Seqwater developed the Land Use Risk Tool (LURT), an online iterative decision support tool, to assist local government and others better understand Seqwater’s site and design requirements for onsite wastewater treatment systems (OWTS) in drinking water catchments.

OWTS are generally the only available means for treatment of domestic wastewater in areas that are not serviced by reticulated wastewater networks. Wastewater poses an inherent risk to drinking water supplies due to its microbial and chemical constituents.  This includes risks associated with human pathogenic bacteria, protozoa and viruses as well as nitrogen and phosphorous which may result in undesirable ecosystem changes (e.g. algal blooms, eutrophication).  If not appropriately treated, domestic wastewater presents a potential risk to the drinking water supply, the environment and water-based recreational activities in the catchment.

Seqwater partnered with Cardno to develop this best practice tool and the tool has been peer reviewed by the Queensland University of Technology. The LURT is also brought up by Seqwater’s Development Guidelines and requires proposals for onsite wastewater treatment systems to attain a certain risk rating in order to be accepted.

The online tool asks users to answer a range of questions about the location and design of their proposed OWTS.  Questions cover site features such as proximity to watercourses and flood immunity, slope, soil and dwelling characteristics as well as proposed system features including system type and irrigation and/or liquid disposal method.

Based on answers provided about site features, the tool guides users through the design parameters and in doing so assigns a risk rating to each proposal.  This risk rating can be lowered either by using mitigation measures at the end of the tool, or, if an acceptable risk rating still can’t be achieved, by changing system siting and other basic design elements.

A medium or lower risk rating is required in order to comply with the provisions of the Seqwater Development Guidelines. Once obtained, the tool will generate a draft set of conditions that are recommended by Seqwater.

Whilst the tool does not cover every conceivable type or combination of system possible, it does cover the most common situations encountered in drinking water catchments. Where unconventional or non-compliant systems are proposed, Seqwater requests that designs are submitted for a case-by-case assessment to [email protected].

When it comes to soil characteristics, the LURT considers several soil-related features when examining risk arising from an onsite wastewater system.  This first is soil permeability which is an indication of much liquid the soil can hold before seepage occurs and the second is soil category, as determined from Australian Standard AS 1547:2012. 

This information is gathered from site and soil evaluation testing carried out by an onsite wastewater system designer and used to calculate the specific design loading/irrigation rate for the disposal system.  LURT limits what types of systems can be proposed based on soil permeability and soil category results obtained as well as slope.

LURT has been designed to ensure that the draft conditions are only generated for those proposals which obtain a risk rating of medium or lower. 

As it is not possible for the tool to adequately capture all possible system designs or combinations and given that some sites are significantly limited, in some situations, it can be very difficult to achieve a ‘Medium’ or below risk rating. In these instances, a case by case assessment of proposals can be undertaken.  To have a case by case assessment undertaken please contact Seqwater at [email protected] who will review your site and soil evaluation and waste water design report and provide advice on facilities design.   

The LURT can be used by local government, onsite designers and even land owners. It relies on inputting information typically found in a site and soil evaluation and waste water design report.

Most proposals for onsite wastewater systems in a drinking water catchment in SEQ are sent to Seqwater by a local government seeking advice on plumbing applications.  Where advice is sought, Seqwater reviews each wastewater design and provides advice which includes recommended conditions of approval. The local government considers these and may include them on any plumbing permit (in part or in full) as they deem appropriate.

Additionally local government and state agencies ( e.g. Economic Development Queensland and the Office of the Coordinator-General) may request third party advice on development applications where located in a drinking water catchment.

For assistance with using the tool, you can:

• email the team at [email protected] with your contact details