RESERVOIRS ACT (1975)

SUPERVISING ENGINEER'S REPORT

Reservoir Name : Lawton Hall Lake Reservoir

Inspection Date : 8 May 2013

Report Date : 31 May 2013

Supervising Engineer: K D GARDINER

Undertaker : Mr and Mrs Haddon

This report is issued in accordance with the requirements of Section 12 of the Reservoirs Act

(1975).

* Appointed to the panel of All Reservoirs Engineers under the Reservoirs Act 1975 until 30

July 2017

REPORT CONTENTS

SECTION 1. Supervising Engineer’s Statement and Summary

SECTION 2. Record of Inspection

SECTION 3. Document Inspection

SECTION 4. Description of Site and Conditions Found

SECTION 5. Recommendations of Last Statutory Inspection

APPENDICES - used and updated as required

Appendix 1 Summary of Statutory Reservoir Inspections

2013

Appendix 2 Sketch of disused overflow and drawdown

facilities

1988

Appendix 3 A selection of photographs taken during the

inspection

2013

RESERVOIRS ACT (1975)

SUPERVISING ENGINEER'S STATEMENT AND SUMMARY

Reservoir Name : Lawton Hall Lake

Date of Inspection : 8 May 2013

Supervising Engineer : K D Gardiner

STATEMENT OF COMPLIANCE

This is my first report as Supervising Engineer. The last statutory Section 10 inspection was carried

out by Dr A K Hughes on 22 January 2008. Under the current undertaker the reservoir has not been

operated in accordance with the Reservoirs Act or with the requirements of the previous Inspecting

Engineer. Almost all the recommendations of the previous Inspecting Engineer have not been

carried out.

The latest statutory Section 10 inspection was carried out by me on 8 May 2013. The next statutory

inspection should be carried out on or before 22 January 2017

OTHER COMMENTS

The present owners/undertakers did not receive the last Section 10 report on purchase of the

reservoir or any other documentation and were only made aware of their duties and liabilities

under the Reservoirs Act by the Enforcement Authority.

I was appointed as Supervising Engineer by letter dated 25 April 2013

Supervising Engineer:

Date:

Section 2 Record of Inspection

Name of Reservoir: Lawton Hall Lake Reservoir

Supervising Engineer: :K D GARDINER

Reservoir undertaker and owner: Mr and Mrs Haddon

Kendal

Brown Edge

Stoke-on-Trent

Tel 07737 281829

Accompanied by: Mr and Mrs Haddon

Date of Inspection: 8 May 2013

Water Level at Time of Inspection: At Top Water Level.

Weather: At Time of Inspection: Fine and dry and quite cool.

Preceding Period: Mostly dry

Hazards Identified Prior to Inspection None

Hazards Identified During Inspection None

SECTION 3. DOCUMENT INSPECTION

Schedule of Drawings & Microfilms

Original Drawings/Tracings held at: None.

Datum Level: None

Level of lowest point on overflow: Reported to be 101.72*m AOD. (This is probably the level

of the concrete overflow channel invert.)

Comments: No drawings or other documentation was available except two previous inspecting

Engineers’ Reports and the last Supervising Engineer’s report made available to me by the

Enforcement Authority.

Mr and Mrs Haddon did not receive any documentation from the previous owners and were

unaware of their duties and responsibilities under the Reservoirs Act until notified by the

Enforcement Authority that a Statutory Inspection was overdue.

Statutory Reservoir Record

No Prescribed Form of Record was available for inspection.

Instrumentation

None

SECTION 4. DESCRIPTION OF SITE AND CONDITIONS FOUND

INFLOW CONTROLS & BYWASH ARRANGEMENTS

(i) Inflow Control Structures: There is no inflow control

(ii) Bywash Channel: A bywash channel runs next to the reservoir on the west side in open

channel and in culvert. The bywash runs into the overflow culvert through the west abutment of

the dam.

