19-074-CALCS-STEP Tank Sizing-2025.01.09Deutscher - Yelm Commercial
STEP Sewer Tank Sizing Calculation
1/9/2025
Typical Unit Flow Rates:15 gpd/employee
12 Employees/day 180 gpd
Minimum Liquid Volume = 2 x peak day flow (per DOE Orange Book C1-10.1.5)
Peak Daily Flow = 180 gallons
Minimum Liquid Volume = 360 gallons
Working Volume must exceed the difference between the peak influent flow and discharge of the pump over the peak duration
Assumed Peak Duration = 15 minutes
Assumed Peak Inflow = QDesign * ((18 + sqrt(P))/(4 + sqrt(P))) where P = Population in Thousands
= (180 gpd) * (18 +sqrt(0.012)/(4 + sqrt(0.012)) / 24hrs/day = 33 gallons/hour = 0.6 gpm
Assumed Peak Discharge = 10 gpm for P.10 0511 OSI Pump
Peak Discharge > Peak Inflow ----> Okay
Working Volume = 0 gallons
Storage Volume shall equal 24 hours of Peak Daily Infow for emergency storage
Storage Volume = 180 gallons
Sum of Liquid Detention Volume, Working Volume, and Storage Volume. Liquid Detention Volume not to exceed 65% to 75% of total Volume.
Liquid Detention Volume = 360 gallons 67%
Working Volume = - gallons 0%
Storage Volume = 180 gallons 33%
Total Volume =540 gallons 100%
1,000 gallon Tank
Total tank volume required:
Building 1 (Retail Site)
Sizing per Criteria for Sewage Works Design (DOE Orange Book), Section C1-10.1.5.
Liquid Detention Volume:
Working Volume:
Storage Volume:
1
01/09/2025
Deutscher - Yelm Commercial
STEP Sewer Tank Sizing Calculation
1/9/2025
Typical Unit Flow Rates:15 gpd/employee
12 Employees/day 180 gpd
Minimum Liquid Volume = 2 x peak day flow (per DOE Orange Book C1-10.1.5)
Peak Daily Flow = 180 gallons
Minimum Liquid Volume = 360 gallons
Working Volume must exceed the difference between the peak influent flow and discharge of the pump over the peak duration
Assumed Peak Duration = 15 minutes
Assumed Peak Inflow = QDesign * ((18 + sqrt(P))/(4 + sqrt(P))) where P = Population in Thousands
= (180 gpd) * (18 +sqrt(0.012)/(4 + sqrt(0.012)) / 24hrs/day = 33 gallons/hour = 0.6 gpm
Assumed Peak Discharge = 10 gpm for P.10 0511 OSI Pump
Peak Discharge > Peak Inflow ----> Okay
Working Volume = 0 gallons
Storage Volume shall equal 24 hours of Peak Daily Infow for emergency storage
Storage Volume = 180 gallons
Sum of Liquid Detention Volume, Working Volume, and Storage Volume. Liquid Detention Volume not to exceed 65% to 75% of total Volume.
Liquid Detention Volume = 360 gallons 67%
Working Volume = - gallons 0%
Storage Volume = 180 gallons 33%
Total Volume =540 gallons 100%
1,000 gallon Tank
Total tank volume required:
Building 2 (Retail Site)
Sizing per Criteria for Sewage Works Design (DOE Orange Book), Section C1-10.1.5.
Liquid Detention Volume:
Working Volume:
Storage Volume:
2
01/09/2025
Deutscher - Yelm Commercial
STEP Sewer Tank Sizing Calculation
1/9/2025
Typical Unit Flow Rates:15 gpd/employee
50 gpd/Seat
10 Employees/day & 35 Seats 1900 gpd
Minimum Liquid Volume = 2 x peak day flow (per DOE Orange Book C1-10.1.5)
Peak Daily Flow = 1,900 gallons
Minimum Liquid Volume = 3,800 gallons
Working Volume must exceed the difference between the peak influent flow and discharge of the pump over the peak duration
Assumed Peak Duration = 15 minutes
Assumed Peak Inflow = QDesign * ((18 + sqrt(P))/(4 + sqrt(P))) where P = Population in Thousands
= (1,900 gpd) * (18 +sqrt(0.045))/(4 + sqrt(0.045)) / 24hrs/day = 342 gallons/hour = 5.7 gpm
Assumed Peak Discharge = 10 gpm for P.10 0511 OSI Pump
Peak Discharge > Peak Inflow ----> Okay
Working Volume = 0 gallons
Storage Volume shall equal 24 hours of Peak Daily Infow for emergency storage
Storage Volume = 1,900 gallons
Sum of Liquid Detention Volume, Working Volume, and Storage Volume. Liquid Detention Volume not to exceed 65% to 75% of total Volume.
Liquid Detention Volume = 3,800 gallons 67%
Working Volume = - gallons 0%
Storage Volume = 1,900 gallons 33%
Total Volume =5,700 gallons 100%
6,000 gallon Tank
Building 3 (Restaurant)
Liquid Detention Volume:
Working Volume:
Storage Volume:
Total tank volume required:
Sizing per Criteria for Sewage Works Design (DOE Orange Book), Section C1-10.1.5.
3
01/09/2025