Report on Morrison's Submission

REPORT ON MORRISONS’ SUBMISSION

TO THE

GLOUCESTER COUNCIL PLANNING COMMITTEE

CONSTRUCT A PETROL/FUEL FILLING STATION

AT THE RIDGE AND FURROW PUBLIC HOUSE SITE

“Demolition of the Ridge and Furrow Public House and the erection of a petrol filling station to include sales kiosk, canopy, 6 no. fuel pumps, forecourt, underground fuel tanks, carwash, alterations to boundary treatments and associated access arrangements. at Ridge And Furrow Glevum Way, Gloucester GL4 4BL”.

R.J.Cavaney BSc, MSc (hons), MSc (Mining & exp geol), AusIMM (f), SEG, GSA, SME. Consulting Geologist,

January 2014.

FRONTISPEICE

M5 M5 A

M TV

An oblique aerial Landsat view look ing southeast showing the setting of Morrisons superstore in th e middle centre (red ‘M’), part of the Heron Wa y Prim ary school (red ‘H’) right foreground. The Cotswold escarpment is in the background – a feature of natural scenic beauty along which the fa med Cotswold Way runs. The escarpment is capped by limestone and underlain by sands and clays that are prone to slumping. Nut Hill is shown as ‘NH’ (t urquoise) in the background. It is capped by harder silts and marlstone with Lower Lias Clay beneat h. The Ash Path (turquoise ‘A ’) runs along the Wheatridge to the right. This is cap ped by higher level glacial outwash terrace gravels on Lower Lias Clays. The Twyver River valley (turquoise ‘TV ’) is in the centre and left and flows over the Lower Lias Clays. The Ridge and Furrow pub is immediat ely to the left of the roundabout (red oval) back from Morrisons car park. The M5 motorway (Turquoise ‘M5’) r uns across the field of view along the edge of the residential area in the background. (The colours for the letters have no code significance but have been chosen for best visibility.)

3 CONTENTS 1 Introduction...... 4 2 Location ...... 5 3 Building a Petrol Filling Station on the site...... 6 3.1 Traffic Congestion Concerns ...... 6 3.1.1 The Effect on Schools and Pupil Safety...... 9 3.1.2 Traffic Accidents...... 10 3.2 Parking Concerns...... 13 3.3 Noise and Light Pollution ...... 13 3.4 Wildlife Concerns...... 14 3.5 Archaeology...... 15 3.6 Risk of flooding ...... 16 3.7 Local Geology...... 20 3.7.1 Outline of the Geology...... 20 3.7.2 The River Terraces...... 23 3.7.3 The Water Table...... 25 3.8 Geotechnical Considerations...... 26 3.8.1 Landslides ...... 26 3.8.2 Shrinking and Swelling Clay ...... 27 3.8.3 Thaumasite Sulphate Attack (TSA) ...... 33 3.9 Risk of Contamination...... 37 3.10 Previous Applications for a Petrol Filling Station ...... 39 4 Summary and Discussion...... 39 5 CONCLUSIONS...... 43 6 RECOMMENDATIONS...... 45 7 REFERENCES...... 45

4 1 Introduction

The actions proposed by Morrisons can be divided into two intended acts and will be treated as such in this report. The two intended acts are;- • Firstly, to demolish the Ridge and Furrow Pub House (pub). This is the subject of another report by the author. • Secondly, to build a Petrol/Fuel Filling Station (PFS) with attendant and ancillary structures on the site. This is the subject of the present report.

As this report contains technical sections, some explanations have been expanded to enable the members of the Planning Committee (and other readers) to understand geotechnical aspects of the geohazards present. To assist in this the writer has resorted to liberally inserted diagrams and illustrations. This has been done to assist the reader to visualise situations, aspects and potential events concerning the local geomorphology, drainage and geology.

Figure 1. View of the Ridge and Furrow pub south side showing one part of th e outdoor seating areas and a segment of the playground area in the right background where there is more seating.

5 2 Location The Ridge and Furrow public house (pub) is located at 20 Glevum Way, Abbeydale, GL4 4BL. The OSBG coordinates are SO 86030 East 15810 North, and NOT at (3)86032 East, (2)15740 North as in the Gloucester City Council Planning Permission Application Form as lodged by Rapleys LLP on behalf of Morrisons. The latter position places the building at the veterinary animal hospital location some 118m @ 350° True out of position. This may invalidate the application.

Figure 2. Map showing the location of the Ridge and Furrow pub in Gloucester. The light blue circle is at one mile radius. The light represents residential areas making up Gloucester city.

The frontispiece and above and figure 4 below are oblique aerial views and show the setting in Gloucester and Abbeydale. The topography is shown with the Ridge and Furrow site on the banks of the Twyver River. This river is confined by terrace edges some two metres high. The southern terrace edge bounds the Ridge and Furrow site. The Twyver River flows to Gloucester and as can be seen from Figure 9 it divides downstream from the Ridge and Furrow. One branch flows through the Saintbridge Balancing pond to Tredworth and Gloucester Park. The other branch flows through Coney Hill, is culverted between Trier Way and Barton street, and flows under Gloucester city.

6 3 Building a Petrol Filling Station on the site The second part of Morrisons intended action is to replace the Ridge and Furrow Public House with a Petrol/fuel Filling Station (PFS) with attendant structures including a car wash. There are concerns about several aspects that warrant commenting on. Other submissions already lodged validly raise similar concerns about part or all of the proposals by Morrisons.

3.1 Traffic Congestion Concerns Congestion caused by an increase in traffic is a major concern. That there would be an increase in traffic in the area by replacing the pub with a PFS is beyond doubt. Simple logic suggests this. Yet the Bryan G Hall traffic assessment (by Mr M. Crabtree 13 May 2013) submitted on behalf of Morrisons deduces on the basis of limited observations made in winter that traffic would actually be reduced by replacing the pub with a PFS. It factors in, amongst other things, deductions based on “linked journeys”. Again, simple logic says if there are fewer cars visiting the PFC than would visit the pub, it would not have enough custom and would therefore be uneconomic. Most people walk to the pub; everyone drives to a petrol filling station! The modelling software used (Arcady) may well be employing faulty logic in the modelling techniques applied. It is also possible that the sample taken was insufficient and not statistically meaningful. The Ridge and Furrow pub was actually closed – outside normal opening hours for part of the Bryan G Hall observation times! Certain of the deductions appear to be derived from apparently similar situations in other and distant locations. Application of such figures may not be valid especially if the baseline established for the Ridge and Furrow pub, or for that matter on other remote locations, is dependant on too small a sample as is apparent in the Bryan G Hall report.

Discussions with a statistician resulted in the following comments being made about one section of the Bryan G Hall report:- “Their logic in obtaining the results in Table 5.3 is flawed. They have tried to infer the "trip rate of the PFS" by subtracting "the actual measured trip rates into their current store" from "the average trip rate for a PFS and store from the TRICS database". You cannot subtract an "average rate from many locations" from an "actual rate at an individual location" as it does not account for the relative popularity of the individual location.” “To find the trip rate for a PFS they must subtract “the average trip rate for a PFS and store from the TRICS database" from, "the average trip rate for a store only from the TRICS database". This comment applies only to one section of the Bryan G Hall report, but doubt must be cast on the statistics in the whole report. The whole report needs to be carefully examined by a competent, independent statistician to ascertain why there are considerable differences between the Bryan G Hall report and the observations made by Mr Jones referred to below.

Recent surveys have been carried out and reported on by Mr. Kevin Jones and reported in his submission of 10th July 2013. These give a very different picture and arrive at contrary conclusions from those of the Morrisons commissioned report by Bryan G Hall 13th May 2013. Mr Jones shows that there may be an extra 13.000 cars in a six day period around the Abbeymead Avenue – Heron Way – Wheatway roundabout. This is very different from the “four journeys a day less” concluded in the Bryan G Hall report.

Significantly, Alison Curtis’s submission (4th June 2013) from the Highway Authority of the Gloucestershire County Council recommends that this application be refused on highway grounds.

Nth 4 5 3

2 6

12 10

1 7 13 9 8 Morrisons car park Morrisons car Glevum Way Way Glevum

Abbeymead Avenue

Figure 3. Part of the map from file “temp_doc_201307032222483853762-copy.pdf”; Bryan G Hall’s Drawing No. 12/365/TTR/005 dated 7/6/13 showing tanker tracking. The north point, street names and tanker position num bers have been added to clarify th e diagram for this report. The blue num bers in square boxes are tanker position numbers added for reference.

