Sewer line failures are a major cause of stream impairment in urban areas. While many sewer line failures can be readily identified and corrected, other failures may be more difficult to remedy. This paper examines the general problem of sewer line failures. Specifically, we discuss 1) the observed causes of sewer line failures, 2) methods for determining which streams are being affected by sew...

Biological nutrient removal (BNR) technology can suffer poor performance or complete failure due to the fastidious nature of the bacteria used in the system. The bacteria involved necessitate strict operating conditions, multiple zones with one or more recycling lines, carbon source augmentation, and efficient aeration. For wastewater treatment plants receiving significant combined sewer overfl...

A d-gem is a {+,−,×}-circuit having very few ×-gates and computing from {x} ∪ Z a univariate polynomial of degree d having d distinct integer roots. We introduce d-gems because they could help factoring integers and because their existence for infinitely many d would blatantly disprove a variant of the Blum-Cucker-Shub-Smale conjecture. A natural step towards validating the conjecture would thu...

Sewers are aging, expensive assets that attract public attention only when they fail. Sewer operators are under increasing pressure to minimise their maintenance costs, while preventing sewer failures. Inspection can give early warning of failures and allow economical repair under noncrisis conditions. Current inspection techniques are subjective and detect only gross defects reliably. They can...

Inflow/infiltration (I/I) and infiltration/exfiltration (I/E) are interactive processes which dynamically affect sewer and groundwater performance. The incidence and condition of "critical" sewers in the UK are identified together with methods of quantifying I/I and I/E as well as their impact on wet weather sewer performance and on urban groundwater pollution. Whilst the impacts of sewer trenc...

Separate sanitary sewer systems are designed to convey sewage waste from municipal areas to a central treatment facility; they are not designed to handle water associated with precipitation events. However, intercept of groundwater (infiltration) and of flows through manholes or unauthorized connections (inflows) introduces rainwater into the sanitary sewer system. Infiltration/Inflow (I/I) inc...