Highway stormwater runoff contains a number of contaminants including nutrients and heavy metals that can be detrimental to the health of lakes, rivers, and streams. Biofiltration is a common stormwater treatment mechanism that can reduce nutrients and heavy metals through physical, chemical, and biological processes. Vegetation type has been shown to impact the removal of nutrients from stormwater runoff (Barrett et al. 2013; Read et al. 2008). The inclusion of a permanent saturated layer underneath the surface of a biofilter has been investigated to enhance denitrification and thus nitrogen removal (Kim et al. 2003; Zinger et al. 2007). Six Georgia native grasses as well as one turf grass have been tested in a column study along with a permanent saturated zone for biofiltration enhancement. Synthetic stormwater was used in this study. Two months of dosages with an average synthetic stormwater were monitored followed by one event with a heavy metal spiked synthetic stormwater, one event with a nutrient spiked synthetic stormwater, and one event with an average synthetic stormwater after two weeks of drought conditions. Biomass fly ash was also added to columns to determine potential benefits to biofiltration applications. Results indicated that Big Bluestem, Indiangrass, and Switchgrass when paired with a permanent saturated zone remove the highest percentage of total nitrogen across all experiments (4%, 13%, and 18% respectively). These species contained think and dense root systems that spanned the entirety of the biofilter column. Removal of nitrate was enhanced with a saturated zone while ammonium removal decreased. Nitrogen leaching from the columns may be reduced by utilizing soil of low organic content. Phosphorus, copper, lead, and zinc removal was not correlated with plant species; however, a permanent saturated zone increased removal of phosphorus, copper, and zinc (removal of lead was >97% in all cases making differences in removal insignificant). These results support the impact of specific vegetation types on the removal extent of total nitrogen. Saturation provided benefits of total nitrogen, phosphorus, copper, and zinc removal in terms of removal extents as well as consistency of treatment across all experiments. Field experimentation is encouraged to determine long term effects at a large scale.

<p> As highway runoff is one major source of non-point pollution in urban areas, removal of contaminants in runoff should be of great concern. In this paper, the necessity of highway runoff treatment in Shanghai was approved, systemic comparisons between runoff treatments were listed, detailed discussions on treatment approach selection were given based upon the availability of land. Three design models for highway runoff treatment were proposed; one focused on the urban highway, one focused on the suburb highway, and the third focused on the urban-suburb area. A survey among scientists studying runoff in China showed that the use of constructed wetlands was a remedy that was highly approved. They also supported the establishment of an urban runoff database. This paper will assist in the development of suitable treatment strategies for highway runoff in urban areas in China.</p>

As highway runoff is one major source of non-point pollution in urban areas, removal of contaminants in runoff should be of great concern. In this paper, the necessity of highway runoff treatment in Shanghai was approved, systemic comparisons between runoff treatments were listed, detailed discussions on treatment approach selection were given based upon the availability of land. Three design models for highway runoff treatment were proposed; one focused on the urban highway, one focused on the suburb highway, and the third focused on the urban-suburb area. A survey among scientists studying runoff in China showed that the use of constructed wetlands was a remedy that was highly approved. They also supported the establishment of an urban runoff database. This paper will assist in the development of suitable treatment strategies for highway runoff in urban areas in China.

This paper presents the results of an experimental study aimed at determining the impact of porous asphalt on the quality of stormwater runoff on highways with a curb and gutter drainage system. A porous overlay, also known as permeable friction course (PFC), is a layer of porous asphalt applied to the top of conventional asphalt highways at a thickness of 50 mm to improve safety and water quality and reduce noise. The quality of highway stormwater runoff was monitored before and after the installation of PFC on an eight-lane divided highway in the Austin, Texas area for 15 months. Observed concentrations of total suspended solids from PFC are more than an 80% lower than from the conventional pavement. Concentration reductions are also observed for nitrate/nitrite and total amounts of phosphorus, copper, lead, and zinc. The data shows that the results with curb and gutter are consistent with past results where runoff sheet flowed onto vegetated shoulders. / text

No description available.

The increasing urbanization of landscapes significantly alters the surface water hydrology of impacted watersheds. As a side effect, stormwater discharges to receiving water bodies are often of decreased quality due to pollutants deposited on impervious urban surfaces being entrained by runoff. A pertinent example of this problem is the presence of copper and zinc in highway runoff. Both copper and zinc have been shown to exert toxic effects on aquatic micro- and macro-biota. Copper in particular has been shown to harmfully disrupt the olfactory nervous system of fish species at concentrations as low as 3 [mu]g/L. To meet these limits, treatment of highway runoff for the removal of copper and zinc is necessary. However, due to the complexities associated with the behavior of heavy metals in natural systems, the appropriateness of removal techniques will necessarily depend on a variety of system-specific factors and chemical characteristics of highway runoff. Adsorption has been shown to be generally effective in the removal of dissolved heavy metals, but the choice of adsorptive media is again dependent on system-specific parameters. This study developed and evaluated a column testing protocol that can be used to quickly and reliably evaluate adsorptive removal of dissolved heavy metals from highway runoff. The protocol is demonstrated in an evaluation of iron oxide, manganese oxide, crab shell, concrete, and bone meal media for removing dissolved copper and zinc from highway runoff. The performance of these media was assessed as a function of various runoff characteristics including pH, ionic strength, alkalinity, and total organic carbon. The methodology was used to show that iron oxide media in combination with crab shell or concrete media provided the most effective removal of copper and zinc from highway runoff. Through this study, the convenience, flexibility, and robustness of the proposed protocol are compellingly established. / text

