Section 82(3)(a) in Assam Notified Urban Areas (Other than Guwahati) Building Rules, 2014
(a)Percolation Pits:- The paved surface around the building shall have percolation pits of 1.2m x 1.2m x 1.2m covering at least 30% of such area. Such pits shall be filled with small pebbles or brick jelly or river sand and covered with perforated concrete slabs;