WATER SENSITIVE URBAN DESIGN & CONSTRUCTED WETLANDS
IN-LINE END-OF-LINE PRIMARY TREATMENT SOLUTION
Urban Asset Solutions has also developed a standard modular trash rack system suitable for most stormwater outlet applications. The Ecosol Trash Rack is a robust and modern primary treatment filtration system for use where there are cost or space constraints, or specialised cleaning equipment is not available. The unit captures and retains more than 93% of solid pollutants larger than >2000μm, although, in practice, it has been found to collect much smaller particles, including fine sediments.
Easily installed, the Ecosol Trash Rack’s simple design overcomes any adverse hydraulic impact traditionally encountered with generic, direct screening, trash racks that often block in first flush flows. By incorporating filtration nets into the design its operating life is significantly improved with an increased screening surface area and a larger pollutant holding capacity.
It can be installed not only end-of-line at almost any pipe outlet discharging to beaches, rivers, and creeks but also in-line within open channels.
The Ecosol Trash Rack consists of a structurally engineered stainless-steel frame with support legs and a removable heavy-duty UV-stabilised polyethylene filtration net that can be easily lifted out for cleaning and maintenance using a small crane truck. This overcomes the problem usually encountered with traditional, fixed direct-screen designs, which are often difficult and expensive to clean.
The system has been designed to provide a robust and durable cost effective primary treatment system that captures and retains solid pollutants conveyed in stormwater conduits.
The Ecosol Trash Rack is usually installed at drainage discharge points prior to the receiving waterway, enhancing not only water quality but also site aesthetics by stopping significant volumes of gross pollutants entering the natural waterway and damaging the existing marine life and vegetation.
The Ecosol Trash Rack is a compact, efficient, and cost effective solution to the ever-increasing problem of water pollution. Key to its success is the robust, engineered structural frame and filtration net that provides a significantly-greater screening area than that of traditional direct-screening trash rack designs.
The table below highlights the key performance specifications for typically-sized single module Ecosol Trash Rack units to suit cylindrical pipes up to 1050mm and for box culverts up to 900mm wide by 900mm high. Figures quoted are for single units – for multi-units multiply the figures by the number of single unit modules required for your site.
Ecosol can design, model, install and maintain systems specific to your site. This includes:
Multiple module Trash Rack Systems
Designs inclusive of sediment fore-bays for improved retention of coarse sedimentation
Wing wall/headwall construction
Hard stand and access ramp for maintenance
Off-line systems with diversion weirs for high flow open channel applications
Systems inclusive of overhead hoists for easy lifting and removal of full net modules for cleaning.
At Ecosol we can provide a complete turnkey service with the purchase of your trash rack, including site measure, modelling, structural design, fabricate, installation and maintenance of your Trash Rack system.
In 2012 the University of Adelaide (Engtest Civil, Environmental and Mining) completed extensive testing and measurements of the products capture efficiency, hydraulic performance and durability at varying flow rates its and compiled a comprehensive product performance report (Performance Review of the Ecosol Net Guard) on which the Ecosol Modular Trash Rack Design is based. Testing also included a detailed reviewing of on both past and present field and laboratory testing data in comparison with current testing data to determine meaningful, conservative product performance results.
The results of this extensive product testing and verification phase is summarised in the table below.
As with all filtration systems, the Ecosol Trash Rack should be cleaned regularly. The cleaning frequency, and the cost, depends heavily on the catchment size, type, estimated pollutant loading and rainfall.
The Ecosol Trash Rack can be easily inspected visually to determine whether it needs cleaning. Ecosol recommends the unit is inspected every two months or after any major rain event to determine if it needs to be cleaned.
One of the key advantages of the Ecosol Trash Rack is that a small crane truck can easily lift the individual filtration netting modules for cleaning thereby eliminating any manual handling risks and the need for specialised cleaning equipment. As the unit is a dry system there is a reduced likelihood of captured contaminants causing any significant adverse environmental impact or nuisance (e.g. odours and putrefaction).
Cleaning is recommended before the filtration net reaches its capacity to avoid flows bypassing the system and discharging untreated to the receiving waterway. The figures below give a broad guideline about the catchment size and the number of cleans required annually for single module systems.
Cleaning frequencies are based on typical pollution loads of 0.280m3/ha/year for gross pollutants generated on typical fully developed urban catchment. Excludes coarse sedimentation typical urban pollutant loads.