Long Term Community Plan 2012-2022 - Hurunui District Council

Activity 1: Stormwater and Drainage
Overview
The Stormwater and Drainage activity includes the various
functions of land drainage schemes and flood protection.
Current Situation
We maintain four small land drainage schemes set up by the
former North Canterbury Catchment Board. They are the
Ashworths drains, Leithfield Outfall drain, Newcombes Road
drains and the Jed River areas.
We have only a very small quantity of stormwater pipes in
our townships, as most stormwater is disposed of to kerb and
channelling and open drains. There are approximately 100 metres
of stormwater pipe in Hanmer Springs and approximately 560
metres of pipe in Amberley. Much of the District’s stormwater
disposal systems comprise infrastructure that is maintained by
private individual property owners, such as on-site soakage
disposal, open drains/creeks, piped networks outfalls, silt traps,
and detention structures.
After two significant rainfall events in and around Amberley in
2008, we engaged a specialist consultant to review the adequacy
of our stormwater systems. The recommendations were to
carry out some major capital works to reduce the impact of
surface flooding on both Amberley Township and Amberley
Beach. The works were to include diversion drains to “behead”
the surface flows from north of Amberley to discharge them to
natural waterways outside the urban area, and realignment of
drains discharging to the lagoons north and south of Amberley
Beach.
Because of the time taken to obtain resource consents,
exacerbated by the Canterbury earthquakes and appeals lodged
against the consents granted after a lengthy hearing, only two
major physical works have been completed. These were the
flood diversion from Dock Creek along Lawcocks Road, and a
piped outfall of the Leithfiled Outfall Drain to the sea.
However with consents now finalised for three more significant
capital projects, work is expected to be completed for flood
diversion works in the Amberley swamp area (to include an
outlet culvert under Stanton Rd) and from Dry Gully across to
Mimimoto lagoon before the end of the 2011/12 year.
Plans for the future
Hurunui Community Long Term Plan 2012 - 2022
2016/17 budget for unspecified improvements. All funding is
from a special rate struck over the entire Amberley Ward.
A global consent for discharge of stormwater from the Amberley
Urban area was heard in 2011, along with the other 15 consents
for flood mitigation works described above. This was put on
hold pending as there was not enough information and a new
application will be made in the 2012/13 year.
AECOM Consultants will finalise an application in the 2012/13
year for a global consent for management of stormwater
from future residential developments in Hanmer Springs. In
anticipation of the stormwater management plan identifying some
minor capital works being required on existing infrastructure, an
allowance of $62,000 has been made in the 2013/14 year and
a further $69,000 in the 2016/17 year. As in Amberley this will
be funded by a separate rate over all properties in the Hanmer
Springs Ward.
We are proposing a new stormwater engineer to be appointed
in 2013/2014 to manage this area of our work. This engineer
will be responsible for developing district-wide stormwater
catchment and management plans, and undertake the range of
tasks required to ensure we have effective stormwater systems
in place, inclusive of appropriate maintenance regimes.
We will progressively move towards managing all of its urban
stormwater responsibilities in a more holistic, integrated and
life cycle way.
Funding
Operational Costs:
• 100% Targeted Rate based on the area benefiting
• Engineer for stormwater catchment and management
plans funded through the General Rate
Capital Costs:
• Significant Council capital expenditure is funded by a
loan as per the Council’s Internal Financing Policy
• If loans are not raised, then it will be from targeted
rates
A flood flow diversion from Eastern Drain across to the
Amberely North lagoon is proposed for the 2012/13 year to
complete the flood mitigation works covered by the 15 consents
mentioned above.
Detailed design and land ownership issues still have to be finalised,
but a preliminary estimate of $298,000 has been allowed for in
the 2012/13 budget for this work and a further $84,000 in the
• If any of the Capital Expenditure caters for future
growth of the scheme, then that portion of the
expenditure that relates to growth may be funded
from future users via Development Contributions and
Financial Contributions
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