Total cost $........ Cost per million gallons daily capacity, $..... ........ f. Other structures, as coagulation, sedimental and filtered water Cost per m.g.d. of rated capacity of filter plants. g. Average cost of new services $.. h. Average cost of setting meters $.. i. Average cost of maintaining meters $. 34. a. Unskilled labor b. Meter readers .¢ per hour. .& per hour. c. Engineers at pumping stations. .S... .per month. d. Firemen at pumping stations .... .S. . per month. The following form, with slight modifications, has been used by a number of engineers in this country in their practice during the past twenty years It is inserted for the convenience of concise comparison of different water works properties, by water works men, rather than for use in published reports made by water departments or water works. or more. Consumption, annual, mg.. Daily, mgd. Per capita, gpd Per mile of pipe, gpd. Per service, gpd. Pressure, (range) lbs. Hydrants-number. Gross Revenue, Total $. Per capita $. Per mile of pipe $. Per service $. Per mg. consumption $. Public Water Revenue, Total $ Pub. Fire Protec. (Hydr.) Serv. only $. Per hydrant $. Per mile of pipe $. Gross Rev, excl. public rev. $. Per capita $.. Per mile of pipe $. Per service $ Per mil. gals. $ Oper. Exp. excl. Taxes and Depr. $.. Per capita $.. Per mile of pipe $. Per service $. Per mil. gals $. % of Gross Revenue. Taxes, Total $ Per capita $. % of Gross Revenue. % of Fair Value.. Depreciation Allowance $. Per capita $.. % of Gross Revenue.. % of Net. Reprod. Structures. Net Revenue-Divisable $. Per capita $.. Per mile of pipe $. Per service $. Per mil. gals $ % of Gross Revenue.. Bonds....%. Amount $. Preferred Stock....%. Amount $. Common Stock. Amount $.. Per cent paid... Total Funded Debt. Amount $. Floating Debt. Amount $. Gross Reproduction Cost $......: Accrued Depreciation, on Existing Property $........ (in Abandoned Property $. . . . . . ) : as of. MECHANICAL ANALYSIS OF SAND AND GRAVEL The methods of mechanical analysis now in common use were first used at the Lawrence Experiment Station about 1890. A description of them, as then developed, appeared in the Report of the Massachusetts State Board of Health for the year 1892. In thirty years practical experience has accumulated, committee reports have been presented, and some improvements in procedure have been made, but there has been no change in basic method. Information as to the sizes of the sand-grains is obtained by mechanical analysis. The sand is separated by sieves into portions having grains of definite sizes, and from the weights of the several portions the relative quantities of grains of any size are computed. SAMPLES There are numerous ways of taking sand samples. A sample to represent the run of a sand bank can be taken by drawing the point of a shovel up a vertical face so as to take a small portion of the material as it goes. A number of such moist samples are placed in a pail and thoroughly mixed. Small portions of sand from a washing machine may be put in a pail at regular intervals and mixed in the same way. In sampling sand in a car or barge a long butter tester is convenient for getting samples representing a considerable depth. The procedure must be varied to meet the requirements of the business in hand. Samples are best kept in their natural moist condition in handling and shipping, as there is then no tendency to separate into portions of unequalled sized grains. If the sand by any accident becomes dry such separation is inevitable, and it is then difficult to get a representative portion for analysis. Quartering, as in assaying, is frequently the only method that can be used. Eight ounce wide necked glass bottles are convenient for samples that are to be kept and compared. Small cloth money bags can be sent by mail or express without breaking, and the description can be written on the bag with a soft pencil. They should not be used where there is very fine material or dust. Small pastebroard containers are convenient for samples not to be permanently kept. Duplicate samples for comparison after obtaining the results of analysis are often useful. From half a pound to a pound is enough for a sample of filter sand, but for gravels and sand containing large particles larger quantities are necessary. WEIGHING A small "prescription" scale weighing 100 grams and sensitive to one-tenth gram is convenient, rapid and sufficiently accurate. A quantity of moist sand, such that after drying there will be approximately 100 grams, or such other quantity as is to be used for analysis, is put in a porcelain dish and dried. After drying, the sample is transferred to the scale pan for weighing. If it weighs slightly over the desired amount the excess may be removed and the weight adjusted without appreciable change in the composition of the sand. Otherwise the exact amount weighed is used whatever it may be. After sifting, the various portions of particles, beginning with the finest, are transferred from the bottom pan and from the various sieves to pieces of smooth paper to which the grains do not adhere and in turn are put upon the scale pan and weighed. The weight after each addition is entered on an appropriate record sheet. When all the portions have been brought back the original weight should be reached. If 100 grams were taken the final result should check within 0.2 gram. If a greater shortage is indicated there is some defect in the procedure or the sand was not thoroughly dried. Per cents of the original weights other than 100 grams, are computed by slide rule. DRYING The sample in the porcelain dish must be completely dried before the analysis proceeds. A close regulation of heat is not necessary. Exposure to sunshine in a hot dry climate may be sufficient. A steam radiator or an electric heater will serve or a kerosene stove may be used. With ordinary sands no damage is done if the temperature is carried considerably above the boiling point and this will insure immediate and complete drying; but the sand should not be baked. SIFTING The dried sand is put in the top of the nest of sieves, each fitting into the one below with a cover at the top and a pan at the bottom. The sieves may be shaken by hand for occasional field tests, but generally a shaking machine is employed. The machine frequently used is geared so that 150 turns of the handle give 700 single shakes to the sieves. This is enough ordinarily. The speed must be such that the sand is drawn back and forth over the wire cloth. If it is too slow the necessary movement will not take place. If it is too fast the grains will be thrown back and forth and will not pass the meshes. An experienced operator can tell by the sound what is going on. Test runs with the cover off will be helpful to a beginner. The sifting machine may be attached to an electric motor or other power. In this case it is essential that the proper speed be maintained; and a counter is desirable to show when the necessary amount of shaking has been given. It is sometimes stated that the process should be continued until no more sand passes. This is incorrect. The shaking should be sufficient to get the bulk of the sand that will pass through the openings, and it should be uniform to give comparable results. A few larger holes must be expected in every sieve, and if the shaking is continued long enough everything smaller than these accidental holes will pass. In ordinary work double the amount of shaking will not make more than a few tenths difference in the per cent passing; and this may be taken as a reliable criterion of sufficiency of shaking. The amount of shaking to be used in practice should be the same as that used when the sieves are rated as described below. |