Written report from topographical survery completed on Laxey River

Summary

The requester sought the written report and recommendations for a 2016 topographical survey of the Laxey River, which had been omitted from a previous request. The Manx Utilities Authority provided the survey report detailing flood risk management improvements, though the overall outcome was noted as partially exempt.

Key Facts

• The survey was conducted by Storm Geomatics Limited for the Douglas and Laxey Flood Risk Management Improvements project.
• The survey covered multiple watercourses including River Laxey, Glen Roy, Glen Mooar, The Breem, and Laxey Mill Race.
• An E2 grade permanent control station (E2-Laxey Base) was installed and processed against Ordnance Survey Active Rinex Stations.
• Two new E6 grade permanent control stations (E6-1A and E6-2A) were installed for future reference.
• Survey equipment used included a Leica GS14 Smart Antenna and a Leica TS15 R1000 Total Station.

Data Disclosed

• July – August 2016
• 2019-09-11
• 2019-09-25
• 17 pages
• 2 documents
• 243065.727
• 485150.967
• 48.089
• 244245.113
• 483804.923
• 5.410
• 243291.246
• 484670.050
• 41.082
• 16MU10017
• PO135907
• 941145
• 954701

Original Request

I would like a copy of the written report and recommendations that accompanied the topographical survey that was completed on Laxey River in 2016 or near to that date. This is a further request to your ref 941145 as whilst I was provided with the survey drawings the written report and any additional supporting documents were omitted.

Data Tables (5)

Full Response Text

REPORT OF SURVEY FOR LAXEY

Project: Douglas and Laxey Flood Risk Management Improvements
Watercourses: River Laxey (LAXE01), Glen Roy (ROY01), Glen Mooar (GLEN01), The Breem (BREE01), Laxey Mill Race (MILL01), Glen Roy Mill Race (GRMR01) and Lake Inlet Pipe (LAKE01). Type of Survey:

Channel & Topographic Surveys Drawing Numbers: Please see Transmittal Document Storm Geomatics Job No: 16MU10017 Client Name Job No: PO135907 Date of Survey:

July – August 2016

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

To:
Manx Utilities

PO Box 177

Douglas

Isle of Man

IM99 1PS

From: Storm Geomatics Limited

Unit 28

Ditchford Farm

Nr. Moreton-in-Marsh

Gloucestershire

GL56 9RD

Date of Survey: July - August 2016

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Contents

1.0 Scope

2.0 Survey Control

3.0 Topographic Survey

4.0 Presentation

5.0 Health & Safety

6.0 Comments

Appendix I Control Processing Information Appendix II Self Certification Forms Appendix III Additional Site Photos

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Report of Survey

1.0 Scope

1.1 Survey requirements were set out as follows:

1.2 The survey brief amplifies and amends the Environment Agency National Standards Contract and Specification for Surveying Services (Version 3.2 and subsequent amendment).

2.0 Survey Control

2.1 An Environment Agency (EA) specification E2 grade permanent control station was installed on site to use as control for the entire survey. This station was occupied for a period in excess of 8 hours and the resulting data then processed against the nearest 4 Ordnance Survey (OS) Active Rinex Stations. The Station was also processed to the IOMS Rinex station and BASE 1 DOUGLAS. This gave a baseline spread of 23mm and the IOMS baseline was used for final Station Coordinates due to its proximity. Details of this can be found in appendix 1. The final result was then transformed to the OS Grid and Douglas 02 Datum using the

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

OSGM02 and OSTN02 geoid and transformation models. The final coordinates for the new station are detailed in the following table:

2.1.1 Table showing the final coordinates for the newly installed E2 grade control station:
Station Name Eastings Northings Height (mADD) E2-Laxey Base 243065.727 485150.967 48.089

2.2
Two new Environment Agency (EA) specification E6 grade permanent control stations have also been installed on site to be used for future reference. The new E6 control was installed as a pair with one being permanent and the other temporary. A closed loop level run was then completed between them and a ‘best fit’ adjustment made to the height value.

