Tender Summary

Nutrient Neutrality - Feasibility assessment for a constructed wetland located on land near Lyscombe and Highdon SSSI in the Poole Harbour catchment area in Dorset

Buying Organisation

Natural England

Contract Value

£10,000 to £25,000

Tender Description

To create a feasibility assessment for a constructed wetland located on land near Lyscombe and Highdon SSSI in the Poole Harbour catchment area in Dorset. Nature recovery is a key focus for stakeholders, therefore naturalised solutions or those in keeping with the natural landscape should be included within the optioneering process.

The output for the site assessment would be a brief report to identify the opportunities for developing a treatment wetland to treat historical nutrient loads from a groundwater-fed natural spring.

Key outputs would include:

a map of the holding and the area(s) of interest (including an estimation of the amount land required in hectares required to build a treatment wetland).
an options assessment of wetland types or design that identifies opportunities for the development of a treatment wetland working with natural processes to achieve nutrient reduction and habitat improvement.
a description of the potential of the site, including barriers or potential 'show-stoppers' to the development of a treatment wetland.
an initial broad assessment of the potential nutrient credit yield range and the financial cost of delivery. Including appraisal against the wetland mitigation framework confidence matrix.

1. Desk-based feasibility assessment

A desk-based feasibility assessment guided by stage 2 of the wetland framework. This assessment should review:
o Topography;
o Soil;
o Geology & Hydrogeology;
o Groundwater protection;
o Hydrology & drainage;
o Flood risk;
o Protected sites & species;
o Land use, Historic landfill & Contaminated Land

2. Site assessment

The pre-feasibility assessment will require a visit from a treatment wetland engineer. To provide an overview of the land and associated hydraulic pathways through the site, then focusing on the areas with the greatest potential in terms of both credit nutrient yield and any business objectives for the land.

A soil sample(s) to be taken from prospective areas identified for wetland to determine:
o Potential for groundwater interaction
o Whether the wetland requires a clay or artificial liner
o If soil nutrient levels pose a risk of 'treatment liability' in terms of nutrient leaching

A water sample(s) to be taken from potential source of influent to the wetland to identify nutrient concentrations of Total Nitrogen and Total Phosphorus.
o Water sample(s) should be analysed against the time of year, flow conditions and recent rainfall patterns for potential variability.
o Identification of prospective water sampling points on-site to measure flows and loads to the wetland.

DESCRIPTION CONTINUES IN 'ADDITIONAL TEXT' SECTION

Tender categories (products & services required)

Environmental services (CPV 90700000)

Region

North East (UKC)

Buyer Information