Water Storage Systems
In the age of climate change, droughts, and wildfires, water storage systems are more important than ever.
There is only one readily available, accessible, and inexpensive substance that can be widely used to combat fires: water. However, in a changed climate where drought and forest fires are far more prevalent, and where commercial and residential development in vulnerable areas makes for ever more expensive property damage, available water supplies can be severely strained. Adding to this stress are long-term droughts induced by a changing climate, limiting the naturally available groundwater and surface water sources that are normally used to combat fires. A key to alleviating this water scarcity, water stress, and water deficit lies in securing adequate water storage systems. Water tanks are the traditional means of enclosed water storage, and they are evolving to meet the challenges of an increasingly unstable climate. The increasing frequency of forest fires and the lengthening duration of droughts are affecting both sizing requirements and tank liner material selections.
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THE THREATS—PHYSICAL AND FINANCIAL
While one can disbelieve in climate change, nobody can deny increases in insurance premiums and decreases in bond ratings. Begin with coastal regions, which are subjected to larger and more frequent hurricanes as well as rising sea levels. Rates for shoreline homeowners in the Atlantic hurricane zone from Boston to Brownsville have spiked since 2003. Of the 15 states that saw the worst increases in insurance premiums, 14 of them are on the Gulf coast or the Atlantic Ocean. All of those states saw rates increase by at least 44% with the worst being Florida, which saw a 91% price increase. (Source: National Association of Insurance Commissioners.)
From this most dramatic and obvious impact of a changing climate, we can go to the effects of drought on insurance rates. Index-based drought insurance rates for agricultural operations were developed to avoid adverse selection and moral hazard that may not be covered by traditional agricultural insurance. The index acts as a proxy for shortfalls in crop yields due to drought conditions. Drought remains the greatest risk to agricultural production with much greater impact than pests, floods, or frost. To quote an assessment by the USDA: “In 2012, the US Department of Agriculture (USDA) declared more than two-thirds of counties in the United States drought disaster areas. This was the most severe and extensive US drought in over 50 years, and it underscored the far-reaching role that drought can play in agricultural production and policy.” The financial impact of droughts is projected to cost $6 to $8 billion annually in lost production.
Hand-in-hand with drought conditions come wildfires and the threat they pose to life and property. The cost of insurance to vulnerable homeowners has kept pace with this increasing threat. One area that has seen these insurance rates skyrocket is California. Survivors of California wildfires have seen annual homeowners’ premiums nearly quadruple. And insurers are using increasingly more sophisticated risk assessment models in response to climate change and droughts generating more frequent and severe fires. These events are increasingly unpredictable and so some insurers are restricting where they will write policies. But this is not just a Californian or even an American phenomenon. While the world’s attention was focused on California, British Columbia, Canada (a region which can normally expect both high rainfall and snowfall), had its worst fire season on record in 2017. Almost 900,000 hectares were burned at an estimated cost of over $315 million.
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From drought and fire, we go to the opposite: increased flooding caused by ever more extreme and erratic weather patterns and rising sea levels. Global sea levels are rising 1/8 to 1/6 inches per year, with the potential for more rapid increases. This is a result of both glacial melt and the expansion of the oceans’ waters as a result of increased temperatures. Higher sea levels imperil infrastructure and natural features such as marshlands. It also magnifies the effects of storm surges and wave action along the coasts. In the interior, flood elevations and associated flood zones of major rivers are also expanding. Rivers and streams across the Northeast and Midwest have seen increases in the size of floods. The frequency of large river floods has increased in the Northeast, Pacific Northwest, and northern Great Plains. (Source: “Climate Change Indicators: River Flooding”, EPA.gov)
Insurance is not the only financial market impacted by climate change. Moody’s Investors Service Inc. now incorporates climate change into its credit ratings for state and local bonds. Cities and states that fail to deal adequately with the effects of a changing climate are assumed to be at greater risk of default and therefore receive a downgraded bond rating to cover the anticipated risks. These financial risks stem from both the damage to property values (and subsequent tax review) from repeated storms and floods and the necessity of major capital investments on sea walls, storm drains, or hardening buildings and infrastructure against flooding. Moody’s lists six indicators that assess “the exposure and overall susceptibility of US states to the physical effects of climate change”: the share of economic activity that comes from coastal areas, more frequent droughts, severe heat waves, hurricane and extreme weather damage as a share of the economy, and the share of homes in a floodplain.
