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Phosphate Assessments for Planning

If you are applying for planning permission in the River Tone or River Parrett catchments then unless, you are dealing with a minor development (and not always then) you will have been asked to prove nutrient neutrality with regards to phosphate, and to you will probably be asked to provide a Phosphate Assessment with your Drainage Strategy. Phosphates are now also being asked for in relation to planning applications in the River Camel Catchment in Cornwall, in order to protect the River Camel SAC.

Good News!

1- We have had a site receive planning permission using one of our phosphate assessment reports. Please see June 2021 update.

2 - We have had one of Reports Approved in Cornwall. Please January Update 2022

Phosphate Updates

Please click below links to see updates which we post monthly (Or Scroll Down for Further Reading):

November 2020

December 2020

March 2021

April 2021

June 2021

July 2021

August 2021

October 2021

December 2021

January 2022

March 2022

May 2022

June 2022

Planning Authorities with Phosphate Planning Requirements

Planning authorities that might ask for these phosphate assessments include:

Areas affected by Phosphate Planning Issues

For more detailed review of affected areas please see Areas Affected by Phosphate Planning Embargo.

Sources or Phosphate

Sources of Phosphate in the UK are varied, they can include Households, Agriculture and Industry. About 80% of all phosphate in rivers comes from Households, with around 15% coming from agriculture. Unusual sources of Phosphates in household effluent:

 These phosphates whether from households or agriculture find their way in to the River Parrett catchment, and are causing an impact of the Somerset Levels and Moors SSSI. They create algal blooms, which causes the water to go murky, blocking out sunlight, and causing problems with oxygen levels within the water, which is home to various rare species.

Small Scale Thresholds

Planning Authorities in the majority of affected areas have adopted "small scale thresholds". These are a list of criteria that if met, offer a simplified approach to development in Phosphate Sensitive Areas. The list of criteria are quite long, and we have only managed to get 1 site passed off under this Small Scale Threshold Arrangement.

a) The drainage field is more than 50m from the designated site boundary (or sensitive interest feature)7 and;

b) The drainage field is more than 40m from any surface water feature e.g. ditch, drain, watercourse8 and;

c) The drainage field in an area with a slope no greater than 15%9 , and;

d) The drainage field is in an area where the high-water table groundwater depth is at least 2m below the surface at all times and;

e) The drainage field will not be subject to significant flooding, e.g. it is not in flood zone 2 or 310 and;

f) There are no other known factors which would expedite the transport of phosphorus for example fissured geology, insufficient soil below the drainage pipes, known sewer flooding, conditions in the soil/geology that would cause remobilisation phosphorus, presence of mineshafts, etc and;

g) To ensure that there is no significant in combination effect, the discharge to ground should be at least 200m from any other discharge to ground11 and

h) The percolation test has been performed of the proposed location of the drainage field with the resulting value lying within the required range under the Building Regulations 2010, which specify an average Vp value of between 12 and 100. T

For more information please see our Small Scale Thresholds Page.

Phosphate Project Management

To provide a solution for those that would like their planning application to succeed we would would offer up one of the below solutions.

Phosphate Solution1 - Removal of Phosphate at Source

It is possible to "filter out" phosphate from waste water, and if you are on private drainage discharging to soak-away or a water course then you may have a real chance of proving neutrality, using on site treatment.

A typical treatment system might include a septic tank or package treatment plant to remove bulk of particulate matter, followed by an engineered or natural filter to remove phosphates.

This solution although perfectly effective is not allowable, if you intended to discharge treated water to a foul sewer. Sewer companies (as well as discharging masses of plastic pollution in to rivers via combined sewer overflows) are quite often consented to discharge at a set rate say 1mg/l. They will treat water to make sure it meets this target threshold, but if you were to add more clean water (from you treatment system) it would just make their life easier . . .  they would still discharge at 1mg/l. So treating water prior to discharge to foul sewer, does not fix the phosphate problem.

Phosphate Solution 2 - Offset

In a given year a a farmer might spread 225kg/hectare of Phosphate on their land. Cows or other animals may be dropping their dung on the fields, and particularly on sloping land, run-off of rain water carriers these Phosphates in to water courses.

A quick solution is to ask that farmer to take his agricultural land out of production. They will stop adding phosphates, send their cattle to be made in to beef burgers, and a Phosphate Offset will have been created. 

However, although peer reviewed papers indicate that useful amounts of Phosphate can be offset by removing land from production. Phosphate Assessments using the recent Phosphate Budget Calculator, shows that you would need hectares of land taken out of production to offset just a few homes.

Phosphate Solution 3 - Mitigation

Features such a riparian buffer zone can be used to filter out agricultural  run-off and create betterment. If the betterment provided can be calculated then this in turn can be sold to developers as a Phosphate credit.

Phosphate Solution 4 - Removal

A system of lagoons or constructed wetlands constructed next to a river, can trap sediment over the course of a year. This sediment is then dug or sucked out after a few years, and used as a fertilizer in less sensitive catchments.

Phosphates Consultancy

We are currently assisting with several planning applications involving phosphate neutrality based on numerous different methods.

We are also setting up a 27 hectare scheme which aims to provide around 3000kg of phosphate offset per annum in the Taunton area. Initially this would rely on taking agricultural land out of production, or establishing a riparian buffer zone, it may mature in to a constructed wetland based system given time.

Phosphate Credits

We are now looking to sell Phosphate Credits to People who need them. These are based on ecosystem services, or via the removal of extant Phosphate Sources.

Problems with Phosphate Neutrality

It is unfortunate then that most the proposed Phosphate capture or offset project will use Agricultural Land, as this will lead to an increased reliance on imports. The current rush to deal with Phosphates is very narrow in its focus, and will likely cause knock on negative impacts in other areas.

