Introduction - Major Projects

Ropes Creek Riparian Corridor Assessment Aecom

July 2015

Page 1 of 11

Re: Ropes Creek Riparian Corridor Assessment

Introduction

SESL Australia has been engaged by Aecom (the Client) to undertake a soil resource assessment and survey

along Ropes Creek and the realigned tributary at Horsley Park (the Site).

The objective of this assessment is to characterise the physical and chemical properties of the surrounding soil

profiles and of the alluvial deposits associated with the creek line for the purpose of restoration of existing remnant

riparian vegetation and realignment of a tributary.

The natural soil landscape is a combination of “South Creek” and “Luddenham” (Hazelton and Bannerman, 1990).

This Luddenham soil landscape comprises of dark brown silty loam podsolics soils formed on Wianamatta Shales

often associated with Minchinbury Sandstone. South Creek soils are a sandy loam and derive from a floodplain of

drainage networks of the Cumberland Plain. Typically they have a deep profile that overlay bedrock or relic soils.

Both soil types are prone to waterlogging, flood hazards, permanently high water tables, erosion from water and

surface movement. Luddenham soils are highly erodible and have hardsetting surfaces

A full investigation was carried out to investigate the two drainage lines (Drainage Line 1 and Drainage Line 2) of

Ropes Creek. Drainage Line 1 is a 2nd order watercourse that requires restoration of existing

riparian vegetation. This report provides advice on the restoration of the 20m vegetated riparian zones along both

sides of the watercourse. Drainage Line 2 is not defined as a watercourse therefore can be realigned or relocated.

This report covers how to achieve this including stripping plans, reconstruction of soil profiles and compatible

Cumberland Plain vegetation types will be approved from a client species list.

Our Ref: B35587 C5852 Q4632.docx

31st July, 2015

Aecom

420 George Street

Sydney, NSW 2000

Attention: Mark Blanche

Dear Mark,


July 2015

Page 2 of 11

Methodology

The field assessment was carried out by Chantal Milner and Andrew Lynam of SESL on Friday 12th June 2015.

Based on a desktop review and in-situ surveying, SESL Australia designated nine (9) borehole locations for

sampling. Exact locations were defined after a site walkover and establishing the variations in the soil and

vegetative growth. Samples were collected by hand auger using the Free Survey technique, focusing on identifying

the main soil catenas and variability across the site – particularly with regard to slope position vs. topsoil depth and

vegetation diversity. Profile descriptions were made of the entire profile at each sampling location (Appendix B). A

map of the sampling locations is attached as Appendix A. A soil survey at this scale cannot provide detailed soil

mapping but only identify the main occurrences and variability. Three profiles were placed in the location of the

tributary creek realignment to investigate conditions at depth once the realignment is made.

The collected samples were analysed for a range of soil chemistry properties. Topsoils were tested for pH, EC,

exchangeable cations and plant available nutrients. Subsoils were tested for pH, EC and exchangeable cations. As

the site is to be revegetated with CPW, available phosphorus levels were also determined. This allows us to

determine whether phosphorus will be limiting to the success of the planting, as many CPW species are highly

phosphorus sensitive. As plants generally take their nutrients from the top 200 mm of soil, it is not necessary to test

for plant available nutrients in subsoils.

The pH, EC, exchangeable cations and plant available nutrients were all analysed utilising the Mehlich 3 extract.

Mehlich 3 (M3) estimates plant availability of most macro- and micronutrients on soils acid to neutral pH using a

dilute acid-fluoride-EDTA solution of pH 2.5. The method has shown to be well correlated to crop response to

fertilizer phosphorus and applicable for the determination of extractable potassium, calcium, magnesium, sodium

and micronutrients, such as manganese, iron, copper and zinc (Mehlich, 1984).

This report presents the findings from the field assessment, laboratory analysis, and provides recommendations to

ameliorate the soil for re-use.

Field & Laboratory Results

Topsoil Physical and Chemical Properties

The chemical test results are presented in Appendix C. Table 1 summarises the topsoil chemical test results for

Ropes Creek Drainage Line 1 (restoration of existing riparian vegetation), Table 2 summarises the topsoil

chemistry for Drainage Line 2 (creek realignment), Table 3 looks at the subsoil (Horizon A and B) for both Drainage

Lines 1 and 2.

