Otama-ngenge Integrated Catchment Management Plan WHAT IT MEANS FOR YOU.
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Transcript of Otama-ngenge Integrated Catchment Management Plan WHAT IT MEANS FOR YOU.
Otama-ngenge Integrated Catchment Management Plan WHAT IT MEANS
FOR YOU
RECAP – An ICMP does what….
1. Provides guidance on how growth will be accommodated
2. Ensures LOS are not compromised 3. Allows stormwater discharges to meet
conditions of the CSDC 4. Helps HCC to control the effects of landuse
within city boundaries and on adjacent territories.
This ICMP
Catchment Values and Further Technical Investigations
Catchment Objectives
Best Practicable Options that will meet Catchment Objectives
Design Parameters that will meet Objectives
Methods of Compliance to achieve design parameters and BPO’s
Who will use this document and how?Key users How
HCC – Development Engineers • Assessing WIA• Assessing consent applications• Assessing engineering design
proposals• Formulating consent conditions
HCC - • Building consent
assessment officers• Building review officers• Building inspectors
• Approving building consent applications
• Assessing building design proposals
• Formulating consent conditions
HCC Asset owners Program of works
Key users How
WRC • Assessing stormwater and earthwork consent applications (full catchment)
• Assessing engineering design proposals• Requiring further information• Formulating consent conditions
WDC • Assessing consent applications (within WDC area)
• Assessing engineering design proposals• Requiring further information• Formulating consent conditions
Landowners, interested parties, Compliance Teams
• Information about catchment and future works
A Bit of Background
• means “of being tired and sapping the youth of one’s strength”,
• General and Medium Density Residential • 822 ha, 91ha (11%) within HCC boundaries • Stream 3.2 km long with significant branches • Northern branch in the Horsham Downs area - 3.8 km • Traditional land holdings of Ngati Wairere. • native trees, berries and native birds - Te Totara• Kai - native birds, cultivation, tuna (Eels), fresh water
mussel beds, Inanga (white bait) collection points, Kokowai (ochre) deposits highly prized for adornment for carvings.
Erosion issues • Small and sensitive waterways • Existing active bank failure• North branch have limited flow capacity. • High Risk that stormwater flows will erode the
sandy sediment and cause bank slumping • Remedial works are required to reverse these effects
and reinstate the aquatic habitat.• Erosion observed near the Otama-ngenge Stream
confluence with Waikato River at River Road.
Stream capacity• Assessed flow in the 2 year, 10 year and 100 year 24 hour
event • Assessed existing culvert capacity at public road crossings• Increased volume - potential to destabilise stream banks
and beds. • No predicted bank overtopping in the predevelopment or
postdevelopment scenario.• Predicted surcharging • Water levels in the 10 year and 100 year events are not
predicted to overtop banks therefore LOS to avoid more than 3 days ponding in the 10 year event for rural channels is met.
• Geotechnical assessment needed to determine land stability issues.
Flood potential
• 5-10% to of 50-60% imperviousness • Low lying central regions currently subject to
surface flooding following prolonged periods of rainfall.
• Flat terrain limits the ability for stormwater to drain away via overland flow paths
• Peaty soils and high groundwater tables
Ecology• Poor riparian habitat, • Poor or moderate aquatic habitat values• Moderate water quality• Good sediment quality (with localised contamination) • Low native fish diversity (fish passage issues and poor
habitat)• BUT threatened giant kokopu and shortfin eel• Potential for long fin and mudfish • Stream vulnerable to contaminants and heated
stormwater. • Streams vulnerable to sediment
• Need densely planted wetland and sediment control• Need fish surveys of drains along the road alignments. • Road design and construction measures for the Waikato
Expressway and Resolution Drive Extension will need to ensure continued fish passage between upstream and downstream fish habitat for all native fish species present
• Replacement of removed habitat with equivalent or enhanced habitats.
• Fish translocation to adjacent habitats and habitat enhancement may be necessary to mitigate the impacts of road construction and stormwater discharges on habitats of ecological significance.
Water Quality and Contaminants• Storage of pesticides, herbicides, and fertilisers,
fuel bowsers and oil tanks, and sheep dips. • Contamination low in terms of risk to people and
the environment. • Site specific investigation and potential testing
required • Contaminant modelling showed that if measures
prescribed in Methods of Compliance are applied, inputs of suspended sediment, nutrients, metals and pathogens contaminants could meet required design parameters.
Overland flow• Designated overland flow paths need to be
incorporated into the design and layout of subdivisions.
