July

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Ridgeway balancing pond (large version)

June was a good month for the project, with fine weather meaning the bulk earth moving for the project has been finished.

During July the earthworks will be ‘trimmed’ to get the final levels for embankments and roundabouts correct. The main areas for this are Ridgeway, the balancing ponds at Littlemoor and the southern part of the scheme by Manor Railway bridge, Two Mile Coppice and Lodmoor.

There is a huge amount of drainage still to put in for the scheme, including balancing ponds such as the one at Ridgeway pictured above.

There are 33 concrete drainage outfall structures on streams, drains and ditches across the scheme – with eight left to install.

The handrails, top-soiling and surfacing works on Chapel Lane, Southdown Ridge and Lorton Lane bridges will also be finished this month.

Chalk stabilisation of the road surface and placing tarmac will also continue.

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4 Responses to “July”

  1. Peter Harris Says:

    The balancing pond opposite the Littlemoor shops looks to be small and shallow and to be above the height of the shopping centre. How often is it anticipated that it will overflow?
    I would guess that a sizeable pipe takes its outflow, when close to full, away towards the enlarged pond at the Preston end of the new road but I don’t see any route for an outflow from there so assume again it is a pipe underground. Will a new large pipe be layed? What happens when any of these pipes are blocked or just cannot cope with the flow? Are we looking at multiple single points of failure here? Are there any calculations for how often parts of Preston will be flooded?
    Realise that I have asked a number of questions but would much appreciate a comprehensive answer, please.

    Regards

    Peter Harris

    • Weymouth Relief Road Says:

      Hi Peter

      The balancing pond opposite Littlemoor shops is indeed fairly small, but so is the catchment that it collects runoff from. This balancing pond doesn’t collect any runoff from the shopping centre, which has a drainage system in place already. What it does take is runoff from 650 metres of the new section of Littlemoor Road . Some of the field drains to the north are also diverted into this drainage system. The pond discharges into the existing Littlemoor drainage system, which has sufficient capacity to take the extra runoff from the road and always did take the field drainage. This pond is not quite excavated down to its final level as yet.

      The very large catchment of Bincombe Valley nearby is dealt with by the balancing ponds at Littlemoor, which are being expanded as part of the relief road works.

      The Chalbury basin pond at Preston already has an outfall system and we don’t modify this as part of the relief road works but we have increased the amount of storage available at Chalbury before discharge. There are two outfall systems at Chalbury pond. One is designed to discharge at a controlled rate to avoid downstream flooding, and the second is an overflow weir at a higher level to cope with major rainfall events. The Chalbury system is designed to cope with a 1 in 120 year storm event, and then oversized by 20%.

      Drainage pipes have a screen across the entrance, and smaller pipes can be jetted to remove blockages. Larger pipes can be inspected by camera and manually cleared if necessary.

  2. Chris Says:

    Hi,

    I’ve tried to follow the plan (PDF on http://www.dorsetforyou.com/index.jsp?articleid=3463) but I’m having trouble working out how the cycleway/bridleway/footpaths all work as part of the road.

    Is there a better plan that shows all these parts in relation to the road? As in, what side of the road they are on, how they cross the road etc?

    Particularly the Lorton Lane area, how it joins/leaves the road – and how it’ll work by the new roundabout/park and ride behind Morrisons.

    Thanks

    • Weymouth Relief Road Says:

      Hi Chris,

      The best place to look at a simplified map of the cycleways is on the back page of the last edition of the Route newsletter.

      For the most part, the cycleway is on the railway side (northbound) of the road and is one metre away from the edge of the road. From Ridgeway to Dorchester it’s on the southbound side of the road.

      The cycleway joins up with each of the bridges at: Lorton Lane, Southdown Ridge, Littlemoor, Chapel Lane, Bincombe and Ridgeway.

      At the southern end of the scheme it joins up with the cycleway around the rugby club and into the Lodmoor Country Park.

      There’s a new subway at the Morrison’s roundabout and an underpass under the road at Two Mile Coppice, or you can cycle over the railway bridge.

      Also, there’s a cycleway on either side of the new Littlemoor Road.

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