-'■'..'' .:■'..,■; 1 IRRIGATION WELLS / WFII Iff IiLli C. N. CIRCULAR 404 TON MAY 1951 IRRIGATION WELLS are expensive but long-time investments, and it behooves a farmer to know what he is getting into before he orders a well dug. THIS DISCUSSION is not offered as a manual for well drillers, but to acquaint farmers with the oper- ations involved in the drilling of a well. By studying this circular, potential well owners may perhaps be helped toward reasonable decisions regarding location, drilling, development, and use of a relatively expensive asset to their property. THESE FACTORS are discussed, beginning on the pages listed: Origin of underground water 3 Distribution of underground water 4 The value of former stream channels 6 Well-drilling methods described 7 The well log 16 Checking straightness of the hole 17 Casings and linings 19 Perforating the lining 22 Developing the new well 23 Choosing a pump to fit the well 28 The well-drilling agreement 30 The Author: C. N. Johnston is Associate Professor of Irrigation and Associate Irrigation Engineer in the Experiment Station, Davis. The practices of irrigation well drilling and development are already established in California, where about two-fifths of the irrigated land is supplied from wells. Early development in the late nineteenth century was largely confined to the use of shallow water supplies that could be reached by hand-dug pits or wells and which could in turn be harnessed to the crude pumps and engines then available. Though the underground waters of the state have been utilized for over half a century, there is still lack of understanding as to their source of supply and the best methods of obtaining and using them. Underground water — where it comes from . . . Fundamentally, all underground water comes from precipitation (rain, snow, etc.) , as does the surface water. As is ade- quately demonstrated from records of precipitation and stream runoff, not all the water that falls appears as streamflow. Instead, some of it is intercepted by the vegetation and is evaporated back to the atmosphere, never reaching the ground. A portion that does strike the surface seeps or percolates into the earth at or near the point of contact. Some of this moisture is taken up by the roots of vege- tation, some evaporates from the soil sur- face, and the rest is stored in the soil. Map of the state of California showing concentration of irrigation pumping plants in the valley areas of the state. The reason for this concentration is mainly geological, as explained. -^> TRANSPIRATION 100% PRECIPITATION This drawing of a mountain and valley area shows how and where precipitation is distributed. This process is shown graphically in the accompanying drawing. Because these processes of precipita- tion, runoff, percolation, vegetational use, and storage have continued for millions of years, a balance was reached long ago ; the moisture in the soil at lower depths has reached a limit beyond which no more storage can be accommodated. When this condition prevails, any surplus water tends to flow through the soil mass. The downward pull of gravity on this water is often blocked by underground rocky formations or by other dense layers such as clays or hardpans; vertical progress is restricted to a combination of horizontal and downward movement, or to a sloped plane. The active moving force is still the gravitational pull, which is vertical; but the water, adapting itself to the easiest paths of escape under this force, moves horizontally or even upward at times if the source of flow is sufficiently high. • • • and how it gets distributed through the state Fortunately for California, the land masses of the state are so arranged that large agricultural valleys lie between ex- tensive mountain ranges. Thousands of years ago the mountains were higher and the valleys lower. Through the centuries, precipitation has found its way from mountain to valley. Weathering in the mountain masses has produced broken fragments of rock in varying sizes, and the streams have borne this weathered material both under normal flow and dur- ing the tremendous floods of ages past. In the process, these rock chunks were ground upon each other, their sharp edges were rounded, and smaller particles were formed. The grinding continued as long as the weathered rock remained in the streams, and the result was material ranging from coarse to fine. At first the streams had more slope than at present; they swept out from the mountain flanks at greater velocities and could transport the coarse fragments farther out on the valley floors than to- day. As they continued to dump these burdens, their beds lost slope, and their flow velocities were reduced. Because ma- terial therefore fell out of the streams sooner, the beds filled until they became higher than the surrounding territory. [4] Floods cut the banks, and new channels were formed, only to be choked in turn; new breaks occurred in the banks, and the streams were made to wander across the fan-shaped deposits of loose material left by former streams. The resultant areas constitute our pres- ent valley fills. Over these are flowing the descendants of the early streams. Some still leave their banks at flood stage and continue to form depositional slopes, deltas, or alluvial fans. The material dropped was at first the coarsest rock, then finer and finer material, till the finest par- ticles that make up our present sedimen- tary clays settled out in still water. This deposition, taking place along the down- ward course of the streams, made sloping sheets of varied texture, layer upon layer (see drawing). The early layers, having the greatest slope, intersect more recent ones; and so on to the top of each fill. As a result, the valley floors are composed of alternate layers of various material de- pending upon the conditions that pre- vailed when each layer was deposited. These layers have been cut and scoured by the wandering stream beds so they are not always unbroken planes, but more frequently form strips or bands or lenses of the original material. Toward the center of the valleys farthest from the mountains, deep gravels connect with the shallower gravels nearer the sides of the valleys; and so on toward the present mountain ranges, where great gravel FOOTHILLS This is a cross section of valley fill and shows detail of the strata from surface to bedrock. [5] banks still attest to the magnitude of former floods and the sweeping transpor- tational operations of streams in the past. These old stream channels still have value today Because the valley floors in California were formed in the manner just outlined, today a driller can sink wells through these layered materials in the valleys with some hope of finding strata that contain an effective supply of water for irrigation. The water-bearing strata encountered are usually portions of a large sloped sheet of that same type of material, with the upper ends of the slope crossed near the mountain flanks by the present streams. These streams, percolating in passing, re- plenish the water-bearing strata more or less completely after each year's pumping season. Additional water reaches these layers by gradual infiltration from the valley surface. Water-bearing materials. In the search for strata containing a water sup- ply, one may safely assume that not all these materials are effective sources. The reasons are numerous. To be effective, a stratum must transmit or carry water within itself rather easily. In other words, if supplies cannot move through it to a well fast enough to replace the water being taken out, the well will run dry. Water will pass through porous ma- terials. Clean gravels and coarse sands, with comparatively large pore spaces be- tween adjoining particles, are therefore the water-producing strata in our wells; although the fine sands and the clays may have just as much pore space, the pores are smaller because the particles are finer. Water cannot pass through the small pores as easily as through large ones. In drilling for water, the hope is that the drill will intersect a good proportion of gravel and coarse-sand layers. Some- times, however, a large amount of these materials may