Urban Ecology

FROM ROOF TO SEA

Urban Ecology Land7401

Semester 1 2012

Kieran Dove1346290

14th June 2012

Leslie Haines

Application of LIUDD techniques for a sustainable development

Contents:

Introduction - What is LUIDD 2-3 The Site 4

Water Direction 5

Site Quantification 6-7 Device Calcutations 8-26

Justification 28-30

Application 31-34

Conclusion 41

References 42

What is LIUDD?

The principles of LIUDD have been developing over many years in other countries such as Australia and Canada, but NZ has been a bit slower to catch onto this method. Since the early 1990’s NZ has been developing low impact and water sensitive urban design techniques to help deal with human impacts on natural processes. Though one of the aims is to deal with human impacts, it also incor-porates protection of aquatic and terrestrial integrity, minimize infrastructure costs and aims to avoid a wide range of adverse affects from conventional development (Landcare Research, 2009). The underlying driver behind LIUDD is that to be sustainable we must recognize the limitations of ecosys-tems and that we must adjust our activity as humans to be within the ecosystems limitations.

Overview:

LIUDD can be broken up into several hierarchy of principles ranging from Primary – Secondary – Tertiary – Sub-principle, my particular focus discussed below will be on the Primary and Secondary. The Primary focus of LIUDD is to work with nature’s cycles on a catchment basis to maintain the integrity and mauri of ecosystems and the Secondary’s being (1) Effect/impact minimization through site selection (2) Efficient use of ecosystem services and infrastructure (3) Maximize localization of resource use and waste minimization (van Roon & van Roon, 2009), followed by identifying some LIUDD concepts.

Primary Principle:

Through the knowledge of cyclical systems, a research assessment of the site’s water, soil, plant nutrients, contaminants, organisms, energy and several other systems can help designers and urban developers work within nature’s cycles. LIUDD works within ecological limits and try’s to manage hu-man activity appropriately to make it fit within these limits. The single primary principle seeks recog-nition that human activity should respect and operate within natural cycles (van Roon and Knight, 2004) in order to minimize negative effects and optimize catchment internalization of materials, con-taminants and energy.

Secondary Principle:

When selecting sites for LIUDD, the long term and the bigger picture come into consideration (van Roon, van Roon, 2009). The selection of a site is dependent on many factors, such as cultural/natural significance, cost affective areas, option to develop outside of the originally chosen area and effec-tiveness of using LIUDD. Van Roon states that all the designs, plans and policies cannot equate to a lost treasure, though enhancement of the environment in urban areas will still benefit from LIUDD. Ecosystem services play an important role in LIUDD, with the enhancement of already existing eco-systems such as motorway corridors, which act as migration corridors and help clean road run off in some cases. Maximizing resources and minimizing waste has been a very important principle in recent times, with councils creating laws to include a rainwater catchment system in all new houses. By doing so can create onsite water storage and decrease the need to get water from off-site. Rather than allowing contaminated water to run freely into our natural streams, devices are installed such as rain gardens, which naturally filters out the contaminants.

Introduction:

Concepts:

LUIDD has several key concepts that it follows, from working with nature, avoiding or minimizing impervious surfaces, minimizing earthworks, utilizing vegetation to assist in trapping sediment and pollutants. With the overall aim in reducing energy use, material, and waste in the urban develop-ment. This is accomplished through the understanding of natural process and integrating them into our developments (Mortimer, 2010).

Design, Amenity and Biodiversity:

LIUDD methods have many other outcomes and functions such as been used as a design tool, an amenity creation tool and of enhancing of biodiversity. Raingardens, swales, biofiltration ponds, reten-tion ponds, wetlands, soakpits, permeable pavement and many more design techniques are used in different stormwater situations to achieve the desired outcome of less that 15% ‘effective’ impervi-ous surface area. These design techniques in combination with one another create treatment trains, which are series of devices linking sites in a catchment, to capture, slow and treat rain runoff (Van Roon, Van Roon, 2009). Amenity value is a very highly sort after function of any design, with people always wanting to see something beautiful aswell as being functional. Native planting is one of the creators of this amenity value with plants such as Apodasmia similis and Carex secta/virgata used as amenity plants which also are used in collecting sediment and pollutants that helps clean the water. Biodiversity is about the variety of species in ecosystems, both native and exotics are used in LIUDD. The design and implementation of native planted green corridors along streamside’s helps with this biodiversity, creating places here native flora can use and feed from.

References.

Mortimer, C. (2010), Stories/What on Earth is LIUDD. (L. R. No, Producer) Retrieved May 2012, from Our Future: http://www.ourfu- ture.net.nz/Stories/21

Marjorie, v. R., & Hanri, v. R. (2009). Low Impact Urban Design and Development: the big picture. University of Auckland, Landcare Research Science Series No.37. Lincoln: Manaaki Whenua Press, Landcare Research.Landcare Research, (2009). Low Impact Urban Design & Development (LIUDD), Retrieved May 2012, from http://www.landcareresearch.co.nz/research/built/liudd/van Roon, M. R. and S. J. Knight (2004) Ecological Context of Development: New Zealand perspec-tives. Oxford University Press. Melbourne.

