attachment 2 - 2a and 2b premises maps...dardanup wwtp treatment / design capacity (ref appl section...

Dardanup WWTP - Support for licencing application

Attachment 1A Proof of occupier status

Water Corp internal:

https://nexus.watercorporation.com.au/otcs/cs.exe/app/nodes/97968436

Attachment 2 - 2A and 2B Premises maps

Water Corp internal:

2A:https://nexus.watercorporation.com.au/otcs/cs.exe/app/nodes/98190710

2B https://nexus.watercorporation.com.au/otcs/cs.exe/app/nodes/97969756



LANDGATE COPY OF ORIGINAL NOT TO SCALE

www.landgate.wa.gov.au

JOB 53959726Wed May 24 09:24:53 2017

!

!

Perth

Dardanup

!

!

!!

!

!

!

!!

!!

!

!

!

!!

! !

!

Treelot

DischargePoint

Inflow

InfiltrationChannel

InfiltrationChannel

Facultative Pond 1A

Maturation Pond 2A

Maturation Pond 3A

TreatedWastewater

Storage Pond

TreatedWastewater

Flume

Ban

ksia

Rd

Marginata Cl

12

3

4

5

67

8

9

10

14

17

15

16

11 12

13

Landgate / SLIP

386,200

386,200

386,400

386,400

386,600

386,600

386,800

386,800

387,000

387,000

387,200

387,200

387,400

387,400

6,30

0,80

0

6,30

0,80

0

6,30

1,00

0

6,30

1,00

0

6,30

1,20

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6,30

1,20

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6,30

1,40

0

6,30

1,40

0

BRANCH: DTG - MAPPING & GEOSPATIAL

DATE: 17/06/2020AUTHOR: CHONGV1Dardanup

Wastewater Treatment PlantPremises Map

File: J:\Mapping_Tasks\South_West\Wastewater\RITM0419590_DardanupWWTP\Working\DardanupWWTP.mxd

The information contained herein is the exclusive property of theWater Corporation and the respective copyright owners. It is subject toongoing review and should be viewed in conjunction with the associated

materials. No part of this production should be copied, modified, reproducedor published in any form other than that intended by the author.

0 100 200

MetresCoordinate System: GDA 1994 MGA Zone 50

Vertical Datum: AHD

at A41:5,000

´

LEGEND

Dardanup WWTP Prescribed Premises Boundary

Cadastre

ID mE mN1 386,670.90 6,300,802.232 386,594.31 6,300,802.333 386,543.19 6,300,859.024 386,544.29 6,301,012.375 386,389.84 6,301,091.446 386,387.10 6,301,393.137 386,397.19 6,301,403.078 386,986.20 6,301,410.209 386,988.44 6,301,418.96

10 387,078.99 6,301,400.8511 387,082.06 6,301,411.5612 387,195.06 6,301,412.9213 387,208.26 6,301,151.3014 387,025.97 6,301,192.9115 386,935.22 6,301,211.0516 386,935.71 6,301,212.93

Dardanup WWTP Schematic

Dardanup WWTP Process Control Points:

Sampling Point

Monitoring Point

TR

EE

LO

T

Primary Treatment Pond0.292ha3800kL

Secondary Treatment Pond0.155ha2300kL

TertiaryTreatment Pond0.103ha, 1750kL

Treated WastewaterStorage Pond0.180ha3600kL

Pond Connection

Discharge MH

Pressure Main

Ba

nksia

Ro

ad

Re

se

rve

Final Effluent

S8000216

Open

infiltration

channels

S085-001-003

(meter off site)

S8008227

Attachment 3B Proposed (existing) Activities

Dardanup Wastewater Treatment Plant (WWTP) is located approximately 3 km south-east of the

Dardanup town site. It is surrounded by the Shire’s waste transfer facility to the east, Shire’s

gravel pit to the north and the regional landfill / resource recovery facility, currently operated by

Cleanaway, to the south. The surrounding land use to the north and east and far west of the

WWTP is predominantly cattle pasture and state forest. The WWTP services Dardanup town

site, with a population of approximately 500 people and 224 wastewater services connected.

The annual average daily flow (AADF) in 2020 is ~85 kL/day (Figure 1). Wastewater from

Dardanup’s reticulated system is received at the WWTP primarily through the pressure main,

and occasionally by road tanker when required due to maintenance or incident management of

the reticulated system.

There are four ponds on site, operating in series — a facultative treatment pond (1A), two

maturation ponds (2A, 3A) and a treated wastewater storage pond. Disposal of the treated

wastewater (TWW) is by irrigation to an adjacent treelot (22 Ha blue gum - Eucalyptus globulus)

situated downgradient and to the west of the WWTP. TWW is discharged from the tertiary pond

via a flume to either the TWW storage pond* or directed to the treelot. With no power on site,

TWW gravitates through the pipeline to a splitter box in the treelot. The flow is divided between

two open infiltration channels which stretch across the breadth of the upper reaches of the

treelot. The TWW infiltrates the ground and irrigates the trees by percolating horizontally

westwards through the treelot due to a perched aquifer and westerly grading slope.

*Note: The storage pond is not currently in use, as the liner is compromised. However Water

Corporation would like the option to use this pond once repaired. A pipeline currently conveys

TWW from the tertiary pond 3 discharge flume, bypasses the storage pond and links in with the

existing pipework which takes flow to the designated emission point at the infiltration channels in

the treelot.

Figure 1: Dardanup WWTP daily inflow volumes, averaged monthly, showing peaks during winter

months and as compared to the threshold for registered premises (cat. 85)

0

20

40

60

80

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120

140

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180

Jul-

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ave

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dai

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low

(kL

)

Dardanup WWTP Inflow average daily volumes (kL)

Inflow avg/daily Cat 85 max vol Treatment capacity

Production capacity/throughput - inflow volume (ref application sections 4.8 & 4.9)

Wastewater volume received at a WWTP is in effect restricted by the number of

connections in the catchment feeding that particular plant. Different catchments will vary

in the average volume contributed per connection (based on the makeup of the types of

connections within that catchment), but it is a relatively stable parameter within each

catchment. For the Dardanup catchment, the average volume per connection is ~380

L/day (85kL/224 connections), or ~170 L/day/person (85kL/500 people).

Notable in figure 1 are peaks which occur during the winter period, coinciding with the

rainy season for this area, and is caused by rainwater which has infiltrated the reticulated

system. On this basis, the 380 L/day average per connection is a somewhat inflated

representation of the wastewater that each connection contributes (as it is calculated

from rainwater-affected data).

Average inflow over the past five years has been a steady 83 kL/day. Modelling suggests

it will remain between 80 and 90 kL/day for the next 5 to 10 years. However, given the

land zoned for development in the Shire of Dardanup Town Planning Scheme No. 3, and

uncertainty around regional migration and intrastate travel during the coronavirus

pandemic, there is a risk that inflow might near 95 kL/day in the near future.

Dardanup WWTP treatment / design capacity (ref appl section 4.8)

The WWTP was first registered with then DEC in 1996 with a raw sewage treatment

capacity of 90 kL/day. A subsequent review of treatment capacity through a State-wide

standardization process using the Mara method has recalculated the treatment capacity

of the WWTP to 165 kL/day. The declared treatment capacity for the WWTP of

165kL/day is based on the minimum treatment capacity for this plant, which occurs

during the cooler winter months.

Based on forecast population growth in Dardanup, the WWTP has treatment capacity for

more than 20 years (Figure 2).

Figure 2 Dardanup WWTP flow forecast compared to category 85 volume threshold, and

minimum treatment capacity of the plant.

------------------------------ END 3B ------------------------------

Attachment 6A Emissions, discharges, and waste

- Details of management measures employed to control emissions should also be included. Please

provide / attach any relevant documents (e.g. management plans, etc.). – e.g. NIMP

Monitoring

Inflow is continuously monitored by flowmeter, designated S085-001-003, and outflow is

monitored through a flume designated S8008227 (refer to Attachment 2 for the site diagram

showing the location of these monitoring points).

Sampling of final effluent is conducted quarterly during the months of January, April, July and

October. Typical results for TWW nutrients: TN average ~25mg/L; TP average ~12 mg/L. Table

1 provides data for one year of monitoring.

Table 1: Monitoring results for Dardanup WWTP final effluent

Groundwater monitoring

Historically there are four groundwater monitoring sites (noted as MW1 to MW04 on the NIMP

map - Figure 8), each consisting of three nested bores (A, B, C) that were developed to gather

data for the differing water tables/aquifers, which were retained as monitoring bores. It is the

view of Water Corporation that there are likely bore integrity issues and that groundwater has

potentially been compromised/impacted by neighbouring activities around the WWTP site. As a

consequence, when interpreting the data from these bores it is difficult to draw meaningful

conclusions about the impacts of WWTP operations and disposal.

An environmental risk assessment is currently underway for the Dardanup WWTP site. This

includes the drilling and monitoring of bores, a selection of which will be chosen to replace the

historical bores for ongoing groundwater monitoring. Details of these new bores and initial data

can be provided after a groundwater monitoring event has taken place (expected 3rd quarter

2020).

E. co

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Am

mo

niu

m a

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nit

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en

Bio

ch

em

ica

l

Oxy

ge

n D

em

an

d

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(B

OD

)

Co

nd

uc

tivit

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La

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ry a

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rite

plu

s

nit

rate

as

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me

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sp

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So

lid

s

To

tal

nit

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en

To

tal

ph

os

ph

oru

s

MPN

/100m

L

mg/L mg/L mS/m mg/L NOUNIT mg/L mg/L mg/L mg/L

Jul

2018 1100 7.5 30 80 8.3 7.39 130 450 32 12

Oct

2018 160 23 10 85 0.14 7.93 5 450 25 12

Jan

2019 1300 0.090 25 104 <0.05 9.38 140 640 20 11

Apr

2019 1800 3.9 20 140 0.32 8.92 100 860 21 14

Discharge disposal

With no power on site, TWW gravitates through a pipeline to a splitter box in the treelot and

divides into two open infiltration channels, spreading flow across the breadth of the upper

reaches of the treelot. The TWW infiltrates the ground and irrigates the trees by percolating

horizontally westwards through the treelot, perched above the low-permeability lateritized layer.

The soil A horizon across the site has a relatively high infiltration capacity and is classified as a

sandy loam to loam. At depths of approximately 1 to 3 m, there is a lateritized layer of up to 0.5m

thick of sandy gravels with decreased permeability followed by a B horizon of clayey

sands/sandy clays intermixed with sandy gravels/gravelly sands. The duplex nature of the soils

across the site produces two distinctive permeabilities that causes water to flow preferentially in

a horizontal direction and irrigates the trees by percolating through the treelot area in a westerly

direction, consistent with surface contours.

A Nutrient Irrigation Management Plan (NIMP) was developed for the site by Worley Parsons

(with site investigations in July 2012) to manage the irrigation of the treelot area sustainably for

the anticipated flow forecast. It was developed in accordance with Water Quality Protection Note

33: Nutrient and Irrigation Management Plans (DoW 2010) and Water Quality Protection Note

22: Irrigation with Nutrient-Rich Wastewater (DoW 2008).

In brief, with the information available at that time, investigations for development of the NIMP

confirmed the treelot’s is capablity of sustainably utilising the forecast flows from the WWTP,

both hydraulically and in terms of nutrient management.

A copy of the NIMP is attached at the end of this document.

Water Corporation internal link: Dardanup WWTP - Nutrient Irrigation Management Plan 2012

Worley Parsons.pdf (https://nexus.watercorporation.com.au/otcs/cs.exe/link/99341555)

The plan remains mostly relevant for the site but some of the assumptions used in developing

the NIMP have changed, for example:

- All water balance conclusions and outcomes in the NIMP are centred on the treelot having an

irrigable area of 28 Ha. The current treelot however is 22.5 Ha (or 20% less than shown in the

NIMP). A further 20% reduction in irrigable area can be applied to the current scenario to

account for unplanted areas (roadway, firebreaks, infiltration channels). Values of the outcomes

for the treelot to handle the irrigation volumes therefore need to be adjusted downwards to 60%

of what is shown in the NIMP (representing 17 Ha canopy area).

- At the time the NIMP was developed, population growth was predicted to be higher than the

current actuals, causing the NIMP scope to be extended to a capacity of 277 kL/day. Revised

growth predictions as shown in Attachment 3B indicate such volume would only be reached well

beyond 2050 (rather than the 2025 prediction in the NIMP). For the purpose of this application

therefore the growth outlook should be moderated to extend only to the treatment capacity of the

plant which is 165 kL/day.

Notable extracts from the NIMP:

- Stated in the NIMP (s3.1 pg. 5) that the 28 Ha treelot is expected to meet the

projected effluent flow forecast until the year 2025 (up to 277 kL/day). So, correcting

this for the reduced canopy area of 17 Ha approximates to the 165 kL/day treatment

capacity of the WWTP. We can infer then that disposal to the current woodlot (22 Ha,

canopy 17 Ha) can be expected to meet the projected inflows for the next 20 years

(refer to Figure 2 in Attachment 3B).

https://nexus.watercorporation.com.au/otcs/cs.exe/link/99341555

- In general, the risk of nutrient export offsite is considered to be low due to the ability

of soils to adsorb phosphorus and the high uptake of nitrogen by the blue gums.

Water balance / hydraulic capability of the treelot

- The soil A horizon has relatively good infiltration, whereas infiltration is poor in the B-

horizon.

- There is vertical separation to the regional water table, with regional groundwater

likely residing at a depth of approximately 8.5 m below ground and, due to the duplex

nature of the soils, perched groundwater above this where there is a more clayey,

compacted B horizon layer.

- Modelling was undertaken to determine the treelot capability to manage hydraulically

(water balance modelling) - so treelot water demand, incorporating predicted

wastewater flows and disposal demand.

- A site water balance for the period of 2012 to 2025 was conducted to assess the

effect of irrigating with a maximum forecasted rate of 277 kL/d on the 28-ha treelot

area. Results of the modelling indicate that a maximum daily flow of 277 kL/d equates

to 20% of the hydraulic capacity of the site, assuming a 70% vegetative cover. It was

also noted that less than 1 mm of runoff and no overtopping of the ponds were

anticipated.

- NOTE: (bottom pg. 28) For the period between 2012 and 2025, the required disposal

demand (up to 277 kL/d) does not exceed the mature tree lot demand of

approximately 3.14 mm.

- NOTE: (top pg. 29) Ultimately, results of the modelling indicate that the 28 ha treelot

can sustainably be irrigated up to 277 kL/d over the period of 2012 to 2025.

Nutrient management: Phosphorus

- The nutrient mass balance was calculated, assessing potential impacts of effluent

irrigation on the nutrient mass balance of the treelot area based on the average

concentrations of nitrogen and phosphorus in the effluent wastewater.

- The Phosphorus Retention Index (PRI) analyses reflect the duplex nature of the soils,

with low values recorded in the A horizon and lateritized sandy gravels, and

increasing PRI values reported in the underlying clay B horizon. The capacity of soils

to sorb P increases with increasing clay content and therefore with depth. Topsoil and

sands (depth < 2 m) had PRI values ranging from less than 5 to 12.5. The lateritic

sandy gravel PRI values ranged from 25 to 380 and values greater than 700

generally reported for the intermixed sandy/gravelly clays.

- Similarly, Phosphorus Buffering Index values are low (4 to 8) for the A horizon sands

and increase with depth in the subsoil from 13 to 29 for the lateritized sandy gravel

layer and values greater than 680 were generally reported for the sandy/gravelly

clays.

- The average Phosphorus Retention Time (PRT) of 23 to 37 years exceeds the

planned duration of irrigation in the treelot, therefore the likelihood of off-site export of

phosphorus through discharge in the sub-surface is considered low.

Nutrient Management: Nitrogen

- The likelihood of nitrogen leaching from the site is low; more nitrogen is being

assimilated and lost compared to the amount of nitrogen being input by effluent. The

key variable in the nitrogen balance is the rate which nitrogen is assimilated into

above ground biomass. Biomass assimilation changes over time as the plantation

matures; the highest assimilation is during the early growth period and decreases as

the tree growth slows. Plantation management is an important tool in reducing the

likelihood of nitrogen export from the site.

