- .. -
MORDIALLOC CREEK
Environmental Strategy and Opportunities Report
Prt:part:d by
Dandenong Valley WaterwaysAdvisory Committee
..fag ;; • DRAFT
MORDJAL LOC CREEK En vironmental Strategy and
OpportunitiesR epon
Pro duced for Public Comment by the Dandenong Valley Wate,ways Advisory Committee
September_1 992
Comments on this reportsh o uld be forwarded to: Dandenong Valley Waterways A dvisory Committee PO Box 550 DA NDENONG 3175 by 18 November 1992 ------··
•
The oandenong Valley Wate::-...tays Advisory Committee was for:ned in 1990 to advise the Hinis-ee.:- for Water I ! Resources on progress bei.ng made to achieve wate.: quality st·andards and other objectives p::-oposed by the State Environment Protection ?olicy for the Wate::-s of the Dandenong Va.lley. M embership of the Commi.t':ee includes representatives of: oe�a::-t:nent of Conservation & Envi.:-o��ent Deoar<:ment of Water Resources Helbou::-ne Water En·,..ironment Protection Authority City of Kordialloc City of Chelsea City of frankston City of Springvale toget:1er with The Hon. Hal Sanden, MP The Hon. Peter Spyker, MP A Community Representative Table of Contents
Page
Synopsis l
l. Background 2
2. Ti.m.i.og 4
3. Kxisting Conditions s
4 • .. Objectives • Principles ·, 5. Opportunities " Constraints 10 6. Elements of the Concept 11
7. Impleme!1tation Opportunities 14
8. The Next Step 22
Figures -- 1. Zones and Reserved Land 3
2. Kordialloc Creek catchment 7
3. Wetlands of the Lower Dandenong Valley 18
Foldout Illustrations - Waterway G Wetland Enhancement Opportunities following 22 - l -
SYNOPSIS The Draft Environmental Strategy presented here outlines the opportunities for the remodelling of Moi;:slialloc Mai_�a.in__ ��o� __ .Pillars Crossing to Wells Road. The plan proposes earthworks and planting to change the shape of the levees and waterway from the existing straight course to a more interesting, "natural" form. There is a significant opportunity to create a series of wetlands along the Creek. Reed beds within the wetlands will help to filter out sediments and pollutants, thus improving the quality of water entering Mordialloc Creek and Port Phillip Bay. The strategy has five main aims:- l. To improve the quality of water and reduce the amount of sediment entering the estuary. 2. To retain and improve the flood mitigation capability of the creek and floodplains. 3. To increase the amount and variety of habitat along the c:eek for local fauna and flora. .. 4. To enhance the quality of the local landscape • 5. To develop the creek as a place for recreation. The creation of a series of wetlands along Mordialloc Main Drain, which lies midway between Braeside Park and the Edithvale Wetlands, will consolidate the habitat and recreation importance of this region, making it a "habitat area" of truly international significance.
The plans incorporated in this report present the ��-l_"_situation and may �\ be implemented over a long period of time. -rmplementation will be dependent on funding and on some land becoming available - by co-operative arrangements with landowners, by purchase where necessary, and by co ordinated sympathetic development.
This document should form the basis for the preparation of a statutory concept plan under the Planning and Environment Act 1987. Such a statutory planning document would ensure that the objectives of the plan are considered in·any future town planning determinations for the area. This plan seeks to:
flag to decision-makers and landowners the desirable future form of the parcels of land which make up the Creek and environs.
enthuse the local and broader communities about the possibility for a better creek environs.
Underpinning the plan are the principles of total catchment management and environmentally sustainable development. - 4 -
2. TlXING
It is desirable that an environmental strategy for Mordialloc creek be prepared at this time as there are a number of matters that will be affected by the strategy. These include: a) a review of a portion of the "green wedge" in Keysborough is being carried out by the Department of Planning and Sousing in conjunction with the Cities of Oandenong and Springvale. The "green wedge" review area is the area surrounded by the Mornington Peninsula Freeway, South Eastern Purification Plant and the proposed Dingley and Scoresby Freeways. This review will investigate appropriate land ·1 uses for the area, identify major road, service, open space and , landscape linkages through the area and prepare landscape and design guidelines for critical locations. Amendment to the planning schemes covering the area may result. b) the need to decide what part the proposed Theme Park, .on the corner of Button and Springvale Roads, Keysborough is to play in the development of the Chain of Wetlands strategy. c) the need by Melbourne Water · and other agencies to develop total catchment management strategies for the improvement in quality of urban runoff and the control of trash and sediment reaching waterways, estuaries and Port Phillip Bay. - 5 -
3. EXISTING CONDITIONS 3.l Water QUality The water quality of Mordialloc Creek is dominated by urban runoff and the sewage effluent discharge from the Melbourne Water Dandenong treatment works.
The table shows current water quality at various sites both upstream and downstream of Mordialloc Main Drain. In general, water quality at all sites exceeds State Environment Protection Policy criteria. The difference between values downstream of Mile Creek and at Pillars Crossing in Dandenong Creek indicate the degree of influence the Melbourne Water Dandenong treatment works discharge is having on the water quality in Dandenong Creek. Differences between values in Dandenong Creek downstream of Mile Creek (Melways 89Kl0) and those of the major drains entering Mordialloc Creek indicate the relative impact of these drain inputs. The elevated concentrations in Mordialloc creek at Wells Road are difficult to interpret and are probably an aberration of testing at this site being sampled less frequently (approx. 10 times over 2 years) than Dandenong Creek at Pillars Crossing or Mordialloc Creek at the Railway Bridge (approx. 30 times over 2 years). In general the results and water quality are similar to the most recent previous assessment by the Dandenong Valley Authority in 1990.
