I recently came across an Australian paper which looks at the impact of concrete pipes and PVC pipes on the chemistry of different water types and what changes were made to the quality of the water. The paper, Impact of concrete and PVC pipes on urban chemistry by PJ Davies, I.A Wright, O.J Jonasson and S.J Finlay, was first released in 2010 and is still highly relevant today given the continued use of concrete pipes for urban water infrastructure.
This study was one of the first in Australia that looked at not only the change in water chemistry based on the water collection, but also the in-transport processes of pipes and how they can impact on water chemistry. Missing in any previous discussion or study to date is the role of the drainage network itself with respect to contributing to the in-transport pollution load and also the natural ionic balance and how this may impact on ecological health.
The challenge for those within the urban water profession is both to protect both water quality and the ecological health of urban waterways (Aplin 2002). The study found that at a catchment scale, concrete pipes, as a conduit for stormwater, have a greater negative effect on water chemistry than PVC Pipes for certain chemical attributes.
Summary from the paper
Three types of water (roof water, reference creek water and urban creek water) were…circulated through a concrete pipe or PVC pipe for 100 min and measured for a range of water chemical attributes. Roof water and water from the reference creek reported a significant increase across a range of analytes, most notably bicarbonate and calcium levels when passed through the concrete pipe, while water from the urban creek changed a lesser amount.
When passed through the PVC pipe the changes in water chemistry were significantly less for roof water and urban creek water. The data suggests that in-transport processes from concrete drainage systems are having a significant influence on water chemistry, particularly where inflow is acidic.
The implications of this study point towards a need to consider the type of materials used in urban drainage networks if water chemistry and stream ecostream health is to be protected.
Other notable findings from the paper
- The concrete pipe was associated with the largest changes in pH
- Total alkalinity (bicarbonate) levels also increased after the experiment with the concrete pipe
- Calcium concentrations also displayed large and highly significant increased for all water types exposed to concrete
- The increase in potassium concentrations was also highly significant, increasing between 100 and 700%, in all water types exposed to the concrete pipe. PVC pipes did not result in an increase in potassium
Download the paper Impact of concrete and PVC pipes on urban chemistry by PJ Davies, I.A Wright, O.J Jonasson and S.J Finlay here