The Reasons given for the Highway Authority’s refusal to recommend are:- “Insufficient information has been submitted to enable the Local Planning Authority to satisfactorily determine the highway implications associated with the development proposed.” Further, concerns are expressed about the tanker delivery route (illustrated in Figure 6 below) :- “In a number of places the wheels of the tanker appear to make contact with k erbs and the body of the vehicle overhangs the footway and pedestrian crossing points, this is not acceptable” 8 Figure 3 shows that there is insufficient room to safely manoeuvre in the confined space the design has allowed for. This is particularly evident at tanker position numbers 3, 5, 9 and 11 on the map. There is insufficient room to safely deliver fuel to the site and to exit the tankers.

Note that the grey shaded area in figure 8 above is the two metre slope of the old Twyver River terrace edge with the old Upper Barnwood Mill Leat (‘drain’) at its base. A delivery tanker going out of control at any point from position 5 to position 6 in the diagram below would result in the tanker rolling down this slope and spilling fuel into the old mill leat. The latter discharges back into the main course of the Twyver river at a point some 100 metres downstream from the Animal Hospital culvert (Grid Reference SO 85982 16119). Significantly the Twyver River splits some 75 metres below this again (at Grid Reference SO 85997 16183), with one branch flowing through the Saintbridge balancing pond and on south of Gloucester Park. The second branch flows through residential suburbs past the Asda superstore and under Gloucester city. The Twyver drainage system is shown below on the aerial oblique of figure 4. More details are given in figures 13, 14 and section 3.6 below.

Figure 4. Oblique aerial view from approximately above Barton Street looking south east up the Twyver River which, along with other water courses, is shown in light blue. Morrisons is indicated by a white “M” centre. The Upper Barnwood Mill Leat can be seen left of Morrisons and the point where the course splits just down from that.

9 3.1.1 The Effect on Schools and Pupil Safety. There are two schools in the immediate neighbourhood. The nearest is only 370 metres northwest along Heron Way. The second is some 910 metres distant northerly along Abbeymead Avenue. Both these schools have over 400 pupils enrolled according to their websites. There are traffic problems including congestion at start and finish of school days already and the situation would be exacerbated should a PFS be constructed on the intermediary Abbeydale roundabout (see figure 7). Figures 5 and 6 show the present congestion during school ‘runs’.

Figure 5. Traffic congestion during the morning ‘school run’ at Heron Way Primary School. September 2013.

Figure 6. Traffic congestion during the afternoon ‘school run’ at Heron Way Primary School. (Note – image blurred to obscure number plates). September 2013.

A third school has recently been opened some two kilometres to the east at Coopers Edge over Lobleys Drive Bridge. This is thought to have a similar number of pupils now but will certainly be gaining more in the future. The Coopers Edge housing development is administered in part by Stroud District Council and by Tewkesbury Borough Council. There are to be some 1900 houses built here and it has been estimated by an officer in the Stroud Council Development Control Department that some 750 to 800 have been completed – that is about 40%. On completion there will be a significant increase not 10 only in school run journeys but also in general traffic. It is bad enough now during the school runs. There appear to be no submissions from any of these school’s representatives. It would seem that the schools, being a cause of and having a pupil-safely interest in, traffic congestion, should have been notified of the Morrisons proposal and invited to lodge a submission. Most people would put the safety of school children as a very high priority and be rightly concerned about it.

HS CC

M V

HW R&F

AA D C

Figure 7. An oblique aerial Landsat view north over the roads and roundabout at Abbeydale. Key:- M = Morrisons; R&F = Ridge & Furrow Pub; D = Dentist, Optician and Accountant; C =Church; V = Veterinary and Doctor’s Surgery; HS = Heron W ay School; CC = Comm unity Centre, HW = Heron Way; WW = Wheatway; AA = Abbeymead Avenue. The letter col ours in this figure have been chosen to be seen against a variably coloured background and have no code significance.

Topically, The Citizen of 11th January 2014 has an article (page 5) expressing concern about school run chaos and children in danger at a Gloucester school. The chaos already being experienced at the Abbey Ward schools can be expected to worsen with consequent increased danger to local pupils should a PFS be built near Morrisons supermarket.

3.1.2 Traffic Accidents Crashmap (http://www.crashmap.co.uk/Search) records traffic accidents in the Abbeydale area and there are shown on figures 8 and 9. It can be seen that there is a clustering of accidents around the ‘Morrisons’ roundabout where Herron Way, Abbeymead Avenue, Glevum Way and the Wheatway meet with some ten being recorded, two serious. There are about a dozen accidents recorded along and close to Herron Way on which the Herron Way School is located. Figures 10 and 11 show the accidents in which a child was involved. Note that there are three such accidents along Herron Way and two close to the Abbeymead Primary school. The figures from Crashmap are only those up to 2012. In 2013 there were at least one more right at the Abbeydale roundabout and another in Glevum Way at the mini-roundabout. There may have been more in 2013. There certainly will be many more in the future should a PFS be built right on the roundabout!

Figure 8. Crashmap street map centred on Morrisons Roundabout and showing the traffic accidents in the Abbeydale area up to 2012.

Figure 9. Crashmap satellite image of the same area as figure 13. 12

Figure 10. Crashmap street map of the Abbeydale area showing the traffic accidents involving children.

Figure 11. Crashmap satellite image of the same area as figure 15.

13 3.2 Parking Concerns. The two nearest neighbours beyond (north of) the proposed PFS along Glevum Way – the Hadwen Medical Centre and the Veterinary Animal Hospital have lodged submissions expressing concern about parking and access to their premises for their customers/clients/patients. Some of these need to get very close to their front doors, and at times with emergency vehicles. These are very valid concerns. There are only some 22 parking spaces for the Veterinary Animal Hospital, the Hadwen Medical Centre and the adjacent pharmacy. Most of these spaces are taken up by staff and indeed many need at present to park on Glevum Way on the opposite (west) side of the road, inevitably constricting access to the street’s north end.

There are concerned objections submitted to the planning department from residents and other businesses in the vicinity about the loss of parking on removing those spaces currently available in the present Ridge and Furrow car park, (approximately 54 spaces). The latter are used by visitors to the Hadwen Medical Centre and the adjacent pharmacy. Some ten parking spaces are used by medical centre and pharmacy customers on a regular basis as shown on figure 12.

H P

Figure 12. Photograph of the ten or so parking spaces within the Ride and Furrow pub parking area used on a regular basis by patrons of the Hadwen Medical Centre (H) and the adjacent Pharmacy (P).

The loss of parking spaces in this area is a very real concern. Morrisons themselves have reduced their parking spaces by some ten to fifteen by opening up their gardening area. What other spaces will disappear in the future when other facilities such as a mechanic’s shop are dreamt up by Morrisons’ management?

3.3 Noise and Light Pollution Other concerns submitted from nearby residents specify an increase in noise & light pollution. Although there seems to be reluctant acceptance of present levels from Morrisons’ supermarket, worries by those living nearby and likely to be affected, are that any increase would be a source of unhappiness and dissatisfaction. This would especially be the case for those residents close to Abbeymead Avenue, many of whom have got up their own petition objecting to replacing the pub with a PFS. This has been lodged with the panning department (21st June 2013) along with letters from the residents. 14

As part of the inevitable increase in traffic associated with an operating Petrol/fuel Filling Station is the coming and going of heavy tankers at all hours of the day and night. Some of the submissions from local residents point up that the heavy delivery trucks for the supermarket are noisy and disruptive enough as is without compounding the situation with fuel deliveries that are closer to Abbeymead Avenue. No matter what the present Morrisons’ commissioned study concludes, it may be taken as axiomatic that there will be an increase in numbers of heavy tankers on the adjacent roads by erecting a PFS.

One prime concern for noise is the possible car wash. These are very noisy. The Hadwen medical centre management have expressed worries about the noise in their submission. Other washes nearby are underused. Hand wash places now seem to be more in favour. In any event there are sufficient car washes and another is definitely not warranted at the Abbeydale location.

In fact the whole Petrol/fuel Filling Station is unnecessary and not just the car wash. There are at least six other PFS’s nearby and another has been recently constructed at Morrisons’ new location on the Railway Triangle.