2.3 Control description sheets for newly installed control can be found in appendix 1. The following table outlines the final coordinates for newly installed control:

2.3.1 Table showing the final coordinates for the newly installed E6 Control stations:
Station Name Eastings Northings Height (mADD) E6-1A 244245.113 483804.923 5.410 E6-2A 243291.246 484670.050 41.082

2.4 Both of the new E6 control stations were also measured using 10 seconds of RTK observations from the new E2 base station (E2-Laxey). The following table shows the difference between the Network RTK and Base – Rover RTK observations:

2.4.1 Table showing the comparison between full E6 derived heights and those derived from Base – Rover via E2-Laxey: Station Name E6 Grade Value RTK Value Difference E6-1A 5.410 5.410 0.000 E6-2A 41.082 41.093 -0.011

        2.5

Existing control installed around the new road bridge in Old Laxey has been observed with the elevation results outlined in the following table:

2.5.1 Table showing differences between surveyed and existing control values: Station Name Existing Value (mADD) Surveyed Value (mADD) Difference STN 1 6.036 6.025 0.011 STN 2 7.550 7.552 -0.002 STN 4 6.282 6.299 -0.017 STN 5 7.186 7.214 -0.028

3.0 Topography

3.1 All files relating to detail survey observations and computations are held on Storm Geomatics server in Leica Geo Office format.

3.2 The detail has been surveyed using a Leica GS14 Smart Antenna and a Leica TS15 R1000 Total Station. The following self checks were made:

• Daily check measurements of the detail pole height were taken to a known point with the daily results comparing favourably outlined in the table below:

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Date Eastings Northings Height (mADD) 19.07.2016 243097.241 485145.331 49.024 20.07.2016 243097.231 485145.330 49.018 21.07.2016 243097.241 485145.326 49.022 22.07.2016 243097.225 485145.322 49.019 24.07.2016 243097.232 485145.326 49.019 25.07.2016 243097.236 485145.322 49.010 26.07.2016 243097.232 485145.318 49.015 27.07.2016 243097.237 485145.320 49.014 05.08.2016 243097.247 485145.316 49.019 06.08.2016 243097.255 485145.314 49.009 06.08.2016 243097.238 485145.308 48.999 06.08.16 Chk 2 243097.238 485145.313 48.996 07.08.2016 243097.250 485145.321 49.009 08.08.2016 243097.253 485145.322 49.030 Mean 243097.240 485145.321 49.015 Standard Deviation 0.009 0.006 0.009

3.3 The survey as a whole has been quality checked by Anthony Pritchard - Director

4.0 Presentation

4.1 The survey is presented as CAD drawings in .dwg format.

4.2 Digital data is supplied via the web.

5.0 Health and Safety

5.1 There were no incidents to report. All members of the site team were briefed at each location by the senior surveyor as to the hazards on site and the method of work.

6.0 Comments

6.1 In consultation with the 2015 winter flood victims along Old Laxey Hill and Back Shore Rd, many residents attribute the cause to blocked road culverts uphill rather than a direct inadequacy of the channel to contain the high flow. This backlog caused the Old Laxey Hill road to become a torrent which flowed through driveways and property on its way downhill. 6.2 Dangerous collapse of right bank upstream of Laxey Glen Mills by playground and public toilets. Subterranean utilities exposed.
6.3 Concrete channel wall is part-destroyed and right bank has collapsed along footpath alongside Laxey River near Sports Club, Glen Rd (Appendix III; Images 3 & 4), also subsiding of the damaged stone walls likely (Appendix III; Image 5 ). 6.4 Left bank collapse and concrete wall destroyed at rear of property downstream of Basketball Court, Glen Rd (Appendix III; Image 6). 6.5 Dilapidated wire mesh fencing needs to be removed from channel by The Salmon Centre, near The Laxey Wheel.

