had been recently developed and the poor bacterial results obtained were considered to be due to temporary con- tamination incident to construction.
Of the 685 placarded safe or disapproved wells, 275 were dug wells, 248 drilled wells and 162 springs, runs
or cisterns. Of the 275 dug wells examined, 104, or 38 per cent, were approved and 62 per cent disapproved.
Of the 248 drilled wells examined, 199 or 80 per cent were approved and 20 per cent disapproved. Of the 162 springs, etc., examined, 104, or 65 per cent, were approved and 35 per cent disapproved. A study of the supplies condemned shows that over 75 per cent of those not approved were in limestone and broken shale forma- tion, while only 13 per cent approved were in limestone or broken shale formation. When it is borne in mind that all of the 685 sources were selected supplies having satisfactory surface conditions and showing no evident signs of contamination, it is apparent that the geologic structure was the determining factor in most cases as to the safety of the supply. In many cases a surface supply or shallow spring not in limestone formation was found to be safe, while such a spring in a lime-
stone formation was found to be unsafe. The «any. condition obtains in the deep wells.
Owing to the fact that the work was started rat}).; late in the season and it was desired to cover the entire state, the principal object was to locate sources of s: ‘>. drinking water. The improvement of unsatisfactory sources of supply was considered of secondary imyvr- tance during the first survey. As a matter of f::+ many owners of sources of supply which were not ap- proved have sought advice from the Department of Health, and are trying to effect improvements which will insure their supplies being approved on the next survey. It is the intention of the department to con- tinue this project during the summer of 1925. |! sources of highway water supply will be re-examine! and re-tested before approval signs for 1925 are granted.
Lake Erie-Ohio River Canal Reported on Unfavorably
N UNFAVORABLE report upon the proposed canal connecting Lake Erie with the Ohio River has been made to the Board of Engineers for Rivers and Harbors by the division engineer of the Central Division, Corps of Engineers, U. S. Army, according to a notice issued to parties interested in the proposed canal by Col. C. W. Kutz, division engineer. Details of the report will not be made public until after it has been presented to Congress, but the notice states that the adverse con- clusions are based on economic considerations as al! three routes studied are feasible from an engineering standpoint. The report recites:
“The route extending from Portsmouth, Ohio, to San- dusky, Ohio, and the route extending from Cincinnati, Ohio, to Toledo, are both found to be economically in- advisable in that the fixed charges on such waterways
' will greatly exceed the prospective benefits; the latter
having been computed by taking the differences between canal haulage costs and existing rail rates and applying them to the prospective commerce.
“As to the route extending from Beaver, Pa., to Ashtabula, Ohio, an economic comparison similar to the one just described shows that such a cazal, when oper- ating at capacity, will yield benefits approximately equal to the fixed charges but that if certain inequities and inequalities in the existing rail rate structure on com- peting rail routes are eliminated and rail rates on low grade bulk commodities on such rail routes made rea- sonably proportional to the cost of the service, the direct benefits will be substantially less than the fixed charges.
“As a rail rate case, seeking the elimination of some of these inequalities, is now pending before the Interstate Commerce Commission, the conclusion has been reached that a canal along the Beaver-Ashtabula Route is also economically inadvisable.
“French Creek Route—Supplementary to the legisla- tion authorizing the above report, the River and Har- bor act approved Sept. 22, 1922, provided for a pre- liminary examination and report on a waterway from a point at or near Erie Harbor, Pa., by way of French Creek and Allegheny River, to the Ohio River.
“The report thereon has been made and is unfavor- able to the improvement. This adverse conclusion was based on a study of existing maps and data which
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ENGINEERING
NEWS-RECORD 647
April 16, 1925
chowed that such a waterway would be longer, require vreater lockage, and be far less valuable as a trans- portation route for through commerce between Lake Erie and the Ohio River than a waterway of the same -ize built along the Beaver-Mahoning Route (synony- mous with Beaver-Mahoning River).”
Interested parties are given the privilege of an appeal from this conclusion to the Board of Engineers for Rivers and Harbors within four weeks from the date of the publication of the notice of the adverse report.
Ford Company Develops and Uses | Power at High Dam
Manufacturing Plant Built at Dam with Rail and Water Facilities—Steam Plant Supplements Water Power
T HIGH DAM on the Mississippi River in St. Paul, Minn., the Ford Motor Co. has built a large manu- facturing plant to be supplied with power from a hydro-electric generating station making use of the
plant will also furnish steam heat for all the buildings. Railroad connections for the manufacturing plant are
provided through two depressed tracks running the
full length of the building and one coal track running along the outside, all three tracks connected to the C. M. & St. P. Ry. Access to the navigable channel of the Mississippi River is provided by means of a quay along the river bank between the two power houses in a situation where the flow of tail water from the hydro-electric plant will insure an open channel. A pair of tunnels 10 ft. wide and 11 ft. high extend back into the bluff and under the manufacturing plant to give direct access from the plant to the water terminal.
The construction was carried on by Stone & Webster. About 600 men were employed on the power houses and 500 on the manufacturing plant. The hydro-electric plant was ready to generate power in July and, pending the completion of the manufacturing plant, the power available was generated and sold in compliance with the terms of the lease which call for the generation of all the power available at the site and the sale to outside
FORD MOTOR CO. MANUFACTURING PLANT AND POWER HOUSES, ST. PAUL, MINN.
water power available at the dam and supplemented by
a steam-electric generating station. High Dam was
completed by the government in 1917 after earlier plans for two dams with locks in the river at this point had been abandoned in favor of one set of locks and one dam in order to develop the full head of 314 ft. with an output of about 24,000 horsepower. The substruc- ture for a four-unit power house was built in the dam but no attempt was made to develop the power until the site was leased recently to the Ford Motor Co. When the new power house was built it was necessary to cut away the greater part of the concrete in the substructure built by the government in order to make way for new draft tubes adapted to the developments in design since the substructure was built.
On a tract of land of approximately 160 acres the company has built a manufacturing plant with a main building 1,400 ft. long and 600 ft. wide and on the river bank below the dam a steam-electric generating plant as an auxiliary to the hydro-electric plant. The general layout is shown in the accompanying illustra- tion. The hydro-electric plant contains four units of 4,500 kw. each and the steam plant contains one unit of 5,000 kw. with provisions for a second unit. This
companies of all power not used in the manufacturing plant.
South Australia Adopts American Methods
American railway methods are being applied to the South Australian railways under the direction of Chief Railway Commissioner W. A. Webb, former vice-presi- dent and general manager of the M.-K.-T. R.R., who was engaged from America by the Barwell government in 1923 to take charge of the railways. Several million pounds are being spent in relaying portions of existing lines with 80-lb. rails, strengthening existing structures to carry heavier loadings, providing more engines of the Mountain and Pacific type, providing steel pas- senger cars and 40-ton freight cars and generally bring- ing the railways of South Australia in line with modern standard practice. New structures include coaling plants of types similar to modern ones in the United States and having capacities ranging from 150 to 300 tons. All-electric signaling is being extended from Adelaide north and south along the ,main arteries. A feature of the reorganization has been the introduc- tion of rail motor cars built in America for use gen- erally for branch lines and feeders to main lines.
.
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648 ENGINEERING
NEWS-RECORD Vol. 94, No.
Old Steel Trainshed Replaced by 4 Platform Shelters
=a Lofty Truss Roof Dismantled After 32 Years’ i Service on Account of Maintenance
a Cost Due to Corrosion
is EMOVAL of the old steel trainshed of the Union
Station at Duluth, Minn., and its replacement with platform shelters, marks the gradual disappearance of this old type of lofty long-span structures. This trainshed, 130-ft. span c. to c. of end pins and 400 ft. long, was built in 1892 and during the past ten years it has required large expenditures for mainte-
spaced 20 ft. c. to c. and having 17-ft. T-heads carry}; wood joists for a 21-ft. plank roof of the butterfly ty,.. with central gutter and downspouts. The plank sheat' ing of the shelter roof is covered with tar and gray. roofing.
For reasons of safety and convenience, the work .; dismantling the trainshed was done only between 11: 33); p.m. and 6 a.m., since no trains enter or leave the st: tion during this period. The contractor used two loco- motive cranes having booms of sufficient length ¢, support a truss from the top chord, the ends beiny burned off while it was held in this position. Then th: truss was lowered to the ground and cut by torche-
ia nance. Smoke and gases from the engines ee caused corrosion of some of the metal directly R: beneath the skylights, and the structure was oun maintained in condition by placing wooden members as substitutes for some of the metal- work supporting the glass. An examination made in 1924 showed that it train shed would be necessary to spend $15,000 to $20,000 " , > a in the removal of purlins, skylights and louvres, while at little greater expenditure the trainshed és could be removed and replaced with platform . “> 129° - FIG. 2—OLD TRAINSHED AND NEW PLATFORM SHELTERS AT DULUTH UNION STATION Re shelters. Furthermore, while the trainshed was only into pieces of sufficient Jength to be loaded onto cars. 4 400 ft. long, the four new shelters are from 400 to 875 All equipment and salvage material was removed from 4 ft. long. Across the ends of the tracks is a 25-ft. the station platform each night, so that there was no <j covered transverse platform connecting with the head- interference with the use of the station. After the S house. Each shelter consists of a row of steel columns removal of the skylights, roofing and sheathing, about 4
Me | FIG. 1—STEEL TRAINSHED AT UNION STATION, DULUTH, MINN.
This trainshed was built in 1892 and was taken down in 1924 and replaced with platform shelters.