3.4 Wildlife Concerns. The area immediately to the east of the Ridge & Furrow pub, the Hadwen Medical Centre and the Animal Hospital is a natural corridor for wildlife to pass through and to reside along. It is the Twyver River course with aquatic habitats and trees. Badger activity was recorded during a wildlife inspection in January 2013 by the Environmental Authority. There has been a reported sighting of a badger just to the north recently. There was talk of relocating the badger set at one time. Urban foxes are common in the nearby suburbs and undoubtedly use the habitats within the Twyver valley. Ducks are not uncommon along the river and there are fish and aquatic birdlife downstream. Pheasants have been observed in the Twyver corridor and bats are usual around the lights of the Abbeydale Community Centre in the evenings. Newts are present in the water features of local resident’s gardens and no doubt use the Twyver River and old mill leat, as do water voles. The latter are commonly seen adjacent the Community Centre and Glevum Way park. The Twyver River splits in two some 360 metres below Abbeymead Avenue with one course (probably the pre-historic original course) flowing to the Saintbridge balancing pond and on to the Park in Gloucester. The second course, probably excavated in historical times to bring water in to Gloucester City, flows to the area north of Barton Street near Asda’s car park where it is culverted under the city. This arm supplied the old city moat and the cathedral. Both arms of the Twyver River empty in to the Severn River. The Twyver River and its tributaries and divisions can be seen on figure 9. Figures 13 and 14 show the local drainage in more detail.

Fuel spills into the River Twyver in the past have resulted in a considerable number of fish deaths at the Saintbridge balancing pond. The Subadra Consulting Ltd (Subadra) Report of March 2013 documents this. Swans are present at this pond and have nested there.

216200NE m m 216200N m 85600 385700E m 385700E 3 m 385800E m 385900E m 386000E m 386100E m 386200E m 386300E m 386400E m 386500E m 386600E

216100N m 216100N m SCHOOL

216000N m 216000N m

UPPER BARNWOOD 215900N m MILL 215900N m

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385 m 385700E m 385800E m 385900E m 386000E m 386100E m 386200E m 386300E m 386400E m 386500E m 386600E

Figure 13. Vertical aerial photograph of the Abbeydale area showing the Abbeymead Avenue – Wheatway – Herron Way roundabout (centre). The position of the Upper Barnwood Mill taken from the 1885 map is shown in yellow in between the old mill leat and the Twyver River in light blue. The Community Centre can also be seen between the two water courses. The split (diversion) of the Twyver River can be seen top left of the image. The green lines mark the old roads, again taken from the 1885 map.

3.5 Archaeology The Upper Barnwood Mill ruins dating to the 13th century are located to the east of the Ridge and Furrow pub. The mills of the River Twyver, of which there were some eleven, have been studied by Mr I. M. Hollingsbee MA, JP, noted local historian and author. The Twyver River is some 90 to 100 metres east of the site but the tail race overflow or mill leat is only ten metres east at the foot of an approximately two metre slope that marks the confining river terrace edge. The Upper Barnwood Mill between the Twyver River and the old mill leat can be seen on figures 13 and 14.

Mr. A. Armstrong in his memo of 7/8/2013 Points out that the site “has some archaeological sensitivity. Previous archaeological investigations to the west and the north have recovered finds of prehistoric and Roman date. The site is also located c.40m to the west of the known site of a medieval watermill.” He recommends archaeological investigations prior to any development.

Early (pre-Saxon?) habitations are likely on the terrace where the pub is. There was one near the Saintbridge balancing pond. They occur where better drained higher gravels occur but still close to a stream. The better drainage here results from the old glacial outwash gravels derived from the Wheatridge. The latter has been mapped a Severn S3 Terrace remnant by the British Geological Survey (BGS), (see Section 3.7 Local Geology).

16 385900E m 386000E m 386100E m 386200E m

d216200N m 216200N m i ve r si o n c ha nn e l

216100N m 216100N m Tw yve

r Riv

216000N m 216000N m drainage

ch a nnel UPPER BARNWOOD 215900N m MILL 215900N m

Ridge & Furrow Pub

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W he at ri y dg a e w t 215700N m a 215700N m e h W

385900E m 386000E m 386100E m 386200E m

Figure 14. Map showing the Upper Barnwood Mill (red), Twyver River and mill leat (blue) and old roads (green) taken from the 1885 map and overlain on a more modern map. The grid is OSGB.

3.6 Risk of flooding Although there is little risk of the Ridge and Furrow site being flooded, there are potentially adverse circumstances that would be greatly exacerbated by flooding. When Abbeymead Avenue was constructed during suburb building, it is almost certain that the function of the Upper Barnwood Mill leat in flood alleviation was not recognised. According to Mr. Hollingsbee, the mill ceased working in 1921 although the building remained. By 1934 the pond was dry. However in times of flood the old mill leat would play a significant part in alleviating the effects. The Twyver River at Abbeymead Avenue has a culvert several metres across but the old mill leat was blocked off. At the back of the Animal Hospital, the mill leat was culverted using a 34 cm pipe to go under Glevum Way. The mill leat continued as an open ‘drain’ alongside the west side of the Abbeydale Community centre. Just before the July 2007 floods the ‘drain’ or old mill leat was inexplicably culverted through a 34 cm pipe to beyond the north end of the Community Centre a further distance of some 50 metres. This severely 17 exacerbated the flood problem and the community Centre has been flooded now several times. Valerie John points this out in her submission. Figure 15 shows the inadequate culvert behind the Animal Hospital. It is 2.2 metres below the centre of the Ridge and Furrow car park. Figures 16, 17 and 18 show the flooding at the Abbeydale Community Centre in July 2007. Enquiries of the Environmental Agency then elicited that no flow rates had been recorded for the Twyver River to that time.

Figure 15. The inadequate 34 cm culvert for the old mill leat at the rear of the Animal Hospital.

Figure 16. The Abbeydale Community Centre between the Twyver River to the right (east) and the flooded old mill leat in the foreground. July 2007. 18

Figure 17. The east side of the Abbeydale Community Centre where the old mill leat has been culverted through a 34 cm pipe constricting flow and exacerbating flooding. July 2007.

Figure 18. The footbridge over the Twyver River east of the Abbeydale Community Centre (to the right) looking west towards the Animal Hospital. The river bed here is 1.5 metres below the Bridge deck and 3.09 metres below the centre of the Ridge and Furrow car park. July 2007.

19 Flood alleviation work since has been confined to the Twyver River’s course; removing a couple of trees and replacing the footbridge shown in Figure 18, making no difference to flow volumes or rates. The very important old mill leat has been ignored as it is mostly a small drain and only conducts large quantities water in flood conditions. These water courses are shown on figures 13 and 14 above.

Eventually the council engineers will realise the positive effect that the old mill leat had on flood alleviation and reconfigure the drainage system. The mill leat needs to be culverted under Abbeymead Avenue with a culvert as big as that for the Twyver River. The ridiculously small 34 cm culver at the rear of the Animal Hospital (figure 15) and on the west side of the Abbeydale Community Centre will need to be replaced with a culvert at least a metre wide. Flooding will occur again with or without culverts but they will dramatically lessen the severity and allow more rapid recovery by getting the water away far more quickly. Mr Hollingsbee has compiled very illustrative video clips showing the intensity and effects of the 2007 flooding in the area.

At about 5 pm on Wednesday January 1st 2014 – New Years Day, the Abbeydale Community Centre was closed because the Twyver River was rising and there was a fear that the Centre would be flooded. An inspection at 6 pm showed the water level was some 15 cm below the adjacent footbridge (shown in figure 23). This is some 80 cm (~32 inches) below the July 2007 level.

As stated, the actual site the Ridge and Furrow pub sits on is not really in danger of flooding. However, paradoxically, the re-opening of the old mill leat as an inevitable and necessary response to future flood alleviation for the Community Centre will have a deleterious effect should underground fuel storage tanks be installed as part of PFS construction. This is explained further in Section 3.9 Contamination below.

Note that the Lithos Consulting Limited (Lithos) Report (their section 9.3.2), and the Westwood submission on Groundwater Assessment (October 2013), wrongly describe the Twyver River as being 900 metres east of the Ridge and Furrow pub and flowing in the reverse direction to actual.

20 3.7 Local Geology

3.7.1 Outline of the Geology The sequence of sediments in the Severn Valley area has been assigned to an age known as the Jurassic. It comprises Lower Lias Clay (also called the Charmouth Mudstone) in the valley overlain by harder silts and marlstones of the Middle Lias, then sands of the Upper Lias and finally limestones capping the escarpment. Thus, topographically the Cotswold Hills to the east of Gloucester are topped by limestone with the foothills and slope beneath them made up of sand and marl. The low lying Severn Vale plains are of clay. To the west of the Severn River and underlying all this sequence are older rocks of the Triassic, as at Westbury. Figure 19 is a block diagram illustrating this sequence.

Figure 19. Simplified geology of the Gloucester area (From Dreghorn 1967).

