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Cemetery Drainage

      
Date Published: 
October, 1926
Original Author: 
Bellett Lawson
Original Publication: 
AACS Proceedings of the 40th Annual Convention

One of the most essential things in Cemetery Construction is drainage. However, there are more mistakes made in this line than any other form of Cemetery construction.

In the selection of a site for a Cemetery the possibility of draining the land should be the first consideration. Of times however, the price of the land is the first consideration. I know of a site purchased where the price was the predominate factor and when it came to drainage it cost more for a sewer without the grounds than the whole tract of land was worth. Even after this sewer was constructed the fall was so limited that the Cemetery will always be a poorly drained place.

It may not be out of place to say what are the essential requirements for drainage when selecting a site?

First of all it is necessary to have some spot on the land, or near it, that is low enough with a natural outlet for the water into which the main drain or sewer can he emptied. Presuming this has been taken into consideration the next question is the kind of land to be drained.

The ideal land for Cemetery purposes is that which has well cultivated top soil with sandy loam subsoil, to a depth of at least six feet. However, so many cemetery sites are selected that have heavy subsoil and in that case the drainage question is one that entails much more care and expense.

Where possible the main drains or sewers should be six or more feet in depth. The size of these main drains will be determined by the area of the land to be drained. It is better to have these too large than too small. A good rule is to allow half an inch of main drain for each acre to be drained. On that basis a Cemetery containing 48 acres should have at least a two foot outlet as a minimum. These figures are given with the presumption that no food water or other than Cemetery drainage is going into this sewer. As stated before if in doubt enlarge on the main sewer.

If possible lay all the main sewers under the driveways or Avenues and as stated before keep them six or more feet in depth. As most Cemetery Avenues are laid out in curves there is often a tendency to follow these curved lines with the sewers. However, my experience has proven this to be bad practice. In level sections of land these sewers need cleaning at intervals and this becomes a difficult job where curved lines have to be followed. It is far better to lay out straight lines from point to point on these curves and at these intersecting points build a manhole. Some one may say this makes many manholes, but this is a good feature. Manholes should be every two hundred feet at least. In fact it is much better to have manholes at intersections of the avenues and let the catch basin connection empty into these manholes instead of putting Y's and T's into the sewer system.

No cemetery drain under an avenue should be less than ten inches in diameter and no catch basin connection should be less than six inches in diameter.

So far I have talked about outlets and size of pipe.

The next important step is the kind of sewer pipe. Vitrified sewer pipe is the kind most commonly used, although good concrete pipe make good material for use in a cemetery.

There is a great difference of opinion as to whether the bell end or butt end pipe is the best for cemetery use. If plenty of manholes are used, I prefer the butt end pipe. These pipes are placed tight together and over the joint a piece of good roofing felt is laid and carefully kept in place until the trench is filled. If the land is of heavy clay; this kind of sewer can be made still better by filling around the pipe and over the top to a depth of six inches with cinder, slag or any porous material before the rest of the trench is filled with earth.

In cemeteries that are composed of heavy clay it is essential that in addition to the drains mentioned small farm tile be connected to these sewers at intervals and run into the sections where the pathways will come between the lots. This tile should be deep enough so they will be at least six inches lower than the bottom of graves at any point in the section. However, as this method is expensive I would not advise this unless it is absolutely necessary.

No drainage system is good that does not provide not only deep drainage but plenty of inlets for catching the surface water and plenty of places to catch the sand, mud and other debris that gets into the sewers with the water. With this thought in mind let us first consider the manholes. As stated before, these should be plentiful. First because if they are close together it makes it easy to clean out the sewer if it becomes stopped by tree roots or from other causes and secondly if properly constructed these manholes make ample space into which the fine dirt and debris can settle instead of in the bed of the sewer.

The construction of manholes should be along the following lines. They should be at least three and one half feet in diameter and at least eighteen inches deeper than the bottom of the sewer. This depth serves a double purpose. First it allows the debris to settle as stated above and secondly it allows room for a man to work if it becomes necessary to rod out the sewer. The construction of these manholes can be of brick, concrete segments, concrete pipe or poured concrete. Local conditions will govern this.

As to catch basins and before we discuss this let me state that sometimes a manhole is a combined catch basin and manhole. However, catch basins are usually at the aide of the road and are used as inlets into which the surface water flows. These inlets can be of various forms but it is quite essential that like the manholes the first sand and dirt is caught in these basins. This is accomplished by building the catch basin a little lower than the pipe outlet that connects these catch basins with sewer or manholes. I could at this time go into detail as to the construction of these inlets but it is best to use what is obtainable in the various communities.

From the publication:
AACS - Proceedings of the 40th Annual Convention
Memphis, TN
October 11, 12 and 13, 1926

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Code: 
A1276