The Crane operational catchment - Crane Valley … · The Crane operational catchment Thames River...

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The Crane operational catchment Thames River Basin Management Plan consultation support pack Nov 2014

This pack is to help those with an interest in the Crane operational

catchment to respond to the 2014/15 consultation on the draft

updated Thames River Basin Management Plan.

It should be read alongside the official consultation documents and

the London catchment summary, and does not seek to duplicate

the explanation or information they contain.

Access the consultation online at

http://www.gov.uk/government/consultations/update-to-the-draft-

river-basin-management-plans

Alternatively you can request a hard copy of the reports and

response forms by contacting our enquiries team on 03708 506 506

or [email protected]

http://www.gov.uk/government/consultations/update-to-the-draft-river-basin-management-plans

http://www.gov.uk/government/consultations/update-to-the-draft-river-basin-management-plans

mailto:[email protected]

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List of Contents

Changes to water bodies – information to support consultation question 1

Cycle 1 water bodies

Cycle 2 water bodies

Proposed changes to designated uses of heavily modified and artificial

water bodies

Long-term objectives for 2021 – information to support consultation question 2

Catchment Data Explorer – information to support consultation question 3

Measures – information to support consultation questions 4 and 6

Catchment-wide measures for all water bodies

Measures for the Crane GB106039023030

Measures for the Yeading Brook GB106039023051

Measures for the Port Lane Brook GB106039023450

Measures for the Duke of Northumberland’s River at Heathrow*

GB806100108

*includes measures for the Duke of Northumberland’s River at

Twickenham and the Longford River – these rivers are not currently on

the proposed cycle 2 water body network but were included in the cost-

benefit analysis

Measures for Kempton Park East Reservoir GB30642614

Cost benefit analysis final appraisal report – information to support consultation

question 5

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Water bodies in RBMP cycle 1 (current)

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Water bodies in RBMP cycle 2 (proposed)

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Long-term objectives for 2021

We are proposing long term objectives of good ecological status by 2021 for the Crane water

body, and good ecological potential by 2021 for the other water bodies.

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Catchment Data Explorer

Information about the status of water bodies in the Crane operational catchment can be found

doing a classification search on Catchment Data Explorer at

http://environment.data.gov.uk/catchment-planning/OperationalCatchment/senet79/ .

http://environment.data.gov.uk/catchment-planning/OperationalCatchment/senet79/

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Proposed designated uses of heavily modified and artificial water bodies.

Water body Cycle 1 designated

use(s)

Proposed Cycle 2

designated use(s)

Reasons for change

Crane Urbanisation No designated use –

remove heavily

modified designation

The most urbanised reaches of the

cycle 1 water body have been assigned

to other cycle 2 water bodies. Most of

the cycle 2 Crane water body runs

through open space where measures

will not have an impact on buildings or

infrastructure and are likely to result in

good ecological status.

Yeading Brook

Urbanisation (applies

to cycle 1 water

bodies that are

merged to create

cycle 2 water body)

Flood protection

(applies to cycle 1

water bodies that are

merged to create

cycle 2 water body)

Urbanisation Restoration to a natural state would

require major redevelopment, involving

the removal of residential and

industrial/commercial properties and

removal or diversion of roads and

railways.

Incorrect designation in first cycle: flood

protection structures are not extensive.

Flood storage areas do not have a

significant impact on ecology; one is

been decommissioned.

Port Lane Brook Urbanisation Urbanisation Restoration to a natural state would

require major redevelopment, involving

the removal of residential and


removal or diversion of roads.

Duke of

Northumberland’s

River at

Heathrow

Water Regulation

Urbanisation Near-natural conditions could only be

achieved through redevelopment

involving the removal of residential and


major transport infrastructure.

Incorrect designation in first cycle: not

used for drinking water supply.

Kempton Park

East Reservoir

Wider Environment

Water storage

Wider Environment

The reservoir is a SSSI.

Incorrect designation used in cycle 1:

decommissioned as a drinking water

reservoir in 1980.

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Measures

Measures are on 4 different scales:

Catchment-wide measures (listed on the next page) – applicable to all water bodies in the

Crane catchment.

Water body wide measures (listed for each water body) – applicable throughout the water

body and/or its catchment area.

