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James McKellar
By James McKellar
Schulich School of Business

Cities have been the engines of prosperity and the elixir for new ideas for centuries. They are associated with the rise of democracy in ancient Greece, the Renaissance in Italy, and the Industrial Revolution in 17th and 18th century England. Cities today are healthier, wealthier and more alluring than any time in history.

They attract the poor and provide the clearest path from poverty to prosperity. Historically, cities have triumphed, but, today, the urban footprint is overwhelming the environment, represents squalor in many parts of the world, and has come to accentuate the divide between the haves and have-nots. For the first time in the history of mankind, more than half of the world’s population now calls a city home. Within a few decades, 5 billion people will live in cities. Very soon, 500 cities around the world, most of them in Asia or Africa, will each contain more than 1 million people.

By 2025, China’s urban population will reach 926 million, having added 325 million people, including 230 million migrants, according to McKinsey Global Institute. By 2030, more than 1 billion people will reside in China’s cities, growth that is equivalent to the building of 54 new cities, each the size of the Greater Toronto Area.

As India and China get richer and hasten their pace of city building, their urban dwellers face choices that could dramatically alter our lives. Building sustainable cities in both developed and developing worlds will be among the most important issues of the 21st century. It is time to get our own house in order and set examples to ensure prosperity for all, whether through innovation, reduced consumption, mitigated environmental damage, or recovery from a growing incidence of extreme weather events such as flooding, drought, and fires.

North Americans enjoy a relatively high standard of living. But what happens if the rest of the world wants what we now have? With only 5% of the global population, we fuel our lifestyle using 30% of the world’s natural resources. Such excessive consumption of land and other resources is not sustainable.

North Americans are the leaders in the consumption of oil at a rate of about 7,500 kilograms per person per year, according to the World Bank. By comparison, this figure is about 3,000 kg in Denmark, 1,500 kg in China, and 500 kg in India. In terms of impact, the average North American emits about 16 metric tons of CO2 each year, compared with the Danes’ eight metric tons, less than six in China and less than two in India. The question remains: Who will trend up, who will trend down, by how much, and when?

When it comes to water, we see the same disparity. North Americans use more than 4,000 litres per person per day, compared with 1,800 litres in India, about 1,200 litres in China, and remarkably, less than 500 litres in Denmark. Only 0.5% of the world’s water is available and potable, 97% is seawater, and the remaining 2% is frozen. Water and food, not energy, may precipitate the most profound crises of the 21st century and be the most significant constraint on urban growth.

What is a city?

A city is the absence of physical space between people and companies. As Edward Glaeser, of Harvard University and author of The Triumph of Cities, has observed, a city is proximity, density and closeness. Cities enable us to work and play together and their success depends upon the demand for physical connection to move people, things and services.

However, the planet, as a whole, is fast becoming suburban, rather than strictly urban. In the emerging world, almost every metropolis is growing in size faster than its population is increasing.

Cities are becoming less dense, as New York University’s Shlomo Angel tells us. Chicago in 1920 had 59 people per hectare and that figure is now just 16. Beijing’s population density has dropped from 425 people per hectare in 1970, to 59 people per hectare today. As people become wealthier, they consume more space, just as they consume more energy, more goods, and more services. Wealth drives sprawl in both developed and developing countries. Can this be reversed?

Our consumption of housing underscores this trend. In Canada, in 1950, we consumed 300 square feet per person (3.38 persons per household) and that figure is now closer to 1,000 square feet per person (occupancy is now fewer than 2 persons per household). This amounts to more than a three-fold increase in just two generations. We have become a collector of things and our homes have become our storage lockers. How much stuff do we really need?

For North Americans, the car has become synonymous with urban life. Yet, most of our cars are parked 96% of the time, 86% the fuel never reaches the wheel, and less than 1% of the energy is used to move the driver. Today, there are some 1.2 billion cars on the road worldwide, a figure that is expected to double to 2.4 billion by 2030, according to McKinsey.

The issue of mobility is compounded by the space required and the costs involved. The car is the second largest expense for any household after housing. The average North American family spends 32% of disposable income on the house and 19% on the car. Should we not combine the cost of the house and the car when addressing affordability?

Climate change and cities

A complicating factor in all of this is climate change. A report just released by the Rand Corp. and commissioned by the U.S. Department of Homeland Security’s Office of Infrastructure Protection, shows climate change has the potential to severely impact U.S. infrastructure. It lists several perils that may be exacerbated by climate change, including tornadoes, hurricanes and storm surge. The one with possibly the biggest potential impact is drought, claim the authors. Oftentimes people think of disasters as largely a coastal phenomenon, however, the authors found potential impacts from rivers flooding, and wind and ice storms, among other perils, faced by people living far from the coast. Climate change is a global phenomenon destined to severely impact cities across the globe – the very cities that are giving rise to the perils of major natural disasters.

This is but a sample of the issues we face in moving forward with our exercise in city building during the age of urbanization. If the North American city is not the prototype for the future, what is? Solutions likely lie in the realm of human collaboration that first drove the creation of cities and served as the foundation of civilization’s successes.

Through collaboration can we begin to make our cities the engines of innovation and the marketplace for new ideas? What changes might we consider and where can we start?

  • Make big cities better places to live at substantially increased densities by growing up as well as out.
  • Pursue strategies for inclusive, affordable urbanization that provides a cross section of social, economic and environmental benefits for all residents.
  • Solve the mobility challenge with new models of transportation that can ensure efficient movement of people, goods and services.
  • Replace obsolete models of infrastructure that are no longer sustainable in an age of urbanization and resource constraints.
  • Focus on ways that industry can intelligently meet the demand for more livable and sustainable communities, using new technologies and new business models.
  • Make the city itself a renewable resource, addressing the production of food and energy and the efficient use of water.

James McKellar is the Academic Director of the Real Estate and Infrastructure Program at Schulich School of Business. This article appears in ES&E Magazine’s December 2016 issue.

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ESA reserve land valley
By Keli Just

Select First Nation communities across Canada have chosen to join the First Nations Land Management Regime (FNLM). The FNLM Regime operates under the Framework Agreement on First Nation Land Management, which is a government-to-government agreement that was ratified by Canada in 1999.

The main goals of the FNLM Regime are to facilitate the creation of a streamlined and enhanced economic development climate on reserve lands, while maintaining a high level of environmental protection and stewardship. The Framework Agreement provides signatory First Nations with the option to manage their reserve lands under their own Land Codes. Until each of these First Nation communities develops and approves a Land Code to take control of its reserve lands and resources, federal administration of their reserve lands continues under the Indian Act.

PINTER & Associates Ltd. (PINTER) provided technical engineering expertise, environmental program development and legal framework guidance for FNLM Regime member Nations. Innovative techniques were developed during environmental site assessment (ESA) work to nurture community engagement, collect information from various sources, gather oral history, carry out site inspections, manage the information and data, and to prioritize sites requiring further work.

