Intermittent Sand Filters. Intermittent sand filters consist of beds of sand, surrounded by concrete curb walls or earthen embankments and underdrained by means of a system of field tile or vitrified pipe. The settled sewage is discharged upon the surface of the beds intermittently by means of the alternating siphons in the dosing chamber. Influent or control chambers are often employed in order to provide more elasticity in the operation of the filters. The underdrains are surrounded with coarse gravel to provide free drainage and an overlying layer of graded gravel prevents the finer filtering sand from being washed into the underdrains. Operation of Intermittent Sand Filters. In view of the fact that the settled sewage is discharged upon the surface of sand beds and that the retention of this liquid for a considerable length of time upon the surface of the sand may result in a nuisance due to odors, it is incumbent upon the operator to maintain the beds in such condition as to admit a free passage of the liquid thru the filter. A pooling of the liquid upon the surface of the sand is a sign that the beds are in need of cleaning. When this occurs, one of the beds should be thrown out of service and the sewage diverted to the other unit or units. The former bed should then be allowed to dry and if a light scum has occurred, this should be lightly scraped from the surface of the sand. No effort should be made to remove the scum until the bed has thoroly dried. When pooling occurs frequently, i. e., within two weeks after the scraping of the beds, the scraping should be supplemented by the removal of the upper crust on the sand, not to exceed one inch in thickness, a raking of the sand surface to a depth of about two inches and a re-leveling of the bed. Filter beds should at all times be maintained free from weeds, as experience indicates that a neglected growth of weeds is one of the most common causes of the filter clogging. If earthen emabnkments are used around the filters, they should be sodded to prevent the washing of clay or loam upon the sand surface. During the winter months, when the surface of the filters is likely to freeze, the beds should be furrowed. This should be done by means of a shovel or flat spade. The furrows should be 12 to 18 inches in. width and should have a depth of about five inches below the normal sand level. This process will prevent the freezing of the entire sand surface during the winter months. With the advent of warm weather the beds should be allowed to dry and the scum and upper layer of clogged sand should be removed and the beds again leveled by raking. The depth of sand upon the filter should ordinarily not be less than 30 inches when the plant is constructed. As soon as the sand layer has been decreased to 24 inches in thickness, new sand should be obtained. This sand should be of good quality and a sample should be submitted to the State Board of Health for analysis. Records of Operation. All operators of sewage treatment plants should realize the value of systematically recording all important data in regard to the condition and operation of their plants. These data, while seemingly unnecessary to the average operator, may, if properly used, be of great value in determining the most efficient methods of operating the plant. Such records are also valuable to the State Board of Health when called upon to investigate complaints in regard to the condition of treatment plants. The operator should be provided with a note book in which these various records may be systematically entered. Sewage Flow. An accurate estimate of the flow of sewage reaching a sewage treatment plant is considered to be the most necessary of the records which should be maintained. The various devices comprising the plant are designed upon the basis of an estimated sewage flow and it is therefore essential that the operator should be able to determine this flow in order to know when the treatment devices are operating above or below their nominal capacity. For the smaller plants occasional observations of flow will suffice. Continuous. records are however valuable in detecting increased flows of sewage due to ground water leakage or improper sewer connections. Measurement of Sewage Flow. In some cases the smaller treatment plants are provided with a weir chamber for the measurement of sewage flow. In such cases the operator should be provided with a table showing the various rates of flow corresponding to the heights of the liquid above the crest of the weir. Ordinarily plate weirs may be easily installed upon the outfall sewer leading to the plant or in connection with the various devices making up the plant. Where continuous records are desired, simple automatic recording gauges may be installed. In those plants where a dosing chamber is employed, the rate of flow may be conveniently determined by measuring the rise of the liquid in the chamber. Float counters may also be installed to maintain a record of the number of times the chamber has been emptied by means of the siphons. Cleaning of Settling Tanks. The records of tank cleaning should include the time of cleaning and the depth of sludge removed. Sludge Disposal. Where sludge drying beds are employed, records should consist of the amount of sludge deposited upon the beds, the depth of sludge, the time required for drving, the date of removal and a statement relative to weather conditions during the drying period. If the sludge is disposed of by burial or by trenching, a record of the quantity of sludge is sufficient. Care of Filters. The essential items to be recorded in connection with the maintenance of intermittent sand filters are the dates on which the beds were weeded, scraped, raked, leveled and furrowed, and also the dates on which the filters were in service. General. In addition to those records outlined above, the operator should note all repairs which were made upon the plant. Notes should also be added in regard to odors in the vicinity of the plant and to the appearance of the final effluent. Conclusions. The State Board of Health realizes that the operators of small sewage treatment plants are to some extent handicapped, due to their inability to obtain definite information in regard to operating methods. Officials in charge of institutions and public buildings are therefore urged to make arrangements with their consulting engineers at the time the plant is completed to make periodic inspections of the plant and to furnish advice in regard to its proper operation. Inspections. of existing sewage treatment plants are made by the division of sanitary engineering of the State Board of Health as often as conditions. will permit, but the volume of urgent work which this division is called upon to do prohibits regular detailed investigations. General information in regard to operation may be obtained by written request, but it must be understood that the division of sanitary engineering cannot act in the capacity of the consulting engineer. ANOTHER STATE CONSIDERS DISTRICT HEALTH OFFICER PLAN. - SACRAMENTO, CAL. There will be two districts north and four districts south of Sacramento, if the legislature at its coming session approves plans of the State Board of Health for dividing California. into health districts. The draft of a bill which has this object in view has been tentatively agreed upon by the board and probably will be submitted to the lawmakers when they convene, with few, if any, changes. The creation of health districts and their administration by specially appointed health officers is regarded by the state health authorities as the most important thing in their legislative program. For the purpose of dividing the population as equally as possible in accordance with the need of counties for better health and sanitation control, it is proposed to create three districts along the coast and three in the interior. In addition to the appointment of health officers, the bill provides for the appointment of ten sanitary inspectors with police powers to making arrests for violations of the state health laws. The salary proposed for health officers to be paid by the state is $3,000, and for sanitary inspectors $1,800 each, together with traveling expenses. To qualify for appointment it is provided in the draft that each district health officer shall be the holder of a degree in medicine, sanitary engineering, or public health and shall have had at least a year's experience in public health work. REPORTING CASES OF VENEREAL DISEASES. The Chicago Department of Health is supporting an ordinance submitted by the Morals Commission to the Committee on Health of the Chicago City Council. It requires physicians to make a report to the Department of Health each month of the number of cases of |