Construction Only Award
Client: Roads Service NI
Constructor: Mc Laughlin & Harvey/PT McWilliams JV
Within the A32 Cherrymount Link Scheme, there were large areas of poor unsuitable material for building a road foundation therefore a method of Excavate & Replace was employed to remove this unsuitable material. This therefore resulted in potentially large volumes of material to be taken off-site.
Within Excavate & Replace Area 1 (Carran to UFM roundabout) there was approx 30,000m3 of unsuitable alluvium / peat material, and within Excavate & Replace Area 2 (UFM to Coa roundabout) there was approx 60,000m3 of unsuitable alluvium / peat material.
There was also a Cut area of approx 30,000m3, so in total this equates to 240,000t of material potentially to be removed from site.
To reduce waste going to landfill and as a more sustainable solution we leased neighbouring low lying lands and obtained Planning Permission for its use as a tip area for the poor material, and also incorporated the cut volumes into the road design to allow for 30,000m3 of fill. This fill material was then tested and deemed suitable to be used within the fill areas in the correct weather conditions.
Therefore the fill re-design, and leased neighbouring lands, prevented any material from going off-site which equated to a saving of 96.9 tonnes of transport carbon.
The adjacent tip area also allowed the necessary time for the unsuitable material to dry so it could be levelled over the low lying area and small volumes re-used on site within landscaping areas.
This ultimately enhanced the neighbouring low lying lands, by reducing any potential for flooding, increased the productive land area of this farm and created a highly fertile landscaping material (top soil/peat mixture) which was used within the full road scheme landscaping area.
St Michael’s construction students site tour
Historic Environment & Archaeology
The presence of a Crannog within the A32 Cherrymount site area was alluded to, but the exact location and position could not be exactly plotted as it was below water in a bog area. This was positioned within route of the new road. The only method of determining the exact location was to de-water the site and commence investigation works. From the outset of this project McLaughlin & Harvey/PT McWilliams liaised with the NIEA as to the initial locating and investigation works of the Crannog, which then progressed to a preliminary archaeological dig to determine if this was a viable Crannog settlement. At this stage the road design was to include for the Crannog, with no disruption to the structure.
However, the initial archaeological findings being that the Drumclay Crannog was artefact rich, and had potentially settlement finds dating back thousands of years. Due to these findings it was then agreed that the Drumclay Crannog would have a controlled full excavation, with archaeological logging of this structure step by step to determine the Crannog construction make-up and insight to the living conditions, materials and tools used by its settlers. This was the first controlled full excavation of a Crannog in Northern Ireland, and only the third Crannog excavation including Southern Ireland, so these works were of significant importance and the archaeologists needed the necessary time to complete the dig.
This resulted in McLaughlin & Harvey/PT McWilliams setting up a separate fully enclosed site dedicated to the archaeologists, which had separate entrance, parking, office and welfare facilities to house between 25-35Nr archaeologists. McLaughlin & Harvey/PT McWilliams cooperation was paramount to the archaeological dig, hence the road construction programme was stalled within this area, and when required, mechanical assistance was provided. The road structure in this area was then fully re-designed to accommodate the Crannog controlled excavation, and likewise completion of this new road section was delayed to accommodate the Crannog controlled dig time scale.
There were thousands of fascinating artefacts uncovered including intricately decorated dress pins, a medieval board game and the remains of dozens of flattened wooden houses. Another remarkable find from the crannog is a complete wooden paddle used in boating. A series of test pits were excavated through the peat fill surrounding the crannog, which allowed deep archaeological deposits to be viewed in sections down to the formation layer / foundation of the Crannog.
Excavation of Crannog
One especially intriguing discovery was a suspiciously buried skeleton that dates back to the 15th or 16th century. The remains belong to a female in her late teens and researchers believe she may have met an untimely end, evidenced by her damaged skull and due to the fact that she was not interred in a graveyard.
These fascinating finds led to the Crannog being publicised nationally on the television and on the radio on numerous occasions. After receiving feedback of the local interest in the Crannog, the site held three open days and supplied buses for the public to come and view the artefacts and speak to the archaeologists. The Environment Minister at the time, Alex Attwood, also visited the site.
