AbstractThe pervious pavement system has been identified as an effective source control device capable of removing urban stormwater pollution by trapping pollutants within the system and biodegradation. Recent studies have further demonstrated that the pervious pavement system could be used as a source of renewable energy capable of reducing household energy bill by about 80%. In view of ever increasing demand for water and the continued reduction in available fresh water resources in the world, stormwater has been recognized as a potential valuable source of water which could be harnessed.
The overall aim of this multi disciplinary research was to evaluate the suitability of a modified pervious pavement system (PPS) for water harvesting and re-use, particularly focussing on potential third world applications and taking advantage of the latest developments in materials that are available for such applications. The aim was a holistic one in which water re-use was examined in terms of both the potential advantages from an irrigation point of view without ignoring the very important public health concerns that are often of concern when water is stored in circumstances which do not fit the normally used criteria for potable supplies.
The results of this study confirmed the pollution control capability of the porous pavement system as earlier determined by previous studies. Also, a novel experimental rig was designed to reproducibly create very high and realistic rainfall events over model pavement structures. Furthermore, the performance of a new geotextile, Inbitex Composite® in the pervious pavement system was determined for the first time. Furthermore, this study also tested for the first time, the performance of a pervious pavement system modified by the incorporation of Inbitex Composite® geotextile with slits and made prescriptions as to how this new geotextile could be best installed in a modified pervious pavement system in order to achieve high infiltration without compromising pollution control.
This study tested the practical use of the pervious pavement system for water harvesting and storage for reuse in irrigation. In order to achieve this, the author took what could be considered as a holistic approach to water quality issues and determined the chemical, electrochemical and microbiological quality of water stored in the system as well as investigated the public health concern of the potential of pathogenic organisms in waters stored in unconventional water storage system as the pervious pavement system. It also determined that the pervious pavement system have the capability to recycle water with physical, chemical and microbiological qualities that will meet international standards for irrigation and that the system does not offer a conducive environment for potential pathogenic organisms if contamination incident occurs from adjoining areas.
This study also became the first to practically relate Sustainable Urban Drainage System (SUDS) to agricultural benefit by demonstrating how a SUDS device (pervious pavement system) could be used in addition to its urban drainage control role, as a source of supply of high quality irrigation water to cultivate crops fit for human and animal consumption despite high application of pollutants. This study determined contrary to the observation of earlier studies that the use of slow-release iv fertilizer could lead to eutrophication problems in cases where the water is channeled to natural water courses. Furthermore, active response of potential pathogenic bacteria to the presence of slow-release fertilizer was observed in this study. This raises a huge question on the need to add fertilizer to the pervious pavement system. Coupe, (2004) had demonstrated that oil degrading microbes would respond positively to food sources in the system and hence, there was no significant need for simulation by nutrient addition, the author concluded in the study presented here that fertilizer addition should only be conducted if the waters are to be used for irrigation where the nutrients would be beneficial to the plants and that even in this case, the microbiological water quality should be constantly monitored and the addition suspended if the risk of contamination from adjoining areas is high.
|Date of Award||2009|
|Sponsors||Permavoid Limited & Hanson Formpave|
|Supervisor||Les Duckers (Supervisor), Alan Newman (Supervisor), Steve Coupe (Supervisor) & Tim Puehmeier (Supervisor)|
- pervious pavements
- microbiological contamination
- urban drainage
- water recycling
- water harvesting