LOT 201 ARMSTRONG RD, KELMSCOTT LAND CAPABILITY FOR … · 4.0 CONCLUSION 15 5.0 REFERENCES 16 ... The investigation included nine test pits, four soil permeability tests, a preliminary

Sundowner Nominees Pty Ltd as trustee for the Bayley Cook Family Trust ABN 20 822 598 897 trading as Bayley Environmental Services

LOT 201 ARMSTRONG RD, KELMSCOTT

LAND CAPABILITY FOR ON-SITE EFFLUENT DISPOSAL

Prepared for

Armadale Gospel Trust c/- Rowe Group

369 Newcastle Street NORTHBRIDGE WA 6003

Report No. J18018a 1 October 2018

BAYLEY ENVIRONMENTAL SERVICES 30 Thomas Street SOUTH FREMANTLE WA 6162

Lot 201 Armstrong Rd, Kelmscott – Land Capability for On-site Effluent Disposal Page i ______________________________________________________________________________________

_____________________________________________________________________________________ BAYLEY ENVIRONMENTAL SERVICES

TABLE OF CONTENTS

Page

1.0 INTRODUCTION 1

2.0 SITE CHARACTERISTICS 2 2.1 Landforms and Soils 2

2.1.1 Topography 2 2.1.2 Geology and Soils 2 2.1.3 Acid Sulphate Soils 4

2.2 Hydrology 4 2.2.1 Surface Drainage 4 2.2.2 Groundwater 4 2.2.3 Wetlands 4

2.3 Vegetation 5 2.4 Fauna and Habitats 5 2.5 Neighbouring Land Uses 5 2.6 Land Capability for On-site Effluent Disposal 5

2.6.1 Site Area 5 2.6.2 Slope 6 2.6.3 Soil Profile 6 2.6.4 Soil Permeability 6 2.6.5 Published Land Capability Recommendations 7 2.6.6 Land Capability Summary 8 2.6.7 Setbacks 8

2.7 Aboriginal Heritage 9

3.0 EFFLUENT SYSTEM CONCEPTUAL DESIGN 10 3.1 Effluent Generation 10 3.2 System Selection 10 3.3 System Sizing 11

3.3.1 Septic Tanks 11 3.3.2 Leach Drains 12

3.4 System Location 13

4.0 CONCLUSION 15

5.0 REFERENCES 16

Lot 201 Armstrong Rd, Kelmscott – Land Capability for On-site Effluent Disposal Page ii ______________________________________________________________________________________


LIST OF TABLES

Table Title Page 2.1 Results of Infiltration Tests 7 2.1 Site Population and Operating Hours 10

LIST OF FIGURES Figure Title 1 Location and Layout 2 Oblique Aerial View 3 Environmental Features 4 Effluent System Proposed Location

LIST OF APPENDICES

Appendix Title A Soil Logs B PRI Test Results

Lot 201 Armstrong Rd, Kelmscott – Land Capability for On-site Effluent Disposal Page 1 ______________________________________________________________________________________


1.0 INTRODUCTION The Armadale Gospel Trust is proposing to establish a Place of Worship at Lot 201 Armstrong Rd, Kelmscott. Figure 1 shows the location and proposed layout of the facility. Figure 2 shows an oblique aerial photograph of the site. The facility is intended to accommodate varying numbers of worshippers for periods of one to 1½ hours, varying between 30-40 on Mondays and up to 480 on alternate Sundays. The site does not have access to deep sewerage, so the facility will need to employ on-site effluent disposal. Bayley Environmental Services was commissioned in September 2018 to examine the capability of the site to support on-site effluent disposal and to prepare a conceptual design and layout for the system. This report has been prepared based on the results of site investigations by Bayley Environmental Services and others, published information regarding the site and surrounds, project information supplied by Rowe Group, and consultation with the Health Department of WA regarding effluent generation rates.



2.0 SITE CHARACTERISTICS Bayley Environmental Services carried out a land capability assessment of Lot 201 in 2007 for a proposed health retreat. The investigation included nine test pits, four soil permeability tests, a preliminary tree survey, a preliminary site contamination assessment, preliminary acid sulphate soils (ASS) risk assessment, a search of the Department of Aboriginal Affairs’ (DAA) online database, collation and review of published and unpublished information regarding land capability. More recently, Structerre Consulting Engineers carried out a geotechnical investigation of the lot in 2018 in support of the current proposal. The investigation included drilling of three boreholes and excavation of eleven test pits across the site. In 2018 Bayley Environmental Services excavated a further 14 test pits in the area proposed for effluent disposal. The site description that follows is based on these investigations. 2.1 Landforms and Soils 2.1.1 Topography Lot 201 lies on the southern slope of the Canning River valley. The elevation ranges from about 25m AHD next to the river in the north to 35m AHD in the southern corner. The slope varies from about 4% to 8%. Topographic contours are shown on Figure 3. 2.1.2 Geology and Soils Soil Types The Geological Survey of Western Australia (GSWA) maps the upper parts of Lot 201 as Scg: Gravelly Clayey Sand – decomposed bedrock, gravel rock fragments, angular quartz, feldspar sands, clay minerals may flocculate to silt/sand size, of colluvial origin (Colluvium, Qc). The lower parts including the river are mapped as Ms4: Sandy Silt – cream to pale brown alluvium, clayey in part, fine to medium-grained sand, of alluvial origin (Alluvium, Qha). The GSWA mapping is shown on Figure 3. Test pitting at nine locations by Bayley Environmental Services in 2007 and a further 14 sites in 2018 (Figure 3) show that the soils on the upper slopes are generally red-brown clay-loams over orange and red clays, underlain by weathered granite. Granite rocks and boulders occur throughout the soil profile. On the lower and middle slopes the soils are deep red-brown silty loams over granite. Further testing in three boreholes and eleven test pits by Structerre in 2018 (Figure 3) found similar soil conditions, with silty alluvial sand to 1.5m to over 2.8m in the western part of the site and shallow silty soil to 0.1m-0.8m overlying clay, with rock occurring at



