Jorge Rodriguez-Hernandez

A fuzzy stochastic multi-criteria model for the selection of urban pervious pavements

Multi-criteria decision making methods (MCDM) have been widely used throughout the last years to assist project contractors in selection processes related to the construction field. Sustainable urban drainage systems (SUDS) are an especially suitable discipline to implement these techniques, since they involve important impacts on each branch of sustainability: economy, environment and society. Considering that pervious pavements constitute an efficient solution to manage urban stormwater runoff as a source control system, this paper presents a multi-criteria approach based on the Integrated Value Model for Sustainable Assessments (MIVES) method to facilitate their proper selection. Given the lack of accurate information to shape the behavior of the alternatives regarding some of the criteria defining the decision-making environment, a series of variables are modeled by executing stochastic simulations based on the Monte Carlo methods. Additionally, a group of ten experts from various sectors related to water management was requested to provide their opinions about the importance of the set of selected criteria, according to the comparison levels of the Analytic Hierarchy Process (AHP). These judgments are converted into triangular fuzzy numbers, in order to capture the vagueness that human attitude entails when making judgments. A case of study in which the three major types of pervious pavements (porous asphalt, porous concrete and interlocking concrete pavers) are evaluated is presented to demonstrate the potential of the model.

Runoff infiltration to permeable paving in clogged conditions

The effect of varying runoff on a clogged permeable surface was analysed using a specifically designed laboratory rig consisting of a variable gradient testing frame, a rain simulator and water collecting chambers. The results indicate that the apparatus can be used successfully to test the runoff resistance of concrete blocks in permeable surfaces. The results indicate that a surface at 2% gradient that is clogged with crushed construction debris still permits significant levels of infiltration.

Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks

Interlocking concrete block pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (R(SL)) and surface slope (S(S)). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25 m(2) for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the R(SL) and S(S) variables. All models passed a confidence level of 95%, presenting high R(2) values and showing that R(SL) is a more influential variable than the S(S) for all clogging scenarios.

An evaluation of enhanced geotextile layer in permeable pavement to improve stormwater infiltration and attenuation

This paper reports on an evaluation of the properties of a novel structure known as OASIS® which was designed at Coventry University as an enhancement of the commercially available geotextiles when incorporated in the permeable pavement system (PPS). The impact on the hydraulic behaviour of a PPS was analysed through the study of infiltration rate, throughout the PPS and time required to reach the steady-state stage behaviour of the water within the PPS, under extreme rainfall intensities of 100 mm/hr, 200 mm/hr and 400 mm/hr, corresponding to a 100-year return period rainfall over a duration of 15 min in different parts of the world. The result indicated that the novel structure provides an extra benefit when incorporated in PPSs, delaying peak flow of a rainfall event by retaining and storing great volumes of water within its structure. These additional benefits are especially important under extreme rainfall events.

Characterization of Infiltration Capacity of Permeable Pavements with Porous Asphalt Surface Using Cantabrian Fixed Infiltrometer

AbstractPorous asphalt is used in Permeable Pavement Systems, but it is sensitive to surface clogging, which leads to a loss in its infiltration capacity. Test methods based on the use of permeable pavement models, which are manufactured in a laboratory and assessed under different clogging conditions, such as slope, rain, and runoff, have been widely applied to the study of permeable pavements with concrete blocks but not to the study of porous bituminous mixtures. The Cantabrian Fixed (CF) Infiltrometer has been used for the study of porous asphalt with void percentages between 20 and 33%. Three clogging scenarios were studied: 1) newly placed surface, 2) surface with an average maintenance level, and 3) clogged surface. Each clogging scenario was tested with five different slopes: 0, 2, 5, 8, and 10% and three repetitions. The direct rainfall simulation was produced by five lines of bubblers over the 0.25 - m2 piece, and the runoff was simulated by one perforated pipe over a plastic ramp at the beginni...

Long-term analysis of clogging and oil bio-degradation in a System of Catchment, Pre-treatment and Treatment (SCPT).

Runoff contamination has motivated the development of different systems for its treatment in order to decrease the pollutant load that is discharged into natural water bodies. In the long term, these systems may undergo operational problems. This paper presents the results obtained in a laboratory study with a 1:1 scale prototype of a System of Catchment, Pre-treatment and Treatment (SCPT) of runoff waters. The analysis aims to establish the operational behaviour of the SCPT in the long term with respect to oil degradation and hydraulic conductivity in the geotextile filter. It is concluded that bio-degradation processes take place inside the SCPT and that hydraulic conductivity of the geotextile filtration system decreases slowly with successive simulated runoff events.

Long-Term Simulation of a System for Catchment, Pretreatment, and Treatment of Polluted Runoff Water

The effects of pollutants in runoff on the environment have forced the development of several water treatment systems with the aim of reducing this kind of pollution before its final discharge. Nevertheless, many of these systems do not behave satisfactorily and, additionally, there is a low level of confidence in the treatment performance. This paper introduces the results of research on the long-term performance of a laboratory prototype of a system for catchment, pretreatment, and treatment (SCPT) designed to deal with the polluted runoff water. Solid and oil treatment efficiency were the focus of the study. After 14 consecutive simulated rain events, the treatment efficiency levels achieved by the prototype are higher than 80% of solids and 90% of oils.

Laboratory Study on the Stormwater Retention and Runoff Attenuation Capacity of Four Permeable Pavements

AbstractHydrological behavior of pervious pavements during rainfall events is a complex process that is affected by many factors such as surface type, nature of aggregates, layer thickness, rainfall height, rainfall intensity, and the preceding dry period. In order to determine the influence of construction materials on the runoff attenuation capacity of pervious pavements, 16 laboratory models were created with four different cross sections obtained by combining two pervious surfaces and two subbase aggregate materials. Successive rainfall simulations were applied over the laboratory models, measuring lag times, retained rainfalls, and times to peak, and peak outflows were registered for the simulated rainfalls. The results obtained were grouped depending on the materials used and statistically analyzed in order to compare their stormwater retention and runoff attenuation capacities. Both surface type and subbase aggregate characteristics were proven to influence the attenuation capacity of pervious pave...

Comparative analysis of the outflow water quality of two sustainable linear drainage systems

Three different drainage systems were built in a roadside car park located on the outskirts of Oviedo (Spain): two sustainable urban drainage systems (SUDS), a swale and a filter drain; and one conventional drainage system, a concrete ditch, which is representative of the most frequently used roadside drainage system in Spain. The concentrations of pollutants were analyzed in the outflow of all three systems in order to compare their capacity to improve water quality. Physicochemical water quality parameters such as dissolved oxygen, total suspended solids, pH, electrical conductivity, turbidity and total petroleum hydrocarbons were monitored and analyzed for 25 months. Results are presented in detail showing significantly smaller amounts of outflow pollutants in SUDS than in conventional drainage systems, especially in the filter drain which provided the best performance.

Relationship between Urban Runoff Pollutant and Catchment Characteristics

Much research has been done to determine levels of contamination in runoff from urban and rural catchment areas. Some authors compare their results with other authors or look for relationships between the variations of pollutant concentration and the catchment characteristics, but they seldom focus on determining the statistical significance of their results. This paper presents a review of 37 papers selected from a total of 169 papers consulted about runoff-water quality throughout the world (America, Asia, and Europe). The results presented in these 37 papers have been reviewed and statistically analyzed to evaluate the influence of catchment-area characteristics (location, size, average daily traffic, and type of land use) on the storm water runoff pollution. For the cases studied, most of the results about the polluting agents studied are comparable and no important element of the catchment characteristics had significant influence on the pollutants’ concentration.