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GrencOr
<br /> Design
<br /> Table A.Recommended Minimum HRTs,Primary Tankage and Configurations
<br /> Application Type Hydraulic Retention Time(HRT) in Days Minimum Volumes&Configurations
<br /> for Primary Tankage
<br /> Grease Tankage' Primary Tankage2 Without Aeration With Aeration
<br /> Type 1, Residential quality waste' n/a 2 2x design max.day flow n/a
<br /> (includes apartments,condos,mobile home parks, (1P+1A)
<br /> municipal, planned communities,subdivisions,work
<br /> camps)
<br /> Type 2, Primarily black water waste'S 3 3 3x design max.day flow n/a
<br /> (includes airport facilities,campgrounds,fire depart- (2P+1A)
<br /> ments,golf courses,marinas,offices,parks,public
<br /> toilets, rest areas, RV parks',ski resorts,visitor
<br /> centers)
<br /> Type 3, Primarily black water waste with surge 3 3 3x design max.day flow n/a
<br /> flows',' (2P+1A with no flow
<br /> (includes churches and schools) equalization)
<br /> 4 4x equalized design day
<br /> flow(2P+1A+10M with
<br /> flow equalization)
<br /> Type 4, Primarily black waster waste with 3^ 4 4x design max.day flow 3x design max.day flow
<br /> pharmaceutical concerns' (3P+1A) (1 P+1A+0.5 AE+0.5 C)
<br /> (includes hospitals, retirement facilities,veterinary
<br /> clinics)
<br /> Type 5, Black water waste and restaurant waste',10 3 n/a 4x design max.day flow 4x design max.day flow
<br /> (includes bars/taverns,casinos,delis,gas stations, (3P+1A) (2P+1A+0.5 AE+0.5 C)
<br /> hotels/motels, restaurants,resorts,shopping cen-
<br /> ters/strip malls)
<br /> Type 6, Polishing bioreactors(includes polishing n/a n/a n/a n/a
<br /> bioreactors for organic or ammonia removal,e.g.
<br /> lagoon compliance)
<br /> Type 7, High-strength process waste10 n/a n/a n/a 4.5x design max.day flow
<br /> (includes wineries,breweries,dairy or food process- (2P+1A+1AE+0.5C)
<br /> ing facilities,slaughterhouses)
<br /> All other applications Contact Orenco for support with application types having characteristics not listed in this chart.
<br /> Key: P=Primary TankageA=Pre-Anoxic AE=Aeration Tankage C=Clarification Tankage EQ=Equalization Tankage
<br /> HRT is based on a separate kitchen design maximum day flow,integrated into the main flow prior to the primary septic tanks.Orenco recommends a grease tank for any facility with a commercial kitchen.Addi-
<br /> tional grease tankage provides increased reduction of organics,as well as separation of grease and oil(G&0)prior to secondary treatment.G&O concentrations entering secondary treatment should be limited
<br /> to 25 mg/L.Chemical disinfection dishwashers can cause significant downstream problems due to the high volumes of sanitizing compounds and emulsifiers and should not be used in onsite treatment and soil
<br /> dispersal applications.
<br /> Z HRT is based on the sum of the Design Maximum Day Flows from all sources.This assumes each waste source has a separate primary tank and a watertight collection system.For systems using gravity collec-
<br /> tion to a single primary tank,add 1 day HRT(based on Design Maximum Day Flow).For grinder or vacuum collection systems feeding into primary tankage,the recommended volume for pre-anoxic tankage is
<br /> 1.5 days HRT;the recommended volume for primary tankage is 2.5 days HRT for a total HRT of 4 days(based on Design Maximum Day Flow).
<br /> a Communities with gravity sewers should review 12+months of documented wastewater flows to determine Design Maximum Day Flow.
<br /> "For systems with cafeteria or restaurant facilities,use the grease tankage listed.
<br /> e RV dump stations should have a minimum 7 days of storage;flow should be blended into the balance of the waste stream throughout the course of the day by timer-controlled pumps.Dump station flow contribu-
<br /> tions should not exceed 20%of the design maximum day flow.
<br /> s Flow equalization is strongly recommended for this application type to reduce the total treatment area required.If flow equalization is not used,base the total primary tankage volume and treatment area on Design
<br /> Maximum Day Flow.
<br /> If using flow equalization for this application type,base the total primary tankage on Equalized Design Day Flow(EDDF)to secondary treatment.EDDF=total weekly flow divided by 6,allowing 1 day for recovery.
<br /> e To reduce septage pumping in these and other specialized applications,we recommend using multiple tanks:The first should be small(0.5 to 0.75 day HRT);subsequent tanks should provide the remaining HRT
<br /> requirements.
<br /> 9 For facilities with restrooms and kitchen,the primary tank volume is determined by summing the design maximum day flows of the restrooms and kitchen—and then multiplying by the HRT value in the primary
<br /> tankage column.Kitchen dishwashing appliances should be high-temperature disinfection models only;low-temperature chemical disinfection dishwashers are not recommended.
<br /> 10 Pre-treatment(e.g.,aeration)is necessary for this application type to reduce overall influent organic waste strength.
<br /> NDA-ATX-1 Orenco Systems®•800-348-9843•+1 541-459-4449•www.orenco.com
<br /> Rev.8,©10/20
<br /> Page 22 of 38
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