Section 82(1)(b) in Assam Notified Urban Areas (Other than Guwahati) Building Rules, 2014
(b)for special building, Group Developments, Multi-storeyed Buildings, Industries and Institutional Building there shall be a pebble bed of 1 metres width and 1.5 metres depth all round the building and filled with rounded pebbles of 5 centimeter to 7.5 centimeter size. The concrete paving around the building has to be sloped at about 1 in 20 towards the pebble bed, so that rain water from the terrace and side open spaces flow over this pavement and spread into the pebble bed around. Dwarf walls in masonry of 7.5 centimeter, height shall be constructed at the entrance and exit gates to retard rainwater collected into the compound from drawing out to the road.