Performance, environmental and cost comparisons of onsite detention (OSD) and onsite retention (OSR) in re-developed residential catchments

Abstract

On-site detention (OSD) of storm runoff decreases catchment peak flows through the routing effect of temporary storage; on-site retention (OSR) achieves the same objective by abstracting part of the urban flood wave and passing the retained water to disposal on site. The investigation explored both strategies applied to a set of hypothetical present/re-developed urban catchments ranging in size from 14 ha to 210 ha. Comparisons were made on the basis of site storage required (SSR) to achieve the same global peak flow reductions, environmental aspects and cost. OSR practice was shown to out-perform OSD generally in medium-large catchments with respect to SSR and, hence, cost. The retention option also has clear environmental benefits that fall beyond the scope normally ascribed to OSD practice. The paper cautions against use of OSR in unsuitable circumstances.

Urban nitrogen biogeochemistry: status and processes in green retention basins

“…City retention devices have been given numerous names such as retention basins, detention basins, detention tanks, retention ditches, and retention ponds. Scott et al (1999) defined 'detention' as the holding of runoff for short periods to reduce peak flow, followed by later release into watercourses to continue in the hydrologic cycle, and 'retention' as the procedures and schemes whereby storm water is held for considerable periods causing water to continue its hydrologic cycle via infiltration, percolation and evapotranspiration, and not via direct discharge to watercourses. In the Phoenix metropolitan area, stormwater management systems have both retention and detention functions.…”

“…Since the 1960s, in most developed countries, the old practice of 'collecting and disposing urban runoff as completely and as quickly as possible' has been deemed mostly impossible with the fast pace of urbanization, and is increasingly being criticized as environmentally insensible (Scott et al 1999). Instead, multilevel devices have been created to reduce peak runoff volume (and the pollutants in runoff).…”

Introducing leaky-well concept for stormwater quantity control in Dhaka, Bangladesh

“…For this particular catchment, WSUD infiltration technology was capable of diverting up to half of the natural groundwater input, which was able to maintain low flow characteristics. Scott et al (1999) investigated the impacts of WSUD to reduce stormwater runoff peak flow in urban catchment ranging from 14 to 210 ha in Parramatta, New South Wales, Australia and remarked that on-site retention system was better option for medium to large sized catchment. These cases support for introducing of leaky-wells to stormwater quantity control in urban landscape including Dhaka.…”

Nonpoint Sources

“…After determining that most stormwater detention basins were inadequate in a dense urban area in France, researchers worked with the basins and were able to present concrete examples of how to increase the effectiveness of these stormwater-BMPs (Piel et al, 1999). On-site retention practices were shown to out-perform on-site detention practices with respect to site storage requirements and hence are more economical (Scott et al, 1999).…”