CTMP Revision 0 7.2 Appendix B – Instructions for Maintenance of Rainfall Activated Treatment Systems Reducing the Header Tank Water Volume The header tank is used to avoid dosing during the initial stages of rainfall when site conditions are dry, and no runoff is to be expected. The volume in the header tank is lowered using the lowest of the three outlet tubes. • After 3 days without rain - reduce volume to 50%. • After 6 days without rain - reduce volume to empty (level at lowest outlet). Refilling the Chemical Reservoir The chemical reservoir tank should be refilled when the white displacement tank is half full, or sooner if heavy rain is predicted. This is done by first emptying the white tank (baling with a bucket is efficient), and then refilling the black reservoir tank until the PAC or Superfloc level is at the lower edge of the outlet. Observation of Water Quality in Sediment Control Device The pond water quality will be observed at least weekly, and the clarity determined using a black disc and recorded on the monitoring sheet. pH shall be recorded once the pond has filled up to ensure that chemical dosing does not have an unacceptable effect. Periodic System Checks Check that the rainfall catchment tray is not leaking – especially along the lower edge of the tray. This should be done after rainfall has ceased. Check the lower hose with the small tube outlet, from the header tank to the displacement tank, is not blocked. Monitoring Records A separate sheet is provided for monitoring records for each month (see Appendix B). The information to be recorded is as follows: Visual check - Check the tray for leaks, the plumbing, and the hoses from the header tank. Record ‘ok’ or if maintenance is required write ‘M’ and note requirement in Notes column. How full is the header tank (%)? This is the volume between the lowest and middle outlets. After rain this should be either 100% after 12mm or more rain, or between 0-100% after less than 12mm rain. In summer: 50% when lowered after 3 dry days; 0% when emptied after 6 dry days. Depth in Displacement Tank (%) - Measure depth of water in cm. Reduces to 0 when emptied. Chemical volume added - Record the PAC or Superfloc volume added. 1 drum = 200L, 9cm in the 200L drum = 20L. The volume can also be calculated from change in water level in displacement tank where 1cm change = 4 litres of chemical. Water Clarity - Record using black disc near device outlet. (Refer above).
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