Tokoroa Wastewater Treatment Plant Upgrade South Waikato District Council

• Four Treatment Plants • Tirau Consent Approved Late 2020 • Putāruru Consent Approved Late 2020 • Arapuni Consent Expired 1 July 2020 • Tokoroa Consent Expired 31 Dec 2011

• Tokoroa and Arapuni Consent lodged in 2018 • Notified (likely), New NPS, and NES Tokoroa Wastewater Treatment Plant Existing • Digester, Consolidation, Mechanical Biosolids • Step Screen • 3 Clarifiers • 2 Trickling Filters • FAST 1st in NZ • Drum Filter • UV Disinfection

• SWDC inherited the Arapuni Treatment plant from ECNZ in 1993

• Discharge to ground infiltration on west side of Waikato River

• Imhoff tank was built in the 1930’s

• Upgraded in 1982, sand beds added • Tirau Plant. • It was upgraded in 2005 • Was first membrane treatment in NZ

Phasing of Upgrades

CAPEX ($000) INCREASED OPEX

Year Proposed Staging for Discussion with WRC

1 2019 Wetlands for Tirau $ 418 $ 572 $ 60,600 $ 82,800

2 2020 Sludge Upgrade at Tokoroa - Enabling works for TN and TP upgrades $ 4,469 $ 6,115 $ 183,200 $ 250,700

2 2020 Putāruru Sludge Upgrade (additional centrifuge at Tokoroa) $ 2,466 $ 3,375 $ 233,000 $ 318,800

2 2020 Wetlands for Putāruru $ 599 $ 820 $ 251,400 $ 343,900

3 2021 Wetlands for Tokoroa $ 1,117 $ 1,529 $ 280,000 $ 383,000

4 2022 Tokoroa - TP Upgrade $ 631,200 $ 863,600

8 2026 Putaruru TN Upgrade $ 5,421 $ 7,418 $ 906,100 $ 1,239,700

12 2030 Arapuni $ 1,225 $ 1,676 $ 916,100 $ 1,254,700

14 2032 Tokoroa - TN Upgrade $ 3,250 $ 4,447 $ 1,236,500 $ 1,693,200

22 2040 Putaruru TP Upgrade $ 164 $ 225 $ 1,320,100 $ 1,807,600

27 2045 Tirau TN and TP Upgrade $ 2,088 $ 2,857 $ 1,398,800 $ 1,929,000

35 2053 Consent Expiry

$ 21,217 $ 29,034 $ 1,398,800 $ 1,929,000

Tokoroa Wastewater Treatment Plant Upgrades over the years

Tokoroa Wastewater Treatment Plant • 1958 • Initially a primary Dortmund, followed by two low rate biological filters and a final Dortmund sedimentation tank. • Sludge digestion of settled and filtered solids was installed to enable sludge to be processed for land application •

Tokoroa Wastewater Treatment Plant • 1967 • A second plant was commissioned to run parallel to the original, dividing the waste between the two. • Upgrade included addition of primary treatment, two high rate biological filters, secondary settlement. • Sludge now treated in a new heated digester and existing used as a cold consolidating digester.

Tokoroa Wastewater Treatment Plant • 1987 • Upgrades included changing existing low rate filters to high rate filters • Pre treatment was installed • The existing 1967 plant was decomissioned

Tokoroa Wastewater Treatment Plant • 1993 • Decommissioned primary clarifier recommissioned as an intermediate clarifier and plumbed in between the trickling filters.

Tokoroa Wastewater Treatment Plant • 1997 • Pre screening • Tertiary Treatment upgrades • FAST • Sand filtration • UV Disinfection

Tokoroa Wastewater Treatment Plant • 2013 • Biosolids Upgrade • Decommission existing drying beds • New Mechanical dewatering system • Centrifuge and Screw Conveyor • Polymer dosing • Odour control

Tokoroa Wastewater Treatment Plant Upgrade Today Tokoroa Wastewater Treatment Plant Upgrades • 2020 • Flare - Complete • New Digester & Ancillary Plant – Construction 60% complete • Site Visit this afternoon • Contract NZS 3916 Design and Build • Mott MacDonald & Spartan Construction

Tokoroa Wastewater Treatment Plant • 2021 • Bandscreen • Tradewaste / Septage • Blowers 3 Waters Reform Funding

• Application prepared with recommendation to bring forward planned upgrade in the LTP 2028 to 2022 to improve Total Nitrogen discharges (TN). • Denitrification Stage 1 of a process to improve water effluent quality to the receiving environment. • Receiving environment will change from a freshwater receiving environment to a Cultural Wetland to be constructed by 2023.

Tokoroa Wastewater Treatment Plant

• 2022 • Denitrification Project • Sampling (Pilot Complete) ECI • BIOWIN Model to determine best solution • Basis of Design to be novated • Design and Build Contract NZS 3916 • Completion March 2022 • Watch this space