northumbrian water

Northumbrian Water

Ouseburn Flooding - Brunton Park Meeting

17th January 2006

Introductions

Les Hall – Investment Delivery Team Leader

Presentation Topics: -

• Flooding 2005 – An Overview

• Progress to Date

• Key Findings

• The cause of flooding on 30th June 2005

• Growth

• Future Plans

• Timescales

Sewer flooding – significant events

• 2005 – significant sewer flooding events

Contact numbers

14/15/16/17 April 376

19 June 707

30 June 312

13 August 207

31 August 764

9 September 275

12/13 October 220

24 October 232

Sewer flooding – monthly contact

Sewer flooding contact trendsNovember 2000 - October 2005

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Phone Written

Sewer flooding daily call volumes1 April 2005 - 31 October 2005

0

50

100

150

200

250

300

350

400

450

500

1-A

pr-0

5

8-A

pr-0

5

15-A

pr-

05

22-A

pr-

05

29-A

pr-

05

6-M

ay-

05

13-M

ay-0

5

20-M

ay-0

5

27-M

ay-0

5

3-Jun

-05

10-J

un-

05

17-J

un-

05

24-J

un-

05

1-Jul

-05

8-Jul

-05

15-J

ul-0

5

22-J

ul-0

5

29-J

ul-0

5

5-A

ug-0

5

12-A

ug-

05

19-A

ug-

05

26-A

ug-

05

2-S

ep-0

5

9-S

ep-0

5

16-S

ep-

05

23-S

ep-

05

30-S

ep-

05

7-O

ct-

05

14-O

ct-0

5

21-O

ct-0

5

28-O

ct-0

5

Sewer flooding – daily call volumes

DG7 operational contact breakdown

51%

9%

7%

14%

1%

6%

4%

0%

0%8% 0%

29%

10%

9%7%

4%

8%

13%

0%

0%

20%

0%

Sewerage

WaterQuantity

Water Quality

Water Ops

WaterContractors

Leakage

Meters

Billing

Leisure Ops

Misc

Nonregulatory

2004/05 2005/06

Acomb Crescent, Fawdon - Progress to date – Operations

• CCTV of 3 km

• Sewer Cleansing almost complete (3 km)

• Flap valve installed on Surface Water Sewer

• New Grill and safety railings installed on Overflow

• CSO chamber de-silted as part of regular maintenance programme

Acomb Crescent, Fawdon - Progress to date – Investigation

• Independent consultant appointed - Entec

• Entec have visited site and spoken to some residents to

understand flood mechanisms and establish all areas affected

• Hydraulic model revisited and updated

• Details of 30th June fed into the model

• Model predicts flooding in the areas where actually experienced

Key Findings – Ouseburn

• A1 Western Bypass & Retail Park discharge to Ouseburn u/s of Redhouse Farm Estate

• Intense rainfall causes Ouseburn to react quickly

• Ouseburn re-profiled by EA since 2000

• Ouseburn levels can be higher than weir level in the Combined Sewer Overflow

Key Findings – Initial Investigation

• Rainfall data not available for 30/6/05 – unable to attribute a return frequency for this ‘extreme’ very localised event

• Hydraulic model predicts incapacity at 1 in 10 year event and flooding could occur without the influence of the Ouseburn

• River levels are however a significant factor in terms of frequency and severity of flooding

• Had river level been that of 2000 flooding in 2005 would have been much worse

• Siltation of continuation pipes and mechanical screen have a small effect of spill volume

The Cause(s) of Flooding

• ‘Extreme’ very localised rainfall event (30/6/05)

• Incapacity in part of the Combined Sewer network

• Levels of the Ouseburn

• Topography and relative position/level of properties to the Ouseburn

Invert of Sewer 49.76m AODLow spot (65-77 Acomb) 50.45m AODCSO Weir 50.55m AODOuseburn (30/6/05) 50.78m AODOuseburn (20/9/00) 51.09m AOD

Proposed development within the Ouseburn catchment

• 320 Houses on Cell G of Newcastle Great Park• Additional Cells of Great Park• Hotel Development at Newcastle International

Airport• Business Park at south side of airport

Proposed peak foul sewage flows from development

Development 2006 2007 2008 2009+ Max FoulFlow

320 Houses at Cell G ofNewcastle Great Park

1 l/s 3l/s 3 l/s 6 l/s 13 l/s

Additional Cells ofNewcastle Great Park

0 1 l/s 2 l/s 2 l/s + 5 l/s +

Hotel and Filling Stationat Airport

0 9 l/s 0 0 9 l/s

Extension of AirportSouthside Freight Village

0 4 l/s 4 l/s 3 l/s 11 l/s

Total ( l/sec) 1 l/s 17l/s 9 l/s 11 l/s + 38 l/s +

2006 onwards

• Identification of short term measures to prevent flooding (where possible)

• Commence Feasibility Study – Identify potential solutions (advance works already underway ie flow monitors)

• Prioritisation of Project in Sewer Flooding Programme

• Catchment Study incorporating further developments at Great North Park and Newcastle Airport

• Continued liaison with Red House Farm Residents Association/customers

• Continued liaison with EA & Newcastle City Council with particular regard to the Atkins Study.

Timescales

• Cause Report review 15 Dec 05

• Identification of short term measures by end Jan 06

• Feedback to RHF residents (7/12) and Newcastle Great Park Advisory Committee early Dec 05

• Completion of Feasibility Study (relies on weather dependant surveys)

• Major catchment study planned completion by March 07

• Following prioritisation the scheme would be programmed accordingly

• Construction typically 3 to 12 months depending on size/complexity

QUESTIONS ?