THE WATER SUPPLY OF CHARLESTON.
The situation of Charleston, upon the extreme point of a peninsula, surrounded on the east, south and west by saline waters, presents a problem of unusual interests to students of municipal water supply. A brief review of former supplies and resources will be of interest and throw some light upon the difficulty of the problem now confronting the city authorities.
Underlying the peninsula at a depth of 15 to 20 ft is a bed of hlucbtack day, quite thick and impervious to water. The over burden at the time of the original settlement consisted of quartrose sand, which was practically saturated with water, receiv ‘d from a rainfall averaging 45 in. a year. As a consequence, in the earliest days of the colony, the citizens were amply provided with water for all sanitary purposes by shallowwells, varyingfrom 10 to 30 ft. in depth. The water was raised to the surface by means of wooden pumps, or with a windlass and bucket arrangement. Each house thus maintained and controlled its own source of water. It is to be regretted that no description of these waters exists other than the statement that they were cliar, limpid and palatable. Without proper disposition of sewage matter, and because of the porosity of the sand, as well as its shallow depth, contamination of these wells quickly followed the growth in population. Surface waters from every source found their way practically unaltered into the drinking waters of the community. Numerous epidemics of typhoid fever and other waterborne diseases followed the continued use of this source of water as a natural consequence, and soon led to its abandonment.
In consequence of the pollution of these ground waters and in an effort to secure relief from such unhealthy conditions, the wealthier citizens of the community conceived the idea of utilizing citerns to catch the rain which fell upon their roofs. This water v as storeul in suitable reservoirs, which, for convenience and in order to cool and preserve it for domestic use, were placed unde rground. Under the house itself or the kitchen which adjoined the house was preferred as a location. The water was withdrawn for use by pumps situated either in the kitchen or yard, as suited the individual fancy or convenience; servants then distributed the water to the various rooms >f the house, where it was to be used for drinking, laundry or bathing purposes. In some instances the water was pumped to a tank, situated on the roof of the house, whence it was distributed by gravity These cisterns were built of wood or of brick, principally the latter. The early brick ones were unlined, but were subsequently lined with cement, as are all of the more modern cisterns. Many of them are still in existence and are in constant use by a large majority of the present inhabitants of the city: this. too. in preference to either the attesian water or the municipal supply, even in the face of the established and wellknown relation existing between their use and disease. (With a population of over 60,000 inhabitants there are only a few over 3,000 subscribers to the present supply.) As cisterns are the source of water for so large a number of citizens, and as they play so prominent a part in all discussions relating to the municipal problem, they merit a full description. Many of them are very large, twenty or more feet in diameter, and capable of holding several thousand gallons of water. This size was necessitated, of course, by the varying rainfall, and the fluctuations in the demands made upon them. In the larger cisterns an effort was made to filter the water by introducing a brick wall which divided the cistern into two equal portions. The water from the roof, gathered by means of the gutters, was allowed to flow into one portion, and hence found its way by percolation through the porous material composing this wall to the other half of the cistern. An attempt was also made *o control the character of the water entering these reservoirs by means of a shutter placed in the gutter or pipe leading from the roof. This shutter was so arranged that it could be adjusted to waste the water first falling upon the roof. Usually, though, as is generally the case when such matters are relegated to the care of servants, the shutter was turned so as to permit all the water from the roof to enter the cistern, regardless of is quality.
When first put into operation, these more or less crude filters doubtless performed their functions satisfactorily, but from accumulation of bacteria, dirt, dust and debris from the roof, these filters became in the course of time more foul than the water they were designed to cleanse. From their nature it is practically impossible to clean these walls of the befouling matter. Each accession of water from the roof to the cistern serving only to wash the accumulated aerial sewage through the interstices of the filtering wall. As can be easily imagined, removing accumulated sediment and otherwise cleansing these cisterns is often an herculean labor. This feature of the cistern supply gives employment to a large number of men who make such work a specialty.
With the increasing pollution of the shallow wells above referred to, this supply grew rapidly in favor, until even the most modest dwelling was so furnished with water. It may be mentioned incidentally that the cistern “built in” underground is the favorite haunt of untold hundreds of enormous wharf rats which, in time of persecution, find here a safe retreat from all enemies, making it extremely difficult to exterminate them. In an indirect way this adds another menace to the health of the community utilizing such waters. It also frequently happens that young birds falling from the parental nest are washed into the gutters, and so find their way into the cisterns to add further spice to this favored supply. It is almost unnecessary to add that they make an ideal breeding place for mosquitoes.
