Basin Water, Inc

Treating Water High in Nitrate to Supplement Supply

By Steve Ruppenthal

Located 15 miles west of downtown Phoenix, Arizona, the city of Avondale is one of the fastest growing residential areas in Maricopa County.

Between 1990 and 2000, Avondale's population grew over 120%. Maricopa County is the nation's fourth largest county in terms of population size, and the fourteenth largest in the continental United States in land area, covering more than 9,220 sq mi (23,880 km²). With more than 50,000 current residents, Avondale is expected to reach a population of 100,000 by 2020.

Avondale supplies more than 2.6 bil gal (9.8 GL) of water to its customers each year. This water is primarily groundwater pumped from the West Valley sub-basin aquifer. Avondale has 10 operating wells and 8 storage reservoirs with a capacity of 5.3 mil gal (20 ML).

Increasing Nitrate Levels in Groundwater

Like many other cities in the West Valley , Avondale has a long history of agriculture and farming. Agriculture is and will continue to be an important part of the city's economic and cultural makeup.

However, one of the side-effects of the regional agricultural industry is nitrate contamination of groundwater as a result of long-term fertilizer use. Consequently, as Avondale's groundwater pumping has increased because of the growing population, the city has experienced a steady rise in nitrate levels. The nitrate contamination appears to be extensive and uniformly distributed throughout the area's groundwater aquifer and is expected to be a problem for the foreseeable future.

During the summer of 2003, increasing demand for groundwater caused Avondale to actively pursue methods of nitrate removal at Well 8, which is located next to a new commercial development. Well 8 had a nitrate level of 13 mg/l as nitrogen, which exceeds the federal standard of 10 mg/l. In addition, it also had a sulfate level of 77 mg/l which generally makes conventional nitrate removal very expensive.

High-Efficiency System Offers Best Nitrate Removal

After examining various treatment alternatives such as reverse osmosis and conventional ion exchange, Avondale decided to contract with Basin Water, Inc. to install a 1,000 gpm (63 L/s) high-efficiency ion exchange system. Basin Water's packaged ion exchange system is specifically designed and engineered for wellhead treatment. Unlike conventional ion exchange systems, which are large and produce a high volume of waste, Basin Water's proprietary system has a very low waste rate and a small footprint that makes it ideal for installation at the wellhead. An added benefit of using this ion exchange system to remove nitrate is that it also simultaneously remove arsenic and uranium. This is an important consideration in areas that may have multiple contaminants in groundwater.

Avondale selected the Basin Water treatment system because it offered the following key benefits:

Small footprint - allows for treatment at the well head;
Low treatment costs – long-term program and low waste rates made this system the most economical treatment solution for nitrate removal;
High efficiency - low waste rates conserve drinking water and reduce operating costs;
Rapid Deployment - system allows for rapid installation, permitting, and operation;
Automatic operation - treatment process requires minimal training and operator supervision from Avondale staff; and
Service - Basin Water has a high level of service and responsiveness.

When evaluating any nitrate removal technology, the most important factor to consider is the amount of waste produced. Waste disposal is typically the single highest cost of operation, often making treatment uneconomic or impractical. In Avondale's case, the waste rate for reverse osmosis was estimated to be in excess of 25%, and the waste rate for conventional ion exchange was estimated to be 5 to 7%. This low waste rate, considered outstanding by the city, also helps conserve drinking water - an important benefit in the desert Southwest.

Deployment of System was Rapid

Avondale contracted with Basin Water for a turnkey 1,000 gpm (63 L/s) treatment unit in June 2003. The unit was installed, permitted and operating by the end of July 2003 – less than 30 days after contract execution. The city's research showed that Basin Water offered the only treatment solution that could achieve operation in such a short time frame.

Installation was managed by both the city employees and Basin Water staff with the assistance of an outside engineering firm. Basin Water provided startup services and worked closely with Maricopa County to ensure that the system was permitted in accordance with all state and federal regulations.

