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

Enfield is a nianiifactiiring and farming town in the northeast corner of Hartford County. It is bounded on the north by Massa- chusetts, on the east by Somers, in Tolland County, and on the west by Connecticut River. The town covers about 34 sc^Liare miles, of w^hich IS square miles, or about 40 per cent, is wooded. A strip IJ miles wide along the Connecticut is in the main cleared, but wood- lands are uniformly distributed throughout the i"est of the town. Thompsonville, on Connecticut River, 1^ miles south of the Massa- chusetts boundaiy, is the principal settlement. The village of Enfield is strung out for 1^ miles along Enfield Street, which follows the crest of the iddge south from Thompsonville. Hazardville and Sci- tico are small settlements in tlie eastern part of the town. There are post offices and stores at all the places. The town has about 75 miles of road, exclusive of the streets of Thompsonville and including 7| miles of the State trunk-line road from Hartford to Springfield. The Hartford division of the New York, New Haven & Hartford Rail- road follows the west boundary and has stations at Thompsonville and Enfield Bridge. The Spring-field division of the same company runs north and south through the eastern part of the town and has stations at Scitico and Shaker Station. The East Side line of the Hartford & Springfield Street Railway Co. runs through Enfield and Thompsonville, and the Somers branch leaves the main line a 132 GROUND WATER IN NOR WALK AND OTHER AREAS, CONN. little south of Thompsonville and runs through Hazardville and Scitico to Somerville and Somers. Enfield was named and granted by Massachusetts in 1683 and annexed to Connecticut in 1749. Since then there has been no change in its extent or organization. In 1910 the population was 9,719, an increase of 3,020 over the population of 1900. The density is 284 in- habitants to the square mile, but most of the population is concen- trated in Thompsonville, and most of the area is much more sparsely populated, since 1756; The following table shows the changes in population Population of Enfield, 1156 to 1910.°' 1756. 1774. 17S2. 1790. 1800. ISIO. 1820. 1830. Popula- tion. 1,050 1,360 1,562 1,800 1,761 1,846 2,065 2,129 Per cent change. +30 + 15 + 15 - 2 + 5 + 12 + 3 1840. 1850. 1860. 1S70. 1880. 1890. 1900. 1910. Popula- tion. 2,648 4,460 4,997 6,322 6,755 7,199 6,899 9,719 Per cent +24 + 68 + 12 +27 + 7 + 7 - 7 + 43 a Connecticut Register and Manual, 1919, p. 638. There has been in general an increase in each census period. The manufacture of carpets was begun at Thompsonville about 1830 and the manufacture of gunpowder at Hazardville a few years later. The growth in population has been dependent in large part upon the prosperity of these industries. The decrease of population from 1890 to 1900 was probably due to the abandonment of the powder factory at Hazardville. Thompsonville may continue to grow stead- ilj", but no great increase is to be expected in the rest of the town. The principal industries of Enfield are the manufacture of carpets and undertakers' supplies and agriculture, which is confined chiefly to the raising of wrapper and binder tobacco. SURFACE FEATURES AND GEOLOGIC STRUCTURE. Most of Enfield lies on a sand plain, 120 feet above sea level at the south boundary and 200 feet at the north. Along the east bound- ary till-covered slopes rise to a maximum elevation of 400 feet above sea level. The plain is bounded on the west in part by a ridge 140 to 180 feet high, the west slope of which extends inland to the river and in others flattens to a terrace 60 to 80 feet above sea level. The river is about 25 feet above sea level at the southeast corner of the town. The total range in elevation is about 375 feet. The bedrock of Enfield comprises the red sandstones, shales, and conglomerate of the upper part of the Triassic. They were origi- nally deposited as sands, clays, and gravels, but became cemented and consolidated. Subsequently they were broken into great blocks and tilted 15° or 20° E. Their history since has been solely one ENFIELD. 133 of erosion. Prior to the g] acini eijoch the Connecticut had a channel east of the Enfield Street ridge, as is indicated by the well of Mr. Eichard Smyth (No. 31, PL IV). This well is 418 feet deep, but reached bedrock only at a depth of 236 feet. As the mouth of the \vell is about 120 feet above sea level, the bedrock at this point is over 100 feet below sea level. The most probable explanation of these facts is that formerly the land stood about 150 feet higher tlian now, and that Connecticut River cut a channel which passed this point. During the later part of the glacial epoch, as the ice slieet was receding from this region, many streams of melt water issued from its front carrying much debris, which Avas deposited in the main in the broad central valle}?