Unacceptable Inflow and Infiltration (Clean Water) is Entering Sewers in Brand New Construction
Barbara has been studying the phenomenon of inflow and infiltration in brand new sanitary sewers since 2005, and has presented dozens of presentations on the topic at a variety of industry and non-industry forums (WEF, WEAO, CWWA, NRC, NWWBI, OPIA, OBOA, ICLR Board, etc.).
Once establishing Norton Engineering, Barbara initiated the development of a "Project to Reduce Unacceptable I/I in New Subdivisions" with direct funding from municipalities working to reduce their I/I. Currently, Norton's work in this area is funded by a variety of municipalities across Ontario, as well as NRC and CSA.
Through flow monitoring at the downstream end of new subdivision sanitary sewers across Ontario (and likely beyond), it has been determined that new subdivisions are "leaking" and allowing unacceptable levels of groundwater and rainwater to enter these pipes. Fifty out of fifty-one subdivisions for which flow monitoring has been collected exhibit unacceptable (as determined by the municipality) levels of I/I. This has significant, expensive, long term implications for municipalities, including compromising their ability to cope with the more frequent and peakier rainfall events expected with the advent of climate change.
The reasons for this phenomenon are myriad and complex. There are gaps in Codes & Standards on both the public and private sides (particularly as regards pipe construction on the private side). Existing Codes and Standards are not being applied (particularly as regards leak testing) in the majority of municipalities. Inspectors do not always understand the reasons for the provisions in the Codes & Standards (although Norton's work is starting to change this). City departments typically exist in silos, so there is insufficient cross-pollination of best practices in construction. The consulting engineer responsible for the design and inspection of the new construction is typically hired by the Developer, so a conflict of interest exists (since the Developer's interests and the municipality's interests do not necessarily align). There is confusion regarding the Professional Engineer's role around signing off on new construction. And, inspection staff report a *perception* that insisting on excellence in construction may result in reprimand, since new development is very important to municipalities' bottom line.