IMS Annual Conference 2019

A little spark - miles away - changed the universe for the Duchesne Valley Water Treatment Plant. It resulted in a massive forest fire, source water quality degradation, treatment challenges, a cancelled project at 95% design, and new project to address post fire realities.

This presentation outlines how rapid things can change when a forest fire hits the watershed, what was done operationally to address the post-fire water quality, and a new process improvement project to provide long-term plant resiliency against the effects of the fire. The presentation includes how treatment processes were impacted by the post-fire water quality and the selection process for determining whether pretreatment was needed upstream or downstream of the existing ozone system.

The Ashley Valley Water Treatment Plant, Duchesne Valley Water Treatment Plant and the Don A. Christiansen Water Treatment Plant all have different challenges in treating the raw water as it comes into the plant. These challenges are heavily influenced by natural and anthropogenic influences in the surrounding watershed. Some of these challenges include seasonal shifts in turbidity levels causing the operators to switch to a water source that has higher total organic carbon. Algal blooms in the spring and fall significantly increase filter head loss. Changes in the landscape due to fire have augmented the potential for more organic material and sediment to enter the waterway. Another challenge is having a major highway so close to the river that when a vehicle crashes there is a probability that pollutant material may enter the waterway. To determine water quality challenges and solutions within each watershed and to measure water quality coming into these 3 plants I regularly sample 5 reservoirs and 22 river sample sites. Working together, plant managers and operators continue to produce water that is safe to drink despite the many challenges that they face while treating the water.

Small-scale membrane filtration systems (

Flocculation of particles into larger and easily removable forms is necessary for efficient separation by sedimentation, filtration, or dewatering. Three types of polymers are discussed in regards to physical form, molecular weight, charge density, and size distribution. Proper way of handling and storage of polymer is reviewed as well as its shelf-life.

Quality of dilution water including hardness has tremendous impact on the efficiency of polymer solution. With increasing trend of utilizing reclaimed water for polymer mixing at most WWTPs, chlorine level of dilution water must be carefully monitored. When reclaimed water is used, aging of polymer solution is also carefully evaluated. Chlorine, suspended solids, and dissolved ions included in reclaimed water are reacting with polymer and resulting in degraded polymer solution during aging.

Preparing efficient polymer solution is one of several key factors for successful solid-liquid separation. Due to its unique property of polymer, polymer make-down requires well established scientific understanding. It includes the concept of two-stage mixing; very high energy mixing at the first stage followed by low energy mixing to minimize damaging polymer chains. Two-step dilution and adequate residence time are also required to achieve fully extended molecular structure of polymer in solution.

Solids production at water treatment plants is influenced by many factors such as coagulant chemical dosing, raw water quality, plant production, recycle, and possible use of powdered activated carbon. Many plants are removing historically higher levels of TOC and turbidity in order to achieve regulatory compliance, to meet aesthetic objectives, or to optimize subsequent downstream processes. This has led to peak solids production quantities that exceed the original design criteria and tax plant dewatering facilities.

Selecting solids management tactics will always remain a fit-for-purpose activity. Internal factors such as staff preferences and expertise, siting, and solids composition must be considered along with external factors such as climate conditions and ultimate disposal options for project success. In some cases, conventional drying techniques such as lagoons and drying beds are being enhanced and supplemented with bags made of geofabric textiles for an old-but-new approach. Elsewhere, screw presses offer advantages with respect to reliability, uptime, and reduced labor needs and are competing directly with equipment such as centrifuges as a cost effective method for mechanical dewatering.

Operating experiences, energy and chemical (polymer) requirements, successful design arrangements, and overall performance of low tech and high-tech Solids management methods will be summarized for the benefit of utilities and design engineers, using examples from recent full-scale applications.

The City of Mapleton, UT has received customer complaints over the years pertaining to drinking water taste, odor and color. As the City has continued to grow, water quality concerns have arisen as well pumping durations have increased. The City and J-U-B Engineers conducted a water quality assessment, characterizing risk and developing strategies to mitigate water quality risks.
A water sampling plan was developed at strategic locations in the distribution system. The analysis of the results focused first on source water chemistry and then on distribution system dynamics. The AWWA M68 manual was the guiding document through the assessment.
Being able to correlate customer complaints to operational conditions began to tell a story that suggests there is potential for differing source chemistry that impact taste, odor and color. There was no one single water quality parameter that can be attributed to customer complaints. Rather, awareness of source water interaction and how that source moves through the water distribution system provided a complete story. Data management and operations and maintenance strategies were recommended as the highest value solutions. The governing objective going forward is to proactively address water quality risk regarding customer confidence, that manifests in taste, odor and color concerns.

