Ground Water in the Norwalk, Suffield, and Glastonbury Areas, Connecticut

Rams. — Springs of large yield Avhich lie lower than the point of utilization may be developed by means of hydraulic rams. A few exceptional wells also may be developed in this way. The hydraulic ram is a mechanical device which uses the momentum of a relatively largo vohuno of water falling a short distance to raise a small volume of V ater to a relatively great height. Theoretically 10() gallons fall- ing 10 feet would have enough energy to raise 10 gallons 100 feet or 1 gallon 1,000 feet, and other quantities and lieights in proportion. However, on account of leakage through the valves and elasticity and friction in the pipes this condition is not realized. A-, cording to tables given by Bj(")rling,' when the ratio of lift to fall is 4: to 1 the ram will lift 86 per cent of the theoretical amount; with a ratio of 10 to 1.. oo per cent; and with a ratio of 25 to 1, only 2 per cent. Bj()rling says further that the length of the drive pipe (from spring to ram) should be 5 to 10 times as great as the fall. The delivery ' Bjorling, V. R., Water or hydrauUc motors, pp. COl-STl, 1S04. GROUND WATER IN NORWALK AND OTHER AREAS, CONN. pipe (from the ram to the storage tank) should have an area of cross section equal to one-fourth or one-third that of the supply or drive pipe (from the spring or well to the ram). The rapidity of the beat should be as great as is compatible with perfect and complete action of the valves and in most rams may be regulated by adjusting springs or weights on the main valve. The noise made by rams is considerable and is transmitted along iron pipes but may be reduced by the use of lead pipe or of a section of rubber hose. Many people have been disappointed in trying to use rams because they did not realize their limitations. Rams must of necessity waste a large portion of the water. Before installing a ram careful meas- urements should be made of the flow of the well or spring during its lowest season, the amount of fall available, the amount of lift desired, and the horizontal distance from well to ram. If these data are sup- plied to the, makers they will be able to recommend the best model and size of ram. With proper conditions a suitable ram correctly installed will furnish a reliable, inexpensive, and permanent supply. It is customary to have the ram de- liver the water to a tank or reservoir in an elevated posi- sition from which it is dis- tributed by gravity. Windmills and air-'pressure tanks. — A popular method of suppljdng water is by the use of a windmill, pumj^ing jack, pump, and reservoir. Another equipment used by many people is the air-pressure system. A pump driven by a gasoline engine or electric motor pumps water into a closed steel tank containing air. As the water comes in it compresses the air and gives pressure sufficient to drive the water through the piping in the house. The pump is fitted with a snifting valve, which takes in a little air with each stroke to replace that dissolved by the water. Some of the tanks are equipped Avith telltales which give a signal or automatically start the motor when the water level in the tank is reduced below a set point It is the usual practice to put the tank in the cellar, but some are in specially constructed pits outside. Tanks and reservoirs built in the open are apt to allow the Avater to become disagreeably warm in summer and to give trouble by freez- FlGUUE 9.- the Avell TIME ELAPSED^ IN MINUTES —Graph showing the recovery of of J. S. Dewey after pumping. RECOVKRY OF CKOUXl^ WATHR. 41 ing in ^viIltor. Tho liciitiiig in ^iinuncr is an ;ulviinta<rt' in irrifjation, as the Avarni Avater «»i\ cs Ic^ss shock to (ho ])hints on wliich it is put. YIELDS OF I>1(! AVHLLS. One of tlic most important qnestions rehitive to the recovery of ground Avater is the anionnt avaihible. A study Avas made of the dug well of Mr. J. S. Dewey (Xo. 3. PL IV) near Granby station in East (uaiiby. The Avell Avas dug in stratified drift to a depth of 24 feet, i-N 4 feet in diameter, and rarely has more tlian 5 feet of water. At the time the well Avas visited it had been pumped continuously for five hours. Mr. Dewey very kindly stopped pumping in order that the recovery of the Avell might be observed. At intervals of about 10 minutes measurements were made of the depth from a datum point on the curb to tlie Avater surface. The results are given in the fol- loAving table : R'isc of Icccl in J. S. J^cirey'-s well. Time elapsed. Length of interval. Deptli to water sur- face from datum. Total rise of water surface. Rise during intervaJ. MinuUs. Minutes. Fat. Feet. Feet. 0 0 2(5.47 0 _ 0 10 10 25. 95 . 52 .52 22 12 25.53 .94 .42 33 11 25.14 1.33 .39 41 8 24.94 1.53 .20 50 9 24. 77 1.70 .17 t.o 10 24. 62 1.85 .15 71 11 24.49 1.98 .13 80 9 24.40 2.07 . 09 <tl 11 24.30 2.17 .10 100 9 24.23 2.24 .07 These data are also graphical!