Reach measures (mapped for each water body) – measures for specific lengths of river.

Note that the colours used are to distinguish neighbouring or overlapping measures and

have no other significance.

Point measures (mapped for each water body) – measures for specific locations centred

on a single point represented by a dot on the map.

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Catchment-wide measures – measures for all water bodies in the

Crane catchment

2041 Only Rain in Rivers - Be a Solution to Water Pollution' pollution awareness campaign

throughout the Crane catchment to raise awareness and elicit behaviour change about

misconnections, blockages, and other sources of domestic pollution.

2282 Ongoing, co-ordinated programme for the control and management of Himalayan

Balsam in a catchment-wide strategy as a contribution to national Invasive Species Action

Plan

2283 Slow the spread of high impact invasive non-native species by adopting good

biosecurity practice and by promoting campaigns such as, “Check, Clean, Dry” and “Be

Plantwise” to local stakeholders who take part in water sports, boating, angling and other

activities in or near water.

2286 Continue to improve knowledge of species distributions and improve public

awareness of new and established Invasive Non-native Species through co-ordinated

catchment-wide monitoring, surveys and mapping.

2572 Ongoing, co-ordinated programme for the control and management of giant hogweed

in a catchment-wide strategy as a contribution to national Invasive Species Action Plan.

2575 Ongoing, co-ordinated programme for the control and management of Japanese

knotweed in a catchment-wide strategy as a contribution to national Invasive Species

Action Plan.

2589 Promote Local Action Groups in the Crane catchment to engage the support of the

third sector in controlling invasive non-native species and in promoting key messages.

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Measures for the Crane GB106039023030

Measures are to:

Resolve failures in Phosphate, Diatoms and Macrophytes caused by pollution

from misconnections, Combined Sewer Overflows (CSOs) and shared

manholes, urban run-off and incidents

Our source apportionment modelling of phosphate indicates:

o 20-40% of Phosphate load comes from shared manholes (CSOs) and

associated incidents

o 20-40% of Phosphate load comes from misconnections

o 20-40% of Phosphate load comes from urban run-off

o less than 20% of Phosphate load comes from sewage treatment works in the

Colne catchment

Resolve failures in Invertebrates caused by modified habitat, misconnections

and airport de-icer pollution

Resolve failures in Fish caused by modified habitat

Water body wide measures

2408 In-channel habitat enhancements, removal or replacement of hard bank revetment

and bank rehabilitation/reprofiling where appropriate in reaches still to be identified.

2471 Assess and improve or remove CSOs in the Crane (including part of the Yeading

Brook) water body; identify all cross connections and shared manholes and assess,

improve and formally permit, or remove these overflows.

2475 Identify and correct polluted surface water outfalls throughout the Crane water body.

2481 Coordinated Pollution Prevention/Hazardous Waste inspections of businesses,

particularly in the Southall area.

2515 Rectify the majority of misconnections leading to identified polluted surface water

outfalls on the River Crane.

2523 Assess and improve highway runoff management, including best practice gulley

maintenance, throughout the the catchment area of the Crane water body.

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Measures for the Yeading Brook GB106039023051

Measures are to:

Put mitigation measures in place

Resolve failures in Invertebrates caused by pollution from misconnections and

urban run-off


Note: water body wide measures were identified for the two separate cycle 1 water bodies which

we are now proposing to combine in cycle 2. We propose that otherwise identical actions listed

below for both cycle 1 water bodies should be combined into single actions for the cycle 2 water

body.

008 Educate riparian landowners along whole watercourse on sensitive management in

response to changes to vegetation, hydrology and sediment supply as a result of

urbanisation.

009 Enhance channel bed within all railway and road culverts downstream of the A404.



urbanisation.

024 Enhance channel bed within all railway and road culverts downstream of Victoria Retail

Park.

2473 Identify and correct polluted surface water outfalls throughout the Yeading Brook

West water body.

2474 Identify and correct polluted surface water outfalls throughout the Yeading Brook East

water body.


outfalls on the Yeading Brook East.


outfalls on the Yeading Brook West.


maintenance, throughout the the catchment area of the Yeading Brook East water body.


maintenance, throughout the the catchment area of the Yeading Brook West water body.

