A WELL-EQUIPPED AIRPORT OF THE FUTURE, OPERATED IN CONJUNCTION WITH OTHER MUNI- able for use at any hour, including boundary lights, obstruction lights and beacon, in strict accord with the Department of Commerce recommendations. A feature of the development is that everything except the concrete floor of the hangar has been built with a view to easy removal, if necessary, to whatever permanent site may be selected. Even the electric cable carrying current to the boundary lights can be ripped out of the ground with a tractor and relaid where desired. The administration building was purposely planned only 33 feet wide, so that it could be loaded on trucks and hauled along the highways to any point. The Oakland Site Somewhat the same view taken in Portland has been assumed by the Oakland authorities. As in Portland, the expense of developing this airport is being covered from the surplus revenues of the Port Commission. The Oakland site is on Bay Farm "Island," a peninsula just south of the city in San Francisco Bay. The cost of the bare land is $650,000, and no esti Santa Monica's Field mate of the expense of improving has been completed as yet. Runways as long as 6,000 feet can be developed on this site, thus enabling it to accommodate the heaviest planes now built or foreseen for the immediate future with a very high factor of safety. Santa Monica's field is a 144-acre affair, of which 80 acres are used. It was financed through a bond issue under the California Parks and Playgrounds Act, which permits formation of an assessment district to pay for certain classes of public improvements. Sources of Information on Airports and Aviation THE The foregoing article was written for AMERICAN CITY just before the intrepid Lindbergh made airport development an inescapable The problem for American municipal officials. information on which this timely outline of progress in the West is based was gathered by the author for the Airport Committee of the Board of Supervisors of the City and County of San Francisco, and its publication is with the consent of that Committee. Mr. Lane's investigations, which covered a trip of some seven weeks, involved studies of surfacing, meteorological conditions, obstructions in air approaches, physical connections, distances from post offices, hangars and other improvements on the fields, lighting equipment, and revenues, both real and anticipated, of the major airports in the West Coast cities. Municipal officials, chamber of commerce executives, and other readers of THE AMERICAN CITY interested in airports and aviation, can secure information of much value from the following Aeronautics Branch, Department of Commerce, Washington, D. C.-An Airway Bulletin in looseleaf form, a mimeographed Domestic Air News, and occasional special bulletins on construction of airports, air traffic rules and similar subjects are published by the Branch. A preliminary list of about 1,000 of the more important landing fields owned by cities, commercial organizations, business corporations, individuals and Government services has just been made available. This includes 207 cities having municipal airports completed or under construction. Transportation and Communication Department, Chamber of Commerce of the United States, Washington, D. C.-The Department published on April 25, 1927, an exceedingly valuable bulletin on Air Transportation, and offers the cooperation of the National Chamber in furnishing further information. American Academy of Political and Social Science. -The May number of The Annals, devoted to the topic of aviation, is listed on page 117 of this issue. This "Airports and Airways."-By Donald Duke. new book, published in June, 1927, is reviewed on page 117 of this issue. "Transport Aviation."-A 251-page book by Archibald Black; published in 1926; $3.00. "Civil Aviation."-A report by the Joint Commit. tee on Civil Aviation of The United States Department the American Engineering of Commerce and Council; published in 1926; 206 pages; $2.50. FLYING AND PARKING RULES FOR STATE AERONAUTICAL CONGRESS, HELD AT SAN FRANCISCO MUNICIPAL AIRPORT, MAY 5-7, 1927 Automatic Control of Sewage at the Syracuse Sewage Treatment Plant TH By E. F. Sipher HE sewage treatment plant which was put into operation at Syracuse, N. Y., last fall, contains several unusual features. Of particular importance is the method employed to control the rate of flow of the sewage through the grit chamber, which makes use of automatically controlled motor-operated pumps to maintain the velocity of the sewage within close limits, without excessive loss of head. Because of the topography of the city it is necessary to pump the sewage up to the treating or settling tanks. The sewage enters the treatment works at an overflow chamber, which is connected to a deep-water conduit leading to Onondaga Lake, near which the plant is located. This conduit is not used except in emergencies such as floods. From the overflow chamber the sewage passes through a coarse screen, which removes sticks, logs, etc., into a three-compartment grit chamber, then through fine screens which are mechanically raked, one screen for each grit chamber, and thence into the pump well. From here the sewage is pumped, by three Morris 24-inch horizontal pumps of 18 million gallons daily capacity each, driven by 75-h.p. wound-rotor motors, through a 48-inch force main and venturi meter to the settling tanks, where the sewage is clarified. There is one similar pump in reserve. The effluent passes from the grit chamber through a conduit to deep water in Onondaga Lake. The sludge as it settles is slowly forced to the center of the settling tanks by the plow blades on the revolving arms of the Dorr clarifiers and drawn out by sludge pumps and forced through a 4-inch main and buried with the wastes from the Solvay Process Company. When the velocity of sewage is reduced to one foot per second, the grit will