Fifty analyses of cistern water, made by the writer and covering a period of two years, gave the following results: Fifty per cent, ol the total number were unmistakably contaminated, and unfit for drinking purposes; 12 per cent, were suspicious, and should have been condemned as a precautionary measure; 4 per cent, were in a condition that might be called doubtful. Only 34 per cent, of the total number examined could be pronounced as perfectly satisfactory from a sanitary point of view. These waters were taken at random throughout the city and are fairly representative. though quite a number were taken from humble portions of the city.
THE FIRST DEEP WELL.
In the early part of the last century thoughtful minds were aroused to the potential evils lurking in the use of such waters, and. becoming alarmed, determined o augment the supply in the city by utilizing waters higher up on the Neck, which were as yet unpolluted. Numerous plans were laid before city council: one was to pipe the water from the springs by means of wooden box pipes. nother plan which was proposed was to firing the water to the city in carts, peddling it from door to door, as the artesian well water now is carted from door to door and sold in amounts varying from one to five gallons. But as none of the plans offered were feasible or were entirely too extravagant, nothing was done at this time.
li was about 1820 when the first socalled deep well was sunk. 57 ft. deep, penetrating the strata of blueblack clay above referred to. and opening another bed of water bearing sands. This was accomplished In digging down to the clay bed at 30 ft. and then driving an iron pipe 37 ft. through the clay. This was far deeper than any heretofore attempted in this locality, and was in actual use until quite recently. The cost of digging the well was $1,000. considered a very large amount at the time. At a somewhat later period, the city council dug a number of these wells, and maintained them as “fire wells.” that is, for use in protection against fires. One of these wells, said to have been the best in point of quality as well as quantity, was situated near St. Michael’s alley, at the of the church yard, on Meeting street The flow from all the wells of this depth continued copious until they fell into disuse as a consequence of the greater demands of the city necessitating other sources of water.
THE ARTESIAN WELL.
In 1823, the city council determined to dig an artesian well. After intermittent work covering a period of 20 years, water was obtained at a depth of 1,200 ft., at total cost of thirty odd thousand dollars. This well, together with two others sunk subsequently, constituted the sole municipal supply until 1904, the city franchise being held by a stock company known as the Charleston Water company. These three wells yielded a maximum of about 1,800,000 gal. per twenty-four hours by pumping. During the last of the service by the Charleston Water company the water was elevated by meanus of an airlift to a pumping reservoir, from which it was pumped into a standpipe with an elevation of 80 ft. This supphed the distribution system by gravity, but the pressure upon the mains and service pipes was never very great.
As shown by analysis these waters are highly charged with carbonate of soda, and sodium chloride. For this reason they are not at all satisfactory for steam making purposes, as well as objectionable because of the large percentage of total mineral matter in solution. Foaming and priming were among the least of the evils incident upon the use of so alkaline a water in boilers and heaters. Chiefly because of this unfitness for manufacturing purposes and because of the brackish taste the artesian water never found universal favor, though highly esteemed for bathing by every one because of its softness. This water is said to be slightly therapeutical in its action on the human system, being beneficial in dyspepsia and similar disorders. However, the yield of the combined wells was not adequate to meet the needs of the city. During the last few years of this service full supply and pressure was given only for a small portion of each day. The inequality in supply and demand was so unsatisfactory and the subject of so many vigorous complaints from all classes that it was determined by city council to undertake more extensive investigations than any heretofore attempted.
Edisto river has always been considered the ultimate source of water supply for Charleston, and it was decided to look into the feasibility of bringing water from it into the city. In 1899 city council employed Mr. J. L. Ludlow. M. Am. Soc. C. E„ of Winston-Salem. N. C., to make the necessary surveys, estimate the cost of erecting a plant capable of furnishing 5,000,000 gal. of water per twenty-four hours, and secure all the data relative thereto. The investigation showed this source to he a highly desirable one, hut it was also brought out that too great a financial outlay would be involved and accordingly the Ashley river and Goose creek were investigated. After an exhaustive study of the Goose creek watershed, involving not only quality, but the quantity of available water, as well as the cost to the consumers, it was determined to attempt to use this water area. Accordingly, a company was formed which, taking over the works of the Charleston Water company, became known as the Charleston Light and Water company. This company, financed for the most part fi.y Northern capital, was granted a provisional franchise by the city, and began work on its plant in 1902.