Some policy-makers may not care about protesters in the street, but the price shock of increasing insurance premiums and downgraded bond ratings will get their full and complete attention. At the end of the day, politicians have to deal with budgetary, economic, and financial reality. And in that sense, climate change is becoming very real indeed. And while this approach to the problem of climate change may not have the same passion as a dedicated environmental movement, it does allow for efficient and accurate assessment of the problem and the development of cost-effective measures to deal with it. And the key to preparing for the adverse effect of climate change is adequate reserves of water.
Credit: GETTY IMAGES
STRAINS ON WATER RESOURCES—CLIMATE, DROUGHT, AND FIRE
The more dramatic effects of climate change are rising temperatures and melting glaciers. There is no doubt about its effect on planetary climate. Closer to home, climate change creates secondary effects that have serious impacts on water supply and storage needs. Concerns about climate change’s effects on water tend to focus on the world’s oceans. But closer to home, its primary threat is to freshwater supplies used for human consumption, agriculture, and industry.
The first and most obvious effect of climate change is the increased frequency, duration, and intensity of heat waves. The 10 hottest years recorded by NASA and NOAA have all occurred since 1998 (in order: 2007, 2012, 1998, 2009, 2005, 2013, 2010, 2014, 2015, and 2016) with 2017 on track to be one of three hottest years on record. (Source: Climate Central) With increased heat comes increased demand for freshwater.
Higher temperatures increase the risk of drought. Increased heat also results in increased demand for water at a time when changes in weather patterns cause droughts and make wildfires far more likely. Increased evaporation results in increased demand for irrigation water even as individual plants require more water as a result of heat stress.
High-intensity farming requires large amounts of water, even to the point of draining groundwater aquifers faster than they can recharge, a process that will accelerate with increased heat levels. For example, agricultural wells are extracting water from the Ogallala aquifer (serving the states of Colorado, Kansas, Nebraska, New Mexico, Texas, Oklahoma, Wyoming, and South Dakota) at a greater rate than it is being replenished. Colorado farmers this year pumped groundwater out of 4,000 wells, state records show, siphoning as much as 500 gallons a minute from each well to irrigate roughly 580,000 acres of water-intensive crops.
With this combination of increased demand and altered rainfall patterns, this trend is getting worse. Federal data indicates that the Ogallala aquifer contracted twice as fast in the past six years as it had in the previous 60. At least 358 miles of rivers and streams have dried up within a 200-square-mile area straddling Colorado, Kansas, and Nebraska, with another 177 miles expected to dry up by 2060. The depth where groundwater can be tapped has fallen by as much as 100 feet in eastern Colorado. (Source: USGS data)
Which brings us to drought, the most famous one in the US being the extensive drought that has afflicted California, leading to severe strains on the state’s water supplies and massive property damages and loss of life due to wildfires. In California, the mountain snowpack that accumulates each winter provides up to a third of the state’s water supply. Each spring it melts and flows downhill, feeding tributaries and rivers providing water to the low lands. But climate change is projected to cause smaller and smaller snow accumulations in coming years. (Source: California’s Department of Water Resources) California expects to lose at least a quarter of its Sierra mountains snowpack by 2050, resulting in a major reduction in California’s freshwater supplies.
A stealthier effect of climate change results from sea level rise which increases saltwater infiltration into coastal freshwater aquifers. These pockets of freshwater along the coast are a primary source of drinking water for coastal communities and irrigation for agriculture. Once contaminated by saltwater, these aquifers must either be abandoned or the water extracted from them forced through an expensive process of desalination. This process of saltwater intrusion can be accelerated by increased pumping from the freshwater aquifer to meet the increased demands generated by high heat. Lowering the head within the aquifer, even temporarily, can reduce resistance to intrusion, making saltwater contamination more likely.
