Auckland CBD

Rosebank + Blum Site

The site is located in Rosebank or on the Rosebank peninsula which extends out from Henderson into the Waitemata harbour. The Te Atatu peninsula situ-ated to the west is separated from Rosebank by the Whau river. Topography of the site is generally flat and level until the ground slopes steeply down to the water. The area features underling soils of Pumi-ceous mud, sand and gravel with black muddy peat and lignite. The site has a history prior to industry as being predominantly agricultural and horticultural. The Rosebank site has an industrial and commer-cial surrounding. It is situated in a highly disturbed area where impervious concrete dominates. The site is boarded by large buildings and the Avondale Pen-insula.

Ryan James Aldrich

Auckland CBD

Auckland, New Zealand

Auckland CBDRosebank + Blum Site

Ryan James Aldrich

LIUDD is an acronym for low impact urban design. The underlying driver behind LIUDD is that to be sustainable we must recognize the limitations of ecosystems. We must adjust our activity as humans to be within these ecosystems limitations. LUIDD is an integrated approach to design and development that aims to protect aquatic and terrestrial ecologi-cal integrity while allowing urbanization. It aims to avoid the adverse effects typically associated with development. (Marjori & Hanri, 2009)

New Zealand since the late 1990’s has been evolving low impact and water sensitive approaches to urban development. LIUDD is a mechanism for achieving improved catchment management, more sustain-able subdivision, and development, reduced envi-ronmental footprints of urban areas, reduced mate-rial use and waste, reduced sediment, pollutant run off and impervious surfaces, while increasing ter-restrial and aquatic biodiversity. Low impact urban design and development is a synthesis of a number of concepts. LIUDD comprises of previous concepts such as Low impact development, conservation sub divisions, integrated catchment management, sus-tainable building / green architecture. (Landcare Research, 2011)

Low impact urban design and development is a con-cept that focuses on avoiding impervious surfaces

such as concrete. It aims to minimize earthworks in construction. LIUDD uses vegetation is used to trap sediment and pollutants. Ultimately it aims to minimize energy, material, and waste in urban de-velopment. This is accomplished through the un-derstanding of natural process and integrating them into our developments. (Mortimer, 2010 )

LUIDD is intended to be sustainable. It aims to maintain and enrich the condition of ecosystems and ultimately our environment as a whole. Indige-nous nature and biodiversity become integrated into urban areas. Designing natural features or systems to reduce flooding, to filter pollutes, and to regulate temperatures are some of the underlying reasons and outcomes of LIUDD. Low impact urban de-sign and development utilizes and is not limited to green roofs, rain gardens, wetlands, water tanks and swales. (Mortimer, 2010 )

The primary principle of LIUDD: “seeks recogni-tion that human activity should respect and operate within natural cycles in order to minimize negative effects and optimize catchment internalization of materials, contaminates and energy. This principle is embedded in all other principles. The ecological carry copasity concept as part of resilient natural cycles is central to the LIUDD approach.” (Marjorie van & Henri van, 2005)

LIUDD, DEFINITION AND PRINCIPLES

Access to the site

Site parking

Industrial context

Vegetation is scarce

Ryan James Aldrich

Bordering vegetation

Mangroves dominate

Exposed fill soil

Site parking

Industrial context

Steep banks

Ryan James Aldrich

Strom water management is an important and fun-damental, component of low impact urban design and development. When designing for storm water management it is important to select LIUDD devic-es that are fit for purpose, robust and effective for delivering the design objective. LIUDD sets the goal of achieving less then 15% ‘effective impervious sur-face on site. This is to ensure hydrological neutral-ity within a catchment. (Marjorie van & Henri van, 2005)

Storm water management on sites adjacent to ripar-ian areas such as BLUM NZ is crucially important. The site is adjacent to roads, and factories. It is situ-ated in an industrial area. These factors contribute to pollutants being attached to storm water. Im-pervious surfaces within urban areas are far more then that of natural environments. This results in higher peak discharge rates and run of volumes. In-filtration volumes are also lower. To mitigated the environmental impacts resulting from the situation of high impervious areas within urban areas it is im-portant to estimate the quantity of runoff to enable appropriate design of storm water control facilities. (American Jornal of Scientific Research, 2011)

The Low impact urban design and development ap-proach to storm water management is to hold and treat storm water on site. To understand how to best manage storm water on the BLUM NZ site prelimi-nary calculation were undertaken. These calcula-tions help form an understanding of the specific site

conditions and requirements. They inform design so that appropriate storm water devices are selected and placed accordantly. Design of treatment devices based on calculation avoids shortcomings from us-ing ‘off the shelf ’ solutions that are not tailored to the site. Ultimately a LIUDD site-specific storm wa-ter design should offer the greatest efficiency and most beneficial outcomes for storm water manage-ment on the site.

