FLOODING IN EVERSLEY

Representatives of Eversley Parish Council held a meeting on 28.08.08 with representatives from Hampshire CC, Hart DC and the Environment Agency to discuss all items raised in the Flood Report produced by Eversley Parish CouncilAction is due to be taken by the various agencies in several areas to prevent the problems recurring. 

EVERSLEY PARISH COUNCIL
FLOODING in EVERSLEY

Flooding in Eversley
 Final Report of the Eversley Parish Council Flooding Working Party.
April 2008 

Introduction.
The village of Eversley lies in the Blackwater Valley south of the river. The River Blackwater is not, however, the cause of flooding except in one location. The floods that have been experienced have all resulted from surface water draining from higher land south of the village as it tries to make its way to the river.

Ancient watercourses and drainage ditches have been diverted, changed and in some cases filled in as a result of uncontrolled development of village roads and properties. Existing ditches have not been adequately maintained. Underground pipes have been blocked or partially blocked. Road drainage in many places is inadequate.

The time has come to address these problems which have caused serious flooding on two separate occasions in the last six months and will surely continue if corrective action is not taken.

History of Investigative Activity.
Flooding in various locations in Eversley has been the subject of investigative activity for many years.

In February 2001 the Parish Council distributed a questionnaire to a total of 43 properties that were known to have experienced flooding problems. Responses were summarised in a “Management of Flooding Questionnaire”. This was returned to the Hart Association of Parish & Town Councils (HAPTC) in readiness for an open meeting organised by the Hampshire County Council Planning & Transportation Committee on the 27th February 2001. There is nothing on record that indicates that any benefits or actions were derived from the questionnaire or from this meeting.

The specific problem of flooding in Warbrook Lane was, however, pursued by Cllr Webb who in March 2001 wrote a very detailed letter on the state of ditches and culverts to the Environmental Agency (EA), Hart District Council (HDC), the Highways Department of HCC and Style Conferences (the then owners of Warbrook House). This led to further correspondence and meetings but there was no constructive follow up by any of the authorities.

There is, in fact, no record of any further investigative activity until 2004 when the EA commissioned a study by Babtie Brown & Root specifically directed at the Warbrook Lane problem. Unfortunately it reached the conclusion that the predominant cause of flooding was the obstruction of field drainage. Since this was said to fall outside of the responsibility of the EA the study recommended that nothing more should be done. This conclusion was incorrect and should have been challenged.

It was not until 2006 that the subject of flooding in Warbrook Lane re-surfaced and the EA commissioned Halcrow Group Ltd to look at it again. Their very detailed study estimates the “maximum conveyance” in all of the drainage channels relating to the lane and its environs. It provides invaluable information on not only Warbrook Lane but also on the land known as The Great A, and drainage from this land. This excellent study should also have provided a basis for decisions and actions. However, there is again no record of follow up.

Neither of these two studies looked for the root causes and origins of floods and did not therefore propose solutions. Because they concluded that flooding was being caused by watercourses that were outside of the jurisdiction of the EA nothing further appears to have been done and the risk of repeat floods in the village remained. This should have been unacceptable. 

In January 2007 EPC was advised that Hart DC was intending to carry out a “Strategic Flood Risk Assessment” and that the EA intended to do additional survey work on the River Blackwater. We have heard nothing further. 

Definitions and Responsibilities.
The Parish Council records show a need to distinguish between the different categories of watercourses. They show that the three authorities, the EA, HDC and HCC, at one time, had three main designations:

  • Main River  -  which can be no more than a roadside stream e.g. Firgrove Stream.
  • Critical Ordinary Watercourse  -  which is a stream or ditch that has the potential of putting large numbers of properties at risk from flooding.
  • Non Critical Watercourse  -  a stream or ditch that does not have this potential.

These designations and definitions were given in a letter to the Parish Council from Hart Engineering Department dated 29/07/05.  Since drafting this report we have, however, been advised by the EA that these designations are no longer recognised. We are told that there are only two categories of watercourse – “main river”, and “ordinary watercourse.” Ordinary watercourses therefore include anything from a continuously running stream to a normally dry ditch.   We are also told that the EA  “has a duty to supervise all matters relating to main rivers,” and “we have powers to complete maintenance work, we do not have a duty to do so, i.e. maintenance is not the responsibility of the EA.”  This refers to main rivers only.

Taken literally this means that there is no local authority that accepts responsibility for work on any waterway to ensure that it does not pose a flood risk. We can assume, however, that this excludes the Highways Department when the cause is attributable to a road culvert or failure of road drainage.

This definition of responsibilities also means that there is no one authority that residents or parish councils can turn to.  The consequence, as we have experienced, is that if issues are raised they pass from one to the other of the three authorities and ultimately disappear. We accept that the prime responsibility for maintenance rests with the owners of land through which watercourses pass i.e. the riparian owners, but in a rural community where watercourses develop from large catchment areas and pass through land belonging to a multitude of owners total abdication of responsibility by authorities is not logical.

To summarise, acceptance of these designations and definitions means that parish councils and landowners are on their own when it comes to the flood potential of every watercourse. They can only expect help, limited to advice and supervision, when the stream is designated as a main river.  They can expect no help with other watercourses even if they are clearly critical as previously defined.  This cannot be correct.

