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Weetwood 41 St Paul’s Street Leeds LS1 2JG T: 0113 244 1377 E:[email protected] www.weetwood.net LAND AT COTES, LOUGHBOROUGH FOUL WATER DRAINAGE STRATEGY Final Report v1.0 September 2013
Weetwood 41 St Paul’s Street Leeds LS1 2JG T: 0113 244 1377 E:[email protected]
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LAND AT COTES, LOUGHBOROUGH
FOUL WATER DRAINAGE STRATEGY Final Report v1.0
September 2013
Jelson Homes Ltd and Davidsons Developments Ltd
Flood Risk Assessment – Cotes, Loughborough
©Weetwood
www.weetwood.net
i 2148/FWDS Final v1.0
16 September 2013
Report Title: Land at Cotes, Loughborough
Foul Water Drainage Strategy Final Report v1.0
Client: Jelson Homes Ltd and Davidsons Developments Ltd
Date of Issue: 16 September 2013
James Aldridge BEng (Hons) MSc Prepared by:
Technical Engineer
Kevin Tilford BSc MSc PhD MBA C.WEM MCIWEM CEnv Checked by: Director
Andrew Grime BEng MBA CEng C.WEM MICE FCIWEM Approved by: Managing Director
This document has been prepared solely as a Foul Water Drainage Strategy for Jelson Homes
Ltd and Davidsons Developments Ltd. Weetwood Services Ltd accepts no responsibility or
liability for any use that is made of this document other than by Jelson Homes Ltd and
Davidsons Developments Ltd for the purposes for which it was originally commissioned and
prepared.
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CONTENTS
Page Signature Sheet Contents
List of Tables, Figures and Appendices
i ii
iii
1 INTRODUCTION............................................................... 2
2 SITE DESCRIPTION AND DEVELOPMENT PROPOSALS ............ 3
3 FOUL WATER SEWERAGE INFRASTRUCTURE ........................ 5
4 PROVISIONAL LOAD ESTIMATION ...................................... 6
5 FOUL WATER STRATEGY ................................................... 7
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LIST OF TABLES
Table 1: Foul Discharge Rates ............................................................................6
LIST OF FIGURES
Figure 1: Site Location.......................................................................................3 Figure 2: Digital Terrain Model (DTM)..................................................................4 Figure 3: Proposed Sewage Treatment Works Location ..........................................7
APPENDICES
Appendix A: Illustrative Masterplan Appendix B: Communication with Severn Trent Water
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1 INTRODUCTION
There are plans for a residential led mixed use development at Cotes, near Loughborough.
Weetwood has been instructed by the Pegasus Group on behalf of Jelson
Homes Ltd and Davidsons Developments Ltd to prepare an indicative strategy for the disposal of foul water from the development.
This strategy is informed by an assessment of existing sewerage infrastructure provision in the vicinity of the site and the projected service demand of the
proposed development. This strategy may be subject to revision as the illustrative masterplan is
developed.
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2 SITE DESCRIPTION AND DEVELOPMENT PROPOSALS
The site is located in Cotes, to the east of Loughborough at Ordnance Survey (OS) National Grid Reference SK 556 214, as shown in Figure 1.
© Crown Copyright 2013. All rights reserved.
Image reproduced with permission of Ordnance Survey and Ordnance Survey of Northern Ireland
Site boundary
Development area
Legend
Figure 1: Site Location
In general, the site slopes from north-east to south-west, as shown in Figure 2 with levels ranging between 71.0 metres Above Ordnance Datum (m AOD)
to 35.0 m AOD. The development proposals consist of up to 975 residential dwellings, a local
centre, employment land, school and packaged sewage treatment works. This development will be located within a core development area of approximately
44.8 hectare (ha). This area is referred to in this report as the “development area”.
The development proposals also include a number of infrastructure improvements. These improvements are located outside of the core
development area but within the “red-line” site area shown on Figure 1. The red-line area is referred to in this report as “the site”. The total area of the site is 131.023 ha.
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The illustrative masterplan for the proposed development is presented in Appendix A
Figure 2: Digital Terrain Model (DTM)
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3 FOUL WATER SEWERAGE INFRASTRUCTURE
The public sewer network owner operator (the sewerage undertaker) in Loughborough and the area of the site is Severn Trent Water (STW).
By way of a letter dated 1 August 2012 (see Appendix B) STW has confirmed
that the development site is a non mains sewered area and that according to its records there is no mains sewerage infrastructure in the vicinity of the site.
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4 PROVISIONAL LOAD ESTIMATION
Error! Reference source not found. presents the indicative peak dry weather flow based on:
• 975 residential dwellings
• Domestic water consumption figure of 360 litres/dwelling/day • Primary school water consumption of 75 litres/pupil/day • Employment area water consumption of 750 litres/100 m2/day
• Community centre water consumption of 50 litres/person/day1 • Infiltration allowance of 10% of average DWF
Based on this data, the peak DWF from the developed site is estimated to be 50 litres/sec.
