NR 811.39(2)(f)3.c.c. A chemical feed pump discharging without any air gap or break box may be approved by the department on a case-by-case basis if the installation is provided with a spring opposed diaphragm type anti-siphon and back pressure valve device. The back pressure valve shall be installed as close as possible to the point of chemical addition. The spring opposed diaphragm type anti-siphon and back pressure valve device shall be installed in accordance with the requirements of par. (e) 1.

NR 811.39(2)(g)(g) Makeup water lines. The makeup water supply lines to chemical feed tanks shall be protected from contamination by chemical solutions either by equipping the supply line with backflow or backsiphonage prevention devices, or by providing an air gap between the supply line and the top of the solution tank.

NR 811.39(2)(h)(h) Chemical resistance. Materials and surfaces coming in contact with chemicals shall be resistant to the aggressiveness of the chemical solution.

NR 811.39(2)(i)(i) Dry chemical feeders. Dry chemical feeders shall meet the following requirements:

NR 811.39(2)(i)2.2. Provide effective dissolving and mixing of the chemical in the solution pot and provide gravity feed from solution pots, if possible.

NR 811.39(2)(j)(j) Direct sewer connections prohibited. No direct connection shall be made between any sanitary or storm sewer and a drain or overflow from any feeder or solution chamber or tank.

NR 811.39(3)(a)(a) Be located near points of application to minimize length of feed lines.

NR 811.39(3)(b)(b) Be readily accessible for servicing or repair and observation of operation.

NR 811.39(3)(c)(c) Be located and have protective containment curbs so that chemicals from equipment failure, spillage, or accidental drainage may not enter the water in conduits, treatment, or storage basins.

NR 811.39(3)(d)(d) Be located within a containment basin capable of receiving accidental spills, drainage, or overflows without an uncontrolled discharge outside of the containment basin. At minimum, the containment basin shall be sized to contain the volume of the largest tank that could fail. Chemical containment basins shall not be provided with floor drains. Trapped and vented floor drains discharging to sanitary sewers, holding tanks, or the ground surface in accordance with s. NR 811.25 (1) (h) may be installed for chemical rooms outside of containment basins. Chemical feed pumps shall be located within the containment basin. Piping shall be designed to minimize or contain chemical spills in the event of pipe ruptures.

NR 811.39(3)(e)(e) Be located above grade, except if this requirement is waived by the department.

NR 811.39(3)(f)(f) Be located in accordance with s. NR 811.48 (5) if gas chlorine feeders are used.

NR 811.39(3)(g)(g) Be located in accordance with s. NR 811.51 (2) if fluorosilicic acid is used.

NR 811.39(4)(a)(a) Feeders may be manually or automatically controlled if the water supply pumps are manually controlled. Where pumps are automatically controlled, the feeders shall be automatically controlled. In all cases, automatic control shall be capable of reverting to manual control when necessary.

NR 811.39(4)(b)(b) The operation of the chemical feed pumps shall be interlocked with the operation of the appropriate well or service pump. Any controlled electrical outlet used for any chemical feed pump shall be clearly marked.

NR 811.39(4)(c)(c) Secondary control of chemical feed equipment shall be provided for fluoride chemical feed equipment in accordance with s. NR 811.51 (4) or when required by the department.

NR 811.39(4)(d)(d) Feeders shall be designed and controlled to provide chemical feed rates proportional to flow and for variable flow rates shall be paced by a water meter.

NR 811.39(4)(e)(e) Automatic chemical feed rate control in combination with residual analyzers which have alarms for critical values and SCADA system reporting or recording charts may be used.

NR 811.39(6)(6) Chemical use measurement. The determination of chemical usage when using chemical feeders shall meet all of the following requirements:

NR 811.39(6)(a)(a) Weighing scales shall be provided for weighing cylinders at all plants utilizing chlorine gas.

NR 811.39(6)(b)(b) Weighing scales are required for liquid solution feed unless comparable means for determining usage is approved by the department.