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ENGINEERING
NEWS-RECORD 649
April 16, 1925
<ix days’ work was required to take down the trusses and all steelwork.
In connection with this alteration, there was a gen- eral relocation of tracks in the station and yard, to-
yether with laying 90-lb. rails and stone ballast.
The total cost of all the work was about $100,000. After the removal of the roofing by M. J. Harney, Duluth, the trainshed was taken down by Peppard & Fulton, Superior, Wis. This improvement was planned ynd earried out under the direction of H. E. Stevens, chief engineer, Northern Pacific Railway.
Effect of Flowing Water on the Stability of Sand
Experiments in Filter Bed and Observations on Dikes, Cofferdams, and Jetting Piles for Water Intake at St. Louis, Mo.
By C. M. DAILY
livision Engineer, Supply and Purifying Section, Water Division, St. Louis, Mo.
HE flow of water through sand may produce a hard compact mass or it may cause the sand to lose its resistance to lateral movement or it may cause any intermediate state, depending entirely upon the direction and velocity of the water. A downward flow of water through sand makes it compact and an upward flow causes it to become mobile. The upward velocity required to cause water to lose its resistance to lateral movement depends upon the size of the sand grains and the amount and character of the foreign material in it. Some experiments were made last winter in one of the filter beds, in St. Louis, Mo., to determine the upward velocity of the water through the sand at which the sand bed would fail to support a weight of 24 lb. over an area of 6 sq.in. and allow the weight to sink to the gravel. The sand varied from 0.38 to 1.2 mm. in size and was 27 in. deep. The upward velocity of the water, considered over the entire area, was about 0.09 ft., per minute. A downward flow of the same velocity caused the sand to become firm and the same 24-lb. weight would not make a depression in it.
Extensive data on this subject would be very useful in designing dikes to be constructed in sandy rivers like the Mississippi and Missouri and for such cases as the construction of cofferdams, the jetting of piles and the many kindred operations.
It is a well recognized fact that a permeable dike in the Missouri River is liable to fail if the water on the upstream side has a head of about 1 ft. or more above that on the downstream side. The cause of such a failure is not as fully recognized, judging from the lack of precautionary measures embodied in their design. The failures are caused primarily by water rising through the sand below the dike, in each case causing the sand to lose its resistance to lateral move- ment; the pressure of the water above the dike com- pletes the failure. Two measures may be used in some cases to overcome the difficulty, but neither of them may be practical in other cases. The first is to reduce the head on each dike by building several close together rather than a few far apart, and the second is to pre- vent water from penetrating the sand above the dike.
In December, 1924, the water was lowered 23 ft.
below the river level in a cellular cofferdam around the site of the water-works intake and low-service pump pit for our Missouri River plant, for convenience in dredging. An inward movement of the cells imme- diately took place. The water was then raised 14 ft. above the river level and all movement ceased. This incident impressed one with the necessity of controlling the flow of water into or out of a cofferdam to obtain the degree of stability required.
The jetting of piles depends on the upward flow of water through the sand around the pile and not entirely, as might be supposed, upon a jet action near the point of the pile. The quantity of water required to jet a pile in the ground depends on the character of the material encountered and the proximity to piles pre- viously jetted which may provide a path of low resist- ance to water moving upward. The ideal jet for sinking piles in alluvial soil is one that will insure a column of sand in suspension, or quicksand, around the pile. To obtain this, in many cases, it is advisable to allow water to escape from the sides of the jet pipe at close intervals and in sufficient quantities to main- tain a column of sand in suspension around the pile which will offer a channel of least resistance for the upward flow of water which escapes at the lower end of the jet pipe. When this mobile condition of sand exists around a pile, it may easily be forced to any depth. The churning of a jet pipe, so common and seemingly so necessary in jetting a pile into the ground, causes only the same condition of lowered resistance to upward flow of water around the pile that frequent side jets produce.
In jetting 48-ft. reinforced-concrete bearing piles 164 in. square for the intake and low-service pump pit for our Missouri River plant, the Frazier-Davis Construction Co. used from 600 to 900 gal. of water per minute through a 4-in. jet pipe having 2-in. nozzle. No side jets have been used to date but difficulties on several occasions were experienced in getting the piles to rock.
State Settlement Proposed for North Dakota
State promotion of land settlement is recommended
by the state engineer of North Dakota in his annual
report, just issued. Irrigation is developing slowly in the state, and “the settlement of land is perhaps the most difficult problem faced by the U. S. Reclamation Service on the projects already developed” in the state. Proper control of settlement was not possible because most of the land was in private ownership, and as the holders attempted to farm excessive areas many failures resulted. Adequate settlement is the greatest need of all irrigation projects in the state, and it is realized that until present projects show good results it will be difficult to obtain further funds for reclamation. On this account, says the state engineer, W. G. Black, “it should be to the interest of the state to encourage the settlement of the land in as small tracts as possible. It is recommended that land settlement schemes such as are now being applied on irrigation projects in several western states be studied. The settlement sed of California in particular is recommended . . Irrigation in North Dakota should be considered as a new industry that will serve to supplement the type of farming heretofore practised by supplying food products not obtainable by any other means.”
| < % ; i ; ¢ a 4 2 = 3 > & 7. 4 3
650 ENGINEERING NEWS-RECORD
Vol. 94, No. 16
From the Water-Works Field
Solving Every-Day W ater-W orks Problems of Cities and Towns
at Albany Water-Works
Control Valve, Pressure Gage, U-Tube Manometer and Rate-of-Flow Chart Based on Pressure Loss and Density of Gas
By THEODORE HORTON
Chief Sanitary Engineer, Department of State Engineer, and Formerly Chief Engineer State Department of Health, Albany, N. Y.
HOSE concerned in the chlorination of water and
sewage will probably find interest in a new ap- paratus of recent design, which has just been installed for the chlorination of the water supply of Albany, N. Y. The apparatus is the outgrowth of experiments carried out by the writer in an effort to develop an inexpensive instrument of simple design and construc- tion, i.e., one less liable to get out of order and less troublesome to maintain than any hitherto developed.
The apparatus is essentially a gas meter comprising four essential parts: A control valve, a pressure gage, a manometer and a rate-of-flow chart. The principle upon which the instrument operates is a co-ordination of the loss of pressure resulting from a flow of gas through a short tube with the density of the gas.
It is a well-known fact that the laws governing the flow of gases through pipes or tubes are closely similar to the laws for the flow of water through pipes or conduits. The only factor of importance which causes a variation in this similarity is that of density. Thus, with water the frictional loss of head due to uniform flow through a pipe of given diameter will increase with the velocity and be independent of the water pressure. The same is substantially true with a gas except that the greater the pressure of the gas the
FIG. 1—NEW TYPE OF CHLORINATOR, ALBANY, N., Y.
greater will be the density. The quantity by weight of
such a gas flowing through such a pipe will therefore
depend not only upon the velocity of flow but also upon its density. It is obvious therefore that by bringing these two factors, frictional loss of head and density,
New Type of Chlorinating Apparatus
into mechanical combination with a chart or scale. as in the apparatus recently installed in Albany, a direct measurement of the quantity of the gas flowing through
Sert/) tan
aN
Chlorine cylinder
Diffuser
FIG. 2—COMBINED CHLORINATOR AND RATE-OF-FLOW INDICATOR
The upper pressure gage registers the average pressure (density) of the gas. The bulb at the top of the U-tube maintains the liquid in the left leg at a practically con- stant level when the liquid in the right leg is depressed. By sliding, along the horizontal guides, the glass or wood plate on which the chart is mounted the observer brings the vertical lines corresponding to the upper pressure gage opposite the right leg of the U-tube, then reads the volume of gas flow from the position of the meniscus with ref- erence to the curved lines. Similarly, the opening of the control valve to give the desired volume rate of gas flow is controlled. Once set, little if any further adjustment is required, except to meet (1) temperature changes or (2) depletion of gas in the cylinders, or (3) to establish a new dosing rate. Experience shows that changes in temperature need give little concern, while the replacement of cylinders can be so ordered as to reduce to a minimum the varia- tions in pressure on the score of depleted pressure.
the apparatus per hour, or per day, as may be desired, is obtained.
Fig. 1 shows the instrument installed at Albany. Fig. 2 and its sub-caption illustrate and explain the design and operation of the apparatus.
The present apparatus eliminates entirely the need of a compensating valve, and the use of a check valve is not considered at all necessary by the designer. It is true that if the instrument is shut down water will be drawn back a slight distance into the tube, due to absorption of the gas. The height to which it is drawn is, however, ordinarily not over 3 or 4 ft. and for the obvious reason that as the water is drawn back into the tube, that portion on top of the column of water
3 4 Pressure | gage Cortro/ va/ve | HE Pane/ hart Pressure | Board ...-3 gage | | [2 — | || | | | ost
16
ENGINEERING
April 16, 1925
NEWS-RECORD 651
becomes saturated (the saturation point being only a few per cent), so that equilibrium is soon established with only a slight rise of the liquid. If the instru- ment is placed in a low position with reference to the level of the diffuser, it is a very simple matter to run the discharge tube up a short distance above the instru- ment before leading it downward to the diffuser, thus
forming a trap which would prevent the water from
being drawn back into the apparatus.
Two of these chlorinators are now in use in the city of Albany. One, used for pre-chlorinating the general supply, was first put in service on Sept. 26, 1924. Ex- cept for two brief periods, one awaiting the receipt of silver tubing to replace the rubber tubing temporarily used on the discharge line and the other awaiting chlorine shipment, this apparatus has been in continuous use, applying chlorine at a rate of from 200 to 250 lb. per day. The other apparatus was installed on Feb. 11, 1925, and is now chlorinating the supply from Rensse- laer Lake, a temporary source used only during the winter months. Both installations are running smoothly and with perfect satisfaction, requiring almost no ad- justment or other attention except replacement of chlorine cylinders.
