Waking up in Geelong

So you have paid heed to Melbourne’s history of railway flash flooding, and flood proofed your rail under road grade separation. But there is something you can’t fix as easily – flooding out anyone living beside the train trench.

Flooding out the sandbelt

In 2016 the level crossings on the Frankston line at North Road, McKinnon Road and Centre Road were removed, with the railway being placed into a trench between each road, with three new stations constructed at Ormond, McKinnon and Bentleigh.

Massive drainage pits were constructed on the uphill side of the rail cutting, to ensure that stormwater would not enter the trench, and stop trains.

But given enough rain a massive concrete lined cutting across a natural watercourse will turn into a dam – as local residents found out in December 2016 – the first big storm after completion of the level crossing removal project.

LXRA investigates flood of allegations from angry homeowners
Sam Bidey
Moorabbin Glen Eira Leader
January 17, 2017

An investigation is under way to determine whether a new drainage system installed by the Level Crossing Removal Authority caused the severe flooding of dozens of homes.

Residents along Glen Orme Ave, McKinnon, are still out of their houses as the clean-up continues following the December 29 storm.

Irate homeowner Aislinn Martin believes new drainage running through Glen Orme Ave, which was constructed during works to remove the McKinnon level crossing, caused thousands of litres of water to sweep through her house.

The LXRA installed the drainage to protect the rail trench from flooding, but Ms Martin said that just resulted in her street being walloped with a torrential amount of excess water during the storm.

One neighbour, who did not wish to be named, said the flooding occurred because the water was intended to flow into the Elster Creek drain, but, with that already overflowing, it gushed out of the new overflow grates along Glen Orme Ave.

Following the December 29 storm, the LXRA sent letters to residents to advise that all newly installed drainage would be checked and the authority would notify them on the outcome of the investigation.

“We have worked closely with Melbourne Water and council to protect the rail line and ensure our work does not cause any additional flooding,” LXRA project director Adam Maguire said. “We will continue to help clean up with our road sweepers.”

Local member and Liberal MP Georgie Crozier raised the issue in Parliament on 21 March 2017.

My adjournment matter this evening is for the minister responsible for the removal of level crossings, Minister Allan. I have raised on a number of occasions issues in relation to the level crossing removals at North Road in Ormond and McKinnon Road and Centre Road in Bentleigh. This matter relates to the level crossing removal in Ormond and involves the works undertaken for drainage. We have had another weather event today. I believe there are a number of areas in metropolitan Melbourne that have been flooded, and I do hope that there is no ongoing damage from the rains today.

On 29 December significant flooding occurred in Melbourne and across the state from which there was significant damage in the Ormond area and also in the neighbouring area of McKinnon, where significant amounts of water were coming out of the drains that were put in place to cope with the extensive drainage from those level crossing sites.

Nevertheless, my issue concerns, as I said, the North Road area. Many residents have written to me and expressed their concerns about what has actually happened in terms of the pipes and various construction dealing with these drainage issues, with the Level Crossing Removal Authority (LXRA), Melbourne Water and the local council. All of these residents have been told that significant work was done, that everything was okay and that the LXRA had undertaken some investigation and found that the system was operating as it was designed to. However, there are still some concerns held by various residents who have not had many of their queries answered to their satisfaction.

One of the areas of concern relates to all of the piping and the drainage that was laid during the construction phase and what other areas may be affected by this.

The action I am seeking from the minister is that the investigation and the report by the LXRA on these works be made public so that the affected residents can understand fully what consultation with Melbourne Water and the Glen Eira City Council was undertaken and what works actually took place to cater for future flooding, because we will get future rain events which will be greater than the last one. If the minister could provide that to the public, that would be most helpful.

With the Level Crossing Removal Authority publishing their report into the flooding in September 2017.

Throughout 2017 Melbourne Water and the Level Crossing Removal Authority have undertaken a joint review of flooding that occurred as a result of intense rainfall on 29 December 2016 and how the drainage system installed as part of the North McKinnon Centre Level Crossing Removal Project operated during the storm event.

Which found:

The drainage works needed to enable the level crossing removal at Ormond and McKinnon were very complex to design. The passage of the rail corridor through the floodplain and the established character of the area limited drainage design options.

Significant planning and care was taken to ensure the drainage design for the North McKinnon Centre Level Crossing Removal Project did not make flooding worse.

