Category Archives: GeoTechnical Engineering

A Seawall for All: The Seattle Waterfront Project as a Model for Future Redevelopment

By Brian Dutra, Engineer at Pare Corporation and a member of Pare’s Sustainability Committee

Coastline Along Marblehead, MA

New England’s coastline is home to some of the Nation’s first and largest waterfront communities, with nearly 6,100 miles of tidal shoreline in the region. Unfortunately, the nation’s coastal infrastructure is deteriorating, which greatly impacts these communities.  According to the 2017 ASCE Infrastructure Report Card, Ports and Inland Waterways were given a grade of “C+” and “D”, respectively, with a need to modify or replace structures that have far exceeded their design life.  The need to rehabilitate or replace these structures is further emphasized as the infrastructure along the coastline continues to age and deteriorate.

As we evaluate and rehabilitate New England’s coastal infrastructure, an ongoing project in Seattle, Washington can provide a template for innovative and sustainable design improvements.

The billion dollar “Waterfront Seattle” project is a total waterfront reconstruction along Elliot Bay that began in 2013 and is scheduled for completion in 2023. Similar to a number of New England’s Ports, The Elliot Bay Seawall was built between 1916 and 1934 and has exceeded its original design life. The original concrete seawall was built on approximately 20,000 timber piles.  Deterioration of the structure had led to instability of the seawall and the development of sinkholes behind it. The design and reconstruction of the new Elliott Bay Seawall incorporates several sustainable features, providing ancillary benefits to the area’s infrastructure, tourism, and environment.

The Waterfront Seattle Project replaces more than just the failing seawall; it improves quality of life for both marine life and humans, including a salmon migration corridor and new pedestrian access to the water. The budget for the project includes nearly $350 million for the following:

  • Stabilizing the existing soil and foundations with jet-grouted columns.
  • Installing precast concrete textured walls for the salmon migration corridor.
  • Installing a habitat bench along the wall to increase fish and marine life habitat.
  • Installing a sidewalk and pedestrian space with light-penetrating surfaces

Overview of the Textured Wall and Concrete Shelves (currently behind a temporary coffer dam) from https://waterfrontseattle.org/

What makes this engineering project truly unique is the focus on promoting sustainable and natural environmental growth. The new textured concrete walls will create a salmon migratory corridor where one has not existed for over 100 years. Textured shelves cast into the concrete walls allow plant and marine life to adhere to the wall. The walkway above the new corridor consists of glass bricks installed into precast concrete sidewalk panels that are able to support pedestrian traffic and allow sunlight to penetrate the sidewalk, promoting plant and marine growth below the walkway and on the wall. An intertidal bench, located in shallow water, will also be constructed to simulate a nearshore habitat.

Now fish, crustaceans, and plant life that would typically be found in and around the shallow natural shoreline of Elliot Bay can find their way back to an area that was previously inaccessible. Plants that could not grow in the deep waters along the original wall can thrive on the textured shelves and intertidal benches creating aquatic food for the marine life in the bay. Juvenile salmon that would typically avoid the shoreline of the previous wall due to the lack of light will use the new seawall as a migratory corridor.

As we look to rehabilitate our aged coastal infrastructure in New England, the Waterfront Seattle Project is a prime example of how we can sustainably build and rehabilitate an already established waterfront. A thoughtful and innovative approach can update critical infrastructure while simultaneously benefiting businesses, people, and marine life for years to come.

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Join Pare in Commemorating Dam Safety Awareness Day

By J. Matthew Bellisle, Senior Vice President of the Geotechnical Division of Pare Corporation and the Co-Chair of the Dam Management Committee of the Environmental Business Council of New England

Dam Safety Awareness Day was established to commemorate the lives lost in the Johnstown Flood. The tragedy occurred on May 31, 1889 when the South Fork Dam burst sending a flood of water that resulted in the destruction of 1,600 homes, $17 million in property damage (current value of approximately $425 million) and the deaths of 2,209 people (including the entirety of 99 families; of the deceased, 396 were children) in the valley below in Johnstown, Pennsylvania.  While this is the worst dam failure in the United States it has become symbolic in our history.  Unfortunately it is not the only incident of dam failure.

As we remember the lives lost and the heroes who worked to minimize damage and save lives, we also must remember the lessons learned in regard to dam engineering. We need to put our own hubris aside and recognize the impact that these engineered structures have on our communities and environment.

