At NY Civil Engineering, we believe that before we ask anything, we must first give to our clients and future clients. That's why we've answered our most frequently asked questions below.
So...What is Stormwater Management?
Stormwater Management is the process of transporting stormwater runoff and overland flows impacting a site from the property into an adequately designed network of pipes, rainwater tanks, absorption systems or on-site detention systems. 'Blueprints' of pipes, pits, rainwater tanks, OSD tanks and other infrastructure are called 'Stormwater Management Plans'. These plans are generally necessary for every residential, industrial and commercial development across Sydney.
NY Civil Engineering provides quality Stormwater Management Plans using the industry's best practice AutoCAD drafting software. Our experience with Local Council's across Sydney allow us to deliver our projects in record time and with a high level of detail.
What is On Site Detention (OSD) and why do I need it?
On Site Detention is the temporary storage of water on a property before allowing it to discharge into the downstream waterway. The reason behind it is, as more and more area becomes urbanised and goes from being previous vegetated to impervious paved area, less and less water is absorbed into the ground, and more water leaves the site as runoff. As cities develop, this increase in runoff on a large scale can cause flooding of downstream and low-lying areas, as the increased volume of runoff has to go somewhere. OSD is a way of slowing the runoff down by temporarily storing it on private property and releasing it in a controlled manner. Almost every Council in Greater Sydney requires OSD to be implemented on developments of differing sizes. OSD storage can come in the form of below ground tanks, above ground vegetated basins or above ground rainwater tanks, depending on the respective Council Controls.
NY Civil Engineering has experience in designing OSD throughout the differing Local Government Areas of Sydney and we work to Design you the most efficient and cost effective system, working with your preferred building design. We adopt the latest design and modelling software and spend the time needed in detailing an OSD system ensured to integrate seamlessly with your proposal.
What is a 'flood report' and why does Council ask for it?
Much of Sydney is affected by flooding, This is broken up into two categories, 'overland flow' and 'mainstream flooding'.
Overland flow is the impact of runoff from local upstream catchments, caused by runoff in large storm events concentrating onto properties causing significant sheet flow of water. Mainstream flooding is the effect of creeks and rivers over-topping their banks when much larger catchments experience high rainfall. Both types of flooding can be dangerous to people and property, which is why Council requests that a 'flood study' or 'flood report' is prepared with any application for development in a flood impacted area.
NY Civil Engineering utilises the latest in 2-Dimensional flood modelling software to accurately model the rainfall, catchment and floodwater behaviour, and work with you to design your development reaching the safest and most economical solution.
Our services range from simply flood certificates confirming flood levels, to in-depth flood studies, and each quote is tailored to suit the needs of your project. For more information, get in touch with one of our friendly staff to guide you through the process.
What is Water Sensitive Urban Design?
Water Sensitive Urban Design (WSUD) is an approach to treating runoff from urbanised catchments or developments for pollutants such as Nitrogen, Phosphorus, Suspended Solids and General Waste. This is generally a Council requirement for larger developments such as townhouses and apartments due to the cost involved.
The treatment system can often involve landscape elements such as vegetated swales or basins, or proprietary 'man-made' products such as cartridge-type filters housed in below ground tanks. These systems generally integrate with the natural environment or are hidden from site, and work to filter water from pollutants thereby increasing the quality of water entering creeks and waterways. On a large Scale WSUD promotes healthy marine and estuary environments and their respective flora and fauna.
At NY Civil Engineering, we used the industry standard 'MUSIC' software to model the natural water cycle and suggest the treatment options most suited to the project budget and environment. We design each water treatment device to function as part of a whole system to minimise cost and enhance the functionality and aesthetics of each development.
Why is Every Council Different?
Stormwater management practices vary between every Council in Sydney. This is due to a number of environmental factors such as soil conditions, susceptibility to flooding and the Council's existing infrastructure. NY Civil Engineering have made it our business to be across all Council's respective guidelines to provide our clients a tailored solution.
Some Council's have topography consisting of mostly sandy soils, particularly ones closest to the ocean. Drainage in these sandy locations can be in the form of 'absorption' or 'infiltration' systems, where domestic runoff can be used to recharge groundwater. In locations where the soil environment is generally clay-like, water cannot be absorbed into the ground and must be managed in other ways.
Locations high in a catchment generally require runoff from developed areas to be limited by means of On Site Detention (OSD). This works to prevent the increase in runoff from the catchment being magnified and causing flooding in lower areas of the catchment. This can cause differing OSD requirements within a Council, and is also evident between Councils. For example, Western Sydney suburbs drainage into Parramatta River may experience more stringent OSD requirements as flows from these areasimpacts the entire Parramatta River and expansive downstream area.
More modern Council's may have allowed for greater volumes of runoff in their drainage infrastructure, reducing the necessity of OSD in private properties. More established areas such as inner suburbs of Sydney may be relying on under-capacity infrastructure which is not financially feasible to replace. In these scenarios, it is likely that drainage requirements for private properties are more stringent to compensate for a lack of infrastructure.
At NY Civil Engineering, we've undertaken projects across Greater Sydney and are familiar with all different Councils' policies, development control plans and technical specifications, which allows us to ensure the right system is designed for the right location and development. We pride ourselves on our highly detailed designs which lead to fewer requests for additional information, and remove the risk of mistakes during construction.
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