Our review has highlighted that:

• All affected properties are within the envelope of flooding predicted by our modelling both pre and post construction of the drainage.
• As a result of the construction works, many properties will in fact have experienced lower flood levels through the December event than would have been experienced pre-construction. These properties are primarily upstream of the railway works.
• A small number of properties downstream of the railway line were adversely affected as the storm event occurred during construction prior to the works being completed. These property owners have
been contacted directly and are located in Elm Grove and Glen Orme Avenue.

As part of the Project, significant drainage infrastructure was installed and existing assets altered. The drainage infrastructure and alterations have been designed to replicate the pre-existing (prior to project) flood conditions in the area.

The drainage infrastructure and alterations have been designed to replicate the pre-existing (prior to the project) flood conditions in the area. As part of normal flood mitigation activities, Melbourne Water has initiated a project to evaluate localised mitigation opportunities.

Cold comfort for local residents, but a quick glance at the Glen Eira Planning Scheme shows that the entire area is subject to a Special Building Overlay, so flooding is a fact of life for this area.

And over to Blackburn

Blackburn Road in Blackburn is another rail under road grade separation, with the level crossing removed in 2017.

The pedestrian subway at Blackburn station used to flood as soon as a single drop of rain fell.

So the drainage was upgraded to prevent it, including this massive stormwater detention structure on the south side of Blackburn station.

But it had a flow on effect to residents of South Parade, located south of the station.

Rail drain’s flow-on effect
Blackburn station underpass fixed but houses now flooded
Whitehorse Leader
Paddy Naughtin
December 18, 2017

The State Government’s much vaunted improvements to the notorious Blackburn station underpass failed to handle the latest deluge, leading to flooding of neighbouring properties.

Properties in South Parade flooded on December 7 after the new drainage system at the station reached capacity and overflowed on to the street. The water was too much for the street’s gutters and flowed over into people’s yards.

Susan Rundle said the “horrendous” flooding was the worst she’d seen in a decade. “We measured the water being 70cm deep in our backyard — you can see the line on my husband’s workshop where the water got to,” Ms Rundle said.

“The drainage system was upgraded during the level-crossing removal works to ensure the station underpass didn’t flood, but its seems to have just made things worse for other areas in the neighbourhood.”

State Government spokeswoman Hayley McNaughton said the drainage upgrade had been built to standards.

“As part of works to remove the dangerous and congested level crossing on Blackburn Rd the project also upgraded the drainage to mitigate flooding,” Ms McNaughton said.

Local member and Liberal MP Robert Clark took up the case a few days after the floods.

Residents flooded by bungled rail project
9 December 2017

This was South Parade in Blackburn on Thursday evening, as residents were inundated with overflow from the Blackburn rail project’s new drainage system.

Backyards have been flooded, garages filled with water and driveways washed away, causing thousands of dollars of damage to residents’ homes.

After turning the South Parade shopping strip into a concrete jungle in the name of fixing the drainage, instead the project has turned a quiet residential street into a floodplain.

Raising the issue in Parliament a few days later.

I raise with the Minister for Public Transport the flooding that has occurred in South Parade, Blackburn, as a result of the Blackburn rail project, and I ask the minister to find out exactly what has gone wrong and to have urgent remedial works undertaken so this flooding does not happen again.

Last Thursday evening numerous homes along South Parade were inundated with overflow from the rail project’s new drainage system.

After turning the South Parade shopping strip into a concrete jungle in the name of fixing the drainage, the government’s handling of the rail project has turned a quiet residential street into a flood plain.

Photos taken by residents show water gushing out through the grill around the top of the drainage pit next to the station and strewing gravel and other debris across the road before pouring downhill into residents’ homes.

Last Thursday’s flooding was the third and most damaging of the flood events that have started to occur since the rail project works have been undertaken. Long-term residents say that prior to the rail project works there had been no major flooding in South Parade since a drain was installed in the 1960s.

Then raising it again a year later, following more flash flooding.

South Parade residents flooded again by Labor’s crossing bungle
8 November 2018

This is South Parade, Blackburn, on Tuesday – flooded yet again by water overflowing from the “upgraded” drainage system installed as part of Labor’s bungling of the Blackburn level crossing removal.

The LXRA and the government have known about this problem since similar major flooding almost a year ago, but have done nothing to fix it, leaving residents to suffer every time there’s a heavy downpour.

It’s clear that the flooding is coming straight out of the new drainage system – instead of flooding the station’s pedestrian underpass, as used to happen, it’s now flooding residents’ homes all along South Parade.

