Case Studies

Fieldwork Case Study

Monitoring and reporting groundwater temperature and quality

Fifth Dimension Associates (FDAL) was contracted to undertake an assessment of ground water for a business seeking to utilise its latent cooling properties. The client had an arrangement of drains which in turn flowed to a sump. Before any use could be made of the collected water, it was necessary to verify levels of contamination from foul/surface water drains, potable mains and the perched water aquifer. The water quality had to be tested to determine levels of bacteria, metal content, pH, total dissolved solids, organic chemicals and other contaminants. As well as the quality of the water, its temperature also needed to be recorded over a defined period.

For three weeks the water temperature was measured at 15-minute intervals, along with the surrounding air temperature, using precision data logging instruments. Each morning, 5-litres of water were collected for same day analysis. FDAL provided the methodology and skilled staff to collect water samples without risk of cross-contamination, as well as equipment for the temperature logging. FDAL worked in partnership with water specialist Veolia laboratories which carried out the detailed chemical and biological analysis. The sump area was considered a Confined Space and the specialist training of FDAL operatives enabled the sampling work to be undertaken in complete safety. The temperature data collected and the laboratory water analysis results were both interpreted by FDAL to provide the client with the information necessary to evaluate the viability of the project.

It was discovered that despite there being very low rainfall over the monitoring period, the submerged water level activated sump pumps which were removing vast quantities of water every day. This indicated that there was significant seepage from other drains and potable mains into the client’s drains which in turn flowed into the sump. The temperature of the water in the sump was found to be reasonably static but not sufficiently below ambient to give significant cooling benefit.

As to the water quality – the contamination levels, bacteriological, organic and inorganic – were generally in line with that expected of water taken from a complex urban drainage system. There were unexpected high levels of Tetrachloroethane and Trichcloroethane, but a street level walk above the route of the drains revealed various dry cleaners as well as hair dressing/beauty salons, a print shop and shoe-repairers, all possible sources of the contaminants.

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