Stream J: Drinking Water Issues

 

6.5 A tale of two methods: The arguments for and against adjusting pipe roughness coefficients

6.6 Disinfection by-product compliance for the Duteau Creek supply

6.7 Optimizing coagulation and addressing low alkalinity: Studies and laboratory testing at the Seymour-Capilano filtration plant

11.1 Direct feed reverse osmosis membrane filtration selected to treat challenging groundwater source

11.2 The evolution of drinking water treatment objectives for groundwater supplies In western Canada

11.3 The City of Vancouver's "Access to Water" program

11.4 Advances in UV technology and using UV for 4-log virus during primary disinfection of groundwater

11.5 Operation – Kapoor tunnel inspection

 


  

6.5 A tale of two methods: The arguments for and against adjusting pipe roughness coefficients

Presented By: Dr. Werner de Schaetzen, GeoAdvice Engineering Inc.
Time: Tuesday, 10:20 - 10:50 AM

A hydraulic model is a mathematical model of a water distribution system and is used to analyze the system's hydraulic behavior. A simplified model of the actual network is used. Before such model can be used, it must be adjusted to ensure that it will predict with reasonable accuracy the behavior of the water distribution system it models, i.e. it must be calibrated.

This paper will discuss the City of Coquitlam, BC water distribution system model calibration.

The model was set-up to use the Hazen-Williams headloss formula to estimate friction loss through water mains based on pipe roughness C-factors. A C-factor of 110 was assumed globally for all the water mains irrespective of age, material, and diameter. The model was first calibrated based on field data from the City SCADA system. Both the average and maximum days were used for model calibration (24 hour extended period calibration). Fire flow tests were then completed to validate the hydraulic model (steady state calibration). Finally, C-factor tests were completed to determine actual roughness coefficients.

A significant amount of effort during model calibration was devoted to correcting boundary facilities such as pump stations, storage facilities, demand data, and control valves. Key facility attributes that were reviewed and adjusted as necessary included pump curves, storage geometry, and controls. No micro-level calibration of adjusting roughness coefficients was completed.

Overall, an excellent correlation was achieved between the model results and measured data for both static and dynamic conditions without adjusting the pipe roughness C-factors.

pdf icon Presentation PDF


 

6.6 Disinfection by-product compliance for the Duteau Creek supply

Presented By: Brett deWynter, AECOM.
Time: Tuesday, 10:50 - 11:20 AM

The Regional District of North Okanagan (RDNO) provides water from the Duteau Creek source, which is a typical upland supply with reasonably low turbidity with somewhat high levels of dissolved natural organic matter. Given the characteristics of the raw water, this source is plagued with elevated levels of disinfection byproducts. The focus of the pilot study completed during the past couple of years has been to develop a complete treatment scheme that sustainably filters the water and results in compliant levels of disinfection byproducts.

The RDNO regularly tracks the total Trihalomethanes (TTHM's) levels within the distribution network through sampling at five different sites. Historically, the TTHM levels have consistently exceeded the Guidelines for Canadian Drinking Water Quality (GCDWQ) Maximum Acceptable Concentration (MAC) of 100 µg/L. Since the commissioning of the Duteau Creek water treatment plant (DCWTP), there has been a marked reduction in the levels of TTHM measured in the network. However, the TTHM results continue to be in excess of the GCDWQ MAC, ranging between roughly 100 and 200 µg/L.

To address the disinfection by-product concerns and to determine the optimum solution for the planned addition of filtration at the DCWTP, pilot testing was completed. The effectiveness of the following treatment processes at the pilot scale for TTHM reduction will be presented:

• Chloramination;
• Bio-filtration;
• MIOX; and
• Aeration for the stripping of chloroform based TTHM's.

 pdf icon  Presentation PDF


 

6.7 Optimizing coagulation and addressing low alkalinity: Studies and laboratory testing at the Seymour-Capilano filtration plant

Presented By: Jennifer Farr, Metro Vancouver.
Time: Tuesday, 11:20 - 11:50  AM

Metro Vancouver's Seymour-Capilano Filtration Plant (SCFP) uses source water from the Seymour Reservoir (present) and the Capilano Reservoir (future). During a heavy rainfall, these waters can experience increased turbidity and total organic carbon concentrations, while the already low alkalinity concentrations decrease. In October of 2012, another turbidity event occurred and the filtration plant acted as designed, but not without challenges. The SCFP treatment process uses a coagulant and coagulant-aid polymer to destabilize the naturally occurring dissolved and colloidal material, followed by flocculation and filtration with the assistance of a filter-aid polymer. The low alkalinity and high alum dose poses a challenge during turbidity events and reliable methods to determine suitable coagulants and optimal dosages are critical for effective operation during these events.

