Phase One September 2006

• Weir Watching - May 2007

• Responding to questions & concerns

• Phase Two - May 2007

Local Contractors, Jenkins Marine, arrived on 4th September and set up a site compound on the hard standing left by demolition of the Pavilion.

Sub-contractors Earlcoate installed the new footpath through the long field.

Phase One excavation work included:

The stream and flood basin system is designed to provide 3,500 cu.m. of stormwater storage.

Phase One was completed in December 2006.

11th September

The main elements of the project have been marked out (the fishing pond, the stream bed and the footpath) and topsoil removed; it will be stored and replaced when the excavation work is complete.

A small standing of willow scrub by the new fishing lake has been cut back; the area will be regraded and the willow will grow back.  One other small area will be cleared of vegetation, at the end of the wooded walk at Herbert Avenue where the slope of the access path will be improved for people using wheelchairs and mobility scooters.

12th September

Excavation is underway; the fishing pond is the first part of the stream works to be undertaken.  The spoil from it has been relocated to regrade the approach from Turbary Close. 

Work has started on the footpath and should be continuing at about 40 metres per day.

19th September

Good and exciting progress in the last week. 

The fishing lake has been dug and is filling with groundwater.  It is also supplied by a natural spring that was discovered during the excavation and water appears to be rising at about 1" per day.  The lake has two small islands in the centre, both of which should be just below the final water level; they will become vegetated to provide visual interest and a refuge for fish and other wildlife.  There are still some finishing touches to be carried out.

The footpath is coming along well and will probably be completed by the end of next week.

Work started in the last couple of days to remove top soil from the long field, where excavation will soon start for the stream channel. 

We have all been very encouraged by the positive attitude of neighbours and users, and the lack of problems at the site.  After a few harmless pranks in the first few days, the young people are now far more interested in when the fishing pond will be stocked and ready to use.

At the weekend Jenkins cleared some of the bulrushes and other vegetation from the existing wildlife pond, exposing for the first time in many years part of the original granite kerb wall around it.

22nd September

Probably the most drastic changes have taken place in the last few days.  Work has started in the long field to excavate the flood basin and stream channel.

Water levels in the pond rise steadily, and the footpath route is complete; the sub-contractors are now just adding surface material to the the required level. 

They were also today installing ducting along the northern edge of the footpath to take cabling for the lighting.

Cllr Graham Wilson spent two wet hours on site today familiarising himself with all the project details.

25th September

The fishing lake quickly filled after the torrential rain on Friday & Saturday.  The islands are completely under water.  Eventually water levels will reduce slightly (an outlet pipe has been included in the design to maintain a safe level, releasing flood water slowly to the stream.

The photo (below right) shows the view of it this morning from a high point on the heathland behind it; beyond the lake it's possible to see how the grassland alongside the route from Turbary Close has been regraded by spoil from the lake.  On the left of the photo is the pile of topsoil removed from the area when work started, and which will be replaced when this phase of the project is complete.

29th September

The end of Week 3 and progress continues on schedule despite the at times inclement weather.

The flood basin and terraced stream channel has been cut through the long field.  Next week the final cut will be made, just 2m wide and 250mm deep in the centre of the channel; water will flow through this cut during dry weather conditions. 

During heavy rainfall stormwater in the system will be held in check by utilising a section of the existing culverting at the downstream end of the channel as a 'throttle'.  This pipe will control the quantity and velocity of water flowing downstream.  In this way it acts as a flood detention structure to prevent flooding of properties in Alder Crescent.

Stormwater from Evering Avenue & surrounding area (photo below) will be intercepted and cleansed by creating a small SUDS or vegetated wetland through which it will run before entering the stream.

03rd October

The wet weather has been getting the better of progress; areas of the stream bed has filled with water, causing difficulties for the excavation work.  There is a lot of clay in the substrate which hampers drainage and the contractors are having to pump out pools of water.  Meantime, work has started on the 'embankment'; it has no real function but simply makes use of some logs from the site to create a interesting feature along the stream channel.

05th October

Earth moving has finished and the large dumper trucks have left the site.  The diggers remain to carry out the final cut in the stream channel, remodel the viewpoint and replace all the topsoil.  Work has started on the new bridge.

Andrew Flockhart, the Council's Strategic Director, spent some time on site this afternoon to check on progress.

Next week we will be regrading the end of the footpath at Herbert Avenue, and a kissing gate will be installed to allow (for the first time at Bourne Valley Park) disabled access.

The Contractors expect to be on site for another two weeks to carry out the rest of the scheduled work and a few finishing touches.  At the request of several parents, especially those pushing buggies, these will now include small improvements, and probably an extension, to one of the informal footpaths.

15th October

Contractors have spent the last 10 days working on the stream channel and replacing topsoil across the site.  At Herbert Avenue the disabled access has been regraded and the new kissing gate is due to be installed this week.  The weir structure has also been completed, with concrete studded with pebbles to soften its appearance. 

The weir will only come into action during heavy rainfall, when the flood detention capacity of the channel upstream of the weir is full.  Water will flow through the 'letterbox' in the weir and tumble down the 'ramp' on its journey through the park and on to Bournemouth Gardens.  During dry flow conditions the stream will run through a pipe in the bottom of the weir structure.

18th October

The pipe was broken through on Monday evening (16th) and the stream is now flowing though the new channel.

Clive Smith, Head of Leisure Services made a site visit today, accompanying Allan Frake of the Environment Agency who came to see the fishing lake that organisation paid for.  The kissing gate at Herbert Avenue was also installed. 

The Contractors expect to leave site on Friday, before which they will regrade the sides of the upper level of the fishing lake and complete the footpath.

