In this issue



   - In this Edition



Overland Flow Paths

-  Why do we need it?



New Stormwater Quality Device

-  SPELFilter



Wrap Up

   - See you next month



Visit our website: 




07 3398 4992



Hello everyone and welcome to July edition of “Keep Things Flowing”, the monthly newsletter presented by Storm Water Consulting.

In this month’s newsletter we review a new proprietary stormwater quality treatment device and we look at the implication of disregarding overland flow paths.



Earlier this month we met with a representative from SPEL. SPEL specialise in the treatment of water and waste-water quality. It is only recently that proprietary stormwater quality treatment devices other than Stormwater 360’s StormFilter have been accepted for use in major Council’s within South East Queensland. The increased number of competitors into the market results in more versatile and cost-effective proprietary treatment systems. SPEL has developed a new proprietary device which has successfully been approved for use in a number of major Councils. The new device is called the SPELFilter and is pictured below. 


The SPELFilter has an upflow treatment process, through a spiral wrapped media configuration that maximises surface area. The benefit is excellent pollutant removal in a small footprint. Hydraulic pressure forces water through the filter media, discharges through the centre tube and out through the outlet collection manifold. Upon completion of a treatment cycle, each cartridge backwashes and effectively dislodges particulates from the filtration layers. This re-establishes filter porosity. The dislodged particles accumulate on the vault floor for easy removal during maintenance.

The SPELFilter system can be deployed in a variety of structures including manholes, precast vaults, or cast-in-place structures.

The SPELFilter System has now been approved for use in:

·         Brisbane City Council;

·         Redlands City Council;

·         Ipswich City Council;

·         Blacktown City Council;


The SPELFilter does require pre-treatment by a GPT (known as a SPEL STORMSACK) to achieve the best pollutant removal rates. If you would like any further information on the SPELFilter or STORMSACK, or have any water quality treatment questions or projects please contact our office and we would be happy to provide you with assistance.


Overland Flow Paths

As hydraulic engineers we often see people disregard the importance of overland flow paths. In many cases people have never seen water flowing through the location of the supposed overland flow path and consequently want to use the vacant space. So what are the consequences and implications if someone decides to build in an overland flow path without proper advice from a hydraulic engineer and Council approval?


The owners of the property (shown in the image below) want to build in underneath their house. The house is currently raised and overland flow passes underneath as shown by the blue hatching.

If the owners failed to implement advice from a certified hydraulic engineer and failed to gain approval from the relevant authority and built in underneath, the following consequences may occur;

·         The overland flow path would be partially blocked. The development would likely increase flood levels in the overland flow path and increase the depth and extent of flooding on neighbouring properties. This could cause damage to the neighbouring properties/dwellings.

·         The frequency of flooding occurring on the neighbouring properties would likely be increased, potentially reducing the land value of the neighbouring properties.

The above two consequences could lead to civil litigation actions by the neighbours against the owners.

·         The built in area has been constructed without the consent of the governing authority. The built in area may be required to be removed as development approval has not been obtained.

·         The built in area is not officially recognised as part of the dwelling (as no approval has been obtained) and therefore these areas cannot be advertised as part of the dwelling if selling the property.

·         As the built in area has not been approved, the whole property may be refused insurance due to the unapproved addition to the dwelling.

The above three consequences could lead to serious financial implications for the owners.

·         The built in area may not meet design requirements for the overland flow impacting the dwelling, leading to potential structural failure of the whole dwelling.

·         The built in area may not meet minimum flood immunity requirements, leading to increased potential for inundation into the built in area.

The above two issues show the potential impact of the overland flow on the dwelling itself.

As highlighted above, the consequences for disregarding overland flow areas can have serious implications. If you have any concerns about overland flow through your property or overland flow is impacting your development please feel free to contact our office and we would be pleased to assist you.


Wrap Up

That brings us to the end of another edition of “Keep Things Flowing”. If you have any questions about information presented in this month’s edition please feel free to contact our office.

As always, Keep Things Flowing!

The Storm Team



To unsubscribe from this newsletter send a reply email and you will be removed from our mailing list.