In Eversley, Firgrove Stream is the only “main river” that traverses the village. We have other streams which, as we shall see, have proven to be critical.

Situation.
The properties that are at risk in Eversley lie within the contours that are between 50m and 56m above sea level. The land immediately south of the village ranges from 64m to 67m whilst that to the south west on the western side of the A327 peaks at around 89m. The height of the Blackwater River at the New Mill sluice gates as it exits the western boundary of the parish is normally 46m to 47m. Under severe flood conditions with the sluice gates fully open it has peaked at 47.4m.

This means that the fall for drainage of surface water from village properties is generally adequate. However, the fall is small once water enters the residential area which makes drainage a problem. Excepting Firgrove Stream, drainage has to rely on manmade ditches, underground pipes, road drains and their culverts.

In some places surface water from a large catchment area is expected to disappear into a road drainage system that was installed decades ago before roads were widened or raised and before housing development removed the absorptive capacity of the land. It is hardly surprising that drainage systems cannot cope.

Uncontrolled housing development has also seen ditches being filled in or built over. As a result some are no longer continuous whilst many of those that remain are poorly maintained.

As stated earlier the river is not the cause of flooding except in one location. The causes are inadequate road drains, and badly maintained ditches and culverts.

Flood Locations.
These are indicated on the attached map (Figure 1). They can be designated as follows:

  • Eversley Cross.  -  from Marsh Lane along and adjacent to the B3272 as far as Chapel Meade.
  • Longwater Road - adjacent to the eastern side between the village pond (B3016) and the Blackwater River.
  • Eversley Centre.  -  including Chequers Lane and Hollybush Lane.
  • Eversley Street  -  both sides of the A327 throughout the Street.
  • Warbrook Lane.  -  including the eastern end and as far as Webb’s Corner.
  • Lower Common - in particular the properties north of the lane that are accessed by unadopted tracks.
  • The Ford  -   including the western end of New Mill Lane.   

There have been other “wet spots” but these have been caused by temporary blockages of ditches or culverts that were subsequently cleared.

ANALYSIS.
1.      Eversley Cross.   

Firgrove Stream runs along the eastern side of Marsh Lane, see Figure 2. It accepts water from a large catchment area including Blackbushe Airport. Within the parish it is fed by an overflow from the lake in the grounds of Kits Croft. This in turn supplies the lake in Firgrove Manor which then overflows to create the continuously flowing stream along Marsh Lane. 

Firgrove Stream was classified by the EA as a “main river” some two or three years ago. This means that they have a clear responsibility to ensure that it flows freely.

The stream disappears into a complex array of old culverts under the B3272 before emerging to flow along Fox Lane. It then turns north and west adjacent to Footpath 23 before flanking the new Eversley Sports Association playing field on its way to the river. The culvert system and flow paths are shown in Figure 2.

It will be seen that the stream is divided as it flows down Marsh Lane. Two culverts, each accessed by manholes in the road, lead to two pipes that cross the field west of the lane and south of Footpath 22. One of these feeds a short open ditch between The Cross and Eversley Manor. This ditch is then culverted under the B3272, and the area of the Cross Green children’s playground, to provide the feed to the Village Pond. The other pipe feeds Parfitt’s Pond.

There is also a short section of open ditch on the western side of the end of Marsh Lane which receives some water from Firgrove Stream. This has, at its end, a small bore high level culvert under the B3272 that continues under the land of Vann Place and Eversley Barn Cottages to create the stream adjacent to the gravel track to the cricket pavilion. This stream appears to take very little flow even under high rainfall conditions. This may be due to blockage of the culvert or the downstream pipe.                                                                                                                                         

The main flow in Firgrove Stream down Marsh Lane should pass through two 450 mm culverts under the B3272 and a smaller culvert west of them. Flow in the two main culverts emerges into a short length of open ditch on the northern side of the B3272 before passing into a further long culvert under Fox Lane. From there it should have a clear path to the river under a new bridge that carries Footpath 23. The downstream path from this point is in the process of being cleared by Hadley’s under contract to CEMEX.

Flow through the smaller culvert under the B3272 emerges into a ditch on the northern side of Fox Lane before re-combining with the main flow near to the entrance to the “pony field”.

If the Firgrove Stream backs up through blockage at the end of Marsh Lane or if there is rainfall in excess of the culvert system at that point then it can flow onto and over the B3272. The section of this road opposite to the Chequers public house is low and this means that the road and adjacent properties can become flooded as far as Chapel Meade. This can be aggravated by water flowing down Chequers Lane (see later) and by overflow from the ditch that feeds the village pond.

If, as has happened, Firgrove Stream is restricted further downstream, water overflows behind the cricket pavilion along a short length of ditch and into the pond in the grounds of Eversley Cross House. Under excessive rainfall conditions this ditch overflows to join the water that has crossed the B3272. The pavilion end of Cross Green is then flooded (see photograph).  The other consequence is that overflow from the Eversley Cross House Pond becomes excessive and joins the overflow from the village pond to affect Longwater Road (see later).

