Drainage and Wastewater Management Plans (DWMPs) - Workshop for the Isle of Wight DWMP
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Drainage and Wastewater Management Plans (DWMPs) Workshop for the Isle of Wight DWMP Tuesday 27 April 2021
Agenda Welcome and Purpose of the workshop Presentation: Problem Characterisation Break Out Session 1: Understanding the risks and identifying our strategy BREAK Presentation: Options Development and Appraisal Break Out Session 2: Identifying generic options Prioritising Wastewater Catchments Next steps 2
Welcome and Purpose Kaylass Ramlagan Strategy Manager, Asset Strategy & Planning 3
DWMP Process: Where are we now?
Complete Our aim today is to:
Complete
Understand the problem:
Complete risks, causes and drivers
Start the Options
TODAY
Development and Appraisal
process by selecting generic
options
Prioritise catchments for
detailed planning
4
Purpose of the Workshop Determine the investment strategy for all wastewater catchments within the Isle of Wight river basin Start the options development and appraisal process by selecting generic options to progress to the detailed planning stage Prioritise wastewater catchments for the detailed planning stage; and Identify where we can work with partner organisations on the detailed (level 3) plans 5
Presentation: Problem Characterisation 6
Problem Characterisation 3 parts: 1. Causes and drivers of risks 7
Drivers
A Driver is “a factor which causes a particular risk to happen or develop”. For the DWMP, it is the category
associated with the cause of the risk, as set out below.
Driver Definition Examples
Hydraulic Risks dependent on the capacity of the Rain water, surface water, highway run-off, and river flooding
sewer network to cope with current or entering into combined or separate foul sewers. Infiltration
future flows generated in the from surface or groundwater.
catchment
Operational Risks associated with our asset Asset failures such as sewer collapse, leaking sewers, pump
management and operational breakdowns and power supply faults.
management activities
Customer Risks dependent on the activities and Misconnections of surface water to foul sewers (or vice versa).
behaviours of our customers. Blockages caused by disposing of fats, oils and grease into
sewer or flushing of baby wipes, nappies etc. Unconsented
trade waste or chemicals being poured into drains.
Quality Risks associated with the treatment Unable to achieve permits specified by the Environment
capacity and flow and quality Agency, lack of adequate treatment capacity for the flow
compliance of our wastewater arriving at the treatment works.
treatment works
8Problem Characterisation 3 parts: 1. Causes and drivers of risk 2. Identifying Catchment Strategy 9
Problem Characterisation 3 parts: 1. Causes and drivers of risks 2. Identifying Catchment Strategy 3. Strategic Needs and Complexity Assessment 10
Purpose of Catchment Strategies Moves us to longer term thinking (25 year plan) Provides a clear statement of intent for our customers Align our whole business to get behind it and deliver Provides a focus for where investment is needed, and when Supports our investment planning 11
Catchment Investment Strategies 12
Determining our Investment Strategies
Short Term Medium Term Long Term Investment
2020 - 2030 2030 - 2040 2040 – 2050+ Strategy
Maintain
LEVEL OF EFFORT
Band 0 Band 0
Band 1 Sustain
Band 1 Band 1 Enhance
Band 2 Defer
Band 2 Prepare
Band 2 Improve /
Change
13BRAVA Results: Isle of Wight River Basin Catchment
Planning Objective
Population Equivalent
Sewer Length (KM)
Risk of
Wastewater Risk of Dry
Internal Sewer Storm Risk of Good Surface
Catchment Wastewater Catchment Reference Sewer flooding Weather Groundwa
