2011 Excellence in Environmental Engineering and Science™ Competition Winner

E3S Grand Prize

2011 Grand Prize - Environmental Sustainability

Clayton County Water Authority Sustainable Water Supply Project

Entrant: CH2M Hill
Engineer in Charge: Wayne D. Murphy, P.E.
Location: Morrow, Georgia
Media Contact: Jodie Willson, 720-286-0923

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This diagram shows how the man-made wetlands and existing reservoirs treat and supply CCWA's water system.

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The Panhandle Road Constructed Wetlands demonstrated that natural treatment could be a viable option for recycling Clayton County's treated wastewater.

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The much larger E.L. Huie Jr. Constructed Wetlands were developed in several phases and farther north of the Panhandle Road Wetlands. This photo shows the Huie wetlands during construction in October 2007.

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The final phase of the Huie Constructed Wetlands was completed in September 2010, providing a total of 17.4 million gallons per day of water recycling.

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Plantings at earlier phases of the Huie Constructed Wetlands project.

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Closeup of plantings at earlier phases of the Huie Constructed Wetlands project.


Entrant Profile

Headquartered near Denver, Colorado, employee-owned CH2M HILL is a global leader in full- service consulting, design, design-build, operations, and program management for public and private clients. With $6.3 billion in revenue and 23,000 employees worldwide, CH2M HILL delivers innovative, practical, and sustainable solutions that help clients develop infrastructure and facilities that improve efficiency, safety, and quality of life. The firm has long been recognized as a most-admired company and leading employer. CH2M HILL is an industry- leading program management, construction management, and design firm as ranked by Engineering News-Record (2010).

CH2M HILL has worked for the Clayton County Water Authority (CCWA) as their Engineer of Record since 1998 and assisted CCWA in identifying the use of constructed wetlands as the most reliable and sustainable option for both water treatment and water supply augmentation. Constructed wetlands are proven to require much less land, energy, and maintenance than a land application system (LAS), while continuing a CCWA tradition of using natural systems for water reclamation. Throughout the conversion process from LAS into constructed wetlands, CH2M HILL provided engineering services during design and construction of all phases. The design component included the demolition and removal of existing LAS piping, layout and grading of wetland cells and associated structures and piping to allow for gravity flow, and layout of mains to convey the treated effluent into the constructed wetlands. The services during construction included a full-time onsite inspector to guide construction, review submittals, act as a liaison between the contractor and CCWA, and monitor progress.

Project Description

Quality Project Leads To Proven Performance

Very few indirect potable reuse treatment systems are found in the United States, and most involve injection of treated wastewater into groundwater aquifers following intensive biological and chemical treatment. Clayton County Water Authority (CCWA), in response to the need for increased wastewater treatment capacity and despite having limited available surface or groundwater supplies, partnered with CH2M HILL in developing a truly sustainable water supply through the use of constructed wetlands for recycling treated wastewater and recharging surface waters.

With the completion of the largest phase of constructed wetlands in the fall of 2010, CCWA is recycling as much as 65 percent of daily water use into the existing reservoir. This system augments CCWA's water supply and reduces the need to withdraw water from the small streams that flow out of the county. During Georgia's second worst drought on record, this system sustained raw water reserves at 77 percent of capacity or greater. CCWA also has documented reductions in micro-constituents such as pharmaceuticals, hormones, and pesticides because of this wetlands treatment.

Complexity Of The Problem Needing To Be Addressed

CCWA was created in 1955 to provide water, sewer, and stormwater services to the more than 280,000 residents of Clayton County, situated just south of Atlanta, Georgia. In the 1970s, as CCWA looked for ways to increase water supplies for a rapidly growing population and to minimize the impact of treated wastewater discharges on small local streams, CCWA management selected land application as the preferred wastewater treatment and disposal method.

CCWA purchased more than 4,000 acres of land in the headwaters of one of its water supply reservoirs and converted approximately 2,500 acres into spray fields, giving CCWA 20 million gallons per day (mgd) of wastewater treatment and disposal capacity. Much of this water made its way through underground recharge back into CCWA's downstream water supply reservoir, beginning the process of essentially "drought-proofing" their water supplies.