Flooding in Eversley

Flow down Chequers Lane also contributes to the problems at Eversley Cross. This should be contained in ditches on both sides of the lane but these have been blocked. Flood water has therefore remained on the surface and flows onto the B3272 where it joins that from Firgrove Stream. Since the problems at Chequers Lane are similar to those in Hollybush Lane they will both be considered as Eversley Centre, see Section 3 of this analysis.          

Solutions to the Eversley Cross Problem.
There is clearly a solution to the contribution that Firgrove Stream makes to flooding in the area of Eversley Cross. This is to ensure that it has adequate capacity and is free flowing all of the way down to the river. The clearance that CEMEX have in hand may be sufficient to ensure this. Heavy rainfall conditions need to be experienced to know whether this is so. If not, it may be necessary to install a new culvert or to enlarge the existing culvert under the B3272 at its junction with Marsh Lane. 

Another possibility that could avoid the high cost of modifying the culvert system could be to construct a flood relief ditch to take excessive flow directly to the river from the point where the new bridge carrying Footpath 23 has been constructed. CEMEX plan to create a ditch as one of the security measures on the eastern boundary of the ESA playing field. This could be used for this purpose.

All of this means that Firgrove Stream could be taken out of the equation. The Eversley Cross area could still, however, suffer flooding problems from; the pipe and ditch feeding the Village Pond, the pipe feeding Parfitt’s Pond, the stream adjacent to the cricket pavilion driveway and flow down Chequers Lane.   The pipes could be restricted when it is certain that Firgrove Stream can cope.   Flow in the pavilion stream is controllable. This would leave Chequers Lane (see later).

2.      Longwater Road (B3016)
The village pond overflows into a stream that meets the overflow stream from the lake in the grounds of Eversley Cross House, see Figure 3. The combined flow follows the boundary of Dial House land. This is not a ditch, it has a continuous flow of water and at one time would have been classified as a critical ordinary watercourse since it has been responsible for the flooding of a number of properties.

At times of heavy rain the stream leaving the village pond also receives water overflowing Firgrove Stream both across the B3272 and from the north east corner of Cross Green where the pavilion is flooded. The combined flows pass out of Dial House land through a small bore pipe into the drainage system in Longwater Road. To protect the house the owner has made two holes in the brickwork above this pipe so that excess water can discharge directly onto the road (see photograph).  

Longwater Road 

Under these conditions the drainage system which is already full cannot cope. It is receiving surface water from a large catchment area that now includes Chequers Lane, the land that creates flow into the village pond and the land that feeds Firgrove Stream. The result of this excessive flow into the Longwater Road drainage system is that manhole covers lift and water flows on the road surface and into Cobwebs, the last property on the eastern side of the road, before reaching the Blackwater River.

The level of the stream flowing through Dial House land is also such that the village pond overflow spills onto the track outside of Dial House before discharging directly onto Longwater Road (see photograph).

Stream flowing through Dial House land

The problem is clearly complex and has nothing to do with ditches belonging to riparian owners being blocked or filled in (except those in Chequers Lane). Firgrove Stream, the responsibility of the Environmental Agency, has been a major contributor.

Solutions to the Longwater Road Problem.
Prior to gravel extraction Firgrove Stream used to go directly to the river north of Fox Lane. This route would not have resulted in water overflowing onto Longwater Road.

Attention to the Eversley Cross problem, as proposed earlier, should ensure that Firgrove Stream does not contribute to flooding in Longwater Road. However, there is another, currently minor, aspect to the complexity of flood water flow in this region. The stream that runs behind the cricket pavilion to feed the pond in the grounds of Eversley Cross House has an overflow pipe in the north east corner of Cross Green that takes excess back to Firgrove Stream. This overflow needs to be cleaned out and to be at an appropriate height to ensure that flood water does not reach the Eversley Cross House pond and thence Dial House and the Longwater Road area. At the moment the flow in this stream is small but this may be due to blockage of the B3272 culvert or its downstream pipe under the land of Vann Place and Eversley Barn Cottages. Should blockages be cleared and flow in this stream be increased it could be important to ensure diversion of any excess via the overflow pipe.

The main flow would still be to the pond in Eversley Cross House grounds which would still overflow to join the overflow from the village pond but without the excessive flow that puts Dial House at risk. To minimise this risk, however, the bore of the pipe exiting Dial House grounds must be increased.

Another possibility is to divert the stream from the north east corner of Dial House land by piping it under Eversley Cross House land to meet an old ditch that would, if cleared, take it to the lower reaches of Firgrove Stream. This would be an extreme measure and would be difficult to arrange.

Given the changes to Firgrove Stream that are advocated as solutions to the Eversley Cross flooding problem the Longwater Road drainage system could be found to cope with higher flow from the Village Pond and the surface water from Chequers Lane. If this is not the case and the other measures that have been suggested are impractical or ineffective the road drainage system will need to be improved.

3.         Eversley Centre.
Water that drains from the higher land and fields south of the Centre should flow down a series of open ditches, underground pipes and culverts under driveways. These lead to further culverts under the B3272 and thence across the fields north of the B3272 to the river.

The lane culverts range from 150mm at Happy Farm, opposite to Yeomans, to 300mm along the southern edge of Hollybush Lane as far as Parfitt’s Barn. 150mm appears to be inadequate considering that the large catchment area of the higher land to the south is capable of providing a lot of surface water under adverse conditions.                                                                                                                                                                                                                                                           

In the case of Chequers Lane, heavy rainfall causes manhole covers to lift and water then flows on the road surfaces all the way down to the B3272. The Chequers public house and Church Place are then flooded.