The technical engineering principles involved in environmental assessment, remediation, and development of laws and regulations governing the environment and land development were the foundation of this process.

PINTER has assisted 12 member Nations to date through various aspects of this process. There are currently a total of 128 First Nations across Canada that are members of the Framework Agreement and FNLM Regime. Sixty-one of those Nations have their own Land Code and are responsible for their lands under the Framework Agreement. There are also approximately 61 other Nations that have expressed interest in joining the process and Regime.

diagram
Environmental management and protection program.

Goals of the First Nations Land Management Regime

Each First Nation has varying objectives for the FNLM process, but the overall goals are similar and include: assessment, identification and remediation of environmental impacts on reserve land; engaging the community to determine environmental and economic priorities; and identifying traditional practices and customs that relate to environmental stewardship.

The development of a comprehensive environmental management and protection regime, development of environmental assessment and protection law regimes and a sustainable, appealing economic development climate on reserves are goals shared by member communities.

Environmental Site Assessments

Through the FNLM Regime process, First Nations can opt out of the land provisions of the Indian Act and regain authority and control of their lands from the federal government. The land is to be transferred to each Nation in as close to pre-impact condition as possible. To achieve this goal, PINTER works with communities to complete the required ESAs for each reserve. The environmental assessment includes a Phase I assessment, Phase II investigation and delineation work, and the Phase III remediation of identified impacts on reserve lands.

Phase I ESA

garbage-dumping-site-for-assessment
Environmental assessment work at a dumpsite/burn site.

The Phase I ESA involves assessment of every building and development on reserve, including cursory inspections of each residential septic system. Each active and historical dumpsite and ravine dump, fuel storage site, historical bluestone pit (fence post treatment) operation, vehicle salvage yard, agricultural chemical storage location, and culturally significant site identified by the community is visited, visually assessed, and catalogued. Typically, several hundred residences exist on reserve and each yard is visited and visually assessed during the Phase I ESA.

The results are presented to the community to allow each Nation to decide whether or not to proceed further with the process. Contrary to typical ESAs, this type of project has to consider cultural customs, taboos and sensitivities, as well as develop an efficient method of obtaining historical information from the community, including from seniors and elders.

Phase II ESA

The majority of the Phase I ESAs that PINTER has completed have been followed up by the completion of limited and detailed Phase II ESAs. Based on the findings of the Phase I ESA, a prioritized list of potentially impacted sites on reserve is developed.

A variety of environmental contaminants have been encountered during the Phase II ESA work. These include petroleum hydrocarbons (PHCs), copper sulfate, metals, dioxins and furans, livestock waste and human waste effluent, agricultural chemicals, mould and fungus, asbestos, mercury and polychlorinated biphenyls.

Phase II ESA work includes environmental drilling and soil sampling, groundwater monitoring, well installation and groundwater sampling, test pit excavation, surface water sampling, and hand auger soil sampling. While each sampling technique is not unique, applying them all to one project to ensure the investigation is efficient and cost-effective requires an innovative approach and consistent overview of long-term goals.

Phase III ESA

Once identified environmental impacts have been delineated and quantified, remediation is carried out. PINTER utilizes a variety of recognized methods to clean up impacts to federal Canadian Council of Ministers of the Environment (CCME) and Health Canada guidelines for both soil and groundwater.

Both in situ and ex situ techniques and pro­cesses are employed to remediate identified impacts. Excavation and on-site remediation of PHC impacted soils via landfarming techniques has been completed at numerous locations. Efforts are made to return reserve land back to pre-impact conditions, while working within available federal funding constraints. Remediation of impacts on reserve land helps to enhance sustainability and empower each community to take responsibility for their future actions.

The ESAs and remediation of legacy sites also provide context and examples to First Nation Band Councils of negative environmental impacts, increasing their understanding of proper environmental stewardship and practices.

Environmental Management and Protection Program

Once First Nations assume control over their lands, they have the daunting task of developing a comprehensive environmental protection framework and environmental law regime. Each Nation is tasked with managing and directing business development, utilization of natural resources, and protection and assessment of their lands. Management and operation of an environmental regime is a complex undertaking that involves many stakeholders and affects both on and off reserve residents.

The mechanism typically chosen by First Nations is an Environmental Management and Protection Program (EMPP). These are essentially operational guides for First Nations that incorporate all aspects of a Nation’s environmental protection and law regime. The foundation for each EMPP consists of the environmental knowledge gained during the ESA process, the community’s environmental goals and priorities, each Nation’s traditional knowledge and practices, and the First Nation’s Land Code.

Environmental Protection and Assessment Law Regime

First Nations under the FNLM Regime are also required to develop an Environmental Protection and Assessment Law Regime to regulate and manage economic development and resource utilization on reserve land. Nations have three options for law regime development: full adoption of provincial legislation, hybrid adoption of provincial legislation, or development of unique Nation-specific laws and regulations. Environmental regulations on reserve need to meet or exceed existing provincial and federal legislation in place within the province each Nation is located.

Environmental Assessment (EA) law and processes are required to either meet or exceed existing federal EA laws. Establishment of Nation-specific EA laws and structure helps to ensure that potential impacts to the environment are identified and steps are taken to properly mitigate these prior to development approval.

The environmental protection regimes and environmental law regimes developed through this project for First Nations are based on recognized environmental engineering principles and established provincial and federal environmental legislation.

Considerable effort is employed to harmonize each Nation’s EMPP with their developed environmental law regime to ensure continuity between the two processes and facilitate efficient management of each Nation’s environmental regime.

Project challenges and complexities

As with any undertaking, there are challenges that arise during the multiple phases of these projects. Numerous components to this process can span several years of assessment and development, which lead to various complications and issues. Working with multiple First Nations simultaneously, each with their own community and environmental issues, perspectives, priorities and political agendas, was a challenging aspect of this process for PINTER and for many consultants.

Maintaining a consistent approach through governmental mandate changes and balancing First Nation expectations with government agency mandates were also challenges during this process.

Other project challenges included addressing a variety of environmental liabilities accrued over the years on First Nation land, developing community engagement programs, meeting First Nation expectations, and helping the First Nation develop a land management process. Existing environmental site assessment techniques were adapted for this type of project and new techniques were developed.

Social and economic benefits

An underlying goal for this type of project and the First Nations Land Management Regime is to provide member Nations with the ability to easily and effectively facilitate and manage economic development on reserve land. The ultimate benefits are vibrant, self-sustaining First Nation communities that contribute to Canadian society and the Canadian economy.

There are numerous social and economic benefits to First Nations Land Management Regime member First Nations and to surrounding local and provincial jurisdictions. The outcome grants First Nations greater freedom for development on their land, including business and investment on reserve, and for First Nation entrepreneurialism and employment opportunities for Band members.

