11-26-2001 Council Packet - Laserfiche WebLink

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OCT-31-01 UED 12:11 PH DEEPHAVEN CITY HALL FAXNa 18124741274 P. 08 Section 330:00 one and one-half inches. Other filter media and related filter and back^^'ash rates may be used subject to approval by the health ofGcer. Patented underdmin systems may be used provided that they give results which arc equal to or better than that above. Diaiomite Type Filters. 1. 2. Diatomite type filters shall be designed for operation under pressure or vacuum. The design capacity shall not exceed two gpm per square foot of effective filter area. The determination of the filter area shall be made on a basis of a true and effective supported septum surface. In the case of fabric septums, the area compulation will be made on the basis of measurements of tlie septum suppon in a reasonably constant plane. Area allowance shall not be granted for folds in the septum fabric or deviations in the septum surface which could easily bridge. Tlic lank containing the filter dements shall he constructed of sled, plastic or other suitable material, which will satisfactorily provide resistrnce to conosion, with or without coaling. Pressure fillers shall be designed for a v/orklng pressure equal to the shut-off head of the pump, with a safety factor of four (4). Vacuum filters shall be designed to withstand the pressiuc developed by the weight of the w'ater contained therein and closed vacuum fillets shall, in addition, be designed to willistand the crushing pressure developed under a vacuum of 2S inches of mercuiy, both with a safely factor of 3.5. In cither type filter wdicre the tank is fabricated from material which is corroded by water, then a suitable corrosion resistant coating shall be applied to retard such attack. The filter dements shall be fabricated of corrosion-resistant materials tliroughout. They shall be designed to be adequately resistant to a differential pressure between influent and effluent of not less than the maximum pressure, wdiich can be developed by the circulating pump and shall be of adequate strength to resist any additional stresses developed during the cleaning operation. The filter septum, upon which the filter-aid cake is deposited, shall be provided willi openings, the minimum dimensions of which shall be not greater than O.OOS inches. P'-ovisions shall be made to introduce filter aid into the filter in such a w'ay as to evenly precoat the filter septum before the filter is placed in