The soils in each horizon remain generally consistent with only some variation. The overall trend seen in each

horizon is summarised as follows however a more in-depth interpretation is discussed after each table:


July 2015

Page 3 of 11

• Topsoil in Drainage Line 1: Dark brown silty loam to silty clay loam. Slight to strong acidity with desirably

low salinity. Highly magnesic and acidic aside from BH6, which is highly magnesic and sodic.

• Topsoil in Drainage Line 2: Dark brown silty loam to silty clay loam. Moderate acidity with desirably low

salinity. Highly acidic and sodic.

• Subsoil (B Horizon) for both drainage lines – Orange brown to dark yellow with some red and black

mottling silty clay. BH5 sandy clay. BH1 and BH3 are moderately to highly acidic and moderately to highly

saline. BH4, 6, 7, 8, 9 are slightly acidic with low salinity and BH5 is slightly alkaline and highly saline. All

subsoils are magnesic and sodic and BH1, 3, 6, 7, 8 and 9 are also acidic.

• Subgrade (C Horizon) for Drainage Line 2: The C horizon becomes more crumbly and less clayey. The soil

type is a light clay and a paler orange colour. Highly magnesic and highly sodic.

Table 1. Chemical analysis results of Ropes Creek Drainage Line 1 topsoil.

Sample Number

1 3 12 13 14 16

Sample Name BH1 0-340mm

BH2 0-300mm

BH6 0-250mm

BH7 0-200mm

BH8 0-300mm

BH9 0-270mm

pH in H2O 5.8 5.3 7.1 6.4 6.2 6

pH in CaCl2 5.04 4.76 6.24 5.69 5.47 5.2

EC dSm 0.04 0.04 0.12 0.15 0.04 0.04

Na mg/kg 20.4 64.2 330 275 123 85.9

Cl mg/kg 18.14 21.45 78.4 101.76 31.68 21.03

Na % CEC 0.9 3.6 10.9 6.6 2.3 2.2

K % CEC 2.9 0.6 1.8 2.9 0.9 1.4

Ca % CEC 30 16.6 35.6 35.7 41.7 32.3

Mg % CEC 22.8 26.8 52 54.7 27.3 28.7

H % CEC 43.1 51.7 0 0 27.8 35.2

Al % CEC 0 0.1 0 0 0 0

eCEC meq/100g

9.7 7.7 13.1 18.2 22.9 16.5

NO3 mg/kg 3.8 1.6 3.9 2.7 2.2 1.6

PO4 mg/kg 3.4 1.3 4.8 7.5 4.2 6.3

K mg/kg 108 21.2 91.4 205 80.8 89.6

SO4 mg/kg 14 11 11 14 6.5 10

Ca mg/kg 584 257 933 1301 1911 1069

Mg mg/kg 268 251 827 1211 759 574

Fe mg/kg 121.7 90.5 133.8 169.1 130.1 148.1

Mn mg/kg 71 205 93 148 161 130


July 2015

Page 4 of 11

Cu mg/kg 1.3 0.64 2.6 2.4 1.8 1.9

B mg/kg 0.1 0.1 0.4 0.1 0.1 0.1

Zn mg/kg 1.3 0.65 3.1 4.7 1.7 1.2

Drainage Line 1 Topsoil (Restoration of existing vegetation)

Samples were taken at varying distances from the creek line ranging from 10-100mm to determine how much the

chemistry altered with the presence of water. Samples taken less than 50m from the creek line are acidic and

magnesic however the same result was seen in samples taken at a much further distance of 100m from the creek

line. In conclusion closeness to the water makes little difference to the chemistry. The difference in chemistry

occurs with depth and the soil becomes more hostile with increasing depth.

The laboratory analysis indicates that the chemistry of the samples along Drainage Line 1 are fairly consistent.

They are all a dark brown silty loam to silty clay loam that are slightly to strongly acidic with desirably low salinity.