Keli Just, P.Eng. is with PINTER & Associates Ltd. This article appears in ES&E Magazine’s December 2016 issue.

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Claude “Bud” Lewis Carlsbad Desalination Plant
Aerial view of the Claude “Bud” Lewis Carlsbad Desalination Plant in California.

By Boaz Keinan

In December 2015, IDE Technologies opened the largest desalination plant in the Western Hemisphere. The Claude “Bud” Lewis Carlsbad Desalination Plant is in California, a region which has been threatened by extreme drought in recent years. Developed and owned by Poseidon Water, the plant overcame significant practical, regulatory and economic hurdles to deliver a cost-effective and environmentally-friendly water supply to 300,000 residents and businesses in San Diego County.

The Carlsbad plant taps into the largest reservoir in the world – the Pacific Ocean. It uses the seawater reverse osmosis (SWRO) technique to produce more than 204 million litres of drinking water per day. In reverse osmosis, pumping energy moves seawater through a series of filtering membranes with pores that let water molecules permeate but retain salt and debris. Utilizing a proprietary design, the plant has implemented a minimal number of independent trains fed by both feed pumping centers.

The plant is located adjacent to the Encina Power Station, so project financing relies on a true partnership model. It shares the existing intake and outflow systems with the Encina Power Station and takes up to 420,000 m3 per day of cooling water from the power plant. The water is then filtered through gravel and sand to reduce particulates, before going through reverse osmosis filtration.

Half of the saltwater taken into the plant is converted into pure potable water and the rest is discharged as concentrated brine. The outflow of the plant is put into the discharge from the power plant for dilution, for a final salt concentration about 20% higher than seawater. Desalination plants primarily discharge water with about 50% extra salt. This leads to dead spots in the ocean as the super-saline brine does not mix well with seawater.

Intake

Seawater from the Encina Power Station discharge channel flows through the intake vault and common inlet line and is distributed to the intake pumps. The intake vault is adjacent to the power station discharge channel and is equipped with a stop log for isolating the intake pump station from the channel during heat treatment of the power station cooling system, or for maintenance purposes. The seawater pumping station includes three vertical intake pumps: two operating and one stand by. Each intake pump provides up to 216 million litres/day. The intake station includes seawater quality monitors that allows online monitoring of the raw seawater quality.

Pre-treatment and post-treatment processes

Pretreatment is composed of a flocculation stage and a gravitational dual media filter stage. Pretreatment feed flow is controlled by the four flocculation chamber flow control valves. Coagulant and flocculant are added to the water at the static mixer, upstream of the flocculation chambers.

After coagulation and flocculation, the water enters the common feed channel and is distributed to 18 dual media filters. Each filter contains two filtration layers: coarse coal (anthracite) and fine silica sand.

The flocculation basin facilitates the process to separate suspended solids and the remaining impurities are removed through dual media gravity filtration. Filtered seawater is then pumped by the low pressure feed booster pumps to the reverse osmosis section for desalination. Post-treatment at Carlsbad involves re-mineralization of the desalinated water, followed by final disinfection.

Interior – Carlsbad desalination plant
Reverse osmosis trains at Carlsbad desalination plant.

SWRO pressure center

IDE designed the Carlsbad plant based on its proprietary multi-media filtration (MMF) and pressure center design, which has shown increased availability and reliability, higher efficiencies and greater flexibility under variable operational modes, and lower capital expenditure/operating expense costs. It utilizes horizontal centrifugal axially split high pressure pumps, with an optimized size in order to achieve the highest efficiency. Optimization is based on the pumps specific speed (Ns), pump flow rate, total dynamic head, etc.

The pressure center offers economy of scale and simplified erection, and allows feed pressure to the RO trains to be increased or decreased. This means that all RO trains remain operational during periods of reduced production, thereby decreasing system recovery, without increasing the total feed to the plant.

The Carlsbad plant produces 8,517 m3/hr at its peak. The operating pressure of the seawater reverse osmosis section varies from 60 bar to 65 bar, according to the seawater characteristics and the operating regime.

Carlsbad is the first major California infrastructure project to eliminate its carbon footprint. The plant has a system to reuse energy that is otherwise lost in the desalination process. This makes it possible to reduce the total energy consumption of the plant by 46%.

Environmental precautions

At all stages of the process, IDE adopted mitigation measures to preserve the region’s valuable resources. The increased salinity of the brine discharged to the sea does not have an adverse effect on marine organisms in the vicinity of the discharge channel. After the brine is returned to the discharge channel, and prior to its discharge to the Pacific Ocean, the brine stream is diluted with the return flow from the power plant’s cooling water system.

The Carlsbad Desalination Plant has already produced more than 55 billion litres of high-quality water, and will generate over $50 million annually for the regional economy.

Boaz Keinan is with IDE Technologies. This article appears in ES&E Magazine’s December 2016 issue.

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Wet grit classifier
Typical wet grit classifier

By Jim Weidler, Kusters Water

The primary benefit to grit removal in the wastewater treatment process is to eliminate potential damage to downstream mechanical equipment, and reduce the likelihood of adverse effects on the treatment processes.

There are many different types of grit removal systems currently utilized in the municipal wastewater industry, including mechanical vortex, induced vortex, multi-tray vortex, aerated grit chambers and detritus tanks. Regardless of the methodology used to collect the grit, the need still exists for dewatering.

When designing grit systems, there are two options available for dewatering prior to disposal, either grit “washing” or grit “classification”. In simplified terms, you can “wash” the grit to reduce organics (typically <5%), or you can simply “dewater” it and not address the organics (typically <25%). The decision is normally dictated by tolerance for odours directly related to the percentage of organics and moisture content of the discharged grit.

How a grit washer works

A vortex grit washer receives direct pumped flow into a tangentially fed vortex style tank from either a grit pump or airlift, without the need for primary separation. It can operate effectively over a wide range of flows, with standard flows up to 640 gpm.

Due to the grit washer operating principles, mechanical agitator and internal grit scour wash system, the organics are “washed” and rejected. The cleaned grit is transported up a 40 degree inclined screw conveyor, resulting in an extremely dry, clean and odour-free grit, with very low organics (volatile solids) content of <5%.

Grit washer diagram
Key components of a typical grit washer.

How a grit classifier works

Grit classification is available in two operational styles: “dry” or “wet”.

A “dry” classifier includes a cyclone separator to concentrate the grit and discharge the underflow from the cyclone to further dewater as it is being discharged via an inclined screw conveyor. Typically, cyclone classifiers can have a higher percentage of organics in the grit discharge, somewhere in the range of 10% – 15%. The moisture content is in the range of 25% – 30%.

Limitations when considering a cyclone classifier include: a limited range of flow based on cyclone size and corresponding operating pressure, and their inability to operate with an airlift design, as they cannot maintain a constant pressure.

