At the close of
the agenda no apologies had been received.
2 Leave
of absence
At the close of
the agenda no requests for leave of absence had been received.
3 Conflict
of Interest
Committee
Members are reminded of the need to be vigilant to stand aside from
decision-making when a conflict arises between their role as a member and any
private or other external interest they might have.
4 Public Forum
Notification to
speak is required by 5pm at least two days before the meeting. Further
information is available on www.southlanddc.govt.nz
or phoning 0800 732 732.
5 Extraordinary/Urgent
Items
To consider, and if
thought fit, to pass a resolution to permit the committee
to consider any further items which do not appear on
the Agenda of this meeting and/or the meeting to be held with the public
excluded.
Such resolution is
required to be made pursuant to Section 46A(7) of the Local Government Official
Information and Meetings Act 1987, and the Chairperson must advise:
(i) the
reason why the item was not on the Agenda, and
(ii) the
reason why the discussion of this item cannot be delayed until a subsequent
meeting.
Section 46A(7A) of the Local Government Official Information and Meetings
Act 1987 (as amended) states:
“Where an item
is not on the agenda for a meeting,-
(a)
that item may be discussed at that meeting if-
(i) that
item is a minor matter relating to the general business of the local authority;
and
(ii) the
presiding member explains at the beginning of the meeting, at a time when it is
open to the public, that the item will be discussed at the meeting; but
(b)
no resolution, decision or recommendation may be made in
respect of that item except to refer that item to a subsequent meeting of the
local authority for further discussion.”
6 Confirmation
of Minutes
5.1 There are no minutes to confirm at this
meeting.
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Extraordinary
Executive Committee
12 September
2016
|
|
Emergency
Stormwater Drain Renewal - Riverton
Record No: R/16/9/14846
Author: Ian
Marshall, Group Manager Services and Assets
Approved by: Steve Ruru,
Chief Executive
☒
Decision ☐
Recommendation ☐
Information
Purpose
1 To
seek approval to carry out emergency repairs to a stormwater drain in Jetty
Street, Riverton.
Executive
Summary
2 The
report describes a failure that has occurred in the stormwater drain in Jetty
Street, Riverton.
3 The
drain is a major stormwater outfall for a large area of Riverton. It
appears to be totally blocked. The repair is at the outfall end of the pipe
where it discharges into the estuary. The repairs can only be carried out
cost effectively by timing the work to coincide with spring low tides.
4 The
cost of the repair project is estimated to be $59,900. The project will
be funded from the Riverton Stormwater Reserve which has a balance of
approximately $309,000.
5 The
Chairman and members of the Riverton Community Board inspected the site with
the Council’s engineers on Friday (9th September) and agreed
the work should go ahead as soon as it can be done.
|
Recommendation
That the Executive
Committee:
a) Receives
the report titled “Emergency Stormwater Drain Renewal - Riverton”
dated 12 September 2016.
b) Determines
that this matter or decision be recognised as not significant
in terms of Section 76 of the Local Government Act 2002.
c) Determines
that it has complied with the decision-making provisions of the Local
Government Act 2002 to the extent necessary in relation to this decision; and
in accordance with Section 79 of the Act determines that it does not require
further information, further assessment of options or further analysis of
costs and benefits or advantages and disadvantages prior to making a decision
on this matter.
d) Approve
the work and a project budget of $59,900 (excluding GST) for the project to
make emergency repairs to the Jetty Street, Riverton stormwater pipeline and
that the work be funded from the Riverton Stormwater Reserve.
|
Content
Background
6 There
has been a failure of the 450mm stormwater main near the Riverton Butchery
(former Riverton Fishermens Co-op) wharf. This main is a critical part of the
stormwater system that provides drainage for most of Riverton on the north side
of the bridge, including the main street business area.
7 The
Community Engineer Greg Erskine, approached the water & waste department to
provide assistance in developing a solution to the problem.
8 The
location of the failure is in potentially difficult ground conditions of
reclaimed land in a tidal area.
Investigation & proposal
9 A
section of pipe has collapsed which resulted in a hole appearing in the surface
beside the carpark and it appears that the pipe is completely filled with
gravel with the stormwater only able to drain through the voids in the gravel (the
green line near the boat on the aerial photo below).
10 We
identified through CCTV investigation that instead of the main being concrete
(as we initially thought due to the last few lengths at the outfall being
concrete) with rusted reinforcing the cause of the collapsing, the main is
earthenware and the majority of the main appears to be in good condition.
11 So
instead of replacing the entire 94m of main by pipe bursting which was
originally thought necessary at an estimated cost of $100,000, it is proposed
to replace approximately a 30m section of the 450mm stormwater main near the
Riverton Butchery (former Riverton Fishermens Co-op) wharf at 7 Jetty St with
450mm SN16 polypropylene pipe.
Issues
Risks
12 The
greatest risk involved is property damage due to flooding which is difficult to
quantify given the patchy knowledge that we have of the Riverton stormwater
network. It stands to reason that the capacity is significantly reduced with a
corresponding risk of flooding in a significant rainfall event of even less
than the current expected level of service. Logic suggests that the areas
immediately above the collapse would be the most affected. A rudimentary
preliminary concept plan of the existing drainage system that was undertaken by
e2 solutions in 2009 indicates that the area’s most at risk are Jetty
Street and both Palmerston Street and Havelock Street south of Princes Street.
