Phoslock Treatment Trial – Lyndhurst Place Lake

Lyndhurst-Place-Lake

Project Details

The waterbody has a natural groundwater connection due to the low groundwater table. The lake is not supplied with any further groundwater via a bore system. There are four storm water inlets connected to the waterbody, which provide annual stormwater from residential areas and parks runoff. The waterbody has no aerators or active mixing. Ongoing water quality monitoring reports that the water is consistently high in nutrients.

WSUD Category: Wetland/lake algae management

CriteriaInformation
Development Type:Public Open Space
Function/Driver:Water quality
Government Area:City of Mandurah
Site Context:Shallow groundwater
Year Completed:2019

Type of wetland

Constructed – Urbanised

Description of the wetland management issue

  • The waterbody has a natural groundwater connection due to the low groundwater table.
  • The lake is not supplied with any further groundwater via a bore system.
  • There are four storm water inlets connected to the waterbody, which provide annual stormwater from residential areas and parks runoff.
  • The waterbody has no aerators or active mixing.
  • Ongoing water quality monitoring reports that the water is consistently high in nutrients.

Treatment trialed

  • Name of treatment: Phoslock
  • Quantity used: 2,367 kg
  • Method of application: Mobile shore-based application equipment.
  • Is there any known scientific research supporting its effectiveness? Yes. Proposal for Phoslock treatment of Lyndhurst Place Lake Mandurah, Report, Phoslock Environmental Technologies.

Date(s) of treatment

27/05/2019 one-off application

Outcome of treatment

  • Visual observations: Water column seems clearer.
  • Have water parameters specific to the treatment claims been measured before and after application? Yes. “Lyndhurst Place Lake Quarterly Health Check Report, EcoAdvise, August 2019″ (available upon request).
  • Water testing was carried out on the 12/06/2019 after the first major winter rainfall event. Further regular quarterly testing was carried out on the 8/08/2019.
  • Phoslock treatment reduced the TP concentration in the water considerably, by 91% after two weeks and by 75 % after three months. Also, Phoslock treatment has helped to drop the EC or TDS levels in water and show a 50% reduction in Biochemical Oxygen Demand (BOD) levels after 3 months. Reduction in BOD could be helpul in maintaining DO levels in water, which is good for this lake as there is no active aeration system installed.
  • Although the TP level dropped post Phoslock treatment, TN and TP levels remained high enough for the lake to be considered eutrophic

 

Contact Officer:  Tanith McCaw and Dale Robinson

Email: [email protected] and [email protected]