Augunt 1981
INDUSTRIAL AND ENGINEERING CHEMISTRY
In all four of the states, along river valleys which are wide and atorage for water pumped from the stream8 at W s w . Substsntial p r o m has been made in defining them underground ahallow paaibilities in some of the Oklahoma valleys, where it has been mgnined that water pumped from the u n d d o w ahom improvement in quality. The construction of systems to utilize either underflow or &-river storage varies widely in cost and p m h b i l i t y from one location to a n o h . whether the pIanner of a new chemical plant expeota to ohtgin his water from a municipal system, already in operation, or to develop his own water upp ply, he must take into acwunt not only presently available supplies and potential additional s u p plies, but he mu& ale0 investigate the likelihood of wmpetitive demand8 for water before his plant is built. The largast increase in the UBB of water is in krigation projects and in the expansion of per capita demsnde for domestic we, including particularly the increased application of abconditiouing in reaidencee, factories, and offices and the increase in landscaping and small gardening. Expamion of irriition demands was mentioned in discussing
the Great Plaine of west Texas have been put in c a b crop despite the fact that the average rainfall is less than 20 inches. Here prolonged periods of drought can necavitate irrigation throngbout the entire growing 88aaon. similar expnnniona in irriition are evidmtly going to take place elsewhere in the region. Plant managers contanplatinglocation inthis district, therefore should determine to what extent the local community intend8 to use both current and potential water suppliesfor irrigation inatead of -wing them for industry. In some p k it 8eam8 quite possible that a plan might be worked out whereby the water will be uaed first in industry and then delivered in suitable condition for irrigation. ~ n o n r v r~ ~
~16. 1951. ~ i
i
Construction Requirements C. W.ROBERTS THE H. L. ?ERQTISON CO., HOUSTON. IEI.
I n the four-stat. area then Mmany facton which &t ing did riae during the wet RE Southwest hne a little of all climates industrial corutrudion, making tha problem wmmhat a w n and did fall during dif6.nnt froom other m. Th.M o m d l c d in tha the dry n e m . The s t r u e because it hen land at e a paper includ. the doction of sit., foundation &, suitture proper changed elemlevel and a t "XI feet; it has regions with little or no ability and avdhbility of mat&. and .nathe~tion slightly, if at all. The rainfall, 86 well aa a cona s p e d d y rdnfdl and humidity. A dLcupon ' ofopen ditlereuce in movement b4 construction M op+ to dad construction L oiwn. tween the floor and the &elaidwahle area of real estate visible only at low tide. ter portion of the huildmg This paper, theu, will be caused all the trouble. Pipe lines connected to the equipment on the flcmr and anchored restricted to a disoussion of the Gulf Col~sta~ Plain; and gento the structure were either broken or badly bent. The conorete erally to conditione which are peculiar to Texas. The &uthwest haa m m l mditions not found elsewhere which affect floor, which wvered a %foot earth I31 over the original top sod, con&mct,ion operstione 88 well 88 wmpleted plante. An erwa as much aa 6 inches. Ma&nery waa thrown out of aliiment and elect"trical wnnections were broken. By the time repairs ginaer or aontnrctor must have an appreciation of conditions penrliar to the GulfCoeat if he is to avoid expense, embwere made the ground water level would fall, the floor would stsrt down, and the breakkg of pipes and 6xed equipment would ment, and near disaster. Arranged m the order of appearance, but not neceassrily in start all over again. order of importance,tbees couditwns are: Inspection ravenled that all footingn were down to a fairly stable clay or caliche. Grade beams, or Iimt floor spandrel8, ex1. €w&ioll~ofni* tended mme 6 to 8 inches below the exterior grade. The area 2. Foundataonmda beneath the floor had been filled with materisl s e d from drive3. Suitability and availaqility of m a w s 4. Weather,cspeciauy ramfall and burmdity way and street excavation. The material w ~ wmmonly d known aa "black waxy" or "Teras gumbo," and any awt rise in the -ON OF SITE normal water table saturated the fill both by immersion and by Basic requkmnta for selection of rite are essentially the Bame capillary action. the world over. They are: mrcea of raw material, available A report from Raymond Damn, aeaociate director of the mark&, mst of tranapOrtation, labor supply, foundstion wndiBureau of Engineering Research a t the University of Texaa, tions, and simikr itcons. of said that nocording to laborstory inveatigatione an e+on 80 to Zoo% of dry volume waa to be expected when such mils SOItB were saturated to their liquid limit. The laboratory bad re corded swelling pressuras in aced8 of 30,oOO pound8 per square Teras does not have extensive fdea.5 