The planned removal of Melbourne Water Dandenong treatment works effluent from the system before 1995 will significantly improve the water quality of Dandenong Creek and Mordialloc Creeks particularly with respect to nutrients, however significant concentrations of suspended solids and E. coli are likely to remain. These variables alone can significantly influence beneficial uses and water quality in the estuary and warrant the investigation of possible urban runoff treatment methods such as wetlands. KXDIAN VALUES * (July 1989 - January 1992)
DO .K.co.l.i. 8005 SS Dandenong Creek 9.5 2.1 22.0 0.1 0.1 1400 downstream Mile Creek Dandenong Creek 8.5 8.7 21.0 2.3 2.9 2200 at Pillars Crossing (A) I
Dunlops Drain 6.8 6.0 10.0 0.4 0.4 3200 downstream Governor Rd (8)
Mordialloc Settlement 7.1 6.1 10.0 0.5 0.2 2500 Drain at Governor Rd (C)
Mordialloc Creek 5.4 ll.O 28.0 2.5 7.0 3100 at Wells Rd (D)
Mordialloc Creek 6.2 5.5 20.0 l. 7 2.0 2200 at Railway Bridge (E)
State Environment >4.0 N .S. <25 N.S. N.S. <1000 Protection Policy W-28A
Desirable Values >8 <5 <20 <0.l <0.l <1000
Onita: mg./1, except for E. coli - organisms/lOOml. • Where DO • Dissolved Oxygen, soo5 • Biochemical Oxygen Demand, SS • Suspended Solids, P04-P • Orthophosphate as Phosphorus, NH4-N = Ammonia as Nitrogen and N.S. • Not Specified. t For location refer to Figure 2. - 8 -
An industrial subdivision has been filled and developed adjacent to Wells Road and west of Mordialloc Settlement Drain (Canterbury Road and Haymer Court), right down to the WAG pipeline. Similarly, a small area on Governor Road east of Dunlops Drain.
The balance of the land is undeveloped and generally flood prone. The undeveloped land is held in two parcels, and development requirements have been set on both.
The larger parcel of some 75 hectares had development requirements set in 1971, including the provision of a 300 foot (91.4 metre) drainage reserve adjacent to Mordialloc Creek. All of this land, including the proposed drainage reserve, is currently zoned industrial.
The rest of the land up to Springvale Road south of Governor Road was previously zoned for farming and extractive uses but the 19 ha triangular portion west of the freeway has been recently rezoned garden industrial. A condition placed on this rezoning, which will result in filling, was that there was to be no further loss of flood storage on the balance of the land east of the freeway and that the drainage reserve was to be provided, as described above.
On the triangular piece of land, the area between Mordialloc Creek and the WAG easement has been zoned stream and floodway. Further, negotiations on subdivision have resulted in a proposal for a l.65 hectare drainage reserve to cover an area of remnant swamp paperbark. A drainage scheme has been prepared for this section of creek and includes remodelling of the area between the WAG easement and Mordialloc Creek. Proposed Freeway to Springvale Road The existing creek has the same section here as downstream, that is, a. straight channel with high levees on either side. The northern· levee is unlikely to be overtopped and flooding mainly occurs through backing up from the Dunlops Drain/Mordialloc Creek confluence any future works should ensure that the flow path remains open so that the flood storage can be fully utilised.
The floodplain north of the creek in this area has some 1,000,000 cubic metres of flood storage which has to be retained. soringvale Road to Pillars crossing
Mordialloc Main Drain in this section is again a straight channel with levees on the north and south, and a. catch drain a.long the north side. The north levee is relatively low at Springvale Road, there are breaches in the levee for Sheltons Drain and Edithvale Road Drain, and large catchments result in the section of floodplain near Springvale Road flooding several times a year.
The drainage requirements placed on these has been for no loss of flood storage and no increase in upstream flood levels. 3.3 Plora • Fauna
This work has arisen out of a desire to improve water quality attributes of the Mordialloc Creek. Flora and fauna information has not been collated as part of this report. However this information will be available as more detail is given to the proposals. - 9 -
4. OBJECTIVES_ 'i PIUNCIPLKS Mordialloc Creek (that section of waten.ray between the creek mouth and Wells Road) was remodelled during the period 1977-79. Subsequent revegetation of its banks, together with noxious weed control, have resulted in the creation of an aesthetically pleasing waten.ray which has moderate values for the conservation of wildlife. It is however, troubled by sub-standard water quality and copious quantities of silt and trash washed down from the catchment above. Mordialloc Main Drain (that section of waten.ray between �ells Road and Pillars Crossing), being a straight levee-banked channel, was constructed for the purpose of conveying the waters of Dandenong Creek to Mordialloc Creek. It is of limited value as a habitat for wildlife and has low aesthetic or recreational values. An opportunity exists to mitigate the water quality and sedimentation problems of the Creek, and to develop the Main Drain so that its future aesthetic, habitat and recreational values are greatly enhanced. As a prerequisite to this, sediments, trash and water quality must be controlled in all tributaries of the Creek and Main Drain. The objectives of this strategy are therefore: 1. Improvement of the quality of water entering the Mordialloc . Creek estuary and Port Phillip Bay by trapping of pollution and sediments upstream of the estuary. 2. Restoration and enhancement of local floodplains and wetland habitats. Maintaining and where possi.ble increasing floodplain storage capacity is of prime importance. 3. creation of habitat, by re-establishing local native vegetation. Planting will enhance the charateristics of the creek as a wildlife corridor. 4. Protection and enhancement of landscape quality. 5. Creation of recreational opportunities. Development of the creek into a �pular place for walking, cycling and exploring. The strategy should be based upon the following principles: l. reduction in the a.mount of silt and trash entering the estuary. Each _t.ei.bu-t-a-r�-of.--the-.. Creek or Main Drain should be fitted w,i.th. one::oi::. more silt/trash retention facilities from whic�accumulatad material can-be-mechanically removed on a periodical basis.
