We anticipate it will take around two years (from Dec 2022) to complete the wastewater pipes upgrade through Bothamley Park. Next year we will be able to share a revised timeline for works. If there are to be any changes to the timeline, we will keep the community updated.

When designing the wastewater pipes route we had an opportunity to make improvements that would benefit both te taiao, and the community. To achieve this specialists have done a lot of investigation work and ground testing through Bothamley Park.

We wanted to create pipes that would:

• Improve water quality in Kenepuru Stream and Te Awarua-o-Porirua Harbour by significantly reducing the amount of raw sewage overflowing into waterways
• Be built with environmentally responsible materials that will last generations
• Improve the look and feel of the park by significantly reducing (more than half) the number of places the pipe crosses the streams well as reducing the amount of manholes.
• Be more resilient in natural events i.e. earthquakes
• Improve park paths

We will replace the current mix of steel and concrete pipes with polyethylene pipes. This material has been proven to be long lasting, more resilient to earthquakes and gives greater flexibility for choosing where we can lay the new wastewater pipes.

The current wastewater pipes are 450mm in diameter/height. To ensure we invest in pipes that will not only cope with current wastewater, but also population growth in the future, the new pipes will be around 900mm diameter/height.

We are looking at upgrading the pipes through a couple of different techniques. The first is tunnelling where we use a machine to drill a hole through the soil. The second is open cut. This is where we dig a trench, lay the pipe and then fill the trench back in.

Where possible we are trying to reduce the number of visible pipes and stream crossings through the park.

To complete the pipes upgrade as safely and quickly as possible with minimal disruption to local residents and park users we will need to temporarily close portions of Bothamley Park and Champion Street.

We expect Stage 1 of the upgrade to take about 2 years then stage 2 and 3 an additional year. The work will proceed in different sections of the park through this period, so different parts of the park would need to be closed while the construction work is being undertaken in each location.

The closures were formally notified under the Reserves Act, and will be clearly signposted in advance of a particular area closing. Parkrun will be relocated to an alternative site in Plimmerton for approximately two years while the main track through the park is affected.

When it rains, stormwater gets into the pipes. When this happens, untreated sewage overflows from manholes and runs into our waterways. Untreated wastewater getting into the stream poses a risk to our health, kills fish and other life in the stream, and prevents locals from collecting healthy kai moana (seafood).

It is currently estimated that 40,000m3 of untreated wastewater overflows into Kenepuru Stream in a typical year. That’s enough to fill 16 Olympic swimming pools! As more houses are built in the area, this puts even more pressure on Bothamley Park’s wastewater pipe and results in more overflows of untreated sewage.

Investigation from a range of partners, local government and government agencies has identified three opportunities to help to fix our wastewater problems:

1. Upgrade the Bothamley Park wastewater pipes with newer, larger pipes.
   This will be installed along a similar route as existing pipes and where possible, we will lay the pipes underground, rather than across Kenepuru Stream.
2. Build a large wastewater storage tank just north of the Porirua Station carpark.
   Wastewater will overflow into this tank when there is not enough capacity in the wastewater network downstream, instead of overflowing into Kenepuru Stream. This work is currently underway and being led by Wellington Water.
3. Renew old, leaky pipes within eastern Porirua to reduce the amount of stormwater that gets into the wastewater pipe.

Together, these three improvements are designed to significantly reduce overflows of untreated sewage into waterways in eastern Porirua.  This current work is focused on the first of these opportunities – upgrading the wastewater pipes through Bothamley Park

We have been working with Porirua City Council, Ngāti Toa Rangatira and local community groups to ensure places valued by the community are protected and maintained during construction.

Specialists are looking at how we minimise noise or vibration during construction. A detailed construction plan in line with New Zealand standards and guidance has been prepared, as required by our consent. 

We will also monitor and test during construction to ensure noise and vibration are kept to a safe standard.

We will be constructing a new path on the north side of the stream opposite the Champion Street carpark, to provide an additional route through the park while the works are taking place. When the main track is closed from Champion Street carpark to the blackberry harvest area, walkers, runners and cyclists will need to divert through the streets in Cannons Creek (if they are taking through route), or use another area of the park (if they are just using the park for recreation).

Parkrun are relocating to Plimmerton while the main track is closed.

Our construction planning includes making sure that industry good practice standards are in place so that any dust or mud is minimised.  Proven techniques include lightly spraying water on site to keep any soil damp, doing work in stages to avoid disturbing large areas, and using straw or other materials.

We will have to move some large equipment, significant amounts of materials and workers to and from the construction areas.  We will prepare traffic management plans that minimise disruption and keep the community safe during construction, and these will be approved by Porirua City Council and/or Waka Kotahi, as required by our consent.

Te Rā Nui, Eastern Porirua Development is a partnership between Kāinga Ora, Porirua City Council and Ngāti Toa Rangatira. To remove and replace the wastewater pipes, Porirua Development have contracted construction and infrastructure experts Te Aranga to deliver the work. Te Aranga Alliance is a partnership of construction and infrastructure experts Higgins, Goodman, Beca, Harrison Grierson and Orogen with Kāinga Ora, Porirua City Council and Ngāti Toa Rangatira.