Scheduled for completion in 2012, the major rehabilitation and expansion project currently underway at the Clear Creek WWTP will provide the city of Redding with a modern wastewater treatment facility able to meet expected demand up to 2025. Treatment capacity at the plant will ultimately be increased to 151,500m³/day – more than doubling the current maximum peak flow – and energy efficiency will be improved.
The work involves repairing, rehabilitating or replacing existing equipment, enhancing biosolids treatment and disposal and augmenting and improving odour control measures at the plant. In addition, a number of new facilities are to be constructed, including a new dissolved air flotation thickener (DAFT), ultra-violet building, outfall pipeline, blower building, administration block and laboratory.
The estimated cost of the first phase, which will be completed in October 2007 is $3.5m; the total cost of the entire project is anticipated to be around $71m.
BACKGROUND
"Treatment capacity at the plant will ultimately be increased to 151,500m³/day ‐ more than doubling the current maximum peak flow ‐ and energy efficiency will be improved."
The original plant was constructed in 1966 and underwent upgrading and expansion in 1977, to accommodate a dry weather flow of 33,000m³/day from May to October and a peak 62,000m³/day wet weather flow during November to April.
The existing plant design is largely conventional. Influent passes through bar screens before entering the primary clarifiers, subsequently undergoing secondary treatment in a series of aeration basins.
Filtration of the clarified effluent uses sand and crushed coal media, with chlorine being added for disinfection, followed by sulphur dioxide to neutralise the remaining chlorine prior to discharge to the Sacramento River. Solids are digested and then dewatered in large drying beds before being transported off-site for disposal.
Having served the city since 1979 in its present form, the ageing works has now reached its design capability, leading the city to instigate the current project to rehabilitate the plant and extend its treatment capacity to meet the demands of the predicted future wastewater flows. Work began on the project towards the end of October 2006 and will be completed in eight phases, finally scheduled to finish in April 2012.
THE PROJECT
Currently, as part of phase 1, a new 8in water pipeline is being installed, coating applied to the ferric chloride foundation within the chemical facility, electrical equipment installed at the head-works and new piping put in place from the chemical facility.
Also during this phase the two mechanically cleaned influent bar screens will be replaced with new fine screen units, with an associated sluice and new processing equipment installed to wash, dewater and subsequently compact the
screenings.
A new influent wastewater pump will be installed, along with a new biofilter system to control odour, and the existing belt conveyor will be demolished. A new chemical storage and feed facility is to be built, the existing chlorine and sulphur dioxide storage arrangements renovated and a new toxic gas scrubber system installed.
Scheduled to start in June 2007, phase 2 involves the refurbishment of one of the facultative sludge lagoon ponds, the construction of a new access-way and the installation of a tie-in to the city’s potable water supply. This phase is expected to be completed by the end of 2007.
Phase 3 will begin in July 2007 and is scheduled to take two years. The plant’s existing dissolved air flotation thickener (DAFT) will be refurbished and a new DAFT built. The primary clarifiers are to be rehabilitated along with one of the pump stations, the head-works and aeration basin. The existing secondary clarifier will be refurbished, the filters renovated and a new secondary clarifier constructed.
"Work began on the project towards the end of October 2006 and will be completed in eight phases, finally scheduled to finish in April 2012."
Starting in June 2008 and continuing through to February 2009, phase 4 involves the expansion of the plant’s diffuser and the construction of a new outfall and associated building work. Phase 5, which follows on in June, principally involves the conversion work to some of the existing ponds; one is destined to become two wet weather storage ponds, another will be turned into lined facultative sludge lagoons and two more will be converted into drying beds.
The construction of a new ultra violet building forms the entirety of phase 6, which is scheduled to span June 2008 to January 2010, while phase 7 includes rehabilitating the facility’s existing aeration basin and the construction of a new blower building.
This element of the project is scheduled to get underway in July 2009 and be completed by July 2011. The final phase, which is planned to run from October 2010 until April 2012, involves building the new administration building and laboratory, together with rehabilitation of the non potable water system.
KEY PLAYERS
The plant is owned by the city of Redding and operated by its wastewater utility. CH2Hill is acting as the construction manager and engineer, with TICO Construction being the main contractor for the project. Project funding is being provided by city wastewater revenues and low-interest loans from the California Water Resources Control Board’s State Revolving Fund.
