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Skanska Projects to Bring State Into Clean Water Act Compliance

Fri September 29, 2006 - Southeast Edition
David S. Chartock

The wastewater treatment, reclamation combined sewer overflow (CSO) and water reclamation construction market is booming in Georgia and has been since the U.S. Environmental Protection Agency (EPA) sued the Georgia Environmental Protection Division (EPD) in the late 1990s to force compliance with the U.S. Clean Water Act, according to the Georgia Senate Research Department (GSRD).

The result of the lawsuit was a consent decree that laid the groundwork for a series of construction projects designed to improve reliability of Atlanta’s water quality.

With a compliance deadline of July 1, 2014, the wheels were set in motion for CSO facilities, expansion, and upgrading of wastewater treatment and water reclamation facilities. Major cities throughout Georgia followed suit.

A GSRD spokeswoman said funding for these projects is coming from several sources, including federal and state funds and revenue bonds.

The general contractor for many of these projects is Atlantic Skanska Inc. (ASI) of Atlanta because the construction and expansion of wastewater treatment, reclamation and CSO facilities is ASI’s specialty in the Southeast. These projects include the $138-million F. Wayne Hill Water Reclamation Plant; the $66-million Atlanta-Fulton County Water Treatment Plant, Phase 2.5; the $52.5-million South Central Wastewater Treatment Plant; the $47-million West Area Combined Sewer Overflow (CSO) Facility; the $34.2-million Rome Wastewater Pollution Control Plant; and the $22.7-million Northwest Cobb County Water Reclamation Facility Expansion.

F. Wayne Hill Water Reclamation Plant

Construction of the $138-million F. Wayne Hill Water Reclamation Plant in Buford, GA, which began in January 2003, was completed in June 2006. It is a modern facility that includes a reverse osmosis system and triples the plant’s capacity to treat wastewater from 20 million gal. (75.7 million L) per day to 60 million gal. (227 million L) per day.

According to ASI Project Manager Walter Robidoux, “The work can be generally described as modifications to and expansion of the effluent pump station; construction of a new post-ozonation distribution box; demolition of the membrane demonstration building; construction of five new prestressed concrete equalization tanks and an associated odor control building and system.”

The scope of work included construction of new pre-ozone contractors; construction of new post-ozone contractors; construction of a new ozone/effluent electrical building; construction of new granular activated carbon (GAC) absorbers; modifying existing GAC absorbers; construction of a new GAC blower building and a new GAC electrical building; construction of two new chemical solids thickeners; construction of a new solids storage tank; and construction of two new backwash return basins.

In addition, plans called for modifications to the existing backwash return pump station; construction of three new anaerobic digesters; modifications of two existing anaerobic digesters; expansion of the residuals gallery; installation of a new gas control system, including a new compressor building and four new gas storage tanks; construction of a new influent pump station; and installation of all piping associated with the new and modified facilities.

Work also consisted of construction of new electrical duct banks; providing new electrical wiring, switches, equipment, appurtenances, and transformers; providing new instrumentation and controls; installation of new and modifying existing yard piping; providing temporary work to facilitate construction sequencing; and construction of or modifications to other components and systems as necessary.

Robidoux said that ASI was one of three prime contractors on the site. ASI was required to complete its work in conjunction with the work being done by the other two prime contractors and to coordinate its activities with plant personnel so they would not be adversely impacted by the construction.

Robidoux said the project team was faced with numerous challenges, among them was “having picked up the project as Beers Skanska Inc. in January 2003. This transformation was more than a name change. It involved a project team of which 50 percent were employees needed for the project. The solution to this project challenge was to continue to build the project while dealing with the formation of [the] new company and simultaneously establish policies and procedures and educate the staff members about them.”

A windstorm also affected the project. Robidoux recalled that “while in the process of constructing five 20-million gallon storage tanks for effluent water, two were formed out when a wind storm completely destroyed them, requiring us to reorder metal liners and scaffolding.”

The destroyed forms for the tanks did not delay the project because ASI hired additional workers to help meet the project schedule and rebuild the two tank forms obliterated by the wind storm, he noted.

The project was completed on a fast-track schedule. Robidoux said ASI completed the work in 30 months instead of the contractual 48 months, reducing the schedule by 18 months.

To do this, ASI increased manpower on the project, peaking at 300 workers; and by increasing the number of supervisors by 35 percent and by doubling the amount of heavy construction equipment used on the site.

“We also worked overtime to meet our schedule. Overtime amounted to 15 percent of the hours worked and it took place on weekends and nights,” he added.

