Developing Water Supplies of Small Cities
Important Considerations are Quantity, Purity and Economy—Employ Competent Engineer—Storage—Pumping Equipment—Pipe layout
THE choosing of the best available type of water supply for a small city or village is fully as import ant a matter as the same operation for the municipality of larger size. The most important considerations are ample quantity, purity of a supply and the matter of economy both in installation and in operation. The following article gives some excellent hints as to the best method of choosing the water supply for a small city or town:
The necessity of an ample and pure supply of water is not open to discussion, but means by which this result may be attained, often become the subject of widely diverging opinions. It is not the purpose of this article to give information of a quantity and quality that will enable the novice to design and build a complete water works system. It is intended only to give a general idea of the results to be obtained, and some of the things to be avoided as well as done.
It Pays to Employ a Reputable Engineer
First we would recommend the services of a good reputable water-works engineer, one who has a good record of service. In many instances the engineer is chosen on price alone; this is an unfortunate condition, and often results in a real calamity to the municipality. When choosing your engineer, make your selection primarily on his ability and reputation, with price the secondary consideration. A good engineer will save money, and in addition, build a system that will be well designed and constructed; one adequate to meet present as well as future needs. Though you should have a fairly comprehensive idea of the complete system and decide the main scheme or general plan, the details and a great many of the minor constructive features and should be left directly to the engineer for his decision.
Prime Requisites for a General Water Supply
The prime requisites for a general water supply are purity and freedom from excessive hardness and chemicals which tend to make the water undesirable for domestic purposes. Whether the water is taken from a lake, stream or well, the location should be chosen with the idea of avoiding contaminating surface waters. Where surface water is stored and used, it should be filtered, or at lease treated with a chlorine solution.
Often the source of the water supply is determined by cost alone. Sometimes the mistaken idea of the municipal authorities, and many times the lack of the necessary funds to go to the proper supply, control the choice of location. These are unfortunate conditions, as many towns are compelled to use water that is undesirable and also dangerous.
Our state law makers have seen fit to make nothing but hard and fast laws regarding the handling of public funds. In many cases this is the direct cause of poorly designed and equipped water systems, doing the people a positive injury, both to their physical being and purse.
There is a type of pump best suited to each condition. Some pumps are better than others. Pumps should be of a recognized make and consideration should he given to their efficiency as well as their general make-up. This is the era of electricity and when current is available, motor driven pumps can generally IK* used to the lx*st advantage. Where water comes near enough to the surface to permit the placing of the pump at ground level, or in a pit not more than 20 feet deep, the motor driven turbine pump should be first choice. It also might be desirable to use the triplex gear head at ground level and the cylinder in a pit at a depth not exceeding 25 feet.
In the deeper wells we have the choice of pumps that have single stroke (single stroke, double acting), double stroke or triple stroke. Of these various types, the double stroke seems to be the most popular. The lifting of water from well to a surface reservoir with air pressure is expensive. There are instances where ibis has been found to be the only satisfactory means of securing water, but under usual conditions it is not considered.
The pumphouse building should be built around the machinery, not the machinery made to fit the building, as is often the case. The building should be of substantial construction and of neat appearance; its location will determine to a great extent the amount to be spent for exterior decoration. The interior arrangement should be such that all equipment is easy to ojx*rate, and with plenty of light; also with the idea of making the work as easy as possible for the o]x*rator.
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Developing Water Supply of Small Cities
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Every system should have a tank or reservoir. 1 his tank should be placed at such a height that will give a minimum pressure of fifty pounds in the district to he served. This tank has other useful and saving values in addition to that of storage value. It relieves the mains of the excessive shcx’ks of the pump and permits the pumps to be run to their full capacity, until tank is filled, when they may be shut down, fhe tank permits the pumps to be started and stopped automatically. Iceing controlled by the height of the water in the tank.
The operating records kept in some of the larger cities, where pumping used to be continuous, show that the storage tank has lowered their costs very materially. For all classes of municipalities, and especially the smaller ones, where the amount of water used is small, an all-steel elevated tank will serve advantageously in most cases.