A “wet” classifier is fed a water/grit slurry directly from the grit basin. It includes a large flared settling zone to allow the grit to settle and dewater as it is being discharged via an inclined screw conveyor. Typical “wet” classifiers can retain an even higher percentage of organics in the grit discharge in the range of 20% – 25%, with a higher moisture content of 35% – 45%.

Conclusion

A number of factors should be considered before making a final selection of grit removal equipment, including: costs, flow rate, moisture content, and tolerance for odours due to organics in the discharged grit. The key design parameters are summarized in Table 1.

Table 1. Key design parameters for grit washing or classification selection.

TechnologyGrit WasherGrit Classifier (with 1 cyclone)Grit Classifier (without cyclone)
Peak Flow Rate (gpm)640250320
Organic Content (%)<5%10 – 15%20 – 25%
Moisture Content (%)<15%25 – 30%35 – 45%
Typical Costs$$$$$$$$$
OdourVery lowLowModerate

Jim Weidler is with Kusters Water, a Division of Kusters Zima Corp. This article appears in ES&E Magazine’s December 2016 issue.

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Chief Peigan at Indigenous Water Forum
Chief Peigan, File Hills Qu’Appelle Tribal Council, speaking about the potash industry’s water use.

By Peter Davey, ES&E Magazine

In late October, I had the privilege of being asked to speak at the Indigenous Water Forum in Whitecap Dakota First Nation, Saskatchewan. Hosted by the Safe Water for Health Research Team, the University of Saskatchewan, Touchwood Agency Tribal Council, and the Safe Drinking Water Team, the event was an emotional and inspiring gathering of Elders and Chiefs, water system operators, public health workers and researchers.

The purpose of the forum was to bridge people’s knowledge of water through sharing of indigenous ways of knowing, research presentations and demonstrations of practical applications. Living in southern Ontario, discussions and news about First Nation water is usually in the context of a boil water advisory or funding to eliminate advisories.

I found the most powerful demonstration at the forum were the water pitchers at each table. The water that we all drank during the two-day event was produced by one of two integrated biological reverse osmosis membrane (IBROM) treatment plants on Whitecap Dakota First Nation land.

During the technical breakout sessions, Brian Tralnberg, water treatment operator for Whitecap, explained how his community’s water treatment and distribution system worked, and he took questions from an audience of largely First Nation operators.

Other presentations discussed drinking water success stories; lessons learned from the Husky oil spill; policy gaps between stakeholders and government, and much more. This was a truly unique event and a must-attend for all water professionals.

For more information on the event, visit: www.indigenouswaterforum.com. This article appears in ES&E Magazine’s December 2016 issue.

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industrial water reuse tank

By Jeff Easton and Jim Woods, WesTech Engineering

Diminishing and increasingly regulated high-quality fresh water sources has pushed the issue of industrial water recycling into the forefront.

Water is required in almost every industrial sector for the processing and manufacture of products. Sources of high quality raw water for commercial plants are becoming progressively scarce. The availability of water from rivers and lakes is not only diminishing, but what is available is increasingly regulated. This scenario has pushed industrial water recycling into the forefront as a high-profile concern.

Cooling water systems, particularly at power plants and oil refineries, are the largest industrial consumers for recycled water, due to their high-volume demand. Other industrial applications include oil and gas drilling, petroleum refining, chemical plants, metal finishers, textile and carpet dying, paper manufacturing, cement manufacturers, and other cooling and process applications.

Many companies are aware of the risks that growing water constraints could place on their operations, and recognize the need to consider unconventional sources of water. The technology, chemistry and processes exist today to feasibly and economically integrate water reuse from unconventional sources into almost any industrial process application.

Unconventional industrial water sources

Unlike conventional water sources like potable supplies, rivers, lakes, surface ponds and fresh water wells, unconventional industrial water sources can originate from wastewater treatment plant effluent, brackish, surface, well, and mine pool water, acid mine drainage, hydraulic fracturing flowback and produced water.

These water sources may contain varying levels of suspended solids, oils and greases, colloidal silica and metals, and dissolved minerals and organics. Contaminants can include dirt and sediments, hardness (such as dissolved calcium and magnesium), heavy metals (like lead, zinc, cadmium, mercury and arsenic), salts, organics and colour.

Since every industrial application requires a different level of finished water quality, understanding the condition of the source water and the finished water quality requirements determines the processes and equipment needed. For most industrial uses of reclaimed water, conventional processes involve secondary treatment, filtration and disinfection steps to achieve a desired level of water quality. Most applications will require multiple processes to achieve the desired finished water quality.

Reuse of municipal wastewater

Recycled municipal wastewater can be used for a broad range of reuse applications, but not for direct drinking water and the manufacturing of food and beverages. Besides traditional uses such as industrial processes, agricultural irrigation, and the irrigation of lawns, landscapes, cemeteries and golf courses, many areas add recycled water to underground storage basins that are used as drinking water supplies.

Water recycling is very important in arid climates, like southern California, where water must be imported from other parts of the state. The Sanitation Districts of Los Angeles County operate the largest engineered wastewater recycling program in the world. The goal is to recycle as much water as possible from their 10 water reclamation plants (WRPs). These play a major role in meeting southern California’s water needs, providing primary, secondary, and tertiary treatment for approximately two million litres per day, 650,000 litres of which are available for reuse.

Utilizing mine pool water/acid mine drainage

New or expanded steam electric power plants frequently need to turn to non-traditional alternative sources of water for cooling. One type of alternative water source is groundwater collected in underground pools associated with coal mines, known as mine pool water. When this water flows from the mine to the surface it is called acid mine drainage (AMD). It contains multiple combinations of acidity, and metals such as arsenic, cadmium, copper, mercury, silver and zinc.

With water sources becoming harder to obtain for industrial applications, these marginal-quality mine pool waters and AMD streams are becoming more attractive for reclamation and reuse. From a cooling perspective, mine pool/AMD water is desirable for industrial water use because it has a relatively consistent and low temperature year round.

Implementing sustainable and financially viable methods to reuse vast quantities of mine pool/AMD water is an area of relatively new, but growing, interest for mining operations. The technologies exist to economically treat any strength of acid mine drainage for industrial reuse.

Recent technological refinements in such processes as CO2 stripping, aeration, thickening, clarification, sludge disposal, ultrafiltration and reverse osmosis are making these systems more streamlined and efficient. This enables full-scale mine pool water/AMD reuse projects to not only control, manage and reuse these contaminated waters, but also to be financially viable.

An advanced surface aeration process is critical in facilitating an economically feasible solution for treatment of the mine pool/AMD wastewater. New impeller designs increase oxygen transfer efficiency, and reduce axial and radial loads. Such a system can produce a minimum efficiency of 3.8 pounds of oxygen per horsepower-hour. This improved transfer efficiency saves significant operational costs over the life of the equipment. Reduced axial and radial loads increase the life of the drive unit and reduce the size of support structures and beams for the surface aerators.

