NACOE O31: The primary purpose of this project was to assess the waste RPMs and linemarking paint wash water to determine if the waste category can be changed from regulated waste to non-regulated waste. If the waste categories can be changed, it will allow RoadTek to reduce disposal costs and may enable these materials to be recycled in the future.

The project also included a review of options which could be used to separate the paint solids from the liquid components in the washings from linemarking equipment and determine if there is a difference between linemarking paint and architectural paint (which is not classified as regulated waste). The following key scope items required by the project have been addressed:

• Stage 1: Technical support was provided to optimise the chemical treatment systems used to separate water from paint at RoadTek’s Toowoomba depot. Note: the paint wash water treatment technical support component of the project has not been included in this final report in accordance with the agreed project scope of work.
• Stage 2: A preliminary technical review was conducted by an external environmental consultant (EnRiskS) which relates to the classification of RPMs and the linemarking paint wash water.
• Stage 3: Laboratory analysis of samples of RPMs and linemarking paint wash water based on the advice obtained in Stage 2 was undertaken.
• Stage 4: EnRiskS conducted a review of the test data obtained in Stage 3 to determine whether RPMs and linemarking paint wash water have the potential to be of concern in relation to human health and the environment and whether the data supports a different waste classification for disposal.
• Stage 5: A technical report (this report), has been prepared by ARRB detailing a summary of the background, project process and main conclusions of the work conducted by the external consultant.

In carrying out a legislation review and consulting with the suitably qualified person, it was recognised that the current Queensland waste framework includes a waste classification process via a default or sampling and analysis process. An end of waste framework is also in place to enable the beneficial reuse of materials for a specific purpose or industry. The review also highlighted the legislated requirements TMR has to meet its general environmental duty and has a primary duty of care to look after the health and safety of all persons who may be affected by TMR’s activities.

The preliminary technical review identified the status of the waste RPMs and waste linemarking paint wash water, including the current waste classification and the potential contaminants of concern present within the materials. The technical review provided a summary of potential treatment methods for the paint wash water, including:

• nanotechnology
• membrane separation
• coagulants and flocculant.

Further, a comparison of the status of industrial and architectural or decorative paints was undertaken as industrial waste is considered regulated, whereas architectural or decorative paints are considered
non-regulated. EnRiskS identified the following possible reasons for this dichotomy:

• Industrial paints may be produced and/or used in larger volumes.
• Industrial paints may contain different chemicals to architectural or decorative paints (e.g. metals or higher concentrations of solvents) as they are developed for specialist applications.
• Industrial paints may be used with other additives.

Sampling and laboratory analysis of the waste materials was conducted to confirm the extent of the potential contaminants of concern present, and to provide a basis for comparison against current accepted waste classification standards and guidelines. The outcomes of the sampling and laboratory analysis indicated:

• The linemarking paint wash water will remain classified as regulated as per the initial assessment based on the presence of detected per- and poly-fluoroalkyl substances (PFAS), copper, zinc, electrical conductivity (Ec) and biological oxygen demand (BOD).
• The waste RPMs will remain classified as regulated; however, the classification can be lowered from Category 1 to the less hazardous Category 2. The potential contaminants of concern detected within the waste RPMs include pH and total petroleum hydrocarbons (TPH).

A risk assessment for the beneficial reuse of the waste RPMs was undertaken for the assessment of:

• Application 1 – partial aggregate replacement in asphalt
• Application 2 – use in materials underlying asphalt (encapsulating the waste RPM, where fresh asphalt is laid over older asphalt with RPMs affixed).

An additional end of waste assessment for the use of waste RPMs in unbound applications was also undertaken. All human health and ecological risk assessments determined the material is suitable for reuse
in the proposed applications. Due to the presence of volatile organic compounds (VOCs) and total recoverable hydrocarbons (TRH) exceeding nominated guidelines, the material is not considered suitable for
use underneath buildings without further assessment.