Soil Contamination Risk Validation Report 117 & 119 ... · Nicola Peacock, Principal Environmental Engineer, NZCE, CEnvP (11 years contaminated land experience within 27 years environmental

Malloch Environmental Ltd 19 Robertsons Road, Kirwee

RD1, Christchurch 7671

021 132 0321

www.mallochenviro.co.nz

Soil Contamination Investigations • XRF Services •Environmental Planning

Soil Contamination Risk Validation Report

117 & 119 Kennedys Bush Halswell, Christchurch

July 2019

SVR – 117+119 Kennedys Bush Rd, Christchurch

Malloch Environmental Ltd Page 2

QUALITY CONTROL AND CERTIFICATION SHEET

Client: GW Halswell Ltd Date of issue: 1 July 2019

Report co-written by: Fran Hobkirk, Environmental Scientist, BSc (2 years contaminated land experience)

Signed:

Report co-written, reviewed and certified as a Suitably Qualified and Experienced Practitioner by: Nicola Peacock, Principal Environmental Engineer, NZCE, CEnvP (11 years contaminated land experience within 27 years environmental experience)

Signed:



CONTENTS

1 Executive Summary ......................................................................................................................... 4

2 Objectives of the Report ................................................................................................................. 4

3 Scope of Work Undertaken ............................................................................................................. 4

4 Site Identification ............................................................................................................................ 5

5 Summary of Site Description and Surrounding Environment ......................................................... 6

6 Geology and Hydrology ................................................................................................................... 6

7 Basis for Guideline Values ............................................................................................................... 6

7.1 Activity Description ............................................................................................................. 6

7.2 Zoning .................................................................................................................................. 6

7.3 Soil Guideline Values ........................................................................................................... 6

8 Summary of DSI Results .................................................................................................................. 7

9 Summary of Remediation Action Plan ............................................................................................ 7

10 Remediation Actions and Validation Sampling ............................................................................... 7

11 XRF Quality Assurance Measures .................................................................................................. 11

12 Field Quality Assurance and Quality Control ................................................................................ 11

13 Laboratory Quality Assurance and Quality Control ...................................................................... 11

14 Results Summary ........................................................................................................................... 11

15 Site Characterisation and Conclusion ........................................................................................... 12

16 Limitations..................................................................................................................................... 12

APPENDICES

A. DSI Sample Location Plan B. Validation Sample Location Plan C. Table of XRF Validation Results D. Laboratory Report E. Disposal Documentation



1 Executive Summary

The subject site is part of a large block of land on Kennedys Bush and Cashmere Road, in Southeast Halswell, Christchurch. It is proposed to subdivide the site for residential use. This will change the use of the land and result in disturbance of soils. The Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Health) Regulations 2011 (NESCS) require an assessment of the likelihood of soil contamination being present. It is noted also that Malloch Environmental Ltd is obligated to consider the requirements of Section 10 (4) of the Health and Safety at Work (Asbestos) Regulations 2016. The Detailed Site Investigation undertaken by Malloch Environmental Ltd in August 2017 identified arsenic and lead contamination of the soil, around the pre-1955 dwelling and the existing and historical farmyards. Contaminant levels were above ‘residential 10% produce’ Soil Guideline Values (SGV). It was recommended that the site be remediated by excavation and disposal of the contaminated soils to an approved facility. A copy of the DSI Sample Location Plan is included in Appendix A, which shows the identified contaminated area. The remediation was carried out in over two days, using XRF to determine the extent of the remediation required and to confirm the remediation had been successful. Lab results also confirmed successful remediation. There are some results with lead and arsenic contamination elevated above expected background levels, but the majority are well below the ‘residential 10% produce’ SGV. The total area of excavation was approximately 2400m2 with the depth of excavation ranging from 150-250mm deep. A total of 851.68 tonnes was disposed of at Burwood Landfill. The entire area was then subject to normal subdivision bulk earthworks and then filled with approximately 400-500mm depth of cleanfill in order to meet the subdivisions finished ground level requirements. The remediation actions have successfully remediated the identified contaminated areas. The site is considered to be suitable for its proposed residential use with no further actions required.

