12 



BULLETIN 57, U. S. DEPARTMENT OF AGKICLTLTURE. 



clii-ections from the center. The outer edge should be raised to form 

 a trough emptying into a tight drain, or a drain trough should be 

 provided to catch the drip. E. Bartow^ suggests that the earth l)e 

 excavated for 4 feet outside of the regular casing to a depth of 4 feet 

 and that an extra 4-inch coating of waterproof Portland cement mortar 

 be ])laced outside this casing ^vitl^ 4 to 6 inches of mortar in the bot- 

 tom of the excavation. This bottom should have a raised portion at its 

 outer edge to divert the seepage water to a tile drain. This arrangement 

 ])revents surface water that has not been filtered through at least 4 feet 



of earth from gaining 

 ^- access to the well. 

 Figure 10 shows a 

 combination of these 

 protective arrange- 

 ments. . 



L^-/; 



S^^^ 



I 



9°'^ 

 § 



■^cojvc/p^ze- /fss£-/ryo//f 



Springs are good 

 sources of water sup- 

 ply, since they usu- 



FiG. 10.— AVell protection. -^ ^ ' 



all}^ come from great 

 depths within rock or are filtered through many layers of sand and 

 gi'avel. However, they are subject to pollution . from the same 

 sources as wells and should be closely watched in this respect. 

 Farm spring supplies are often polluted by the drainage from build- 

 ings and stock pens. Spring water supplies from limestone are also 

 subject to pollution from distant garbage and sewage dumps in sink 

 holes, as shown in fig- 

 ure 6 . The s ame pr e- 

 cautions should be 

 taken for safeguard- 

 ing spring suppHes as 

 in the case of wells, 

 and in addition the 

 spring should always 



1 (■ 1 i 1 i. Fig. 11.— Method of wallini; in springs. 



be fenced to keep out 



stock. It should be cleaned of all trash and walled in to form a kind 

 of reservoir, as shown in figure 1 1 . The Supply may then be conducted 

 to the house by gravity or by means of a hydrauUc ram. Where a spring 

 is small a large vitrified tile may be so placed as to form a small storage 

 reservoir. The reservoir should be covered and protected as much 

 as possible from filth and vermin. After rains the spring should be 

 noticed for any signs of turbidity which may indicate pollution from 



I Univ. 111. Bui., 7 (1909), No. 2. 