Coagulation optimization at the SCFP relies on charge neutralization using an online streaming current detector and laboratory tests for zeta-potential. This method of optimization is unique and has been extremely useful to quickly determine dosages during turbidity events instead of relying on jar testing.

The SCFP has a three train pilot plant that is an effective tool to test different chemicals. Several different coagulants and hydrated lime were tested to determine the best choice to address low alkalinity concerns from a treatment and cost perspective. The presentation discusses how to replicate water treatment processes, the SCFP turbidity event and the challenges involved, and the information required to determine optimal chemicals and dosages.

 


 

11.1 Direct feed reverse osmosis membrane filtration selected to treat challenging groundwater source

Presented By: Dr. Cristina Donesca, Urban Systems.
Time: Tuesday, 2:00 - 2:30 PM

The County of St. Paul is located northeast of Edmonton, Alberta and supplies water to the community of Ashmont. Source water is the Beverly Aquifer, a groundwater with extremely challenging water quality, i.e., 3.3 mg/L of ammonia, 10 mg/L of total organic carbon, 2.2 mg/L of iron, 0.1 mg/L of manganese, UVT of 60% and 1400 mg/L of total dissolved solids. The current treatment process does not meet 4-log virus inactivation. In addition, most customers do not drink tap water due to aesthetic reasons. The water treatment plant (WTP) is also at capacity and not able to meet future demand. The objective of the Ashmont WTP Upgrade project was to increase capacity, select a treatment process capable of meeting health and aesthetic treated water quality criteria, and minimize project life-cycle costs.

As part of this project, two treatment options were evaluated at pilot-scale, using an 8 gpm skid. Testing was done over a 6-month period. Option 1 consisted of direct raw water feed to a reverse osmosis (RO) membrane system, with upstream addition of anti-scalant. Option 2 consisted of pre-treatment with Greensand Plus/Anthracite pressure filtration followed by RO membrane filtration. Toray TMG10 membranes were tested with a recovery rate ranging between 70 and 80 percent.

Comparative pre-design life-cycle cost evaluation determined Option 1 to be $1.3 Million. Lower than Option 2. Based on pilot-scale results and cost evaluation Direct Feed RO membrane filtration was selected.

 pdf icon Presentation PDF


 

11.2 The evolution of drinking water treatment objectives for groundwater supplies In western Canada

Presented By: Matthew Henney, Associated Engineering.
Time: Tuesday, 2:30 - 3:00 PM

British Columbians have historically relied heavily on groundwater for domestic drinking water, agricultural and industrial needs: all resource demands not subject to regulation. In fact, more than 25% of our 4.4 million residents rely on wells to provide source water for potable use. Provincial health-related regulation has historically focussed on bacterial factors, often leaving groundwater supplies untreated. Common aesthetic water quality concerns, (e.g. iron, manganese, hardness) are typically accepted. However, we are in a state of change.

With the advent of DWPR (2003) and GWPR (2005), there has been an improved focus on well design, wellhead protection, and a clearer linkage with federal water quality guidelines (including a reduced arsenic MAC). Evaluation tools are now being proposed for determination of Groundwater at Risk of Containing Pathogens. The Water Sustainability Act may result in regulations (and limitations) around groundwater as a resource. Consumers are also seeking improved aesthetics.

Health Authorities largely have the discretion to address risks associated with a water system. Innovative, collaborative approaches to setting and meeting water quality and treatment objectives are needed.

We will present recent case studies from around BC and the Yukon illustrating varied technical challenges and solutions used for municipal groundwater supplies:

• GWUDI source using dual stage treatment coupled with wellhead and aquifer protection
• Virus inactivation using UV without chlorine
• Implementing secondary disinfection on a previously non-disinfected supply
• Re-evaluating a high iron aquifer for future use
• Blending of treated surface water and groundwater supplies
• Water quality considerations in Aquifer Storage and Recovery (ASR) schemes

pdf icon Presentation PDF


 

11.3 The City of Vancouver's "Access to Water" program

Presented By: Laura Hosokawa, City of Vancouver.
Time: Tuesday, 3:20 - 3:50 PM

With ever increasing social and recreational demands, the City of Vancouver supports an 'Access to Water' program, which enables the installation and maintenance of public drinking water infrastructure throughout Vancouver.

