Water main crossing insulation practices 1

[ErHen]

First post!

I'm curious what standards/best practices are for when to install direct bury insulation over water mains that cross storm/sanitary pipe. In MN we have a minimum 7.5 of cover for frost protection and the typical standards of 18" separation with pipe crossings. But when a 6-10" WM crosses under storm structures or storm pipe subject to open air conditions, what is a good rule of thumb to add the direct bury insulation (our specs require 4" thick insulation). I'd think it's good practice at 18" separation to have the insulation, but when is it OK not to require the insulation?

Any insights are appreciated.

 

[CarlB]

Anchorage, Alaska standards require 10 feet cover over water lines for frost protection, and 4" board insulation at crossings when separation between water & storm/culvert is less than 4 feet. So in your slightly warmer climate, maybe insulate if less than 3 feet separation? Actual need depends on storm drain pipe size, air flow conditions, depth of pipe, etc.

 

[bimr]

It would depend on the climatic conditions, wouldn't it?