This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol2", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
When the main line of drains has been laid the trenches can be continued in a similar manner to the gulleys or soil pipes. Right-angled junctions should never be permitted, but special pipes with easy bends should be used (see Fig. 185). Connections should be made at the sides and not top of the pipes.
Fig. 186 shows a method of carrying stoneware drains on marshy or silty ground. 12 by 6-inch piles are driven about 6 feet apart and two 12 by 4-inch runners secured to each side of these piles with coach screws. The bottom of the trench is then made firm by clay puddling, the concrete foundations put in, and the pipes laid in the usual way.
When it is found necessary to carry a line of mains through a house, cast-iron pipes should be used and completely covered with concrete. These are made in 9-feet lengths, and weigh as follows:-
Rust joints are sometimes used for iron pipes, but caulked joints are preferable, as the expansion of the rust cement when setting has a tendency to burst and crack the sockets of the pipes. The usual way is to make the joints with lead wire or molten lead and caulk them afterwards. Turned and bored pipes have been used, and it has been found that they readily adjust themselves to slight settlements.
All junctions and bends should be arranged with cast-iron access pipes fitted with air-tight covers secured with brass screws.
Fig. 187 shows an Intercepting Chamber. These should be built in cement, on a concrete bed at least 9 inches thick, and finished on top with a double or single seal cast-iron manhole cover. The concrete foundation having been put in, the disconnecting trap is placed in position and set perfectly level. There are many varieties of intercepting traps in the market, but a satisfactory one should have a 3-inch weir action and 1 1/2-inch water seal and sweeping arm.
The channel pipes (either 1/2 or 3/4 section) and the various branches discharging over them are next fixed and benched round with concrete. A course of brick on edge should be placed on top of the straight half-channel, and the concrete sloped off to the edge of the channel thus formed. This will form a deep channel, which will prevent the excreta from being washed up on to the slopes out of the reach of the next discharge. The sides and slopes of the chamber should then be finished to a smooth surface in cement mortar, 1 to 1.
Should the sewer be at a great depth, ramps may be used to save the expense of laying deep drains. These have a short arm with stopper fixed in same carried through the wall of manhole for rodding the drains.
Another form of ramp is that shown by dotted lines, the main pipe being continued full bore direct into the chamber, and a galvanised cast-iron flap valve fixed at the chamber end, to enable the sewage to flow into the chamber should the ramp become blocked.
The minimum internal dimensions of chambers should be 3 feet 0 inches by 2 feet 3 inches. In deep drains, however, they may be as large as 4 feet 1 1/2 inch by 2 feet 7 1/2 inches, and be gathered over at a height of 5 feet 6 inches above invert of drain, and continued to ground level with a shaft 1 foot 10 1/2 inches by 1 foot 10 1/2 inches inside dimensions.
Chambers over 4 feet deep should have step irons 1 foot 6 inches apart.
Where the distance between two inspection chambers exceeds 100 feet, sweeping eyes may be constructed, as shown by Fig. 188. These should be finished with a stopper bedded in soft soap and covered by a slab of York stone and a small hinged cast-iron cover. Inspection chambers are similar in construction to intercepting chambers, but the fresh-air inlet and intercepter are omitted.
There are several ways of dealing with these.
1. They may be connected to a Sykes' slipper, as shown on Fig. 189.
2. They may be discharged on to an open channel in accordance with the Model Bye-Laws.
3. They may be connected to a grease trap, as Fig. 190.
4. They may be connected to a flushing rim gulley, such as Fig. 191.
The advantages and disadvantages of the foregoing may be summed up as follows:-
1. Sykes' slipper is a deep glazed earthenware channel, covered by a movable cast-iron grating, and connected to a trap which can be set at any angle. It is without doubt an advantage to collect the wastes and connect them to one gully. But the grease thus collected should be cleaned off at least once a week.
2. This is a modification of the above, the channel having no grating, and possessing the advantage that the grease can be easily seen; it is, therefore, more likely to be kept clean.