January 2019 Print

President's Report

I hope everyone enjoyed the holidays. We are starting a new year, and with it comes new opportunities for 2019. I have been thinking about how 2018 went, and what I would like to do differently in 2019. I want to continue to grow in my career, so I am doing a self-inventory to figure out what I need to keep doing, what I need to stop doing, and what I need to start doing. I recently read an article on LinkedIn about work-life balance titled, “Leave the office on time.” There are several theories on work-life balance and how to achieve it. Some like to call it work-life integration, but I think everyone is unique and needs to find their own way to manage their responsibilities at work, home, and in personal lives. This LinkedIn article resonated with me and I wanted to share some of the ideas that the author discussed.

Work never ends. We need to find ways to manage our time wisely because there is always a project or other responsibility we need to take care of each day. Learn time management skills and stop trying to get everything done in a day.

Interest of a client is important, so is your family. Each day I get maybe two hours with my family in the evening. Is this enough? Give your family the time they deserve. Your family will enrich your life more than a client, no matter how good the client is.

If you fall in life neither your client or boss will lend you a helping hand, your family will. This sounds kind of harsh. Most bosses are trying to support and help their employees as best as they can, but that is the point. They “try.” Families will support you and lend a helping hand.

A person who stays late at the office is not a hardworking person. I have to admit that I was almost offended when I read this. The point is that we should look at what we are trying to accomplish by consistently working 10 to 12-hour days or over the weekend. Are we adding value and is it worth the impacts to your family? Use your time wisely and plan your day before it starts.

You did not study hard or struggle in life to become a machine. A machine can work 24/7 with the right fuel. I am human and can’t work 24/7. I need to take care of myself, so I can be a productive and valuable member of my team. Remember that you only have 24 hours in a day (8 hours to sleep, 8 hours to work, and 8 hours for yourself).

This year the Utah Section would also like to give back to our community. The Utah Section Board has been discussing service opportunities for 2019 and ways to give back to our communities. We have decided on a couple activities.

First is working at the Ronald McDonald House. The Younger Member Forum (YMF) will be preparing a meal for the families who are staying at Ronald McDonald House. The Section will support the YMF, both financially and with volunteers. The meal is planned for February 28th and more information will be shared with ASCE members.

The second is an activity with Liberty Elementary School in Salt Lake City. This is a Title I school, and some of the students come from refugee or homeless families. One of the teachers recently watched the Dream Big movie from ASCE and got excited about showing the movie to their students. I met with the Principal and some of the teachers to discuss their vision for this activity. They want to show Dream Big to their student body and their families, and have an engineer visit each class in the school and do a fun activity. ASCE is teaming with ACEC to visit Liberty Elementary on February 19th to meet the students and show Dream Big. Mark your calendars. More information will be coming.

I am looking forward to 2019 and the opportunities it holds. I wish the best to all of you this year and am excited to see all the great things that ASCE members will accomplish.

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Technical Article

Wildfires and Civil Engineering

Ben Willardson, PE, PhD – CWE

Mike Rau - CUWCD

Fire plays an important role in most wildland ecosystems. Vegetation often depends on fire to create a period of rebirth by removing dead materials and releasing nutrients back into the environment (Ainsworth and Doss, 1995).  Across the United States, wildfires burn more than 4 million acres annually, costing Federal agencies in excess of $768 million a year (1994-2002) in suppression alone (Butry et al., 2008).  Some of the most well-known fires have burned large sections of famous national parks such as Yellowstone and Yosemite. 

Utah was impacted by several fires in 2018, including the Dollar Ridge, Bear Trap, Coal Hollow, Pole Creek, Notch, and Willow Creek Fires. Estimates of the burned watershed areas is over 200,000 acres, or over 300 square miles of forest lands.  These fires have impacted many watersheds that provide water supplies for cities and towns throughout Utah.  These fires set the stage for impacts to highways, drinking water systems, and dwellings.  The impacts to the Duchesne Valley Water Treatment Plant operated by the Central Utah Water Conservancy District is provided as an example of the impacts faced by civil engineers after fire.  See Figure 1.

Figure 1 - Dollar Ridge Fire

Between the 1930s and 1970s, firefighting tactics and equipment became increasingly more sophisticated and effective fire suppression efforts increased dramatically, and the annual acreage consumed by wildfires in the lower 48 states dropped from 40 to 50 million acres a year (Laverty, 2001).   Across the Western United States, the aggressive fire suppression policies appeared to be successful.  However, these policies have set the stage for the intense fires experienced over the last few decades. 

Many fires are caused by lightning. Others are man-made.