The Site:

LegendMedium Density

Apartments

Terraced Housing #1

Terraced Housing #2

River

Wetland Park + Revegetation

Fig 1 - Kaukapakapa subdivison (Dove, K. 2011)


Apartments

Terraced Housing #1

Terraced Housing #2

River


Water Direction:

Devices Used: -Rain Garden -Swales -Revegetation -Living Garden -Permeable Paving -Infiltration Trench -Wetland Pond -Rain Tanks

Fig 2 - Ridges + Contours (Dove, K. 2011)

Quantifications:

Total Extent Excluding Wetland Park - 54.5ha

Housing:

Med Density – 115,682m² is 231 Houses. @ 500m² each plot with a 250m² footprint and 80m² of Driveway + Paths. Total of 7.6ha of impervious surface.

Terraced Housing #1 – 68,571m² is 275 houses. @ 250m² each plot with a 100m² footprint + 60m² of Driveway and Paths. Total of 4.4ha of impervious surface.

Terraced Housing #2– 41,704m² is 139 terraced houses @ 300m² each plot with a 150m² footprint + 70m² of Driveway + Paths. Total of 3.05ha of impervious surface.

Apartments – 6,882m² is 9 apartments @ 750m² each plot with a 500m² footprint and 150m² of Driveway + Paths. Total of 0.58ha of impervious surface.

Total Housing - 15.63ha

Roads:

4.7ha (20m Wide Road) + 1.8ha (14m wideRoad)

Total Roading - 6.5ha

Green Space:

Stream Buffers - 24.75ha

Medium Density - 231 Lots with 170m² left over after removing impervious surfaces. -231 x 170m² =3.93ha

Terraced Housing #1 - 275 Lots with 90m² left over after removing impervious surfaces. -275 x 90m² =2.475ha

Terraced Housing #2 - 139 Lots with 80m² left over after removing impervious surfaces. -139 x 80m² =1.12ha

Apartments - 9 Lots with 100m² left over after removing impervious surfaces -9 x 100m² =0.09ha

Total Green Space - 32.365ha

Extent Quantifications:

Extent - 54.5ha

Housing + Roads = Impervious Surface

Green Space = Pervious Surface

Housing + Roads =15.63 + 6.5 = 22.13ha Impervious Surface.

Calculating Site Impervious %

-22.13 / 54.5 =0.406 x 100

=40.6% Impervious Surface

=59.4% Pervious Surface

Total Volume of Water of Site:

Aeff - Catchment effective first flush runoff area Aeff = (Impervious % ÷ 100) x Total Area (ha) = (.406) x 54.5ha = 22.13 ha dff - First flush water quality depth - 1/3 of 2-year 24-hour storm (TP 108) Rainfall depth for Kaukapakapa = 80mm (see appendix 1) *Therefore 1/3 of rainfall depth - dff = 27mm

Vff- first flush volume Vff= 10 x Aeff x dff (m

3) = 10 x 22.13 x 27 (m3) = 5,975.1m3

WQV - water quality volume WQV = Vff + 30% buffer for additional control WQV= 5,975.1m3 + 30% = 7,767.63m3

Total Volume of runoff water to be dealt with by my chosen devices = 7,767.63m3

Suspended - Solids Reduced light levels, and smothering of the bed substrate (when suspended solids settle out). Increased Biochemical Oxygen Demand (BOD) from organic materials.

Nutrients - Nuisance plant growth (if no other fac tors are limiting), and increased BOD.

Hydrocarbons- Oxygen depletion of waters (Chemical OA),gen Demand, COD) .

Metals - Impact on the physiology of plants, chronic and acute effec ts on animals.

Microbes - Potential impacts on human health.

Contaminants:

Medium Density Housing :

Treatment Devices: -Living Roof -Infiltration Trench -Permiable Paving Living Roof:

Roof Area = 250 m2 (0.025ha) Impervious % = 100%

Total Volume of Water:

Aeff - Catchment effective first flush runoff area Aeff = (Impervious % ÷ 100) x Total Area (ha) = (1) x 0.025ha = 0.025 ha dff - First flush water quality depth - 1/3 of 2-year 24-hour storm (TP 108) Rainfall depth for Silverdale = 80mm (see appendix 1) *Therefore 1/3 of rainfall depth - dff = 27mm


3) = 10 x 0.025 x 27 (m3) = 6.75m3

WQV - water quality volume WQV = Vff + 30% buffer for additional control WQV= 2.7m3 + 30% = 8.7m3

70% of WQV is treated on the living roof. *Therefore WQV = 70 % of 8.7m3 = 6.1m3

30% of water from living roof is runoff. *Therefore Vff = 30% of 8.7m3 = 2.6m3

Total Volume of runoff water to be dealt with by another device = 2.6m3

Site Calculations:

Infiltration Trench:

For Living Roof Runoff of Medium Density Housing:


Rainfall depth for Silverdale = 90mm (see appendix 1) *Therefore 1/3 of rainfall depth - dff = 27mm

As - Surface Area of the Trench (m2) As = WQV/((fd)(i)(t)-p)

As = surface area of the trench (m2) WQV = water quality volume (m3) = 2.6m3

fd = infiltration rate (m/hr) - rate reduced by 1⁄2 from measured -14mm from table C9 (1/2 = 0.007m/hr) i = hydraulic gradient (m/m) - assumed to be 1 t = time to drain from full condition (hours) - time 48 hours p = rainfall depth for water quality storm (m) = dff = 0.027m

As = 2.6/((0.007)(1)(48)-0.027) = 2.6/0.309 = 8.41 m2

Calculate the maximum trench depth

dmax = fd(t/Vr)

