Appendix A. Previous PCP and dioxin investigations

PCP investigations

Northland Regional Council (NRC)

In 1991 the NRC collected and analysed sediment samples from and adjacent to 13 sites. At seven of these sites surface water samples were also taken. Sediment at most of the sites showed PCP levels at or below the detection limit (2 mg/kg). One site had levels up to 1.0 mg/kg, another up to 1.7 mg/kg and a third up to 18 mg/kg. The latter also had PCP concentrations in water up to 20 mg/m³. Another site had a PCP concentration in water of 2 mg/m³; all other samples were at or below the detection limit (1 mg/m³).

In 1994 preliminary site investigations were undertaken by the NRC at six sites. These showed no, or low levels of, PCP in the soil samples and at one site a low level in groundwater.

Auckland Regional Council (ARC)

In 1992/93 the ARC collected and analysed samples from drainage courses on or adjacent to a number of sites. Sediment/soil from six of the sites showed maximum PCP levels ranging from 0.8 to 11.3 mg/kg. One site also had a PCP concentration of 0.008 mg/m³ in stormwater run-off.

Environment Waikato (EW)

EW has not undertaken a specific programme of PCP investigations.

Environment Bay of Plenty (EBOP)

EBOP has not undertaken a specific programme of PCP investigation. However, the site which was the major user of PCP in the country (Waipa) was subject to investigation (for both PCP and dioxin contamination) by the National Task Group in 1992 (Ministry for the Environment and Department of Health, 1992). Significant levels of contamination were found in the soils on site: in groundwater and receiving environment water, sediment and biota. Further investigations and monitoring have been undertaken by the site owners and by the council. A treatment system has been installed for the interception and clean-up of the contaminated groundwater.

Hawke’s Bay Regional Council (HBRC)

HBRC has not undertaken a specific programme of PCP investigation.

Gisborne District Council (GDC)

GDC has not undertaken a specific programme of PCP investigation

Taranaki Regional Council (TRC)

In 1994 the TRC undertook investigations at 33 current and past timber-processing sites with regard to possible discharges from these sites into groundwater or surface water. Samples were taken of soils, sludges, sediments, discharges and receiving waters. No PCP was found in any of the water samples (discharges or receiving environment). Maximum concentrations of PCP found in soils (or sludges where stormwater pools) on 11 sites ranged from 0.1 to 14 mg/kg and in sediments on five sites ranged from 0.2 to 0.5 mg/kg.

Manawatu–Wanganui Regional Council (Horizons-MW)

Horizons-MW has not undertaken a specific programme of PCP investigation.

Wellington Regional Council (WRC)

In 1998 a review was conducted for the WRC on 24 timber treatment sites and 17 sawmill sites. This indicated six priority sites for follow-up investigation. An investigation was undertaken in 1999 to assess the off-site effects of discharges from these sites. No PCP was found in the sediment of samples collected around the periphery at five of the sites. At the remaining site a maximum PCP concentration of 0.3 mg/kg was found. At four of the sites maximum PCP concentrations in surface water run-off ranged from 0.00005 to 0.0117 mg/L.

Nelson City Council (NCC)

At NCC’s request, a number of the sites have been investigated by the site owners. NCC reports that at two of the sites very low levels of PCP were detected, and at a third the levels were at an acceptable level for its ongoing use as a sawmill / timber treatment site.

Tasman District Council (TDC)

TDC has not undertaken a specific programme of PCP investigation.

Marlborough District Council (MDC)

MDC has not undertaken a specific programme of PCP investigation.

West Coast Regional Council (WCRC)

WCRC has not undertaken a specific programme of PCP investigation.

Canterbury Regional Council (ECan)

ECan had PCP investigations undertaken at 18 sites in 1994. At three of the sites no PCP was found. On the remaining sites the maximum PCP concentration found in soil generally ranged from 1.0 to 4,500 mg/kg, although at one site a concentration of 25,000 mg/kg was found in sawdust beneath an antisapstain dip tank. Previous work for the council had provided estimates of PCP use at many of these sites. There was no correlation between quantity of PCP estimated to have been used and levels of PCP contamination found.

