The upgraded Raglan Wastewater Treatment Plant (new consent issued 2005) uses natural processes to treat sewage collected from the Raglan community. Pre-screening removes solids, paper, plastics and material that will not pass through a 6mm screen. As the water flows through a number of treatment ponds, air is added to provide oxygen for the biological process of removing organic contamination. The treated effluent collects in a holding pond before passing through an ultra violet (UV) light to sterilise bacterial pathogens. The quality of the final discharged effluent is equivalent to high quality estuarine water standards.
Aerial overview Raglan Wastewater Treatment site
Reticulated sewage from the Raglan community collects at the Marine Parade pump station where it is pumped to the wastewater treatment plant inlet screen to remove solids. The wastewater then flows into ponds 1 and 2. From this point two lines emerge, the east line feeds aeration ponds A through B. The west line feeds aeration ponds D through C. The lines then rejoin and the treated effluent flows to the roadside holding pond. The final effluent is pumped from the holding pond through an ultraviolet (UV) steriliser and then to the harbour outfall. Discharge times are restricted to ensure that tidal mixing is maximised.