15
E/One Grinder Pump Station Ballast Calculations
Sample Calculation, DH502/DR502
Volume of Station Wet Well = 91.3 cu ft
Station Weight = 845 lb
Station Height = 103.3”
A. Buoyant Force
1. The buoyant force acting on the submerged DH502 is equal to the weight of the displaced
water for the section of the tank that is submerged (wet well).
F
buoyant
= (density of water)(volume of DH502-104 wet well)
= (62.4 lb/cu. ft)(91.3 cu. ft)
= 5697.1 lb
2. The net buoyant force acting on the station (F
net-buoyant
) is equal to the buoyant force (F
buoyant
)
minus the weight of the grinder pump station.
F
net-buoyant
= 5697.1 lb – 845 lb
= 4852.1 lb
B. Ballast Force
1. Determine the volume of concrete (if applicable) & soil (saturated and dry)
Section I: Used To Determine The Volume Of Dry Soil
Area =(Height)(Width) +(Trapezoidal Area) + (Top Area)
= (47.5”)(3.8”) + (1/2)(20” + 47.5”)(18.7”) +(27.2”)(13.4”)
=
1176.1in
2
Volume = (Area)(Average Perimeter of the cylinder)
=
(1176.1in
2
)(2
π
)(26.8”)
= (249199.4 in
3
)(1/1728 ft
3
/in
3
)
= 114.6 ft
3
2. Determine the combined ballast
Ballast (total) = Ballast (dry soil)
=
(V
soil
)(density dry soil)
= (114.6 cu ft)(110 lb/ft
3
)
= 12606.0 lb