2. �ing improvement in water qualityY through the control of point source_�T1fchargea... (a..task largeI aclileved by EPA. activftyY, ··a.ncf ·non�· """PO'inc source pollution (such as urban runoff). Note that low flows will be reduced in quantity but improved in quality by the cessation of discharge from the Melbourne Water Dandenong treatment works. 3. retenti�_and . possible enhancement of existing___ wetlands in the • . I catchment. Creation of new ···wetlanaa·-wh"ere --�ssi.ble to assist the·1 .,. -tre-atmen�c:r-·c1arification-ot__ _ botti ..tiL;h and iow-tiows:···-·-onry· the· ,'1-,. . -moet-advantageou·s· sites .. for· .. wetland- creation should be ·utilised, 80 as to minimise loss of productivity or land acquisition costs. 4. The floodplain storage capacity must be retained and enhanced as -;k • opportunity arises • Concurrent with, and part of the above activities should be a program of landscape enhancement, habitat creation and development of a system of -:11 linear trails for recreation. (No public access on private lands should be Jf' contemplated. ) 10
5. OPPORTUNITDCS AND CONSTRAINTS
5.1 Opportunities The majority of opportunities identified in this report require usage of land. Opportunity exists to better use the land within the Main Drain, and the Bowen Road reserve. The proposed Mornington Peninsula Freeway represents an opportunity, as the batters for roadworks may in themselves be able to be used as levees.
Land can become available through co-operative arrangements with landholders who wish to enhance the existing uses, or directly through land purchase and possibly via development tradeoffs, wherein the landholder �laces part of the land into public ownership in exchange for development l vc. I vil. l«un:i8utl.D]i0 cmi�o.ts ensuring that the nature of any development does not endanger the broader creek concept are required. 5.2 Constraints
Flood mitigation: In any remodelling of the creek, the current flood storage capacity of each site needs ·.to be at least retained and preferably increased. The lower reaches of creek are extensively urbanised limiting opportunities in these areas. Pillars Road Levee: The south levee, in the section running parallel to Pillars Road, protects the whole of the land between Mordialloc Creek, Dandenong Creek and the Nepean Highway from flooding. Substantial alteration of the location of the southern levee would involve significant earthworks, reconstruction of Pillars Road and compensation for the numerous dwellings and properties fronting Pillars Road. The cost would far outweigh the benefits. Flows: The Main Drain will have considerably reduced base flow once discharge from the Melbourne Water Dandenong treatment works ceases. WAG Pipeline: .. The Westernport-Altona-Geelong (WAG) Pipeline Authority will not allow permanent waterbodies to be created above the underground f , pipeline. The distance between the northern levee and the WAG pipeline varies from a.bout 40 to 80 metres. Land Ownership: The majority of the land a.butting the creek is in private ownership. On the north side, land between Wells Road and the proposed Mornington Peninsula Freeway is zoned industrial. Between the Freeway and Pillars Road the land is predominantly zoned rural and is used for agricultural purposes.
Financial: Considerable financial input may be required to realise the objectives of this strategy, and it is therefore likely that implementation will be a long-term project.
Town Planning: The strategy will require appropriate support and recognition in town planning schemes to achieve maximum success. - ll -
6. KI.XMXNTS 0!' TBB OONCXPT
For the concept to be developed, a number of elements have been identified, each with specific functions. Particular elements of the concept are. aimed at one or more of the following functions: .. water quality improvement . .. flood mitigation • .. habitat creation and enhancement . .. improvement in landscape quality. .. development of recreational usage • Water Quality Improvement The control of litter and sediment is of prime concern in enhancing water quality in the catchment. As most litter and sediment are moved down the drainage system under higher flo�s, it is necessary that litter and sediment be controlled in each tributary, and not by one massive installation at the bottom of the catchment. No one installation is likely to be successful for all situations. Litter may be removed in a number of ways. These include: (i) Control near its source, such as in traps installed in the drainage system serving areas that are known to generate large amounts of litter such as shopping centres, fast food outlets, and some industrial areas. (ii) Ose of floating booms across waterways. These are moderately effective for floating litter under lower flows, but are of limited value under flood flow conditions. (iii) Dual purpose use of flood retarding basins, whereby flows are stored and allowed to drain slowly, catching trash and sediment within the basin. This is a concept that requires further investigation. Not all re�arding basins are suitable for conversion. Water quality can be improved by the following measures: (i) Point source control of pollutants. These discharges are usually controlled by the EPA, if they are of a regular nature·. In general they are no longer a problem in the catchment, although the discharge from the Melbourne Water Dandenong treatment works will possibly continue until 1994. Pollution spills, however can be a problem and· should be dealt with as swiftly and effectively as possible. (ii) Improved control of non-point source pollutants. These are generally materials conveyed to the waterways by rainfall runoff. Materials-. such as nutrients, bacteria, heavy metals and sediment fall into this category. Most of these materials are conveyed as a result of runoff arising from high rainfall. More frequent street-sweeping may reduce the amount of material arising from this source. The practice of street flushing should be discontinued. (iii) Encourage the use of floodplains for the temporary ponding of water arising from higher rainfall events. This will assist in the removal of finer sediments and associated contaminants, and provide time for the dieoff of bacteria. - 12 -