• Overland flow paths to convey flows in excess of the design storm, up to and including the 100 year ARI event.
• Roadways to form these secondary flow paths as far as possible.
• Any overland flow paths required over private land need to be formally recognized and protected as part of the consenting and construction processes.
Land drainage
• Catchment in Kirikiriroa Horsham Downs drainage area - Primary purpose to manage the water table.
• Secondary purpose to drain ponded surface water from the 10 year event within three days.
• Potential impacts of development include capacity, bank and channel instability
• WRC collects rates for maintenance on selected sections of watercourse.
• Potential for O&M costs to increase
Water SupplyWater capacity• Meadows development - limit in place until the trunk water main in
Meadowfield Street connects with the future 250mm water main in Borman Road.
• New Rototuna reservoir and associated bulk mains not in until 2018
Water allocation and pressure• Predicted drop in water pressure, particularly in the elevated sections
of the developing catchment. • Pressures predicted to meet HCC LOS requirements • A small area of properties on a restricted supply can not be permitted
to have a pressurised water connection until Reservoir built • Water Impact Assessments required by the Proposed District Plan will
need to investigate issues associated with significant new developments.
Wastewater issues
• We are sweet here
• Just make sure that …Collection and distribution networks generally emulate the existing city network in order to maximise commonality and efficient maintenance (i.e. conventional gravity sewers).
Three Waters Management Hierarchy
Minimise Demand Reuse Treat & Dispose to Ground Treatment & Detention Reticulation
Catchment Limits Parameter Requirement All sub catchments (except for catchments going to TAOK)1 Extended
detention24mm, 24 hours for greenfields development
2 Contaminants Treatment Device Performance (contaminant removal on a long term average basis):a) Suspended solids: > 75%b) Other contaminants (metals, TPH/PAH, TN and TP): to achieve maximum
potential removal rates
Receiving Environment (after reasonable mixing)c) Dissolved oxygen: > 80% saturationd) Turbidity: < 25 NTUe) Colour/visual clarity: no conspicuous change in colour or visual clarity
3 Temperature <23° Celsius at the point of discharge to a waterway and water temperature increase of no more than 3° Celsius
4 Attenuation and Flood Control
a) 2 and 10 year post-development flow attenuated to respective 2 and 10 year pre-development flow.
b) 100 year post development flow attenuated to 80% of pre-development flow.
5 Land drainage Level Of Service
a) In a 10 year storm, ponding of stormwater on adjacent farmland shall not exceed 3 days on farmland serviced by a WRC land drainage network.
b) mean depth of shallow groundwater on farmland serviced by land drainage network not increased as a result of increased stormwater discharge volumes.
Sub catchments in Otama-ngenge hydrological catchment with piped drainage and/or overland flows to Te Awa O Katapaki Stream
6 All parameters
Refer to HCC for expected or preferred parameters, BPOs and Compliance methods to apply in Te Awa O Katapaki catchment.
Parameter Requirement5 Land drainage Level Of
Servicea) In a 10 year storm, ponding of stormwater on adjacent farmland shall not
exceed 3 days on farmland serviced by a WRC land drainage network.b) mean depth of shallow groundwater on farmland serviced by land drainage
network not increased as a result of increased stormwater discharge volumes.
BPO’s• Developer must prove any non-ICMP option is the most
appropriate and will meet the ICMP objectives. • Design report should include, but not necessarily be limited
to Information Requirements provided in Appendix F (PDP). • Note: may form the basis of a Water Impact Assessment as
required under the District Plan.• Unless specifically superseded by ICMP, all development
design is to be in accordance with the HCC ITS; • Development design must specifically consider cumulative
environmental and infrastructure effects; and• Development design must provide for long-term
management of effects that encompasses the entire area over which potential effects may occur.
Methods to Achieve Compliance• Where there is an approved Water Impact Assessment
(WIA) that recommends specific on-lot water efficiency measures, use the WIA.
• Where compliance methods are not practical, reference to be made to the relevant authority, (and HCC ITS) for alternative solutions which are acceptable to HCC.