occur in a well and yet be unproductive, or almost so: the strata drilled may be isolated from the rest of the valley fill by layers of clay laid down by the prehistoric wandering streams. Fortunately, this situation is not normal in California valleys, so that most of the potential water-producing strata are ac- tually usable. Water levels in wells. The water in a productive stratum has arrived there from some higher point by moving through the transmitting layers and through the stratum itself. If the stratum has been filled so most of the water can escape and if a well is put down, the water will rise no higher than the source of sup- ply. If the source is above the well, the water may flow from the top of the cas- ing; such a well is called flowing artesian. If the source is somewhat lower than the top of the casing, or if the water comes up part way in the casing above the sup- plying stratum, the well is nonflowing artesian. Wells in which the water fails to rise above the supplying strata are non- artesian. Drawdown. When an artesian well flows or is pumped, water movement takes place in the supplying strata. This movement encounters resistance, or fric- tion; and consequently there is less pres- sure, or head, at the well than before flow started. As a result, the flow diminishes, or the water levels in the pumped well drop. Other nearby wells, if connected with this same stratum, feel in turn the effect of flow within the stratum caused by the first well, and their pressures also are lowered in time. This lowering is noted as the seasonal drawdown in pumped areas from spring to fall. The recovery of water levels in winter indicates that infiltration to the conduct- ing strata has replenished the water used and that pressure under the area has been restored. If the levels in wells do not re- cover from spring to spring, the infilter- ing supply is inadequate; and unless this lowering process stops, the available sup- a ply to the area may be seriously depleted. [6] Often, in an area, the seasonal recovery is less than the seasonal drawdown in the wells for several years, after which the two reach a balance. Under these condi- tions, the lowering of water levels repre- sents the reduction of pressure necessary at the wells to permit the required flow from the source through the supply strata. In other words, some recession in general levels is necessary in order that the water needed may move toward the area of use. In moving, it encounters re- sistance; flow is impossible unless it can pass toward a zone of lower level or lowered pressure. In areas where the seasonal recession is unabated, there must be some means of replenishing the underground supply. The job of replenishment for an area can be attempted only with the cooperation (es- pecially financial) of all who will benefit. It may require the storage of water be- hind expensive dams, the construction of canals and ditches, and the operation and control of percolating areas. Since these works require a large investment, they should be undertaken only with sound engineering advice and planning. Storage would be in the upper drainage basin, and the percolation areas would be in the present stream bed and on prehistoric beds represented by the gravel bluffs and terraces that fan out now on the foothills at the point where the present streams enter the valleys. From certain areas of the state come reports on the procedure in organizing, designing, and constructing such under- ground water-replenishment systems. As an example of progress made in planning water-replenishment systems, there might be cited the report made by Mr. Fred H. Tibbetts to the board of directors of the Santa Clara Valley Water Conservation District on the 1934 well-replacement project. This report outlined the physical aspects of a typical valley and recom- mended a procedure for the organization and construction of a water-replenish- ment system. Drilling methods — three are commonly employed Because the water-bearing strata in the valleys are a considerable distance below the surface proper, manual excavation is laborious. In many areas the difficulty for the hand-constructed wells has been in- creased by the lowering of levels neces- sary to permit flow from the source. This lowering makes hand-digging extremely dangerous as well as difficult. To elimi- nate the hazards and to ease the burden on men, power-driven equipment has been developed. These mechanized devices have replaced the manual drilling of irri- gation wells in California except for occa- sional small-bore shallow developments for windmill or similar small-capacity pump use. The three principal types of well drill- ing are excavation, cable, and boring. A fourth type, but of minor importance, is jetting. Excavation. As its name implies, ex- cavation is the development of a hole, usually rather large, using hand or power shovels of various design. This, the oldest "A" HAS BEEN EXCAVATED BEYOND EDGE OF CRIBBING. A partially mechanized, excavated well with wood cribbing following closely on the digging. [7] method, has not changed fundamentally in the hand-operated phases since Bible times, when Joseph's well was excavated. In those days one man started to dig, throwing out the dirt till the hole became too deep. Then a second man, standing part way down, relayed the dirt to the top ; and so on as they went deeper. Some- times a bucket or basket replaced the chain of men, and often many diggers worked together on the floor of large holes that became community or munici- pal wells. Today man supplements his efforts with mechanical devices, often lift- ing the spaded material from the bottom with power from a tractor or an old auto- mobile, by use of suitable pulleys and lines upon which is hung a container such as a wheelbarrow. Safety requires that a carefully made continuous lining or cribbing be lowered as the hole deepens. This is particularly true in the unconsolidated sedimentary material normal for California valley floors. Unless such precautions are taken, the digger's life may be forfeited by a cave-in occurring at any depth more than 3 or 4 feet from the surface. The hazard This is a clamshell bucket. An orange-peel bucket used on power diggers- POWER-UNIT EXCAVATING EQUIPMENT CRIBBED EXCAVATION Typical power equipment used for excavated wells. Note how cribbing follows the excavation. [8] FORCING CASING DOWN DOUBLE BEAM ANCHOR OR DEADMAN STOVEPIPE CASING BEING FORCED DOWN BY USE OF HYDRAULIC JACKS OIL DRUMS FILLED WITH WATER OR SOIL AS SUSPENDED WEIGHTS AT TOP OF CRIBBING TO FORCE IT DOWN "•*$& SURFACE jo- iner/eases with the depth; the cribbing must follow the excavation, leaving just enough space to permit trimming of the vertical earth walls so the cribbing can pass downward. Cribbing may bind on the sides of the hole because of slight caving or for other reasons, in which case its top can be weighted to force it down. [ Water or earth in suitable containers de- vised on the job make simple weighting materials to force the cribbing down- ward. The cribbing for the sides of the hole is necessary to hold back caving formations. To mechanize the excavation method requires clam-shell or orange-peel type buckets which both dig and remove 9] the material. These buckets can excavate under water, unassisted, as long as the cribbing prevents a cave-in. If water is encountered, hand-excavated pits must be kept relatively dry by pumping— another complication, which generally limits the penetration of hand-dug wells into watered zones to about 6 to 10 feet. In a few instances, drillers have made large excavations into water-bearing gravels from the surface, leaving an open cut (sloping banks) filled with water at the bottom. Since the inward motion of the water to the cut resulting from pump- ing disturbs the bottom and banks, the pump foundation shifts, and it is there- fore difficult to set pumping equipment near the water. An alternative to the open cut is to open it at first, install porous casing along the bottom, and then refill the pit, placing coarse, clean gravel along the porous casing. The pump may then be connected to the porous casing with satisfactory results. The cribbing and cas- ing