HydroCon Pipe Systems The sketches and illustrations below have been prepared by HydroCon over a period of years and reflect progressive development of HydroCon stormwater treatment systems. Scroll down to bottom to view earliest designs. More recent designs appear towards the top. Click on images to enlarge. Consulting engineers responsible for designing HydroCon stormwater treatment systems are identified elsewhere against relevant installations. Pipe & pit terminology  Sketches  1  2  3 16.  HydroCon sketches were used by Canada Bay Council in Sydney as a basis of a major stormwater harvesting and re-use project. Construction of the project - at Powells Creek Reserve, Concord West - commenced in March 2008. 15.  The design in Figure 15 relates to a stormwater treatment project in Auckland, New Zealand. Runoff from a carpark was intended to be treated through HydroCon pipes and discharged back into existing stormwater drains. Levels across the carpark required the use of DN300 HydroCon pipes. Since cover above the pipes in several areas was less than the recommended 430 mm, a reinforced concrete slab over the pipes was incorporated into the design. Where the cover was 430 mm or more, an aggregate product called GAP 40 (cement stabilised at 2% by volume) replaced the concrete slab. GAP 40 was also recommended as bedding for the DN300 HydroCon pipe and the PVC stormwater pipe shown to the right of the HydroCon pipe in Figure A-A and beneath the HydroCon pipe in Figure B-B. Modifications (shown as annotations and colouring) to the HydroCon designed system were made by GHD Auckland. 14.  This figure shows stormwater passing through a HydroCon inlet pit with a horizontally positioned filter, discharging into a standard HydroCon pipe filtration system. Collection pipes (PVC DN100 drainpipe) at the base of the trench (middle section) convey treated water to an outlet chamber (pit on right), which controls the discharge of treated water. The HydroCon pipes serve to remove any contaminants not filtered out in the primary chamber. The overall design acts both as a stormwater treatment and detention system. 13.  Aquifers can be created with HydroCon pipes as shown in Figure 13. 196 litres of stormwater runoff can be stored in 1 linear metre of HydroCon pipe. Water filtrates through the permeable walls of the HydroCon pipe into the surrounding media. The media generally has a void space of around 30% enabling additional storage of water. Water is discharged through slotted drain pipes at the bottom of the trench. The discharge rate can be controlled through the installation of throttling devices. It is estimated that system configuration shown in Figure 13 would be able to store 1.79 m3 of water per linear metre of trench. 12.  This sketch was generated in response to a request from a stormwater engineer for options concerning location of HydroCon pipe systems on restricted areas of land. The sketch envisages the HydroCon system being placed under the concrete floor of the building (house) during construction. The building would in effect be sitting over its own aquifer, collecting water from the roof and treating and storing the collected water under the building. Water is pumped out of the reservoir as required. A HydroCon inlet pit is shown at one end (top of sketch) and a harvesting/pump pit at the other end. Scale 1:100 11.  HydroCon pipe systems can be used under traffic surfaces, permeable or impermeable pavements, or vegetated areas including swales. Figure 10 shows DN500 HydroCon pipes under two types of superstructure. The system is 'confined' in that treatment takes place isolated from the surrounding environment. The trench containing the pipes is lined with an impermeable fabric - shown by the dashed line around the perimeter of the trench. The media selected in this case is coarse sand - the best media for filtering out any remaining contaminants. Slotted PVC DN100 pipes at the base of the trench allow treated water to be harvested for re-use or discharged into existing waterways. 10.  'Confined' pipe and trench treatment systems are particulary suited to conditions where infiltration is slow or undesirable eg clay soils. Figure 10 shows the simplest type of confined system, with the trench lined with an impermeable material. Slotted collection pipes (not shown here) would be placed at the lowest point of the trench ie right hand bottom corner in Figure 9 to allow discharge of treated water. HydroCon pipes in this design are placed under vegetated non-trafficable surface. For trafficable surfaces, depth of cover should be at least 430 mm and comprise a suitable load bearing material. 9.  HydroCon pipes can be used in comjunction with vegetated swales. On the left of Figure 9 is a cross section view of HydroCon pipes within a sand/gravel filled trench under a 300 mm high grass swale. A longitudinal view of the HydroCon system is depicted on the right. The pre-filtering chamber is shown with a throttle controlled overflow allowing excess water to discharge to a lower level HydroCon unit or alternatively to receiving waters. Treated water is infiltrated to supplement groundwater. Recommended minimum depth of the groundwater level to the base of the trench is 1 m. 8.  HydroCon pipe systems can be used under sealed or permeable pavements as shown in Figure 8. Pipes can be arranged in numerous configurations, inluding in parallel lines as also shown in Figure 8. The depth of cover normally recommended for HydroCon 500 pipes is 430 mm. HydroCon does not yet produce DN300 pipes in Australia. 7.  By 2004, improvements had been made to the pre-filtering chamber. Overflow and access for removing sediment had been combined in a centrally located tube within the filter element as shown in Figure 7. The efficiency of the vortex (sediment separator) had also been refined. At this stage, HydroCon permeable pipes are still an integral component of the treatment system. 6.  Figure 6 shows modification of access for sediment removal. Combining overflow and cleaning access via a single vertically positioned tube was a later development. 5.  The system shown in Figure 5 is the same design as in Figure 4, except the inlet pit achieves full pre-treatment capability through the inclusion of a centrifugal sediment separator and an upward flow porous concrete filter. This new addition, which is an early form of HydroCon's HydroFilter product, takes pressure off the HydroCon pipes and allows them to perform final treatment or 'polishing' functions. A patent was applied for in Germany by HydroCon GmbH on 11 July 2002 and granted on 29 January 2004 (DE102 31 241 A1 2004.01.29). Components in Figure 5 are listed separately. 4.  Figure 4 shows further development of the HydroCon system through the addition of a gross pollutant trap to filter out debris in stormwater before it enters the pre-filtering pit. A chamber is also shown added to the outlet end of the system to regulate excessive flows. Treated water infiltrates through the HydroCon pipes into the ground. Excessive flows are discharged either into another HydroCon pipe section or to receiving waters. 3.  The next step in the product development process was to incorporate pre-treatment into the process, This was done by placing a structure horizontally in the inlet pit below the inlet as shown in Figure 3. The structure assisted in separating the sediment, which fell by gravity to the bottom of the pit. Water then flowed upwards through a porous concrete filter and into the HydroCon pipeline. The complete pre-treatment concept was later developed into the HydroCon HydroFilter™. 2.  HydroCon pipe systems invariably involve an inlet pit connected to a line of pipes laid at zero gradient. Figure 2 shows a small pipe system treating runoff from the roof of a house. The blue horizontal arrows in Figure 2 indicate the direction of flow, while the vertical blue lines show infiltration direct into the substrate. A flushing pipe can be inserted into the stopped end of the last pipe in the pipeline to provide a means of cleaning. Flushing pipes are unnecessary where industrial vacuum cleaning services are available. 1.  The simplest HydroCon pipe system is one that is placed within a trench and back filled with a suitable filtration medium eg clean coarse sand or 5 - 20 mm crushed rock. Treated water is infiltrated directly into the ground to supplement ground water or underlying aquifers.