Sydney: the connection to the water

22 11 2009

Sydney is a great example of an industrial city that has transformed its image and waterfront to fit its commercial expansion. The waterfront is a destination catered to pedestrians and bustling with activity.

What is a successful urban waterfront? Of course, there are many other issues but these 3 represent the main issues a waterfront development should address:

– A clear and concise pedestrian connection to the water

– A commitment to environmental sustainability, whether it be through creating habitat in the water or through the landscape.

– A statement about the importance of education the present and future generations about the importance of a sustainable waterfront

After meeting with Peter Nowland and Rafael Chemke from the Sydney Harbour Foreshore Authority, they showed me some important spots along the harbour that I should visit. Here are a couple:

White Bay Seawall

Parts of an old vertical concrete seawall at White Bay had become unsafe and were due to be demolished and rebuilt.

Sydney Ports Corporation considered several different designs, most of which consisted of an inclined rubble-bank of some description. The design that was chosen to replace the old seawall is a stepped wall made of large rough-cut sandstone blocks.

The new stepped design means that the seawall has horizontal surfaces, approximately 0.5m wide and vertical surfaces, approximately 0.3m high, at various heights on the shore – a considerable change over the previous vertical concrete seawall. It also has similar composition to local natural rocky shores. The steps incorporate horizontal surfaces, which are a common feature of most rocky shores around Sydney, but are usually lacking on seawalls. This will increase the intertidal area as well as allowing for small rock-pools.

Picture 018 Glebe Point Park is a good example of redeveloping the foreshore with a sandstone seawall, access points to the water, and a pedestrian/biking trail along the edge. It is a mixture of seawall and natural shoreline and re-established mangroves.



Picture 169

Ballast Point was an old industrial refinery. As a contaminated industrial site, it has now been rebuilt as a public park with heritage fabric and historical story telling. They also renovated the existing sandstone seawall. This park portrays 20-25 years of landscape architecture evolution by providing a modern park using old materials.


Picture 165Picture 145 


Picture 102Peacock Point: In the 70s, the Sydney School of Architecture heavily influenced the landscape architecture language of the area. They believed that local bush should be reintroduced and the old industrial language of heavy timbers and bridge girders preserved. This park was the first to incorporate this style through bollards, picnic shelters, heavy timber stairs and benches.



I will be going to others on my way home to Seattle. For now, off to Brisbane….


Sydney: Meeting with Ashraf Doureihi

20 11 2009

I met with Ashraf Doureihi from the North Sydney Council, which is the Council that managed the McMahons Point seawall.

Most seawalls around the harbour are 100 year old heritage sandstone walls. They have stood the test of time but over the years and with increased wave action, a lot of the material held back by the seawall begins to siphon out through the joints.

A typical scenario for a Sydney sandstone seawall will begin showing signs of fill failure by sunken holes being present at the pedestrian level. The Councils use a pre-emptive program to save walls before they collapse, avoiding having to rebuild them from scratch. They have been using the grout penetration process for about 17 years now, which was an in house design. Grout penetration consists of drilling 100 millimeter hole casings 1 meter behind the seawall all the way down to the foundation every 3 meter spacing. They then pump grout underneath using a tremmie and a special mix that has been adjusted through trial and error.

The grout penetration then goes through 3 stages:

1 – Build a concrete toe grout at the foot of the existing seawall at .25 meter height

2- Pump/inject grout into all voids in the foundation

3- Raise tremmie to fill all holes along length.

The average cost of rebuilding a failed seawall is around $12,000-18,000 per linear meter. The grout penetration greatly reduces the cost to around $3,000-6,000 per linear meter and preventing any injury to pedestrians. There is a very low 5% rate of failure in grout penetrated seawalls.

At McMahons point, sections of the seawall had collapsed and the sea bed floor was extremely weak. This was a unique case that needed special attention since the sea floor had no bearing capacity and could not be knocked down and rebuilt. The North Sydney Council installed steel I-beams by hammering them 8 meters deep on average until they hit bedrock. They were tied back 10 meters to concrete anchors installed underground every 5 meters. Then, L-shaped precast concrete panels were attached to the steel beams. Sandstone blocks were then laid on the bottom section of the L and built vertically. Several blocks were left out for environmental purposes as they had no structural significance. They also incorporated a rock armor along the bottom of the seawall to protect against an abundance of wave action.

