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To support the goals of the Division, the Committee is launching a blog on the TAWWA.org website to highlight existing utilities and programs across the state. This blog will provide valuable information on existing programs and highlight how more information on the programs can be obtained, thus creating an online database of water education resources.

 

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Drought’s Effect on Infrastructure

Posted By Karen E. Menard, Friday, September 7, 2018

 

 

Education Division – Consumer Outreach Committee Blog

 

All Things H2O                            September 2018 Issue

 

 

 

 

Drought’s Effect on Infrastructure

 

As a child, I remember always hearing “The optimist says the glass is half full, the pessimist says the glass is half empty, and the engineer says the glass is twice as big as it needed to be”. It is with this endearing engineer humor that brings me to today’s topic.

 

When I started in the water industry over 10 years ago, I was taught that conservation was the answer to the water scarcity issue and I thought we could conserve our way to abundance. If everyone could cut back just a little more water problems would be solved. It wasn’t until I went to work for an infrastructure supplier that I realized the negative effect drought and conservation can have on water and wastewater systems.

 

Presently, the water industry is caught between a rock and a hard place. There are some that advocate the hypothesis we are running out of water thus conservation is the only way to resolve the issue. On the flip side, selling the resource is how utilities bring in: revenue, pay off debt, pay employees, service existing infrastructure and fund new infrastructure. Water treatment entities are encouraging customers to not buy their product and then wonder why the money is not there when an upgrade, repair, or replacement is needed.

 

Most of the water infrastructure in the United States was installed in the early to mid-20th century.1 The environmental movement did not exist, at this time, therefore conservation was not a part of everyday life. According to a United States Geological Survey report published in 2015, per capita water consumption has dropped below 1960’s level. In 1960, per capita water usage in the U.S. was 89 gallons per day. In 2015, the number decreased to 82 gallons per day.2 Though there are obvious pockets of higher usage where infrastructure must be designed accordingly, one hundred gallons per person per day is still being regularly used as the benchmark for water system design. Though the glass may not be twice as big as it needs to be, it is oversized.

 

There are two major contributing factors for the drop in per capita water usage over the last five decades. One difference is education and a shift to a generally more conservation-oriented culture. The second difference is the Energy Policy Act, signed in 1992, by George H.W. Bush. This led to uniform water conservation standards for nearly all toilets, urinals, showerheads, and faucets manufactured after January 1994.3 If there is less water being used in the home then there is less water going down the drain. The effect is twofold influencing both water and wastewater infrastructure.

 

Prior to the Energy Policy Act, of 1992, water and wastewater infrastructure were geared towards increasing water usage. Water systems were designed for the demands that may occur twenty plus years in the future.4 If these demands do not come to fruition, then the system will be oversized based on per capita usage. Drought and conservation, exacerbated by overdesign, has negatively affected water infrastructure by detention time of treated water and gas buildup of wastewater systems.

 

With regards to extended detention time of treated water, pipes and pump stations were not designed to act as long-term storage devices, but that is exactly what they are doing. When pipes and pumps are sized to accommodate mass quantities of water, and customers use less, the water is stored in the distribution system for long periods of time. As water detention time increases chemical effectiveness subsides and adverse chemical reactions with water constituents increase, overall causing vast negative effects on the water infrastructure.

 

Secondly, gas buildup in wastewater systems is just as costly as extended detention time of treated water. If conserving the resource is crucial during drought conditions and customers are using less water; less water is flushed down the drain. Wastewater infrastructure was designed to account for future demand in the same way fresh water systems were. Following World War II, there was a shift from a largely rural population to more urban and suburban, couples were having children and a population boom occurred. Starting in the eighties, the conservation movement began leading to decreased water usage causing solids and chemical concentrations to increase. As concentrations went up, infrastructure deterioration accelerated. Just as with fresh water, wastewater collection systems were not designed for long term storage. Oversized lift stations and force mains were affected the most. When a lift station is oversized, and detention time increases the breakdown of human waste causes acid gases H2S and CO2 to form. Limited data on sulfates and inorganic phosphates show that because of this, concentrations increase by approximately thirty percent. This increase in concentration is in line with flow reduction.5 These gases wreak havoc on all infrastructure and especially metal, effecting: cast iron pumps, ductile iron pipes, and any unprotected electrical equipment. With drought induced low flows, lift stations take longer to fill then oversized pumps experience very short run times to empty the station. Leading to a slug effect in an oversized force main where pump cycle times are not long enough to fully evacuate from each pump cycle. Greater solids concentration and detention times are only exacerbated by drought in oversized infrastructure leading to faster deterioration of infrastructure.

 

Design engineers of yesteryear had to plan for future expansion based upon historic usage. There are rehabs happening every day to downsize water treatment and transport infrastructure. I have seen these on a local level because of the drop in per capita water use. By encouraging conservation, water entities are wreaking havoc on their infrastructure which must be repaired or replaced sooner, and the money isn’t there to take care of all the issues. If we correctly size our infrastructure design and installation, it will cost less to install, maintain and last longer in the process. Unfortunately, there is no silver bullet solution, it will take a whole new way of thinking to solve the water infrastructure issues of tomorrow.

 

  1. https://www.infrastructurereportcard.org/cat-item/drinking-water/

  2. Americans are conserving water like never before, according to the latest federal data – Christopher Ingraham

  3. The Energy Policy Act: Assessing Its Impact on Utilities – Amy Vickers

  4. Effects of Water Age on Distribution System Water Quality – EPA Office of Water (4601M)

  5. Effects of Water Conservation on Sanitary Sewers and Wastewater Treatment Plants – Jeffrey T. DeZellar, Walter J. Maier

 

About the Author

Clayton Coe is a Business Development Manager with Wachs Water Services, a Xylem Brand. He enjoys educating public and private stakeholders in all aspects of water. He has a diverse background in both the water and energy industries and a Master's Degree focused on Water Management & Hydrological Science. Clayton has worked for water infrastructure suppliers including National Waterworks and Xylem Inc. and water service providers including Wickson Creek Special Utility District and Severn Trent Services. He has inside and outside sales experience spanning multiple industries and field experience installing water and wastewater infrastructure.

 

 

Tags:  drought  engineering  infrastructure  water and wastewater  water conservation 

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