(iv) Encourage the use of wetlands, both within the waterways and on adjacent lands. Such areas are frequently vegetated by stands of species such as Typ?d and Phra9I1.i.ces, which are recognised as being effective in removing sediments and contaminants from water flowing through them. Existing swamps should be retained, and new ones developed as opportunity arises. Urban runoff wetlands are similar to natural ephemeral marshes and swamps and can sometimes be conveniently located in the floor of flood retarding basins. They can have a very wide range of habitats varying from permanent water silt traps to ephemeral grass-woodland. Flooding regime and retention time of the various habitats vary greatly depending on system design and the catchment hydrology. They can be used in any situation where space allows for the dispersal of runoff flows and hence the control of water velocity and inundation frequency and duration. For example where waterways have floodplains, a proportion of stream flow, at any chosen point in the hydrograph, can be directed through off-course wetlands located in the floodplain. Such off-course wetlands may be simply the reactivation of floodplain features such as old courses and billabongs or cleared natural, floodplain marshes or swamps, or be purpose designed and constructed systems. Urban runoff may carry large pollutant loads but water volumes are large and as a result concentrations are generally low. Fine particulate material in urban runoff is mostly mineral in nature, and a large proportion of the pollutants, such as phosphorus, metals and organics, are adsorbed to these mineral particulates. The major treatment role of the emergent aquatic macrophytes is to provide surface area for the filtering and adhesion of particles. Flood Mitigation and Drainage Successfully mitigating against flooding and providing· adequate drainage (!l .J for the area can be achieved by: ( i) retaining the existing floodplain storage capacity identified in the Mordialloc Creek floodplain management study as being required, and enhancing it wherever possible. (ii) retention of all critical waterway flow paths, ensuring they are of sufficient capacity to provide protection of assets from flooding. (iii) acquisition of strategic lands adjacent to Mordialloc Main Drain for the purpose of providing additional floodplain storage capacity as well as wetland treatment area. Habitat Creation and Enhancement The creation and enhancement of the habitat values of the Ma.in Drain and environs can be effected by: (i) reshaping the form of the banks of the drain to create a series of meanders and a series of wetlands of varying configurations and dimensions which will provide a variety of niches which would support a diversity of aquatic and riparian plants and animals. Amphibians are currently one of the most threatened groups within the Victorian fauna. An opportunity exists here to create considerable amphibian habitat. (ii) appropriate revegetation of areas around the creek and upon any acquired lands which can form regional habitat corridords, particularly between Braeside and Edithvale Wetlands. - lJ -
Improvement in Landscape quality Tree planting and bank reshaping could transform the Main Drain · into a pleasant, striking, landscape feature. With considered planting of the local River Red Gums, the Creek could take on the typical appearance of a river flowing through the Australian landscape. As a landscape feature the Main Drain would provide interesting attractive views across the paddocks from Springvale Road, Governor Road and Perry Road. River bank planting could reinforce the relaxed, semi-rural character of the green wedge. Vistas from the Springvale Road and Wells Road bridges could provide the passing motorist with intriguing glimpses of the widened Creek environs. Water in the landscape is considered pleasing and calming. Development of Recreation Opportunities A cycle/walking path along"the Main Drain would open it up to exploration and enjoyment by the broader community. An interesting path network is developing in this area. A path along the Drain could link to Port Phillip Bay in the west and to the Dandenong Creek trail (and hence to Carrum and the Dandenong Ranges) in the east_. Linkages to Braeside Park and to Edithvale Wetlands could ultimately be created. In practice, this means that local people would be able to visit a whole series of parks by cycling or walking. ,
With good signage, the trail network may become a popular tourist attraction for visitors (local, interstate and indeed international) seeking to explore the south-east complex of Wetlands.
Through considered design, �safe� areas for eeling and tadpoling could also be created for the enjoyment of local fisherman and children. - 14 -
7. IKPLKMK'.NTATION OPPORTUNITIES Reference needs to be made to the foldout illustrations at the rear of this • report whe� reading this section •
These elements are aimed at increasing the efficiency of the drainage system, maintaining or adding to overland flow paths and enhancing sediment collection. Opportunities exist to: Cl - Investigate the potential for diversion of up to l in 2 year ARI event from H.ordialloc Settlement Drain to Ounlops Drain at Lower Oandenong Road. Would divert silt loads to Ounlops Drain allowing more efficient removal. 02 - Finalise the drainage form of Smythes Drain floodway through Drill's property (subject to acquisition in progress by Melbourne Water) in a soft engineering form with appropriate landscaping. 03 - Remodel of Mordialloc Main Drain floodway between the southern levee and WAG pipeline alignment· for increased hydraulic capacity. Waterway form to cater for side cast, wetlands, variable batters and mitigation of adverse visual impact at rear of industrial premises. This remodelling includes removal of existing northern levee and creation of a wider floodplain. 04 - Remodel the end of Ounlops Drain to allow for silt trap and side casting capability into wetlands. 05 - Diversion of Oingley Drain. The road formation qf the future freeway will cut off the existing flow path to the west: a diversion path will be necessary. Waterway form could be a minor channel with braiding segments. The potential to use the freeway/Governor Road enhancements as a retarding basin needs further investigation. South of Governor Road, the new drainage line may be a minor ill defined channel winding its way through the wetland areas. 06 - Create _low amplitude meanders to ensure little impact on drainage efficiency or gradient problems. Use of typical trapezoidal channel form to be avoided. Waterway may also have flow 'chokes' to encourage side casting of events greater than l in l ARI. Establish a major waterway feature to form sedimentation pondage at the critical upper reach point of tidal influence. Create a major fj- landscape and water quality treatment feature. The inclusion of more land area may enhance critical volume for floodplain storage in Hains' property. Maintain low flow (floodgated) diversion of Smythes Drain into Mordialloc Main Drain with high flow diversion/segregation as per existing arrangement but with new positioning. New floodway to be variable in form with vegetation coppices from top of batters. Stabilise and revegetate recent drainage diversions of Sheltons Drain West. Create a major water feature on Sheltons Drain upstream of the Main Drain. May be used for water supply supplement by adjoining developments. Form to ensure a 'non-engineered' appearance and ·, include a variety of wetland and habitat opportunities� ,oJ3t- Remodel the waterway along the Main Drain upstream of Springvale Road v' to have a variable form and low amplitude meanders. This will necessitate removal of the northern levee but as flood flow diversion -.lS -
from Pillars Crossing is to decrease, little flooding impact should be felt.
