Surface water and groundwater

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6. Surface water and groundwater - Department of Planning and Community Development The Minister for Planning has issued Terms of Reference, under which the Assessment Committee will assess the CIS and submissions in response.

Extract: (7) Terms of Reference: Conduct a Public Hearing, in accordance with Division 2 of Part 8 of the Act, to hear properly made submissions confined to the following matters.

(7) (f) Whether the impacts of the project on surface and ground waters have been appropriately addressed.


Contents

[edit] EWL CIS documents for reference

  • Appendix A Existing flooding overlays
    • Precinct 1 – Hoddle Street (Eastern Portal) – Figure 1 to Figure 4
    • Precinct 2 – Alexandra Parade (Tunnel)– Figure 5 to Figure 8
    • Precinct 3 – Royal Park (Western Portal) – Figure 9 to Figure 15
    • Precinct 4 – CityLink – Figure 16 to Figure 21
    • Precinct 5 – Port Connection – Figure 22 to Figure 28


All CIS documents

[edit] Extract - Overview

Potential impacts to groundwater arise largely from altering groundwater levels, with the greatest risks likely to occur during construction, mostly due to dewatering activities required to create dry construction areas. There are potentially three broad risks to the groundwater environment that extend across precinct boundaries: the ‘damming’ effect caused by the project’s twin tunnels (which run directly across the general north-south regional groundwater flow); the dislocation and/or interception of contaminated groundwater; and subsidence caused by changes to groundwater levels during the construction of the tunnel and portals. These risks are not consistent within the project boundary and options to manage them would need to be considered at the relevant local sites. However, longer term groundwater issues – such as managing contaminated groundwater inflows or future remediation efforts – would need to be considered in a broader regional context. The project’s location in a highly urbanised area means that past and present land uses pose contamination risks in all six precincts. Construction activities such as tunnelling, cut and cover, open cut and road widening have the potential to intercept contaminated groundwater, soil and rocks. Contaminated groundwater plumes have been identified as migrating from the former Fitzroy Gasworks site at the intersection of Hoddle and Smith streets at the eastern end of Precinct 2. These plumes could be intercepted during construction works for the tunnel and portals in Precincts 1, 2 and 3. Linking Melbourne Authority | East West Link – Eastern Section | Comprehensive Impact Statement Chapter


[edit] Surface water and groundwater draft submission notes

East-west dig a 'health hazard' The Age November 3, 2013

[edit] Residents Against the Tunnel (RAT) - CIS Groundwater Response - some key issues

The report acknowledges that groundwater levels & quality will be detrimentally affected through the construction process & then on an ongoing basis post construction. GHD Expert report identifies & acknowledges 4 potential impacts to groundwater. 1. Contaminated Groundwater Plumes. These result mainly from the Fitzroy Gasworks in precinct 2 but may have spread as far as precinct 1 & may be very deep. Contamination is in all 6 precincts. Asbestos also in precinct 3. There is also the problem of potential leaching from the cemetery. 2. Contaminated and/or saline Groundwater inflow into the tunnel. 3. Tunnel acts as a dam to regional groundwater flow. 4. Potential “dewatering” causing subsidence.

Legislation apparently requires that groundwater must be improved or maintained.

Issues of concern that are not adequately addressed by the CIS are as follows

1. There is no permit required for the use of groundwater. There are EPA Legislation & guidelines that provide a framework only. (Appendix M Page 2) Considering the potential impacts, a framework is inadequate. What obligation is there to follow the framework?

2. To overcome the weakness at 1 above, the expert proposes a series of performance requirements to ensure the mitigation of risk & minimisation of impacts. There are no assurances that these performance requirements will be the final requirements or adhered to.

3. The expert has said it will be up to contractor to determine the best approach to achieve the performance requirements. (Appendix M, page10). We do not accept that commercial interests should determine the method to ensure performance requirements. There are ample examples of self–regulation failing, especially when associated with commercial interests.

4. According to the expert report (Appendix M page 11), “Some innovation may be required to manage tunnel constructions and operations particularly for the Fitzroy Gasworks contaminated groundwater plume to minimise clean-up costs, protect the safety of workers and residents and enable ongoing clean-up and monitoring”. Unproven & experimental techniques are not acceptable. The project should not endanger the health of workers or residents.

5. The expert report (Appendix M, page 11) suggests the project is unlikely to significantly impact the existing groundwater users, potential groundwater ecosystems, activate acid sulphate soils or water quality. We are concerned that this opinion is relying on the innovation & ingenuity of the contractor as outlined at 4 above. The expert also acknowledges there will be a detrimental effect on the groundwater but has not quantified the extent. What is an acceptable level of damage to the groundwater when one considers the impacts could be so vast? (Human & ecosystem health)

6. The expert report has acknowledged that the contamination level from the Fitzroy Gasworks is high with over 50 separate contaminants identified. It has also acknowledged that the tunnel & portal works have the potential to mobilise (Appendix M, page 67) this contamination and hence spread the contamination to other areas. The potential extent of this mobilisation is not quantified. In addition, the works could alter the direction of groundwater flows due to the tunnel works and the damming effect of the tunnel. How far could this contaminated groundwater be spread in such a densely populated area and in what direction? How many people could potentially be endangered? These questions/impacts are not addressed.

