table of contents - department of defence...surface water quality monitoring is undertaken to...

Table of contents 1. Introduction..................................................................................................................................... 1

1.1 Overview .............................................................................................................................. 1 1.2 Objectives ............................................................................................................................ 1

2. Summary of recommendations ...................................................................................................... 2

3. Scope of works ............................................................................................................................... 3

4. Methodology ................................................................................................................................... 4

4.1 Surface water quality sampling ............................................................................................ 4

4.2 Assessment criteria for water quality ................................................................................... 4

5. Field and analytical results ............................................................................................................. 8

5.1 Field observations ................................................................................................................ 8 5.2 Surface water quality ........................................................................................................... 8

6. Discussion of results ...................................................................................................................... 9

6.1 Overview .............................................................................................................................. 9

6.2 Location MD1 ....................................................................................................................... 9

6.3 Location DD1 ..................................................................................................................... 10 6.4 Locations F8 and F9 .......................................................................................................... 12

7. Conclusions .................................................................................................................................. 13

8. Limitations .................................................................................................................................... 14

9. References ................................................................................................................................... 16

Table index Table 3-1 MD1 and DD1 catchment details ......................................................................................... 3

Table 4-1 Assessment criteria for surface water quality at RAAF WLM .............................................. 5

Table 4-2 Site specific trigger values for RAAF WLM .......................................................................... 7

Table 6-1 Exceedances at MD1 – First-Flush .................................................................................... 10

Table 6-2 Exceedances at MD1 – Follow Up ..................................................................................... 10

Table 6-3 Exceedances at DD1 – First Flush .................................................................................... 11

Table 6-4 Exceedances at DD1 – Follow Up ..................................................................................... 11

Table 6-5 Exceedances at F8 and F9 ................................................................................................ 12

GHD | Report for Department of Defence - Surface Water Quality Monitoring RAAF Base Williamtown, 22/16319 | ii

Appendices Appendix A – Figures

Appendix B – Tables

Appendix C – Quality assurance and quality control

GHD | Report for Department of Defence - Surface Water Quality Monitoring RAAF Base Williamtown, 22/16319 | iii

1. Introduction1.1 Overview

GHD Pty Ltd (GHD) was commissioned by Transfield Services Australia Pty Ltd (Transfield), on behalf of the Department of Defence (Defence), to carry out quarterly surface water quality monitoring at RAAF Base Williamtown (RAAF WLM) as part of the Water Quality Monitoring works for the Central Northern NSW (CN NSW) Region. This report details the work carried out and highlights results from the February 2014 monitoring round, undertaken on 20 February 2014.

Previously, surface water quality monitoring was undertaken on a monthly basis between May 2003 and June 2008. Since June 2008, the monitoring frequency has been altered from monthly to quarterly. The last monitoring round was undertaken by GHD in November 2013. The November 2013 monitoring round was the first round to implement event based sampling based on the previous recommendations by GHD.

1.2 Objectives

Surface water quality monitoring is undertaken to satisfy Condition of Consent No. 18 of the Environmental Impact Statement for the introduction into service of the Hawk Lead-In Fighter. Additionally, Defence wishes to determine whether the quality of the surface water exiting RAAF WLM could impact receiving environments such as the aquatic ecosystems and oyster growing industry within the Port Stephens and Hunter River Estuaries and the Tomago Sandbeds drinking water supply.

GHD | Report for Department of Defence - Surface Water Quality Monitoring RAAF Base Williamtown, 22/16319 | 1

2. Summary of recommendationsThere are no new recommendations based on this monitoring round.


4. Methodology4.1 Surface water quality sampling

Surface water sampling was undertaken at sites MD1, DD1, F8 and F9 in general accordance with ANZECC/ARMCANZ (2000b) Guidelines for Water Quality Monitoring and Reporting. Stormwater samplers were installed at MD1 and DD1 to collect ‘first-flush’ samples during rainfall events as per the recommendations in GHD (2013). This round of surface water monitoring was the second monitoring round to be conducted following a rainfall event. The surface water monitoring event was specifically conducted to coincide with a rainfall event. A rainfall event was defined as 5-10 mm of rainfall in the previous 24 hours.

