Pool construction plans - do I need a Landscape Architect?

We are working with a Landscape architect to prepare a master design for our backyard patio and pool area. It will be a 25,000 gallon free form pool with spa, waterfalls and vanishing edge and surrounding 20' patio of bluestone, natural stone slab steps and recommended lighting and plantings. The landscape architect has worked with us to come up with a beautiful final design sketch. He now wants to prepare the pool construction plans for pool builder bidding. The plans will be a significant further expense and I thought the transfer of his sketch to pool construction plans would be the job of the builder not the landscape architect. There will be some re-grading of the area and I know we need some construction details for all of the masonary work but should he be doing the pool plans (plumbing as well) or am i just throwing away money this way?