2 Objectives of the Report

The objective of the report is to detail the remedial actions undertaken which will ensure the site is suitable for future residential use. It also describes the validation sampling undertaken and results received. It has been completed in accordance with the Ministry for the Environment’s (MfE) “Contaminated Land Management Guidelines No 1: Reporting on Contaminated Sites in New Zealand”.

3 Scope of Work Undertaken

This report includes all requirements for a Stage 4 Validation report and includes:

• A summary of the site and the results of the previous reports

• Details of the remedial works undertaken

• Details of the validation sampling undertaken and results analysis

• Preparation of report in accordance with MfE guidelines



4 Site Identification

The site is located at street address 117 and 119 Kennedys Bush Road, Halswell, Christchurch as shown on the plans in Figure 1 below. The subject site is legally described as Lots 1 and 2 DP 474804 with a total area of approximately 3.8387Ha. The remediation area is approximately 2,350m2 of the site around the dwelling and farmyard areas. Figure 1 – Location Plan

N

#119 #117



5 Summary of Site Description and Surrounding Environment

The site is generally flat land near the base of the Port Hills, in South East Halswell. It is currently in rural use and is generally used for grazing. Prior to remediation a dwelling and farm buildings were present on the site. The subject site is bounded by a combination of residential and rural residential land. Halswell Quarry Park is beyond the subject site to the south.

6 Geology and Hydrology The ECan GIS describes the soil as Taitapu deep silty loam. Wells in the area indicate that topsoils are underlain by layers of soil and sand, shingle and clay. Soil trace elements are described as ‘Regional, Gley’. The site lies over the coastal confined gravel aquifer system. Wells on the site indicate that ground water levels are approximately 1-1.4m deep. The direction of ground water flow is generally in a south-east direction There are no open water features on the subject site.

7 Basis for Guideline Values 7.1 Activity Description

This report has been written for the following potential activities:

• Subdivision and development of the site for residential use,

• Soil disturbance activities associated with the above use and development of the site

7.2 Zoning

The subject site is currently zoned Residential New Neighbourhood.

7.3 Soil Guideline Values

Human health soil contaminant standards for a group of 12 priority contaminants were derived under a set of five land-use scenarios and are legally binding under The Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Health) Regulations 2011 (NES). These standards have been applied where applicable. The regulations describe these as Soil Contaminant Standards. For contaminants other than the 12 priority contaminants, the hierarchy as set out in the Ministry for the Environment Contaminated Land Management Guidelines No 2 has been followed. These are generally described as Soil Guideline Values. For simplicity, this report uses the terminology Soil Guideline Values (SGV) when referring to the appropriate soil contaminant standard or other derived value from the hierarchy. For soil, guideline values are predominantly risk based, in that they are typically derived using designated exposure scenarios that relate to different land uses. For each exposure scenario, selected pathways of exposure are used to derive guideline values. These pathways typically include soil ingestion, inhalation and dermal adsorption. The guideline values for the appropriate land use scenario relate to the most critical pathway.



The land-use scenarios applicable for this site would be ‘residential 10% produce’ and ‘commercial/industrial outdoor/maintenance workers’ as a proxy for construction workers disturbing soils.

8 Summary of DSI Results The Preliminary and Detailed Site Investigations (PSI and DSI) undertaken by Malloch Environmental Ltd in August 2017 identified areas of arsenic and lead contamination of the soil above ‘residential 10% produce’ Soil Guideline Values (SGV). A judgemental sampling strategy was used to sample areas of the site around the pre-1955 dwelling and the existing and historical farmyards. The results showed approximately 2,350m2 of the site contains lead contaminated soils with isolated arsenic hotspots. Lead levels ranged from 250-620 mg/kg, nearly triple the residential SGV. One isolated hotspot of arsenic recorded a concentration of 300mg/kg which also exceeds the commercial/outdoor worker SGV of 70mg/kg. This was a localised hotspot likely related to the visible ash seen. The DSI recommended that the lead and arsenic contaminated area be remediated prior to the site being used for a residential use. The DSI Sample Location Plan showing the area to be remediated is included in Appendix A.

