I need a mechanical engineer

I am adding 3 sinks to a commercial location( please see attatched, shows where I would like the sinks). I have a plumber and he said we need to create 2 drainage holes which will connect to pipes leading to the underground parking. The mechanical drawings are needed by strata for approval. I only need to add plumbing. It should be Fairly easy/straightforward. I can also provide other previous drawings upon request and link you with my plumber if necessary. I require someone who can get started right away as I am behind. Please give me a quotation. Thank you!