Fredrick U. Mbanaso

Stormwater harvesting for irrigation purposes: An investigation of chemical quality of water recycled in pervious pavement system

Most available water resources in the world are used for agricultural irrigation. Whilst this level of water use is expected to increase due to rising world population and land use, available water resources are expected to become limited due to climate change and uneven rainfall distribution. Recycled stormwater has the potential to be used as an alternative source of irrigation water and part of sustainable water management strategy. This paper reports on a study to investigate whether a sustainable urban drainage system (SUDS) technique, known as the pervious pavements system (PPS) has the capability to recycle water that meets irrigation water quality standard. Furthermore, the experiment provided information on the impact of hydrocarbon (which was applied to simulate oil dripping from parked vehicles onto PPS), leaching of nutrients from different layers of the PPS and effects of nutrients (applied to enhance bioremediation) on the stormwater recycling efficiency of the PPS. A weekly dose of 6.23 × 10(-3) L of lubricating oil and single dose of 17.06 g of polymer coated controlled-release fertilizer granules were applied to the series of 710 mm × 360 mm model pervious pavement structure except the controls. Rainfall intensity of 7.4 mm/h was applied to the test models at the rate of 3 events per week. Analysis of the recycled water showed that PPS has the capability to recycle stormwater to a quality that meets the chemical standards for use in agricultural irrigation irrespective of the type of sub-base used. There is a potential benefit of nutrient availability in recycled water for plants, but care should be taken not to dispose of this water in natural water courses as it might result in eutrophication problems.

Laboratory-based experiments to investigate the impact of glyphosate-containing herbicide on pollution attenuation and biodegradation in a model pervious paving system.

An experimental investigation was carried out to determine the effect of glyphosate-containing herbicides (GCHs) on the hydrocarbon retention and biodegradation processes known to occur in pervious pavement systems (PPSs). The PPS test rigs were based on the four-layered design detailed in CIRIA C582. This enabled the pollutant retention capacity of the PPS and biodegradation of retained pollutants by microorganisms to be investigated. The use of test rigs also enabled the impact of GCH on PPS eukaryotic organisms to be studied, by the monitoring of protist bioindicators. Results showed that GCH disrupted hydrocarbon retention by the geotextiles relative to rigs with mineral oil only added, as 9.3% and 24.5% of added hydrocarbon were found in herbicide only rigs and herbicide plus oil rigs respectively. In previous studies, PPS contaminated by mineral oil had been shown to retain 98.7% of added oils and over several weeks, biodegrade this oil in situ. Where GCH was added to experimental models, much higher concentrations of heavy metals, including Pb, Cu, and Zn, were released from the PPS in effluent, particularly where GCH and mineral oil were added together. The source of the majority of the metal contamination was thought to be the used engine oil. The herbicide generally increased the total activity of microbial communities in rig systems and had a stimulating effect on bacterial and fungal population numbers. Although the protists, which are part of the microbial community directly or indirectly responsible for biodegradation, were initially strongly affected by the herbicide, they showed resilience by quickly recovering and increasing their population compared with rigs without added herbicide, including the rigs with mineral oil added to them. However, the presence of herbicide was associated with a decrease in the species richness of recorded protist taxa and a predominance of robust, cosmopolitan or ubiquitous protist genera.

Human factors analysis and classification system for the oil and gas industry (HFACS-OGI)

The oil and gas industry has been beset with several catastrophic accidents, most of which have been attributed to organisational and operational human factor errors. The current HFACS developed for the aviation industry, cannot be used to simultaneously analyse regulatory deficiencies and emerging violation issues, such as sabotage in the oil and gas industry. This paper presents an attempt to improve the existing HFACS investigation tool and proposes a novel HFACS named the Human Factors Analysis and Classification System for the Oil and Gas Industry (HFACS-OGI). Results found the HFACS-OGI system to be suitable for categorising accidents, following the analysis of 11 accident reports from the US Chemical Safety Board (US CSB). The HFACS-OGI system moreover revealed some significant relationships between the different categories. Furthermore, the results indicated that failures in national and international industry regulatory standards would automatically create the preconditions for accidents to occur.