Surface water monitoring was conducted on 20 February 2014, with both ‘first-flush’ (F-F) sampling and ‘follow-up’(F-U) sampling conducted on the same day. The surface water monitoring was undertaken with reference to ANZECC/ARMCANZ (2000b) Guidelines for Water Quality Monitoring and Reporting. This involved:

Collection of samples as follows:

– “First-flush Samples”(F-F) were collected via the transfer of water stored in thestormwater samplers into appropriately preserved containers. The sampling from thestormwater samplers were prioritised based on the primary water quality issues at theSite. The priority sampling was required to ensure relevant water quality issues wereassessed and addressed as volumes were limited as a result of the stormwatersamplers 1 litre capacity. Surface water samples collected from the stormwatersamplers were assigned with the suffix “F” to the Location name, that is, the first-flushsample for monitoring location MD1 was identified as MD1F.

– “Follow-up Samples”(F-U) were generally collected by immersion (using a samplingpole) of clean unpreserved sample containers to a depth of 0.3 m if possible. Themouth of the containers faced upstream during filling. Collected water was thenpoured into appropriately preserved sample containers.

Samples for dissolved heavy metal analysis were filtered in the field using a 0.45 µmfilter.

Silica gel clean-up for Total Petroleum Hydrocarbon (TPH) analysis was undertaken bythe laboratory to ensure that any detections of TPH only included petroleumhydrocarbons. The silica gel clean-up method removes polar compounds in the sampleextract, allowing only non-polar petroleum based compounds to be analysed by the GasChromatograph - Flame Ionisation Detector (GC-FID).

Samples were placed in an ice-filled cooler and transferred to Australian LaboratoryServices (ALS) for analysis. This laboratory is NATA accredited for the analysesrequested.

Samples were analysed according to the schedule in Appendix B including the annualsuite of parameters.

4.2 Assessment criteria for water quality

Surface water quality data were assessed, in most cases; with respect to the NEPM (2013) with reference to the “Australian Water Quality Guidelines for Fresh and Marine Waters” (ANZECC/ARMCANZ, 2000a) default trigger values for:

Toxicants for the protection of aquatic ecosystems at the 99% level of protection (forheavy metals).


a. Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ARMCANZ, 2000), 99%Protection Level for freshwater and marine water.

b. All units in µg/L unless indicated.

c. ANZECC/ARMCANZ (2000) trigger value for physical/chemical stressors for NSW coastal rivers, slightlydisturbed ecosystems – Table 3.2.3.

d. ANZECC/ARMCANZ (2000) trigger value for physical/chemical stressors for NSW estuaries, slightly disturbedecosystems – Table 3.2.3.

e. These values are low reliability trigger values (ANZECC/ARMCANZ, 2000).

f. MHSPE (1994) Dutch Intervention Level for Mineral Oil in Groundwater.

g. ANZECC/ARMCANZ (2000a) guideline for protection of human consumers of aquatic food.

h. Australian Drinking Water Guidelines (NHMRC/NRMMC, 2011) health-based guideline.

i. MHSPE (1994) criteria adopted since the low reliability ANZECC/ARMCANZ (2000) criteria is below thelaboratory PQL.

j. Laboratory PQL exceeds adopted criteria.

k. The Australian Drinking Water Guideline has not been adopted due to the relatively large distances betweensurface water channels and groundwater pumping stations. The closest pumping station to any major surfacewater channel carrying stormwater from RAAF WLM is approximately 750 m up gradient.

l. Value for filterable reactive phosphorus.

m. These values are derived from the Minnesota Department of Health (MDH, 2007).

4.2.1 Site specific trigger values

Site specific trigger values (SSTV) were derived as part of the 2012 Annual Report on the basis of the ANZECC/ARMCANZ (2000a) procedure. The recommended process is to calculate a series of different percentiles for different parameters based on reference site data as follows:

For physicochemical parameters: 20th and/or 80th percentile.

For nutrients: 80th percentile.

At this stage, SSTV have been derived using water quality data from monitoring undertaken between December 2004 and December 2012 at three locations (F8, F9 and B5) within the Tilligerry Catchment by Port Stephens Council (PSC). PSC sampling locations F8 and F9 are situated within Tilligerry Creek, upstream of the point where Moors Drain discharges into Tilligerry Creek. They are therefore not considered to be directly affected by Defence’s activities at RAAF WLM and adequately characterise background conditions across the Tilligerry Creek Catchment.

Over five years of monitoring data collected weekly and/or fortnightly was available for pH, turbidity, Electrical Conductivity (EC), FC, TN and TP. SSTV for these parameters are outlined in Table 4-2. Data provided in the following table has been updated based on the re-derivation of SSTV in the 2012 Annual Report. SSTV are reviewed annually.

