The Design of the Water Treatment Plant

The City was conducting a pilot scale study to evaluate the efficacy of the best technologies to provide useful information for the design and construction of a water treatment system for treating the water drawn from wells 1, 2, 3, 6, 7 and 8. Kerr Wood Leidal Associates (KWL) was retained to provide cost evaluations for three options for design and construction of water treatment plant(s).

The options are as follows:

• Option 1 is based on one water treatment plant at the Oxford site;
• Option 2 is based on two water treatment plants, one at Merklin site and another at Oxford site; and
• Option 3 is one water treatment plant covering all the above referenced wells in addition to connecting existing well # 4 to the plant located at the Oxford site.

Water Treatment Capacity and Process

The seven (7) wells have different levels of Ammonia, Iron, Manganese and Arsenic in the water. The goal is to have a water treatment system that is capable of addressing all these chemicals and metals. Currently wells 1, 2, 3 and 8 supply water to the Oxford reservoir and wells 6 and 7 supply water to the Merklin reservoir. The existing secondary disinfection systems at both pumping stations will be used for the water treatment plant effluent secondary disinfection.

Water Treatment Processes

The treatment process considered the method of oxidation followed by filtration for the removal of manganese and arsenic. To identify the best technologies that will provide a significant reduction of arsenic and manganese and deliver water that is safe, of high quality and clarity, a partnership was approved by the City Council with the RES’EAU-WaterNet, based at the University of British Columbia. This collaboration included investigating the efficacy of different technologies to provide a successful and sustainable solution to address the water quality parameters of concern. The project started in December 2016, the RES’EAU-WaterNet delivered a Mobile Pilot Plant to the Merklin Pumping Station to conduct the experiments.

After completion of the pilot plant study and analysis of the collected data, a report was prepared that included all the treatment processes considered in the experimental project. The report was provided to the contractors/consultants selected for the RFP following the signing of a Non-Disclosure Agreement. The report data provided useful information to the design team. The report is available on the website.

Design and Selection of Water Treatment 

In order to accommodate the water treatment units, an insulated steel frame building (s) were considered for 1 or 2 water treatment plants. The building would include the area for the filter units and accessories and modest areas for office, chemical storage, building ventilation, electrical control room and lab.

Pipe Network

Under each option, additional pipe work is required for moving the water from the well pump discharge lines to the treatment plant and back to the treated water reservoirs located at Merklin and Oxford sites. The pipe work was included, as required for all the options in the budget for connecting the well discharge headers to the treatment plants and from the treatment plants to the reservoirs at Oxford and Merklin sites.

Available Space

The available space for a potential water plant at both the Merklin and Oxford Pumping Stations are:

• Merklin Pumping Station: 331.2 m²; and
• Oxford Pumping Station: 1,251.26 m.

Cost Opinion

The cost opinion is based upon the following:

• No water distribution system improvements are required to boost distribution system pressures;
• Existing equipment for secondary disinfection will be re-used; and
• New power service costs by BC Hydro will be negligible but will need to be verified once a preliminary design has been completed for the facility.

Recommendation

It was recommended to have only “One Water Treatment Plant” located at the Oxford Pumping Station Site for the following reasons:

1. The difference in water quality between the two sites (Merklin and Oxford) would require a different treatment operation setup on each site to deal with the different water quality parameters (Ammonia, Iron, Manganese, and Arsenic) if two water treatment plants are considered. Blending the water from the 7 wells and provide the treatment processes required and have the same water quality pumped from the two pumping stations would be a better engineering, operational and cost effective approach.
2. The available space at the Merklin pumping station is very small, and less than 30% of the available space at the Oxford pumping station.
3. The estimated Capital cost difference associated with building one plant at Oxford, and connecting Well 4 to Oxford, which is necessary in any case, is estimated to be $964,000 less than building two plants (one at Oxford and another at Merklin).
4. The Operation and Maintenance Cost for one plant at the Oxford (including connection to Well 4 - Option 3) is estimated to be $422,000 less than for two plants.

The Development of Request for Qualification (RFQ) and Request for Proposals (RFP)

The City issued a Request for Qualifications (RFQ) on BC BID for a Design-Build (DB) of the Oxford Water Treatment Plant Project. The intent of the RFQ was to seek statements of qualifications (responses) from suitably qualified candidates interested in a DB opportunity for a water treatment plant for arsenic and manganese removal. The proposed work was fully described in the Request for Proposal Documents (RFP) that followed the RFQ process.