Sewer Pollution Flooding Overflow WTW Eclogical Water Nutrient Bathing Shellfish
Reference Collapse due to Flow ter
Flooding Risk in a 1 in performan Complian Status / Managem Neutrality Waters Waters
Risk Hydraulic Complian Pollution
Risk 50 year ce ce Failure Potential ent
Overload ce
storm
ATOP ARRETON STREET ARRETON TOP 93 0.2 NF NF NF NF NF NF NF NF NF NF NF NF NF NF
BLAC BLACKWATER 89 0.2 0 0 0 0 NA NA 0 0 0 0 1 0 NA NA
BSTN BRIGHSTONE 1,619 26.2 0 0 0 2 1 0 0 0 0 0 2 0 0 NA
CALB CALBOURNE 212 3.0 0 0 0 0 2 0 0 0 0 0 1 0 NA NA
CHLE CHALE 579 12.9 0 0 0 0 0 0 1 2 0 0 1 0 NA NA
CHON CHILLERTON 348 5.0 0 0 0 0 NA 0 2 0 0 0 1 2 NA NA
GOHI GODSHILL 1,681 20.4 0 2 0 0 2 0 0 0 0 0 2 0 NA NA
HAZE HAZELEY COOMBE ARRETON 148 1.4 NF NF NF NF NF NF NF NF NF NF NF NF NF NF
HELS ST HELENS 1,436 11.3 0 0 0 0 2 1 2 1 0 0 0 0 0 NA
HIGL HIGHWOOD LANE ROOKLEY 52 0.6 NF NF NF NF NF NF NF NF NF NF NF NF NF NF
KNIG KNIGHTON 11 0.1 NF NF NF NF NF NF NF NF NF NF NF NF NF NF
MNEW NEWLANDS MERSTONE 138 1.5 NF NF NF NF NF NF NF NF NF NF NF NF NF NF
ROUD ROUD 1,828 26.2 0 0 0 0 2 0 0 0 0 0 2 0 NA NA
SAND SANDOWN 130,771 1,299.2 1 2 2 2 2 0 0 2 1 0 2 0 1 2
SHAL SHALFLEET 821 10.9 0 0 0 0 2 0 0 0 1 0 1 0 NA NA
SHOR SHORWELL 470 6.3 0 1 0 0 1 0 1 1 0 0 0 0 NA NA
THYN NORTH VIEW THORLEY 154 3.8 0 0 0 0 NA 0 0 0 0 0 1 0 NA NA
VICL NEWTOWN IOW 37 0.2 0 0 0 0 NA 0 0 2 0 0 1 0 NA NA
WILL WILLOW WOOD ST LAWRENCE 271 2.4 0 0 0 0 NA 0 0 2 0 0 1 0 NA NA
WROX WROXALL 2,784 23.1 0 0 0 1 1 0 0 0 2 0 2 0 NA NA
Key
Not Flagged *
NF
NA Not Applicable **
Results shown for 2020 only
0 Not Significant
1 Moderately Significant
2 Very SignificantSuggested Catchment Strategies: Isle of Wight
Catchment Wastewater Catchment Population Investment
Ref Strategy
SAND SANDOWN 130,771 Improve
GOHI GODSHILL 1,681 Improve
HELS ST HELENS 1,436 Improve
WROX WROXALL 2,784 Improve
BSTN BRIGHSTONE 1,619 Improve
CHON CHILLERTON 348 Improve
ROUD ROUD 1,828 Prepare
CHLE CHALE 579 Improve
SHAL SHALFLEET 821 Improve
CALB CALBOURNE 212 Prepare
VICL NEWTOWN IOW 37 Improve
WILL WILLOW WOOD ST LAWRENCE 271 Improve
SHOR SHORWELL 470 Improve
BLAC BLACKWATER 89 Prepare
THYN NORTH VIEW THORLEY 154 Prepare
ATOP ARRETON STREET ARRETON TOP 93 Maintain
HAZE HAZELEY COOMBE ARRETON 148 Maintain
HIGL HIGHWOOD LANE ROOKLEY 52 Maintain
KNIG KNIGHTON 11 Maintain
MNEW NEWLANDS MERSTONE 138 MaintainSuggested Catchment Strategies: Isle of Wight
20 sewer
catchments
20 WTWs
167 pumping
stations
1455 km sewers
13% area
95% homes
connected
Prepare
Maintain
16Questions 17
Break Out Session 1 18
Instructions for Break-Out Session 1 For each wastewater catchment: 1. Review the BRAVA results and decide the appropriate catchment investment strategy; and 2. Review the causes of the risks and decide the appropriate drivers Time allowed: 30 minutes 19
Plenary: Feedback from Break-Outs 20
Poll 1 21
Options Development and Appraisal (ODA) 22
DWMPs: Identifying and Developing Options
Generic Options Unconstrained Options Constrained Options Feasible Options
Screening Questions: Screening Questions: Screening Questions: Provide for each Feasible Option:
•A description of the option
•Could this generic option be 1. Feasibility and risk: •A description of how the option being
utilised to manage and/or reduce •Is the option technically feasible •Customer acceptability? described differs from baseline
given site, operational or option- activities
the risks identified in the BRAVA?
specific circumstances? •Political acceptability?
•Scale of the benefits to be achieved
•Timeline for implementation against single or multiple planning
•Is it cost effective (based on a •Dependencies objectives.
simple high, medium, low cost
•‘Third parties’ •An assessment of customers’ likely
assessment)?
