Hydrodynamic characteristics of a new permeable pavement material produced from recycled concrete and organic matter

The aim of the present study was to evaluate the hydrodynamic characteristics of a new material to be used for permeable and purifying pavements in urban areas. The new material is a mixture of crushed concrete, to provide structural support, and a compost mix intended to retain and biologically treat stormwater pollutants. The first part of this study was to evaluate the hydraulic conductivity of the material at different mixing ratios to define the range of materials suitable for urban drainage applications. The second part of the study involved using tracing experiments to quantify the effects of the pollutant transport mechanisms occurring during the water infiltration process. These experiments were conducted under steady state flows condition using a conservative tracer (NaCl). The results demonstrate that while the addition of compost significantly reduced the permeability of the concrete mix, it was still suitable for use as a paving material in an urban environment. The increased residence time of the stormwater pollutants due to the addition of the compost mix was shown to have a positive effect on the biological treatment of the stormwater pollution.     

Influence of stratigraphy and slope on the drainage capacity of permeable pavements: laboratory results

A small size laboratory test-bed was realized at the University of Genoa in order to evaluate the drainage capacity of permeable pavements by monitoring inflow, runoff and sub-surface outflow. The laboratory test programme was designed to investigate the influence of rainfall intensity and pavement slope on the hydrologic response of permeable pavements. Four permeable pavement systems combining two paving types (concrete cell and pervious brick) with two filter layers made of recycled glass aggregate and a mix of gravel and coarse sand are tested. The hydrologic response of permeable pavements is analysed by using a dimensionless volume index (discharge coefficient) and a timing index. Laboratory results reveal that the hydrologic performance is fairly consistent for all the investigated permeable pavements. The recycled glass aggregate turns out to be a valid solution. No surface runoff occurs even at 98 mm/h rainfall intensity.     

Status of porous pavement research

This paper discusses the U.S. Environmental Protection Agency's porous pavement research program along with the economics, advantages, potential applications, and status and future research needs of porous pavements.Porous pavements are an available stormwater management technique which can be used on parking lots and low volume roadways to reduce both stormwater runoff volume and pollution. In addition, groundwater recharge is enhanced. Also, cost reductions result due to elimination of curbs, drains, and small sized storm sewers.Porous asphalt pavements consist of a relatively thin course of open graded asphalt mix over a deep base of large size crushed stones. Water can be stored in the crushed stone base until it can percolate into the subbase or drain laterally. Other porous pavement types include concrete lattice blocks and a porous concrete mix.     

Optimum mix design of enhanced permeable concrete – An experimental investigation

Permeable pavement, due to its high porosity and permeability, is considered as an alternative to traditional impervious hard pavements for controlling stormwater in an economical and friendly environmental way. Permeable concrete normally made of single-sized aggregate bound together by Portland cement, using restrictedly as a pavement material, because of its insufficient structural strength. Aimed at developing a new type of permeable concrete with enhanced structural strength, various mix designs were attempted and their effects on the compressive strength and permeability of permeable concrete were investigated in this research. The optimum aggregate and mix components design were consequently recommended for enhanced permeable concrete.     

Stormwater quality associated with a silt trap (empty and full) discharging into an urban watercourse in Scotland

The aim was to assess the influence of a full silt trap at the end of a stormwater drainage pipe on the water quality of stormwater discharged into a semi‐natural urban watercourse. For approximately eleven weeks, the water qualities of the preliminarily treated stormwater and of the receiving watercourse (Braid Burn) were studied. The mean outflow concentrations of suspended solids were 2.0 mg/l and 34.1 mg/l during dry and wet weather conditions, respectively. Suspended solids concentrations of up to 141.6 mg/l were recorded during storm events. Suspended solids values for treated stormwater were often too high compared to international secondary wastewater treatment standards of around 30 mg/l. Pollutants including heavy metals (e.g., zinc, copper and nickel) accumulated in the silt trap. However, high outflow velocities during heavy rainfall events did not result in clearly defined sediment layers due to sediment re‐suspension. Metals did not accumulate in the receiving watercourse.     

Experimental study on the effects of LID measures on the control of rainfall runoff

ABSTRACT

Low impact development (LID) measures are important for controlling pollution and reducing the rainfall runoff volume, but they need lots of experiments to determine optimal characteristics. This study established low-elevation greenbelts, permeable pavements, and green roofs to determine the effect of LID measures on the control of rainfall runoff in a lateritic red soils region by simulating rainfall or runoff, and the variables were mainly of grass type, pavement type, substrate thicknesses, and rainfall intensity. The results (43.54–94.00% volume reduction and 40.59–97.48% pollutant removal effectiveness of low-elevation greenbelt with 10 cm depth and 5 cm height gullies, 13.19–74.20% volume reduction and 64.04–99.90% pollutant removal effectiveness of permeable pavement with 36.4 cm thick graded gravel layer, and 8.63–24.40%, 19.22–37.26%, and 30.14–48.44% volume reduction respectively of green roofs with 30, 50, and 70 mm substrate thicknesses) implied that LID measures can effectively reduce rainfall runoff volume and pollutants in lateritic red soils regions.     

