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

Slink by saiul pniups. ami at first yielded 7,000,000 o-allons a day, I. lit soon fell off to only 2,000,000 oallons. Fifteen 4-inch wells were added, and increased the yield to ;},000,()()() cjallons, Imt the con- tractors considered it impossible to get 5,000,000 «2:allons, and aban- doned the contract. In 189+ the Hydraulic Construction Co., of New Vork, sunk by the jettin<!: method 120 open-end 2-inch wells a mile upstream from the old wells. As the total yield from both well fields v,-as less than 5,0(X),000 ^-Jilloiis a day, it was necessary to pump i-iver wator to supply the T.OOO.OOO-g'allon daily consumption in IHiK). In July. 1895, B. F. Smith & Co. commenced driving wells in a locality on Merrimack Eiver. and that company made 169 successful wells 27 to 40 feet deep, situated 150 to 350 feet from the river. The daily yield from this area, known as the Lower Boulevard Field, was about 4.000.000 gallons. Excessive corrosion of lead pipes in the city developed in 1800 and the State board of health attributed it to the high content of carbon dioxide in the water from the Cook wells. Consequently tlie Cook Held and the field a mile upstream on River Meadow Brook were abandoned in 1900. Fifty-two wells driven in 1900 and 125 driven in 1901 supply the Upper Boulevard station. The system was adequate for the demand in 1902 and 1903, but the supply began to decrease, and from 1904 to 1911 it was found necessary to use the Cook wells. A deterioration in quality, due to overdraft, was coincident ^^ith the decrease in supply. In 1911 there were added 118 new wells in the Boulevard field, so that there were then 450 wells available in this area, allowing for a few that had been aban- doned. The addition of these wells counteracted the overdraft and for several years the supply was satisfactory. The wells that have been sunk since 1900 are of the closed-end type. They are of 2}-inch extra-heavy iron pipe with a bottom sec- tion 38 inches long, in which are bored 180 half -inch holes. A heavy brass wire wound spirally around the pipe separates it from a brass screen with vertical slots, 20 to the inch horizontally and 6 to the inch vertically. The bottom is screwed into a cast-iron driving ])oint 4 1 inches in diameter that protects the strainer from abrasion. The wells are driven with a heavy drop hammer. As the forma- tion into which the. wells are driven is of fine grain, the strainers have to be cleaned at intervals. Each casing is ca2)ped at the sur- face, and a connection with the suction main is made l)elow the caj) through a T. In general, the wells are staggered 12 feet apart oi^ alternate sides of the suction main and 4 feet distant from it. I4iat the water comes in large part from the river is shown by the seasonal range of the temperature from 45° to 65° F.. which is much more pronounced than that of true ground water. The de- 62 GROUND WATER IN NORWALK AND OTHER AREAS, CONN. terioration upon overdraft is presninabl^y due to the fact that the water is then retained a shorter time in the earth and consequently loses less of its impurities.^ XEAVRURYPORT, MASS. At Newburyport, Mass., a flat gravelly or sanely stretch, which looked rather promising as a source of water supply, yielded little Avater when test wells were sunk. As there was urgent need of a water supply a plan was worked out b}^ which water from an impui-e source was pumped onto the plain and was recovered by driven wells after having percolated some distance. The quality of the water is stated to have been greatly impro^s^ed by this filtration process.^ NEWTON, MASS. A filter basin 1,575 feet long by 10 to 88 feet wide at Newton, Mass., lies parallel to Charles Eiver and intercepts the underflow to the river. This amounts to an excavation in the bottom of which are driven wells that collect the water. The system also includes a number of driven wells on the other side of the river.^ PLAINVILLE, CONN. In 1909 the Plainville Water Co. decided to install a ground-water supply for use in summer because of the annoying algal growths in the surface supply then used. Test wells on a site near Quinnipiac Eiver showed an underflow toward the river. Thirty driven wells, each 3 inches in diameter, were put down in two rows of 15 wells each at right angles to the direction of underflow. The depths range from 25 to 30 feet. Tests indicated a capacity of 40 gallons a minute for each well. The pump has a capacity of 500 gallons a minute, and if operated 10 or 12 hours a day it provides sufficient water. Despite the heavy draft on the ground water there has been no permanent reduction of the supply, and though the Avater level is depressed by the day's pumpage it recovers overnight. The water is excellent, though a little harder than the reservoir water.