1.1m to over 2.8m in the eastern portion. Soil profile logs and photographs from the test pitting are attached in Appendix A. The Department of Agriculture (King & Wells, 1990) maps the south-east of the Lot as part of the Helena (H2) soil-landform unit and the north-west as Swan (Sw4) unit. These units are mapped on Figure 3 and described as follows: Helena (H2) Moderately inclined sideslopes and lower slopes of very deeply

incised river valleys. Black to brown to dark reddish brown clayey sand to sandy clay loam topsoils over very dark greyish brown to pale brown, shallow A2 horizon over yellow to brown, sandy clay loam to heavy clay subsoil, over saprolite (weathered granite). Granite subcrop and outcrop are common.

Swan (Sw4) Low, level to very gently inclined, occasionally flooded river

terraces with poorly drained variable alluvial soils featuring dark greyish brown to dark brown clay loam to silty clay topsoils sith a hard-setting surface, and dark brown, grey and black silty clay subsoils.

Soil Permeability Falling-head permeability tests carried out in 2006 using the method set out in the Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974 gave implied saturated hydraulic conductivity (Ks) values ranging from <0.17m/day to 26m/day. In the vicinity of Basin B the tests indicated a Ks of between 0.5m/day and 5m/day. Further details of the permeability tests are given in Section 2.6.4. Phosphorus Retention Index Phosphorus Retention Index (PRI) is a measure of the ability of a soil to adsorb and retain phosphorus from solution. A high PRI indicates that the soil is unlikely to leach phosphorus to the water table. Typical ranges for PRI in soils are as follows: PRI Range Rating Typical soils 0 – 0.5 Very Low Bassendean Sand 2 – 4 Low – Moderate Karrakatta Sands 5 – 12 Moderate – High Cottesloe Sands 12 – 20 High Crushed Limestone, Limesand 20 – 1000+ Very High Clay Soil testing at four sites at depths of 0.5m and 1.5-2m in the proposed vicinity of the leach drain on Lot 201 returned PRI values ranging from 36.6 to 1018.7. These show that the PRI of the site soils is very high. The results of the PRI tests are attached in Appendix B.



2.1.3 Acid Sulphate Soils The Department of Environment and Conservation (DEC) maps the Canning River watercourse and immediate surrounds as a high risk area for actual or potential acid sulphate soils (ASS). The high risk mapping extends into part of Lot 201 (Figure 3). Notwithstanding the DEC mapping, the on-site test pits show that the soils across most or all of the Lot, including all proposed development areas, are elevated with no wetland or estuarine influence. This suggests that no acid sulphate soils are likely to be present. 2.2 Hydrology 2.2.1 Surface Drainage There is no defined surface drainage within Lot 201, although overland flow may occur under extreme rainfall conditions. The Canning River is the dominant surface drainage feature of the area, being located adjacent to the northern boundary of the site. The Canning River has been heavily modified by upstream dams and now carries only low flows all year round. Flood mapping held by the DWER shows the 100-year floodway and flood fringe encroaching slightly into the lowest part of Lot 201 but posing no risk or constraint to the proposed development. 2.2.2 Groundwater There is unlikely to be significant groundwater present over most of the site given the shallow soils and presence of granite. Downslope seepage above the granite would probably occur in winter. Surface saturation was observed in an area of the upper slopes (Figure 4) in September 2018, following an unusually wet winter. A more substantial aquifer is likely to be present in the low, flat ground adjacent to the river. This aquifer may hold sufficient quantities of groundwater for domestic use, although the quality is unknown. Test pitting by BES in May 2007 found groundwater at 1.4m depth in one test pit, AK8, located in the far north of the lot about 20m from the river. Further test pitting by Structerre in late July 2018 and BES in September 2018 found no groundwater in any test pit. 2.2.3 Wetlands There are no wetlands within or adjacent to the Lot, except for the watercourse of the Canning River.



