Attachment 1. Updated Infrastructure Assessment Report

Transcription

1 Attachment 1 Updated Infrastructure Assessment Report

2 Infrastructure Assessment Report Prepared for Bloom St Georges Limited 21 Swanson Road, Henderson,, Auckland Prepared by Terra Group NZ Ltd. June 2016 PROJECT MANAGEMENT: RESOURCE MANAGEMENT: CIVIL & ENVIRONMENTAL ENGINEERING

3 DOCUMENT CONTROL RECORD CLIENT PROJECT Bloom St Georges Limited Bloom Henderson TERRA PROJECT NO DOCUMENT TITLE Infrastructure Assessment Report VERSION HISTORY VERSION DATE OF ISSUE /03/ /04/ /06/2016 AUTHOR Josh Raynes Civil Engineer REVIEWED Graham Tuhi Engineering Manager OFFICE OF ORIGIN Auckland TELEPHONE DOCUMENT LOCATION Z:\Swanson Road (21)\Engineering\Project File\12. Infrastructure Assessment Report\21 Swanson IAR.docx

4 TABLE OF CONTENTS 1 Introduction Scope of Assessment Scope of work Assessment Criteria Site Description Development Proposal Proposed Earthworks Description of Earthworks Earthworks Management Plans Construction Management Plan (CMP) Erosion and Sediment Control Plan (ESCP) Earthworks Management Plan and Methodology Wastewater Assessment Proposed Wastewater Connection Existing Situation Stormwater Assessment Existing Situation Proposed Stormwater Management Systems Onsite Management for a 10 Year ARI Storm Event Water Quality Management Onsite Management for a 100 Year ARI Storm Event Flood Assessment Operation and Maintenance Stormwater Summary Water Supply assessment Water supply classification Fire Fighting water supply Water Supply Summary Common Accessway and Vehicle Crossings Power, telecommunications and gas Conclusions Swanson Road, Henderson - Infrastructure Assessment Report Page 1 of 14

5 Figure 1 Locality/ site plan... 4 Table 1 Residential Units... 8 Table 2 Upstream Residential... 8 Appendix 1 Appendix 2 Appendix 3 Appendix 4 Appendix 5 GIS Plans Wastewater Calculations Stormwater Calculations and Plans Potable Water Supply and Fire Details Terra Drawing Set 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 2 of 14

6 1 INTRODUCTION Terra Consultants have been engaged by Bloom St Georges Limited to carry out an infrastructure assessment on the suitability of existing public services; wastewater, stormwater and water networks to accommodate the proposed development at 21 Swanson Road, Henderson, Auckland. The report also addresses the implications to the proposal of overland flows and localised flooding, together with addressing the earthworks associated with the development during the construction period. The proposal is to develop two multi-storey residential units on the subject site. This report has been prepared in support of a Resource Consent application to Auckland Council and presents findings of investigations undertaken thus far. 2 SCOPE OF ASSESSMENT 2.1 SCOPE OF WORK A review of the existing topography and the proposed development plan Site walk over inspection by engineer to identify any key features that may influence the development and design Calculations of earthworks and management controls Calculations of anticipated volumes of stormwater and wastewater Assessment of stormwater and wastewater networks in the vicinity to cater for the development Pressure testing of the existing hydrants and water supply classification Assessment of overland flow and localised flooding 2.2 ASSESSMENT CRITERIA This report addresses the following items: Earthworks: Earthworks management controls and plans Wastewater: Calculate the expected flows to be generated from the development Assess the capacity of the downstream sewer line to cater for the additional flows Stormwater Calculate the expected flows generated from the developments Determine appropriate stormwater treatment and disposal methods Overland flow and flooding 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 3 of 14

7 Water Supply Determine the appropriate water supply classification for the development Assess the ability of the existing public water network to meet the demands of the proposed development. Requirement for firefighting purposes 3 SITE DESCRIPTION The subject site is located on Swanson Road approx. 200m west of the Lincoln Road and Swanson Road intersection. The site is with within walking distance of the Henderson CBD and the Waitakere Hospital. This site is vacant and is accessed directly of Swanson Road via 90m long driveway. The site has been cleared of vegetation. The subject site is currently in one title with a total area of 3,877 m2. See topographical plan in Appendix 5. Legal Property Details Lot 1 DP60325 = 3,877m² The site is located in an established residential neighbourhood and surrounded by residential properties on the north and west boundaries. There are residential units on the east boundary of the driveway and a private hospital located on the eastern boundary of the site. The site is relatively flat with the driveway levels that gently slope towards Swanson Road. Auckland Council Geographical Information System (GIS) indicates there is a public wastewater line traversing through the property at the end of the driveway and a public stormwater line on the southern side of Swanson Road. The public watermain outside the property entrance within the berm is a 100mm dia with fire hydrant located outside of the driveway of the units on 17 Swanson Road. Figure 1 Locality/ site plan 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 4 of 14