mentioned above will be discussed under well casing. PLAN OF OPEN PIT OR WELL rpfc^ THIS BANK LIABLE TO SHIFT, RUINING FOUN- DATION FOR PUMPING PLANT SECTION A • A Plan and section views of a typical open-cut well, showing how the pumping unit is installed. [10] *es£» r~\ 13 j. ffl /Al k-sAy g Si Cable tools. A, suction or sand bucket; B, scow or bailer; C, dart-valve bailer; D, jars; E, drill stem; F, standard bit; G, star bit; H, heavy-duty bit (spudder type); I, rope-sub; J, bit gauge; K, swage; L, drive clamps. Any or all of such tools may be needed in well drilling. Cable Equipment. This type covers a group of devices suspended from a cable, whose vertical motion causes the tools to surge up and down in the hole, breaking the formation at the bottom so that other cable tools (or sometimes the same ones) can remove the loosened material. Under this type is grouped a large family of equipment having varying usefulness. Cable tools differ radically from the cable-suspended orange-peel and clam- shell buckets used in excavated wells : in- stead of gouging out chunks of material, they loosen, soften, and entrap. Most of them work best in water, which promotes the softening and suspends the loosened material for entrapment in the body of certain tools. The loosening and softening results from the pounding at the bottom of the hole. In general, cable tools require a water supply at the well site during op- erations and are limited to the making of holes less than 14 to 16 inches in di- ameter. [in In friable material, tools of the bailer class are used both to loosen and to entrap the solids being cut. The result- ant loosening combines surge action with some cutting by the bottom edges of the bailer or scow. The material thus loosened is suspended in the water in the hole, and the valve at the bottom of the tool admits this mixture as the tool sinks farther. When the tool is full, the cable is reeled in, and the entrapped debris is dumped. In hard, compacted substrata and in rocks, the bailer-type tool will not act rapidly, and heavier bits of the flat or star section are therefore suspended on the cable. These bits batter the resisting ma- terial to small fragments. A scow or bailer must be lowered into the hole, replacing the bit and removing the cuttings. Where there is danger of the bit's jam- ming, and where an additional weight will be more effective than the bit alone, heavy rods (called jars) with a sliding These are hand-operated tools for excavat- ing. Shown are three sizes of augers; a carpen- ter's bit-type auger; clamp-type digger. yoke section are fitted above the bit. The sliding yoke permits a hammering blow from above on top of the rigid lower sec- tion and also an upward blow if the bit itself is stuck. The remaining tools supplement those mentioned. The swage, for example, forces out the walls of a collapsed casing. Tapered and smooth, it will true up a collapsed section so the other tools can pass. Operating trouble often means a broken cable, with loss of tools at the bottom of the hole. Although each oper- ator has his own devices for fishing out lost tools, there are few standard pieces of equipment for the purpose. Drillers do, however, perform marvelous feats in recovering tools. Because drilling proceeds through the casing, comparatively accurate samples of the material being cut are dumped reg- ularly at the surface; the depths and structure can be accurately noted. Such a record is necessary when the time comes to perforate the casing opposite the po- tential water-producing strata. Perforat- ing methods will be discussed under well casing. Boring. This method involves equip- ment that is turned from the surface by use of a drilling column. The cutting faces are in tools located at the bottom of the column; according to the device in use, they may or may not need to be re- moved to bring the cuttings up from the bottom of the hole. Bored wells may be classified under two procedures. In the first, the boring tool works best in cohesive materials, such as clays, and requires no water to func- tion most efficiently. This tool has an augerlike blade at the bottom. When the drilling shaft is turned at the top, the cut- ting faces of the auger peel the soil from the hole, discharging it into the cylindri- cal chamber above the bit surfaces. The cuttings thus collected are removed by re- traction of the tool, which involves the dismantling of all drill shafting each time. This tool fails if it encounters loose gravel [12] SQUARE DRIVE SHAFT DRIVE CHUCK ROTATION CUT-OUT SEC- TION SHOWS DETAIL OF CUT- TING FACE AT BOTTOM OF AUGER POWER-DRIVEN PINION RING GEAR ON TABLE OR BASE OF DRILL RIG AUGER NOTE: AUGER BODY MAY HAVE HINGED SECTION THAT CAN BE CLEANED MORE EASILY Detail of a power-driven auger, showing a part of the driving mechanism that turns it. or sand, or if water enters the hole, sluic- ing the cuttings out of the container when the tool is elevated from the bottom. Its chief use is to supplement the cable tool when sticky, resisting materials can be cut more speedily by the auger-shaped bit than by the churning cable tools. The hand-sized models of these augers, typi- fied by some posthole diggers, are oc- casionally used in sinking small-diameter wells 50 to 100 feet. As has been noted, the power-driven tools are limited in their application to the cutting of certain ma- terials. The other type of boring equipment is the so-called rotary rig. In such drilling, a water supply must be provided as soon as the well is started. The tool operates efficiently only in a thick muddy suspen- sion, of its own stirring, called rotary mud. The cuttings from the hole are re- Rota ry-d rilling rig, showing reamer in center foreground; bit to right of rig; seven drilling pipes; bailer (under bit). Truck is used to haul water for mixing into the rotary-mud stream used. [13] -ROD ^ TRAVELING BLOCK HAIRPIN SWIVEL- KELLEY BAIL a a REAMER / \ o [14] moved by pumping this muddy mixture down the hollow drill shaft to the sides of the bit, whence it travels upward outside the shaft, bearing the loosened materials to the top (partly floating, partly wash- ing). If the rotary mud is not thick, it will not be heavy enough to float the cut- tings; a good, creamy suspension must be maintained. Since this mud-filled hole stands up securely while the whole well is dug, no casing is involved in the drilling proper. The mud not only elevates the cuttings while holding up the sides, but seals off the water-bearing loose gravels and sands so that they do not slide into the open hole. Usually a pilot hole of small diameter (8 to 10 inches) is put down first. This prospects the zone below the surface, lo- cates the potential water-bearing strata, and provides a well log on the spot from which the final depth of the well can be decided, as well as the location of the perforations. This pilot hole, if found po- tentially unproductive, is not costly; the driller can move to some other site at once, perhaps at a considerable saving to the owner. The completed hole follows the test hole as a guide, and the enlarge- ment results from the action of reaming blades attached to the side of the drill tool just above the bit. These blades can be adjusted by bolting on to the wings above the bit. Like all cutting tools, they tend to wear and must be resurfaced fre- quently by the welding of hard metals on the cutting edges. If they are not kept sharp and to size, their efficiency suffers. The final hole is usually 6 to 12 inches greater in diameter than the casing to be put into the well. After the casing is placed, the excess bore is filled with coarse, clean, uniform-sized gravel that acts as a continuous porous screen be- tween the hole proper and the casing. This AT LEFT: Some common rotary-rig tools used in rotary-drilling of wells in California. < OUTSIDE SURFACE OF "tf* Wy FINISHED ««j|W HOLE *\_ Typical section of a rotary-drilled well, with gravel envelope and casing shown in place. gravel is not admitted into the well until the driller has thinned the rotary mud markedly by pumping clear water to the bottom of the hole and washing the excess mud out of the top. At this time sufficient gravel must be available to