Where:

dmax = maximum depth of trench fd = infiltration rate (m/hr) = 0.007 m/hour t = time to drain from full condition (hours) = 48 hours Vr = void ratio of reservoir stone (scoria) = 0.5

dmax = .007(48/.5) = 0.67 m Find the trench volume

Vt = 0.37(WQV + pAs)/Vr = 0.37(2.6 + 0.027(8.41)/.5 = 2.09 m3

Calculate the trench depth and compare with the maximum depth d = Vt/As = depth of trench (d) = 2.09/8.41 = 0.25 m

d < dmax = 0.25m < 0.67m so the design is adequate

Total Volume of runoff water to be dealt with by another device = 0m3

Medium Density Housing: Permeable paving:

Impervious Surface = 80 m2 (0.008ha) Impervious % = 100%




3) = 10 x 0.008 x 27 (m3) = 2.16m3

WQV - water quality volume WQV= Vff + 30% buffer for additional control WQV= 2.16m3 + 30% = 2.8m3

Total Volume of water filtered and treated through Permeable Paving 100%

Total Medium Density Housing Permeable Paving Dealt with:

-Total # of houses x (Driveway+Paths) =Total permeable paving treated

-231 x 80m2

=18,480m2 of Driveways and Paths

-231 x 2.8m3

=646.8m3 Total treated by Permeable Paving.


Terraced Housing #1:




Aeff - Catchment effective first flush runoff area Aeff = (Impervious % ÷ 100) x Total Area (ha) = (.1) x 0.01ha = 0.01 ha dff - First flush water quality depth - 1/3 of 2-year 24-hour storm (TP 108) Rainfall depth for Silverdale = 80mm (see appendix 1) *Therefore 1/3 of rainfall depth - dff = 27mm


3) = 10 x 0.01 x 27 (m3) = 2.7m3






For Living Roof Runoff of Terraced Housing #1:






As = 1.05/((0.007)(1)(48)-0.027) = 1.05/0.309 = 3.4 m2


dmax = fd(t/Vr)

Where:



Vt = 0.37(WQV + pAs)/Vr = 0.37(1.05 + 0.027(3.4)/.5 = 0.85 m3

Calculate the trench depth and compare with the maximum depth d = Vt/As = depth of trench (d) = .85/3.4 = 0.25 m



Terraced Housing #1: Permeable paving:





3) = 10 x 0.006 x 27 (m3) = 1.62m3




-Total # of houses x (Driveway+Paths) =Total permeable paving to be treated

-275 x 60m2


-275 x 2.1m3



Terraced Housing #2:






3) = 10 x 0.015 x 27 (m3) = 2.7m3






For Living Roof Runoff of Terraced Housing #2:






As = 1.2/((0.007)(1)(48)-0.027) = 1.2/0.309 = 3.9 m2


dmax = fd(t/Vr)

Where:



Vt = 0.37(WQV + pAs)/Vr = 0.37(1.2 + 0.027(3.9)/.5 = 0.97 m3

Calculate the trench depth and compare with the maximum depth d = Vt/As = depth of trench (d) = .85/3.9 = 0.25 m



Terraced Housing #2: Permeable paving:





3) = 10 x 0.007 x 27 (m3) = 1.89m3


Total Volume of water filtered and treated through Permeable Paving is 100%


-Total # of houses x (Driveway+Paths) =Total permeable paving to be treated

-139 x 60m2


-139 x 2.5m3



Apartments:

Rain Tank:

Peak Flow Consideration- With my 5 storey apartment, an avg of 3 people per family was used to give a daily use of 325L and a total of 1625L a day for the building, this required a extrapalation of the data from the data below. This was done by addind a 1000L, 500L and a 125L together to get a tank size adequate for the site.

So, 60% + 30% + 5% = 95% as fraction of rainfall used.

% of rainfall becoming runoff = 1 – (0.75 x fraction of rainfall used)

0.75 is the percentage of the time that the water tank is full due to excess rainfall. 1-(.75x.95) =1-0.72 =0.28 = 28% runoff.

With a Dual tank system, there will be sufficient water for the 5 storey apartment.

With the 28% runoff from the rain tanks. They will be filtered through a small infiltration trench beside the rain tanks.

Fig 3 - Rain Tanks use (“Rain Tanks”, 2010)


Apartments: Permeable paving:

Impervious Surface = 150 m2 (0.015ha)Impervious % = 100%




3) = 10 x 0.015 x 27 (m3) = 4.05m3



Total Apartment Permeable Paving Dealt with:

-Total # of apartments x (Driveway+Paths) =Total permeable paving treated

-9 x 150m2


-9 x 5.3m3



Dealt With Runoff:

Starting off Runoff volume - 7,767.63m3

With the design of -LivingRoofs -Infiltration Trenches -Permeable Paving -Rain Tanks

I was able to calculate a 0% runoff of all the housing types through a combination of the devices stated above.