settle out, but the organic matter remains suspended and passes on with the sewage. With velocities lower than one foot per second, the organic matter begins to settle out, and with higher velocities than one foot per second, the grit is carried over into the pump well. Control of the velocity of the sewage may be obtained by using a weir in the grit chamber, or by the shape of the grit chamber and means for con MAIN PUMP-ROOM AND SWITCHBOARD AT THE SYRACUSE SEWAGE PLANT trolling the rate of pumping within close limits. With the weir there is a loss in efficiency due to having to raise the sewage from the pump-well level, which of necessity must be lower than the grit-chamber level. Where the grit-chamber velocity is controlled directly by the rate of pumping and without a weir, the sewage level in the pump well is the same as in the grit chamber. Therefore, with the latter arrangement the pumps have less work to do. The grit chambers at the Syracuse plant are without weirs and the velocity is controlled by means of pumps. There are three of these chambers, one being used for each pump in service. Overhead is a direct-current, motoroperated traveling crane carrying a grabbucket, for removing the grit. This motor is the only direct-current application in the entire plant, and it receives its current from a motorgenerator set in the main pump-room. Each grit chamber has a motor-operated sluice-gate at the inlet end, controlled by push-button from the main switchboard, and a mechanically raked screen at the outlet end driven by induction motors which are also controlled from the main switchboard. The plant is designed to pump a maximum of 55 million gallons per day, with three pumps in service. Anything in excess of this is bypassed to the lake. In the main pump-room along one wall are two vacuum pumps driven by squirrel-cage motors controlled by automatic auto-starters. Here is also located the motor-generator set for furnishing direct current to the grit-chamber crane. Down through the center of the room are the main pumping units, four in number, only three ever being used at one time, the fourth being a spare unit. The entire plant, except the grit-chamber crane and the sludge pumping-station, is controlled from the eighteen-panel switchboard. The power used on all motors except the directcurrent crane motor is 440-volt, 25-cycle, and all control circuits on the face of the panel are 110-volt. The first panel at the left is the circuitbreaker or entrance panel, providing metering instruments and overload and no-voltage protection for the entire plant. Adjoining are five panels for the control of the main pumps, then two panels for meters for the main pumps, and a panel for auxiliary apparatus such as vacuum pump motors, sump pump, sluice-gates, screen rakes, etc., with ammeters and push-button control. A protective circuit-breaker panel with ammeter is provided for the cables to the sludge pump-houses. There is a panel for the motor generator set with meters and a carbon breaker for protection of the direct-current line to the grit-chamber crane and a lighting panel for the main circuits of the plant lighting system. There are also two panels for the control of the sluice-gates, four panels for the hydraulic meters and instruments, and valves for controlling the hydraulically operated gate-valves on the main pumps. As stated before, the velocity through the grit chamber is controlled by the rate of pumping or the speed of the pumps. The level of connected by a sprocket and chain to a float in the pump well. This device makes a contact at every 0.2-foot change in sewage elevation. A horizontal rack or slider with its contactmaking parts moves along a row of fingers which make contact with the large drum. The contact-making device at the same time resets for the next 0.2-foot change in level. The only function of the float is to give the starting impulse to the pilot motor by means of the contact-making device; all other operation of the master control is carried on by motor drive. The float can therefore be relatively small and readily responsive to small changes in elevation of sewage. The large drum is divided into three sections, one for each condition of one, SETTLING-TANKS AT SYRACUSE SEWAGE WORKS, SHOWING DORR CLARIFIERS the water in the pump well is used to regulate the speed by means of a float and special Westinghouse control apparatus. The total working range of elevation in the pump well and grit chamber is approximately 3.6 feet. Any rise in the sewage above this point indicates a flood condition, and the sluice-gates are throttled down to keep the maximum output of the plant down to the 55-million-gallon-perday rate; any sewage in excess of this amount escapes to the shore relief conduit through the overflow chamber. At each 0.2-foot change in elevation of the sewage in the pump well there is a change in pump speed. When more than one pump is running, all pumps are operated at the same speed and discharged into a common header. The controller designed to take care of these conditions consists of a contact-making device two, and three pumps in operation, and there are seventeen fingers in contact with this drum, the same as the number of 0.2-foot divisions of operating range of elevation in the pump well. Each section of the drum consists of two segments separated by a "zigzag" strip of insulation, one giving forward direction or increase in pump speed, and the other reverse or decrease in pump speed. These sections are automatically selected by relays, depending upon the number of pumps in operation, no matter which of the four pumps are being used. It is not necessary to change any jumpers in order to change the sequence in which the pumps are to be run. The master drum is connected by a clutch and operating shafts to four Westinghouse cam controllers which vary the resistance in the secondary of the main pump motors, there |