8 4 DEVELOPMENT PROPOSAL The applicant s proposal is to a construct two multi-level residential buildings. The two buildings will consist of three levels with a total number of 36 units. The proposed buildings will each consist of three levels with each building hosting 6 units per level for a total of 36 units (18 on each). The ground floors of each building contain 5 x 2 bedroom units, and a 1 x 1 bedroom unit, while the two upper floors all contain 6 x 2 bedroom units. There are 42 proposed parking spaces, some of which will be covered. The surrounding areas around the buildings will be landscaped. Refer to the development plans in the resource consent application and separate traffic report for parking clarification. 5 PROPOSED EARTHWORKS 5.1 DESCRIPTION OF EARTHWORKS The proposal will result in earthworks being carried out over 98% of the site including a portion of the right of way easement along 17 Swanson Road units being an area of approx. 120 m 2. The portion of the site in the north-western corner under the protected trees namely the root exclusion zone will be protected during the construction phase. The total earthworks area is 3,928 m 2 and results in bulk volumes of 150 m 3 cut and 1,420 m 3 fill. The earthworks activities will include cut and disposal of the existing driveway to design levels. The stripping of the topsoil and disposal offsite approx. 770m 3. Construction of retaining walls to accommodate the finished levels around building 1. Import of additional material in the form of aggregate and other bulk construction material will be brought onto site for accessway, parking areas and slabs construction. EARTHWORK SUMMARY Within the building platform Outside the building platform Total earthworks Area 900 m2 3,028 m2 3,928 m2 Volume 310 fill topsoil = 500m3 1,990 m3 150 cut topsoil fill = 2,490 m3 5.2 EARTHWORKS MANAGEMENT PLANS A Construction Management Plan (CMP) and Erosion and Sediment Control Plan (ESCP) as described below will be provided to manage the construction process prior to the commencement of any physical work on the site for review and approval by the 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 5 of 14

9 Auckland Council Compliance and Monitoring team: An assessment against Rule 3.4 (a) of the District Plan General Natural Area Earthworks is also included Construction Management Plan (CMP) This Plan shall include specific details relating to the construction and management of all works and include but not be limited to: A construction methodology; Specific details relating to avoiding, remedying or mitigating adverse effects, including the effects of vibration during demolition, excavation and other earthworks, construction and management of all works associated with the development; A plan of action to remedy any adverse effects which may occur to any adjacent property during construction; Confirmation that sufficient equipment, materials and personnel to be available on site to ensure that any necessary measures to avoid, remedy or mitigate adverse effects will be implemented; Measures to be adopted to maintain the site in a tidy condition in terms of disposal/ storage of rubbish, storage and unloading of building materials and similar construction activities; Measures for waste management which include designated sites for refuse bins, and for recycling bins for glass, plastic and can storage and collection in accordance with the Council's waste reduction policy; Location of workers' conveniences ("portaloos"); Dust control measures; Location of site hoardings. No hoardings on the site shall contain any advertising materials (whether affixed permanently or otherwise); Measures to ensure ongoing access for the properties use the right of way. Temporary traffic management Erosion and Sediment Control Plan (ESCP) The site is flat and gently slopes at 1% from the western boundary to the eastern boundary. The earthworks consist of 300mm cut within the right of way/carpark 2 and 0-700mm of fill within the building foundations and carpark 1. Sediment controls will be put in place prior to earthworks in accordance with Council s requirements. The topography of the site is low risk therefore we have proposed silt fences along the eastern boundary of the site to allow for sheet flow and protection of the neighbouring site. The construction site entrance is proposed to be located at the entrance off Swanson Rd and stabilized access to manage material tracking onto the public road. This is required to be fully fenced with a lockable security gate at the entrance. The proposed measures are in accordance with the ARC Technical Publication 90 and will be constructed prior to any site works earthworks commencing, and thereafter maintained these measures for the duration of the excavation works. 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 6 of 14