Calculations:

Total Medium Density impervious surface runoff volume to deal with- 11.5m3

Devices Effectiveness: -Living Roof - 6.1m3

-Infiltration Trench - 2.6m3

-Permeable Paving - 2.8m3

Total Effective Runoff Dealt With - 11.5m3 x 231 houses = 2,656.5m3

Total Terraced Housing #1 impervious surface runoff volume to deal with - 5.6m3




Total Effective Runoff Dealt With - 5.6m3 x 275 houses = 1,540m3

Total Terraced Housing #2 impervious surface runoff volume to deal with - 6.53m3




Total Effective Runoff Dealt With - 6.53m3 x 139 houses = 907.67m3

Total Apartment impervious surface runoff volume to deal with - 22.9m3

Devices Effectiveness: -Rain Tank - 17.6m3


Total Effective Runoff Dealt With - 22.9m3 x 9 apartments = 206.1m3

New Total Volume of runoff water to be dealt with after onsite removed =2,457.36m3

Park Front Roads: Version 1

Rain Gardens:




3) = 10 x 1.8 x 27 (m3) = 486m3

WQV - water quality volume WQV= Vff + 30% buffer for additional control WQV= 486m3 + 30% = 631.8m3

Calculate the required surface area of the rain garden.

Arg = (WQV)(drg)/k(h+drg)trg

Where: Arg = surface area of rain garden (m2) WQV = water quality treatment volume (m3) drg = planting soil depth (m) k = coefficient of permeability (m/day) h = average height of water (m) = ½ maximum depth trg time to pass WQV through soil bed The following values should be used. drg = 1.0 metre k = 0.5 m/d h = 0.15 m (maximum water depth 300 mm) trg = 1.0 days

Arg =631.8(1)/0.5(0.15+1)(1.0)

= 1,098.78m2 Of Rain Garden required to clean 631.8m3 volume.

This figure of 1,098.78m2 used along the edge of the wetland park in sections none larger then

Park Front Roads: Version 2

Rain Gardens:




3) = 10 x 1.8 x 27 (m3) = 486m3

WQV - water quality volume WQV= Vff + 30% buffer for additional control WQV= 486m3 + 30% = 631.8m3

Using Paul Matthews Place rain garden as a case study, I calculated that it was 20% of the subcatchment so a 1:5 ratio was used on the site. Using that ratio for my site I can calculate that the 18,000m2 road will need 3,600m2 of rain garden to treat the contaminants that it will runoff into the wetland park.


Apartments

Terraced Housing #1

Terraced Housing #2

River


1

2

3

45

5 sites are identified by the ridges of the site. These sites are varying in size and constrution of the roads determines which way the runoff will be flowing. The roads will be lined with swales and stormwater dispersal pipes that help disperse the runoff evenly across a revegetated area.

Fig 4 - Catchment Section (Dove, K. 2011)

Bush Revegetation:

Section 1: -14,193m2 of road =14,193 x 5 =70,965m2 of Bush is required.





Total bush required to treat all roads is 23.4ha.

Fig 5 -Revegetated Ratio (“Bush Revegetation”, 2010)

Final Total Volume of Runoff Water:

Old Total Volume of runoff water to be dealt with after onsite removed =2,457.36m3

Removal of Waterfront Park Road WQV = 631.8m3

Removal of Main Road WQV = 1,649.7m3

New Total Volume of runoff water to be dealt with = 175.86m3

Giving the site a 2.2% effective runoff rate.

With the incorporation of the wetland ponds and the uncalculated swales along the roads, there is a little discrepency of the New Total Volume of 175.86m3

Secondary Roads:

At this development stage not all quantifications are finalised, with roads to be built through the housing areas which I have not yet developed. This will effect my overall impervious % figure aswell as the total volume of effective runoff that needs to be treated over the site.

The stormwater device which will be treating these future developments of the roading system will be porous asphalt. With its 100% self mitigating characteristic, it is the optimum device without creating further infrastucture on the site. Porous asphalt is an open graded misture of coarse and fine aggregates, mineral filler and a bituminous based binder.

Also creating porous asphalt roads it will decrease speed and the roads won’t need to be as wide which will help decrease contaminants.

Fig 6 - Porous Asphalt example (“porous asphalt”, 2012)

Living Roofs:

Living Roofs were chosen due to its effectiveness of both water quality and quantity attritbutes. By planting an extensive living roof on all medium and terraced housing roofs, this will help take out all contaminants of the water and through evapotranspiration and absorbation there will only be a 30% runoff rate from all Living Roofs.

With a total area of 10.61ha of Living Roofs covering 645 houses and will treat 70%, it being 2,606.9m3 of water, which is a very large portion of the sites overall effective runoff volume of 7,767.63m3. With the implementation of these Living Roofs, it will create a large stepping stone for bird life and a large habitat for other insects, reptiles and will likely have several intruding species of plants as time goes on.

Further reseach would be taken into consideration of using an intensive roofing system, as it being a larger/heavier Living Roof which can handle large shrubs growing on it maybe the large grown plants will take up more water and evapotranspiration will occur faster. Thus assuming that the larger substrate medium and larger plants would take up more water and less than 30% would be calculated as runoff, this could be an option to further develop buildings to withstand the structural requirements for an intensive Living Roof.


The infiltration trench was chosen as the second device in the treatment train for onsite treatment. This was due to its characteristics not to treat water quality but to treat volume instead. This was useful in my design as the Living Roof removed all contaminants from the water before it hits the ground surface and it was then clean enough to be funnelled into the stream directly.

Due to the clay soil of Kaukapakapa, the infiltration trench couldnt let the water leach back into the groundwater, so it has to be redirected using stormwater pipes back into the local streams. This was done for all infiltration trenches on the sites. For amenity value and biodiversity, the trenches could be planted on with suitable plants or if wanted could just be grassed over. The plants would though create a habitat for insects and other animals that may use the vegetation as cover, a home or shade.