Full fire suppression gave forests and wildlands the opportunity to grow without the effects of fire, disrupting ecological cycles and changing the structure and make-up of the forests (Laverty, 2001; Pierson, Jr. et. al, 2003). Other vegetation that had been regularly eliminated from forests by periodic, low-intensity fires, became a dominant part of the forest.  This vegetation became susceptible to insects and disease, which left dead trees, mixed brush, and downed material to fill the forest floor. The accumulation of materials, when dried by extended periods of drought, creates the fuels that allow extremely large fires to burn across large areas of forest and wildland (Laverty, 2001).

Changes to Vegetation and Soils During Fires

Fire in forested areas is an important natural disturbance mechanism that plays a role of variable significance depending on climate, fire frequency, and geomorphic conditions. This is particularly true in regions where frequent fires, steep terrain, vegetation, and post-fire seasonal precipitation interact to produce dramatic impacts (USDA, 2005). The amount of vegetation consumed by a fire depends on the fire regime and fire severity (USDA, 2005).  The USDA (2005) provides an in-depth discussion of fire regimes and severities.  Low severity fires rarely produce adverse effects on watershed hydrologic conditions, while high severity fires generally result in higher runoff and erosion. 

Wildfires can leave large areas devoid of vegetation and vulnerable to producing large volumes of runoff leading to flash floods, floods, or mudslides (NOAA, 2004). The high rate of runoff following brush fires may result from the combined effects of denudation and formation of a water-repellent soil layer beneath the ground surface (Nasseri, 1988).  The type of vegetative cover on a soil changes the infiltration rates.  This is due to the effects of vegetation on slowing surface runoff velocities.  Loss of surface litter, vegetative basal cover, and the associated microtopographic relief also reduce surface storage of water crucial for reducing runoff and increasing infiltration (Pierson, Jr. et. al, 2003).  The removal of vegetation due to fires increases runoff as surface runoff velocities increase, decreasing the time available for infiltration.  Fires also change soil characteristics.

Fires induce temperatures at ground level reaching six to seven hundred degrees centigrade. Burning vegetation, especially chaparral, releases oils, resins, and waxy fats stored in plants and plant litter as intense heat vaporizes the vegetation (McPhee, 1989). The soil acts as an insulator, keeping temperatures a few centimeters below the surface much cooler. This temperature difference allows condensation of vaporized substances, forming a hydrophobic layer. This layer is impermeable and prevents water from reaching all but the first few inches of soil.  It also slows evaporation through the soil (Ainsworth and Doss, 1995).  The extent and depth of a hydrophobic layer depends on the type of soil, the fire intensity, and antecedent soil moisture. Clay soils tend to resists the formation of a hydrophobic layer.  Sandy and sandy loam soils are far more susceptible to hydrophobic conditions (DeBano 1987).

If a drop of water is placed on a pre-burn sample of sandy loam soil, the water will all but disappear.  If the same water drop is placed on a post-burn sample, the drop will ball up and may remain there for hours.  Water quickly saturates the thin layer of permeable soil above the hydrophobic zone not being slowed by a vegetative canopy. Slower infiltration rates result in an increased intensity of surface runoff and erosion.  These changes to the soil and vegetation lead to higher soil erosion rates. Figure 2 shows expected probabilities of debris flow in watershed areas due to impacts from the Dollar Fire area above Starvation Reservoir.

Figure 2 - Expecter Change to Soil Erosion and Debris Flows - Dollar Fire

Changes to Runoff After Fires

Fire changes the soil and vegetation characteristics of a watershed. The changes result in higher runoff rates and more erosion within the watershed.  Erosion of sediment leads to bulking of flows, where entrained sediment increases the volume of runoff.   Vegetation, litter, rocks and other forms of ground cover create barriers that slow and spread water movement across the soil surface allowing more time for water to infiltrate over a larger surface area. Fire removes most of these barriers and allows the water to concentrate into rills.  Rills allow increased flow depth and velocity.  Higher flow depths and velocities significantly decreases runoff response time and increases runoff volume in streams (Pierson, Jr. et. al, 2003).  Several studies have been conducted to determine the influence of fire on the volume and peak runoff from watersheds. 

Work by Davis (1977) suggests that many post fire flows are debris flows. In the watersheds that Davis studied he found bulking ratios in runoff ranged from 0.5% to 2.5% by volume for normal flows to 40% to 60% by volume for post fire flows. Bulking can increase runoff volumes and peaks significantly.  However, it will not be further evaluated in this study.

Veenhuis (2002) studied two burned watersheds in New Mexico.  He noted that storm flows increased dramatically after the wildfire.  Peak flows in each of these two watersheds increased to about 160 times the maximum-recorded flood prior to the fire.  As vegetation reestablished itself in the second year, the annual maximum peak flow was reduced to approximately 10 to 15 times the pre-fire annual maximum peak flow.  During the third year, maximum annual peak flows were reduced to about three to five times the pre-fire maximum peak flow. In the 22 years since the La Mesa wildfire, flood magnitudes have not completely returned to pre-fire magnitudes.  The number of larger than normal peak flows seems to be most pronounced for 3 years after the fire. (Veenhuis, 2002).  Other studies also indicate significant increases in runoff after fire (Pierson, Jr. et. al, 2003; Nasseri, 1988; Wondzell et. al, 2003). Figure 3 shows sediment deposited in the Strawberry River floodplain after rainfall in July 2018.