- Given the slow rate of groundwater movement across the site, it is unlikely that

nutrient leaching will have an impact on offsite surface water bodies.

- Offsite movement of water and/or nutrients into sensitive areas is therefore not

expected.

----------------------------- END 6A ----------------------------------

Attachment 6B Waste Acceptance

Waste type received at Dardanup WWTP

Wastewater from Dardanup’s reticulated system is received at the WWTP through the pressure

main. A representation of these flow volumes has been provided in Attachment 3B figure 1.

Very occasionally, when maintenance or other incident of the reticulated system occurs, it is

necessary to use tanker trucks to draw the wastewater (sewage) from the system catchment and

deliver it to the WWTP. Such loads are managed under the Controlled Waste Tracking System

(CWTS) and Dardanup WWTP has a controlled waste category K130 listing for this purpose.

Due to the incidental nature of these events, volume cannot be predicted but forms part of the

normal daily flows accepted by this plant.

The information in table 2 has been drawn from the CWTS. It shows the receipts of waste

(sewage – K130) at Dardanup WWTP for the past three years.

Table 2: CWTS receipts for Dardanup WWTP over a 3-year period 1/07/2017 to 4/5/2020

Waste Facility: Water Corporation [Dardanup WWTP]

Selection Criteria:

Received Date Start: 01/07/2017

Data Date: 05/05/2020

Received Date End: 04/05/2020

Data Time: 03:02:17PM

Delivery Dates

Tracking Form(s) L KG M3 Density Factor

Normalised Total (Tonnes)

26/09/2018 6007173 19,000 0.00 0.00 0.72 13.7

27/09/2018 6007194 18,000 0.00 0.00 0.72 12.98

27/09/2018 6007195 18,000 0.00 0.00 0.72 12.98

27/09/2018 6007196 18,000 0.00 0.00 0.72 12.98

27/09/2018 6007197 18,000 0.00 0.00 0.72 12.98

Waste Type>

K130 91,000 0.00 0.00 0.72 65.61

-------------------------------------- END 6B -----------------------------------

Attachment 7 Siting and location

Sensitive land uses

The Dardanup WWTP is situated on the eastern fringe of the coastal plain and is surrounded by

land zoned ‘general farming’. The Greater Bunbury Region Scheme shows the WWTP is in a

‘rural’ area and is designated ‘public utilities’.

(Figure 3 - Dardanup WWTP – Local Planning)

The WWTP and treelot are not within a Public Drinking Water Supply Area. The Dardanup Water

Reserve is located over 2.5km to the north-west of the premises boundary, from which Water

Corporation supplies the town of Dardanup. There are no known groundwater users in close

proximity to the WWTP. Risk to this resource is considered low due to the distance of the

receptor and that there are multiple confining/semi-confining units to where the production bore

is screened. There are some groundwater licences issued for the Perth-Leederville aquifer to the

north, west and south of the WWTP, the closest being approximately 1.5 km from the premises.

(Figure 4 - Dardanup WWTP - Human)

The only areas of significance that show up as registered Aboriginal Heritage sites are the two

watercourses (Ferguson River 19796RNN, approximately 2.6km away, and Crooked Brook

19795RNN approximately 2 km away).

(Figure 5 - Dardanup WWTP - Heritage)

Nearby environmentally sensitive receptors

Surface water - The closest natural water courses are the Ferguson River to the north east and

Crooked Brook to the south west, located approximately 2.6 km and 2 km from Dardanup

WWTP respectively.

(Figure 5 - Dardanup WWTP - Heritage)

Conservation areas – There is a ‘DPAW Reserve’ in the forested area to the south and east, the

boundary of which commences approximately 1km from Dardanup WWTP. The Dardanup

regional landfill is situated between the WWTP and the forest reserve.

(Figure 6 – Dardanup WWTP - Conservation Areas)

Biodiversity and habitat – the only significant items showing up are narrow swathes of ‘Banksia

Dominated Woodlands of the Swan Coastal Plain’ along the western boundary of the treelot (in

effect the remnant woodland along road reserves).

(Figure 7 – Dardanup WWTP - Biodiversity and Habitat)

!Perth

WWTP BANKSIARD DARDANUP

CROOKED BROOK

DARDANUP R30R12.5

R12.5R15

R12.5 R12.5R12.5

Landgate / SLIP

383,000

383,000

384,000

384,000

385,000

385,000

386,000

386,000

387,000

387,000

388,000

388,000

389,000

389,000

390,000

390,000

391,000

391,000

6,299

,000

6,299

,000

6,300

,000

6,300

,000

6,301

,000

6,301

,000

6,302

,000

6,302

,000

6,303

,000

6,303

,000

BRANCH: SEAADAT E: 19/05/2020AUT HOR: SCOT T B2

File: S:\AA_EIA_GIS\1_Projects\Operational\AER WWT P Environm ental Siting Mapping\SWR - Dardanu p WWT P\Risk Based Assessm ent - Local Planning – Dardanup WWT P.m xd

T h e inform ation contained h erein is th e exclu sive property of th eWater Corporation and th e respective copyrig h t owners. It is subject toong oing review and sh ou ld be viewed in conju nction with th e associated

m aterials. No part of th is production sh ou ld be copied, m odified, reproducedor publish ed in any form oth er th an th at intended by th e au th or.

0 340 680 1020 1360Metres

Coordinate System : GDA 1994 MGA Zone 50Vertical Datum : AHD

at A41:35,000

´

Local PlanningDardanup WWT P

LegendDardanup Site Boundary2 km BufferWWTP

!( Major Town!( Minor Town

Local Planning Schemeszone

Business - commercia lDevelopmentGenera l farmingNo zoneOther communityRecreationResidentia lSchoolSmall holdingSpecialRcode

Figure 3: Dardanup WWTP – Local Planning

!Perth


CROOKED BROOK

DARDANUP

Landgate / SLIP

383,000

383,000

384,000

384,000

385,000

385,000

386,000

386,000

387,000

387,000

388,000

388,000

389,000

389,000

390,000

390,000

391,000

391,000

6,299

,000

6,299

,000

6,300

,000

6,300

,000

6,301

,000

6,301

,000

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,000

6,302

,000

6,303

,000

6,303

,000

BRANCH: SEAADATE: 19/05/2020AU THOR: SCOTTB2

File: S:\AA_EIA_GIS\1_Projects\Operational\AER WWTP Env ironm ental Siting Mapping \SWR - Dardanup WWTP\Risk Based Assessm ent - Hum an – Dardanup WWTP.m xd

Th e inform ation contained herein is the exclusive property of theWater Corporation and the respective copyrig h t owners. It is subject toong oing review and sh ould be v iewed in conjunction with the associated

m aterials. No part of th is production sh ould be copied, m odified, reproducedor published in any form oth er than that intended by the auth or.

0 340 680 1020 1360Metres


at A41:35,000

´

Hum anDardanup WWTP

LegendDardanup Site Boundary2 km BufferWWTPPublic Drinking Water Supply Area(PDWSA)

WRL_DrawpointsINSTRUMENT!( Groundwater Licence!( Surface Water Licence

WRL_PropertiesINSTRUMENT

Groundwater LicenceSurface Water Licence


Figure 4: Dardanup WWTP – Human

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19796R N N

19796R N N

19795R N N


CROOKED BROOK

DARDANUP

Landgate / SLIP

383,000

383,000

384,000

384,000

385,000

385,000

386,000

386,000

387,000

387,000

388,000

388,000

389,000

389,000

390,000

390,000

391,000

391,000

6,299

,000

6,299

,000

6,300

,000

6,300

,000

6,301

,000

6,301

,000

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,000

6,302

,000

6,303

,000

6,303

,000

BRANCH: SEAADATE: 19/05/2020AU THOR: SCOTTB2

File: S:\AA_EIA_GIS\1_Projects\Operational\AER WWTP Env ironm ental Siting Mapping \SWR - Dardanup WWTP\Risk Based Assessm ent - Heritag e – Dardanup WWTP.m xd

Th e inform ation contained herein is the exclusive property of theWater Corporation and the respective copyrig h t owners. It is subject toong oing review and sh ould be v iewed in conjunction with the associated

m aterials. No part of th is production sh ould be copied, m odified, reproducedor published in any form oth er than that intended by the auth or.

0 340 680 1020 1360Metres


at A41:35,000

´

Heritag eDardanup WWTP


Aboriginal HeritageSites.shpSTATUS

Registered Site


Figure 5: Dardanup WWTP – Heritage

!Perth


CROOKED BROOK

DARDANUP

Landgate / SLIP

383,000

383,000

384,000

384,000

385,000

385,000

386,000

386,000

387,000

387,000

388,000

388,000

389,000

389,000

390,000

390,000

391,000

391,000

6,299

,000

6,299

,000

6,300

,000

6,300

,000

6,301

,000

6,301

,000

6,302

,000

6,302

,000

6,303

,000

6,303

,000

BRANCH: S EAADATE: 19/05/2020AUTHOR: S COTTB2

File : S :\AA_EIA_GIS \1_Proje cts\Ope ra tional\AER WWTP Environm e ntal S iting Mapping \S WR - Da rdanup WWTP\Risk Ba se d Asse ssm e nt - Environm e nt (Conse rva tion Are as) – Dardanup WWTP.m xd

Th e inform ation conta ine d h e re in is th e exclusive prope rty of th eWa te r Corpora tion a nd th e re spe ctive copyrig h t owne rs. It is sub je ct toong oing re vie w a nd sh ould b e vie wed in conjunction with th e a ssociate d

m a te ria ls. No pa rt of th is production sh ould b e copie d, m odifie d, re produce dor pub lish e d in a ny form oth e r th a n th a t inte nde d by th e auth or.

0 340 680 1020 1360Me tre s

Coordinate S yste m : GDA 1994 MGA Zone 50Vertical Datum : AHD

at A41:35,000

´

Environm e nt - Conse rva tion Are a sDardanup WWTP



categoryDPAW ReserveDECManagedLandsWaters

Figure 6: Dardanup WWTP – Conservation Areas

!Perth


CROOKED BROOK

DARDANUP

Landgate / SLIP

383,000

383,000

384,000

384,000

385,000

385,000

386,000

386,000

387,000

387,000

388,000

388,000

389,000

389,000

390,000

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391,000

391,000

6,299

,000

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,000

6,300

,000

6,300

,000

6,301

,000

6,301

,000

6,302

,000

6,302

,000

6,303

,000

6,303

,000

BRANCH: S EAADATE: 19/05/2020AUTHOR: S COTTB2

File : S :\AA_EIA_GIS \1_Proje cts\Ope ra tional\AER WWTP Environm e ntal S iting Mapping \S WR - Da rdanup WWTP\Risk Ba se d Asse ssm e nt - Environm e nt (Biodive rsity a nd Ha bita t) – Dardanup WWTP.m xd

Th e inform ation conta ine d h e re in is th e exclusive prope rty of th eWa te r Corpora tion a nd th e re spe ctive copyrig h t owne rs. It is sub je ct toong oing re vie w a nd sh ould b e vie wed in conjunction with th e a ssociate d

m a te ria ls. No pa rt of th is production sh ould b e copie d, m odifie d, re produce dor pub lish e d in a ny form oth e r th a n th a t inte nde d by th e auth or.

0 340 680 1020 1360Me tre s

Coordinate S yste m : GDA 1994 MGA Zone 50Vertical Datum : AHD

at A41:35,000

´

Environm e nt - Biodive rsity and Habita tDardanup WWTP


Herbarium.shpCons_code# T

# 1

# 2

# 3

# 4Threatened FloraThreatened Flora ConservationStatus# (T) Declared Rare Flora - Extant

Taxa# Priority 1

# Priority 4Threatened FaunaCLASS

BIRDINVERTEBRATEMAMMALSouth West Region Linkage -Lines

TEC/ PEC BuffersCOM_NAME

Banksia Dominated Woodlands ofthe Swan Coastal Plain IBRARegionDardanup Jarrah and MountainMarri woodland on lateriteEucalyptus haematoxylon - E.marginata woodlands on WhicherfoothillsSouthern Banksia attenuatawoodlands


Figure 7: Dardanup WWTP – Biodiversity and Habitat

Nutrient Irrigation Management Plan – Supplement to Attachment 6A

Water Corp internal: Dardanup WWTP - Nutrient Irrigation Management Plan 2012 Worley Parsons.pdf

(https://nexus.watercorporation.com.au/otcs/cs.exe/link/99341555)

https://nexus.watercorporation.com.au/otcs/cs.exe/link/99341555

WATER CORPORATION

i:\projects\301012-01582 watercorp dardanup nimp\4_engineering\reports\dardanup\nimp\rev 0\301012-01582-en-rep dardanup nimp 19oct2012 rev 0.docxx

Page i 301012-01582-EN-REP: Rev 0: 19 Oct 2012

Nutrient and Irrigation Management Plan

Dardanup Wastewater Treatment Plant

301012-01582-EN-REP

19-Oct-2012

Infrastructure & Environment Level 7, QV1 Building 250 St Georges Terrace Perth WA 6000 Australia Tel: +61 8 9278 8111 Fax: +61 8 9278 8110 www.worleyparsons.com WorleyParsons Services Pty Ltd ABN 61 001 279 812

© Copyright 2012 WorleyParsons Services Pty Ltd

WATER CORPORATION


Page iii 301012-01582-EN-REP: Rev 0: 19 Oct 2012

Abbreviations

ADWG Australian Drinking Water Guideline

ANZECC Australia and New Zealand Environment Conservation Council

ASRIS Australia Soil Resource Information Service

BoM Bureau of Meteorology

cfu Colony Forming Units

DoW Department of Water

EC Electrical Conductivity

GDE Groundwater Dependant Ecosystems

ha Hectares

kL/d Kilolitres per day

LTV Long Term Trigger Values

mbgs Metres below ground surface

MEDLI Model for Effluent Disposal Using Land Irrigation

mg/L Miligrams per litre

ML/yr Megalitres per year

NHMRC National Health and Medical Research Council

NIMP Nutrient Irrigation Management Plan

PBI Phosphorus Buffering Index

PDWSA Public Drinking Water Source Areas

PRI Phosphorus Retention Index

PWSS Private Water Supply Sources

STV Short Term Trigger Values

TDS Total Dissolved Solids, expressed as mg/L

TN Total Nitrogen

TP Total Phosphorus

UGBZ Upper groundwater bearing zone

UWA University of Western Australia

WQPN Water Quality Protection Note

WWTP Wastewater Treatment Plant

uS/cm Microsiemens per centimetre

WATER CORPORATION

NUTRIENT AND IRRIGATION MANAGEMENT PLAN

DARDANUP WASTEWATER TREATMENT PLANT

i:\projects\301012-01582 watercorp dardanup nimp\4_engineering\reports\dardanup\nimp\rev 0\301012-01582-en-rep dardanup nimp 19oct2012 rev 0.docx

Page iv 301012-01582-EN-REP: Rev 0: 19 October 2012

TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................................ 1

1.1 Project Scope ...................................................................................................................... 1

1.2 Project Summary ................................................................................................................ 2

2. PROJECT SETTING........................................................................................................... 3

2.1 Site Location and Features ................................................................................................. 3

2.2 Existing Site Land Use ........................................................................................................ 3

2.3 Land Zoning ........................................................................................................................ 3

3. LAND USE AND NUTRIENT APPLICATION DETAILS ..................................................... 5

3.1 Planned Land Use .............................................................................................................. 5

3.2 Animal Species and Density ............................................................................................... 6

3.3 On-Site Management .......................................................................................................... 6

4. LOCAL RAINFALL AND EVAPORATION .......................................................................... 7

4.1 Local Rainfall and Evaporation Data .................................................................................. 7

4.2 Rainfall Runoff and Infiltration Factors ............................................................................... 8

5. SOILS AND LANDFORM DESCRIPTION .......................................................................... 9

5.1 Phosphorus Retention and Buffer Indices (PRI and PBI) ................................................. 10

5.2 Acid Sulphate Soil Risk Evaluated .................................................................................... 10

5.3 Proposed Earthworks Details ........................................................................................... 11

5.4 Details of Any Imported Soil Amendment ......................................................................... 11

6. WATER RESOURCES DESCRIPTION AND USE .......................................................... 12

6.1 Sensitive Environments Located Near the Site ................................................................ 12

6.2 Surface Water Description ................................................................................................ 14

