Thursday Poster Session - Source control measures - Understanding & management

Physically based integrated modelling of surface and groundwater is an important tool in the management of groundwater systems but is most often conducted at large catchment scales. At the same time local management of stormwater often allows water to infiltrate impacting local groundwater dynamics. For these scales the demands on the model for representing local processes is not well documented. This study determines the impacts of utilising alternative model resolutions (1m and 2m) and geological conceptualisations (simplified and real-world) in a physically-based, integrated model on local groundwater responses in a small urbanised sub-catchment. The results indicated minor differences in overland flow directions as well as groundwater heads locally under an infiltration swale and across a larger site between 1m and 2m resolutions. Altering the geological representation impacted the characteristics of the groundwater response substantially. Local dynamics were visible using a 20mm rain event at both resolutions and geological representations. For future groundwater modelling at smaller scales, a 2m resolution is recommended to allow for more extensive calibration as a starting point if surface water flows are verified. When complex short-term local response representation is not demanded a simpler conceptualisation of geology may be viable. If a detailed representation is applied that includes low conductivity layers, knowledge of infiltration rates, natural groundwater levels and how to set up appropriate model boundary conditions is especially important. 

This abstract describes the adaptation of an infiltration swale to improve the infiltration and retention of metals, addressing common challenges in coastal regions characterised by shallow aquifers and high infiltration rates. The former infiltration swale received surface runoff containing metallic ions, thereby becoming a point source for the injection of pollutants into the subsoil. The design of the new structure includes the complete sealing of the swale, the installation of a perforated drainage tube, and the insertion of a commercial chitin (biosorbent) bedding. Following the modification of the swale, samples of surface runoff, groundwater, water percolated through the chitin bedding, and soil were collected to determine the concentrations of metals (Cr, Pb, Ni, Cu, Zn, Fe, and Mn). This paper presents information on the metals present in surface runoff and filtrated flow. The analyses and methodological procedures followed the APHA manual (2012). The results obtained for metal removal were excellent for Cr, Pb, Cu, Zn, and Fe, improving the quality of the runoff reaching the aquifer. However, the modifications to the structure led to the retention of solids and a reduction in the volume of soil infiltrated into the subsoil. 

Green roofs (GRs) are increasingly being applied in urban areas to mitigate the effects of climate change, enhance biodiversity, and reduce heat and stormwater runoff peaks. However, GRs runoff may contain nutrients, metals, and pesticides originating from substrates, root barrier layers, and façade paints. These substances may deteriorate aquatic ecosystems. This study examines the effectiveness of a decentralized granular activated carbon (GAC) filter in removing pesticides and nutrients from GR runoff. Laboratory batch experiments tested eleven GAC types and mixtures, including those with iron hydroxide, calcite, and iron shavings, under controlled conditions. The best-performing GAC achieved high pesticide retention (up to 98%) and strong phosphate removal (>99%), though DOC removal was limited. A pilot system was installed at the runoff of a 1,000 m² extensive GR. The monitoring of the first nine rain events using automated flow and sampling systems show Mecoprop removal efficiencies ranging from 27% to 84%, influenced by consecutive dry weather days and the volume of rainfall. The findings highlight the potential of decentralized GAC filtration to reduce pollutants in GRs runoff, supporting sustainable urban water management. However, the treatment system must be improved. 

Technical filters for stormwater treatment have already been used in decentralized scale for a longer time, in Germany. Their use in centralized scale is still limited because of missing (operational) experience and the absence of established dimensioning approaches. This work shortly describes the state of research of two in-situ centralized filter systems as well as column experiments, with focus on dimensioning parameters, operating behavior of the filters, and concentration profiles of suspended solids. The coefficient of permeability (kf-value) represents one main dimensioning parameter due to the functional correlation of head loss, volume flow and filter geometry (filter height, filter cross-sectional area). This value exponentially decreases with increasing filter lifetime and pollution load. Feeding interruptions, as naturally inherent to stormwater treatment systems, lead to short-term increases of the kf-value. Deep-bed filters in centralized systems allow the retention of (fine) suspended solids as well as dissolved pollutants (e.g. heavy metals as copper and zinc), with efficiencies of about 60 to 80 % regarding suspended solids and > 70% for heavy metals. 

Porous asphalt mixtures (PAM) are one of the main surfaces used in permeable pavement systems (PPS) and represent a key Blue-Green Infrastructure (BGI). PAM must preserve an efficient void network to ensure adequate infiltration, but their hydraulic performance is highly sensitive to structural damage such as cracking. This study evaluates changes in hydraulic conductivity in PAM incorporating blast furnace dust (BFD), a steel-industry by-product, in both before and after centrally cracked states, supporting future microwave-based healing applications. Compacted mixtures containing 0%, 4% and 8% BFD (M0, M4 and M8) were tested to assess how cracking affects void connectivity, flow paths and hydraulic behaviour. Hydraulic conductivity (K) was measured using a falling-head permeameter, enabling comparison between intact specimens and those with a single mid-height crack. Results show that cracking modifies the drainage regime, with slight increasing K values in mixtures with higher void connectivity (M0 and M4) and a notable increase K-values in the denser M8 mixture. Hydraulic variation was mainly governed by void structure and tortuosity, confirming that cracking reshapes drainage pathways within PAM. These findings highlight the interaction between structural damage and hydraulic function and establish a reference condition for evaluating microwave-healing performance in BGI pavement technologies. 