The majority of the samples are highly magnesic and acidic which have the potential for hardsettting soils. Overall

the nutrient levels are low aside from magnesium and manganese. Iron/Manganese concretions (“shotgun pellets”)

are common at the A/B boundary indicating intense wetting and drying cycles typical of the Eastern Australian

climate. This is a result not only of extreme variations in rainfall but poor internal drainage of the soils. The

exception to this chemistry is BH6 and BH7, which are highly magnesic and sodic. BH6 is also very slightly

alkaline.

Table 2. Drainage Line 2, topsoil chemistry.

Sample Number 4 7 10

Sample Name BH3 0-250mm BH4 0-330mm BH5 0-350mm

pH in H2O 5.7 5.8 6.7

pH in CaCl2 4.93 4.93 5.86

EC dSm 0.04 0.03 0.22

Na mg/kg 132 103 820

Cl mg/kg 27.05 18.96 218.54

Na % CEC 5 4.3 29

K % CEC 1.6 0.9 1.1

Ca % CEC 19 25.3 13.9

Mg % CEC 32.2 24.6 55.7

H % CEC 42.3 45 0

Al % CEC 0 0 0

eCEC meq/100g 11.5 10.4 12.3

NO3 mg/kg 2 1.6 6.7


July 2015

Page 5 of 11

PO4 mg/kg 0.9 2.1 1.5

K mg/kg 69.2 34.1 49

SO4 mg/kg 7.6 10 15

Ca mg/kg 439 527 343

Mg mg/kg 450 311 832

Fe mg/kg 142.9 118 167.5

Mn mg/kg 201 184 203

Cu mg/kg 0.8 0.6 1.8

B mg/kg 0.1 0.1 0.1

Zn mg/kg 0.65 0.65 0.8

Drainage Line 2 Topsoil (Proposed tributary)

Samples, BH3, BH4 and BH5 were taken at various locations along the proposed tributary (Drainage Line 2). BH3

and BH4 were taken towards the central side of the site whereas BH5 was taken at the eastern side. Chemically

BH3 and BH4 are similar as they both have moderate acidity and desirably low salinity. Their cation exchange is

highly acidic, highly magnesic and sodic which have dispersive and hardsetting characteristics. BH5 is located in

the lowest part of the creek profile and has very slight acidity and moderate salinity. The cation exchange is highly

magnesic and sodic. Nutrient levels overall are low for all bore holes aside from magnesium and manganese which

are high.

Magnesic and highly sodic soils are not ideal for creek lines as they are very dispersive and prone to erosion.

Applications of gypsum are required to help correct this chemistry.

Table 3. Subsoil (B Horizon and C Horizon) chemistry for Drainage Line 1 and Drainage Line 2.

