Brendan Oversby Senior Sustainability Consultant TME … · Brendan Oversby . Senior Sustainability Consultant . TME . ... • Doris likes Yellow flowers Opportunities • Local Reference

Biofilter Design Principles – Wayne Edgeloe Town Planning Management Engineering

Brendan Oversby

Senior Sustainability Consultant

TME Town Planning Management Engineering Pty Ltd

2 Documents

Vegetation Guidelines for stormwater biofilters in the South West of Western Australia

Full research and practical guide

Vegetation Guidelines for stormwater biofilters in

the South West of Western Australia – Practice Note

Summary document – focus on ‘how to’

Why were the Guidelines produced ?

? Community Resource Centre, Busselton

Town Planning Management Engineering

Components of a typical system

Ref:

Parkfield POS Biofilter, Bertram


Perth Airport, Long Term Parking

Queen Street, Busselton: Road side biofilters

Bioretention Swales and Basins


Treendale, Australind

Wind and water borne sand/sediments

Guidelines attempt to provide a blueprint to vegetating

biofilters…….

Biofilters and the Role Plants play

Riverlea Estate, Bunbury

Biofilters and the Role Plants play


Cross section


Bioretention Systems- Main Components

• Inlet Zone and Structures, Sediment Trap

• Extended Detention Zone

• Vegetation – above ground function • Vegetation – below ground function • Filter Media

• Transition Layer

• Underdrainage

RESEARCH OUTCOMES Nutrient Removal by Plants &

Hydrological influences

Biofilter research outcomes and implications for practical design

23rd – 24th September 2014 Perth Emily Payne, Belinda Hatt, Tim Fletcher, Perran Cook, Tracey Pham

Stormwater Biofilters

UNSATURATED ZONE

TREATED STORMWATER

100mm Sub-surface Collection Pipe on 0% grade

DRAINAGE LAYER

Ove

rflo

w

Untreated Stormwater

Line

r

150 Gravel

300

300–500

50

200–500

Filter Media

Coarse Sand

Detention

TRANSITION LAYER

Collection pipe

SUBMERGED ZONE & CARBON SOURCE

Biofilter configurations

Infiltration

Role of the submerged zone • Support vegetation & function during drought

• Enhance N removal

• Greater species performance consistency

• Prolonged retention

www.huffingtonpost

http://www.huffingtonpost.com/jay-famiglietti/water-in-a-changing-climate_b_3582258.html

Why are plants important in biofilters?

Biofilter key components

Filter media Sand transition layer/s Gravel drainage layer

Plant roots

Vegetation

Microbes

Roles of plants in water treatment

Nutrient uptake

Conversion into organic forms

Return via litter

Provide carbon to drive microbial activity

Oxygenate the rhizosphere

Slow and disperse flow

Stabilise the media

Evapotranspiration loss

Maintain infiltration

uptake

Microbial community

Exudates

O2

Microbial community

Exudates

Additional benefits of biofilter vegetation Aesthetics

Green spaces

Human health

Microclimate

Economic

Biodiversity

Sporobolus virginicus

Cyperus gymnocaulis

Carex tereticaulis Poa

poiformis

Austrodanthonia caespitosa

Velvetene

Juncus kraussii

Melaleuca incana

Astartea scoparia

Gahnia trifida

Hypocalymma angustifolium

Buffalo

Dianella revoluta

Poa sieberiana

Soil only (+ moss)

Poa labilldieri Gahnia

sieberiana

Carex appressa

Allocasurina littoralis

Dianella tasmanica

Juncus pallidus

Hakea laurina

Leptospermum continentale

Buffalo

Sporobolus virginicus

Cyperus gymnocaulis

Carex tereticaulis Poa

poiformis

Austrodanthonia caespitosa

Velvetene

Juncus kraussii

Melaleuca incana

Astartea scoparia

Gahnia trifida

Hypocalymma angustifolium

Dianella revoluta

Poa sieberiana

Soil only

Poa labilldieri Gahnia

sieberiana

Carex appressa

Allocasurina littoralis

Dianella tasmanica

Juncus pallidus

Hakea laurina

Leptospermum continentale

Nitrogen removal performance

Removing nitrogen from stormwater

NH4+, NO3

-

Urban stormwater runoff

PLANTS

FILTER MEDIA and SOIL ORGANIC MATTER

MICROBES DNRA

N2O, N2

Denitrification

Nitrification

Leaching

Microbial exudation or death

Mineralisation

Bio

filte

r

Root exudation, litter or plant death

Uptake/ Assimilation

Organic Nitrogen

PON DON

Decomposition

Uptake/Assimilation

150 mm

100 mm gravel drainage

200 mm sand transition

300 mm loamy sand filter media

200 mm perspex ponding zone

Non-saturated

Non-saturated

Saturated zone + C source

Satu

rate

d zo

ne &

C

sour

ce

Total Nitrogen (TN)

Non

-veg

etat

ed

cont

rols

During wet conditions – • All plant species perform relatively well –

significantly more effect than non-veg • May be low nutrient media • Saturated zone reduces species variation

After drying…

Total Nitrogen (TN) Following drying – Poorer removal Greater variation between species Benefit of saturated zone clear

Where does the nitrogen go?

