CTMP Revision 0 4.3.1 Application Procedure for Batch Dosing The chemical dose should be applied evenly over the surface of the sediment control device as quickly as practicable. It is best to apply the dose in one application, rather than going over the surface of the water two or more times. The total dose may be applied in one of two ways. a) Spray The chemical can be applied to the surface of the pond using a sprayer that produces large drops. b) Bucket Place no more than 1 litre of chemical in a 10-litre bucket and throw the chemical onto the pond surface so that the chemical divides into drops before hitting the surface. Settlement generally requires 1-2 hours. 4.3.2 Timing As impounded water often develops marked temperature gradients during the day, which can inhibit mixing of the chemical that is added to the surface of the impounded water and the settlement of coagulated solids, batch treatment should be carried out in the early morning to optimise mixing of the chemical with the sediment laden runoff and the subsequent settlement of coagulated solids. 5 Determination of Dose Rate Bench testing will be undertaken to determine the preferred chemical treatment system and optimum dose for suspended solids removal. The bench testing will also consider the effects on pH of the treated water for the sediment retention devices. Bench testing will be undertaken as an ongoing and continual process throughout the life of the Project (refer to Section 3 of this plan "Implementation"). Ongoing monitoring will also be undertaken of the site’s sediment retention devices as outlined in Appendix C. If the monitoring highlights any deficiencies further bench testing will be undertaken. All bench testing results will be recorded in the Bench Testing Result Sheets in Appendix D. 6 Monitoring and Maintenance Requirements 6.1 Routine Management and Maintenance Instructions for routine management and maintenance of the chemical treatment system are provided in Appendix B. A copy of this table will be kept onsite and will be available for review. All monitoring records and maintenance checks and actions will be recorded on the monthly record sheet provided in Appendix C. The systems will be checked after each rainfall event, and during dry periods the systems will be checked weekly. It is also noted that chemical treatment increases the sediment removal efficiency of the sediment controls. The sediment controls will need to be regularly desilted to ensure that the maximum volume is re-established after rain events. 6.2 Contingency Management Contingencies could include poor performance of the treatment system, or effects of other influences on sediment laden runoff quality, such as reduced pH, that might make the use of chemicals inappropriate.
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