Description Drainage Line 1 B Horizon

Drainage Line 2 B Horizon

Drainage Line 2 C Horizon

Sample Number

2 15 17 5 8 11 6 9

Sample Name

BH1 340-

700mm

BH6, 7, 8 Composite

BH9 270mm+

BH3 250-

930mm

BH4 330-

660mm

BH5 350-

600mm+

BH3 930-1100mm

BH4 660-

1120mm pH in H2O 4.8 6.2 6.2 5.7 6.3 8 5.6 6.3

pH in CaCl2 4.21 5.17 5.04 5.1 5.32 6.46 5.07 5.9

EC dSm 0.52 0.14 0.05 0.5 0.07 0.89 0.87 0.58

Na mg/kg 498 351 229 1306 343 2315 1440 1299

Na % CEC 10.2 6.5 4.5 26.3 8.2 54.1 34 38.4

K % CEC 0.6 0.7 0.8 0.7 0.8 0.5 0.7 0.7

Ca % CEC 2.7 27 18.6 1.8 15 8.7 1 3.1

Mg % CEC 28.2 35.8 44.7 50.4 48.5 36.4 42.9 57.8

H % CEC 47.9 29.9 31.3 20.8 27.4 0 21 0


July 2015

Page 6 of 11

Al % CEC 10.3 0 0 0 0 0 0 0

eCEC meq/100g

21.1 23.6 22.1 21.6 18.2 18.6 18.4 14.7

K mg/kg 51.8 61.9 69.8 62.7 56.8 37.5 48.1 37.3

Ca mg/kg 117 1276 824 77 546 322 39 90

Mg mg/kg 724 1028 1201 1324 1072 823 959 1033

Texture Silty Clay Silty Clay Silty Clay Silty Clay Medium Clay

Sandy Clay

Light Clay

Light Clay Structure Crumb Crumb Crumb Crumb Crumb Crumb Crumb Crumb

Permeability Slow Slow Slow Slow Slow Slow Slow Slow

Pedal Strength

Moderate Moderate Moderate Moderate Moderate Weak Moderate Weak

Clay content

40 - 50% 40 - 50% 40 - 50% 40 - 50% 40 - 55% 35 - 45% 35 - 40% 35 - 40%

B Horizon Subsoil for Drainage Line 1 and 2

Subsoils in general are heavier in texture than the topsoil and contain a higher percentage of clay.

The subsoils along Drainage Line 1 vary depending on the depth to which the sample was taken. BH1 was taken at

a deeper depth between 340mm – 700mm and is highly acidic, moderately sodic and moderately magnesic. The

strong acidity of the soil has caused aluminium to become available which is toxic to plants. BH6-9 are taken to a

maximum depth of 450mm whereby the soil is not as acidic and hostile although are still highly magnesic, sodic

and magnesic. The subsoils overall have a similar physical appearance and structure. They vary from an orange

brown to dark yellow with some mottling. The soil type is a silty clay with a moderate crumb structure and slow

permeability.

The subsoils along Drainage Line 2 vary considerably in their pH and salinity levels therefore will be described

separately:

BH3 is located midway along the proposed creek line and is at the greatest depth taken at a depth of 250-930mm.

The soil type is a silty clay with a moderate crumb structure and slow permeability. The soil has moderate acidity

and is moderately saline. The cation exchange is highly acidic, highly magnesic and highly sodic.

BH4 is located to the east of the tree, which will remain on the proposed creek line and is taken at a depth of 330-

660mm. The soil type is a medium clay with a moderate crumb structure and slow permeability. The soil has slight

acidity and has desirably low salinity. The cation exchange is highly acidic, highly magnesic and moderately sodic.

BH5 is located in the lowest part of the creek profile, which overlaps the road and was sampled at a depth of 350-

600mm. The soil type belongs to the South Creek landscape and is a sandy clay with a weak crumb structure and


July 2015

Page 7 of 11

slow permeability. The soil has slight alkalinity and is very highly saline. The cation exchange is highly magnesic

and very highly sodic.

C Horizon Subsoil

The soil in the C Horizon becomes more crumbly and changes to a light clay which a moderate crumb structure

and slow permeability. The colour is a darker orange brown with some red mottling. The chemistry is similar at BH3

and BH4 whereby it's slightly to moderately acidic and highly saline. The cation exchange is highly acidic and

highly sodic.

Discussion

In general the topsoils have a slight to strong acidity however have low salinity. They are also variously magnesic

and BH 5 and 6 are sodic. Sodicity in a soils causes the soil to be come highly dispersive in particular at these

levels. Magnesic soils tend to be quite hardsetting particularly on the surface which can cause erosion. The soils

become more saline and hostile with depth by which the dispersive and hardsetting characteristics increase. All

subsoils are magnesic and some are variously sodic.

While these soil landscapes represent some of the better soils of the Cumberland Plain they are fragile and very

easily degraded due to the highly sodic, magnesic and acidic nature of the subsoils.

There are several issues that need to be addressed to prevent detrimental soil issues -

! Hostile sodic and magnesic subsoil - Correct stripping depths so that hostile sodic and magnesic subsoil is

not included in the final recovered topsoil inventory. Acidic, sodic/magnesic subsoil is extremely hostile to

plant growth and we have seen many projects give very poor outcomes and massive losses of plantings

when this material makes its way to the surface.

! Extreme salinity at depth - The salinity and sodicity issues within the B and C horizons and in the

underlying shale makes it important not to allow these to occur at the surface.

! Restablishment of proper A/B/C profiles in in the realigned tributary banks is critical to the establishment of

Cumberland Plain and riparian areas.

! Highly magnesic soils can be hardsetting and dispersive. This can be remedied by using the Ca:Mg ratio

as a guide to boosting the calcium levels. At present calcium is potentially deficient to low and the ratio

ranges between 0.0 to 1.5 whereas the target range to establish new vegetation should be 2.0-3.0.