^ of Connecticut Eiver, forming bread outw^ash plains. These deposits filled and blocked the old channel and diverted the river into its present course. The youth of this new channel from Thompsonville to Windsor Locks is show^n b}- two facts — that the stream is not 3'et worn to grade and still has many small rapids and riffles, and that the banks are in large part low, fresh cliffs of sandstone. Moreover, there are no flood plains in this narrow portion of the valley as there are in tlie broader por- tions to the north and south. The outwash plain is in general well preserved, but Scantic River has cut in it a valley 80 to 100 feet deep and a quarter to three- quarters of a mile wide. The floor of this valley is flat and in part sw^ampy. The till-covered slopes along the east boundary ow^e their eleva- tion to the resistance of the underlying sandstone. The boundary be- tween the till of the slopes and the stratified drift of the plain is about 200 feet above sea level. The southeastern part of Enfield is drained by Scantic River and its tributaries. The Scantic enters the town from the east near Scitico and flows west to Hazardville, and then turns south into East Windsor. The southwestern part of Enfield is drained by short brooks that empty into Connecticut River. Grape Brook and Freshv\'ater Brook drain the northern half of the town. In com- parison with towns in which till is the dominant surface material, there are few brooks in Enfield, because the water that falls as rain soaks readily into the porous soil, becom.es part of the ground-water body, and reaches the main streams by percolation through the ground rather than by -flowing in surface streams. WATER-BEARIXG rOR3IATIOXS. Red sandstone. — Red sandstone and associated red shales and con- glomerates form the bedrock of Enfield. They crop out in a number of places along Connecticut River and on the ridge just east of the river, and there are a few outcrops on the till-covered slopes along 134 GROUIS^D WATER IN NORWALK AND OTHER AREAS, CONN. tlie east boundary of the town. These rocks are cut by numerous jomts and fissures formed by the jarring and crushing incident to their tilting. There are probablj^ zones in the sandstone that are somewhat jjorous, but they do not constitute an important source of ground water. The joints and fractures form a maze of intercon- necting channels inta which water works its way from the saturated basal portions of the overlying mantle rock. This water may be recovered by means of drilled wells. A drill hole at any point will probably cut one or more fissures and procure a satisfactory supply of water. Data were obtained concerning 13 such wells in Enfield and are summarized in the following table. SiinDiiory of drUled tvells in Enfield. Maximum Minimum. Average... Total depth. Feet. ■187 • 38 179 Deptb to rock. Feet. 236 25 55 Depth to water. Feet. Yield per minute. Gallons. 170 22 52 The drilled well of Dr. Vail (Ko. 14, PL IV) has a depth of 487 feet, of which 450 feet is in rock. The well yields 50 gallons a minute, but the water stands 90 feet below the surface. This is presumably because the well is situated near the crest of a ridge from which the water drains with considerable facility. Till. — The slopes in the eastern part of Enfield are covered with a mantle of till, which is, in general, 20 to 30 feet thick. It is a dense mixture of glacial debris and consists of a well-compacted matrix of fine rock flour, clay, silt, and sand, in which larger fragments are embedded. It is able to absorb and transmit moderate amounts of water that falls on it as rain arid yields fairly abundant and dependable supplies of water to wells dug in it. Three such wells were visited in Enfield and all are said never to fail. Sti'atified drift. — The bedrock of Enfield, except the hills in the eastern part, is covered by stratified drift. The evidence of the drilled wells in the town is that the thickness of the stratified drift ranges from 25 to 236 feet, the average being 55 feet. Inasmuch as one of these wells was sunk through an unusually great thickness of stratified drift, this average may be too great. Probably a bet- ter estimate would be 35 or 40 feet. In Thompsonville and on the Enfield Street ridge there is only a thin mantle. In excavations at various points there was only 3 or 4 feet of stratified drift, and below it there was either till or red sandstone. (See PL XI, B.) The stratified drift is of aqueous origin and comprises the well- washed, reworked constituents of the till, together with minor amounts of debris formed by the erosion of firm rocks. For the EI^FIELD. 135