At the head of the reservoir the Kidsgrove brook enters a brick culvert which connects to the

bywash. The upstream headwall to this culvert has collapsed at some time in the past and the

roof of the culvert is exposed locally. The headwall and the first 5 or 6 metres of the culvert are

within land belonging to Lawton Hall Farm. There was a fallen sapling across the entrance to

the culvert and the flow was within about half a metre of the soffit. If this culvert should become

blocked or collapse the stream will back up, overtop the access track constructed over the culvert

and enter the reservoir. Collapse of the culvert will also cut off the farm buildings from the

meadows to the east of the reservoir.

The track alongside the bywash has been fenced by the adjoining landowner which blocks

access. Gates should be provided to obtain access for tree management and bank repair.

The bywash is culverted for most of its length, the longest section past Lawton Hall being more

than 200m long. The portals appeared to be in good condition at present but are being damaged

by tree roots. The culverts were not inspected internally. The culvert cross-sections appeared

similar to that through the dam abutment. The ground above the culverts supports large trees and

root infiltration is inevitable.

The open sections of bywash are very overgrown and the banks are crumbling in places. There

are fallen trees alongside the bywash and saplings growing out of it which could be lifted and

carried downstream in a severe flood.

Where there is no culvert, the dividing bank between the bywash and the reservoir is variable in

nature. The bank has been brought to level since the last Inspection. The bank carries a

significant number of mature trees and some were reported to have fallen into the reservoir on

the last inspection, but there were none on this occasion. Should fallen trees move into the

reservoir they could block the spillway.

(iii) Other Structures: None.

RESERVOIR SITUATION

(i) Valley Sides: The side slopes above the bywash are locally quite steep, and on the right

hand side of the reservoir the land slopes gently toward the reservoir and is devoted to arable

farming.

(ii) Access: Access to the dam crest is via a stone surfaced track, about 500m long, provided

as part of the works in 2003. Access to the track is off a small housing estate road named “The

Spinney” which is off the A34 Kidsgrove to Congleton road. Access along the track is

constricted by a 3m wide farm gate at the entrance and by overhanging trees which could be

quite easily cut back in an emergency if required.

EMBANKMENT OR DAM

(i) Upstream Face:

The upstream face slopes steeply down to a low masonry retaining wall at about Top Water

Level approximately 4m below the crest. To the left of the dam centreline the wall is mostly

intact although there are many saplings and shrubs growing within it and from the base. To the

right of the centreline the wall has all but disappeared. Above the wall the slope is generally

about 1 in 2 although the bank is very uneven and contains flatter sections and areas where the

face is almost vertical. There are many large tree stumps in the right-hand of the face. It appears

that a tree has at some time fallen into the reservoir and taken a large part of the wall with it.

Mr Haddon informs me that below the wall the slope is much flatter and then steepens again but

this is impossible to verify at the current water level.

At the right-hand end of the dam, a flat area has been excavated into the face to accommodate a

large canvass bivouac structure used as protection when fishing. The slope behind this structure

is almost vertical and consists of bare earth and tree stumps.

(ii) Crest:

The crest, which carries a well trafficked carriage road/footpath, is in a satisfactory condition

with good line and level. There is a car park just beyond the west abutment. The crest can be

used for access. Erosion has been caused by the run-off from the tracks leading onto the dam

(iii) Downstream Face:

The downstream face is very steep and has no grass cover. The line and level is generally good

but the face supports a significant number of mature trees and saplings. The toe of the dam is

very wet, overgrown and difficult to inspect.

(iv) Drainage:

The toe of the embankment is very wet and boggy with standing water. This area is very

overgrown and it was not possible to identify any drains or observe any flows. There is reported

to be a drainage system in this area but none can be found.

In addition there is a surface stream that comes down the valley just off the right hand mitre.

The channel is very close to the mitre as the stream turns away from the dam and it is clear that

high flows in the stream could flow onto the dam.

OVERFLOW WORKS

(i) Overflow Weir & Approach:

The main overflow consists of a reinforced concrete channel forming a broad crested side weir

some 1.55 metres wide and 0.65 metres deep, discharging into the bywash. The weir is fitted

with grooves for stop-logs. The bywash is faced with large stones through and over which the

flow runs. There is no formal spillway channel into the bywash. The channel is spanned by an

open mesh steel walkway.