2.3 Vegetation Lot 201 is fully cleared of native vegetation except for a few mature flooded gums and paperbarks fringing the Canning River. There are a few planted eucalypts along the eastern boundary of the Lot. A macadamia orchard occupies about 1.5ha in the central north of the lot. The orchard has historically been irrigated with water drawn from the river. The orchard will be partly cleared to accommodate the development. Given the cleared nature of the lot, no rare or significant flora is likely to be present. No desktop or field search for rare or significant species was undertaken. 2.4 Fauna and Habitats Given the absence of native vegetation, there is little or no habitat within the lot for native fauna. The adjacent Canning River may provide some habitat for waterbirds, bandicoots, water rats and other native species, but its value would be limited by the narrowness of the riparian vegetation zone on this part of the river. 2.5 Neighbouring Land Uses Lot 201 is located in a rural-urban fringe area and is bounded to the east by farm paddocks, to the west and north by residential land and to the south by commercial and rural-residential uses. There are no land uses nearby that require buffering or that would be adversely affected by the proposed development of Lot 201. 2.6 Land Capability for On-site Effluent Disposal The Government Sewerage Policy (SGP, 1996?) sets site requirements for on-site effluent disposal including site area, slope and soil profiles. 2.6.1 Site Area The GSP limits the density (an hence lot size) of unsewered development in the Metropolitan area to “R5 equivalent”, or the equivalent of five standard residences per hectare. One standard residence is considered to produce 540 litres of effluent per day, so R5 equates to 2,700 litres per hectare per day.



The effluent system sizing for the proposed place of worship on Lot 201 is based on an effluent generation rate of up to 4,800 litres per day, in line with Health Department standards (see Section 3.1), although this volume is likely to be rarely if ever generated in a single day. The area of the lot is 5.46 hectares, giving an effluent load of 879 L/ha/day, or R1.6 equivalent. Thus the site has well in excess of the area required under the GSP. 2.6.2 Slope The GSP limits the slope of land used for effluent disposal to 20% (1 in 5). The slope in the area proposed for effluent disposal on Lot 201 (Figure 4) is in the order of 2.5%, well below the limit set by the GSP. 2.6.3 Soil Profile Test pitting and drilling at 37 locations (Figure 3) showed that all soils on the lot possess at least 0.5m clearance above groundwater. All of the test pits displayed at least 0.9m unsaturated soil profile above rock. The test pits in the eastern and upper parts of the lot showed a red loamy clay and clay profile over weathered granite, while those in the western and lower parts showed a sandy loam or loamy sand profile. There was no evidence of shallow groundwater except at 1.4m depth in Test Pit 8 near the river. It is likely that seepage would occur above the rock in the shallow soils in the east of the site. One area of surface saturation was observed in the south of the site in September 2018, likely to be due to retention of rainfall in the poorly-drained surface soils. The deeper silty soils in the west of the site contain no confining layers in the shallow profile that would give rise to seepage. 2.6.4 Soil Permeability Falling-head infiltration tests were carried out at four locations using the method set out in the Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974. The locations of the tests are shown on Figure 3. The purpose of the testing was to assess the capacity of the soils to absorb and disperse effluent. The infiltration test method essentially consists of filling a pre-soaked 30 x 30 x 60 cm hole with water and timing the rate at which it soaks away. In order for the soil to be suitable for a conventional leach drain, the water level should take no more than 60 minutes to fall from a depth of 40cm to 42.5cm. In addition to the basic 60-minute test above, regular measurements of the water depth in each test pit were made and used to calculate the saturated hydraulic conductivity (Ks) using the equation below:



Ks = ∆V/(A*∆t) where Ks = saturated hydraulic conductivity (m/day) ∆V = change in volume

A = average infiltration area (sides & base) over time interval ∆t = elapsed time (days) The results of the infiltration tests and calculations are set out in Table 2.1 below. Table 2.1 Results of Infiltration Tests

Site No. (see Figure 3)

Time for water to fall from 40cm to 42.5cm (maximum permitted = 60 minutes)

Hydraulic Conductivity below 40cm bgl (m/day)

K1 > 60 min <0.17

K4 0.4 min 26

K5 20 min 0.5

K6 2 min 5

Table 2.1 shows that three of the four test pits passed the Health Department test, indicating that the soils over most of the site are suitable for on-site effluent disposal using conventional leach drains. Test No. K1, located in the east of the Lot, displayed a very low hydraulic conductivity in the region below 0.35m depth, although the conductivity at shallower depths was higher (1.0 m/day below 0.3m). This suggests that this site, and soils like it, are not preferred for on-site effluent disposal. Test No. K4, located less than 30m north of K1, showed a very high conductivity (estimated at 26m/day below 40cm b.g.), suggesting the presence of one or more preferred flow pathways through the soil in this location – perhaps through fissures in the rock or clay. This would raise the possibility of rapid transport of effluent and contaminants through the soil in this location. Tests K5 and K6, located in the centre and west of the Lot, displayed moderate permeability and appear well suited to on-site effluent disposal. The results of the infiltration testing are in line with the findings of the soil profiling, which showed more clayey, highly-structured soils (which are more likely to have either very high or very low permeability) in the east and south of the Lot and lighter, more sandy soils in the west. 2.6.5 Published Land Capability Recommendations The Department of Agriculture’s Land Resources Series No. 3: Darling Range Rural Land Capability Study (King & Wells, 1990) rated the capability of the Helena-2 (H2) and Swan-4 (Sw4) soil-landscape units for on-site effluent disposal using septic tanks as follows:



Unit Capability Limiting factor(s) H2 Fair Soil absorption ability Sw4 Very Low Water pollution risk – by overland flow