This 150 meter section of seawall cost around 2 million dollars, or $20,000/linear meter. This cost was justified because of the prominence of this spot in the Sydney Harbour. It had to be built vertically as it is prime real estate and could not take up pedestrian space with a sloped seawall. The site had to closed down for 3 years to raise funds and was built in 4 months, completed in 2006. This project shows a great 12 years relationship with the University of Sydney and the biological strength of seawalls. The site used to have zero marine life and has now blossomed with habitat. It is a great example of an urban vertical seawall that provides biodiversity.

The success of the project hinged on a great contractor and project manager that overcame hurdles easily. One hurdle included encountering a large sewer pipe in the way of the tie backs. This included convincing the Sydney Water Company of the benefits of this seawall/

This project could definitely be adjusted to fit the Alaskan Way Seawall. Ashraf explained that the sea wall depth bears no significance on the project, as the structural bearing relies completely on the steel I-beams, which could be drilled to any depth needed.

Ashraf sketched some images of the different seawall options and said he could provide me with the engineering drawings for the McMahons seawall. Once I return to the States, I will scan and upload said images.


Ashraf Doureihi is the Design & Investigations Engineer for the North Sydney Council.

Sydney: Meeting with John Heptonstall

19 11 2009

Located on the northern shores of Sydney Harbour, Mosman offers a rich cultural life amidst beautiful bush land surrounds. Mosman Council plans for building and development, maintains parks, beaches and sporting facilities, provides services for children, youth and seniors and runs cultural activities, a library and an art gallery.

Many of Mosman’s seawalls are nearly a century old and many are heritage listed. Some, including the walls at Mosman Bay, Quakers Hat Bay and the Spit are showing the effects of exposure to the elements, with collapsed and damaged sections, fallen sandstone blocks and subsidence behind the wall.

Ecological engineering Mosman’s foreshores

Council has developed a proposal for seawall works at Spit West, Spit East, Parriwi Point and Musgrave Street. Integrated with the seawall works in Spit East and Spit West is a proposed upgrade of access along the foreshore.

Seawall works will include rehabilitation, maintenance, upgrading walls and the establishment of new habitats for marine flora and fauna.

The proposal for improved access along the foreshore in Spit East will include improvements to the boat ramp, a new bicycle path, pedestrian path, bus bay and shared zone. In Spit West the proposed access improvements include a shared path for bicycles and pedestrians linking Pearl Bay Avenue to the Spit Bridge and mobility access from the car park to the foreshore.

I met with John and he took me to the Pearl Bay/Spit seawall which is about to the opened.

At Spit Bay, before there was a plain faced concrete seawall that covered the embankment. Besides some oysters that were growing along the bottom, there was no habitat to speak of. Also, the concrete was cracking in several spots and lifting out. Where they have implemented the new rock armory, an abundance of life has blossomed and provided a great comparison of an environment that provides habitat versus one that just has a concrete wall.

They used a rock armory to provide a barrier to tidal waves and structural stability at the base of the seawall where it is sliding out. This method of saving the seawall without having to rebuild it cost about 1/5 of the cost of rebuilding the seawall – this is quite significant across 800 meters of seawall. They implemented a rock armory to protect from tidal action and varied the placement and size of stone related to where the wave action comes from and its variance in strength. They scraped loose material at the bottom, placed geotextile and placed the stones – its slope is at one vertical to one and half horizontal. The rocks have been designed by coastal engineers. This provides stability at the bottom of the aging seawall and stops the seawall from sliding down.

They got the rocks in a quarry north of Sydney and they had to go through stringent testing to check the stability of the sandstone rocks. One of the major issues with seawall rocks is that they breakdown with the attack of sulfites and they had to test they could withstand the constant wetting and drying of being at a seawall.

The rocks provide shelter for smaller fish and it creates a breeding ground for habitat. There is quite a lot of sea life. The only minor problem they are getting is some litter issues that washes in from the harbour, which can be remedied by regular clean up maintenance.

On the ground, they implemented a bike trail and a pedestrian trail as well as planting that will eventually grow and become quite dense to act as a handrail for bicyclists and pedestrians. They also augmented a natural beach and put more sand in to create a high tide beach. At low tide you have a recreational beach area and it also creates habitat.

They worked with the Department of Energy and Climate Change as well as the University of Sydney – they have taken ideas from different sites to diversify the habitat and create a recreational area.

Another habitat they created was a salt marsh area where a section in inundated at high tide and allows the salt marsh to live within the correct habitat. They are providing it as an educational tool to show how seawalls should look like with signage and tours:

They also built a large tide pool that will flood at high tide and provide a shallow water habitat at low tide:

We also visited Quakers Hat Bay, where they were looking to create habitat for oysters and small fish. They’d like to study what actually has grown and lives there since it was built. They have worked with the University of Sydney about their research and gotten a lot of ideas of what can be done in each situation:


John Heptonstall is a Contract Engineer for the Mosman Council. He is the engineer principally involved in the project management of the design and construction of the Mosman seawalls.