The Lower Lias clays have thin bands of limestone in them. The clays are about 200 metres thick near Gloucester, thickening to the north towards Evesham and thinning southwards towards Bristol. The east tilted limestone escarpment of the Cotswold Hills has been retreating eastwards as it erodes. This has been happening over a long period of time. In the course of this ongoing scarp retreat, hills with harder caps that have resisted erosion have been left behind as ‘outliers’. Robinswood Hill, Chosen Hill and Bredon Hill are examples of this. The former are capped by the harder (Middle Lias) Dyrham Silts and Marlstone Rock Bed that overly the Lower Lias Clays. It is these harder beds that form the ‘Cotswold sub-edge on Dreghorn’s block diagram of figure 19. Above the harder Dyrham Silts and Marlstone Rock Bed are the softer sands and clays of the Upper Lias. These are prone to slumping causing disruption to roads along the escarpment such as the A46. The hard limestone cap of the Cotswolds may also fail and be carried down hill with this slumping and landslip behaviour.

It is just beyond the Cotswold Sub-edge, slightly west of Nut Hill where the Twyver River is no longer restricted and is able to spread out over the flatter and softer lower Lias Clays. This can be seen in figure 9 and the frontispiece.

Figure 20 below is a stratigraphic column that shows the rock types, their thicknesses and sequence.

TRIASSIC

Figure 20. Generalised stratigraphic column of the rocks in the Gloucester area. (Brit. Geol. Surv. 1972). The Lower Lias Clays are some 200 metres thick at Gloucester.

Nut Hill is capped by the harder Dyrham Silts that overlie the Lower Lias Clays. Where they occur on a steep slope such as on the southwest side of Nutt Hill, the underlying Clays exhibit slumping. On the southwest side of Nut Hill, the Dyrham Silts are cut by a fault that is up thrown on the southwest side. This fault has been mapped by the BGS running east south-easterly for some 3.5 km and may join to the Througham Fault that curves to run south for at least another 11 km to near Edgeworth and Oakridge. The west north-westerly extension of this fault at Nut Hill would run down the Twyver River course and may be the reason why the river is where it is. Figure 21 is a map showing Nut Hill, the fault and its extrapolation along strike.

Nut Hill

Slumping

Figure 21. Map showing the Dyrham Silts on Nut Hill outlined in yellow with the BGS mapped fault in dark blue. The west north-westerly extrapolation of the fault is shown in light blue. The red lines mark the recent terrace edge bounding the Twyver River northwest of the M5 motorway. The red “A” indicates the Abbeydale roundabout.

Figure 22. Vertical aerial image covering the same area as figure 21 showing the Dyrham Silts capping Nut Hill in yellow, the BGS mapped fault in dark blue and its extrapolation west north-westerly is in light blue. The terrace edges bounding the Twyver River northwest of the M5 are shown in red. 23

Figure 23. An oblique aerial view south-easterly showing the Dyrham Silt cap to Nut Hill with the fault and its extension running along the course of the Twyver River. The bounding terrace edges of the latter are in red. Morrisons, th e Abbeydale Roundabout and the Ridge and Furrow pub can be seen in the centre foreground.

3.7.2 The River Terraces The terrace edges bounding the Twyver River shown in red on figures 21, 22 and 23 are one to two metres high and comparatively recent. They are post-glacial and an earlier set of terraces of River Severn outwash gravels occur at a higher level. These have been designated “S3, Third Main Terrace Gravels of the River Severn” by the British Geological Survey. These are mapped on figures 24 and 25 below. Figure 26 shows these gravels exposed in an opening made July 2013.

The Wheatridge

Figure 24. The terraces associated with the Twyver River. The A bbeydale roundabout is shown as a red “A”. The older and higher “S3, Third Main Terrace Gravels of the River Severn” are outlined in light blue. The younger bounding terrace edges to the river are show n in red with areas of recent stream sediments within the current river bed outlined with light green lines.

Figure 25. A vertical aerial image covering the same area as that in figure 24.

25 The earlier “S3” river terrace gravels, outlined in light blue on Figures 24 and 25, once covered a much greater extent but have been eroded to the remnants present today. These gravels on the Wheatridge contributed material that irregularly covers the areas on either side to depths of about a metre including the Ridge and Furrow site. These were encountered in the drill holes put down by Lithos Consulting Limited (Lithos) Report and described in their report as “made ground”. They are shown in figure 26.

Figure 26. The older and higher “S3, Third Main Terrace Gravels of the River Severn” (of the BGS) exposed in a pit along the path from the Abbeydale Community Cent re to the traffic lights on Abbeymead Avenue by the Abbeym ead Pri mary school. The grey gravels can b e seen beneath the bitumen path. To the right beneath the gravels can be seen the yellow-brown Lower Lias clays. (OSGB Grid Ref. SO 86320E 16221N; some 500 metres at 035°T from the Ridge and Furrow pub.)

The same gravels were also exposed in pit Lobleys Drive (OSGB Grid Ref. SO 86753E 16305N) near Brome Road; some 880 metres at 055°T from the Ridge and Furrow pub.

3.7.3 The Water Table Several submissions to this hearing have speculated on the presence, absence or the whereabouts of the “water table” in the area and especially at the Ridge and Furrow pub site where Morrisons would wish to store fuel underground. The Lower Lias Clays are impervious to water or can only be permeated by it extremely slowly unless cut by a fracture, fault, shear or man-made opening. The whole of the Lower Lias Clay unit is a giant ‘aquaclude’ or ‘aquifuge’; that is, it stops water from passing through it. An aquaclude is in effect the opposite of an aquifer that contains and/or conducts water. The clays form a barrier that holds water beneath and above them. The water above the clay aquaclude are said to be on a ‘perched’ water table.

26 Thus, the Twyver River is on a perched water table. Its bed at the Community Centre footbridge is some 3.09 metres below the Ridge and Furrow car park (below the base of the light pole in the centre of the car park). The old mill leat at the back of the Animal Hospital is 2.2 metres below the Ridge and Furrow car park. These points can be taken as the (perched) water table at those locations. Any water held within the one to two metres of outwash gravels (or ‘head’) at the Ridge and Furrow site would be on a perched water table above the impermeable Lower Lias Clays. However mostly they would drain east to the mill leat and river. Should an excavation be made such as for installing fuel tanks, these would be subject to water percolating in and this would be the water table (perched) at that point. The fuel tanks would then be below the water table.

3.8 Geotechnical Considerations There are key geohazards involved in the engineering geology of clays and mudstones. Information for the following discussion concerning geotechnical matters is extracted among other sources, from Hobbs et al (2012 British Geological Survey internal Engineering Geology report on the Lias Group) ; from the BGS Engineering Geology Maps by Dearman et al (2011), and from BRE Special Digest 1 (2005); - see the References section for full details.

3.8.1 Landslides Britain does not suffer from landslide hazards on the scale of some parts of the world. However, there are a large number of landslides (believed to be in excess of 10,000) existing largely as a result of Britain’s glacial and periglacial history. It is apparent that Lias Group rocks are markedly landslide- prone and are on record as having the highest incidence in the UK. The types of inland landslides within the Lias Group in the Cotswolds are multiple rotational, cambering, debris slides and mudslides. Landslide complexes within the Lias Group may be extensive, and though some are ancient in origin, they may become partially reactivated by engineering and building activity or by changes in climate and water regime. Landslides are not particularly evident in the Lower Lias Clays (Charmouth Mudstone) below the Dyrham Silts and Marlstone Rock Beds that cap the hills as at Chosen Hill, Robinswood Hill and Nut Hill partly because the terrain is not ‘hilly’ enough and the slope is not steep. However they can occur where the slope is steeper such as on the hills mentioned. Above the Dyrham Silts and Marlstone Rock Beds where the slope is steeper on the Cotswold escarpment, landslips are common and stabilisation work is commonly undertaken on the A46 road where it crosses the Upper Lias below the oolitic limestones. It is the harder, protective limestone beds capping the softer sands and clays that cause the escarpment and attendant steep slope. At this stratigraphic level much of the highly adsorbent and shrink - swell Fullers Earth clay, used for wool degreasing, was extracted. The properties of the Lower Lias Clay types are the same as those of the Upper Lias that commonly cause landslips on the Cotswold escarpment. The Lower Lias clays beneath the harder capping of Marlstone Rock Bed and Dyrham Silts show evidence of landslips as do those on the southwest side of the Dyrham Silt capping of Nut Hill. The latter is some 1500 metres (approximately one mile) east south east of the Ridge and Furrow site.

