National Dam Safety Awareness Day

There are over 87,000 dams in the United States. With one-third of those dams posing a serious threat to people’s lives and property if they fail, dam safety is nothing to ignore. Dams are a critical part of our infrastructure providing flood protection, water supply, hydropower, irrigation, and recreation. Although dam safety may not seem to be a big concern, dam failure can affect people for miles and miles, with sometimes fatal results. National Dam Safety Awareness Day is a day to acknowledge the progress we have made in making our dams safe structures and the continuous progress we still have yet to make.

Damage caused by Lake Delhi Dam failure in Iowa, July 27, 2010
Damage caused by Lake Delhi Dam failure in Iowa, July 27, 2010

As our population keeps growing, our dams are getting older and some are even deteriorating. A dam can fail within hours of the first signs of breeching. Dam safety is a shared responsibility. Dam owners, engineers, community planners, along with federal and state leaders all have important roles in keeping dams running efficiently and safely.

The National Dam Safety Program (NDSP), led by FEMA, has been working for 30 years to keep Americans safe from dam failures. The NDSP assists states in establishing and maintaining dam safety programs along with providing technical training to state and federal dam safety staff. Their support for research and development has greatly helped raise awareness about improper dam safety along with lessening the impact on a community if a dam were to fail.

Why Dams Fail

One of the most frequent ways dams fail is overtopping. Overtopping is a strong indicator of an unsafe dam. This can happen due to a number of reasons but typically it is from inadequate spillway design, debris blockage, or settlement of the dam crest. Overtopping accounts for about 34% of all dam failures in the United States and can also lead to erosion of the downstream face of the dam. Without proper maintenance of the downstream face, the dam is at a heightened risk of failure. Wind and other harsh weather conditions can cause waves to erode the upstream face which can make the dam unsafe during heavy rainfall or flash floods.

Missouri River Flood: Breeching of the levee at mile 550 in Aitchison County, June 19, 2011
Missouri River Flood: Breeching of the levee at mile 550 in Aitchison County, June 19, 2011

Other important factors that can cause dam failure are seepage and foundation defects. These defects account for about 30% of dam failures in the US, typically due to slide failure. If seepage or other factors weaken the soil supporting a dam, the overall strength of the dam greatly diminishes, creating the potential for a landslide-like affect.

Improper construction measures such as insufficient soil testing also contribute to dam failures. When permeable cavities or course gravel are present in dam foundations, seepage is a big concern because it erodes the soil at a fast rate. This often results in the dam settling or sinking which causes failure. A dam can fail by water passing under, over, through, or around it. Every dam should be properly connected to the ground and constructed using the best materials and methods to meet current design and construction standards.

How to Prevent Failures

When constructing and maintaining a dam, taking the proper engineering steps is vital. For example, completing sufficient soil tests prior to construction helps ensure that the dam will be adequately supported. The soil on the actual site should be examined before any detailed planning is put into place. It is also important to confirm the existence of impervious clay to seal the excavation and form the core of the bank. Failures can be prevented if the contractor is aware of any soil limitations at the site.

Teton Dam failure, June 5, 1976
Teton Dam failure, June 5, 1976

Dam failures have taken the lives of hundreds of people in recent decades so it is important to hire the right contractors to do the proper work. Nothing can take the place of a reliable and reputable contractor. Having experienced engineers and machine operators greatly reduces the risk of failure. It is important to review every employee’s credentials before starting a job and to always seek professional advice from an engineer when planning and designing a dam. Improper construction and inspection can lead to a weak structure, which can be dangerous and, sometimes, even fatal.

Maintenance and inspection must be routinely completed in order to keep dams safe. If a problem associated with a dam is not addressed in a timely manner, it can become more dangerous as time goes on. Dam inspectors should document every inspection in order to accurately assess needed repairs. While maintaining a dam, vegetation control, erosion repair, and clearing debris from spillways should be a routine practice.  A healthy layer of grass can help prevent erosion, and any debris within 25 feet of the dam should be removed. A poorly maintained dam can cost the owner more to repair than a dam which is regularly inspected and checked for needed repairs.

Emergency Action Plans

Damage left behind after the Teton Dam failure, Rexburg, Idaho, 1976
Damage left behind after the Teton Dam failure, Rexburg, Idaho, 1976

173 dams across the country have failed since 2005 so it is important to know what your community’s Emergency Action Plan (EAP) is if a local dam were to fail. An up-to-date EAP is critical to reduce the risk of lost lives and property damage. A good EAP accomplishes three main goals: identify the area below the dam that would be flooded, establish a line of communication for the dam owner and emergency response, and provide warnings and evacuations to be conducted by local emergency teams. Below are the six essential elements of a successful EAP.

