Little Hayes Lane Nutrient Mitigation Project
River Itchen Catchment
Overview
The Little Hayes Lane Nutrient Project delivers phosphorus and nitrogen reductions through the upgrade of an existing private wastewater treatment system to a modern package treatment plant (PTP).
This project provides nutrient mitigation suitable for residential development within the River Itchen and River Test catchments, in accordance with Natural England guidance.
Location
Itchen Abbas, Hampshire
River Itchen catchment
(Test and Itchen catchments considered as one for nutrient neutrality purposes)
Catchment & Eligibility
- Catchment: River Itchen
- Eligible developments:
- River Itchen catchment
- River Test catchment
Natural England Advice Note (June 2020, Version 5) confirms that the River Test and River Itchen are to be considered as a single catchment for nutrient neutrality. Development within either catchment may therefore be mitigated within the other.
Mitigation Type
Wastewater Treatment Upgrade (Private System)
The project involves the replacement of an existing septic tank with a high-performance package treatment plant, delivering a measurable reduction in nutrient loading to the catchment.
Natural England recognises wastewater treatment upgrades as a valid form of nutrient mitigation where reductions can be robustly evidenced and secured.
Nutrient Reductions Delivered
Based on the technical assessment:
- Total Nitrogen (TN) reduction:
~145 kg TN per year - Total Phosphorus (TP) reduction:
~18 kg TP per year
Reductions are calculated by comparing existing septic tank loads against post-upgrade treated effluent performance, using Natural England default concentrations and certified treatment efficiencies
Delivery & Security
- Mitigation delivered through permanent infrastructure upgrade
- Legally secured via Section 106 Agreement with SDNPA
- Operates under an Environment Agency Permit to Discharge
- Ongoing operation and maintenance secured via an OFWAT-registered provider
- Suitable for securing via planning condition or legal agreement, subject to LPA requirements
Availability
- Status: Available
- Delivery timeframe: Immediate to short-term, subject to legal completion and planning confirmation
- Allocation: Units allocated on a first-come basis
Management & Monitoring
- System installed and operated in line with manufacturer certification and EN12566-3 standards
- Performance based on certified effluent concentrations and Natural England methodology
- Long-term management arrangements can be secured to satisfy LPA and Natural England requirements
Provider
Bio Diverse
Supporting Nature’s Recovery
Enquiries
Please contact the South Downs National Park Authority ReNature team for allocation enquiries and next steps.