In terms of the Ridge and Furrow pub site, the slope down to the bed of the Twyver River is not steep enough to make the terrace edge unstable under present conditions. However any ground disturbance due to engineering works or water access could reactivate old failures possibly associated with the Nut Hill Fault. Figure 27 below is taken from BGS Engineering Geology Map (Superficial) 2011 and shows the type of clay and soil movement that could occur on the two metre terrace slope that bounds the Twyver River immediately east of the present Ridge and Furrow car park.

Figure 27. Diagram s showing the type of slippage, slide and flow m ovements that can occur on clay and soil slopes especially in swell and shrink clays of the Lower Lias. This is likely to happen where excavations allow water egress adjacent terrace edge slopes. (From BGS, Dearman et al 2011.)

In wet winter conditions, this movement could result in downhill creep of hydrocarbon (fuel and oil) contaminated clays into the old mill leat of the previous Upper Barnwood Mill. During flooding, these would be washed into the Twyver River and its diversion.

The Britsh Geological Survey has a number of You Tube videos on Geohazzards at:- https://www.youtube-nocookie.com/embed/WLuVLfg3G1Q Amongst these is one on failure of retaining walls and slope failure: https://www.youtube.com/watch?v=fYjIdsJXE5k In this video it is pointed out that clays and sands can fail at very low angles. Lithos in their Appendix I report high plasticity.

3.8.2 Shrinking and Swelling Clay The British Geological Survey (BGS) web site gives information on Shrink – Swell at:- http://www.bgs.ac.uk/products/geosure/shrink_swell.html . They report as follows - “Shrinking and swelling of the ground (often reported as subsidence) is one of the most damaging geohazards in Britain today, costing the economy an estimated £3 billion over the past decade.” 28 “Many soils contain clay minerals that absorb water when wet (making them swell), and lose water as they dry (making them shrink). Many of us see this in our gardens when the ground becomes cracked during the summer, yet becomes 'heavy' in the winter.” See also:- http://www.bgs.ac.uk/products/geosure/animations/shrink_swell.html

Figure 28. A British Geological Survey m ap showing the areas of potential Swell – shrink hazard. Although Gloucester is in the area of “Moderate” classification, som e areas are classified as having “Significant” Swell – shrink geohazard. (Dearman et al 2011.)

The terrace on which the Ridge and Furrow pub stands is covered with a metre or so of gravels washed down from the old glacial material that caps the Wheatridge. The gravels are underlain by clays of the Lower Lias. According to Green (1992), these clays may have a higher proportion (up to 80%) of smectite group clays, probably montmorillonite (Deer, Howie and Zussman 1997). The clay mineral smectite in particular is the reason for the distinctive swell - shrink behaviour noted in the Lias Group mudstones and specifically within the Lower Lias Charmouth Mudstone, Blue Lias and the Dyrham Formations.

29 These clays have the characteristic of adsorbing water and swelling when wetted. They also give off the water and shrink on drying out. This swelling and shrinking gives the common pattern of cracks seen in the soils and bitumen roads/paths locally. Local samples show up 20% loss in weight by simple sun drying as the water is given off, such as for a 1.5 kg sample collected from 20 cm depth in mid- summer. That is, the sample was not at maximum water content but partly dry. Hobbs et al (2012) show that loss of 25 to 30% water can occur and result in a volume change of up to 30%. This is significant in foundation engineering. Lithos in their Appendix I report water contents to 29% and high plasticity.

Within the Abbeydale - Abbeymead area and indeed right along the Severn Vale, shrinkage cracks are common in lawns and gardens as well as bitumen footpaths and roads. These cracks can be up to 40 mm wide. Figure 29 shows such shrinkage cracks.

Figure 29. Shrinkage cracks to 40 or 50 mm wide opened up during summ er drying of soils derived from Lower Lias shrink /swell clays. This locality is about half a kilometre north of the Ridge and Furrow pub. The scale rule is 15 cm long. (21st July 2013).

The bitumen on footpaths is opened up and concrete curbing can be displaced. Shrinkage cracks are present on footpaths adjacent the Ridge and Furrow pub as in figure 30 because of the swell – shrink clays beneath. That there is about a metre of gravel between the bitumen and the shrink – swell Lower Lias Clays has not prevented the path from being badly damaged.

Figure 30. Shrinkage cracks in the bitum en footpath on Abbeymead Avenue immediately outside the Ridge and Furrow pub. There m aybe as m uch as a metre of re-sorted outwash gravels between the bitumen path and the u nderlying shrink/swell Lower Lias Clays; ye t the bitumen is still to rn by their movement. (30th July 2013.)

Similar cracks are evident on the Glevum Way bitumen footpath outside the Animal Hospital at the edge of the Twyver River confining terrace. These shrinkage cracks are very common locally.

The uppermost few metres of outcropping geological formations are subject to seasonal water content variations. These are often exacerbated by the presence of trees and shrubs, soakaways and fractured water pipes. In the case of clays, a decrease in water content causes shrinkage (an overall volume decrease) and an increase in water content causes swelling (an overall volume increase). These conditions are neither permanent nor exactly reversible, and may take years to develop due to the extremely low permeability of clays. Neither are they intrinsic properties of the soil or rock, but rather a response to prevailing environmental conditions. It is significant that the relationship between swell - shrink and water content is also non-linear. This phenomenon becomes particularly significant where shallow, foundations are concerned. This applies to houses and properties where foundation depths are generally shallower. Consequent structural damage results from seasonal and long-term volume 31 changes. A moderately dry summer will not necessarily result in major shrinkage of a clay soil, whereas a drought will. This may result in structural damage for buildings with shallow foundations, and disruption to services such as gas and water mains.

Cracks appear in brick houses and walls in the Abbey Ward area. Figures 31 and 32 illustrate this.

Figure 31. Fractured brick wall cau sed by swell/shri nk action of underlying Lower Lias Clays. Note that not only the mortar has failed, but the actual bricks are fractured as well. This locality is some 500 metres north of the Ridge and Furrow site but the same clays occur there too.

Where the clay rich unit is broken at surface for engineered fill and liners, rainwater egress and drying out in times of drought will affect the unit. Durability depends on mineralogy, porosity, cementation, and structure. Whilst older mudstones tend to be more durable, changes on exhumation and exposure to air can result in rapid breakdown and loss of durability.

Figure 32. Crack at second floor level in a house in the Abbey area. This house had extensive work done to repair major cracks some seven years ago. The cracks are now reappearing.

The best known type of this clay is Fuller’s Earth, present in the Cotswolds and previously used in the local wool and woollen cloth industry as it adsorbs the grease from wool. It is also used in other industries for the same purpose. It will adsorb hydrocarbons such as fuel or oil and undergo swelling and shrinking. The Upper Lias Clays and overlying limestones are the horizons through which the Sapperton Tunnel (Thames and Severn Canal Tunnel) passed and it was the swell - shrink clays present that caused its collapse.

The Britsh Geological Survey has a number of You Tube videos on Geohazzards at:- https://www.youtube-nocookie.com/embed/WLuVLfg3G1Q Amongst these is one on Swell-shrink clays: https://www.youtube.com/watch?v=WLuVLfg3G1Q In the case of the Ridge and Furrow, the causative clays are an extensive near-surface thick sheet, not a buried lens or pod of restricted extent.

33 3.8.3 Thaumasite Sulphate Attack (TSA) Oxidation of pyrite in any environment leads to the formation of sulphuric acid, which considerably reduces the pH of groundwater. Where such acidic groundwaters make contact with concrete foundations, the main cementitious binder, calcium silicate hydrate, or calcium silicate hydrogel, the main component of cement paste, may be converted to thaumasite (a non-binding calcium carbonate silicate sulphate hydrate) resulting in deterioration and failure. (Ettringite can be another product of this reaction.) Knowledge of the presence of sulphate-bearing species in Lias Group sediments is therefore crucial to foundation design and construction in such strata. (Hobbs et al 2012, BGS Internal Report OR/12/032).

Figure 33. A BGS Geosure map showing Sulphide Hazard Potential. Note that Gloucester is in an area classed as significant.

The BGS reports as follows on Sulphide Hazard:- “The deleterious effect of aqueous sulphate on buried concrete structures has been recognised in the UK since the mid 20" Century. In addition, ground heave associated with sulphate attack, has also become widely recognised. The principal form of sulphate attack occurs when sulphates react with calcium hydroxide and calcium aluminate hydrate to form 34 gypsum and ettringite. The formation of Thaumasite may also occur at low temperatures (5 – 15° C) in the presence of high pH water and free carbonate ions. Thaumasite formation is accompanied by large increases in volume and massive reduction in strength (BRE. 2005).”