Scheduled for completion in October 2009, the upgrade of the Nogales International Wastewater Treatment Plant represents the culmination of years of planning involving a variety of agencies at local, state, federal and international levels.
Located in Santa Cruz County, on Arizona’s international boundary with the Mexican state of Sonora, the plant treats wastewater from both sides of the border. Though this makes it a unique facility, its administration has inevitably been complicated by the legal, political and environmental issues that have arisen as a result of this distinctive status – leading to the current rehabilitation project itself being delayed for a number of years.
The work includes significant upgrades to the secondary treatment to meet regulatory standards for TSS and total nitrogen discharge, together with improvements to disinfection and sludge treatment. In addition, the International Outfall Interceptor (IOI), which transports wastewater from both sides of the border to the plant, will receive much-needed repair.
In December 2005, the City of Nogales, Arizona received a $59.5m grant agreement from the North American Development Bank to meet the project costs. The plant upgrade itself is expected to cost $50m.
BACKGROUND
The Nogales International Wastewater Treatment Plant was first conceived in 1943 to provide a regional approach to the issue of wastewater treatment and disposal. Serving the cities of Nogales, Arizona and Nogales, Sonora, together with the surrounding areas of Santa Cruz County, the original works was designed to meet the needs of 20,000 people. As this population has grown over the years, the plant has been subject to a series of upgrades and enhancements.
Between 1990 and 2000, the population on the Mexican side grew from around 108,000 to more than 206,500. With an eye on the increase which was taking shape, in the mid-1990s, the US Environmental Protection Agency sponsored a bi-national discourse on wastewater management. This led to a variety of options being considered including treating Mexican sewage in Mexico, at the existing international facility or operating treatment works on either side of the border.
As a result, plans emerged for a major renovation of the Nogales facility and in 1995, international agreement was reached. The US Border Environment Cooperation Commission certified the concept and the Environmental Protection Agency authorised a $60m grant for the project.
Unfortunately, forging agreement between the wider stakeholders was to prove more troublesome and considerably more time consuming. A number of issues, including operational costs, responsibility for over-spending and planned
capacity allocation proved difficult to resolve.
"One of the main drivers on the need to upgrade was the continuing environmental and public health hazard posed by the plant’s illegally high discharges into the Santa Cruz River and the Nogales Wash."
One of the main drivers on the need to upgrade was the continuing environmental and public health hazard posed by the plant’s illegally high discharges into the Santa Cruz River and the Nogales Wash. In 2000, the Sierra Club filed a legal action alleging ongoing and continuous violations of the Clean Water Act, which ultimately resulted in a court-ratified agreement that the plant would comply with federal standards by 2004 – a deadline which came and went.
Facing the possibility of losing federal funding, the Arizona Department of Environmental Quality took the driving seat and policy and technical committees were formed to progress the work. Ultimately, with consensus reached over the major sticking points and the technical specifications of the project, everything was in place to enable work to start on the long-awaited programme of rehabilitation.
THE PLANT
Described as a "low tech, low cost plant", the facility treats water to a secondary level, removing floating debris and settled solids to exclude around 75% of the influent organics. Ammonia and hydrocarbons are not specifically removed and the plant has problems meeting its TSS and nitrogen discharge limits.
Currently it provides primary screening and grit removal at the head-works, secondary treatment comprising both complete-mix and partial-mix lagoons with subsequent filtration. The final effluent is disinfected before discharge using chlorine and UV; the sludge is periodically removed. The rehabilitation project calls for the head-works and primary treatment facility to have a new medium screen installed in parallel with the existing coarse one, along with a new washer/compactor conveyor system. Two new aerated grit chambers will also be constructed, each 520m³ in volume and a biofilter odour control system put in place.
The main upgrade to secondary treatment is the intended provision of a new Modified Ludzack-Ettinger (MLE) system, with a target effluent total nitrogen of 10mg/l as a five-month rolling geometric mean and a 90% confident limit of 8mg/l. The two process basins will between them provide a total anoxic volume of 3,800m³ and 24,600m³ in total aerated volume and an internal recycle of up to 3.3 times the design in-flow.