The limitation due to soil absorption ability of the H2 land unit refers to the sometimes low permeability exhibited by the soils of this unit. The testing carried out to date on Lot 201 confirms the variability of the H2 unit but demonstrates that the soils in the west of the Lot, the soils are suitable for effluent disposal. 2.6.6 Land Capability Summary The test pitting and infiltration testing indicates that on-site effluent disposal may be effectively achieved on Lot 201, but that the soil capability varies significantly over the lot. The testing suggests that the western part of the lot is most suitable for on-site effluent disposal, while the eastern part is less so. 2.6.7 Setbacks The Department of Water & Environmental Regulation (DWER) Water Quality Protection Note (WQPN) 70: Wastewater Treatment – Onsite Domestic Systems (2006) recommends varying setbacks of effluent disposal systems from waterways depending on the type of system and the phosphorus retention index (PRI) of the soil, as follows: PRI <5 (e.g. grey sands) - Conventional septic system 100m - Nutrient removing system (eg Ecomax, Filtrex) 30m PRI >5 (e.g. loam, clay, yellow sand) 30m. The soils in the proposed effluent disposal area were tested and found to have PRI values ranging from 36.6 to 1018.7. Therefore a 30m setback would apply. The proposed leach drains are set back nearly 100m from the river (Section 3.4). The Swan River Trust’s Policy D3: Development Setback Requirements requires than commercial development on lots fronting the Swan-Canning Riverpark (areas zoned as Parks & Recreation) be set back by the lesser of ten metres or 20% of the width of the lot. On lots having title to the high water mark the minimum setback is 50 metres. Figure 4 shows that the Swan-Canning Riverpark abuts and in parts encroaches on Lot 201. The area proposed for effluent disposal is more than 60m from the Riverpark boundary and the high water mark. The Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974 require that leach drains be set back at least 1.8m from any building, septic tank or lot boundary. The Health Department’s draft Code of Practice for the Design, Manufacture, Installation and Operation of Aerobic Treatment Units (ATUs) (2001) recommends that subsoil effluent irrigation areas be set back at least 1.8m from buildings, paved areas and open-fenced lot boundaries. For closed-fenced boundaries



(e.g. fibro cement, brick), the required setback is 1.2m. The area proposed for effluent disposal easily complies with these setback requirements. 2.7 Aboriginal Heritage The Department of Aboriginal Affairs’ online Aboriginal Sites Database lists the Canning River and immediate surrounds as a registered Aboriginal Heritage site associated with the Waugyl myth. The registered site encroaches into Lot 201 by up to 30 metres, as shown on Figure 4. The area proposed for effluent disposal is more than 50m from the boundary of the registered site.



3.0 EFFLUENT SYSTEM CONCEPTUAL DESIGN 3.1 Effluent Generation The number of worshippers using the facility will vary from day to day and week to week. Worshippers will typically be on site for between one and 1½ hours. Table 3.1 shows the expected usage. Table 3.1 Site Population and Operating Hours

Monday Tuesday Wednes -day

Thursday Friday Saturday Sunday Alternate Sundays

Alternate Sundays

Number of Patrons

30-40 120-180 0 180-220 120-180 180-220 30-40 380-440 120-150

Time on Site 6pm-

7pm

7:15pm-

8:30pm

0 7:15pm-

8:30pm

7pm-

8:30pm

7:45am-

9:15am

6am-

7am

10am-

12pm

4:45pm-

6pm

Frequency Weekly Weekly 0 Weekly Monthly Monthly Weekly Fortnightly Fortnightly

The facilities on site will include toilets and hand basins but will not include showers, kitchens or laundry facilities. The Health Department of WA (A. Richard, pers. comm.) has advised that sizing of the effluent disposal system should be based on the maximum daily site population of 480 persons (Table 3.1) and an effluent generation rate of 10 litres/person/day, as set out in Supplement to Regulation 29 and Schedule 9 – Wastewater System Loading Rates (2017). This gives a design effluent flow of 4,800 litres/day. 3.2 System Selection Effluent treatment and disposal may be achieved by: a conventional septic tank and leach drain system; septic tanks with a modified (nutrient-removing) leach drain (e.g. Ecomax, Filtrex); an aerobic treatment unit (ATU) with leach drains; or an ATU with subsoil irrigation. Septic systems have the advantage of being relatively cheap to install and operate. They also can be gravity-fed (site layout permitting), and the disposal area may be used for low-impact recreation (including walking, croquet lawns etc.). Maintenance of septic tank/leach drain systems consists of turning a valve every six to twelve months to switch between leach drain pairs, and infrequent (generally every four to ten years) desludging of the septic tanks.



A disadvantage of septic systems is that the leach drains require a minimum total soil depth of 2m above confining layers such as rock or heavy clay, so that partial or complete inversion (mounding) might be required for leach drains in shallow soil areas. Modified leach drain systems use a conventional septic tank but the leach drain is filled with an amended soil (such as red sand bauxite residue) and enclosed in an impermeable membrane, so that the effluent flow from the leach drain is forced up through the amended soil before exiting at the top of the membrane. Because the exit point is at the top, rather than the bottom of the leach drain, these systems can be installed closer to the water table. Their main advantage is their ability to remove up to 95% of phosphorus from the effluent. Modified leach drain systems are more expensive to purchase and install but their operation and maintenance are essentially the same as for conventional septic systems. Aerobic treatment units (ATUs) are essentially mini wastewater treatment plants, with multiple chambers operated by electric pumps and, in some cases, chemical dosing. They produce a higher quality of effluent than septic tanks, although not as high as modified leach drain systems. Treated ATU effluent can be disposed of by leach drains or by subsoil irrigation. The major advantage of ATUs is that the height of the disposal system is only about 150mm (essentially the depth of soil cover over the drip lines), so the irrigation area can be sited on areas of shallow soil with less need for mounding than leach drains. The disadvantages of ATUs are: they are more expensive than septic systems to purchase, install and operate; they require regular (generally every three months) maintenance by a qualified

