Dumpster diving, or the act of scavenging through someone else's trash, is a controversial practice that is legal in some circumstances and illegal in others. In the context of a construction site, whether or not it's legal to dumpster dive depends on a number of factors.

In general, it's not illegal to go through someone else's trash if it's been placed on the curb or in a publicly accessible area. However, if the trash has been placed on private property, such as a construction site, it may be considered trespassing to go through it.

There are also laws that prohibit the theft of items from a dumpster, even if they are considered to be waste. For example, it's illegal to take items from a dumpster if they have been discarded with the intention of being sold or used again.

It's also worth noting that some construction sites may have security measures in place to prevent trespassing and theft. It's important to respect these measures and avoid going through a dumpster on a construction site if you are not authorized to do so.

In summary, whether or not it's legal to dumpster dive at a construction site depends on the specific circumstances and laws of your location. It's generally best to avoid dumpster diving on private property, including construction sites, to avoid potential legal issues.