Abstract: The talk deals with the problem of locating a maximal cardinality set of obnoxious facilities within a bounded rectangle in the plane such that their pairwise L_inf-distance as well as the L_inf-distance to a set of already placed demand sites is above a given threshold. We employ techniques and methods from computational geometry to design an optimization algorithm and an efficient 12-approximation algorithm for the problem, and employ the optimization algorithm to design a PTAS based on the shifting strategy of Hochbaum and Maass for geometry problems. As a byproduct we improve the algorithm for placing obnoxious facilities of Katz et al. [Improved algorithms for placing undesirable facilities. Computers & Operations Research, 2002, 29:1859-1872].