The first step in the design of the storm water devices for the BLUM NZ site was calculating the percent-ages of permeable and impermeable surfaces of the site. Secondly the storm water for a two year rainfall is calculated for the site. The table and figures used in these calculations are attached in the appendix.

The total area of impervious surface: 1,450.7m2The total area of pervious surface: 342.7m2

This establishes that the site currently consists of 23.6% pervious surfaces. Or consisting of 76.4% im-pervious surface. This establishes base guidance for design, as the figure of 23.6% should be reduced to below 15%. This can be achieved by increasing the impervious surface area. A calculation of the storm water run off depth from the site based on 2 year average rainfall was undertaken. The run off depth is 0.22mm. The 24 hour run off depth is 61mm.

CALCULATION OF STORM WATER FOR BLUM NZ SITE

Ryan James Aldrich

STORM WATER TREATMENT DEVICES

Designing from the top down. When approaching storm water treatment and management design for the BLUM NZ site it seemed logical to start at the highest elevation working down to the lowest edge of the site. Creating a train of treatment devices. Elevation is highest at the western edge of the site along Rosebank road. Elevation slopes across the site towards the east. Slope is relatively consistent across the site however at the eastern edge the land it steeply drops away.

As the slop or elevation change is relatively con-sistent across the site the general storm water flow path is relatively simple. Simplistically storm water enters the site from the west or falls. Es-sentially it flows towards the east while the more gradual slopes in conjunction with obstacles such as buildings move water towards the sites north and south boundaries were it exists to continue its vector east.

From this simplistic analysis the design move to prevent storm water existing on the north and south boundaries emerged. The concept is that water can be prevented from leaving along these boundaries and instead be treated by storm water devices in ac-cordance with LIUDD guidelines and principles as it travels along these boundaries.

Rain Garden

Retaining Wall

Ryan James Aldrich

To stop water leaving the site on the north and south boundaries the topography is to be adjusted along these edges. To achieve this a steeping concrete retaining wall runs along these boundaries. The retaining walls sup-port rain gardens running along these boundaries. The eastern edge of the site is subject to steep slope as the land contours down towards the mangrove covered wa-ter. It was decided that a terrace could be formed on the eastern edge of the property. This terrace would function as a rain garden. The west side of the BLUM building would feature a narrow filter strip comprising of stones. When at capacity this device via piping feeds into a larger infiltration and rain garden area butting onto the eastern edge of the container ‘bio isolation’ storage area of the site. This is supported by the retain-ing wall creating the terrace that runs along the eastern side of the site. It was decided that the area of land along Rosebank road between the public and contrac-tor entrances of the BLUM site should be developed to be of similar ecological value and visual aesthetic. Water from the roof of the BLUM building is to be col-lected in a rain water tank located under the deck. The water from this tank is to be used for garden irrigation and for the needs of the building.

Rain water tank

Filter Strip

Retaining W

all

Retaining Wall

Rain Garden

Car Park

Stepping Rain Gardens

Ryan James Aldrich

FAUNA, WILDLIFE, ECOLOGY

Rain Garden

Ryan James Aldrich

FAUNA, WILDLIFE, ECOLOGY

Rain Garden

Retaining Wall

Stepping Rain Gardens

A key component of the management and treatment of storm water on the BLUM site will be rain gardens. These are densely planted depressions that allow for temporary storage of storm water. The underling the soil hosting the planted material comprises allows storm water to percolate through. A typical soil for a rain garden would be a sandy loam. Water is chan-neled above ground into rain gardens from higher elevations. An under drain is used to disperse water that does not evaporate or become absorbed in the soil to the next suitable outfall. (Auckland Regional Council)

Rain gardens like those proposed for BLUM site re-move sediments and their attached contaminates from storm water. Pollutants such as Zinc and cop-per are removed the water and remain adsorbed in the soiled material of the filtration medium. Water flow is reduced while it percolates through the soil. Some water water volume reduction is achieved through evaporation from the plants of the rain gar-den. (Auckland Regional Council)

The soil component is vital for rain garden crea-tion. The soil comprising the rain gardens for the BLUM site should meet permeability requirements of 300mm per day. This figure is necessary for storm water filtration. The soil must also be able to sustain plant life to maximize evapotranspiration. The rain gardens need depressions of at least 200mm to hold storm water while during the filtration. (Auckland Regional Council)

The rain gardens feature at the BLUM site have de-pression from the road and drive of 300mm. An overflow is also vital to cater for water volumes in excess of the rain gardens maximum capacity.