/Ol-2 - Create a meander system to allow for side casting of· flood flows I . into existing low lying, flood prone areas to reinforce existing � freshwater meadow wetlands. 013 - Control flows at Pillars Crossing to provide base winter flows of 60 ML/d. Recognise that flows will be reduced following Melbourne Water Dandenong treatment works diversion. Ultimate low flow split between Mordia.lloc and Dandenong Creeks will be determined by water quality maintenance requirements in both Mordialloc estuary and the National Water Sports Centre, but a recommended maximum flow of 20ML/d to the Mordialloc system is recommended. 014 - Modify the Pillars Crossing Weirs to lower flood levels upstream thus increasing flexibility for changes in waterway and landscape form. Notionally remove 0.5 - 1.0 m from primary weir (full investigation required). Removal of material in waterway floor may also be required. remodel Cheltenham and Chandler Road Retarding Basins to enable trapping of sediment and trash. Stabilise the Edithva.le Road Dr.a.in downstream of Cheltenham Road in an environmentally acceptable manner to limit instream erosion contributing to sedimentation problems in Mordialloc Main Drain. Sediment and Trash Control
These elements are principally aimed at reduction in the amount of sediment and trash being transmitted to the Creek .and Main Drain. The concept of side casting flows into flood prone areas is intended to temporarily utilise these areas for the removal of fine sediments, thereby preventing them from being deposited in the Mordialloc Creek estuary. Opportunities exist to:
Sl - Incorporate silt and trash control structures in the Southern Retarding Basin at the rear of Moorabbin Airport. This will remove significant load of trash, sediment and oils coming from the Heatherton Drain system. There will be no interference with the flood mitigation function of the retarding basin. 52 - Form a new sediment basin at the end of Mordialloc Settlement Drain south of the WAG pipeline easement and adjacent to the current intertidal zone. This will remove or concentrate the coarser sediments coming down Mordialloc Main Drain under higher frequency events. (Note: Proposed investigation of diversion of l in 2 year ARI flows.)
53 - Create a new sediment trap on Dunlops Drain north of Governor Road. May receive increased loads of sediment due to the proposed diversion of the l or 2 year ARI flows of Mordialloc Settlement Drain further north (refer to 01). A larger silt trap may be required and located about 200 metres north of Governor Road and may form part of a landscape feature of the proposed industrial subdivision in that area.
54 - Create a new sediment and trash trap at the end of Ounlops Drain north of the existing waterway and south of the WAG pipeline at a point west of the existing drain. This structure is to intercept higher flow silt and trash loads that would operate under a side cast operation. This structure should be constructed as part of the remodelling of the floodway between the WAG pipeline and the existing southern levee. - 16 - ·' S�:· - create a new pondage at the upper end of the tidal influence area ;,,__ _,,./ which will assist greatly in the trapment of bedload and silt, particularly from Edithvale Road Drain. I 56 - remodel the Cheltenham Road Retarding Basin. Modify the inlet and _,., floor to accommodate a new silt and trash trap. . S7: - make further use of Sheltons Drain in removing low levels of silt and I trash which will only increase with time. The proposal is to create a combined silt trap in conjunction with a wetland area and water storage at the eastern end of the proposed Theme Park establishment. I SS - remodel the waterway floor of Dandenong Creek upstream of Pillars crossing, creating of a series of silt traps that would intercept the bedload that is currently partially being diverted down Mordialloc Main Drain. 59 - continue utilising the existing trash booms in the intertidal area of Mordialloc Creek at the rear of the Mordialloc-Chelsea High School. Flood Kitigation and Control One of the crucial aims of the enhancement program is the retention and enhancement of flood storage capacities, along with flood transmission needs of the Mordialloc Main Drain system. The Mordialloc Main Drain Flood Study has identified that there are critical elements required to ensure that existing developments in the Mordialloc area are not threatened by flooding events exceeding the l in 100 year ARI. Opportunities include: Fl - The remodelling of the floodway between the existing levee adjacent to Bowen Road and the proposed limit of filling_ adjacent to the WAG pipeline is critical for the transmission of flood flows and also the retention of some storage capacity. Restructure . of this area will include the removal of the existing catch drain and levee on the north side of the floodway and the removal of an extensive amount of material to provide for satisfactory storage and transmission requirements. There is potential for development of wetlands for water treatment in conjunction with this remodelling. F2 - Completion of the Smythes Drain floodway which has only been partially constructed at the rear of the Aspendale Gardens Estate and will need to be continued through to Wells and Springvale Road. The design and form of this floodway should not . be undertaken in its current "hard" trapezoidal form and should have more variable form to allow for enhancement of landscape elements. - The acquisition of land south of the exis� Main Drain alignment between the propose on Pen.1.ns�F�way and Springvale I ;G3J Road, is seen as · ical to providin�an iq!=J::.e.�.