Permeable Paving:

Permeable paving was a very easy decision as a substitute for concrete due it its 100% self mitigating and visual appearance. Permeable paving has its limitations though, it won’t take runoff from other surfaces. It treats water by infiltrating into the groundwater or piping, filtering out contaminants and sedimentation control.

Justifications:

Rain Garden:

Rain gardens are a very effective device, with it slowing down waterflow, reducing volume and increasing water quality all at once. The selection to use a rain garden along the edge of the wetland park was due to the large road which it was catching runoff from. The road along the park is 1.8ha in size and as the river in the wetland park comes close to the road in some places, the need to clean, slow and reduce the water was essential.

The size of the rain garden is 3,600m2 but it will be split up into smaller catchments relevant to the road and where the walkways to the wetland park are. With the road being 1.6km long, a break every 160m is a sufficient length betwen paths so the rain garden can be broken up into 10 lots of 360m2 each. The road will be designed to help guide runoff into these lots, with the road camfering at certain points to help direct runoff.

With The case study of Paul Matthews Place rain garden being an efficient enough size rain garden to treat the water it collects, I can assume that all the water off the road will be cleaned enough to enter the stream with no contaminants in it.

Wetland Pond:

With the wetland park being an educational and operational park, it will have a series of wetland ponds, grassed areas, boardwalks, rain gardens and swales scattered appropriately over the park. These devices will act as an amenity value for the community aswell as a stormwater device. With no caluclations done for the park, assumptions are made that with a treatment train within the park itself will be more than enough to clean any runoff that enters the park from the subdivision.

Rain Tanks:

My apartments are 5 storey developments where I wanted to use the water collected for the gardening, laundry and the toilet. With a total of 325L a day used per storey, a series of rain tanks was needed to attain the water needed by the building. This ment 3 x 25,000L tanks with a infiltration trench/swale for the overflow runoff, which calculated out to be 29%. This 29% could also be used for other purposes or sent away to other sites for use. The dual tank system is a very useful design feature of the apartment area, with taking the pressure of needing water from water mains.

Swales:

Swales were to difficult to calculate so a ratio was used for the design of them. The use of swales was mainly round the roading system. With the clay bedrock below being not porous enough for water to drain, the swales had to have stormwater drains built in below them. These pipes directed water off site and dispersed into the bush revegetation areas along the stream edges and then to the streams.

Swales were designed to be a length of 30m at a time before a break was needed, slope over 4 deg were unbuildable and consideration of a different device was needed. Swales provide a habitat for insects, lizards and birds along with a visual amenity.

Treatment Train:

The key principle is to use plants and substrates to detain, filter and reduce the amount of stormwater and suspended contaminants moving across a landscape (Dunnett & Clayden 2007). A treatment train is therefore a series of elements or devices linked together in the landscape. they are arranged top down from living roofs to rain tanks and moving onto roads with swales and rain gardens, just to name a few. These devices lengthen and slow the passage of water before reaching the ocean.

Living Roofs:

Living Roofs are a roofing system that offer a range of benefits not provided by convential roof systems, by introducing vegetation to areas previousy impervious this creates a heavily reduced runoff rate of the site. The vegetation cover has many benefits that traditional roofs don’t have, not only does it mimic the natural environment but filters the rain through the soil and capturing some to evapotranpire later. This infiltration and filtering technique helps to limit the quantity and increases the quality of water being deposited into the local river system. Living Roofs have several key objectives that I want to incorporate into this Subdivision. -Stormwater reduction, retention, transpiration and filtration. -Cost saving on heating and air conditioning to the indulating effect of the growing medium and plants. -Protection of the roof from UV damage. -Moderation of the urban heat island effect. -Provides a habitat for insects, birds and even lizards. -Noise reduction (inside the building).

The size of the Living Roof is dependent on several factors, as of the course of this assignment I wont be able to fully calculate. But some assumptions will have to be made, them being; the supporting bearing beams of the building determine if the roof can hold up the Living Roof, the slope of the roof, whether of not the roof has a skylight in it. I have chosen to use Living Roofs on all my residential houses excluding my apartment blocks, this was because for my apartments I want to have gardens for them so the rain collected from the roof will be used to water the garden all year round.

For the successful construction of a Living Roof, not only a Engineer is involved, this process includes ecologists, architects, hydraulic engineers and ofcourse the Landscape Architect. Considerations from each of these professions will help to construct a sustainable Living Roof.

The Living Roof construction constists of layers of materials, these are; -A waterproof membrane -A root barrier -An insulation layer (optional) -A drainage layer -Filter fabric -The engineered growing medium or soil substrate -The plant material -Usually some form of biodegradable wind blanket, such as a jute or coco liner-type mesh, is placed over the new plants to stablilise establishing roots.

Application:

The waterproofing layer consists of a liquid-applied membrane. I believe the liquid-applied membraneprovides a superior waterproofing and easier maintenance. Every Living Roof must have a drainage layer to carry away excess water. Drainage capacity must increase closer to the rainwater outlets, so a separation barrier 500 mm wide of large rounded pebbles should be installed along the eaves and near outlets. Additionally, a shallow layer of gravel or pebbles placed approximately 400mm from the outside perimeter of the roof is recommended, providing additional drainage, fire control and access to the roof for maintenance. The Living Roofs will be an extensive (thin) Living Roof which will feature drought tolerant plants that will grow in a thin layer 100mm of light weight soil, this weight will be less than 150 kg per m2.