Mosman’s walls have been designed and built in collaboration with Sydney University’s Centre for Environmental Impact in Coastal Cities (EICC). Also the state government’s Department of Environment and Climate Change has been involved with advice and funding as well as coordinating knowledge around the Sydney region for ecological engineering works.

Sydney: Meeting with Peter Nowland and Rafael Chemke

18 11 2009

I met with Peter and Rafael from the Sydney Harbour Foreshore Authority. We talked about the main Sydney wharf and its development over the years, specifically about the pedestrian connection to the water and how the landscape and seawall can aid such connection.

Sydney is a sunken river valley: Over many years, Sydney was carved out by a river and then flooded as the sea level rose. It was once a maritime industrial harbour with many working boats. There is an ongoing debate about the character of the urban foreshore: should it retain its industrial character as a business wharf and allow industrial business to continue? Or should it be restored to its original shoreline? One big argument is that you cannot have industry and people in the same place as it poses many privacy problems.

Picture 001

An interesting fact about Sydney’s code is that it is based on risk management, not on strict rules. Most of the harbour does not have railings and there are multiple spots where one could fall into the water easily. They view it as a personal risk management issue: you should be able to manage yourself and monitor your children so they do not require a handrail. In spots where rock is exposed or there is a drop farther than 1 meter or heavy pedestrian traffic, they do put up a handrail, typically as see-thru as possible. Signs and buoys are provided as well. They used to have a lot of classic legal cases where people would sue over injury, but the courts take a lenient view and usually side with the city. They think that in reality you could never truly make everything safe, and they would much rather preserve the physical and optical connection to the water.

Naturally, everyone wants to be near the water and the SHFA makes sure the water’s edge is activated with cafes and parks. There is a state policy that all waterfront must be accessible. They have some fights with private owners to preserve the water’s edge as public domain but there is strong documentation that the water’s edge belongs to the state and should be publicly designated.

As far as ownership goes, The Sydney Harbour Foreshore Authority owns the bricks, pavement top, and handrail at Sydney’s main neighborhoods, including Circular Quay, Darling Harbour, and the Rocks. Sydney Maritime owns the wharfs, seawall and anything below the median water level. Sydney Ports owns the overseas passenger terminals (cruise ships).

Most of the seawalls around the Sydney Harbour were established 100 yrs ago. They are expensive to maintain and many are beginning to fail. Sydney is known as sandstone country which is why most of the seawalls are made out of such. This poses some problems, as the sedimentary sandstone is much softer than granites and basalts, and over the years it wears down with water and salt.  The councils (or cities) and responsible for replacing the blocks as they wear down.

Picture 088

Peter and Rafael recommended several sports around the Sydney Harbour that I should visit to study the connection to the water. I will be going to the sites they mentioned and uploading info on each one.


Peter Nowland is a Landscape Architect for the Sydney Harbour Foreshore Authority. Rafael Chemke is a Sustainability Manager and Property and Asset Management. The Sydney Harbour Foreshore Authority is responsible for Sydney’s most historically and culturally significant waterfront  locations.

Sydney: Meeting with Professor Ross Coleman

18 11 2009

The reason I chose Australia to study seawalls was because of the studies the Centre for Research on Ecological Impacts of Coastal Cities has done, specifically in Sydney. I met with Professor Ross Coleman who gave me some great info on their studies:

The Centre for Research on Ecological Impacts of Coastal Cities is doing the necessary research to improve our understanding of the ecological processes affected by coastal changes so that we can make better progress in our protection and use of coastal habitats. Their team includes some of the world’s leading researchers in various related fields. The Centre is able to do the research to integrate ideas and models across habitats, to understand the processes of re-colonization after disturbances, to interpret the way populations persist when they are disturbed and to predict the patterns of occupation of new habitats when they are built.

In the New South Wales system, the natural urban coast consists of rocky ledges backed by vertical slopes. The study done by the University under the leadership of Prof Gee Chapman wanted to focus on what would happen with sea level rise when the habitat would have a sudden switch from horizontal to a vertical habitat (e.g. reduction in area etc). What they noticed was that what went on on rocky shores was radically different from what went on on vertical concrete seawalls, which led to engineering for biodiversity. The scientific process makes certain predictions: if I change the habitat (or structural complexity) I predict that the numbers of these organisms will increase compared to places that don’t have the habitat changed.