The City's Access to Water program works with a variety of City departments and the public, to select locations and install drinking fountains and bottle filling stations. The selection and installation process includes: Identifying areas of need, evaluating location suitability, selecting the appropriate type of infrastructure for the location (frost-free fountains, temporary fountains), and coordinating the City's Water, Sewer and Streets Operations departments to install the fountain.

With the growing fountain inventory, operating and maintenance work has become a priority. The City is continually working to improve upon our maintenance and operating program; recently, a pilot project was initiated to ensure that the water dispensed from the fountains meets the City's water quality standards.

Specifically, the pilot compliments our citywide water quality testing that is undertaken at 55 monitoring stations across the city. Additional water testing was piloted at select drinking fountains this summer, combining a detailed examination of the fountain physical condition, location, and water quality. Results from water quality testing are being used in the program to determine best management practices for actual and perceived high quality water for public use.

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11.4 Advances in UV technology and using UV for 4-log virus during primary disinfection of groundwater

Presented By: John Houghton, Trojan Technologies.
Time: Tuesday, 3:50 - 4:20 PM

Groundwater is an important source of municipal drinking water in British Columbia. In 2011 alone, over 100 million cubic meters of groundwater were treated for public consumption. Due to its "natural" filtration, water from groundwater aquifers generally contains fewer pathogens than surface waters. However, there are concerns that groundwater supplies are becoming increasingly exposed to pathogens including bacteria and viruses due to aging and expanding wastewater collection systems as well as failing septic systems. As a result of these concerns, Canadian Drinking Water Guidelines suggest, and in some cases require, facilities to carry out 4-log (99.99%) disinfection of enteric viruses.

The use of high-UV resistance microbial surrogates has resulted in third-party-validated UV systems designed for 4-log inactivation of virus (including adenovirus) using low-pressure high-output (LPHO) UV lamps. Several small communities depending on groundwater for their drinking water supply have evaluated UV and chlorine, and found UV to be the best approach to primary disinfection for a number of reasons. First, UV provides a low-cost approach to virus treatment that requires minimal footprint and avoids costly infrastructure improvements such as contact tanks that may be required to maintain appropriate chlorine contact time. Secondly, decreased dependence on chemicals for disinfection reduces the potential for the formation of harmful chemical by-products such as trihalomethanes (THM) and haloacetic acids (HAA).

This presentation discusses the benefits of using UV to meet guidelines for groundwater disinfection as well as highlights UV performance at particular sites where UV is currently installed for 4-log virus inactivation.

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11.5 Operation – Kapoor Tunnel Inspection

Presented By: Peter Sparanese and Russ Thomas, Capital Regional District.
Time: Tuesday, 4:20 - 4:50 PM

The Capital Regional District (CRD) supplies drinking water for residential, commercial, institutional and agriculture uses to approximately 350,000 people within the Greater Victoria area located on the southeast corner of Vancouver Island. The population served by the Greater Victoria Water Supply System is the third largest in British Columbia and located within the traditional territories of the Coast Salish people.

Each year, the CRD inspects the Kapoor Tunnel to review its overall condition. This is executed with tactical precision with most of the work being conducted behind the scene. The Kapoor Tunnel was constructed in the 1969 to provide additional capacity to a growing region and is approximately 2.3 metre in diameter (except for the last 200 metres, which is, horseshoe shaped) and 8.8 kilometers in length made primarily from concrete in a cored rock tunnel. The Kapoor Tunnel is one component of the overall water supply system transporting drinking water from Sooke Lake Reservoir to Japan Gulch Treatment Plant and is capable of providing flow of 167MGD to the customers. This infrastructure is of critical importance to the sustainability of the Greater Victoria area and supports the economic vitality, social well-being and environment aspects of the greater community.

Executing such a significant operational activity has many inherent risks that need to be managed and mitigated and requires the expertise and coordination of many individuals. Some of the major risks include availability of water, water quality, worker safety, engineering, operation, and communications. This presentation will provide an in-depth account of the activities associated with this significant task and how risks were managed.

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