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Purpose of issue:
Document title:
Planning Condition Response
Condition 16 Private Surface Water Culvert
| Document revision: | S4-P1.0<br><br> |
|---|---|
| Issue date: | 11 Aug 23 |
Purpose of issue:
Document title:
Planning Condition Response Condition 16 Private Surface Water Culvert Author: Rhys Jones Checked: David Hickman
Signed:
Signed
Filing Ref: 3301-BSA-HDG-XX-FN-D-0002_PCR-C16 Filing Ref: 3301-BSA-HDG-XX-FN-D-0002_PCR-C16 Creator: [email protected] Jones, (Civil Engineer) Creator: [email protected] Jones, (Civil Engineer)
| Document revision: | S4-P1.0<br><br> |
|---|---|
| Issue date: | 11 Aug 23 |
Document tracking:
| Rev: | Description: | Issued by: | Date: | Checked: |
|---|---|---|---|---|
| S2-P1.0 | ORIGINAL ISSUE | RLJ | 13/01/23 | DDH |
| S3-P1.0 | DRAFT ISSUE TO DISCHARGE PLANNING CONDITION | RLJ | 10/08/23 | DDH |
| S4-P1.0 | ISSUE TO DISCHARGE PLANNING CONDITION | RLJ | 11/08/23 | DDH |
Version 2.9
© Burroughs Stewart Associates 2022 Contents 3301-bsa-hdg-xx-fn-d-0002_planningconditionresponse-condition#16(s3-p1.0)
Burroughs Stewart Associates are engaged by Excel Construction Group as civil engineering works designers for the proposed King Gaming Campus, Douglas, Isle of Man.
The existing site is a demolished brownfield site and is proposed to be developed into commercial offices, and two blocks of residential accommodation.
A full planning application (Ref: 22/00549/B) for the proposed King Gaming Campus scheme was submitted to Isle of Man Government, on 13 May 2022. The application was originally determined on 22 November 2022, appeal determination on 29 June 2023 and a series of planning conditions accompanied the decision.
This strategic note presents the applicant’s response to Planning Condition 16 and outlines the route to discharging the condition.
“Prior to the commencement of any works (excluding enabling working) a detailed plan showing further details of the existing and proposed culvert running through the site (as indicated in Flood Management Division email dated 11th August 2022) shall be submitted in writing for approval by the Department and this approved scheme shall be completed prior to the occupation/operation of any building on the site and retained thereafter.”
There are two existing culverts crossing the development plot. A private culvert to the north and one owned by the Manx Utilities Authority (MUA) to the south.
The private culvert to the north will be retained in-situ. The scheme proposes to connect additional surface water drainage into the culvert, and these flows will be attenuated to the agreed greenfield runoff rate of 7.0 l/s. CCTV Drainage survey has established the existing private culvert is large, in good working condition. We’ve therefore judged the existing culvert would have capacity for the small additional surface water flows from the scheme.
Further information has been received since the original planning application was submitted confirming the culvert location and outfall to the Glen - Refer to the graphic below indicating existing drainage networks interfacing with the site. It has also been subject to recent CCTV Drainage survey investigation which confirms the internal arrangement as being a concrete box section approximately 590mm wide and 1500mm high. Further details of the CCTV Drainage survey investigation are included in: Appendix A1 appended with this document.
Figure 3.1 - Existing Culverts, Glen Watercourse and Proposed Diversion
The surveys have established that the culvert is in a good working condition, and we would not expect the development to exacerbate deterioration of the culvert.
Subject to legal confirmation, it is expected that the developer would inherit the riparian landowner responsibilities for this private culvert and become the owner of this section within the site. Further details on the existing private surface water sewer and scheme surface water drainage connecting into the existing culvert can be seen on drainage overview drawing: 3301-BSA-S-XX-DR-D-0500-03_DrainageOverview in Appendix A2.
The second culvert is owned by the MUA and carries surface water flows from the adjacent Summerhill Business Park. The details of this sewer arrangement have been confirmed through sewer record cards and a CCTV Drainage survey. The operation of this culvert, its associated tank and flow controls will be unaltered by the development. Further details of the CCTV Drainage survey investigation are included in: Appendix A1 appended with this document.
The scheme no longer proposes to connect to this facility as it is not possible to confidently prove the detailed operation of this historic asset and consequentially the impact of altering the contributing catchment. Instead, the surface water from the development will be managed independently through flow attenuation and throttle to greenfield run-off before discharging to the local water course.
To facilitate the construction of the development and the Block C building, sections of the existing MUA sewer will need to be permanently diverted. The redundant section will be removed to construct Block C following completion of the diversion. The existing MUA surface water sewer and proposed diversion are identified with a contour plot below:
Figure 4.1 - Existing MUA Surface Water Sewer and Proposed Diversion
This will be made through a Section Application to the MUA and will be based on like-forlike flow characteristics with no adjustment to upstream catchments. Therefore, posing no impact to hydraulic performance and operation of the existing arrangement. Further details on the existing MUA surface water sewer and proposed diversion can be seen on drainage overview drawing: 3301-BSA-S-XX-DR-D-0500-03_DrainageOverview in Appendix A2 and surface water MUA diversion drawing: 3301-BSA-S-XX-DR-D-050703_SurfaceWaterMUADiversion in Appendix A3.
PCR-C16 - Planning Condition Response Condition 16 Private Surface Water Culvert
August 23
CCTV Drainage Survey Information Existing Private Surface Water Culvert and MUA Surface Water Sewer
© Burroughs Stewart Associates 2022 Appendix 3301-bsa-hdg-xx-fn-d-0002_planningconditionresponse-condition#16(s3-p1.0)
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