�e in floodplain /,l ,sto �e and also a. ··s.1. cant landsca� reature and water quality �rol struc:l:Ure. The proposal involves ehe--shifting of the existing levee bank southwards to a point where it runs parallel to the proposed freeway boundary with the Smythes Drain high flow floodway running between. The formation of new levee may be achieved using the existing levee materials or material excavated to create the proposed water feature in this area. Excess material in this 1 area may be excavated by or sold to Vic Roads tor the future freeway \ formation. Acquisition of this land may also involve the short term acquisition of the freeway land unless Vic Roads can become party to a joint acquisition program. The removal of the existing levee on the north side of the main drain downstream of Springvale Road may necessitate the provision of new levees within the Hains' property. The levee proposed_, would be required around the existing high value horse complex giving a 100 year ARI level of protection. - 17 - /-� FS - Acquisition of the western portion of rural zoned land of thS\_Hains'� property. This property provides a significant component af--.theil storage capacity required for the flood mitigation strategy for: 1 Mordialloc Creek. There is a potential conflict with respect to ; I realization of the potential of the special extractive zone, if· removal of the area from the floodplain storage is sought. F6·. - The retention of floodplain storage upstream of Springvale Road is I seen as critical as the whole system backs up into this area under flood conditions. The proposed Theme Park will be required to maintain the flood storage capacity and if relocation of the flood storage further upstream is desired, flow paths need to be kept wide to avoid increasing the height of the flood levels in this area. improvement of Dandenong Creek at Pillars Crossing. The existing capacity of the Dandenong Creek upstream of Pillars Crossing at the l in 100 ARI event is seen as fairly marginal with minimal freeboard being available within the levee system in that event. The retention of a diversion capacity to the Mordialloc Main Drain system is seen as a valuable option. The level of protection in this area may be increased by remodelling of the floor of the Oandenong creek floodway in this area. F8 - The acquisition of lands south and west of Wells Road (Drill's property) for flood storage capacity n�eds to be finalised. This acquisition is associated with a permit to develop lands.to north of Wells Road and the process is currently being held in abeyance by a Department of Planning and Housing objection, based on the misunderstanding of a perceived loss of floodplain storage. Once acquired the land south of Wells Road will be remodelled and the flood storage capacity north of Wells Road woul_d be compensated for by excavation and remodelling on the south side ·of Wells Road. This will provide an opportunity for landscaping and wetland construction. Wetlands The retention of existing natural wetland elements and the creation of new wetland bodies for the treatment of the runoff flows is an important element of the enhancement strategy. Most of the lands north of the Main Drain were at some stage part of the former Carrum carrum Swamp (see figure 3). The remnant elements a.re few but examination of aerial photography and Landsat imagery indicates that remnant morphological elements still exist, although the original flowpaths have been diverted. It is proposed to retain the existing natural elements, reactivate some of the alienated areas and also to create treatment areas using wetland technology, particularly along the Main Drain. Opportunities include: Wl - In the area of land south and west of Wells Road an excavation to provide flood storage capacity will be required possibly having wetland elements within the new floor. (See FB) W2 - The reformation of the floodway in this area may involve the creation of side cast wetland bodies to enable the diversion of higher flows through those bodies thus removing some of the contaminant load. The "saddle" or side cast wetlands are a feature along the Main Drain between Wells Road and Sheltons Drain. futher enhancement of the wetlands at Braeside Park together with the diversion of the Dingley Drain which will provide opportunity for the creation of wetland meadows in the area. This will add to the existing diversity of habitat already existing at Braeside. ,.,..-�·\4 ..- :'W creation of new wetlands within the Hains' property. Examination of ·-·· aerial photography indicates that shallow depressions exist within this property, associated with the probable former flow paths of the Dingley Drain catchment. An option in the proposal to create an enhanced variety of shallow wetland structures in this area is to - 18 -
BR.AE::51D� we,1..AN D�
W'f s�vs::cc;; 1. su.:..ver- P-JO� SY r.e. �"Ur PHlLL-IPPORT B,.\y �cl'/T OJTL.Sr�. __ KA.NAflCOK. � __ ..,.._, (:;.;. - x ! "AP'PTW.X.fMAIE C::.x11::.N'l° OF- (lG'E:I.:,) \ �----"_.:;.:. - I CA;::.�M CA�M $VVA}../lP' 0 2· J Figure 3 Wetlands of the Lower Dandenong Valley - 19 - take the opportunity of the need and acquire fill for the freeway construction or adjacent industrial land. Water for these wetlands ,,,-.. would be provided from the Dingley Drain diversion. utilisation and enhancement {to Council and Melbourne Water (_//ws; requirements) of the current area of 2 in l year ARI inundation upstream of Springvale Road which is forming a meadow wetland habitat. The water for this wetland is being provided by backup flows out of the Mordialloc Main Drain and also side cast flows from Edithvale Road Drain. It is interesting to note some of the more significant areas of wetlands in this cell are actually over the depressions formed by the WAG pipeline. The existing meadow wetland is providing for some occasional feeding opportunities. W6 =- The proposal to mainW� relocate floodplain storage in association with the Theme Parls)development along Sheltons Drain is an opportunity for crelat__.i,.ng--a" wetland treatment zone for Sheltons Drain flows. It is also interesting to note that a former flow path of Sheltons Drain to the west of the current alignment has some meadow wetalnd features . ..::-, to extend and create larger wetland bodies on la d north of &- the WAG pipel�J:oc..g tbe ax.i,S't"'tng d?a.i.nage ressi within the floodplain areas of the property. Water supply o these wetlands would be principally via local drainage and some side cast from the remodelled Mordialloc Main Drain and catchment drain systems. /"\ w�; - i/ . enhance the ing wetland areas within the floodplain on Young's ·,.... / propert tnroug� the removal of the levees on the north side of the Mordl�c Main, rain allowing for more side casting of flows out of the �ordiallo';/�ain Drain during higher flows. �he wetlands could be enh�ced :9----provide new habitat and the provision of local catchment draina.ge--co this area is seen as critical for retention. Landscape Enhancement The landscape of the Mordialloc Main Drain environs has been severely degraded since European settlement, by clearance of the area for graz.1.ng. Prior to settlement and drainage of the Carrum Lowlands, it is most likely that the landscape. was dominated by open redgum woodlands on the higher dunal systems and possessed extensive coverage of swamp paperbark and tea tree swamps with occasional outcrops of other eucalypt species on the margins. Clearing has removed most of the significant vegetation. The landscape has been degraded by