Stormwater runoff quality and quantity from asphalt, paver, and crushed stone driveways in Connecticut

This study compared the quality and quantity of stormwater runoff from replicated asphalt, permeable paver, and crushed-stone driveways. Rainfall was measured on-site and runoff was recorded using tipping buckets. Flow-weighted composite runoff samples were analyzed weekly for total suspended solids, total Kjeldahl nitrogen, nitrate-nitrogen, ammonia-nitrogen, total phosphorus (TP), zinc, lead, and copper. Infiltration rate was determined on each driveway annually. Repeated measures analysis of variance indicated that stormwater runoff was significantly different among each driveway type; the order of decreasing runoff was asphalt> paver> stone. Average infiltration rates were 0, 11.2 and 9.0 cm/h for asphalt, paver, and crushed stone driveways, respectively. Both paver and crushed stone driveways reduced stormwater runoff as compared to asphalt driveways. Runoff from paver driveways contained significantly lower concentrations of all pollutants measured than runoff from asphalt driveways. However, runoff from crushed stone driveways was similar in concentrations to runoff from asphalt driveways, except for TP concentrations, which were lower in runoff from crushed stone driveways than runoff from asphalt driveways. The mass export of measured pollutants followed the relative differences in stormwater runoff, rather than differences in concentrations.     

In Situ Performance Monitoring of an Infiltration Drainage System and Field Testing of Current Design Procedures

Sustainable urban drainage systems offer a sustainable option for the disposal of stormwater runoff - reducing the risks of flooding and pollution of receiving watercourses. However, the adoption of such systems has been slow, with a lack of performance data identified as being one barrier. This paper presents in situ performance data from a perforated concrete ring soakaway which was installed to collect stormwater runoff from a school roof and paved area. Data on rainfall at the site and water depth in the soakaway were collected for a period of twenty months, and a number of rain events were studied in detail. Data from the soakaway were used to test the most recent design procedures for infiltration drainage systems, and it was found that the design equations gave reasonable predictions of system response to rainfall - especially when the observed runoff coefficients were taken into account.     

IN-SITU HYDRAULIC PERFORMANCE OF A PERMEABLE PAVEMENT SUSTAINABLE URBAN DRAINAGE SYSTEM

There is growing awareness that sustainable urban drainage systems can offer a more sustainable option for the management of stormwater runoff than conventional drainage systems. This paper presents in-situ performance data from a permeable pavement system which was installed to collect and treat stormwater runoff from a motorway servicestation car park. Data on rainfall at the site and outflow from the permeable pavement were collected over a thirteen-month period, and twenty rain events were studied in detail. The system provided a large degree of attenuation in terms of (a) reduction in peak flows, and (b) extended duration of outflows compared with rain events. Infiltration tests provided information on the processes of water entry into the pavement system and impacts of clogging on hydraulic performance.     

Experimental study on the hydrological performance of a permeable pavement

Permeable pavements play an essential role in urban drainage systems, making them the subject of great interest to both researchers and practitioners. However, previous studies have demonstrated a significant degree of uncertainty regarding both the hydrological performance and the maintenance requirements of this type of pavement. Within this context, the presented research involved the construction of a one metre square surface area of permeable pavement and a laboratory rainfall simulator to investigate the influence of rainfall intensity on the hydrologic response of permeable pavements. The design of the permeable pavement complied with the SuDS Manual guidance and British Standards (BS 7533-13:2009). The laboratory test programme was designed to investigate the influence of rainfall intensity on the hydrologic response of permeable pavements. The results demonstrate that the hydrologic performance varied according to rainfall intensity. The total volume of discharge from the permeable pavement ranged between 8% to 60% of the inflow. More than 40% of the total rainfall from all rain events was temporarily detained within the structure. Permeable pavement design optimisation has therefore been tested in the study. The SuDS Manual guidance has been found to meet current optimisation requirements.     

上海市区透水性路面渗透性能的实测与应用分析

采用透水性铺面削减径流水量与城区面源污染在国内尚处于起步阶段,虽然<建筑与小区雨水利用工程技术规范>标准对其设计、施工、维护等作了规定,但对其性能测定与实际应用效果的调查却很少.在对上海市具有代表性透水性路面的渗透效果进行实测调查的基础上,初步总结了透水性路面的应用现状,分析了影响透水性路面实际渗透性能的因素,为今后的应用推广提出了建议.     