Soon afterwards the Council's grounds people will sort out the rubble that litters the site and will start planning to seed the stream channel and plant the viewpoint.

20th October

The heavy rainfall during the past couple of nights has washed through areas of stagnant water and fine silts and the stream is now beginning to look like a more natural watercourse, with a streambed that is becoming gravelled.  We can really visualise how good it will look when the grass grows.

The steeper edges of the fishing pond have been regraded to a more gentle slope.

The Contractors have finished their work and will be moving off the site over Monday & Tuesday next week.

We still have the bridge to construct; we're just waiting for the holly green cast iron railings we're having made (they'll be delivered in about 4 weeks).  Then there's the seating and dog/litter bins to go in, and some lighting if that's what the majority of people want and from chatting with people on site it seems that many of them do.

23rd October

The contractors have completed the finishing touches to the new footpath and added another short length from the Milbourne Crescent heath path to the school route.

They've tidied up the main access from Turbary Close, wound down the site compound, and the last of their equipment will leave tomorrow.

It's good to see that grass has already started to grow in the topsoil along the stream, so we're hoping we'll soon have some colour amongst the mud!  The seeding and planting that's planned will also make a difference.

Note 1: Heavy rain has waterlogged the most recent lengths of footpath; when they have had a chance to dry out they will be rolled flat. 

Note 2: Also due to the wet weather conditions, it is unlikely that seeding and planting will be happening next week as we had planned; we will need to wait until the ground conditions are more suitable.  Latest news will be updated here as soon as we know more...

30.04.07 - With the weather much improved, work recommenced at Alderney today. 

• Read about Phase Two

During the delay we carried out some drainage work alongside the footpath from Herbert Avenue, creating a wetland & reedbed area and piping run-off beneath the path and into the stream.

Weir Watching, May 2007

Above: the 2m deep stream channel beyond the bridge, filled with floodwater, acts as a 'detention basin'.  Below: when it reaches full capacity water flows through the weir and down the lower channel and the second detention basin.

Photos courtesy of Glynis Northwood-Long

Responding to questions & concerns:

• The weir: several people have asked when they might see the weir in action.  The disappointing answer is that, unless you are out in an extremely and unusually heavy rainstorm, you won't.  The entire system of stream channel and flood basin has been designed to store the rainfall from a storm that is likely to happen only once in 20 years (known as a 1:20 event) - see note.  Total capacity is 3,500 cu.m., with a little extra available in the fishing lake should it ever be needed.  Capacity was designed using calculations by Wessex Water who carried out flow measurements and modelling over a period of weeks during the winter of 2005. 

During the 1:20 event water will first be stored in the channel upstream of the weir until it reaches the level of the 'letterbox' opening, when it will tumble over the weir and into the second phase of storage - the downstream channel and flood basin created beside the original footpath.  The footpath should never flood, however.  If levels should exceed those predicted, excess water will escape via the high level overflow (simply a depression in ground level) that leads from the flood basin to the ditch beside the long field, which then runs straight back to the stream and via another high level overflow into the fishing lake.  The velocity and quantity of water that's released to the stream under predicted conditions is controlled by the size of pipe and 'letterbox' of the weir and at the downstream end of the flood basin.

Note: Several residents and council officers report witnessing a 1:20 event on at least three occasions during Spring/Summer 2007! 

• Viewpoint: we have received an email from a resident of Evering Avenue who is surprised and concerned at the size of the "small" viewpoint.  In fact "small" is not a good description, it's lower than some people expected but does take up a fairly large area and, from some angles, seems quite high & steep-sided in it's rough form.  Now we have used all the spoil we needed to, it's being remodelling into a more appealing shape and once the grass makes an appearance and we have planted some shrubs it will lose it's 'waste ground' look.  The view from the top is just as good as we'd hoped.

• "Bomb Holes": as named by one resident.  The two holes dug to the north of the stream channel intercept a storm water drain that brings run-off from the Evering Avenue catchment.  We will be planting them with Yellow Flag Iris and other vegetation which will act as a SUDS to improve water quality before it enters the main stream.  For the time being I'm afraid they look exactly as described!

• Footpaths: we have had some questions about whether we intend to upgrade any of the footpaths from, particularly, Milborne Crescent & Tollard Close, as part of the project.  The simple answer is that it has been neither considered or budgeted for.  However, if we have money available when the scheduled works are complete, we will certainly discuss it.  The paths cross part of the site's SSSI (protected heathland) so we would firstly need to consult with English Nature.

• Space: one or two residents, seeing the width of the top of the stream channel, have expressed concerns that there will be less space for exercising their dogs.  We would like to reassure them that the final channel form will be terraced and grass-seeded; during dry weather conditions water will run only as a shallow stream at the bottom.  If anything, dogs will find the landscape more interesting and challenging than before, and will probably enjoy playing in the water which, during dry weather, should be perfectly clean enough for them to do so.

• Safety: A lady has called the Council to express concerns over health & safety issues surrounding young children crossing the site to and from school.  The Contractors are very aware of users' safety, especially the young people.  The maintain a well marked public path across all main routes.  During peak times (8.30-9.00 a.m. and 3.15-3.45 p.m.) they ensure supervisory personnel attend all points that people will be crossing areas used by moving machinery.  They are also ready & willing to answer any questions users may have about the project.

• Dust & Noise: two residents have asked how long the dusty & noisy excavation work will continue.  Mostly it is caused by the constant movements of dumper trucks and we anticipate that they will be off site by Monday or Tuesday (2nd/3rd October), after which things will calm down considerably.