Within ASI-s 30-month, fast-track schedule, were 36 milestones, each of which had to be met or ASI would incur a $10,000 per day penalty. All of the milestones were met.

Another challenge faced by the project team was working in and around existing underground piping. The solution was to use twice the number of trench boxes planned. A total of 16 20-ft. (6 m) long, 8-ft. (2.4 m) high trench boxes were in use at one time.

Yet another project challenge was the amount of rock that was discovered, much of which was unexpected. This resulted in having to drill out and haul it off site. A crusher was brought in and used to crush the rock into fill and road base.

Atlanta-Fulton County Water Treatment Plant Upgrade

Earthmoving was the primary project challenge for the $66-million Atlanta-Fulton County water treatment improvements project, Phase 2.5, in Alpharetta, GA.

In total, 2.5 million cu. yds. (1.9 million cu m) of dirt was excavated and hauled off to other sites and reused as fill.

According to ASI Project Manager Brad Jackson, it took approximately three years to perform this task, moving the dirt to various sites from 10 to 35 mi. away using more than 100 trucks totaling more than 250,000 truck loads from the project’s 90-acre site.

To haul away the dirt, temporary, 150-ft. (45.7 m) long steel and wood deck bridges were installed “so that the dump trucks would not rear up the road,” he added.

The project’s scope of work includes providing increased water pumping, conveyance and off-stream storage capacity, an increased filter backwash and a finished water storage capacity.

It also includes water treatment plant instrumentation, security, a finished water pumping capacity and building improvements. Improvements to the raw water pump station included additional intake screens and 1,250-hp (932 kW) variable speed water pumps.

A new parallel 54-in. (137 cm) ductile iron raw water main between the raw water pump station and the existing reservoir, a new raw water reservoir with a capacity of approximately 640 million gal. (2.4 billion L) and other improvements are included in the project’s scope of work. Jackson noted that other improvements will consist of construction of an access bridge to the reservoir outlet tower, a motorized operator for sluice gate, construction of a new backwash water tank, and facility improvements that will include two new plate and frame presses, a dewatering building, an administration building, sedimentation basin catwalks and painting.

The entire project is expected to be completed by November 2006.

Jackson said “Weather was also an issue. When it rained, we couldn’t work that day or the day after because the wet dirt could not be hauled or accepted.”

In these situations, the schedule was sequenced so that other work could be performed, he added, noting that at the project’s peak, the work crew totaled 40 people on the plant side and 30 to 40 people at the reservoir site.

Construction of the project’s 190-ft. (57.9 m) pedestrian bridge also was challenging, Jackson said.

The bridge was constructed off site and shipped in by truck in three 20-ton (18 t), 65-ft. (19.8 m) long pieces. Construction of the bridge required the use of a Maxim AC500-2 600-ton (544 t) crane with a 177-ft. luffing jib with a boom. This bridge was set in two picks. The first was set at 177 ft. (53.9 m) at 20 tons (18 t) and the second, consisting of two sections bolted together, at 85 ft. (26 m) at 40 tons (36.3 t).

According to Jackson, the project contract included $4,000 per day in liquidated damages for each day the project exceeds the contract due date. So far, all plant milestones have been achieved and completed before or on the due date. As a result, “ASI’s portion of the contract was completed under budget.”

South Central WWTP

The South Central Waste Water Treatment Plant (WWTP) project in Douglasville, GA, with a price tag of $52.5 million, began in October 2005 and is scheduled for completion Aug. 17, 2008.

According to ASI Project Manager Steve Sisneros, the “South Central WWTP is a greenfield project. We are fortunate in the fact that we do not have the typical coordination issues we would typically have in keeping an existing plant fully operational during construction. This is a fast paced project that has a stringent schedule and we are constantly searching for sequence opportunities that will provide a time benefit.”

Scheduling is important because the owner, the Douglasville-Douglas County Water and Sewer Authority of Douglasville has promised the public that this 6-million gal. (22.7 million L) per day wastewater treatment facility would take 27 months for construction and three additional months for mobilization.

The solution to this challenge is a sequencing plan that uses multiple crews to build multiple structures. “Three buildings are now being built simultaneously and we are ready to ramp up a fourth,” Sisneros said, adding that the project contract specifies eight-hour workdays.

There are multiple crews per structure, totaling 80 on-site workers. This was increased to approximately 110 workers.

When the team encounters inclement weather, the work schedule is re-sequenced to keep the project moving forward.

The influent pump station is a project challenge, according to Sisneros, because it has to be built 1 mi. off site. The solution is using a separate crew to build it, he noted.

