TAKE 5: Treatment plant takes pride in water quality
This week, we Take 5 with Scott M. Christiansen, the superintendent of the city of Sanford’s water treatment plant on Poplar Springs Road. Christiansen, a native of Fayetteville, earned a degree in environmental studies from UNC-Wilmington in 1994. He was named superintendent of the city's water plant in 2004, and his responsibilities include overseeing and managing all aspects of the treatment and distribution of drinking water, including laboratory sampling and analysis, equipment maintenance and plant operations.
What is the status of the plant's capacity?
Currently the plant is permitted to treat and pump 12 million gallons daily. We average 7 million gallons daily, which is approximately 60 percent of capacity. The plant was permitted for 6 million gallons daily when it was placed into service in 1971. The capacity was doubled in 1992 and has served the region for more than 20 years.
There have been multiple upgrades throughout the years to both improve the treatment and increase the redundancy in operations to prevent outages. Recently, in 2010, the 2 million gallon storage tank at the plant was rehabilitated. In 2012, we saw the replacement of a 600HP diesel pump for emergency power outages, and in 2013, we saw the replacement of a motor control center that powers a 700HP electric pump. There is adequate capacity for several years, and an expansion could be on the horizon dependent on the growth of the region.
We experienced a very wet spring and summer. How does excess rainfall impact the work you do at the water treatment plant?
The excessive rainfall we have received this year definitely has an impact in treating the water. The Cape Fear River Basin drains an area of approximately 3,400 square miles. The Deep, Haw and Rocky rivers form the headwaters of the Cape Fear River, augmented by releases of Jordan Lake and Randleman Lake.
Our intake is located in close proximity to the headwaters, and under normal rainfall, the majority of the water originates from the Haw River. During periods of abundant rainfall, we receive a greater blending of the rivers, increasing the amount of water received from both the Deep and Rocky rivers. This blending alters the water chemistry, and treating the water becomes a greater challenge. Thankfully, we have veteran staff of professionals who can modify the treatment based on experience and science to achieve our goal of high water quality.
The additional rainfall does ensure an adequate water supply, and the increased volume dilutes undesirable contaminants such as naturally occurring metals (iron and manganese) and algae. Elevated metals and algae increase the treatment process and cost.
The city’s water and sewer rates changed in August. Talk about what planning and analysis went into structuring the rates.
In 2007, the city began working with utility management firm Raftelis Financial Consultants to study and manage the Water and Sewer Operating Fund. Raftelis studied the city's capital improvement plan and the fund's overall consumption history, operating costs, capital outlay, debt service and bond covenants.
From that study, Raftelis created a rate model that factors each of those variables to calculate what the city's rates should be to accurately reflect expenditures and consumption. The city's finance department updates the model each month with the most current information, and the rates are typically adjusted in August of each year.
The city’s treatment plant was recently recognized by the U.S. Environmental Protection Agency for the third straight year for meeting the state’s performance goals. What were those goals, and how important is it for the city to reach those milestones?
The performance goal met was for turbidity reduction, or increased water clarity in the drinking water, under the Area Wide Optimization Program (AWOP). The North Carolina Public Water Supply Section (PWSS) oversees the state’s public water systems. The PWSS implements the AWOP for the Environmental Protection Agency, which encourages utilities such as ours to optimize plant performance utilizing existing technologies and equipment without large capital investments that increase treatment costs.
We measure the turbidity in the final stages of treatment after the water passes through multi-media filters composed of sand and anthracite. This measurement is done utilizing an instrument called a nephelometer. A nephelometer passes light through a sample, and the amount of light deflected is then measured. The unit of measurement is in NTUs or nephelometic turbidity units. The national primary drinking water standards require a continuous NTU at or below 0.30. The “optimization” goal requires a continuous NTU at or below 0.10 NTUs.
Keeping the turbidity at or below the performance goal greatly increases the quality of the treated water. The lower turbidity contains fewer contaminants, especially microbiological, providing higher quality water for our customers. This recognition of optimization provides our customers with the confidence that their water provider is continuously promoting new ideas and investing in the future to provide safe, reliable drinking water.
What surprises people most when they learn about the operation of the water treatment plant?
The realization of the complexity and multi-departmental cooperation to provide drinking water to our customers always shocks visitors.
The operators of the plant are the “front line” in the treatment process — managing the process, chemical addition and flow of water into the system. The operators also monitor and control three booster pump stations and six elevated storage tanks throughout Lee County. The laboratory staff monitors the water quality, ensuring the process is efficient and maintains the parameters outlined in the Safe Drinking Water Act.
The laboratory is licensed in microbiology and reports weekly and monthly to the N.C. Public Water Supply Section. The laboratory is audited annually and performs quarterly proficiency testing to maintain licensure. Once the water leaves the plant, the water construction and distribution operators maintain the water quality throughout the system by testing, flushing and repairing damaged lines. Engineering provides planning, system rehabilitation, and engineering inspectors monitor construction and provide support to both the water plant and distribution operators system wide.
This inter-departmental cohesion works together to provide drinking water originating from the Cape Fear River into your business or residence.