Sulphates and sulphides are very common in Lias Group mudstones and clays. The damaging effects of sulphate salts on concrete, particularly below the water table, are well documented. For example, during construction of the M40 motorway in Oxfordshire, heave of the carriageway was caused when lime stabilisation of pyrite-bearing Charmouth Mudstone Formation (part of the ‘Lower Lias Clay’) was attempted. The layer concerned had to be removed. The best-known forms of sulphate in mudrocks are gypsum and anhydrite formed by the oxidation of sulphides. Sulphides, particularly pyrite (FeS2), are formed in anaerobic conditions through the action of sulphate-reducing bacteria and are generally found as dispersed microscopic minerals. Pyrite oxidation is complex but may be summarised as follows: a) Oxidation of pyrite to form ferric oxide (Fe2O3) and sulphuric acid (H2SO4), b) Reaction of sulphuric acid with calcium carbonate to form gypsum (CaSO4.2H2O), c) Reaction of sulphuric acid with clay minerals, if calcium carbonate is lacking, leaching them of exchangeable cations.

One of the end products of this process may be the formation of the sulphate mineral thaumasite. Oxidation of pyrite associated with weathering may be a slow process. However, buried concrete structures within Lias Group mudrocks are prone to thaumasite sulphate attack (TSA), particularly where the concrete is in contact with saturated un-weathered Lias-derived fill. The result is a transformation of the concrete fabric into a weak paste, which has serious consequences for the integrity of the concrete, and may result ultimately in failure.

Figure 34. A photograph showing the effect of sulphate rich water on concrete, converting it to thaumasite. (Hooton 2005).

Figure 35. A concrete block subjected to Thaumasite attack for 12 months. (Zhou, Judith 2003)

The overall total sulphate content median value (for the Lias Group formations for which BGS data were available) is 0.16 %, (=1.6 g/l = 1600 mg/l). The equivalent ‘water-soluble’ and ‘ground water’ values are 1.01 and 0.14 g/l, respectively. The Lias Group dataset is dominated by mudstones, in particular the Charmouth Mudstone. The Charmouth Mudstone Formation demonstrated the highest overall aqueous extract sulphate values and hence the greatest sulphate geohazard potential.

Lithos Consulting Limited (Lithos) in their Groundwater Assessment Report submitted by Westwood (October 2013), report chemical assays for sulphate in their Appendix I One sample has a result of 1600mg/l SO4 value. It is dismissed as being a spurious high. In fact it is the norm for Lower Lias Group clays (Hobbs et al (2012).

Figure 36. The result of sulphate attack on bridge columns, North Dakota. (Hooton 2005).

36 Thaumasite formed by sulphate attack on concrete has been found on twenty to thirty year old concrete structures on the M5 and other major trunk roads in Gloucestershire, Somerset and Wiltshire, in the Charmouth Mudstone Formation. Of the concrete structures investigated, 75% had been damaged, with abutments and columns being the most severely affected members. Thaumasite sulphate attack (TSA) is characterised by softening and expansion of the concrete surface as discrete blisters or across the full width of the face. The surface has a white pulpy appearance, or occasionally a ‘crust’ of apparently ‘fresh’ concrete, beneath which the coarse aggregate, is surrounded by white rings or halos of reaction products.

Figure 37. Form erly high quality concrete from a hi ghway bridge foundation th at has been severely affected by TSA. The outer 50 mm of concrete has been reduced to a m ushy reaction product rich in thaumasite. White halos of pure thaumasite can be seen around dolomite aggregate particles. BRE Special Digest 1 (2005).

The position of these areas of attack appears to be associated with groundwater level. At Tredington Ashchurch Road Bridge, (some 11 miles north along strike from Abbeydale,) one of the worst affected structures investigated, the maximum depth of softening and amount of expansion were approximately 45mm and 33mm, respectively.

The extent of thaumasite attack was strongly related to groundwater level. Thaumasite damage zones correlated with the maximum and minimum groundwater levels. Generally the concrete was not attacked above the maximum water level (i.e. permanently dry, except for percolating water); greatest attack usually occurred below the minimum water level (i.e. permanently wet), and partial attack where the groundwater level was between a maximum and minimum value. Also, sufficient groundwater sulphate and carbonate were both found to be required in order to form thaumasite.

Figure 38. Extrem e example of sul phate attach on a 30 year old bridge sub-structure exposed to wet, pyritic clay fill. BRE Special Digest 1 (2005).

A recent article in the Citizen Newspaper (14th January 2014 page 2) reports on repairs to M5 Bridge foundations as follows: - “From February, work will also begin to strengthen the foundations of three other bridges. They are the one carrying the A4173 Stroud Road over the Motorway in Brookthorpe; the Piff’s Elm Bridge at Junction 10 (A4019 Uckington); and the B4634 Old Gloucester Road over the M5 between Hayden and Staverton, north of Junction 11.”

3.9 Risk of Contamination. The risk of contamination is higher than has been recognised in previous submissions. As per the Subadra and Lithos reports, the “tributary” or “drain” mentioned is the old mill leat and is some 13 m east north east of the Ridge and Furrow building’s east corner, the east edge of the car park and the Animal Hospital building. It is at the bottom of the slope down from, (east of), the rise on which the pub is situated. The slope is about two metres high. This PFS, if built, would be the only one on the banks of a water course that flows near Gloucester city, let alone under and around it!

The plans for the PFS require burying large tanks to store some 250,000 litres (55,000 gallons) of fuel. This process would require excavations that go through the gravel and into the Lower Lias Clays. Water would eventually percolate into these excavations, pick up sulphate from the clays and immerse the concrete foundations in sulphate rich water. The foundations would be weakened by thaumasite attack. As described above, the clays have the characteristic of adsorbing water and swelling, then shrinking again on drying out. This alternate swelling and shrinking action would occur during wet winters and dry summers and could easily fracture the thaumasite weakened concrete foundations, and also fracture the fuel lines. This would result in fuel leakage into the surrounding clay formations. As 38 stated above, some of the fuel would be adsorbed by the clay but continued swell and shrink on the edge of the terrace would result in downhill creep of the weakened clay. Eventually the contaminated clay would reach the old Upper Barnwood Mill leat a few metres down slope to the east. A flood such as that experienced in July 2007 would spread this contaminated clay down the mill leat to the Twyver River some 280 metres downstream at OSGB Grid Ref SO 85982E 16119N. The possible scenario would be a series of wet winters and dry summers over a period of time followed by a very large flood as recorded in recent years.

It is important to note that the drainage of the Twyver River is not a simple, single channel with the old mill leat loop at Abbeydale. Some 65 metres below where the Mill Race rejoins the Twyver River at the footbridge, is a weir and diversion. This is at OSGB Grid Reference SO 85997E 16183N. The weir was probably put in when modern suburban housing was planned (1970s – 1980s). The river had been diverted in prehistoric times possibly by the Romans to carry water in to the city of Gloucester. This supplied water for drinking, to fill the city moat and even had a diversion to the Cathedral to supply the lavatorium and a mill. Figure 4, repeated below, shows the drainage pattern.

Figure 4. . Oblique aerial view from approximately above Barton Street looking south east up the Twyver River which, along with other water courses, is shown in light blue. Morrisons is indicated by a white “M” centre. The Upper Barnwood Mill Leat can be seen left of Morrisons and the point where the course splits just down from that. 39 Historically the water reticulation system was widespread and comprehensive. Much of the system is still in place. As the diversion to supply Gloucester city’s water ran at a higher level than the original river bed, it was easily cut between Hawthorne Avenue and the Saintbridge balancing pond and returned to its previous course by the besiegers in 1643 during the Civil War. From the present site of Asda on downstream the water course has been mainly culverted under the registry office and city. During Abbeydale suburb construction, the river was diverted so that the part of the flow was returned to its original course. This ran down to the Saintbridge balancing pond and on through Tredworth and past Gloucester Park by Trier Way.

Thus a contamination event at the Upper Barnwood Mill leat site would distribute the contamination down both arms of the Twyver River; to Gloucester City Centre and through the Saintbridge balancing pond past Tredworth to south Gloucester City areas. This contamination could be simply fuel soaked clay or potentially, liquid fuel.

3.10 Previous Applications for a Petrol Filling Station Note that Morrisons took over the previous Safeway supermarket and demolished it to build the present structure. In their submissions to the planning committee were proposals to construct a Petrol Filling Station with car wash on the site. The first, dated 24th May 1999 (Reference: 99/00313/FUL) was a proposal for “Redevelopment of new foodstore & 4xA1 (retail) units 2xA2 (financial professional) units & associated carparking, landscaping, off site petrol filling station & highway works”. The second dated 20th August 2002 (Reference: 02/00690/FUL) was a proposal for “Redevelopment of New Foodstore (A1) and 6 A1 (Retail) or A2 (Financial and Professional Services) Units associated Parking, Landscaping, Erection of Petrol Filling Station, Car Wash and associated Highway Works.”