Shallow rooted and light weight plants are important in the selection for the coverage of the roof, due to the weight bearing beams. Good regenerative qualities, for an effective pervious cover and to increase the biodiversity of the site. As this site lies on a coastal edge the wind is a major problem contributing to the choic e in drought tolerant, sun/shade exposure, rainfall and humidity.

Below are a list of some plants suitable for the site to coupe with a range of factors: -Crassula sieberiana, sand convolvulus -Oxalis exilis, NZ iceplant -Epilobium brunnescens -Epilobium nummulariifolium, sea spurge -NZ linen flax, knobby clubrush -Lachnogrostis spp., Leptinella dioica -Leptostigma/Nertera setulosa -Libertia peregrinans -NZ groundsels, -Pimelea prostrata

Biodiversity is a key aspect with this design and use of Living Roofs, to create links that were identified in the first part of this research, the creation of Living Roofs provided a stepping stone across Kaukapakapa and further towards the “Green Heart”, which is known as Riverhead Forest. This device has been designed to mimic natural and local habitats for te benefit of the birds, insects and lizards that might find there way onto these Living Roofs.

-Cotula coronopifolia, -Acaena microphylla, danthonias -Festuca coxii -Selliera radicans -Pimelea prostrata -Coprosma petriei -Festuca coxii -Coprosma acerosa -Muehlenbeckia axillaris -Libertia ixioides

Fig 7 : Living Roof Construction Fig 8 : A grown Living Roof

-Cotula coronopifolia, -Acaena microphylla, danthonias -Festuca coxii -Selliera radicans -Pimelea prostrata -Coprosma petriei -Festuca coxii -Coprosma acerosa -Muehlenbeckia axillaris -Libertia ixioides

Infiltration Trenches:

Infiltration trenches are direct urban stormwater devices that direct the runoff into the underlying soil. This method is in contrast with the detention methods which detains water but it eventually reaches the stream systems, with infiltration trenches it diverts the runoff into the groundwater directly. Infiltration trenches were chosen due to its characteristics of volume reduction rather than water quality treatment. In combination with a Living Roof, which will be the primary contaminant removal device of the water before it comes out of the downpipes and directed into the groundwater system.

When designing a infiltration trench several considerations must be looked at, primarily to stream baseflow augmentation and stream erosion protection by reducing the total volume of runoff.

Infiltration trenches function as a passage of water from the surface into the ground, for this device to work effectively it depends on the following: -Permeability Rates -Sufficient depth to groundwater or bedrock. -Influent concentrationf that would not cause clogging or a theat to local groundwater quality.

The size of infiltration trenches is designed around the flow of water through the porous media, in my design I used scoria in all cases. This approach relies on Darcy’s Law (1856) (Countryside Living, 2010). By calculating surface area of the trench I was able to calculate a suitable minimum and maximum depth of scoria needed for a adequate design.

Infiltration trenches don’t offer much to biodiversity or amenity value, with a thin layer of surface gravel preventing much planting. Amenity value could be incoroporated with a long line of surface gravel along side the wall to help create a barrier between the permeable paving and wall, this could create a suttle edge to visually handle.

Fig 9: Infiltration Trench Detail. Fig 10: House with Infiltration Trench

Permeable Paving:

Permeable Paving is a very effective device in minimising runoff, with a 100% mitigation effect it is one of the more diversely used devices. It can be used in several scenarios from paths, decks, driveways and carparking areas. The device assists with stormwater and design proposals by removing the contaminants by filtration, allowing absorption, microbiological and settlement.

For my individual sites of my subdivision, all my paths and driveways will have permeable paving designed with a series or different styles such examples are pervious paving include paving blocks (numerous shapes and sizes), plastic grids that allow grass growth between the plastic, pervious concrete and pervious asphalt.

One of the main reasons I choose to use permeable paving instead of treating the runoff from the driveway/path offsite was due to it does not require a larger area than what the original driveway/path was going to be. Another was the soil condition below, as they do not constrain the use of permeable paving, although they do determine whether an underdrain is required. When designing permeable paving the slopes must be less than 10%. manufacturer’s specifications must be followed for any system installed or by a registered engineer.

Permeable paving material specification vary according to the specific pavement product selected, but for my design I have chosen plastic reinforced grid pavers which have only a few layers of materials listed below: - Pervoius Material -Bedding Layer -Resorvoir Layer -Drainage (if required) -Filter Layer.

The reason for the large % of Reservoir layer is required to support the structural load of the cars and other objects that will be ontop of the pavement.

Fig 11 - Eco-friendly paving (“eco-paving, 2012) Fig 12 - Permeable Paving (“permeable Paving”, 2012)

Planting within the cracks of the eco-friendly concrete is possible and easy to maintain, with small groundcovers between the cracks it will help control the water as it goes through the paving areas. The planting is very minimal in this area of the garden, with only small grasses/groundcover such as mondo grass (Ophiopogon planiscapus ‘black dragon’) shown below, aswell as other groundcover such as Selleria radicans and dichondra in combination with the plastic grid and the eco-friendly concrete.

This creates a very small habitat for animals to utilize comapred to other devices on the site. With a very small amount of insects likely living amongst the groundcover, this design choice offers a more amenity aspect with plain boring walkways of concrete being transformed into colourful walkways of mondo grass and selliera amongst the cracks.