At about the same time a number of investigations were carried out at the former Forest Service Hanmer Springs site (PCP-in-oil operation). The maximum PCP concentration found in soil in the vicinity of the treatment plant was 830 mg/kg and in the waste disposal area 770 mg/kg. One hot spot (possibly disposed waste) had a PCP concentration of 5,700 mg/kg. The maximum PCP concentration in groundwater was 40 mg/L and in downstream surface water 0.08 mg/L. Results from later investigations were consistent with these results but showed that PCP contamination at one location extended to a depth of approximately 4 metres, a maximum groundwater concentration of 100 mg/L and downstream surface water concentration of 0.007 mg/L.

Otago Regional Council (ORC)

In 1995 the ORC had PCP investigations undertaken at four sites. Maximum PCP concentrations found ranged from less than 0.1 to 12,000 mg/kg in soil, and up to 49 g/m³ and 0.8 g/m³ in groundwater and stormwater respectively. Later investigations or monitoring by the ORC have shown low levels of soil or groundwater contamination at a further four sites.

Southland Regional Council (SRC)

SRC has not undertaken a specific programme of PCP investigation.

Dioxin investigations

A number of investigations of dioxin contamination have been undertaken by site owners. However, as mentioned, the results of these investigations are not publicly available. A limited number of sites have been investigated by central or local government. The most comprehensive investigation was carried out by the National Task Group (Ministry for the Environment and Department of Health, 1992). As described above for PCP, dioxin contamination was found in soils, groundwater and surface waters, including sediment and biota. Dioxin contamination of soils associated with the PCP-in-oil process were in the order of 20 µg I-TEQ/kg, and for soils associated with green chain and boric dip antisapstain operations the contamination ranged from 0.1 to 3.1 µg I-TEQ/kg. One hot spot beneath the mix room had a concentration of 3,300 µg I-TEQ/kg. (All TEQ values are based on full congener analysis.)

At the Hanmer Springs site the maximum dioxin contamination found in soil was 3.5µg I-TEQ/kg (full congener analysis). When the plant was decommissioned, a surface layer (250-300 mm) was scraped off the treatment plant and log storage area and disposed of at an unknown location. There is also a plume of PCP/dioxin contaminated oil on the groundwater surface at the site. The dioxin concentration in the oil was measured to be 159 µg I-TEQ/kg.

A preliminary investigation was also undertaken at three sites in the Canterbury region classified as small NaPCP users. Dioxin concentrations in soils on these sites ranged from 0.5 to 4.2 µg I-TEQ/kg.

The sources for this information are as follows:

• CMPS&F 1995a. Audit of Timber Treatment Sites – Overview Report. Canterbury Regional Council: Christchurch

• CMPS&F 1995b. Timber Site Audit Project – Environmental Site Assessment, Site A. Canterbury Regional Council: Christchurch

• CMPS&F 1995c. Timber Site Audit Project – Environmental Site Assessment, Site B. Canterbury Regional Council: Christchurch

• CMPS&F 1995d. Timber Site Audit Project – Environmental Site Assessment, Site C. Canterbury Regional Council: Christchurch.

Level of confidence in site contamination characterisation

PCP

In many of the regions the emphasis has been on assessing the extent of PCP migration from the site or the ongoing potential for this to occur. For some councils, the assessment of the potential for ongoing migration has focused on those areas of the site most likely to have higher levels of residual contamination.

With the exception of the Canterbury region, there have been few comprehensive council investigations of PCP contamination at sawmill and timber treatment sites. Therefore the level of confidence that can be placed on PCP contamination characterisation (on the public record) is relatively low. However, a significant number of PCP investigations have been undertaken by site owners and much of this information has been provided to councils in association with proposed remedial works, consent applications or monitoring. These councils will have a higher level of confidence in the characterisation of PCP contamination at sites under their jurisdiction.

Dioxins

The two sites that used PCP in oil (discussed above) have been thoroughly investigated and the dioxin contamination has been well characterised. Given the preliminary nature of the investigation at the three small Canterbury sites, there is only a low level of confidence in the characterisation of dioxin contamination associated with NaPCP antisapstain treatment. As with PCP (see above), there have been a number of dioxin investigations undertaken by site owners and therefore some councils will have a higher level of confidence in the characterisation of dioxin contamination at sites under their jurisdiction.