The City received nine (9) submissions and worked on the evaluation of the proponent’s submittal and shortlisted three (3) proponents to receive the RFP. The purpose of the RFP was to invite eligible proponents to prepare and submit competitive proposals to design, construct, commission, and provide one (1) year operational support and a two (2) year warranty for the Oxford Water Treatment Plant.

The City worked with Kerr Wood Leidal (KWL) (who developed the RFP and managed the progress and evaluation of the submissions) and Colliers Project Leaders (who assumed the responsibility of the project management until project completion) to develop a detailed technical evaluation to each proposal, and submitted questions to each group to clarify design issues. The response to questions from the technical evaluation from both groups was evaluated by the City staff of White Rock, KWL and Colliers Project Leaders. 

A unanimous decision to select NAC Constructors Ltd./Associated Engineering based on the technical evaluation was taken by the technical evaluation committee (City of White Rock, KWL & Colliers Project Leaders).

The financial proposals were reviewed independently after the technical review was completed. The NAC Constructors Ltd. and Associated Engineering Ltd team were selected based on both the technical and financial proposal submissions.

Based upon the outcome of the review teams’ analysis, it was recommended that the City select the NAC Constructors Ltd. and Associated Engineering Ltd team as the successful Proponent, subject only to final negotiations for a completed contract. The NAC financial submission is for a Total Guaranteed Maximum Price $12,611,000 (excluding GST). It is noted that the estimate for the annual operations cost will be approximately $655,000.

The recommendation was presented to the City Council at its meeting on November 6, 2017. The City Council awarded NAC Constructors Ltd. the contract for the Design Build of the Water Treatment Plant for the amount of $12,611,000 (excluding GST).

NAC started work right away and, under the guidance of the City, began clearing the site of trees and brush in December 2017.

Detailed Design Reports

At the 30%, 50%, 90% and 100% design milestones, the NAC/ Associated team will submit Design Reports that reflect the status of the technical design of the Oxford WTP. The reports will be complementary to the drawing and specification packages also issued at these milestones.

Water Treatment Processes and Technologies Design

Manganese removal in groundwater supplies has been practiced for many decades. Technology approaches are mature and improvements in treatment efficiency have been only incremental. Attention to arsenic removal has been comparatively recent and has been driven by broad emerging concerns over long-term human exposure risks of arsenic and the subsequent tightening of drinking water arsenic regulations. Available technologies and processes to remove arsenic are several. There has been significant research into arsenic treatment technologies over the last 20 years. Often the selection of the right (or best) technology must consider what other constituents are in the water that would also have to be removed or may otherwise interfere with the arsenic removal process. Like many southwest BC groundwaters, White Rock’s groundwater is of high quality with manganese (and sometimes iron) being the issues of concern along with arsenic levels just at or above the Health Canada MAC. Therefore, the use of advanced and capital cost-intensive treatment technologies are not generally warranted. Whereas biofiltration or membrane technologies must often be considered in groundwaters where there is concurrent high TDS, ammonia, organics, iron, manganese and/or arsenic, the use of conventional greensand and arsenic polishing technologies is more appropriate for groundwater sources like White Rock’s. It is from this perspective that the NAC | Associated Team has chosen filtration using GreenSand Plus media for manganese reduction and the AdEdge

E33 adsorption media for arsenic polishing to achieve the low target levels required by the City. The use of ozone for pre-oxidation of the arsenic and manganese prior to the two-stage filtration and adsorption process will be implement;

• Many arsenic removal technologies are most effective at removing the pentavalent form of arsenic “Arsenate”, As(V).
• Therefore, many treatment systems include an oxidation step to convert Arsenite As(III) to arsenate As(V).
• Oxidation alone does not remove arsenic from solution, and must be coupled with a removal process such as coagulation, adsorption or ion exchange

The use of steel pressure vessels for the key unit processes is not only appropriate for long-term durability but also allows for future changes in filter and/or adsorption media design should improvements become available. The new water treatment plant will have a Supervisory Control and Data Acquisition (SCADA) for operation, control and data acquisition for the water treatment processes. The existing SCADA will be integrated into the water treatment plant system to have a central operation and control at the water treatment plant Control Room.

2019

April 29, 2019 - Update on Water Testing

March 14, 2019 - Notice of Water Testing until April 15, 2019

2018

September 20, 2018 - White Rock Makes Significant Water Quality Enhancements Thanks to Clean Water & Wastewater Fund

2017

November 8, 2017 - White Rock moves Forward with Water Treatment Plant Following Study by World-Class Scientists

March 17, 2017 - White Rock Receives Historic Water Funding Towards Removal of Arsenic and Manganese

2016

November 29, 2016 - Tour of RES'EAU WaterNET's Mobile Water Treatment (Pilot Plant)