  1. Notification Flowchart. This is to identify who should be notified by whom, and in what priority. This information is crucial for the notification of the persons in charge of taking emergency actions. The flowchart should have detailed information about each position in the chart such as title, office, and multiple ways of contacting that individual. EAPs should include the residents and businesses downstream of the dam that should be notified in case of an emergency. Proper communication and assigned roles can drastically reduce the impacts of a dam failure.
  2. Emergency Detection, Evaluation, and Classification. This ensures that the appropriate course of action is taken based on the urgency of the situation. Having procedures in place to classify an emergency situation properly will better prepare a community to activate their EAP before a catastrophe occurs. Early detection of a potential problem can save hundreds of lives and millions of dollars in property damage.
  3. Responsibilities. When an emergency occurs, everyone should know their role in reacting to the situation. Typically, the dam owner’s responsibilities include developing, maintaining, and implementing the EAP while state and emergency management officials are responsible for warning and evacuation. Without proper assignment of responsibilities, the EAP would be ineffective.
  4. Preparedness. This section outlines actions to be taken before an emergency occurs. Preparedness actions are taken to moderate or minimize the effects of a dam failure and to identify specific responses to be taken in emergencies.
  5. Inundation Maps. An inundation map identifies the areas affected if a dam were to fail. This map is important in identifying a strategy to notify and evacuate areas in danger. These maps graphically display flooded areas and show travel times for wave front and flood peaks at critical locations.
  6. Appendices. This section contains information directly applicable to the actions of the dam owner and the emergency management parties. The appendices provide information that supports the material used to develop the EAP such as maintenance requirements and dam break investigations.

In Conclusion

Dams serve an important role in our nation’s infrastructure. Millions of people in every state rely on dams to bring them benefits such as flood control, water supply, irrigation, recreational areas, and renewable energy. Safe operation and maintenance is important to sustaining these advantages and avoiding disasters which are very often preventable.  Dams fail for a number of reasons but the primary source of failure is poor inspection and maintenance, inadequate design, and improper operation. Know your risk when it comes to dam failure in your community. Getting familiar with your community’s EAP and level of risk from a dam failure can greatly help you in an emergency situation. National Dam Safety Awareness Day is an opportunity to raise awareness about our nations deteriorating dams and to take steps in making them safer structures for our community.

Happy National Dam Safety Awareness Day!

Summertime, Beaches, and Water Quality

crowded-beach-300x225Memorial Day is the generally accepted start of summer to most New England communities. Pools are opened, grills are wheeled out from storage, flowers are planted, and beaches are officially opened. And while summer is absolutely breathtaking in New England, it is also a time of increased stress on water quality and supply.

Water Quality

Defined by the EPA as a sandy, pebbly, or rocky shore of a body of water, beaches provide recreation for approximately 100 million United States residents over the age of 16 each year. Families flock to beaches during the summer months to enjoy activities such as swimming, surfing, boating, fishing, parasailing, exploring, walking, and sunbathing. Beaches not only include the sandy expanses with boardwalks and cottage rentals along the coastline, but also lake and riverfront areas, ponds, estuaries, and lagoons, some of which are even found in urban areas. Beaches are also an integral part of the the United States economy and provide habitat to many species.

beach-closed-sign-300x139Unfortunately, because of the huge popularity of beaches in the summer, water quality can suffer. Beach closures are common during the summer months, and are a result of pollutants and pathogens entering the water. One of the most common sources of water pollution is human fecal matter from leaky septic systems and sewer overflows. Human waste contains a variety of harmful organisms, including bacteria, viruses, and parasites, that can cause illnesses such as gastroenteritis, hepatitis, and skin infection to humans. Another source of pollution is animal fecal matter from agricultural and stormwater runoff. While runoff contains a number of pollutants including motor oil, pesticides, fertilizers, and trash, arguably the most dangerous and disruptive is animal feces. A single gram of dog feces contains over 23 million parvovirus bacteria in addition to whipworms, hookworms, roundworms, threadworms, giardia, and coccidian. These pathogens and parasites enter waterways through runoff and can have detrimental effects on waterways, aquatic life, and humans.

