Attachment J - Sewage Treatment Assessment

Land application and area and irrigation system
A MEDLI assessment to determine the size required to adequately assimilate the irrigation of effluent to land
based on the peak design capacity of the proposed STP intended to service the site will be required. The
computer-based model will also validate the capacity of the wet weather storage required to assist in achieving
the sustainable irrigation of effluent to land. MEDLI is a Windows-based, daily time-step water and nutrient
balance model developed jointly by the CRC for Waste Management and Pollution Control, the Queensland
Department of Natural Resources and the Queensland Department of Primary Industries.
It is anticipated that a surface irrigation system will be used distribute treated effluent across the proposed
irrigation area. Standard design details for surface irrigation systems, and required setback distances from
sensitive receptors will be provided as part of the EA application.

Future works required

An application and supporting document for an Environmental Authority will be prepared for submission to the
Department of Environment and Science to install a new on-site STP and effluent irrigation system that is
sufficient to service the existing and new guest and volunteer staff accommodation and supporting facilities.
The supporting document will detail the likely environmental impacts associated with the proposed STP and
the effluent irrigation scheme while demonstrating that each of the potential environmental impacts can be
adequately managed in accordance with relevant legislation, standards and guidelines.
Specifically, the report will include:
    ▪      A calculation of an appropriate hydraulic loading and design capacity for the proposed STP;
    ▪      Determination of the minimum required standard of treatment to achieve desired environmental and
           public health objectives;
    ▪      Assessment of potential environmental impacts, including the outcomes of a daily time-step water
           and nutrient balance using MEDLI; and
    ▪      Management measures proposed to address any potential environmental impacts in accordance
           with the relevant legislation, standards and guidelines.
A Site Based Management Plan will also be prepared to maintain compliance with environmental authority
conditions, relevant legislation and standards and to minimise impacts to sensitive receptors.
A suitable Operation and Maintenance Manual will be required to achieve the operational components of the
new system, associated hardware and required routine maintenance to achieve ongoing compliance of the
system. This is likely to be prepared by the contractor engaged to install the STP and irrigation area given
that operation and maintenance requirements will vary between different plant designs.




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