where goOa bearing mafoot. D a m n observed floors raked aa much 88 18 inch- above t e a m t be found at some reaeonable depth. This is in wnthe original level solely because of expsnaion of the MI material. to mch looationa aa New Orlesna, with ita depth of soft Probably the best known clays are the Taylor marl nnd the ooze, or Mexim City, with ita overburden of volcanic aah. In Eagle Ford &ale of central T e r n , and the Beaumont clay of the fact, m U mtmcbnw (oftenpoorly designed or built) along *e Gulf Coast area. Them clays contain varyhg amounta of benGulf cmst mdez more damage by b e i i lifted than by nettletonib, and, of wuree, the expansion Wries directly with the ment. In one instaoes a buil-, amrding to the owner, rose amount of bentonite or wlloidal particlea present. @om buildand fell with the tide. O k a t i n I.eveslsd that the owner's era have experimentad with miXing these expannive clays with statement w p only slightly exaggerated. The floor of the build-
T
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
sand or similar materials. This practice has not gained widespread acceptance, however, because the mixing is difficult and at least 50% of the granular material must be used.
Vol. 43, No. 8
thick and 10 to 12 feet square-may tumble into the excavation. It is standard procedure to saturate even the smallest cracks with water to keep them from growing larger.
RECOMMENDATIONS
MATERIAL AVAILABLE AND SUITABLE
Foundations should go well below any soil material subject to volumetric change. All questionable material should be removed from the area to be covered by buildings and roads. If cost rules against importing suitable fill material, stable material may often be obtained at a reasonable deflh on or near the site. If the owner objects to leaving open borrow pits, an exchange of materials may be effected. In fact, this is the method used by The H. K. Ferguson Co. at the new Corn Products Refining Co. plant a t Corpus Christi, Tex. (Figure 1). Borings had revealed a deposit of highly satisfactory material between elevation -8 feet and elevation -23 feet. Several inches of top soil were removed from the entire site and stockpiled for future grading and landscaping. The rest of the material unsuitable for fill was then removed and placed adjacent to the proposed borroir pit. Several thousand cubic yards of particularly good mixed sand and caliche 11ere excavated and used for fill beneath floors and for deep backfill around foundations. All questionable material was used to refill the borrow pit. Stripping of top soils well outside the actual building is reconimended. It is not always practical to do this beneath exterior walks or drives, nor beneath grade beams where floors are supported independently of fill. I t is important, however, that enough of the unstable material be removed from such areas to allow a sand fill, or to place a cushion immediately beneath such beams or slabs. This cushion should be approximately one third the depth of the unstable material left beneath it. In no case should it be less than 3 inches thick if the soil beneath is at all questionable. In most parts of the country a construction Euperintendent starts to worry nhen his working area begins to get vr.et. Where bentonite is present, he also needs to worry when it gets too dry. Cracks will appear parallel to ditches, and slabs-12 to 14 inches
There is no building material in general use today which cannot be used to some 6xtent in the Southwest. A11 of the better known materials are of course available. Abundant deposits of concrete, sand, and gravel are available eome 60 to 80 miles inland. Finer grain sand, suitable for plaster and masons mortar, may be secured much closer t o the coast. Cement is manufactured from limestone a t several interior cities, and from oyster shell a t Houston and Corpus Chrieti. Cinders, which are often used in the North and East for fill and for roof cants, simply are not available along the coast. Roof cants are usually formed with various light-weight insulations such as expanded mica. Fills or cushions beneath floors are usually “bank” sand, which is entirely stable. Oyster shell is used for many things, including secondary roads built entirely of “mud shell” just as it is pumped from the bay. A better class road uses washed and screened shell held together by a suitable binder. Even a seal coat or topping will ensure years of excellent service. The flexibility of this type of construction makes it far better than poorly designed concrete placed over unstable soil. Not only is shell one of the principal raw materials used in cement manufacture, but recently it has also been used as roof covering in lieu of gravel or slag. Extensive strides have been made in the local manufacture of light-weight aggregate. One method burns the black Texas clays to produce a material light in weight, pleasing in color, and with unusual strength and insulating qualities. The delivered price is well below that of volcanic material formerly imported. Structural steel is used extensively, of course, and welded construction is being introduced rapidly. Widonless buildings are still considered radical, and have yet to gain widespread acceptance. Tilt-up concrete construction is very popular and includes many jobs using local light-n-eight aggregates. Tilt-up is not restricted to one-story buildings, a1 -