In all, the scope of work includes a total of 21 buildings and consists of furnishing all labor, materials, tools, equipment and incidentals and performing all work required to construct, complete in place, and ready the plant for operation.

The new South Central WWTP will include an influent flow box and influent pumping station with associated equipment; an influent force main; plant headworks with fine screens, a grit removal system and odor control, one 6 million gal. (22.7 million L) prestressed concrete equalization tank with bypass and associated equipment; an aeration tank splitter box with two aeration tanks and associated equipment; two secondary clarifiers with associated equipment; a tertiary flash mix and spitter box; four tertiary flocculators, two tertiary clarifiers, and seven tertiary filters with associated equipment; two ultraviolet disinfection channels and associated equipment; one post aeration tank with associated equipment; a solids handling and dewatering system with associated equipment; associated filter backwash return, scum, plant drain, and solids recycling pumping systems; an administration building, and associated site, and architectural, mechanical, electrical, instrumentation and controls, he explained.

Sisneros noted that the contract calls for no early finish incentives. However, he said, it does include a distinctive of $2,000 per day in substantial completion liquidation damages.

Sisneros said he is particularly proud of one of the project’s team accomplishments to date: the mass excavation and infill on the site, It involved 1.2 million cu. yds. (917,466 cu m) of earth and included balancing the site by cutting and filling with the cut material as required. Unsuitable fill material was compacted and stored in a “spoils” area on the site. He added that the cut and fill work was even performed in inclement weather to meet this project milestone on schedule.

West Area CSO

Logistics, safety and the project schedule topped the list of project challenges facing the ASI’s team for the $47.3-million West Area Combined Sewer Overflow Facility in Atlanta.

According to ASI Project Manager John Hellman, the project’s scope of work includes the construction of the following structures:

o A drum screen building, housing two drum screens, corresponding troughs and a conveyor.

o A vortex structure with four individual vortices, with interconnecting channels.

o An overhead channel spanning an existing road that connects the vortex to the sedimentation basin.

o A sedimentation basin with three individual basins with sludge collectors in each.

o Upflow filters consisting of a structure housing 48 individual filters.

o A dechlorination basin.

o A chemical building housing various chemicals and corresponding pumps and piping.

o A blower building to house three 25-hp (18.6 kW) blowers for the upflow filters.

o An operations building with an electric control room.

o A grit electric building to house the electric equipment for the upper portion of the project.

o A detrius separator that contains two separators and conveyors.

The contract includes installation of 13,000 linear ft. (3,962 m) of associated piping, a $3.3-million electrical package, a $2.7-million instrumentation package and more than $2 million worth of architectural work.

According to Hellman, ASI’s contract for this project is part of the city’s plan to bring the combined sewer system into compliance with federal and state water quality laws. The plan has been approved by the U.S. Environmental Protection Agency (EPA) and the Georgia Environmental Protection Division (GEPD).

“CSOs [combined sewer overflow] are known to be one of the primary sources of water pollution in major metropolitan areas. Once constructed, this facility will reduce CSO discharge into waterways, reduce bacteria and provide control over pollutants,” Hellman explained, adding that “combined sewers were built many years ago to carry wastewater and storm water. During dry weather, wastewater flows through combined sewers to water reclamation centers for treatment and eventual discharge into a local water body. When there are heavy rains, storm water flows into the same sewers, creating ’combined flow.’ The combined flow is sent for treatment. To protect water reclamation centers from flooding during heavy rain, regulators redirect the combined flow to a CSO treatment facility. These facilities treat the combined flows through screening and disinfection prior to discharge into a river or stream. However, during larger storms, flow can exceed the capacity of a CSO facility.”

The project began September 2005 and is slated for completion in September 2007.

The contract also called for the installation of 19,386 cu. yds. (14,822 cu m) of concrete, site grading, paving, and landscaping. Because there are three other contractors who also are performing work on this site, close coordination with the city is a necessity.

“When completed, the new CSO plant will have a treatment capacity of 85 million gallons per day,” Hellman said. “The combined sewage stored in the tunnel system will undergo both physical and chemical treatment prior to discharge into receiving waters. The treatment processes will utilize clarification and filtration to remove suspended solids and disinfection with chlorine. Prior to being discharged into the nearby Chattahoochee River, the wastewater will be dechlorinated with sodium hypochlorite and sodium bisulfite. The purpose of the project is to provide additional filtering during an upset or rain event.”

In providing solutions to project challenges, he explained that “the project site is very tight, with virtually no room for parking, laydown and office trailers. Working with the city of Atlanta, we were able to fill in low areas and build up other areas for parking and laydown. The field office had to be placed on the other side of the street. To complicate matters, there are two other general contractors on site, all vying for the limited parking and laydown area.

