Allans Creek is a partly developed catchment within the Wollongong City Council Local Government Area. The catchment has an area of 42 square kilometres and is located to the South-West of the Wollongong CBD. The most prominent feature of the catchment is the Illawarra Escarpment, rising to the west of Wollongong up to Mount Kembla (534 m AHD) at its highest point. The sharp increase in elevation, with close proximity to the coast leads to intense orographic rainfall conditions within the catchment, resulting in high creek discharges for rare and extreme events.

An assessment of the potential sites and configuration of DCS at two locations (i.e. FM56 and FM58) has been undertaken. The assessment has been informed by the review of available data, a stream and debris source assessment, as well as a site inspection. The site inspection was undertaken jointly by RHDHV, OEH and Council personnel.