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Recent Projects

This page summarises some of our previous projects and gives an indication of the scope of our work. Further details of each of the schemes can be viewed by following the relevant links.

Our main areas of operation are river and flood modelling, the design of drainage for new developments, expert witness work for drainage matters, Flood Consequence Assessments and Flood Risk Assessments.

Please Contact Us for further details.

Corporation Street bridge, Ystradgynlais

TUFLOW river modelling, Ystradgynlais

A proportion of our river modelling work involves upgrading existing models held by National Resources Wales (NRW) and since their standard river modelling software is TUFLOW, many of their existing models use that program. An example of this type of work was the FCA for a proposed small residential development in Ystradgynlais, a town about 20km north-east of Swansea.

NRW's existing flood maps showed that the proposed development site, just to the south of Ystradgynlais town centre, was on the edge of the area predicted to flood once every 1,000 years. In addition the access route for the site would be flooded to a significant depth probably meaning that it would be unsafe to use during flood conditions. These factors would mean that the site would not meet the criteria...


Hydrograph produced by modelling work

Expert Witness, flooding from highway drain

One of our senior staff acted as an expert witness in a court case regarding a complex flooding problem in southern England and this involved producing a comprehensive expert witness report and later giving evidence in court. The flooding affected the highway and a residential property, the latter being flooded internally on occasion.

The terms of reference involved assessing the suitability of an existing Micro Drainage computer model of the drainage system and examining the maintenance regime at the site. Our expert was also asked to construct a separate independent model of the drainage system and to comment on the flooding problem in the light of this.

The modelling work carried out was based on data produced by a manhole survey organised as part of the study...


Flood Risk Assessment,

Morton-Roberts produced a Flood Risk Assessment for a 3ha greenfield site close to the River Frome in Somerset which the Client wanted to develop for residential purposes. The study examined the risk of flooding from various sources including fluvial (river), surface water, ground water, sewers as well as due to infrastructure failure.


Watercourse study for redevelopment site, Cwmbach

Morton-Roberts were engaged to assess if it was possible to drain the attenuated surface water flows from a proposed development into a small local watercourse. Part of an existing housing estate in Cwmbach was being redeveloped with some 37 new residential properties replacing the existing. The old development drained to the combined sewerage system but the new houses were required to...


Flooding advice for financial services company

Morton-Roberts provided advice to a financial services company regarding a flooding problem which affected their head office located in south-west England. The lower floor of the office had flooded during the summer storms of 2007 and the company was anxious to ensure that it was suitably protected against future floods...


Existing barn under conversion

Drainage Strategy Report and surface water (SUDS) design

Morton-Roberts produced a design for the surface water drainage for a development comprising 18 new and converted residential properties on a brown field site within a Herefordshire village. The site was formerly occupied by farm buildings.

The ground at the site was largely favourable to SUDS infiltration drainage although percolation tests showed that the soil in some parts of the site was impermeable. The use of soakaways was further constrained by the very dense proposed housing layout, together with a high water table. The drainage of the site in general was difficult since it was largely flat and the only available watercourse was at a very shallow depth...


Off-site drainage works under construction

Off-site surface water sewer design, Herefordshire

Morton-Roberts was engaged to design a suitable surface water sewer to act as an outfall for this 30 house development site located adjacent to a main road in a small village in Herefordshire.

Prior to our involvement, the design of the on-site surface water sewer system for the development had already been completed. The surface water from the proposed roofs and highway was planned to drain into new surface water sewers which were to include a flow control and oversize pipes to attenuate the outflow. These sewers were to be adopted by Dwr Cymru Welsh Water (DCWW). Our appointment was prompted by the point of discharge of the proposed on-site sewers proving to be at a different level to that originally assumed...


Inlet to culvert

Expert Witness, flooding from culverted Watercourse

One of our senior staff acted as an expert witness in a case involving flooding from a small culverted watercourse in southern England. A blockage had formed in the culvert which resulted in extensive flooding to two properties during a period of high flows caused by melting snow combined with heavy rainfall.

Our expert witness provided opinion on the obligations of the various parties, the speed of occurrence of the flooding, the reasonable steps which one of the parties could have taken prior to the flooding and the significance of...


Drainage for new development, Gowerton

Morton-Roberts secured approval for the disposal of surface water from a new residential development on the site of a previously demolished property. This proved to be extremely challenging since Dwr Cymru Welsh Water (DCWW) had imposed a moratorium on further surface water being discharged into their Gowerton sewer catchment. This was because excessive spills from combined sewer...


River Pelenna

Linked 1D − 2D river model,
River Pelenna

This study was carried out to assess the flood risk to a proposed development of three detached houses on the site of a former HGV garage situated close to the River Pelenna to the east of Neath in south Wales. This was done in the context of TAN15, the Welsh Government's document governing new development and flood risk.

The length of modelled river was fairly steeply graded with a bed comprising sandstone cobbles and boulders. Approximately 75m downstream of the site itself the river was crossed by a three span reinforced concrete road bridge and just downstream of this, a small tributary flowed into the river from the west.

A Flood Estimation Handbook (FEH) study covering both the River Pelenna and the tributary catchment...


Flood Consequence Assessment, Powys

Morton-Roberts produced a Flood Consequence Assessment (FCA) to TAN15 to support a planning application for the construction of a new building near the confluence of a local watercourse and a main river within the Brecon Beacons National Park. The building...


Weir downstream of DCWW water abstraction point

River Modelling, Lisvane, Cardiff

The study involved producing a river model of the Nant Ty-draw and Nant y Felin watercourses within the predominately agricultural land to the north-east of Lisvane in Cardiff. The model was then used to determine the extent of flooding adjacent to a proposed new residential development in the area. The model used the river flows estimated using a Flood Estimation Handbook (FEH) study also carried out a part of the project. Morton-Roberts also sized six new culverts to carry the proposed development's spine road over the watercourses.

The catchments of the two watercourses extend to the ridge of the steep hills which rise to the north of Cardiff.

The FEH study involved estimating the flows at several points along the two named watercourses and tributaries and...


The site development

Surface water (SUDS) design for development, Monmouthshire

Morton-Roberts were engaged to produced a design to dispose of the surface water from this small 'green field' residential development, comprising 5 properties, on the edge of a village in Monmouthshire.

Prior to our involvement, percolation tests had been carried out at the site which suggested that the underlying soil had a very low rate of permeability. This might have meant that SUDS infiltration techniques such as soakaways could not be used for the disposal of surface water. This would have been problematical since the site was some distance from any other means of draining the surface water such as a watercourse, surface water or combined sewer...


Lots Road pumping station

Counters Creek Flooding Scheme

One of our senior staff was seconded to Thames Water's Counters Creek team in Paddington, London during 2012 to assist in the preparation of outline sewerage designs. These were intended to address extensive property flooding in the Shepherd's Bush, Hammersmith, Fulham, Chelsea and Belgravia areas of west London. The scale of the flooding problem in the area first became apparent during the heavy rainfall of July 2007.

The Counters Creek flood alleviation scheme in fact comprised one large tunnel project and several smaller sewerage schemes which were together intended to alleviate the flooding of the basements of some 2,000 properties. The cost of the scheme was estimated in January 2013 as being approximately £230m to £310m...