San Dona Stage 3 & 6 Wastewater Treatment Plant

sewer treatment

Key Statistics

  • Client: R.D Hughes Developments Ltd
  • Consultant: Connell Wagner (Contact – John Wilson, Ph (03) 366 0821)
  • Time Frame: 3 months
  • Size: Servicing of 50 Lots

This project was the design and construction of a package wastewater treatment plant in 2 stages for 50 homes in the San Dona Subdivision in North Canterbury.

The community on-site sewage treatment/disposal system for the 26 homes of the San Dona Groves Stage 3 subdivision and 25 homes of the San Dona Groves Stage 6 subdivision, plus an additional 10 homes (spare capacity) comprises:

  1. Pre-treatment by individual household septic tanks equipped with outlet filters to retain gross solids,
  2. Reticulation of septic tank effluent to a community facility for aerobic treatment by an N-DN BiofilterTM design Recirculating Sand Filter treatment plant, with disinfection of the treated effluent by UV irradiation,
  3. Discharge of treated, disinfected effluent to land by subsurface irrigation using pumped, low-pressure dosing to shallow-buried Raam dripper-line.


Design Load to plant: Septic tank effluent reticulated from the residential homes, Characteristics of septic tank effluent loading to the plant: BOD5 120-250 g/m3 Suspended Solids 60-100 g/m3 Total Nitrogen less than 100 g N/m3 Design Flows to stage 6 of the plant: max. daily flow 26 m3/day avg daily flow 16 m3/day peak hourly flow 4 m3/hour Design Flows to stage 6 of the plant: max. daily flow 35 m3/day avg daily flow 25 m3/day peak hourly flow 5 m3/hour