Is it permissible to dig a pit for sewage (blackwater) on a waqf (endowment) land?

The waqf (endowment) must remain as it is, and its administration must adhere to the conditions set by the endower, provided they are just and fair. It is impermissible to dispose of it in a way that contradicts its benefit or the endower's conditions. Thus, if digging sewers in the waqf land is for its benefit, then there is no objection to it. If it is not for its benefit, then it is impermissible.