9 Summary of Remediation Action Plan

Several remediation options were considered including leaving the soils in-situ, soil mixing, relocation on-site and off-site disposal. Off-site disposal was determined to be the most practical and cost-effective option for the site. The remediation goals were to ensure that the soils remaining after remediation of the identified contaminated areas have lead and arsenic concentrations below the residential 10% produce SGVs of 20mg/kg for arsenic and 210mg/kg for lead. It was proposed to excavate and dispose of the approximately 2,350m² of contaminated soil. It was noted that full delineation of the extent of contamination will be completed during the remediation. The delineation and remediation will be undertaken in conjunction with the use of a portable XRF to ensure all contaminated soils within the identified area are removed and that the volume of material removed is kept to the minimum required to achieve the remediation objective. The excavated soil is to be disposed of at Burwood landfill or an alternative authorised location. Following removal of the contaminated soils, validation of the excavated area using portable XRF and laboratory sampling will be undertaken.

10 Remediation Actions and Validation Sampling

An initial excavation was carried out by the contractors and Malloch Environmental Ltd were then requested to attend site on 12th March 2019 to test with portable XRF and determine what additional work was required. During the DSI investigations the soils were very wet and a reliable XRF/lab regression analysis was not obtained for lead, and there were insufficient arsenic results above the limit of detection. The typical most conservative regression analyses for other similar soils indicates a result on the XRF of less than 15mg/kg for arsenic or less than 150mg/kg for lead can reliably be expected to be below the SGV, in normal soil moisture conditions. At the time of the excavations and validations the soils were generally drier than normal. In practice, the majority of XRF readings of soils remaining in situ were well below these limits.



The excavation base was generally into the sandy silty subsoil layer. The topsoil depth was typically shallow. For all excavations, XRF testing of the walls of the excavation and the surface just beyond the excavation was carried out, as well as testing of the base of the excavation in an approximate 2-3m grid pattern. On arrival at site two large parts of the recommended excavation had been completed including the former house footprint and surround, and the larger former yard area. An area in the middle and to the north had been started but was still to be completed. XRF testing showed that the former house area had been successfully remediated to the west and north. Testing of the walls showed that to the south lead levels were still elevated and the extent of the affected area was delineated for further excavation. In the former yard area, the majority of the initial excavation was shown to have successfully remediated the contaminated soils. The exception was an area at the north end. The following day further excavation was completed with Malloch Environmental Ltd in attendance with the portable XRF. The area to the south of the former house, the strip through the middle and the northern area was all further excavated. XRF testing of the walls at approximately 5-100mm depth and the base of the excavation was carried out. Where results were over the limits mentioned above, a further scrape was done. The depth of excavation required to achieve remediation varied within a range of 150-250mm depth. The final excavated area was approximately 2400m2. Following 71 XRF tests of walls and base confirming successful remediation, five validation samples were collected for laboratory analysis of lead and arsenic, three from the base of the excavation and two from the walls at approximately 100mm depth. Photos below show the remediation progress, with painted circles indicating a good XRF result and a cross indicating further excavation is required.

Looking from the north over the excavated former yard area.



Looking from the north over the excavated former yard area.

Looking over northern part of former yard area to former house area.

Looking from the north over the excavated former yard area, validation in progress.



Delineating additional area for excavation adjacent to south of house area.

House area to left, former yard to right, mid area yet to be excavated

House area looking to road.



The validation plans included in Appendix B show the extent of the remediated areas and the XRF location groups on each day of testing. A table of XRF results is included in Appendix C, with the laboratory report in Appendix D. A total of 851.68 tonnes was disposed of at Burwood Landfill. Disposal documentation is attached in Appendix E.

11 XRF Quality Assurance Measures

The XRF used was an Olympus pXRF. The manufacturer’s instructions were followed in the use of the device. Standardization with the device standard was carried out prior to each day’s testing. Silicon blank readings were taken approximately every 20 samples to ensure there was no contamination of the XRF window. After each test the window was checked and cleared of visible soils as required. The US EPA Method 6200 - Field Portable X-ray Fluorescence Spectrometry for the Determination of Elemental Concentrations in Soil and Sediment (2007) was used as guidance for the use of the XRF and quality assurance measures. This method recommends that 5% of XRF tests should be verified through lab testing. A total of 71 XRF tests confirmed successful remediation and 5 samples were lab tested for lead and arsenic, which equates to 7%.