6.3 Groundwater Description and Depth ................................................................................ 15

6.4 Quality of Local Water Resources .................................................................................... 17

6.5 Present or Planned Licensed Water Use ......................................................................... 19

7. SITE MANAGEMENT ....................................................................................................... 21

WATER CORPORATION




Page v 301012-01582-EN-REP: Rev 0: 19 October 2012

7.1 Irrigation Scheme .............................................................................................................. 21

8. WATER BALANCE SCENARIOS ..................................................................................... 24

8.1 Site Water Balance ........................................................................................................... 24

8.1.1 MEDLI Model ....................................................................................................... 24

8.1.2 MEDLI Results ..................................................................................................... 24

8.2 Irrigation Water Balance ................................................................................................... 25

8.3 Nutrient Balance Modelling ............................................................................................... 29

8.3.1 Total Nitrogen ....................................................................................................... 29

8.3.2 Phosphorus .......................................................................................................... 30

9. DRAINAGE AND CONTAMINANT LEACHING CONTROLS .......................................... 33

9.1 Design and Function of Artificial Water Controls .............................................................. 33

9.2 Management/Monitoring of Water Bodies ........................................................................ 33

9.3 Offsite Water Movement into Sensitive Areas Prevention Plan ....................................... 33

9.4 Existing Surface or Buried Drainage Systems .................................................................. 34

9.5 Runoff Design for both Frequent and Extreme Storm Events .......................................... 34

9.6 Proposed Stormwater Calculation/Diversion Pipework or Channels ................................ 34

9.7 Proposals to Manage Soil Sodicity, Compaction and Salinity Risks ................................ 34

10. PROTECTION OF NATURAL WATER RESOURCES .................................................... 36

10.1 Surface Water Protection ............................................................................................. 36

10.2 Groundwater Protection ............................................................................................... 36

10.3 Nutrient Transport ........................................................................................................ 37

11. VEGETATION MANAGEMENT ........................................................................................ 38

11.1 Pesticide and Herbicide Storage and Use ................................................................... 38

12. SITE MONITORING AND REPORTING .......................................................................... 39

13. CONTINGENCY PLAN ..................................................................................................... 41

14. REFERENCES ................................................................................................................. 44

WATER CORPORATION




Page vi 301012-01582-EN-REP: Rev 0: 19 October 2012

Tables in Text

Table 1 Proponent’s Name and Contact Details .............................................................................. 2

Table 2 Site Identification ................................................................................................................. 2

Table 3 Average Effluent Water Quality Concentrations – Dardanup WWTP ................................. 6

Table 4 Climate Averages for 2011, Dardanup (BoM Site No. 9695) .............................................. 7

Table 5 Summary of the Soil Profile within the Woodlot Area ......................................................... 9

Table 6 Sensitive Land Use Within 10 km Buffer Area .................................................................. 12

Table 7 Summary of Monitoring Well Installation Details and Depth to Groundwater ................... 16

Table 8 Quality of Local Water Resources ..................................................................................... 18

Table 9 Present and Planned Licensed Water Use, Effluent Irrigation Water ............................... 20

Table 10 Irrigation Scheme Description ........................................................................................... 21

Table 11 Nutrient Application Description ........................................................................................ 23

Table 12 Tree Water Use and Ramp Up Values .............................................................................. 25

Table 13 Projected Wastewater Flows to be used for Irrigation ...................................................... 26

Table 14 Phosphorus Retention and Buffer Index Calculations ...................................................... 31

Table 15 Site Monitoring Program .................................................................................................... 39

Table 16 Contingency Plan Risk Ranking and Mitigation Strategies ............................................... 42

Figures in Text

Figure 1 Site Location Plan ............................................................................................................... 4

Figure 2 Average Monthly Rainfall and Evaporation Data for Dardanup (BoM Site No. 9695) ........ 8

Figure 3 Acid Sulphate Soil Risk Map Classification ....................................................................... 11

Figure 4 Public Drinking Water Source Areas ................................................................................. 13

Figure 5 The Leschenault Catchment Area, Western Australia ...................................................... 14

Figure 6 Projected Tree Water Demand Over 20 Year Period, Current Practice ........................... 28

Figure 7 Monitoring Well and Soil Monitoring Locations ................................................................. 40

Appendices

Appendix 1 Soil and Groundwater Monitoring Results of Woodlot Investigation

Appendix 2 RAW Modelling Data

WATER CORPORATION




Page 1 301012-01582-EN-REP: Rev 0: 19-Oct-2012

1. INTRODUCTION

WorleyParsons was commissioned by the Water Corporation to prepare a Nutrient and Irrigation

Management Plan (NIMP) for the Dardanup Wastewater Treatment Plant (WWTP), located

approximately 5 km southeast of the town of Dardanup and approximately 175 km south of Perth in

Western Australia. This NIMP has been developed in accordance with guidelines prescribed in the

Department of Water (DoW) Water Quality Protection Note 33: Nutrient and Irrigation Management

Plans (DoW 2010a) and Water Quality Protection Note 22: Irrigation with Nutrient-Rich Wastewater

(DoW 2008). The NIMP reporting template was provided by the Water Corporation and is based on

the NIMP checklist found within the DoW Water Quality Information Sheet 04 (DoW 2010b).

1.1 Project Scope

Dardanup WWTP is a 90 kL/d registered plant currently treating approximately 77 kL/d of raw

sewage. The raw sewage is treated via a 3-pond system and the treated wastewater is fed as effluent

to a 22-hectare (ha) blue gum (Eucalyptus globulus) woodlot irrigation area via infiltration channels

located to the west (the “Site”), directly adjacent to the treatment ponds. The Water Corporation is

currently planning to upgrade the Dardanup WWTP to cater for future growth, with the intent of also

progressively increasing the forecasted flow rates from approximately 77 to 566 kL/d by 2040. The

purpose of this NIMP is to cover the period of 2012 to 2022, over which time the Water Corporation

intends to progressively increase their flow rate from approximately 77 to 219 kL/d. It is intended that

from 2012 to 2022, the existing 22-ha blue gum woodlot will continue to be irrigated with treated

wastewater from the Dardanup WWTP.

Prior to development of the NIMP, WorleyParsons was commissioned by the Water Corporation to

undertake a feasibility study of the 22-ha woodlot area adjacent to the Dardanup WWTP to assess

the hydraulic capacity of the woodlot area to receive effluent wastewater and identify potential

impacts as a result of effluent irrigation. The scope of work was conducted in two phases:

• The first phase consisted of a field investigation, including the advancement of soil boreholes,

installation of groundwater monitoring wells, permeability and infiltration testing and

groundwater sampling; and

• The second phase consisted of a desktop assessment and subsequent modelling of the Site

using the software package MEDLI (Model for Effluent Disposal Using Land Irrigation).

Upon completion of the feasibility work, WorleyParsons was then commissioned by the Water

Corporation to develop a NIMP based on the outcomes of the site investigation and subsequent

modelling of the Site. A detailed description of the investigation can be referenced in WorleyParsons

Dardanup Woodlots Site Investigation and Water Balance Report (WorleyParsons 2012).

WATER CORPORATION





1.2 Project Summary

It is intended that the existing 22-ha woodlot area, currently a blue gum plantation, will continue to be

used as an irrigation site for the disposal of treated wastewater from the Dardanup WWTP from 2012

to 2022 with a maximum forecasted flow rate of 219 kL/d.

The proponent’s name and contact details are provided in Table 1.

Table 1 Proponent’s Name and Contact Details

Project Proponent: Water Corporation

Contact Name: Lee Tin Lim

Address: 629 Newcastle Street, Leederville WA 6007

Phone: (08) 9420 3421

Fax: (08) 9420 3179

Email: [email protected]

Details of the Dardanup WWTP, including a description of the project and anticipated start date are

provided in Table 2.

Table 2 Site Identification

Site Location: 33°25’18 S / 115°47’04 E; Approximately 5 km

southeast of the town of Dardanup, WA.

Description of Nature and

Scale of Project:

Dardanup WWTP is a 90 kL/d registered plant currently

treating approximately 77 kL/d of raw sewage with a

projected future growth demand up to 219 kL/d in 2022.

Anticipated Start Date: Use of treated effluent from the Dardanup WWTP to

irrigate the existing 22-ha woodlot area commenced in

1998.

Duration of Intensive Land Use: Irrigation of the existing woodlot area commenced in

1998 with use of the WWTP facility planned to continue

indefinitely. This NIMP has been developed for the 10-

year period from 2012 to 2022.

WATER CORPORATION





2. PROJECT SETTING

The town of Dardanup is located approximately 175 km south of Perth in the South West Region of

Western Australia. Dardanup falls within the Water Corporation’s South West operational boundary.

The Dardanup WWTP is located approximately 5 km southeast of the town of Dardanup.

The proposed wastewater irrigation site, an existing woodlot area planted with blue gum trees

(Eucalyptus globulus), is located west of and directly adjacent to the Dardanup WWTP. The total

irrigation area of the woodlot is approximately 22 ha. All water balance conclusions and outcomes in

this NIMP relate to the total available irrigation area of 22 ha and the expectation that blue gum trees

will continue to be planted and harvested at the Site.

2.1 Site Location and Features

The Dardanup WWTP is located on a westerly grading terrain, with an average slope of 2.5%, near

the eastern edge of the coastal plain. The surrounding land use to the north and east of the WWTP is

predominantly cattle pasture and state forest. The Shire of Dardanup landfill and refuse recycling

facilities are located south of the Dardanup WWTP and the woodlot irrigation area and a blue gum

plantation is located immediately to the west. A site location plan, showing the woodlot area relative to

adjoining properties and existing infrastructure is shown on Figure 1.

No surface water bodies were observed in the woodlot area. The closest natural water courses are

the Ferguson River and Crooked Brook, located approximately 2.5 km to the north east and south

east of the Dardanup WWTP, respectively.

2.2 Existing Site Land Use

The existing site land use of the planned irrigation area is a woodlot area that consists of a blue gum

(Eucalyptus globulus) tree plantation, approximately 22 ha in size. The blue gum plantation has been

used as an irrigation area since 1998 and is located immediately to the west of the Dardanup WWTP.

Cleared land includes an access track through the middle and around the perimeter of the woodlot

area (Figure 1).

2.3 Land Zoning

A review of the Shire of Dardanup Town Planning Scheme No. 3 District Scheme document, updated

in 2011 (Government of Western Australia 2011), indicates that the woodlot area is zoned for

‘General Farming’. The zoning term ‘General Farming’ allows rural activity, including tree plantations.

A review of the Greater Bunbury Land Resource Planning document also illustrates that a 5 km buffer

area surrounding the Dardanup WWTP is compatibly zoned for rural purposes.

WATER CORPORATION





In accordance with State Planning Policy 2.7 Public Drinking Water Policy (Government of Western

Australia 2003), the existing woodlot area is not located within a Public Drinking Water Supply Area

(PDWSA), reservoir protection zone or waterways management area. Additional details regarding

sensitive environments located near the site can be found in Section 6.1.

Figure 1 Site Location Plan

WATER CORPORATION





3. LAND USE AND NUTRIENT APPLICATION DETAILS

3.1 Planned Land Use

It is intended that the woodlot area, located west of the WWTP, will continue to be used for the

irrigation of treated wastewater from the Dardanup WWTP. The woodlot area is planted with blue gum

trees which are currently being irrigated with primary treated wastewater from the Dardanup WWTP.

At this time, the current size of the woodlot area (22 ha) is expected to meet the projected effluent

flow forecast until the year 2022 (up to 219 kL/d).

A preliminary assessment of the average electrical conductivity (EC) value (930 µS/cm) indicates a

low to medium water salinity rating, indicating the primary treated effluent water is suitable for plants

with a moderately sensitive to moderately tolerant salinity threshold (ANZECC 2000).

Average concentrations of E. coli are below the recommended guideline value of less than

1,000 colony forming units (cfu) per 100 ml for thermotolerant coliforms in irrigation water (ANZECC

2000) for non-food crops.

The water quality of the treated effluent from the Dardanup WWTP is presented in Table 3. The total

nitrogen and phosphorus concentrations in the effluent are above the ANZECC guideline values for

freshwater (2 and 0.2 mg/L, respectively; ANZECC 2000). However, ANZECC (2000) has also

proposed guideline values for nitrogen and phosphorus in irrigation water to ensure irrigation is

conducted in an environmentally responsible manner. It is noted that concentrations of the effluent

wastewater are below or meet the recommended short-term trigger values (STVs) for irrigation water

(25 to 125 mg/L and 0.8 to 12 mg/L, respectively; ANZECC 2000). STVs are recommended for

irrigation of less than 20 years and have been developed to ensure that groundwater and surface

water concentrations of nitrogen and phosphorus do not exceed guidelines for drinking water. Further

nutrient mass balance calculations are presented in Section 8.

Irrigation of the woodlots area has been occurring since 1998 (approximately 14 years); therefore for

future use long-term trigger values (LTV; up to 100 years) should also be assessed. Average

concentrations of nitrogen and phosphorus reported in the effluent wastewater exceed the LTV for

both nitrogen and phosphorus (5 and 0.05 mg/L, respectively); however it important to note that

reported concentrations of nitrite and nitrate in shallow groundwater at the site were below their

respective drinking water quality guidelines of 3 and 50 mg/L in 2012 (NHMRC 2011). No drinking

water quality guidelines currently exist for total phosphorus.

Further details regarding the protection of water resources (surface groundwater) can be found in

Sections 6 and 10.

WATER CORPORATION





Table 3 Average Effluent Water Quality Concentrations – Dardanup WWTP

Total

Nitrogen

(mg/L)

Total

Phosphorus

(mg/L)

EC1

(µS/cm)

TDS

(mg/L)

E. coli

(cfu/100ml)2

Freshwater Guideline 3 2 0.2 --- --- <1,000

Irrigation Water STV 4 25-125 0.8-12 --- --- ---

Irrigation Water LTV 4 5 0.05 --- --- ---

Dardanup Effluent

Concentrations 5

19 12 930 595 400

Notes: 1 EC represents electrical conductivity at 25°C

2 E. coli units are presented as colony forming units (cfu) per 100 ml

3 Guideline values refer to values presented in ANZECC (2000);

4 STV = Short Term Trigger Value, LTV = Long Term Trigger Value

5 Average concentration of Dardanup WWTP effluent over a 14-year period (1998-2012)

3.2 Animal Species and Density

The Dardanup WWTP is an active facility operated by the Water Corporation disposing of effluent

irrigation water to a blue gum plantation. No domesticated animals (i.e. cattle, horses, pigs, etc.)

graze within the woodlot area; therefore it is not expected that any additional wastes from

domesticated animals would be contributing to the total nutrient concentrations.

3.3 On-Site Management

The Dardanup WWTP is an active facility; however it is not continuously-manned, and therefore no

personnel are residing on site. No domestic sewage facilities or infrastructure are maintained on site;

therefore no additional domestic wastewater is expected to contribute to the total nutrient

concentrations.

WATER CORPORATION





4. LOCAL RAINFALL AND EVAPORATION

4.1 Local Rainfall and Evaporation Data

Dardanup experiences a typical Mediterranean climate with cool wet winters and warm dry summers.

Average temperatures range from 15 to 30°C in January and from 7 to 17°C in July (BoM 2012). Over

a 20-year period (1991 to 2011), Dardanup had an average annual rainfall of 901 mm (BoM 2012).

The average annual rainfall in 2011 was within historical range and average evaporation was

approximately 1636 mm (Table 4). In general rainfall significantly exceeds evaporation between the

months of May to September (Figure 2).

