Study sites were selected in the Gold Coast region, South East Queensland, Australia. The Gold Coast region is currently subjected to significant urban development providing an appreciable variation in stormwater pollutant sources. Four suburbs from the Gold Coast namely, Surfers Paradise, Benowa, Nerang and Clearview Estate were selected for this study as shown in Figure 4-1. These four suburbs are situated in close proximity to the Nerang River from downstream to upstream, respectively.
Figure 4-1 Map of the selected sites
The selected four suburbs represent different land use characteristics such as commercial, industrial and residential. Differences in soil characteristics were also expected as the suburbs stretch from the coastline to inland. Four different road sites from each of the four suburbs were selected for investigations so that they represent the different traffic characteristics. Accordingly, it was assumed that the potential variability in road surfaces pollutants due to variations in soil characteristics, land use variations and traffic variations are represented in the site selection.
Table 4-1 provides the details of the selected study sites together with site identification (Site ID), which is used in further discussions. In addition, daily traffic volume, texture depth (a measure of road surface condition), slope of the road section and distances from the coastline to the sampling locations are given in Table 4-1. The slope and the distance from the coastline to the sampling location was measured using Nearmap mapping product (Nearmap, 2014). A 50 m road section across the sampling location was considered in measuring the slope of the road and Figure 4-2 shows an example image of measurement of distance from coastline. The daily
traffic volume given in Table 4-1 was obtained from the Gold Coast City Council. Daily traffic volume in C3, C4, I2, M4, R2 and R4 are actual traffic counts conducted by the City Council whereas the other data given are traffic modelling estimates. It should be noted that traffic modelling estimates are as close as possible to actual traffic in the roads which provide good engineering judgement. Texture depth of the road surface was obtained from Gunawardana (2011) study measured using the sand patch experiment based on ASTM (2006) and FHWA (2005). Brief descriptions of each suburb and selected sites are given in Table 4-1 and further details can be found in Gunawardana (2011).
Table 4-1 Selected study sites
Site name Site
ID Land use Daily traffic volume *Texture depth (mm) Slope % DIS (m) S u rfe rs P ara d ise Hobgen Street C1 C 750 0.9 0.1 1332 St Paul’s Place C2 C 750 0.63 0.2 1107 Thornton Street C3 C 3184 1.11 0.1 243 Via Roma Drive C4 C 1587 0.85 0.1 1098 Ne ra n g Hilldon Court I1 I 3500 0.93 0.4 8992 Lawrence Drive I2 I 6915 1.06 0.2 8424 Patrick Road I3 I 500 1.14 0.4 8896 Steven Street I4 I 500 1.1 8.7 9601 Be n o wa De Haviland Avenue M1 R 500 0.9 0.1 4064 Mediterranean drive M2 C 750 0.82 5.4 4270 Strathaird Road M3 C 3000 0.8 0.1 2901 Village High Road M4 R 1537 0.91 1.8 3539 Clea rv iew Estate Carine Court R1 R 500 0.92 4.8 11639 Merloo Drive R2 R 834 0.76 2.2 12788 Winchester Drive R3 R 750 0.87 1.2 11580 Yarrimbah Drive R4 R 608 0.84 0.4 12251
C: Commercial, I: industrial, R: Residential
* Texture depth were obtained from (Gunawardana, 2011) DIS: Distance from the coastline
Surfers Paradise (commercial land use)
Surfers Paradise is a popular tourist destination in the Gold Coast region as it is situated close to the coastline. Traffic activities within the area are comparatively high due to visitors to the area. Many of the buildings in Surfers Paradise are commercial buildings such as hotels, shops and schools. Hence, this suburb can be categorised as commercial land use. The common type of roadside soil in this area is sandy soil due to the close vicinity to the coastline. All of the selected sites in Surfers Paradise are within 1.5km from the coastline.
Figure 4-2 Distance from the coastline to the sampling point
Four roads from this suburb were selected so that they represent the varying traffic characteristics (see Figure 4-3). The selected sites were:
Hobgen Street (C1)
St Paul’s Place (C2)
Thornton Street (C3)
Via Roma Drive (C4)
Hobgen Street is situated closed to a school and a playground and has parking lots along the road. St Paul’s Place is a residential access road. Relatively light traffic conditions are experienced on Hobgen Street and St Paul’s Place. Thornton Street is the nearest street to the coastline surrounded by hotels and high rise apartments and directly connected to an arterial road. Hence, high traffic flow is experienced on this road (3184).
Via Roma Drive is a major road. Both Hobgen Street and St Paul’s Place are connected to this road. Two traffic signalised intersections exist along this road. All the four roads has fairly flat surface with varying texture depths ranging from 0.63- 1.11 mm (see Table 4-1).
Figure 4-3 Study sites in Surfers Paradise
Benowa (Mixed land use)
Benowa is located west of Surfers Paradise. In this suburb, land use characteristics vary considerably from one location to another. Four sites were selected from this suburb (see Figure 4-4) so that they represent the mixed land use characteristics within the suburb. The selected sites and characteristics of each of the selected roads are given below.
De Havilland Avenue (M1):
Mediterranean Drive (M2):
Strathaird Road (M3):
Village High Road (M4):
De Havilland Avenue is an access road to a residential area with detached family houses and town houses. Mediterranean Drive is an access road to a school and detached family houses and it connects to a major road (Benowa Road). It has a relatively steep slope compared to other roads. Strathaird Road is an access road to a commercial area and located close to a major road (Ashmore Road) and the highest
daily traffic volume among four roads selected is reported on this road. Commercial buildings such as a warehouse, food stores, mechanical workshops and a service station are situated on either side of the road. Village High Road is an access road to a residential area with detached family houses and town houses.
Figure 4-4 Study Sites in Benowa
Nerang (Industrial land use)
Nerang is located next to Benowa to the inland along the Nerang River. The study sites were selected so that they represent the industrial land use characteristics. Following are the sites and their characteristics (Figure 4-5):
Hilldon Court (I1):
Lawrence Drive (I2):
Patrick Road (I3):
Stevens Street (I4):
Hilldon Court is an arterial road with access to several industries including a vehicle service station, plumbing and metal work industries. Lawrence Drive is also an arterial road providing access to industries including a vehicle service station and carpet and steel industries having the highest daily traffic volume among the 16 sites. Patrick Road is an access road for a number of industries such as a boat builder and plumbing and furniture industries. Stevens Street is an industrial road with steep
slope (8.7%). It provides access to sheet metal, paint, furniture, welding and ready mix concrete industries. Relatively light traffic flow is experienced on this road.
In addition to that, traffic movements are different from the other land uses. This suburb is subjected to heavy duty traffic activities due to industrial activities in the area. Other than Stevens Street, the other three roads are close to a motorway (Pacific Motorway).
Figure 4-5 Study sites in Nerang
Clearview Estate (Residential land use)
Clearview Estate is situated most upstream of the Nerang River from among the selected sturdy areas, and has residential land use characteristics within the area. The selected sites are shown in Figure 4-6. All the sites are surrounded by detached family houses and well maintained lawns. The selections of the four different sites were based on the housing density which reflects the traffic activities in the area (Figure 4-6). These sites were:
Carine Court (R1)
Merloo Drive (R2)
Winchester Drive (R3)
Traffic activities are comparatively low in this suburb. Yarrimbah Drive is the connector road for this suburb to the main arterial and has high traffic flow. The other three roads are access roads.
Figure 4-6 Study sites in Clearview Estate
4.3 LABORATORY TESTING OF POLLUTANT BUILD-UP AND WASH-OFF SAMPLES