Nutrient Neutrality -Full Feasibility Assessment of the Potential for the Development of Constructed Wetlands within Norfolk

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Description

Further feasibility work should provide the following information in report form. The work should be informed by the initial pre-feasibility report, 'Pre-Feasibility Assessment of the Potential for the Development of Constructed Wetlands' dated 03/05/2023. The report should provide the confidence to proceed to 'design and build' phases or the rationale for not proceeding with wetland implementation. Full feasibility Specification The key deliverable for this contract will be: I. Build on the 'pre-feasibility reduction figures' through identification of the possible range, ie minimum and maximum, for nutrient reduction capacity of the site, via wetland creation, for Nitrogen and Phosphorus using: a. Transfer abstraction of water from the relevant watercourse and; with generated reductions calculated using: i. One of the following methods with a supporting narrative - P-k-C* model - k-C* model - regression equation ii. Details of potential Flow - Flows of water from the relevant source - Inflow of other water sources - Variability of flow with time iii. Details of Concentration within Flow - Nitrogen and Phosphorus loads within all water sources considered - Variability of the quality with time iv. Refinement should enhance reduction calculations by ensuring the most relevant/localised data is used. Including: - A water balance calculation - Estimated sediment accumulation rates 2. Clarification of design objectives in terms of the site's capacity to generate nutrient reductions for N and P in the context of: - Define the potential biodiversity impacts of: o potential loss of ditch/stream (where relevant) o water impoundment/abstraction o water temperature impacts through wetland transfer - Carry out soil substrate investigations to determine: o potential for groundwater interaction o the extent of clay onsite 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 - Development of a monitoring and baselining strategy, including: o identification of suitable monitoring points at in-flow and potential out-flows o flow and nutrient concentration monitoring - Ranged cost estimates of: o implementation and construction o performance monitoring to equilibrium o annual wetland maintenance - Carry out a desk-based assessment to identify any risks that may impact design or construction of the wetland from: o archaeological areas on-site o utilities on-site - Define the potential impacts of 'urban runoff' on wetland effectiveness (where relevant) including but not limited to: o contaminate collection and discharge risk o contaminate effect on biological processes on wetland plants DESCRIPTION CONTINUES IN ADDITIONAL TEXT SECTION Additional information: 3. Feasibility Assessment including constraints and options assessment covering: - Topography - On-site Soil & Water sampling and analysis - Geology & Hydrogeology - Groundwater protection, - Hydrology & drainage - Flood risk - Protected sites & species - Land use, Historic landfill & Contaminated Land - Estimated costs of potential wetland design, construction, monitoring and maintenance The above should be influenced by the provided 'site pre-feasibility' report and be undertaken within scope of the 'Wetland Mitigation Framework' Purpose of this Contract To support the Nutrient Neutrality project's habitat delivery enabling Natural England, landowners and other interested parties to understand constraints and likely costs of progression towards the design and build phase of schemes. ----- To apply for this opportunity you must submit your quotation meeting the requirements detailed in the Request for Quotation (RFQ) attached. Your response must be sent to [email protected] by 17:00 on 20th October 2023 If you have any clarification questions linked to this opportunity or the procurement process please submit these via email to [email protected]. Please note that, unless commercially sensitive, both the question and the response will be circulated to all tenderers.

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