• Style & appearance
• Product data
• Design considerations
• Installation & Maintenance

Style & appearance

Photographs

Product photograph

Dimensions (mm)
Diagram
Radii
Rodding Unit	Slit Box Top
Base Uints	Locking/Lifiting Key 40626

Product data

Trafficking

• Urban areas
• City roads
• Car parks

Features and benefits

• Outstanding aesthetics
• Maintains existing kerb line
• Excellent drainage characteristics
• Visual appearance of a traditional kerb
• Three discrete drainage holes
• Fast to lay

Product range dimensions

Radii

Tops and bases for radius units are the same length. To begin laying to a radius, bases must be trimmed so both start at the same point.

Design considerations

Description

The system is comprised of a channel base unit, and a British Standard profile kerb incorporating drainage holes.

Composition and manufacture

Top

Manufactured from South West granites using a wet pressed method. The kerb is then shot blasted to expose the aggregate.

Base

HydroKerb bases are manufactured from high quality quartzite and granite, bound in a resin compound.

Standards

Conforms to EN 1433 Load, Class D.

Specification clauses

Assistance with model specification clauses is available for this product, please refer to Charcon Technical Services.

Colour availability

Standard

Top units

Top units in standard kerb profile and available in a textured finish.
The combination of 914mm kerb and 1000mm channel creates added strength.

Base units

HydroKerb base units are manufactured from polymer concrete.

HydroKerb Silt Box Top

Tested to EN 1433 Class D. Captive hinged and locking (stainless steel cap head bolt).

HydroKerb Rodding Unit

Load tested to category D400 of EN 1433 plus additional 10% ultimate test load.
Captive hinged and locking (stainless steel cap head bolt).
Multi-purpose locking/lifting key available for use with Silt Box and inspection unit.
HydroKerb crossing baseplate available in galvanised steel.

Locking/Lifting Key 40626

General principles

The aim is to ensure prompt and cost effective removal of surface water during and immediately after rainfall.

• Multiple inlet holes system and continuous U-shaped channel profile enables system design
• This can provide a lower cost solution to traditional gully systems

Note: Not suitable for carriageways carrying high volumes of fast flowing heavy vehicles

System capacity

In common with all combined kerb and drainage systems, Hydrokerb units will not run full due to turbulence from the inlet holes. System flow capacities given are, therefore, confined to realistic flow levels rather than theoretical/full bore maximum levels

Design procedure

When the runs to be designed have a longitudinal gradient (i.e. not laid flat) the following procedure may be used.

1. Determine desired run length from drawing.
   Assess area to be drained to run.
   Note location of main sewer.
   
2. Decide on rainfall intensity.
   Usually either 50 mm/hr or 75 mm/hr
3. Calculate gradient based on proposed levels.
   Choose next lower gradient from tables above if not an exact match.
4. Based on catchment width, read off maximum length to outlet
5. Divide length of desired run by value from tables below to give number of outlets required.

Rainfall intensity (50 mm/hr)

Rainfall intensity (75 mm/hr)

Installation design – units

General principles

All units are unreinforced: protect from stresses caused by thermal expansion of cementitious paving materials. Leave 1mm gap between each unit to prevent damage from thermal expansion of the units themselves.

Expansion joints MUST be installed on each side of drainage runs in concrete pavements or those incorporating a cement bound/lean mix concrete roadbase.

DO NOT place these joints directly adjacent to any trafficked unit as this would allow units to rock under trafficking and may allow water ingress into the base or sub-grade.

• Recommended position of joints (minimum distances):
• 600 mm from Clearway/Safeticurb units (see Figs 12-14).
• 125 mm from Highway units (see Figs 5-6).

Note:
As Highway units are not regularly trafficked, expansion joints could be placed directly against them. However, 125 mm distance is recommended to avoid ingress of water between the unit and carriageway construction.

Base foundations

Recommended typical foundations are:

• for Clearway/Safeticurb: minimum 150 mm depth of ST4 concrete with a 25 mm bed of Class 1 mortar (1:3 cement: sand) to allow easy adjustment of units to line and level.
• for Highway: minimum 75 mm of concrete.

Note:
Strength, overall depth and width of the base may need to be increased when laid on low - strength sub-grades.

Haunching

Recommended typical haunches (to within 100 mm of top unit) are:

• For Clearway/Safeticurb: ST4 concrete.
• For Highway: ST1 concrete minimum 125 mm width.

General principles

Details of outlet units an inspection access differ according to which linear drainage system is used.
In any system, silt or detritus should normally be prevented from entering the main drainage sewer. An outfall chamber is required to enable silt collection before onward connection to a sewer.

Types of outfall chamber

• trapped precast concrete, clay or plastic gully pots. Gully pot capacity may be insufficient for some largerlinear drainage installations.
• Purpose-built brick or concrete inspection chamber.
• Precast concrete manhole rings.
• Dedicated sump unit.

Select outfall pipe diameter/gradient

Care should be taken to ensure sufficient capacity.

Highway

Standard outlet formed using two base outlet units (in place of standard base units) to give full width rectangular outlet 400x275 mm. (shallow and deep base outlet units available). Positioning is not critical, but should allow access for suction pipe from gully emptier.

Discharge capacity may be increased by installing more than one pair of Base Outlet units discharging into the same outfall chamber.
For larger schemes, chambers to be detailed in accordance with The Specification for Highway works, clauses 507 and 508. For larger outfall pipes it may be necessary to incorporate a manhole access at rear of run.

Clearway/Safeticurb

Select outfall chamber, pipe dimension and pipe gradient to suit system capacity. Position a silt box top on two courses of engineering brickwork over the selected outfall chamber/silt trap to give access (via the silt box lid) for silt removal.

HydroKerb sump unit

With hinged, removable lid for inspection access, is placed over sump unit in place of standard top units. (See page 143 for alternative option).

Mini Highway sump unit

With hinged, removable lid for inspection access, is placed over inflow unit in place of standard top units.

Radii

Highway/Mini Highway:

• To form external radii of 25 metres or less (minimum 6 m), special radius units should be used (see table below). As these do not cover all individual radius dimensions, some slight gaps are required between units as indicated in Highway radii gap widths table, below.
• For external radii greater than 25 metres, lay straight units with open joints.
• To form internal radii (minimum 6 metres), use 7/6 internal radius units.

Clearway/Safeticurb:

• Where necessary, standard (straight) units may be laid to form radii or bends.
• Safeticurb units: alignment ring within bore acts as a former for infill mortars to seal joint.

Crossings

Highway/Mini Highway:

• Use crossing base units to carry drainage runs under side roads/vehicular crossing points. Grid units available.

Safeticurb (DBK unit only):

• To continue linear drainage at road junctions, kerb crossing points (pedestrian/vehicular), use transition units to reduce kerb height to road level. These connect with standard grid or slot units as necessary.

Junctions/sharp bends

Clearway/Safeticurb:

• Use silt box top at outlets or with suitable uPVC pipe fittings (cut to fit) to form junctions or sharp bends.

Highway radii gaps widths