Figure 3 - Sediment in Strawberry River Below Timber Canyon after Dollar Fire - July 2018

Watershed Recovery From Fires

The vegetation of chaparral communities has evolved to a point it requires fire to spawn regeneration. Many studies have shown an increase in runoff and erosion rates the first year following fire, with recovery to pre-fire rates generally within five years (Wright and Bailey 1982).  The timing and extent of recovery is highly dependent on precipitation, slope and vegetation type (Branson et al. 1981, Wright et al. 1982, Knight et al. 1983, Wilcox et al. 1988).   Pierson, Jr. et. al (2003) noted that water repellency of the hydrophobic water layer deteriorates over time, resulting in a gradual recovery in the infiltration capacity of the soil.

The Ainsworth and Doss (1995) qualitative summary has been numerically quantified by other studies.   Pierson, Jr. et. al, (2003) studied two watersheds in Idaho which were severely burned.  They note that virtually all vegetation and litter was consumed during the fire. Bare ground for all burned sites was greater than 95% resulting in increased soil exposure to the erosive forces of raindrop impact and overland flow.   It took two growing seasons and three winters for litter accumulation to reduce the amount of bare ground on the burned sites to near 50 percent.  Watershed vegetation recovers to 90 percent of the pre-fire condition after five years.  This is consistent with the results of the other researchers, both quantitatively and qualitatively.

Local Impacts and Civil Engineering

Fires and post-fire impacts often impact built infrastructure and utility systems that are operated by civil engineers. These impacts include higher runoff volumes, debris flows, and impacts to water quality.  One example of impacts to facilities in Utah in 2018 include impacts to watersheds and water supply systems.

Figure 4 shows debris from the fire was washed down to the culvert during a summer thunderstorm.

Figure 4 - Impacts to Culvert on Strawberry River

Another impact with long-term implications is the generation of higher than normal sediment loads in the flows from the watershed. The Dollar Ridge Fire burned the watershed tributary to Starvation Reservoir.  The Central Utah Water Conservancy District operates the Duchesne Valley Water Treatment Plant (DVWTP) that draws water from Starvation Reservoir for treatment and distribution.  The plant is the only water supply for parts of Duschesne County.  

After the fire and initial assessment, CUWCD was concerned with operation of the plant in the impacted system. The pollutants of concern included turbidity, nutrients, algae growth, organics, disinfection byproducts (DBPs) and dissolved oxygen.  Turbidity from increased sediment has the potential to impact the treatment and filtration systems, as well as impact fish within the reservoir.  Nutrients, such as phosphorous, increase the potential for algae growth, which then interferes with the filtration processes and has the potential to cause cyanobacteria blooms.  Increased organics in the water cause more disinfectant demand, which leads to increased disinfection by-products (DBPs), and can also change both the taste and odor of the water delivered to end users.  Increases in suspended solids can cause lower dissolved oxygen, reducing the oxygen available for fish within the reservoir. Figure 5 shows the results of sampling on several days at one of the monitoring locations in Starvation Reservoir.

The water intake from Starvation Reservoir near the DVWTP intake is usually less than 3.0 NTU. As a direct filtration plant, the DVWTP cannot treat high turbidity water under Utah rule R309-530-5.3.g.  The rule requires that the plant be designed and operated so that it will automatically shut down when source water turbidity is 20 NTU for more than three hours, or when source water turbidity exceeds 30 NTU at any time.

Figure 5 - Turbidity Monitoring Locations and Results on Starvation Reservoir

Figure 6 - Turbid Water Channeled Through the Reservoir and Flowed Through the Outlet of the Dam at >1000 NTU

After the fire and resulting debris flows high turbidity water channeled across the bottom of the reservoir following the prior river channel and came through the Starvation Dam outlet at more than1000 NTU. This type of flow through the reservoir had never been observed historically. See Figure 6.  During this condition the water near the intake, 2 meters above the bottom of the reservoir was 61 NTU, with approximately 6 to 8 NTU coming into the plant.  The CUWCD mobilized a sampling and monitoring team to evaluate turbidity within the lake.  The team sampled several areas at several depths on various days.  Figure 5 shows the locations and the turbidity at various depths in the reservoir at one of the sampling locations.  The turbidity was impacted by thunderstorms that washed down significant sediment during a storm that produced over 2,000 cubic feet per second in the Strawberry River.  Figure 6 shows the flows coming out of Starvation Reservoir when the high turbidity water was channeling all the way through the reservoir and coming out of the dam.  This sediment has the potential to shut down this water supply to parts of the Duchesne Valley.