This first happened in December last year. I raised it in Parliament, residents raised it with the LXRA, it was front page of the local paper, LXRA and the government promised to look into it and then… nothing. It needs to be fixed.

A check of the SES Flood Guide for Laburnum shows that the entire area was already at risk of flooding, thanks to a creek placed underground when the area was first turned into houses.

But that doesn’t mean much to residents if the flooding is now worse than before the level crossing removal works.

And a Pakenham line footnote

Upgrade works at the Clyde Road level crossing in Berwick also resulted in local businesses being flooded out.

Flooded by the rails
Rowan Forster
Pakenham Gazette
2 November 2018

The Level Crossing Removal Authority has been flooded with complaints from aggrieved business owners in Berwick amid allegations properties are becoming inundated by stormwater due to botched upgrades.

Landlords of Enterprise Avenue have reached boiling point – fearful labourers and construction workers could be rendered jobless if the issue persists.

The Gazette understands the problem arose when the State Government began construction at the Clyde Road crossing more than 12 months ago.

As the railway line has been elevated, water no longer flows into the natural drainage system and instead gushes towards the rear of the Berwick properties.

Despite pressuring bureaucrats for more than a year, Barry Pitcher has not received any answers.

It might sound simple, but keeping things dry isn’t easy!

Recent years have seen many new rail under road grade separations built across Melbourne, yet they don’t turn into swimming pools every time it rains. You can’t use the rest of the network as a model – flash flooding is a common sight across Melbourne’s poorly maintained rail system – so how do they stay dry?

Prevention is better than pumps

The first step is to prevent water from flowing into the trench.

Taking advantage of existing slopes is the easiest way.

Or regrading the surrounding soil to slope away from the cutting.

Adding small kerbs alongside the top of the cutting wall will redirect water.

As will exploiting the massive concrete walls used to stop idiot motorists from crashing down onto the tracks.

But that might not be enough – sometimes upgrades to the local drainage system are required.

To ensure that stormwater doesn’t overflow the surrounding streets, and breach the trench walls.

This means that the only water to end up in the trench is the rain that falls upon it.

Time for drains

Drains between the tracks collect any rainwater.

It then flows downhill to the lowest part of the trench.

Where a pump then sends it back out again, via a web of pipe work.

Under the pump

So how big do the pumps need to be?

The Furlong Road grade separation on the Sunbury line at Ginifer station is a deep hole – the pump station supplied by Aquatec Enviro‎ has some impressive specifications – 3.2 metre outside diameter, 10.74 metres deep, and capable of pumping out 440 litres/second of water.

Main Road at St Albans has a longer approach cutting, so the pump station needs to remove more water – 3.2 metre outside diameter, 9.74 metres deep, and capable of pumping out 490 litres/second of water.

While the Blackburn Road grade separation on the Belgrave/Lilydale lines has more complicated requirements.

The long trench on the approach to the station has a pump station for drainage – 2.3 metre outside diameter, 5.78 metres deep, and capable of pumping out 480 litres/second of water.

But thanks to the depth of the cutting, groundwater also needs to be removed from the cutting, requiring a second pump station – 1.0 metre outside diameter and 6.0 metres deep, but only needing to remove 2 litres/second of water.

And finally, the infamous ever flooded pedestrian subway – it has a 1.8 metre outside diameter and 3.5 metres deep pump station, capable of removing 50 litres/second of water, hopefully to prevent a repeat of this.

And the cost to run them?

Taking the figures for Furlong Road, a 480 litre/second capacity pump lifting water 10.74 metres, assuming 60% pump efficiency, requires a 85 kilowatt motor to drive it.

In reality you might provide two separate pumps taking half the load, which appears to be what happened at the pump stations Aquatec Enviro supplied to the LXRA.

Photo by Aquatec Enviro

The same logic was applied at Ormond station on the Frankston line – multiple 30 kW pumps were installed, backed by a 220 KVA generator to take over if mains power failed.

According to Sustainability Victoria’s “Energy Efficiency – Pumping Systems” best practice guide, a fully loaded 100 kW electric motor, assuring 90% motor efficiency, costs $16 / hour to run or $373 / day to run, if you’re paying 14 cents a kilowatt hour.

So not expensive to run, but still far more costly than the free drainage provided by gravity.