fill the space outside the casing because the mud, when thinned, is not heavy enough to hold up the walls of the well for any considerable period. In addition, the gravel is care- fully introduced so that the casing will not be forced sideways. Since wells of this type sometimes continue to take gravel for several months or a year after being finished, there should be enough additional gravel to keep the hole full at all times. [15] This type of drilling encounters diffi- culties when the subsurface structures are deficient in clays because the rotary mud produced is not sufficient to fill the hole with the necessary thick suspension. When this happens, the driller must mix extra clay till the fluid has the desired density. Sometimes porous strata will drain away nearly all the mud before they seal off, and new clay must be worked up to bring the circulation back to the top of the hole. Rotary-drilled wells can be made very large-20 to 30 inches in di- ameter. This ample size, with the accom- panying large area of contact with the porous, water-bearing strata, is what com- mends them. There may be hazards in using the rotary mud, which may per- manently seal off some water-bearing strata; but the yields of these wells indi- cate a beneficial effect from their size. One possible disadvantage in the por- ous gravel envelope is that shallow-level impure water can contaminate the main well supply by seeping into the envelope and through it to the water-bearing zone. For large domestic wells the driller can eliminate this hazard by using a special concrete or metal lining outside the gravel for the depth of potential pollution, with a cemented joint between this lining and the inner well casing. Jetting. This minor drilling method employs the erosive action of a stream of water to cut a hole. The direction of the cut is controlled by the pointing of the stream in a downward course. Little control over the shape of the hole is pos- sible. One system employs a combination of jetting and boring. The high-velocity stream washes the earth away (as the casing is lowered in the deepening hole) and carries the cuttings up out of the well. Such a jet may cut or scour irregu- larly, swirling out first one way then an- other, so that the casing fits the cut vol- ume poorly. Since the use of the jet pre- supposes a considerable supply of water at the well side, only small-diameter holes (iy 2 to 3 inches) are normally dug in this way, and then to rather shallow depths. Such wells are suitable for only the most limited irrigation use, because of their small water yield. In certain areas, only one type of drill- ing equipment is represented, whereas in others, several types are operating. It is not always economical to bring a particu- lar kind of drilling rig to a territory that does not have one; to move these heavy outfits is expensive. For this reason, the desirable features of a particular method may not be available to an owner. Ar- rangements can usually, however, be made to complete the proposed well satis- factorily with the equipment available. A well log is helpful in locating strata The well log is the recorded description of the materials encountered in sequence throughout the drilling, with formations accurately noted as distances from the surface of the ground. All three drilling methods provide a good record of the stratification below the surface. With the exception of the rotary-drilling and jet- ting, all the methods, as part of the drill- ing, bring up samples of the immediate formation being cut. This permits inspec- tion and classification while depth is be- ing ascertained by frequent measurement. Since the driller is able to inspect and classify the cuttings frequently, he has a good record of the materials to be found below the rig. He cannot depend, how- ever, solely on the observation of cut- tings for his log. He must be constantly alert to the sounds and behavior of tools and rig, which give him the exact loca- tion of the change from one material to another. This ability to interpret the structure being cut, through the sound of the rig and the behavior of the tools, comes with practice. In general the rig is heard to labor harder in clay than in other kinds of material. The tools move down readily in sand or gravel, and— by a trained ear— the gravel particles can be heard rattling. [16] WELL LOG GRAPH DEPTH DRILLER'S NOTES DOE, JOHN S. E. OF DAVIS, 1V 2 Ml. Va mi. s. of hiway start may 10, 1942, 10 a.m. 12 FEET SURFACE SOIL 2 FEET SAND AND GRAVEL 17 FEET STIFF BROWN CLA V 1 FOOT YELLOW CLAY 2 FEET SAND 12 FEET GOOD GRAVEL (SOME WATER; 3 FEET SAND 3 FEET YELLOW TOUGH CLAY 13 FEET REDDISH CLAY 1 FOOT SANDY GRAVEL 27 FEET LIGHT-BROWN CLAY 5 FEET HARD YELLOW CLAY 18 FEET GOOD LOOSE GRAVEL 4 FEET BLUE CLAY— END HOLE It's important that the hole be straight Regardless of the drilling method, the resultant well should be as nearly per- pendicular as possible. This requirement must be met so that the pumping equip- ment can be inserted or withdrawn with- out becoming stuck, and so that the shaft- ing and bearings may not be subject to excessive stresses due to bending. The driller should start the first 20 to 40 feet very carefully to see that the hole is absolutely vertical; thus he secures a guide for the remainder. If careless or hurried, he may allow the tools to wander sideways even to the point where the lower part is drilled on a slant rather than in a vertical line. The owner would be justified in refusing payment for such a well if the condition can be discerned in time. On the other hand, curvature at a distance below the lowest possible set- ting of pumping equipment is not neces- sarily disastrous and need not prohibit the acceptance of a well. A vertical hole should be constructed as one having vertical sides and a con- 12' 14' 31' 32' 34' 46' 49' 52' 65' 66' 93' 98' 116' 120' PLOTTED FROM DRILLER'S NOTES SURFACE OF GROUND mz ° o' ► o„o %Y & a./. »•■'.•■ & (IK Y .°° o"o Bl > SURF. SOIL y SAND AND GRAVEL ► STIFF BROWN CLAY — YELLOW CLAY > SAND GRAVEL (GOOD) } SAND J YELLOW CLAY RED CLAY SANDY GRAVEL > LIGHT BROWN CLAY YELLOW CLAY (HARD) V LOOSE GRAVEL \ BLUE CLAY tinuously maintained true diameter. If the drilling tool wobbles, the resultant hole may be shaped somewhat like a cork- screw; the diameter of the bore may be too constricted in some sections, too great in others. If the driller is not careful, this condition can occur with any of the tools in use today. The casing will not readily [17] SUSPENDING LINE PLUMB LINE LEGEND L - VERHCAL DISTANCE TOP OF CASING TO TIE ON POINT OF CAGE [> = HORIZONTAL DISPLACEMENT OF CASING I - ANY CONVENIENT VERTICAL DISTANCE MEASURED ALONG SUSPENDING LINE d = HORIZONTAL DISPLACEMENT OF SUSPENDING LINE IN VERTICAL DISTANCE I CAGE Lxd CASING CAGE CAGING WELL USING SHORT SECTION OF PIPE FOR CAGE SUPPORTING WIRE FOR CAGE KEPT VERTICAL CAGING WELL USING WOOD FRAME CAGE. SUSPENDING LINE KEPT CENTERED IN CAS- ING This drawing shows how a cage may be used to determine misalignment in the bore of a well. [18] pass poorly trimmed holes. Clay is more apt to present this problem than other materials, although large boulders can create a similar effect by shifting the hole sideways. In the rotary-drilling, where the clean finished diameter depends upon the ra- dius of the cutting edges of the reamers, these edges, if worn, must be rebuilt to dimension, otherwise the resulting hole will be tapered, becoming smaller as drill- ing progresses. This condition defeats the purpose of the reamers, which are ex- pected to finish a clean cylindrical bore for insertion of the casing and for jacket- ing of the latter by the gravel envelope. Sometimes, with a gravel envelope, the hole is clean and vertical, but the gravel lodges somewhere on one side of the cas- ing, forcing it out of plumb in that vicin- ity. As a rule, reasonable care in the run- ning in of the gravel will eliminate this hazard. The owner should expect the driller to finish a well whose casing is plumb at least for the distance to be oc- cupied by pump and column. Any type of equipment described will, if properly used, satisfy this condition. Caging. One can check the alignment of finished well casing by