Elliptical pipes were recently employed to offer a stormwater attenuation and storage solution for a new 48 property housing development in Pontefract. The £8M investment by Barrat Homes was built over a 3.2 acre site in a greenfield area. Therefore there was a need to ensure that the local environment was not impacted. This would require stormwater peak flows off site to mimic the existing situation.
Due to the site’s nature, and its steep landscape, there was limited depth available to install an underground tank. The need for vehicle loading to National Highways standards.
Luke Martin, engineer for Barratt Homes explained that circular storage pipes “… would not have large enough cross sectional area to keep attenuation within the lower part of the site. We would have needed very deep drainage with extensive costs associated”. Elliptical pipes also do not need any in-situ secondary inverting to form dry weather flow channels or additional jointing material due to its integrated watertight elastomeric gasket.
The Stanton Precast team then worked closely with design consultants on the set up and design of side entry manholes. A total 31 elliptical pipe units (DN2650 x 1500) were supplied, along with fittings and end walls. An addition, a further 22 DN1600 circular pipes were supplied to replace the originally specified plastic pipes.
The project contractors, PJ Towey Construction ltd, were also pleased with the level of support and site training offered to help with the management and installation of the elliptical pipes on site. Martin Towey (PJ Towey Construction Ltd) noted that Stanton Precast members of staddd, including technician Chris Taylor, were “…a great help to the guys on site and made it a lot easier to work with the elliptical pipes. Overall we were really happy with the products, services and ease of installation. Once the team got started the installation was quite quick”.
FP McCann has supplied its largest precast StormCleanser system to date to a recycling and waste management facility in Norwich.
The PSH Environmental ltd recycling facility is based on the Rackheath Industrial Estate. As part of its site extension plan, the onsite surface drainage network was upgraded to help deal with increased surface water run-off and improve interception and prevention of contaminants within the surface water run-off washing out into the site’s holding lagoon.
The 3600mm wide StormCleanser™ hydrodynamic separator unit was supplied from FP McCann’s Ellistown precast concrete plant in Leicestershire. The unit was installed by civil engineering contract MB Plant & Civils with DN900 pipes for the unit’s inlet/ outlet.
Surface rainwater and any pollutants enter the StormCleanser™ chamber via the inlet pipe where the internal layout then enables low energy vortex flow patterns to form. This allows floatable materials such as plastics, paper and other light debris to gather at the top of the system and heavier sediment to settle at the bottom of the treatment chamber for removal by standard gully suction equipment. A baffle plate located above the sediment storage sump prevents the re-suspension of solids. Treated water then flows out of the system back into the main drainage network.
Commenting on StormCleanser™, Matthew Body Managing Director of MB Plant and Civils says, “FP McCann delivered the 3600mm precast concrete StormCleanser™ chamber and the internal stainless steel components. It was then a simple task for our onsite team to assemble the unit which comfortably sits within the online drainage system”.
StormCleanser™ can be installed in precast concrete drainage chambers ranging from DN1200 up DN4000mm accommodating pipe diameters from DN150 up to DN900. Modular and bespoke designs are available for multiple inlet orientation with a choice of flow direction providing optimum configuration performance.
Stanton Precast provided up to 330 metres of 2650x 1500mm elliptical pipes, with a number of side entry manhole units, for the Pentland View housing development in Bilston, Edinburgh.
Situated in Midlothian, Pentland View, a new 190 unit housing development, is surrounded by countryside and has a striking background of the Pentland Hills. The development is located only 7 miles from the centre of Edinburgh and will include both, private and affordable housing units.
Analysis was carried out by Scottish Water engineers and the consultant Ironside Farrar into the DIA (drainage impact assessment) and the best solution for Scottish Waters combined sewer for storm and foul water. This included assessment of area, ground conditions and specific needs of the project. Stanton Precast Elliptical Pipes were then specified as they met the project criteria, which required more storage with efficient self-cleansing properties.
Advance Construction Scotland Ltd were awarded the contract and started DIA work on site in July 2021.
Over 330 metres of elliptical pipe were ordered to create two runs to sit parallel on a sloped area. Included in this were integrated side entry manhole units cast in to some of the elliptical pipes during manufacture. This eliminated the need for large diameter chambers to be constructed for man entry and maintenance as well as contributed to a quicker and easier installation. Again these were specified along with end walls for some of the end units.
Providing integrated products during manufacture ensures that quality and durability is maintained and there is less time, materials and waste on site.
A total of 69 loads were delivered in just 20 days to meet the installation scheduling – on time and in spec.
Advance Construction Scotland Ltd were impressed with the elliptical pipe and support from Stanton Precast.
Marc Watson, Technical Manager for ACS Ltd said: “Stanton Precast were really helpful with installation data, off loading and turning, elliptical installation literature to assist site with works. Delivery schedule with timings were agreed prior to the first delivery, so that site were fully aware when they were due, so that they could work around other site deliveries. Stanton Precast were able to double the amount of units being delivered to site per day to assist with speeding up installation on site. Lifting clutches were provided to assist with off- loading and placing units.
Our contracts manager John Irving has advised that these works are currently progressing ahead of programme and without any issues. Our site supervisor on site had said that the units were very easy to move around site and place in excavation despite their awkward size.”
