Abstract: An embedded geometrically variable filter underdrain header and a method for constructing such a filter. Often the variation is a decrease in cross section along the header from the backwash media source, which avoids a pressure loss as liquid is diverted to the laterals along the header. The header is formed inside a filter underdrain basin and is embedded in the basin. The method for constructing the basin and header includes providing a mold for the basin and the header and filling the molds with concrete by pouring concrete into the area between the interior of the mold for the basin and the exterior of the mold for the header. After the concrete cures, the mold for the basin may or may not be removed, while the mold for the header is kept in place.

Abstract: The invention recites a filtration tank including a chamber for holding liquid to be filtered, the filtration tank includes a fluid inlet for providing liquid to the chamber. The filtration tank further includes a fluid outlet and at least one filter block disposed between the inlet and the outlet, wherein the at least one filter block includes a porous cap having an average pore size of up to about 250 microns.

Abstract: The invention recites a filtration tank including a chamber for holding liquid to be filtered, the filtration tank comprising a fluid inlet for providing liquid to the chamber. The filtration tank further includes a fluid outlet and at least one filter block disposed between the inlet and the outlet, wherein the at least one filter block includes a porous cap having an average pore size of up to about 250 microns.

Abstract: A self-regulating tide gate is installed on a conduit connecting an open body of water with a protected body of water. The tide gate comprises a mounting plate secured to the conduit at its end in the open body of water, the mounting plate defining an opening into the conduit. A door has its upper edge pivotally mounted at the top of the conduit, a door float is mounted to the door on its edge opposite the hinged edge and counterfloats are mounted to counterfloat arms extending from the door across the pivot axis thereof. When the water is below a critical level at which it is desired that the door close, the door float maintains the lower edge of the door on the surface of the water, thereby maintaining the door open and blocking debris from jamming the mouth of the conduit. As the water level rises, it acts on the counterfloat to pivot the door towards its closed position, whereafter the door is caught in the flow of water entering the conduit and rapidly pivoted to its closed position.

Abstract: Self-regulating tide gates comprise a door pivotally mounted to the end of a conduit connecting two separated bodies of water. The door is held open to permit full reciprocal flow between a protected one of the bodies of water and the other body of water until the flow would cause an undesirably high water level in the protected body of water. A float senses the water level and releases the door, which then closes a cut off further flow of water. In some embodiments, the door is hingedly connected to the lower edge of the conduit, is buoyant, and is retained in its open position until the float releases it for self-closing. A latching mechanism is employed to hold the door open, or the weight of the float and its connecting float rod accomplish this purpose. In other embodiments, the door is pivotally hinged to the upper edge of the conduit and is provided with counterweights to maintain it in its open position. A float operates against the counterweight to release the door for closing.