Table 1: Foul Discharge Rates
Development Average DWF
(litres/day)
Average DWF
(litres/sec)
975 residential dwellings 351,000 4.06
Primary School – 200 pupils 15,000 0.17
Employment Area – 5.5 ha 412,500 4.77
Community Centre – 100 people 5,000 0.06
Sub Total 783,500 9.09
Multiplier of 6 54.4
Infiltration allowance of 10% 5.4
Peak DWF 50.0
1 British Water Codes of Practice – Flows and Loads 3, 2009
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5 FOUL WATER STRATEGY
The site is in a non mains sewered area and disposal of foul water to the public sewer network.
In line with the advice provided by the DETR Circular 03/992 and PPG43 the
most effective way to dispose of foul water is therefore considered to be through the installation of a packaged plant (designed in line with EN 12566-3).
It is proposed that the treatment plant would be located to the west of the
development area, between Stanford Lane and the River Soar as shown in Figure 3.
Proposed location of sewage treatment plant
Figure 3: Proposed Sewage Treatment Works Location
2 Planning Requirement in respect of the Use of Non-Mains Sewerage incorporating Septic Tanks in New Development,
Department of the Environment, Transport and the Regions, 1 April, 1999 3 Pollution Prevention Guidelines: Treatment and disposal of sewage where no foul sewer is available, Environment
Agency, July 2006
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This location would support the gravity flow of most, if not all foul water to the treatment works (subject to confirmation at detailed design) and is located
entirely in Flood Zone 1 in accordance with siting requirements stated in PPG4. The outfall would be to the River Soar.
The implementation of a plant would be subject to satisfying the legal requirements regarding consultation with the local planning authority and
statutory sewerage undertaker and submission of a foul drainage assessment as per DETR Circular 03/99 and WO Circular 10/99 requirements (ref: 13.35).
In addition to the above, PPG4 states:
• Any proposals for non-mains sewerage systems must take account of the requirements of Building Regulations and should be discussed with
the local planning authority at an early stage and well before any planning application is made.
• Approval for the construction and installation of a PTP may be needed from the local authority building control department and would be
governed by the Building Regulations (England & Wales) 2000 (as amended) and guidance “Wastewater Treatment Systems and Cesspools” The Requirement H2 (ref: 13.36).
• Consent for any discharge from a PTP as well as separate permission for
the outfall structure to the River Soar (Main River) would be required from the EA under the provisions of the Water Resources Act 1991.
• Holder of the discharge consent for the PTP would responsible for ensuring that the plant is well maintained, that the effluent complies
with the consent conditions and that a sampling chamber downstream of the PTP is installed so that representative samples of the effluent can be sampled.
The effluent quality and volume limits would be set out in the EA consent to
ensure that there is no deterioration in the water quality of the River Soar as a result of any discharge from the proposed PTP. At a minimum an effluent standard of 20 mg/l Biological Oxygen Demand, 30 mg/l Suspended Solids and
20 mg/l Ammonia is anticipated.
It is acknowledged that the River Soar is currently failing WFD ecology standards on ammonia and phosphorus levels. It is recognised that a
constructed wetland / reed-bed system may be required to provide tertiary effluent treatment and further reduce BOD, ammonia and phosphorus levels, and sufficient space exists in the identified plant location should a reed-bed
system be required. This issue would be discussed with the EA prior to design and installation of the plant.
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If required, the reed bed system would be designed and maintained in accordance with BRE Good Building Guide No. 424.
Procedures for maintenance of the plant would be implemented in accordance
with best practice and the system manufacturer’s instructions, carried out by an accredited operator experienced in dealing with sewage treatment plants.
In addition to the above, water consumption of the development would be managed through the use of best practice water saving and efficiency
measures such as low consumption dual flush WC cisterns and, in the commercial units, waterless urinals and time limited tap usage, in accordance with Charnwood Policy CS16.
4 Good Building Guide 42, Part 1 – Reed Beds, Building Research Establishment
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APPENDIX A:
Illustrative Masterplan
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APPENDIX B:
Correspondence with Severn Trent Water
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Flood Risk Assessment – Cotes, Loughborough
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Flood Risk Assessment – Cotes, Loughborough
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Delivering client focussed services including:
Flood Risk Assessments
Flood Consequences Assessments
Surface Water Drainage
Foul Water Drainage
Environmental Impact Assessments
River Realignment and Restoration
Water Framework Directive Assessments
Flood Defence Consent Applications
Sequential, Justification and Exception Tests
Utility Assessments
Expert Witness and Planning Appeals
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