“A major safety concern has been that one of the other general contractors on site is installing a tunnel, which requires continuous trucks to cycle through our work area. The city of Atlanta, working with the other contractors, has installed speed bumps and has implemented dust suppress methods to help minimize the impact,” Hellman said.

ASI’s schedule required the installation of the influent structure to be constructed early in the project. Construction of this structure would have required excavation of a portion of the tunnel contractor’s stockpiling area, potentially impacting their storage capability. Again, working with the city, “We were able to utilize an oversized trench box, provided by Trench Shoring, and mitigate the amount of overlap and impact on other parts of the project,” he said.

To resolve issues as they came up, the project team participated in weekly project progress meetings. These meetings, he noted, also served as a means by which the project’s progress could be reviewed.

In addition, Hellman said, ASI’s “contract has liquidated damages of $18,000 per day on substantial completion and $10,000 per day on final completion. The project is currently on track for an on-time completion. The average crew size will be 55 people, which includes the office staff and will peak at around 80 people. The project is based on 40 hours a week, overtime is worked on an as needed basis or as weather requires.”

Rome WPCP Plant Improvements

Maintaining an operational facility while expanding a water pollution control plan, dealing with site conditions and dewatering were among the challenges ASI is facing during the $34.2-million Rome Water Pollution Control Plant (WPCP) improvement project in Rome, GA.

According to ASI Project Manager Jason Walker, the project’s scope of work will be construction of a new influent pumping station, with new coarse bar screens; connecting the existing 60-in. (152 cm) sewer interceptor to the new pump station; construction of new preliminary treatment facilities for the removal of screenings and grit; removal of piping constrictions within the plant; providing secondary treatment capacity for all flows; construction and installation of two new, additional secondary clarifiers; modification of two of the existing secondary clarifiers; construction and installation of a new return activated sludge-and-waste-activated sludge RAS/WAS Pump Station; construction of new chemical feed facilities for the removal of phosphorus; construction of a new sludge thickener; expanding the plant’s administration building; installation of a new plant supervisory control and data acquisition (SCADA) system; and associated site, mechanical, electrical, and instrumentation work.

Expansion of the wastewater treatment plant from 24 million gal. per day to 54 million gal. per day while maintaining existing plant operations required the construction of two new clarifiers, said ASI Project Manager Jason Walker.

“To maintain the existing clarifiers and modify two existing ones required the use of bypass piping,” he explained.

Site conditions also were a project challenge. Walker said the site contains shale, rock and soft rock. In fact, there was so much shale it had to be blasted out.

“This was undulating vertical rock, which meant it had to be blasted with the existing piping and structures above it and without disturbing the existing structures and piping. The solution to this challenge was to use close proximity blasting techniques by excavating pieces of the lime and rock in order to create voids so when rock was blasted, it would uplift and allow blasted rock relief into the voids away from the structures and pipes. A subcontractor, Kesco Dynamics of Atlanta, did the drilling and blasting and used an emulsion compound to fill in the drilled holes for blasting.”

Dewatering also posed challenges. “We had to dig deeper than the water level of the Coosa River and had to take into account seasonal variances of the river’s elevation. The solution was to use a well point system of about 20 wells that were supplemented by large diameter sumps dug into rock. Then we installed French drains at the bottom of the excavations to collect seepage,” said Walker.

Site logistics also were troublesome.

“We had to work in and around existing clarifiers and treatment tanks and mazes of interconnecting pipes,” Walker explained, adding that the solution to the challenge of site logistics was a Link-Belt 70-ton (63.5 t), rubber-tired crane, which was used to set the pumps and clarifiers and other equipment into place.

This project began in September 2004 and is due for completion in November 2007.

One of the project’s accomplishments is a U.S. Occupational Safety and Health Administration (OSHA) partnership agreement. This agreement, Walker explained, is between ASI and Georgia Tech Consultative Service (GTCS). It is an agreement that was entered into to protect workers during the construction of the Rome WPCP.

“OSHA safety and health partnerships are part of the U.S. labor secretary’s ongoing efforts to improve the health and safety of workers through cooperative partnerships with trade associations, labor organizations and employers. This partnership sets safety and health as a high priority,” said Andre Richards, director of OSHA’s Atlanta-West office. “It represents a commitment by all the parties to provide workers with a safe and healthy work environment.”

