THE COLLECTION OF A WATER SUPPLY TO GALLERIES AT RICHMOND, IND
By Howard A,.Dill, Superintendent Water Company, Richmond, Ind.
Where a city or town cannot secure its water supply in sufficient quantity or purity front streams or lakes, an underground source must be investigated. A careful study of the underlying strata is important, in order to determine the depth at which the water-bearing vein lies, as well as its extent. The United States Geological Survey has done considerable work that is valuanle in such investigations, and many waterworks companies would be the wiser and richer, if such sources of information had been utilised. No subject of this character should be undertaken without the most thorough examination of all available data, and with the advice of a competent engineering expert. The location of a pumping station or a reservoir is largely determined by the source from which the supply is drawn, and, if a mistake is made in the latter, future expense in operation may be greatly increased by required changes in the system. Smaller towns or cities, particularly, are inclined to use their own judgment in many instances, when, by an expenditure of a few hundred dollars, such outlay would be returned to them from a judicious planning of their water systems. When a sufficient volume of underground water has been located, it remains to find the best means of conveying it to the pumping-station. If the supply is artesian, the problem is usually a simple one. If deep wells are used, the means employed depends upon the height of the water-level, in the wells. If this level stands near the surface, a pipeline may be laid, connecting the different wells at a point below the water-level when the wells are being used. In some cases, the suction-pipe of the pumps may be directly connected to the wells. If the water-level is at considerable depth, an air-lift plant or centrifugal pumps must be considered. If the geological Conditions do not permit deep driven wells, then a study must be made of the best means of collecting the available rainfall over a certain territory. If a deep layer of gravel underlies this section, a system of infiltration-galleries may be used to advantage. The rainfall passing through this gravel bed would be naturally filtered, giving a very satisfactory supply. Infiltration-galleries are used to collect water as it filters from an adjoining stream, or to catch the rainfall, over a certain section often it has passed through the gravel stratum. In both cases, the amount of water secured depends upon the porosity ot tlie sand or gravel between the gallery and the main body of water, the distance through which the water must percolate, the area of the gallery, and the head or pressure under which the infiltration is maintained. If it is desired to utilise the water from a stream, it is necessary to determine how near the gallery shall be placed, and whether or not the water will filter through the intervening sand and gravel. Some streams carry a large percentage of silt, which may prevent percolation to a large degree, and many failures in the use of galleries have resulted from this condition. In some instances, the water has been diverted from a stream, so that it will flow over a section of ground in which a gallery has been located. At first success may result: but eventually the silt from the stream will fill the interstices in the gravel, and the same conditions exist as in an artificial sand-filter. Probably the majority of the infiltration-galleries in operation derive their waters from the land side, and. with proper protection of the watershed, a uniformly good simply is obtained. In planning a system of this kind, it must be remembered that the supply is dependent on the rainfall, and fluctuates accordingly—making it necessary to design the gal lery so that it shall deliver the maximum flow at times of minimum rainfall. Infiltrationgalleries are generally built with 2 or 3-arched rings of brick, laid in cement, resting on stone walls usually laid dry, and with a gradient depending upon local conditions. Fanning goes a number of instances of galleries in Ibis and European countries, such as Lawrence, Lowell. Waltham, Mass.. Providence, R. I., Hamilton and Toronto, Ont., Binghamton and Schenectady, N. Y., Perth, Scotland, Angers, Lyons and Toulouse, France. Fanning says: “These basins generally clarify the w’ater in a most satisfactory manner, and accomplish all that can be expected of a mechanical process; but they have not always delivered the expected volumes of water; but, perhaps, too much is anticipated through ignorance of the true nature of the soil and false estimate of ‘ground-water’ flow’.” He gives the average supply per square foot of bottom-area of front 150 to 200 gal. in tw’entyfour hours, with an average flow in the gallery of 20 to 25 lin. ft. in twenty-four hours. The supply at Richmond is derived altogether from infiltration-galleries or welts, and. perhaps, a brief description of its sources of supply and means of collecting its water may prove of interest. This system was inaugurated in 1884. and a contract let to an Eastern firm. Certain requirements as to hydrants, sizes and location of mains, pressure normally and for fire, make of pump, etc., were specified by the