Table 4 Climate Averages for 2011, Dardanup (BoM Site No. 9695)

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Rainfall

(mm) 72 1 0 67 94 154 117 152 128 42 47 44 918

Evaporation

(mm) 239 233 209 124 73 55 50 70 87 122 164 210 1636

Evaporation

(mm/day) 7.7 8.3 6.8 4.1 2.3 1.8 1.6 2.3 2.9 3.9 5.5 6.8 ---

Notes: Average rainfall and evaporation values are based on 2011 data provided by the Bureau of Meteorology (BoM 2012)

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Figure 2 Average Monthly Rainfall and Evaporation Data for Dardanup (BoM Site No. 9695)

Notes: Average Rainfall values are based on 2011 data provided by the Bureau of Meteorology (BoM 2012)

4.2 Rainfall Runoff and Infiltration Factors

Rainfall runoff and infiltration factors were incorporated into the MEDLI modelling scenarios

developed to assess the hydraulic capacity of the woodlot irrigation area. Irrigation was assumed to

infiltrate the soil surface with no runoff; whereas runoff from rainfall was predicted using the Curve

Number technique (USDA-SCS 1972) and was calculated as a function of daily rainfall, soil water

deficit, plant total cover and a modified curve number taking into account the percentage of green

cover in the woodlot area, for average antecedent moisture conditions.

0

50

100

150

200

250

300

0

20

40

60

80

100

120

140

160

180

Mo

nth

ly E

va

po

rati

on

(m

m)

Mo

nth

ly R

ain

fall

(m

m)

Rainfall and Evaporation Data for Dardanup (BoM 9695)

Rainfall Evaporation

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5. SOILS AND LANDFORM DESCRIPTION

The surficial geology of the site is described at the regional level by the Geological Survey of Western

Australia (GSWA; 1:250,000; 1984). Two major geological units of importance were noted, including:

• Qpa/Qpb (sands and clays) – Bassendean sands and Guildford clays, mainly dune sands and

alluvial sandy clays; and

• Czl (laterite) – primarily massive, but includes overlying pisolitic gravel and minor lateritized

sand.

A detailed site investigation was performed by WorleyParsons in July 2012 to confirm the land

suitability of the irrigated woodlot area for continued effluent irrigation. A geotechnical investigation of

the woodlot area was performed by Golder in 1997 and findings of Golder’s study were supplemented

by WorleyParsons in 2012.

The soil profile at the site can be described as duplexing soils, which are defined as one type of soil

(fine to coarse grained Bassendean sands) overlying another soil of differing characteristics (sandy to

gravelly clays). The A horizon across the site is generally classified as a sandy loam to loam with

relatively high infiltration capacity. The thickness of the A horizon (sand layer) increases towards the

south from 1.3 m noted in soil borehole MW 07A to 2.0 m as noted in soil borehole MW 06A.

Between a depth of approximately 1.0 to 3.0 m, a 0.2 to 0.5 m thick lateritized layer of sandy gravels

with decreased permeability was noted across the site. This lateritized layer overlies a B horizon

comprised of clayey sands/sandy clays intermixed with sandy gravels/gravelly sands. A summary of

the soil profiles at the site has been provided in Table 5.

Table 5 Summary of the Soil Profile within the Woodlot Area

Depth

(mbgs)1

Description Horizon

0.0 to 0.1 Top Soil/Sand: grey, fine to medium grained, trace roots and

organic material, dry

A

0.1 to <2.0 Sand: pale gray, fine to medium grained, sub-angular to sub-

rounded, pale grey

1.3 to 3.0 Sandy gravel, fine to medium grained, lateritized, semi-compacted B

> 3.0 Clayey sands and sandy clays intermixed with sandy gravels and

gravelly sands

Notes: 1metres below ground surface

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5.1 Phosphorus Retention and Buffer Indices (PRI and PBI)

The Phosphorus Retention Index (PRI) analytical data reported for soils collected during the site

investigation reflects the duplex nature of the soils, with low values recorded in the A horizon and

lateritized sandy gravels, and increasing PRI values reported in the underlying clay B horizon. The

increasing PRI values indicate that the capacity of soils to sorb P increases with increasing clay

content and thus increasing sorption is also noted with depth. The topsoil and sands (to a depth of

less than 2 m) reported PRI values that ranged between less than 5 to 12.5, which is typical for

Bassendean sands. The lateritic sandy gravel PRI values ranged between 25 to 380 and values

greater than 700 were generally reported for the intermixed sandy/gravelly clays.

In 2002, Burkitt et al. proposed the Phosphorus Buffer Index (PBI) as the single-point sorption index

to be used by all laboratories in Australia (Bolland and Allen 2003a). The site-specific PBI data

analysed in August 2012 confirm the results of the PRI data, in that PBI values are low (4 to 8) for the

A horizon sands and increase with depth in the subsoil from 13 to 29 for the lateritized sandy gravel

layer and values greater than 680 were generally reported for the sandy/gravelly clays. It is noted that

some of the PBI values reported at depths of approximately 2.5 to 3.5 mbgs are greater than their

respective PRI values, which is considered anomalous and may be the result of heterogeneities in

soil samples collected at the semi-lateritised layer. Further testing of the soils in this area chould be

conducted to confirm results; however it is important to note that results of both PRI and PBI testing

indicate that the phosphorus sorption capacity of the upper soil layer is considered to be very low to

moderate (Bolland and Russell 2010).

Overall, values of PRI and PBI indicate that the capacity of the soils to sorb phosphorus is generally

very low to moderate in the sands and sorption capacity increases with depth likely due to increasing

clay content.

5.2 Acid Sulphate Soil Risk Evaluated

A review of the Atlas of Australian Acid Sulfate Soils, developed by the Australia Soil Resource

Information Service (ASRIS) indicates that the likelihood of acid sulphate soils in the Dardanup region

is negligible with a low probability rating (Figure 3).

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Figure 3 Acid Sulphate Soil Risk Map Classification

There is at least a two metre vertical separation to the regional water table across the site; however,

due to the duplex nature of the soils, perched groundwater is potentially present in areas where the

lateritized layer is compacted. A lateritized layer was noted throughout the woodlot area at a depth of

approximately 2.5 to 3.0 m beneath the natural ground surface (mbgs); however it was generally

considered to be non-compacted throughout the woodlot area. During the site investigation, no

surface water expressions or water logged areas were noted in the woodlot area to indicate that the

woodlot soils are susceptible to acid drainage generation.

5.3 Proposed Earthworks Details

At this time, no amendments to the woodlot landform or proposed earthworks have been anticipated

or recommended.

5.4 Details of Any Imported Soil Amendment

At this time, no amendments to the soil profile within the woodlot area have been undertaken or are

planned for the site.

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6. WATER RESOURCES DESCRIPTION AND USE

A site investigation was performed by WorleyParsons in July 2012 to assess surface water and

groundwater conditions within the woodlot area (WorleyParsons 2012).

6.1 Sensitive Environments Located Near the Site

A review of the DoW (2012) Geographic Data Atlas and the Bunbury Groundwater Areas Subarea

Reference Sheet (DoW 2009) was undertaken in August 2012 to assess the potential for sensitive

environments within a 10-km buffer area of the Dardanup WWTP and adjacent woodlot. No sensitive

land use areas were noted within the 10 km buffer area of the Site, with the exception of two surface

water features, Ferguson River and Crooked Brook, located approximately 2.5 km north and south of

the site, respectively (Table 6Table 6).

Table 6 Sensitive Land Use Within 10 km Buffer Area

Sensitive Land Use Applicable

(Y) or (N)

Approximate Distance From Site (m)

Public Drinking Water

Source Areas (PDWSA)

N A review of PDWSAs in the DoW Geographic Atlas

database indicates Dardanup WWTP is approx.

10 km up-gradient of the nearest P3 area (Bunbury

Water Reserve; Figure 4)

Buffers to Water Supply

Sources

Y Approx. 2.5 km to nearest surface water source,

Ferguson River and Crooked Brook

Clearing Control

Catchments

N WWTP and woodlot are not located within clearing

control catchment areas

Private Water Supply

Sources (PWSS)

Y Licensed water use for Superficial aquifer is

42,800 kL/yr in Dardanup Subarea for stock,

domestic and garden use. Distance to closest

PWSS is unknown

Underground Ecological

Functions

N No groundwater dependant ecosystems (GDEs) are

present at the site

Waterway Ecological and

Social Values

N The Water Corporation supplies the town of

Dardanup with drinking water from the Leederville

Formation aquifer

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Sensitive Land Use Applicable

(Y) or (N)

Approximate Distance From Site (m)

Wetland Ecology N No major wetlands found in woodlot area. Fifteen

major EPP wetlands in subarea; however the

nearest to Dardanup WWTP is located close to

Ferguson River (~2.5 km away)

A review of PDWSAs in the DoW Geographic Atlas Database (DoW 2012) is illustrated in Figure 4,

below. The closest PDWSA to the Dardanup WWTP is the Bunbury Water Reserve, a P3 protection

area, located approximately 10 km west of the Site.

Figure 4 Public Drinking Water Source Areas

WWTP

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6.2 Surface Water Description

The Dardanup WWTP and woodlot area is located within the Leschenault Catchment of Western

Australia. The Leschenault water catchment in the south-west of Western Australia is an area of

~1980 km2 (square kilometres) that drains into the Leschenault Estuary just north of Bunbury (Figure

5). One of the potential risks of using treated effluent as irrigation water is the offsite discharge of

nutrients into nearby surface water bodies.

There are no major surface water features (wetlands, rivers, etc.) located within or immediately

downgradient of the Site. The closest surface water features to the Site are the Ferguson River,

located approximately 2.5 km north of the Site and Crooked Brook, located approximately 2.5 km

south of the Site. The Ferguson River and Crooked Brook are located north and south, respectively,

of the anticipated surface water and groundwater flow directions, which are towards the west.

Figure 5 The Leschenault Catchment Area, Western Australia

WWTP

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Given the high infiltration capacity of the surface soil (fine to coarse grained Bassandean sands), it is

expected that surface run-off will be relatively low compared to sub-surface flow.

The proposed irrigation area (blue gum woodlot) is not subject to seasonal flooding nor is it located

within any PDWSA, reservoir protection zone or waterways management area.

6.3 Groundwater Description and Depth

There are two distinct hydrogeological systems present beneath the site: a shallow seasonal

(potentially perched) water table and a permanent regional groundwater table. The duplex nature of

the soils across the site produces two distinctive permeabilities, which causes water to flow

preferentially in a horizontal direction. The A horizon across the site is classified as a sandy loam to

sand with a relatively high infiltration capacity. At depths of approximately 1 to 3 mbgs, a 0.2 to 0.5 m

a lateritized sandy gravel layer is noted throughout the woodlot area which overlies the B horizon

(sandy clays intermixed with gravelly sands). Areas in which the lateritized layer is more compact and

where clays are present have relatively low permeabilities and thus a much lower infiltration capacity.

The groundwater monitoring network in the woodlot area consists of six monitoring wells completed

within the upper (shallow, potentially perched) groundwater bearing zone (“A-series”; except MW01A;

UGBZ). These wells are completed at depths of approximately 3.0 to 5.0 mbgs (Table 7) and

measured groundwater levels in the UGBZ ranged from 0.7 to 3.3 mbgs, in August 2012.

An additional nine monitoring wells (“B” and “C”-series) are completed at depths ranging from 18.5 to

43.6 mbgs in the lower groundwater bearing zone (LGBZ) and Leederville Aquifer. Measured depths

to groundwater in the B- and C-series wells ranged from 4.72 to 24.2 mbgs in August 2012. It is likely

the regional groundwater table resides at a depth of approximately 8.5 mbgs and that the depth to

groundwater in the Leederville Formation aquifer (>40 mbgs) resides at about 16 to 24 mbgs.

A summary of monitoring well installation details and depth to groundwater is shown on Table 7. A

figure with groundwater surface elevations and inferred groundwater flow direction is shown as

Figure A and an illustrative cross-section is shown as Figure B.

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Table 7 Summary of Monitoring Well Installation Details and Depth to Groundwater

Well ID Easting (m) Northing (m) Total Depth of

Well (mbgs)

Depth to

GW (mbgs)

MW 01A 387033.45 6301005.40 18.56 7.87

MW 01B 387033.45 6301005.40 33.56 24.20

MW 01C 387033.45 6301005.40 43.64 25.831

MW 02A 386883.49 6301206.79 3.14 0.72

MW 02B 386883.49 6301206.79 29.35 19.81

MW 02C 386883.49 6301206.79 41.45 20.661

MW 03A 386518.42 6301259.05 3.25 2.22

MW 03B 386518.42 6301259.05 26.00 4.72

MW 03C 386518.42 6301259.05 43.60 15.97

MW 04A 386372.16 6301297.62 3.26 2.10

MW 04B 386372.16 6301297.62 29.13 8.65

MW 04C 386372.16 6301297.62 41.41 16.361

MW 05A 386484.5639 6301041.557 4.10 2.44

MW 06A 386661.4056 6300814.158 5.00 3.34

MW07A 386729.7444 6301416.146 4.00 1.07 Notes:

1 Indicates water level collected April 2012. Water levels for wells deeper than 40 mbgs were not collected in August

2012.

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The hydraulic conductivity (K), effective porosity (ne), and hydraulic gradient (i) of a saturated medium

can be used to estimate the average linear flow velocity (v) of groundwater (Equation 1):

en

Kiv = Equation 1

A conservative estimate of v (i.e. the fastest migration speed of a dissolved phase non-reactive

constituent) can be made by selecting the maximum values of K and i across the Site, and selecting a

conservative value for ne. From the difference in groundwater contour elevations (∆h), in conjunction

with the distance between contours (∆l), the maximum hydraulic gradient (i = ∆h/∆l = 0.015) across the

Site was calculated for the UGBZ.

Assuming that the effective porosity is in the order of ne = 0.25 for sandy material (Todd 1959), and

taking the maximum hydraulic conductivity recorded (0.016 m/day; 1.9 x10-7 m/s), the maximum linear

flow velocity for the UGBZ can be estimated. A flow velocity calculation for the UGBZ at the site is

shown below:

yearmyeardaysdaym

v /4.025.0

/365015.0/016.0≅

××=

Groundwater flow through the sandy/clayey and gravelly/clayey material is generally considered to be

slow due to the low hydraulic conductivity of the aquifer material at the site. In general, groundwater

flow across the Site is inferred to be in the west-southwest direction.

Infiltration testing of the topsoil and relatively permeable sand layer (i.e. the unsaturated zone) was

also conducted in August 2012. The geometric mean K-value (1.22 x 10-1

m/d) was used to calculate

an average flow velocity of 2.3 m/year for the unsaturated zone. This value is an order of magnitude

faster than the saturated zone velocity (0.4 m/year), reflecting the higher permeability and

unsaturated conditions of the sand material on site.

6.4 Quality of Local Water Resources

Monitoring wells were sampled for groundwater quality in August 2012 and a detailed summary of the

results has been presented in Appendix 1. A brief summary of routine and nutrient parameter water

quality results is provided in Table 8.

In general, groundwater is considered to be fresh with EC values of less than 580 µS/cm (with the

exception of MW07A) and TDS values at or less than 521 mg/L. Total nitrogen values ranged from

4.6 to 14.6 mg/L and total phosphorus values ranged from 0.2 to 8.2 mg/L in the shallow monitoring

wells.

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Total nitrogen (TN) values ranged from 4.6 to 14.6 mg/L. At this time, no guidelines currently exist for

TN in drinking water and no specific health effects have been associated with TN (NPI 2012; NHRMC

2011). However, concentrations of the mobile forms of nitrogen, nitrite (NO2) and nitrate (NO3), were

compared to their respective Australian Drinking Water Guidelines (ADWG; NHMRC 2011) to assess

potential impacts to groundwater quality. Samples analysed in August 2012 reported nitrite and nitrate

values less than their respective ADWG values of 3 and 50 mg/L (Appendix 2; NHMRC 2011).

Total phosphorus (TP) values ranged from 0.2 to 8.2 mg/L in the shallow monitoring wells. At this

time, no guideline value exists for phosphorus in the ADWG (2011); although reported concentrations

were generally less than 1.4 mg/L, with the exception of a reported value of 8.2 mg/L at MW03A. The

reported value at MW03A appears to be anomalous when compared to historical data and should be

reconfirmed in future sampling events. TP guidelines for freshwater systems (rivers and streams) in

the ANZECC (2000) guidelines are between 0.01 and 0.1 mg/L; however the closest natural water

system is approximately 2.5 km away from the Dardanup WWTP, therefore these guidelines are not

directly applicable. It is also noted that there are no specific health effects directly associated with TP

(NPI 2012).

