how to find utilities hook up location on a developed lot

[Amrendra Kumar]

Hi guys,
I am buying a developed lot(all the utilities hook-ups are present on the site). The seller who happened to be developer for the land is is telling me, he does not have map locating all the utilities hook-ups. He did give me map showing storm sewer placement.
Can any one tell me how do I find out the hook-ups for all other utilities?

Thank you

Kumar