Assimilation Denitrification

vs

NO3-

N2, N2O

NO3-, NH4

+

• Most nitrate is assimilated • Denitrification minimal at this stage

Division of incoming nitrate (early biofilter life)

Plant species selection for optimal nitrogen removal

Relationships in wet conditions • Root characteristics – high total length, surface area,

mass and length of fine roots

• High total biomass

• Key process - plant nitrogen uptake

Total root length across species

Performance vs. Root surface area

Effective = High root surface area

Relationships in dry conditions

• Drying changed relationships with plant characteristics from the wet

• Water conservation critical

• Advantage to species with lower growth and biomass

• Lawn grass performance was promising but clogging and experimental limitations problematic

Slower growth an advantage in dry

Performance vs. Relative Growth Rate

• Select species with extensive and fine roots, relatively high growth, and high total plant mass

• Effective species differentiated by high total root length

Effective species – Extensive root systems

Carex tere.

Buffalo

Carex app. Melaleuca

Leptospermum

Juncus kraussii

Melaleuca Carex app.

Juncus pallidus

Leptospermum Juncus kraussii

Melaleuca

• Generally exclude species with thick roots or minimal root systems, particularly small and slow-growing shrubs/trees

Dianella revoluta

Poorer performers – minimal root systems

Gahnia trifida Sporobolus

Dianella

Hypocalymma

Austrodanthonia

Gahnia trifida

Dianella Hypocalymma

Sporobolus Gahnia trifida

• Some species perform relatively well in both wet and dry (e.g. Carex spp., Juncus pallidus and Melaleuca incana)

…or consistently poorly (e.g. Hypocalymma, Hakea and Gahnia spp.)

• Plant species with quite differing appearance can have similar performance and key morphological traits -> variety in form may provide long-term functional capacity

Plant species selection guidelines • Similarity in broad plant type or general

appearance is a poor guide e.g. Carex vs.Gahnia

Carex -> effective

Gahnia -> poor

• Plant a mixture of species -> more consistent function across seasons

• Minimise surface layer drying -

• Relatively dense planting - maximise uptake and microbial processing capacity, but beware excessive drying

WET DRY

Lawn grasses - Distinct morphology –

suggests alternate mechanisms

- Promising but need to consider:

- Clogging potential

- Maintenance issues – mowing effectively harvests and removes N but media consolidation potential

- Evapotranspiration loss on large scale

Velvetene Buffalo

Phosphorus removal

Total Phosphorus • Effective removal in wet irrespective of design

• Reduced performance following drying

• Not sensitive to species – media important

Role of plants in maintaining permeability

Confirming the role of plants in maintaining permeability

Hypothesis: growth of roots…

Hatt, B. E., Fletcher, T. D., & Deletic, A. (2009). Hydrologic and pollutant removal performance of biofiltration systems at the field scale. Journal of Hydrology, 365(3-4), 310-321.

Permeability increased by the presence of plants…

0

300

600

900

1 2 3 4 5 6 7Site Number

Ksa

t (m

m/h

r)

Cover

BareVegetated

Harry Virahsawmy: [email protected]

Virasawhmy, H., Stewardson, M., Vietz, G., & Fletcher, T. D. (in press). Factors that affect the hydraulic performance of raingardens: Implications for design and maintenance. Water Science and Technology.

Preferential flow paths…

… using a dye-tracer

With plants (preferential flow, high Ks)

Without plants (uniform flows, low Ks)

Water balance

Water balance of rain-gardens…

Catchment area: 321 m2

Raingarden area: 10 m2

1m

• Rainfall • Inflow • Water level • Surrounding soil

moisture • Climate

Perrine Hamel: [email protected]

Results – Water balance

z

3% evapotranspiration

87%

10%

Soil profile Loamy sand Clay

Hamel, P., Fletcher, T. D., Walsh, C. J., Beringer, J., & Plessis, E. (in press). Water balance of infiltration systems in relation to their operating environment. Water Science and Technology.

Conclusions

● Nitrogen removal is sensitive to plant species selection

● Include a diversity of plant species

● Low nutrient media critical

● Including a saturated zone supports plants & function across dry periods, allows denitrification, and buffers against poor plant choice

● Importance of an extensive root system BUT must be able to survive dry periods and sandy media

● Plants help maintain permeability – include some thicker rooted species (Virahsawmy et al., in press)

● Rule of thumb - % ET loss approx. = % catchment area (Hamel et al., in press)

Thanks very much for your time!