August 1951
1739
I N D U S T R I A L AND E N G I N E E R I N G C H E M I S T R Y
\
I stand that open construction
climate. Engineers and manufacturing men, steeped in the traditions of mills of the past, ct waged a Zyear discussion of the problem. Walls went in and walls came out, until those remaining represented the bare essentials for protecting delicate controls and electrical machinery. Figure 2 illustrates a combination of open and dosed construction. The livestock feed is dried by vacuum and drum methods in the exposed portions of the building and is bagged in the walled-io portion, ready for shipment. When real doubts occurred between advocates of open and closed construction, they usually compmmked by designing a structure that would be pleasing to the eye, both with or wiGhout walls. Then the walls were left out until such time BB a d e h i t e need appeared. In only one instance has it been necessary to install walls in &Tea8originally left open. Thin has been done in the suw olystallisation building to ensure better control of the proce88 during sudden changes in temperature.
OUTHWE
Figum 2.
Feed n o u n at Corpus C M i Plant of Corn Pmducta Refining Co.
thou# the general practice on multistory jobs is to provide a steel or concrete frame to which precast concrete slabs are attached.
ELIMINATION OF SOME USUAL BUILDING
REQUIREMENT8
.
Many practices considered absolutely neceseary elsewhere may be dispnsed with in the Southwest. For instance, it is not necessary to extend exterior grade beams or walls more than a few inches below grad.e to prevent damage from frost. It is not ueoessary to design roofs for snow load, although the need for wind load design may o6set this in certain types of construction close to the coast. Fuel atorage facilities are unnecessary, bemuse natural gas come8 to the plant in underground lines under hi# pressure. A few more cautious operators carry B small supply of fuel oil in underground tanks for emergency use. In numerous instances plant operators do not consider a p l a d fence necessary. Usually fences are installed only when the operation presents definite hazards to the public. Seldom are they installed to protect the property from vandalism, petty thievery, or damage during labor turmoil. It is rarely necessary to provide heating for aggregates or other stockpiles. Extreme weather is usually of such short duration that contractam postpone pouring until the weather is more favorable. No embedded steam lines are required for snow removal from drives or walks. No heating of downspouts or roof drains is necessary. In small buildings it is not economieal to provide basements to house heating plants, because small unit beaters burning natural gaa may be located on the floor or even in the attic. Generally it is not necessary to provide housing for workmen. They think nothing of driving.40 to 60 miles morning and night.
W€ATHER AND HUMIDITY Rainfall range8 fmm a low 1.78 inches in February to a hi h of 3.70inches in May, with the summer mouth averaging slighty less than 3.00 inches. There is no &tinct wet or dry season. If one divides Texas into four vertical stri 8 of ap roximately over 40 equal widths, the annual rainfall will range 8om sl&y Inches in the east to less than 10 inches in the extreme west strip. Snowfall ranges from a trace along the coast to 20+ inches at Amarillo. On various occasions deaigners have gone to great expense to secure dry floors. Thousands of dollms have been spent on selected granular IiII material. Other thousands have been spent on felt and membrane thoroughly mopped with pitch or asphalt to form a moisture stop over thie fill and beneath the concrete slabs. Except for the questionable valne of such a plications as insulation against m l e r tam eratures of the earth, h e is gained toward reducin the free an# absorbed moisture on the wearing surface of the s%b. Floors walls ateel members, metal equipment, conduits, and sprinkle: ipes become chilled during the cooler nights; they eollect and &? I moistnre as m n sa the daytime temperature ine m s . T h s condition presents a constant challenge to heating and ventilating design engineers. If provisions are made for maintaining a constant temperature during the 24-bour day, the condensation nuisance is greatly reduced.
OPEN CONSTRUCTION The Blue Bonnet plant of Corn Products Co. a t Corpus Christi, in one of the Southwest's outstanding examples of construction geared to meet operating requirements. Engineers took the
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