SSTV will be calculated for dissolved heavy metals when at least two years of data are available for locations F8 and F9.


5. Field and analytical results5.1 Field observations

Rainfall data obtained from the Bureau of Meteorology weather station located at RAAF WLM (Station No. 061078) indicated that 27 mm of rain fell during the three weeks prior to sampling with a further 17 mm of the total rain falling on the day of sampling.

5.2 Surface water quality

Surface water quality results for February 2014 are provided in Tables 2 to 3 in Appendix B. Data has been compared to the nominated default trigger values (assessment criteria,

Table 4-1) and exceedances have been highlighted.

Exceedances above nominated assessment criteria have been highlighted according to the key below (assessment criteria referred to as ‘guidelines’ in key). Changes in surface water quality over time have not specifically been assessed as part of this report.

Key: Exceedances categories highlighted as follows

within 1.1 times guideline concentrations

greater than 1.1 and up to 2.5 t imes guideline concentrations

greater than 2.5 and up to 10 times guideline concentrations

greater than 10 times guideline concentrations

below guideline concentrations

In order to determine changes in surface water quality over time, data for monitoring locations MD1 and DD1 have also been compared to ‘baseline’ concentrations. A baseline concentration has been calculated for each analyte for both MD1 and DD1 (where sufficient data exists) by taking the 80th percentile concentration of monthly results reported at these locations between May 2003 and November 2004. This period has been assumed to represent pre-redevelopment concentrations for RAAF WLM. The methodology for calculating baseline concentrations conforms to the ANZECC/ARMCANZ (2000a) procedure for establishing site-specific trigger values. Baseline concentrations are given in Tables 2 to 3 in Appendix B. Corresponding baseline concentrations over the same period are not available for locations F8 or F9.

Where the majority of results between May 2003 and November 2004 were reported as less than the laboratory Practical Quantitation Limit (PQL), the PQL was adopted as the baseline concentration. Analytes which were not monitored between May 2003 and November 2004 do not have baseline concentrations. The appropriateness of all baseline concentrations is reviewed annually.


6. Discussion of results6.1 Overview

The following discussion is based on data obtained from the February 2014 surface water monitoring round and is therefore relevant only for this point in time and subject to review in the next monitoring round. Trends in water quality data are assessed annually.

In the case where no additional action is required for a particular facility, this is not meant to imply that there are no contamination issues at this facility. Rather, it implies that the current actions should continue or previous recommendations should still be investigated.

The following tables should be read with consideration of the following notes:

For analytes with SSTVs, the greatest exceedance of the SSTV has been classified usingthe exceedance categories from reported in Section 5.2.

Results of analytes with concentrations marginally above criteria and/or marginally abovethe laboratory PQL that may be influenced by laboratory analysis precision error have notbeen reported in the exceedance tables or discussed. Precision limits were alsoconsidered when determining whether the concentrations were greater, below or withinbaseline concentrations.

For analyte exceedances below the baseline concentration, comments have not beenprovided for comparison with historical ranges.

N/A – indicates that baseline concentrations are not available for particular analytes atidentified monitoring locations. Where baselines are not available, concentrations havebeen compared to historical ranges.

Where increases in exceedance categories above baseline concentrations have beenreported, these have been provided as comments in the Table 6-1 to Table 6-5. Theabsence of these comments indicates that the reported concentrations were consistentwith or less than the baseline concentration (where applicable).

Where the duplicate sample exceeded the primary sample, the highest concentration hasbeen reported in the tables.

Refer to list of abbreviations for analyte abbreviations in the following tables.

6.2 Location MD1

All analyte concentrations were found either below laboratory PQLs and/or nominated trigger values, with the exception of the following outlined in Table 6-1 and Table 6-2.


7. ConclusionsGHD has undertaken quarterly water quality monitoring as part of the Surface Water Monitoring Program for RAAF WLM. Reported results have been compared to nominated trigger values, as well as baseline concentrations calculated from pre-redevelopment data and limited SSTV established from data provided by PSC.

There were several exceedances of the nominated assessment criteria, SSTVs and baseline criteria during this monitoring round with the most notable exceedances zinc during F-F sampling at MD1 and during F-F and F-U sampling at DD1. This will be monitored in subsequent rounds to identify whether there are any increasing trends.