person; they require inputs of power for the operation of the ATU and pressure distribution of

the treated effluent; if using effluent irrigation, the irrigation area must be dedicated for this purpose and

cannot be used for anything else; and they cope less well with “shock loadings” and widely varying daily effluent flows. The scale and operation of the proposed place of worship, with intermitted occupancy and occasional large populations, does not favour an ATU system. The system sizing and layout discussion below is based on a septic tank/leach drain system. 3.3 System Sizing 3.3.1 Septic Tanks The Health Regulations require that a septic system should include a tank or tanks with a “reserve capacity” of 1,820 litres plus an allowance (in this case, 10 litres/day) for



each person served by the system. Based on the effluent generation rates in Section 3.1, this equates to a tank or tanks totalling 6,620 litres. 3.3.2 Leach Drains Leach drain sizing in commercial applications is primarily determined by the effluent volume and quality and the soil type (and hence permissible effluent loading rate). Australian Standard AS1547:2012 – On-site Domestic Wastewater Management sets out recommended daily loading rates for different soil types. Based on this and advice from the Health Department (A. Richard, pers. comm.), a Design Loading Rate (DLR) of 30mm/day has been adopted in this case for septic tank effluent. Leach drains consist of a concrete or brick channel with an open floor and perforated sides, with a nominal internal width of 0.4m, an external width of 610mm and a height of 0.6m. The leach drain is laid in a trench which is backfilled with a layer of porous material (e.g. blue metal) overlain with soil. Different sizes of leach drain can be created by laying leach drain sections end-to-end (to a maximum length of 20m) and/or by laying drains side by side. Leach drains are normally arranged in pairs, with one of each pair being used and rested in a 6 to 12 month rotation. The leach drains must be laid across the slope on a lengthwise gradient of 1:200. Based on the requirements and recommendations of the Government Sewerage Policy, the Health (Treatment of Effluent and Disposal of Liquid Waste) Regulations 1974, the draft Code of Practice for Onsite Sewage Management (2012), Australian Standard AS1547:2012 and the City of Armadale’s A guide to onsite effluent disposal applications (20__), the following design parameters have been adopted for leach drains on the site:

Leach drain length Minimum 6m Maximum 20m (Code of Practice)

Leach drain width Internal 0.4m (Health Regulations) External 0.61m (Health Regulations)

Aggregate surrounding leach drain 0.3m (City of Armadale) Spacing between leach drains 3m (City of Armadale).

The diagram below illustrates this conceptual design.

LEACHDRAIN

LEACHDRAIN

AGGREGATE AGGREGATE AGGREGATE AGGREGATE

TOPSOIL COVER

SURROUNDING SOIL

0.6m 0.6m 0.3m0.3m0.3m0.3m 2.4m

LEACHDRAIN

LEACHDRAIN

AGGREGATE AGGREGATE AGGREGATE AGGREGATE

TOPSOIL COVER

SURROUNDING SOIL

0.6m 0.6m 0.3m0.3m0.3m0.3m 2.4m



This design gives an effective infiltrative width of 1.6m, comprising the base and sides of the leach drain. When leach drains are arranged in parallel, each leach drain occupies an effective width of 3.6m. The size of the leach drain field required can be calculated from the DLR and the leach drain dimensions as follows: Effluent volume = 4.8m3/day DLR = 0.03m/day Length of leach drain = 4.8 / (1.6 x .03) = 100m (arranged in two end-to-end groups of 3 x 16.7m leach drains) Total width = 3 x 0.6 + 2 x 3 = 7.8m Total length = 2 x 16.7 + 3 = 36.4m Total area = 7.8 x 36.4 = 284m2 Figure 4 shows indicative footprints on the site of leach drains for septic tanks. 3.4 System Location Site tests by BES (2007 & 2018) and Structerre (2018) (Section 2.1.2) found shallow clayey soils in the eastern and higher parts of the site and deeper silty loam soils in the western and lower parts. Permeability testing by BES (2007) found that the silty loam soils had suitable permeability for effluent disposal, while the clay soils had highly variable permeability. For these reasons the preferred location for the effluent disposal area is on the western side of the main building. This is conveniently downhill of the building, facilitating gravity feed. The septic tanks will be located close to the toilet facilities, with the disposal field located to the west. The location of the disposal field is constrained by: foreshore setbacks from the Canning River (50m from high water mark, HWM); the floodway and flood fringe of the river (30-65m from HWM); the boundary of the Aboriginal heritage site (about 30m from HWM); effluent disposal setbacks recommended by DWER (30m for PRI>5); and Armadale policy PLN2.6 (2017) 50m setback from major watercourses. These constraints are shown on Figure 4. The major factor determining the disposal field location is the boundary between the shallow clayey upland soils and the sandy loam soils of the lower slopes. To better define this boundary, further test pitting was carried out in the area of the proposed leach drains in September 2018. The testing consisted of excavating fourteen test pits



to at least 2m in three transects across the proposed leach drain field (Figure 4), as well as observations of surface soil conditions. The testing found that the location originally proposed for the leach drains, just over 100m from the river, had clayey soils with, in one case, weathered granite at 1.6m depth. It was also observed that surface saturation after heavy rainfall extended from the east into this area. For these reasons the leach drain location was moved approximately 10m west, where the test pitting showed a deep silty loam profile with no shallow rock or evidence of saturation. Figure 4 shows the proposed location of the disposal field, based on the results of the soil testing.