the development activity, including the channelisation of the drainage system. Whilst this strategy is primarily aimed at improvement of water quality through the development of wetlands, this in turn provides scope for improvement in landscape quality and creation of recreational opportunities. An important element of the enhancement program is the re establishment of significant stands of indigenous plantings {particularly the redgums and swamp paperbark) as well as the preservation of the foreground, midground, and particularly the background views to the Dandenong Ranges. It is important to remember that the creek is viewed primarily from the bridges which cross it. Opportunities comprise: Ll - The acquisition of the land south and west of Wells Road and the I reforming of this area for flood mitigation purposes would provide an excellent opportunity to landscape and revegetate the area in a sympathetic manner. L2 - Dunlops Drain. The wel.l established river redgum stand immediately north of Governor Road on either side of Dunlops Drain should be retained as an important feature and an offset to the future industrial development of the area. Similarly revegetation along the - 20 - concrete lined channel area downstream of Governor Road with species such as river redgum and swamp paperbark in clumps should be undertaken. LJ - The Smythes Drain floodway and Bowen Road frontage of the southern levee is a dominant landscape feature. Strategically placed clumps of vegetation in association with some reforming of the levee and minor meandering of the floodway will significantly enhance the area through reducing the linearity of the features. L4 - The retention of the remnant swamp paperbark wetland on the Whiteacres property has already been negotiated with the current owners. This was done in conjunction with a rezoning of the triangle of land west of the proposed freeway alignment. An opportunity exists to extend this area westwards, to cover other remnants of this vegetation type when planning industrial development on this site. The co-ordinated planning and landscape treatment of this area with the northern batter of the floodway is crucial. The sympathetic treatment of landscape elements along the rear of the industrial :",,.. properties is seen as being critical factor to maintaining a .. · j reasonable landscape amenity in the area. ... Ls-·· / /. The minor meandering of the waterway and variation in the southern :_/· levee form along Bowen Road and around the freeway is critical to mitigating the visua��ct� future freeway. It is recommended that the reew'ay be heavily plan n its title boundary ..._ prior to constructi ing e nt of mature trees . /- \ / r.6' - ' ; The total realignment of the levee bank southwards to abut to the freeway in this are��rs arr-��Lopportunity to provide a diverse range of- _�cl__in.tersea.t.i,on with Springvale Road has created an excellent opportunity for revegetation in the area not required for road formation. Plantings could be undertaken immediately with some simple preparation. L9 Important landscape elements of the propose��;�site which lie in the variability of landscape fea rising from the floodplain up through an old dunal area, which has been vegetated with exotic windbreaks and also single remnant specimens of river redgum��y of this amenity should not be lost in any development scenario and indeed very strong revegetation of development elements should be undertaken. This includes the successful landscaping of wetland elements on the floodplain and also ...... adjacent to Sheltons Drain • LlO - The opportunity to revegetate areas around the junction of Sheltons ":<� Drain east and west branches should not be lost as the perfect habitat is available for the growing of flood2_.y,in__ s�c..k.�S. ._such as swamp paperbark a.nd river redgum. � es Lll, 12 & 13 - The existing solitary river redgums located on high sand dunes knolls throughout the area should be retained. With suitable fencing, regeneration of copses of river redgum will add to the landscape quality of the area. - 21 - !.14 - The revegetation opportunity of the waterway upstream of Pillars Crossing has always been limited by perceived capacity problems which restrict planting of trees in the floor or on the batters. If the I floor of the waterway is reformed then opportunities to ·create small mounds and copses of river redgums will become available. This will significantly improve the harsh engineered aspect of the waterway in this area and also help lessen the visual intrusion of the I Dandenong's offensive industrial zone. LlS - The strong linearity of the waterway and levee between Springvale Road and Pillars Crossing and in particularly along Pillars Road is a severe constraint. Affordable opportunities for variation in the levee form only exist on the southern levee, where bulk fill could be placed against the levee to vary its form and allow for revegetation. It may only take a few well planted copses to remove the strong linear and hard engineered appearance. Habitat Creation One of the benefits of the program of works recommended is that a significant increase in the diversity of habitat will be achieved along the waterway. Not only will there be a variety of wetland forms and increased vegetation diversity, but also there should be a change in the periodicity of inundation of some of the wetlands thus creating an increase in feeding habitat diversity. The revegetation program will further increase of habitat for some terrestrial species such as possums and woodland birds. The importance of the waterway for transitory feeding, flight paths and wildlife corridors should not be underestimated and maintenance of a significant green link along Mordialloc Main Drain will serve to link the wetlands at Braeside Park with those of Edithvale and Seaford and those· systems further north via Dandenong Creek and further east via the Eumemmerring and Ballam Valley drainage systems •. Recreation Opportunity There is an existing investigation into the formation of a linear trail along the full length of the Main Drain from Wells Road through to Pillars Crossing. At the moment a 1.5 kilometre segment of trail exists upstream of Wells Road to the rear of the Aspendale Gardens subdivision. It is envisaged that this trail may be extended to Springvale Road sometime in the next five years. Further opportunities exist for the interconnection of local trail systems northwards between Bowen Road and Braeside Park, either via the Dunlops Drain or the freeway reserves. Location of this link has not been determined but it