The apparatus, in conjunction with the chart, is cov- ered by U. S. Patent No. 1,423,217, granted to the author July 18, 1922. ©
Fire Hose Forms Seal for Stop Logs to Unwater Intake Chamber
By J. E. GIBSON
Manager and Engineer, Water Department, Charleston, S. C.
URING the recent construction of a water-supply
intake at the shore line of the Goose Creek stor- age reservoir of the water-works of Charleston, S. C., it was necessary to unwater the new intake chamber to permit making the connection of the old and the new intake pipes. In the construction, provision had been made for placing stop logs in the concrete intake chan- nel from the reservoir. When the time came to place these stop logs in position and unwater the chamber, the leakage around the ends of the stop logs was greatly in excess of the capacity of the three 2-in. steam
ejectors that had been used to unwater the cofferdam
at the time of placing the concrete. In other words, sufficient difference in head could not be obtained to cause the outward pressure to seat the stop logs effectu- ally against the sides of the groove in the concrete, although by means of the jack bolts the horizontal joints between the logs themselves could be effectually sealed.
It was objectionable to attempt to seal these leaks by placing cinders or other material in the intake chan- nel as it was thought that this material would be car- ried through and might ultimately reach the pumps.
The method finally adopted, which we considered unique, was to remove all of the logs, shape the lower end of the bottom log to a gentle radius and fasten to it by means of strips of canvas a piece of standard 24-in. fire hose, allowing sufficient hose to extend beyond each end of the log to reach above the surface of the water when the bottom log was in final position, placing the log back in the groove or slot in the intake channel; then placing successively the remaining logs, forcing them to the bottom of the groove or slot until sufficient logs had been placed to extend above the flow
line of the storage reservoir. The stop logs had been cut short enough to make room in the slots for the collapsed fire hose.
After all necessary stop logs were in position and forced to their seats by the jack bolts, a j-in. water pipe was connected to the inlet end of the hose. On the opposite end of the hose a standard hose valve was placed and allowed to remain open to vent the air
ES 56 Pipe to maintain eniform Peada 07 kre hose
| |
To water main| | sa \\
pressure == f
<1 > 213 2°x 12 Silt- Elevation Section ~- |
| Plan
i Flow
FIRE HOSE UNDER UNIFORM HEAD SEALS STOP LOGS AT ENTRANCE TO CONCRETE WATER-WORKS INTAKE
and to permit a circulation of water completely through the section around the stop logs. To prevent excessive pressure, and to maintain a uniform head in the hose, a section of j-in. pipe was run up alongside a tree to an elevation about 45 ft. above the flow line of the reser- voir. The valve A (see illustration) was cracked suffi- ciently to keep this pipe overflowing. Water was allowed to circulate continuously through the hose and escaped through the valve B to give the foreman a visual assurance that he was maintaining the supply of water in the hose and, further, to prevent freezing in the exposed sections. It will be seen that an exces- sive pressure in the hose would have acted the same as a hydraulic jack and might have ruptured the con- crete abutments. It was reasoned that a 45-ft. head would not do this.
After everything was in place and the water was turned on, the leakage was reduced so that one 2-in. steam ejector running about three hours per day would take care of the leakage through and around the stop
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652 ENGINEERING
NEWS-RECORD Vol. 94, No. is
logs. There was a total of 192 ft. of joint between the individual logs and the ends of the intake. This was maintained for about three months as other diffi- culties prevented the completion of connections to the old intake line.
Upon removal of the hose, it was found that the mil- dew had practically ruined it, but on the whole we con- sidered it a good job and a satisfactory method of stopping the leakage.
F. B. McDowell, assistant manager and engineer of the Charleston Water Department, was responsible for the suggestion and its successful use.
Water-Works Problems in a Town of 1,000 People
Aerating Tower to Eliminate Odors—Superintend- ent Reverses Filter Flow and Throws { Away Alum Apparatus
By Harry P. LETTON Of Grant, Smith & Letton, Consulting Engineers, Lincoln, Neb.
Some are aerating tower constructed for the pur- pose of removing tastes and odors from a public water supply in Weeping Water, Neb., has proved so successful that it is believed a similar structure might be used with benefit in other places where odor troubles are encountered. Experience of this town of 1,000 people with a superintendent who discarded the filter sand, reversed the flow in a pressure filter and junked the alum rig indicate the vicissitudes small towns with- out intelligent operation occasionally endure.
The water supply was formerly obtained from shallow wells along the bank of Weeping Water Creek. This supply proving inadequate some years ago, a 4-in. cast- iron pipe line was run from the pumping station to an ice pond 900 ft. away. This pond, which covers not over four acres to an average depth of 5 ft., is kept full by diverting water from the creek whenever re- quired. The creek, which is a spring-fed stream, has a small dry-weather flow and becomes extremely turbid during rains. At the time the line to the pond was con- structed, a pressure filter having a rated capacity of 180,000 gal. per day was installed. The filter did not remove the turbidity satisfactorily and accordingly the town constructed a circular sedimentation basin with a spiral baffle wall so arranged that the raw water entered at the center and passed spirally through the tank.
AERATING TOWER, COAGULATION BASIN AND LOW-LIFT PUMP HOUSE
Solving the Every-Day
In 1922 the writer’s firm was employed to advise th. city on the water situation. At this time no apprecia}). difference was noted between the pond water and the water delivered at the taps. Investigation disclosed th. fact that although the filter and sedimentation basin were large enough under
proper operation to treat —_—# the water successfully, no RA apparent improvement was effected. On opening the — ae filter it was found that the _ water superintendent had
removed all the filter sand, replaced it with 2 ft. of coarse gravel and charcoal and had punched holes in the tops of the strainers. He had also changed the filter piping and was pumping the water backward through the Strainers and up through the gravel and charcoal into the distribution system. The result of this practice was that the filter became an incubator; the bacterial count increased rather than decreased. No coagulant had been used although the necessary equipment was found in a junk heap in the attic of the pumping station.
New strainers were obtained for the filter, properly graded filter sand and gravel were replaced and the filter piping put back. Alum tanks and an orifice box were installed for coagulating purposes and a chlorina- tor for sterilizing the supply.
As the elevation of the water in the pond was less than a foot above the coagulation basin walls it was im- possible to obtain sufficient flow by gravity. A second- hand, belt-driven centrifugal pump had been installed, previous to this investigation, in a small building along- side the basin. This pump took its suction from the 4-in. line and discharged into a home-made aerator in the center of the basin. As soon as the changes out- lined had been made, a pure, clear, sparkling water was obtained, but it was necessary to run the high-lift pump intermittently because of the fact that the pump feeding the basin had a smaller capacity than the triplex pump which forced the water through the filter and into the distribution system of the town. This arrangement required the coagulation basin to operate partially on a fill-and-draw primiple.
Although the water was perfectly clear it had a dis- agreeable taste and odor due to the presence of green growths. Treatment of the pond with copper sulphate was not sufficient to overcome the odors, and it was therefore decided to construct a more efficient aerating device. A new motor-driven centrifugal pump capable of delivering over 200,000 gal. per day against a total head of 50 ft. was obtained and installed in the place of the old pump.
The discharge from this pump was connected to a 4-in. riser on which were three lateral 2-in. branches spaced 5 ft. apart. The ends of the lateral pipes were bent up on a 1-ft. radius and on each was placed a spray nozzle of the type used in cooling ponds. These nozzles
INSIDE OF AERATING TOWER NEAR TOP
cant
PR
sin
4 | | | { | | 4 x Ves a 4 45
‘April 16, 1925 ENGINEERING
NEWS-RECORD 653
WVater- Works Problems
have j-in. orifices and each of them will deliver about 45 gal. per minute under a pressure of 8 lb. The riser pipe was located so that the nozzles were directly over the center of the basin.
Around the nozzles as a center was constructed an octagonal-shaped open-work tower having a diameter of about 30 ft. Each corner of the tower was formed by a 6 x 8-in. timber bolted to the baffle wall in the sedi- mentation basin. Between the uprights were nailed louvres sawed from 1 x 12-in. lumber and spaced in such a manner as to prevent spray from the nozzles from passing between the louvres. The top of the tower was
BOTTOM NOZZLE OF AERATING TOWER IN ACTION
Looking into the tower through opening formed by remov- ing some of the louvres.
framed and braced with 2 x 6-in. timber and the whole was tied together by means of iron rods. The lowest nozzle was placed just above the baffle wall and the area within the tower was floored so as to collect the water falling from the sprays and louvres. The floor was sloped to discharge this water into the center of the basin. Valves were placed on each of the lateral spray pipes so that the pressure in each might be regulated to distribute the water equally. A bypass valve was placed on the riser below the surfaee of the water in the basin so that during the winter months when aeration was not required the pond water could be pumped directly into the basin without danger of freezing.
The entire cost of the installation described, includ- ing the pump, was less than $800. The system was successful in eliminating odors in the summer of 1924.
Users Advance Money for Small-Town Water Extensions
By JENT G. THORNE Consulting Engineer, Clinton, Iowa HE town of Low Moor, Iowa, being confronted with the necessity of providing more water mains, after all legal means of increasing the town’s bond issue were exhausted, appealed to the interested prop- erty owners for aid. These property owners asked per-
mission to subscribe certain amounts of money to be used to pay for the desired mains provided that the town would grant them credit on future water bills at the regular rate. A majority of property owners subscribed $100 each and a few larger amounts. Fig- ured at the rate of $20 a year the average consumer would use up his credit in five years time and the water mains would then belong to the town.
