Residential Soil Quality the real risk. Murray Wallis Carole Lee

Transcription

1 Residential Soil Quality the real risk Murray Wallis Carole Lee

2 Auckland horticultural sites

3 The Real Risk.. Has undue emphasis been placed on horticultural sites in Auckland? Is the cleanup cost for horticultural sites justified from a health risk perspective? Does our current approach to regulation best address the level of health risk posed?

4 This presentation What does the data set for horticultural sites inform us with respect to health risk? What are the costs involved? What are the known risks posed by lead based paint in New Zealand? Suggestions for improved regulation.

5 Database for Horticultural sites Original thesis data from Sally Gaw (2002) Residential site investigations in Waitakere City; data from other Auckland URS investigations Gaw et al. (2006) Science of the Total Environment

6 Health Risk Criteria Parameter Arsenic Copper Lead Total DDT isomers Health Risk Criteria Source Timber Treatment Guidelines Residential (10% produce consumption) Timber Treatment Guidelines Residential (10% produce consumption) Cavanagh, 2004, Review of soil acceptance criteria for lead. (10% produce consumption) Sheep Dip Guidelines Standard residential (50% produce consumption)

7 DDT in Auckland Soils (Gaw thesis 2002) Health Risk Guideline 28 mg/kg [MfE 2006 Sheep Dip Guidelines] Land use Minimum Maximum Median Glasshouses < Market Gardens Multi-use use < Orchards < Vineyards < Overall <

8 DDT in Auckland Soils (Gaw thesis 2002) Health Risk Guideline 28 mg/kg [MfE 2006 Sheep Dip Guidelines] Land use Minimum Maximum Median Glasshouses < Market Gardens Multi-use use < Orchards < Vineyards < Overall <

9 Lead in Auckland Soils Gaw thesis (2002) Health Risk Guideline 300mg/kg Land use Minimum Maximum Median Glasshouses Market Gardens Multi-use use Orchards Vineyards Overall

10 Lead in Auckland Soils Gaw thesis (2002) Health Risk Guideline 300mg/kg Land use Minimum Maximum Median Glasshouses Market Gardens Multi-use use Orchards Vineyards Overall

11 Data from 22 sites 164 soil samples NZ Health Risk Criteria Min Max Median orchards, vineyards, glass houses, market garden Majority of samples taken at <150mm depth Residential land use guidelines assuming 10% home grown produce consumption (As, Cu, Pb) and 50% for DDT derivation Arsenic Copper Lead Total DDT isomers <

12 Total DDT Isomers Source: database of horticultural soils (22 sites) Total DDT Isomers Min <0.06 mg/kg Max 57 mg/kg Median 0.07 mg/kg Mean 2.21mg/kg Total DDT mg/kg Total DDT Isomers Health Risk Guideline Sample

13 Total Lead Source: database of horticultural soils (22 sites) Lead Lead mg/kg Min 4 mg/kg Max 342 mg/kg Median 42 mg/kg Mean 57 mg/kg Pb Health Risk Criteria ARC Background Sample

14 Gaw et al. (Science of the Total Environment 2006) Market Garden Orchard Vineyard Grazing Contaminant of concern Health risk guideline Min Max Median Min Max Median Min Max Median Min Max Median Arsenic 30 mg/kg Copper 370 mg/kg Lead 300 mg/kg Total DDT isomers 28 mg/kg < <

15 Gaw et al. (Science of the Total Environment 2006) Market Garden Orchard Vineyard Grazing Contaminant of concern Health risk guideline Min Max Median Min Max Median Min Max Median Min Max Median Arsenic 30 mg/kg Copper 370 mg/kg Lead 300 mg/kg Total DDT isomers 28 mg/kg < <

16 Discussion of data Median concentrations are low, and below health risk guideline criteria. Most significant concentrations appear to be on orchard sites. Results showing isolated hotspots rather than a significant risk over the entire site. Site specific environmental consideration This justifies site investigation and careful sampling design. Does not favour compositing.

17 Remediation costs - Case study 0.72 ha glasshouse site in Auckland Subdivided into 14 sections Large topsoil excess

18 Remediation cost 72 Sampling locations on this site Investigations, RAP and validation cost $27,000

19 Residential development- the reality Remediation costs dominated by cost of landfill disposal Marginal cost between landfill (say $70/ t gate) and cleanfill or managed fill (say $14/ t at gate) Case Study 1500 t topsoil disposal $84,000 penalty (plus extra haulage costs) Cleanfill and managed fill criteria are more stringent than current residential criteria

20 Lead based paint in residential soil Reeves et al Analysis of Lead in Blood, Paint, Soil and House Dust for the Assessment of Human Lead Exposure in Auckland. NZ Journal of Science Vol 25: URS case study at a play centre Ministry of Health 1998 The Environmental Case Management of Lead Exposed Persons

21 Reeves et al Lead analysis in exterior house paint, soil, household dust, blood lead of children aged 1 3 years from 4 suburban areas House ages in each area: new/ y/ y/ y at the time of testing n = 37 to 72 children in each area 50 g soil samples from 0 50 mm depth in area where child usually played (n = 32 to 56 in each area) Flame AA analysis of soil following sequential nitric/ HCl digestion

22 Mean Lead concentrations *P<0.05;**P<0.01;***P<0.001 Area 4 Area 3 Area 2 Area 1 (New) (20 30 y) (40 60 y) (80 90 y) Soil (mg/kg) *** 592*** 842*** Paint (%) * 3.1*** 3.6*** Dust *** (µg/sq ft) Children s whole blood (µmol/l) ** 0.70*** 0.90***

23 Mean Lead concentrations *P<0.05;**P<0.01;***P<0.001 Area 4 Area 3 Area 2 Area 1 (New) (20 30 y) (40 60 y) (80 90 y) Soil (mg/kg) *** 592*** 842*** Paint (%) * 3.1*** 3.6*** Dust *** (µg/sq ft) Children s whole blood (µmol/l) ** 0.70*** 0.90***

24 Children's Mean Whole Blood Lead 1 Mean Whole Blood Lead (umol/l) Children s whole blood (µmol/l) Notifiable 15 µg/dl Target 10 µg/dl Age of Residence

25 URS Lead Paint Case Study Investigation initiated as property had been used as a play centre. Buildings on site were estimated to have been constructed around the 1960 s as a residential property and comprised a painted weatherboard construction. 12 shallow soil samples collected from distances of approximately 1m, 5m and 10m from the main building on site. Samples composited to keep costs down Analysed for lead only

26 URS Lead Paint Case Study

27 Lead Concentrations vs Distance from Building Lead (mg/kg) Distance (m)

28 NZ MoH Guideline (1998) The MoH Guideline quotes typical urban soil background levels of mg/kg (no reference provided) This range underestimates the situation in older suburbs MoH did not refer to the Reeves study In 1984 it was estimated that 251,000 NZ houses have leadbased paint. Approx 5,000 of those houses are renovated each year

29 Has undue emphasis been placed on horticultural sites in Auckland? YES based on relative health risks Is the cleanup cost for horticultural sites with trace soil contaminants justified? Investigation justified to locate any hot spots Need to rationalise Cleanfill standards with riskbased site acceptance criteria Does our current approach to contaminated sites regulation best address the level of risk posed? NO need for clarity and consistency (landuse vs disposal) Need for equitable management of hazardous activities and industries

30 Questions