Elevated heavy metals, nutrients and TSS were noted at all locations, in particular during F-F sampling and could be attributed to the lower rainfall in the months leading up to sampling. MD1 and DD1 during F-F sampling continued to report concentrations greater than non-event based monitoring indicating that previous non-event sampling was missing potential impacts occurring at F-F .Subsequent monitoring rounds will be required to identify whether the exceedances identified in February 2014 were isolated incidents or whether there are impacts occurring in surface water during F-F sampling that had previously been missed.

It is recommended to continue event based sampling in order to identify potential impacts and to identify any increasing trends.


8. LimitationsThis February 2014 Quarterly Monitoring Report (“Report”):

Has been prepared by GHD Pty Ltd (“GHD”) for the Department of Defence.

May only be used and relied on by the Department of Defence.

Must not be copied to, used by, or relied on by any person other than the Department ofDefence without the prior written consent of GHD and subject always to the nextparagraph.

May only be used for the purpose as stated in Section 1 of the Report (and must not beused for any other purpose).

GHD and its servants, employees and officers otherwise expressly disclaim responsibility to any person other than the Department of Defence arising from or in connection with this Report.

To the maximum extent permitted by law, all implied warranties and conditions in relation to the services provided by GHD and the Report are excluded unless they are expressly stated to apply in this Report.

The services undertaken by GHD in connection with preparing this Report:

Were limited to those specifically detailed in Section 3 of this Report.

Were undertaken in accordance with current profession practice and by reference torelevant environmental regulatory authority and industry standards, guidelines andassessment criteria in existence as at the date of this Report.

The opinions, conclusions and any recommendations in this Report are based on assumptions made by GHD when undertaking the services mentioned above and preparing the Report (“Assumptions”), as specified throughout this Report.

GHD expressly disclaims responsibility for any error in, or omission from, this Report arising from or in connection with any of the Assumptions being incorrect.

Subject to the paragraphs in this section of the Report, the opinions, conclusions and any recommendations in this Report are based on conditions encountered and information reviewed at the time of preparation of this Report and are relevant until such times as the site conditions or relevant legislations changes, at which time, GHD expressly disclaims responsibility for any error in, or omission from, this Report arising from or in connection with those opinions, conclusions and any recommendations.

No investigations have been undertaken into any off-site conditions, or whether any adjoining sites may have been impacted by contamination or other conditions originating from this site.

The opinions, conclusions and any recommendations in this Report are based on information obtained from, and testing undertaken at or in connection with, specific sampling points and may not fully represent the conditions that may be encountered across the site at other than these locations. Site conditions at other parts of the site may be different from the site conditions found at the specific sampling points.

GHD has considered and/or tested for only those chemicals specifically referred to in this Report and makes no statement or representation as to the existence (or otherwise) of any other chemicals.


Site conditions (including any the presence of hazardous substances and/or site contamination) may change after the date of this Report. GHD expressly disclaims responsibility:

Arising from, or in connection with, any change to the site conditions.

To update this Report if the site conditions change.

These Disclaimers should be read in conjunction with the entire Report and no excerpts are taken to be representative of the findings of this Report.


9. ReferencesANZECC/ARMCANZ (2000a). Australian and New Zealand Guidelines for Fresh and Marine Water Quality

ANZECC/ARMCANZ (2000b). Australian and New Zealand Guidelines for Water Quality Monitoring and Reporting

GHD (2012). Surface Water Quality Monitoring RAAF Base Williamtown, 2011 Annual Report, November 2012

GHD (2013). Surface Water Quality Monitoring RAAF Base Williamtown, 2012 Annual Report, April 2013

MDH (2007) Health Based Values for Perfluoroocane Sulfonate (PFOS), Minnesota Department of Health Memo from Helen Goeden, MDH Risk Assessment Unit, 26 February 2007

Ministry of Housing, Spatial Planning and Environment (MHSPE) (1994). Environmental Quality Objectives in the Netherlands - A review of environmental quality objectives and their policy framework in the Netherlands

NEPC (2013). National Environment Protection (Assessment of Site Contamination) Measure (NEPM), 1999 as amended by the National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1).