Effects of PVC,cast iron and concrete conduit on concentrations of copper in stormwater

Architectural applications of copper on roofs, gutters and facades exposes it to weathering forces, such as wind and all forms of precipitation. This leads to the dissolution of copper from these surfaces and its introduction into local watersheds. The potential for exposure in local watersheds is a function of the amount of copper entering the watershed and the assimilation capacity of a wide variety of natural and manmade substrates that transform and sequester copper, thus reducing exposure of sensitive organisms to bioavailable copper. This study investigates one type of manmade substrate, stormwater conduit, commonly used to transport stormwater away from buildings. Conduits made of PVC and cast iron did not significantly remove copper from a synthetic stormwater spiked with copper averaging 2391 μg Cu/L. Concrete conduit significantly removed copper from the synthetic water and at high rates (12 – 18%) over a short distance (610 cm). A high percentage (81 – 100%) of the copper removed from the water was from the dissolved copper fraction. Once adsorbed to the concrete, copper did not readily leach back into copper-free water subsequently pumped into the conduit. These characteristics have significant implications for watershed management and best management practices for reducing concentrations of copper in stormwater runoff.     

The potential of green roofs to manage Urban Stormwater

Green roofs have considerable potential for stormwater source control, both for new developments and as a retrofit option. In the United Kingdom the lack of local quantitative performance data and modelling tools, together with more general barriers to sustainable drainage systems (SUDS) implementation, may explain their limited uptake to date. This paper presents preliminary findings from a small-scale instrumented green roof test plot located in Sheffield, UK. During spring 2006 the average volume retention was 34% and the average peak reduction was 57%. The key hydrological determinants were the antecedent dry weather period (ADWP), mean rainfall intensity and rainfall depth. Detailed examination of rainfall–runoff relationships in summer 2007 demonstrates the dependency of performance on antecedent moisture conditions. Structural appraisal of a range of flat roof types suggests that retrofitting a green roof will be a feasible option in many cases, particularly for concrete slab roofs.     

透水性路面材料缓解广州水浸街现象的研究

论述了透水性路面材料的意义,探讨了透水性混凝土的特性,介绍了透水性路面材料在缓解广州水浸街现象应用的试验情况,为广州市解决暴雨时路面水浸情况开辟了新的思路,从而对城市建设和发展作出巨大贡献.     

透水砖和下凹式绿地对城市雨洪的影响

为考察不同雨洪措施对防洪和增加雨洪资源利用量的贡献,采用城市暴雨雨水管理模型(SWMM),对北京某区域内铺设透水砖和采用下凹式绿地措施的排水管道主要断面洪峰流量的变化进行了计算分析。结果表明,铺设透水砖和采用下凹式绿地均可有效削减洪峰流量,减小径流系数,从而增加雨洪资源的利用量。但对于不同降雨频率的地区,下凹式绿地在降雨频率较大的地区,雨洪利用效果较好;透水砖则在降雨频率较小的地区,雨洪利用效果较好。该研究成果可以用来评价不同雨洪措施在不同降雨频率下对城市雨洪的利用效果,为防洪排涝工程提供了一定的技术支持。     

Advancing assessment and design of stormwater monitoring programs using a self-organizing map: characterization of trace metal concentration profiles in stormwater runoff

Stormwater runoff poses a great challenge to the scientific assessment of the effects of diffuse pollution sources on receiving waters. In this study, a self-organizing map (SOM), a research tool for analyzing specific patterns in a large array of data, was applied to the monitoring data obtained from a stormwater monitoring survey to acquire new insights into stream water quality profiles under different rainfall conditions. The components of the input data vectors used by the SOM included concentrations of 10 metal elements, river discharge, and rainfall amount which were collected at the inlet and endpoint of an urban segment of the Yeongsan River, Korea. From the study, it was found that the SOM displayed significant variability in trace metal concentrations for different monitoring sites and rainfall events, with a greater impact of stormwater runoff on stream water quality at the upstream site than at the downstream site, except under low rainfall conditions (≤4 mm). In addition, the SOM clearly determined the water quality characteristics for “non-storm” and “storm” data, where the parameters nickel and arsenic and the parameters chromium, cadmium, and lead played an important role in reflecting the spatial and temporal water quality, respectively. When the SOM was used to examine the efficacy of stormwater quality monitoring programs, between 34 and 64% of the sample size in the current data set was shown to be sufficient for estimating the stormwater pollutant loads. The observed errors were small, generally being below 10, 6, and 20% for load estimation, map resolution, and clustering accuracy, respectively. Thus, the method recommended may be used to minimize monitoring costs if both the efficiency and accuracy are further determined by examining a large existing data set.     