As urban areas expand, water runoff and energy demand increase. Combined with the escalating impacts of climate change, such as heightened risks of flooding and pollution, these challenges highlight the growing importance of green infrastructure innovations. Two such systems, permeable pavement and geothermal energy, have been independently researched and implemented for decades. Although initial studies have demonstrated promising potential, further research is required to assess feasibility, cost-effectiveness, and optimal design parameters. Building on previous laboratory and real-world studies, we designed a field experiment in Wilson, NC, to test a combined system with optimized design parameters. The main objectives of the project are to evaluate the water quality exiting the permeable pavement system, assess the energy efficiency of the geothermal coils, and provide a practical demonstration of a combined PPS and GHPS system. To assess the heat pump’s efficiency, the Coefficient of Performance (COP) will be calculated using data collected on temperature, air flow, and energy usage. The permeable pavement performance will be evaluated by monitoring flow rates and analyzing the water quality during storm events. The integration of these two green infrastructure systems has the potential to incentivize contractors to adopt PPS over traditional pavements by demonstrating enhanced financial benefits, such as reduced energy costs, that justify higher initial investments. 

EcOasis® is a systemic solution combining high-albedo pavement, integrated stormwater management, and greening. This innovation, developed by Eiffage Route, aim to mitigate urban heat island (UHI) phenomenon. A monitoring study was conducted by City Climate X on Rue de la Blanchisserie in Belleville-en-Beaujolais (69), which was requalified as an EcOasis® in 2023. It allowed for the evaluation of the site's thermal comfort over several days representative of the summer of 2025, compared to a control site located on Rue des Remparts. The results show a significant variation in comfort throughout the day. In the morning, EcOasis® is generally less comfortable, due to its rapid exposure to solar radiation. However, in the afternoon and evening, the trend reverses: EcOasis® offers significantly greater thermal comfort thanks to its design, which reduces heat flow and promotes nighttime dissipation, cooling down faster than Rue des Remparts, which retains heat. These findings highlight the effectiveness of EcOasis® for urban cooling. 

The acceleration of urbanization, combined with recurrent heatwave episodes, intensifies the Urban Heat Island (UHI) effect. This major phenomenon results in a temperature increase, leading to higher energy consumption, public health concerns, and an impact on biodiversity. Urban surfaces, particularly sealing pavements that absorb and restitute heat, are primary contributors to the UHI. The management of stormwater is also a crucial issue for urban resilience. In this context, Holcim is developing permeable concrete solutions that contribute for the non sailing of soils and open the route for new cooling strategies. However, the large-scale deployment of these solutions is hampered by a lack of experimental data to quantify cooling performance. The studies undertaken here aim to fill this gap by evaluating the efficiency of evapotranspiration. The study focuses on comparing two hydraulic porous materials: A Draining Concrete (Hydromedia) with a permeability of 5.10-2 m/s and a Sponge Concrete with a permeability of 2.10-6 m/s. This new cooling concrete technology stores rainwater in its porosity so that it can be evaporated during hot and dry periods. 

Most nature-based solutions (NBS) for urban stormwater management rely on the principle of water infiltration. Reliable estimates of key hydraulic parameters, such as saturated hydraulic conductivity (Ksat), are therefore essential to compare and assess these NBS. However, traditional techniques for measuring these parameters remain difficult to implement in the field, and commercial infiltrometers are costly and proprietary. This study presents INFLOW (INFiltration characterization with Low-cost Open-hardware Water infiltrometer), an open-source device providing high temporal resolution infiltration measurements with minimal field constraints. INFLOW combines modular components and comprehensive documentation to enable broad access and allow users to assemble and repair the device independently. Operational feedback showed low measurement noise, precise depiction of infiltration phases, rapid autonomous sampling, portability, and robust reproducibility. Limitations include the need to improve water-level stabilization and supply rate to measure infiltration in highly permeable soils. Coupled with the BEST model (Beerkan Estimation of Soil Transfer parameters), INFLOW enables estimation of hydraulic parameters in porous media. Preliminary multi-site results show that INFLOW is a scalable, low-cost alternative capable of comparing NBS hydraulic parameters, contributing to their standardized and accessible characterization. 

Urban areas are facing increasing challenges from extreme weather events, necessitating the development of multifunctional green infrastructure solutions. Infiltration swales are widely used to manage stormwater, but their long-term performance is compromised by the accumulation of heavy metals, in particular copper leached from roof surfaces. This study evaluates the potential of zeolite amendments to enhance heavy metal retention and soil conservation in infiltration swales. A semi-technical experimental setup with 18 vegetated troughs was established, comparing three configurations: regular soil, soil-zeolite mix, and a zeolite surface layer, combined with either a designed plant community or a standard lawn seeding. Stormwater from a copper roof will be applied over a one-year period, with analyses of copper removal efficiency, soil contamination, and the regeneration potential of the zeolite layer. Complementary laboratory tests will be used to assess adsorption kinetics and capacity. The findings aim to determine pollutant retention, durability, and biodiversity benefits, supporting sustainable stormwater management strategies in urban environments.