NR 811.39(2)(a)3.a.a. Where multiple water sources are discharging to the same location. In this case, a means shall be provided for determining the flow from each individual water source.

NR 811.39(2)(a)3.b.b. Where multiple pumps are pumping from the same water source and discharging to the same location through a combined header pipe. In this case, a means shall be provided for measuring total flow.

NR 811.39(2)(a)3.c.c. For the situations in subd. 3. a. and b., a single chemical feeder with a single feed point or multiple chemical feeders with multiple feed points may be used, provided the installation meets the other requirements of this subchapter.

NR 811.39 NoteNote: An example of subd. 3. a. would be multiple wells discharging to a single reservoir or water treatment plant. An example of subd. 3. b. would be multiple high-lift pumps taking suction from a single reservoir and discharging to a combined pump discharge pipe.

NR 811.39(2)(b)(b) Acceptable chemical feed pumps. Positive displacement diaphragm metering pumps, peristaltic chemical feed pumps or other pumps, as approved by the department, shall be used to feed liquid chemicals. Pumps shall be sized to match or exceed maximum head conditions found at the point of injection.

NR 811.39(2)(c)(c) Chemical feeder settings. Feeders shall be able to supply, at all times, the necessary amounts of chemical at an accurate rate, throughout the range of feed. All positive displacement diaphragm metering pumps shall be operated at a minimum speed setting of 12 strokes per minute. For positive displacement diaphragm metering pumps with an adjustable stroke length the pumps shall be operated at a minimum of 20 percent of the maximum stroke length. Peristaltic chemical feed pumps shall be operated at a minimum of 10 percent of the maximum feeder output for the given interior diameter of the feed tube installed. If these operating requirements cannot be met using stock chemical solution, dilution of the chemical shall be required.

NR 811.39(2)(d)(d) Flow paced chemical feed. Automatic proportioning of chemical feed to rate of water flow shall be provided when water flow rates will vary. Chemical feed pumps shall be proportionally flow paced by a signal from a water meter when discharge rates from a well or service pump will be variable over the pump cycle. When applicable, this includes variable output control devices as required by s. NR 811.34 (5).

NR 811.39(2)(e)1.1. All electronic positive displacement diaphragm metering pumps shall be provided with a spring-opposed diaphragm type anti-siphon device or a spring opposed diaphragm type anti-siphon and back pressure valve device installed in the discharge piping of the chemical feed pump. The anti-siphon and back pressure functions may be part of a common device or separate devices. Any back pressure valve shall be set to open at a pressure greater than the maximum pressure in the piping or facilities into which the chemical feed pump will discharge. When a back pressure valve is installed on the discharge piping of a chemical feed pump, it shall be preceded by a pressure relief valve and a pressure gauge or other department approved means to verify that the back pressure valve is operating satisfactory.

NR 811.39(2)(e)3.3. Peristaltic chemical feed pumps shall be provided with a back pressure valve device installed in the discharge piping of the chemical feed pump in accordance with the requirements under subd. 1. The department may allow exceptions to the requirements under subd. 1. for peristaltic chemical feed pumps when the installation meets all of the following requirements:

NR 811.39(2)(e)4.4. The department may be contacted to request approval of an equivalent anti-siphon device or equivalent means of providing anti-siphon protection if the installation of the anti-siphon devices as required in subds. 1. to 3. is not practical given the properties of the chemical to be fed. Adequate justification shall be provided to the department for the request.

NR 811.39(2)(f)1.1. Chemical solutions shall be prevented from being siphoned into the water supply. Anti-siphon protection shall be provided by discharging chemicals at points of positive pressure and by providing anti-siphon devices in accordance with par. (e), or through a suitable air gap or other effective means approved by the department.

NR 811.39(2)(f)2.2. All chemicals shall be fed downstream of the check valve. Strong acids and bases such as fluorosilicic acid and sodium hydroxide shall be fed downstream of both the check valve and the shut-off valve.

NR 811.39 NoteNote: It is recommended that all chemicals be fed downstream of both the check valve and the shutoff valve. If a second shut-off valve is provided downstream of the primary shut-off valve, the point of injection may be between the 2 shut-off valves.

NR 811.39(2)(f)3.3. If chemical feeding is at a location without continuous positive pressure, one of the following installation requirements shall be met to prevent siphoning of chemical solutions:

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.