The number of artefacts recovered from Drumclay was in excess of 4,100. Personal ornaments, crafts and every-day life are represented amongst the finds which included an iron axehead, a small stone axehead; a finger ring, a crutch-headed pin, a shaft of pin brooch, several wooden and bone pins and needles; a bone weft beater, a wooden comb for textile production, a decorated bone plaque, a fragment of a small bronze ring or hoop with decoration (possibly a band from a drinking horn), fragments of several wooden vessels including staves, unfinished staves, a lid and a decorated cup.
Securing the crannog over the Christmas period (because of the absence of personnel on-site) involved passive flooding of the excavation site. Sheets of terram were pinned, using bent re-bar, onto the crannog surface with extra-measures taken to protect particularly sensitive or fragile deposits. All tracking and walking surfaces were lifted off-site. The pumps were shut down and moved off-site thus allowing the site to flood.
Ecology & biodiversity
A full environmental assessment was undertaken for the project area prior to the project, and highlighted potential for badgers and other mammals in the area.
A full mammal survey was carried out by the contractor prior to the works to ensure that no badger sets were in the vicinity of the site. There were badger ‘set ‘checks’ prior to works in any new areas to confirm there were no badgers or other mammals in the area. The site team carried out badger and mammal tool box talks throughout the project to ensure that operatives were fully aware of the protocol upon finding a badger or set. There was also a badger pass incorporated into the project.
All tree felling was scheduled outside of the bird breeding season and left for 24 hours after felling before being removed. The site team amended the design to keep a number of trees which were originally to be felled – these were fenced off and protected during the works.
A settlement pond planting schedule was brought forward to utilise the filtering benefits of the aquatic plants. Extra trees and shrubs were planted to enhance the visual amenity of the area and to allow biodiversity to flourish.
Effects on neighbours
Due to the location of the project it was imperative to keep the neighbours informed and to ensure they were not affected by the works. The site manager called to the neighbouring houses to speak to those who were closest to the site activities and to answer any queries they may have. The site was registered with the Considerate Constructors Scheme and scored beyond compliance.
Acoustic barriers were erected earlier than scheduled in the contract to mitigate construction noise for those closest to the site. A fence was also erected for the local nursery as a goodwill gesture-, which included the installation of flower boxes.
The public were kept updated with newsletters and various community initiatives were carried out, including donating construction toys to the local nursery (picture 1), hosting site tours and speaking at career days for the St Michaels School (picture 2). The site also held ‘Women working in Construction’ site tours.
The site also took part in a STEM networking day for schools (picture 3) to educate on careers within the construction industry and to emphasise the importance of the associated subjects.
Noise and vibration monitoring was carried out at major points in the project to ensure levels were within the authorised limits. Vibration monitors were also installed at neighbouring properties in the vicinity of Excavate & Replace operations and large embankment cuts, to monitor any ground movement as a result of the works.
Toy donation to the local Burrendale Nursery school
STEM Networking day with St Comghalls School
The project incorporated 9 culvert installations, which prompted the need for extensive silt mitigation measures to be put in place during the works. Licences were sought for pumping and discharging activities with temporary SuDS measures incorporated to ensure that water quality was within the required limits.
Water sampling was carried out prior to the works to get a baseline measurement of the water quality in the area. This was supported by frequent testing carried out by the NIEA to ensure that water quality was not adversely affected.
The site carried out regular tool box talks on pollution control, including the storage of fuel and chemicals on site and managing and maintenance of SuDS features.
Due to the on-site excavation of the Crannog, a water management strategy was devised to manage groundwater as the controlled Crannog excavation went below the natural water level. Super silent pumps were also employed to mitigate nuisance to local receptors.
There were frequent environmental audits on the project to check for any construction-related issues and to offer advice on environmental improvements.
To what extent did the use of CEEQUAL influence your project?
CEEQUAL had an underlying influence on the A32 Cherrymount Project from design through to completion. Frequent visits from the CEEQUAL Assessor who was also acting as the environmental advisor, ensured that the project was executed with sympathy to the surrounding environment and that all mitigation measures were fully implemented throughout the project.
Registering sites with CEEQUAL ensures that the elements of CEEQUAL are pre-examined and that the project is designed with the assessment in mind. CEEQUAL is a driving mechanism for environmentally sensitive design.