This country—especially New England—grew due to the power harnessed by dams during the industrial revolution, by the water impounded for irrigation and water supply, and by the additional navigation afforded by strategically placed and engineered dams and locks.  The dams that have greatly impacted our nation come in a multitude of forms–from concrete and earthen structures impounding large reservoirs, small earthen embankments and structures creating irrigation ponds, hydro-electric structures providing sustainable energy, to historic masonry structures from a time long past.  Our communities are surrounded by over 87,000 dams throughout the United States, which are a marvelous testament to our ability to engineer our surroundings to enable productivity, health, safety, and energy.

As today’ dams provide increasing levels of flood protection, energy, water supply, and environmental resource areas to support our communities, we need to remember three things.

  • First, dams do deteriorate over time. It would be incorrect to assume that the condition of the dam at any point in time will continue to represent the condition of the dam at some point in the future. There also comes a time when a dam is no longer providing a benefit and it should be removed.  It is only through continued diligence, observation, and maintenance that dams, bridges, roadways, and other parts of our national infrastructure will continue to serve the needs of the nation.
  • Second, financial resources are needed for routine maintenance and long-term repairs. However, just because money has been spent on the dam recently, the need for continued inspection by qualified personnel is still paramount to the long term performance of the dam.
  • Third, we are all stakeholders in continuing dam safety.  Ongoing steps to develop and maintain emergency action plans and procedures require support from our local communities to enable efficient notification, response, and recovery.

As we commemorate the Johnstown Flood let us take comfort knowing that dedicated regulators, designers and owners also remember these events and are taking positive steps to mitigate such incidents. Advances in the study of dam engineering have led to enhancements in hydraulic and soil modeling, which in turn have improved our understanding of the integration of the engineered environment with the natural environment. With the support of local and federal regulations we continue to protect the environment and the public by identifying and repairing aging dams, and removing those structures that are unsafe or no longer serve a beneficial purpose.  Ignoring complacency, we are taking positive steps to improve this nation’s dams and support the resources, opportunities and public which are so dependent upon these sometimes invisible engineered structures.

To learn more about dam safety and flooding, please download the two ebooks (‘Living with Dams: Know Your Risks’ and “Living with Dams: Extreme Rainfall Events’ prepared by the Association of State Dam Safety Officials (ASDSO) at  http://livingneardams.org/

The Return of Dams To The News Cycle

By J. Matthew Bellisle, Senior Vice President of the Geotechnical Division of Pare Corporation and the Co-Chair of the Dam Management Committee of the Environmental Business Council of New England

The recent events in California regarding the Oroville Dam have highlighted dams and how they impact our communities.  Like many of my colleagues, I have heard questions such as, “Why did the situation develop?”  “Why did it take so long to evacuate the downstream area?”  “Who is at fault?”  And the most frequent comment… “Why did the dam fail?”

First, due to the experience, efforts, and capabilities of those in positions of responsibility, the situation in Oroville has been stabilized.  Public officials worked tirelessly to mitigate the situation and ensure public safety throughout the emergency.

Second, I can only speculate when responding to questions about the structure of the dam, its maintenance, and its operation.  Answers to those questions will be provided as the waters recede, through forensic investigations and the review of historical records.

The question that most people are afraid to ask is:  “Can a similar scenario happen here in New England?”  Although our dams are smaller in this part of the county and, in the event of a potential failure would likely impact fewer people, the answer is “Yes.”  As one of the responding engineers, I remember well the week in October 2005 when a portion of downtown Taunton, MA was evacuated as an old mill dam threatened to release the flood waters resulting from nine days of record-breaking rainfall.  Our dams here in New England are integral to our communities.   They impound our drinking water, provide flood attenuation, and impact where and how we build.  But many are old—older than the Oroville Dam.

In New England, we have an appreciation for dams and the benefits they provide, while understanding the hazards that come with those benefits.   There are active Dam Safety programs in each New England state that have prescribed inspection schedules based upon the hazard potential for each dam.  Dedicated and knowledgeable dam safety professionals regularly complete inspections to ensure public safety. There are responsible dam owners that maintain their dams on a regular basis.

Many of the dam owners for whom we work understand the problems associated with the age of their dams.  Some have embarked on multi-year programs to improve their entire inventory of dams. Some have instituted a program of upgrades to meet design standards that were not in place when the dam was originally constructed.  Others have established programs to remove dams that are no longer beneficial and provide flood attenuation, water supply, and recreation through other means

These proactive steps are being taken to improve the condition of each dam, protect the environment, safeguard the resources around the dam, and shield the downstream public.  So as budget requests for dam repairs are presented, when emergency action plans are developed, and when disaster drills are conducted, remember the 160,000 individuals sitting in their cars below the Oroville Dam as they evacuated.  Please support these dam safety initiatives, as they will ultimately protect the communities where we work and live.