Secondary Containment Sump sizing

[Althalus]

Folks,

I've got a concrete secondary containment dike for a large tank. We've designed the low point location for sump placement. This sump will only be to provide an obvious low point for suction trucks to go to.

Is there a standard or rule of thumb for the sizing of the sump? 1% of the entire area? 0.25%?

 

[coloeng]

Big enough so that when the suction trucks are removing any spilled product the flow is continuous into the suction truck. If you size it too small, the flow into the sump won't keep up with the flow out.

 

[bimr]

No, there is no standard size. Make it a practical size, maybe 3 ft by 3 ft.

 

[chicopee]

I would size it for a 25 year,24 hour storm as a guess, if the secondary containment is exposed to rainwater.

 

[zelgar]

If this is a RCRA (Hazardous Waste) Tank, the entire secondary containment system should be able to hold the volume of the largest tank plus the volume of the 25-year 24-hour storm event (Note: also address displacment of items in the secondary contatinment system). Most sumps I've seen are fairly small (e.g., 3' x 3' x 3') as they are only sized for small leaks/minor precipitation mainly to facilitate liquid removal as it's easier to remove liquids from a small depression than trying to remove a 1/4" of liquids over the entire containment pad.