4.0 CONCLUSION Site investigations by BES (2007 and 2018) and Structerre (2018) have shown that Lot 201 Armstrong Road is suitable for on-site effluent disposal at the scale proposed. Based on the project characteristics and the site conditions, a conventional septic tank/leach drain system is considered appropriate. An ATU is not recommended due to the widely varying effluent loads. Based on the project characteristics and site conditions, the recommended location and approximate size of the leach drain field are shown on Figure 4. The sizing and location will be refined and confirmed as part of detailed design by the system supplier.



5.0 REFERENCES Churchward H.M. and W.M. McArthur (1980). Landforms and Soils of the Darling

System, Western Australia. In Atlas of Natural Resources: Darling System, Western Australia. Dept of Conservation & Environment, Perth.

City of Armadale (20__). A guide to onsite effluent disposal applications. City of

Armadale, Armadale WA. DoW (2006). Water Quality Protection Note 70: Wastewater treatment – onsite

domestic systems. Department of Water, Perth. Environmental Protection Authority (1983). Conservation Reserves for Western

Australia as recommended by the Environmental Protection Authority. The Darling System – System 6. Part II: Recommendations for Specific Localities. Dept of Conservation & Environment, Perth.

Government of Western Australia (2000). Bush Forever. WAPC, Perth. Government of Western Australia (2003). Health Act 1911: Health (Treatment of

Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974. Health Department of Western Australia (2001). Code of Practice for the Design,

Manufacture, Installation and Operation of Aerobic Treatment Units (ATUs). Health Department of WA, Perth.

King P.D. and M.R. Wells (1990). Darling Range Rural Land Capability Study. Land

Resources Series No. 3. Department of Agriculture, Perth. Somerville, S.H. (1986). Control of Groundwater for Temporary Works. Construction

Industry Research and Information Association, London, U.K. ISSN:0305-408X. Standards Australia (2012). Australian/New Zealand Standard 1547:2012 – On-site

Domestic Wastewater Management. SAI Global Ltd, Sydney. Structerre (2018). Geotechnical Investigation, 31 Armstrong Road, Kelmscott.

Unpublished report prepared for Bend Tech Group, Maddington, WA. Swan River Trust (2007). Draft Policy SRT/D3: Development Setback Requirements.

Swan River Trust, Perth. _

Figures

#

0 100 Meters

Figure 1

LOCATION AND LAYOUT

Proposed leachdrain location

Place of Worship

Subject Site

Figure 2

OBLIQUE AERIAL VIEW

N

#

#

#

#

#

#

#

#

#

#

0 100 Meters

Figure 3

ENVIRONMENTAL FEATURES

Site boundaryTopographic contour (1m interval)100-year floodway100-year flood fringeHigh ASS risk (DWER)GSWA geology boundaryDoA land unit boundaryBES (2007) test pitBES permeability testStructerre (2018) borehole/test pitBES (2018) test pit

Site boundaryTopographic contour (1m interval)100-year floodway100-year flood fringeHigh ASS risk (DWER)GSWA geology boundaryDoA land unit boundaryBES (2007) test pitBES permeability testStructerre (2018) borehole/test pitBES (2018) test pit

TP7

H2

Sw

Sgc (Qc)

Ms4 (Qha)

KP1

KP2KP2A

KP3

KP4

KP5

KP6KP7 KP8

KP9KP10

KP11

KP12KP13

#

##

#

#

##

#

#

#

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#

KP3

KP12

KP13

KP4

KP5

KP6

0 50 Meters

Figure 4

EFFLUENT SYSTEMPROPOSED LOCATION

Proposed Leach Drains

Indicative SepticTank Location

KP1

KP2

KP2A

KP3KP4

KP5

KP6

KP7KP8

KP9KP10

KP11

KP12KP13

Site boundary100-year floodway100-year flood fringeSwan-Canning Riverpark (SRT)Aboriginal heritage site boundary50m setback from high water mark (SRT/CoA)30m setback from high water mark (DWER)100m setback from high water mark (DWER)Visible surface saturationBES (2018) test pitProposed leach drains

Site boundary100-year floodway100-year flood fringeSwan-Canning Riverpark (SRT)Aboriginal heritage site boundary50m setback from high water mark (SRT/CoA)30m setback from high water mark (DWER)100m setback from high water mark (DWER)Visible surface saturationBES (2018) test pitProposed leach drains

Appendix A

Soil Logs

J06030

K1

Excavator

1.15

Y

7/05/2007

DEPTH (m) SAMPLE ID INTERVAL (m)

0 - 0.55

0.55 - 0.9

0.9 - 1.15

1.15

FURTHER COMMENTS:

