No abstract

Water companies are now required by the Drinking Water Inspectorate to install continuous monitoring for Cryptosporidium at all sources (surface water and groundwater) where there is deemed to be a significant risk of Cryptosporidium oocysts being present in the final water. This has substantial cost implications, not only for the one-off installation of monitoring equipment, but also for the daily collection and analysis of samples. This paper describes a methodology that has been used by Southern Water to screen all their groundwater sources, in order to identify those which are at significant risk of Cryptosporidium contamination, and which therefore need continuous monitoring. The methodology is a semi-quantitative scoring technique, developed by the authors, which produces a ranked list of sources and enables action to be prioritized. The methodology is designed to operate with a level of information and data easily available to a water company, overcoming the problems of significant data requirements associated with probabilistic methodologies.

Tullow Kenya BV, with joint-venture partners, holds the exploration licences for several onshore blocks in Turkana, northern Kenya, and an exploration/appraisal drilling programme is well advanced. Turkana is one of the driest parts of Kenya, so finding, developing and managing water supplies presents many challenges. The challenges have been solved by applying methods and procedures from the water utility industry; the way in which this has been achieved is explained.Water is required by Tullow for drilling, field camps, civil engineering and community water supply. Larger quantities of water will be required in the future for reservoir injection. Water supplies to meet current demand are provided by a dispersed network of boreholes, exploiting groundwater in local shallow aquifers. Water is distributed from sources to demand centres by a combination of pipelines and tanker trucking. The demand centres include permanent installations but also many short-term sites. Matching supply from widely-scattered sources, with different yields and water qualities, to ever-shifting patterns of demand is the same puzzle faced by public water utilities.Key indicators used in the water sector include: deployable output, outage, water available for use, headroom and potential yield, and these have been successfully applied in Turkana. The application of water resources management and reporting procedures from the water utility industry to an oil operation in a region that is semi-arid, remote and insecure, with fierce competition for scarce water resources, has proven to be a powerful technique. Given that most of the source boreholes yield relatively fresh water, there is a big responsibility on Tullow to use water wisely and to be able to demonstrate that it is doing so. The techniques also allow plans to be made for when and where new water sources (from groundwater and surface water) need to be brought on stream to stay ahead of the demand curve.Yields from individual water sources vary considerably with the seasons and from year to year. Defining the long-term sustainable yield of any particular source is not straightforward and must be done using a standard technique if the results are to have any value for comparison, reporting or auditing. Tullow has addressed this and other water resource management issues by the novel approach of treating its operations in Turkana as if it were a water utility.