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TANKS AND WATER RESOURCE MANAGEMENT
The water tower is the most common means of storing water for domestic urban, suburban, and township use. These are fixtures of towns large and small and are usually their most prominent landmark. A water tower combines both storage capacity and height to allow for efficient gravity flow through its distribution pipe network at the minimum required pressure head at the point of use. As such it typically resembles a large bulbous tank set on top of a cylindrical tower stand. The tanks come in a variety of shapes and sizes such as ellipsoids, teardrops, cylinders, and spheres. The cylindrical stand typically provides an overall height of 130 feet to allow for structural stability and ensure proper gravity flow. A variation on this is the vertical water pipe where the cylinder by itself contains the water being stored.
Gravity flow is key to the operation of a standard water storage tank. It ensures that water flow can be sustained even at critical moments when electric power is out and pumps no longer work. So even in the worst possible emergency situation, water can be distributed for consumption and firefighting operations. Pumps are used only to refill the water tank, raising water to the top of its storage volume at the tower’s maximum elevation.
Sizing of the tank’s storage capacity depends on peak usage rates and the water consumption needs of emergency situations. As such, a water tower will be oversized for typical daily consumption. The water being consumed can either be potable (for residential and commercial use) or nonpotable (for industrial and agricultural use). Emergency water use can be either potable or nonpotable so long as it meets the situation’s firefighting requirements. A typical operating cycle involves gravity drainage to provide water during daylight hours with pumps recharging the storage tank at night.
In addition to its basic storage and support structures, a water storage facility utilizes a complicated assembly of internal piping, fixtures, controls, and appurtenances. These are often specialized or customized for the tank’s operating system. The rest of the water storage tower is built from a variety of structural materials: steel, reinforced concrete, pre-stressed concrete, wood, fiberglass, or brick. The interior of the storage tank portion is lined with a protective coating that prevents leaks and contamination of the stored water.
Structural limitations and space constraints can place an upper limit on the storage capacity of a standard water tower tank. A 1.5-million-gallon storage tank would be considered at the extreme end of the size scale. For even greater storage capacity, reservoirs are utilized. These can be either aboveground ponds and lakes (either natural or man-made) or belowground caverns and cisterns. Normally, a small town has no need for so much water storage, so these are reserved for larger cities and industrial or agricultural applications that utilize large quantities of water during production. Man-made aboveground reservoirs can be of almost unlimited size and can be constructed by placing something as relatively small as an earthen dike at a key topographic bottleneck.
If there are no natural lowlands or valleys that can be converted to hold water, a reservoir can be built directly by excavating a pond of sufficient depth and volume. Often, the bottoms and sides of these excavated ponds are also lined with compacted low-permeability clay layer, a geosynthetic liner, or a combination of the two (referred to as a “composite liner”). Impermeable geomembrane liners are constructed of welded sheets of high-density polyethylene (HDPE), polyvinyl chloride (PVC), and reinforced polyethylene (RPE).
Natural bodies of surface water (lakes, ponds, creeks, and rivers) can also be used as reservoirs. Pumps or siphons are used to extract water from natural sources. Underground caves, caverns, and man-made cisterns can also be used to store water. Usually, they are installed as part of a surface water run-off control system to hold excess surface water runoff.
So how can water storage capacities be modified to meet the general needs of a drought condition and the emergency needs of the wildfires that droughts generate? Storage solutions can be used to mitigate the effects of droughts and to prepare for dry times. Farmers and firefighters can both rely on stored water reserves to make it through dry times. Water can be captured and stored during wet times when water is plentiful. Storage for nonpotable uses is simpler and cheaper than the higher standards required for human consumption. However, tanks can be equipped with impermeable liners and fixed or floating covers that prevent contamination and minimize evaporation. For the most part, this water supply can be accumulated from captured rainfall during wet periods. With sufficient planning and analysis of water needs, agricultural operations and communities can plan their storage requirements to see them through an anticipated drought and make up the shortfall between supply and demand.