EASTING: NORTHING:

DEPTH TO WATER (mbgl)

Refusal on weathered granite

SOIL DESCRIPTION

Red-brown loam with granite boulders to 40cm

Red clay with occasional white mottling, very hard

Yellow-brown weathered granite

SOIL PROFILE SAMPLE DATA

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

J06030

K2

Excavator

1

Y

7/05/2007


0 - 0.3

0.3 - 0.65

0.65 - 1.0

1

FURTHER COMMENTS:

EASTING: NORTHING:

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):




SOIL DESCRIPTION

Red-brown loam

Orange loamy clay, well structured breaking into clods 5-20cm, with granite boulders to 30cm

Yellow-brown weathered granite

J06030

K3

Excavator

0.9

Y

7/05/2007


0 - 0.2

0.2 - 0.85

0.85 - 0.9

0.9

FURTHER COMMENTS:

EASTING: NORTHING:


Refusal on granite

SOIL DESCRIPTION

Red-brown loam

Red -brown clay

Orange-brown gritty clay to weathered granite with granite boulders


REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

J06030

K4

Excavator

0.95

Y

7/05/2007


0 - 0.25

0.25 - 0.85

0.85 - 0.95

0.95

FURTHER COMMENTS:

EASTING: NORTHING:

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):



Refusal on granite

SOIL DESCRIPTION

Dark red-brown loam

Orange-brown mottled clay

Weathered granite

J06030

K5

Excavator

1.1

Y

7/05/2007


0 - 0.3

0.3 - 0.7 Red-orange clay-loam

0.7 - 1.1

1.1

FURTHER COMMENTS:

EASTING: NORTHING:

SOIL DESCRIPTION

Red loam

Dark brown clay


Refusal on granite

REFUSAL (Y/N):

DATE:


TOTAL DEPTH (mbgl):

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

J06030

K6

Excavator

2.1

N

7/05/2007


0 - 0.75

0.75 - 2.1 Orange-brown loamy sand

FURTHER COMMENTS:

EASTING: NORTHING:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

REFUSAL (Y/N):

DATE:


TOTAL DEPTH (mbgl):

SOIL DESCRIPTION

Dark red-brown sandy loam


J06030

K7

Excavator

1

Y

7/05/2007


0 - 0.25

0.25 - 0.55

0.55 - 1.0

1

FURTHER COMMENTS:

EASTING: NORTHING:


Refusal on granite

SOIL DESCRIPTION

Red-brown loam

Red-brown clay

Orange-brown mottled gritty clay with granite boulders, tending to weathered granite


REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

J06030

K8

Excavator

1.7

N

7/05/2007


0 - 0.25

0.25 - 0.65 Pale brown to dark brown clayey silty sand

0.65 - 1.4

1.4 - 1.7

FURTHER COMMENTS:

EASTING: NORTHING:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

REFUSAL (Y/N):

DATE:


TOTAL DEPTH (mbgl):

Grey mottled gritty clay, wet

SOIL DESCRIPTION

Dark red-brown sandy loam

Dark brown silty loam with occasional granite boulders to 40cm


J06030

K9

Excavator

1.2m

Y

7/05/2007


0 - 0.2

0.2 - 0.35

0.35 - 1.2

1.2

FURTHER COMMENTS:

EASTING: NORTHING:

SOIL DESCRIPTION

Dark brown loam

Orange mottled clay with very occasional granite boulders to 20cm


Red clay-loam

Refusal on granite

REFUSAL (Y/N):

DATE:


TOTAL DEPTH (mbgl):

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

J18018

KP1

408862.40

6445619.96

3-tonne excavator

1.6

Y

13/09/2018

Not encountered


0 - 0.3

0.3 - 0.9 KP1 0.5m

0.9 - 1.6

1.6

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:



SOIL DESCRIPTION

Dark brown silty loam topsoil

Dark orange-brown silty loam with occasionan orange mottles

Mottled orange-brown-grey silty clay with occasional granite cobbles


J18018

KP2

408856.24

6445624.81

3-tonne excavator

2.3

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 1.4 KP2 0.5

1.4 - 2.3



SOIL DESCRIPTION

Dark brown silty loam topsoil, damp

Dark orange-brown silty loam with occasional granite stones

Red-brown/grey mottled silty clay, moderately structured, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP2A

408852.40

6445625.15

3-tonne excavator

2.3

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 1.5

1.5 - 2.3

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION

Dark brown silty loam topsoil, moist

Orange-brown silty loam grading to orange-brown silty clay, damp

Red-brown/brown mottrled silty clay, moderately structured, damp


J18018

KP3

408847.02

6445627.42

3-tonne excavator

2.6

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 2.6 KP3-1 0.5

KP3-2 1.5 - 2



SOIL DESCRIPTION


Red-brown silty loam, moderately structured, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP4