Table 8 Quality of Local Water Resources

Local Water

Resource

Parameters Nutrients (mg/L)

pH

Salinity

(EC)

µS/cm

Turbidity

(TDS)

mg/L

Total

Nitrogen

(N)

Total

Phosphorus

(P)

Total

Potassium

(K)

Shallow Groundwater

MW02A 4.4 181 118 8.2 0.20 <1

MW03A 6.4 220 143 11.3 8.21 3

MW04A 6.5 181 118 6.4 1.40 1

MW05A 7.6 580 377 4.6 0.72 5

MW06A 7.1 386 251 14.6 1.19 7

MW07A 6.7 802 521 8.7 1.08 5

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Local Water

Resource

Parameters Nutrients (mg/L)

pH

Salinity

(EC)

µS/cm

Turbidity

(TDS)

mg/L

Total

Nitrogen

(N)

Total

Phosphorus

(P)

Total

Potassium

(K)

Intermediate and Deep Groundwater

MW01A 6.4 174 113 8.60 0.26 <1

MW1B 5.9 176 114 2.90 0.11 <1

MW02B 5.9 242 157 3.00 0.46 <1

MW03B 6.1 200 130 0.80 0.02 <1

MW04B 6.3 197 122 0.60 0.01 1

MW04C 6.0 251 163 0.20 <0.01 2

Source: Samples collected by WorleyParsons and analysed by ALS Laboratory (August 2012)

Reported concentrations of metals and trace elements were generally at or below their respective

laboratory detection limits and respective freshwater and drinking water guideline values (ANZECC

2000 and NHMRC 2011), with the exception of concentrations of aluminium, iron, manganese,

selenium, strontium and titanium (Appendix 1). Reported concentrations of metals and trace elements

are likely due to natural groundwater conditions.

6.5 Present or Planned Licensed Water Use

At this time, no shandying or supplemental use of groundwater or surface water is anticipated. All

effluent irrigation will be supplied by treated wastewater from the Dardanup WWTP.

The forecasted flow rate for 2012 through 2022 is shown in Table 9. The current licensed capacity of

the Dardanup WWTP is 90 kL/d. It is anticipated that that volume of effluent will increase

progressively on an annual basis from 77 to 219 kL/d up until 2022.

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Table 9 Present and Planned Licensed Water Use, Effluent Irrigation Water

Year Daily Flow Rate

(kL/d)

Annual Volume

(kL/year)

2012 76 27,740

2013 78 22,470

2014 80 29,200

2015 90 32,850

2016 1071 39,055

2017 1251 45,625

2018 1431 52,195

2019 1621 59,130

2020 1801 65,700

2021 2001 73,000

2022 2191 79,935

Notes: 1 Indicates that Forecasted Flow Rate is above the current licensed capacity

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7. SITE MANAGEMENT

Treated effluent from the Dardanup WWTP is currently being used as effluent irrigation water for the

existing woodlot area directly adjacent to the WWTP. A feasibility study of the woodlot area was

undertaken in July 2012 to confirm that irrigation of the woodlot area is sustainable for the anticipated

flow forecast until 2022 (up to 219 kL/d).

7.1 Irrigation Scheme

The current irrigation scheme consists of treated wastewater being conveyed via an underground

pipe, approximately 140 m in length, to a second outflow control valve at the irrigation channels. The

outflow control valve is used to manually regulate the flow to the northern and southern woodlot

irrigation channels. Wastewater then percolates through the woodlot area in a westerly direction,

consistent with surface contours. A detailed description of the Irrigation Scheme has been provided

below in Table 10.

Table 10 Irrigation Scheme Description

Item Description Units Comments

a) Source of Irrigated Water Treated effluent from the Dardanup WWTP.

Provide Information on Recycled

Water Use No irrigation water is collected for recycling.

b) Water Storage Location on Site

Treated wastewater is stored in 3 treatment ponds

located east of the woodlot area. Water Corporation

currently plans to expand the pond area once capacity

is reached.

Water Storage Capacity kL

Approximate volume of the treatment ponds is 7,000 m3

(kL) with an expansion planned up to approximately

17,000 m3. .

c)

Zones to be Irrigated to Suit

Plantings and Expected Water

Uptake

ha

Existing woodlot area (blue gum plantation) has a total

area of 22 ha. Expected water uptake is >300 kL/d at

full maturity and minimum of 180 kL/d after harvesting.

d) Sprinkler Type Current irrigation design consists of irrigation channels

through the woodlot area and land surface flooding.

Sprinkler Layout Not applicable.

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Operating Pressure kPa Not applicable.

e) Water Application Rate kL/d 77 to 219 kL/d, over a period of 2012 to 2022.

Watering Duration mins/

day Variable.

Watering Frequency per

week Up to 7 days per week.

f) Seasonal Variation and/or

Planned Expansion of Activities

Potential to expand size of treatment ponds and

progressively increase effluent irrigation flow rate from

77 kL/d to 219 kL/d over 10 year period. Currently

greatest volume of irrigation (>40%) occurs over winter

months (Jul-Sep).

g) Irrigation Management Measures

and Monitoring

Irrigation management measures and monitoring are

noted in detail in Sections 8, 9 and 10.

h) Irrigation Shut Off Controls

During Wet Weather

Out flow control is manually operated by Water

Corporation personnel.

i) Soil Protection Measures

Potential impacts to surface soils will be monitored and

shallow groundwater quality assessed annually. A soil

management plan will be implemented if any impacts

are observed.

j) Irrigation Runoff kL

Due to the high permeability of the underlying sand

layer and high plant water uptake of blue gum, no

significant volume of irrigation runoff is expected at the

site.

Irrigation Capture kL At this time no irrigation capture system has been

implemented at the site.

Irrigation Storage kL At this time no irrigation storage system has been


Irrigation Recycle kL At this time no irrigation recycle system has been


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k) Irrigation Management to Soil

Salinity Issues

Soil monitoring will be conducted on an annual basis to

identify any impacts. A soil management plan will be

implemented if any salinity impacts are observed.

l)

Describe Any Irrigation Water

Contaminant Control Pre-

Treatment

Raw sewerage discharges directly to the first treatment

pond area via a surge tank and solids settle out and

decompose prior to wastewater passing through 2

additional treatment ponds.

At this time, no additional fertilizer or nutrient applications are anticipated for the woodlot (blue gum

plantation) area (Table 11).

Table 11 Nutrient Application Description


a) Fertiliser Crop Needs Not applicable

Fertiliser Nutrient Availability (including soil

and/or plant tissue testing)

Not applicable

b) Nutrient Needs Defined for: Not applicable

Planned Short-Term Crops at Various Points in

their Growth Cycle

Not applicable

c) Types and Constituents of Fertilisers %N %P Not applicable

d) Fertiliser Application Details: Not applicable

Fertiliser Method Area Quantity Frequency

N/A N/A N/A N/A N/A

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8. WATER BALANCE SCENARIOS

WorleyParsons conducted a feasibility study of the current irrigation area in 2012 which included a

detailed water balance and nutrient balance modelling study. The purpose of the water balance

modelling was to establish the pre- and post-irrigation water balance and the capacity of the woodlot

area to receive the intended quantity of wastewater. A brief description of the modelling scenarios and

results is provided below. The water balance scenarios consisted of three stages: first, a daily time

step simulation water balance model was conducted in MEDLI to assess pre-irrigation water balance

and potential post-irrigation impacts. The second stage consisted of calculating the potential woodlot

water demand, including predicted wastewater flows and disposal demand, such that an irrigation

water balance could be determined. Lastly, the third stage consisted of calculating the nutrient mass

balance and assessing potential impacts of effluent irrigation on the nutrient mass balance of the

woodlot area based on the average concentrations of nitrogen and phosphorus in the effluent

wastewater.

8.1 Site Water Balance

8.1.1 MEDLI Model

The MEDLI modelling software package was used to model the site water balance on a daily time-

step. MEDLI was developed jointly by the CRC for Waste Management and Pollution Control, the

Queensland Department of Natural Resources and the Queensland Department of Primary

Industries. Additional details regarding the modelling approach are summarized in Appendix 2.

8.1.2 MEDLI Results

The modelling scenarios run in MEDLI illustrate that the blue gum plantation has a major impact on

the water balance at the site. The first model scenario run in MEDLI consisted of the full forecasted

flow rate (up to 566 kL/d) with no vegetation (i.e. pre-development of the blue gum plantation).

Subsequent model scenarios included the blue gum plantation as a 70% vegetative cover. This was

anticipated as it is expected that the blue gum trees decrease the effective precipitation across the

site due to an increase in interception. Blue gum trees take up a significant volume of water on a daily

basis. This is noted in the modelling scenarios as a reduction in groundwater elevation and

subsequent flow as water is taken up from the soil profile.

The MEDLI modelling also indicates that infiltration and evapotranspiration are higher under a blue

gum plantation regime. It is expected that an increase in infiltration also reduces overland flow and

stores more water in the catchment which results in infiltration. An increase in evapotranspiration is

primarily noted in the summer months during periods when evaporation rates are greater than

precipitation rates.

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A site water balance specifically for the period of 2012 to 2022 was conducted to assess the effect of

irrigating with a maximum forecasted rate of 219 kL/d on the 22-ha woodlot area. Results of the

modelling indicate that a maximum daily flow of 219 kL/d with a 70% vegetative cover would result in

less than 1 mm of runoff and no overtopping of the ponds with their current size (7,000 m3).

8.2 Irrigation Water Balance

The second stage of the water balance study was undertaken to predict potential plant water uptake

from the existing woodlot. In order to undertake the woodlot water balance, two assumptions were

required with respect to tree demand and forestry management. It was assumed that the total size of

the woodlot area (22 ha) would remain the same for the period between 2010 and 2022 and that the

harvest period would be every 10 years, with the most recent harvest occurring in 2010.

Plant uptake data (i.e. water use data) was also supplemented by literature data, in particular from

studies conducted by the University of Western Australia (UWA) at the Albany Tree Farm (ERG

2001), a blue gum plantation. Woodlot tree water demand was derived using blue gum water use

values and ramp up (with growth) mature usage correlates with root uptake for UWA SNAPS model

for Albany Tree Farm (~566 mm/yr). Crop factor and water usage values that were used for the blue

gum water irrigation area are shown in Table 12. It is expected that blue gums reach full growth

maturity in year 4 and thus water ramp up values would remain stable thereafter until the trees were

harvested.

Table 12 Tree Water Use and Ramp Up Values

Age 1 2 3 4 5+

Factor 0.5 0.7 0.85 1 1

Usage (mm/d) 1.57 2.198 2.669 3.14 3.14

An additional component of this stage was to calculate the required wastewater disposal depth and

volumes from the Dardanup WWTP. This is to ensure that there is sufficient tree water demand to

allow for the sustainable irrigation of wastewater (i.e. to ensure that the required disposal volume

doesn’t exceed the plant water use, leading to over-irrigation). The depth of irrigation was also

calculated to ensure that the predicted depth of irrigation and depth to groundwater has a minimum of

2 m separation as stipulated in WQPN:22 (DoW 2008).

The predicted wastewater flows were provided by the Water Corporation (Table 13). Monthly

averages of irrigation were based on percentages, as observed in previous years, with the greatest

irrigation occurring during the winter months (greater than 40%; Jun-Aug). It was also assumed that

irrigation occurred daily throughout the year and that no storage of water was required.

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Table 13 Projected Wastewater Flows to be used for Irrigation

ADF1

(kL/d)

Annual

Total

(kL)

20% 20% 17% 8% 7% 2% 2% 2% 2% 5% 9% 7%

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun

2010 77 19893 3978 3978 3381.8 1591.4 1392.5 397.9 298.4 298.4 397.8 994.6 1790.3 1392.5

2011 70 25550 5110 5110 4343.5 2044 1789.5 511 383.25 383.25 511 1277.5 2299.5 1788.5

2012 76 27740 5548 5548 4715.8 2219.2 1941.8 554.8 416.1 416.1 554.8 1387 2496.6 1941.8

2013 78 22470 5694 5694 4839.9 2277.6 1992.9 569.4 427.05 427.05 569.4 1423.5 2562.3 1992.9

2014 80 29200 5840 5840 4964 2336 2044 584 438 438 584 1460 2622 2044

2015 90 32250 6570 6570 5584.5 2622 2299.5 657 492.75 492.75 657 1642.5 2956.5 2299.5

2016 107 39055 7811 7811 6639.35 3124.4 2733.85 781.1 585.825 585.85 781.1 1952.75 3514.95 2733.85

2017 125 45625 9125 9125 7756.25 3650 3193.75 912.5 684.375 684.37 912.5 2221.25 4106.25 3193.75

2018 143 52195 10439 10439 8873.15 4175.6 3653.65 1043.9 782.925 782.925 1043.9 2609.75 4697.55 3653.65

2019 162 59130 11826 11826 10052.1 4730.4 4139.1 1182.6 886.95 886.95 1182.6 2956.5 5321.7 4139.1

2020 180 65700 13140 13140 11169 5256 4599 1314 985.5 985.5 1314 3225 5913 4599

2021 200 73000 14600 14600 12410 5840 5110 1460 1095 1095 1460 3650 6570 5110

2022 219 79935 15987 15987 13588.95 6394.8 5595.45 1598.7 1199.03 1199.025 1598.7 3996.75 7194.15 5595.45

Notes: 1Average Daily Flow

Figure 6a shows the projected water demand of the entire 22-ha blue gum woodlot over a 20-year

period from 2010 to 2030 for 10-year harvest cycles, with no staggering of planting or harvesting.

Figure 6b shows the same data converted to an irrigation depth over the available irrigation area

(22 ha).

The annual forecasted flow volume begins in 2010 at 19.9 ML/yr (77 kL/d) and progressively

increases to 143 ML/yr (393 kL/d) in 2030. Figure 6a shows that the minimum annual age-weighted

plant demand is approximately 66 ML/yr (180 kL/d) during the period immediately after harvesting of

the woodlot. The last minimum plant water demand occurred in 2010, immediately after harvesting

and it is expected that if harvesting occurs in 2022 the plant water demand would again decrease, at

which point it would be below the annual required disposal volume (Figure 6a).

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As noted, after the harvesting period in 2020, it is expected that the plant water demand will decrease

until the blue gum trees reach maturity. Therefore, it is observed that in 2021, the irrigation water

volume may exceed the plant water demand by approximately 2 ML. However, Water Corporation is

currently planning on expanding their pond storage volume in 2017 from 7,000 m3 to 17,000 m

3 which

will allow for an additional 50 days of storage and evaporation losses at the average annual daily flow

rate (180 kL/d), thereby offsetting the decrease in plant water demand. It is expected that by 2022,

the plant water demand will increase to a point at which it is again above the irrigation water volume

(Figure 6a).

The required irrigation disposal volume was also converted to an irrigation depth based on the

available irrigation area of 22 ha and the calculated depths were then compared to the tree lot water

demand. For the period between 2012 and 2022, the required disposal demand (up to 219 kL/d) does

not exceed the mature tree lot demand of approximately 3.14 mm (ERG 2001). The maximum

irrigation depth over the 10 year period is approximately 1.2 mm. With a minimum UGBZ greater than

2 mbgs, a 2 m separation from the irrigation depth the UGBZ is achieved. It is also noted that the

UGBZ consists of a potentially perched groundwater system with groundwater measured at between

0.7 to 1.0 mbgs; however this perched system is not laterally continuous throughout the site and is

separated from the regional water table and Leederville aquifer by a semi-confining, lateritized layer.

Ultimately, results of the modelling indicate that the 22 ha woodlot can sustainably be irrigated up to

Water Corporation’s ADF rate of 219 kL/d over the period of 2012 to 2022. An increase in the flow

forecast would require a re-evaluation of the potential hydraulic capacity of the woodlot and plant

water uptake of the blue gum plantation, most notably during periods immediately after harvesting

when plant water demand it at a minimum.

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Figure 6 Projected Tree Water Demand Over 20 Year Period, Current Practice

2010 2015 2020 2025 2030 2035

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8.3 Nutrient Balance Modelling

Based on the forecasted flow rate provided by the Water Corporation, it is expected that there will be

an increase in the ADF rate from 77 to 219 kL/d over the period of 2012 to 2022. Nutrient balance

modelling of the existing woodlot area has been conducted to determine the potential for nutrients to

be exported from the site through overland flow and/or subsurface discharge and their resulting offsite

impacts, as a result of increasing the flow rate.

