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Tunnels are specific sections of roads, where the rainfall runoff process does not take place. Nevertheless, they are washed out periodically mainly for traffic safety reasons. The Portuguese National Laboratory for Civil Engineering (LNEC) monitored twice (in May and December 2003) the washout process of the 1570 m long IP2 Gardunha tunnel. The objective was to evaluate pollutant accumulation in the road pavement. Due to specific requirements from LNEC the wash operation was performed without the common detergents used to enhance the cleaning process. The annual average daily traffic (AADT), in 2003, was 9923. Measurements of flow and the collection of manual samples took place at the inlet of an oil separator tank that receives all the runoff from the tunnel, and discharges it into the local creek.

The first wash (1st wash) took place over two nights, with a total duration of 345 min, and an average flow of 1.6 L s. The second wash (2nd wash) operation was shorter, with the duration of 103 min and an average flow of 4.2 L s. The annual pollutant loads for metals, total suspended solids (TSS), oil, and grease and polycyclic aromatic hydro carbon (PAH) were estimated based on wash volumes and pollutant concentrations.

Compared to other monitoring studies of highway runoff in Portugal, Gardunha tunnel wash water presented low pollutants content. Only an evaluation of the results taking into consideration the flow processes inside the tunnel atmosphere allowed an understanding of the data, being concluded that tunnel pavements accumulate much less traffic pollutants than ordinary road pavements, under similar operation conditions. Furthermore, pollutants emitted inside the tunnel will tend to build up outside, therefore increasing runoff concentrations in the road sections flanking tunnels. These results are important for the control of highway runoff impacts.

Implementation of the European Union (EU) Water Framework Directive (WFD) has refocused attention on the impact of non-point source discharges on receiving water bodies. However, although the physico-chemical characteristics of urban runoff have been widely reported, its ecotoxicological impacts are less certain. There is currently considerable debate surrounding how the ecological status of water bodies should be determined and the all-encompassing environmental quality standards, required by the WFD, developed and complied with. To contribute to the debate surrounding these issues, the ecotoxicity of urban water and sediments were investigated in relation to concentrations of selected heavy metals in these environments. The Microtox test was used to evaluate the ecotoxicity of urban stream water, water samples in which sediments had been resuspended, porewater and sediments. Total concentrations of Zn, Cu, and Cd were determined in the same fractions. Data reported indicate that the toxicity of surface water is greater during wet weather events compared to dry weather conditions. Two different statistical approaches for assessing the associations between metals and ecotoxicity are described and the different interpretations provided are fully discussed

In Portugal, there is insufficient data concerning road runoff characterization to identify the most important explanatory variables to predict pollutant concentrations. Nevertheless, there is the need for a simple methodology to predict road runoff pollutants, for use by road project designers and national services in charge of water management.

Based on literature results a set of five independent variables, proved to explain site concentrations on road runoff constituents, have been selected. Using data for six Portuguese road sites, a multiple linear equation and its coefficients, named the PREQUALE, was established to predict total suspended solid (TSS), Zn, Cu, and Pb average concentrations in road runoff. The predictions obtained were very close to the observed concentrations; therefore, the PREQUALE will significantly improve the present practice in Portugal. This tool should be improved in the near future with the acquisition of more information concerning road runoff characterization in Portugal.

The approach followed by this study may be useful for other countries that have not yet much data but need to establish a simple way of predicting road runoff pollutants.

A field-based microcosm method was used to determine whether sediments and soils that receive road runoff are toxic to indigenous aquatic macroinvertebrates present in the Greater Melbourne Area (GMA), Australia. Sediments and soils collected from areas draining three major highways were placed in 20 L microcosms along the littoral zone of a non-polluted wetland. Aquatic insects that emerge from the wetland randomly lay eggs in the microcosms. The occurrence and abundance of key taxa in these microcosms was measured to determine toxicity of the sediments. Several taxa responded in different ways to these sediments. The abundance of , , and significantly increased with increased concentrations of contaminants in sediments, and appeared to be most influenced by nutrient enrichment. The occurrence of significantly declined with increased concentrations of zinc in surface waters that leached from sediments. abundance was significantly higher in nutrient-enriched sediments, but significantly declined in high zinc concentrations in surface waters. There were significant negative correlations between the occurrence of , , and spp. and copper or total petroleum hydrocarbon (TPH) concentrations in sediments. This method provides unique information on the effects of contaminated soils and sediments on indigenous aquatic macroinvertebrates and can be used to determine the effectiveness of water sensitive urban designs in reducing sediment toxicity.