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Measures for the Port Lane Brook GB106039023450

Measures are to:


Resolve failures in Phosphate and Invertebrates caused by pollution from

misconnections and urban run-off; and in Phosphate caused by Combined

Sewer Overflows (CSOs) and industry

Our source apportionment modelling of phosphate indicates:

o Urban run-off and misconnections are a major source of the Phosphate

load

o Combined Sewer Overflows (CSOs) and shared manholes are a minor

source of the Phosphate load

o Industry is a minor source of the Phosphate load


2316 Enhance marginal and in-channel habitats wherever possible along the Port Lane

Brook and Felthamhill Brook.

2476 Identify and correct polluted surface water outfalls throughout the Port Lane Brook

water body.

2480 Co-ordinated Pollution Prevention/Hazardous Waste inspections of businesses,

particularly in the Bedfont and Hanworth areas.


outfalls on the Port Lane Brook.


maintenance, throughout the the catchment area of the Port Lane Brook water body.

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Measures for the Duke of Northumberland’s River at Heathrow GB806100108

Measures are to:





urbanisation.

2487 Enhance channel bed within the six road culverts (total length 284m) passing beneath

the major roads around the perimeter of Heathrow Airport.

2488 Remove timber toe-boarding and realign/reprofile banks in appropriate locations still

to be identified.

Measures for the Duke of Northumberland’s River at Twickenham

Note: this water body is not currently proposed as a cycle 2 water body, but actions have been

identified for it as part of the cost benefit analysis and are listed here.

Measures are to:



2571 Ongoing, co-ordinated programme for the control and management of Floating

pennywort (Hydrocotyle ranunculoides) on the Duke of Northumberland’s River as a

contribution to the national Invasive Species Action Plan.

307 Remove toe-boarding and realign/reprofile banks in appropriate locations still to be

identified.

308 Retain and enhance the vegetation within the river channel and riparian zones.



urbanisation.

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Measures for the Longford River

Note: this water body is not currently proposed as a cycle 2 water body, but actions have been

identified for it as part of the cost benefit analysis and are listed here.

Measures are to:


Water body wide measure

2558 Enhance channel bed within the four road culverts (total length 250m) passing

beneath the major roads around the perimeter of Heathrow Airport.

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Measures for Kempton Park East Reservoir GB306426140

Measures have not been identified for this water body, as we consider it to be at good ecological

potential.

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Operational Catchment Economic Appraisal - Final Appraisal Report

Further detail, including a list of costs, is available on request

Note: appraisal was carried out using Cycle 1 water bodies

Overview

Operational

catchment

Crane

Part of the London management catchment.

Waterbodies:

4 rivers (heavily modified)

2 surface water transfers*

1 lake (heavily modified) *A third surface water transfer, the Longford River, is included in the Port Lane Brook water body.

Date economic

appraisal started 1 November 2013

Date economic

appraisal completed 30 January 2014

Name/s of

assessor/s

Lead assessor:

Amanda MacLean, Catchment Co-ordinator (Brent & Crane)

Contributors:

Neale Hider, Biodiversity Officer

Lucy Shuker, Geomorphology Technical Specialist

John Bryden, Biodiversity Technical Specialist

Phil Belfield, Fisheries Technical Specialist

Karen Douse, Senior Environment Officer

Laura Beardsworth, IEP officer (AST)

Tom Perry , Area WFD Co-ordinator

Objective and aim of

economic appraisal

Objective

To identify a bundle of measures to improve all six failing

water bodies in the Crane operational catchment to good

ecological potential.

Aim

To identify whether the bundle of measures is cost beneficial

or not.

Number of bundles of

measures assessed

One bundle was assessed, comprising all the actions

identified to resolve the reasons for failure in the Crane

catchment and achieve Good Ecological Potential.

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Overview

Risk of failure %

applied to

recommended

bundle of measures

25% . This value is towards the upper end of the low risk

category. The great majority of actions, including the key

ones, are physical modification or water quality improvement

projects that will address issues directly, with relatively

certain outcomes when delivered. A small minority of actions

require behavioural change.

This was approved in a meeting of the the North East Thames Area Economics & Investigations Group* as the right level of risk on 20/1/2014.

