Buying

Video transcript

Please note this has been automatically generated and is a work in progress.

This is a user-orientated video to provide instructions on how to use the Norfolk nutrient budget calculator the calculator can be used to determine the approximate phosphate and nitrate loading from a development whether a project is nutrient neutral and if it is not neutral a guide on what mitigation can be put in place in order to achieve neutrality.

This guide will work through a simple example to demonstrate how the tool should be used and clarify the steps where user input is required the introduction tab provides useful background information details of the various stages and definitions of land use types a coluor coding is used throughout this calculator whereby cells highlighted blue require an action from the user and cells highlighted beige are calculated automatically there is also the criteria for determining soil drainage characteristics and instructions for operational catchment information and the location of nitrate vulnerable zones.

The info tab allows the user to input information relevant to their development such as the address, date the calculator was completed, and details of proposed works. The Norfolk nutrient neutrality catchment area is the zone in which new development will increase nutrient loading to the river Wensum and all the broads. The map is available on the various local authorities websites.

The surface water catchment area is accompanied by a map of the applicable wastewater treatment works developments that are located within the surface water catchment area and will drain to a wastewater treatment works within the surface water catchment will need to complete all stages of the calculator developments that are located outside of the surface water catchment but drain to a wastewater treatment works within the surface water catchment will need to complete stage one developments that will drain to a wastewater treatment works that will drain outside of the catchment do not need to complete the calculator as no likely significant effects can be concluded this may be applicable to certain developments in Lee term and Great Yarmouth stage 1 calculates the additional nutrients added into the system as a result of an increased population the first step is to calculate the additional population here the user should input the number of dwellings proposed this will be multiplied by the average occupancy to calculate the increased population for a proposed development that already has a population only the additional population should be inputted this will then calculate the Wastewater volume generated by the development the second step is for the user to select if the sewage is to be treated by wastewater treatment works or by on-site treatment plants first we will run through the wastewater treatment works the user should ensure that yes is selected for wastewater treatment works and no is selected for on-site treatment plants you cannot select both options the user must then select the wastewater treatment works that the development will connect to this will automatically calculate the nutrient loading to the system in kilograms per year the calculator shows the nutrient loading under existing commit limits as well as any planned 2025 upgrades and proposed 2030 permit limits in the case of on-site treatment plants the user should answer yes and ensure wastewater treatment works are set to no the user should then use the drop down menu to select the relevant on-site treatment plant where the discharge concentration in milligrams per liter is unknown default values can be used where the discharge concentration is known this should be inputted into the blue box this should be based on published results from the manufacturer that calculated the value from Laboratory test results or affluent concentrations from real-world applications to achieve the highest reduction values then package treatment plants with specific phosphate stripping should be used step 3 presents the total nutrient load resulting from the additional population stage 2 calculates the phosphate loading from the existing site land use firstly the user must determine the catchment the development is located within from the drop down list follow the link to the introduction Tab and the instructions there to find the operational catchment next the user must select the dominant soil type of the site and should refer back to the introduction tab the dominant soil type for a site can be retrieved from soil's cakes by clicking on the soil underlying the site the user can identify the name and number the user should look to see if their dominant drainage type Falls onto free draining impermeable drained for arable or impermeable drain for arable and grassland category from the table shown on screen in the case where multiple soils types are found on site then the soil type with the largest area should be chosen the user should then select the drainage type from the drop-down list the user should then refer to the rainfall tab to determine the appropriate average annual rainfall band follow the link to determine if the site is within a nitrate vulnerable Zone use the drop down list to select either yes or no next the user should input the various current land uses on site in hectares multiple land uses can be selected and the total area automatically calculated this will automatically calculate the total nutrient loading from the current land uses stage 3 calculates the phosphate loading from the proposed land use the user should input the proposed land uses of the site ensuring the total area matches what was inputted in stage 2.

Land use definitions can be found in the introduction tab if large-scale designed wetlands are to be used the user should input the predicted nutrient banking value in step 3.

Step 4 calculates the total nutrient load from the proposed land use stage 4 provides an overview of the previous three stages and calculates the total nutrient load by adding the contribution from the additional population to the net change in land use types and applying a 20 buffer the stage considers the loading under current permit limits and proposed future permit limits step 5 tells the user if the project is nutrient neutral if the project will generate additional nutrients then mitigation is required the mitigation tabs provide guidance on the mitigation required either off-site or on-site and how this can be offset through changing land uses Step 1 outlines the excess nutrients that needs to be offset for the project to be neutral Step 2 allows the users to select either on-site mitigation or off-site mitigation the user should yes or no as appropriate and select either on-site or off-site mitigation not both taking the example of on-site mitigation the user should select the land use of the mitigation site which in this case will be a part of their site if the exact location on site where mitigation will be situated is unknown then an average value can be used for off-site mitigation the process is very similar the user should select yes and complete the drop-down lists the user should then identify what the land use is of the off-site mitigation area if more than one land use is selected then the average runoff coefficients will be automatically used step 3 provides an indication of the area needed to be created for each mitigation land use assuming that only one mitigation land use is used step 4 allows the user to input the amount of phosphate or nitrate they wish to offset for each mitigation land use type and the area needed will be automatically calculated in the case of wetland the user should input a bespoke banking coefficient and select the amount of phosphate to be offset step 5 works the opposite way to step four allowing the user to input the area of the mitigation land use type and the tool calculates the nutrients that would be mitigated the values outputted will give a good Guide to the areas needing to be mitigated for off-site mitigation however in the case of on-site mitigation the actual area of mitigation needed will be slightly less than what is calculated in Stage 5 due to relative changes with the other land use therefore the user should input the mitigation land use areas given in Stage 5 into the stage 3 and iteratively alter the areas until the proposed development is phosphate neutral the remaining mitigation tabs work in the same way but are for mitigating nutrient under post 2025 in proposed post-2030 permit limits the zero value calculator shows the number of dwellings which can be built and occupied by taking the entire development site out of use and placing a set percentage into low input land use types such as semi-natural grassland the lower value of the coated number of dwellings is the value that should be taken