Gypsum amendments will correct this imbalance.

! High manganese levels. Manganese levels average at 160mg/kg. High manganese levels are indicative of

waterlogging, which is further supported by the mottling which is apparent in most profiles. Provided

profiles are rebuilt properly Cumberland Plan Woodland is tolerant of this.


July 2015

Page 8 of 11

! Very acidic pH. As vegetation develops it acidifies its soil by depleting it of calcium. To counteract the soils

becoming even more severely acidic we recommend small lime additions to allow vegetation to develop

properly.

There is a valuable natural soil resource on this site that, if properly managed, conserved, and reused properly is

suitable for the restoration and creek realignment.

The main limitations for the development will be the dispersive tendencies of the soils alongside the realigned

tribituary.

"Recommendations

Restoration process for Drainage Line 1

The restoration process along Drainage Line 1 will involve treating only the A horizon topsoil. Some of the

ameliorants will work their way into the B Horizon however only in small quantities. Alternatively the A Horizon can

be stripped to treat the B Horizon however this is not deemed necessary for the Cumberland Plain Landscape.

Table 4. Schedule of amelioration requirements.

Soil Type Amelioration Requirement

Gypsum Lime Green Waste

Compost –

Soils for use

with general

tube-stock.

Chipped Hardwood Mulch*

Soils for use with

Cumberland re-vegetation

seeding.

A Horizon

Southern

end (BH 1 and BH2)

1kg/m3 or 100g/m2 4kg/m3 or

400g/m2

10 litres/m2 of compost 60/40 mix, using 60% soil

and 40% hardwood mulch.

Also apply 2 x applications of

20g/m2 of urea

A Horizon

Central and

Northern

end (BH 6 –

BH9)

80kg/m3 or 800g/m2 - 10 litres/m2 of compost 60/40 mix, using 60% soil



20g/m2 of urea

* The chipped hardwood mulch can be sourced from on-site trees that are to be removed during the upgrade.


July 2015

Page 9 of 11

Soil Stripping and amelioration for Drainage Line 2

The following methodology and amelioration is recommended:

Excavate soil to the depths specified in the Table 5 stripping plan. Stripping operators should observe the following

general guidelines:

• Remove large shrubs and trees first.

• Strip soil and pasture cover to the indicative depth from Table 5.

• Stop stripping if the more orange brown coloured clay subsoil starts showing through regardless of the

indicative depth.

• Stockpile soils from A and B horizon separately in a location where they will not be disturbed during

construction.

• Do not store soil within 8m of the trunk of any retained tree.

• Clearly label the stockpile with its soil horizon using permanent signage.

• Surround stockpiles with silt fencing.

Its imperative during the stripping that the process is carefully supervised to ensure that both weeds and subsoil

are not included with the topsoil.

Table 5. Profile description of Drainage Line 2 for stripping purposes.

Horizon A Horizon B Horizon C

Stripping Depth 250mm 250 - 800mm 800mm+

Colour Medium to dark brown Orange brown Paler orange

Texture Silty loam to silty clay loam Medium clay to sandy clay Light clay and crumbly

Aggregate strength Weak Moderate Weak

Topsoil Reinstatement

Reuse of Site Soils

Table 6 provides a schedule of amelioration requirements each of the soil horizons. These are the basic

amelioration requirements to correct the soil characteristics for Cumberland specific vegetation growth.


July 2015

Page 10 of 11

Table 6. Schedule of amelioration requirements.

Soil Type Amelioration Requirement

Gypsum Lime Green Waste

Compost –

Soils for use with general

tube-stock.

Chipped Hardwood Mulch*

Soils for use with

Cumberland re-vegetation seeding.

A Horizon 8kg/m3 or 800g/m2 4kg/m3 or

400g/m2

10 litres/m2 of compost 60/40 mix, using 60% soil



20g/m2 of urea

B Horizon 10kg/m3 or

1000g/m2

2 x applications

1kg/m3 or

100g/m2

C Horizon 10kg/m3 or

1000g/m2

2 x applications

1kg/m3 or

200g/m2

- -

* The chipped hardwood mulch can be sourced from on-site trees that are to be removed during the upgrade.