Neither of these submissions was enacted. Having failed twice, why should the proposal to construct a PFS be allowed to succeed the third time under a much more sensitive situation, location, and circumstance? There is a precedent here, a Petrol Filling Station has not been wanted by the local community and the council in the past; it is still not wanted nor needed.

The matter of uneconomic Petrol/Fuel Filling Stations has been raised by nearby resident Mrs. M. McKecknie’s submission. This points out that two PFS previously nearby have closed in recent times. One of these was on Hucclecote Road some 2 km north northeast and the other on Painswich Road one km to the west. Why do Morrisons think they can run an economic PFS unit here when two others in the vicinity have failed recently? 4 Summary and Discussion There are numerous reasons why a PFS is not advisable at this locality. If a PFS were to be built here it would be unique in that it would be the only one built one the banks of a river that flows both UNDER and around the City of Gloucester. It would be only metres away from the old mill leat that discharges into the Twyver River. The nearest PFS at present to the drainage is the Esso one at 2 Eastern Avenue (GL4 6QS) which is some 100 metres at 25°T from Sud Brook. The next nearest is the Shell PFS at 191 Painswick Road, Matson which is about 185 metres at 215°T from Sud Brook. The new Morrisons at the Railway triangle is approximately 445 metres northeast from the Twyver River (between Barton Street and Metz Way).

The Highway Authority of the Gloucestershire County Council recommended that this application be refused on highway grounds. There is simply insufficient room to move tankers carrying 41,000 litres 40 of fuel (9,000 gallons) safely in to the site. A misjudged move could easily result in a tanker overturning and discharging its load into the Twyver River.

Congestion caused by an increase in traffic is a major concern. An estimate by a Morrisons’ contractor concludes that that traffic would be reduced by replacing the pub with a PFS. This is patently nonsense. Most people walk to a pub, everyone drives to a PFS. Other aspects of their traffic study are in error statistically. Other more comprehensive surveys predict some 13,000 more vehicles using the Abbeydale roundabout in a six day period.

Three schools in the area at Herron Way, Abbeymead Avenue and Coopers Edge suffer from congestion during the ‘school run’ already. The problem will be amplified should a PFS be built on the Abbeydale roundabout. There are already accident hot spots outside the two closest schools; children’s safety should be a priority.

There have been submissions to the council expressing concern about the lack of parking. As it is there is insufficient room for staff to park at the Animal Hospital, Medical Centre and associated Pharmacy. This has resulted in cars parking along Glevum Way with consequent road restriction. These businesses are concerned abut being able to get emergency vehicles close to their front doors. Since the Ridge and Furrow closed in December the car park has been often close to full pointing up the developing parking problem.

Local residents have expressed concerns about noise and light pollution, pointing out that it is only just acceptable at present levels but that it would be much worse, especially for residents on Abbeymead Avenue, should a PFS be constructed. Morrisons would also wish to install a car wash. The Medical Centre has expressed concern about this as it would be adjacent their consulting rooms and noisy. It is understood that a previous application for a car wash as part of the Safeway rebuild was strongly objected to by the residents of Shergar Close.

Concerns have been expressed for the wildlife inhabiting the green strip along the Twyver River. Fuel spills in the past have resulted in a considerable number of fish deaths at the Saintbridge balancing pond. Water birds nest there.

Although flooding may not reach the Ridge and Furrow site on the terrace above the river, it can and does extensively flood the in area where the Twyver River and old mill leat occupy the river bed confined by terrace edges. The Abbeydale Community Centre has been flooded several times. Any fuel spill or contaminated clay would be distributed down the two branches of the river Twyver and taken both under Gloucester city and through southern suburbs. This is unacceptable.

The Severn Vale and Gloucester including Abbeydale are underlain by a thick (approximately 200 metres) clay unit, the Lower Lias Clays. It is also called the Charmouth Mudstone. This comprises clay minerals of the smectite group probably montmorillonite. The clay mineral smectite in particular is the reason for the distinctive swell - shrink behaviour noted in the Lias Group mudstones. The base of the Lower Lias Clays is seen at Westbury on the Severn River. The top is found at Nut Hill which is capped by the next highest unit in the stratigraphic sequence, the harder Dyrham Silt. At Nut Hill a fault is mapped on the southerly side of this by the British Geological Survey. This fault runs east southeast towards the limestone cap of the Cotswold escarpment. Its extrapolation west northwest runs down the Twyver River at Abbeydale passing very close to the Ridge and Furrow site.

41 Speculations in submissions to this hearing have been concerned with the whereabouts of the water table at this locality. They have not taken in to account that the Lower Lias Clays are impervious to water and act as a giant aquaclude preventing water from passing through it; either up or down. Any water above the clay unit is on a perched water table. The Twyver River bed is 3.09 metres below, the base of the light pole at the centre of the Ridge and Furrow car park. The old mill leat culvert at the Animal Hospital is 2.2 metres below the same point. This is the water table (perched) at these points. This would be complicated should the Nut Hill Fault be sufficiently permeable to be water filled. Water could be circulating along this fault, probably in a westerly direction. Any water held within the one to two metres of outwash gravels (or ‘Head’) at the Ridge and Furrow site would be on a perched water table above the impermeable Lower Lias Clays. However mostly they would drain east to the mill leat and river. Should excavations be made such as for installing fuel tanks, they would cut into the lower Lois Clays and be subject to water percolating in. This then would be the water table (perched) at that point. The fuel tanks would then be below the water table.

There are key geohazards involved in the engineering geology of clays and mudstones of the Lower Lias Clay unit. Lias Group rocks are markedly landslide-prone and are on record as having the highest incidence in the UK. Although the slope is not high enough to result in a dramatic landslip, the swell – shrink behaviour of these clays on exposure to water to swell and long summers to dry would result in movement down hill. That is, down the two metre slope of the old Twyver River terrace edge. In wet winter conditions, this movement could result in downhill creep of hydrocarbon (fuel and oil) contaminated clays into the old mill leat of the previous Upper Barnwood Mill. During flooding, these would be washed into the Twyver River and its diversion.

The British Geological Survey (BGS) web site gives information on the Shrink – Swell phenomenon as follows - “Shrinking and swelling of the ground is one of the most damaging geohazards in Britain today, costing the economy an estimated £3 billion over the past decade.” The Lower Lias Clays are regarded as particularly prone to this behaviour. It has been shown that loss of 25 to 30% water can occur and result in a volume change of up to 30%. This may result in structural damage to buildings and disruption to services such as gas and water mains. That swell - shrink is occurring in the Abbey Ward area is shown by extensive cracking of bitumen roads and paths and in cracks in brick walls and houses.

Oxidation of pyrite in any environment leads to the formation of sulphuric acid, which considerably reduces the pH of groundwater. Where such acidic groundwaters make contact with concrete foundations, the main cementitious binder may be converted to thaumasite resulting in deterioration and failure. Sulphates and sulphides are very common in Lias Group mudstones and clays. The damaging effects of sulphate salts on concrete, particularly below the water table, are well documented. The result is a transformation of the concrete fabric into a weak paste, which has serious consequences for the integrity of the concrete, and may result ultimately in failure. The overall total sulphate content median value for the Lias Group formations (British Geological Survey data) is 0.16 %, (=1.6 g/l = 1600 mg/l). The Charmouth Mudstone Formation demonstrated the highest overall aqueous extract sulphate values and hence the greatest sulphate geohazard potential. During the recent geotechnical/groundwater study of the Ridge and Furrow site, chemical assays for sulphate were reported. One sample returned a result of 1600mg/l SO4 value. This sample is dismissed as being a spurious high by the report’s authors. In fact it is the norm for Lower Lias Group clays.

Thaumasite formed by sulphate attack on concrete and has been found on twenty to thirty year old concrete structures on the M5 and other major trunk roads in Gloucestershire in the Charmouth Mudstone Formation. Of the concrete structures investigated, 75% had been damaged, with abutments 42 and columns being the most severely affected members. The Citizen Newspaper (14th January 2014), reports that repairs to foundations on four bridges in the immediate vicinity of Gloucester are to begin next month.