Systems like these are making acid mine drainage reuse more accessible for mining operations, which require systems to not only be financially feasible, but capable of efficiently handling wastewater streams at remote locations, usually within a confined footprint.

The latest developments in high-rate thickeners, used to separate liquids and solids at very high rates, are effective in coal refuse thickening, gold recovery, copper leaching, molybdenum processing, and other mining and chemical applications where mine pool water/AMD is sourced. Separation is effected rapidly because of the system’s hydraulics, which can be in excess of 20 times the hydraulics of conventional thickeners. As a result, the plant area required for this new generation of thickeners is greatly reduced.

Hydraulic fracturing flowback and produced water

As more hydraulic fracturing wells come into operation, so does the stress on surface water and groundwater supplies from the withdrawal of large volumes of water used in the process. This can be as much as 3.8 million litres of fresh water per wellhead to complete the fracturing process alone.

Equally important is the growing volume of wastewater generated from fracturing wells, requiring disposal or recycling. Up to 60% of the water injected into a wellhead during the fracturing process will discharge back out of the well shortly thereafter, as flowback wastewater. For the life of the wellhead, it will discharge up to 380,000 litres per day of produced wastewater.

Because water is the base fluid and biggest component used in hydraulic fracturing, its importance remains a critical factor in the operation and economics of shale oil and gas production. Fresh water and wastewater operating procedures which have been in place since the late 1990s are experiencing increasingly stiffer governmental regulations on water availability and disposal limitations. This is prompting oil and gas executives to reassess their current water use for fracturing, and adopt a more unified, and longer-range perspective on their water life-cycle management.

Fresh water supplies for use in hydraulic fracturing are becoming more expensive and more unobtainable.

Wastewater associated with shale oil and gas extraction can contain high levels of total dissolved solids (TDS), fracturing fluid additives, total suspended solids (TSS), hardness compounds, metals, oil and gas, bacteria and bacteria disinfection agents, and naturally occurring radioactive materials. These contaminants are partially a combination of chemicals and agents inserted deep into the well (3,000 metres and deeper) which facilitate fracturing by modifying the water chemistry to increase viscosity, carry more sand and improve conductivity.

Wellhead recycling

Some drilling operators elect to reuse a portion of the wastewater to replace and/or supplement fresh water in formulating fracturing fluid for a future well or re-fracturing the same well. Reuse of shale oil and gas wastewater is, in part, dependent on the levels of pollutants in the wastewater and the proximity of other fracturing sites that might reuse the wastewater.

Mobile solutions to treat wastewater at the wellhead enable recycling and reuse of flowback wastewater without the need for storing it in surface ponds on-site, or for trucking it for disposal at off-site deep-well injection locations. The drawback of wellhead mobile solutions is that they do not provide continuous processing to handle produced wastewaters, which would need to be processed for potentially 20 years following fracturing.

Since produced wastewater represents 95%, or more, of the wastewater generated during the life cycle of a well, mobile processing systems do not provide a solution adequate to solving the long-term problems of diminished water sourcing.

Brackish surface and well water

Brackish water refers to water supplies that are more saline than freshwater, but much less salty than seawater. This level of salinity in water is measured in TDS. In hydraulic fracturing, saline water is introduced into the process by contacting brackish aquifers.

The two most common desalination technologies are membrane and thermal processes. Membrane processes rely on permeable membranes to separate salts from water. They can be pressure-driven (reverse osmosis) or voltage-driven (electrodialysis).

Reverse osmosis is currently the most common desalination treatment method. The thermal process involves heating saline water to produce water vapour, which is then condensed and collected as fresh water. In a reverse osmosis system, the greater the TDS concentration of the water, the higher the pressure needed for the pumps to push water through the membranes, and, consequently, the higher the energy costs.

Mine pool water/acid mine drainage

The reuse of mine pool water/AMD in hydraulic fracturing for shale oil and gas production is quickly becoming a hot topic of interest. Many current shale oil and gas hydraulic fracturing wells are in close proximity to mine pool water/AMD areas, creating a unique opportunity to beneficially use these wastewater sites for hydraulic fracturing.

According to a 2013 Duke University-led study, much of the naturally occurring radioactivity (radium and barium) in fracturing wastewater might be removed by blending it with wastewater from mine pool water/acid mine drainage. Blending can bind some fracturing contaminants into solids that can then be removed before the water is discharged back into waterways.

Centralized handling of flowback and produced wastewater

Centralized treatment of wastewater has emerged as a viable solution for long-term efficiency in managing water sourcing and wastewater treatment in hydraulic fracturing. Centralized treatment facilities handle both the flowback wastewater and produced wastewater from oil and gas wells within a region, in a radius of 70 km – 80 km. Pipelines connect all wellheads directly with the central treatment plant.

Such centralized plants can be integrated with alternative sources of water to supplement fresh water needs for fracturing, such as from abandoned mines, stormwater control basins, municipal wastewater treatment plant effluent, and power plant cooling water. Centralized water management allows wastewater sourcing to be implemented on an economy of scale that has not before been realized in the shale oil and gas production industry.

Jeff Easton and Jim Woods are with WesTech Engineering Inc. This article appears in ES&E Magazine’s December 2016 issue.

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StormTech® MC-3500 chamber, McLaughlin Place retail centre
StormTech® MC-3500 chamber used in McLaughlin Place retail centre in Moncton, New Brunswick

The new McLaughlin Place retail centre in Moncton, New Brunswick, is meeting the city’s mandate of eliminating any increase in stormwater runoff while maximizing the number of parking spaces. Instead of using a detention pond or sump, the designers decided to use a system of chambers under the parking lot that would collect and hold stormwater runoff from the lot and rooftops.

The one-hectare commercial development with five buildings is located near the Université de Moncton. Plans call for apartment buildings to be added in the future.

“Based on the city’s design criteria, there could not be any increase in stormwater runoff into Moncton’s storm sewer system from McLaughlin Place,” stated Denis LeBlanc, P.Eng., of WSP Canada Inc. “This is in an older, fully developed part of the city with roads, storm sewers, etc., already in place. The city has a zero net increase stormwater policy, which means that, when you develop a site, post-development flows have to equal pre-development flows.

“In our case, some old houses and an old skating rink on the property had been demolished a few years before, but the downstream storm sewer was still limited by capacity. This meant we had to go above and beyond the zero increase requirements. In our design, we actually had to reduce pre-development flow conditions due to the undersized storm sewer that was downstream of our site.”

“Moncton uses a lot of open, dry detention ponds,” LeBlanc explained. “The reason for that is because land value is not that high and developers can usually afford to lose a bit of land to put in a pond. In this case, we didn’t have any available land and our site was fully covered by buildings or parking lots. So, underground storage was our choice for detention.”