How do you design and construct a new finished water reservoir to enhance water quality for the largest water treatment plant in Utah, while still maintaining service to customers? Despite the fact that the Jordan Valley Water Treatment Plant capacity has more than quadrupled from 42 MGD to 180 MGD over the last four decades, the plant has always operated with a meager 8 MG of onsite storage capacity. The District identified a need for additional storage to solve these problems and retained Bowen, Collins & Associates to provide engineering services for the project. The project presented a number of challenges requiring innovative solutions, including:
1. CFD Modeling to Optimize Baffle Configuration: Development of computational fluid dynamics models in the design phase paid dividends by allowing us optimize hydraulic efficiency of the new reservoir. This efficiency is key in achieving the primary project goal to improve water quality by reducing the potential for formation of disinfection byproducts.
2. New Valve Technology: We leveraged new advances in butterfly valve technology to replace leaking and inoperable slide gates with more reliable double-offset butterfly valves that have much-improved sealing and operation characteristics.
3. Maintaining Service During Construction: In response to unanticipated changes in water demand during construction, the team worked together to modify construction sequencing and meet both supply and construction goals.
The new reservoir has been in service for more than a year now and the District is gratified with the improved flexibility and enhanced water quality that it provides.

Elevated trihalomethane (THM) levels are the most common violations of the Stage 2 DBP Rule in the United States. Municipalities across the country have employed a variety of methods to reduce THM formation rates. Utilities can incur costly and lengthy treatment plant upgrades, which often provide inadequate reduction levels in distribution networks due to continued THM formation at points distant from treatment plants.
Active tank mixing, in-tank aeration, and head-space ventilation systems are three tools that through thoughtful combination, can yield meaningful reductions in distribution system THM levels. These technologies make water storage tanks a smart and active agent in the management and improvement of water quality instead of a passive vessel holding water of uncertain quality.
In the past, THM reduction literature focused on the extensive deployment of capital equipment that obligated utilities to even greater lifetime energy consumption costs. Today, with a decade of compliance data from a variety of different system configurations, manufacturers can dramatically lower initial capital costs and significantly reduce energy costs while guaranteeing compliance.
A number of case studies depicting a variety of equipment options as well as process control options that represent the current state-of-the-art will be profiled to underscore the use of water reservoirs to help manage distribution network THM levels.

Per- and polyfluoroalkyl substances (PFAS, emerging contaminants of concern) have been detected in the water of multiple culinary water supply wells serving a confidential client. The wells are down gradient of a regional airport, where aqueous film forming foam (AFFF) containing PFAS was used in firefighting exercises. In 2017, the Minnesota Department of Health (MDH) issued new health based guidance values for PFAS that were lower than levels in many of the supply wells. The client has proactively blended water from several wells to supply water that is compliant with the new guidance while actively pursuing options to address PFAS in the water supply.

Steps taken to secure a PFAS free supply for the near and long term, include completing a water treatment study for PFAS that compared three different treatment media. The test included an accelerated column test (ACT) with granular activated carbon (GAC) and a single-pass ion exchange pilot test that simultaneously evaluated two different ion exchange (IX) resins. The data collected resulted in the ability to compare the three different types of treatment media and their effectiveness in removal of PFAS from drinking water. This presentation will provide detailed results of the ACT and pilot test.

Corrosion coupons are a simple, cost-effective research tool for measuring the corrosive properties of water. Planning for a successful corrosion coupon study requires careful consideration of what parameters the corrosion study will include. Some of the parameters include apparatus design, plumbing conditions, flow, coupon alloys, study duration, and analyses at the conclusion of the study. While corrosion coupon studies are well established in the water industry, the nuances of experimental design and execution are not well established. In this talk, we will discuss the corrosion coupon studies conducted by Central Utah Water Conservancy District and Jordan Valley Water Conservancy Districts and some of the lessons that we have learned during the design, experimental and analytical phases of these studies.

This presentation focuses on water quality characteristics affecting distribution system corrosion that are altered by water treatment processes. Oxidants used for iron/manganese removal and disinfection impact the oxidation/reduction potential, metal salt coagulants impact pH, lime softening chemicals impact pH and buffer capacity, and nanofiltration/reverse osmosis impact pH and dissolved solids. When these processes are optimized for their specific treatment objectives, the resulting water chemistry can impact corrosiveness. This presentation will describe these water chemistry impacts and outline treated water chemistry adjustments to mitigate corrosion impacts in the distribution system.

Park City Municipal Corporation (PCMC) has been issued Utah Pollutant Discharge Elimination System (UPDES) permits for the discharge of waters from Judge and Spiro Tunnels. PCMC entered into a Stipulated Compliance Order (SCO), concurrent with the issuance of the permits, which established schedules and certain terms and conditions for bringing the tunnel water metals discharges into compliance with the UPDES permits. The mine tunnel waters are currently used by PCMC (and other entities) for municipal drinking water, irrigation, and snowmaking.

In 2016, PCMC conducted pilot-scale testing to evaluate treatment alternatives for these water sources which formed the basis of design for the new 7.2 million gallons per day (mgd) 3Kings Water Treatment Plant in Park City. Based on the results, a treatment design approach was developed to address challenging water quality, optimize the facility layout to fit within a highly space constrained site, and balance the demand for visual appeal to the public.

This presentation will discuss the treatment technologies selected, process design approach, and how challenges were addressed while achieving architectural appeal.