Management of silt from SuDS
Regular maintenance of SuDS, including removal of sediment, is required to ensure long term performance of the treatment systems.
Final SuDS (for treating water from a completed development)
Chapter 33 of the CIRIA SuDS Manual (C753) 2015 provides guidance on the principles of good practice for the management of waste resulting from maintenance of SuDS.
You will not require waste management authorisation for deposits of sediments removed from SuDS where;
- They are deposited on the bank of the SuDS from which they were excavated.
- The sediments are non-hazardous. Sediment must be analysed in accordance with the requirements in the table below to establish if they are hazardous waste.
| SuDs type | Analysis required |
|---|---|
| Collecting from roofs only | No |
| Collecting from residential roads, parking areas and commercial zones | No |
| Collecting from refuse collection, industrial areas, loading bays, lorry parks and highways | Yes |
Residential and commercial premises – The material accumulating in final SuDS will be suitable for deposit on the banks of the SuDS.
Once removed, the sediment should be dewatered, spread and over-seeded to avoid silt being carried off during heavy rain and to avoid the loss of storage capacity in the SuDS feature.
Industrial area or road network - The material will require to be analysed/tested to ensure that it is non-hazardous as for example the SuDS pond may have contained chemical/oil/fuel spill. As a result the sediment (and, in the case of a spill, the liquid as well) must be taken to a suitably licenced facility for treatment and/or disposal, in accordance with the Duty of Care for Waste
Construction SuDS (for treating surface water run-off from a construction site)
It is likely that material accumulating in temporary construction SuDS will be suitable for reuse on as the same site as appropriate (even where flocculants have been used to aide settlement of fines). Where the SuDS form part of a land remediation project, advice regarding on-site reuse should be sought from the Local Authority Contaminated Land Officer.
If however the SuDS has contained a spill i.e chemical/fuel/oil then the material should be sampled and analysed to establish if it is hazardous waste. In these cases, the sediment (and, in the case of a spill, the liquid as well) must be taken to a suitably licenced facility for treatment and/or disposal, in accordance with the Duty of Care for Waste.