The Plant Table

Car park pocket biofilter, Margaret River

Which plants for which site

Table 5

Part A

Part B - Selection Criteria

• South West Botanical Province • Sandy Loam • Readily available as nursery tubestock • Tolerate Regular – Temporary Inundation

www.sercul.org.au

Attributes 1. Root Type 2. Habit 3. Inundation Tolerance 4. Drought Tolerance 5. Height 6. Nutrient Removal 7. IBRA region 8. Growth rates 9. Flower colour 10. Salinity Tolerance 11. pH Tolerance

Root Type

Fine

Coarse

Inundation Tolerance

REGULAR TEMPORARY

DRY

Nutrient removal

H = High M = Moderate L = Low S = Suspected U = Unknown

Interim Biogeographic Regionalisation for Australia

1. Avon Wheatbelt 2. Esperance Plains 3. Geraldton Sandplains 4. Jarrah Forrest 5. Mallee 6. Swan Coastal plain 7. Warren

Example

Objectives • Improve Water Quality, Biodiversity &

Aesthetics

Site Location: Armadale Constraints • Roadside verge height restrictions

<1.5m • Range of hydrozones • No irrigation • Late in season • Acid- Neutral • Doris likes Yellow flowers

Opportunities • Local Reference site

Selection Criteria

• Swan Coastal Plain Region • Height <1.5m • Mix of High - Moderate Nutrient

removers • Fast - Moderate Growth rate • Species that can tolerate RT

Inundation • Include some yellow flowers for Doris • Use species list from Local reference

site

Species List • 27 species • 6 proven

performers • 9 species with

yellow flowers

FAMILY - GENUS SPECIESCOMMON

NAME

Root Length

(cm)

Root Type Coarse (C)

Fine(F)

( sedges and

rushes: Clumping = C, Spreading = S)

TOLERANCE - REGULAR(R)

TEMPORARY (T) DRY (D)

Drou toler

(Y/

Cyperaceae Baumea junceaBare twig sedge

30 F Sedge -S RTD N

Cyperaceae Baumea rubiginosaSoft twig sedge

F Sedge -S RT N

Cyperaceae Carex tereticaulis 60 CF Sedge - C RTD N

Cyperaceae Cyperus gymnocaulosSpiny flat sedge

25 C Sedge - C RT N

Juncaceae Juncus kraussii Sea Rush 25 F Rush -C RT N

Juncaceae Juncus subsecundus Finger Rush F Rush -C RTD Y

Cyperaceae Baumea preissii F Sedge - S RT N

Cyperaceae Baumea vaginalisSheath twig sedge

F Sedge - S RT N

Cyperaceae Bolboschoenus caldwelliiSea Club sedge

Sedge - S RT N

Cyperaceae Carex fascicularis Tassel sedge 60 F Sedge - S RT N

Cyperaceae Carex inversa Knob sedge F Sedge - S RT

Haemodoraceae Conostylis aculeataSpiny cotton heads

Herb RTD Y

Asteraceae Cotula cotuloidesSmooth cotula

Herb RTD Y

Goodeniaceae Dampiera trigonaAngled stem dampiera

Herb RT N

Goodeniaceae Dampieria linearisCommon Dampiera

Herb RTD Y

Asteraceae Hyalosperma cotula Herb RTD Y

Cyperaceae Isolepis cernua Sedge -C RT N

Juncaceae Juncus pauciflorusLoose Flower rush

F Rush - C RTD Y

Cyperaceae Lepidosperma longitudinalePithy Sword Sedge

Sedge - S RT N

Restionaceae Meeboldina scariosa Velvet rush Rush-C RT N

Restionaceae Meeboldina coangustatus Rush -C RT N

Myrtaceae Melaleuca seriata F Shrub RTD Y

Primulaceae Samolus repensCreeping Brookweed

Herb RTD Y

Primulaceae Samolus junceus Herb RT N

Goodeniaceae Scaevola lanceolata Herb RT N

Hemerocallidaceae Tricoryne elatior Yellow lily Herb RTD Y

Myrtaceae Verticordia plumosaPlumed Featherflowe

Shrub RTD Y

Practical Considerations


Assess the Site • Is a biofilter the best option? • Check: Location, access, safety, ownership….. Liaise with key stakeholders Budget Climate Hydrology Existing Soil Services

What are your objectives FIRST: Water quality

Other attributes Biodiversity Landscaping Improved hydraulic capacity Water conservation Reduced maintenance for downstream systems

Parkfield POS, Bertram

Biodiversity and Landscaping outcomes

Performers and landscapers

Treendale Shopping Centre


Direct watering and reduced downstream flows

Queens Gardens Bunbury

Selecting Plants

Establishing the plants

When to plant Ordering plants Plant quality Irrigation Site Prep Planting techniques – tubestock Mulch – organic/stones/nothing ??

Plant placement


Stone Mulch

Coarse Jute matting

Monitoring and Maintenance

Keep the love going

Suggested Timeframe One week After 1 month After 3 months Every 6 months

AND……. after first and major rain events

Questions

Biofilter Vegetation Guidelines – Brendan Oversby