In the case of Hollybush Lane, heavy rainfall also causes water to flow on the road surface down to the B3272 where it meets a road drain. This can normally cope but in extreme conditions the water from the lane meets an already flooded road. Surface water on Hollybush Lane is caused by the blockage of ditches and culverts under driveways on the eastern side of the lane and, in particular those north of the entrance to Sherlock Lea serving Nos 1 to 4.

Solutions to the Eversley Centre Problem

Detailed inspection has shown that new sections of underground pipe, clearance of culverts under driveways, and a scheduled ditch and drain maintenance programme will be the only way to prevent water cascading down road surfaces. EPC has, therefore, commenced a programme of rectification in cooperation with the Highways Department of HCC and with individual land and property owners. If new pipes or culverts are agreed it is suggested that they should be a minimum of 300mm.

In the Chequers Lane case it may also be possible to create a new ditch alongside Footpath 22 to take excess flow into the village pond and/or Parfitt’s Pond.

As already noted, flow down Chequers Lane has contributed to both the Eversley Cross and Longwater Road problems. Though attention to inadequate or poorly maintained ditches is essential, it is obvious that flow that is currently on the surface would still create problems downstream if contained in the existing drainage system or if, as suggested above, it were diverted directly to the two ponds.   Better knowledge of the culvert system under the B3272 and the ditch system north of this road is needed before we can comment on the flooding problems at the Hollybush/Centre Stores end of the area.

4.         Warbrook Lane / Webb’s Corner.
Water drains from the higher land south of the Bramshill Road through two streams both of which run for many days after rainfall has ceased. Again, both of them, at one time, should have been classified as critical ordinary watercourses. The streams as they flow to and through land known as The Great A are shown in Figure 4.

Stream A adjacent to Footpath 7 flows through a culvert, close to the property, Longreach, into the land on the north side of the road. From there it follows Footpath 9 to eventually form the western boundary of The Great A. It continues adjacent to the A327 before entering a ditch on the southern side of the eastern end of Warbrook Lane. 

The fields south of the Great A have ditches at their boundaries that ultimately feed another ditch that marks the southern boundary of the Great A. This can run west to join Stream A or can traverse the Great A to join another stream which we will label Stream B.

Stream B has its origins in Warren Heath and flows via Church Pond west of the church across the fields to arrive on the southern side of Bramshill Road close to its junction with the A327. It appears that there are then two culverts leading the stream into a boggy triangle of land north and west of this junction.

This stream then uses a ditch on the western side of and adjacent to the A327 before passing through a large brick culvert at the gated entrance to the Great A. It then continues to follow the main road until it meets a culvert that takes it under the road to the east into land known as “the Duck Farm”. The ditch then passes under a farm bridge after which it widens and could be free flowing as far as the Blackwater River.

It is clear that Stream B is expected to take water from a large catchment area including the high ground west of Brickhouse Hill such that the culvert under the A327 and the subsequent ditch has not coped under heavy rainfall conditions.

What has then happened is that water has overflowed within the Great A to join Stream A. The ditch on the southern side of the eastern end of Warbrook Lane is then receiving the full flow of Stream A and the overflow from Stream B. Flooding is inevitable.  Water in this Warbrook Lane ditch has two opportunities to find culverts under the lane which should ultimately take it through fields behind the Warbrook Lane properties to a ditch alongside Footpath 4 and thence to the river.

The excellent analysis and maps of the Halcrow report provide very useful information on these culverts. The first (from east to west) should carry water through to a ditch on the north side of the lane to meet flow from the second. The Halcrow figures for their maximum conveyance are, (1) 0.2 m3/sec and (2) 0.11 m3/sec. The combined flow then passes through a 600mm pipe under the land of No1 Rose Cottages. A current extension to thIs property has diverted the straight pipe introducing two dog legs to avoid the footings. This could aggravate the problem though it has been done with the approval of the EA.

On inspection under rainfall conditions the first culvert is taking all of the flow. The second culvert is totally blocked and takes none.

The third culvert further down Warbrook Lane normally serves to clear water from the stream that emerges from Warbrook House land and from ditches adjacent to St Neot’s Road one of which continues along the south side of Warbrook Lane. On passing through the culvert the water meets water flowing in a ditch on the north side of Warbrook Lane from Webb’s Corner. Observation under rainfall conditions showed that the strength of the stream prevents free flow from this ditch and the water is held back on the road surface. The owner of Four Seasons has cleared the ditch in front of his property and also the downstream ditch that takes the combined flow across the fields to the river but this has not prevented road surface water. We understand that the depth of the ditch was deliberately decreased by tipping rubble into it at the time the adjacent property, Rommat, was built. Obstruction further downstream may also need to be looked at. The culvert with a Halcrow estimated capacity of 0.3 m3/sec appears to be adequate.