12 Field Quality Assurance and Quality Control

The Contaminated Land Management Guidelines No 5, Ministry for the Environment was followed for all aspects of the investigation. Field quality control procedures included ensuring decontamination procedures were followed. Samples were taken using a stainless steel trowel or fresh disposable nitrile gloves. All equipment was decontaminated between samples using Decon 90 and rinsed with tap water. Samples were collected in laboratory supplied containers and immediately placed in chilled bins. Following sampling, the samples were delivered to Hill Laboratory under chain-of-custody documentation.

13 Laboratory Quality Assurance and Quality Control

All samples were submitted to Hill Laboratories for analysis. Hill Laboratories hold IANZ accreditation. As part of holding accreditation the laboratory follows appropriate testing and quality control procedures. No quality control issues were identified.

14 Results Summary

More than 100 XRF tests were performed throughout the remediation process, with a total of 71 tests confirming successful remediation. The XRF measured final lead concentrations mostly around 20-50mg/kg, with only a few results up to around 100-110mg/kg. The highest lead result of soils remining in-situ was 142mg/kg. Final arsenic concentrations were mostly around 3-10mg/kg, with only a few results up to around 12-15mg/kg. The highest arsenic result of soils remaining in-situ was a single reading of 17mg/kg, in an area surrounded by much lower results. Although this is slightly above the recommended maximum XRF reading, the entire excavated area and surrounds area will have subsequent subdivision earthworks occurring and this will adequately mix soils so that there is no human health risk. It is also noted that a significant depth of approximately 400-500mm fill is required in the area to meet final subdivision finished ground levels.



Lab results were all well below the residential 10% produce SGV, with a maximum of 20mg/kg for lead and 6mg/kg for arsenic.

15 Site Characterisation and Conclusion

The remediation was carried out in over two days, using XRF to determine the extent of the remediation required and to confirm the remediation had been successful. Lab results also confirmed successful remediation. There are some results with lead and arsenic contamination elevated above expected background levels, but the majority are well below the ‘residential 10% produce’ SGV. A total of 851.68 tonnes was disposed of at Burwood Landfill. The remediation actions have successfully remediated the identified contaminated areas. The site is considered to be suitable for its proposed residential use with no further actions required.

16 Limitations

Malloch Environmental Limited has performed services for this project in accordance with current professional standards for environmental site assessments, and in terms of the client’s financial and technical brief for the work. Any reliance on this report by other parties shall be at such party’s own risk. It does not purport to completely describe all the site characteristics and properties. Where data is supplied by the client or any third party, it has been assumed that the information is correct, unless otherwise stated. Malloch Environmental Limited accepts no responsibility for errors or omissions in the information provided. Should further information become available regarding the conditions at the site, Malloch Environmental Limited reserves the right to review the report in the context of the additional information. Opinions and judgments expressed in this report are based on an understanding and interpretation of regulatory standards at the time of writing and should not be construed as legal opinions. As regulatory standards are constantly changing, conclusions and recommendations considered to be acceptable at the time of writing, may in the future become subject to different regulatory standards which cause them to become unacceptable. This may require further assessment and/or remediation of the site to be suitable for the existing or proposed land use activities. There is no investigation that is thorough enough to preclude the presence of materials at the site that presently or in the future may be considered hazardous. No part of this report may be reproduced, distributed, publicly displayed, or made into a derivative work without the permission of Malloch Environmental Ltd, other than the distribution in its entirety for the purposes it is intended.


Malloch Environmental Ltd

Appendix A – DSI Sample Location Plan

LEGEND

Soil sample location

Soil sample location XRF and

laboratory tested

Soil sample location that exceeds

the residential SGV for lead

Soil sample location that exceeds

the residential SGV for arsenic and

lead

Proposed area of remediation –

depth not expected to exceed

300mm and will be determined

during site excavation using

portable XRF

Remediation extent to be

delineated by XRF during

remediation

Notes:

1. This plan has been prepared for soil

contamination risk assessment purposes

only. No liability is accepted if the plan is

used for any other purposes.

