Idaho Administrative Code › Title IDAPA 58 - Environmental Quality, Department of › Rule 58.01.08 - IDAHO RULES FOR PUBLIC DRINKING WATER SYSTEMS › Section 58.01.08.535 - FACILITY AND DESIGN STANDARDS: DESIGN STANDARDS FOR IRON AND MANGANESE CONTROL SYSTEMS

Current through August 31, 2023
Iron and manganese control, as used herein, refers solely to
				treatment processes designed specifically for this purpose. The treatment
				process used will depend upon the character of the raw water. The selection of
				one (1) or more treatment processes must meet specific local conditions as
				determined by engineering investigations, including chemical analyses of
				representative samples of water to be treated, and receive the approval of the
				Department. The Department may require a pilot plant study in order to gather
				all information pertinent to the design. See Subsection
				501.19 for general information
				on conducting pilot studies. (3-24-22)
01.
Removal by Oxidation, Detention and
			 Filtration
. (3-24-22)
a. Oxidation may
			 be by aeration or by chemical oxidation with chlorine, potassium permanganate,
			 ozone or chlorine dioxide. (3-24-22)
b. Detention time: (3-24-22)
i. A minimum detention time of thirty (30)
			 minutes shall be provided following aeration to ensure that the oxidation
			 reactions are as complete as possible. This minimum detention may be omitted
			 only where a pilot plant study indicates no need for detention. The detention
			 basin may be designed as a holding tank without provisions for sludge
			 collection but with sufficient baffling to prevent short circuiting.
			 (3-24-22)
ii. Sedimentation basins
			 shall be provided when treating water with high iron or manganese content, or
			 where chemical coagulation is used to reduce the load on the filters.
			 Provisions for sludge removal shall be made. (3-24-22)
c. Filtration. Rapid rate pressure filters
			 are normally used for iron and manganese removal. Pressure filters shall not be
			 used in the filtration of surface or other polluted waters or following
			 lime-soda softening. (3-24-22)
i. The rate of
			 filtration shall not exceed three (3) gallons per minute per square foot of
			 filter area except where in-plant testing as approved by the Department has
			 demonstrated satisfactory results at higher rates. (3-24-22)
ii. The filters shall be designed to provide
			 for: (3-24-22)
(1) Loss of head gauges on the
			 inlet and outlet pipes of each battery of filters. (3-24-22)
(2) An easily readable meter or flow
			 indicator on each battery of filters. (3-24-22)
(3) Filtration and backwashing of each filter
			 individually with an arrangement of piping as simple as possible to accomplish
			 these purposes. (3-24-22)
(4)
			 Minimum side wall shell height of five (5) feet. A corresponding reduction in
			 side wall height is acceptable where proprietary bottoms permit reduction of
			 the gravel depth. (3-24-22)
(5) The
			 top of the wash water collectors to be at least eighteen (18) inches above the
			 surface of the media, (3-24-22)
(6)
			 The underdrain system to efficiently collect the filtered water and to
			 uniformly distribute the backwash water at a rate not less than fifteen (15)
			 gallons per minute per square foot of filter area. (3-24-22)
(7) Backwash flow indicators and controls
			 that are easily readable while operating the control valves.
			 (3-24-22)
(8) An air release valve
			 on the highest point of each filter. (3-24-22)
(9) An accessible manhole to facilitate
			 inspection and repairs for filters thirty-six (36) inches or more in diameter.
			 Sufficient handholds shall be provided for filters less than thirty-six (36)
			 inches in diameter. (3-24-22)
(10)
			 A means to observe the wastewater during backwashing and construction to
			 prevent cross connection. (3-24-22)