The fourth culvert is a serious problem. It is located immediately west of Webb’s Corner where Warbrook Lane changes into Lower Common. It is reported as being only 300mm in diameter and the Halcrow report states that it is both collapsed and blocked. Many years ago it discharged into a broad ditch that traversed land now occupied by Harry’s Cottage and Stepping Stones Cottage before crossing fields and discharging into the Blackwater River.  Developers have, however, put a small bore pipe into this ditch and back filled it. It is believed that this pipe is a plastic land drain though the Halcrow Report assumed (?) that it was 300 mm. On this basis they estimated the capacity of this 30m or so length of pipe to be only 0.09 m3/sec even if water could reach it from the culvert. Blockage of the culvert means, however, that water cannot reach this small pipe and there is regular flooding at Webb’s Corner even with light rain.  The excess water flows back along the north side of Warbrook Lane where, as already seen, it meets the stream exiting the third culvert and builds back.  Given heavy rainfall this excess water remains on the road surface and joins that at Rose Cottages. The entire length of Warbrook Lane is then underwater.

The culvert system and the ditches and streams that they serve are shown in Figure 5.

There is no doubt that the condition of the fourth culvert and loss of its downstream ditch is the cause of flooding at Webb’s Corner and is one of the principal causes of flooding in Warbrook Lane.

Solutions to the Warbrook Lane Problem.
The state of the culvert and the inadequacy of the land drain at Webb’s Corner clearly have to be addressed. There is no other solution. EPC were advised in September 2006 that the EA was in the process of serving notices on the properties involved but nothing further has been heard.  Continued inaction is inexcusable. EPC must not take “no” for an answer and must not let the present state of inactivity continue. If re-creation of the downstream ditch from the fourth culvert is not possible consideration should be given to creation of a new ditch on the eastern boundary of Harry’s Cottage.

At the other end of the lane the potential to flood could be decreased by opening up the second culvert and/or making better use of the first culvert. A new ditch across the field on the eastern border of the allotments could take the flow from both culverts. The ditch would cross HCC land and the pipe under No1 Rose Cottage would be redundant. However, this was suggested by the current owner of No1 Rose Cottage in a letter to HDC dated 05.04.06 and the response was that “initial feedback had indicated that this was not a practicable proposition”. The proposal was passed to the EA for comment and we have no record thereafter. Residents are now taking the matter into their own hands.

The current work on the Great A may hold helpful solutions to the overall flooding problem. A newly dug ditch has, at its end, a low stone wall that would form a dam in rainy conditions. If this ditch were to be connected to Stream A and the dam was at a suitable height it could take excess water from this stream and divert it through the A327 culvert to the river. However, the capacity of the A327 culvert has long been suspect so it cannot be used to take excess water from Stream A unless it is enlarged.

The changes in the Great A have therefore been restricted to creation of a channel across it that takes excess water from Stream B and ensures that the excess does not get into Stream A, see Figure 6.

The A327 Culvert.
In March 2003 this culvert was altered. However, the plan to install a 450mm pipe was abandoned in favour of a 300mm pipe due to “the proximity of utility apparatus” and the consequent increase in both cost and time (see letter from James Holt, HCC Highways, dated 12/03/03)

This letter states that the new pipe was installed alongside the existing pipe such that it will “greatly improve the capacity of flow of water”.  Installation of this smaller pipe was approved by the EA.

That this was a wrong decision has been confirmed by events. It was also made suspect by the Babtie Brown & Root study in 2004 where it was recommended that the Highways Authority should consider “how best to mitigate or remove the offset” in the culvert. There is no record of follow-up. The Halcrow study in 2006 should also have highlighted the problem with this culvert when it gave an estimated capacity of only 0.2m3/sec based on the belief that there was a 450mm pipe alongside the original 225mm pipe. If the capacity had been calculated using the correct 300mm figure it would have been 0.11m3/sec. Such a low flow rate should surely never be contemplated for a stream with the large catchment area of Stream B.

Eversley Parish Council needs to make urgent representations to ensure a significant upgrading of this culvert. In the meantime the downstream ditch needs to be cleared.

As will be seen in the next section of this report, prevention of excess water reaching Stream A from Stream B as well as helping the Warbrook Lane problem, could also help the flooding problem in Eversley Street. Deliberate diversion of water from Stream A to Stream B would clearly be beneficial but would only be possible with an upgraded culvert.

5.         Eversley Street.
Ditches used to exist on both sides of the A327 but lack of control of housing development has seen them disappear.

On the western side a ditch remains adjacent to Dressors which should communicate with pipework on either side and with culverts under access drives.  On the eastern side a ditch commences (or ends) at the bridge but disappears into a culvert under the driveway of Belee and is not seen again.

South of the Street there is no ditch along the eastern border of the A327 though the land under the fringe of trees is low in many places and contains standing water in heavy rain conditions. This could contribute to the problem at Little Chesters (see later).

In general, drainage from the area of The Street must depend on the road drainage system which is clearly inadequate in heavy rain conditions.

Another problem with road drainage is that years of road surface refurbishment have raised the surface level such that gardens of properties and some properties themselves are lower. Excess water then runs off the road into the gardens and properties. At the southern end of the Street, on its eastern side, the last property, Little Chesters, is considerably lower than the road surface and must depend on the road coping with surface water.