Life-cycle cost analysis of highway noise barriers designed with photocatalytic cement

This study examines the environmental and economic feasibility of concrete noise barriers containing photocatalytic cement using a life-cycle cost analysis (LCCA). Photocatalytic concrete contains titanium dioxide (TiO₂) which allows for the oxidation of air pollutants to occur on the surface of the building material. Design variables studied include the cementing material type (general use (GU) cement, ground granulated blast furnace slag (GGBFS) used as cement replacement, and photocatalytic (PCAT) cement), and the thickness of a photocatalytic concrete cover. The LCCA accounts for the CO₂ and NO_x generated during manufacturing and the NO_x (NO, NO₂) oxidised during the life of barriers containing photocatalytic concrete. A key outcome from this study revealed that at a 40-year service life, assuming a 6 mg/h/m² NO_x degradation rate, a barrier designed with 100%GU cement and a 25 mm photocatalytic concrete cover has an annual cost that is 7%, 30%, and 36% greater than the 100%GU, 35% and 50%GGBFS barriers without a photocatalytic cover, respectively. Results of this analysis also indicated that the application of a 25 mm photocatalytic concrete cover to concrete containing 35 and 50%GGBFS is more economically feasible than 100%GU concrete, irrespective of the service life and pollution degradation rate.     

生物滞留设施对城市雨水径流热污染的削减效应

径流热污染是水污染的重要方面,也是城市水体生态环境破坏的重要原因,生物滞留是缓解城市雨水径流热污染最有效的措施之一。通过不同填料的生物滞留实验,在人工模拟均匀降雨的条件下,探究了在不同降雨特征下不同填料生物滞留设施对城市雨水径流热污染的削减效果。结果表明,不同填料生物滞留设施热负荷削减效果从大到小依次为:炉渣、石英砂、陶粒、沸石;径流温度越高,所携带的热量越大,生物滞留设施的径流热污染负荷削减率也越高;体积削减对生物滞留设施削减雨水径流热污染的贡献大于热交换。     

Real-time control of stormwater detention basins as an adaptation measure in mid-size cities

ABSTRACT

The performance of predictive real-time control (RTC) of outflow from a detention basin, integrating rainfall forecasts in the definition of the control rules, was assessed in terms of peak flow reduction in the receiving water body, improvement of the level of service of the stormwater network downstream and qualitative treatment of runoff. Evaluations were performed using the PCWMM software with rainfall data for a continuous 6-month period and four individual events, in a future climate. As compared to the situation with static control, peak flows at the outfall were reduced by an average of 46% with predictive RTC, and the downstream collector was used up to 22% less during rainfalls. Also, the detention time reached the desired period of 36 h for water quality control, for most of the simulated rainfall events. This demonstrates the usefulness of RTC as an adaption measure to climate change in existing urban areas.     

Characterisation of diffuse pollutions from forested watersheds in Japan during storm events - its association with rainfall and watershed features

Forest areas have been identified as important sources of nonpoint pollution in Japan. The managers must estimate stormwater quality and quantities from forested watersheds to develop effective management strategies. Therefore, stormwater runoff loads and concentrations of 10 constituents (total suspended solids, dissolved organic carbon, PO(4)-P, dissolved total phosphorus, total phosphorus, NH(4)-N, NO(2)-N, NO(3)-N, dissolved total nitrogen, and total nitrogen) for 72 events across five regions (Aichi, Kochi, Mie, Nagano, and Tokyo) were characterised. Most loads were significantly and positively correlated with stormwater variables (total event rainfall, event duration, and rainfall intensity), but most discharge-weighted event concentrations (DWECs) showed negative correlations with rainfall intensity. Mean water quality concentration during baseflow was correlated significantly with storm concentrations (r=0.41-0.77). Although all pollutant load equations showed high coefficients of determination (R(2)=0.55-0.80), no models predicted well pollutant concentrations, except those for the three N constituents (R(2)=0.59-0.67). Linear regressions to estimate stormwater concentrations and loads were greatly improved by regional grouping. The lower prediction capability of the concentration models for Mie, compared with the other four regions, indicated that other watershed or storm characteristics should be included in the prediction models. Significant differences among regions were found more frequently in concentrations than in loads for all constituents. Since baseflow conditions implied available pollutant sources for stormwater, the similar spatial characteristics of pollutant concentrations between baseflow and stormflow conditions were an important control for stormwater quality.