The key benefits of using elliptical pipes:
Stanton Precast (formerly Stanton Bonna Concrete Ltd) are widely recognised as a leading UK manufacturer of precast concrete pipes, manholes, culverts and linear drainage as part of a comprehensive range of precast offsite solutions for water, highways, rail, housing, commercial, telecom and power sectors of the construction industry.
This, together with being part of Sateba, a European specialist in precast concrete rail and infrastructure, gives confidence that our knowledge and experience of precast concrete products is extensive and professional.
Sateba’s aim is to be the leaders in sustainability within our industry and ensure precast concrete will play its part in the circular economy. We are looking forward to working on building the future in a more sustainable way.
More information can be found at Stanton Precast’s website:
Castlehouse Construction has the £7m main contract to build three industrial units totalling 29,950 sq ft for Carnworth Estates adjacent to the Pheasant Fields Lane retail park in Skelton. The project also included the construction of a car park for approximately 70 vehicles, plus soft and hard landscaping. Each industrial unit will have its own surface‐water management system to collect rainwater and surface water run‐off. These all feed into a central sub surface attenuation tank located under the road near the development’s main entrance.
Marshalls Civils & Drainage supplied 32 precast concrete MC2010 STKA box culverts laid in a double run to create the attenuation tank for storage and management of surface water from the three units. From receiving the order to delivery of the first units, Marshalls had a tight lead‐in time of less than 10 weeks. Marshalls was selected to supply the precast units for the attenuation tank on two main criteria: quality and availability.
The ability to supply standard units from existing stock was a key factor in keeping construction of the attenuation system on schedule.
The underground tank comprises 32 MC2010 culverts laid in a double row. Twenty of the culverts were standard designs which could be delivered immediately ex‐stock, while the remaining 12 were bespoke units manufactured to order. “Being able to use a stock product allowed us to speed up the programme,” explains Marshall’s Business Development Manager (Special Projects) Billy Fairhurst.
Castlehouse dug the excavation and cast the base slab for the attenuation tank and was able to start installing the standard MC2010 culverts without delay. Meanwhile Marshalls began manufacturing the 12 bespoke units for delivery on a just‐in‐time basis. The bespoke units included four end‐wall culverts with custom designed access holes and connections plus another eight units manufactured with special penetrations to connect the two parallel runs and to collect water flowing in from gulleys.
Dave Crozier, Project Manager with Castlehouse Construction, praised the quality of the Marshalls product as well as the support provided by Marshalls during the installation phase: “Marshalls kept us fully up‐to‐date with the manufacture of the specials and provided helpful advice to make the installation easier for us,” he says. It only took seven days to install all of the units, backfilling the excavation as we went,” he noted, “It took us only two weeks to finish the entire job.”
FP McCann has supplied and installed a 1,000m³ precast concrete panel attenuation tank on behalf of housing developer Miller Homes and their main drainage infrastructure contractor Esh Construction. Once complete the ‘Roman Fields’ development in Corbridge, Northumberland will consist of 123 prestigious properties. The attenuation tank is designed to alleviate flood risks from the site and to cater for a 1 in 100 year storm surge event.
The attenuation tank is amongst a number of precast concrete products that are now accepted by Northumbrian Water within Sewers for Adoption 6th and 7th Editions and is part of the FP McCann multi-purpose StormStore™ panel tank range which can be designed and installed up to 6 metres high with overall dimensions to suit the client brief. Measuring 23 metres long by 17 metres wide at a height of 3 metres, the online drainage precast concrete panel tank sited under the access road, manages a storm event by capturing excess surface rainwater. The water can then be released back into the drainage system at a controlled rate, thereby relieving the pressure on the main network and reducing the risk of downstream flooding into the nearby Cor Burn.
Prior to the construction of the tank, a 75mm thick blinding layer of concrete formed the hardstand to receive the poured floor slab; a 250mm thick layer of C40 reinforced concrete. The panel sections manufactured at FP McCann’s state-of-the-art precast facility in Byley, Cheshire were then delivered to site over a period of 4 days for installation by the approved FP McCann specialist fixing team.In total, 22 external walling panels were fixed and 24 internal wall units to form four special internal support walls. Large openings in the internal walls allow water to flow freely between each section. Covering the tank are 70 individual precast cover slabs. 4 manhole openings have been cast into 4 end slabs to give easy access for maintenance purposes.
The tank has been set on a 1:400 fall towards the outlet and the base is complete with a dry weather flow channel. To complete the tank, in-situ concrete was pumped onto the roof slabs to provide an additional protection layer.
Commenting on the panel tank design and build, Steve Morris, Senior Quantity Surveyor for Esh Construction says, “With final adoption under the Northumbrian Water S104 approval process, we had to take into consideration a number of factors on tank design. Robustness and long-life, low maintenance performance was key to our choice of attenuation tank. FP McCann’s multi-purpose panel tank system fitted both the design and performance criteria. The FP McCann approved installation team undertook the work in a timely, efficient and safe manner. On future projects, we will certainly consider similar FP McCann supply and install precast concrete StormStore™ panel tanks systems.”
In addition to the tank, FP McCann has also supplied standard precast concrete spigot and socket pipes, manhole chamber rings and cover slabs to the Corbridge housing development.
FP McCann’s multi-purpose panel tanks have a 100-year design life and can be installed up to 6 metres high with no footprint size limitation and are designed for pedestrian loading through to LM1 highway loading.
Internal design features can be added such as weir and baffle walls and penstocks or flap-valves can be pre-installed. Typical uses include:
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