The water level at the time of the inspection was at about TWL with small waves lapping over

the overflow. One stop-log about 300mm high was padlocked in position within the stop-log

channels built into the structure.

The bank adjacent to the weir is lowered on either side of the overflow structure by a depth of

about 0.35 metres and the whole area reinforced with interlocking concrete blockwork to provide

an auxiliary spillway. The armoured length extends approximately four metres north of the

overflow and 6m to the south. At either end there is an armoured slope 2m long up to the

general level of the bank. Again there is no formal channel to convey the flow to the bywash.

.

The approach to the weir was clear and the channel structure itself appeared to be in a

satisfactory condition. There was reported, at the last statutory inspection in 2008, to have been a

spillway consisting of a concrete slab which had broken up. There was no sign of it on this

occasion, just very rough rocks and pieces of concrete lining the bywash bank. There were also

large rocks in the bywash itself and at the culvert entrance.

The open mesh steel walkway spanning the overflow channel is somewhat bent and is partially

supported with timber props made from branches.

There were many sticks and leaves lining the channel invert and one medium sized log. The face

of the bywash in the position of the spillway was also strewn with such debris.

The reinforced grass section of spillway appeared to be in a satisfactory condition but again there

is no formal spillway chute into the bywash.

The far bank of the bywash appears to be in natural rock. It appears that there was once some

formal rock protection from the impinging flow but this is now in a very poor state.

There are a number of trees, saplings and bushes growing near to the spillway and around the

upstream culvert portal.

(ii) Discharge Culvert:

The bywash is carried past the dam in a brick culvert some 2.6 metres wide and 1.75 metres

high. The culvert is approximately 44 metres long and is constructed through the left hand

abutment of the dam. The culvert has a change of direction to the left about 15m from the

downstream portal. The base of the culvert is flat and strewn with rocks.

The flow was such that the bywash and overflow culvert could be entered with care. The

brickwork appeared in good condition. It is reported that the culvert brickwork was grouted in

2003. The base of the culvert is flat and strewn with rocks. There was a tree stump lying in the

culvert at the downstream portal.

(iii) Stilling basin

There is a cascade structure at the downstream end of the culvert. The first step is in brickwork

about 1.2m high and below this there is a reinforced concrete stilling basin. The sidewalls are

stepped and taper outwards. There is a v-notch formed in the end wall of the basin. This

structure was built as part of the 2003 improvements.

The stilling basin is in good condition but erosion is occurring due to water overtopping the

sidewalls of the basin. The headwall at the downstream portal of the culvert is in poor condition

with many missing bricks. The wall appears to have been buttressed in brick and masonry on

either side at some point but the support to these buttresses appears to have been lost during the

construction of the new basin.

DRAWOFF WORKS

(i) Outlet works

These works are indicated on the schematic prepared by Mr Davies as part of his Statutory

Inspection report in 1988. (See Appendix 2) The records indicate that there were drawoff

facilities at the left-hand end of the dam that apparently have been sealed up, however I was

unable to locate any of these facilities during my inspection.

(i) Scour facility

Records indicate that there was a ‘well’ some 900 mm in diameter in the left-hand abutment,

upstream of the crest, discharging to a culvert at the base of the dam in the north-west corner.

Mr Davies describes the well as brick lined, containing water at the same level as the reservoir

and having an ancient corroded windlass across its top. It is likely that this was once part of the

scour arrangement which was sealed in 2003.

SECTION 5 Recommendations from the last Statutory Inspection

I carried out the S10 inspection on 8 May 2013 but as a historical record I have reported in detail on

the recommendations of the last Inspecting Engineer. Subsequent S12 reports will include my S10

recommendations and the actions taken, although most of my recommendations are similar to those

from the previous S10 which have generally not been carried out.

Inspecting Engineer: Dr A K Hughes

Inspection Date: 22 January 2008.

Recommendations Comments

1 Recommendations in the “interests of safety”

a that the wall at the base of the upstream face be

repaired.

Not carried out

b all trees and saplings are cut back/removed from

the wall.

