Potential for effects from onsite wastewater in the Waikato region, with particular focus on development south and east of Hamilton
Report: TR 2012/09
Author: Urlwyn Trebilco, Brent Fletcher, Trisha Simonson, John Hadfield
Abstract
This report has been produced in response to a request by the Future Proof Implementation Committee. This committee oversees implementation of the Future Proof growth strategy; a strategy for the sub-region comprising Waikato District, Hamilton City and Waipa District.
The report assesses the potential for cumulative effects from on-site wastewater systems in the Waikato region with particular focus on development south and east of Hamilton. It responds to concerns raised in Future Proof's “Southern Sector Study” about potential adverse effects from continuing development in the Tamahere area serviced by on-site wastewater systems. The report also investigates potential for effects from on-site wastewater discharges in small urban areas, particularly Pirongia and Ohaupo.
The report describes local authority management responsibilities for on-site wastewater. It describes the types of wastewater treatment and disposal systems commonly used and their treatment efficiencies. It then describes the main potential adverse environmental and health effects from on-site systems.
Communities in the Future Proof area (Waipa District, Hamilton City and Waikato District) serviced by on-site wastewater systems are identified.The report describes what is known about on-site wastewater systems in Waipa and Waikato Districts including evidence of adverse effects. The description includes findings from the Waikato Regional Council On-site Wastewater Risk Assessment Model. This model was developed to identify areas in the Waikato region where there is a high risk of adverse effects from on-site wastewater systems.
The report reviews relevant studies, guidelines and standards in order to identify whencommunities serviced by on-site wastewater systems may be subject to a risk of adverse environmental and health effects from these systems.
Regional plans are the primary mechanism for managing potential for effects from onsite wastewater systems. The review summarises the main regional plan provisions used in New Zealand to manage on-site wastewater and compares the Waikato Regional Council provisions.
| Contents | ||
| Executive summary | i | |
| 1 | Introduction | 1 |
| 1.1 | Background | 1 |
| 1.2 | Project scope | 2 |
| 2 | Management of on-site wastewater | 3 |
| 3 | Potential effects from on-site wastewater | 4 |
| 3.1 | On-site wastewater treatment systems | 4 |
| 3.2 | Wastewater discharge pathways and effects | 6 |
| 3.3 | Domestic wastewater contaminants | 7 |
| 4 | On-site wastewater in the Future Proof area | 8 |
| 5 | Review of relevant studies, guidelines and standards | 15 |
| 5.1 | Observations from studies and literature reviews | 15 |
| 5.2 | Review of relevant guidelines and standards | 16 |
| 6 | Review of Waikato Regional Plan on-site wastewater rules | 18 |
| 7 | Conclusions | 20 |
| 8 | Recommendations | 22 |
| References | 24 | |