has been suggested that the linear trail may utilise the eastern side of the freeway formation. This would link existing elements of Braeside Park and the main linear trail along the southern levee. A further opportunity exists between the rear of the proposed industrial developments west of the freeway and the newly formed floodway. An opportunity exists for a variable step batter formation over the WAG pipeline thus creating an opportunity for casual linear trail in a variable landscape setting. The extension of the linear trail eastwards of Springvale Road will provide a link to the existing Dandenong Creek linear trail. This link may take some time to realise as it may be difficult to recommend or to receive allocation within a total metropolitan priority context. Further extension of the recreational amenity along the waterway will depend to a significant degree upon the amount of land put into the public ownership. Limited opportunity is available for public access onto private land except of course where sympathetic development of that land occurs for a recreational purpose. - 22 - 8. THB: RXrr STEP This draft- document will be distributed widely to the public, local landholders, conservation groups and state and local planning authorities for corrment. A finalised strategy, incorporating comments received, will be presented to Melbourne Water and the appropriate councils for adoption in principle. It is not envisaged that any program of activities will be initiated until full consultation with affected landowners has been conducted, .snd mechanisms of achievement thoroughly investigated. This document is an important first step in realising the potential of Mordialloc Main Drain as a water filtering system, as wildlife habitat, as a flood storage system, and as a landscape and recreation asset. To achieve real, on-going change - to create a better creek - it is important that the opportunities broadly outlined in this document be further investigated. Essentially this requires a commitment from the managing agencies to resource the further work required to develop this opportunity plan into a Statutory Concept Plan under the Planning and Environment Act 1987. Such a statutory planning document would ensure that the objectives of the plan are considered in any future town planning determinations for the area. .DRAFT MORDIALLOC CREEK J ENVIRONMENTAL STRATEGY • " • -. • ,u :,o • ; :, ;,- ,: �•,o , :·,•:••'":� '<�•:,:•. y :••: •,.,, =··�· • •••='•·.:••: , •: •:•••; ,•,:•, •• •••: •:,: •: •: : : .. ,, • •,,-••,: .. •:••:.. •·. :•""'_.•:••!•�•,•�,.;?•*.•f;:•·�'V,•:••:••••••••:•, • • ;, •• :, '•• • •.• ·{-.· : • •• • • _-, : •• • •, • ; • ,•• ;,,, .. : •:,,.,, . •• • • • Waterway & Wetland Enhancement Opportunities LEGEND @ Sediment & Trash Control Existing Trail • Drainage Elements Proposed Trail Flood Mitigation & Control ••••••••• • 0 Silt Trap • Wetland Elements . Deep Water • landscape Enhancements & Silt Trap Flood Plain - Existing Boundary 111 - -- Levees ExistiAg Drainage Lines - � _---; -----7- --j _.-:., Property Boundaries Existing, Removed Ro ads ------Dams � fP a, � Vegetation Reeds, Rushes Pipelines w . -· ���*�� --·--:::::-· :::::::::::::-�� Woodland (eg River Red Gum) Existing alignment Mordialloc Main Drain Shrubbery (eg Melaleuca)1119 . · · Future Open Waterways & Drainage Paths · a p- .-.. MordlaJloc Catchment • Plan Sheet PORT PHILLIP BAY CATCHMENTS & LOCALITY. PLAN - PLAN SHEETS 1 TO 5 DRAFT MORDIALLOC CREEK ENVIRONMENTAL STRATEGY Waterway & Wetland EnhancementOpportunities r. Figure 1 J zones and Reserved 1Er Land 1 l I I ! /-- II ! --.... I I II Fl -� - .. ; !I I I i i / I I I I I ! ! i l>NO '· I YED L ' I I ! ANO RESER I I ZONES I !I I \Nic.RESi l,e.-.OSC.oPE. cc:AAJOJP. FlCOO'«AY STREPI" .At-0 L.At-0 � RESERVr.0 S?EC\,!L :.L IH P.O.All RES \rfNT\ lSi\NG 1-'A lllG EX P.O.All E?.vEO l IV O 1-'AlN RES PRCf>l)SE y P.O.All 1tSS lNG SECO� &t3\ \/ELC!l�£Ni E)(\Si Y ll.QPD �NS\Vc QE 5Ecat,0AA C �o \� �i CEN"ffiE pru)POSED II.� 'lt\tfN 1 (!N"lllE 11.A\l°MVS 0 \S"iR\ C EitS11NG l.oll 11.A\l°MVS 110JS1R PR(l'OSEO S?� PI.S-\C QPEN R� E)(IS1lt-G S?� FAAM\NG PlfLI C QPEN � 9-E pR(l>()SED p!JU)OSES vE �\CIJ,J\ P\fL\C ([) \NiENS\ .XIS1lt-G ?QSES i AAEA E IC PUR CE1£Leflt..fN (j>()SED � �T\Vc PR s.DEC \� EX'Tll. ON co,:SEIWAT l ] p ] lr ] r r ] Mordialloc I Settlement Drain Industrial .· .. (Filled) . . . ·,:•:.-:.. - cb ( ,�I" -. r. \ ,, . : .- I �, I r·� r f ] \ Future - � ) I / Springvale / R ad Trail / o .f / Industrial ./ .. . ·- . ..:�.... -.. . . -... .:,.--..- .. _.. -�:--:=-=�?"':� ·""'-�1�� . .- ..' ... ::�:Sli�b�:s\'Drain.: . :. } I . ,•• . -· .-_:�.r--Floodwiif· Reserve �:;�. - ��-;�·£-� . . • ..J : • . • :.-.... � '"-!. ·...... • . .. ..: ··.· � -��- ··...:...: �·· -: .. .. ·- �----:t 0 -- ' -·· \ --=...-+---I _:J c: ' e Ro f'.-�______w_ 1_1s_ _ _a_d__ -...... - J' ' PLAN 2 ol !1 I · �s6 •• h I� -·_... :-•. . ,• 9.. - Edithvale Road Drain �· Proposed Theme I Fun Park.---- Existing Floodplain 100 Year Event f 3.3 AHO ----xisting Floodplain 100 Year Event 3.3 AHO .,I •Ii Future f. Springvale . ' Road Trail r • . � ....__..,...._._,_... � ,;-� -. . . . I . . ..-·� ...... ·-:.....� .·· i . . :: ·.- \ (· - ii t · � -- I v I I I -- -1 _ (7' t � t J I I f I , t I + I ·l __ l + i i -t I I I I t 4 I -.. . - -- I / Jf / I .J. I I � I / JI' / _..,;I"' �Existing y --� Floodplain / 100 Year Even JI' 3.7 AHO �Existing . I Floodplain AI . 100 Year Event / I ,I 3.7 AHO I I Existing • Floodplain 100 Year Event 4.0 AHO I. � __,...-. · -�- -·· · --::s...-.- ' - -=-"'"---,- ...... - -;· · ...,- · .-- -- -· : •. : --�· -··-·�·-�--:"-�,:::----, · · +--- �--- - =: ...... - :.:· � -.---.R.... ::, · d · ="'! LEGEND Sediment & Trash Control G) Existing Trail • Drainage Elements ...._ _....,._ ...... Proposed Trail Flood Mitigation & Control •• • • • • • • • • \ 0. Wetland De ress1.on Silt Trap • Wetland Elements · · · Deep Water • Landscape Enhancements & Silt Trap Flood Plain - Existing Boundary Levees Existing �.�-talned ---- - �r.u++tt!WH,rmmtttttHlfflttltf.... . )!IH\\� Existing Drainage Lines New 1u1\Un1tl1f11H1lll\UIMW\\Wllllh - -� ---?-___..,- --j _ _->, Piilars Road CD Property Boundaries Existing, Removed -is ------Roads Da ms t1l> �·-;:···:'-' , . Vegetation Reeds, Rush.es Ill Pipe Ii n es ---·:::::--. v �...:JtL.'lk.,__w :.u . � . tu.. i;s.>� . IJJ .·�i'/.. .�-�·- --a--·- � -·--.::::·-� Woodland (eg River Red Gum) Existing alignment Mordialloc------·-- Main Drain Shrubbery� 11 I (eg Melaleuca) :.� SCALE 1 : 5000 Ii"i : ; ' ! oo omes,�i!Eil-='..,���...... 200._ .... .300�11111111400 ._.. ..soo. t DI AM i:; :r