* QUALITY OF GROUND WATER. ANALYSES AND ASSAYS. The chemical studies made in connection with this report com- prise 3 complete analj'ses, 22 partial analyses, and 42 laboratory assays made by Alfred A. Chambers and C. H, Kidwell in the 1 Thomas, R. .T., Tbe Lowell Waterworks and some recent impiovements : New England Waterworks Assoc. Jour., vol. 27, Marcb, 1913. " .Tolmston, W. S., Ground waters as sources of public water supply: New England Waterworks Assoc. Jour., vol. 23, pp. 401-434, 1909. 3 Baker, W. N., Manual of American waterworks, p. 53, 1897. ■* Palmer, H. S., Ground water in the Southington-Granby area, Conn. : U. S. Geol. Survey Water-Supply Paper 466 (in press). GROUND WATEK FOR PUBLIC SUPPLY. 53 wiitor-resonrces laboiatorv of the United States Geological Survey. These are divicled ninoiio- the three areas as follows: Norwalk area^ 14 iinalyses and '2''\ assays; Sudield area, 7 analyses and 12 assays; (ilastonhury area. 4 analyses and 7 assays. The quantities are Imported in parts per million. (onstftiK nt.'i (Jetcrinhicd hij analysis. — In 22 of the 25 analyses the following constituents Avere chemically determined : Silica (SiO._>), iron (Fe), calcium (Ca), magnesium (Mg), carbonate radicle (CO,), bicarbonate radicle (HCO,), sulphate radicle (SO,), chloride radicle (CI), nitrate radicle (NO.,), and total dissolved solids at 180° C. In the three remaining analyses (Ridgefield Xos. 15 and Ki and Westport No, 39) sodium (Na) and potassium (K) were also determined. In the assays the following constituents were chemically deter- inincd: Iron (Fe). carbonate radicle (CO,), bicarbonate radicle (H(MX). sulphate i-adicle (SO,), chloride radicle (CI), and total hardness in the conventional terms of CaCOg. Consiituents computed. — In the partial analyses the following (juantities were computed: Sodium and potassium taken together (Na+K), total hardness as CaCOg, scale-forming ingredients, foam- ing ingredients, and the probabilitj^ of corrosion in steam boilers. In three of the analyses, as noted above, sodium and potassiimi were de- termined independently by chemical methods instead of by com- putation. The computation of sodium and potassium was made by calculat- ing the sum of the reacting values of the acid radicles (CO.. HCO3, SO4, CI. and NO3) and subtracting from it the sum of the reacting values of calcium and magnesium (Ca and Mg). The reacting value of a constituent is its capacitj^ to enter into chemical combina- tion and is equal to the amount of the constituent present multiplied by its valence and divided by its molecular Aveight. The excess of the acid radicles is considered to be equivalent to and in equilibrium with the sodium and potassium. They were computed on the hypothesis tliat only sodium Avas present, by dividing the difference between the i-eacting values of the acids and bases by the reacting value of an amount of sodium equivalent to one part per million. The result is reported as if it were sodium and potassium. Total hardness was computed in the conventional terms of cal- cium carbonate (CaCO.) by the following formula given by Dole:^ IIrr=2.5 Ca-f 4.1 Mg The computations of s, f, and c, which represent respectively the scale-forming ingredients, the foaming ingredients, and the prob- ' Mendenb.Tll. W. C, Dole. R. B., and Stablfr, Herman, Groiind water in San .Toaquin Vallfy, Calif.: U. S. Geol. Survey Water-Supply Paper 308, p. 45, 1916. 54 GROUND WATEE IN NOEWALK AND OTHEE AEEAS, CONN. ability of corrosion, were made by the following' formulas given by Dole.^ s=Sm+Cm+2,95 Ca+1.66 Ms; t=2.7 Na 0=0.0821 Mg-0.0333 CO,— 0.0164 HGOo The symbols Sm and Cm represent suspended matter and colloidal matter, respectively, and are expressed in parts per million. In the assaj^s the same quantities were computed except total hardness which was determined, and in addition the total solids were computed. In the assays the following formula given by Dole - was used to compute the values of the alkalies, sodium and potassium (Na+K). Na==0.83 CO3+O.4I HCO:+0.71 Cl+0.52 SO,-0.5 H Tile symbols represent the parts per million of alkali (sodium and potassium) and the carbonate, bicarbonate, chloride, sulphate, and total hardness found by the assay. The total solids were computed by the following approximate formula given by Dole : ^ T. S. =SiO,+1.73 CO3+O.86 HCO3+I.48 SO,+1.62 CI The s,ymbols represent the parts per million of silica and the car- bonate, bicarbonate, sulphate, and cliloride radicles. In applying this formula it is necessary to set some arbitrary value for the silica. Inasmuch as the average silica content of the analyses of ground waters in this report is 23 parts per million, 25 parts per million, a convenient round number on the safe side, was taken as the arbitrary value for silica. The estimate of solids is rough, and only two signifi- cant figures are reported. The factor for scale-forming ingredients, s, was computed ac- cording to an approximate formula given by Dole.* s=Cm+H The symbols represent the joarts per million of colloidal matter and of total hardness in terms of CaCOa. Inasmuch as the colloidal matter is essentially the same as the silica, the above equation lias been used in the equivalent form