Generate Key TakeawaysA moneyed Upper East Side family is looking to build an indoor pool in the cellar of their posh residence — but their neighbors aren’t exactly having a splash. Plans are in place — but work hasn’t yet begun — to construct a private underground swimming pool on a tony block near Fifth Avenue. Olga Ginzburg for the N.Y. PostThe law allows for a construction project to encroach upon an adjacent property — with proper protections, such as scaffolding and a licensing agreement for access. “Its desire to have an underground swimming pool is causing enormous inconvenience to its directly adjacent neighbors.”Both lawyers declined The Post’s requests for comment. Dueling lawsuits over the pool construction have made for a legal battle on the leafy block.