lowering a "cage"— a piece of pipe which just passes the inside of the casing; or a wooden frame made on the job to the needed di- mensions, but slightly smaller than the inside of the casing. The cage must be heavy enough to sink if it encounters water. It is suspended from a strong, fine wire attached to the exact center of its top. As the cage is lowered to measured desired depths it is halted, and the sus- pending wire is caused to pass through the center of the top of the casing while hanging from a point 5 or 10 feet above it. As long as the suspending wire re- mains vertical while passing through the center of the top of the casing, the cage is vertically below that top. If the cage is off the vertical, the suspending point can be moved to the side to bring the wire into a vertical position. The displacement of the wire from the top center position is the misalignment of the casing at that depth. When the misalignment equals or exceeds a half diameter, the vertical wire will contact the side of the casing at the top, and no further check of plumbness will be possible with the plumb line or wire alone. The wire can be moved at the suspend- ing point so it does pass through the center line of the casing at the top of the well. In this position it lines up with the sides of the casing; and if the latter is out of plumb or is off the true vertical line, the wire is also. If 10 feet of the suspend- ing wire is found to be % inch out of plumb, the casing is misaligned % inch per ten feet of its length down to the top of the cage. In other words, if the cage is down 60 feet in the well and the suspend- ing wire is out of plumb % inch per 10 feet of length, the casing is out of plumb — x Y? inch = 3 inches at the 60-foot 10 depth. A good spirit level or an independ- ent plumb line can be used to check the deviation of the suspending wire from the true vertical. Casing, or lining — may be of wood or metal Well casing is the lining that restrains the earthen walls, preventing a cave-in and holding out loose materials. The terms lining and casing, though inter- changeable, have each become associated with special materials. Casing is the metallic tubing inserted in smaller wells. This iron tubing may be standard pipe or special fabricated pieces varying in length from 2 to 30 or 40 feet. Lining or liners are the wood, con- crete, or metallic walls installed in wells of large diameter. Large wells might be classified as from 30 inches in diameter upward. The wood with which they are usually lined is held fast against the ex- cavation by heavy open timber framing placed horizontally, with the planks that [19] form the lining proper standing verti- cally outside the frames. The frames may have circular or rectangular outer faces, but occasionally have other shapes— equi- lateral hexagon or octagon. Regardless of the shape, these framed internal braces must be carefully laid out and accurately fashioned of strong ma- terial so that they will retain their uni- form dimensions and shape as the well is dug. While the lining, or cribbing, is moving down following the excavation (added to from the top), severe strains are set up; and if the frames lose their shape, the vertical planking will be forced out of line and will bind on the earth walls, hindering the downward progress of the lining. In addition, a deformed sec- tion will not resist cave-ins as effectively as one that keeps its symmetry. Water enters wood-lined wells through slots or bored holes cut in the planking of the walls or through cracks between planks. In some instances lower sections Details of a wood-framed well cribbing, showing the breaking of joints on the vertical planks and the strong inner bracing. PLAN NJ SECTION A-A ELEVATIONS Special cylindrical wood cribbing with the planking on edge facing outward. This makes a slotted wall and allows entrance of water. that will be stopped in a water-bearing stratum are made up especially to form a vertically slotted wooden screen; the planking is placed with the edge face out- ward, and open joints are left between planks. Large-diameter concrete pipes are used occasionally for the larger wells. With these, new sections are placed on the top as the lower sections settle down imme- diately after the excavation. A continuous concrete lining can be made by pouring the concrete within forms at the top as the excavation proceeds, allowing the growing cured section to follow the ex- cavation. Under this plan one can have steel reinforcing throughout the concrete well lining, making the finished liner a homogeneous unit. Perforations for con- [20] Large-diameter concrete pipe may be used as a well lining. The perforated sections are put in place at water-bearing strata levels. crete walls must be cast at the time the concrete is poured. The cores for the per- forations may be wood, clay, or soft brick that can be removed after the cement has set. All perforations should be wider toward the inside wall of the liner; in a given opening they should be long and narrow rather than square or round. The long, narrow opening admits only the smaller particles of gravel while present- ing, at the same time, a large area of opening for the entrance of the water. Because of the wider section toward the inside, particles that do get past the en- trance section are prevented from ac- cumulating in the passageway and block- ing the flow. The entrance opening can be an inch wide if the gravel to be ex- cluded is larger than 1 inch. Casing as defined includes a wide range of materials, varying from light- weight (12 gauge or less) galvanized sheet metal tubes to standard line pipe. Lighter-weight materials are used on wells less than approximately 10 inches in diameter. The heavier casing is re- quired in the larger holes to resist col- lapse under the load of the caving sides. The light-weight casings, being shorter- lived than the heavier ones, are not recommended for irrigation wells. One exception is the so-called stove- pipe casing. This is made up of laminated layers formed by telescoping one cylin- drical section halfway through another so that light, easily handled, 30-inch lengths are assembled to make a continu- ous pipe of two or more thicknesses with all joints staggered. The sections are fastened together by hitting them forcibly with a sharp tool such as the point of a pick. The resultant dent in the outer shell seats in a corresponding dent in the in- OUTSIDE SECTIONS OF STOVEPIPE RESULT OF SINGLE BLOW ON STOVEPIPE CASING. A SERIES OF SUCH BLOWS GIVEN CASING ON CIRCUM- FERENCE ABOVE AND BELOW OUTSIDE PIPE SECTION JOINTS INSIDE SECTION OF STOVEPIPE JOINT BETWEEN OUT- SIDE SECTIONS Detail of stovepipe casing dented with blow from a pick to seal the sections together and allow for pulling (if needed) without separation. [21] side sheet. Four to a dozen of these dents per section join the sections sufficiently to permit pulling of the casing if need be. Without the dents, the sections would pull apart during installation. Casing is seldom made up at the well; most of it is prepared in special shops. Stovepipe casing is occasionally made up ready to roll into cylindrical form, with all rivet holes punched, and is then shipped flat to save space if it must be transported a considerable distance. Heavier casing is made from heavy, flat sheets that are cut to exact width, then rolled at the shop into cylindrical form in 20-foot lengths. The edges of the sheet are welded, completing the cylinder. A collar of the same weight metal is welded around one end of each of these cylinders so that half the collar is on the cylinder and the other half extends beyond. At SEE DETAIL AT JOINT SEE DETAIL AT JOINT SEE DETAIL AT JOINT r : WELD COLLAR WELD Details of casings and joints. A, line pipe or casing, without threads; B, the same, with threads; C, manufactured casing with collars welded to the joints on the job. the well the uncollared end of each cylin- der seats into the collared end of the one below, and the newly inserted cylinder is welded to the collar in which it rests. In this way the continuous casing is as- sembled on the job. Lightweight pipe, called casing pipe, and standard line pipe have threaded collars or