PLANNING COMMENT FOR APPLICATION REF:  5/2025/2228

Devcon Team

Maple Lodge STW
Denham Way

Thames Water

Our DTS Ref: 107221

Your Ref: 5/2025/2228

13 January 2026

Dear Sir/Madam,

Re: 14 - 16, CRANBROOK DRIVE, ST. ALBANS, Hertfordshire County, AL4 0SS

WASTE:

With regard to SURFACE WATER drainage, Thames Water would advise that if the developer follows the sequential approach to the disposal of surface water we would have no objection. Management of surface water from new developments should follow guidance under sections 167, 168 & 169 in the National Planning Policy Framework. Where the developer proposes to discharge to a public sewer, prior approval from Thames Water Developer Services will be required. Should you require further information please refer to our website. https://www.thameswater.co.uk/help/home-improvements/how-to-connect-to-a-sewer/sewer-connection-design

The foul water network in this catchment is impacted by high infiltration flows during certain groundwater conditions. Care must be taken when designing new networks to ensure they don’t surcharge and cause flooding. Whilst design and construction guidance for sewers allows for an element of infiltration, we would expect in high risk areas such as this that additional precautions are taken to minimise infiltration; this should be in the form of the installation of leak tight liners within sewers and resin injection to seal chambers. This will help to mitigate the risk of flooding in the vicinity of the development (e.g. reduce property flood risk and travel disruption in the locality) and also help to reduce the risk of pollutions in the wider environment, particularly considering the impact of climate change. In the longer term, Thames Water, along with other partners, are working on a strategy to reduce groundwater entering public sewer networks.

The surface water network in this catchment is impacted by high infiltration flows during certain groundwater conditions. Care must be taken when designing new networks to ensure they don’t surcharge and cause flooding. Whilst design and construction guidance for sewers allows for an element of infiltration, we would expect in high risk areas such as this that additional precautions are taken to minimise infiltration; this should be in the form of the installation of leak tight liners within sewers and resin injection to seal chambers. This will help to mitigate the risk of flooding in the vicinity of the development (e.g. reduce property flood risk and travel disruption in the locality) and also help to reduce the risk of pollutions in the wider environment, particularly considering the impact of climate change. Developers must liaise with the LLFA to agree an appropriate sustainable surface water strategy following the sequential approach before considering connection to the public sewer network. This must also ensure that the design of any SUDS or surface water management solution conveys exceedance flows away from public sewer networks. In the longer term, Thames Water, along with other partners, are working on a strategy to reduce groundwater entering public sewer networks.

Public sewers are crossing or close to your development. Build over agreements are required for any building works within 3 metres of a public sewer and, or within 1 metre of a public lateral drain. This is to prevent damage to the sewer network and ensures we have suitable and safe access to carry out maintenance and repairs. Please refer to our guide on working near or diverting our pipes:https://www.thameswater.co.uk/developers/larger-scale-developments/planning-your-development/working-near-our-pipes Please ensure to apply to determine if a build over agreement will be granted.

Thames Water would advise that with regard to WASTE WATER NETWORK and SEWAGE TREATMENT WORKS infrastructure capacity, we would not have any objection to the above planning application, based on the information provided.

WATER:

With regard to water supply, this comes within the area covered by the Affinity Water Company. For your information the address to write to is - Affinity Water Company The Hub, Tamblin Way, Hatfield, Herts, AL10 9EZ - Tel - 0845 782 3333.

The applicant is advised that their development boundary falls within a Source Protection Zone for groundwater abstraction. These zones may be at particular risk from polluting activities on or below the land surface. To prevent pollution, the Environment Agency and Thames Water (or other local water undertaker) will use a tiered, risk-based approach to regulate activities that may impact groundwater resources. The applicant is encouraged to read the Environment Agency’s approach to groundwater protection (available at https://www.gov.uk/government/publications/groundwater-protection-position-statements) and may wish to discuss the implication for their development with a suitably qualified environmental consultant.

Yours faithfully,
Development Planning Department

Development Planning, Thames Water
Maple Lodge STW, Denham Way, Rickmansworth, WD3 9SQ