Harmful algal blooms are toxic to marine life Image: U.S. Geological Survey, Dr. Jennifer L. Graham

Algal blooms are also more common in summer months. Algal blooms are caused by a variety of sources including warmer temperatures, high light, and increased turbidity, but the most contributive source is nutrients in the water from human and animal waste. Some algal blooms are extremely dangerous and have the potential to sicken or kill humans and animals, while less toxic blooms still cause harm to local economies and the environment. Commonly referred to as red tide, cyanobacteria, or blue-green algae, algal blooms effectively cause dead zones in the water and often require significantly increased treatment costs to remedy.

Water Supply

In addition to water quality issues at beaches, water supply can also be a concern. Since the population at popular vacation spots such as Cape Cod and the Maine beaches increases astronomically in the summer months, so does the demand for water. And not only are these seasonal visitors doing laundry, cooking, and drinking the water — they are also watering their lawns and gardens, which accounts for over half of a household’s total water usage. It is therefore understandable how a small community’s water supply can easily become taxed during the high summer season.


clean-water-act-300x169Fortunately, there are policies and regulations in place that directly address seasonal water quality and quantity issues. The EPA, along with other governmental agencies, have enacted several laws that aim to protect the quality of our nation’s beaches:

The Clean Water Act
The Clean Water Act, established by the EPA in 1971, establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters. Under the Clean Water Act, the following programs specifically address water pollution:

The National Pollutant Discharge Elimination (NPDES) Permit Program
The NPDES program controls water pollution by regulating point sources that discharge pollutants into waters of the United States.

The Pollution Budgeting (TMDL) Program
The TMDL program requires states, territories, and authorized tribes to develop lists of impaired waters, establish priority rankings for waters, and develop Total Maximum Daily Loads (TMDLs). TMDLs related to beaches include pathogens, nutrients, and trash.

The Beaches Environmental Assessment and Coastal Health (BEACH) Act of 2000
The BEACH Act amends the Clean Water Act to better protect public health at our nation’s beaches. The BEACH Act requires EPA to recommend water quality criteria that states, territories, and tribes can adopt into their water quality standards for pathogens and pathogen indicators in coastal recreational waters. The BEACH Act also authorizes grants to states, territories, and eligible Tribes to monitor coastal and Great Lakes beaches and to notify the public when water quality standards are exceeded.

Marine Debris Research, Prevention, and Reduction Act (MDRPRA)
The MDRPRA established programs within the National Oceanic and Atmospheric Administration (NOAA) and the United States Coast Guard (USCG) that identify, determine sources of, assess, reduce, and prevent marine debris. MDRPRA also reactivates the Interagency Marine Debris Coordinating Committee, chaired by NOAA.

The Coastal Zone Management Act
The Coastal Zone Management Act is administered by NOAA, Office of Ocean and Coastal Resource Management (OCRM), and provides for management of the nation’s coastal resources, including the Great Lakes.

The Act to Prevent Pollution from Ships (APPS)
The APPS implements the provisions of Marpol 73/78, the International Convention for the Prevention of Pollution From Ships, 1973 as modified by the Protocol of 1978. (“Marpol” is short for marine pollution.) In 1987, APPS was amended by the Marine Plastic Pollution Research and Control Act. The MPPRCA requires EPA and National Oceanic and Atmospheric Administration (NOAA) to study the effects of improper disposal of plastics on the environment and methods to reduce or eliminate such adverse effects. MPPRCA also requires EPA, NOAA, and the U.S. Coast Guard (USCG) to evaluate the use of volunteer groups in monitoring floatable debris.

Shore Protection Act (SPA)
The SPA is applicable to transportation of municipal and commercial wastes in coastal waters. The SPA aims to minimize debris from being deposited into coastal waters from inadequate waste handling procedures by waste transporting vessels. EPA, in consultation with the Coast Guard, is responsible for developing regulations under the SPA.

Marine Protection, Research, and Sanctuaries Act (MPRSA)
The MPRSA, also called the Ocean Dumping Act, generally prohibits the following:

  • Transportation of material from the United States for the purpose of ocean dumping;
  • Transportation of material from anywhere for the purpose of ocean dumping by U.S. agencies or U.S.-flagged vessels; and
  • Dumping of material transported from outside the United States into the U.S. territorial sea.