System Provides Reliable Long-Term Solution

During last year's peak summer season, the Basin Water unit operated 24 hours a day, seven days a week, providing roughly 1 mgd (3.8 ML/d) of drinking water. System downtime was minimal and treated nitrate levels were consistently below 8 mg/l as predicted, well below the state standard of 10 mg/L.

The Basin Water treatment system operates unstaffed and requires minimal operator attention. In addition, the operating system monitoring and troubleshooting can be done remotely from any location via telephone line.

Avondale has drilled a new well that will replace well 8. This new well, well 8A, is designed to produce 2,000 gpm (126 L/s) and will be used as a baseload well for the system. Based on Avondale's positive experience with the Basin Water system on well 8, the city has recently concluded negotiations with Basin Water to install a larger ion exchange unit on well 8A. The new ion exchange unit will be used in conjunction with onsite blending to achieve a blended nitrate level of less than 8 mg/l. Basin Water is guaranteeing unit performance and operating costs through a long-term 10-year contract. This unit will be placed in service by June 2004 and will meet or exceed state and federal health department standards for nitrate.

Conclusion

Basin Water has provided Avondale with a reliable and economic solution for nitrate removal. As a result, city staff and elected leaders have been able to commit to a long-term contract with Basin Water to deliver safe, nitrate-compliant drinking water to Avondale residents and customers.

In today's environment where it is becoming ever more difficult to supply safe, secure, reliable, and affordable drinking water, it is important that water managers and other professionals in the industry understand that there are viable options for the treatment of nitrate-contaminated wells. By treating a high nitrate well instead of allowing it to remain out of service, a water purveyor can create a new source of water from what would otherwise be a “stranded” asset. In the future, these “new” sources of water could be our most valuable assets. The city of Avondale is now well-positioned to keep pace with its growing population and thriving business community.

- Steve Ruppenthal is the Water/Wastewater Superintendent at the City of Avondale Utilities Department Water Division , 1211 S. Fourth Street , Avondale , AZ 85323 . He can be reached at (623) 478 – 3370.


