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Bothamley Park Trunk Sewer Upgrade
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Harrison Grierson successfully led the Covid Fast-Track consent application for the trunk sewer upgrade, as well as surveying and landscape design at Bothamley Park, paving the way for new Kāinga Ora homes in Eastern Porirua.
The new trunk sewer is expected to prevent 40,000m³ of raw sewage from overflowing into nearby streams and Te Awarua-o-Porirua (Porirua Harbour) each year.
The construction of the trunk sewer in Bothamley Park was a technical challenge.
Multiple existing sewer pipe crossings over Kenepuru Stream were removed and replaced with multiple crossings under the stream bed
Large areas of old pine trees throughout the Park were required to be removed to improve safety for park users
Areas of the streambank required additional protection using rip rap (layers of stone) to reduce erosion that had undermined the access track throughout the park
A combination of construction techniques was used to lay the trunk sewer in the park, including open trenching, horizontal directional drilling (HDD) and pipe ramming under the Porirua Interchange of State Highway 59
As part of the Te Aranga Alliance, HG provided:
Planning services that involved preparation and obtaining consents under a range of legislation, including the Covid Fast Track, Resource Management, Reserve, Conservation and Wildlife Acts
Surveying services to set out the position of the sewer and assist with the preparation of as-built plans
Landscape architecture services involving detailed landscape design and implementation of remediation planting throughout the Park, preparing revegetation management plans to satisfy vegetation offset requirements and ecological mitigation
Mana whenua (Ngāti Toa) and council consultation and collaboration
Community engagement and involvement
Structural services involving bridge inspections
Project management
We received a ‘’Promoter’’ Beaton score from the team at Kāinga Ora, who said ‘’the work Harrison Grierson did on the BP Wastewater Project was exceptional. Predominantly, the planning team led by Poul Israelson, who provided such a comprehensive, all-encompassing management of the planning process to get it approved via the Fast Track Consenting Process, which was new legislation.’’
Photograph 1: The trunk sewer pipe is being pulled into a tunnel created by the drill rig and HDD
Photograph 2: Section of Kenepuru Stream temporarily dry to enable the installation of sewer casing and rip rap protection of the stream bank
Photograph 3: New permanent piped stream crossing, piped through a steel casing under the stream bed, before being covered with rip-rap
Photographs 4 and 5: Erosion protection installed on Kenepuru Stream bank to protect public access