Water Company. Group pumping tests
Pumping tests were undertaken to assess individual borehole and site operational performance. This included co-ordination and overseeing of test pumping, analysis of data from individual step tests for four abstraction boreholes and combined and individual constant rate tests. Hafren Water made recommendations regarding optimum operation of the site to ensure future security of supply and to review the need for additional boreholes.
Abstraction borehole monitoring
Weir tank
The Hafren Water input demonstrated that the required yield could be obtained by pumping combinations of 3 rather than all 4 boreholes. There was thus no need to drill additional boreholes at the site, resulting in significant cost savings. Additional savings to the water company would also be achieved through reduced operating costs.
Water Company. Borehole rehabilitation
A study of the feasibility of water well rehabilitation was initially undertaken to investigate options for improving the declining yield of a source. Assessment of operational yield and pumped water levels indicated that yields had decreased by 22% in the preceding 4 years, combined with an increase in operational drawdown of 12 m. An innovative technique called AirBurst was recommended by Hafren Water and subsequently used in conjunction with traditional wire brushing and airlift to rehabilitate the screened section of the borehole.
A subsequent step test indicated a 13% improvement in borehole efficiency since the previous complete test. The water company should therefore benefit from cost savings due to reduced pump running costs as a result of the improved borehole efficiency.
Water Company. Groundwater source incident support
Historical operational yield, pumped water level and groundwater quality results were compiled and reviewed to identify the source of contamination. The data indicated little correlation between yield and contaminant concentration, however a relationship was identified between depth of activated flow horizons and the occurrence of the contamination. Recommendations were made regarding operation of the source and for rehabilitation measures to mitigate against the observed contamination.
Mineral Company, Lancashire. Water well design, installation and obtaining abstraction licence
A groundwater source of 500 m3/d was required for mineral washing at a quarry. Hafren Water undertook an initial borehole prognosis to determine the likelihood of obtaining the require yields and subsequent abstraction licence. It was found that the underlying superficial sand and gravel deposits in the area had sufficient depth and transmissivity to provide the required yield and the Environment Agency would in principle have no objections to a licence being issued.
A waterwell was designed to maximise borehole efficiencies and reduce potential for the ingress of fines to the borehole. The consents required under Section 32 (3) of the Water Resources Act (1991) were obtained and a contract let for the drilling and subsequent pump testing works.
The waterwell was constructed and tested satisfactorily and a licence later granted by the Environment Agency.
Test pumping time drawdown relationship
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