Annual Report 2010 - Christchurch City Council

p106. Annual Report
Christchurch Otautahi
2010
Council activities and
services
Wastewater collection
and treatment
Council activities and services
Wastewater collection and treatment
What is wastewater collection and treatment and
what does the Council do?
Wastewater includes both ‘grey water’ and sewerage, collected
from household drains and sewerage pipes. It is delivered through
an underground network of pump stations and pipes to treatment
plants, where contaminants are removed prior to discharge to the
ocean.
Why does the Council provide wastewater
collection, treatment and disposal?
We collect wastewater from Christchurch homes and businesses to
protect the health of the city.
Local government is responsible for promoting the cultural,
economic, environmental and social well-being of communities for
the present and the future.
Wastewater collection and treatment activities contribute to
the environmental, economic and cultural well-being of the
community by ensuring that wastewater is collected in a reliable
and safe fashion that protects public health, and that wastewater
is treated and disposed of in an efficient and environmentally
acceptable manner.
They also contribute toward the achievement of the city’s
Community Outcomes by helping to make Christchurch a safe city,
a city of people who value and protect the natural environment and
a healthy city – three of the nine goals for our city that are included
in our Community Outcomes. This contribution is made by
providing a sanitary wastewater collection and treatment. service.
For more information on these nine goals see the Community
Outcomes section of this report.
How does it affect me?
The collection and treatment of our wastewater keeps our city
healthy and protects our environment.
What activities are included in wastewater
collection and treatment?
Wastewater collection
We provide for the continuous collection and transportation of the
city’s wastewater from properties, via an underground sewerage
network, to treatment plants – the main Christchurch plant at
Bromley, plus a number of smaller plants in Banks Peninsula.
Wastewater treatment and disposal
The city’s wastewater is processed through treatment plants before
being disposed of through outfalls to the sea and, at some small
plants, to land. An accredited laboratory monitors and controls the
treatment process to ensure that discharged treated effluent meets
health and environmental standards.
What did we achieve?
Wastewater asset renewal works progressed well over the year and
in line with the renewal programme.
The Ocean Outfall project was successfully commissioned in April
2010 and all disinfected and treated effluent is now discharged
three kilometres offshore in Pegasus Bay.
The biosolids drying project has progressed well in 2009/10 with
the project currently in the commissioning phase. Dried biosolids
from the project will be beneficially reused in land rehabilitation
projects in the South Island. The plant will be fuelled using
renewable energy sources including wood, biogas and landfill gas.
Design work for a replacement cogeneration engine at the
Christchurch Wastewater Treatment Plant commenced in 2009/10
and will be completed in 2010/11.
A six year trial associated with the conversion of algae to biofuel
commenced in late 2009. Solray Energy and NIWA are Council
partners in this study.
The sewer renewal programme was completed in line with the asset
renewal programme requirements.
The programme of removing old underground fuel tanks at the
pump stations and treatment plants was completed in 2009/10 with
the last programmed tanks being removed and replaced with above
ground vessels that meet modern environmental and engineering
codes.
Good progress was made on the major sewer upgrade project in
2009/10 with the Western Interceptor being completed as far as
Fitzgerald Avenue. The tender for the construction of the rest of
the Western Interceptor and Fendalton Duplicator were let. The
contractor commenced site works in July 2010. These are both major
sewer pipelines which are designed to reduce load on the existing
system, reducing wet weather overflows into the Avon river and
also increasing capacity to allow for growth in the South-West of
the city. Modelling and initial investigation works for pressure
Main 60 (south west of the city) and the Northern Relief trunk sewer
progressed well during the year.
Design for the Wainui wastewater scheme is complete but we
are awaiting the outcome of an appeal under the Resource
Management Act before a tender can be let and site works for the
Stage 1 works can commence.
The Akaroa Harbour working party has been looking at options for
wastewater treatment and disposal. The working party will report
to Council in late 2010.
All of these achievements have contributed towards providing a
sanitary wastewater collection and treatment service and therefore
contributed to the safety, environment and health community
outcomes.