Solutions to the Eversley Street Problem.
As indicated earlier storm water exiting the Great A must be a significant contributor to the flooding problem particularly at the southern end of The Street since floods in Warbrook Lane and floods in The Street can merge. We therefore believe that opening up the culvert under the A 327, clearing the subsequent ditch and diverting water away from Stream A should be of significant help to both the Warbrook Lane and Eversley Street problems.

The only alternative would appear to be to create new drainage channels behind properties in The Street.

6.         Lower Common.
Surface water drains from the wooded land south of the Lower Common road through culverts under the road and into three main ditches.

One ditch runs between the twin tracks of Mud Lane before disappearing into a pipe under land belonging to Nod Cottage. The other cottages at the end of the lane are prone to flooding under excessive rainfall conditions due to water overflowing this ditch. The contour of the Lower Common road is such that water at Webb’s Corner does not reach this ditch.

Since Mud Lane is unadopted the only action that can be taken is for the residents to maintain the ditch and, as necessary, to take corrective action on the pipe at Nod Cottage which may either be blocked or too small.  Another ditch runs adjacent to the driveway to Horn’s Farm. This is fed by a stream that runs adjacent to the road that provides a rear entrance to Gaddeshill House. The owner of Fourways has cleaned this stream which now flows freely. The culvert under the Lower Common road is clear and the owner of Horns Farm Cottage has continued the clearance work all the way to the fields north of the farm. The effectiveness or otherwise of all of this work needs to be checked by inspection at time of heavy rain.

The third ditch traverses land east of the one at Fourways. This passes through a culvert under the road opposite to house No 7 before turning east in a short length of open ditch. It then enters a long length of underground pipe (50m or so) running the length of the private drive that serves houses No 1 to 6. At the end the pipe feeds an open ditch at the rear of Horns Farm Cottage land before finding its way across the fields to the north. Inadequacy or blockage of the pipe and/or the ditch resulted in severe flooding of the houses at the end of the drive and the rear of Horns Farm Cottage in July 2007.

Solutions to the Lower Common Problems.
The state of all ditches that drain this area as they cross fields to the north needs to be examined. Underground pipes need to be checked and, where necessary, cleared.

The difficulty in these instances is that the driveways that serve the properties that are set back from the road are all unadopted. The Parish Council should help by offering advice and by seeking professional assistance but the residents that are affected also need to resort to self help.

7.         New Mill Lane and the Ford.
Ditches on both sides of New Mill Lane exist but, in general, have been poorly maintained. EPC needs to alert many of the property and land owners to their responsibility for maintenance.

On the northern side of the lane the culvert under Oaklea Drive appears to be blocked and an open ditch between Sandrina and Oak Cottage has been filled in. The former is a matter for Highways. The latter has been brought to the attention of Hart DC who have included re-creation of the ditch as one of the planning consent conditions on a current house building project.

Continuation of the roadside ditch in front of Oak Cottage is suspect following planting of a new hedge.

At the ford end of New Mill Lane water from the higher land of Bramshill Forest flows down two large ditches on either side of Sandy Lane. On the western side the ditch used to be known as Slade’s Gutter and was a continuously flowing watercourse taking water from a large catchment area within the forest. Gravel working altered the watershed and the ditch now dries up except in rainy periods. In heavy rain it just copes together with the ditch on the eastern side. Culverts are large and clear.

These ditches meet a ditch that runs down the southern side of New Mill Lane and the combined flow passes through the garden of The Old Chapel. There is a small culvert in the New Mill Lane ditch which permits excess water under heavy rain conditions to overflow into a ditch on the north side of the lane opposite to Millstream. From there and from the Old Chapel garden the water flows to the Blackwater River at the ford, downstream of the mill sluice gates.

The problem here is not the surface water drainage it is the river itself. Very heavy rain, with the sluice gates fully open, can cause the river to burst its bank upstream of the gates somewhere behind Rycroft Stables. River water then flows across the fields adjacent to the new route of Footpath No 4, through the field gate into the end of New Mill Lane.  From there it returns to the river downstream of the sluice gates. It should be noted that this return flow is heavily contaminated with horse stable manure from the midden in the flooded field.

When this happens the downstream level of the river is high and water enters and flows through The Old Chapel farmyard picking up more stable manure before returning to the river through the flooded fields of Old Chapel Farm.

Under these conditions the original buildings at the New Mill Restaurant, on the other side of the river are also flooded.

Solutions to the New Mill Lane and Ford Area Problem.
EPC needs to pursue individual land and property owners re clearance of ditches and needs to request Highways to clear the culvert under Oaklea Drive.

At the Ford there does not appear to be a solution to the problem other than building up the banks or dredging the river downstream of the ford. The contamination problem could, however, be minimised by the Environmental Agency identifying and rectifying the apparent low spots in the river bank behind Rycroft.

Conclusions and Recommendations.  
There are a number of steps that can be taken to alleviate the flooding problems in the village. In no particular order of priority they are:

1.      To increase the capacity of Firgrove Stream. This has been done by the downstream clearance work of CEMEX/Hadley and it remains to be seen if this has been effective or whether it is necessary to continue all the way to the river as was originally intended. If this work is not an answer to the problem it may be necessary to install a new larger diameter culvert under the B3272 at the bottom of Marsh Lane.

A flood relief ditch on the eastern boundary of the ESA playing field with a weir to take excess water from Firgrove Stream directly to the river could also be considered.