couplings for joining the sep- arate lengths. The casing thread is finer than standard pipe thread; and casing dimensions refer to outside sizes, whereas pipe dimensions are for inside. Both these forms of casing can be purchased without threads if desired and are then welded together on the job, section by section, as the casing is lowered. All casing or lining must be perforated Regardless of the material used in well casing, provision must be made for water to enter through its walls in the vicinity of the water-bearing strata. The well log gives the location of these strata; but if the casing has been inserted as drilling progresses, no information may have been available to show where the per- forations or entrances should be. In that case the perforating must be done on the job. Many tools are available for this pur- pose. Each has one or more knives that are forced outward and through the cas- ing under the control of the well driller. The latter tries to obtain a regular pattern of these cuts or slots in the zone required, but cannot always be certain of accuracy until the well is put to test. If he knows the location of water-bearing zones, he can buy the casing perforated in the lengths required and, by inserting it cor- rectly, can make it match the water- bearing layers. Rotary-drilled wells give adequate opportunity to match water- bearing strata and casing perforations: the log can be ascertained before the cas- ing is ordered, and records from the pilot hole can be used. [22] Shop-made perforations are formed under perfect control and can be put in on even spacing with precision. This con- trol insures that the casing will not be weakened by the perforation job. The knife in the field job makes a tapered hole with the wide face inside, and any good shop-perforated casing is made with similarly tapered holes or slots. The shop-made perforation may be punched, chiseled, or torch cut, and is normally cleaner than the perforations made in the field after the casing is in the well. In some areas where fine sand is pres- ent in the water-bearing formations, the perforations must be screened so the per- forated casing is wrapped with specially formed wire to give a fine, narrow, spiral opening. Such wrapped casing is factory- made. The precaution is not necessary in most California wells. Developing the new well serves 3 useful purposes A well should not be considered finished when the casing, with the neces- sary perforations, is installed. It should undergo a development test to serve three objectives. First, this test proves whether a water supply has actually been found; second, it removes the sand and other foreign matter about the well casing so that only clear water is pumped; and third, it supplies a set of data to portray the characteristics of the well. From these data can be determined the size of pump to be used or the amount that a given pump can draw. The main purpose of the test is, of course, a water supply. The test provides the first proof of success or failure, and this proof is attained automatically along / W1M f^DPalWc'^L These are typical tools used to perforate a well casing after it is in place in the ground. [23] TAPER PUNCHED SLOT (FIELD JOB TYPE) SQUARE PUNCHED SLOT DRILLED OR PUNCHED ROUND HOLE TORCH CUT SLOT SPECIAL WIRE WRAPPED PERFORATIONS This shows details of several common types of perforations. At bottom is detail of one type of screen, made by wrapping with wire. [24] with the second objective— the elimin- ation of suspended matter from the water. Data necessary to the third objective also result from successful cleaning of the well. All of the porous materials that form the water-conducting strata tapped con- tain fine particles that will move toward the well when water is being withdrawn from the casing by pumping. In the rotary-drilled well, the rotary mud has flooded these strata to some extent. All drilling procedures mix more or less foreign material into the facing of these porous zones. These finer and foreign materials seal the pores of the water- producing strata and when they are washed out, the delivery of water to the well is facilitated. The procedure then is to create a circulation in the water- producing zones that will loosen the ma- terial to be removed. For this purpose, the drilling equipment provides prelimi- nary tools. Bailing. The bailer will bucket out the water and clean sediment from the bottom of the hole. (Rotary rigs, too, usually have lines for the operation of a bailer.) Each bailerful removed permits the entrance of an equivalent volume of water from the water-producing zones. This causes motion into the well, and the moving water carries the loose material with it. If the bailer is allowed to descend rapidly, the countercurrent resulting will force water outward and loosen more trash, which will follow the inward-bound current when the bailer is elevated. Rapid elevation causes a heavier surge inward, bringing in more material. The intensity of the surging is stepped up from gentle to strenuous activity as the work pro- gresses. By putting a jacket of canvas belting or rope about the bailer, one can make the casing fit rather tightly. When low- ered and raised it acts as a piston, forcing water before it. Similar pistons are some- times made of wood or other materials for the same purpose. The energetic operation of pistonlike equipment causes surges in the water- bearing zones about the casing, and through this disturbance the fine sedi- ments are moved into the well. Their movement usually ceases after the piston has operated for a while, and the develop- ment of the well by this means is com- plete, within the limitations of the method. Estimating discharge rate. Before starting to bail, a record should be made of the normal depth to water— the dis- tance from the top of the casing to the top of the water (see page 27). Then as bailing is done, one can keep a record of the number of bailerfuls of water that are removed in a given time. By again measuring depth to water while bailing for a known length of time— knowing the capacity of the bailer— it is possible to arrive at the discharge rate of the well. Drawdown. While bailing at a given rate, it will be found that the depth to water will be somewhat greater than it is when no water has been removed for a while. This lowering of the water level by the bailer is known as drawdown. The drawdown for any given well will be directly proportionate to the rate of flow. That is, if a 16-foot drawdown is noted when water is being taken from the well at a rate of 600 gallons per minute, then the drawdown will be 52 feet when 1,200 gallons per minute are being removed. This well characteristic is almost uni- versal in California, where artesian-type wells are the rule, and the formula can be safely applied when water is with- drawn from any elevation above the highest water-bearing stratum. As water levels recede below the highest water- bearing stratum, the area of entrance for the incoming water supply is reduced, so drawdown in that area of the well pro- gresses more rapidly with increased rates of removal by pumping or bailing. Developing pump. Since the oper- ation of the bailer permits only a limited WOODEN SURGE BLOCK OR SWAB MADE BY CLAMPING LAMINATED DISC BETWEEN PAIR OF PIPE FLANGES SWAB MADE BY WRAPPING BELTING ABOUT SCOW OR BAILER AND SECURING IT IN PLACE This shows details of surge block (top) and swab, used for bailing or for developing wells. [25] draught on the well, a test or developing pump should be used if possible. There are two reasons : first, the greater demand of the pump upon the water-supplying strata will probably cause increased flow velocities in these zones, and will bring in more solids; second, this movement of the loosened particles will further open the structure, so that the friction loss due to movement through them becomes less. This lowering of friction losses means reduced drawdown, and the well will be correspondingly improved. If the test pump does not remove these solids, the new pump will have to do so and its critical, carefully machined inner sur- faces will become cut and worn. Such wear, although very light, markedly re- duces