In addition to the numerous governmental regulations protecting water quality and our nation’s beaches, local communities also implement policies that specifically aim to address water supply issues. Some of these include the following:

  • water-banOutdoor water restrictions and bans: Many communities implement water bans in the summer that severely limit or prohibit outdoor watering.
  • Public education: Many summer communities implement public outreach that includes requests for voluntary conservation.
  • Leak detection and repair: Because water loss is such a serious issue across the United States, many communities are actively implementing leak detection and repair policies. Repairing older infrastructure typically has an exponential return on investment and also serves as a means of public education, with repair crews in the street garnering local media attention.

In Conclusion

dog-sign-201x300Beaches are one of the most traditional and enjoyable means of summer entertainment for families and individuals, and they provide a plethora of recreational activities for all ages. Protecting our beaches and recreational waters is imperative to the health of our nation’s citizens and economy, and we are fortunate that our nation’s governmental agencies and local communities proactively work to maintain the health of our waters. We as individuals can also help to protect our beaches and waterways by reducing our personal water consumption, cleaning up after our pets, and being mindful of pesticide and fertilizer usage. Together, we can assure that present and future generations are able to enjoy our nation’s beautiful beaches.

Surf’s up!

Infrastructure Week 2016 — #InfrastructureMatters

Logo_IW_Small-1024x416It is scary to realize how complacent our country has become in accepting crumbling infrastructure as the norm. Our international competitors are investing more in high speed rail, modern airports, and bigger shipping ports, while just about every few months, some kind of preventable catastrophic infrastructure event happens in America. Yet our leaders are still not spurred into taking decisive action.

Infrastructure matters. It matters, in big ways and in small, to our country, our economy, our quality of life, our safety, and our communities. Roads, bridges, rails, ports, airports, pipes, the power grid, and broadband — infrastructure matters to companies that manufacture and ship goods. It matters to our daily commutes and our summer vacations. Infrastructure determines if we can drink water straight from our taps and flush our toilets or do our laundry. It brings electricity in to our homes. Ultimately, infrastructure matters to every aspect of our daily lives.

That is why Tata & Howard has teamed up with hundreds of other groups around the country to participate in Infrastructure Week 2016. We’re raising awareness about the need to invest in infrastructure, which is the backbone of our economy, locally and nationally.

Every year America fails to adequately invest in our infrastructure, the United States becomes less competitive, our economy grows more slowly, and families and businesses lose valuable time and money. The goods we manufacture cost more when they get stuck on congested highways, rerouted around structurally deficient bridges, and stranded at outdated ports. Continued reliance on World War II era technology and airports that lack sufficient capacity cause U.S. consumers to skip travel, costing the economy tens of billions of dollars each year.

Water main break
Water main break

Particularly in the northeast, water and wastewater infrastructure has reached the end of its useful life. A water main breaks every two minutes, and we have seen the tragedy that can come from utilizing outdated technology, such as lead pipes in Flint, Michigan. And, our failure to invest in infrastructure ripples throughout the economy: for every $1 invested in infrastructure, $2 in output is created – putting our friends and neighbors to work.

Decades of underfunding and deferred maintenance have pushed our country to the brink of a national infrastructure crisis. And we have begun to accept preventable tragedies as normal, when they should in fact be entirely unacceptable: fatal mass transit accidents; deadly, poisonous drinking water; sickening gas leaks; levee-breaking floods; deadly pipeline bursts; and rivers contaminated with raw sewage. America’s poorly-funded infrastructure and transportation systems can be more than just inconvenient; they can be harmful to our health and safety. Importantly, all of these tragedies are preventable with adequate investment – they are not merely unfortunate accidents we must endure.

Traffic in Stamford, Connecticut
Traffic in Stamford, Connecticut

Every dollar we invest in infrastructure is an investment in our neighborhoods and our future. Because our roads are in poor condition and littered with potholes, U.S. drivers pay more than $500 in avoidable vehicle repairs and operating costs each year. In Connecticut, the areas of New Haven, Bridgeport, and Stamford have had 45% of their roadways rated “poor” by TRIP, a Washington, D.C.-based national transportation research group. Instead of wasting over 40 hours each year stuck in traffic jams, we could spend that time being productive.