In addition, four 28.5m diameter final clarifiers are also planned, the disinfection facilities are to be upgraded and improvements are to be made to the arrangements for solids including sludge thickening and dewatering.
KEY PLAYERS
The City of Nogales, Arizona and the International Boundary and Water Commission (IBWC) are co-owners and operators of the plant. Project funding is being provided by a grant from the North American Development Bank (NADB), through the Border Environment Infrastructure Fund, financed by the US Environmental Protection Agency (EPA).
The technology evaluation was done by Camp Dresser and McKee. Atkins an Faithful & Gould have been appointed to provide the design review and project
construction management. The working group consisted of the Arizona Department of Environmental Quality, the EPA, the Border Environment Cooperation Commission, the University of Arizona, along with the NADB, the IBWC and the City of Nogales itself.
Darling Pumps manufactures sewage, wastewater, dewatering, ETP, slurry, dredging, aeration, irrigation, water supply, fountains and cascades, high-rise buildings and aqua-culture pumps.
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Submersible heavy-duty slurry pumps handle settled and very-abrasive slurries containing solids of desired size and
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DREDGER PUMPS
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RELIABLE DREDGER PUMP MOTORS
To reduce motor failure, the sealing of our heavy-duty dredger pump motors ensures no seals have direct contact with pumped liquid which may contain abrasive particles.
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HOMOGENEOUS-FLOW IMPELLER VANES
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DREDGER PUMP MATERIAL AGITATOR
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JUMBO DEWATERING PUMPS
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GRP pipes in big demand for irrigation projects.
Amiantit’s GRP manufacturing facility Amitech Spain has been recently awarded contracts amounting to approximately $13 million (€9.82 million).
The orders are for Flowtite GRP (glass reinforced polyester) pipes for a variety of applications ranging from an underwater pipeline in Marseille, France to sewage pipe systems in Spain, and GRP pipes for a power plant cooling system in Mallorca which, because of the good experience and trust built up, decided the owner of the project to order Flowtite GRP pipes for a power plant cooling system in the Canary Islands. However, the largest part of the contract awards consists of six orders for irrigation projects in Spain which amount to approximately $9.3 million (€7 million).
"In the year 2000, when the Amiantit Group began the process of going global, Spain was given high priority in our strategic planning because of its strong economic growth," said Amiantit President and CEO Eng. Fareed Al-Khalawi. "We took into consideration three factors which would create an ongoing demand for Flowtite GRP pipe systems: continuous development of the tourist industry; rapid industrial expansion; and extensive agricultural expansion which, due to Spain’s hot, dry climate, would require new irrigation networks and also replacement of old, outdated irrigation systems."
Eng. Fareed went on to say "Amitech Spain is consistently producing excellent results as is shown by the recent batch of orders, out of which the largest amount is for irrigation projects, proving our initial forecast to be correct and fully justifying our investment in establishing a GRP manufacturing facility in Spain."
Spain is not the only country where Amiantit Flowtite GRP pipes are in demand. There are Amitech factories in Germany and Poland serving other European countries such as France and Lithuania, and going further east there is an Amiantit GRP plant in Kazakhstan. In the Middle East there are GRP manufacturing facilities in Egypt, Algeria and Morocco and, of course, Saudi Arabia which is Amiantit’s core market boosted by orders from its GCC neighbours. Other Amiantit GRP plants are in Turkey, India, South Africa, Argentina and Brazil.
Amiantit holds the exclusive world patents for Flowtite, which is the main technological process for the manufacture of GRP pipes. Apart from its wholly owned manufacturing facilities, Amiantit enters into joint ventures in countries outside Saudi Arabia with partners whose local presence is a vital factor in securing contracts.
GRP pipes are so highly rated by project owners and contractors because they are strong and durable yet lightweight, which makes them easy to transport and install, thus reducing costs. But above all Amiantit Flowtite GRP pipes are corrosion resistant, which makes them environment friendly because there is no leakage of contaminating liquids into the surrounding soil and groundwater.
Amiantit Flowtite GRP pipes are used for water, sewage, industrial, agricultural and marine applications. Flowtite technology is also used to manufacture GRP corrosion resistant single and double wall tanks which are used for underground and above ground storage of liquids such as gasoline, aviation fuel, and petrochemicals.