As part of the European Union 5th Framework Programme (EU FP5) sustainable storm water management project DayWater, an international monitoring programme was established to investigate the ecotoxicity of highway and urban runoff samples. This involved the collection of samples from a total of 35 storm events from sites in Sweden (Luleå and Stockholm), Germany (Wuppertal), and France (Nantes). To enable both chronic and acute end points to be addressed, the ecotoxicity tests were performed using rotifers (), bacteria (), and algae (). Samples collected at the Stockholm site were additionally analysed for a range of water quality parameters enabling this site to be considered from a combined physico-chemical and ecotoxicological perspective. This paper provides an overview of the results of the whole monitoring programme and demonstrates that storm water frequently exerts a toxic effect. Although the levels of ecotoxicity detected were found to vary greatly in relation to sites, storm events and test organisms, further analysis demonstrated a moderately strong correlation between the responses of algae and rotifer tests. Microtox was generally found to be the most responsive test in terms of both frequency of detection of toxicity and level at which a toxic impact could be detected.

Reducing the impervious area (IA) of a watershed is becoming a common practice to mitigate the effects of urban runoff on the health of aquatic ecosystems. Yet, it is often argued that this approach is rather inefficient and it is debatable whether percentage IA targets can be applied to all urban environments, as local factors (e.g., soils, geology, terrain, and rainfall patterns) may influence the effect of imperviousness. Furthermore, different receiving waters may be affected by urban runoff in different ways: the effect of flows is likely to be strongest at the sub-watershed level, whereas quiescent waters are likely to be more affected by pollutants. A more effective approach is to develop an understanding of the effects of urban runoff on all receiving waters. This can be achieved by recognizing all the values in all receiving waters and the threat urban runoff poses to these values.

Ponds are frequently used to remove pollutants from urban runoff, but only a few accurate studies have been carried out to determine the long-term pollutant removal efficiency, and almost none on changes in removal over time. Removal efficiency will be affected by changes in pond morphology, vegetation growth, and sediment accumulation. This study presents the evolution of pollutant removal efficiency over a 7-year period.

The results showed that vegetation growth and increased sediment thickness affected copper, zinc, and nitrogen removal efficiency negatively. Concluding recommendations are removal of vegetation in the autumn and sediment removal after approximately 7–10 years in operation.

The road runoff of a sewered section of a road in Switzerland with a traffic intensity of 17,000 vehicles per day was intensely investigated over a period of 2 years. At the same time the road runoff was collected and pumped to a pilot plant for road runoff treatment. The treatment facilities consisted on one hand of shafts containing removable fleece filter bags and underlying GfeH-adsorber filters and on the other rotating fleece filter drums and subsequent adsorbers. It could be shown that the investigated processes for road runoff treatment can be operated as modular systems in one-, two-, or three-step flow schemes. Depending on the process scheme between 70% and 97% of the heavy metals could be removed.

Efficient heavy-metal removal from road runoff should be realized with particle separation and adsorption. As adsorbents, three zeolites and three ferric hydroxides were tested for copper and zinc removal. Sorption capacity and kinetics were evaluated with batch and specific column experiments. Results evidence that sorption capacity and kinetics of all ferric hydroxides were superior to the zeolites. Increased electrical conductivity revealed severe desorption of copper and zinc only from zeolites. For the full-scale treatment plant, zeolite 3 and Ferrosorp are used in one of the two retention filters each. The zeolite retention filter is not in service during winter to prevent desorption caused by de-icing salt.

A pilot-scale system consisting of presedimentation and a saturated downflow reactive bed filter was used for cleaning highway runoff. Blast furnace slag (BFS) and Polonite were selected as filter materials. A total suspended solids (TSSs) removal of over 99% was achieved. High removal performance was observed for dissolved Mn, Ni, Co, and Cu. In contrast Al was released after filtration. Metals were retained in the upper layer of the bed filters while a desorption was suggested to take place in the downward layers. This was probably attributed to the elevated salt levels during winter and the intermittent operation.