NHMRC/NRMMC (2011). Australian Drinking Water Guidelines 6. National Health and Medical Research Council/Natural Resource Management Ministerial Council


GHD | Report for Department of Defence - Surface Water Quality Monitoring RAAF Base Williamtown, 22/16319

Appendices

Appendix A – Figures


Table B-2 - Surface Water Quality Data for RAAF WLM, February 2013

Biological

Tem

pera

ture

pH EC DO

Red

ox P

oten

tial

C6

- C 9

Fra

ctio

n

C10

- C

14 F

ract

ion

Silic

a C

lean

up

C15

- C

28 F

ract

ion

Silic

a C

lean

up

C29

- C

36 F

ract

ion

Silic

a C

lean

up

C10

- C

36 (S

um o

f Tot

al)

C6

- C10

Fra

ctio

n

C6-

C10

less

BTE

X (F

1)

TRH

>C10

-C16

afte

r Sili

ca c

lean

up

>C10

- C

16 F

ract

ion

min

us N

apht

hale

ne (F

2)

TRH

>C16

-C34

afte

r Sili

ca C

lean

up

TRH

>C34

-C40

afte

r Sili

ca C

lean

up

TRH

>C10

- C

40 a

fter S

ilica

Cle

anup

(sum

)

Ben

zene

Ethy

lben

zene

Tolu

ene

Xyle

ne (m

& p

)

Xyle

ne (o

)

Xyle

ne T

otal

Nap

htha

lene

PFO

S

PFO

A

62

Fluo

rote

lom

er S

ulfo

nate

(62

FtS)

BO

D

Tota

l Sus

pend

ed S

olid

s

Turb

idity

Faec

al C

olifo

rm

Ars

enic

Cad

miu

m

Chr

omiu

m (I

II+VI

)

Cop

per

Lead

Mer

cury

Zinc

Am

mon

ia a

s N

Nitr

ate

(as

N)

Nitr

ite (a

s N

)

Nitr

ogen

(Tot

al O

xidi

sed)

Nitr

ogen

(Tot

al)

Kje

ldah

l Nitr

ogen

Tot

al

Phos

phor

us

Rea

ctiv

e Ph

osph

orus

as

P

°C pH units µS/cm mg/L mV µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L mg/L mg/L NTU CFU/100mL mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/LPQL 20 50 100 50 50 20 20 100 100 100 100 100 1 2 2 2 2 2 5 0.02 0 02 0.1 2 5 0.1 1 0.001 0.0001 0 001 0 001 0.001 0.0001 0.005 0.01 0.01 0.01 0.01 0.1 0.1 0.01 0.01SW Assessment Criteria x 1 600 0.3 0 3 6 6 14 0.0008 0.00006 0.0003 0 001 0.00006 0 0024 0.32 0.01 0.35 0.025 0 004SW Assessment Criteria x 1.1 660 0.33 0 33 6.6 6.6 15.4 0.00088 0.000066 0.00033 0.0011 0.000066 0 00264 0 352 0.011 0.385 0 0275 0.0044SW Assessment Criteria x 2.5 1500 0.75 0.75 15 15 35 0.002 0.00015 0.00075 0.0025 0.00015 0.006 0.8 0.025 0.875 0 0625 0.01SW Assessment Criteria x 10 6000 3 3 60 60 140 0.008 0.0006 0 003 0.01 0.0006 0.024 3.2 0.1 3.5 0.25 0.04Nominated Assessment Criteria 600 0.3 0 3 6 6 14 0.0008 0.00006 0.077 0.0003 0 001 0.00006 0 0024 0.32 0.01 0.35 0.025 0 004Site Specific Trigger Value 7.1-7.8 29,100 57.2 844 1.7 0.3

Field ID Sampled DateFirst Flush SamplingMD1 Baseline <20 <50 777 154 1090 19.2 12.2 104 0.21 1.63 1.568 0.101MD1 FF 20/02/2014 - - - - - - <50 240 80 320 - - <100 - 280 <100 280 - - - - - - - 2.68 0 06 <0.1 - 25 5.4 - <0.001 <0.0001 <0.001 0 003 <0.001 <0.0001 0.103 0.06 0.3 <0.01 0.3 0.5 0 2 0.2 <0.01DD1 Baseline <20 <50 <100 <50 <50 5 5.4 8 <0.01 0.552 0.555DD1 FF 20/02/2014 - - - - - - <50 <100 <50 <200 - - <100 - <100 <100 <100 - - - - - - - 6.33 0.13 <0.1 - 58 35 2 - <0.001 <0.0001 0.001 <0.001 <0.001 <0.0001 0.611 0.38 0.02 <0.01 0.02 1.8 1 8 0.09 <0.01Follow Up SamplingMD1 Baseline <20 <50 777 154 1090 19.2 12.2 104 0.21 1.63 1.568 0.101MD1 20/02/2014 28.6 6.26 211.6 4 27 90.4 <20 <50 <100 <50 <200 <20 <20 <100 <100 <100 <100 <100 <1 <2 <2 <2 <2 <2 <5 4.22 0 09 <0.1 <2 <5 1.8 14 <0.001 0.0002 <0.001 0 001 <0 001 <0.0001 0.076 0.13 0.12 <0.01 0.12 0.5 0.4 0.02 <0.01Q01 20/02/2014 - - - - - <20 <50 <100 <50 <200 <20 <20 <100 <100 <100 <100 <100 <1 <2 <2 <2 <2 <2 <5 4.39 0.1 <0.1 <2 <5 1.5 14 <0.001 0.0002 <0.001 0 002 <0.001 <0.0001 0.078 0.12 0.12 <0.01 0.12 0.5 0.4 <0.01 <0.01

