Update on Flood Control Activity in Parish since last meeting.
1. Cllr Tipper re-worked Appendix 2 of his report following the jetting team's visit during January
(on 12th and 13th). They established the actual path of the culvert that runs from the bends on
the Ashton Road.
This was installed after the flooding of July 2007.
The route was different to that previously assumed.
2. Cllr Tipper attended Operational Flood Working Group (North) meeting on 11 March 2015.
Wiltshire have recruited two additional Drainage Engineers, and for the north of the county
the engineer is Richard Williams, formerly of Atkins’ contractors so is already familiar with the
area.
3. The engineer has reviewed my report and attended an initial meeting (Friday 27 March) in the
village to see the situation on the ground.
4. A 'draft' report has been prepared on the issues near the bends on Ashton Road.
It is being reviewed internally but will be shared with us when finalised.
It is likely to recommend actions for both the council and local land owners.
The engineer has completed some water flow calculations based on a 1-in-100 year event and
concluded that if “properly maintained”, the solution should have the capacity to cope with
such an event.
5. On a second visit (Friday 10 April) some surveying work was carried out on the other two
areas on concern within the parish.
5a. The first is the B4040 bend by Greenacres and nos. 39, 34 and 33 Malmesbury Road.
Here the situation is such that the ditches on the north side of the road have a very limited
fall, about 100mm between nos 39 and 41.
Additionally the ditches to the north of the B4040 between no. 39 and the bridge beyond
no.42 are not clear. The recommended depth is 100mm below the invert level of the culvert at
either end.
The camera did not prove that useful in tracing the culvert back up from no.39 and stopped
prior to the property boundary, so it is not possible to know where this culvert terminates.
If the ditches are cleared then the engineer will arrange for the jetting team to attend on site
and clear the culvert, so that the full extent of the culvert on the north side of the road can be
established.
5b. The second area is on the bend on the east end of Swan Lane outside No.69/the Old Post
Office.
This area is important as it is on the main route to Hillside (the main housing density in the
village) and is the route least likely to suffer from flooding.
The area was surveyed to establish levels and falls and identify options.
The engineer has reviewed the data and produced some preliminary profiles, they confirm
that the area is virtually ‘flat’.
The ditch to the south of Swan Lane opposite Cross Lanes Farm needs digging out to provide
storage capacity if we are to transport the water from the corner of Swan Lane. We need to
identify the owner, the engineer has calculated that this could be 95 cu.m (90 tons).
Cross Lanes pond could also provide additional storage if also dug out.
Water flow calculations have yet to be done (based on the adjacent field and road areas) and
this may result in further considerations.
One outstanding issue is who owns the verge opposite the end of Waterhay as this could be
used as additional water storage resource, should the calculations predict this to be a benefit.
Also the culvert under Clancy Cottage was surveyed with a camera, it was clear, but reduced in
diameter as it passed behind the garage. Provided some form of gulley into this culvert to take
water from the field may be prudent once the ditch to the south of Swan Lane has more
capacity.
6. Other Drainage Observations
6a. Whilst travelling between sites in the village the Wiltshire Engineer commented on the
lack of maintenance on the ditches by Glebe Farm.
These will receive more water once the remedial work has been completed by the bends at
No.53 Ashton Road.
7. The Wild Project
Helen Richards and Jenny Phelps + Cllrs Richard Rummings and Dave Tipper met to
discuss water issues in the Parish.
The initial outcome was to walk the ditches between Swan Lane and the Thames where the
two flows cross by Brookside Farm and Home Farm.
So far Jenny has yet to get a response from either owner.
It is important to clear these ditches before clearing the culverts under the bridges on Swan
Lane, which the drainage engineer can arrange when the down-stream ditches are capable of
transporting the water away.
Dave Tipper
14 April 2015