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

6.6 Staff at Laxey Wheel site voiced concern for lack of maintenance to the overflow piping.
6.7 After speaking with expressed concern about a concrete plinth installed without planning permission at the crest of a large weir. This plinth was installed by Stuart Clague (Salmon Lake Centre) and restricts flow of water over the weir crest.
6.8 Many residents expressed concerns over the height of the new laxey road bridge. Concern was also about the ability for overland flow of water to now make its way across the flat deck of the bridge and inundate properties on the right bank of the river.
6.9 Upstream extent of reach 3 was very overgrown, with a large +15m high water fall surveyed, open channel cross sections were moved to represent the crest and toe of the weir. 6.10 All river channels within the laxey catchment were very steep, with large amounts of rock and boulders washed down during the 3rd December flood event. 6.11 Glen Mooar (Laxey Wheel Stream) is an exceptionally steep river channel, with bedrock weirs and drops along its entire length. Cross Sections have been moved to represent the crest and downstream toe of the largest of these drops. 6.12 After a site walk with laxey parish commissioners and

concern was raised over the overall state of surface drainage, as well as the drainage allowing surface water to enter the watercourse. Concern was also raised about the combined surface runoff/ sewage system in laxey village not being able to cope with combined surface and riverine flooding.
6.13 All residents spoken to raised concern with the Swales Access Bridge. During the 3rd December flood event this bridge was blocked by trees and debris swept down the channel.
6.14 Laxey Woollen mill raised concerns over the starting position of the flood wall on the left bank immediately downstream of the confluence between the Laxey River and the Glen Roy River. The flood wall does not extend upstream to the bridge, leaving a large gap that could cause major flooding to property and businesses on Glen road. 6.15 Laxey Parish commissioners were concerned that the old mining structures and weirs within the Laxey River channel may be causing a restriction to the channel (Between LAXE01_0918 & LAXE01_0990). These were the site of the 1930’s flood that damaged a large area of Laxey.

Signed: ……………………………………………. Date: 26/08/2016

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Appendix I

Control Processing Information

No.1 E6 Original Level Runs E6-1A Level Run

E6–2A Level Run

No.2 E6 Adjustment E6-1A Adjustment

E6-2A Adjustment

No.3 E6 Final Level Run E6-1A Final Level Run

E6-2A Final Level Run

No.4 Station Description E2-Laxey E6-1A E6-2A

No.5 GNSS Processing Summary - BLANK

No.6 Gauge Board Description Sheets

GB-SC 4368 8402

Appendix II

Self Certification Check Forms

Appendix III

Additional Site Photos

Image 1

Image 2

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Image 3

Image 4

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Image 5

Image 6

Laxey Flood Risk Management Improvements Survey Date: July – August 2016 .

Image 7

Image 8

Manx Utilities PO Box 177, Douglas Isle of Man, IM99 1PS

e: enquiries@manxutilities.im t: 01624 687687 www.manxutilities.im

Our ref: 954701 25 September 2019

Dear ###

We write further to your request which was received on 11 September 2019 and which states:

"I would like a copy of the written report and recommendations that accompanied the topographical survey that was completed on Laxey River in 2016 or near to that date. This is a further request to your ref 941145 as whilst I was provided with the survey drawings the written report and any additional supporting documents were omitted."

Our response to your request is as follows: Please find attached the Report of Survey for Laxey dated August 2016.

Section s25(b) While our aim is to provide information whenever possible, in this instance we are unable to provide some of the information you have requested because it is absolutely exempt under section 25 of the Act (absolutely exempt personal information). The reasons why that exemption applies are that: • Manx Utilities is satisfied that the information amounts to personal data of which you are not the data subject; and • Manx Utilities is satisfied that disclosure of the information would contravene one of the data protection principles as set out at Article 5 of the General Data Protection Regulation as it applies in the Isle of Man pursuant to the Data Protection (Application of GDPR) Order 2018, namely that Manx Utilities can only disclose the information where it would be fair, lawful and meet one of the conditions for lawful processing in Article 6 and in this case, none of those conditions have been met. Please quote the reference number 954701 in any future communications.

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I will now close your request as of this date.

Yours sincerely