• Planning and regulatory constraints support for the option.
•Does the option achieve the required •An estimate of the time needed to
outcome? 2. Engineering and cost: investigate and implement the option,
including the earliest start date.
•Are there environmental risks that •Engineering complexity
cannot be mitigated or benefits •An assessment of the risks and
•Cost uncertainty associated with the
provided?
option.
•Would the option likely be supported 3. Performance: •An assessment of the flexibility of the
by customers? •Outcomes option to adapt to future uncertainty.
•Risk and uncertainty – does the •Flexibility to adapt •An explanation of whether the option
•Resilience depends on an existing scheme or a
option provide resilience against
proposed option, or is mutually
future uncertainties? exclusive with another option.
4. Operational •An assessment of factors or
constraints specific to the option (e.g.
5. Environmental planning risks).
• High Level Screening (SEA, HRA, •A description of how the option will
WFD, Biodiversity Net Gain, Natural be utilised and impact on costs.
Capital) •An assessment of the environmental
impacts of the option
•A Habitats Regulations Assessment
if an option could affect any
designated European site.
•An assessment of the costs and
benefits.
23DWMPs: Generic Options
Type of
Generic Option Categories Icon Examples of Generic Options
Measures
Natural Flood Management; rural land management and catchment
Control / Reduce surface water
management; SuDS including blue and green infrastructure; storm management
Control / Reduce groundwater Re-line sewer pipe and manholes; pump away schemes to locally lower
Source
infiltration groundwater near network
(Demand)
Measures Domestic and business customer education; incentives and behaviour change
(to reduce Improve quality of wastewater
(reduce Fats, Oils & Grease, wet wipes etc.); monitoring trade waste at source;
likelihood) entering sewers
on-site black water and/or greywater pre-treatment
Manage the quantity / flow of Water efficient appliances; water efficient measures; blackwater and/or
wastewater entering sewer system greywater re-use
Asset optimisation; additional network capacity; storage; separate flows;
Improve Network operational improvements; structural repairs; smart networks; sewer
Pathway rehabilitation
(Supply) Increase treatment capacity; rationalisation of treatment works (centralisation /
Measures Improve Treatment de-centralisation); install tertiary plant; UV plant or disinfection facilities;
(to reduce innovation; improve Technical Achievable Limits; new WTWs
likelihood)
Transfer flow to other network or treatment sites; transport sewage by tanker to
Wastewater Transfer
other sites
Mitigate impacts on Air Quality Carbon offsetting; noise suppression /filtering; odour control and treatments
Receptor
Measures Improve Land and Soils Sludge soil enhancement
(to reduce
consequences) Mitigate impacts on Water Quality River enhancement
Reduce impact on properties Property flood resilience; non-return valves; flood guards / doors; air brick covers
Additional data required; hydraulic model development; WQ monitoring and
24 Other Study / Investigation
modellingBreak Out Session 2 25
Instructions for Break-Out Session Task: Based on your understanding of the risks, causes and the drivers from the first break-out session …. …… now identify the generic options to progress in the detailed planning for the wastewater catchment Time allowed: 30 minutes 26
Break-out Groups: Template to complete
Carry through
Type of to
Planning Objectives Driver Generic Option Categories Icon Reasons for rejection Examples of Generic Options
Measures unconstrained
list?
