Various locations across the Clutha District

Application No. RM24.297

Clutha District Council (CDC) operates 11 wastewater treatment plants (WWTPs) covered by a total of 13 consents. Formal compliance investigations were undertaken by the Consent Authority on all 11 WWTPs in late 2019/early 2020. The Consent Authority’s investigation found that all 11 sites were poorly maintained and in breach of existing resource consent conditions. However, enforcement action centred around the operations of the 5 treatment plants at Lawrence, Tapanui, Kaka Point, Owaka and Stirling. Wastewater at these 5 sites is treated by a Biofiltro sewage treatment plant. The Biofiltro treatment system consists of a raised aerated bed of sawdust on rock fill over which the effluent is distributed. The sawdust is populated with worms and bacteria. The effluent is treated in the bed by direct bacterial action, with the worms consuming the bacterial residues. The effluent is collected in the base of the bed and discharged through a single drain to a UV treatment system. The UV chamber provides tertiary treatment. Once treated, the effluent is discharged.

The enforcement action led to court proceedings against CDC and City Care Ltd (CCL), who were contracted to manage the plants on behalf of CDC. Following charges being laid by the Consent Authority, the CDC pleaded guilty and were sentenced at the District Court in Dunedin. CCL however pleaded not guilty to all charges and Court proceedings against CCL were heard in court in late 2022. On 11 August 2023 CCL was convicted of all charges.

During the trial, Judge Dwyer made specific reference to the interpretation of Condition 6(b) of the relevant resource consents in the decision and rulings document and recommended a review:

‘‘Condition 6(b) does not specify a method for calculating that 90th percentile. For conditions of this kind to work properly the means of calculating the 90th percentile must be adequately defined in those conditions. Condition 6(b) fails to do that and should be reviewed if the WWTPs are to continue operating under their present consents.”

Therefore, all 90th percentile limits under the current discharge consents for the 5 plants at Lawrence, Tapanui, Kaka Point, Owaka and Stirling are currently unenforceable.

Another condition which impacts the 90th percentile calculation is the current allowance in Condition 6(d) for CDC to undertake resamples of the final effluent following a non-compliant result:

6d)     The consent holder shall also arrange for resampling/retesting of the discharge parameter(s) in breach of the consent limits (within 7 days of receiving any results that exceed the values set by Condition 6(b)) and forward the results to the Consent Authority upon receipt.”

It had been previously recognised by the Consent Authority that condition 6(d) is unclear in specifying how resample results should be included (or excluded) in the 90th percentile calculation.

Consequently, the Consent Authority served notice on CDC on 12 March 2024 of its intention to review conditions 6(b) and 6(d) of the relevant resource consents, being 2005.246, 2008.308, 2005.193, 2008.690, and 2003.680, under Section 128 of the Resource Management Act 1991. The review is a discretionary activity under Section 130(3) of the RMA.

2003.680

2005.193

2005.246

2008.308

2008.690

Ōwaka River, approximately 475 metres upstream of the intersection of Owaka Highway and Duttons Road, Owaka

True right bank of the Matau branch of the Clutha River/Mata-Au, approximately 390 metres south southeast of the intersection of the Kaitangata Highway and Riverbank Road, Stirling

True left bank of the Pomahaka River, approximately 100 metres south of the intersection of Seddon Hill Road and Beatties Road, Tapanui, Clutha District

True left bank of Tuapeka Creek, approximately 680 metres downstream of the Gabriels Gully Road bridge, Lawrence

Pacific Ocean, approximately 265 metres northeast of the intersection of Kaka Point Road and Selsea Street, Kaka Point, South Otago

Sections 3-5 SO 22858

Crown Land River Bed, adjacent to Pt Sec 8 Blk XII North Molyneux SD

Crown Land River Bed adjacent to Lot 1 DP 3133

Pt Sec 7 Blk XX Tuapeka East SD

Crown Land Sea Bed

CDC Notification And 104 Decision Report 11 Jun 24

Discharge Permit 2003.680.V1

Discharge Permit 2005.193.V1

Discharge Permit 2005.246.V1

Discharge Permit 2008.308.V1

Discharge Permit 2008.690.V1