10 5.2.3 Earthworks Management Plan and Methodology Although a detailed CMP and ESCP will be provided by the contractor as described above, the following details relate to the assessment of Rule 3.4(a) of the district plan. The total earthworks for the site is 2,490m3 and assuming small trucks are used can take 15m3 solid measure each trip that is 166 movements over an earthwork period of say 2 months. The land will be stabilised by laying the aggregate for the road and building foundations shortly after earthworks have been completed. The drainage and control of silt is as described on drawing RC205 and described in section The land will be recontoured in accordance with the proposed contour plan RC200 and the pervious areas landscaped as per the landscape plan MP01. Haul roads for earthworks will closely follow the final common accessway location with silt controls in place. 6 WASTEWATER ASSESSMENT According to the Auckland Council Geographical Information System (GIS) contained in Appendix 1 and topographical plan contained in Appendix 5, there is a 150mm diameter public sewer pipe located midway through the site located at the end of the existing driveway. This serves the upstream catchment of approximately 1.6ha incorporating 30 households with a mixture of residential properties. The topographical survey has been completed for the upstream manhole (id ) within 27 Swanson road and the downstream manhole (id ) within 13 Swanson road. The downstream network continues east along Sel Peacock drive towards the trunkmain at Alderman drive intersection. 6.1 PROPOSED WASTEWATER CONNECTION The proposal is to construct a new public manhole on this line and connect each building to the new manhole via a private wastewater connection allowing a private manhole for each building to connect to, refer to drainage plans in appendix 5. A pre and post construction CCTV will be necessary to confirm the existing condition and any post construction defects. The existing private connection on this line will need to be removed and sealed off. Building work is required over the existing public wastewater for the covered carpark 2, a works over application to Watercare will be required prior to commencement of work. The Watercare Services Limited Water and Wastewater Code of Practice for Land Development and Subdivision, Section 5, for residential flows suggests an average dry weather flow of 225 litres per day per person and a dry weather diurnal peaking factor of 3.0. For design purposes a peak wet weather flow of 1,500 litres per day per person is specified. The proposal is for retirement living, which will have 2 persons (if not less) on average. From these design parameters the amount of wastewater generated by the development is calculated as: Number of Peak Flow Q People per Total Peak Total Peak 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 7 of 14

11 Units (l/d/p) Unit Flow (l/d) Flow (l/s) 36 1, , Table 1 Residential Units 6.2 EXISTING SITUATION As mentioned previously the upstream catchment incorporates a mixture of residential properties. The total catchment area is approximately 1.7 ha and has 30 existing units/households. The existing 150mm pipeline through the centre of the site has been surveyed and has a confirmed grade of 0.82% from manhole ( ) to manhole ( ). The wastewater generated by these properties is estimated as follows: Number of Units Peak Flow Q (l/d/p) People per Unit Total Peak Flow (l/d) Total Peak Flow (l/s) 30 1, , Table 2 Upstream Residential Using the Colebrook-White method, it has been calculated that the pipeline noted above has an average carrying capacity of 16.1 L/s (see appendix 2). The existing catchment thus currently contributes: 1.56/16.2 x 100% = 9.6% With the addition of the proposed development, the total flow in the pipe will increase to 1.56 L/s plus 1.25 L/s equalling a total of 2.81 L/s and therefore: 2.81/16.2 x 100% = 17.3% Noting that this represents an increase of 7.7%, and that the pipe still has a residual capacity of L/s (or 82.7%), thus wastewater generated by the proposal can be accommodated by the existing public network. 7 STORMWATER ASSESSMENT 7.1 EXISTING SITUATION The site is currently brownfield with a recently occupied large dwelling and a tennis court. Currently there is no existing stormwater connection to public reticulation. The nearest public reticulation to the site is a 375mm diameter pipe located on the southern 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 8 of 14

12 side of Swanson Road. The existing public infrastructure discharges to Opanuku Stream. 7.2 PROPOSED STORMWATER MANAGEMENT SYSTEMS Guidelines adopted for the design of the stormwater management system are provided within the Auckland Council Stormwater Code of Practice (SWCoP). Guidance and criteria for the design of stormwater devices is provided in the Auckland Regional Council technical publication TP10 (Stormwater Management Devices: Design Guidelines Manual). Post development offsite flows for the primary system will be managed to pre development greenfield levels. In addition, as the existing reticulated network is under capacity, we have limited the post development flows to greenfield levels of a 5 year storm as directed by the council Development Engineer. As the site is located within a Stormwater Management Area Flow 1 (SMAF 1), the development will also be required to mitigate stormwater flows according to the PAUP requirements below; Provide detention (temporary storage) with a volume equal to the runoff volume from the 95th percentile, 24 hr rainfall event for the impervious area for which hydrology mitigation is required. Provide retention (volume reduction) of a 10mm, 24 hr rainfall event for the impervious area for which hydrology mitigation is required Onsite Management for a 10 Year ARI Storm Event The stormwater runoff from the proposed development will be managed by collecting it from the roof and paved areas and connecting it into a regulated drainage system. This will ensure the existing stormwater network downstream is not affected from additional flows produced from the proposed impervious areas created from the development. Although the site had buildings prior the development proposal, for calculation purposes we have assumed the site to be in a greenfield condition. Above ground detention tank systems will be installed adjacent each building to manage flows from the building roofs and covered carpark roof areas. Within the tanks will be a retention portion which will be for reuse. An in-ground detention tank system will be installed within the southern end of the common accessway to manage the flows from the common accessway and other paved areas. A new connection is proposed by extending the public infrastructure from the 375mm diameter pipe along the southern side of Swanson Road to a new proposed public manhole within the property boundary. The network from this point will be privately owned and maintained. Please see Appendix 5 Terra drawing set for details. 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 9 of 14