McMahon’s Point Seawall


An extensive seawall at McMahon’s Point was in disrepair and needing to be rebuilt as part of North Sydney Council’s program of repairing and redesigning many of their seawalls. The original seawall was made of sandstone blocks, but, in order to provide adequate support and resistance to wave-action in the long term, a precast concrete seawall was constructed. It was then faced with large sandstone blocks to resemble the original wall. Blocks at different tidal elevation were removed to provide tide pools to increase habitat.

At McMahons Point they built an old seawall (vertical) and a new seawall (vertical with tide pools) side by side so you could look at the relative abundance of organisms. The Sydney tidal floor range is under two meters, making all the seawall habitats be shallow. This points out a large difference between Sydney and Seattle, as the sea floor along the seawall in Seattle is as deep as 30 feet in some places. I asked Prof Coleman if the depth of the sea floor would affect the outcome. Prof Coleman replied that anything that increases habitat will increase biodiversity. What they don’t know is how the relative scale at which you manipulate the habitat will affect the scale at which the system responds. For example, is it good to build a bunch of big holes, or do you need lots of little ones? That sort of ratio is largely dictated by the system that you are in. All the variables for the specific habitat will come into play and it is hard to predict the actual scale of habitat change without doing tests in the actual system itself. The things that control abundance are usually very contingent on where you are. He concluded that you can’t predict the exact percentage of biodiversity increase but if you do change the seawall to have nooks and crannies, you will see some increase in habitat. It largely depends on what the management goals are.

At the McMahons Point seawall the biodiversity part is not structural. All the structural work is done by the reinforced vertical concrete wall behind the sandstone seawall panels along the front, which is similar to the studies being done by the UW on the Alaskan Way seawall. One thing is for sure: If you increase structural complexity you increase biodiversity. But they don’t know by how much and by what. The actual raw data of the % of habitat increase at McMahons will not be released until the publication of Gee Chapman’s seawall study. Until the scientific publication goes through, the quantitative data will not be released.

The tide pools are more like caves rather than rock pools so you get some animals that you would find in rock/tide pools, but since they don’t get full sunlight, you get other animals as well because it tends to be more sponge dominated. The alternative is to have things sticking out instead of receding, and what they are studying at the moment is bolting flower pots on the side of a vertical seawall. Various councils have the obligation under federal and state laws that they have to increase the biodiversity of their area, so if you don’t want to knock a seawall down but you want to increase the biodiversity, you can attach these flower pots to create tide pools.

A couple of facts about the Sydney Harbour:
-The tidal floor range is under two meters, making all the seawall habitats be shallow.
-There is little or no commercial fishing in the harbour because of contaminated surroundings.
-There is no migratory salmon along McMahons seawall, or Sydney Harbour
-There is very low tidal action, just boat wash.
-Councils (or cities) have state regulations that require to increase biodiversity if rebuilding a seawall.

Here is Ross Coleman speaking about seawalls:

They’ve also studied how a fish is attracted by light and not by eyesight. In Seattle, this means that when the migratory salmon swims north out of the Duwamish River, it will swim around the piers to be near light. This exposes them to predators. Maybe there can be something incorporated at the joint between the seawall and the pier. Perhaps a metal grid so light can travel downwards or perhaps artificial light to attract the fish as they travel. This could also provide a visual connection for the human to the water.

As people we tend to homogenize environments and make them cleaner and sleeker, when in fact biodiversity is accomplished by complicated structures (nooks and crannies). A system where the estuary would have normally had rocky shores, sandy beaches, muddy coves, tree material… that all accounts as structure and accounts as habitat for lots of organisms. So imagine if you replace all of that with a vertical concrete wall – you destroy all the complicated structure that creates life.

The Uni did research on artificial reefs and found there is no detectable difference between an artificial versus a natural habitat. You technically could get cleaned up rubbish and it would produce the same habitat as using clean stone and expensive materials. Creating topographical diversity, from large to small holes, even receding the grout between the sandstone blocks about 3 mm, can create different surfaces for habitat. There is benefits in creating both caves and stick outs. But, invasive species occur more on artificial habitat. So you may increase biodiversity but some of those species will be non natives. You have a higher probability of non natives than native species. There are issues on what you term biodiversity and it might be a double edged sword.