Fig 13 : Construction of Permeable Paving. (VTC, 2010)

Fig 14 - Mondo grass amenity Fig 15 - Dichondra planting

Revegetation:

Revegetation planting is a key design feature of my subdivision, with my the streams passing through the site a 50m buffer was given to it to help mitigate the runoff from the roads and housing lots. With the addition of newly revegetated areas alongside the current vegetation, the increased bush provides a larger core for the patch, so along with stormwater qualities, it also provides a very needed additional value for the patches health. There were several key considerations when choosing to revegetate instead of creating large open spaced areas along the stream sides with other devices to clean the water, they are: -Existing bush had the opportunity to extend -Slope was a indication that revegetation could treat the runoff effectively -Streams that were slowly dwindling away needed a protection mechanism, revegetation and offered this mechanism. -Enhancement of site characteristics were considered in the design stage.

Some benefits with choosing revegetation over other devices include, as the bush grows, maintenance needs slowly diminish, biodiversity and amenity value, acts as a windbreak and improves hydrological function over time.

Sizes required to clean a given area of impervious surface run on the ration of 1:6, with 1m2 of impervious will need 6m2 of revegetated bush to treat the run off. On my site with the vast stream system through the site and a 24.5ha revegetated buffer zone along the stream edge, this vast bush area can treat a large amount of impervious surface runoff throughout my site. With the right design features such as 30m long swales incorporated into the roads to act as channels to help guide the runoff to the revegetated. With other design ideas such as stormwater dispersal pipes that gather water from the road and are carried through these pipes to then be dispersed on the bush areas edge, shown below.

Fig 16 - Bush revegetation map (“Bush Revegetation, 2010)

Fig 17 - stream side cross section (“Bush Revegetation, 2010)

Rain Tanks:

Rain tanks are primarily a water quantity management device, with the intention to supply on-site water use. The use of the water caught by my rain tanks for my apartment blocks will be used for the sole purpose of garden maintenance, with watering the garden during droughts, it can also be used for temporary storage for the later distribution or sharing of excess water for other duties round the site.

The only source to fill the rain tank is from the roof of the apartment, with a 500m2 roof, a large amount of water will be gathered, so the installation of large rain tanks is necessary for my design. The roofing material will be a benign material, giving off minimal to none contaminants, making the water that enters the rain tank able to be used on gardens and to not pass onto any contaminants.

With the apartments being 500m2 the table above shows the options for the this type of roof area. Calculated in Part 2 showed a 13.5m3 effective runoff so with the selection of the rain tank, size and rate of usage was reviewed.

With a 3 x 25,000L tanks were selected per site, this size will be sufficient to take all water from runoff and provide a large enough storage for when the water isnt used. With the type of rain tank used, a overflow connection will be incorporated and will feed the main stormwater system, this overflow water can be used elsewhere on site or may be sent off site depends on the needs of other sites.

Biodiversity is not applicable to this type of device, but can be incorporated into surrounding shelterbelts, that may be designed to help hide or soften the view of the large tank. The tanks could be surrounded with shrubery and groundcover or could be surrounded with a vine like structure where fruit trees like grapes or peas could grow on, which would become a kind of community garden. Amenity value would be icluded in with the design of the vegetation cover of the rain tank, as the tank does not provide any sort of amenity value.

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Fig 18 - Section of Rain Tank - (“Rain Tank” - 2010)

Fig 19 - Rain Tank

Fig 19 - Rain Tank

Wetland Pond:

With the design of my subdivision, my site was built around a large floodplain with the intention of making this large flat area into a large wetland park. The floodplain has a large stream passing through it, which is where my sites runoff is heading to, so this wetland park had to be fuctional aswell as a recreational park.

Wetland and ponds are usually rich environemts of organisms with its diverse plant communities and sweeping landforms. For the wetland park the surface flow wetland is going to be the dominant stormwater device. It consists of a basin of varying depths with soil or other media to support the wetland vegetation and a water control structure that maintains water depth above the substrate. The water is treated as it passes though alternating zones of deep water and shelves of wetland planting.

Landscape amenity is a key aspect with the creation of wetlands and ponds, benefits of constructed wetlands impacting not only a visual amenity but can provide a wide range of eco-services such as heat moderation, noise reduction and phytoremediation and provide a place where people will enjoy going to. Pathways/boardwalks are usually incorporated into wetland ponds as it creates a tranquil experience walking through them for people and they are usually associated with open space so interactions will often occur. Education has become a popular addition to wetland ponds, with many new designs incorporating educational signs, posters, boards or even schools regularly visiting to learn about the ecosystems. Due to the man-made side to wetland construction, the landform can be adventerious, with manipulation of land to create hills, and other features along with planting design giving the user a different experience round every corner as plants vary in height, size and combination.

Fig 20 - Wetland Pond Section (Arc, 2010)

There are a wide range of plants that can grow in wetland environments, ranging from groundcover to trees. There is a wide range of plant lists for wetland planting in NZ, with the different planting zones along in a wetland there is a very large number of species that can survive in a wide range of conditions. Some plants can be: -Baumea tenax -Ficinia nodosa -Isolepsis prolifer -Polygonum salicaifolium -Carex virgata/lessoniana -Elocharis acuta -Apodasmia similis -Astelia grandis -Baumea articulata -Typha orientalis -Juncus pallidus

Wetland ponds create a new habitat for fauna, when designing wetlands the designer can design for the animals that will be using the site, with the use of logs to create habitats for lizards or rock crevasses along the edge of the pond which will accomodate fish species. Water birds will be a frequent visitor to the site with vast areas of ponds where nests and hunting will likely occur, aswell as bush birds which will come to the site to eat the fruiting trees planted such as the cabbage tree or pururi aswell as nesting in the canopy of the taller trees.

