IS 4111:2000 (Part 2) is the Indian Standard (BIS) for ancillary structures in the sewerage system, part ii: flushing tanks. This code outlines the criteria for the planning, design, construction, and maintenance of tidal outfalls for discharging treated or partially treated sewage into marine environments. It covers essential hydrographic investigations, dilution modeling, hydraulic sizing, and structural stability against oceanographic forces.
Code of practice for ancillary structures in the sewerage system, Part II: Flushing tanks
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Minimum internal diameter (Normal manhole) | 900 mm for rectangular manholes; 1200 mm diameter for circular manholes. | 1000 mm or 1200 mm depending on number of connections and local practice. | BS EN 752:2017 |
| Maximum spacing on straight sewer runs (for pipe dia. 300-500 mm) | 45 metres | Generally up to 100 m; can be extended based on risk assessment and cleaning technology. | BS EN 752:2017 |
| Benching Slope | Sloped towards the channel at about 1 in 6. | Sloped between 1:10 and 1:20 to ensure self-cleansing while allowing safe footing. | WSA 02-2014-3.1 |
| Vertical spacing of step irons | 300 mm centre to centre. | Typically 250 mm to 300 mm, complying with specific product standards like EN 13101. | BS EN 1917:2002 |
| Minimum clear opening of manhole cover | 560 mm for normal duty; 600 mm for heavy duty. | Minimum 600 mm clear opening is standard for personnel access. | BS EN 124-1:2015 |
| Water Tightness Test (Hydrostatic) | Head of 2.5 m of water above invert, held for a specified duration. | Fill with water to ground level, or minimum 1m above pipe crown or groundwater level (whichever is higher), for a specified duration. | BS EN 1610:1997 (referenced for systems) |
| Minimum shaft access diameter (Deep manhole) | 750 mm clear circular opening. | 600 mm is a minimum, but 750 mm is recommended for frequent entry or equipment. | WSA 02-2014-3.1 |