Five blocks of water mains were laid and financed in this manner. The town was willing to supply the water as the number of consumers was so small that water was being wasted to keep a fresh supply in the tank, The property owners feel that they have a good bargain and the town officials are gratified to have the additional mains installed ready for use. Petitions are now in circulation for the laying of more mains by the same method.
Brass Services and Special Goosenecks Used by Hackensack Water Co. By D. W. FRENCH
Superintendent, Hackensack Water Co., Weehawken, N. J. RASS service pipes and lead goosenecks with cupped joints are now being used by the Hackensack Water
Co. which supplies some fifty New Jersey towns and villages on and near the Hudson and Hackensack Rivers. The goosenecks are made in the company’s shop, at a saving of 80c. each compared with the wiped joint goosenecks formerly made by plumbers.
The use of brass services was begun by the company about three years ago on all of its house service instal- lation work between the street main and the curb, and also in renewals of old services which had failed. The smallest size used is }-in. but for l-in. work brass pipe is also used. For sizes larger than 1-in., cast-iron is used exclusively. When we first started this work we used the regular brass pipe, I.P.S. (iron pipe size). It gave us some trouble on account of its being too hard and brittle and being non-flexible so that it broke trans- versely much as would a glass tube. In the nxt purchase semi-annealed pipe was specified and with this quality no trouble has developed.
Before purchasing pipe for this year’s work (1925) I obtained from Mr. Schneider, representing the Copper & Brass Research Association of New York City, a copy of a specification prepared by the American Society for Testing Materials covering brass service pipe re- quirements and asked for bids for 135,000 ft. in Jan-
Coupling with female thread out. ti
New Style OLD AND NEW STYLE GOOSENECK, HACKENSACK
uary. Part of the pipe has been received and is being used. The pipe is I.P.S., is very flexible, threads and cuts well and comes in 12-ft. lengths. I fully believe it will meet requirements in every way.
Brass pipe may not be quite as cheap as lead-lined galvanized iron, galvanized iron or black, but the fol- lowing figures show that it is less costly than lead of
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654 ENGINEERING
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NEWS-RECORD
the same size: j-in. lead AA weighs 33 lb. per ft. and with lead pipe at 10c. per lb. the cost is 35c. per ft.; ij in. brass weighs 1} Ib. per ft. and costs 18i%c. per lb. or 23c. per foot. We are using a lead gooseneck between the corpora- tion tap and the point where the brass pipe begins. Until Jan. 1 of this year, these goosenecks were made up by local plumbers, the 90-deg. tail piece of the corporation tap and a brass soldering nipple at the other end of a piece of lead pipe 20 in. long having wiped joints. These goosenecks were expensive, frequently leaked and were generally unsatisfactory. Our master mechanic, Hugh Davis, suggested doing away with the wiped joints and making cup joints instead. This is done by driving a former into the ends of a piece of lead pipe and soldering in the tail piece at one end and a special coupling at the other, leaving when finished a female thread to receive the pipe. No soldering nipple is used. We are now making these in our own shop for about 80c. apiece less than the old style and each completed piece is tested to 300 Ib. pressure before going into stock. They are exceedingly satisfactory.
Standard Report Sheets for Small Filters
O assist the smaller filter plants in Illinois in
keeping their daily records so that standard, com- parable monthly reports may be made to the State Board of Health, Harry F. Ferguson, state sanitary engineer, has had a blank form for recording daily results printed. The forms are supplied at cost. One of them is reproduced herewith.
Vol. 94, No.
Solving the Every-Day
Electrically-Welded Steel Pipe Line for Vallejo Water-Works
HE city of Vallejo, Calif., on March 18, awarded «
contract to the Western Pipe & Steel Co. for °2 miles of electrically-welded steel pipe which is to briny water from Gordon Valley, where a new storage reser- voir is being built, to the city distribution system. Th: manufacturers, who are to install the line, have placed themselves under a $200,000 surety bond, guaranteeiny the pipe for a period of five years against all leaks and other defects due to faulty material, manufacture or installation, and agreeing to make good or replace any such defects without cost to the city. This is believed to be the first installation of its kind to be made in the West.
Bids on the electrically-welded pipe were 10 per cent lower and the guaranteed efficiency was 10 per cent higher than those for riveted steel pipe. Bids on both types were submitted by the same firm. Although the specifications did not call for electrically-welded pipe, two separate firms submitted bids on this type. Adop- tion of the electrically-welded joints saved the city about $40,000 on the job, the entire cost of which will be about $450,000.
The diameters will be 22 and 24 in., the length of the sections 14 ft. and the plate thicknesses *% and / in.
WATER PURIFICATION PLANT
ERATION REPORT FOR ~ 492 (Month) (Day) } LOW-SERVICE PUMPS COAGULATION HIGH-SERVICE PUMPS CLEAR NO. PUMP NO PUMP NO PUMP STAGE NO PUMP NO. PUMP NO. PUMP STAGE | | on om | on | "ort | | on | Om | | | | Time wt if FILTER OPERATING DATA > = Amount | LOSS-OF-HEAD WASH Amount |_LOSS-OF-HEAD WASH 35 No. On of (hours) rate 1000 Gal Start End Minutes Rate 1000 Gael. °. ( rs) rate al . mutes dl 1000 Gal. CHLORINE COAGULANT DOSAGE GAS FORMERS ~H N _ No. HLORINATOR DOSE NO 1 TANK NO. 2 TANK Grams PRESUMPTIV BACTERIA NO_1 CHLORINATO 9.2 CHL | pee TIME [CONFIRM | PER CC Puls. per Puls. per On Of | Lbs used On or Lbs used Gallon M 24 48 Hrs os minute Os os minute Pounds se On or or ' Ibs. per Ibs per oil at Settled 24 brs. 24 Fil > No. |< Filtered ? No. Fileered No. i RESID. CL. H ot Co ODOR 3H IGHT OF CYLINDERS| TOTAL ~ “HLORINE Time | RAW | FILT. | RaW | FILT. i Time Weight | Lbs used | Time Weght | Lbs used Us ) £ POUNDS ALUM USED LOW-LIFT PUMPAGE Gals. 3 TURBIDITY ALKALINITY AVERAGE DOSE (GR PER GAL.) , HIGH-LIFT PUMPAGE Gee Time Raw Sertied Fite. | Time Raw Filt. POUNDS LIME USED WASH WATER USED Gats | AVERAGE DOSE (GR. PER GAL.) 4 PER CENT WASH WATER % POUNDS CHLORINE USED AVERAGE DOSE (LBS PER MIL. GAL. . ' CHIEF OPERATOR OR SUPERINTENDENT
FORM FOR SMALL FILTER PLANT DAILY RECORDS, SUPPLIED BY ILLINOIS STATE DEPARTMENT OF HEALTH The original sheets are 84x11 in. There are 10 lines for pump records and 18 lines for results of individual filters.
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April 16, 1925 ENGINEERING
NEWS-RECORD 655
Water-Works Problems
The sections are to be dipped and wrapped. The esti- mated life of the pipe is 35 to 40 years. For a third of its length the pipe line will be under a head of avout 400 ft., the remainder will be under heads rang- ing down to a minimum of 100 ft. Each section is to be tested in the shop to a pressure of 225 Ib. per sq.in. and after installation the completed line is to be sub- jected to a test of 200 Ib. per sq.in. for 48 hours.
In the manufacture of this pipe the longitudinal seams are all made by the full automatic process, using direct current, and are guaranteed to 80 per cent of the full strength of the plate used. The circumferential seams are to be guaranteed to a strength of 40 per cent that of the plate. All angles are to be made in the field, either lap or butt welded, by making a diagonal cut in a standard pipe section and welding the two parts to- gether after a 180-deg. rotation. No single angles are to be more than 10 deg. This provision is made to secure the desired pipe strength and low friction loss.
The pipe coating is typical of California practice. After the 14-ft. pipe lengths have been immersed in “California asphaltum” at 400 deg. F. for 10 to 15 minutes they are lifted from the bath, drained and
' then, while still hot, put in a rotating machine and
wrapped spirally with “a mica covering” previously impregnated with “a high melting point bituminous compound containing not less than 25 per cent by weight of an alkali-resisting mineral.” The impreg- nated covering must weigh not less than 3.6 Ib. per sq.yd. The spiral wrapping, which is 18 in. wide and overlaps about 1 in., is applied under a 50-lb. tension. While the wrapping is being applied a stream of hot asphaltum is poured continuously between it and the pipe. This increases the thickness of the coating, bonds the wrapping to the pipe and seals the joint where the spiral “lay” overlaps. Flake mica is applied to the out- side of the pipe covering wherever surplus asphaltum oozes from the wrapping particularly at the joints.
A. Kempkey, consulting engineer, San Francisco, is in charge of design and construction on this extension.
Novelties in the New Water Filters at Windsor, Ontario
NIQUE features in the new water purification plant
at Windsor, Ont., include a double-deck pipe gallery, operation of two filters from one table, attention to architectural effects and a cemented-gravel slab over the perforated-pipe underdrains.
The plant is being built by the Essex Border Utilities Commission, which is a district organization for handling sewage and water utilities for a group of cities on the Canadian side of the river near Detroit. The nominal capacity of the plant is 20 m.g.d., arranged so that the capacity can be doubled when required. The
- plant is on flat ground and must deliver filtered water
by gravity through a rather long pipe line to the pumping stations at Windsor and Walkerville. This condition was met by a shallow clear-water reservoir and an unusually deep coagulating basin of 20-ft. water depth.