efficiency; irreparable damage re- sults at the beginning of the life of the new unit, and the owner will pay there- after in larger power costs. The test pump can do the whole de- velopment job in a well, and most drillers can bring in a unit at a nominal charge. As a rule, the pump should be belt driven so that its speed is subject to control. It gives the owner the opportunity to sup- ply his own motive power if he desires. Speed control on the pump is necessary because the demand on the well should be gradually stepped up as the test con- tinues. The test may require 20 or more hours of operating the pump and at the end, the demand on the well should be at least equal to the desired discharge or, better, as much as 1% times the desired flow. If the demand is made as great as possible, the largest volume of loose material will be cleaned away from the water strata, and only clear water will pass through the new unit. Stopping and starting the pump during the test will cause surges to wash away any loose material near the perforated casing, sweeping it into the well. This surging is important; with clear water the ultimate goal, the well is not fully developed till the surge ceases to produce large new quantities of solids. A direct-connected, electric-motor- driven well-test pump is satisfactory for use in developing a new well if a dis- charge valve is supplied. Under this arrangement, one can step up the flow from the well gradually by opening the discharge valve a little at a time, running the pump for a reasonable period before each change in setting the valve. Surging is accomplished by stopping and starting the motor. If the discharge and depth to water in the well are recorded during the test, the drawdown for a given discharge rate is found to be much greater at first than toward the end. This is proof that the water-bearing strata have been flushed of their obstructions. Sometimes the developing pump draws in solids from without the casing and deposits them at the bottom of the hole. To eliminate this condition, the suction pipe of the pump is extended to the lower part of the well so that no volume of quiet water is left for settlement of the sus- pended load. If it proves impracticable to extend the suction pipe to the full depth of the well, the bottom must be cleaned with a bailer, sometimes dur- ing the test and necessarily afterward. Though one must remove the pump in order to bail, such procedure is some- times necessary in order that all possible strata may be developed as completely as possible and the maximum yield ob- tained, with the minimum drawdown. A stout piece of cord or a marked tape may be used for measuring the depth to water in the open hole. When, however, the pump is in the well, there is not much space between pump and casing; tapes and plumb lines become wet by contact with pipe and casing, and accurate read- ing is impossible. In that event, electrical contacts or air lines replace these devices. The electrical contact is made by means of an insulated wire with a shielded con- tact which is small enough to go through constricted passages, but which will ground or complete a circuit in the free [26] ELECTRICAL CURRENT FLOW INDICATOR BATTERY AIR LINE Vb" OR Va" pipe AIR LINE OPERATION DISTANCE BOTTOM OF AIR LINE TO TOP OF CASING = b + a + c (c CAN BE MEASURED) PRESSURE GAUGE READING IN POUNDS PER SQ. IN. X 2.31 = SUB- MERSION = b a + b -f c, LESS COMPUTED b AND LESS MEASURED c, GIVES a, THE DISTANCE TO WATER FROM THE GOUND SURFACE CONTACT ON CASING WELL CASING ELECTRICAL SOUNDING LINE INSULATION X WATER SURFACE LEVEL IN WELL BARE WIRE 1.+ u DETAIL OF END OF SOUNDER ELECTRICAL CONTACT OPERATION EQUIPMENT 1— BATTERY 2— AMMETER OR VOLTMETER 3— GROUND CONTACT 4— SOUNDING LINE LOWER SOUNDING LINE TILL RECORD- ING INSTRUMENT SHOWS FLOW OF CUR- RENT BY MOVEMENT OF NEEDLE. READ DISTANCE ON LINE TO WATER FROM TOP OF CASING (a f c). SUBTRACT c FROM THIS READING, GIV- ING a. DEPTH TO WATER These are devices commonly used for measuring depth to water, either by air line or electricity. water. When contact with the water is made, a bell rings steadily, or an ammeter shows that a current is flowing. The exact position of the water can be scaled di- rectly on the line or by removing the line from the well and checking the distance upon it with a tape. Fastening a few feet of fish line to the end of the sounding wire and stringing small weights on this line will materially assist the use of the sounder because the weights act as guides feeding the wire past constricted places. Another sounding device is the airline. This is a small-diameter pipe (^4 or % inch), usually galvanized iron (but pref- erably copper for long life) , run down at least 10 feet below the lowest pumping depth of water in the well. The exact [27 length of this pipe is recorded; then a pressure gauge and an air pump are con- nected to the upper end. When air is forced into the pipe, the pressure builds up inside till air begins to bubble out of the bottom of the pipe. Thereafter, no more pressure can be built up; the ac- cumulated pressure now equals the depth of submergence of the pipe. If the gauge reads in pounds per square inch, the sub- mergence in feet equals that reading times 2.31. The depth to water equals the distance from the ground surface to the bottom of the pipe minus the sub- mergence. Some air-line pressure gauges are marked in feet so that the depth to water is read directly on the gauge itself. Choosing a pump that best suits the well The drawdown characteristics of the well have been emphasized here because these data have great value in the selec- tion of a pump to fit a particular well. If the water in a well stands at an elevation only 5 feet below the top of the casing before pumping begins, it might be thought to be within reach of a pump situated at the top of the casing. This is not likely, however, because the water level will recede as soon as the pump is started. Any type of pump operates less efficiently as the suction lift increases. The maximum suction lift theoretically possible, but not actually attainable, is just under 34 feet. The centrifugal-type pump suffers more from increasing suc- tion lift than positive displacement forms of pump; and the centrifugal type, ca- pable of large discharge rates, is most frequently used for irrigation purposes. To avoid the possibility of excessive suction lift, this type of pump is installed in special designs, called deep-well tur- bines, that suspend the pump proper down inside the well casing 10 or 20 feet below the lowest water level after the drawdown is complete. The drive shaft 60 50 ^45 I 40 < £30 u-20 Z I 15 a! a 10 )EPTH TO * fATER WHE [ NJ PUMniNo 1200 v^.r.A I 1 -^ — * - STATIC WATER LEVEL o u. o in ill a t 200 H 400 ■\ h 600 -I h 800 — H 1000 —I — 1200 G.P.M. H r— .2 .4 .6 .8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 co. ft./$ec. Typical drawdown curve for a well. The preparation of such a graph is discussed on pages 29-30. [28] for such pumps normally extends to the top of the ground inside the discharge pipe, and power is applied at the top. Information regarding standing water levels and the pumping water levels is fundamental to the proper application of most irrigation pumps to the well. The following figures might be avail- able at the end of a development run: 1. Flow or discharge: 1,200 gallons per minute (clear water) 2. Depth to water while pumping at this rate: 45 feet 3. Depth to water 30 minutes or more after the pump stopped (static water level) : 15 feet 4. Drawdown for 1,200 gallons per minute: 30 feet (2 minus 3) 5. Desired pump capacity: 1,000 gal- lons per minute (required for crop) One can either lay out these items on a chart or graph and picture the condi- tions, or calculate a solution. The graph is the more enlightening and will be more useful in selecting the pump. The graph on page 28 illustrates conditions for the tabulation above. It shows that for a discharge of 1,000 gallons per minute, the depth to water will be 40 feet. This value could also have been determined by the following simple calculation : Drawdown for 1,200 gallons per min- ute = 30 feet. Discharge (gallons per minute per , , , , 1200 ._ „ loot drawdown) = = 40 gallons 30 per minute per foot drawdown. Drawdown for 1,000 gallons per min- 1000 oc , ute = = 2d leet. 40 Static water level plus drawdown (total depth to water) = 15 feet + 25 feet = 40 feet. \ N \ y* y" y~ ^ A ^ *«* ^^ y' \ N . \ . y' y* s N ^v ,B y^ N N x^ *■' x> % y y* y~ y* y* y* ^y'" \ \ \ 2 y *'' 3 1 y* + * y " .''' 