13 7.2.2 Water Quality Management Water quality management for the proposed development is discussed as follows: All roofing, cladding or architectural features will not have high contaminantyielding materials. Stormwater from the paved areas of the development will be collected via catchpits with Stormwater 360 Enviropods or similar. In-ground and above ground detention tanks shall be installed prior to discharging to the public network. Under the PAUP, Part 3 Chapter H Section , uncovered parking including entry/exit, which is less than or equal 1000m² is permitted without requiring treatment. As the development has a total of 989m² of impermeable uncovered paved area, no treatment is required Onsite Management for a 100 Year ARI Storm Event The new design levels for the driveway and carparks allow for approximately a third of the roof and carpark catchment post development flows to be managed into Swanson Rd. The remaining flows will discharge to the eastern boundary via a level spreader within the constructed upstream conveyance channel along eastern boundary of building 1. In addition, a channel at base of the wall long building 2 directs the stormwater flows from carpark 2. The calculations and catchment plans have been produced to indicate predevelopment flows at the existing overland flow path exit location are maintained, therefore the effects are to be equivalent in the event of a 100yr storm event Flood Assessment The Auckland Council GIS indicates a minor overland flow path (OLFP) that traverses through the site and discharge to the neighbouring hospital site midway along the eastern boundary. The upper catchment area is indicated to be approximately 0.24ha from Te Kanawa Crescent entering the site midway on the northern boundary. It is apparent from the site visit that Te Kanawa Crescent has a highpoint midway of the road and delineates the upper catchment in an east to west direction. Therefore, confirming our catchment area for calculation purposes. The upper catchment area is estimated at approximate 0.24ha from the northern boundary to Te Kanawa Cresent. This flow has been calculated at 75L/s using TP108 method. Therefore, no ponding occurs on site, and we have assessed the development as an exercise of managing overland flows. The proposed building 1 will be located within the overland flow path indicated on the GIS therefore an allowance has been made to manage this flow around the building as not to effect the entry and exit points of the existing upstream overland flow. The overland flow will be fully contained in a constructed channel which will ensure compliant freeboard is achieved to the building floor level and the capacity of the flow path will not be affected by the development. Fencing at the boundaries will be designed to ensure the overland flow will not be 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 10 of 14

14 obstructed. Refer to Appendix 3 for calculations and Appendix 5 for Terra drawings/details. Pre development 100-year sheet flows at the eastern boundary are around 185 L/s based on 75L/s off site and 110L/s on site. In the post development situation, the overall sheet flows at the eastern boundary are around the same at 188L/s comprised of 75L/s offsite, and 113L/s on site. The remaining on-site flows are directed down the accessway onto Swanson Road. Therefore, there is no increased risk for downstream flooding as we are discharging the overland flows at the same location and at a similar rate as the existing situation. 7.3 OPERATION AND MAINTENANCE The Stormwater Management Manual set out standard forms to be used and submitted to Auckland Council as part of the building consent for private drainage. The forms include Operation and Maintenance Plans and Operation and Maintenance Routine documents for the proposed systems. These forms will be provided at a later stage. It should be noted that proposed stormwater systems will be private. It is expected that conditions will be included in the consent to ensure that stormwater devices are properly operated and maintained. 7.4 STORMWATER SUMMARY Based on the calculations and assessments, the proposed stormwater system will not significantly affect the existing stormwater network. The use of detention tanks will attenuate 10 year ARI storms and SMAF 1 requirements under PAUP. The storm water discharge which is going to the reticulated system is in accordance with the conditions of the network discharge consent. The development is within the permitted area for stormwater quality measures under the PAUP. Engineering approval for the extension of the public system shall be applied for prior to construction. 8 WATER SUPPLY ASSESSMENT 8.1 WATER SUPPLY CLASSIFICATION The New Zealand Fire Service - Fire Fighting Water Supplies Code of Practice SNZ PAS 4509:2008 applies. For sprinklered structures we have determined the development will have a water supply classification of FW FIRE FIGHTING WATER SUPPLY 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 11 of 14