Yes / Although highway runoff has historically been extensively studied, the increasing complexity of stormwater management means that there are still significant gaps regarding the reduction of soluble metals. The work reported in this paper addresses these challenges by analysing the presence and behaviour of iron, copper and zinc in runoff from junction 24 of the M1 motorway in the UK (peak traffic flow: 30,000 vehicles per hour) and comparing it with other urban sources of metals found in the same catchment (a local brook and sewage treatment works). The sampling site included an interceptor and a treatment lagoon and the event monitoring indicated a trend by which the metals did not change their concentration or particulate soluble proportion immediately, hence showing that pre- and post-storm conditions are important factors when analysing the solubility of metals and their behaviour. The data provided further evidence of the important influence of storm characteristics on metal concentrations in highway runoff, in particular the effects of an antecedent dry weather period (ADWP). In addition, this study also helped us to better understand how the release of sodium the application of de-icer for road maintenance in winter affects the availability of zinc.

No description available.

Highway runoff, as a nonpoint source, may exert significant pollutant load on the catchment. Finding ways to mitigate nonpoint sources of pollutants is a matter of great concern for improving water quality. It was cited by the Environment Agency in 2005 that more than 80% of English rivers were at risk of failing to achieve Water Framework Directive (WFD) objectives through diffuse pollution (Faram, 2007; p.14). The presence and behaviour of metals were analysed and compared through seasonal sampling from one of the most trafficked roads in the Midlands, M1. These were compared with other sources: local streams and sewage works. The concentration of metals in stormwater from the M1, three neighbouring rural brooks and three local sewage works, all in the same catchment, were sampled. Three metals (Fe, Cu and Zn) were used as an indicator because of their predominance and potential harmful effect on biodiversity. The data was analysed to establish any links between the total and dissolved metals and standard water quality parameters. The thesis also examines the performance of a standard highway treatment system of interceptor and lagoon for removing metals. The results indicate that evaporation and de-icer salts had the strongest effect on metal concentrations and their solubility in the runoff from the M1. As additional factors, rainfall intensity and antecedent dry weather period (ADWP) had the most important influence on metal concentrations. Fe was always at the highest concentrations for all weather conditions (total and dissolved) and all sampling locations. The results also showed that Fe was affiliated with the particulate matter; however, it was also suggested that it was solubilised by anaerobic conditions. Zntot during wet weather exceeded the environmental quality standards (EQS) both on the M1 and in Woodbrook. The sewage work effluent did not exceed the EQS at any time of sampling. It was also found that Zn solubility was increased by the presence of de-icer salts which released it from the sediment by a process of ion-exchange, as suggested by the literature. Cu concentrations had the most erratic values and varied widely but were in the lowest concentrations compared to other metals. During wet weather Cudis from the M1 runoff exceeded the EQS. It was also concluded that the analytical and sample preservation methods chosen could have an effect on the concentrations of copper. Filtration with recycled glass and pea-gravel was able to remove particles down to 5 μm, but at the typical flow rate (5 m/hr), and solids loading the filters would need regular washing. The adsorption studies showed that metals are more effectively removed by alkaline conditions than acid conditions which release metals into the environment.

This paper presents the results of a study on the effectiveness of porous overlays on urban highways. Permeable Friction Course (PFC) is a layer of porous asphalt applied to the top of conventional asphalt highways at a thickness of around 50 mm. PFC is often installed for safety and noise benefits, and is being seen as an emerging technology for meeting environmental requirements for stormwater discharge. The first objective of the study was to determine the impact of porous asphalt on the quality of stormwater runoff on highways with a curb and gutter drainage system. The quality of highway stormwater runoff was monitored before and after the installation of PFC on an eight-lane divided highway in the Austin, Texas area for 2 years. Observed concentrations of total suspended solids from PFC are 92% lower than those in runoff from the conventional pavement. Concentration reductions are also observed for nitrate/nitrite and total amounts of phosphorus, copper, lead, and zinc. The data shows that the results with curb and gutter are consistent with past results where runoff sheet flowed onto vegetated shoulders. The effect of two different binder compositions is also compared, showing an increase in zinc when recycled rubber is used. The second objective focuses on the drainage capabilities of PFC. While porous overlays can reduce stormwater accumulation on roadways, capacity at high rainfall intensities is limited. Installing subgrade underdrains within PFC could further improve stormwater conveyance. This research attempts to model the hydraulic profile of runoff as it approaches an underdrain with varying flow rates and grades. The results could assist TxDOT in the sizing and configuration of drains based on rainfall intensity and roadway geometry. / text