1 2 3 _^y\ ^ -» HEADI HSCHARGE CURVES ^^ ,"' FOR PUMP BIDS OF SAME ^" NUM BER. 200 400 600 800 1000 1200 1400 G.P.M. This shows how drawdown and pump-head discharge curves are used to choose the right pump. [29] A pump capable of lifting 1,000 gal- lons per minute 40 feet is required if the desired flow is to be obtained at the sur- face of the ground. If the water must be discharged through a pipe line for any distance, the pump must overcome addi- tional lift because of friction loss plus any change in elevation (plus for a rise, minus for a drop) . In the simplest case, where the pump lifts the water out of the well only (1,000 gallons per minute, at a 40-foot lift) , bids might be obtained from vendors who have been asked to supply the head- capacity curves for each pump bid upon. These curves, or the data from which they are drawn, can be plotted on a draw- down graph for the well, the same scale being used for the pump curves as for the drawdown line. The graph on page 29 illustrates the result of plotting typical pump data from three bidders. The curve for pump 1 intersects the drawdown curve at exactly 1,000 gallons per minute and 40 feet, and the unit is satisfactory so long as the total lift for this flow remains constant. Part of the time, the pump may deliver 1,000 gallons per minute through a pipe line or to an elevation that adds, say, 10 feet more lift. The total lift then becomes 40 feet plus 10 feet equals 50 feet, and pump 2 is the most satisfactory if no less than 1,000 gallons per minute must be supplied. If pump 2 is used and if the discharge is released at the surface of the ground, the flow will become a little over 1,140 gallons per minute. There might not be two discharge con- ditions to be met; but if the water levels in the well were lowered, during the sea- son, a total of 10 feet (as is quite possible anywhere in the state), the static water level would then be 10 feet lower, and the drawdown curve would be shifted up- ward 10 feet all the way. The effect on the graph is to raise the drawdown curve to the position of line a. With this shift in water levels, pump 2 fits the require- ments for the minimum 1,000 gallons per minute flow. If pump 1 were put in the well and the water levels dropped the 10 feet, the discharge would become about 830 gallons per minute. Conceivably, the well test might have been made when water levels were down as far as could be expected, and they would therefore average 5 feet higher most of the pumping season. On this basis the average drawdown curve would be shifted downward 5 feet to b. Under these conditions, pump 3 might be satisfac- tory: it would deliver 1,040 gallons per minute most of the season, and not less than 970 during the short remaining period. Under this last assumption, there might be a choice between pumps 1 and 3, the purchase depending upon expected service, or upon efficiency of operation, or both. Every well or area has its own draw- down characteristics and can be effi- ciently fitted with a pump only if one considers them. For the well in the dis- cussion, several typical possibilities have been suggested to illustrate the use of these data in selecting the correct pump. For a proper fit of pump and well, similar figures on the particular well involved must be applied to the pump-perform- ance data available. A pump that has slightly more capacity than required is a better investment than one that just meets the requirements. Here is a suggested well-drilling agreement When a prospective well owner and a driller begin to discuss operations, the owner should have a basis on which to start. For this reason, the following agree- ment is suggested as a plan by which both parties can indicate their desires and promises. Most drillers are familiar with or have similar forms, and the owner should possess a general knowledge of the text before making final arrange- ments with anyone whom he wishes to engage to do the work. [30] Proposed Well-Drilling Agreement This agreement (signed and dated at the bottom by the driller and the owner) described below, covers the drilling of a water well on the land of the owner, whose property is located miles of the city of Direction State Owner: , whose post-office address is. Name Driller: , whose post-office address is Name Item: A. Location of well: - - Where and by whom B. Drilling method: , using driller's equipment. Type C. Inside diameter and depth of finished hole:* 1. Depth of finished well to be decided by owner after completion of pilot or test hole, if rotary-drilled. 2. Cost of pilot hole (if rotary-drilled well): (a) per foot if pilot hole only is drilled, and no charge for pilot hole if well is finished to speci- fied diameter to depth decided upon by owner under item C, 1 . (b) If owner decides pilot-hole showing is unfavorable, he may decide not to drill the finished well at that location and shall then reimburse driller for depth of pilot hole drilled at the rate named above and shall be subject to no addi- tional charge for services by the driller for work at that location. 3. Depth of pilot hole, not more than feet. Finished hole to be plumb of wall and of true diameter throughout its depth, per item C. Driller will supply owner with accurate log of all materials encountered to depth penetrated, to complete owner's record of well. Driller will, at owner's request, supply owner with samples of all identified gravels encountered and also supply data as to their depth and thickness. If the well is to be rotary-drilled, before its final depths and dimensions can be decided upon, the owner must have these data as supplied by the pilot hole. F. Casing: Depth Inside diameter in inches Type Weight or thickness Type of joints When and how joints are to be finished to to to to All field joints will be finished to make a tight, continuous tube with inside surface as smooth as possible. * Give determined dimensions and depths; or arrange for field decision on this item, and for entry in this agree- ment at that time. Perforations in casing: Depth How made Number per sq. ft. Dimensions Remarks to to to to G. Gravel envelope (rotary-drilled wells): (1) To be washed, clean gravel of inches graded diameter. (2) At least 3 yards gravel to be left at well when all gravel envelope has been run in. H. Water supply when drilling (who will supply water for drilling and charges, if any): I. Performance: Driller will take every reasonable precaution to protect owner's property while drilling and will remove his equipment and clean up the working area within days after acceptance of the job by the owner. Driller will not have to remove or clean up excavated material from well, but will keep it within reasonable bounds during the drilling operation. J. Payments: 1. Driller agrees to finish the well described, and in the manner given in the preceding tabulations, complete with the casing, plain and perforated, as decided upon and complete with the gravel envelope (if rotary-drilled), at the cost per unit depth to the owner as follows; and to make no other charge to the owner for the job: Depth in feet Casing diameter and type Cost casing per foot installed Perforations, cost per foot Finished hole, diam- eter, inches Cost finished hole per foot Cost gravel envelope if used, per foot to to to to 2. Owner wil pay. Payment procedure K. Development of well. The owner and driller mutually agree:. L. Insurance. Driller agrees to insure himself against all claims that may arise from any injury to his crew or himself while on the drilling job and absolves the owner from all responsibility in this matter. The owner and the driller, having agreed together, and each having accepted as his responsibility that portion of this agreement which becomes his to perform, have placed their signatures on this day of. , 19. Signed: at Driller Owner 20m-5,'51(3845)WP