15 Based on Table 1 - Method for determining required water supply classification, (New Zealand Fire Service - Fire Fighting Water Supplies Code of Practice SNZ PAS 4509:2008) the proposed development requires structures to be fitted with sprinkler systems which are installed to an approved standard. There are two public fire hydrants in the vicinity of the proposed development. There is one hydrant located on the northern side of Swanson Rd outside number 17 on a 100mm AC pipe (Hydrant 1) refer to Appendix 4. There is another fire hydrant located on the western side of Swanson Rd outside number 14 (Hydrant 2) on a 150mm AC pipe. Hydrants 1 is within the 200m distance from the back boundary of the site and Hydrant 2 approximately 295m. In order to meet the FW2 minimum requirements of PAS 4509: 2008, 12.5Lps is required within 135m and an additional 12.5Lps is required within 270m of the development buildings. This being a total of 25Lps at a minimum residual pressure of 100kPa. Only Hydrant 1 complies with this requirement to be within the distance of 270m. The development requires an additional hydrant to be with 135m therefore we have proposed a private FH within the site. A hydrant test was undertaken by Nova Flow Tec on the 29 th January The results showed a flow of 50.1 L/s for both hydrant 1 and 2 which proves the minimum FW2 requirement for flowrate is available at the street entrance. 8.3 WATER SUPPLY SUMMARY With the existing network in place the proposed development will not have any significant impact on the water distribution in the area. Connections will be made in accordance with the Watercare Services Limited Water and Wastewater Code of Practice for land Development and Subdivision Section 6 on water supply. With the proposal to construct an additional private fire hydrant and have the buildings fitted with sprinklers the development will comply with the distance for an FW2 requirement. The Nova Flowtec test results confirm there is sufficient flow at the entrance of the site for firefighting purposes. 9 COMMON ACCESSWAY AND VEHICLE CROSSINGS The buildings shall be accessed directly from Swanson Road and will require a new concrete vehicle crossing. The design of the vehicle crossing, car parking and common access way will be to the Auckland Transport code of practice. Prior to construction work an engineering application will be applied for separately for both the new vehicle crossing and a common access way. Refer to separate traffic report for parking and traffic impacts from the development. 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 12 of 14

16 10 POWER, TELECOMMUNICATIONS AND GAS Noting that the site is located in an established locality it is fair to assume that it can be adequately serviced by all existing utility services provided within the road reserve (Telecom, Power, and Gas). These services will be extended into the site with approval from the various services providers. Connection details of utility services will be provided at engineering approval/building consent stage. 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 13 of 14

17 11 CONCLUSIONS From this assessment of infrastructure, it has been found that there is capacity in all existing infrastructure systems to accommodate the proposed development. This assessment has been carried out in accordance with regional and national statutory requirements. Earthworks management plans are to be in place prior to commencement of site work and these are subject to review and approval by Auckland Council Compliance and Monitoring Team. Relevant activities shall be carried out in accordance with the ARC TP90 design guidelines. The Earthworks and Sediment Control Plan by Terra Consultants should be used. Wastewater assessment was carried out in accordance with the Watercare Services Limited Water and Wastewater Code of Practice for land Development and Subdivision - Section 5. The Auckland City Council GIS system was used to identify the sewer network in the locality. It was concluded through our assessment that the existing downstream infrastructure has adequate capacity to absorb the effects of the proposed development. An application will be made to Watercare for connection into the public sewer. Stormwater management systems have been designed in accordance with the Auckland Council Stormwater Code of Practice (SWCoP) and Technical Publication TP10. The onsite management for a 10yr storm event has been designed to attenuate flows to ensure the post development is no greater the pre-development (greenfield). The overland flows have been assessed and identified for the onsite and upstream catchments for the 100yr storm event. The New Zealand Fire Service - Fire Fighting Water Supplies Code of Practice SNZ PAS 4509:2008 was used to assess the adequacy of water supply in the locality in order to service the proposed development. It was determined that there is sufficient flow and pressure in the existing network for potable supply and firefighting requirements. With the proposal to construct an additional private fire hydrant and have the buildings fitted with sprinklers the development will comply with the distances for an FW2 requirement. Other utilities will be connected with approval from the various service providers. 21 Swanson Road, Henderson - Infrastructure Assessment Report Page 14 of 14

18 Appendix 1 GIS PLANS 21 Swanson Road, Henderson - Infrastructure Assessment Report

19 This map/plan is illustrative only and all information should be independently verified on site before taking any action.copyright Auckland Council. Boundary information from LINZ (Crown Copyright Reserved). Whilst due care has been taken, Auckland Council gives no warranty as to the accuracy and completeness of any information on this map/plan and accepts no liability for any error, omission or use of the information. Height datum: Auckland Created: Wednesday, 16 March 2016,5:11:06 p.m. 21 Swanson Road A3 1:1000

20 Appendix 2 WASTEWATER CALCULATIONS 21 Swanson Road, Henderson - Infrastructure Assessment Report

21 Pipe capacity ( 0.82 % grade) Colebrook-White Formula g = Gravity n = kinematic viscosity of water = 9.81 m/s2 = 1.010E-06 m2/s k = Colebrook-White roughness coeff = mm = 6.000E-04 m D = Inside diameter = 150 mm = m S = Slope, in metres per metre = 0.820% = m/m = (Hydraulic Gradient) V = Velocity = 0.91 m/s Discharge: Q = V x A A = m2 Q = m/s = 16.1 L/s