8.3.1 Total Nitrogen

Leaching of nitrogen to groundwater is one of the primary factors that could limit the sustainability of

the effluent irrigated woodlot. Thus, a nitrogen mass balance was undertaken in accordance with the

CSIRO guideline “Sustainable Effluent-Irrigated Plantations: An Australian Guideline” (CSIRO 1999).

The mass balance approach calculates the residual nitrogen available for leaching after inputs (i.e.

nitrogen in effluent and released from soil organic matter) and outputs (gaseous loss and biomass

accumulation) are taken into account.

Where applicable, nitrogen values from the feasibility study were used and supplemented by literature

values for a similar study conducted in Albany (ERG 2001). A nutrient and hydrological study was

conducted at the Albany Tree Farm, a blue gum plantation on similar soils (duplex soils with loam

over laterite) and similar climatic conditions to the Dardanup WWTP irrigation site. In the absence of

site specific data from the Dardanup WWTP, average values of the rate of nitrogen assimilation in the

above ground biomass, rate of denitrification and nitrogen mineralisation were used to calculate

theoretical values of leachable nitrogen.

The average total nitrogen concentration (19 mg/L) in the effluent from the Dardanup WWTP was

used to provide the nutrient loading values. A conservative total nitrogen load of 69 kg/ha/year was

used for the tree lot irrigation, based on the maximum predicted irrigation rate of 3.6 ML/ha/yr in 2022

(for an ADF of 219 kL/d).

The balance between nitrogen inputs and outputs is expressed in Equation 1:

LN + NS – NV – NG = NL Equation 1

Where:

LN = Total nitrogen load (applied by irrigation water);

NS = Available nitrogen in soil;

NV = Nitrogen uptake by vegetation;

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NG = Nitrogen lost due to volatilisation; and

NL = Nitrogen available for leaching (CSIRO 1999).

Where, for an ADF rate of 219 kL/d, a total nitrogen concentration of 69 kg/ha/yr is applied over the

22 ha and the maximum available nitrogen (as N) for the coarse sandy soil at Dardanup is estimated

at approximately 150 kg/ha/yr (ERG 2001). Studies of blue gum plantations estimate that nitrogen

uptake is approximately 200 kg/ha/yr and that less than 10 % of nitrogen is assimilated as ammonium

(NH4+

). Using these values, the average concentration of leachable nitrogen for the woodlot area is

calculated as:

NL = - 2 kg/ha/yr

Based on this assessment, the likelihood of nitrogen leaching from the site is low; more nitrogen

is being assimilated and up-taken by the blue gum trees in comparison to the amount of nitrogen

being input by effluent. The key variable in the nitrogen mass balance is the rate in which

nitrogen is assimilated into above ground biomass. Biomass assimilation changes over time as

the plantation matures; the highest assimilation is during the early growth period and decreases

as the tree growth slows. Plantation management is an important tool in reducing the likelihood of

nitrogen export from the site.

8.3.2 Phosphorus

Phosphorus is a key contaminant of concern due to it being a limiting nutrient for algae growth, which

can lead to algal blooms, oxygen depletion and fish kills. A similar mass balance approach was

undertaken for Total Phosphorus (TP). Phosphorus is less mobile in the sub-surface than nitrate, thus

soil adsorption is an important component in determining its potential offsite export. The Phosphorus

Retention Index (PRI) and Phosphorus Buffer Index (PBI) values were analysed for various soil types

across the site. The minimum and maximum PRI and PBI were subsequently used in the mass

balance calculations. In order to determine the potential capacity of the irrigation area to adsorb

phosphorus, the PRI and PBI values were converted to an adsorption capacity in units of mg P/kg of

soil. Bolland et al. (2003b) presents a method for the conversion of PRI and PBI to the Ozane and

Shaw (O&S) value which is a measure of Phosphorus sorbed or retained in the soil matrix as mg P/kg

of soil. Using the method presented in Bolland et al. (2003b) the PRI and PBI values were converted

to O&S values for the lowest, highest and average PRI and PBI values reported from the site

investigation.

The method outline in the CSIRO guideline “Sustainable Effluent-Irrigated Plantations: An Australian

Guideline” (CSIRO 1999) was used to determine the Phosphorus retention time for the irrigation area,

using the low, high and average PRI and PBI values. The Total Phosphorus Retention (TPR) capacity

was calculated from the Equation 2:

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�� &��

�� !"##$%&'()"*+,& -./011 Equation 2

An average soil bulk density of 1,800 kg/m3 was assumed for the entire site, based on a

geometric mean value of laboratory reported values for the sandy soils, with an average soil layer

thickness of 1.5 m. In order to calculate the minimum phosphorus retention time required, the

most conservative TP loading rate was applied based on the maximum flow rate of 219 kL/d over

an irrigation area of 22 ha. With an average TP concentration of 12 mg/L, the annual TP loading

rate (LP) was calculated to be 44 kg/ha/yr, using the maximum expected flow rate of 219 kL/d

over 22 ha. The TP retention time was thus calculated based on Equation 3:

�� 23456 Equation 3

Results from PRI and PBI calculations are summarized in Table 14.

Table 14 Phosphorus Retention and Buffer Index Calculations

PRI PBI

Parameter Symbol Low High Average Low High Average

Irrigation Area (m2) 220,000

Irrigation depth (mm) <210

Conc of P in effluent (mg/L) 12

Annual P loading rate (kg/ha/yr) Lp 44

P retained (mg P/kg of soil) 1.7 21.4 16.5 0.3 48.5 10.1

Soil bulk density (kg/m3) BD 1800.0 1800.0 1800.0 1800.0 1800.0 1800.0

Soil thickness ST 1.5 1.5 1.5 1.5 1.5 1.5

Total P retention (kg/ha) TPR 46.9 578.1 446.7 9.3 1309.4 272.5

P Retention Time (years) PRT 4 48 37 1 109 23

Conversion of PRI to O & S values

PRI / PBI 6.0 550.0 220 4.0 680.0 129

Observed Conc P in supernatent (mg P/L) c 7.7 0.4 0.7 8.3 0.3 1.3

Sorption onto soil (mg P/L) S 46.2 193.0 186.7 9.5 406.8 145.5

Freundich coefficient b 0.35 0.35 0.35 0.41 0.41 0.41

Coefficient q --- --- --- 0.08 0.08 0.08

O & S value (mg P/kg of soil) OS 1.7 21.4 16.5 0.3 48.5 10.1

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Based on the above assumptions and the variability in soils across the site and using the

average PRI and PBI values for the soils in the woodlot area, the values calculated for the PRT

vary from 4 years (low PRI/PBI soils) up to 100 years (high PRI/PBI) soils, with an average PRT

of between 23 to 37 years (Table 14).

The PRI and PBI values indicate that the sandy soils have limited ability to adsorb phosphorus

which is likely due to low content of clay minerals and iron and aluminium hydrous oxides

(Bolland and Russell 2010). It is expected that over time mobile orthophosphorus will be uptaken

by the blue gum trees and immobile forms of phosphorus will be retained by the clayey sands

noted at greater than 3 mbgs. The average PRT of 23 to 37 years exceeds the planned duration

of irrigation in the woodlot for the period of 2012 to 2022, with PRTs calculated up to 100 years

for finer-grained soils; therefore the likelihood of off-site export of phosphorus through discharge

in the sub-surface is considered low.

It is also noted that in 1999, the National Environment Protection Council published an interim

Ecological Investigation Level guideline value for phosphorus in soil of 2,000 mg/kg for contaminated

sites (NEPC 1999). Reported total phosphorus values from the site investigation in August 2012

range from 15 to 48 mg/kg in the woodlot soils, well below the NEPC EIL (NEPC 1999).

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9. DRAINAGE AND CONTAMINANT LEACHING CONTROLS

9.1 Design and Function of Artificial Water Controls

The Dardanup WWTP consists of three treatment ponds, with an approximate volume of 7 ML,

representing 90 days of storage at the 2012 average daily site inflow rate (77 kL/d) and 30 days of

storage at the 2022 average daily site inflow rate (219 kL/d). Water Corporation currently has plans to

expand their treatment pond system to an approximate pond volume of 17 ML, providing up to 77

days of storage at peak water inflows in 2022 (219 kL/d). During times of peak rainfall, holding times

will be reduced.

Raw sewage discharges directly from the sewer main to the northwest corner of the treatment pond

area via a surge tank with an access manhole. Solids are settled out and decompose in-situ as

wastewater flows pass through three primary (facultative) treatment ponds before reaching the fourth

treatment pond. Outflow from the fourth treatment pond to the woodlot area is controlled by a manual

flow valve on the outflow pipe.

9.2 Management/Monitoring of Water Bodies

No surface water bodies exist on site and the closest natural water courses (Ferguson River and

Crooked Brook) are located approximately 2.5 km away from the site; therefore direct impacts to

surface water are not anticipated as a result of effluent irrigation of the woodlot area.

Wastewater irrigation of the woodlot area will involve summer and winter irrigation. In winter, the

irrigation rate will exceed evapotranspiration rates and therefore greater infiltration is expected to

occur. This could potentially result in some leaching of nutrients (nitrogen and phosphorus) into

groundwater which eventually recharges to river systems as baseflow; however, nutrient balance

calculations (Section 8.3) indicate the nitrogen uptake by blue gum vegetation exceeds nutrient

loading of effluent and that phosphorus adsorption by finer-grained soils (i.e. clayey sands and sandy

clays) will occur. Given the slow rate of groundwater movement across the site, it is unlikely that

nutrient leaching will have an impact on offsite surface water bodies.

9.3 Offsite Water Movement into Sensitive Areas Prevention Plan

A review of sensitive areas within a 10 km buffer area of the Dardanup WWTP was conducted during

the feasibility study. The closest natural water courses are the Ferguson River and Crooked Brook,

both located approximately 2.5 km north and south, respectively, of the woodlot area. The closest

PDWS (the Bunbury Water Reserve) is located approximately 10 km downgradient of the Dardanup

WWTP. Offsite movement of water and/or nutrients into sensitive areas is therefore not expected.

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9.4 Existing Surface or Buried Drainage Systems

Water balance calculations based on the maximum effluent flow rate of 219 kL/d indicate that surface

runoff is considered to be negligible (less than 1 mm) and that the depth to irrigation is less than 20%

of the field capacity. Therefore, at this time no drainage systems are recommended.

9.5 Runoff Design for both Frequent and Extreme Storm Events

Water balance calculations performed during the feasibility study indicate that runoff from effluent

irrigation is negligible and that depth to irrigation is less than 210 mm based on the maximum

forecasted flow rate of 219 kL/d in 2022. The depth to irrigation has been calculated based on water

balance modelling and expected plant water uptake demands. Water balance modelling was

performed using MEDLI software and included precipitation data from the past 20 years, which

accounts for both frequent (annual wet season) rainfall events and extreme events (ten or more years

of averaging). The annual average runoff, based on a maximum flow rate of 219 kL/d was less than

1 mm per year and it is expected that any rainfall would flow towards the west, following the

topographic contours of the site.

9.6 Proposed Stormwater Calculation/Diversion Pipework or Channels

Water balance calculations based on the maximum effluent flow rate of 219 kL/d indicate that surface

runoff is considered to be negligible (less than 1 mm) and that the depth to irrigation is less than 20%

of the field capacity. It is expected that storm water would run off into existing drainage ditches

located west of the woodlot area. Therefore, at this time no additional stormwater diversion pipework

or drainage channels are recommended.

9.7 Proposals to Manage Soil Sodicity, Compaction and Salinity Risks

Salinity is the presence of soluble salts in or on soils or in water. High levels of soluble salts in soils

may result in reduced plant productivity. If elevated levels of salt are present in irrigation water and/or

the soil profile, accumulation of salts can lead to reduced crop yield and land degradation (ANZECC

2000). The average EC of the irrigation water is 1.9 dS/m which, based on the preliminary water

salinity rating (ANZECC 2000), is a low to medium water salinity. At this time, EC values reported in

shallow soils and groundwater are within expected range of background values and no water logging

or surface water bodies were observed on site.

Sodicity is a condition that degrades soil properties by making the soil more dispersible and erodible,

restricting water entry and reducing hydraulic conductivity of the soil. These factors limit leaching so

that salt accumulates over long periods of time, resulting in saline subsoils. A soil with increased

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dispersibility may also become more susceptible to erosion by water and wind (ANZECC 2000).

Reported concentrations of sodium in the woodlots soil were <40 mg/kg and sodium adsorption ratios

(SAR) were low (between 1.6 and 14.0), indicating sodicity is not a concern at the woodlots area.

Monitoring of soils and groundwater in the woodlot area, as noted in Section 12, will be conducted by

Water Corporation and if threshold values are exceeded, management approaches for salinity,

sodicity or compaction will be implemented as required.

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10. PROTECTION OF NATURAL WATER RESOURCES

10.1 Surface Water Protection

There are currently no surface water features in the existing woodlot area and there is no specific

guidance on a buffer distance within the Department of Water’s Water Quality Protection Note 22:

Irrigation with Nutrient-Rich Wastewater (DoW 2008). Given that the nearest water courses, the

Ferguson River and Crooked Brook, are approximately 2.5 km away from the Dardanup WWTP,

direct impacts to surface water bodies as a result of effluent irrigation are not anticipated.

10.2 Groundwater Protection

There is at least a two metre vertical separation to the regional water table across the site; although

due to the duplex nature of the soils, potentially perched groundwater is seasonally present at the site

above the 0.2 to 0.5 m thick lateritized layer noted approximately 2.0 to 3.0 m below the natural

ground surface. It is important to note that no water logging or surface water expressions of

groundwater were observed in the woodlot area during the field investigation.

A groundwater monitoring network is currently installed at the site to allow for the collection of

groundwater quality samples. Concentrations of nitrite (NO2) and nitrate (NO3) were assessed against

the Australian Drinking Water Guidelines (ADWG; NHMRC 2011) to assess potential impacts to

groundwater quality. Samples analysed in August 2012 reported nitrite and nitrate values less than

their respective ADWG values of 3 and 50 mg/L (NHMRC 2011). At this time, no guideline value

exists for phosphorus in the ADWG (NHMRC 2011); although reported concentrations were generally

less than 1.4 mg/L, with the exception of a reported value of 8.2 mg/L at MW03A which is anomalous

in comparison to historical values and should be reconfirmed in subsequent sampling events.

Volume 3 of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality provides

guidelines of short-term and long-term trigger values for irrigation water quality to protect groundwater

quality. Short-term trigger values (STV) are defined as the maximum concentration of a contaminant

in irrigation water that can be tolerated for a period of 20 years, whereas Long-term trigger values

(LTV) assumes a period of 100 years. Concentrations of Total Nitrogen and Total Phosphorus in the

Dardanup effluent irrigation water, over the period of 1998 to 2012, are within their respective STVs

but exceed their respective LTVs.

Although STV and LTVs are provided as guideline, it is noted that these values are based on

vegetable and forage crops and do not include trees such as the Eucalyptus globulus which are

currently planted in the woodlots area. It is recommended that a site-specific assessment be

conducted to further evaluate nitrogen uptake, sensitivity to excess nitrogen load, irrigation load,

volatilisation/denitrification and removable nitrogen to define STVs for the woodlot area.

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A monitoring program will be implemented to ensure that the woodlot area achieves the

environmental objectives for the site, including minimisation of offsite impacts. The monitoring

program is outlined in Section 12.

10.3 Nutrient Transport

The water and nutrient balance modelling summarized in Section 8 indicates that in general inputs of

treated wastewater are in balance with the water and nutrient demand of the blue gum trees

plantation in the woodlot irrigation area. The nutrient balance modelling shows that the blue gum

plantation has a significant impact on the water balance at the site as blue gums take up a significant

volume of water on a daily basis. Additional modelling scenarios run also indicate that water losses

through infiltration and evapotranspiration are greater with a blue gum plantation than a typical

pasture crop.

In general, the risk of nutrient export offsite is considered to be low due to the ability of soils to adsorb

phosphorus and the high uptake of nitrogen by the blue gums. A DoW WIN database search was

undertaken and no recorded bores are located within a 1km search radius of the Site which would be

directly impacted by groundwater discharging from the woodlot area.