408834.93

6445633.29

3-tonne excavator

2.6

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 0.9 KP4-1 0.5

0.9 - 2.6 KP4-2 1.5 - 2

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION


Dark brown silty loam

Red-brown silty loam, moderately structured, moist


J18018

KP5

408833.50

6445617.25

3-tonne excavator

2.4

N

13/09/2018

Not encountered


0 - 0.6

0.6 - 2.4



SOIL DESCRIPTION


Red-brown silt, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP6

408840.86

6445612.82

3-tonne excavator

1.9

N

13/09/2018

Not encountered


0 - 0.5

0.5 - 1.4

1.4 - 1.9

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION


Red-brown silt

Red-brown clayey silt


J18018

KP7

408850.29

6445607.05

3-tonne excavator

2.1

N

13/09/2018

Not encountered


0 - 0.5

0.5 - 2.1



SOIL DESCRIPTION


Orange-brown/brown mottled silty clay, moderately structured, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP8

408857.25

6445608.33

3-tonne excavator

2.0

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 1.6

1.6 - 2.0

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION


Brown/grey clayey silt - silty clay with orange mottles, small orange pebbles and occasional granite cobbles

Brown/orange/red mottled silty clay, moderately structured


J18018

KP9

408868.67

6445634.59

3-tonne excavator

2.2

N

13/09/2018

Not encountered


0 - 0.4

0.4 - 2.2



SOIL DESCRIPTION


Orange/brown mottled clayey silt with common laterite pebbles and occasional granite cobbles, grading to moderately structured silty clay

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP10

408858.35

6445635.57

3-tonne excavator

2.0

N

13/09/2018

Not encountered


0 - 0.5

0.5 - 1.1

1.1 - 2 KP10 1.5 - 2

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION


Brown clayey silt with red-brown mottles, moderately structured

Red/brown mottled silty clay


J18018

KP11

408855.74

6445637.32

3-tonne excavator

2.2

N

13/09/2018

Not encountered


0 - 0.5

0.5 - 2.2



SOIL DESCRIPTION


Red-brown mottled clayey silt - silty clay, moderately structured, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

J18018

KP12

408849.86

6445641.00

3-tonne excavator

2.1

N

13/09/2018

Not encountered


0 - 0.5

0.5 - 2.1 KP12 1.5 - 2

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:


SOIL DESCRIPTION


Dark red-brown clayey silt with black mottles, moderately structured, damp


J18018

KP13

408839.56

6445643.38

3-tonne excavator

2.3

N

13/09/2018

Not encountered


0 - 0.3

0.3 - 2.3 KP13 1.5 - 2



SOIL DESCRIPTION


Red-brown silt, moderately structured, moist

REFUSAL (Y/N):

DATE:

SOIL PROFILE LOG

PROJECT NUMBER:

SITE ID:

METHOD:

TOTAL DEPTH (mbgl):

EASTING:

NORTHING:

Appendix B

PRI Test Results

LABORATORY REPORT

Job Number: 18-13756

Revision: 00

ADDRESS: Bayley Environmental Services Date: 21 September 2018

30 Thomas Street

South Fremantle WA 6162

ATTENTION: Phil Bayley

DATE RECEIVED: 14/09/2018

YOUR REFERENCE: J18018 - Armadale Gospel - Armstrong Rd

PURCHASE ORDER:

APPROVALS:

REPORT COMMENTS:

This report is issued by Analytical Reference Laboratory (WA) Pty Ltd

Phosphorus Retention Index analysis subcontracted to CSBP, Report Number 2IS18034-40

METHOD REFERENCES:

Subcontracting See Report Comments section for more information.

ARL GROUP

46-48 Banksia Road, Welshpool, Western Australia 6106

Telephone: 08 6253 4444 Facsimile: 08 6253 4440 www.arlwa.com.au www.promicro.com.au

Page 1 of 2

LABORATORY REPORT

Bayley Environmental Services

ARL Job No: 18-13756 Revision: 00 Date: 21 September 2018

RESULTS:

Subcontracting

Sample No: LOR UNITS 18-13756-1 18-13756-2 18-13756-3 18-13756-4 18-13756-5

Sample Description: KP3-1 KP3-2 KP4-1 KP4-2 KP12

Sample Date: 14/09/2018 14/09/2018 14/09/2018 14/09/2018 14/09/2018

Phosphorus Retention Index 150.5 209.5 53.5 36.6 1028.7

Subcontracting

Sample No: LOR UNITS 18-13756-6

Sample Description: KP13

Sample Date: 14/09/2018

Phosphorus Retention Index 64.7

Result Definitions

LOR Limit of Reporting [NT] Not Tested [ND] Not Detected at indicated Limit of Reporting

* Denotes test conducted by in-house methodology

FOR MICROBIOLOGICAL TESTING - The data in this report may not be representative of a lot, batch or other samples and may not necessarily justify the acceptance

or rejection of a lot or batch, a product recall or support legal proceedings. Tests are not routinely performed as duplicates unless specifically requested. Changes

occur in the bacterial content of biological samples. Samples should be examined as soon as possible after collection, preferably within 6 hrs and must be stored at 4

degrees Celsius or below. Samples tested after 24 hrs cannot be regarded as satisfactory because of temperature abuse and variations.

ARL GROUP

46-48 Banksia Road, Welshpool, Western Australia 6106

Telephone: 08 6253 4444 Facsimile: 08 6253 4440 www.arlwa.com.au www.promicro.com.au

Page 2 of 2

Documents

LOT 201 ARMSTRONG RD, KELMSCOTT LAND CAPABILITY FOR … · 4.0 CONCLUSION 15 5.0 REFERENCES 16 ... The investigation included nine test pits, four soil permeability tests, a preliminary