To satisfy the city’s Zero Net Increase for Stormwater Runoff Law P#215 and meet the site’s storage capacity requirement of 485 cubic metres, the underground system used 87 StormTech® MC-3500 chambers in a 26.8 m x 17.9 m area.

Each StormTech MC-3500 chamber is 2.28 m long x 1.95 m wide x 1.14 m high, with minimum installed storage capacity of 5.06 cubic metres. The open graded stone around and under the chambers provides a significant conveyance capacity, ranging from approximately 23 l/s – 368 l/s. Actual conveyance capacity is dependent upon stone size, depth of foundation stone and head of water.

The excavation was 3.3 m deep, which allowed for 2.13 m of cover above the chambers. The gravel bed was made up of 18 mm – 50 mm washed rock. A rock slinger was used in order to place the stone faster.

A non-woven geotextile separates native soil from the washed rock. To convey the water from the catch basins, ADS N-12® corrugated high-density polyethylene (HDPE) pipe was used to create a 600 mm x 450 mm manifold, connected to the first four chamber rows.

“We’re not calling it retention but detention,” LeBlanc continued. “Water is not infiltrating into the ground. Our soils are all clay here so there’s little to no infiltration. This means you still need to outlet water to a pipe or a sewer. Our chambers are on the bed of gravel with the geotextile under it to prevent the clay from interacting with the gravel. From there, the water flows into a control structure downstream of the chambers. It is basically just a manhole with an orifice in it. From there, it goes into the municipal storm sewer.”

To convey water from the underground detention system to the municipal storm sewer, a 250 mm diameter solid wall DR17 HDPE pipe was horizontally directionally drilled nearly 16 m under Morton Avenue, a major road. This was needed because the city could not shut down any lanes.

For more information, visit www.ads-pipecanada.com. This article appears in ES&E Magazine’s December 2016 issue.

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BFF-C-X Bulk Out® split-frame bulk bag
Bulk bag and lifting frame of the BFF-C-X Bulk Out® split-frame bulk bag discharger are forklifted onto the stationary discharger frame inside the container.

By Craig Favill, Transvac Systems Ltd. and David Boger, Flexicon Corporation

When a water treatment plant faced a spike in pesticide concentration exceeding the allowable concentration limit for incoming water, it was forced to shut down. In order to provide clean drinking water to users, water had to be diverted from a regional water treatment plant until the problem could be solved.

The solution ultimately chosen was a mobile, trailer-mounted carbon dosing system, housed in a six-metre long steel shipping container. It was delivered and activated within one day, without costly and time-consuming site preparation, construction or complex components. The water treatment facility was restored to compliance, as the dosed carbon successfully removed pesticide traces from the main water stream.

Supplied by Transvac Systems, the TransPAC mobile powder handling and carbon dosing system includes a bulk bag discharger, two flexible screw conveyors, and a Transvac ejector system for mixing and injecting a slurry of powdered activated carbon (PAC) into the water stream.

It only requires connections to an electric power supply, the municipal water stream, and an external water supply. Environmental impact and site preparation are minimized, as well as the need for maintenance and planning permission. The system is safe to operate, and simple to control.

From the split-frame bulk bag discharger, PAC is automatically transferred from a half tonne bulk bag, through a flexible screw conveyor, to a surge hopper. From there, a second flexible screw conveyor meters the powder into the ejector.

flexible screw conveyor
The flexible screw conveyor from the bulk bag discharger moves carbon powder to the surge hopper. The second flexible screw conveyor then moves the powder to the intake of the ejector.

A forklift loads the bag-loading frame and 500 kg bulk bag onto the stationary discharger frame inside the shipping container. Once the bag spout is untied, the powder flows into a 75 mm diameter flexible screw conveyor leading to the surge hopper. A second 60 mm diameter flexible screw conveyor moves the carbon powder from the hopper outlet to the intake of the ejector that accurately doses the PAC into the municipal water stream. The conveyors are curved to fit the tight space within the shipping container.

From the control panel, the operator sets the speeds of the conveyor drives to automatically dose the proper amount of PAC according to the site water flow. Low and high level sensors in the surge hopper signal the controller to start or stop flow through the first flexible screw conveyor when the hopper contents reach the low or high level.

The carbon dosing portion of the TransPAC system includes a header tank for incoming water, a booster pump and the ejector. Velocity of the water flowing through a venturi creates a low pressure zone in the ejector that entrains the carbon powder into the treated water stream at a rate set at the control panel. The unit operates with no moving parts.

PAC can pose handling problems

Powdered activated carbon adsorbs the pesticide on its surface, and the carbon and adsorbed material are subsequently removed as sludge in the flocculation process. However, the extremely fine powder is prone to dusting. Both the bulk bag discharger and flexible screw conveyors prevent dusting. The bag outlet spout is connected to the feeder by a Spout-Lock® clamp ring. This creates a secure, dust-tight connection between the clean side of the bag spout and clean side of the bag spout interface.

Each flexible screw conveyor consists of a stainless steel screw rotating inside a durable polymer tube that contains the fine powder as it is conveyed. The conveyor discharge is likewise dust-free, as powder exits through a transition adapter located forward of the drive at the discharge end, thereby preventing it from contacting bearings or seals.

For more information, visit www.flexicon.com, or www.transvac.co.uk. This article appears in ES&E Magazine’s December 2016 issue.

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Pollution illustration
By Patrick Sackville, Paul Acchione and Michael Monette

A growing number of national and subnational jurisdictions have taken steps to develop plans and programs to reduce the emission of greenhouse gases (GHGs). While it is clear that consensus regarding climate change and momentum to address its threats are both building, jurisdictions have yet to coalesce around a common strategy. This has created a patchwork of solutions and encouraged “free riders”.

The Government of Ontario is finalizing plans to launch a cap-and-trade program that will serve as the central component for their ongoing strategy to combat climate change. The Ontario Society of Professional Engineers (OSPE) realizes how critically important the planning, design and execution of this policy is for the province’s environment and economy, and they have voiced their support and criticisms throughout the public consultation process.

Efforts to corral carbon in Canada

In the Canadian context, provincial governments have largely taken a leadership role in curbing emissions and transitioning toward low-carbon economies. Broadly speaking, current climate initiatives in Canada fall into one of two camps: carbon tax systems or cap-and-trade programs.

Launched in 2008, British Columbia’s $30 per tonne carbon tax collects $1-billion annually. This is a revenue-neutral program whereby all funds are redistributed into the economy through a “tax-shift” for businesses and households. Essentially, program revenues are redistributed to organizations and individuals that show environmental proactivity, improved stewardship, and realize energy efficiencies.

This year, Alberta, ahead of environmental conservation, introduced a tax on carbon emissions. Levying an initial rate of $20 per tonne, this price will be raised to $30 after one year. Alberta’s government forecasts the carbon tax will collect $9.6-billion over the next five years, to be reinvested into the provincial economy to realize energy efficiencies.