RPD (%) - - - - - NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC 11 NC NC NC 18 0 NC 0 NC 67 NC NC 3 8 0 NC 0 0 0 67 NCDD1 Baseline <20 <50 <100 <50 <50 5 5.4 8 <0.01 0.552 0.555DD1 20/02/2014 29.2 5.68 239.9 4.79 132.6 <20 <50 <100 <50 <200 <20 <20 <100 <100 <100 <100 <100 <1 <2 <2 <2 <2 <2 <5 7.5 0 08 <0.1 <2 6 6 ~330 <0.001 <0.0001 <0.001 <0.001 <0.001 <0.0001 0.051 0.08 <0.01 <0.01 <0.01 0.4 0.4 <0.01 <0.01Tilligerry CreekF8 20/02/2014 29.5 6.84 10186 5 25 78.7 - - - - - - - - - - - - - - - - - - - - - - <2 <5 19 6 ~12000 0.002 <0.0001 <0.001 <0.001 <0.001 <0.0001 <0.005 1.08 0.05 0.09 0.14 1.5 1.4 0.07 <0.01F9 20/02/2014 28.2 7.26 6169 4 90 42.3 - - - - - - - - - - - - - - - - - - - - - - <2 20 6.6 680 0.002 0.0014 <0.001 0 006 0.008 <0.0001 0.144 0.02 <0.01 <0.01 <0.01 1 3 1 3 0.25 0.08

EC = Electrical ConductivityDO = Dissolved OxygenBOD = Biochemical Oxygen DemandTPH = Total Petroleum HydrocarbonsTRH = Total Recoverable HydrocarbonsPFOS = Perfluorooctyl AcidPFOA = Perfluorooctyl SulfonateNC = Not Caculated

Field Metals NutrientsInorganicsTPH - NEPM 1999 TRH - NEPM 2013 BTEXN PFOS

Summary SW data for WLM February 2014 , 6/05/2014

Spiked Samples: An authentic field sample is spiked by adding an aliquot of known concentration of the target analyte(s) prior to sample extraction and analysis. A spike documents the effect of the sample matrix on the extraction and analytical techniques.

Certified Reference Standards: A reference standard of known (certified) concentration is analysed along with a batch of samples. The Certified Reference Standard provides an indication of the analytical accuracy of the test method.

Surrogate Standard/Spikes: These are organic compounds which are similar to the analyte of interest in terms of chemical composition, extractability, and chromatographic conditions (retention time), but which are not normally found in environmental samples. These surrogate compounds are spiked into blanks, standards and samples submitted for organic analyses by gas-chromatographic techniques prior to sample extraction. They provide a means of checking that no gross errors have occurred during any stage of the test method leading to significant analyte loss.

Laboratory Blank: Usually an organic or aqueous solution that is as free as possible of analyte of interest to which is added all the reagents, in the same volume, as used in the preparation and subsequent analysis of the samples. The reagent blank is carried through the complete sample preparation procedure and contains the same reagent concentrations in the final solution as in the sample solution used for analysis. The reagent blank is used to correct for possible contamination resulting from the preparation or processing of the sample.

C.1.4 Laboratory QC assessment procedure

Assessment of laboratory QC was undertaken internally by the testing laboratory. Duplicates were assessed by calculating the Relative Percent Difference (RPD). Percent Recovery (PR) is used to assess spiked samples and surrogate standards. Acceptable values for RPD and PR can vary depending on the type of analyte tested, concentrations of analytes, and sample matrix.

Laboratory QC results were independently assessed and reviewed by GHD in addition to holding time compliance and frequency of quality control samples. Generally, the results indicated that the laboratory was achieving results within its acceptable limits.

Based on this, GHD considers that the QC performed by the laboratory is acceptable for the analysis requested.


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