Evaluation of the effectiveness of wrapping filter drain pipes in geotextile for pollution prevention in response to relatively large oil releases

French drains or infiltrating filter drains are commonly fitted with slotted plastic pipe to act as an overflow mechanism when rainfall is too great to allow complete infiltration. The release of the effluent from such pipes is commonly to surface water courses. Whilst there is expected to be some slight degree of protection against hydrocarbon release because of interaction with the drain’s stone infill material this will be severely limited. This paper reports an experiment in which model filter drains with or without geotextile sleeves around the slotted drain are challenged with lubricating oil. The textile was a surface-treated non-woven geotextile manufactured from polyester. The models were challenged with very high loadings of oil, as would be anticipated in a motor vehicle collision occurring close to the drain. A series of simulated 10-20mm rain events over 1 hour were applied and two sample types were collected which either included or excluded any free product. Additional aliquots of oil were added at each rain event. The un-sleeved models were found to release visible free product with the addition of as little as 100ml of oil per linear meter of drain. For the models with geotextile sleeves there was no such release with as much as 2000ml per linear metre. Analysis showed that under these conditions the geotextile sleeved pipes continued to produce effluent with hydrocarbon concentrations well below the 5000μg/l limit usually accepted in the UK.

An assessment of the potential use of compost filled plastic void forming units to serve as vents on historic landfills and related sites

Much of the solid municipal waste generated by society is sent to landfill, where biodegrading processes result in the release of methane, a major contributor to climate change. This work examined the possibility of installing a type of biofilter within paved areas of the landfill site, making use of modified pervious paving, both to allow the escape of ground gas and to avoid contamination of groundwater, using specially designed test models with provision for gas sampling in various chambers. It proposes the incorporation of an active layer within a void forming box with a view to making dual use of the pervious pavement to provide both a drainage feature and a ground gas vent, whilst providing an active layer for the oxidation of methane by microbial action. The methane removal was observed to have been effected by microbial oxidation and as such offers great promise as a method of methane removal to allow for development of landfills.

Applications of SuDS Techniques in Harvesting Stormwater for Landscape Irrigation Purposes: Issues and Considerations

While urbanization and increasing population has put much pressure on natural drainage channels and resulted in increase in flooding, there is increased pressure on available water resources due to climate change, reduction in frequency of rainfall events and drought. The emergence of a sustainable drainage system (SuDS), also known as best management practice (BMP) and low impact development (LID), has changed the management strategy of drainage from conventional to sustainable. SuDS techniques seek to deliver the three cardinal paradigms of sustainable drainage: quantity, quality and amenity and as such, they can offer an additional benefit for applications such as landscape irrigation. Most SuDS techniques have the potential for water storage with minimal or no modifications required. This chapter, while covering the capabilities of SuDS systems, explores SuDS devices such as pervious pavements equipped with excess storage capacity, cisterns and tanks harvesting roofwater, infiltration systems aimed at supporting the growth of urban plants and green roofs with the potential to store water in order to maintain water demanding planting scheme even during dry periods. It also covers systems where SuDS is the main driver to device installation and address issues and considerations surrounding applications of such systems in water harvesting for irrigation.

Evaluation of Pervious and Macro-Pervious Pavements as Harvesting Systems for Localized Landscape and Horticultural Irrigation

Pervious pavements have been used as water harvesting systems and studies have shown the value of water derived from pervious pavements as irrigation water for landscaping. An alternative system is a modification known as a macro-pervious pavement system. These devices infiltrate water through discrete points into a porous subbase offering all the benefits of the pervious pavement along with an ability to use the specially designed infiltration systems as a means of protecting the sub surface environment from major oil spillages. This paper reports ongoing research aimed at assessing the suitability of water derived from both pervious and macro-pervious pavement installations for irrigation use. Results are reported from ongoing field studies of a 6 year old macro-pervious pavement and, for comparative purposes, a 10 year old pervious pavement system which illustrates the great potential of pavement derived water from both types of system and some of the problems which require care in the management of the irrigation system.