Low Impact Development Design Research Articles

WATER QUALITY AND FLOW PERFORMANCE-BASED ASSESSMENTS OF STORMWATER CONTROL STRATEGIES DURING COLD WEATHER MONTHS

WATER QUALITY AND FLOW PERFORMANCE-BASED ASSESSMENTS OF STORMWATER CONTROL STRATEGIES DURING COLD WEATHER MONTHSLack of widespread adoption of Low Impact Development (LID) designs in northern climates is in large part due to concerns about poor winter performance. An examination of six varied LID designs in contrast with conventional BMPs and manufactured systems between 2004 and 2006 illustrated that seasonal functionality was evident for many systems however the LID designs were consistently top...Author(s)Robert M. RoseenJames J. HouleThomas P. BallesteroPedro AvellenedaJoshua BriggsGeorge FowlerRobert WildeySourceProceedings of the Water Environment FederationSubjectSession 9: Performance of Green Infrastructure Practice: Water Quantity & QualityDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2008ISSN1938-6478SICI1938-6478(20080101)2008:6L.562;1-DOI10.2175/193864708790894674Volume / Issue2008 / 6Content sourceSustainability ConferenceFirst / last page(s)562 - 564Copyright2008Word count239

Large-Scale Application of Biofiltration Swale Runoff Management Practices

Retaining rainfall where it lands is a fundamental benefit of Low Impact Development (LID). The Delaware Urban Runoff Management Model (DURMM) was developed to address the benefits of LID design. DURMM explicitly addresses the benefits of impervious area disconnection as well as swale flow routing that responds to flow retardance changes. Biofiltration swales are an effective LID BMP for treating urban runoff. By adding check dams, the detention storage provided can also reduce peak rates. This presentation explores how the DURMM runoff reduction approach can be integrated with detention routing procedures to project runoff volume and peak flow reductions provided by BMP facilities. This approach has been applied to a 1,200 unit project on 360 hectares located in Delaware, USA. Over 5 km of biofiltration swales have been designed, many of which have stone check dams placed every 30 to 35 meters to provide detention storage. The engineering involved in the design of such facilities uses hydrologic modeling based upon TR-20 routines, as adapted by the DURMM model. The hydraulic approach includes routing of flows through the check dams. This presentation summarizes the hydrological network, presents the hydrologic responses, along with selected hydrographs to demonstrate the potential of design approach.

Storm Water Low-Impact Development, Conventional Structural, and Manufactured Treatment Strategies for Parking Lot Runoff

Eleven storm water treatment strategies were evaluated for water quality performance and storm volume reduction during rainfall–runoff events between September 2004 and August 2005. Evaluated treatment strategies included structural best management practices (BMPs) (swales, retention ponds), low-impact development (LID) designs (treatment wetland, filtration and infiltration designs), and manufactured BMPs (filtration, infiltration, and hydrodynamic separators). Contaminant event mean concentration, performance efficiency, and mass-based first flush were evaluated for storms with varying rainfall–runoff characteristics. Previous research demonstrated that treatment performance of storm water control measures varies widely in response to site-specific contaminant loading functions. For that reason, the devices were tested in parallel, with a single influent source providing uniform loading to all devices. Treatment strategies were uniformly sized to target a rainfall–runoff depth equivalent to 90% of the annual volume of rainfall. Under the parallel and uniformly sized configuration, a normalized performance evaluation is possible because treatment strategies of the same scale receive runoff from events of the same duration, intensity, peak flow, volume, antecedent dry period, and watershed loading. Runoff constituent analyses included total suspended solids (TSS), total petroleum hydrocarbons-diesel, dissolved inorganic nitrogen, and total zinc. Several water quality parameters (temperature, dissolved oxygen, pH, conductivity) were monitored as real-time data. Performance evaluations indicate that several LID designs have removal efficiencies of 80% to 100%. In contrast, conventional structural BMPs perform poorly for most measures except for the pond with TSS. The manufactured systems tended to vary widely and were dependent on the design and contaminant of interest.

Green Engineering Principles Promote Low-impact Development

This article considers the use of low-impact development (LID) which integrates environmental concerns with land development, focusing on water and pollutant balances. Urbanisation makes drastic changes to the hydrological characteristics of land: materials used contribute higher pollutant loads and natural filtering is reduced. Pollutant sources in runoff water include fertilisers, animal wastes, cars, fuels, herbicides and pesticides. LID design attempts to replicate pre-development hydrologic conditions as closely as possible. Elements are present in site design and preparation, and in runoff management practices such as bioretention areas to collect and treat runoff water. Obstacles to using LID include access requirements for certain sizes of vehicle, safety concerns and public health issues, beside economic concerns. Using LID solves some environmental issues but raises others such as the ownership (for treatment purposes) of captured pollutants. Incorporating LID should not encourage urban sprawl.