22 Appendix 3 STORMWATER CALCULATIONS AND PLANS 21 Swanson Road, Henderson - Infrastructure Assessment Report

23

24 Project 21 Swanson Road Project Number Client Bloom Living By SM Checked GT Date 25/05/2016 Summary of Catchment Areas Area (m²) C Reduced Area (m²) I (mm/hr) Q (L/s) Pre Development (Greenfield) - 5yr Pre Development (Greenfield) - 10yr Post Development Impervious Subcatchment Cover type Area (m²) C Reduced Area (m²) I (mm/hr) Q (L/s) Building 1 Roof Covered Roof 1A Roof Covered Roof 1B Roof TOTAL Building 2 Roof Covered Roof 2A Roof Covered Roof 2B Roof TOTAL Carpark 1 Paved Impervious Carpark 2 Paved Impervious Driveway 1 Paved Impervious Driveway 2 Paved Impervious TOTAL Building 1 Footpaths Paved Impervious Building 2 Footpaths Paved Impervious TOTAL TOTAL IMPERVIOUS Post Development Pervious Subcatchment Cover type Area (m²) Grass Pervious 1137 TOTAL 1137 Carpark 1 Permeable Paved Permeable 151 Carpark 2 Permeable Paved Permeable 57 Additional ROW (Footpath) Paved Permeable 138 TOTAL 346 TOTAL PERVIOUS 1483 Total Post Development Area 4015

25 Project 21 Swanson Road Project Number Client Bloom Living By SM Checked GT Date 25/05/2016 BUILDING 1 DETENTION CALCULATIONS SMAF 1 REQUIREMENTS Provide detention (temporary storage) with a volume equal to the runoff volume from the 95th percentile, 24 hr rainfall event for the impervious area for which hydrology mitigation is required. Provide retention (volume reduction) of a 10mm, 24 hr rainfall event for the impervious area for which hydrology mitigation is required 95th percentile storm 35 mm Retention 10 mm Total Post Impervious Area 651 m² Runoff coefficient 0.9 Vol retained in tank for re-use 5.9 m³ Detention 25 mm Total Post Impervious Area 651 m² Runoff coefficient Vol Required to Detain 24hr 95th percentile storm 0.9 volume 14.6 m³ Average outflow per tank over 24 hours 0.17 L/s Peak outflow = 2 x average outflow 0.34 L/s Orifice height above tank invert 0.60 m Head above orifice 1.5 m Orifice diameter 13 mm Total volume required for SMAF 1 requirements 20.5 m³ 10 YEAR STORM INFLOW / 5 YEAR OUTFLOW Area (m²) C Reduced Area (m²) I (mm/hr) Q (L/s) Pre Development (Greenfield) - 5yr yr permitted discharge Outflow Qpeak orifice [l/s] Qpeak orifice [l/s] Qave = 0.50 x Qpeak 0.17 [l/s] Qave = 0.50 x Qpeak 2.4 [l/s] DETENTION TANK STORAGE CALCULATION Inflow into 10 yr Inflow tank after Depth minus Reduced Time to fill SMAF Outflow Outflow time dur. Intensity 35mm SMAF area Flow from catchment SMAF tank volume full Orifice 1 Orifice 2 Storage [min] [mm/hr] [mm] [m²] [m³/s] [min] [m³] [m³] [m³] [m³] Storage required for 10 year detention 3.4 [m³] Intensities sourced from NIWA HIRDS data TANK DETAILS TOTAL STORAGE = = 23.9m3 Orifice Height above tank invert 2.1 [m] Head above Orifice 0.23 [m] 10 YR volume requirement 3.4 [m³] Orifice 2 diameter 76 [mm]

26 Project 21 Swanson Road Project Number Client Bloom Living By SM Checked GT Date 25/05/2016 BUILDING 2 DETENTION CALCULATIONS SMAF 1 REQUIREMENTS Provide detention (temporary storage) with a volume equal to the runoff volume from the 95th percentile, 24 hr rainfall event for the impervious area for which hydrology mitigation is required. Provide retention (volume reduction) of a 10mm, 24 hr rainfall event for the impervious area for which hydrology mitigation is required 95th percentile storm 35 mm Retention 10 mm Total Post Impervious Area 684 m² Runoff coefficient 0.9 Vol retained in tank for re-use 6.2 m³ Detention 25 mm Total Post Impervious Area 684 m² Runoff coefficient Vol Required to Detain 24hr 95th 0.9 percentile storm volume 15.4 m³ Average outflow per tank over 24 hours 0.18 L/s Peak outflow = 2 x average outflow 0.36 L/s Orifice height above tank invert 0.6 m Head above orifice 1.5 m Orifice diameter 13 mm Total volume required for SMAF 1 requirements 21.5 m³ Area (m²) C Reduced Area (m²) I (mm/hr) Q (L/s) Pre Development (Greenfield) - 5yr yr permitted discharge OUTFLOW Qpeak orifice [l/s] Qpeak orifice [l/s] Qave = 0.50 x Qpeak 0.18 [l/s] Qave = 0.50 x Qpeak 2.6 [l/s] DETENTION TANK STORAGE CALCULATION Depth Reduced Time to Inflow Outflow Outflow time dur. Intensity minus area Flow from catchment fill SMAF into tank Orifice 1 Orifice 2 Storage [min] [mm/hr] [mm] [m²] [m³/s] [min] [m³] [m³] [m³] [m³] Intensities sourced from NIWA HIRDS Storage required for 10 year detention 3.5 [m³] data TANK DETAILS TOTAL STORAGE = = 25m3 10 YEAR STORM REQUIREMENTS Orifice Height above tank invert 2.1 [m] Head above Orifice 0.24 [m] 10 YR volume requirement 3.5 [m³] Orifice 2 diameter 77 [mm]