One great study they have recently embarked upon in a project names Iconic Landscapes. The University was finding that the general public and some legislations were not responding to the terms biodiversity or environmentally-friendly seawalls. The general public sees an experiment as something that will not happen, something they have to pay for but will not yield something for sure. And ecologist, however, knows it might not happen but sees the process as beneficial. How each type of person views ecological language largely affects how much they will be used. Iconic Landscapes is a group of social scientists that are surveying and interviewing different teams of people to see their reactions to different environments and their terms. One of these environments is seawalls. They are assembled three groups of people: scientists, legislators, and Joe Public. Do they feel the same way about the environment as the scientists do? Do they care about improving biodiversity or just catching more fish? They have a website and blog that I will link to shortly. This study is increasing awareness about biodiversity. Click here for link to website.


Associate Professor Ross Coleman is the Director for the Centre for Research on Ecological Impacts of Coastal Cities for the School of Biological Sciences for the University of Sydney.

Sydney: Meeting with Danny Wiecek

14 11 2009

Today I met with Danny Wiecek, Senior Natural Resource Officer of Coast and Estuaries for the Department of Environment, Climate Change and Water for the New South Wales Government. The Department of Environment, Climate Change and Water NSW covers a range of conservation and natural resources science and programs, including native vegetation, biodiversity and environmental water recovery.

The DECC has a funding program called the Estuaries Management Program and they basically give councils (cities) half the funding to do environmentally-friendly seawalls.

Danny recently wrote a state government guideline on improving the environmental value of seawalls in estuaries. This guideline is based on research done by the University of Sydney and the experience of what has been done in Australia and other cities around the world. The University has been doing research on the marine part and Danny does research on seawall lined shores – incorporating mangroves and salt marshes. He has been looking at the whole estuarine habitat rather than focusing on one type of seawall or habitat.

Urban estuaries like Sydney have to replace their crumbling seawalls, as more than 50% of the Sydney shore is lined with seawalls. In the past, there was no stand on whether they should be green or not, but now they’ve realized the destruction and loss of habitat that vertical seawalls cause. These seawalls have to be replaced anyways because they are falling in, so why not make them smarter and better and incorporate terrestrial vegetation and habitat? Danny works with local councils to determine what type of seawalls based on his written guideline will fit in each situation.

The guideline is not a mandatory provision, meaning not one seawall will be required in all situations since each habitat and marine situation is different. What is required is that an environmental aspect be incorporated based on a stack of different alternatives and outcomes (anything from mangroves to salt marshes, which is an endangered ecological community in Australia).

I was impressed by the way the funding for urban seawalls is set up. The city has to find half of the funding but the other half is supplied by an agency that is deeply invested in its ecological outcome, the DECC. This sets up a great scenario that guarantees a successful seawall that will aid its surroundings.

In Seattle, the seawall is a part of the Alaskan Way Viaduct Replacement and is being funded by SDOT and the State. Will the ecological impact be a driving factor behind the waterfront redevelopment?

Danny took me to a couple of seawalls along the Parramatta River. I posted a couple of pictures and here is a small clip of Danny explaining the benefits of the seawall:

STOP #1: Sydney

12 11 2009

SYDNEY, Australia

Sydney is the largest city in Australia, and the state capital of New South Wales. Sydney has a metropolitan area population of approximately 4.34 million and an area of approximately 12,000 square kilometres. Its inhabitants are called Sydneysiders, and Sydney is often called “the Harbour City”. The city is home to many prominent parks, such as Hyde Park, Royal Botanical Gardens and national parks. This is a major factor, along with Sydney Harbour that has led to the city’s reputation as one of the most beautiful in the world.

Out of all the cities I am traveling to as a part of my study, Sydney is the most similar to Seattle as they are both bustling urban cities with a strong connection to their waterfronts. I hope to compare and contrast the climate, geography, and marine habitat of each city to gauge if similar environmentally friendly seawalls could be feasibly built in Seattle.

An extensive seawall at McMahon’s Point in Sydney was recently rebuilt to revitalize the damaged wall and study how the ecosystems present state can be regenerated. A new sandstone façade implements deep rock-pools at different tide levels to renew the present aquatic life.

Also, a part of an old vertical concrete seawall at White Bay became unsafe and has been demolished and rebuilt. In its place, a new stepped design provides horizontal surfaces for sea life to live, as well as an opportunity to bring the person closer to the water.

Sydney is an ideal example of a densely populated urban city with an immediate connection to the sea. They are working to implement a set of coastline guidelines that, when followed, will standardize the use of smart seawalls. I propose to travel to Sydney to study and record my findings of their new and old seawalls, how they affect the environment, and how they connect the water to the urban fabric.

I will be visiting the above seawalls as well as meeting with local architects, engineers, and biologists that were involved in these projects and several other waterfront developments. I will be loading video and images as I travel so check back often!