AWWA B102-15 pdf download.Manganese Greensand for Filters
4.2.1 Composition. Manganese greensand shall consist of hard, durable, angular, dense grains of glauconitic sand that will resist degradation during shipping, handling, and usage and will be capable of maintaining a manganese oxide coating.
4.2.2 Dry specific gravity. The manganese greensand shall have a dry specific gravity of approximately 2.4.
4.2.3 Appearance. The manganese greensand shall be substantially free of visible quantities of clay, dust, and micaceous or organic matter.
4.2.4 Hardness. The manganese greensand shall have a hardness of approximately 2 on the Mohs’ scale.
4.2.5 Grain size. Manganese greensand shall have an effective size of between 0.30 and 0.35 mm, as defined in Section 3. It shall also have a uniformity coefficient of less than 1.60, as defined in Section 3. Both effective size and uniformity coefficient should be determined after scraping.
4.3.1.1 Cleaning. Each filter vessel shall be cleaned thoroughly and disinfected in accordance with ANSI/AWWA C653 before any filter materials are placed and shall be kept clean throughout placement and operations.
4.3.1.2 Marking each layer. Before any materials are placed, the top elevation of each layer shall be marked by a continuous line, as well as a line 1 in. (25 mm) above the top elevation of the manganese greensand on the inside of the filter.
4.3.1.3 Clean materials. Filter materials shall be kept clean.
4.3.1.4 Handling materials. Each type of material shall be stored separately. When materials are shipped in bags, under no circumstance shall materials be removed from the bags before they are placed in the filter, except during sampling.
4.3.2.1 Caution in installing material. The bottom layer of gravel shall be placed in accordance with the filter vessel manufacturer’s specifications and placed carefully to avoid damaging the filter underdrain system. Each layer shall be completed before the layer above is started. Workers shall not stand or walk directly on the filter material. They shall walk on boards of plywood that will sustain their weight without displacing the material.
4.3.2.2 Placing one layer at a time. Each layer of filter material shall be deposited in a uniform thickness, with the top surface screeded and brought to a true level plane. Care shall be exercised in placing each layer to avoid disturbing the surface of the layer beneath. Filter material shipped in bags may be placed in the filter by scattering the material directly from the bags.
4.3.2.3 Checking layer elevation. The elevation of the top surface of each layer shall be checked by filling the filter with water to the level line previously marked on the inside of the filter or by measuring from a straightedge laid across the top of the filter troughs. The manganese greensand layer shall be filled to the 1-in. (25-mm) above top elevation line.AWWA B102-15 pdf download.