}' expressed in figure 9. As the well has a diameter of 4 feet, the area of the cross section is 12.6 square feet, and a rise of 0.01 foot is equivalent to an infloAv of 0.126 cubic foot, or (1.04 gallon. The rate of infloAv in any interval may be ex- pressed by the e({uation RXOM t Avhere /=rate of inflow in gallons per minute, A^=the rise of Avater level in hundredths of a foot, and ^=thc length of the interval in ininutes. If the curA'e in figure 9 is extended upward and to the right, it Aviil become asymptotic to a horizontal line representing a total rise of about 2.5 feet. It is reasonable to assume that when pumping Avas stopped the Avater had been depressed about 2.5 feet below its original level. Then the original IcA-el must have been 2.5 feet above the 26.47-foot level, or about 24 feet below the datum. The drawdoAvn 42 GROUlSrD WATER IX IsOEWALK AjSTD OTHER AREAS, CONN. of the water level at any moment may be obtained by subtracting 24 feet from tlie distance from the datum to the water level at that moment, as was done for the first column of the following table. The second col- umn gives the total inflow in gallons for each of the 10 intervals ( = /?X0.9-l), and the third column gives the rates of inflow as obtained by the formula above. In the fourth column is given the mean drawdown for each interval, found hj averaging the drawdown at the start with the drawdown at the end. In the fifth column are given the ratios of the rate of inflow to the rate of drawclo^vn. The average of these is 2.11, which means that reducing the level in the well by 1 foot increases the rate of inflow by 2.11 gallons a minute. The values in the third and fourth col- umns are plotted against one another in figure 10. The rather uniform slope of the line joining these points is ex- pressive of the relative uniformity of the values found in the fifth column. Relation of rate of infioiv to draiocloiDn. 4 1 / 1 111 1- / D / 5 I ° £3 a. tn z 1 1 J _j < 0 z^ J i 1 J I z / 0 / DRAWDOWN, IN FEET FicuKK 10. — Graph showing the relation of inflow to drawdown in tho well of J. S. Dewey. Inflow in Total Rate of Mean gallons Drawdown. inflow for inflow for drawdown for per niinute for each interval. interval. interval. foot of drawdo^vn. Gallons per Teet. Gallons. minute. Feet. 2.47 1.9-5 0 48. 80 4.88 2.2i 2.21 1.53 39.48 3.29 1.74 1.89 1.14 36.66 3.33 1.34 2.49 .94 18.80 2.35 1.04 2.26 .77 15.98 1.78 .86 2.07 .62 14.10 1.41 .70 2.01 .49 12.22 1.11 .56 1.98 .40 8.46 .94 .45 2.09 .30 9.40 .85 .35 2.43 .23 6.58 .73 .27 2.70 C2.21 o Average. By operating this pump so as to keep the water level down about l.To feet below the level it holds normally when not being pumped an inflow of about 3.5 gallons a minute is obtained. This well could be made to yield at least 210 gallons an hour or about 5,000 gallons a day. iiEcovEnv <ii' (iiioL'M) WATi:r. 43 vSiiuilar tests made on a well dug in till indicate a oapacit}- of only 320 gallons a day, and other tests on a well blasted into Ti-iassic sand- stone and drawing- its water froiu fissures in the rock showed a eapa- city of 210 gallons a day.^ INFILTHATION GALLEBIES. An inliltration gallery is a niodlfieation of a dug waW and dei'ives its watei- in the same way. Turneaure and Russell - say of them: WlitMH' trroimil water can be rojiclicd at: inoderatf depMis it is soinct ir.n's in- 1<^rcepted by ijcallerios constructed across the line of flow. * * * In loi'iii a jialiery may consist of an open ditch which leads tlie water away, or 11 may ))e a closed conduit of masonry, wood, iron, or vitrified clay pipe, provider I \Aiili numerousf sn\all openings to allow the entrance of water. * * * Clal- lerles are usually constructed in an open trench. They ai*e generally arran.ged to lead the water to the p\imp well, and may be provided with gates sw tliat the water may be shut off from various section.*. The cost of galleries is aliout tlie same as tliat of sewers in similar ground. It rapidly increases with depth, lull up to 20 or 25 feet it is sufficiently low so that the construction of galleries can often be advantageously undertaken. A gallery not only intercepts the \\-ater more completely than wells, but it replaces the suction pipe, it is more durable than either pipe or wells, and all trouble from inmiping air isf a"\(iided. Filter galleries maj' be so constructed that surface water is flooded over the ground around and above them and is collected in them after percolating through the soil. This will remove most of the suspended matter that makes the raw water unsightly', but unless fret|uent bacteriologic examinations are made it should not be trusted to completely eliminate the germs of disease. Chlorination or similar treatment might well be added as part of the process. DRIVEN WELLS. Driven wells are made by driving pipes into the ground with a niau.l or machine resembling a pile driver. The pipe is made up of enough sections to reach the ground-water level, and may have either an open end or a closed end.