Not carried out

c the apron on the downstream side of the overflow

be rebuilt.

Not carried out

d all trees and saplings in the area around the

entrance to the culvert be removed.

Not carried out

e an assessment of the hydraulic capacity of the

culvert be undertaken for flows up to the 1000

flood event and the side walls raised to ensure no

erosion of the dam or the stilling basin structure

occurs.

Not carried out

f the crest of the bywash channel divide wall be

filled to give as level a slope as possible to

prevent overtopping by perhaps forming an

access track which would help maintenance

This has been done.

g the shaft and the depression be investigated to see

whether the culvert is properly sealed and the

results of the investigation reported to an All

reservoirs Panel Engineer.

h the toe drainage be rebuilt. Not carried out

i the stream adjacent to the dam be cleared out and

fill placed on the outside of the bend to prevent

water flowing onto the dam.

Not carried out

j the owner prepares a plan to enable the water

level to be reduced in an emergency.

Not carried out

k a Prescribed Form of Record be obtained and

filled in

Completed by the Supervising

Engineer May 2013.

l a secondary spillway be created over the top of

the embankment and down to the stilling basin as

a reinforced grass spillway designed and

constructed under the directions of an All

Reservoirs Panel Engineer

Not carried out

Other Measures Recommended to be taken

but not requiring Supervision by a Qualified

Civil Engineer within the Meaning of the Act

a the mature trees be managed by trimming and

pollarding to reduce their height and their spread.

Some trees have been cut down on

the upstream and downstream faces

of the dam.

b all saplings be removed from the embankment Not carried out

c a grass cover be encouraged on the upstream and

downstream faces.

Not carried out

d the grass on the embankment be cut regularly to

maintain a good grass sward and a strong root

growth.

Not carried out

e any potholes on the crest be filled as and when

necessary

This appears to have been done.

f an interceptor drain is created just off each end of

the dam and the drain constructed to discharge

either to the reservoir or to the stream

downstream.

Not carried out

g the metal bar at the entrance to the culvert be

removed

This has been done

h the approach to the spillway be kept clear. This has been done

i the stones that have moved into the bywash

channel be pulled back

Not carried out

j the trees and bushes be kept back (at least 1m)

from the spillway.

Not carried out

k an inspection of the culvert be undertaken by the

Supervising Engineer when low flow conditions

allow.

The culvert was inspected on 8

May 2013

l the bywash channel be kept clear of debris. Not carried out

m any trees that have fallen into the reservoir be

removed.

There are no fallen trees in the

reservoir.

n the trees on the bywash channel divide wall be

managed/trimmed and pollarded.

Not carried out

Measures Recommended in the Interests of

Improving Monitoring and Supervision under

Section 11 of the Act

a the areas of dampness on and just off the toe be

watched for signs of increased flow or turbid

flow.

Not carried out

b water levels are recorded at least once a month

and at times of high flows

Not carried out recently

c someone should visit the site at least once a week. This has probably occurred

Matters to be watched by the Supervising

Engineer in accordance with Section 10(4) of

the Act

I recommend that the Supervising Engineer visits

the site at least once a year and pays attention to

any settlement, leakage or movement and in

particular ensures that:-

1 the Prescribed Form of Record is complete This has now been completed

2 the spillway is kept clear The spillway is relatively clear.

3 he watches for signs of seepage Not carried out recently

Recommendation as to the date of the next statutory inspection

The next statutory inspection should be carried out on or before 26 June 2017.

APPENDIX 1

Reservoir Data Summary

Name of Reservoir : Lawton Hall Lake Reservoir

Flood Category of Reservoir: C

Map Reference: SJ 825 558

Use: Fishing Lake

Date of completion of construction: Between 1645 and 1760

Type of Dam: Earth embankment dam probably homogeneous.

Maximum Height: 12m.

Crest Length: 100m

Spillway type: Side weir into bywash.

length: Spillway channel 1.55m Lowered section of dividing bank 7m

level: Spillway channel 101.72mAOD* Lowered section of dividing bank 102.5 mAOD*

*These levels require verification

Freeboard: 2..36m.