Americans deserve a 21st century transportation network; modern aviation systems; safe, clean, reliable water and wastewater service; broadband access in every community; and, a freight network and ports that can keep pace in the global economy. To grow our economy, keep Americans safe, and maintain strong communities, we need all levels of government and the private sector to work together to prioritize the rebuilding of our nation’s infrastructure.

tap-water-drop-225x300During Infrastructure Week, groups are coming together to recognize progress and leadership at the federal, state, and local levels – and there is much to celebrate. For example, communities throughout New England have been proactive in lead service line replacement, and the Massachusetts Water Resources Authority (MWRA) announced in March that $100 million in interest-free loans would be made available to its member water communities to fully replace lead service lines.

But our work is nowhere near complete. As we look to 2016 and beyond, closing our country’s trillion-dollar infrastructure investment gap demands a strong federal partner in funding large and transformative projects. We are going to need real collaboration between the public and private sectors to identify and implement innovative solutions. And leaders at all levels are going to need to finally wake up and commit to building a long-term, sustainable plan to invest in America’s infrastructure. There is too much at stake to fail at any of this. Infrastructure matters.

2016 Small MS4 Stormwater Permit for Massachusetts and Stormwater Collaboratives Workshop a Huge Success

Screen Shot 2016-05-19 at 2.42.04 PMOn Wednesday, May 18, 2016, the Association to Preserve Cape Cod (APCC), the Barnstable Coastal Resources Committee, the Cape Cod Commission, and the Massachusetts Bays National Estuary Program hosted a free workshop entitled “2016 Small MS4 Stormwater Permit for Massachusetts and Stormwater Collaboratives.” The event, which was very well attended, was held at Cape Cod Community College and featured several presentations, including the keynote by Mr. Newton Tedder, MS4 Program, Region 1, US EPA, on “2016 Final Massachusetts Small MS4 General Permit for Stormwater.” Mr. Tedder, a key contributor to the revised permit, was available for questions. Also presenting at the workshop were Tata & Howard’s Stormwater Manager Jon Gregory, P.E., and Cherry Valley & Rochdale Water District Superintendent Michael Knox. Both Jon and Mike presented on the Central Massachusetts Regional Stormwater Coalition (CMRSWC), of which the Town of Leicester — which includes the Villages of Cherry Valley and Rochdale — is a member. The presentations included information which provided an overview of the CMRSWC as well as specific products and benefits. Congratulations to both Jon and Mike for their presentations, which provided clear and compelling data on the value of a regional stormwater collaborative.

James Hoyt Joins Tata & Howard as Senior Project Engineer

James Hoyt Joins Tata & Howard as Senior Project Engineer

James V. Hoyt IV, P.E.
James V. Hoyt IV, P.E.

MARLBOROUGH, MA, MAY 18, 2016Tata & Howard, Inc., a leading innovator in water, wastewater, stormwater, and environmental services engineering solutions, is pleased to announce that James V. Hoyt IV, P.E., has rejoined the firm as a Senior Project Engineer. Hoyt brings over nine years of concentrated wastewater engineering experience to Tata & Howard, including his prior experience with the firm from 2007-2013. He will be a team leader in the wastewater division.

“Our continued growth led us to look for a key addition to our wastewater team,” commented Jack O’Connell, P.E., LEED AP, Senior Vice President. “Having worked with James in the past, we knew both the quality of his engineering work as well as the quality of his character, and we feel fortunate that he has rejoined the team in this increased capacity.”

“I am thrilled to be back at Tata & Howard,” stated Hoyt. “I look forward to working with the team to further enhance their already robust wastewater division, and to contributing to the significant growth the company has been experiencing the last few years.”

Hoyt holds a Bachelor of Science in Civil and Environmental Engineering from the University of Massachusetts, Lowell, and is a registered Professional Engineer in the Commonwealth of Massachusetts.

A History of Dams: From Ancient Times to Today

A dam is a human-made structure that is primarily used to hold back water. Dams are constructed for many purposes, including reservoir creation, flood prevention, irrigation, and hydroelectric power. Today, there are almost 50,000 large dams in use worldwide. The United States has the second largest number of dams in the world at 5,500, and China has the most with a whopping 19,000. The United States has 50 major dams – the most in the world. But before we had the Hoover Dam or any of the other major dams of today, our ancestors had to learn about dam engineering, and some of that was done through trial and error.