2.      To increase the capacity of the road drainage system down Longwater Road. NB. This might not be necessary if the improvements to Firgrove Stream or other measures are successful but is very necessary if nothing else is done.

3.      To increase the sizes of the overflow pipe from the village pond and the exit pipe from the overflow stream as it leaves Dial House land to prevent the flooding of Dial House and to prevent the pond spilling over onto the adjacent green and track in front of Dial House. NB. It could be possible to re-route this stream from the north east corner of Dial House land under the adjacent land of Eversley Cross House to a new ditch that could take it back to Firgrove Stream but this would be an extreme measure. 

4.      To ensure that the culvert that feeds the stream that runs alongside the gravel track to the cricket pavilion is cleared and that the overflow pipe at the end of this stream is capable of taking any excess flow back to Firgrove Stream. Some flow remains necessary to feed the pond in Eversley Cross House but diversion of excess could decrease the Longwater Road burden.

5.      To seek the cooperation of householders and landowners to open up and clear ditches especially in Chequers and Hollybush Lanes. At the same time seek the cooperation of Hampshire Highways Department to increase culvert and underground pipe diameters where found to be necessary.

6.      To contact the owners of the Duck Farm and adjacent land to enlarge and clear the ditch that takes water from the Great A. Once we are satisfied that there is no downstream obstruction to re-request Highways to increase the diameter of the culvert under the A327 to ensure more effective use of this ditch. Given that this is done it may be possible to   take measures within the Great A to significantly help both the Warbrook Lane and Eversley Street problems.

 

7.      To re-request the EA to take enforcement action to open up the ditch, create a new ditch or replace the existing pipe with one of much larger diameter at Harry’s Cottage and Stepping Stones Cottage. When this is done to have the culvert at Webb’s Corner either replaced or cleared.

8.      To support the residents in Warbrook Lane in their creation of a new ditch east of Rose Cottages and, as necessary, to request Highways to clear the second culvert. Also to inspect the ditch that takes water from the third culvert to see if it can be dredged or cleared downstream to increase its capacity.

9.      To inspect the drainage ditches that traverse the fields north of Lower Common to see if there are answers to continued flooding problems in a number of Lower Common locations.

10       To request Highways to inspect and, if necessary, unblock the culvert under the entrance to Oaklea Drive. EPC to also that action is taken by individual property owners in New Mill Lane where necessary

11        To inspect the bank of the Blackwater River behind Rycroft Stables and seek the cooperation of the EA to have it built up as necessary. At the same time introduce the possibility of dredging downstream of the ford.

12        To investigate the possibility of creating a new flood relief ditch or ditches behind properties in The Street if we are not successful in opening up the A327 culvert or if this proved to be ineffective.

Clearly we are talking here of a long time frame and an uphill struggle to overcome bureaucracy and seek funding. We need therefore to prioritise. We need also to ensure that some actions are taken before another deluge and a repeat of the floods.

In the meantime a lot can be achieved by developing greater awareness amongst property owners of the need to keep frontage ditches clear. EPC needs to ensure that this responsibility is clearly understood.

Progress.
This report in draft form was submitted to the three authorities; the EA, HDC and the Highways Department of HCC at the beginning of February 2008.  The three parties met to discuss the report on 18/04/08 and we await receipt of notes on that meeting that are being drafted by Brian Roberts of the EA. Following receipt, EPC will press for a meeting at the first opportunity.

There has been progress in specific areas as follows:

1.                  The Firgrove Stream has been cleared by CEMEX/Hadley as far as they can before entering fields owned by Cobwebs. Continuation awaits these fields drying out to permit vehicle access. This may not, however, be found to be necessary if the stream is found to be flowing freely. CEMEX is monitoring presumably in liaison with the EA.

2.                  Chequers Lane ditches and underground pipes have been partially cleared by Highways. Replacement of one section of pipe from Plumb Hollow to Happy Farm is awaited. Ditch clearance from the farm gate down to Parfitt’s Farm House is awaited. Culvert repair work at the gate is necessary.

3.                  Ditches and underground pipes along the section of Hollybush Lane opposite to Parfitt’s Barn have been cleared by Highways and CEMEX. Ditches and culverts under house driveways Nos 1 to 4 have been cleared by EPC and Sentinel Housing. It remains to monitor water flow in heavy rain and to ensure maintenance of ditches from hereon.

4.                  Development of the Great A has proceeded with new channels that ensure that the area is more effectively drained via the culvert under the A327. The ditch downstream of this culvert has been cleared by the land owners. The brick culvert carrying Stream B under the old driveway to Warbrook House has collapsed and is to be replaced by De Vere Venues.

5.                  De Vere Venues have also agreed to clean the ditch that runs along the south side of Warbrook Lane.

6.                  The new ditch east of Rose Cottages has been dug out and is working well in tandem with the re-routed pipe under No 1 Rose Cottage.

7.                  The EA are to take enforcement action on the limitations to flow at Webb’s Corner. Sight of the letter that is to be written to the owners of Harry’s Cottage and Stepping Stones Cottage is awaited. 