2. Any measurements taken from this plan

which are not dimensioned on the electronic

copy are at the risk of the user.

3. Soil sample locations are approximate only.

4. On-site XRF testing during remediation

works may mean that the boundaries of

remediated areas will alter


801 East Maddisons Road, Rolleston

021 132 0321


Scale: NTS

Date: 4 August 2017

Drawing No: 01228/1

Sample Location Plan

117 + 119 Kennedys Bush Road, Christchurch

SS1

N

0 5 10 15 20 25m

SS3

SS2

SS1

SS10

SS12

SS14

SS9

SS11

SS15

SS5

SS6

SS7

SS8

Y2

Y4

Y5

Y6

Y7

Y8

Y9

Y10

Y11

Y12

Y13

Y14

Y15

SS1

SS1

SS1

SS4

SS13

Y3

Y1



Appendix B – Validation Sample Location Plans

RS 37879

VS4

VS3 wall

VS5

LEGEND

Lab validation sample location

Area of XRF test group – no further

excavation required

Area of XRF test group – further

excavation required

Extent of excavation area – approx.

150-250 mm depth

Notes: 1. This plan has been prepared for soil








Malloch Environmental Ltd 801 East Maddisons Road, Rolleston

021 132 0321


Scale: NTS

Date: 10 April 2019

Drawing No: 01228/2A

Validation Plan – 1st excavation


SS1

N

0 5 10 15 20 25m

VS1

VS4

VS3 wall

VS5

LEGEND

Lab validation sample location

Area of XRF test group – no further

excavation required

Area of XRF test group – further

excavation required

Extent of excavation area – approx.

150-250mm depth

Notes: 1. This plan has been prepared for soil









801 East Maddisons Road, Rolleston

021 132 0321


Scale: NTS

Date: 10 April 2019

Drawing No: 01228/2B

Validation Plan – post 2nd excavation


SS1

N

0 5 10 15 20 25m

VS1



Appendix C – Table of XRF Validation Results

XRF Validation Results - 117-119 Kennedys Bush RoadDate Time Reading Status As As +/- Pb Pb +/-

12-Mar-19 10:36:42 21 further excavated, disposed to Burwood 5 5 53 6







12-Mar-19 10:44:52 28 further excavated, disposed to Burwood -9 7 181 10














12-Mar-19 11:03:37 42 remains in situ 5 4 20 5




12-Mar-19 11:07:59 46 remains in situ -1 4 29 5




























12-Mar-19 11:47:17 74 blank -5 4 2 5






13-Mar-19 11:01:04 2 blank -1 2 2 3










13-Mar-19 11:12:56 12 disposed at Burwood 0 8 192 10



13-Mar-19 11:15:47 15 disposed at Burwood -2 7 162 10

























13-Mar-19 12:03:03 40 blank -1 3 1 4













Appendix D - Laboratory Report

R J Hill Laboratories Limited28 Duke Street Frankton 3204Private Bag 3205Hamilton 3240 New Zealand

0508 HILL LAB (44 555 22)+64 7 858 [email protected]

TTEW

This Laboratory is accredited by International Accreditation New Zealand (IANZ), which represents New Zealand in

the International Laboratory Accreditation Cooperation (ILAC). Through the ILAC Mutual Recognition Arrangement

(ILAC-MRA) this accreditation is internationally recognised.

The tests reported herein have been performed in accordance with the terms of accreditation, with the exception of

tests marked *, which are not accredited.

Certificate of Analysis Page 1 of 1

Client:

Contact: Nicola Peacock

C/- Malloch Environmental LimitedPO Box 259Kirwee 7543

Malloch Environmental Limited Lab No:

Date Received:

Date Reported:

Quote No:

Order No:

Client Reference:

Submitted By:

2141144

13-Mar-2019

18-Mar-2019

72157

Nicola Peacock

SPv1

Sample Type: Soil

Sample Name:

Lab Number:

VS1 13-Mar-2019

11:43 am

VS2 13-Mar-2019

11:45 am

VS4 13-Mar-2019

11:50 am

VS5 13-Mar-2019

11:53 am

2141144.1 2141144.2 2141144.3 2141144.4 2141144.5

VS3 13-Mar-2019

11:47 am

mg/kg dry wt 3 4 6 4 3Total Recoverable Arsenic

mg/kg dry wt 9.5 13.9 20 9.8 11.0Total Recoverable Lead

The following table(s) gives a brief description of the methods used to conduct the analyses for this job. The detection limits given below are those attainable in a relatively clean matrix.

