Geology topics
Robert Vittum Cushman
Publications and source records attributed to Robert Vittum Cushman.
Water resources of the Hartford-New Britain area, Connecticut
The Hartford-New Britain area includes the metropolitan areas of Hartford and New Britain and parts of several adjoining towns. Water used in the area is withdrawn from the principal streams and aquifers at an average rate of 463.5 mgd (million gallons per day). Sufficient water is available from these sources to meet present requirements and those for many years to come, although local shortages may develop in some areas as the result of problems of distribution and treatment. About 98 percent of all water used in 1957 was from surface sources. More than 425 mgd was required by industry, and about 23 mgd was for domestic water supply. The Farmington River upstream from Collinsville is the chief source of water for public supply in the Hartford-New Britain area, whereas the Connecticut River is the chief source of water for industry. An average of about 40 mgd is withdrawn from the upper Farmington River for public supply, and about 404 mgd is withdrawn by industry from the Connecticut River for nonconsumptive use and returned directly to the stream. The Connecticut River is the source of the largest quantity of water in the area. The flow of the stream at Thompsonville may be expected to equal or exceed about 2,000 mgd 95 percent of the time, and the flow should not be less than this amount for periods longer than 12 days. The flow below Thompsonville is increased by additions from the Scantic, Farmington, Park, and Hockanum Rivers and from numerous smaller tributary streams. The available streamflow data for the aforementioned rivers have been summarized graphically in the report. The chemical quality of water in the Connecticut River is good, except for short periods when the iron concentration is high. In addition to the removal of iron some other treatment may be necessary if water from the Connecticut River is used for special purposes. The chemical quality of the tributary streams is good, except the quality of the Park River, which is poor. Thus the Connecticut River in the vicinity of Hartford offers an almost unlimited source of water of good chemical quality to the Hartford, New Britain area. The Connecticut River and many of its tributaries, however, are polluted to some degree, and the cost of treatment for pollution and of delivery of water to the area presents an economic problem in the further development of these sources. The Hartford-New Britain area in the vicinity of Hartford has been plagued by floods since the time of its settlement. Most of the damage to property and loss of life in the Hartford area has been caused by flooding of the Connecticut and Park Rivers. Floods have occurred on the Connecticut River and its tributaries in every month of the year, but the most severe floods occur in the spring and fall. The most devastating flood on the Connecticut River occurred on March 21, 1986, when the stage at Hartford reached 37.0 feet above mean sea level. The maximum flood on the Park River occurred on August 19, 1955, when the stage reached 43.5 feet above mean sea level. Floods on the other tributaries have been frequent and some have been large, but damage has not been as great because the streams flow mostly through rural areas. Small to moderate supplies of water suitable for domestic use and for small municipalities and industries are available from wells in the Hartford-New Britain area. Moderate supplies are obtainable from five definable sand-and-gravel aquifers and from widespread consolidated sedimentary rocks. Yields to individual wells range from 15 to 400 gpm (gallons per minute) for wells penetrating sand and gravel and from 1 to 578 gpm for wells penetrating consolidated sedimentary rocks. Sand and gravel deposits bordering the Connecticut River downstream from Rocky Hill afford the greatest potential for the development of large supplies of ground water. Small supplies ranging from 1 to 40 gpm are obtainable from glacial till and from consolidated crystalline rocks.
Ground-water resources of north-central Connecticut
The term 'north-central Connecticut' in this report refers to an area of about 640 square miles within the central lowland of the Connecticut River basin north of Middletown. The area is mostly a broad valley floor underlain by unconsolidated deposits of Pleistocene and Recent age which mantle an erosional surface formed on consolidated rocks of pre-Triassic and Triassic age. The mean annual precipitation at Hartford, near the center of the area, is 42.83 inches and is uniformly distributed throughout the year. The average annual streamflow from the area is about 22 inches or about half the precipitation. The consolidated water-bearing formations are crystalline rocks of pre-Triassic age and sedimentary and igneous rocks of the Newark group of Triassic age. The crystalline rocks include the Middletown gneiss, the Maromas granite gneiss, the Glastonbury granite-gneiss of Rice and Gregory (1906), and the Bolton schist which form the basement complex and the Eastern Upland of north-central Connecticut. Enough water for domestic, stock, and small commercial use generally can be obtained from the crystalline rocks. Recoverable ground water occurs in the interconnected joints and fracture zones and is yielded in amounts ranging from 29 to 35 gpm (gallons per minute) to wells ranging in depth from 29 to 550 feet. The sedimentary rocks of Triassic age underlie all the Connecticut River Lowland and are predominantly arkosic sandstone and shale. Water supplies sufficient for domestic, stock, and small commercial use can be obtained from shallow wells penetrating these rocks, and larger supplies sufficient for industries and smaller municipalities can probably be obtained from deeper wells. Reported yields range from ? to 578 gpm; the larger yields are generally obtained from wells between 300 and 600 feet in depth. Yields are larger where the overlying material is sand and gravel or where the rocks are well fractured. The igneous rocks of Triassic age are basalt and have water-bearing characteristics similar to the crystalline rocks. The unconsolidated deposits comprise ground-moraine and drumlin deposits, ice-contact deposits, outwash-plain and valley-train deposits, and glaciolacustrine and associated delta deposits of Pleistocene age, as well as dune deposits, good-plain deposits, and swamp deposits of Recent age. Ground-moraine deposits occur throughout the area but yield only small quantities of water. The ice-contact deposits consisting mostly of sand and gravel form kames, kame terraces, and crevasse fillings and are the surface deposits in three extensive areas along the eastern margin of the Connecticut River Lowland. The deposits in most places are saturated and, where they consist of well-sorted material, are highly permeable, yielding as much as 750 gpm to properly constructed wells. Outwash-plain and valley-train deposits and bodies of undifferentiated outwash underlie the surface in the eastern and southern parts of the area. These deposits consist of well-sorted sand and silt and some pebble gravel ranging in thickness from nearly zero to more than 225 feet in places. The thicker deposits are an important source of moderate supplies of ground water. Screened wells of moderate depth commonly yield about 150 gpm, but some yield as much as 400 gpm. Bodies of buried outwash deposits of irregular size and shape occur in the bottoms of some of the filled bedrock valleys. They seldom are more than 20-30 feet thick. Their permeability Is generally low because of the high percentage of silt; yields as much as 30 gpm to domestic wells are reported. Under most favorable conditions, these deposits yield as much as 500 gpm. The glaciolacustrine and associated delta deposits occur in nearly all parts of north-central Connecticut and are potential sources of moderate supplies of ground water. They consist of well-sorted sand which generally grades downward into varved clay and silt. The deposits of sand are thic