SEA WATER FROM GROUND SOURCES 



By John R. Clark and Ronald Eisler 



Sandy Hook Marine Laboratory, Bureau of Sport Fisheries and Wildlife, Fish and Wildlife 

 Service, U.S. Department of the inferior, Highlands, N.J. 



Abstract. — Efforts to obtain sea water from a ground-water source at the Sandy 

 Hook Marine Laboratory are described. The basic theory of occurrence of fresh and 

 salt water in coastal sand and gravel deposits is discussed and is contirmed by the re- 

 sults of a test well drilled at Sandy Hook. A hypothesis is advanced to explain both 

 an unexpected reversal of salinity gradient and contamination by ferrous hydroxide. 

 Although plans to maintain a continuous flow were frustrated, the water, after settling 

 (to remove iron precipitate) has been used successfully in rearing 51 species of fishes 

 and some invertebrates. 



Many problems typically encountered in 

 supplying large volumes of sea water to 

 seaside laboratories can be solved by using 

 a shallow ground-water source. The use 

 of ground-water supplies involves a unique 

 complex of problems, however, which must 

 be antici]3ated before deciding in favor 

 of a well system. 



A major advantage of a ground-water 

 supply is the elimination of barnacles, 

 mussels, and other attaching organisms. 

 These animals, which foul supply pipes 

 and fittings, have no access to ground 

 water. Also, sea water from a well is 

 free from particulate contaminating ma- 

 terial such as sand, silt, and detritus. 

 Thus, filtration may be eliminated, and 

 the design and construction as well as 

 maintenance of the supply system may 

 be simplified. 



Another advantage of a ground-water 

 supply is that physical characteristics of 

 ground water remain relatively stable. 

 Kapid fluctuations in salinity induced by 

 tidal forces, which are so typical of estu- 

 arine or shallow bay waters, do not affect 

 ground-water sources. The temperature 

 of ground water is a function of average 

 prevailing air temperature and, to a depth 



of 50 feet, is nearly constant for any loca- 

 tion, varying a maximum of 1 degree 

 annually. Therefore, ground-water tem- 

 perature can be reliably predicted from 

 air-temperature data (Collins, 1925). 



A further advantage in using a ground- 

 water source is that no special intake or 

 pump support structures are required as 

 for a direct sea-water source. These 

 structures are often expensive and in many 

 places are subject to damage by storms 

 or, in northern locations, to damage by ice 

 in winter. A well often may be located 

 much nearer the laboratory than the inlet 

 of a direct intake line, thus reducing cost 

 and complications involved with lengthy 

 transport lines. 



We wish to exf)ress our appreciation to 

 the U.S. Geological Survey (Trenton Dis- 

 trict Office) for their most helpful counsel 

 and for arranging the analysis of our well 

 water. 



DESIGNING THE SYSTEM 



This paper deals with problems encoun- 

 tered in obtaining sea water from subsur- 

 face sands and gravels at Sandy Hook, 

 N.J. The decision to use a ground- water 

 source for our sea-water supply was de- 



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