27 Project 21 Swanson Road Project Number Client Bloom Living By SM Checked GT Date 25/05/2016 PAVED AREA DETENTION CALCULATIONS SMAF 1 REQUIREMENTS Provide detention (temporary storage) with a volume equal to the runoff volume from the 95th percentile, 24 hr rainfall event for the impervious area for which hydrology mitigation is required. Provide retention (volume reduction) of a 10mm, 24 hr rainfall event for the impervious area for which hydrology mitigation is required 95th percentile storm 35 mm Retention 10 mm Total Post Impervious Area 1197 m² Runoff coefficient 0.9 Vol retained in Triton tank 10.8 m³ Detention 25 mm Total Post Impervious Area 1197 m² Runoff coefficient Vol Required to Detain 24hr 95th 0.9 percentile storm volume 26.9 m³ Average outflow per tank over 24 hours 0.31 L/s Peak outflow = 2 x average outflow 0.62 L/s Orifice height above tank invert 0 m Head above orifice 0.67 m Orifice diameter 21 mm Total volume required for SMAF 1 requirements 37.7 m³ Area (m²) C Reduced Area (m²) I (mm/hr) Q (L/s) Pre Development (Greenfield) - 5yr yr permitted discharge OUTFLOW Qpeak orifice [l/s] Qpeak orifice [l/s] Qave = 0.50 x Qpeak 0.31 [l/s] Qave = 0.50 x Qpeak 4.5 [l/s] DETENTION TANK STORAGE CALCULATION Depth Reduced Time to fill Inflow Outflow Outflow time dur. Intensity minus area Flow from catchment SMAF into tank Orifice 1 Orifice 2 Storage [min] [mm/hr] [mm] [m²] [m³/s] [min] [m³] [m³] [m³] [m³] Intensities sourced from NIWA HIRDS Storage required for 10 year detention 6.4 [m³] data TANK DETAILS Orifice 2 Height above tank invert 0.67 m Head above Orifice 0.19 m 10 YR Volume requirement above SMAF detention 6.4 m³ Orifice 2 diameter 109 mm TOTAL STORAGE = = 44.2m3 10 YEAR STORM REQUIREMENTS Bare chamber storage 0.66 m3 (Model S mmW x 864mm H, 762mm L) Trial length 29 m Storage in empty chambers 19 m3 Volume of drainage aggregate around tanks m3 (assuming rectangulare trench 2m wide, x 1.31m high - re Stormwater storage in drainage aggregate m3 assuming 1/3 of drainage aggregate is voids) Total stormwater storage provided 44.47

28 Development Catchment and Hydrological Calculations using AC TP YEAR - PRE DEVELOPMENT UpStream Offiste Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 17/03/2016 Notes: Area assumed greenfield Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Grass Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 5.00 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.8 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.59 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 5.00 Time of Concentration (hrs) = Storage, S (mm) = ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = 74.6 Runoff Depth, Q24 (mm) = 164 Runoff Volume, V24 (m 3 ) = 395

29 Development Catchment and Hydrological Calculations using AC TP YEAR - PRE DEVELOPMENT - Onsite Flows Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 29/01/2016 Notes: Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Grass Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 5.00 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.8 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.59 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 5.00 Time of Concentration (hrs) = Storage, S (mm) = ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = Runoff Depth, Q24 (mm) = 164 Runoff Volume, V24 (m 3 ) = 584

30 Development Catchment and Hydrological Calculations using AC TP YEAR - POST DEVELOPMENT Onsite Flows to Eastern Boundary Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 29/01/2016 Notes: Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Apartment Rooftops Group C East Coast Bays Formation Parking/Driveway Group C East Coast Bays Formation Grass Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 2.05 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.6 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.79 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 2.05 Time of Concentration (hrs) = Storage, S (mm) = ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = 78.3 Runoff Depth, Q24 (mm) = 202 Runoff Volume, V24 (m 3 ) = 448