• Developers to have joint pre-application meetings with HCC, and WRC and, if required, WDC to facilitate alignment
• Information prepared in accordance with PDP 25.13.4.6
Ref
Solution / Requirement Assessment Timing
ON LOT REQUIREMENTS
WATER EFFICIENCY MEASURES (on lot within Hamilton City boundary)
1 Low flow fixtures are installed in accordance with Rule 25.13.4.5a and c of the PDP.
HCC Building Consent
2 On lot water efficiency measures incorporated, connected to, achieved or maintained in accordance with Rule 25.13.4.5a of the PDP, and as detailed within Three Waters Management Practice NotesTo comply with this rule select at least one of the following options.The preferred option for this catchment to meet water efficiency measures for water type Stormwater is: Rainwater reuse tanks (where this is used it shall be plumbed back into the toilet and laundry with an option for garden use).However other equivalent features that may be selected that are suitable for this catchment are:1. Soakage (entire lot if deemed suitable during the subdivision).2. Permeable Surfaces3. Bioretention/raingardens4. Detention (note - least preferred option and particularly in sub-
catchment A - centralised device provides significant attenuation) Other on lot practices that are encouraged: Proper building and landscape design
HCC Building Consent
And where relevant WIA (required by HCC)
Stormwater - continued STORMWATER ON LOT – All Sub Catchments in Hamilton City
3 On lot soakage if feasible as per the requirements of Stormwater BPO 3 and the HCC ITS.
At time of HCC Resource Consent (a piped connection will not be provided if adequate soakage is available).
4 Site specific comprehensive treatment systems will be required for high risk sites as per Stormwater BPO 4.
Building and/or HCC Resource Consent (Pollution Plans required in accordance with HCC Stormwater Bylaw)Compliance Teams
STORMWATER ON LOT – All Sub Catchments If certain areas of a development cannot discharge
to a centralised device, at-source devices will be required to meet the discharge parameters. Strong justification as to why a centralised device cannot serve the lot will be required. Within Hamilton City Boundary, this applies to subcatcment C. Technical certification from WRC may be required in accordance with condition 3 of the CSDC.
At time of HCC Resource Consent (a piped connection will not be provided if adequate soakage is available). Assessment may be provided to WRC in accordance with HCC CSDC.Compliance Teams
STORMWATER CENTRALISED DEVICES AND PRACTICES – all subcatchments
6 Centralised devices to be located and sized to ensure suitable flows and minimised operation and maintenance costs Wetlands to be densely planted with >80% plant cover. Operations and maintenance plans shall be provided to: ensure that stormwater management devices provide best practicable
stormwater management efficiency at all times show how the developer will undertake the monitoring plan
components relevant to device performance (to be compliant before vesting to HCC and during defects liability)
Within wetlands, the management of gross pollutants can be achieved through the installation of inlet or outlet screening
At time of Resource Consents(HCC and WRC)DE’s, WRC Consent Officer
Resource Consents (HCC and WRC)DE’s, WRC Consent Officer
7 Overland flow path to be provided for 100 year ARI event in road or reserve Secure by an appropriate legal mechanism to the satisfaction of the regulatory authority.Adequate freeboard to be provided to all buildings as detailed in the ITS.
At time of Resource Consent
(HCC ) – DE’s
8 Suitable energy dissipation and erosion protection measures shall be provided at all discharge locations, with preference for natural solutions or green engineering appropriate to the soft sediment environment over hard engineering solutions using rock and concrete.
At time of Resource Consents
(WRC)WRC Consent Officer
9 Modified and natural stream channels and their riparian margins shall not to be used as locations for stormwater treatment devices. However, in the upper catchment, the modification of artificial drains to create stormwater treatment wetlands and detention basins is encouraged rather than device creation in farmland, provided that flood flows and fish passage are incorporated into the design as appropriate.
At time of Resource Consents
(HCC, WRC, WDC)
10 Existing riparian vegetation retained any new riparian planting done with indigenous eco-sourced vegetationA minimum of 5m wide riparian planting either side of all waterbodies, streams and drains with stock proofing is encouraged.
At time of Resource Consents
(HCC, WRC, WDC)
11 Application of sediment control measures to protect stormwater devices, Otama-ngenge stream and its tributaries. Translocation and/or fish passage to upstream habitats where native fish are present. Developers may be asked to establish presence of native fish that could potentially be affected by proposed construction.Discovery of artefacts in watercourses -notify appropriate iwi representatives and authorities
At time of Resource Consent
(HCC, WRC, WDC)Sediment – compliance teams under SW bylaw
12 Where it is identified that stormwater discharges will have an effect on aquatic habitat and water quality values, then habitat enhancement shall be included as a mitigation measure via riparian planting and/or stream works as appropriate.Particularly relevant to Major Roading Projects, which will require downstream investigation and potential mitigation works.
