Planning – Application Comments

Consultation Date: Thu 02 Jan 2025

Consultation Date: Thu 02 Jan 2025

Comment Date: Wed 29 Jan 2025

I confirm that I have no objections to the foul water condition 4 being discharged

Comment Date: Tue 21 Jan 2025

The level of detail in the information provided is not sufficient to enable us to properly check the design. The following additional/updated information should be provided:

1. Existing and proposed site catchment areas (permeable & impermeable). Proposed catchment plans should be provided to understand how runoff rates/volumes and water quality assessments have been calculated.
2. Long sections and cross sections necessary to understand how the system works. Cross sections should be provided for all SUDS features and flow controls, as a minimum.
3. Detailed Hydraulic Calculations of the entire system, showing the design criteria used (CV values, rainfall data) and results (max water levels, max outflows, flood volumes if any etc.). Calculations to include the appropriate values for climate change and urban creep. Consideration must be given to the outfall type i.e. free-discharge vs surcharged and evidenced in the report text. Pipe and manhole references should correspond to those made on the plan. The calculations provided appear to be an estimate of attenuation volume only, which is not sufficient.
4. SuDS Water Quality Assessment, justifying using the simple index approach or detailed assessment as appropriate.
5. Plan showing exceedance flow routes, stored flood volumes and any flood risk mitigation. Should include external levels and finished floor levels of buildings.
6. Site landscape proposals or evidence the drainage design has been coordinated with soft and hard landscaping design for the development.
7. Management and maintenance plan identifying the future maintenance requirements and which body/bodies will own and be responsible for maintenance of the system and how they will be funded, for the lifetime of the development.
8. Details of how the drainage system will be protected during construction and how runoff (including any pollutants) from the development site will be managed before the drainage system is operational.

Updated/additional information submitted should also address the following site-specific comments:

a. The proposed foul water discharge rate is required, as per the wording of condition 4.
b. Please provide cross sectional details for the flow control device, permeable pavement and attenuation tanks (the one provided is not representative of the arrangement on site i.e. the outlet is shown at the top of the tank).
c. As per item 4 of the list above, hydraulic calculations for the full network are required.
d. Permeable pavements are not covered in the SuDS maintenance schedule.
e. Whilst I understand the practical function of the site means there is not much space for soft landscaping, consideration should still be given to the use of green SuDS features and the multifunctional benefits they can provide. For example, SuDS pods/planters could be used to collect water from the RWPs, rather than connecting directly to the attenuation tank.

The information submitted also refers to previously approved information as part of other planning applications. The applicant should submit the details referenced as part of this application:

' Calculations for the Phase 1 surface water drainage network showing the 2 l/s flow from phase 2 is accounted for or can be accommodated.