Montana DEQ - Circular DEQ 2 - Design Standards for ... - Force Flow
Montana DEQ - Circular DEQ 2 - Design Standards for ... - Force Flow Montana DEQ - Circular DEQ 2 - Design Standards for ... - Force Flow
Supplemental Treatment Process Chapter 110111.53 CleaningConsideration must be given to the accessibility of piping. Piping shouldbe installed with plugged wyes, tees or crosses with removable plugs atchanges in direction to facilitate cleaning.111.54 Filling Drains and Draw-offAbove-bottom draw off from chemical storage or feed tanks must beprovided to avoid withdrawal of settled solids into the feed system. Abottom drain must also be installed for periodic removal of accumulatedsettled solids. Provisions must be made in the fill lines to prevent backsiphonage of chemical tank contents.111.6 Safety and Hazardous Chemical HandlingThe Chemical handling facilities must meet the appropriate safety and hazardoushandling facilities requirements of Section 57.111.7 Sludge HandlingConsideration must be given to the type and additional capacity of the sludgehandling facilities needed when chemicals are added. Design of dewatering systemsshould be based, where possible, on an analysis of the characteristics of the sludgeto be handled. Consideration should be given to the ease of operation, effect ofrecycle streams generated, production rate, moisture content, dewaterability, finaldisposal, and operating costs. Refer to Chapter 80.112. HIGH RATE EFFLUENT FILTRATION112.1 General112.11 ApplicabilityGranular media filters may be used as an advanced treatment device for theremoval of residual suspended solids from secondary effluents. Filters maybe necessary where effluent concentrations of less than 20 mg/L ofsuspended solids and/or 1.0 mg/L of phosphorus must be achieved. A pretreatmentprocess such as chemical coagulation and sedimentation or otheracceptable process should precede the filter units where effluent suspendedsolids requirements are less than 10 mg/L.157
Chapter 110Supplemental Treatment Process112.12 Design Considerations112.2 Filter TypesCare should be given in designing pipes or conduits ahead of filter units, ifapplicable, to minimize shearing of floc particles. Consideration should begiven in the plant design to providing flow-equalization facilities tomoderate filter influent quality and quantity.Filters may be of the gravity type or pressure type. Pressure filters must beprovided with ready and convenient access to the media for inspection or cleaning.Where abnormal quantities of greases or similar solids, which result in filterplugging are expected, filters should be of the gravity type.112.3 Filtration Rates112.31 Allowable RatesFiltration rates may not exceed 5 gpm/sq. ft. (3.40 l/m 2 s) based on thedesign peak hourly flow rate applied to the filter units. The expected designmaximum suspended solids loading to the filter should also be consideredin determining the necessary filter area.112.32 Number of Units112.4 BackwashTotal filter area must be provided in two or more units, and the filtrationrate must be calculated based on the total available filter area with one unitout of service.112.41 Backwash RateThe backwash rate must be adequate to fluidize and expand each medialayer a minimum of 20 percent based on the media selected. The backwashsystem must be capable of providing variable backwash rates. Minimumand maximum backwash rates must be based on demonstrated satisfactoryfield experience under similar conditions. The design must provide for abackwash period of at least 10 minutes.112.42 Backwash PumpsPumps for back-washing filter units must be sized and interconnected toprovide the required backwash rate to any filter with the largest pump outof service. Filtered water from the clear well or chlorine tank must be usedas the source of backwash water. Waste filter backwash must beadequately treated.158
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Supplemental Treatment Process Chapter 110111.53 CleaningConsideration must be given to the accessibility of piping. Piping shouldbe installed with plugged wyes, tees or crosses with removable plugs atchanges in direction to facilitate cleaning.111.54 Filling Drains and Draw-offAbove-bottom draw off from chemical storage or feed tanks must beprovided to avoid withdrawal of settled solids into the feed system. Abottom drain must also be installed <strong>for</strong> periodic removal of accumulatedsettled solids. Provisions must be made in the fill lines to prevent backsiphonage of chemical tank contents.111.6 Safety and Hazardous Chemical HandlingThe Chemical handling facilities must meet the appropriate safety and hazardoushandling facilities requirements of Section 57.111.7 Sludge HandlingConsideration must be given to the type and additional capacity of the sludgehandling facilities needed when chemicals are added. <strong>Design</strong> of dewatering systemsshould be based, where possible, on an analysis of the characteristics of the sludgeto be handled. Consideration should be given to the ease of operation, effect ofrecycle streams generated, production rate, moisture content, dewaterability, finaldisposal, and operating costs. Refer to Chapter 80.112. HIGH RATE EFFLUENT FILTRATION112.1 General112.11 ApplicabilityGranular media filters may be used as an advanced treatment device <strong>for</strong> theremoval of residual suspended solids from secondary effluents. Filters maybe necessary where effluent concentrations of less than 20 mg/L ofsuspended solids and/or 1.0 mg/L of phosphorus must be achieved. A pretreatmentprocess such as chemical coagulation and sedimentation or otheracceptable process should precede the filter units where effluent suspendedsolids requirements are less than 10 mg/L.157
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