The rain gardens of the BLUM site have been de-signed not have an overflow, instead they are a series of devices that stager in height across the site. When a rain garden is at capacity it overflows into the adjoining and slightly lower rain garden that is next in the train of devices.

ROSEBANK ROAD

Ryan James Aldrich

Rain gardens need to be covered in dense vegetation to be most efficient. A range of plants was considered for the BLUM site. Suitable plants for rain gardens are those that are hardy. Plants that can withstand dry condition and also tolerate short term flooding.

A choice of Leptocarpus (Apodasmia) was made for these characteristics. For variation in texture and high Cordyline australis has been chosen to be planted amongst the Leptocarpus (Apodasmia)in smallgroups.

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Section  of  a  rain  garden.  (Kingston  City  Council,  Melborne,  2011)  

BLUM SHOW ROOM

Stepping Rain Gardens

Ryan James Aldrich

Specific to the BLUM site is how the rain gardens have been design to utilize the sites existing con-tours to incorporate steeping rain gardens. These allow water to overflow rain gardens on higher el-evation and then enter an adjoining and lower rain garden. This forms a treatment train. The stepping rain gardens have an area of 77.4 m2 this is a signifi-cant and would allow infiltration of water from the adjoining impervious surface.

The dense planting of rain gardens should be from eco-sourced plants of the area. The planting of the rain gardens filters pollutants from storm water. Plants increase the evapotranspiration of water from the site. The large amount of plants designed into the sites storm water devices would have a significant af-fect on the sites total run off volume and the quality or purity of this water. The planting also enhances other ecological factors apart from those associated to storm water. Increases in planting help to reduce

the heat island effect of the area. Imperious surfaces are a major factor that contributive to temperature increases in urban areas. Pervious surfaces have a cooling effect. Planted areas that cast shade on areas of impervious surface reduce temperatures and help mitigate height island effects.

Planting provides habitat for fauna. A wide rang of incects will find habitat amongst the Leptocarpus (Apodasmia) and on the Cordyline australis. The eastern edge of the BLUM site boarders onto costal reserve. This area of costal reserve has a selection of foliage across different levels of strata. This provides habitat for a wide range of life.

At the southeast corner of the BLUM site the company has a container unloading and storage bay. This area of the site has strict MATH restriction surrounding the area. It is a ‘bio isolation area’. This prevents planting directly adjoining the area. The area of land adjoining the bay on the east side has been design as an infiltra-tion trench or sump. The surface height of the device area is 200mm below that of the container bay. The device is lined with geo-textile fabric and is filled with coarse gravel. It is berried below 300mm of fine gravel and sandy loam (placed below gravel). Gravel was used on top of the Loam to create a barren area to be within the MATH restrictions for the area.

The size of this infiltration device also caters for the outflow of water from the infiltration trench running along the west edge of the BLUM building.

Ryan James Aldrich

Storm water that enters this infiltration device is filtered removing sediment, leaves and debris. The device allows for storm water to soak into the soil. Storm water is detained while it socks into the underlying soil. The device reduces site runoff volume and it recharges groundwater.

Infiltration Trench

Container Bay

The eastern edge of the BLUM site features a large retaining wall. This wall is of gabion cage construc-tion. This retaining wall allows for the creation of a rain garden between the wall and the BLUM build-ing. As the wall is of gabion cage construction water is able seep through. The loading of storm water on the rain garden supported by this retaining is rela-tively small as most water from the site is handled either by the rain gardens in the drive area, the infil-tration trench adjacent to the container bay and the rain gardens along the site boundaries. Roof water from the BLUM building is to be held in a rainwater tank incorporated into the deck structure. The tank is of concrete construction and takes the shape of the deck. It can be viewed in plan as the total area of the deck. It has a depth of 4 meters. This places the total volume of the tank at 47.6m3 or at 47,600 L. It allows for the storage of all water from the roof.

Overflow from the tank will be dispersed into a bio filtration trench running below and along the ga-bion retaining wall. Water from this tank will be used to irrigate the property as well as provide for the plumbing services within the building.