The analysis of the waters of the Edisto and Ashley rivers and Goose creek show that they arc not essentially different. The high color, ammonia, free and albuminoid and chlorine in these waters are ail due to natural causes; the peaty nature of the country through which the streams flow and proximity to the coast. The waters from the Carolina coastal plains have frequently been compared with the waters of lake Drummond, and of the Great Dismal swamp, Virginia. The similarity is notable. These latter waters were held at one time in high esteem by the inhabitants and mariners, hut with the introduction of modern methods ot water treatment and the installation of condensers aboard ship, use of these waters has been abandoned to a large extent.
THE WATER PLANT.
Saxon’s Crossing. 15 miles by rail from Charleston. was chosen as the place for the location of the power plant, filter beds, sedimentation basins, dam and necessary buildings. At this point Goose creek is 2.000 ft. wide, and 20 ft. deep. The water was extremely saline, containing as much as 4.500 parts chlorine per 1.000,000 at times of high tide. In order to meet the difficulty offered hv tidal fluctuations in the stream, it was proposed to build a dam. impounding the fresh waters and excluding the saline tidal water. This was easily done, and the work was commenced in the latter part of 1902, and completed in the fall of 1903. Water was first pumped into the city from this plant in January, 1904.
The reservoir formed by the construction of this dam holds 2,800,000,000 gal. of water when full, covering an area of 2,100 acres. Back water extends a distance of 10 miles above the dam. Xo effort has been made to remove the organic matter from the reservoir, except floating islands round the mouth of the intake pipe, which is 2,000 ft. upstream from the dam. This intake pipe is composed of 30-in. terra cotta laid on piling to prevent it settling into the soft floor of the reservoir, and discharges into a suction well close to the station. The pumping station is built of red pressed brick, steel roof trusses, slate roof, with floors of cement. The pumping machinery Installed consists of duplicate cross compound pumping engines, each one having a capacity of 5,000,000 gal. per twenty-four hours. In addition there is a triple expansion duplex pump of 3,000,000-gal. capacity per twenty-four hours, and two triple-expansion low service duplex pumps, each having a capacity of 5,000,000 gal. per 24 hours. The three high-service puntps were built for a fire pressure of 125 lb. per square inch, but are run under ordinary consumption at 60 lb. to the square inch. The pumps are operated by three tubular boilers, each one having 2,012 sq. ft. of heating surface. The filter plant was installed by the Jewel Filtration company. It consists of an operating platform, 15 ft. above the floor of the building, 10 cypress tubs, agitators, Weston controllers, loss-of-head gauges and other necessary accessories. The sedimentation basin is situated upon a small hill, between the reservoir and the railroad station, and is about a quarter of a mile from the pumping station. The building containing the pumps, filters, etc., is about 200 yd from the reservoir.
The water from the reservoir is drawn first into the suction well above referred to, where it receives the first treatment or dose of lime and alum. From here it is raised by means of the low-service pumps through 21-in. mains to the sedimentation basins. After complete .sedimentation has taken place the water is withdrawn from the opposite side of the basin, passing through a 24-in. main to the pumping station, where it is distributed by pipes of suitable size to the filter beds. After passing through these the water is collected in a clear water well, located near the building. Entering on the side of the well farthest from the building the filtered water is withdrawn as required in the city, through a 36-in. suction pipe, located on the side of the well nearest the station. The elevation of the flow line of the sedimentation basin is 44 ft. The floor of the pumping station has an elevation of 17 ft., and this is the elevation of the floor line of the clear water well. The elevation of the filter tubs is 33 ft., the operating floor being 3 ft. lower; while the elevation of the streets in the city is 10 ft. The main’s conducting the water from the pump ing station to the city are 24 in. in diameter, and are 17 miles in length. The water from the sedimentation basins enter upon the filter beds under an initial head of 4 ft. When from the accumulation of the gelatinous mat of aluminium hydrate, suspended matter and baeteria, the head is reduced to 2 ft., the filter beds are washed by a reverse current of the filtered water.
The water company began the operation of this plant in 1904. When the dam above referred to across Goose creek was first closed, the chlorine content of the impounded water was 4.000 parts per 1,000,000, but with the exclusion of the tidal waters the chlorine content gradually fell until normal conditions obtained. The chlorine now varies from 12 to 35 parts per 1,000,000, dependent upon the season and the amount of rainfall upon the watershed.
TROUBLE CAUSED BY ALGAE.