Some examples of drought pre-planning have been established:
- “City of Las Vegas, New Mexico. The city is exploring ways to increase water storage by: increasing storage capacity of Bradner Reservoir (raising the dam), recovering seepage from around the dam and pumping water back into the reservoir and pursuing an aquifer storage and recovery pilot project [….] The city worked with the San Miguel County Office of Emergency Management (OEM), to set up a water distribution plan. The county OEM purchased 20,000-gallon portable storage tanks that could be distributed to pre-determined sites if necessary. Through New Mexico WARN, the city of Las Vegas has an agreement to borrow Albuquerque’s water tanker trucks for water delivery to the portable storage tanks when needed”(18).
- “The city of Hogansville [Georgia] effectively communicated with the public through media coverage of frequent briefings to the City Council. Local newspapers also published information on water use restrictions such as watering schedules. Collaboration with USACE and Georgia EPD was required for the Blue Creek Reservoir reallocation in 1988. All participating governments needed to work together to negotiate the water purchasing agreements, and to develop a focused strategy that benefited all participants and the region as a whole. Building upon the regional partnerships, the city and adjacent Meriwether County developed a plan to meet growing water demands in the county’s northern part by sharing the costs of new infrastructure, such as onsite storage tanks, with the large industrial park customers” (33).
(Source: Drought Response and Recovery: A Basic Guide for Water Utilities, EPA.gov.)
Credit: RAIN WATER SOLUTIONS
Water harvesting storage systems from Rain Water Solutions
DROUGHT MANAGEMENT AND WATER SUPPLY STRATEGIES
In addition to preplanning and increasing stored water supplies, steps can be taken concurrently with drought conditions to ensure that sufficient water is available. The first step in drought management is defining the problem. Water resource managers have to determine the following: how much water is currently available; what will be the shortfall caused by the drought, assuming water demand stays constant; how can the water distribution and storage system efficiency be improve; how can customer demand be moderated or even reduced by employing better management and conservation practices by users; and how can additional supplies of water by identified and their capacity determined.
Increased monitoring during a drought is essential to establish water supply levels and to track trends in the reduction of these available supplies. Daily monitoring is preferable and can be accomplished with relatively inexpensive well-sounding equipment to track groundwater levels and extrapolate supply projections. Monitoring precipitation, lake and reservoir elevations, and streamflow depths are also necessary. Direct local measurements can be augmented by information from neighboring water utilities, state and local water agencies (regional water supply agencies, conservancy districts, groundwater management districts, or river authorities), the US Army Corps of Engineers, and other Federal departments.
Monitoring quality is just as important as monitoring quantity. Higher temperatures may increase pathogen populations. Furthermore, lower flows can alter effective watersheds, run-off patterns, and groundwater levels leading to changes in water chemistry. All of the above may require changes in the water treatment process. The frequency of post-treatment testing and sampling of water being distributed or placed in storage will also need to be stepped up.
Once the hard data is available, distribution plans can be modified accordingly to incorporate appropriate conservation measures. At the source, conservation measures can include: reducing pressure heads in the water distribution system to reduce flow rates, aggressively finding leaks and repairing them, increase available water system storage capacity, explore and implement beneficial reuses for flushed water and gray water (irrigation, construction, firefighting, and other non-drinking water applications), implement a plumbing repair program in low income areas, start up a hotline for reporting leaks, and generally encouraging conservation measures by homeowners and businesses.
Among the consumers of water are critical users such as hospitals and care facilities, schools, fire departments, power generation plants, heavy industries, and agriculture. Identifying these critical targets will create a baseline for emergency uses. After these are identified, the distribution of available water can be adjusted for non-essential applications such as landscaping, public swimming pools, and recreation facilities. Use restrictions in extreme drought conditions may include the outright banning of the activity for the duration of the drought. Augmenting these major efforts are a host of minor conservation efforts involving individual water users. Of primary importance is the collaboration with a host of residential and business water users on the implementation of water-saving methods and ways to improve efficiency. Only in extreme drought conditions does a water utility have to ration or allocate water uses to only the essential uses such as toilet flushing, bathing, cooking, and cleaning.
Additional water supply can usually be found outside the drought-affected area or the boundaries of the water supply district. Mass volumes of water may require the construction of water transport pipelines and bulk water purchases or leases. A system of interconnections can be built up between neighboring water service areas in anticipation of the next drought. Portable tanker trucks can be used to quickly move water on an as-needed basis. Brackish water supplies can be tapped for nonpotable and non-agricultural uses. And most important for providing long-term water security: improve water storage capacity by enhancing aquifer storage and recovery, increase the size and number of storage tanks, and expand the volume of surface reservoirs.