It has been the practice to figure storage at 50 gallons per capita, with a reasonable allowance for growth and a minimum of 30,000 gallons. This minimum has been increased to fifty thousand by a great many engineers and insurance boards. Tanks on 100-foot towers have been the common height throughout the country. Some insurance boards have increased this height to” 125 feet. A pressure of 50 pounds gives a fairly satisfactory fire fighting pressure, for average small cities.
Fire protection and insurance are naturally inter-locking. The system should be designed and built so as to secure the minimum insurance rates. You may get a low rate and still not have the maximum protection against fire. Thus you see you must have both conditions in mind when designing your water works. Your engineer should have, when possible, the rating bureau approve the plans and give in writing your new rates and classification.
In the past pipe layout has received too little consideration as to sizes and arrangement. The ideal system gives ample water and fire protection to all. It has complete circulation, or in other words, has no pipe extending out a street without a return. Often this can not be avoided, but when possible the ends should be connected. Valves should be placed so as to cut out the minimum number of users when repairs are being made in any particular section.
It is best to have all lines fed from two or more directions. Also avoid the common error of using pii>o .vhich is too small, as the smaller pipe may cost more each year for extra power consumed by friction loss than the additional cost of the larger pipe. If a line is built for present needs only, when increased demands are to be met, trouble and expense will be encountered in the attempt to give satisfactory service.
Fire Hydrants Easily Accessible
Re sure that your hydrants are easily accessible and that they will so remain, even during a large fire. The fire hose should he one of the better known standard brands. It should have a smooth interior, as the friction loss is great in the hose. Your hydrants should not be placed too far apart so that this loss may be reduced and better pressure maintained.
In many systems the layout is such that in case of fire it is necessary to pump direct at pressures varying from 90 pounds to 125 pounds. A great amount of this pressure is consumed in friction loss, caused by pipes being too small and a poorly designed layout. These high pressures cause a great many leaks, both in the mains and in the plumbing. This water waste and the plumbing repairs can and should be avoided by the storage of water at a height that will give a minimum pressure of about 50 pounds. This gives a good domestic pressure and is sufficient for a large jrercentage of fires.
In municipalities of 3,000 population or more, there should also be provided a motorized fire pump with a capacity of about 350 gallons per minute. This will be ample for 2 ordinary fire streams or one large one. With this you save breakage and leaks; also you avoid the use of heavy pipe and at no greater cost when spread over a period of time. In addition you will have real fire protection.
The meter is important as a saving device. Every user should he metered, whether he gets water free or pays for it. Also there should be a meter at the pumping station, so that all water going into the mains will he recorded. This checked against the amount metered to consumers will enable you to note the discrepancies, and when it becomes too great, means can be taken to correct the situation.
Care in Drawing Up Bond Issues
One of the greatest sources of delay is occasioned by the faulty actions of the council in making the necessary steps in the bond proceeding to meet with the laws so that there can be no successful attack made on their legality. This is not the fault of the members of the council and sometimes not of their attorney, but the blame must be laid on them. Your attorney, in a great many cases, has never had charge of drawing up the papers for a bond issue, and until be has had experience, and finds bow many places be has not complied with the law, the chances are that a new election will have to be called, or you will not be able to sell the bonds. We do not wish to take any honor from the attorney, but in the smaller towns he is not the logical man to supervise the steps to be taken. Some engineers may object, and all lawyers will, but it is my belief that all engineers should make themselves familiar with the laws and statutes in relation to the issuance of bonds. Then have some high class bond attorney write a brief giving in detail every step in its regular order, for towns and cities of various classifications in that particular state. If this was done it would save great delay and in many cases a great deal pf money. Your engineer would not get this especially for you but should have it for the use of his clients and as a part of his regular service.
(Excerpts from paper read before the Annual Convention of the Illinois Section, American Water Works Association.)
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