8.                  Some frontage ditches have been cleared in Warbrook Lane, Lower Common and New Mill Lane.

In general there is a much greater public awareness of need to maintain ditches at the frontages of properties in the village. There is also a continuing programme of action by the Parish Council. It is intended that actions by the Council and by the local authorities will be subject to regular review at a series of meetings which have yet to be arranged.

Addendum 3.
Notes of Meeting – 18th April 2008 to discuss the Flooding Report produced by Eversley Parish Council.

Attendees:   Brian Roberts (Environment Agency)
                  
David Van Beesten (EA)
                  
Steve Pellatt (Hampshire CC)
                  
Colin Harris (HCC)
                 
Dave Goddard (Hart DC)

1          Eversley Cross Area
The main problem in this area was identified as flooding of the Reading Road after heavy rain fall.  This is a significant problem as this is an important access route.  From previous inspections, it appears the Firgrove stream comes out of bank along Marsh Lane to flood Reading Road. It is currently uncertain whether the culverts under the B3272 have insufficient capacity or if water is backing up from the drainage system in Fox Lane due to a blockage/collapse.

HCC confirmed some funding has been set aside for improvement in this area but need CCTV survey to confirm.  EA confirmed some cctv has been completed.  EA to forward details to HCC.

Firgrove Stream has been diverted by Cemex around the new sports ground area.  This included diverting the watercourse around a blocked culvert and improving the channel condition.  It is understood this work is complete.

EA  agreed to check the watercourse adjacent to the cricket club for any obstructions.  A bridge across foot path 23 may need to be improved to allow a greater flow.

It was agreed that Marsh Lane/Fox Lane area is a priority as is an important thorough fare. HCC still concerned that the watercourse down Coopers Hill/Marsh Lane may have insufficient capacity and liable to overtop it’s bank. EA asked to investigate capacity and options for directing excess water from the ‘main river’ onto land away from the road to reduce risk of flooding along B3272 and Longwater Road.

2          Longwater Road Area
It was confirmed the stream feeding the pond is part of a local drainage system, it is the landowners responsibility and not associated with the EA or Hart responsibility.

It was confirmed that Dial house did not suffer internal flooding in July 2007, Cobwebbs property suffered from flooding in their equestrian centre only.  Problems around Dial House should be alleviated by improvements at Marsh Lane area. 

HCC confirmed that the culvert, along the east side of Longwater Road, has been cleared.

3       Eversley Centre
Chequers Lane – an additional gulley is to be installed.  HCC are working with Eversley PC to improve local drainage problems.

Many of the problems appear to be related to maintenance, which is a land owners responsibility.  Drainage issues around 1-6 Holybush Lane are being dealt with by Hart DC. 

The flow control device on the Thames Water surface water drainage system at Sherlock Lea needs to be checked, to ensure that it is operating correctly.

4          A327 Warbrook Manor
Permission to replace culverts in Warbrook Manor has been requested.  EA to confirm progress of this.  The main issue is restriction below the A327.  An additional culvert (9”) was installed after the 2000 flood event.  The difficulty in enlarging this culvert are

  • Other services adjacent to the culvert
  • Maintenance of the down stream channel

Part of the culvert below the A327 is off set.

This area between Duck Farm and the Blackwater needs to be inspected to confirm the condition of the ordinary watercourses. Land owners for the land to be sort to confirm what improvements can be made to the drainage.  Eversley PC to be contacted to confirm if ownership details are known.

EA advised the culvert below the A327 should be equivalent to 900 diameter pipe.

Any changes to the watercourse through the allotments was reviewed.

It was agreed that Eversley PC plans need to be confirmed before the authorities can express a view on any improvements as EPC’s work will determine flows downstream.  This would allow a plan for streams A & B across the Great A to be developed.

From the Eversley PC flood report, it is not clear if the recommendations from the EA survey are to be taken up or if other solutions are to be developed.

5       Warbrook Lane
EA tabled a letter for review, this reiterated riparian owner responsibilities and is to be sent to properties along Warbrook Lane

EA confirmed the culvert through Rose Cottage had been replaced.  This was confirmed to be the section adjacent to the property only.

From the EA study, it appears improving the ditch adjacent to Warbrook Lane would be the quickest solution to flood problems.  This depends on the fall in the ditch.  EA to check details from the study.

It was agreed owners of Harry’s Cottage and Stepping Stones are to be approached to make improvements to the watercourse through their property.  Any improvements to Webbs corner would be subject to progress of this work.

Note – It was agreed this flooding affects a relatively low level of traffic on a minor road.  It is thought to be the result of un-consented improvements.

Agreed that HCC would put on hold any work on the vandalised headwall and collapsed pipe at Webbs Corner pending the EA coming back with view as to which way to route the water as this fundamentally affects the nature of any work here.

6       Eversley Street (Bonny’s Yard)
Main drainage is part of Thames Water drainage system.

Problems here should be alleviated by improvements at Warbrook Lane and Rose Cottage

The EA report suggested alternative routes for watercourses through the allotments.  Eversley PC needs to confirm if EA proposal is to be progressed or if EPC have new proposal.

7          Lower Common
EA confirmed they are not aware of any problems in this area.  EA agreed to confirm if there are any pollution issues at the stables (Rye Croft)

EA confirmed maintenance of the ditches is the responsibility of the riparian owners.