The risk of contamination is higher than has been recognised in previous submissions. The old mill leat is some 13 m east northeast of the Ridge and Furrow pub building’s east corner. It is at the bottom of a two metre slope down from, (east of), the terrace on which the pub is situated. A PFS, if built here, would be the only one on the banks of a water course that flows near Gloucester city, let alone under and through it! The plans for the PFS require burying large tanks to store some 250,000 litres (55,000 gallons) of fuel. This volume of fluid would fill a swimming pool 25 x 10 x 1 metre. A normal road tanker carries some 41,000 litres. The construction process would require excavations that go through the one metre thick gravels at surface and into the Lower Lias Clays. Water would eventually percolate into these excavations, pick up sulphate from the clays and immerse the concrete foundations in sulphate rich water. The foundations would be weakened by thaumasite attack. As described above, the clays have the characteristic of adsorbing water and swelling, then shrinking again on drying out. This alternate swelling and shrinking action would occur during wet winters and dry summers and could easily fracture the thaumasite weakened concrete foundations. It would also fracture the fuel lines. This would result in fuel leakage into the surrounding clay formations. Some of the fuel would be adsorbed by the clay but continued swell and shrink on the edge of the terrace would result in downhill creep of the weakened clay. Eventually the contaminated clay would reach the old Upper Barnwood Mill leat a few metres down slope to the east. A flood such as that experienced in July 2007 would spread this contaminated clay down the mill leat to the Twyver River some 280 metres downstream at OSGB Grid Ref SO 85982E 16119N. The possible scenario would be a series of wet winters and dry summers over a period of time followed by a very large flood as recorded in recent years.

Note that Morrisons took over the previous Safeway supermarket and demolished it to build the present structure. In their submissions to the planning committee were two separate proposals to construct a Petrol Filling Station with car wash on the site. These were dated 24th May 1999 and 20th August 2002. Neither of these submissions was enacted. Having failed twice, why should the proposal to construct a PFS be allowed to succeed the third time under a much more sensitive situation, location, and circumstance? There is a precedent here, a Petrol Filling Station has not been wanted by the local community and the council in the past; it is still not wanted nor needed now.

43 5 CONCLUSIONS 5.1 Traffic Congestion Concerns • Surveys purporting to show that traffic would decrease were the pub to be replaced by a Petrol Filling Station are inherently flawed and incorrect. More relevant and pointed local surveys indicate an increase in vehicles using the Abbeydale roundabout to some 13,000 in a six day period. • The Highway Authority’s assertion that there is insufficient room to safely manoeuvre in the confined space the design has allowed for is apparent from diagrams and maps submitted. A fuel tanker out of control could roll down the two metre terrace edge and discharge fuel into the Twyver River drainage.

5.2 The Effect on Schools and Child Safety. • The three schools in the area suffer from problems during the ‘school run’ and these will worsen should a PFS be built on the Abbeydale roundabout. There are accident hot spots in the vicinity of the two closest schools; children’s safety should be a priority.

5.3 Parking Concerns. • There is concern amongst the local businesses and individuals about the lack of parking. There are insufficient spaces causing cars to park along Glevum Way with road constriction. Emergency vehicles are very likely to be prevented from easily accessing the Medical Centre and Animal Hospital.

5.4 Noise and Light Pollution • There is a reluctant acceptance of present levels of noise and light levels from Morrisons supermarket. However there are worries by those living nearby and likely to be affected that any increase would be a source of unhappiness and dissatisfaction.

• One prime concern for noise is the possible car wash but fact the whole Petrol/fuel Filling Station is unnecessary. There are at least six other PFS’s nearby and another has been recently constructed at Morrisons’ new location on the Railway Triangle.

5.5 Wildlife Concerns • The area immediately to the east of the Ridge & Furrow pub is the Twyver River course with aquatic habitats and trees. It is a natural corridor for wildlife.

• Fuel spills into the River Twyver in the past have resulted in a considerable number of fish deaths at the Saintbridge balancing pond. Swans are present at this pond and have nested here.

5.6 Risk of flooding • The river floods such that the Community Centre has had water through it several times.

5.7 Local Geology and Geohazards The Abbeydale area is underlain by Lower Lias Clays with a thin veneer (~1 metre) of gravels. The clays have special properties that cause geohazards strongly influencing engineering geology.

• These clays have the characteristic of adsorbing water and swelling when wetted, and giving off the water and shrinking on drying out. They are prone to land slip and soil creep even on slight slopes. 44 • Shrinkage cracks are common in lawns and, gardens as well as bitumen footpaths and roads. This swell – shrink phenomenon causes cracks to appear in brick houses and walls in the Abbey Ward area. • Structural damage results from seasonal and long-term volume changes. Wet winters and dry summers will result in major shrinkage of a clay soil. This may result in structural damage for buildings, and disruption to services such as gas and water mains.

• The Abbeydale area is one where sulphate hazards occur; sulphates and sulphides are very common in Lias Group mudstones and clays and the damaging effects of sulphate salts on concrete, particularly below the water table, are well documented. A reaction known as Thaumasite Sulphate Attack (TSA) is characterised by softening and expansion of the concrete which has serious consequences for the integrity of the concrete, and may result ultimately in failure. Lithos Consulting Limited report chemical assays for sulphate including one high sample that was dismissed as being a spurious high. In fact it is the norm for Lower Lias Group clays. Thaumasite sulphate attack has been found on concrete structures on the M5 and other major trunk roads in Gloucestershire. Of the concrete structures investigated, 75% had been damaged. Repairs to M5 and other bridges are being undertaken at present on the Painswick road, the A4173 Stroud Road over the Motorway at Brookthorpe; Junction 10 on the A4019 at Uckington and the B4634 Old Gloucester Road over the M5 between Hayden and Staverton, north of Junction 11.

5.8 Risk of Contamination. • The 200m thick Lower Lias Clays are impermeable and act as a giant aquaclude such that the Twyver River and old mill leat are on a perched water table. Any excavation to place buried fuel tanks will be into the Lower Lias Clays and allow access to water. The tanks will then be below the water table (perched). The high sulphate water will result in thaumasite concrete attack weakening the tank foundations. The water will cause swell – shrink behaviour further damaging the tank foundations and fracturing fuel lines. The tanks are within a few metres of the two metre high terrace edge slope down to the old mill leat. Downhill creep could carry the contaminated clay to the mill leat to be distributed down the Twyver River system. The Nut Hill fault would seem to pass very close to this locality and may be circulating water within it.

5.9 Previous Applications for a Petrol Filling Station. • There have been two previous applications to construct Petrol Filling Stations at this locality previously, neither of which were enacted. With such precedents set, why should the current application be granted in the light of much more opposition and much more risk?

45 6 RECOMMENDATIONS Do not allow a Petrol Filling Station to be built at this locality. There is much opposition to it and it there are several safety concerns including to school children. There is a real risk of contamination of the adjacent river system which flows to and under Gloucester city. 7 REFERENCES British Geological Survey Engineering Maps of the United Kingdom (Bedrock, Superficial and Extended Key, 2011); compiled by Dearman W. R., Dobbs M. R., Culshore M. G., Northmore K. J., Entwisle D. C., Reeves H. J. Building Research Establishment. 2005. Concrete in Aggressive Ground: BRE Special Digest 1, third edition. BRE, Watford. Citizen Newspaper; various articles 2013. Deer, W. A., Howie, R. A. and Zussman, I., (1997) “An Introduction to the Rocl-Forming Minerals”. Dreghorn, W., (1967) “Geology Explained in the Severn Vale and Cotswolds”. Green, G. W., (1992) “Bristol and Gloucester Region”. Brit. Reg Geol, British Geological Survey. P. R. N Hobbs, D. C. Entwisle, K. J. Northmore, M. G. Sumbler, L. D. Jones, S. Kemp, S. Self, M. Barron, J. L. Meakin Contributor/editor K. J. Northmore,(2012); Engineering Geology of British Rocks and Soils - Lias Group, Land Use, Planning and Development Programme, Internal Report OR/12/032 British Geological Survey, Keyworth, Nottingham. Hollingsbee, I. M. Esq. JP. MA. “Gloucester's Water mills on the River Twyver” Gloucester Heritage Open Days September 2005 Hooton, D. G. (2003), A Review of Different Forms of Sulfate Attack. Univ. Toronto Civil Eng. Dept. Zhou, Judith (2003) “The Role of pH in Thaumasite Concrete Attack” Seminar on ‘The Thaumasite Form of Sulphate Attack of Concrete (Clay Agressivity), Univ Sheffield. Various other submissions to the planning committee on the demolition of the Ridge and Furrow Pub and replacing it with a Petrol/Fuel Filling Station, Car Wash and Kiosk.