Roadside drainage
Roadside drainage elements collect stormwater runoff and discharge it to an appropriate location. These systems are an integral part of the planning and design of roads and road infrastructure.
When determining the most appropriate form of roadside drainage, various factors are considered. These include:
- volume of runoff expected
- available space
- environmental impacts
- economic costs
- the landuse zone of the location
Roadside drainage in the Cessnock Local Government Area (LGA)
Older suburbs within the Cessnock LGA were often established without any consideration for drainage. This has resulted in varying forms of drainage throughout the LGA as development progressed.
Roadside drainage elements form a barrier between the road edge and properties. Sufficient roadside drainage prevents water entrance to properties during minor and generally moderate, rainfall events.
Roadside drainage elements are incorporated into the road reserve to facilitate the inception, conveyance and disposal of road surface stormwater runoff. Roadside drainage elements also assist in the preservation of road pavements by reducing excess moisture, which could have negative effects on the integrity of the pavement structure.
While kerb and guttering is often viewed as the best form of drainage, numerous other types of drainage offer similar drainage benefits, while also proving to be more environmentally beneficial. Water sensitive swales are being incorporated into many new developments as they screen pollutants and reduce the sediments entering local watercourses.
Types of roadside drainage in the Cessnock LGA
The various forms of drainage utilised within the Cessnock LGA are outlined within Council’s adopted Roadside Drainage Strategy 2019. These are:
Concrete kerb and gutter
Standard concrete kerb and gutter is found within various streets throughout the Cessnock LGA.
Sandstone kerb and gutter
Sandstone kerb and gutter is heritage listed in various suburbs within the Cessnock LGA. These drainage elements have specific construction and maintenance requirements. The conservation of sandstone kerb and gutter is a priority for Council.
Water sensitive swales
Water sensitive swales are designed in conjunction with structural road edge strips, driveway crossings and stormwater infrastructure. These elements provide drainage and environmental benefits by screening gross pollutants and in turn reducing harm caused to the local rivers and creek.
Wide road – kerb and gutter with a table drain
In locations with a wide verge, kerb and gutter may be constructed at the road pavement edge. A connection to stormwater infrastructure is required in these circumstances. The road pavement edge is often fretted and issues can arise in regards to the flow from the table drain entering properties and affecting road safety.
Wide road – kerb and gutter with grass verge
Wide road verges with concrete kerb and gutter, as well as a grass or earth verge. The road pavement edge is often fretted.
Table drain
Runoff captured and conveyed along a table drain within grass or earth inverts, to a stormwater pit inlet or waterway/flow path. This form of drainage infrastructure is common within the Cessnock LGA.
Table drain and no drainage element
Table drain with no formal road edge. There is no effective capture of runoff along the informal road edge. When the table drain is inundated, runoff may flow across the road and into private property.
No roadside drainage element
Areas where no roadside drainage is present. Stormwater flows along the interface between the pavement and nature strip. This can lead to overland flow into private property on the downslope of the road reserve, particularly during heavy rainfall.
Contributions to kerb and gutter
Under Council’s Development Control Plan (DCP), a developer is required to install kerb and gutter or an appropriate alternative form of drainage.
In areas where kerb and gutter is not currently present, consideration may be given to the installation of new kerb and gutter. This will depend on the current flooding issues, as well as the extent of the flooding risk in comparison to other locations within the Cessnock LGA. If kerb and gutter is the most appropriate form of drainage, property owners are required to contribute to the costs of the kerb and gutter. Under Section 217 of the Roads Act 1993, Council, as the road owner, may charge property owners up to 50% of the cost of kerb and gutter installation. More information is provided in Council’s Contributions for Kerb and Gutter Policy.
Drainage elements for landuse zones
The type of drainage element used is influenced by the landuse zones. The details of this can be found in Council’s Roadside Drainage Strategy 2019. Generally, in rural areas, the most appropriate forms of drainage are water sensitive swales or table drains. Residential areas often have a form of kerb and gutter or alternatively water sensitive swales. The most appropriate form of drainage, for any area, offers drainage and environmental benefits while not taking away from the character of the area. This is particularly relevant in rural locations.
The most appropriate form of roadside drainage is dependent on a number of factors, in particular the landuse zone. Where possible, water sensitive urban design features are to be incorporated into the final solution. The table below provides a summary of the appropriate form of roadside drainage for varying landuse zones. It is clear that various differing forms are acceptable for each location. It may be noted that kerb and gutter is not an acceptable solution in rural areas, while water sensitive swales are suitable in both rural and residential locations.
Drainage usage by landuse zone
Landuse Zone
|
Concrete Kerb and Gutter
|
Sandstone Kerb and Gutter
|
Water Sensitive Swale – with road edge strip
|
Table Drain – no road edge strip
|
Kerb and Gutter with Grass Verge
|
RU2 – Rural Landscape
|
No |
Yes – If heritage listed or present |
Yes |
Yes
|
No |
| RU3 – Forestry |
No |
Yes – If heritage listed or present |
No |
Yes |
No |
| RU4 – Primary Production (small lots) |
No |
Yes – If heritage listed or present |
Yes |
Yes |
No |
| RU5 – Village |
Yes |
Yes – If heritage listed or present |
Yes |
Yes |
Yes |
| R1 – General Residential |
Yes |
Yes – If heritage listed or present |
Yes |
No |
Yes |
| R2 – Low Density Residential |
Yes |
Yes – If heritage listed or present |
Yes |
No |
Yes |
| R3 – Medium Density Residential |
Yes |
Yes – If heritage listed or present |
Yes |
No |
Yes |
| R5 – Large Lot Residential |
No |
Yes – If heritage listed or present |
Yes |
Yes |
Yes |
| B1 – Neighbourhood Centre |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| B2 – Local Centre |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| B3 – Commercial Core |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| B4 – Mixed Use |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| B7 – Business Park |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| IN1 – General Industrial |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| IN2 – Light Industrial |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| IN3 – Heavy Industrial |
Yes |
Yes – If heritage listed or present |
Through a water sensitive urban assessment |
No |
No |
| SP3 – Tourist |
Yes |
Yes – If heritage listed or present |
Yes |
Yes |
Yes |
Community expectation and consultation
Community Satisfaction Research was conducted by Council in 2014, 2016 and 2019 to examine community attitudes and perceptions towards the services and facilities provided by Council. The community maintained the view that kerb and gutter is of high importance and the current performance is unsatisfactory.
Council’s Roadside Drainage Strategy 2019 identified that the cost to install kerb and gutter in locations where it currently does not exist would cost approximately $89 million. Due to this significant cost, other forms of drainage are being utilised throughout the Cessnock LGA.
Council is working to incorporate satisfactory drainage throughout the LGA where funding permits.