A monitoring program will be implemented to ensure that the woodlot area achieves the

environmental objectives for the site, including minimisation of offsite impacts. The proposed

monitoring program for the woodlot area is outlined in Section 12.

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11. VEGETATION MANAGEMENT

It is proposed that the existing woodlot area continue to be used for effluent irrigation for the period of

2012 to 2022. Any increase in forecasted flow rate beyond those currently proposed by Water

Corporation (Table 13), and continued irrigation past 2022 would require a re-evaluation of the

proposed irrigation area and NIMP.

At this time, no additional vegetation planting or clearing or re-establishment of existing vegetative

species is required.

11.1 Pesticide and Herbicide Storage and Use

It is anticipated that the requirement for pesticides or herbicides usage on site will be minimal due to

the expected high tree lot vitality ensuring sustainable water uptake. In instances where pesticide or

herbicide use is likely to be required there will be no use of high-risk residual compounds and use of

any such compounds will be managed by a specialist forestry contractor in accordance with

acceptable forestry practice.

In is not anticipated that any pesticides or herbicides will be permanently stored on site; however in

situations where pesticide use cannot be avoided, short term temporary storage may be required. In

these cases, a pesticide use and storage management plan will be developed to ensure proper

management techniques are implemented by the Water Corporation and/or their contractors.

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12. SITE MONITORING AND REPORTING

Site wide monitoring is required as a condition of effluent-irrigated tree lot management. At this time,

a pre-irrigation monitoring regime, to establish a set of baseline values cannot be conducted because

effluent irrigation is already occurring. However, on-going monitoring will ensure that concentrations

of inorganics within groundwater are being maintained within the environmental objectives of the site.

In instances where there is a significant departure from historical trends, management responses will

be initiated by the Water Corporation to assess the requirement of mitigation measures.

On-going monitoring of the woodlot area consists of fifteen monitoring wells (MW01-MW07, A to C

series) as shown on Figure 7. The monitoring wells already exist on site and were measured and

sampled as part of the site investigation conducted in July 2012. Table 15 outlines the sampling

requirements for the on-going site monitoring program.

Table 15 Site Monitoring Program

Well ID WL Fields1

Major Ions2 Nutrients

3 Metals

4 Frequency

5

A-Series X X X X X Bi-Annually

B-Series X X X X X Bi-Annually

C-Series X X X X Annually

Notes: 1) Fields includes: Field measured parameters of pH, temperature and electrical conductivity (EC)

2) Major Ions includes: Ca, Mg, K, Na, Cl, SO4, pH, EC, Alkalinity, Hardness

3) Nutrients includes: NOx, TN, NH4+, TKN, TP

4) Metals includes: Al, As, Ba, B, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Th, Zn

5) Recommend that bi-annual sampling be conducted in summer and winter

It is also recommended that soil sampling be conducted on an annual basis to assess soil salinity and

sodicity properties within the woodlot irrigation area.

It is expected that sampling and testing will be performed by service providers who are NATA

accredited and in accordance with NATA approved standards. Upon completion on the monitoring

events, an annual site monitoring report should be developed to summarize results of the program

and provide recommendations for future monitoring events.

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Figure 7 Monitoring Well and Soil Monitoring Locations

MW04 MW03

MW02

MW05

MW06

MW01

MW07

Legend Monitoring Well Location Woodlot Irrigation Area Wastewater Treatment Plant (WWTP)

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13. CONTINGENCY PLAN

A contingency plan will be prepared to demonstrate how offsite impacts from the woodlot area will be

minimised. Good planning is important for contingency management to avoid unacceptable offsite

impacts as a result of unforeseen events.

Contingency plans for the following three exceptional events as noted in WQPN 22 are:

• Runoff after wildfire or major storm event: Uncontrolled runoff after a wildfire or major

storm event is considered to be a low risk. The irrigation area is located on flat ground, away

from major surface drainages, natural surface water features and 100 year flood areas. It is

expected that the current and future pond sizes are adequate to account for the exceedance

of monthly irrigation rates and that irrigation schedules can be tailored accordingly during re-

planting or harvesting;

• Accidental spillage and leakage of chemicals: The storage of chemicals or pesticides at

the Dardanup WWTP is not anticipated. If such storage becomes a requirement, a Chemicals

Management Plan will be developed by the Water Corporation to ensure strict protocols are

implemented to control the use and access any chemicals. Spill kits and contingency

measures will be adopted by contractors who use plant equipment or vehicles on site; and

• Overflow or seepage from ponds used to store or treat contaminated water: Excess

capacity of the ponds is currently available and it is expected that for future forecasted rates

excess capacity will be included in the engineering design.

A summary of potential risks (major and minor) as well as mitigation measures that could be

employed to manage such potential risks has been provided in Table 16.

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Table 16 Contingency Plan Risk Ranking and Mitigation Strategies

Risk Comment Likelihood

(L, M, H)

Strategy Actions/Task

Insects defoliate trees or

trees killed, Impact < 12

months.

Risk primarily to young (<7 m tall

and <4 years) trees that have

not reached water use capacity.

Low Reduce irrigation on insect

damaged areas.

Maintain a greater pond storage without

exceeding monthly design irrigation rates.

Increase monitoring of surface ponding and

runoff and adjust irrigation rates as required.

Fire destroys plantation,

Impact 12-36 months.

Not expected to affect irrigation

system.

Low Reduce irrigation on fire damaged

areas.

Maintain a greater pond storage without

exceeding monthly design irrigation rates.

Increase monitoring of surface ponding and

runoff and adjust irrigation rates as required.

Tailor irrigation with re-planting. May need to

adjust harvesting schedule accordingly.

Soil saturation reached

or infiltration capacity is

reduced, likely to impact

in winter.

This would be evident as a

progressive decline in infiltration

capacity.

Low Currently irrigation scheme allows

for greatest irrigation during winter

months (>40% of total; Jun-Aug)

and reduced irrigation during

summer months.

Monitoring of woodlot area during groundwater

monitoring to look for areas of ponding/water

logging. If overflow or runoff is noted,

interception measures or bioremediation

strategies will be implemented (e.g. sawdust

filled trenches and collection ponds).

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Risk Comment Likelihood

(L, M, H)

Strategy Actions/Task

Accidental spillage of

fuels and/or chemicals.

Minimal chemical usage on site.

Likely only to be fuel from

vehicles and mobile plant

equipment. Pesticide usage only

when weed/pest management is

being undertaken.

Low Limit the potential for spills to occur

and quickly remediate in the event

of a spill.

No refuelling will be undertaken on the site.

Fuel spill kit will be located on a t least one

vehicle operating within the site. Use of

pesticides on site will be managed by a

specialist forestry contractor in accordance

with accepted forestry practice and no

pesticides will be stored at the site.

Infrastructure failure

(pipeline) preventing

irrigation, impact <1

month.

Use of treatment ponds should

attenuate flows; however tree

lots would be impacted with

reduced irrigation. Expected to

be low risk because all

equipment is manual.

Low Reinstatement of failed

infrastructure.

Pipeline to be inspected on a monthly basis. If

failure occurs, temporary diversion of irrigation

could potentially occur.

Extreme rainfall event

leading to inflow

exceeding irrigation

capacity.

Outflow of effluent is controlled

manually by Water Corporation

personnel. There is residual

storage in treatment ponds to

accommodate storage during

extreme rainfall.

Low-

Medium

Currently expect annual ADF to be

<20% of hydraulic capacity of

woodlot area, based on water

balance and maximum plant water

demand calculations.

Monitoring of woodlot area during groundwater

monitoring to look for areas of ponding/water

logging. If overflow or runoff is noted,

interception measures or bioremediation

strategies will be implemented (e.g. sawdust

filled trenches and collection ponds).

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14. REFERENCES

Australian and New Zealand Environment and Conservation Council (ANZECC), 2000, Australia and

New Zealand Guidelines for Fresh and Marine Water Quality, October 2010

Australia Soil Resource Information Service (ASRIS), Atlas of Australian Acid Sulfate Soils. Database

Accessed 2012

Bolland, M.D.A., Allen, D.G., and Barrow, N.J., 2003a, Sorption of Phosphorus by Soils – How it is

Measured in Western Australia. Bulletin 4591. Department of Agriculture

Bolland M.D.A., and Allen D.G., 2003b, Phosphorus sorption by sandy soils from Western Australia:

effect of previously sorbed P on P buffer capacity and single-point P sorption indices.

Australian Journal of Soil Research 41, 1369-1388. doi: 10.1071/SR02098

Bolland, M. and Russell, M., 2010, Phosphorus for high rainfall pastures, Government of Western

Australia, Department of Agriculture and Food. Bulletin 4808, ISSN 1833-7236, October 2010

Bureau of Meterology (BoM), 2012, Dardanup Climate Data, www.bom.gov.au, Website Accessed

August 2012

Burkitt LL, Moody PW, Gourley CJP, Hannah MC, 2002, A simple phosphorus buffering index for

Australian soils. Australian Journal of Soil Research 40, 497-513. doi: 10.1071/SR01050

CSIRO, 1999, Sustainable Effluent-Irrigated Plantations: An Australian Guideline

Department of Water (DoW), 2008, Water Quality Protection Note 22: Irrigation with Nutrient-Rich

Wastewater

Department of Water (DoW), 2009, Bunbury and South West Coastal Groundwater Areas Subarea

Reference Sheets: Plan Companion for the South West Groundwater Areas Allocation Plan,

May 2009

Department of Water (DoW), 2010a, Water Quality Protection Note 33: Nutrient and Irrigation

Management Plans

Department of Water (DoW), 2010b, Water Quality Information Sheet 04: Nutrient and Irrigation

Management Plan Checklist

Department of Water (DoW), 2012, Geographic Data Atlas, www.dow.gov.au, Website Database

Accessed August 2012

WATER CORPORATION





Ecosystems Research Group (ERG), 2001, Improved Management of the Albany Effluent Irrigation

Tree Farm, Botany Department of the University of Western Australia

Geological Survey of Western Australia, 1984, 1:250,000 Geological Series

GHD, 2010, Report for Albany Tree Farm – Soil Water Balance Modelling

Golder Associates Pty Ltd., 1997, Dardanup Waste Water Treatment Plant, Geotechnical

Investigation, Tree Lot 4. Unpublished Report prepared for the Water Corporation, July 1997

Government of Western Australia, 2011, Shire of Dardanup Town Planning Scheme No. 3 District

Scheme Document, Western Australia Planning Commission

Government of Western Australia, 2003, State Planning Policy 2.7: Public Drinking Water Source

Policy, State Law Publisher, Perth, WA

Knisel, W.G., (ed)., 1980, CREAMS: A field-scale model for Chemicals, Runoff and Erosion from

Agricultural Management Systems. Conservation Research Report No. 26, U.S. Department of

Agriculture, 640pp

Littleboy, M., Silburn, D.M., Freebairn, D.M., Woodruff, D.R. and Hammer, G.L.,1989, PERFECT: A

Computer Simulation Model of Productivity Erosion Runoff Functions to Evaluate Conservation

Techniques. Training Series QE93010, Department of Primary Industries, Queensland, 119p

Littleboy, M., Silburn, D.M., Freebairn, D.M., Woodruff, D.R., Hammer, G.L. and Leslie, J.K. (1992)

Impact of soil erosion on production in cropping systems. I. Development and validation of a

simulation model, Australian Journal of Soil Research, 30, 757-774. National Health and

Medical Research Council (NHMRC), 2011, National Water Quality Management Strategy,

Australian Drinking Water Guidelines, Volume I, October 2011

National Environment Protection Council (NEPC), 1999, National Environment Protection

(Assessment of Site Contamination) Measure, December 1999

Ritchie, J.T., 1972, A model for predicting evaporation from a row crop with incomplete cover, Water

Resources Research, 8, 1204-1213

Sharpley, A.N. and Williams, J.R. (Eds)., 1990, EPIC: Erosion/Productivity Impact Calculator: I. Model

Documentation. United States Department of Agriculture Technical Bulletin No. 1768, 235 pp

Todd K.T., 1959, Ground Water Hydrology. John Wiley & Sons, New York.

U.S. Dept. of Agriculture. Soil Conservation Service. 1972. National engineering handbook, Section 4,

hydrology. Chapters 7, 8, 9, and 10. U.S. Govt. Print. Off. Washington, DC.

WATER CORPORATION





Williams, J.R. and LaSeur, W.V., 1976, Water yield model using SCS curve numbers, Journal of

Hydraulics Division, American Society of Civil Engineers. 102, pp. 1241-1253

WorleyParsons, 2012. Dardanup Woodlots Site Investigation and Water Balance Modelling. 301012-

01582.

WATER CORPORATION




Appendix 1: 301012-01582-EN-REP: Rev 0: 19-Oct-2012

Appendix 1 Soil and Groundwater Monitoring Results of Woodlot Investigation

Location Depth Date

pH

SA

R

EC

TS

S

Bu

lk D

en

sit

y

Mo

istu

re C

on

ten

t

Su

lfate

(S

O42-)

Ch

lori

de

Calc

ium

Mag

nesiu

m

So

diu

m

Po

tassiu

m

Am

mo

nia

as N

Nit

rite

as N

Nit

rate

as N

Nit

rite

+ N

itra

te a

s N

TK

N a

s N

To

tal

N a

s N

To

tal

Ph

osp

ho

rus a

s P

TO

C

TC

TIC

--- --- uS/cm mg/kg kg/m3 % mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg % % %

Guideline Value --- 5 to 10 1

950 2 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---

Dardanup

BH01 2.50 25-Jul-12 6.2 4 21 69 1680 11 <10 <10 <10 <10 20 <10 <10 <0.1 1.6 1.6 70 70 40 0.25 0.27 0.02

3.50 25-Jul-12 6.2 11 29 95 1870 14 <10 20 <10 <10 20 <10 <20 <0.1 1.6 <0.1 40 40 28 0.13 0.17 0.04

3.90 25-Jul-12 5.6 14 48 155 1740 16 <10 60 <10 <10 40 <10 <20 <0.1 <0.1 <0.1 30 30 30 0.07 0.10 0.03

BH02 2.80 26-Jul-12 --- --- 14 --- 1910 7 <10 <10 <10 <10 <10 <10 <0.1 <20 <0.1 1.0 50 50 15 --- --- ---

2.90 26-Jul-12 6.1 2 13 42 1910 --- --- --- --- --- --- --- --- --- --- --- --- --- --- 0.24 0.26 0.02

3.10 26-Jul-12 5.8 --- 21 --- 1800 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---

4.50 26-Jul-12 5.5 3 24 77 1650 21 30 10 <10 <10 <10 <10 <20 <0.1 3.0 3.0 40 40 25 0.07 0.07 <0.02

BH03 1.10 25-Jul-12 5.2 2 28 90 1780 12 <10 10 <10 <10 <10 <10 <20 <0.1 3.1 3.1 60 60 40 0.18 0.21 0.03

2.90 25-Jul-12 5.7 10 42 138 1800 16 10 40 <10 <10 30 <10 <20 <0.1 <0.1 <0.1 360 360 48 0.99 1.25 0.26

3.80 25-Jul-12 5.5 9 36 118 1760 20 20 40 <10 <10 30 <10 <20 <0.1 <0.1 <0.1 230 230 39 0.44 0.57 0.13

Notes: Bold indicates value is above applied guideline value.1

ANZECC and ARMCANZ (2000) Irrigation Guideline value for soil structure stability in relation to irrigation water.2

ANZECC and ARMCANZ (2000) Irrigation Guideline value for average root zone salinity for sensitive crops.3

National Environmental Protection Measure (Assessment of Site Contamination), NEPC 1999.