7. The expert acknowledges (Appendix M, page 67) that the project may also complicate future attempts to remediate the area from contamination. The project should not reduce the ability to clean up the groundwater contamination for future generations. This has not been addressed.

8. The expert has acknowledged (Appendix M, page 67) the potential for subsidence caused by “de-watering” and resulting in changed groundwater level. This subsidence could manifest into unacceptable movement in buildings or damage to buried services. As it has been acknowledged that the tunnel will likely alter the groundwater flows during the construction phase and permanently due to the damming effect, what areas will be affected? There is no geographical quantification as to the extent of the damage. Who will bear the cost of monitoring the damage & repair to building & services? The CIS fails to address these issues.

9. The expert has acknowledged when quantifying mitigation measures (Appendix M, Page 68) “that metrics are either not available or not easily quantified for some events such as vegetation health should ground water levels change”. Because the metrics are unavailable / unknown is not an acceptable assessment of the risk. As the amount of vegetation within the inner city is minimal & hence so prized, destruction of any vegetation should be viewed as a major impact. Potential damage to vegetation within the Royal Park, its’ enclosed Zoo should be viewed as an abhorrent loss of amenity & an unacceptable risk. We do not accept the expert opinion of the acceptability of this risk.

Precinct 1 will involve “cut & cover “technique to construct the portal. Like all precincts, this area has been identified as contaminated but has the additional concern of proximity to the highly contaminated precinct 2. The potential for contaminated dust, to be transferred in times of high winds has not been assessed.

[edit] Reilly Street Drain

Work commenced on this drain in 1856 and was completed in 1908 it was perceived at the time as one of the most important pieces of infrastructure in inner Melbourne. It was built to take storm water run off from Carlton, Fitzroy and Clifton Hill and disperse this water into the Merri Creek just below Dight's Falls. Before the construction of this drain the land east of Wellington St (known as the flats) would be inundated with water when heavy storms eventuated, it is still a critical part of local infrastructure today. I would presume the structure is built of blue stone sections which was later rendered, it is 20ft wide and 10ft deep. Because this drain was built 150 years ago any severe vibrations or seismic movement could cause cracking and deep water seepage, leading to collapse of drain. This would be a catastrophic event considering this drain is critical to the health and amenity of the City of Yarra. Without this drain severe flooding would occur in many areas of Collingwood and Abbotsford under extreme storm conditions.

In 1856-7 The East Collingwood Council began to construct a major open drain along Reilly Street (Alexandra Parade) from Smith Street to the Merri Creek. It overflowed onto the Collingwood Flat in winter and had to be deepened to ten feet (3m) when the Melbourne City Council began to extend it west. The Argus, Tuesday 17 August 1886 reported the drain had a catchment of 700 acres in Melbourne, 120 acres in the Borough of Brunswick, 900 in City of Fitzroy and 156 in the City of Collingwood, although the principal flow was between Smith Street and the river.

[edit] Destruction of Wetlands in Royal Park

[edit] Implications for Ground Water pollution

Royal Park Stormwater Wetland and Reuse Scheme Extract: The Royal Park wetland stormwater reuse scheme treats, harvests and reuses stormwater from an urban catchment collected by a conventional drainage system. The ‘day lighting’ of the stormwater at the site provided an easy opportunity for diversion. Lows flows are diverted to the constructed wetland and the storage pond. After UV disinfection water is pumped to a closed buffer tank and then used for irrigation. Stormwater runoff is intercepted by the online diversion structure which also incorporates a sedimentation basin. This online silt trap is designed to remove coarse sediments (greater than 125 μm). The diversion structure directs low flows (up to 1 m3/s) into the constructed wetland. This online set-up ensures that low flows always run through the wetland. When the wetland reaches capacity, a feedback mechanism is engaged and the high flow diversion is engaged. As the feedback mechanism dictates the water flow, the design of the wetland’s riser plate was critical to the wetland operation and diversion structure. High flows are directed into the existing main drain via a weir. The weir is designed to also act as gross pollutant trap. Gross pollutants and litter are collected on the trash rack, requiring periodic maintenance for removal. The water then discharges into the Moonee Ponds Creek.

The drain attracted noxious industries to Alexandra Parade. The Shot tower was also the site of former Antimony & Sulphur Works Co.

[edit] Former Gas & Fuel Site Toxic Plume

No confidence that the toxic plume can be contained during works.

"SOIL CONTAMINATION: REMOVAL & CAPPING Remediation to deal with contamination from former gasworks on the site is likely to entail:

1. West side: Excavate to nominal depth of 4.5 metres. Area approx. 14,334 square metres.
2. East side: Excavate to nominal depth of 4.5 metres. Area approx. 20,368 square metres.
3. Gore Street alignment: Cap and retain as open easement. (Cannot be excavated due to extensive services)"

North Fitzroy Gasworks Precinct Urban Design Framework, Adopted 2008, pg3 REMEDIATION ISSUES