The pipe gallery is a two-story affair. The lower por- tion contains pipes only. The upper part contains
valves and rate controllers in a readily accessible posi- tion. The floor, which is of concrete, between the upper and lower portions, gives added strength to the filter walls on either side by acting as a brace.
There are ten filters of 2-m.g.d. capacity each, arranged in two rows on either side of the pipe gallery, each of the two facing filters constituting a pair. The filter connections are valved separately and the valves can be operated from the same operating table. The table mechanism is such that the two corresponding valves on each filter can be operated independently by a single lever. The pair of filters has a single rate-controller which can be used for one filter or two filters. The rate- controllers, which are specially made with a range from 1.75 to 4.25 m.g.d., are provided with an integrating recording mechanism. Rising to within about 6 ft. of the top of the filters, the effluent piping then turns horizontally through the controllers and the outlet of
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APPLYING BRICK VENEERING TO WALLS OF FILTRATION PLANT AT WINDSOR, ONT.
the controllers dips down and discharges into the clear- water space below the filters. This means that the effluent controllers, during periods when the filter is nearing the end of its run, will operate as a true siphon actuated by the down draft on the pipe leading to the clear-water reservoir.
A neat architectural effect is gained by covering the tops of the filter walls with white glazed brick and pro- viding a wainscoting of white and colored glazed brick around the entire interior of the building. The filter operating floor, as well as the floors of the approach ves- tibule, are surfaced with terrazzo. The entrance lobby is decorated with marble. All of the exposed concrete walls on the outside of the structures are veneered with 4 in. of brick with an air space.
A 6-in. layer of cemented gravel is laid over the perforated-pipe underdrains at the surface of the gravel layer, which will be about 18 in. in total thickness. The gravel is about the size of navy beans and will be mixed with one part of cement to fourteen or fifteen parts of gravel and placed in the filter. It will thus form a porous layer looking like ordinary gravel but coated with a thin film of cement. It is expected that this cement will hold the gravel together and prevent the material from working up into the sand. If at any time it is desired to penetrate to the bottom of the filter the gravel can easily be broken out and replaced.
J. Clark Keith is chief engineer for the Essex Border Utilities Commission and William Gore, of Toronto, is consulting engineer.
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Vol. 94, No. 1:
How a Town of 10,000 Revamped Its Water-Works
Financial, Physical and Political Exigencies Over- come—Doubled Rates and Bonds Resulted from Educative Publicity By H. A. TOLBURG City Engineer, Monmouth, I].
INCE 1900 the city of Monmouth, IIl., has been confronted with a water-supply situation that has been more serious than the average citizen suspected. Until 1921 the problem was passed along from one administration to another, each trying to shun it. The old pumping equipment had reached such a deplorable
actual pumping cost,
Solving the Every-Day
an investigation and subsequent report on the true cv: dition of the water-supply system.
From tests run in September, 1921, to determine 1! it was found that the city w. paying 19c. per 1,000 gal. to deliver the water into t}).. mains under 30-lb. pressure. Then the investigatic. was carried further to determine the condition of th. water mains throughout the city. Several of the oldes: mains cut into were found to be in as good condition as when new, although they had been in the ground more than thirty years. The physical condition of th:
Surge tank | Recorder | Lxcifer --3'Diam. Switch boara- concrete pi a” Loi £33 wi |Generator Well ~ Elevated Gasoline Gas | | engine omg (gas /ine) fo 8 _ Deep Well “Gasoline feea © | |
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state that each year as the warm weather approached the people suffered a water shortage, and the domestic pressure was cut down from 55 lb. to 25 lb. to conserve a small reserve for fire protection. No administration was willing to allow the public to understand the exact condition. In 1921 the city council, realizing that the water-works had been more or less of a political foot- ball for years, determined to bring this question to a head by laying the facts before the voters in language that they could understand. It was decided to provide Monmouth with a water system that would be a credit to the city. In July, 1921, the writer was employed as city engineer and given as the paramount problem
Reservoir 70'x 120' x 12" Deep
PUMPING STATION DESIGNED FOR MAXIMUM FLEXIBILITY
old pumping plant was almost as low as it could be and yet operate. The over-all efficiency was only 17 per cent.
Early in October the facts and conditions were pre- sented to the city council, which appointed a special water committee, consisting of the council’s water com- mittee, the mayor and city engineer. This committee formulated several plans of financing the new water system and finally determined on the plan of a $90,000 bond issue.
In addition to the bond issue, an ordinance was passed, creating a water-works rebuilding and construc- tion fund, into which $6,000 was to be put each year from the profits of the water-works. To create this profit the water rates were raised from 35c. to 60c. per 1,000 gal. This rate was known to be excessive, but due to almost an emergency it was deemed wise to carry it out. Realizing that it would take a number of years to create a fund sufficiently large enough to rebuild our water-works through this system of rev-
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April 16, 1925 ENGINEERING
NEWS-RECORD
§57
Water-Works Problems
enue, we deemed it wise to have some money to make repairs if necessary, to the present plant while we were building the new plant.
As is often the case in small-town politics, the party which was out was opposed to the water-works plan, only because the “outs” did not want to see the admin-
through the news columns of the press. Each night there appeared some citizen’s views of the water-works. On Jan. 8, 1924, at a special election, the bond issue was approved by a vote of two to one.
The plan adopted, now almost completed, consisted of drilling two wells to a depth of 2,445 ft., which penetrated the Potsdam sands. These wells were to be finished at 124 in. from St. Peter’s sands, 1,150. ft. below the surface. Then above that for 662 ft. was used 14-in. outside diameter copperoid pipe, and above
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WELDING, PLACING AND TESTING WELDED CAST-IRON PIPE FOR MONMOUTH RECONDITIONED WATER-WORKS
A—Rig for testing section of welded pipe for tension. Both joint and pipe withstood 7s tons in tension test which broke a 14-in. bolt after elongation of 3 in.
B—Bronze welding two lengths of 18-in. cast-iron pipe in cradle. A band of molten bronze from a }j-in. brass rod is laid down on the closely butted joint of the two cast-iron pipes. The collar thus built up is about 2 in. wide, 4 in. thick on the edges and § in. thick at the center directly over the pipe joint.
istration reap the glory which was sure to come from the construction of a new plant. Bonds for sufficient funds to carry on the rebuilding program were opposed. It was determined then to enlighten the people as to the needs of,a new water plant. Sound business men and good citizens were taken over the old water system and the entire program explained. Later on these citizens were asked to make a statement to the newspapers over their signatures of their findings relative to the needs of a new water-works. This publicity program was laid out covering a period of two months-of advertising
C—Two up-ended lengths of pipe after having been welded to pipe already in well. A vertical weld was made by laying the molten bronze against the pipe above a 4x2- in. collar of flat steel, the upper edge of the collar making a 3-in. shelf on which to start laying on the welding ma- terial. A wood clamp of two 18x18-in. timbers 4 ft. long tightened around the pipe by four 2}-in. bolts supported finally 56 tons. Drillers’ tools may be seen at front of the crew.
that for a distance of 488 ft., was used cast-iron well casing, 18 in. inside diameter. The cast-iron well casing was put together by brazing, which, it is be- lieved, is the first attempt to install cast-iron pipe in a deep well by this method. S. B. Geiger, artesian well contractor of Chicago, had the contract for drilling the two wells, and The Chicago Oxwelding Corporation did the welding. It was found through tests at the Armour Institute of Technology that the brazed joint on 18-in. cast-iron pipe would hold more than 78 tons. As the test was: not carried beyond this point, we
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658 ENGINEERING
NEWS-RECORD Vol. 94, No. 1
could not say how much more the weld would be good for. But that was more than the weight that we had to handle, so the test was not carried to destruction. The insertion of this pipe was successfully carried on without mishap by means of special clamps. The wells are pumped with deep-well turbines, designed for a capacity of 900 g.p.m. against a total head of 214 ft. The static head of the Potsdam waters in Monmouth brings the level to within 183 ft. of the surface. The deep-well turbines are driven by 75-hp. 2,300-volt slip- ring motors, controlled by float switches in the reser- voir, so that when the water drops 4 ft. the pumps are automatically started and continued in operation until the reservoir is refilled.
A reservoir of reinforced concrete 70x120 ft. in plan by 12 ft. deep was provided. It has a capacity of 750,000 gal. and is covered with a wood roof.
Each service pump has a capacity of 450 g.p.m. against 60 lb. pressure. The pumps can be operated in parallel or in series. When operated in series they deliver 450 gal. per minute against a total pressure of 120 lb. which is the fire pressure. The units can, therefore, be used at any time to help out the fire pump. The fire pump with a motor of a two-speed type has a capacity of 1,500 g.p.m. and is controlled from the cen- tral fire statiofii When a fire alarm is sounded the chief determines where the fire is and with what pres- sure he will want to fight it. If it is an ordinary resi- dence fire he presses button 1, which starts his fire pump and gives him 1,000 g.p.m. at 80 lb. pressure. Should the fire be in the factory district or business district he presses button 2 and gets 1,500 g.p.m. at 120- Ib. pressure. Then, should he want still more water, it is possible to put the two service pumps in series and get 450 gal. more at 120-lb. pressure, which gives him 1,950 g.p.m., sufficient to combat any fire that Monmouth might have.