The rain garden between the retaining wall and the BLUM building is densely planted. It is a bed of Carex flagellifera and Carex testacea. This is to contrast the vegetation of the other rain gardens. Having different vegetation on the site contributes to greater habitat and biodiversity both across the site and the wider area of Rosebank. Carex was cho-sen for this area of the site beside the gabion wall to provide specific habitat. The combination of stones that comprise the Gabions and the adjacent Carex provide habitat for lizards and skinks.

Rain Garden (Carex)

Ryan James Aldrich

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Rain Water Tank

Ryan James Aldrich

The Rosebank area is highly developed. It is most-ly industrial and commercial property such as the BLUM NZ site. The main form of transport is by personal car. The result of this urban trend is large areas of impervious surfaces. Concrete dominates the area. This is damaging to the environment as large amounts of storm water runs off into the ad-jacent water bodies. The water is untreated and con-tains pollutants. With further urbanisation and the resulting storm water increases additional pressure is placed on storm water systems.

Understanding of context of the BLUM NZ site along with the principles and components of Low Impact Urban Design and Development drove the design of storm water management and treatment devices. The storm water devices selected are spe-cific for the condition and requirements of the site. They have been designed specifically for their loca-tion and to work as a system or a treatment train. Ultimately the devices designed for the site are capa-ble to treat all storm water on site. The storm water devices also offer other ecological benefits such as providing habitat and temperature reduction.

Works CitedAmerican Jornal of Scientific Research. (2011). Effect of Impervious Areas in Discharge Simulation by H2U and Storm Water Management Model. Euro-Journals Publishing, Inc.

Auckland Regional Council. Rain Garden Facts, Rain Gardens What is the purpose of a rain garden.

Kingston City Council, Melborne. (2011, 11). Water Sensitive Urban Design, Case Studies & Technical Reports. Retrieved from City of Kingston: http://www.kingston.vic.gov.au/page/PagePrint.asp?Page_Id=1429

Landcare Research. (2011, November 11). Low impact urban design & devel-opment (LIUDD), What is low impact urban design and development or LI-UDD? Retrieved November 2011, from Landcare Research: http://www.landcareresearch.co.nz/research/built/liudd/

Marjori, v. R., & Hanri, v. R. (2009). Low Impact Urban Design and Develop-ment: the big picture. University of Auckland, Landcare Research Science Series No.37. Lincoln: Manaaki Whenua Press, Landcare Research.

Marjorie van, R., & Henri van, R. (2005). Low Impact Urban Design and De-velopment Principles for Assessment of Planning, Policy and Development Outcomes, Working Paper 051 CUES Working Paper Series. CUES, Centre for Urban Ecosystem Sustainability.

Mortimer, C. (2010 , November 12). Stories/What on Earth is LIUDD. (L. R. No, Producer) Retrieved September 2011, from Our Futre: http://www.ourfu-ture.net.nz/Stories/21

Ryan James Aldrich

APPENDIX

Ryan James Aldrich

2 year rainfall

Run off depth mm (based on 2 year avrage) Runoff Volume Q = (P-Ia)2 / (P − Ia) + S V24 = 1000*Q24*AQ = 0.166123054 V24= 102764.1452Q24= 57.09119178

P (rainfall depth mm)P = 2 to 5 year 24 ARI / 24from figure A.2 tp108 for 2 to 5 24h ARI:2 to 5 year 24 ARI = 82P = ARI / 24 = 3.416666667

Ia mm (initial abstraction)Ia (weighted) = 5*perious area / total areapervius area = 342.7Ia= 0.955447753

S mm (potentail soil storage)S= (1000/CN-10)25.4S= 34.00330791

CN weightedSCS Hydrological Soil Group: cover description curve number area CN * Area (CN Product)from table 3.2C Impervious 98 1,450.70 142168.6C rain garden 45 304.3 13693.5C grass with trees 60 38.4 2304

1,793.40 158166.1 totalCN weighted = total CN product / total areaCN Weighted = 88.19343147

Land Cover

total area m2

total area: 1,793.4impervius

drivway footpath paving road roofs123.50 1.9 4.1 95.3 458.90

177 3.9 5.4 248.50295 15.2 22.9

total: 594.60 21 32.4 95.3 707.4

total impervious: 1,450.70

total area m2

perviousrain gardens grass with trees

77.3 38.488.41.93.7

16.454.118.643.9

total: 304.3 38.4total pervious: 342.7