*The North East Thames Area Economics & Investigations Group is composed of Environment Agency Technical experts from the North East Thames Area Office.

Results of Stage 1

valuation for

recommended

bundle of measures

Net Present

Value

Benefit Cost

Ratio:

Present Value

Benefits:

Present

Value

Costs:

£43 million 1.96 £87.8 million £44.7 million

Non-monetised

benefits

The following benefit categories were recorded as having significant

positive benefit in the AST:

Recreation and tourism

Aesthetic value

Intellectual and scientific, educational

Provision of habitat

WFD status

achievable

All water bodies within the operational catchment could

achieve Good Ecological Potential by 2021.

Sensitivity testing

Sensitivity testing was carried out within the Stage 1

valuation. In addition we have assessed an alternative ‘high

cost’ scenario.

Recommendation of

assessor

The bundle of measures is cost beneficial. In addition, there

are significant non-monetised benefits.

The bundle of measures should be included in the draft River

Basin Management Plan for consultation.

Stage 1+ valuation No

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Overview

required?

WAG section 5

QA undertaken

An informal QA was undertaken by NE area staff in January

2014, however no formal QA has been completed.

Detail

Bundle/s of measures

The main types of measures included in the bundle are to deliver three of the seven key

objectives in The Crane Valley - a Water Framework Directive Catchment Plan produced by the

Crane Valley Partnership:

1. River rich and diverse in habitats and native wildlife - creating and enhancing wetland habitats throughout the river corridor; reducing shading of the river channel; an ongoing, catchment wide programme for the control and management of Giant hogweed, Japanese knotweed, Himalayan balsam and floating pennywort

2. Clean, clear water- reducing pollution from diffuse and point sources (primarily sewer overflows, domestic pollution, and urban drainage)

3. A natural looking and functioning river with sustainable flow- removing or modifying man-made structures; improving connectivity by removing or bypassing barriers to fish passage; improved water level management; realignment and reprofiling

Relevant actions from the Crane Catchment Plan are incorporated alongside others identified by

Environment Agency staff.

Measures which address no deterioration were removed from the cost benefit analysis of the

bundle of measures (as per guidance) before economic appraisal was carried out. The benefits

and effects on the wider environment are recorded in the Appraisal Summary Table.

Measures have been chosen primarily to address the impacts of significant water management

issues causing failures under the Water Framework Directive. Where possible, climate resilient

measures have been chosen. However it is considered unlikely that the measures will be

sufficient to address all impacts of climate change and we will be assessing the likely gaps before

the publication of the final River Basin Management Plans.

Reference: Measures, Bundles and Costs sheet (see below)

Costs

Costs used

Total costs for the Crane cost benefit analysis for CAPEX (Capital

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Detail

expenditure) and OPEX (Operational Expenditure) are presented in

the table below. OPEX costs apply to a minority of actions in this

category. Where OPEX costs are expected to be incurred for less

than 40 years, they are included in the CAPEX cost.

One off

CAPEX

TOTAL

OPEX

Annual OPEX (of costs

sustained for 40

years)

Medium cost scenario:

River rich

and

diverse in

habitats

and native

wildlife

£3,451,025 £107,250 £2,750

Clean,

clear water

£25,779,672 £19,228,638 £493,042

A natural

looking

and

functioning

river with

sustainable

flow

£8,765,950 £234,000 £6,000

TOTAL £37,996,647 £19,569,888 £501,792

In order to account for uncertainty in cost estimates, high and low

cost estimates were entered and a calculated midpoint value was

used in the bundle of measures. The high and low cost estimates

are considered to be the maximum and minimum costs likely, for the

most complex and simplest conditions for each measure. For

measures where there was more certainty in the cost, one cost

estimate was used.

The high cost estimates were used to create an alternative scenario

for sensitivity testing.

Costs were derived from both local and national sources, as follows:

Reducing Pollution

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Detail

Point Source Pollution

Combined Sewer Overflows Costs were provided by Thames

Water but were aggregated to cover entire water body catchments

for all water bodies identified as being affected by CSOs.

Urban Diffuse Pollution

Highways drainage Costs for increased gully pot cleaning were

calculated using cost estimates provided by London Borough of

Waltham Forest. A cost of increasing gulley pot cleaning per km2 of

urban and suburban land was calculated. This figure was multiplied

by the urban and suburban area of each water body to give an

estimate of increased costs for gulley pot cleaning for each water

body catchment.