The switchboard is of the latest heavy contact type. Each piece of equipment may be operated automatically or manually. For standby equipment, to be used in case the local power plant is out of commission, a 2,300-volt generator of 90-kw. capacity is driven by a 6-cylinder 225-hp. gasoline engine. The generator is of sufficient capacity to operate one deep-well turbine and the distributing pump or the fire pump alone, which makes the service safe for continuous operation under any condition.
To the bond issue of $90,000, $23,000 was added from the water-works rebuilding and construction fund, making $113,000. The total cost of the water plant was $112,860. We expect to retire the bonds within a period of seven years, because the excessive water rate will net a yearly profit and saving by the installa- tion of the new plant of $19,850. This figure will give us a good working margin. Further securing these
figures is our contract with the pump company, which guaranteed a surety bond to the amount of the cost of the equipment contract and operating cost of not to exceed 1.92 kw. per 1,000 gal. delivered into the mains under 60-lb. pressure should the pump fail to deliver the water at that rate for one year’s time. A favor- able contract with the local power company was made whereby we were yiven electrical power at the rate of 2c. per kw. which will further reduce our operating cost even below the figure the surety bond guaranteed.
The town of 10,000 population too often spends money
Solving the Every-Day
for local improvements through political channels, rather than through good business channels. It has been our experience in promoting and bringing to a close this water-works issue, that the politicians were the hardest losers, and that unless ways and means sre contrived whereby they can use their political sti¢k. then one immediately ceases to be of use to them and at once is criticized by a large number of people. In our case by using good business tactics we were ab| to educate the average citizen so that he could believe. from knowledge gathered by himself, that the adminis- tration was for the people and not the politicians.
Rehabilitation of Small 30-Year- Old Water-Works Plant
Kirksville, Mo., Plant Brought to Date by New Intake Pumps, Force and Discharge Mains, Filters, Chlorinators and Pipe
By F. M. VEATCH Of Black & Veatch, Consulting Engineers, Kansas City, Mo.
IRKSVILLE, Missouri, has recently completed and
put into operation a modern water purification plant which, together with new supply mains, new pumping equipment and water main extensions, has transformed an obsolete system, constructed piecemeal during the past thirty years, into an up-to-date and efficient water-works.
Kirksville, at the time of the first water-works im- provement, 1894, was a town of approximately 2,000 people and has had a rather uniform growth to its present population of 7,500. The city is the birthplace of osteopathy and at the present time the non-resident population due to the two osteopathic colleges together with the. Northeastern Missouri Teachers College, amounts to approximately 3,000 persons.
Until now the water consumption has been determined entirely by the amount available, since the supply has been deficient and the new plant has not been in service long enough to establish a rate. It is assumed that the consumption will be in the neighborhood of 0.75 m.g.d. or 75 gal. per capita.
Historical—The original water-works was constructed in 1894, at a cost of $20,000. It consisted of two deep wells, a steam pumping plant, and 23,760 ft. of mains with 40 fire hydrants. This system became inadequate within a few years and an additional $40,000 was spent for impravements, which included a steam pumping plant on the Chariton River, 64 miles from the city; a 7-in. kalamein force main to the city, and an addition to the distribution system of 20 hydrants and 53,450 ft. of pipe.
In 1900, a 12-m.g. reservoir, in excavation with rip- rapped sides, was constructed at the highest point in the supply line, approximately one mile west of the city, and a. small high-service station was added. In 1914, the muddy river water became irksorne and two very crude 0.25-m.g.d. uncovered sand filters were con- structed together with a 0.5-m.g. coagulating basin and a small open clear-water reservoir. Improvements at the river station included the installation of boilers and the introduction of a 1-m.g.d. crank-and-fly-
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NEWS-RECORD 659
April 16, 1925 ENGINEERING
lVater-Works Problems
wheel steam pump. In 1919, two 600-g.p.m. oil-engine- driven centrifugal pumps were installed, and in 1921 4 100,000-gal. elevated tank was constructed. The makeshift filters were never satisfactory, and in 1922 plans were started for a complete renovation of the system, the movement being furthered by insistent de- mands of the fire insurance underwriters and by citizens who desired more and better water.
Latest Improvements—The improvements consisted of 4 new intake line to the river, a 12-in. cast-iron force main to the reservoir to replace the 7-in. kalamein pipe line, which was badly deteriorated and was also in- adequate in size, a 1.25-m.g.d. rapid sand filter plant, a new high-service pumping equipment, a new 12-in. dis- charge line to the city, and considerable extensions to the distribution system. The improvements cost:
Pipe line construction ..... 66s cee 38,650
Intake—The new intake consists of a substantial con- crete crib extending to rock, fitted with a removable bar
mixing and to eliminate short-circuiting. Alum alone is used for coagulation since the large storage capacity precludes excessive turbidity and this chemical is fed by means of solution tanks and orifice boxes, at the inlet and at the outlet of the coagulation basin. The filter plant is of standard construction throughout and consists of three 0.5-m.g.d., hydraulically operated units, completely housed in a fireproof brick-and-con- crete building, which also houses the high-service pumps.
The available location of the filter plant made it necessary to have the operating floor approximately 10 ft. above the normal ground level. To prevent ex- cessive and unsightly filling, around the filter cells, the walls of the building were brought up outside the con- crete work, with a 3-in. air space left between the inner and outer walls to prevent freezing and spalling of the damp walls of the filter cells. This construction per- mitted the pipe gallery and pump room to be at the ground level, desirable for light and convenience.
Liquid chlorine is used for sterilization and is fed into the suction header through a Wallace & Tiernan pedestal-type machine.
A 0.66-m.g. rectangular covered clear-water well of reinforced concrete was provided, located adjacent to the pump room.
The total cost of the purification plant was $42,178 and the unit prices per cubic yard were as follows: exca- vation, $1; reinforced concrete, $25; plain concrete, $20.
EXTERIOR AND INTERIOR VIEWS OF NEW MBCHANICAL FILTER PLANT FOR WATER-WORKS OF KIRKSVILLE, MO,
screen, and connected to a concrete suction well, on the river bank by means of a 20-in. cast-iron pipe.
Low -Service Pumping Plant—The existing river plant was not changed, as the pump is in gvod working condition and a city owned and operated coal mine, a few feet from the boiler room door from which coal is delivered to the boilers at a cost of approximately $2 per ton, makes this method of pumping most economical.
Force Main—The force main from the river to the reservoir and the discharge main from the filter plant to the city, were constructed of standard cast-iron pipe, with the Classes A, B, and C distributed according to the pressure, and contain approximately 1,480 tons of pipe which cost f.o.b. Kirksville, $64.17 per ton for Class A and $59.17 per ton for Classes B and C. The contract, price for laying the line, inclusive of hauling, trenching, backfilling and all labor and line materials, was $0.43 per foot.
Purification Plant—The existing 12-m.g. reservoir was left without change, since the leakage is negligible, and the existing coagulating basin was utilized by the construction of weirs and baffles to provide for 1-hr.
Pumping equipment—Electrical power was selected for use at the high-service station since the available prices for current were favorable and since, eventually, the city will install generators at the river station where cheap coal is available. Two motor-driven 600-g.p.m. centrifugal pumps were installed for ordinary use, and a 1,000-g.p.m. steam-engine-driven centrifugal pump was installed for emergency use and for fire protection. Wash-water for the filters is pumped by means of a gasoline-engine-driven 2,700-g.p.m. centrifugal pump. The cost of the pumping equipment was $7,583.40.
Extensions to Mains—The extensions to the distribu- tion system included the removal of 16,470 lin.ft. of 4-in. steel pipe and the installation of 30 hydrants, 2,970 ft. of 4-in., 17,360 ft. of 6-in., 10,520 ft. of 8-in., and 3,280 ft. of 12-in. east-iron pipe. Class B standard cast pipe was used throughout and cost $63.17 per ton for 4-in. and $59.17 per ton for 6-in. and larger. The costs of pipe laying, in cents per foot, were: 4-in., 27; 6-in., 33; 8-in., 36; 12-in., 48.
The engineers for the work were Black & Veatch,
Kansas City, Missouri.
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660 ENGINEERING
NEWS-RECORD Vol. 94, No. 16
Water District and Power Company Adjust Differences
By ARTHUR L. SHAW Designing Engineer, Metcalf & Eddy, Boston, Mass.
HE COMPLETION of the new electric pumping
plant of the Kennebec Water District at Waterville, Me., late in the summer of 1924, marked the consumma- tion of a project whereby a publicly-owned and a privately-owned utility with conflicting interests were able to adjust their differences to mutual advantage. Prior to 1919, the water district pumped the water required by Waterville, Fairfield, Winslow and Benton mainly by means of water power owned by the district on Messalonskee Stream. A steam plant was held in reserve and used only when the water power was in- adequate. The Central Maine Power Co. operated several hydro-electric stations at various points along the same stream, the newest of which was the Rice’s Rip development, about four miles upstream from the district’s pumping station.
When the Rice’s Rip plant was put into operation, in 1919, the method of operation of this chain of de- velopment in conjunction with the rest of the Central Maine system was such that water was withheld except for 9 or 10 hours each day, during which time the rate of flow was so great that it could not be utilized to advantage by the Kennebec Water District. The limita- ions of the water-supply aqueduct, from China Lake, 8.4 miles distant, and of the distribution system, made impossible the pumping of the entire daily supply in so short a period. In consequence, the Kennebec Water District was forced to pump largely by steam and later by electrically-driven pumps installed to supplement the steam plant in this emergency.
