Ōtautahi Community Housing Trust engaged Davis Ogilvie to complete geotechnical and environmental assessments ahead of a proposed redevelopment of a community housing project in Spreydon, Otautahi, Christchurch. The former community housing had served the city for 88 years having been built in 1940 and needed replacing.
Given the age and construction type of the buildings, the potential for lead-based paints to have been used on the weatherboard exteriors and over time to have accidentally entered the soil was a potential soil contamination scenario that was to be assessed.
DO carried out a Detailed Site Investigation (DSI) which identified ground contamination, associated with lead containing paint present on buildings at the site. Arsenic and lead were detected at concentrations more than national soil contamination standards for residential land use. Isolated fragments of Asbestos Containing Material (ACM) were also identified on the surface in the southeast corner of the site associated with former shed locations and in one location on the eastern fence line.
A Remediation Action Plan (RAP) was produced by Davis Ogilvie in July 2022 and submitted to Christchurch City Council (CCC) with a consent application to complete the remedial earthworks as required by the Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011 (NESCS). Remedial works were completed on 8 September 2022 and subsequently validated by DO allowing for the site wide earthworks to commence unhindered.
The DO geotechnical engineering team carried investigations which identified a soil profile of bedded sand and silt with interspersed gravel units. Groundwater was measured at 1.7 to 2.0 meters below ground level. Seismic settlement estimates ranged from MBIE TC2/TC3 to TC3, with the site considered most consistent with an intermediate TC2/TC3 category. A hybrid TC2/TC3 foundation with a geogrid-reinforced gravel raft (minimum 0.6 m thick) and a TC2 Option 2 or 4 was deemed suitable.
Based upon the findings of DO’s geotechnical investigation, Quoin Engineers designed the building foundations, while DO assumed responsibility for construction monitoring of the gravel rafts in November 2022, marking the initial stages of construction. Over the course of this early construction phase, a total of seven inspections were conducted, which also involved supplementary testing aimed at satisfying the requirements stipulated by the Council. The geotechnical phase of this project was successfully concluded in December 2022, culminating in the issuance of a Subgrade Bearing Capacity Producer Statement (PS) 4 for each of the seven blocks involved in the project.
DO is proud to have been involved in such an important transformational community project.
Ōtautahi Community Housing Trust engaged Davis Ogilvie to complete geotechnical and environmental assessments ahead of a proposed redevelopment of a community housing project in Spreydon, Otautahi, Christchurch. The former community housing had served the city for 88 years having been built in 1940 and needed replacing.
Given the age and construction type of the buildings, the potential for lead-based paints to have been used on the weatherboard exteriors and over time to have accidentally entered the soil was a potential soil contamination scenario that was to be assessed.
DO carried out a Detailed Site Investigation (DSI) which identified ground contamination, associated with lead containing paint present on buildings at the site. Arsenic and lead were detected at concentrations more than national soil contamination standards for residential land use. Isolated fragments of Asbestos Containing Material (ACM) were also identified on the surface in the southeast corner of the site associated with former shed locations and in one location on the eastern fence line.
A Remediation Action Plan (RAP) was produced by Davis Ogilvie in July 2022 and submitted to Christchurch City Council (CCC) with a consent application to complete the remedial earthworks as required by the Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011 (NESCS). Remedial works were completed on 8 September 2022 and subsequently validated by DO allowing for the site wide earthworks to commence unhindered.
The DO geotechnical engineering team carried investigations which identified a soil profile of bedded sand and silt with interspersed gravel units. Groundwater was measured at 1.7 to 2.0 meters below ground level. Seismic settlement estimates ranged from MBIE TC2/TC3 to TC3, with the site considered most consistent with an intermediate TC2/TC3 category. A hybrid TC2/TC3 foundation with a geogrid-reinforced gravel raft (minimum 0.6 m thick) and a TC2 Option 2 or 4 was deemed suitable.
Based upon the findings of DO’s geotechnical investigation, Quoin Engineers designed the building foundations, while DO assumed responsibility for construction monitoring of the gravel rafts in November 2022, marking the initial stages of construction. Over the course of this early construction phase, a total of seven inspections were conducted, which also involved supplementary testing aimed at satisfying the requirements stipulated by the Council. The geotechnical phase of this project was successfully concluded in December 2022, culminating in the issuance of a Subgrade Bearing Capacity Producer Statement (PS) 4 for each of the seven blocks involved in the project.
DO is proud to have been involved in such an important transformational community project.