The use of lime will increase the pH levels making the soil less acidic, which will allow for many of the nutrients to

become more available. It is recommended that no additional fertilisers be used as the Cumberland woodland has

a preference for hostile and low nutrient environments. The addition of any further ameliorants will only promote

weed growth and not native growth.

Topsoil re-spreading and amelioration for use in landscape.

The method of application that proves most economical is usually-

1. Spray weed growth on the soil stockpiles with a 1:50 dilution of Roundup or other brand of Glyphosate

concentrate and wait 2 weeks.

2. Remove excess rank weed growth.

3. Place subsoil from the appropriate stockpile. Smooth over B Horizon with grader, consolidate but do not

compact.

4. Place topsoil from the appropriate stockpile to a depth of 250mm and incorporate ameliorants into the top

300mm as specified in Table 5 using chisel ploughs or rotary hoes or alternatively blend into stockpiles

using kg/m3.

5. Apply A Horizon but leave in loose condition for planting, do not consolidate.

6. Incorporate ameliorants into the surface 150mm of the topsoil as specified in Table 5 using chisel ploughs or

rotary hoes or alternatively blend into stockpiles using kg/m3.


July 2015

Page 11 of 11

In summary the soils along Ropes Creek are typical of Cumberland Plain landscape, which are hostile, acidic,

sodic and magnesic. Special care will need to be taken with overall management of stripping and amelioration.

Drainage Line 2 soils are very sodic therefore will easily disperse and care should be taken.

Please feel free to contact our office with any questions you may have.

Sincerely,

SESL Australia.

Chantal Milner

Soil Scientist

Simon Leake

Principal Soil Scientist

References

Bannerman, S.M. and Hazelton, P.A. (1990), Soil Landscapes of the Penrith 1:100 000 Sheet. Soil Conservation

Service of NSW, Sydney.

Mehlich, A. (1984) Mehlich-3 soil test extractant: a modification of Mehlich-2 extractant. Commun. Soil Sci. Plant

Anal. 15(12):1409-1416.

Appendices

Appendix A: Site/ Sampling Map

Appendix B: Profile descriptions

Appendix C: Laboratory Analysis

Appendix D: Site Photos

!

!

!!!

Appendix A Site & Sampling Map

12

6

7 8

9

5

3

4

!

!

Appendix B Profile Descriptions

Oakdale South Riperian CorridorAECOM

July 2015

Bore Hole

Depth (mm) Texture, Structure, Colour Observations

0-340 Medium brown silty loam

340-700Orange/brown medium clay. Some mottling with red and black. Manganese pellets More orange with depth.

BH 2 0-300Silty clay loam, greyish brown. Very wet and surroundngs quite wet. Filled with water @150mm

Drainage Line 1. 15m from creek line.

0-250 Silty brown loam.

250-930Orange brown medium clay with some darker mottling. Becoming a more medium orange with depth.

930-1100Paler orange brown. Soil is more crumbly and less clayey. Black manganese pellets. Some red mottling.

0-330 Medium dull brown, silty clay loam.

330-660 Sudden transition to B horizon. Orange brown clay loam. Red & grey mottling.

660-800 Change in soil, diffuse change.

@800 Soil is more crumbly, mottling of red, grey, back. Darker orangey brown colour.

@1100 Even more crumblier, silty clay.

0-600 Medium dark brown silty clay loam. Wet soil and @350mm becomes even wetter.

600+ Grey wet clay with a few orange mottles.

0-260 Dark brown silty clay loam

260-400 Yellowish dark brown clay. Wet


200+ Dark yellowish brown clay


300+ Browney, orange yellow medium clay0-270 Dark brown silty clay loam270+ Orange brown medium clay

BH 3 Drainage Line 2. Midway, greatest depth of proposed creek.

BH4 Drainage Line 2. South side of tree that will remain.

BH 5

BH 1 Drainage Line 1. 5m from creek line, profile dry.

Drainage Line 2. Lowest point in creek profile, overlaps proposed road.

Drainage Line 1

Drainage Line 1. 50m from creek line

BH 9

Darainge Line 1.

Drainage Line 1

BH 6

BH 7

BH 8

Documents

Introduction - Major Projects