Let us now inquire into the condition of the soil of the city. We find that the general direction of the water trend is from northeast to southwest; that the water level in the wells near the Atlas works is thirty-five feet above the river level at the city water works; and that the waterfall is from fifteen to eighteen feet per mile. The formation of the ground beneath the city is attributed by geologists to the glacial drift of pre-historic times. From seventy to ninety feet below the surface the earth is built up of alternate beds of sand gravel, and clay, and go to show that at some remote period running water with its leveling and transforming power, aided by the corroding force of the air, contributed largely to the geological formation which we find to-day.
After obtaining the distances through these various strata in the different parts of the city, an average is calculated in the following order:
Loam, three to four feet; sand and gravel, thirty to forty feet; blue compact clay (hard-pan), twelve to eighteen feet; sand and gravel, five to ten feet; soft clay, one to five feet; and blue gravel and boulders to Devonian limestone, thirty-five to fifty feet. The first stratum of clay is very hard and tough, and for that reason is called “hard-pan.” It has an inclination from the northeast to the southwest of about thirty feet to the mile. The further north and east of White river, the less distance it is to bed rock. Occasionally below the “hard-pan” is found a small drift of soft clay, but this is not usual and does not extend very far in area; often in moving ten feet it is missed. The first seam of water is usually reached at a depth of seventeen to twenty-five feet; the second seam at fifty to sixty-five feet; and the third seam at seventy to ninety feet.
These various strata of water are all what is called “hard water.” Prof. E. T. Cox states that “the first seam contains the largest amount of mineral water, principally calcium carbonate, magnesium carbonate, chlorides and ferrous sulphate. The amount of chlorine is so large, that its presence is due in a great measure to sewage contaminations. The second seam of water contains but little chlorides, but has about the same amount of calcic and magnesic carbonates as the first. It is a good potable water when properly protected from contaminations from the upper seam. The third seam of water is also a hard water, that is, its salts will decompose a portion of soap and form a curd; but it contains less carbonates and more sulphates of the alkaline earths, lime and magnesia.” Inasmuch as the object of this paper, is to show to what extent the soil and water of Indianapolis are affected by pollution and the influence such pollution has on health, it is proper to state as nearly as possible, the sources from which the contamination arises. By the assistance of the former civil engineer of the city, the following estimate was made:
Area of Indianapolis (not including ground unimproved) 5,000 acres.
Within the city limits there are:
| Surface dug wells | 15,000 |
| Driven wells | 5,000 |
| Open privy vaults | 22,000 |
| Privy vaults filled up | 13,000 |
| Cess-pools | 10,000 |
| Cess-pools filled up | 5,000 |
The builders of the city state, that in the business portion of the city, it is not uncommon to discover from three to a half dozen old privy vaults, in making a single excavation for an ordinary building.
According to the above estimate which is considered very low, 50,000 privy vaults and cess-pools are constantly filling the soil with deadly poisons, and polluting the water of at least 15,000 surface dug wells, which furnish drinking water to 50,000 people.
Not more than 6,000 persons drink water from the city water works, and about 20,000 persons use water from driven wells and cisterns. It is a rule well established by eastern boards of health, that a dug well drains a circular area with a radius equal to twice the distance of the depth of the well. It has been ascertained, that a very large number of the wells of the city are situated within an average distance of less than thirty feet of cess-pools and privy vaults, while a great many are distant from them not over ten feet. Most wells are dug simply with the view of obtaining water and of having it as convenient to hand as possible; the cess-pools are dug similarly, with a view to convenience except that the demand here is that the liquid contents shall readily drain away. Provided the well furnishes an abundance of water, and the cess-pool allows the liquid refuse to soak away, and on this account, seldom requires cleaning out, there is little concern as to what goes on unobserved beneath the surface of the ground. In the course of time the well water is discovered to be impure, after sickness, and perhaps death, have followed its use.