❓ A WA parliamentary question seeks a detailed breakdown of costs associated with a new wetland in Canning River Regional Park, research on an algal curtain in Tranby Lake, and the potential cost of dredging the lake. The answer provides cost breakdowns, research status, and limitations of the algal curtain.
AnsweredQoN 2858Legislative Assembly
QuestionView source ↗
(1) What are the various components of the $400,000 cost of the new wetland in the Canning River Regional Park mentioned on page 1 of the April 2004 RiverView newsletter published by the Swan River Trust?
(2) Specifically, what is the cost of the 60,000 native plants to be planted into the wetland and at what planting density will these plants be placed?
(3) What research has been carried out into the effectiveness of the floating algal curtain described in the page 4 article of the same newsletter?
(4) Who has conducted this research, where have the research results been published and what was the total cost of this research project if it was carried out by a State Government agency?
(5) What would be the cost of dredging or otherwise removing the nutrient-rich sediment at the base of Tranby Lake and safely disposing of it?
(6) Does the floating algal curtain prevent dissolved nutrients from leaving Tranby Lake, recognising that much of the nutrients contained with the algae will dissolve in the lake’s water as the algae die and decompose?
(2) Specifically, what is the cost of the 60,000 native plants to be planted into the wetland and at what planting density will these plants be placed?
(3) What research has been carried out into the effectiveness of the floating algal curtain described in the page 4 article of the same newsletter?
(4) Who has conducted this research, where have the research results been published and what was the total cost of this research project if it was carried out by a State Government agency?
(5) What would be the cost of dredging or otherwise removing the nutrient-rich sediment at the base of Tranby Lake and safely disposing of it?
(6) Does the floating algal curtain prevent dissolved nutrients from leaving Tranby Lake, recognising that much of the nutrients contained with the algae will dissolve in the lake’s water as the algae die and decompose?
AnswerView source ↗
Answered
17 August 2004
Responded by
Minister for the Environment
Response time
77 days
(1) The Swan River Trust is contributing $322,598 to a partnership with City of Canning for initial construction and planting. The balance is for the concept design ($20,000), detailed engineering drawings ($10,000), a landscape plan ($7,000), a maintenance plan ($7,000), indigenous consultation ($1,800), gathering of baseline environmental data ($24,000) and other sundry expenses.
(2) Wetland plants will be purchased through the City of Canning partnership and will cost approximately $53,000. The sumpland will be planted at densities ranging from 3 to 4 plants per m2. In the floodplain, shrubs will be planted at a density of 1 to 2 per m2, trees at 1 to 10 per m2 and herbs at 3 per m2.
(3) Research on the effectiveness of the Tranby Lake algal curtain is continuing. Its purpose is to prevent scums from algal blooms, which are common in the lake, from being flushed into the Swan River. Due to the dry summer, lake water levels are below the outlet and the efficacy of the curtain cannot be tested until levels increase with the winter rains.
Background surveys, including lake bathymetry and nutrient concentrations in the lake and its sediments have been undertaken.
(4) The City of Bayswater assessed the sewage pipe referred to in (3). The Department of Environment has carried out all other work on behalf of the Swan River Trust. At this early stage in the project, publication of data is not warranted. The cost of curtain installation and background surveys is $2,021. Officer time for installation, project management and monitoring is approximately $5,000. The algal curtain has been recycled from a completed project on the Vasse River.
(5) The cost of dredging Tranby Lake is not accurately known. It is understood that several years ago the City of Bayswater obtained an approximate quotation for dredging the lake, that was in the order of $50,000. This did not include a number of significant aspects such as the disposal of the dredge spoil.
(6) The algal curtain is not intended to prevent dissolved nutrients from leaving the lake. Insufficient data is available to comment on the cycling of nutrients within Tranby Lake.
(2) Wetland plants will be purchased through the City of Canning partnership and will cost approximately $53,000. The sumpland will be planted at densities ranging from 3 to 4 plants per m2. In the floodplain, shrubs will be planted at a density of 1 to 2 per m2, trees at 1 to 10 per m2 and herbs at 3 per m2.
(3) Research on the effectiveness of the Tranby Lake algal curtain is continuing. Its purpose is to prevent scums from algal blooms, which are common in the lake, from being flushed into the Swan River. Due to the dry summer, lake water levels are below the outlet and the efficacy of the curtain cannot be tested until levels increase with the winter rains.
Background surveys, including lake bathymetry and nutrient concentrations in the lake and its sediments have been undertaken.
(4) The City of Bayswater assessed the sewage pipe referred to in (3). The Department of Environment has carried out all other work on behalf of the Swan River Trust. At this early stage in the project, publication of data is not warranted. The cost of curtain installation and background surveys is $2,021. Officer time for installation, project management and monitoring is approximately $5,000. The algal curtain has been recycled from a completed project on the Vasse River.
(5) The cost of dredging Tranby Lake is not accurately known. It is understood that several years ago the City of Bayswater obtained an approximate quotation for dredging the lake, that was in the order of $50,000. This did not include a number of significant aspects such as the disposal of the dredge spoil.
(6) The algal curtain is not intended to prevent dissolved nutrients from leaving the lake. Insufficient data is available to comment on the cycling of nutrients within Tranby Lake.
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