Show sandy or gravelly clay best for farm reservoir A satisfactory material for farm reservoirs is a sandy or gravelly clay that can be packed almost watertight says tl 1 I bureau of agricultural engineering united states department of agriculture if the bed of the reservoir Is naturally of such materials and if the water Is not to be used tor for domestic purposes the bottom can be packed by bedding or feeding sheep on the site when the earth Is wet if the soil Is not clayey it Is sometimes practical to spread a three or four inch layer of clay over the bottom and sides of the reservoir and mix it with the surface soll soil by disking or harrowing the bed should then be packed by rolling or by the tramping of stock when the water of a small reservoir is for domestic purposes ordinary concrete makes a satisfactory lining if the lining Is not reinforced it should be from two to four inches thick and should be placed in blocks or squares of 15 to 20 feet with expansion joints to prevent formation of cracks into the joints should be cast a corrugated strip of copper or lead to give a watertight job to reinforce linings a layer of woven wire Is sometimes used to prevent the heaving of concrete linings in freezing wen weather th er when reservoirs are empty where soils are other than porous sand or gravel the linings should either be watertight or laid on thick layers of coarse gravel which will provide draining or drain tile may be laid outside the reservoirs to carry away the water |