--- no value applied or not analysed

mbgl metres below ground level

Table 1 Soil Results - Routine and Nutrient Parameters

Routine Nutrients Carbon

Location Depth DateP

ho

sp

hate

Rete

nti

on

Ind

ex (

PR

I)

Ph

osp

hate

Bu

fferi

ng

In

dex

(PB

I)

Ars

en

ic

Cad

miu

m

Ch

rom

ium

Co

op

er

Lead

Nic

kel

Zin

c

Merc

ury

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Guideline Value 20 3

3 3

400 3

100 3

600 3

60 3

200 3

1 3

Dardanup

BH01 2.50 25-Jul-12 5 8 <5 <1 14 <5 5 2 <5 <0.1

3.50 25-Jul-12 25 29 <5 <1 6 <5 <5 <2 <5 <0.1

3.90 25-Jul-12 552 484 --- --- --- --- --- --- --- ---

BH02 2.80 26-Jul-12 12 18 <5 <1 5 <5 8 <2 <5 ---

2.90 26-Jul-12 26 13 --- --- --- --- --- --- --- ---

3.10 26-Jul-12 378 681 --- --- --- --- --- --- --- ---

4.50 26-Jul-12 698 676 <5 <1 8 <5 6 <2 <5 <0.1

BH03 1.10 25-Jul-12 6 4 <5 <1 <2 <5 <5 <2 <5 <0.1

2.90 25-Jul-12 13 6 --- --- --- --- --- --- --- ---3.80 25-Jul-12 686 681 <5 <1 10 <5 7 2 <5 0.1

Notes: Bold indicates value is above applied guideline value.1

ANZECC and ARMCANZ (2000) Irrigation Guideline value for soil structure stability in relation to irrigation water.2

ANZECC and ARMCANZ (2000) Irrigation Guideline value for average root zone salinity for sensitive crops.3

National Environmental Protection Measure (Assessment of Site Contamination), NEPC 1999.

--- no value applied or not analysed

mbgl metres below ground level

Table 2 Soil Results - Metals

MetalsPhosphorus Indices

Location Date pH

SA

R

EC

TD

S

To

tal

An

ion

s

To

tal

Ca

tio

ns

Ion

ic B

ala

nc

e

To

tal

Ha

rdn

es

s a

s C

aC

O3

Hy

dro

xid

e A

lka

lin

ity

as

Ca

CO

3

Ca

rbo

na

te A

lka

lin

ity

as

Ca

CO

3

Bic

arb

on

ate

Alk

ali

nit

y a

s

Ca

CO

3

To

tal

Alk

ali

nit

y a

s C

aC

O3

Su

lfa

te a

s S

O4

Ch

lori

de

Ca

lciu

m

Ma

gn

es

ium

So

diu

m

Po

tas

siu

m

Flu

ori

de

Am

mo

nia

as

N

Nit

rite

as

N

Nit

rate

as

N

Nit

rite

+ N

itra

te a

s N

TK

N a

s N

To

tal

Nit

rog

en

as

N

To

tal

Ph

os

ph

oru

s a

s P

Re

ac

tiv

e P

ho

sp

ho

rus

as

P

To

tal

Org

an

ic C

arb

on

To

tal

Ino

rga

nic

Ca

rbo

n

To

tal

Ca

rbo

n

--- --- uS/cm mg/kg meq/L meq/L % mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L % % %

NHMRC DWQG AO 6.5-8.5 --- --- 600 --- --- --- 200 --- --- --- --- 250 250 --- --- 180 --- --- 1 --- --- --- --- --- --- --- --- --- ---

NHMRC DWQG Health --- --- --- --- --- --- --- --- --- --- --- --- 500 --- --- --- --- --- 1.5 --- 3 50 --- --- --- --- --- --- --- ---

Dardanup Woodlots

MW01A 6-Aug-12 6.4 0.90 174 113 1.58 1.70 --- 52 <1 <1 8 8 12 22 11 6 15 <1 <0.1 0.04 <0.01 7.75 7.75 0.90 8.60 0.26 0.02 5 8 12

MW1B 6-Aug-12 5.9 3.84 176 114 1.58 1.60 --- 12 <1 <1 3 3 17 34 <1 3 31 <1 <0.1 0.04 <0.01 2.94 2.94 <0.5 2.90 0.11 <0.01 <1 10 10

MW02A 6-Aug-12 4.4 1.19 181 118 1.43 1.38 --- 34 <1 <1 <1 <1 21 52 2 7 36 <1 0.3 <0.01 <0.01 6.61 6.61 1.60 8.20 0.20 0.18 27 5 31

MW02B 6-Aug-12 5.9 2.69 242 157 2.17 2.24 --- 34 <1 <1 6 6 21 52 2 7 36 <1 <0.1 <0.01 <0.01 2.08 2.08 0.90 3.00 0.46 <0.01 4 16 20

MW03A 6-Aug-12 6.4 1.14 220 143 2.14 2.26 --- 64 <1 <1 21 21 17 29 14 7 21 3 <0.1 <0.02 <0.01 7.64 7.64 3.70 11.30 8.21 0.10 3 14 17

MW03B 6-Aug-12 6.1 2.62 200 130 1.84 1.88 --- 26 <1 <1 7 7 13 49 4 4 31 <1 <0.1 0.02 <0.01 0.75 0.75 0.10 0.80 0.02 <0.01 2 12 14

MW04A 6-Aug-12 6.5 1.06 181 118 1.77 1.74 --- 48 <1 <1 21 21 18 21 16 2 17 1 <0.1 0.04 <0.01 5.35 5.35 1.10 6.40 1.40 0.04 3 8 10

MW04B 6-Aug-12 6.3 2.22 197 128 1.77 1.76 --- 28 <1 <1 14 14 11 43 3 5 27 1 <0.1 0.06 <0.01 0.64 0.64 <0.1 0.60 0.01 <0.01 <1 22 21

MW05A 6-Aug-12 7.6 4.40 580 377 5.32 5.08 2.34 67 <1 <1 49 49 27 127 17 6 83 5 <0.1 0.07 0.03 2.82 2.85 1.80 4.60 0.72 <0.01 2 14 16

MW05A (Dup ) 6-Aug-12 7.4 4.28 565 367 5.33 5.16 1.61 71 <1 <1 49 49 26 128 17 7 83 5 <0.1 0.07 0.03 2.76 2.79 2.30 5.10 0.98 <0.01 2 13 14

MW06A 6-Aug-12 7.1 1.91 386 251 3.50 3.58 1.10 83 <1 <1 35 35 34 50 20 8 40 7 <0.1 <0.05 0.08 9.47 9.55 5.10 14.60 1.19 <0.01 <10 12 12

MW07A 6-Aug-12 6.7 7.28 802 521 7.50 7.05 3.09 61 <1 <1 63 63 105 141 13 7 131 5 <0.1 <0.05 0.08 1.04 1.12 7.60 8.70 1.08 <0.01 15 26 42

MW07C 6-Aug-12 6.0 4.00 251 163 2.04 2.17 --- 19 <1 <1 4 4 8 63 1 4 40 2 <0.1 0.05 <0.01 0.23 0.23 <0.1 0.20 <0.01 <0.01 <1 11 10

Notes:

Value above Australia Drinking Water Guideline - Health Objective (NHMRC 2011)

Value above Australia Drinking Water Guideline - Aesthetic Objective (NHMRC 2011)

Table 3 Groundwater Results - Routine and Nutrient Parameters

Nitrogen Phosphorus CarbonRoutine

Location Date

Alu

min

ium

An

tim

on

y

Ars

en

ic

Bari

um

Bery

lliu

m

Bo

ron

Cad

miu

m

Calc

ium

Ch

rom

ium

Co

balt

Co

pp

er

Iro

n

Lead

Mag

nesiu

m

Man

gan

ese

Mo

lyb

den

um

Nic

kel

Ph

osp

ho

rus

Po

tassiu

m

Sele

niu

m

Sil

ver

So

diu

m

Str

on

tiu

m

Th

all

ium

Tin

Tit

an

ium

Van

ad

ium

Zin

c

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

NHMRC DWQG AO 0.20 --- --- --- --- --- --- --- --- --- 1 0.3 --- --- 0.1 --- --- --- --- --- --- --- --- --- --- --- --- 3.00

NHMRC DWQG Health --- 0.003 0.01 2 0.06 4 0.002 --- 0.05 --- 2 --- 0.01 --- 0.5 0.05 0.02 --- --- 0.01 0.1 --- --- --- --- --- --- ---

Dardanup Woodlots

MW01A 6-Aug-12 0.35 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 10 <0.01 <0.01 <0.01 0.06 <0.01 5 <0.01 <0.01 <0.01 <1 1 <0.01 <0.01 12 <0.1 <0.01 <0.01 0.02 <0.01 0.01

MW1B 6-Aug-12 <0.1 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 <1 <0.01 <0.01 <0.01 0.41 <0.01 2 <0.01 <0.01 <0.01 <1 <1 <0.01 <0.01 28 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW02A 6-Aug-12 1.54 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 11 <0.01 <0.01 <0.01 0.09 <0.01 1 0.03 <0.01 <0.01 <1 6 <0.01 <0.01 20 0.10 <0.01 <0.01 <0.01 <0.01 0.03

MW02B 6-Aug-12 0.11 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 <1 <0.01 <0.01 <0.01 0.41 <0.01 5 <0.01 <0.01 <0.01 <1 <1 <0.01 <0.01 34 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW03A 6-Aug-12 0.49 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 12 <0.01 <0.01 <0.01 0.06 <0.01 6 <0.01 <0.01 <0.01 <1 2 <0.01 <0.01 18 <0.1 <0.01 <0.01 0.02 <0.01 0.01

MW03B 6-Aug-12 0.22 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 3 <0.01 <0.01 <0.01 <0.05 <0.01 3 <0.01 <0.01 <0.01 <1 <1 <0.01 <0.01 28 <0.1 <0.01 <0.01 0.01 <0.01 0.01

MW04A 6-Aug-12 0.11 0.01 <0.01 <0.1 <0.01 <0.1 <0.005 13 <0.01 <0.01 <0.01 0.07 <0.01 2 0.02 <0.01 <0.01 <1 <1 <0.01 <0.01 14 0.10 <0.01 <0.01 <0.01 <0.01 0.01

MW04B 6-Aug-12 <0.1 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 3 <0.01 <0.01 <0.01 <0.05 <0.01 4 <0.01 <0.01 <0.01 <1 1 0.01 <0.01 24 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW05A 6-Aug-12 0.18 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 15 <0.01 <0.01 <0.01 <0.05 <0.01 5 0.01 <0.01 <0.01 <1 5 <0.01 <0.01 75 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW05A (Dup) 6-Aug-12 0.15 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 15 <0.01 <0.01 <0.01 <0.05 <0.01 5 <0.01 <0.01 <0.01 <1 5 <0.01 <0.01 76 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW06A 6-Aug-12 <0.1 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 17 <0.01 <0.01 <0.01 <0.05 <0.01 7 0.04 <0.01 <0.01 <1 6 <0.01 <0.01 37 <0.1 <0.01 <0.01 <0.01 <0.01 0.01

MW07A 6-Aug-12 0.18 0.01 <0.01 <0.1 <0.01 <0.1 <0.005 12 <0.01 <0.01 <0.01 0.33 <0.01 6 0.17 <0.01 <0.01 <1 4 <0.01 <0.01 120 <0.1 <0.01 <0.01 <0.01 <0.01 0.02

MW07C 6-Aug-12 <0.1 <0.01 <0.01 <0.1 <0.01 <0.1 <0.005 1 <0.01 <0.01 <0.01 <0.05 <0.01 4 <0.01 <0.01 <0.01 <1 1 <0.01 <0.01 36 <0.1 <0.01 <0.01 <0.01 <0.01 0.05

Notes:

Value above Australia Drinking Water Guideline - Health Objective (NHMRC 2011)

Value above Australia Drinking Water Guideline - Aesthetic Objective (NHMRC 2011)

Table 4 Groundwater Results - Metals and Trace Elements

Metals and Trace Elements

WATER CORPORATION





Appendix 2 RAW Modelling Data

WATER CORPORATION





Modelling Approach

In MEDLI, soil water movement was simulated as a one-dimensional (vertical) water balance,

averaged over the 22 ha woodlot area. The water balance component is taken from PERFECT

(Littleboy et al. 1989; 1992) which is based on the Williams and LaSeur (1976) and Ritchie (1972)

water balance models as used in CREAMS (Knisel 1980) and similar models. The soil profile used for

the woodlot area consisted of four layers of variable thicknesses, with each layer assigned a lower

storage limit, upper storage limit, total porosity, bulk density and saturated hydraulic conductivity,

based on field data and empirically defined values. The top layer (i.e. the top soil), up to 100 mm was

also assigned an air dry component. During the model runs, the soil water of each soil layer is

updated on a daily basis by computing rainfall, irrigation ADF values, runoff, soil evaporation,

transpiration and drainage.

Irrigation is assumed to infiltrate the soil surface with little to no runoff. Runoff from rainfall is predicted

using the Curve Number technique (USDA-SCS, 1972) and is calculated as a function of daily rainfall,

soil water deficit, plant total cover and a modified curve number taking into account the percentage of

green cover in the woodlot area, for average antecedent moisture conditions.

Soil evaporation is based on a two stage evaporation algorithm by Ritchie (1972) as modified in

PERFECT (Littleboy et al. 1989). Stage 1 drying equals the potential evaporation rate (i.e. demand

limited) and continues until the cumulative amount evaporated exceeds a defined limit. Stage II drying

is a soil supply rate limited process, with the rate of evaporation proportional to the square root of

time. Both parameters are related to the soil texture classification for each layer. Evaporation will

remove soil water from the two upper profile layers until the top layer reaches its air dry moisture

content and the second layer reaches its lower storage limit.

Plant transpiration is determined from soil water content, plant canopy cover and Class A pan

evaporation. The potential transpiration demand is estimated as the product of canopy cover, daily

pan evaporation and user-defined maximum crop coefficient. The plant will transpire this amount

unless limited by its ability to extract water from the soil profile (i.e. potential extraction rate).

Transpiration is partitioned across the different soil layers within the root zone such that the pattern of

extraction favours the wetter layers, and only involves those layers with available soil water.

When a soil profile layer is above its defined Upper Storage Limit (i.e. its field capacity) following an

infiltration event, it is assumed that drainage occurs from this layer. The drainage algorithm from EPIC

(Sharply and Williams 1990) is used to predict the proportion of the drainable water (in excess of the

Upper Storage Limit) that will drain on a particular day. The most important parameters are drainable

porosity and saturated hydraulic conductivity. Under profile saturated conditions, drainage can also

occur by saturated flow. The amount that can be infiltrated in one day is equivalent to half the

saturated hydraulic conductivity. When a saturated profile cannot repartition all the predicted

infiltration into saturated drainage, the excess is routed as runoff.

0. 1.2E+3 2.4E+3 3.6E+3 4.8E+3 6.0E+30.01

0.1

1.

Time (sec)

Norm

aliz

ed H

ead (

m/m

)

MW06A BAIL-DOWN TEST

Data Set: I:\...\MW05A.aqtDate: 11/02/12 Time: 10:16:04

PROJECT INFORMATION

Company: WorleyParsonsClient: Water CorporationProject: 301012-01582Location: DardanupTest Well: MW06ATest Date: 01/08/2012

AQUIFER DATA

Saturated Thickness: 10. m Anisotropy Ratio (Kz/Kr): 1.

WELL DATA (New Well)

Initial Displacement: 0.692 m Static Water Column Height: 10. mTotal Well Penetration Depth: 4. m Screen Length: 3. mCasing Radius: 0.026 m Well Radius: 0.026 m

SOLUTION

Aquifer Model: Unconfined Solution Method: Bouwer-Rice

K = 1.65E-7 m/sec y0 = 0.7347 m

0. 1.6E+3 3.2E+3 4.8E+3 6.4E+3 8.0E+30.01

0.1

1.

Time (sec)

Norm

aliz

ed H

ead (

m/m

)



PROJECT INFORMATION


AQUIFER DATA




SOLUTION

Aquifer Model: Confined Solution Method: Bouwer-Rice

K = 1.098E-7 m/sec y0 = 0.5498 m

0. 4.0E+3 8.0E+3 1.2E+4 1.6E+4 2.0E+40.1

1.

Time (sec)

Norm

aliz

ed H

ead (

m/m

)



PROJECT INFORMATION


AQUIFER DATA




SOLUTION

Aquifer Model: Confined Solution Method: Bouwer-Rice

K = 2.681E-7 m/sec y0 = 1.205 m

attachment 2 - 2a and 2b premises maps...dardanup wwtp treatment / design capacity (ref appl section...

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