A Comparative Study of Imhoff Tanks 365 
Placing steel beams : 
1600 pounds at 4 cents 65 .00 
Water pipe placed: 
60 feet — 1| inch pipe — perforated and fitted 50.00 
Reinforcement for brackets and channels: 
400 pounds at 7 cents 28 .00 
Concrete in brackets: 
4 .85 cubic yards at $16 .00. 75.00 
Concrete in top beams. 20 .00 
Weir plates 10.00 
Placing influent pipe and connections. 15 .00 
Total estimated cost. $1950.00 
In the estimate of cost, certain variations in cost items, not 
hitherto mentioned, are to be found. 
The sludge pipe can be placed in the inside of the finished tank 
more cheaply than in the earth outside, hence the prices of $1.50 
and $2 respectively. 
Reinforcement in floors is given at 5 and 6 cents a pound, as 
previously noted. 
Concreting floors is given at $10 in both tanks. 
Reinforcement for walls is given at 5 and 6 cents as noted, 
and for reasons already given. 
Concrete for walls is given at $12 and $14. 
Triangle mesh in place is assumed at $2.50 and $3 and the 
lump sums are not those obtained by strict multiplication. 
Concrete in the partitions is given at $20 and in the outside 
brackets at $16. While these are only estimates, it would seem 
that they are close enough to the proper value. 
A cheaper type of baffle and top construction for the circular 
tank would materially increase the financial advantage of the 
circular tank. The resulting estimates from the above consid- 
erations do not allow much advantage to either side, and peculiar 
conditions might even throw this advantage entirely on the other 
side. 
However, it would seem that while the units cost has been 
figured as greater for the circular tank, the often stated advan- 
tage of that latter type over the former may be seen to be based 
on a small margin of difference. 