News
> News Home Treating Water High in Nitrate to Supplement Supply Click to view PDF Reprinted from Journal AWWA, Vol 96, No.5 (May 2004), by permission. Copyright ©2004, American Water Works Association By Steve Ruppenthal Located 15 miles west of downtown Phoenix, Arizona, the city of Avondale is one of the fastest growing residential areas in Maricopa County. Between 1990 and 2000, Avondale's population grew over 120%. Maricopa County is the nation's fourth largest county in terms of population size, and the fourteenth largest in the continental United States in land area, covering more than 9,220 sq mi (23,880 km²). With more than 50,000 current residents, Avondale is expected to reach a population of 100,000 by 2020. Avondale supplies more than 2.6 bil gal (9.8 GL) of water to its customers each year. This water is primarily groundwater pumped from the West Valley sub-basin aquifer. Avondale has 10 operating wells and 8 storage reservoirs with a capacity of 5.3 mil gal (20 ML). Increasing Nitrate Levels in Groundwater Like many other cities in the West Valley , Avondale has a long history of agriculture and farming. Agriculture is and will continue to be an important part of the city's economic and cultural makeup. However, one of the side-effects of the regional agricultural industry is nitrate contamination of groundwater as a result of long-term fertilizer use. Consequently, as Avondale's groundwater pumping has increased because of the growing population, the city has experienced a steady rise in nitrate levels. The nitrate contamination appears to be extensive and uniformly distributed throughout the area's groundwater aquifer and is expected to be a problem for the foreseeable future. During the summer of 2003, increasing demand for groundwater caused Avondale to actively pursue methods of nitrate removal at Well 8, which is located next to a new commercial development. Well 8 had a nitrate level of 13 mg/l as nitrogen, which exceeds the federal standard of 10 mg/l. In addition, it also had a sulfate level of 77 mg/l which generally makes conventional nitrate removal very expensive. High-Efficiency System Offers Best Nitrate Removal After examining various treatment alternatives such as reverse osmosis and conventional ion exchange, Avondale decided to contract with Basin Water, Inc. to install a 1,000 gpm (63 L/s) high-efficiency ion exchange system. Basin Water's packaged ion exchange system is specifically designed and engineered for wellhead treatment. Unlike conventional ion exchange systems, which are large and produce a high volume of waste, Basin Water's proprietary system has a very low waste rate and a small footprint that makes it ideal for installation at the wellhead. An added benefit of using this ion exchange system to remove nitrate is that it also simultaneously remove arsenic and uranium. This is an important consideration in areas that may have multiple contaminants in groundwater. Avondale selected the Basin Water treatment system because it offered the following key benefits: Small footprint - allows for treatment at the well head; Low treatment costs – long-term program and low waste rates made this system the most economical treatment solution for nitrate removal; High efficiency - low waste rates conserve drinking water and reduce operating costs; Rapid Deployment - system allows for rapid installation, permitting, and operation; Automatic operation - treatment process requires minimal training and operator supervision from Avondale staff; and Service - Basin Water has a high level of service and responsiveness. When evaluating any nitrate removal technology, the most important factor to consider is the amount of waste produced. Waste disposal is typically the single highest cost of operation, often making treatment uneconomic or impractical. In Avondale's case, the waste rate for reverse osmosis was estimated to be in excess of 25%, and the waste rate for conventional ion exchange was estimated to be 5 to 7%. This low waste rate, considered outstanding by the city, also helps conserve drinking water - an important benefit in the desert Southwest. Deployment of System was Rapid Avondale contracted with Basin Water for a turnkey 1,000 gpm (63 L/s) treatment unit in June 2003. The unit was installed, permitted and operating by the end of July 2003 – less than 30 days after contract execution. The city's research showed that Basin Water offered the only treatment solution that could achieve operation in such a short time frame. Installation was managed by both the city employees and Basin Water staff with the assistance of an outside engineering firm. Basin Water provided startup services and worked closely with Maricopa County to ensure that the system was permitted in accordance with all state and federal regulations. System Provides Reliable Long-Term Solution During last year's peak summer season, the Basin Water unit operated 24 hours a day, seven days a week, providing roughly 1 mgd (3.8 ML/d) of drinking water. System downtime was minimal and treated nitrate levels were consistently below 8 mg/l as predicted, well below the state standard of 10 mg/L. The Basin Water treatment system operates unstaffed and requires minimal operator attention. In addition, the operating system monitoring and troubleshooting can be done remotely from any location via telephone line. Avondale has drilled a new well that will replace well 8. This new well, well 8A, is designed to produce 2,000 gpm (126 L/s) and will be used as a baseload well for the system. Based on Avondale's positive experience with the Basin Water system on well 8, the city has recently concluded negotiations with Basin Water to install a larger ion exchange unit on well 8A. The new ion exchange unit will be used in conjunction with onsite blending to achieve a blended nitrate level of less than 8 mg/l. Basin Water is guaranteeing unit performance and operating costs through a long-term 10-year contract. This unit will be placed in service by June 2004 and will meet or exceed state and federal health department standards for nitrate. Conclusion Basin Water has provided Avondale with a reliable and economic solution for nitrate removal. As a result, city staff and elected leaders have been able to commit to a long-term contract with Basin Water to deliver safe, nitrate-compliant drinking water to Avondale residents and customers. In today's environment where it is becoming ever more difficult to supply safe, secure, reliable, and affordable drinking water, it is important that water managers and other professionals in the industry understand that there are viable options for the treatment of nitrate-contaminated wells. By treating a high nitrate well instead of allowing it to remain out of service, a water purveyor can create a new source of water from what would otherwise be a “stranded” asset. In the future, these “new” sources of water could be our most valuable assets. The city of Avondale is now well-positioned to keep pace with its growing population and thriving business community. - Steve Ruppenthal is the Water/Wastewater Superintendent at the City of Avondale Utilities Department Water Division , 1211 S. Fourth Street , Avondale , AZ 85323 . He can be reached at (623) 478 – 3370.
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