Wagga Wagga Gasworks Remediation

Project Details

Client: Wagga Wagga City Council
Timeframe: 2 years
Location: Wagga Wagga, NSW

Enviropacific were engaged to remediate the former Gasworks located immediately adjacent to the Murrumbidgee River in the heart of the city of Wagga Wagga. Remediation excavation works were required to extend to a depth of 10m below the existing ground level. Due to the proximity of the works to the river and the history of flooding in the area, a water treatment plant (WTP) was designed, constructed and operated as part of the remediation works.

The system was designed to allow ability to dewater the excavation and treat the contaminated groundwater at a rate of 10 L/s. The water was treated to meet strict Environmental Protection License (EPL) conditions, based on the ANZECC 95% protection levels for a freshwater ecosystem. Treated water was discharged to storm water and the Murrumbidgee River under the EPL.

Further works involved extensive excavation to remove contaminated materials from the site. A volume of 8,000m3 of coal tar and impacted soils were removed during bulk excavation works before being transported to a licensed treatment facility. The Murrumbidgee river runs directly adjacent to the site and its man-made levee bank had been dual use; its primary purpose to prevent flooding of the township and secondly as a a barrier to offsite contaminant migration. Enviropacific installed a Cutter Soil Mixer Wall (CSM) to protect the structural integrity of the flood levee bank and buildings directly adjacent to the excavation.

Enviropacific also actively assisted WWCC with its comprehensive community consultation program.

Summary

  • Design, construct and operate WTP of dewatering the excavation at over 10 L/s to cope with rainfall events and influence from the river level
  • EPL license obtained to allow discharge to stormwater
  • Treatment of highly contaminated groundwater, TSS, PAHs, TPH, BTEX, phenol, cyanide and ammonia to meet strict ANZECC 95% discharge criteria
  • Treated water was stored in a 100,000 L tank for validation
  • WTP footprint 900 m2
  • Skid mounted operations unit to ensure rapid site establishment

Skid mounted operations unit to ensure rapid site establishment

Facts

900 m2

WTP footprint

ANZECC 95%

discharge criteria