Polluted Surface Water Outfalls were costed at information

redacted per outfall project (figure provided by Thames Water) for

all water bodies identified as being affected by misconnections

and/or urban drainage. For most of these water bodies, the number

of outfalls was known from recent walkover surveys. Since no

walkover surveys had been carried out on the Port Lane Brook

water body, the number of polluted outfalls was estimated from the

average of approximately one outfall per kilometre of river in the

other Crane catchment water bodies.

Other costs were calculated using modifications to the Urban

Diffuse Pollution Measures Costs Calculator, a spreadsheet tool

developed by the Environment Agency Midlands Region, as follows:

Rectifying misconnections The default costs in the tool were

used for the high cost estimate. A low cost estimate was calculated

using the lower bound of costs in the National Cost Effectiveness

Database, on the understanding that a lower figure would be more

representative of average costs* than the mean in the cost

calculator, which is derived from only two data points (maximum

and minimum).

*evidence: figures quoted in a National Misconnections Strategy Group presentation indicate an average of £440 per misconnection,

whether above or below ground; Policy Consulting Network document quotes an average cost of between £20 and £200, while

acknowledging that some will require excavation at a cost of several hundred pounds.

Pollution prevention visits to industrial estates The number of

http://www.linkedin.com/groups/Sewerage-Misconnections-Role-RICS-in-4354705.S.264980939

http://www.policyconsulting.co.uk/downloads/Misconnections_RICS_July2010.pdf

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Detail

small and large industrial estates was counted using aerial

photography.

Awareness campaigns for the general public The default costs in

the tool were used as the high cost estimate. The low cost estimate

was based on an enhanced version of a current pilot campaign.

More accurate population figures for the catchment area of each

water body were obtained using data from the 2011 census.

Annual savings were included for awareness campaigns, based on

the results of the Anglian Water Keep it Clear campaign, where

blockages and associated costs were cut by 75%. Applied to

Thames Water’s current costs of £12 million per annum on

blockages covering 9 million customers, this gave an estimated

saving of £1 per dwelling.

Making Rivers More Natural

Project costs were used in cases where they were available (e.g.

London Rivers Action Plan; quotes from contractors). However, for

the majority of measures, area staff (Fisheries, Biodiversity,

Planning & Strategic Overview, and Catchment Coordinators)

estimated high and low costs using expert judgement, supported by

a list of recent projects in North East Thames and a list of cost

estimates for river restoration works from Halcrow (2008). The

National Cost-Effectiveness Database was used to supply costs in

cases where there was uncertainty concerning the type or extent of

works required.

Tackling Problem Invasive Species

The Biodiversity Technical Specialist used expert judgement to

estimate costs per km for a ten-year programme of invasive species

management for key invasive species. These costs were applied to

the length of river currently affected, as estimated by a Biodiversity

Officer with extensive knowledge of the catchment.

http://www.thameswater.co.uk/help-and-advice/9137.htm

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Detail

Willingness to pay

Value used

Central (default)

The communities living within the Crane catchment range from the

relatively deprived to the more affluent. Extensive reaches of the

River Crane and its tributaries are in open space and are used for

recreation, so a central willingness to pay value is a good

representation of the average.

NWEBS baseline

The NWEBS baseline was determined using the agreed comparative WFD status approach.

The 2013 classification was used to predict 2015 baseline status because it uses the most

complete set of sample data and best reflects the current ecological status of water bodies in the

Crane catchment between 2013 and 2015 .

There were a number of cases where better local information was available, where data for

relevant elements was not available, or where expert judgement indicated that the suggested

baseline was not representative of the situation in the water body. In these cases, the suggested

baseline was modified to better reflect the current NWEBS condition of the water body.

Km /km2or m3 of benefits

In most cases, the entire length/area of the water body was Actions to reduce pollution and tackle

invasive species will happen on a whole water body basis. Specific measures that have been

identified to improve physical habitat cover lengths the equivalent of the river line used as the

basis of the calculations. In the cases of the Yeading Brook (east arm) and the Port Lane Brook,

measures that have been identified to improve physical habitat do not cover the full length of the

water body so only a percentage of the water body was considered to be improved.

