New Glenwood wastewater treatment plant on schedule | PostIndependent.com

New Glenwood wastewater treatment plant on schedule

Heather McGregor
Post Independent Editor
Glenwood Springs, CO Colorado
Kelley Cox Post Independent
ALL |

GLENWOOD SPRINGS, Colorado – Work crews toiling on construction of the new Glenwood Springs wastewater treatment plant are dealing with extremely muddy conditions, but the project is ahead of schedule and going well.

Workers have poured more than 5,000 cubic yards of concrete, driven nearly 3,000 feet of vertical pilings and hardened more than 18,000 cubic yards of soil at the site.

Through the winter months, they dealt with cold and nearly constant shade at the site.

“The sun was going down for the day at 10:30 in the morning,” said Buddy Burns, manager of the city’s wastewater treatment system.

Now the snow is melting, soils are thawing and the site is mired in mud and puddles.

Nevertheless, crews are making progress on a series of treatment buildings and massive treatment tanks, and some of the wastewater treatment equipment is now being installed in the buildings.

The wastewater treatment plant is a $33 million city government project spread across a two-mile-long work area, with two general contractors and a construction schedule that will have spanned five years by the time it’s finished next year.

Designed to handle up to 1.9 million gallons of sewage per day, an increase from the existing plant’s capacity of 1.1 million gallons per day, the plant will set Glenwood Springs up for more than enough treatment capacity for years to come.

The new plant will also take the seasonal stink out of downtown, produce very clean treated water and be a more healthy work environment for Burns and his staff of four treatment plant operators.

And once the new plant is up and running later next year, the city will be able to demolish the existing plant, located at the confluence of the Roaring Fork and Colorado rivers, and look to redevelop the property for beneficial civic and commercial uses.

Most of the funding for the new plant is coming from a $31.4 million loan provided by the Colorado Water Resources and Power Development Authority, according to Michael Brod, the authority’s executive director. The state loan comes from a revolving loan fund for community water and wastewater projects, funded by the federal Clean Water Act, with a bargain interest rate of 2.5 percent.

The city will be paying off the bonds in twice-a-year payments of $958,000 over 21 years, from 2011 through 2032.

To cover the bond payments, sewer rates for Glenwood Springs customers have been gradually increasing since 2006. Rates for residential customers have climbed from a minimum of $25.56 in 2007 to a minimum of $47.84 in 2010, and are expected to take another upward jump this spring.

“Rather than a slam at the end of the project, rates are going up over a period of years,” said Robin Millyard, city public works director. “But there’s no way around it, it will be painful for sewer rate payers. We are not going to spend any more money than necessary on this project, but at end of the day there will be a price tag.”

The new wastewater treatment system is actually a series of four projects stretching from the existing plant site at the confluence to the new site at Chatfield Ranch in the far western end of West Glenwood.

It includes a new lift station at the existing plant site, a two-mile stretch of pipelines to carry wastewater to the new plant site, a new, mile-long road extending from the west end of Wulfsohn Road to the plant site, and the new plant itself, a complex of three buildings and four giant open tanks.

Work started in 2008 on the road and installation of some segments of the pipeline. The road is done, but work on the other three parts continues.

Construction of the pipeline impacted traffic flow on West Midland Avenue over the past two years, and interruptions are occurring again this month.

Martinez Western Constructors of Rifle is continuing work on the two parallel 16-inch pipelines that will carry sewage from the present collection site on Seventh Street two miles west to the new plant. The company has cut across East Meadows Drive this week to install a pipe segment, and will cut across the west end of Wulfsohn Road for the same purpose next week.

Two parallel pipes are being laid, even though one will be large enough to handle the flow, said Steve Vanderleest, the assistant city engineer supervising the project for the city government. He noted that if something goes wrong with one pipe, the flow can be diverted to the other pipe while repairs are being made.

Moltz Construction of Salida, which specializes in building municipal water and wastewater treatment plants, is building the plant and the lift station.

The three plant structures are in place at the new site, including the headworks building and the aerobic digesters building. More work is being done on the third building, which will jointly house the final solids handling and the treatment plant’s maintenance and operations shop.

Moltz has also built the huge open tanks where partially treated wastewater will go through an aerobic treatment and settling process. The two oxidation tanks will each hold 1.2 million gallons of wastewater, since it takes several days for wastewater to move through the treatment system.

Building such massive tanks on the unstable soils at the foot of Red Mountain required extensive preparation, said Blaine Wright, project manager for Schmueser Gordon Meyer. SGM is a Glenwood Springs engineering firm that designed the plant in collaboration with Tetra Tech, a global company that designs and builds wastewater facilities.

Wright said the hydro-compactive soil underneath the oxidation tanks was pre-hardened by mixing 18,400 cubic yards of cement with the soil to a depth of 10 feet below the bottom of the tank.

He said the buildings and other structures have been stabilized by driving foundation pilings deep into the soil.

“We’ve got 50 to 60 pilings just below the headworks building,” said Wright, referring to the smallest of the site’s three buildings.

On Monday, April 4, Moltz will start work on the lift station, the last piece of the puzzle. When it’s finished, the lift station will occupy the east half of what is now a free city parking lot along Seventh Street.

The lift station facility will become the collecting point for all of the city’s sewer lines. Pumps in the facility will send the wastewater west through the two miles of pipelines to the new plant.

Although the new treatment plant site is lower in elevation than the lift station, installing a gravity-flow line would have required excavations as much as 30 to 50 feet deep, Vanderleest said. Instead, the lift station pumps will push the sewage up to the high points on the line, which has been laid closer to the surface.

The lift station will have three power sources to ensure that no matter what, the inflow of wastewater can be pumped to the new plant.

“That’s critical, because it wouldn’t take long to overflow and go into the river,” said Burns.

He noted that the same odor control technology to be used at the new plant will also be employed at the lift station.

“If we get any odors at the new lift station or the new plant, we will have failed,” said Burns.

From April 4 to June 1, the west half of the parking lot will remain open while crews start work on the site. After June 1, the entire parking lot will be closed for intensive construction work on the lift station. City officials anticipate re-opening the west side of the parking lot once the lift station is complete, but the east half will be replaced by the lift station facility.

In the meantime, an alternate all-day parking lot with 90 spaces has been created on the west side of School Street, midway between 10th Street and 11th Street, next to the Glenwood Springs Recycling Center.

In addition to parking impacts and changes, truck traffic will increase on Seventh Street and Midland Avenue during the construction period. Motorists are encouraged to exercise patience and use caution when traveling through this area.


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