Draining Sinks and Ponds 



461 



Where the water collecting in such places is 

 largely from surface drainage, it is frequently possible 

 to reclaim them by intercepting the water and divert- 

 ing it around the sink in the manner suggested in 

 Fig. 148, where A B 

 represents a surface 

 ditch taking the water 

 from the higher land 

 above. 



It is frequently true 

 that such low places 

 without natural outlets 

 are underlaid with well 

 drained beds of coarse 

 sand and gravel, and 

 in such cases, if the 

 volume of water is not 

 very large and if the 

 bed of sand and gravel 

 beneath it is thick and only 10 to 15 feet from the 

 surface, a well sunk into the sand and gravel and 

 stoned or bricked up may serve as an outlet for under 

 or surface drains. 



Instead of curbing the well, it may be simply filled 

 with loose stones to within 3 feet of the surface, 

 covering these with smaller ones and finally with 

 gravel and then sand, leaving the surface unobstructed. 



Unless the approach to this drain is so gradual 

 that there is no danger of fine silt being deposited over 

 it, it would be better to have this in a shallow sink 

 surrounded by a slightly higher border, grassed over 



Method of intercepting surface drain- 

 age. A, B, surface ditch. 