Natural Flood Management; rural land management and
PO1 Pollution Operational Control / Reduce surface water catchment management; SuDS including blue and green
infrastructure; storm management
Control / Reduce groundwater Re-line sewer pipe and manholes; pump away schemes to
PO3 Sewer Collapse Risk Operational Source
infiltration locally lower groundwater near network
(Demand)
Measures Domestic and business customer education; incentives
(to reduce Improve quality of wastewater and behaviour change (reduce Fats, Oils & Grease, wet
PO4 1 in 50 year Hydraulic
likelihood) entering sewers wipes etc.); monitoring trade waste at source; on-site black
water and/or greywater pre-treatment
Manage the quantity / flow of Water efficient appliances; water efficient measures;
BP09 Good Ecological status Quality
wastewater entering sewer system blackwater and/or greywater re-use
Asset optimisation; additional network capacity; storage;
Improve Surface Water &
BP10 Hydraulic Improve Network separate flows; operational improvements; structural
Reduce Flooding
Pathway repairs; smart networks; sewer rehabilitation
(Supply) Increase treatment capacity; rationalisation of treatment
Measures works (centralisation / de-centralisation); install tertiary
BP12 Reduce Groundwater Pollution Operational Improve Treatment
(to reduce plant; UV plant or disinfection facilities; innovation; improve
likelihood) Technical Achievable Limits; new WTWs
Transfer flow to other network or treatment sites; transport
BP13 Improve Bathing Waters Customer Wastewater Transfer
sewage by tanker to other sites
Not included in first round of Carbon offsetting; noise suppression /filtering; odour
Mitigate impacts on Air Quality N/A
DWMPs control and treatments
Receptor
Not included in first round of
Measures Improve Land and Soils N/A Sludge soil enhancement
DWMPs
(to reduce
consequences) Mitigate impacts on Water Quality River enhancement
Property flood resilience; non-return valves; flood guards /
Reduce impact on properties
doors; air brick covers
Additional data required; hydraulic model development; WQ
27 Other Study / Investigation
monitoring and modellingPlenary: Feedback from Break-Outs 28
Poll 2 29
Prioritising Wastewater Catchments 30
Prioritising Wastewater Catchments How to prioritise the wastewater catchments on the Isle of Wight for next stage of the DWMP? Where do we start? Which catchments should we do first? Would you like to work with us on any of these catchments? 31
Prioritising Wastewater Catchments in Isle of Wight
2020
Catchment Wastewater Catchment Population 0 1 2 Investment PC Matrix
Ref Strategy
SAND SANDOWN 130,771 4 3 7 Improve Red
GOHI GODSHILL 1,681 9 0 3 Improve Green
HELS ST HELENS 1,436 9 2 2 Improve Green
WROX WROXALL 2,784 8 2 2 Improve Green
BSTN BRIGHSTONE 1,619 10 1 2 Improve Green
CHON CHILLERTON 348 8 1 2 Improve Green
ROUD ROUD 1,828 10 0 2 Prepare Green
CHLE CHALE 579 9 2 1 Improve Green
SHAL SHALFLEET 821 9 2 1 Improve Green
CALB CALBOURNE 212 10 1 1 Prepare Green
VICL NEWTOWN IOW 37 9 1 1 Improve Green
WILL WILLOW WOOD ST LAWRENCE 271 9 1 1 Improve Green
SHOR SHORWELL 470 8 4 0 Improve Green
BLAC BLACKWATER 89 9 1 0 Prepare Green
THYN NORTH VIEW THORLEY 154 10 1 0 Prepare Green
ATOP ARRETON STREET ARRETON TOP 93 0 0 0 Maintain Green
HAZE HAZELEY COOMBE ARRETON 148 0 0 0 Maintain Green
HIGL HIGHWOOD LANE ROOKLEY 52 0 0 0 Maintain Green
KNIG KNIGHTON 11 0 0 0 Maintain Green
MNEW NEWLANDS MERSTONE 138 0 0 0 Maintain GreenNext Steps 33
DWMP High-Level Delivery Programme
2020/21 TODAY 2021/22 2022/23 2023/24
Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1
AMP6 AMP7
-
Submit Strategic Level 2 DWMPs for River Basin Catchments
RBCS to Webinar on
Water UK Update RBCS Launch
website BRAVA results
Strategic Context Submit
BRAVA to
BRAVA national objectives Water UK BRAVA
Webinars
Partner BRAVA Add POs
workshops
Problem Character’n
Options Dev
Partner Partner
workshops Programme
(x11) Webinars
Plan preparation Consult
Board
Approval Finalise L2
Plans
Tactical Level 3 DWMPs for Wastewater Catchments
Options Dev & Appraisal
Partner Programme Appraisal
workshops
Notes: Draft
1. Level 1 DWMP sets out company policies and Plans
strategy for drainage & wastewater
2. Level 2 DWMPs looks strategically across river Corporate Level 1 DWMP
basin and identifies sewer catchments that need SWS Policies
further investment, type of options to be Board
Investment Programme Sign-off
considered and when
Partner Public Finalise Level 1 Publish
3. Level 3 DWMPs consider options and investment workshops Draft Plan QA final
consultation DWMP
choices in detail (first stages of Risk & Value) DWMPQuestions 35
Summary 36
Summary of Workshop What have we done today? Looked at causes and drivers of the risks Identified the catchment investment strategy for a wastewater catchment Determined the generic options to take forward and which to reject Prioritised the wastewater catchments in the Isle of Wight river basin Started thinking about where we may be able to work together on plans for individual wastewater catchments 37
Poll 3 38
Thank you for participating today
Website: www.southernwater.co.uk/dwmp
Contact us: DWMP@southernwater.co.ukYou can also read