Detection limits may be higher for individual samples should insufficient sample be available, or if the matrix requires that dilutions be performed during analysis.

Unless otherwise indicated, analyses were performed at Hill Laboratories, 28 Duke Street, Frankton, Hamilton 3204.

Summary of Methods

Sample Type: Soil

Test Method Description Default Detection Limit Sample No

1-5Environmental Solids Sample Drying* Air dried at 35°CUsed for sample preparation.May contain a residual moisture content of 2-5%.

-

1-5Environmental Solids SamplePreparation

Air dried at 35°C and sieved, <2mm fraction.Used for sample preparation.May contain a residual moisture content of 2-5%.

-

1-5Total Recoverable digestion Nitric / hydrochloric acid digestion. US EPA 200.2. -

1-5Total Recoverable Arsenic Dried sample, sieved as specified (if required).Nitric/Hydrochloric acid digestion, ICP-MS, screen level. USEPA 200.2.

2 mg/kg dry wt

1-5Total Recoverable Lead Dried sample, sieved as specified (if required).Nitric/Hydrochloric acid digestion, ICP-MS, screen level. USEPA 200.2.

0.4 mg/kg dry wt

These samples were collected by yourselves (or your agent) and analysed as received at the laboratory.

Samples are held at the laboratory after reporting for a length of time depending on the preservation used and the stability ofthe analytes being tested. Once the storage period is completed the samples are discarded unless otherwise advised by theclient.

This certificate of analysis must not be reproduced, except in full, without the written consent of the signatory.

Graham Corban MSc Tech (Hons)

Client Services Manager - Environmental



Appendix E – Disposal Documentation

Account_Number Account_Name Tran Docket Manifest_Number Special_Permit Date Time Vehicle Id Transporter Product Gross Weight Tare Weight Net Weight Unit Price Amount GST Amount Total Amount

4100427 GW Woodend Limited 420919 655652 18/162 5/03/2019 11:34 CSY636 Taggart Earthmoving Ltd CCC Special Soil Class A 25.84 12.12 13.72 $ 20.00 $ 274.40 $ 41.16 $ 315.56

4100427 GW Woodend Limited 420920 655652 18/162 5/03/2019 11:34 CSY636T Taggart Earthmoving Ltd CCC Special Soil Class A 19.42 5.10 14.32 $ 20.00 $ 286.40 $ 42.96 $ 329.36

4100427 GW Woodend Limited 420921 655652 18/162 5/03/2019 11:36 FRK274 Taggart Earthmoving Ltd CCC Special Soil Class A 19.38 10.56 8.82 $ 20.00 $ 176.40 $ 26.46 $ 202.86

4100427 GW Woodend Limited 420922 655652 18/162 5/03/2019 11:36 FRK274T Taggart Earthmoving Ltd CCC Special Soil Class A 16.98 6.22 10.76 $ 20.00 $ 215.20 $ 32.28 $ 247.48

4100427 GW Woodend Limited 420923 655652 18/162 5/03/2019 11:38 BSP644 Taggart Earthmoving Ltd CCC Special Soil Class A 18.36 10.40 7.96 $ 20.00 $ 159.20 $ 23.88 $ 183.08

4100427 GW Woodend Limited 420924 655652 18/162 5/03/2019 11:39 BSP644T Taggart Earthmoving Ltd CCC Special Soil Class A 20.28 7.76 12.52 $ 20.00 $ 250.40 $ 37.56 $ 287.96

































































851.68 $ 17,033.60 $ 2,555.04 $ 19,588.64

Documents

Soil Contamination Risk Validation Report 117 & 119 ... · Nicola Peacock, Principal Environmental Engineer, NZCE, CEnvP (11 years contaminated land experience within 27 years environmental