Litigation followed, but was discontinued in 1923
FIG. 1—NEW DAM AND HYDRO-ELECTRIC STATION, WATERVILLE, ME. This hydro-electric plant of the Central Maine Power Co.,
Waterville, supplies current to drive pumps of the Kennebec
Water District. when an out-of-court agreement was reached under the terms of which the Central Maine Power Co. is given a long lease of the Kennebec Water District privileges and the district in return is to receive power from the Central Maine system without charge up to amounts estimated to be equivalent to the water power which the district might have developed for pumping had there been no interference from the company’s develop- ment. Under the agreement the company has built a new dam and 1,000-kva. power house (Fig. 1), combin- ing the heads of the two old dams affected by the agree-
Solving the Every-Day
FIG. 2—NEW ELECTRIC PUMPING STATION OF KENNERBIO« WATER DISTRICT, WATERVILLE, ME. Contains three motor-driven centrifugal pumping units of
2-, 2.5- and 3-m.g.d. nominal capacity, with space for iu fourth unit; traveling crane, gages, Venturi meter register, chlorinating apparatus and heating plant; also a Wate! laboratory in an upper room. ment, and the water district has constructed a new elec- trically-driven pumping station (see sub-title of Fig. 2 for equipment, including laboratory).
The hydro-electric power plant is operated by push- button from the pumping station and the current is delivered onto a switchboard in the pumping station whence it is taken for driving the motors or dispatched to the outside lines of the power company. If power is required for the pumping station, when the new hydro-electric plant is not being operated, it is drawn from other lines of the power company.
As the result of the existing understanding, the power company is enabled to develop and operate its several plants along the Messalonskee Stream in the most economical and advantageous manner, without en- croachment on the rights of others, and the water district is provided with free power for its present and probable future pumping needs for a considerable time to come, thus affecting a mutually beneficial solu- tion of a problem which promised vexatious and pro- tracted controversy in the courts.
Copper Sulphate Sown on Ice of Cheyenne Water-Works Reservoirs
By P. R. REvIs City Engineer, Cheyenne, Wyo.
N applying copper sulphate to the two reservoirs of
the Cheyenne water-works this year, the chemical was scattered on the ice or sowed like grain instead of being distributed as heretofore by means of bags drawr through the water by boats. The old method was ¢ slow, expensive and uncertain process, the chemical not being evenly distributed over the large area of ou) reservoirs. Strong winds endangered the lives of the boatmen and the distribution was so poor that the water sometimes had a disagreeable taste for a few weeks on account of not all the alge growth being prevented. Application by boats was performed twice a year, once in April and again in August.
The work this year, on the ice, was done in mid- winter. Taking advantage of a wind, each man covered a strip 150 ft. wide at a single passage across the ice.
The size and capacity of the reservoirs are as fol- lows: Granite Springs, 185 acres in area with a capac- ity of 1,734 m.g.; Crystal Lake, 127 acres and 1,482 m.g. capacity. <A total of 9,625 lb. of copper sulphate
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April 16, 1925 ENGINEERING
NEWS-RECORD 661
Water-Works Problems
was used, which was the equivalent of very slightly over 30 lb. for each acre covered and at a dosing rate of 3 lb. per m.g. Four men did the work in five days.
The sulphate is in solution before it goes through the ice and is therefore not strong enough to be in- jurious to fish life, yet is sufficiently strong to have the desired effect upon alge growth. Some two weeks after the copper sulphate was scattered or at about the close of February, the ice was broken up. It is ex- pected that it will not be necessary to treat these reser- voirs again this year.
So far as the writer is aware, this method of treat- ment was never used before.
Drain Valve for Chemical Solution Tanks at Filter Plants
By C. L. B. ANDERSON Portsmouth, Va.
HE following description of a drain valve for
chemical solution tanks, developed along lines radi- cally different from valves commonly used in rapid sand filter plants for this particular service, is offered as a remedy for the troubles experienced with such valves, especially in the smaller plants. In valves of designs commonly used, the corrosion of all the working parts and of the seats by the chemical solutions, and the damage to the seats, disks and gates caused by sediment and grit in the valves when they are being closed, are the principal causes of the deterioration. During the fifteen years’ experience of the writer in the design of rapid sand filter plants, different types of valves such as wedge gate and double-disk gate valves, angle valves and cross-valves, and valves with working parts of different materials—as iron, bronze, brass and monel metal—were experimented with.
For use in soda solution tanks, and, to a lesser degree, in lime solution tanks, iron mounted angle valves have given the best service of any of the standard types used. In the larger sizes, wedge gate, sliding stem, quick opening gate valves, iron trimmed, have also given very good service. Plug corks are unsatisfactory.
In tanks used for sulphate of alumina and hypochlo- rite solutions standard commercial type valves have not proved satisfactory, but the best service has been obtained with valves having seats and working parts of bronze or monel metal. Phosphor bronze seemed to give the best service while Tobin bronze and monel metal gave approximately 80 per cent the service ob- tained from phosphor bronze.
The unsatisfactory service obtained from even the best constructed and special trimmed standard commer- cial type valves has caused many operators in the smaller plants to use light-weight standard angle or xate valves, with the expectation of renewing them from time to time as occasion demanded. This plan has the objection, in addition to the expense and trouble of renewals, of loss of chemical solution through valve leakage. In the smaller plants, where the chemical dosage is often based on the fall of the solution level in the chemical storage tanks, the uncertainty due to leakage is a factor to be considered.
A satisfactory drain valve for chemical tanks must
embody these characteristics: (1) simplicity of design; (2) few moving parts; (3) resistance to corrosion; (4) adaptability to different kinds of solutions; (5) not damaged by grit and sediment; (6) watertight under all conditions of service; (7) accessible for in- spection; (8) easily repaired.
During a visit about fifteen years ago to a small plant in New Jersey, the name of which cannot be recalled, the writer saw an effective, although crude, method that had been used to solve operating difficul- ties. This gave the writer an idea for the design of a valve which has seemed, after several years service, to answer satisfactorily the above requirements. The plant operator had just constructed concrete solution tanks the bottoms of which sloped to one corner. He had molded a funnel-shaped opening in the concrete leading to a drain pipe. These openings were closed with tapered wooden plugs surfaced with rubber gas- ket material, the plugs having wooden handles.
From the arrangement just described the writer de- veloped the valve shown in the accompanying drawing. The following quotation from specifications under which the valves were furnished will more fully describe them:
Elevation of Plug and Handle
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k DRAIN VALVE FOR CHEMICAL TANKS AT WATER FILTRATION PLANTS
Drain Valves For Chemical Solution Tanks—This valve is to consist of a body casting of cast iron to which is to be bolted with tap bolts a yoke forming a guide and support for the operating mechanism. The opening in the body casting is to be closed with a soft rubber plug connected with a rod and handle for operating the valve. For the steel lime and soda tank this valve is to be specially constructed as shown in the drawing. In this case all parts of the valve, with the exception of the rubber plug, shall be constructed of cast iron, steel and wrought iron as far as the same may be used. In the drain valve for the other solution tanks the rod to which the rubber plug is attached, together with eastle nut, washers, cotter keys and tap bolts, are to be made from Tobin bronze. The drain valve is designed to be used in connection with standard 3-in. soil pipe. Steady bearings for the valve stems are to be furnished and, placed near the tops of the solution tanks. .
By the use of a thick washer above the rubber plug the same design and parts used with the concrete tanks are made adaptable for use with steel tanks, being fastened to a pad riveted to the bottom of the tanks.
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662 ENGINEERING
NEWS-RECORD Vol. 94, No. 16
Letters to the Editor
This department aims to be a forum for the discussion of the views of engineers and contractors. The range of interest should be as wide as possible. Contributors are, therefore, asked to make their letters short.
Should Floor Slabs in Shallow Truss Spans Be Made Discontinuous?
Sir—Recently an 80-ft. half-through truss span was given me for checking the design. The span was designed for 20-ft. roadway between curbs. The trusses had a depth of 9 ft. c. to c. of chords with eight 10-ft. panels. The top chord was made up of two 10-in. channels 25 lb. per ft., and one 14x;‘-in. cover plate at the center of the span. The bottom chord was composed of two 10-in. channels 35 lb. per ft.
The concrete floor slab was designed continuous over floorbeams at panel points. The live-load was given as two 15-ton trucks with 6 tons on each rear wheel. The spacing of axles was 12 ft. c. to c., and 9 ft. c. to c. of trucks. It was possible for two trucks either to pass or meet, allowing four wheels in a transverse line. The slab was designed with the formula +s wl for dead-load and 0.8 x 4Pl for concentrated load with 30 per cent added for impact, and was 93 in. in total depth. It was reinforced with 8&-in. round rods spaced 43 in. horizontally 14 in. from top and bottom over supports and center of panels, and similar rods spaced 9 in. horizontally at bottom and top at the same points.
No attention was given to the evident deflection that would occur in the trusses, which would completely destroy the assumption of rigid supports on which the formulas used in the design were based. The slab as designed gave 650 lb. per sq.in. on the concrete and 16,000 lb. per sq.in. on the steel,’assuming the formulas to give correct results. However, taking account of slopes and deflections due to the deflection of the trusses, by a graphical method, the stresses were 850 and 21,000.
These results indicate that the slab would be more effec- tive if cut at the floorbeams, as the stresses would then be only 800 and 20,000.
If it is desired to design for stresses of 650 and 16,000, the continuous slab would require a greater depth than is required by simple slabs in each panel. In this case the continuous slab would call for a depth 10.7 in. and the simple slab for 10.4 in. J. L. ALBERS,
Structural Engineer, Tennessee Department of
Nashville, Tenn. Highways and Public Works.
Feb. 27, 1925.
