ABSTRACT
Large chambers: To have either tapered reducing rings or a flat reducing slab in order to accept the standard cover
Ring depths: 1. 300-1200mm by 300mm increments except for bottom slab and rings below cover slab, these are by 150mm increments
2. 250-1000mm by 250mm increments except for bottom slab and rings below cover slab, these are by 125mm increments
Access hole: 750 × 750mm for DN 1050 chamber 1200 × 675mm for DN 1350 chamber
Area m2 50 100 150 200 300 400 500
Ring size
0.9 1.31 2.62 3.93 5.24 7.86 10.48 13.10 1.1 0.96 1.92 2.89 3.85 5.77 7.70 9.62 1.2 0.74 1.47 2.21 2.95 4.42 5.89 7.37 1.4 0.58 1.16 1.75 2.33 3.49 4.66 5.82 1.5 0.47 0.94 1.41 1.89 2.83 3.77 4.72 1.8 0.33 0.65 0.98 1.31 1.96 2.62 3.27 2.1 0.24 0.48 0.72 0.96 1.44 1.92 2.41 2.4 0.18 0.37 0.55 0.74 1.11 1.47 1.84 2.7 0.15 0.29 0.44 0.58 0.87 1.16 1.46 3.0 0.12 0.24 0.35 0.47 0.71 0.94 1.18
Nominal sizes: 375 diameter, 750, 900mm deep 450 diameter, 750, 900, 1050, 1200mm deep
Depths: from the top for trapped or un-trapped units: centre of outlet 300mm invert (bottom) of the outlet pipe 400mm
Depth of water seal for trapped gullies: 85mm, rodding eye int. dia. 100mm
Cover slab: 65mm min
Type 1 = 100mm fill below pipe, 300mm above pipe: single size material Type 2 = 100mm fill below pipe, 300mm above pipe: single size or graded material Type 3 = 100mm fill below pipe, 75mm above pipe with concrete protective slab over Type 4 = 100mm fill below pipe, fill laid level with top of pipe Type 5 = 200mm fill below pipe, fill laid level with top of pipe Concrete = 25mm sand blinding to bottom of trench, pipe supported on chocks,100mm concrete under the
pipe, 150mm concrete over the pipe
Class D: Pipe laid on natural ground with cut-outs for joints, soil screened to remove stones over 40mm and returned over pipe to 150m min depth. Suitable for firm ground with trenches trimmed by hand.