By contrast, in 2013, Quebec formally launched its cap-and-trade system, now linked with California as part of the Western Climate Initiative (WCI). This partnership created the largest carbon market in North America and established the world’s first carbon market to be designed and operated by subnational governments of different countries.

In February, Ontario introduced legislation to create a cap-and-trade program as part of the Climate Change and Low-Carbon Economy Act.

Unlike carbon tax systems that do not place hard limits on emissions, cap-and-trade programs set a clear limit on GHG emissions. Under cap-and-trade, this limit is translated into tradable emission allowances, each typically equivalent to one metric tonne of carbon dioxide or equivalent. These are auctioned or allocated to regulated emitters on a regular basis.

At the end of each compliance period, each emitter surrenders enough allowances to cover its actual emissions. The total number of available allowances decreases over time, to reduce the total amount of GHG emissions. By creating a market and a price for emissions reductions, the cap-and-trade system offers an environmentally effective and economically efficient response to climate change.

Ultimately, cap-and-trade programs offer opportunities for the most cost-effective emissions reductions. However, many challenging design issues must be addressed before initiating a cap-and-trade program in Ontario. A well-designed market can achieve reduction goals in a cost-effective manner, and drive low-GHG innovation.

Creating connections: Ontario’s cap-and-trade program

While the scope and design of Ontario’s cap-and-trade system have yet to be determined, there is already a significant congruence between the California and Quebec regimes. For example, both systems cover the same GHGs and sectors, set the same emissions’ thresholds, and have virtually identical allocation methods.

The significant parallels between Quebec and California’s cap-and-trade systems have enabled both markets to integrate quickly and seamlessly. Despite only officially linking carbon markets in 2014, they have already successfully held joint auctions of greenhouse gas allowances. Given Ontario’s desire to link with the cap-and-trade markets in Quebec and California, their systems will likely play a significant role in dictating the approach Ontario takes.

The significant similarities between Quebec and California’s systems are largely dictated by detailed policy architecture prepared over a period of several years by the Western Climate Initiative (WCI) and their partner jurisdictions. The WCI, launched in 2007, consists of a voluntary coalition of U.S. states and Canadian provinces, including Ontario. They have developed guidelines to facilitate mutual cooperation in order to reduce greenhouse gas emissions, in particular by developing and implementing a North American system for cap-and-trade.

Ontario has also consistently emphasized the importance of linking cap-and-trade systems with other jurisdictions. In 2008, Ontario Premier Dalton McGuinty and Quebec Premier Jean Charest signed a Memorandum of Understanding (MOU) with respect to a provincial and territorial cap-and-trade initiative. The MOU heavily contemplated and encouraged linkages to other GHG cap-and-trade systems, noting that such linkages could reduce GHGs at lower costs, allow for larger trading volumes, improve liquidity, and speed the pace of innovation, among other benefits.

Shortly after entering into the MOU, Ontario demonstrated its further commitment to a cap-and-trade system by introducing enabling legislation with Bill 185, the Environmental Protection Amendment Act, 2009 (Greenhouse Gas Emissions Trade). The Bill provided the government with broad authority to implement emissions trading systems and establish rules relating to the scope, trading, distribution, and administration of such a system. Like the WCI and MOU, Bill 185 explicitly contemplates integration with other regional cap-and-trade systems.

The need for a border adjustments framework

A cap-and-trade mechanism functions properly when it is connected with other global entities to facilitate a trading structure and force GHG reductions. This complex arrangement needs to work by design, operate based on objective scientific findings, and be outcomes-focused. It should be calibrated to ensure that reduction targets are being achieved.

In the event that connections are not made, are not equitable, or fail to expand, Ontario’s diverse mix of economic sectors could face significant competitive disadvantages, or these pressures could undermine Ontario’s emissions targets. Ensuring that the cap-and-trade program does not disadvantage Ontario producers is key to sustaining public support for the program.

Based on Ontario’s transformation costs to achieve an 80% reduction in emissions from 1990 levels in the electrical sector, OSPE estimates that, to achieve the same goal across all other sectors of the economy, will require substantially higher carbon prices than the $30 per tonne of carbon dioxide equivalent that is currently anticipated. The public is unlikely to tolerate high carbon prices if they create economic hardship in Ontario due to unfair trade.

As an action to mitigate these risks, Ontario could introduce a border adjustments framework. Border adjustments are trade measures that aim to level the playing field between domestic producers facing costly climate change measures and foreign producers facing very few. In the context of cap-and-trade, border adjustments are meant to reduce leakage and competition exposure – a forward-looking design that would serve to fill a critical gap in the program Ontario has proposed.

As it stands, Ontario’s program fails to account for the foreign purchase of allowance credits. Because foreign company emissions are not part of the process for determining allowances, forcing these firms to buy credits in the Ontario market will affect allowance prices in ways that were not anticipated when quantities were established. To prevent these ill-effects, border adjustments act as a carbon tax payment for imports into Ontario or as a carbon tax refund for exports going out. This applies to jurisdictions that do not have an equivalent program.

In context, the market would determine a carbon tax value that would be applied on imports from and exports to key jurisdictions like Michigan, Ohio and New York that do not have a cap-and-trade program recognized by Ontario or its likely program partners (such as California or Quebec). A border adjustments framework would provide a more precise mechanism for fair trade between jurisdictions with differences in their carbon reduction programs. Border adjustments would also put additional pressure on foreign jurisdictions to introduce their own carbon-pricing programs to avoid the carbon price penalties on their exported products.

Time is ticking

For Ontario, the window of opportunity to take the lead in developing a border adjustments framework is quickly closing. California is currently in the middle of their second compliance period and will review the implementation of a border adjustments framework ahead of their third period (2018-2020). This would impose similar compliance costs on imports from jurisdictions without cap-and-trade program linkages equitable to California’s. If California proceeds with such a framework, it will take Ontario some time to modify its own program, and it will need to accommodate California-focused regulations that are not in Ontario’s interests.

Border adjustments make sound policy sense. Ontario has one of the cleanest mixed generation electrical grids in the world and should receive credit from its trading partners for this value-added feature. Ontario has already reduced emissions in its electrical sector by 80% from 1990 levels, putting it about 35 years ahead of the rest of the world.

Allowing products made with high-emissions, low-cost electricity to enter Ontario without a carbon price adjustment would be unfair to Ontario companies. Border adjustments would accelerate carbon reduction in trade-exposed sectors, while maintaining economic priorities and protecting against job losses. Through border adjustments, Ontario businesses would be protected from unfair competition from high-emission jurisdictions.

Looking at the current situation from a global perspective, the proliferation of Chinese solar panels serves as a clear example of how a border adjustments framework would assist Ontario’s environment and economy. Solar panels manufactured in China are made with one of the highest GHG-emitting electrical systems in the world and are undercutting low-emission solar panel production in Ontario. This is a “lose-lose” arrangement for the province both environmentally and economically.