At time of Resource Consent
(HCC, WRC, WDC)
STORMWATER – Sub Catchments with piped network to Te Awa O Katapaki
13 Refer to HCC for expected or preferred parameters, BPOs and Compliance methods to apply in Te Awa O Katapaki catchment.
At time of Resource Consent(HCC) - DE
STORMWATER – Otama-ngenge: Major Roading Projects
14 Swales, wetlands and approved at source devices capable of removal of hydrocarbons.To be densely planted with >80% plant cover and open water areas are to be avoided.Road corridor projects shall be designed to ensure drain replacement devices maintain waterway connectivity and provide surface flow to maintain base flows in the Otoma-ngenge Stream.
At time of Resource Consent (HCC, WRC, WDC)
15
Fish surveys shall be carried out in waterways - Waikato Expressway and Resolution Drive Extension.
Avoid, remedy or mitigate adverse effects on fish habitat - providing for fish passage between habitat upstream and downstream of the road corridors replacing removed habitat with equivalent or enhanced habitats.
At time of Resource Consent
(HCC, WRC, WDC)
WASTEWATER (within Hamilton City boundary) 16 Wastewater in all subcatchments shall be served
by the wastewater pump (in the vicinity of Borman Rd/Hare Puke Drive). Gravity mains to access the pump shall be extended as development occurs and capacity shall be assessed during the engineering phase for suitability to serve the surrounding areas draining to the pump. Levels of service to be achieved in accordance with HCC’s requirements.Best practice design, construction and inspection are required to ensure that inflow and infiltration is minimised.
Resource Consent (HCC)
WATER (within Hamilton City boundary) 16 Strategic 250mm water mains required in specified
locations as per Water Master Plan and indicated on shown in Appendix B Water Supply Network Map B3 (or any updates).
Levels of service to be achieved in accordance with HCC’s requirements.
Minimum pressure and flows to be achieved, including consideration of adverse effects on the existing built and consented environment. Water Impact Assessments for elevated sites shall specifically address predicted Level Of Service prior to Rototuna Reservoir being operational,
Those sites shown on the appendix B water network map predicted to fall below HCC Level of Service shall not be permitted to have a pressurised water connection until the completion of the Rototuna Reservoir unless it is demonstrated that Level Of Service can be provided.
Resource Consent (HCC)
What this means for YouWho What
DE Have joint application meetings with WRCEnsure that consent applications and engineering proposals align with ICMP Methods of Compliance or WIAEnsure that conditions reflect the achievement of design parametersInitiate Vestment process through Vestment Team approachEnsure water connections are only initiated if LOS can be met
WRC Have joint application meetings with HCC and/or WDCEnsure that consent applications and engineering proposals align with ICMP Methods of Compliance Ensure that conditions reflect the achievement of design parametersCheck that O&M is being carried out on devices by consent ownerEnsure HCC, as future asset owner, is satisfied with approval processesCheck that monitoring results for devices are being reported by consent ownerEducate, monitor and enforce sediment control for major earthworks
HCC compliance team
Educate, monitor and enforce sediment control at building sitesResource and Initiate Monitoring Plan requirementsIncorporate area into Education Strategy
Who What
Asset team Provide resources for Vestment process through Vestment Team approachSchedule O&M for HCC owned devices after vestmentInitiate investigations required under Future Actions
Building Consent
Require building proposals align with WIAEnsure that consent applications and engineering proposals align with ICMP Methods of Compliance (including Water sensitive devices, freeboard requirements and overland flow formalisation)Ensure that conditions reflect the achievement of design parametersRequire sediment control at building sites
POS Assist with Vestment process for centralized devices (planting process)Assist with advice on riparian planting (may include planting plan)
CTU Roading design to align with ICMP
WDC Assist with landowner liaison communications in downstream areas.Assist with advice on riparian plantingLook for opportunities to remediate fish passage issuesAcknowledge potential for further erosion at river confluence (not assoicated with HCC discharge)
What next?
• ICMP approval for adoption by PGG and SLT – 5th October
• ICMP – website/s• Geotech investigations• Riparian works• O&M cost investigations• Stormwater education• Monitoring Plan – next summer• Getting ICMP onto website • Meeting with DE’s and PGU
Other ICMPs coming up in the next 12 months:
• Te Awa O Katapaki• Mangakotukutuku• Lake Rotokauri• Mangaheka
Further queries and Otama-ngengne catchment information needs to go to:
• Rae Simpson – City Waters• Andrea Philips– City Development
TRIM link: to be advised
THANKS FOR YOUR TIMEHAPPY IMPLEMENTATION
