Since you are the second underground, I suggest you consider this, -1F commercial if there is drainage, such as supermarket fresh, catering kitchen, etc., consider the structure of the lowering plate to do the ditch, pooling to -2F drainage, -2F can be done in a room as a grease trap room. -1F of the parking lot ground drainage, you can consider the floor drain collection, to -2F discharge, discharge into the -2F catchment wells, -1F of the bathroom drains in the top of the -2F, directly to the -2F discharge, you can make a room to place the sewage catchment wells, remember to close the lid, placed in the odor overflow. -2F floor drainage can be two practices, according to my experience, because you since -2F, certainly the structure of the floor plate thickness is relatively thick, you can consider the use of floor drains to take over the introduction of the way to the catchment wells (need to pay attention to the drain buried in the floor between the upper and lower reinforcement, according to the specification to take the gradient), or the use of guttering is also available.