M^CLURE'SPALDING—SEWERAGE AT THE WORLD^S FAIR.        93

THE SEWERAGE OF THE WORLD'S COLUMBIAN EXPO¬
SITION.*
 

By C. B. McClure, '91, and F. M. Spaldino, '93, School of Civil Enoineerhsto.
 

The World's Columbian Exposition has complete systems of
water-works and sewerage sufficient in capacity for a city of 400 000
inhabitants. Owing to the flatness of the site and to the cost of
construction of a combined system of sewers, the sewerage is divided
into three distinct systems: 1. Roof drains. 2. Storm water sewers.
3. Sanitary or ejector sewers. The different systems will be de¬
scribed in order.

ROOF   DRAINS.

The roof drains, carrying the water from the roofs, have their
outlet in the nearest water-way. In designing the size and grade of
these sewers, the maximum rate of rainfall was taken at one inch
per hour, all of which was considered to reach the sewer. The
amount of water-way provided is probably not sufficient for heavy
storms, and the sewers at such times will necessarily flow under a
head, because the assumed rate of rainrall is often doubled and some¬
times trebled in short, sharp storms In a permanent system this
might profe a serious difficulty, but for the few heavy storms likely
to bccur during tht continuance of the Fair, there will probable be
no trouble.

On the Mines and Mining Building there are 62 6-inch down
spouts. The roof area of this building is 225 000 sq] ft., making a
down spout for every 3 630 sq. ft. The Manufactures and Liberal
Arts Building has 224 6-inch down spouts, or one down spout for
every 5 930 sq. ft. of roof area. Down spouts are made of galvanized
iron. Connection is made with the sewer by a 6-inch vitrified pipe
leading directly from the bottom of down spout to the sewer. The
total number of manholes in the roof drain system is 49.

The following table gives the total amount of vitrified sewer
pipe used in the construction of roof drains:

Table SnowiKa Lei^gth aistd Size of Pipe.
 

diameter of pipe

IN INCHES.
 

LENGTH IN
FEET.
 

DIAMETER OF PIPE
IN INCHES.
 

LENGTH IN
FEET.
 

6

8

9

10
 

30,091
7,259
3,161
4,159
 

12

15       •

■       18
 

5,684
5,052
2,181
 

*The writers desirelto express their obligation to F. H. Eno, '91, Asst. Engi¬
neer in the Water Supply and Sewerage Department of the World's Columbian
Exposition, for valuable data used in the preparation of this article.