FILTER-BEDS AT LAMBERTVILLE, N. J.

FILTER-BEDS AT LAMBERTVILLE, N. J.

The Lambertville, N. J., Water Company’s newly completed filtering plant claims to be second in size of the kind in this country. It has been built on the principle of the Lawrence, Mass, Berlin, Hamburg, and other European plants, after plans drawn by Churchill llungerford, C. F., of New York city. There are two filler-beds, situated just below the reservoir, each 60×100 feet (and, therefore, having 6,000 square feet of filtering surface each), which may be used separately. The average daily consumption of water is about 250,0m) gallons. The beds aie identical in construclii n Upon a natural day-bottom a paving of crushed stone is laid on which perforated terra cotta pipe limlerdrains arc run, con necting at the lower side with a main. Around and over the underdrain a layer of crushed stone is placed, on top of which is a layer of coarse gravel, which is surrounded by a bed of the finest sand, 2 1-2 feet thick. Jiy an automatic device the beds are flooded with water from the reservoir to a depth of 3 feet, and there maintained. It must not be mistaken that the bed of sand is what does the filtering, for, according to Peifker, an eminent German authority on filtration, the sand is only a medium on which to form a sediment blanket of the filth and micro-organisms with which water is permeated. It is this blanket which really performs the filtration, and until this is formed the water will cot be perfectly filtered. It usually requires about one month for the blanket to form. The method of filtration is as follows : As soon as the beds are filled with water it begins to percolate through the sand, and so on into the underdrains and thence into the main, which leads to a receiving basin, from which it is let into the distributing mains and conveyed to the city 160 feet below by gravity.

FRED CROSBY, Vice President American Water Works Association.

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