HE1851 B4069 Lyneham Banks Repair Wiltshire Council April 2024

Description

B4069 Lyneham Banks Repairs In 2022 significant a significant landslip took place on the B4069 Lyneham in North Wiltshire. The resulting landslip dislodged around 90m of the existing carriageway downslope. The B4069 has been closed since February 2022 when the landslip took place, movements continued throughout the first part of 2022 until slowing significantly during the summer months. The B4069 is a regionally important route providing connectivity between junction 17 of the M4 and North Wiltshire as well as serving several local communities. The road when opened normally takes around 5500 vehicles a day. Following extensive ground investigations towards the end of 2022 and a concentrated design effort during 2023 Wiltshire Council are now seeking to procure a contract to re-construct the B4069 under a traditional NEC4 delivery model. It is proposed to stabilise the slope with a contiguous piled embedded retaining wall with capping and upstand at the top. The proposed structure will be constructed on the northern side of the B4069 with a length of approximately 90 m. A in-situ reinforced concrete (RC) capping beam will be supported on a single row of 600 mm diameter bored concrete piles. The in-situ capping beam will be 1000 mm wide and 1000 mm deep structurally connected with the piles. The capping beam will be connected to tension micropiles to provide additional lateral ground support to the retaining wall. A vertical infill parapet or edge restraint is also considered to be provided at this location. The new parapet may be installed in the verge or attached directly to the capping beam at the back of the verge. Highway works will include reinstatement of the carriageway, pavement, drainage, and kerbs. To provide improvement to the existing highway drainage system, it is proposed that the highway shall be drained by a combination of gullies, carrier/ collector pipes and catchpits. The proposed highway drainage will outfall to a watercourse north of the B4069 via a new culvert. To ensure effective drainage of the site a number of land drainage measures will also be put in place on 3rd party land either side of the B4069. The works will be designed and built in accordance with current standards and guidelines, and will include for all key aspects of highway construction – piling, earthworks, carriageway, drainage, signage, and hard and soft landscaping works. The works will be delivered primarily within the existing highway boundary extents, however there will be a need to install drainage within adjacent fields currently owned by 3rd party landowners. Wiltshire Council are currently working on obtaining the necessary agreements and access the land. Further general information regarding the background to the project and its current status can be found at the following web link:- https://www.wiltshire.gov.uk/article/6085/B4069-Lyneham-Banks Wiltshire Council intent to hold a Market Engagement webinar on Thursday 14th December 2023 at 11:00AM via Microsoft Teams. The purpose of the event will be to inform the market of the current developing scheme proposals. Any suppliers interested in attending should express an interest via email to jack.francis@wiltshire.gov.uk and they will receive further information regarding the event details. Should you be interested in attending the event please express your interest by emailing names, roles and contact details to the abovementioned e-mail address by no later than 12:00 Noon on Monday 11th December 2023. This notice is not a call for competition. Contractors expressing interest in attending the event should note that it would be necessary to respond separately to any contract notice in due course. Lot 1: B4069 Lyneham Banks Repairs In 2022 significant a significant landslip took place on the B4069 Lyneham in North Wiltshire. The resulting landslip dislodged around 90m of the existing carriageway downslope. The B4069 has been closed since February 2022 when the landslip took place, movements continued throughout the first part of 2022 until slowing significantly during the summer months. The B4069 is a regionally important route providing connectivity between junction 17 of the M4 and North Wiltshire as well as serving several local communities. The road when opened normally takes around 5500 vehicles a day. Following extensive ground investigations towards the end of 2022 and a concentrated design effort during 2023 Wiltshire Council are now seeking to procure a contract to re-construct the B4069 under a traditional NEC4 delivery model. It is proposed to stabilise the slope with a contiguous piled embedded retaining wall with capping and upstand at the top. The proposed structure will be constructed on the northern side of the B4069 with a length of approximately 90 m. A in-situ reinforced concrete (RC) capping beam will be supported on a single row of 600 mm diameter bored concrete piles. The in-situ capping beam will be 1000 mm wide and 1000 mm deep structurally connected with the piles. The capping beam will be connected to tension micropiles to provide additional lateral ground support to the retaining wall. A vertical infill parapet or edge restraint is also considered to be provided at this location. The new parapet may be installed in the verge or attached directly to the capping beam at the back of the verge. Highway works will include reinstatement of the carriageway, pavement, drainage, and kerbs. To provide improvement to the existing highway drainage system, it is proposed that the highway shall be drained by a combination of gullies, carrier/ collector pipes and catchpits. The proposed highway drainage will outfall to a watercourse north of the B4069 via a new culvert. To ensure effective drainage of the site a number of land drainage measures will also be put in place on 3rd party land either side of the B4069. The works will be designed and built in accordance with current standards and guidelines, and will include for all key aspects of highway construction – piling, earthworks, carriageway, drainage, signage, and hard and soft landscaping works. The works will be delivered primarily within the existing highway boundary extents, however there will be a need to install drainage within adjacent fields currently owned by 3rd party landowners. Wiltshire Council are currently working on obtaining the necessary agreements and access the land. Further general information regarding the background to the project and its current status can be found at the following web link:- https://www.wiltshire.gov.uk/article/6085/B4069-Lyneham-Banks Wiltshire Council intent to hold a Market Engagement webinar on Thursday 14th December 2023 at 11:00AM via Microsoft Teams. The purpose of the event will be to inform the market of the current developing scheme proposals. Any suppliers interested in attending should express an interest via email to jack.francis@wiltshire.gov.uk and they will receive further information regarding the event details. Should you be interested in attending the event please express your interest by emailing names, roles and contact details to the abovementioned e-mail address by no later than 12:00 Noon on Monday 11th December 2023. This notice is not a call for competition. Contractors expressing interest in attending the event should note that it would be necessary to respond separately to any contract notice in due course.