city, through the advice of its engineer. The contractor had his engineer; but, so far as I know, the company had none. Fortunately, the contractor was conscientious, and Richmond was given an excellent plant, which included a io.ooo,ooo-gal. reservoir, giving 65 lb. pressure in the city. The pumping station is located 3 miles east of the city on a branch of the Whitewater river. The geological formation round Richmond is such that deep wells are not available for a supply. There are frequent outcroppings of limestone, overlaid with gravel, and small spring streams are numerous. Test wells for natural gas failed to develop water veins of any consequence below the strata of limestone. This condition necessitated the use of infiltration-galleries, as the city would not permit the use of water from the above stream. Gallery Xo. r is parallel with the stream and about 20 ft. from it. It is 2×3 in section and 1.000 ft. in length. Xo test has been made of the flow in this gallery; but I believe it is capable of supplying 1.000.000 gal. in twenty-four hours. A second gallery was laid in 1887 about a quarter of a mile beyond gallery Xo. 1: but at a greater distance from the river. Its bottom is 12 ft. below the surface, the walls arc laid in stone 2 ft. thick and 3T/> in height, with a distance of 3 ft; between the walls. A 2-ring brick arch is laid on the top of these walls. The length of gallery Xo. 2 is about 500 ft. This gallerv has not given good results, and is not depended upon. Gallery Xro. 3 is about 1,000 ft. in length, and is located half a mile from the pumping station, to which the water is carried by a 12-in. iron pipe. This gallery is situated from 100 to 500 it. from the stream, and furnishes about 500,000 gal. a day. In 1896 an additional supply was investigated, located in a different watershed of about 2 sq. miles area. Tests showed a deep underlying stratum of gravel, with the water-level standing from 3 to 5 ft. below the surface. Geologically, this watershed appears to be the former bed of a large river, tilled with gravel. A 16-ill. syphon line conveys the water to the pumping station 3 miles distant and with a tall of 90 ft. The short leg of the syphon has a rise of y/2 ft. Approximate estimates show this watershed to have a capacity of 2,000,000 gal. a day. At present from 750,000 to 1,000,000 gal. are utilised. It is a water of unusual purity and clearness, with a temperature of 520 at the well in summer. From the receiving well at the pumping station the water is pumped to the city or to tlie reservoir. 1 he latter originally had bouldered sides and a clay bottom. About 1898, a disagreeable taste was noticeable, and traced to the reservoir, where small growths of algK occurred. These were removed in winter by emptying the reservoir and allowing the mud to freeze. In 1903, this condition was so bad, the algte covjj ering the entire bottom, that it was decided to ’ cement the bottom. This remedied the trouble for a few years; but the taste again became disagreeable. Consultation with the Department of Agriculture in Washington resulted in recommendations of the use of copper sulphate. This was done, but with only temporary relief. In 1906 the company engaged Dr. Geo. T. Moore to investigate conditions. His report showed the trouble to be in the mud between the boulders of the reservoir, the copper sulphate apparently not destroying the roots of the chara. In his report Dr. Moore recommended the use of too-lb. applications of copper sulphate, or the lining with cement of the bouldered sides of the reservoir. Two doses were used, but with only temporary success. The company in 1907 decided to resort to cement as a means of removing this annoyance. The work was completed on November 4, and very little taste, if any, is now’ apparent. The 20-in. inlet and outlet-pipe of the reservoir is situated in one corner. By means of tw’o check-valves and a 12-in. line extended to the opposite corner, a better circulation w’as also received. The total cost of the work in 1903 and 1907 amounted to about $15,000, and is considered a good investment. At the time of Dr. Moore’s investigation, in 1906, he also reported signs of crenothrix in the syphon-well. Several applications of copper sulphate have been made in this w’ell, and it is believed this trouble will be removed in a short time. In all this work the advice and approval of the State board of health has been sought, and the company has always endeavored to comply with its suggestions, realising that such co-operation benefit? the company as well as the consumers whom it supplies. NTo case of typhoid fever, so far as T know, has ever been traced to the water furnished. and from a commercial standpoint, the company considers it to its interests to maintain its product at the highest possible standard.
Local officials of the Metropolitan water and sewerage board at Clinton, Mass., have deemed that there is danger of a water famine in the district, which has to draw on over 24.000.000,000 gal. more than it had in the Wachusett reservoir a year ago. and that amount is more than half w’hat the entire district used in the year IQ07. The water in the reservoir,! as a result of the drought, has decreased 3 tt. in elevation, registering 392.23 ft. above the Boston base, as compared with 395.25 two months ago. The decrease in the amount of w’ater in storage in these two months has been only’ 4.000,000.000 gal. The storage quantity reports show t^at now the capacity of the reservoir is 61.276.000.000 gal., as compared with 36,875,400.000 on August 1, 1907-