Asphyxiation Due to Oxygen Depletion
Sir—The letter in Engineering News-Record, April 2, p. 572, on “Asphyxiation Due to Oxygen Depletion,” by F. H. Holway of Tulsa, Okla., is very interesting and instructive. I believe that the correct explanation has been given of the death of the engineer who went into the bottom of this concrete chamber.
Carbon dioxide is heavier than air, its specific gravity being 1.529. Consequently, with the chamber covered over and no agitation of the air within the chamber, the carbon dioxide would settle in a dense layer at the bottom. The first man into this carbon dioxide would, of course, suffer the most concentrated effect of it. Also when the lid was taken off the chamber, the outside air, which was probably cooler than that in the chamber, would settle and produce a certain amount of ventilation if the heavily charged carbon dioxide air in the bottom of the chamber were ugitated.
The question as to whether or not the concrete might bave contributed any part of the CO, is best answered by the fact that a fresh concrete surface absorbs CO, instead ‘f giving it off. In the process of hardening, calcium hydroxide occurs on the exposed surface of concrete which ‘4 contact with air, which alwavs contains CO. and which in this case contains a great deal of this gas, takes up the CO, and forms calcium carbonate. Of course, the amount of CO, thus absorbed is a very smal] amount and
produces only a skin coating on the surfe *e of the coner+: The amount thus absorbed would, therefore, have no ap))\.. ciable effect in reducing the foul condition of the air at ¢}. bottom of the chamber.
There is another possibility, of course, that might have contributed to this tragedy. Carbon dioxide is formed jy the earth whenever an acid solution comes in contact wit) the carbonate, and CO. is frequently given off from fissurv. in the earth. If, after pulling the forms, some honeycon) places in the concrete were uncovered, and if carbon dioxid: was being given off from earth fissures close to these honcy- comb places, there is a possibility, of course, that the carbon dioxide in the bottom of the well might have been augmented from this source. A. C. IRWIN,
Chicago, IIl., Manager, Railways Bureau.
March 26, 1925. Portland Cement Association.
Highway Bridge Impact Moderate
Sir—The editorial entitled “Dangerous Impact Action” in your March 19 issue, p. 464, has a special interest to me, as it was my privilege to be connected with the tests referred to while a graduate student at Iowa State College of Agriculture and Mechanic Arts during the summer of 1923. I do not believe the impression, given by the editorial, that highway. bridges must be designed fo, extremely high impact stresses, is warranted by any pub- lished data of the Iowa tests.
The determination of impact on highway bridges is an extremely difficult task and is accompanied by many variable effects which render individual readings, or even sets of readings, open to suspicion. This will be true til! we are able to design better instruments than we now have for this type of work. It therefore does not seem that the conclusion “impact is measured more properly by the extreme or highest values obtained in a series of experi- ments rather than by the average values” may properly be drawn from the data.
Again quoting from the editorial, “Because of the vari- ability of the effect, there is the further possibility that under full loading (with a number of trucks on a bridge at the same time) larger impact percentages may result than in the case of only one or two trucks. The effects due to the individual trucks may neutralize each ather or they may reinforce each other, and in the extreme case they may produce a larger total stress than corresponds to the sum of their individual effects.” This is inconceiv- able to me. The large impact percentages given in the report of Professor Fuller are due to a 2x4 placed in the most unfavorable position for the member being considered. Even if it is admitted as a possibility that a fleet of truck- traveling at ten miles an hour, close together, wouid al! hit potholes in the bridge floor equivalent to 2x4’s, so time: as to produce simultaneous effects in any given member still the trucks distant from this member would produce effects much less in percentage than those produced by the truck passing over the unfavorable pothole, for the inertia and elasticity of the structure itself would absorb part of the effect. Note that the percentage of impact in the end post is approximately only one-quarter to one-half as great as in the hip-vertical, although for impact in these two members the 2x4 is placed in the same position. In any case the above quoted conclusion could not be drawn from the data presented thus far by Professor Fuller, neither could one say that the impact due to a fleet of trucks is necessarily as large as for one truck.
In the Iowa Bridge Specifications the paragraphs relating to impact, based on the 1922 tests, call for 334 per cent impact for the floor system, 66% per cent for floorbeam hangers, and for the truss a as given by the formula
7 L + 200 where LZ equals the loaded length in feet producing the maximum stress in the member and S equals the computed maximum live-load stress. This portion of the specification was written by Professor Fuller, I believe. Certainly noth- ing extreme here.
Professor Fuller and his co-workers are doing a very
able piece of work on this difficult task. I dislike to see
conclusions drawn from these tests which are unwarranted
and may prove very expensive if put into practice. Urbana, II1., E. A. MACLEAN. April 3. 1925.
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April 16, 1925
ENGINEERING NEWS-RECORD 668
News of the Week
CURRENT EVENTS IN THE CIVIL ENGINEERING AND CONTRACTING FIELDS
Singstad Promoted to Chief Engineer of Commission
Work of Holland and Freeman to be Carried on by Engineer Who Served Under Them
Ole Singstad, engineer of design of the New York State Bridge and Tunnel Commission and the New Jersey Inter- state Bridge and Tunnel Commission on the construction of the Holland tun- nel, has been appointed chief engineer to succeed the late Milton H. Freeman.
Mr. Singstad was born in ‘Norway June 29, 1882, and’ graduated from the Polytechnic Institute of Trondhjem, with the degree of civil engineer in 1905. The same year Mr. Singstad came to New York, and after serving for a few months with the Central Rail- road of New Jersey as a transitman went to the engineering department of the Virginian Railway Co., where he served for two years as assistant engi- neer in charge of construction on the New River Bridge and the Hampton Roads terminal. From March, 1909, to March, 1910, he worked for the Hudson- Manhattan Railroad Co., New York, on the design of the Hudson River tunnel, and from March, 1910, to September, 1917, with the Public Service Commis- sion, First District, in charge of design of subways and tunnels in New York and Brooklyn, including the Williams St.-East River-Clark St. tunnel. From September, 1917, to June, 1919, Mr. Singstad was first with the Chili Ex- ploration Co., of New York, in charge of structural design and then with Barclay Parsons & Klapp, consulting engineers, New York, in charge of lay- ing out and estimating a rapid transit system and preparing preliminary de- signs and estimates on a_ vehicular tunnel.
In July, 1919, Mr. Singstad joined the New York and New Jersey Bridge & Tunnel Commission, first as designing engineer, July, 1919, to July, 1921, and then as engineer of designs until his ap- pointment to be chief engineer.
Money Voted for New Jersey Ship Canal Project
The project to construct a ship canal across the State of New Jersey from Trenton to Raritan Bay as part of the intracoastal canal system has been ad- vanced by the appropriation of $150,- 000 by the state legislature for the purchase of right-of-way, and by the inclusion in the rivers and harbors bill of an item of $1,350,000 for the dredg- ing of a 20-ft. channel in the Delaware River from Philadelphia to Trenton. The New Jersey Legislature expects to have part of the proceeds of the sale of the Morris & Essex canal to devote to the purpose of buying right-of-way for the new ship canal in addition to the amount appropriated.
Engineering Fifty Years Ago
From Engineering News, April, 1875
Abstract of an 1855 Report by E. S. Chesborough, City Engineer of Chicago, Ill. HAT Shall the Sewerage of the City Be Drained Into? Four principal plans, besides modifications, have been proposed:
(1). Into the river and branches directly, and thence into the Lake.
(2). Directly into the lake.
(3). Into artificial reservoirs, to be thence pumped up and used as manure.
(4). Into the river, and thence by the proposed steamboat canal into the Illinois River.
With regard to the fourth plan, or draining into the proposed steamboat canal, which would divert a large ana constantly flowing stream, from Lake Michigan into the Illinois River, it is too remote a contingency to be relied upon for present purposes; besides, the cost of it,, or any other similar channel in that direction, sufficient to | drain off the sewage of the city, would be not only far more than the present sewerage law provides for,-but more than would be necessary to construct sewers for five times the present population.
Should the proposed steamboat canal ever be made for commercial purposes, the plan now recommended would be about as well adapted to such a state of things as it is to the present, making it necessary to aban- don only the proposed method of supplying the South Branch with fresh water from the Lake, and to pump up from the new canal, or draw from the DesPlaines directly, flushing water for the West District, instead of obtaining it from the present canal at Bridgeport as herein recommended.
Progress on Exchequer Dam in California
Exchequer Dam, which is being built by the Merced Irrigation District on the Merced River in California, has now been under construction for six months. In that time, in addition to getting a very complete plant and equipment in- stalled within the limited space in the canyon where the dam is located, some 72,000 cu. yd. of concrete have been poured, and the dam has been brought to a height of 110 ft. above foundation. The ultimate height of the structure will be 325 ft. and the completion date is set for early next year.
Thus far the plant at the dam has been developed to the point where it can pour about 2,000 cu. yd. of concre per day. The contract is being carried out by Bent Bros. of Los Angeles.
City and Regional Planning Conference to Be Held
Three Organizations to Meet in New York City in April—Exhibit at Grand Central Palace
Regional planning, arterial roads, water fronts and waterways, and zon- ing practice in America will be the leading topics before the International Town, City and Regional Planning Con- ference to be held in New York City, April 20-25. Joining. in the conference will be the American City Planning Institute, the National Conference on City Planning, and the International Federation for Town and Country Plan- ning and Garden Cities, together with various affiliated organizations. An ex- hibit of city planning material from all over the world will be held at the Hotel Pennsylvania and at Grand Cen- tral Palace.
Among the many American and foreign speakers at the congress, the following may be noted: Dr. R.