Border adjustments would serve to address this and other gaps between policy objectives and outcomes, while also leveling the playing field for Ontario’s domestic and export industries.

Big challenges require bright minds

During public consultations with the Ontario government on Bill 172, the Climate Change Mitigation and Low-Carbon Economy Act, the argument for border adjustments was presented by OSPE as the voice of the province’s engineering community.

It is OSPE’s belief that by setting a price on carbon and permitting the purchase and sale of emission allowances, cap-and-trade systems have the potential to become the cornerstone of an integrated environmental approach aimed at encouraging the most cost-effective GHG reductions.

Ontario wants to establish the foundation for an economic strategy focused on developing a green economy. With this objective in mind, the Ontario Society of Professional Engineers has urged the government to establish a border adjustments framework that will defend the integrity of our environmental commitments, encourage our trading partners to adopt carbon pricing programs, and support Ontario’s economic interests.

Patrick Sackville, MA, Paul Acchione, M. Eng., P. Eng., FCAE, and Michael Monette, P.Eng., MBA, are with the Ontario Society of Professional Engineers. This article appears in ES&E Magazine’s August 2016 issue.

Ex. Reservoir construction (1920s)
Construction of Ex. Reservoir in 1920s
By Rika Law and Wayne Stiver

Peterborough Utilities Commission (PUC) owns and operates the Peterborough Water Treatment Plant (WTP), which consists of a conventional filtration system, a chlorine contact tank and clearwell.

Given that the chlorine contact tank and the clearwell were constructed in the 1920s, and that there was no operational redundancy for the chlorine contact tank, a new chlorine contact tank and clearwell had to be added. The PUC was also aware that the existing reservoir was leaking. However, they couldn’t quantify or determine the location and extent of the leak. Once the new reservoir was constructed, the existing reservoir could be taken out of service for permanent repairs of the leaks.

The project was designed so that, when both the new and existing reservoirs are constructed or repaired, they can operate in parallel, providing supply security, flexibility in operation, and additional storage.

Existing reservoir leak and shutdown

Excavation was underway for the new chlorine contact tank and clearwell, some distance from the existing chlorine contact tank and clearwell. Slope protection was in place and all seemed well on October 3, 2014. But, by October 6, the excavation site turned into a lake, as the existing reservoir developed a sizeable leak and flooded the site.

The PUC quickly switched the Peterborough WTP to bypass mode. This involved prechlorination at the beginning of the WTP to achieve the required disinfection. Treated water then went through a bypass pipe in the chlorine contact tank into the distribution system. This allowed PUC to drain down the existing chlorine contact tank and clearwell. Once this was done, assessment of the leak and repair plans could start.

R.V. Anderson Associates Limited (RVA) structural staff observed that numerous cracks along the floor of the reservoir in both cells allowed water to leak. The cracks were not new, but the water had found a new path of least resistance when the adjacent site was excavated. It was suspected that the water made channels/voids underneath the floor slab and that these would also need to be addressed.

Based on the structural investigation, the following emergency repairs were recommended by RVA:

  • Polyurethane injection (with NSF-61 approved material for potable water application) for all observed floor cracks;
  • Pressure grouting of the voids underneath the floor slab;
  • Potable water dive into the operational inlet and effluent chambers of the existing reservoir to try to patch up cracks at the floor/wall interface.

This plan would allow the existing chlorine contact tank and clearwell to be put back into service as soon as possible. However, several issues complicated and hindered the emergency repairs, including: frigid winter temperatures; leaks from the operating inlet and effluent chambers (which were in use for the bypass operations); and, leaks from the isolating sluice gates and valves.

Challenges, strategy and lessons learned

There were several things that were done to prepare for this possible leak. PUC had the foresight to implement construction of the new reservoir, and to undertake permanent repairs to the existing one, prior to the major leak event. They knew that the reservoir was leaking, but were not able to quantify it because they could not stop the use of the existing chlorine contact tank and clearwell without going on emergency bypass operations. PUC had budgeted for the two projects in order to address the leaking existing reservoir issue and the lack of redundancy in their chlorine contact tank.

During the unexpected, emergency shutdown of the existing chlorine contact tank, PUC’s operations staff was also able to maintain the supply of potable water. PUC operated the WTP with prechlorination at the
beginning of the conventional filtration system, and emergency bypass of the chlorine contact tank and clearwell for five months. Monitoring for water quality, including trihalomethanes, was
done frequently.

PUC was proactive and informed the Ministry of Environment and Climate Change of the emergency situation and maintained good relations with them. Lessons learned from this unexpected turn of events included:

  • Cultivation of a cooperative environment amongst all parties (client, consultant, contractor, approval agencies, etc.) is important throughout the project, but especially when trouble arises;
  • Updating and informing key stakeholders of the issue throughout the process helps to keep the cooperative spirit;
  • Knowledge of the water system, its limits, capabilities, and redundancies/contingencies, is necessary for troubleshooting under extreme circumstances.

Water treatment plant pipe installation
Critical piping connection between the new chlorine contact tank and clearwell system and the existing distribution network.

Connecting the new system

Plant operators planned for a 36-hour window to perform a critical piping connection between the new chlorine contact tank and clearwell system and the existing distribution network. The situation was complicated due to: space constraints; night-time work; installation of new tee between two existing fixed points; installation of several large 1,200 mm valves and pipe pieces; and, “live” water system at both ends of the connection.

During the shutdown, PUC and RVA had several tools to continue distribution of potable water:

  • Keep the water levels in the City reservoirs high;
  • Overland bypass pumping between the existing clearwell (which had been repaired and put back into service) to another one for the high lift pumps to feed Zone 2 water reservoirs in the City;
  • Back feed Zone 1 via Zone 2;
  • Closely monitor the water levels and water demand;
  • Review and revise the shutdown plan, complete with contingency plans, with the contractor three times;
  • Conduct shutdown planning meetings to coordinate details of who, what, when, where and how.

Despite planning efforts by PUC, RVA and the contractor, accidents and unexpected events still occurred. These included warping of the stainless steel pipe during installation and the breaking of a specially measured and fabricated gasket on an important coupling. In the end the shutdown lasted 21 days! During that time, all parties worked together to try to find alternative solutions, including calling different suppliers, contractors and municipalities for replacement parts.

Lessons learned

• Cultivate a cooperative environment between parties

• Update and inform key stakeholders

• Know your water system’s limits, capabilities and redundancies.

 

A shutdown can never have too many contingency plans, as redundant and pessimistic as it may sound. Also, reliable “as-built” information can save a lot of headaches. Due to the quick thinking, cooperative spirit and collective experience of Peterborough Utilities Commission, operations staff, contractors, and the consultant, both incidents at the plant had a positive ending.

Rika Law, P.Eng., PMP, is with R.V. Anderson Associates. This article appears in ES&E Magazine’s August 2016 issue.