WILDFIRE FIGHTING AND WATER STORAGE REQUIREMENTS
“Some of those areas that typically would be more resilient to wildfires in wildfire-adapted ecosystems aren’t necessarily as resilient,” says Tina Boehle, information officer for the National Interagency Fire Center in Boise, ID. “The drought is making those areas less resilient to wildfire.”
News coverage of wildfires always includes dramatic video of airplanes dumping fire-retardant chemicals on the fire line or water dumped by helicopters. In reality, water is used far more extensively and it is applied mostly from the ground. These tanks can be fixed or portable. They can be operated by fire departments and state agencies or by individual homeowners.
The options for using water storage tanks to combat wildfires range in size from those used by individual homeowners to storage complexes required by fire departments and state firefighting units. Those homeowners living in an area vulnerable to fires can utilize the extra protection provided by individual water storage tanks. Firefighters can usually rely on fire hydrants to provide dependable water supply in urban areas. However, in rural and semi-rural areas there may not be a convenient high-pressure water main available. So, firefighters are often required to rely on locally available water sources or spend the time and money to transport sufficient water to threatened areas. Homeowners with their own storage tank can have a fire truck hook up to it directly to douse approaching flames. A storage tank with a minimum 1,000-gallon capacity is recommended, but commercially available tanks can be a large as 5,000 gallons.
An example of large-scale water tanks dedicated to combatting wildfires can be found in Oklahoma City. The search engine company Google donated large storage tanks previously used for the cooling systems for their data centers. Thirty of these 10-by-30-foot tanks with about 20,000-gallons storage capacity are now in place to combat wildfires.
MAJOR WATER STORAGE SYSTEM SUPPLIERS
Caldwell Tanks has been a builder of customized water tanks for 130 years. It provides customized water tanks for potable water and industrial uses, field erected tanks, and concrete storage structures. Services and capabilities include turnkey design, manufacturing of parts, and tank construction. There industrial tanks not only provide water storage, but also secure storage of fuel, ethanol, biodiesel, distillery liquids, process and treatment water, oil, and gas. In the area of potable water, Caldwell offers both elevated and ground storage tanks.
In addition to the tanks themselves, Caldwell provides a wide array of services, beginning with engineering. The company’s engineering staff applies thorough knowledge of all applicable design codes, material specifications, and consecution standards. This engineering expertise gives Caldwell control over production quality and ensures conformance with all applicable industry standards (AWWA, API, ASME, ASHRAE, SPFA, ASCE, IIAR, and NEHRP). Their fabrication, welding, and painting skills translate these engineering designs into physical structures. Once the parts and materials are fabricated, skilled experience crews perform the assembly and construction in the field. Working hand-in-hand with the field crews are project managers and safety specialists that ensure the most productive and safest assembly possible.
Induron Protective Coatings provides solutions to water tank painting, including coating new potable water tanks, or the recoating/overcoating of a previously painted industrial storage tank. They have pioneered ceramic epoxy potable water coatings specifically developed for use when higher performance systems are needed or lower VOC coating systems are required for painting potable water towers. Their wide range of coatings include high-performance acrylics, epoxies, polyurethanes, fluorourethane, and polysiloxane coatings.
In a related field, Induron also provides concrete canvas storage shelters for emergency situations such as earthquakes, hurricanes, tsunamis, and wildfires. These quickly installed emergency storage shelter can support an affected population after a disaster strikes. They are concrete storage buildings in a bag that can be deployed by two people in an hour and be ready for occupancy and storage within 24 hours after the concrete has cured. The result is a fireproof structure that can perform a wide variety of functions.
In the area of water storage for individual homes, Rain Water Solutions has developed a product line of water harvesting and storage systems. These rain barrels are easy to install and are included in distribution programs for communities across the country to promote water conservation by homeowners. Their affordable and compact Ivy model has a 50-gallon capacity with the larger 65-gallon Moby designed for bulk storage.