Water Asset Research Articles

HYBRID CONTROL ACCOMMODATION FOR WATER-ASSET MANAGEMENT OF HYDRAULIC SYSTEMS SUBJECTED TO LARGE OPERATING CONDITIONS

The Hybrid Control Accommodation (HCA) strategy was proposed to improve the water asset management of hydraulic systems by resource allocation and setpoint assignment. Hydraulic system dynamics are taking into account during the setpoint assignment step which consists in controlling gates for larges operating conditions. For hydraulic systems subjected to strong disturbances, transfer delays are variable, thus different operating modes must be considered. A multimodelling method associated with a transfer delay selection technique allowing for the determination of the number of models, is proposed. The simulation results on the first reach of the Neste canal show the effectiveness of the HCA strategy.

The Pink Fan: a classic deep-marine canyon-fill complex, Block G, NW Sabah

Key risks for exploration in deep-water Neogene basins are reservoir development, hydrocarbon charge and trap retention. Over the last two years SMEP's deep water asset team, EPD-XDW, has made a concerted effort to de-risk the NW Sabah deep water prospect portfolio through large-scale 3D seismic acquisition, integrated basin analysis studies, green-field exploration and deep-water field appraisal. This evaluation allows the main Miocene turbidite fan systems of the Sabah trough to be slowly unraveled and will establish NW Sabah as a classic area for the study of active margin deep-water sedimentation. The NW Sabah basin has a surprisingly rich sand fairway, with at least four fan depositional cycles being recognised within the Upper Miocene stratigraphy between 12.1 and 6.7 Tertiary boundaries, TB2.6-TB3.3. The thickest and best known fans are those of the Kebabangan, Kinarut and Kamunsu, all named after the wells which discovered them. The Pink fan is the last of the sand-prone Upper Miocene fans deposited in the Kamunsu basin and was deposited the furthest outboard, partly in response to the progradation of the shelf edge across the Sabah margin and partly due to local tectonics which strongly influenced the contemporaneous sea-floor profile. The older fan units within this basin are all disconnected from their slope feeders by faulting and erosion. In the past, this hindered reservoir prediction and the generation of viable palaeogeographical reconstructions. The Pink fan is still connected to its feeder canyon and, best of all, has been drilled twice in recent years. This well data in combination with detailed seismic evaluation has enabled the unraveling of this confined fan unit to a degree not yet achievable within the older fans.

Bayesian updating for binary variables: an application in the UK water industry

Summary. In accordance with the regulation of the privatized English and Welsh water industry, water companies are required to submit an asset management plan every few years. A requirement of South West Water's asset management planning is to state the probability that some of its assets will need refurbishment or replacement within the following 5 years. Probability assessments are elicited for the company's assets based on information of varying quality. For the formulation and updating of beliefs we propose and employ the threshold model, a Bayesian updating procedure. The model's main aspect is Jeffrey's conditionalization. This is an updating rule based on a simple conditional independence assumption. According to this rule, it is not necessary to construct a fully specified joint density for the quantities of interest and the probability assessments.

Formation of natural biofilms during chlorine dioxide and u.v. disinfection in a public drinking water distribution system.

The influence of two disinfection techniques on natural biofilm development during drinking water treatment and subsequent distribution is compared with regard to the supply of a high-quality drinking water. The growth of biofilms was studied using the biofilm device technique in a real public technical drinking water asset. Different pipe materials which are commonly used in drinking water facilities (hardened polyethylene, polyvinyl chloride, steel and copper) were used as substrates for biofilm formation. Apart from young biofilms, several months old biofilms were compared in terms of material dependence, biomass and physiological state. Vital staining of biofilms with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and the DNA-specific 4',6-diamidino-2-phenylindole (DAPI) staining resulted in a significant difference in physiological behaviour of biofilm populations depending on the disinfection technique. Compared with chlorine dioxide disinfection (0.12-0.16 mg l-1), the respiratory activities of the micro-organisms were increased on all materials during u.v. disinfection (u.v.254; 400 J m-2). The biofilm biocoenosis was analysed by in situ hybridization with labelled oligonucleotides specific for some subclasses of Proteobacteria. Using PCR and additional hybridization techniques, the biofilms were also tested for the presence of Legionella spp., atypical mycobacteria and enterococci. The results of the molecular-biological experiments in combination with cultivation tests showed that enterococci were able to pass the u.v. disinfection barrier and persist in biofilms of the distribution system, but not after chlorine dioxide disinfection. The results indicated that bacteria are able to regenerate and proliferate more effectively after u.v. irradiation at the waterworks, and chlorine dioxide disinfection appears to be more applicative to maintain a biological stable drinking water. As far as the application of u.v. disinfection is used for conditioning of critical water sources for drinking water, the efficiency of u.v. irradiation in natural systems should reach a high standard to avoid adverse impacts on human health.

Integrated water asset management system (IWAMS)

As data proceeds through different levels of an organisation from its capture to its processing and refinement, it is reported as information relevant to a particular application. Data can be adversely influenced during this conversion process which can result in sub-optimal decisions being made. The collection and handling of information for a water authority must therefore be organised. Asset management systems generally consist of three major constituents: inventory, programmed action, and optimisation. The institutional capacity needs of water authorities in developing countries require greater emphasis on the first of these two constituents. A pragmatic and simple-to-use Integrated Water Asset Management System (IWAMS) has been developed comprising water meter, leakage control and incident management modules. A water audit and water balance module facilitates the determination of the levels of unaccounted for water, as well as the unit cost of leakage. Water mains rehabilitation priorities can be established through the representation of various data collected in the form of a common severity rating that aids decision making.

Markov Model for Storm Water Pipe Deterioration

Effective management of storm water pipe networks requires an accurate assessment of the structural condition of the pipes. Indeed, the recent introduction of Australian accounting standard AAS27 compels local governments to prepare annual financial statements, including the depreciated value of their storm water network. A rational approach to assessing depreciation is to base it on structural deterioration. This study presents a Markov model for the structural deterioration of storm water pipes. The model is calibrated, using Bayesian techniques, to structural condition data from the storm water asset database of the Newcastle City Council (Australia). It is shown that the Markov model is consistent with the data. The pipe characteristics of diameter, construction material, soil type, and exposure classification were found to influence the deterioration process. It is also shown that the depreciation methods required by AAS27 significantly overestimate the structural deterioration.