Where surface water drainage is provided for roads it shall consist of piped drainage. Where practicable drainage work shall be completed before road works is commenced. 

Trenches for piped drainage shall be excavated to the minimum dimensions necessary for the proper construction of the Works, and after pipes have been laid, tested and, where specified, surrounded with gravel or concrete, the trenches shall be backfilled with excavated material and compacted to a dry density equal to that of the adjacent ground. Surplus excavated material shall be disposed of offsite. 

Porous pipes shall be laid dry-jointed and shall be surrounded with gravel. 

Soak-away ponds and in-situ concrete catch pits with kerb weirs shall be constructed 

Brickwork manholes and gullies shall be constructed complete with cast iron covers or gully gratings. 

Open drainage channels for roads shall be constructed as concrete channels with a width up to 1 m and a depth up to 0.5 m. The bottom of the trench and the lower part of the slopes (1/3 of the total depth) shall receive stone pitching as described in the herewith Employer’s Requirements. The works to be carried out shall include the required excavation, the trimming, compaction and pitching of surfaces and site clearance after completion of the works. 

## 10.1.16 Laying kerbs and channels 

Kerbs, edgings, channels and quadrants shall be laid and bedded on a layer of mortar, either on the concrete carriageway or on a Grade C20/25 concrete foundation. They shall be butt-jointed except where otherwise described in the Contract, save that where laid on concrete carriageways they shall be provided with joints coincident with the carriageway movement joints, of width and with filler identical to that used in the carriageway joints. All kerbs shall be backed with Grade C20/25 concrete. 

Alignment of kerbs and channels shall not deviate from that described in the Contract by more than 10 mm, with no lipping of visible faces. 

## 10.1.17 Foundations for walkways 

Foundations for footways shall consist of granular sub-base material spread evenly and compacted in layers of not more than 100 mm thickness. 

Compaction to the correct levels shall be carried out using a vibratory roller have a static load of at least 1000 kg/m width of roll. 

## 10.1.18 Laying concrete paving flags 

Pre-cast concrete flags shall be laid to falls on sub-base material, bonded with joints at right angles to the kerb, and spot bedded with mortar with no lipping of top surfaces. 

Flags shall be cut to fit around surface boxes and other furniture and, on circular work where the radius is 12m or less, shall be radially cut on both edges to the required lines. 

## 10.1.19 Laying paving blocks 

Pre-cast concrete block paving shall be used. 

## 10.1.20 Tolerances for finished carriageway surfaces 

Finished surfaces at each stage of road construction shall not vary from the levels described in the Contract by more than the following permissible deviations: 