The World’s First Dam

jawa-300x225The first known dam to be built is the Jawa Dam, which is actually the largest in a series of dams that are all part of one reservoir system. Located in modern-day Jordan, the Jawa Dam was originally constructed around 3,000 BCE in what was then Mesopotamia. Surprisingly, the Jawa Dam was actually an architectural feat of the times. While most ancient dams were simple gravity dams constructed of gravel and masonry, the Jawa Dam was reinforced with rock fill behind the upstream wall in order to protect the wall from water pressure breach. This safety feature was incredibly innovative for this time period. Unfortunately, the reinforced design was forgotten after the Jawa Dam and was not actually “reinvented” until modern times. The Jawa Dam site is arguably the most important archaeological site in the history of large-scale water projects, and the dam itself was so well designed and constructed that the ancient structure stood until just a few years ago, when it was partially ruined due to physical intervention. In its prime, the Jawa Dam was 15 feet tall, 80 feet long, with a base of 15 feet. It created the Jawa Reservoir that had a capacity of 1.1 million cubic feet.

Ancient Dams

Remains of the poorly designed Sadd el-Kafara
Remains of the poorly designed Sadd el-Kafara

Subsequent ancient dams were built by several cultures with varying rates of success. Approximately 400 years after the construction of the highly successful Jawa Dam, Egyptians built the Sadd el-Kafara, or Dam of the Pagans, most likely to supply water to the local quarries outside of Cairo rather than for irrigation, since the flooding Nile would have supplied plenty of water to the farmers. After ten years of construction, the masonry dam was 37 feet tall, 348 feet long, with a base of 265 feet, contained over 100,000 tons of gravel and stone, and had a limestone cover to resist erosion. Unfortunately, as it was nearing completion, it failed. Due to poor design and lack of a spillway, the dam washed away during a heavy rainfall and was never repaired or completed. Discouraged by the failure of this massive project, ancient Egyptians were dissuaded from constructing other dams until many years later.

The Romans, highly regarded for their advances in hydraulic engineering, were prolific in dam construction during the height of the empire. In addition to the vast network of aqueducts, the Romans built a plethora of gravity dams, most notably the Subiaco Dams, which were constructed around 60 AD to create a pleasure lake for Emperor Nero. The Subiaco Dams were a series of three gravity dams on the Aniene River in Subiaco, Italy, the largest of which stood 165 feet tall and held the honor of being the tallest dam in the world until its destruction in 1305, historically attributed to two careless monks. The Romans also constructed the world’s first arch dam in the Roman province of Gallia Narbonensis, now modern-day southwest France, in the 1st century BCE. The remains of the Glanum Dam, the first recorded true arch dam in history, were discovered in 1763. Unfortunately, a modern arched gravity dam replaced the ancient structure in 1891, and all remnants of the Glanum Dam were lost. The Romans were also responsible for constructing the world’s first buttress dams, although they tended to fail due to their too-thin construction. One third of all dams on the Iberian Peninsula were buttress dams.

The Cornalvo Dam, a Roman gravity dam in built in the 1st or 2nd century AD, still supplies water to the people of Meriden, Spain.
The Cornalvo Dam, a Roman gravity dam in built in the 1st or 2nd century AD, still supplies water to the people of Meriden, Spain.

Asian cultures also contributed to dam engineering. As early as 400 BCE, Asians built earthen embankments dams to store water for the cities of Ceylon, or modern-day Sri Lanka. In the 5th century AD, the Sinhalese built several dams to form reservoirs to catch the monsoon rains for their intricate irrigation system, and many of these reservoirs are still in use today. Around the 12th century AD, about 4,000 dams were built by an egotistical Sinhalese ruler, King Parakrama Babu. While these structures were gargantuan for the time, such as one dam that stretched for almost nine miles, they are not considered to have any true engineering significance, as they did not supply water to the villages. Built to massage the king’s giant ego, these enormous dams were monuments rather than functional structures.

Japan and India also contributed to early dam engineering, with much success. In fact, five of the ten oldest dams still in use are located in these two countries. The oldest operational dam in the world, the Lake Homs Dam in Syria, was built around 1300. The masonry gravity dam is over one mile long, 23 feet high, and creates Lake Homs, which still supplies water to the people of Homs today.

Middle Ages

William John Macquorn Rankine
William John Macquorn Rankine

During the dark ages, dam construction came to a near halt, resuming around the 15th century AD. During this time, no major contributions to dam engineering were made, and the majority of the dams constructed in Europe, where rainfall is plentiful and regular, were modest structures. It wasn’t until the 1850s, when civil engineering professor William John Macquorn Rankine at Glasgow University demonstrated a better understanding of earth stability and structural performance, that dam engineering improved. In fact, Rankine’s work was so innovative, it contributed to the acceptance of civil engineering as a valid university subject and improved the status of civil engineers. Since Rankine, geological, hydrological, and structural scientific contributions have been extensive, and the understanding of dam engineering has improved significantly as a result.