Peak outflow: 16 cumecs This was reported as the 1 in 100yr flood by Mr D Davies

Freeboard at peak (incl wave surcharge): 4.4m

Upstream protection: Stone wall at TWL partially collapsed..

Draw-off & Scour: None functional

Valve arrangements: None .

Constructional Difficulties & Subsequent Major Works

None recorded.

APPENDIX 1

Summary of Statutory Reservoir Inspections ________________________________________________________________

This is not a full list. It has been compiled from the information made available to me.

Inspection Date Engineer Précis of Main Recommendations and Comments

(Period to next inspection) _______________________________________________________________

8/2/88 D DAVIES . (19 months)

R1. Every flood like that of 23 Aug 1987 be recorded

R2 Bypass repairs be undertaken and loose timber and bushes which may

block the tunnel be cleared with some pollarding.

R3 The tunnel and stilling poll be de-watered for inspection.

R4 A permanent overflow as a stop-log groove be constructed and used

temporarily for water diversion during de-watering.

R5 The downstream haunch of the dam be better drained by rodding and

cleaning out two brick culverts

R6 Careful but restrained exploration of the newly discovered well, whetherit

links with the downstream culvert.

R7 A transverse trench be cut across the dam crest to prove the position and

quality of the clay core.

R8 Any direct feeding of the inlet stream into the lake should have regard to

its quality as advised by the Water Authority.

R9 A detailed section of the dam at its greatest height with soundings within

the lake be carried out to ascertain the depth of silt and whether slips have

occurred within the lake.

R10 Abandoned or redundant work such as the eastern lake overflow br

properly sealed.

R11 The SE to oversee the above and advise the Inspecting Engineer when

critical stages (if any) are reached, as informed by the owner.

R12 The undertakers pursue a strict policy of vigilance and active correction

in order that the tunnel enjoys free passage of water at all times.

R13 The above remedial works be completed in such a way as the owner

thinks best.

R14 It is possible that during the repair work amendments may be dictated by

the nature of the environment, when the Supervising Engineer should be

informed.

R15 The remedial works should be completed by October 1st 1989

R16 The next inspection should take place not later than October 1st 1989

25/9/00 P G Mackey (Mr Mackey refers to his reports of July 1993, Sept 1993, Dec

1993, January 1994, October 1994, October 1999 February 2000. However no

details of the recommendations are given He also refers to a report by Mr D

Davies of May 1990 but again no recommendations are quoted.)

1. Statutory records should be maintained.

2. Investigations are required as follows –

a) Clearing of the dam and exposing all hydraulic structures

b) Clearing of culverts and drainage including the east mitre overflow

c) CCTV investigation and reporting as to conditions of the culverts

and overflows

d) West mitre diversion culvert : This to be investigated structurally

and with regard to capacity. Requires surveys and calculations.

Recommends a computer numerical model

3. Works of Safety (currently foreseeable)

a) Repair and maintenance of west mitre diversion channel and

associated culverts

b) Formalization of drainage at eastern mitre upstream and

downstream. Ponding, formalising outfalls to overflows and culverts.

c) Work of reconstructing the west mitre inlet diversion channel

including outlet conditions downstream.

d) Additional work identified to hydraulic structure valves etc in

confirming the design requirements for making the dam safe and

certifying in accordance with the Act.

e) Work associated with draining the downstream shoulder and

associated areas in improving stability.

Works in providing an adequate overflow structure from the lake.

(5 years)

Reports of Supervising Engineers under the Reservoirs Act 1975

Only one report is available

DATE OF VISIT SUPERVISING ENGINEER

18 May 2011 F K Swettenham

APPENDIX 2

Sketch of disused overflow and drawdown facilities.

APPENDIX 3 A selection of photographs taken during the inspection.

P1 – Upstream face, retaining wall on left at TWL

P2 - Crest and downstream face

P3 – Upstream portal of overflow culvert

P4 “Spillway” into bywash

P5 – Overflow channel, one stop-log in position

P6 - Overflow structure in lowered section of bank

P7 - Downstream portal of overflow culvert and stilling basin

P8 – Entance to inlet culvert to bywash