Drainage standards

Metro Trains Melbourne track drainage standard L1-CHE-STD-030 covers the scope of railway drainage – and what it doesn’t:

2.1 This standard sets out MTM requirements for drainage systems within the rail corridor. It covers the technical requirements for drainage of the track formation, supporting embankments and cuttings.

2.2 This standard does not cover drainage from carparks, buildings, overbridges, footbridges, airspace developments, external developments, access roads, roads outside the rail corridor, council drains or properties adjacent to the rail corridor.

2.3 This standard does not include culvert design or design of other infrastructure used to allow overland flow to cross the rail corridor.

As well as the two types of drainage the railway installs:

Cess drains are surface drains located at the formation level at the side of the tracks. They remove water that has percolated through the ballast and is flowing across the capping layer towards the outside of the formation. Cess drains are primarily intended for protect the formation by keeping it dry.

Catch drains (also known as “top drains”) intercept overland flow or runoff before it reaches the track. Catch drains are generally located on the uphill side of a cutting or catch water flowing down the hill and remove it prior to reaching the cutting.

How much water the drains are expected to handle.

9.2.1 Flood design shall protect all track assets from the 1% AEP flood level (1 in 100 year ARI event) and permit the unrestricted operation of trains by not overtopping the capping layer. The capacity of the drainage system shall take into account the rainfall intensity, the water runoff to be managed and the particulars of the location.

And how big the pump stations need to be.

16.4 The pumped system shall provide storage capacity for a 2 hour, 1% AEP (100 year ARI) event in case of pump system failure. A 2 hour period has been determined as an acceptable response time for maintenance staff to reinstate the operation of the pump system after the high water level warning is triggered by the alarm system.

16.5 The pumped system shall provide sufficient redundancy in the pump and pipe sets that when one unit or inlet/outlet pipe is temporarily offline (e.g. maintenance or fault), all drainage requirements can still be satisfied.

16.6 The pump station shall have a connection for a backup generator and pump in case of power failure. The connection type shall be compatible with equipment used by emergency services and MTM.

While the Level Crossing Removal Authorty’s “Cross Drainage Assessment – Rail Under Road” for the Edithvale Road, Edithvale project details the effect that rail under road grade separations might cause to the surrounding area.

3.2 Design requirements

The following criteria and design objectives have been established as a framework for assessing the level crossing removal. The final design requirements will be further developed a part of the design process.

The works must be designed and constructed:

1. To prevent the underside of the ballast flooding from a 1 in 100-year Average Recurrence Interval (ARI) event (without freeboard) estimated in accordance with Australian Rainfall and Runoff (AR&R, 2016).
2. To meet the requirements stated in the Metro Trains Melbourne drainage guidelines (Metro, 2016).
3. To meet the flooding requirements of the relevant drainage authorities (typically Melbourne Water and the City of Kingston).
4. In accordance with the requirements of the relevant road authority and the relevant drainage authorities.
5. Such that the potential for flooding of any other property is not increased by the project (initial focus on the 100-year ARI event and other events may be considered subject to
   further direction).
6. To limit the impact of the project on major drainage and overland water flows to the satisfaction of the relevant drainage authority(s). This will typically require assessment of changes (afflux) in velocity, depth, erosion, duration of inundation.

As well as the elements that make draining a road under rail grade separation hard – or simple.

A preliminary flood and cross drainage assessment has been undertaken for Edithvale Road, Edithvale level crossing removal.

The purpose of the report is to identify matters relating to cross-drainage that may need to be incorporated into the level crossing removal project design.

The proposed works will not occur within a defined land subject to inundation overlay or special building overlay. Furthermore, available topographical data indicates that the proposed works occur along a local ridge where surface flows will generally discharge away from the rail corridor.

Due to the characteristics of the site, in particular the ridge crest location of the existing rail corridor, it is considered that the project will not have a significant effect on cross flows and consequently flood risk within the surrounding area.

Potential increases in rainfall intensities from climate change and the effect that this may have on the standard of flood protection for the railway, road assets and other properties will be considered for cross-drainage design.

Given that the proposed works will not impede or impact overland flow paths or existing flood areas no further mitigation is required as a result of the project.

As the design progresses, management of the local drainage network and catchments should generally be incorporated into the design and further analysis of major overland flow paths should not be required.

And a City Loop footnote

The City Loop tunnels have a similar problem – how do you prevent water from running down the approach ramps and into the tunnels!

Their solution is simple – a concrete lip at the top of each ramp, preventing groundwater from entering.