31 Development Catchment and Hydrological Calculations using AC TP YEAR - POST DEVELOPMENT - Onsite Flows to South Eastern Boundary Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 29/01/2016 Notes: Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Apartment Rooftops Group C East Coast Bays Formation Parking/Driveway Group C East Coast Bays Formation Grass Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 1.25 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.6 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.85 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 1.25 Time of Concentration (hrs) = Storage, S (mm) = ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = 34.9 Runoff Depth, Q24 (mm) = 212 Runoff Volume, V24 (m 3 ) = 192

32 Development Catchment and Hydrological Calculations using AC TP YEAR - PRE DEVELOPMENT - Onsite Accessway Flows to Swanson Road Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 29/01/2016 Notes: Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Parking/Driveway Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 0.00 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.6 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.96 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 0.00 Time of Concentration (hrs) = Storage, S (mm) = 5.18 ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = 16.8 Runoff Depth, Q24 (mm) = 229 Runoff Volume, V24 (m 3 ) = 99

33 Development Catchment and Hydrological Calculations using AC TP YEAR - POST DEVELOPMENT - Onsite Accessway Flows to Swanson Road Project: 21 Swanson Road Project Number: Client: Bloom Living By: JR Checked: Date: 29/01/2016 Notes: Rainfall intensity sourced from AC TP108 Daily Rainfall Depth Charts 1. Runoff Curve Number and Initial abstraction Soil name and classification Cover Description Curve Number Area (m 2 ) Product of CN x Area Group C East Coast Bays Formation Apartment Rooftops Group C East Coast Bays Formation Parking/Driveway Totals = Time of Concentration CN (weighted) = Ia (weighted)(mm) = 0.00 (5mm from pervious areas, 0mm from impervious areas) Channelisation Factor = 0.6 Catchment Length (km) = 0.07 Catchment Slope (m/m) = Runoff factor = 0.96 tc (hrs) = tc (mins) = tp (hrs) = tp (mins) = Graphical Peak Flow Rate Catchment Area (km 2 ) = Runoff Curve Number = Initial Abstraction = 0.00 Time of Concentration (hrs) = Storage, S (mm) = 5.18 ARI = 100 YEAR 24 HR Rainfall Depth, P 24 (mm) = 200 Climate Change Factor (%) = HR Rainfall Depth with Climate Change, P 24 (mm) = c* = q* (from figure TP108) = Peak Flow Rate qp (m 3 /s) = Peak Flow Rate qp (L/s) = 33.0 Runoff Depth, Q24 (mm) = 229 Runoff Volume, V24 (m 3 ) = 196

34 Channel Report Hydraflow Express Extension for Autodesk AutoCAD Civil 3D by Autodesk, Inc. Friday, Jun Cross Section A User-defined Invert Elev (m) = Slope (%) = N-Value = Calculations Compute by: Known Q Known Q (cms) = Highlighted Depth (m) = Q (cms) = Area (sqm) = Velocity (m/s) = Wetted Perim (m) = Crit Depth, Yc (m) = Top Width (m) = EGL (m) = (Sta, El, n)-(sta, El, n)... ( , )-(3.8500, , 0.020)-(4.1000, , 0.020)-(4.2000, , 0.020)-(4.2100, , 0.020)-(5.4100, , 0.020) Elev (m) Depth (m) Section Sta (m)

35 Channel Report Hydraflow Express Extension for Autodesk AutoCAD Civil 3D by Autodesk, Inc. Wednesday, Jun Swanson - B2 Cross Section C User-defined Invert Elev (m) = Slope (%) = N-Value = Calculations Compute by: Known Q Known Q (cms) = Highlighted Depth (m) = Q (cms) = Area (sqm) = Velocity (m/s) = Wetted Perim (m) = Crit Depth, Yc (m) = Top Width (m) = EGL (m) = (Sta, El, n)-(sta, El, n)... ( , )-(2.3000, , 0.011)-(2.3100, , 0.011)-(3.1750, , 0.011)-(3.1770, , 0.011)-(3.3000, , 0.011)-(3.8000, , Elev (m) Depth (m) Section Sta (m)

36 Channel Report Hydraflow Express Extension for Autodesk AutoCAD Civil 3D by Autodesk, Inc. Wednesday, Jun Swanson - B1 Cross Section D User-defined Invert Elev (m) = Slope (%) = N-Value = Calculations Compute by: Known Q Known Q (cms) = Highlighted Depth (m) = Q (cms) = Area (sqm) = Velocity (m/s) = Wetted Perim (m) = Crit Depth, Yc (m) = Top Width (m) = EGL (m) = (Sta, El, n)-(sta, El, n)... ( , )-(2.3000, , 0.011)-(2.3100, , 0.011)-(3.1750, , 0.011)-(3.1770, , 0.011)-(3.3000, , 0.011)-(3.8000, , Elev (m) Depth (m) Section Sta (m)

37 Appendix 4 POTABLE WATER SUPPLY AND FIRE DETAILS 21 Swanson Road, Henderson - Infrastructure Assessment Report

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