In connection with the excavation of collar we should take up the matter of a cesspool, provided there is no sewer connection available. Here we will have a choice of methods. In a great many cases where all danger of contamination of wells is obviated by a city or town water service, the cheaper method of a leaching cesspool may be adopted.

Leaching Cesspool

This consists of a circular excavation eight or ten feet in diameter and deep enough to reach to good leaching or absorbent earth, lined with a dry wall of stones laid with open joints, and arched over on top with stone or brick forming a dome made water-tight, in the center of which should be set a stone, or an iron manhole. (Fig. 10.) This may be finished at the level of the ground or kept low enough so that it can be sodded over. In good coarse sand or gravel a cesspool of this kind will dispose of the sewage of a house for a great many years, but eventually the pores of the earth will become filled with the deposits and leaching will no longer take place. An effective remedy in this case may be adopted by making an outlet to which a series of pipes laid with open joints may be connected, to distribute the waste throughout a system of branches laid about twelve inches below the surface where it will be absorbed and purified by the soil and growth.

Fig. 9. Footing Stone.

Fig. 9. Footing Stone.

Fig. 10. Leaching Cesspool.

Fig. 10. Leaching Cesspool.

Tight Cesspool

The other form of cesspool is what is known as a tight cesspool and is constructed of hard brick and usually made about six feet in diameter and six feet deep from inlet, with walls and dome eight inches thick and a four-inch bottom, the whole cemented inside and out and made perfectly tight. (Fig. 11.) This cesspool will retain the whole of the deposits and must be either frequently emptied, or an outlet made of open-jointed pipe as described in connection with the leaching cesspool. This outlet should be below the level of the inlet and should have a bend turned down below the surface so as to remain in the clear water which will be found under the scum which lies on the surface. We find by the specifications that our architect has adopted a clever combination of these methods by building two cesspools, the first of which is a small tight cesspool which will retain all the solid and putrefying matter, and connecting this by an overflow pipe with a leaching cesspool built as described. The effect of this is that the tight cesspool will receive all of the solid matter which may be in the sewage, where it can be cleaned out at stated periods; and the overflow being of a wholly liquid nature will pass into the leaching cesspool in a comparatively clear state and will be absorbed entirely by the surrounding earth with no perceptible contamination.

In locating the cesspools we must see that they are placed low enough to allow the drain from house to have a good pitch. This drain will be of vitrified earthen pipe and should be laid at least three feet six inches below the surface, with an even pitch and with the bottom of the trench hollowed out where the hubs of pipes will come so that the pipes will lie flat in the trench. Great care must be taken in jointing the pipes to be sure that the cement is scraped off the inside of the pipes, where a projection would catch a portion of any solid matter which might pass through the pipes and they would soon become filled.

Fig. 11. Tight Cesspool.

Fig. 11. Tight Cesspool.