An investigation into an alternative on-site stormwater detention structure to increase capacity and reduce spatial footprint and economic impact

Stormwater runoff management is a subject which is ever-changing and multifaceted in its resolution options. As typical residential lots become smaller, so too does the available space which can be allocated to stormwater management on these restrictive lot sizes. Various options currently exist which work to allow for the infiltration of this material, alleviating the issues associated with elevated impervious areas on a developed block of land. Given the obvious increase in population and subsequent decrease in average sizes of residential lots, the need for effective and spatially conservative stormwater management systems is becoming more prevalent. This report will serve to analyse the effectiveness of the current stormwater detention structures and propose an alternative structure type which increases storage capacity and reduces spatial footprint and economic impact. Currently, either Plastic Modular Detention Systems or Concrete Stormwater Detention Systems dominate the residential and commercial market for stormwater detention. The use of Concrete Stormwater Detention Systems are now more common, yet they have an increased cost in design, supply and installation when compared to their plastic counterparts. Additionally, the storage capacity to supply and installation cost ratio seems to be skewed heavily toward these systems being exorbitantly expensive, whilst still maintaining a very large footprint. Alternatively, plastic structures carry their own burdens relating to confidence in material type, Loading Capability and lifespan. The proposal intends to investigate currently available structures and establish their benefits or drawbacks. This will include experiments and research which test the effectiveness of the most common currently available structures. This investigation should provide some guidance as to the most suitable type of structure for a given application, as well as provide guidance to the direction of an alternate design. Additional investigation into storm events and rainfall frequencies which occur in residential and commercial situations will confirm the storage requirements on typical lots. This will be compared to the recommended storage volumes put forth by Local Council. This will provide guidance on the storage and seepage requirements for the alternate design. The proposal aims to present an alternative to the current systems which are available to combat stormwater runoff. This will entail design of an alternative system which involves rectangular pre-cast concrete units which can be used to create a detention structure that is both flexible and economical in installation and production methods. The system shall also bring the confidence associated with reinforced concrete stormwater structures and couple this with the spatial footprint and economic advantages of their plastic counterparts