Shortly after the plant was put in operation serious trouble was caused by a growth of crenothrix in the reservoir and pipes of the distribution system. This caused the water to become foul, of a most disagreeable odor, as well as most unpalatable. Upon examination it was found that tilt water was devoid of oxygen in solution, a condition favorable to the growth of this organism. Pumping air into the waters of the reservoir proved a simple and easy remedy for this trouble, but the odium and suspicion directed toward the water at the time have never been dissipated. Since this outbreak the water has been comparatively free of algae growth, with the exception of the annual summer appearance of an abaena circinalis and other algae in some numbers. The growth of these, however, is checked with ease by the application of small amounts of sulphate of copper, in accordance with the suggestion of Dr. Moore, of the Government service. The treatment to which the impounded water is subjected consists in the addition of lime, followed by sulphate of alumina. This latter is disassociated in the alkaline waters with the formation of the hydrate of alumina, which, acting mechanically, incloses the coarser particles composing the turbidity and suspended matter, and carries them to the floor of the sedimentation basin, whence they are removed from time to time. The small portion of the hydrate which escapes sedimentation is carried through the pipes to the filter beds, where it completes its work bv forming the gelatinous mat on the sands of the bed, retaining the finest turbidity, suspended matter and the bacteria.
THE SEDIMENTATION BASINS.
The usual office assigned sedimentation basins in treatment of water is to allow a period of quiescence to the waters as withdrawn from the reservoir or stream. In this way the large particles carried mechanically by the force of the stream would be deposited, and the filter tubs relieved of much extra work. In this water under consideration the stream possesses little current, so that the turbidity and suspended matter is negligible, and the sedimentation basins are used chiefly for the chemical treatment. It is here that the major portion of the color is removed. About 75 per cent, of the purification takes place *n these sedimentation basins. Original turbidity and suspended matter is reduced 100 per cent., reduction in color 75 per cent., removal of albuminoid ammonia in suspension is 75 per cent. On the other hand, bacterial life seems to thrive particularly well upon this alkaline water. Comparative bacterial counts indicate a decided increase in the number of bacteria while in the basins amounting to as much as five or six times the number originally in the impounded water. The period of sedimentation is at present three days. ‘These five items as above enumerated constitute the sum total of the purification to be accomplished, as the other requirements of the fianchise deal with other qualities of the water. The hardness in the untreated water is less than that in the effluent front the filter beds, so that the limit of 45 parts of hardness per 1,000,000 established by the franchise is the limit of the amount of lime which can be added. Chlorine is a constant factor, and is not in any way affected by the treatment to which the water is subjected.
THE TEST OF THE PLANT.
In accordance with a clause of the provisional franchise, the plant was submitted to the board of water commissioners for inspection and approval. On the first day of June, 1908, a most searching examination of the plant was commenced under the direction of Mr. J. L. Ludlow, consulting engineer to the board of water commissioners, ami of Dr. F. L. Parker, jr., chemist and biologist to the committee on water supply. Designed originally to cover a period of 00 days from the above date, these tests were extended over an additional period of 60 days. In all 120 days were devoted to these tests.
In a report to the board of commissioners, dated October 12, 1908, Mr. Ludlow unreservedly commends the Goose creek supply and the plant and work of the Charleston Light and Water company. His report is most minute, covering every phase of the tests. W hile admitting the failure of the company to come within the guarantee in some respects, his opinion is that the water company has earned its right to the franchise in a most satisfactory manner, lie recommends that it be allowed to enter upon the privileges and to enjoy the emoluments of the franchise at once.
Dr. Parker, in his report to the committee on water supply, does not concur. His summary of the conditions is as follows: “The Charleston Light and Water company has met the specified requirements as to chlorine, total solids, exclusive of common salt, hardness, removal of matter held in suspension, removal of albuminoid ammonia held in suspension. They have met requirements as to color, odor, and taste. They have not met requirements as to removal of bacteria and the number remaining in the water. Its use for domestic purposes is rendered less valuable on account of corrosion of pipes and discolorations of hot water from hot water feeders and kitchen heaters. It is not a good boiler water. It is suitable for most manufacturing purposes.”
The failure of the water company to maintain the required bacterial efficiency can be remedied by the installation of additional filter units. The company is now making preparations to do this, and will soon be in a position to fulfill the require ments of the ‘ranchise in this respect.
The corrosive action of the water is a more serious and more difficult phase of the problem. It has been the common experience of all students of water filtration that the mechanical filters yield a corrosive effluent. This is especially noticeable wdicn such a water comes into contact with heated iron, copper, zinc, tin and other metals. Some of the action at least is due to the necessary alkaline haracter of the water, though there are doubtless many other contributing factors for the subject of corrosion and incrustation is a most complex one. This phase of the action of water is at present engaging the attention of some of the most noted experts in the world, but the whole subject L still in a more or less chaotic condition.