| Conditions or Reasons: | 9)
No development shall commence until a detailed surface water drainage scheme, to manage surface water runoff from the development for up to and including the 1 in 100 year event (+40%CC), and a maintenance and management plan for the scheme has been submitted to and approved in writing by the Local Planning Authority. The discharge rate from the development will be limited to the equivalent 1 in 1 year rate, or an appropriate rate as agreed by the Bedford Group of Internal Drainage Boards. The final detailed design shall be based on the agreed drainage Strategy (to be submitted) and DEFRAs Non-statutory technical standards for sustainable drainage systems (March 2018) and shall be implemented and maintained as approved. Maintenance will ensure the system functions as designed for the lifetime of the development. Any variation to the connections and controls indicated on the approved drawing which may be necessary at the time of construction would require the resubmission of those details to the Local Planning Authority for approval.
The applicant should address the following points 1, 2, 3, 4, 5, 9 and 10 when submitting details to discharge the condition:
This is a minor development therefore a full FRA is not required, however, we do need evidence that flood risk has been considered as it is going to significantly increase the hardstanding in the area.
We will require a full set of calculations providing evidence of all surface water retained on site for the 1 in 100 (+40%CC+10% Urban Creep). Any exceedance should be shown with pathways with maximum depths and velocity.
Any watercourses within or adjacent to the site should be included in the maintenance and management plan, even if there is no discharge to them. This would be a riparian ownership issue but leaving it as such is no longer acceptable. A maintenance and management plan is required ands should show private/adopted/management owned areas.
We will require full drainage drawings showing all connections, control features, storage, inverts etc. and how it communicates with the development wide scheme, for each phase.
Detailed site investigation results (including any site-specific soakage tests and ground water monitoring shown in accordance with BRE 365) will need to be provided with the detailed design. This could be per phase or strategic, either way if it is used for that phase drainage it will need assessing.
Where the use of permeable surfacing is proposed, this should be designed in accordance with the 'CIRIA RP992 The SuDS Manual Update: Paper RP992/28: Design Assessment Checklists for Permeable/Porous Pavement'.
The final detailed design including proposed standards of operation, construction, structural integrity and ongoing maintenance must be compliant with the 'Non-statutory technical standards for sustainable drainage systems' (March 2015, Ref: PB14308), 'Central Bedfordshire Sustainable Drainage Guidance' (Adopted April 2014, Updated May 2015), and recognised best practise including the Ciria SuDS Manual (2016, C753).
To ensure future homeowners and subsequent homeowners will be aware of any maintenance requirements / responsibilities for surface water drainage, including ditches; further measures should be proposed by the applicant and may include, for example, information provided to the first purchaser of the property and also designation/registration of the SuDS so that it appears as a Land Charge for the property and as such is identified to subsequent purchasers of the property.
Land drainage Consent under the Land Drainage Act 1991 must be secured to discharge surface water to an existing watercourse/ditch, and details of this provided with the full detailed design. This is obtained from the IDB, who consider consents and discharge rates on behalf of CBC. An easement should be provided on the developable side of the watercourse to allow for access for maintenance, this should be 9m but may depend on the maintenance requirements considered appropriate.
Agreement for the sewerage undertaker is required to discharge in to a public system. The agreement and rate (l/s) must be included in relevant correspondence.
Reason: To ensure the approved system will function to a satisfactory minimum standard of operation and maintenance and prevent the increased risk of flooding both on and off site, in accordance with para 163 and 165 of the NPPF and its supporting technical guidance. To ensure that the implementation and long term operation of a sustainable drainage system (SuDS) is in line with what has been approved, in accordance with Written Statement HCWS161, 18th December 2014. The need for it to be pre-commencemnt to ensure the drainage works are carried out before any ground works are undertaken. |
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