Feasibility of Phosphate Schemes

Unless the schemes are heavily subsidised they will remain infeasible. Quick check: 1 Dwelling requires 730m2 of constructed wetland. Round to 10 dwellings offset per hectare. Land cost would be approx £24k / h. Sold at agricultural value. Farmers will not sell land at agricultural value, as it takes away their means of earning money. So suggest £50,000 per ha, and £25,000 per ha to set up scheme. So provided all goes well, land can be found, and delivered on budget, and that a banking coefficient of 8kg is proven with post commissioning testing then base cost would be £7.5k per dwelling. It is worth noting that if wetland does not perform as well as expected then price could at least double. This uncertainty makes investment in such a scheme a risky endeavor. 

Phosphate Updates (From Top of Page)

November 2020

This was around the time we stared getting enquiries relating to the Phosphate Problem. We were contacted by a client in Taunton, who needed a drainage strategy for phosphate neutrality. This report was completed prior to the release of the Phosphate Budget Calculator, so we made our own assumption with regards to nutrient loadings.

The initial scheme proposed treatment of effluent from site using a package treatment plant prior to releasing treated effluent to sewer. This did not work as a concept as water treated down to 0.1mgl Phosphate would then we released from sewage treatment works (Wessex Water) at 0.9mgl. So there was no benefit to receptor.

December 2020

We have had no decision made on reports issued in November. We have begun discussions with Natural England, Taunton and West Somerset and Somerset Wildlife Trust with regards to 25 hectare mitigation site on the banks of the River Tone.

March 2021

We are advising that the only way forward at this stage is with private drainage systems. This enables use of treatment plants and reed beds to remove phosphate and provided mitigation to meet requirements of Phosphate Budget Calculator.

We have to date undertaken around 25 Phosphate reports which have been submitted to various planning authorities within the catchment. We have not heard back any decisions yet, they have neither been rejected or approved, and effort to move things forward by chasing the various stakeholders have not born fruit.

However, we have progressed our strategy to the point where we are not receiving critique, and Somerset County Ecologists have the agreed our design in principal. This only applies to private drainage systems.

April 2021

Taunton and West Somerset and the Somerset Wildlife Trust have visited our proposal site. Taunton and West Somerset Council have made an offer to buy the site, but the amount offered is too low. We hear that EnTrade are developing off site site schemes, which potentially might be bought in to for developments with no option for on site treatment. There are also schemes planned to be available through EnTrade to apply for funding. But these are not yet live.

If we factor in legal, planning, permitting, construction and verification time, we would estimate that there will not be a working offset scheme available prior to 2023. A scheme will likely involve seasonal ecology work to support planning, so we would need to see planning application completed by autumn this year, to avoid waiting for next years season. In addition to this the scheme will involve modification of river channels which will require various additional permits (Flood Risk Activity) from the Environment Agency.

June 2021

2020/2043/FUL - Our Phosphate Report has been reviewed Ecologists and Drainage Consultees at Mendip District Council. Planning has been granted for this application, however a condition requesting detailed drainage design has been included. We are unsure as to why, this maybe because we included a selection of treatment plants in the report, and the consultee requested that we choose one only for certainty. All reports issued since have only included one model of treatment plant.

July 2021

We have now submitted several phosphate reports for sites in Cornwall, including eco lodges, spa hotels, dwellings and barn conversions. Whilst Cornwall council are currently developing a Phosphate Calculator, we are using the Somerset (Parrett) calculator for sites in Cornwall provided there are using private drainage. We have had no feed back on this method as of yet. But we anticipate maths used in the Cornwall phosphate calculator to be very similar.

August 2021

Requests for clarifications have become ever broader, and in some cases are veering in to areas of responsibility , we would not consider the responsibility of planning offices. For example the treatment systems used to filter waste water from development create a clean effluent and a sludge. Consultees are now requesting a long term disposal route for this sludge, which is impossible to provide, and if it were would probably be misleading as it would reflect a level of certainty that is not currently reflected in the waste industry.

October 2021

Cornwall Council have released their Phosphate Calculator, it is very similar to the Somerset Calculator. We are updating all Cornish Reports to reflect new calculator. We are noticing that required wetland area is smaller, when using Cornish Calculator when compared to Somerset One.

December 2021

Mendip Council are now referring to there phosphate planning reports as Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS)

January 2022 (1)

We have received some feedback on off-site mitigation schemes that we are proposing in some of our report. This relates to tree planting within catchment to offset homes in urban setting, and mains drainage connection. The scheme is for 2 homes and will require 1.2 hectares of woodland to offset it. Feed back received indicates that we will need to include specific details as to the location of the land to be used. This complicates matters as the land may not be available for purchase by the time the report is passed off!

 January 2022 (2)

We have had a report approved, and the relating condition discharged for a site in Cornwall. The barn Conversion this relates to received prior approval in 2018. However, there was a drainage condition to discharge. Which triggered requirement for a Phosphate Assessment. We submitted an initial report, and revised in 3 times in order to meet requirements from council. This was all done rapidly, and and we are happy to say it succeeded. Our client can now begin building!

March 2022

We have a plan to make our own Phosphate Credits, which you can then buy.

May 2022

We have now issued several reports for sites in Wales. These differ to the majority of sites in England in that the sewage Treatment Works in Wales we have encountered thus far Cilgerran WWTW & Lampeter STW do not have consent limits for phosphate. This enables us to recommend some mitigation options that would not be allowable in most English sites.

We have also been is discussion with a District Authority in the South with regards to creating a phosphate credit scheme.

June 2022

Gridlock continues. County Ecologists are asking for ever more detail, while conceding little ground.

Phosphate Consultants