A large green and blue pipe with a meter on the outside of it.
The large pipe in the Joseph B. Blake Water Treatment Plant in Highlands Ranch where the raw water comes into the plant to be tested and treated. Credit: Haley Lena

In Highlands Ranch, some believe the water tastes different during the summer compared to winter months. However, while that may be true,  Centennial Water and Sanitation District says it’s still safe to drink and use. 

The taste of water depends on where the water comes from. The water district gathers water from reservoirs and wells, which carry different tastes. 

Last year, Centennial Water began construction throughout their facilities to increase capacity and meet regulations as the Joseph B. Blake Water Treatment Plant and the Marcy Gulch Wastewater Treatment Plant were both built in 1984. 

“It’s to get us to not only meeting the demand that we need to, but also give us the infrastructure that we’ll have in place moving forward for the next 40 years,” said Nic Geroge, the district’s water and wastewater superintendent. 

Currently, the treatment plant can treat about 20 million gallons per day. 

Once construction is complete, the plant will eventually be able to provide 36 to 40 million gallons per day with surface water, said George. 

The end goal is to reduce the district’s reliance on groundwater. 

The district will shut down its water treatment plant this winter. Water will continue to be distributed to residents through the district’s holding tanks and groundwater. 

Although the district uses different sources of water, the water goes through the same water treatment process. 

To ensure the quality of the water, operators take labs every four hours, monitoring how much they get out of the treatment process and to assure water going to customers is clean, potable and palatable. 

The Joseph B. Blake Water Treatment Plant

A large body of water surrounded by green grass and houses in the background.
The forebay is where water from the Chatfield, South Platte and McLellan reservoirs get pumped into and mix before going to the pretreatment building. Credit: Haley Lena

The community’s water supply comes from a conjunctive use system. The supply is a combination of groundwater from three aquifers beneath Highlands Ranch and the surface water from the South Platte River. 

Centennial Water has three storage reservoirs, Chatfield, South Platte and McLellan. Each of them grab water off the South Platte River. Combined, the three reservoirs total about 17,000 acre feet. 

An acre foot of water equals about 326,000 gallons of water. 

Using two pump stations, the raw water from the reservoirs gets pumped into the Joseph B. Blake Water Treatment Plant to what is called the forebay. 

The forebay is a large lake onsite that allows the district to blend the water from the different reservoirs as it comes in. 

Each of the reservoirs has their own unique water as they each have different stream characteristics coming in.

“We blend the water together to try and get the optimal mixture,” said George. “It makes the water not only potable but also palatable.” 

Due to the amount of rainfall the community saw this summer, the rainfall helped dilute the algae in the reservoirs which helped prevent algal blooms. 

Flocculation and sedimentation

Water being pushed through the water treatment plant, becoming more clear.
The water becomes more clean as it goes through the flocculation and sedimentation. Chemicals are added to make particles stick together and those large clumps of particles settle down, allowing the clear water to flow over. Credit: Haley Lena

From the forebay, the raw water flows into a newly replaced pipe in the pretreatment building. 

As the water comes in, there is a flow meter that shows how much water Highlands Ranch is demanding. 

The district did not see their normal summer demand this year because of the rain, said George.  Typically, the demand during the summer is anywhere between the high 20s and 30s gallon per day, but because of the rainfall, the demand was in the low to mid-20s. 

Also at this point in the process, a sample is taken of the water and measures how much debris is in the water, the connectivity and the pH level. 

Chemicals are then added to the water. These include carbon based chemicals to remove the taste and odor in the water, an iron salt that neutralizes all the negative qualities, allowing one side to become positive, one negative and then they start to stick. 

A polymer is also added to help build what George calls “snowballs.”

“When things come in, they’re like light snowflakes and they are dispersed throughout the water, they don’t settle,” said Gerorge. “We add chemicals to help neutralize those and get them to stick together.” 

While mixing the chemicals, they are slowly agitating the water so the “snowballs” become bigger. 

Clear water begins to emerge as everything slows down during the sedimentation process and the clumps start to settle out. 

“It settles down at the bottom, makes a blanket at the bottom, we remove that blanket and send it over to the wastewater plant,” said George. 

By the end of the sedimentation stage, 90-95% of unwanted particles are removed from the water, said George. 

Filters and disinfection

Water lowering into one of the outdoor filters.
The outdoor two-stage filters at the Joseph B. Blake Water Treatment Plant. The filters catch bacteria and unwanted particles before going to the disinfection stage of the treatment process. Credit: Haley Lena

The water treatment plant utilizes 14 two-stage filters. One layer is sand and another is coal based carbon. Six are for indoor use during the winter and the remaining are outside for irrigation use. 

George described the filters as a coffee filter. 

“They stack in there and make little pores,” said George. “All the stuff that comes in that we weren’t able to get out in the sedimentation process, it gets caught up in those and everything else gets stuck in between.”

With nearly two million gallons going through the filters each day, the pores in the filter clog up. The plant runs higher amounts of water through the system backwards to push all the debris out. 

When the water comes off the filter, it goes through a naturally flowing waterfall in which chlorine is added, starting the disinfection stage. The water then goes to the distribution holding tank. 

“We hold the water in there for a certain amount of time to allow the chlorine to do its work,” said George. 

Centennial Water uses chlorine as a disinfectant as chlorine burns any of the bacteria that could have made it through the treatment system.

The final stage is the pump station. There, a chemical called chloramine is added as part of the district’s corrosion control. They raise the pH in the system to add an additional layer of protection to the pipes for the distribution process. 

When water is needed, the district will pump it through the distribution system to six distribution tanks across the community.

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