-Cyperus ustulatus-Myrsine divaricata-Phormium tenax-Plagianthus divaricatus-Coprosma arborea-Laurelia novae-zelandiae-Libocedrus plumosa-Macropiper excelsum-Aristotelia serrata-Coprosma arborea-Olearia solandri

-Rhopalostylis sapida-Plagianthus regius-Vitex lucens-Azolla filliculoides-Baumea complanata-Blechnum minus-Bolboschoenus caldwellii-Amphibromus fluitans-Podocarpus totara-Pseudopanax arboreus-Geniostoma ligustrifolium

Fig 21 - Wetland ponds + Amenity ( ARC, 2010)

Conclusion:

The Kaukapakapa subdivision is located in a rural town Northwest of Auckland. The current township is right next to a large floodplain which is currently used as farming land for the locals. The development was driven round this idea of a large wetland park around the stream that passes through the site. The design consisted of terraced housing, medium density and apartment blocks scattered among a 54.5ha site with extensive stream buffers zones.

With increasing enviornmental awareness, we can change the way in which we manage stormwater, provide protection to our waterways, while avoiding major costs. By intergrating stormwater devices into the urban environment of this subdivision it will create opportunites for birds, insects, fish and will create a more desired place to be for people.

I approached the site by looking at the current way we look at subdivisions and by adopting the concept of a treatment train which introduces a wide range of stormwater devices that are linked together and will become a more effective system. For the purpose of this assignment I didnt include the Wetland Park due to its vast size and difficulty to calculate a accurate treatment train system.

I used a wide range of devices, from a Living Roof which fed a infiltration trench, permeable paving, rain tanks, rain gardens, swales, wetland ponds and bush revegetation. I feel that the types of devices I used were the most suitable for the particular intention. Many of the stormwater devices provide a high level of habitat for birds, lizards, insects, fish and plants that contribute to the urban biodiversity. Amenity value was a sought after function of many of the devices, with the wetland ponds providing a great amenity both dealing with stormwater and for the landscape, with an educational side, a relaxing side and eco-services.

The mix of plants that were chosen or listed are best fits for this floodplain near coastal site, they encourage biodiversity for the site and I feel the section of plants chosen filled the requirements to both act as amenity and to help hide the devices.

Mortimer, C. (2010), Stories/What on Earth is LIUDD. (L. R. No, Producer) Retrieved May 2012, from Our Future: http://www.ourfu- ture.net.nz/Stories/21

Marjorie, v. R., & Hanri, v. R. (2009). Low Impact Urban Design and Development: the big picture. University of Auckland, Landcare Research Science Series No.37. Lincoln: Manaaki Whenua Press, Landcare Research.Landcare Research, (2009). Low Impact Urban Design & Development (LIUDD), Retrieved May 2012, from http://www.landcareresearch.co.nz/research/built/liudd/van Roon, M. R. and S. J. Knight (2004) Ecological Context of Development: New Zealand perspec-tives. Oxford University Press. Melbourne.

Fig 1 - My own ImageFig 2 - My own ImageFig 3 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 4 - My own ImageFig 5 -Countryside Living Toolbox, 2010. Retrieved 13th June 2012 Fig 6 - http://international.fhwa.dot.gov/quiet_pav/images/fig2.jpg, Retrieved 13th June 2012Fig 7 -http://www.concreteconstruction.net/Images/1210_WOC-DN_soil1_tcm45-747049.jpg Retrieved 13th June 2012Fig 8 - http://www.concreteconstruction.net/Images/1210_WOC-DN_soil1_tcm45-747049.jpg Retrieved 13th June 2012Fig 9 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 10 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 11 -http://international.fhwa.dot.gov/quiet_pav/images/fig2.jpg Retrieved 13th June 2012Fig 12 - http://www.concreteconstruction.net/Images/1210_WOC-DN_soil1_tcm45-747049.jpgRetrieved 13th June 2012Fig 13 - http://vwrrc.vt.edu/swc/july2009updates/VASWMBMPSpec7PERMEABLEPAVEMENT_files/image004.jpgFig 14 - http://www.gardenexpress.com.au/images/P/Mondo_Grass_Dwarf_07-01.jpg Retrieved 13th June 2012Fig 15 - http://farm3.staticflickr.com/2696/4445934341_607f12f886_z.jpg - DOGFig 16 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 17 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 18 - Countryside Living Toolbox, 2010. Retrieved 13th June 2012Fig 19 - http://4.bp.blogspot.com/-DQP2UL5MkL4/TXdiWcFZn1I/AAAAAAAAACU/b-65TMXkkRM/s1600/IMG_1646.JPG Retrieved 13th June 2012Fig 20 - Lewis, M.; Simcock, R.; Davidson, G.; Bull, L. (2010). Landscape and Ecology Values within Stormwater Management. Retrieved 13th June 2012Fig 21 -Lewis, M.; Simcock, R.; Davidson, G.; Bull, L. (2010). Landscape and Ecology Values within Stormwater Management. Retrieved 13th June 2012

Reference:

Appendix 1:

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