“Partnership goals,” Richards continued, “include reducing and eliminating safety and health hazards; ensuring effective safety and health programs, and providing effective safety and health training in English- and non-English-speaking employees. Since its Strategic Partnership Program began in 1998, OSHA has formed more than 330 partnerships, impacting almost 13,000 employers and more than 573,000 workers across the United States. Employers are responsible for providing a safe and healthful workplace for their employees. OSHA’s role is to ensure the safety and health of America’s workers by setting and enforcing standards; providing training, outreach, and education; establishing partnerships; and encouraging continual improvement in workplace safety and health.”

Walker said that part of the project’s outreach efforts included several plant and ongoing construction tours by ASI and the city of Rome. Tour groups came from local schools and universities, municipalities, and even visitors from as far away as China.

Walker said the project contract called for a disincentive of $5,000 per day for each day the project is not completed on time.

“We are ahead of schedule by three months,” Walker said. “We have achieved this by coordinating the construction schedule with the plant operator and by having an understanding of the plant’s flow cycle. As a result, we were able to coordinate work during low-flow conditions, which occurred at night and during weekends.”

The crew size peaked at 100 craftspeople at the height of construction, he noted.

NW Cobb Reclamation Facility

Despite successful completion of two early milestones, the $22.7-million Northwest Cobb reclamation facility expansion in Kennesaw, GA, has encountered some delays, according to ASI Project Manager Lincoln Smith.

Smith said delays on the project, which began January 2005 and is slated for completion in June 2007, were due to untimely resolution of unforeseen conflicts prior to earthwork on building on the critical path of the project including: fabrication errors in stainless steel piping required on critical path of the project; unclear engineering drawings for required pipe supports to support the stainless steel piping; and demolition and re-erection of concrete masonry walls for building on the critical path of the project.

Smith said the project’s scope of work includes expansion of the existing Proctor Creek Influent Lift Station with two 600-hp (447 kW) pumps; a new force main from the plant to the treatment facility; minor modifications to the head works and equalization basins; one new 70-ft. (21 m) diameter primary clarifier; expansion of the existing primary sludge pump station; a new scum screening facility; retrofit of eight existing aeration basins with fin bubble diffused air; one new 110-ft. (33.5 m) diameter secondary clarifier with return activated sludge pumps; effluent filters modifications including media and controls replacement; ultraviolet disinfection system expansion; influent and effluent flow measurement structures; new effluent pumps, modifications to the existing positive displacement blowers and sludge holding tanks; new chemical feed and storage facilities; modifications to the existing dewatering building, including the addition of a fourth belt filter press and odor control; new blower/electrical building; modifications to the existing control building and original effluent pumping station; expansion of the existing maintenance building; and on-site yard piping and miscellaneous structures.

In addition, rain also has caused delays at times during the project. Crews have worked on critical path activities on the weekends to make up for rain delays, he added.

In addition to the delays, Smith said, the project team faced numerous challenges. These included installation of a 30-in. (76.2 cm) GTE bypass and plant drain system; backfill of excavation from demolished primary clarifiers; and installation of the underground piping.

The solution to the installation of the 30-in. bypass and plant drain system required that each installation be completed using a pumping bypass. For the 30-in. GTE line, ASI implemented dewatering pumps to bypass the GTE piping to the existing primary clarifiers so that GTE piping could be installed. For the plant’s drain installation, ASI also used dewatering pumps to bypass the existing plant drain system so that the new plant drain could be installed.

The solution to the backfill of excavation from the demolished primary clarifiers required that ASI crunch the concrete rubble into smaller pieces so that it could be spread into the backfill of the excavation from the existing primary clarifiers’ demolition, he added.

“We used a crushing/crunching attachment on a compatible trackhoe in order to reduce the concrete rubble from the demolition into a size suitable to use as backfill in an excavation created by the concrete demolition activities,” Smith said.

The challenge of installing 8,900 ft. (2,712 m) of piping underground arose because it must be installed in an existing facility. Smith said this challenge was met through the use of “endorsement forms,” which serve as schematics for the proper location of where the piping has to be installed.

He noted that 2,500 sq. ft. (232 sq m) of the underground piping consisted of force main that extends from the plant to an existing pumping station.

To facilitate the project and resolve issues, the project team met weekly to discuss the project’s progress, resolve field issues, administer the contract and coordinate all work activities.

One of the project’s major accomplishments, he pointed out, is that there have been “no recordable accidents with over 75,000 man-hours worked so far.”

When completed, the Northwest Cobb reclamation facility will have been expanded from an 8 million gal. (30 million L) per day plant to a 12 million gal. (45 million L) per day reclamation facility.

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