Modern Times

Major advances in concrete dam design were made from 1853 to 1910 by British and French engineers. During this time, understanding of the relationship between the precise weight and profile of gravity dams and the horizontal thrust of water increased extensively. In 1910, further advances were made as engineers began to take a more three dimensional approach to dam engineering, examining the effect of individual stresses and deflections on multiple points rather than on the structure as a whole. By recognizing the complexity of the structure and understanding its interconnectedness, engineers were able to make exponential advances in dam engineering. As a result of this enhanced understanding, model techniques were implemented at this time. Originally built in rubber, plaster, plasticine, or concrete, modelling is now also done digitally, allowing multi-faceted and comprehensive testing and examination of structural stability.

The Hoover Dam

The world’s largest and most complex dams have all been built within the last century, due to engineering as well as technological advances. In addition to supplying water and controlling flooding, modern dams are often constructed to provide hydroelectric power. The Hoover Dam, a concrete arch-gravity dam constructed in the Black Canyon of the Colorado River in 1936, is a prime example of the major advances made in dam engineering. The massive dam, which impounds Lake Mead, stands a whopping 726 feet tall and has a reservoir capacity of 28,537,000 acre feet. It also provides four billion kilowatt-hours of hydroelectric power — enough to supply the private and public electrical needs of over eight million people in Nevada, Arizona, and California— each year. Once the tallest dam in the world, the Hoover Dam lost its title to Switzerland’s 820-foot-tall Mauvoisin Dam in 1957. In the United States, California’s Oroville Dam is now the tallest at 770 feet.

Looking Forward

Workers dismantle the Savage Rapids Dam on the Rogue River in Oregon. (Photo courtesy of Oregon State University)

While dams have been being constructed for over 5,000 years, the last 100 years have seen the most significant contributions in dam engineering. With the increased understanding of earth sciences comes the realization that some dams are actually detrimental to the earth’s ecology. Because of this knowledge, over 900 dams in the United States have been removed since 1990. Also, the understanding of dam safety has made significant strides over the last 100 years, and dam safety programs have been implemented in 49 of the 50 US states — only Alabama has no dam safety program. Of those 49 states, all but eight also require that all significant and high hazard dams require Emergency Action Plans (EAPs).

With the tens of thousands of existing large dams throughout the world, and the ever-increasing demand for water and power, dams will continue to make a significant impact on modern day life. And, as is evidenced by history, dam engineering will continue to evolve as additional innovations, discoveries, and technological advances are made.

Tata & Howard Participates in 17th Annual Earth Day Charles River Cleanup

Tata & Howard Participates in 17th Annual Earth Day Charles River Cleanup


On April 30, 2016, T&H employee owners participated in the 17th Annual Earth Day Charles River Cleanup
On April 30, 2016, T&H employee owners participated in the 17th Annual Earth Day Charles River Cleanup

MArLBOROUGH, MA, MAY 4, 2016Tata & Howard participated in the 17th Annual Earth Day Charles River Cleanup on Saturday, April 30. The event drew over 3,000 volunteers who helped pick up trash, remove invasive species, and assist with park maintenance. Tata & Howard team members were assigned to remove trash from the Dedham section of the riverbank.

“We were thrilled to be a part of the Charles River Cleanup,” said Karen Gracey, P.E., Vice President of Tata & Howard, who also participated in the event. “As an environmental engineering firm, one of Tata & Howard’s primary objectives is clean water. Volunteering at the Charles River — enjoyed by many of us at Tata & Howard as an area of prime recreation — directly enhances that effort.”

The Annual Earth Day Charles River Cleanup, organized through the Charles River Watershed Association, is part of the American Rivers’ National River Cleanup, a nationwide annual event focused on removing trash from America’s waterways. Originally launched in 1991, National River Cleanup has grown astronomically and now encompasses over 6,000 cleanups involving over 1.3 million volunteers nationwide. Since the inception of National River Cleanup, over 20 million pounds of trash and debris have been removed from America’s rivers.

“We are proud to be part of a national community that actively participates in bettering our environment, and we look forward to participating in additional river cleanups in the future,” added Gracey.

For more information on the National River Cleanup or to find a local cleanup, visit