As discussed above, watershed recovery takes 5 to 10 years to complete. The size of the fire limits the effectiveness of erosion mitigation measures.  The ability of the CUWCD to deploy standard mitigation measures are hampered by geology, terrain, and the highly erosive soil.  There will be some seeding this year in an effort to encourage revegetation within the burned area.

Water quality impacts could likely continue for foreseeable future as the watershed slowly recovers. Although there were a few thunderstorms after the fire, there is still sediment within the watershed with no vegetation to hold it in place.  Due to the nature of burned watersheds, is expected that average storms will produce higher flow rates with larger loads of sediment, organics, and debris.  These impacts will taper off as the watershed recovers.

The DVWTP process is not designed to treat high turbidity and is restricted by law. The current process was designed based on past water quality which was stable for 40 years and has now been impacted for years to come.  These changes will require changes in the treatment process to meet the impacted conditions.  The changes may include clarification, with flocculation/sedimentation processes and may also require alternative water sources.

There may be a potential for emergency funding through the Federal Emergency Management Agency to implement watershed recovery programs or fund plant upgrades to handle the changed conditions. Civil engineers will be considering many of these choices to come up with the solution that will best meet the needs of the community served by the DVWTP in the coming years. 

Wildfires are a natural disaster that cause impacts to the communities we live in and work with. The increase the chances for flooding, debris flows, and impacts to utility systems like the WVWTP.  Civil engineers need to consider the risks of fire and after effects when designing the systems that serve our communities. 

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Wasatch Front Branch Update

Last month the Wasatch front branch had the privilege of hearing from Dr. Michael Johnson from Utah State University on their work on the Oroville Dam spillway project. We appreciate his willingness to take time to come talk to us about the amazing work done to stabilize the spillway and reconstruct it as well. This month we will be hearing from Michael Smith, the Utah director of ACEC about our annual legislative update and the bills that may impact us as civil engineers. We would also like to thank everyone that participated in our sub for Santa drive last month. It was a great success. 

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Northern Utah Branch Update

Todd Finlinson from UDOT gave us a great presentation in December. He was able to answer the questions that we had about the UDOT permitting system and give us an overall better understanding of the UDOT website and its resources.

This month our luncheon presentation will be given by Dayton Crites, the Cache County Trails Planner. He will be speaking about future trail plans in Cache County and also about possible funding sources for these projects and others. Many of the local engineering firms are involved in various design and management roles for these trail systems and will enjoy this topic of special interest.

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Central Utah Branch Update

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Luncheon

The CUB Luncheon for January will be presented by Dan Goodrich, a structural engineer at CKR Engineers.   In 2012, BYU decided to enlarge and upgrade the existing scoreboard displays for the football stadium.  The old scoreboards were outdated and undersized for a modern stadium experience expected by fans.  The original plan was to nearly double the size of the original scoreboards, along with increasing the height.  This presented some unique and challenging structural issues.  We will hear about the design challenges and solutions. 

 

Call for Presentation Ideas

CUB is still looking for presentation ideas for the upcoming months.  We are interested in having presentations on projects, research, historical information, and ethics discussions from across the civil engineering spectrum (geotech, transportation, water, structures, etc…).  Please contact Ben Willardson at bwillardson@cwecorp.com, or call him at (801) 310-6153 if you are interested in presenting to the group.  We would love to hear from you.

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Structural Engineering Institute Chapter

There are some important events coming up to put on our calendars.  Foremost is Structures Congress 2019.  It will be held April 24-27 in Orlando, Florida.  The conference will three Plenary Speakers, three Special Sessions and numerous networking opportunities.  This is a great opportunity to learn about structural events and practices worldwide and talk with our peers from across the country.  Look for additional information elsewhere in this month’s Civil Source and visit the official conference website for all of the up-to-date information.

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Utah Geo-Institute Chapter

As we look ahead to 2019, we look forward to the following upcoming events:

·       International Conference on Case Histories in Geotechnical Engineering conference in Philadelphia, Pennsylvania on March 24-27th.  This GeoCongress is unique in that it focuses on bringing together researchers, practitioners, students, and policy makers from around the globe to share their lessons learned and case histories. Additional information and registration information can be found at the following website: https://www.geocongress.org/. 

·       The Utah Chapter was awarded a guest lecture from the ASCE Geo-Institute’s Cross USA Lecturer Program this year.  Dr. Paul Mayne will be lecturing to our membership on April 24th, 2019.  As part of the event, we are looking for sponsors to support refreshments and other event expenses. If you are interested, in being a sponsor for the event, please email ryanm@gerhartcole.com for details.

We would like to ask our members to let us know of topics or upcoming events of interest as we plan for 2019.  Thanks again for your continued support.

- Ryan Maw

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Announcements

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