STORAGE AND DISTRIBUTION. 1 15 







cause the clay bank would not remain quiescent 

 during settlement. It should be formed of one part of 

 Portland cement, two parts of sand, and four parts 

 of broken brick or stone, and should be reinforced 

 through the centre of its thickness with expanded 



Outlet, Pipe 



I I r LD 



FIG. 83. 



metal, while the concrete could be made waterproof 

 by adding a 5 per cent solution of alum to the mix- 

 ture, which is an advisable procedure in all cases of 

 concrete retaining water. A suitable valve for the 

 outlet culvert of this and the previous bank is shown 

 in fig. 83, while it may be men- 

 tioned that it is a very wise pre- 

 caution to use on the pipes, where 

 they pass through the core, circular 

 shields of cast iron, made in seg- 

 ments and bolted together, which 

 will resist the tendency of any 

 water to creep along the pipes, and 

 so start a leak which will often 

 resist all efforts to stop it. The ] IG - 8 4- 



plates, which are called puddle plates, are shown in 

 fig. 84. 



On all reservoirs there must be some provision for 



