Drainage problems in Kirk Road/Kilmalcolm Road. 

Residents have brought to our attention two issues relating to the drainage systems around Kirk Road.  It may be that there are connections between both issues, but they should be dealt with separately. 

There is the large pipe or culvert at Burnside Cottage which appears to accommodate some of the excess storm water.  Looking at the old mapping it does seem likely that it extended an older culvert which passed under Kirk Road before the cottages were developed.  But if it did it was only ever a storm water drain to compensate for the road having cut-off natural ground water drainage from the fields to the north to the burn.  Much of that would now appear to flow onto Kilmalcolm Road.  There is no evidence of a burn to the north of Kirk Road.  

We believe that the flooding of Kirk Road is an issue for the Council.  It may be that solving this issue may mitigate other problems of overflow to the main sewer – one cannot be certain until the Council investigate and chart the sewers, and storm water systems and regimes in the area.  In areas of this age it is likely that there will have been un-chartered and ad hoc connections made between old private systems and the younger public systems. It may well be that Burnside culvert is one such example.  Whatever, it is being used by the Council to dispose of storm water which arises to the north of Kirk Road. 

We have considered a possible solution and suggest that the Council should install a dual drain in the north verge to Kilmalcolm Road to carry the ground water and to provide field drainage to the road and immediate fields. This should flow into a catchpit on the north side of Kirk Road adjacent to Bankfoot Cottage and from there be piped to the burn – choosing a route which does not pass under property.  There would also be some uplifting of kerbs and road reshaping required to Kirk Road and reconnection of road drainage.   This should deal with the apparent sources of storm water, but we would recommend that that the Council provides a large factor of safety for dealing with unseen sources and further increase in the future. 

The Scottish Water main sewer overflows at a manhole situated in the wood on the south side of Kirk Road, opposite the Doctor’s Surgery.  At this point a combined drain which runs along Kirk Road from Kilmalcolm Road joins the main sewer which passes thorough the gardens behind the houses on the south side of Kirk Road.  We assume that this sewer collects both storm and foul from the old village.   The capacity of these two joining drains at full flow exceeds the capacity of the drain they connect into by 60%.  Hence the reason it overflows at times of high rainfall.  The main sewer also overflows into the burn behind Burnside Cottage. As the cover levels at those two points are very close and the one in the wood may be the higher of the two, it would not be safe to conclude that the size of the main sewer is inadequate. 

However, there is a blue plastic deposit at the manhole in the wood which is not evident at the other manhole.  We believe that its presence is coincidence and has nothing to do with the overflow.  However, if it does, you would have to assume that it arises from a source which connects down stream of Burnside Cottage which supports the anecdotal view of local residents.   

We suggest that Scottish Water provides a relatively inexpensive interim measure by providing an overflow arrangement where the Kirk Road drain and the main sewer meets.  It should be provided with screens to collect solids and outfall into the burn at a point below the sluice.   However, in the long terms the system requires upgrading.  To accommodate full flow in the drains referred to above and another main sewer which joins the combined flow at a manhole on the south side of the burn the main sewer which flows down to the Gryffe Valley main sewer is also inadequate and requires upgrading. 

As the system is a combined system a new system it has to accommodate increases in storm water and an alternative may be for the Council to capture more storm water run-off from hard and soft areas and guide it into the burn.  This should be considered as part of the work required at the junction of Kirk Road and Kilmalcolm Road. 

We also draw reference to the damage poor storm water drainage causes to the roads.  It is an essential requirement for road maintenance that the ground water level is maintained below the base level of the road pavement.  It depends of course on the natural ground conditions, but 1 metre below is a good target.  In our opinion a substantial amount of poor road surface conditions in this area are caused by inadequate ground water drainage.