13 Potentially
it would only take something like a plastic bag to come down the line to
completely block drainage and cause flooding even with minimum base flows.
14 From
the CCTV investigation that has been done it appears that any attempt to clear
the pipe would cause further collapse of pipes and development of a hole that
would grow rapidly and threaten damage to the nearby building. The existing
pipes within the work area are in such poor condition that they could possibly
also be continuing to deteriorate which could result in similar damage.
Factors to Consider
Legal
and Statutory Requirements
15 The
proposed work has been discussed with Environment Southland they confirm that
the proposed emergency works are able to be undertaken as a permitted activity
under the rules of their Regional Coastal Plan for Southland.
Community
Views
16 Discussions
have been held with Riverton Butchery management about how the work will be
undertaken and how we’ll minimise the impact on their business.
This business has been affected by the hole (which has been temporarily filled)
and the gates that remain in place. Their preference is for the work to be done
sooner than later.
17 Onsite
discussions have been held with the Riverton Community Board Chairman and Board
members. Officers will endeavour to contact the wharf berth owners to inform
them of the work.
18 The
views of the Community Board members is considered a representation of the
community’s views on this issue.
Costs
19 Prices
were requested from several suitable contractors to undertake emergency repair
works. Prices were sought from 9 contractors with suitable experience and capability
to undertake the Emergency Repair Works. We received prices from Bond
Contracts, Fulton Hogan and Te Anau Earthworks. Reasons given by those that
declined to price the work included the difficulty of the job and
unavailability due to current workload.
20 Te
Anau Earthworks was the lowest tenderer and have provided a methodology that
minimises the risk of passing near the southwest corner of the Butchery
building whilst working in potentially unstable reclaimed land in a tidal zone
by constructing a new outfall through the existing retaining wall approximately
6m west of the existing outfall and laying pipes on a new alignment back to
where they will then join upto the existing pipeline with a new manhole. They
will then fill the remaining pipe and plug the existing outlet with concrete.
21 Officers
recommend acceptance of the Te Anau Earthworks scheduled price of $39,403,
excluding pipes.
22 The
cost of the pipes that have been arranged is $5,380 from Hynds.
23 An
additional contingency sum of $15,000 has also been allowed to provide for
risks associated with the site consisting of potentially contaminated ground
from the old diesel tank that was previously removed from nearby and the
unknown nature of the fill which could consist of large boulders or car bodies
which could result in additional excavation, disposal & fill costs.
24 Investigation,
design, tender & project supervision $3,000.
25 Total
Estimated project Cost $59,900
Funding
26 The
Riverton/Aparima Community Board has approximately $309,000 (as at June 2016)
in the Riverton General – OPR Reserve Account available to pay for this
work.
27 Alternatively,
should the Board wish to fund the works through a loan the finance department has
calculated the repayments for a 5 year or a 10 year loan at the current
interest rate of 5.72%.
28 A
5 year loan will come at a total cost of $70,559.50 at a cost of $14,112 per
annum which works out as a 3.1% increase for the current rateable base.
29 10
year loan will come at a total cost of $80,308.70 at a cost of $8,031 per annum
which works out as a 1.77% increase for the current rateable base.
Policy
Implications
30 There
are no policy implications.
Analysis
Options Considered
31 The
options are to do this work at the first available opportunity as dictated by
spring low tides. These will occur on 17/18 September.
32 Another
option is to seek formal approval from a meeting of the Riverton Community
Board and then seek approval from the full Council meeting on the 28th
of September. The next opportunity to do the work after that would be the
middle of October. If not then it would be the middle of November.
33 The
other option is to do nothing.
Analysis of Options
Option
1 – Seek approval from the Executive Committee under emergency provisions
to carry out the work in mid-September.
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Advantages
|
Disadvantages
|
|
· This
will allow the works to be carried out as soon as possible.
· This
option provides the lowest risk that a rain event will occur and the
potential for private property to be flooded before the repairs are made.
|
· An
extraordinary meeting of the Executive Committee is required
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Option
2 – Wait for approval from the Riverton Community Board and the Council
|
Advantages
|
Disadvantages
|
|
· Formal
approval of the Community Board and Council can be sought.
|
· Construction
will be delayed for one or two months
· The
risk of private property flooding is much greater.
|
Option
3 – Do nothing
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Advantages
|
Disadvantages
|
|
· No
capital costs incurred
|
· Private
property flooding is almost a certainty, it is only a matter of when and how
much.
· The
repair cost latter could be much greater because of consequential damage.
|
Assessment of Significance
34 A
decision in accordance with the recommendation is not considered significant.
Recommended
Option
35 Given
the risk of flooding that could occur during a heavy rain event due to the
significantly restricted capacity of the collapsed pipe, officers recommend
that the proposed emergency repair work as outlined above, be approved
immediately to allow it to be undertaken ASAP.
36 Te
Anau Earthworks has indicated that they are willing to begin the work around
the next suitable spring low tides on 17/18 of September.
37 Urgent
action is recommended otherwise the work will have to be delayed until the next
suitable tides which will be mid-October or November.
Next
Steps
38 If
approved by the Executive Committee the work will be carried out on the 17/18th
of September 2016.
Attachments
There are no attachments for
this report.