Where there are substantial culverts that cannot realistically be removed, the length of river

benefited was reduced proportionally for Flow and Safety.

Benefit lengths were decided by expert judgement. Decisions were made collectively during

meetings involving Neale Hider, Lucy Shuker, Laura Beardsworth, Amanda MacLean and Tom

Perry.

Adjustments to benefit lengths

Correcting for duplication of water body lengths

The Duke of Northumberland's River at Mogden (GB806100095) is a surface water transfer

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Detail

water body in its own right, but is also included in the Crane (including part of the Yeading Brook)

(GB106039023030) water body river line. To avoid double counting benefits along this reach,

2.93 km of benefits (equivalent to the length of the Duke of Northumberland's River at Mogden)

were subtracted from the Crane water body.

Benefits from improvements to water bodies outside the Crane catchment

Improvements to water quality in the Colne catchment (in particular phosphate stripping at

sewage treatment works) are expected to provide some benefits to the Crane (), both branches

of the Duke of Northumberland's River (), and the Longford River.

In order to distribute these benefits in a straightforward and simple manner between the two

catchments it was decided to transfer the benefit lengths for Clarity and Plants from the Crane

operational catchment to the Colne operational catchment. This is based on the principle that

Clarity and Plants are the categories most impacted by actions to improve water quality in the

Colne catchment. We estimate that the benefits to plants from physical modification measures

will be roughly equal to the benefits to fish and invertebrates from water quality measures, so the

overall transfer of benefits between the two catchments should be reasonably accurate.

The methodology and reasoning for the transfer of benefit lengths to the Colne operational

catchment is described in Appendix A.

Once these adjustments are made, the total percentages of river length improved by the

recommended bundle of measures in the Crane operational catchment are, for each NWEBS

element:

Clarity 82%

Fish 90%

Invertebrates 67%

Plants 49%

Flow 54%

Safety 65%

Sensitivity testing WAG section 7

Sensitivity test results are as follows:

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Detail

Baseline Whole life costs x 5 Whole life costs x 2 Whole life costs x 0.8

Change in one off costs for

BCR to approximate to 1.0

Bundle ref Bundle name BCR 1.96 0.392367387 0.98 2.45 1.105096831

1 Crane midpoint costs NPV £ 43034837.34 -135934532 -1707505.00 51983305.81 2x

50% decrease in km

benefited Using low WTP value Using central WTP value Using high WTP value Risk of failure is 0% Risk of failure is 25% Risk of failure is 50%

1.01 1.62 1.96 2.30 2.62 1.96 1.31

603867.66 27891158.10 43034837.34 58178516.58 72293897.23 43034837.34 13775777.44

This assessment passes all of the sensitivity tests except for Whole Life Costs x 2, which

resulted in a BCR of just below 1. However, this is considered to be an unrealistic scenario. Our

own high-cost scenario passed the cost benefit analysis with a BCR of 1.65. The majority of

costs in the high-cost scenario are either provided by the water company, or uncertainty has

already been built into the costings in assigning a maximum likely cost. Therefore doubling these

figures is not considered to be realistic.

Appraisal Summary Table WAG section 3 and 5

The AST records the following benefits as having significant positive benefit:

Recreation and tourism

Aesthetic value

Intellectual and scientific, educational

Provision of habitat

The following benefit categories were recorded as having minor positive benefit in the AST:

Fresh water

Existence Values

Social relations

Much of the benefit recorded in the above categories is not monetised in the calculated NWEBS

benefits for the catchment. This means that the overall benefit for the catchment is likely to be

higher than estimated in the Present Value Benefits figures shown above.

None of the benefit categories recorded an overall negative impact as a result of the proposed

measures. However, potential minor negative impacts were identified in the case of:

Heritage - Minor adverse impacts on the substantial cultural heritage of the Crane were identified as possible, but avoidable. Impacts can be prevented or mitigated for by designing proposals so that they will not damage the cultural heritage (e.g. by installing a

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Detail

fish pass around a historic mill structure, thus avoiding change to the historic structure itself).

