Seaweed

The following gives a brief outline of the council’s seaweed processing and analysis procedure.

The council submits a seaweed deployment application to the Environment Agency and a unique permit number is then issued. Seaweed analysis is then undertaken by appropriate technical experts. Once removed from our beaches the seaweed is further analysed by agricultural specialists prior to being spread on farmland as a fertiliser. Some small quantities of sand can be present on or within the seaweed.

Thanet District Council is provided with analytical reports from the agricultural specialists, as follows:

During 2022, seaweed was applied to the soil at a rate of 30t/ha. The levels of Potentially Toxic Elements (PTEs) applied to agricultural land is very low with all elements providing under 20% of the maximum annual additions, based on the ten year totals.

These levels are much lower than the levels set out in the guidance and legislation and indicate that there is no risk of a build-up of harmful substances in the soil. There are no potentially harmful substances to humans or the environment in the material and measures are put in place to reduce any potential risk.

• All fertiliser recommendations are from the Nutrient Management Guide (RB209), updated January 2019.
• Soil samples were taken and tested in accordance with RB209 by a suitably qualified and trained individual.
• A representative sample of the waste material was taken and sent to NRM Ltd for independent testing.

This takes place between July and September. You can see how this is done in this Twitter thread.

We remove driftweed (seaweed) from the main designated bathing beaches as a balanced way of managing our coastline, leaving the tidal bays alone. This ensures that the natural balance of the ecosystems are not interfered with unnecessarily.

We do not have the option to remove seaweed at places such as Beresford Gap, Grenham Bay and Epple Bay due to the chalk reef extending up to the proms and slipways. We are not permitted by law to drive vehicles over the chalk reef which is protected as it is a Special Area of Conservation. In addition these are not designated bathing beaches.

We also do not remove seaweed from Kingsgate Bay as it is not a designated bathing beach. At this bay there is no access for the heavy plant machinery required in the collecting and loading of seaweed for removal. Driftweed in this area is left for nature and forms part of the beach habitat.

We remove seaweed only where needed, for example Margate Main Sands hasn’t had seaweed removed for some years as it has not been required.

Designated bathing beaches include – Botany Bay, Stone Bay, Viking Bay, Joss Bay, Fulsam Rock, Margate (The Bay), Minnis Bay, Ramsgate Sands, Western Undercliffe, St. Mildreds Bay, Walpole Bay, West Bay and Westbrook Bay.

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More than 900 tonnes has been collected by the council since July 2022. This is more than the last couple of years and it can be cyclical with a number of years in a row not having issues. In the past there have also been years where there has been much more and we have cleared around 2,000 tonnes.

Our seaweed is taken by prior arrangement with the Environment Agency and granting of permits to a farm in local farms. The current licence allows 1,225 tonnes to be spread at the farm. We don’t move seaweed from Blue Flag bays and put it onto other beaches.

We have explored different ways to collect the seaweed from the coast over the years and due to the protected sites and the nature of the seaweed we have an established removal method. We use a JCB telehandler – not the surf rake to remove it.

Seaweed itself does not negatively impact water quality, but contaminants that occur which do impact water quality such as litter and dog faeces may become caught in this. The seaweed harbours these contaminants for longer than if they were exposed just in the seawater.

The recent heatwave has exacerbated the issue, in hot weather decomposition happens more quickly.

We leave seaweed on the coast at all beaches and bays from October – March to allow for the natural ecosystem processes in support of local wildlife.

We allow people to take small quantities of loose driftweed for their own garden or allotment over the summer months (April to September inclusive). Some bays are more suitable for this activity than others. The ones which are more accessible for personal collection include: Walpole Bay, West Bay (west side), Westgate and Minnis Bay, Birchington.

If you are removing seaweed from our beaches as part of a commercial activity – for example, if you are making a seaweed-based product to sell, or foraging seaweed as part of an organised activity – you will need Thanet District Council approval – and Natural England’s assent – to do so. Please contact: Thanet.Coast@thanet.gov.uk with a description of your proposed sustainable activity.

There is a Seaweed harvesting code of conduct: Thanet Coast’s Seaweed Harvesting Code of Conduct

Natural England is concerned with the protection of the Site of Special Scientific Interest (SSSI) conservation designations which Thanet holds, the Environment Agency is concerned with bathing water quality.

• Hydrogen sulphide (H2S) is a colourless gas with a characteristic odour of rotten eggs which being denser than air may pool in low areas in still conditions. Hydrogen sulphide occurs naturally in some environments such as sulfur springs, swamps and salt marshes, and is often associated with the decomposition of organic material.
• Hydrogen sulphide has a characteristic rotten egg smell which can be detected at very low levels, well below those that are known to cause health effects.
• Smelling hydrogen sulphide does not mean that it will harm your health.
• Repeated odour events may culminate in real symptoms such as headache, fatigue and nausea. Although these are not direct health effects they are undesirable.
• Real human impacts from hydrogen sulphide are not likely until air levels reach at least 2 ppm for 30 minutes.
• At this point sensitive groups such as some asthmatics may respond with some minor irritations.
• People are normally exposed to hydrogen sulphide in air by breathing it in or by skin/eye contact.
• Any absorbed hydrogen sulphide does not accumulate in the body as it is rapidly metabolised in the liver and excreted in the urine.
• Hydrogen sulphide usually breaks down in air in about 3 days and is dispersed by wind. Therefore exposure is only likely to continue if there is an ongoing source.

You can reduce your exposure by:

• avoiding areas that are known sources of hydrogen sulphide
• keeping windows closed when the odour outdoors is noticeable and opening doors and windows once the outdoor odour has subsided
• not exercising outdoors when the smell is present, particularly if your breathing rate increases.