Water for non-consumptive use - Minor adverse impacts of weir removal could limit the opportunities for future hydropower schemes. However, any scheme would be small-scale and there is currently no hydropower in the Crane catchment. Improved flow in the lower Crane should have a positive impact on the potential for hydropower that would balance out these negative impacts.

These minor negative impacts should not affect objectives.

Engagement operational instruction (450_13) section 2

Internal

The Crane Catchment Coordinator (Amanda MacLean) held a series of meetings and

discussions with members of the following teams:

Costing measures – Biodiversity (Neale Hider, John Bryden), Geomorphology (Lucy Shuker), Fisheries (Phil Belfield, Planning & Strategic Overview (Anna Parr), Integrated Environment Planning (Tom Perry), Karen Douse (Land & Water)

NWEBS benefits – Biodiversity (Neale Hider), Geomorphology (Lucy Shuker), Integrated Environment Planning (Laura Beardsworth, Tom Perry)

AST - Integrated Environment Planning (Laura Beardsworth)

External

Measures incorporate WFD-related actions from the The Crane Valley - a Water Framework

Directive Catchment Plan produced by the Crane Valley Partnership.

A summary of the process was discussed informally with several key members of the Crane

Valley Partnership, including the catchment host. Partnership members have been invited to hear

further details on the process and results in February 2014.

Any other supporting information such as key uncertainties, other rules of thumb used

and key assumptions made

Nominally the base year for the financial numbers in all CBAs Nationally is 2012 based on the

NWEBS values. Consequently all other financial numbers should be either inflated or deflated to

their 2012 level. However due to the overall uncertainties around costs, savings and other

financial benefits we have not applied an inflation or deflation factor. It is thought to try and use

RPI/CPI to adjust costs to a 2012 base level would suggest a level of accuracy to the financial

numbers we do not have. It is assumed the use of cost ranges and the standard national

sensitivity testing will help to assure a BCR outcome fit for the purpose of a high level

assessment.

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Detail

COSTS

The costs are mostly derived from local costs (based on data from local projects, studies

and experience of area staff); in some cases they were derived from the National Cost

Effectiveness Database and taken as provided there.

Capital costs are placed in the first year of the assessment (2015/16) unless we have

evidence of where capital costs will be spent over the time horizon.

We assume operational costs will occur in the first year after capital costs 2016/17 and will

continue for the remaining time horizon. Operational costs that occur for shorter period of

time are included in capital costs.

Water Companies’ costs for water quality measures are placed in line with the schedule

provided by them.

Urban Diffuse Pollution actions were costed using the National Urban Diffuse Pollution

Calculator, with modifications as described above under 'Costs'.

BENEFITS

It is assumed benefits start two years after capital expenditure (so in most cases 2017/18)

and will continue for the remaining time horizon unless we have local or national evidence.

As a rule NWEBS baselines and status changes are selected in accordance with National

recommendations in the FAQ. However local evidence and expertise was used to

override these rules of thumb when required.

We do not include any financial cost savings or additional financial benefits unless we

have local or national evidence.

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Appendix A

The methodology and reasoning for transferring benefit lengths to the Colne operational catchment is described

below.

Duke of Northumberland’s River at Heathrow (water body ID: GB806100108)

The whole length of this river will benefit from water quality improvements in the Colne.

Longford River (included in Port Lane Brook water body ID: GB106039023450)

The whole length of this river will benefit from water quality improvements in the Colne.

River Crane downstream of Duke of Northumberland’s River at Heathrow; Duke of Northumberland’s River at

Mogden (lower section of Crane (including part of the Yeading Brook) water body ID: GB106039023030; water body

ID: GB806100095)

SAGIS modelling found that 43% of the phosphate in the Crane was derived from sewage treatment works in the

Colne. We therefore need to apportion 43% of the benefits to the Colne catchment. The easiest way to do this is to

apportion the length improved between the two catchments. The Crane, downstream of the Duke of Northumberland’s

River at Heathrow, is 10km, so 43% is 4.3km. The Mogden reach of the Duke of Northumberland’s River is 2.93km, so

43% is 1.26km. We have therefore apportioned 4.3km of benefits from the Crane and 1.26km of benefits from the

Duke of Northumberland’s River to the Colne.

The Crane operational catchment - Crane Valley … · The Crane operational catchment Thames River...

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