CCWA operated two land application systems for almost 30 years as the County matured into a densely developed urbanized area. As part of the development of the CCWA 2000 Master Plan, and in response to the need for additional wastewater treatment capacity, CCWA evaluated numerous wastewater treatment alternatives. However, additional large tracts of land for irrigation system expansion were limited. Working with CH2M HILL, CCWA identified the use of constructed wetlands as the most reliable, sustainable option for both treatment and water supply augmentation.

Integrated Approach To A Reliable Solution

Starting on a small scale, CH2M HILL helped CCWA design and construct its first wetland reuse system in the less populated southern end of the county. An existing land application system (LAS), known as the Shoal Creek LAS, was converted into a series of constructed wetlands (Panhandle Road Constructed Wetlands) and the existing treatment plant was replaced with an advanced, biological treatment plant. Effluent from the new plant is pumped to a nearby constructed wetland system. After flowing through the wetlands, where additional treatment occurs, the water is collected and pumped into a nearby water supply reservoir.

Following the successful completion of the Panhandle Road Constructed Wetlands, CCWA began developing a much larger complex of wetlands farther north on a site known as the E.L. Huie Jr. Constructed Wetlands. The wetlands were constructed in phases, taking existing irrigation sites out of service and replacing them with constructed wetlands. The wetland systems discharge directly to nearby CCWA water supply reservoirs. Four phases have been completed and are in operation, providing 17.4 mgd of water recycling. Additional phases are planned to provide another 6.6 mgd of wetlands treatment capacity at the Huie site.

Originality And Innovation In Application Of Knowledge

The wastewater treatment facilities that discharge to the Huie Constructed Wetlands feature primary and secondary treatment that includes nutrient removal followed by disinfection. Effluent from these facilities goes to the wetlands treatment system and then flows to reservoirs. These various treatment systems provide a multiple-barrier approach to water reclamation and enhance the removal of nutrients, microbial contaminants, and micro-constituents- providing a safe and secure supply of water. In addition, the constructed wetlands provide a buffer between the plants and the reservoirs should a treatment plant upset or malfunction occur.

The transition from irrigation to wetlands has resulted in significant energy savings because of the reduced need for pumping. Compared to CCWA's former treatment method (spray irrigation) or more advanced tertiary treatment, the wetlands system is much less expensive to maintain and operate. CCWA has reduced maintenance staff by eight positions along with associated reductions in equipment and materials. Rather than maintaining miles of irrigation pipes and numerous valves and pumps, routine maintenance consists primarily of vegetation management.

Sustainable Solution Provides Economic, Social, And Environmental Advancement

The constructed wetlands have proven to require much less land, energy, and maintenance than the irrigation systems while sustainably using natural systems for water reclamation. Environmental benefits include CCWA's use of the constructed wetlands facilities as an educational tool for customers to explain the importance of protecting water resources. CCWA was recognized by American Rivers as one of America's "Water Smart" communities in 2009 and has received many awards for operations and innovation.

Additionally, wetlands have enhanced bird habitat in the area and attracted species normally only seen in coastal areas. During the 2009 annual bird survey on CCWA properties, a total of 205 species of birds were observed. Of these, 142 were migratory species of songbirds, raptors, woodland birds, waterfowl, and shorebirds. A bald eagle nesting pair at one of the reservoirs produced three eaglets during the 2009 nesting season.

Conclusion

CH2M HILL and CCWA has demonstrated that a sustainable water supply can be developed for a densely developed urban area where wide fluctuations in rainfall can occur on an annual basis. Moreover, this wetlands system is a model of efficiency and environmental sustainability that can serve as an example for other communities around the world that are facing similar water challenges.


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E3S Photos

Plantings during Phase 4 of the Huie Constructed Wetlands project.

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Effluent from a new biological treatment plant is pumped into one of the constructed wetlands. After flowing through the wetlands, where additional treatment occurs, the water is collected and pumped into a nearby water supply reservoir.

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The new constructed wetlands, such as the Panhandle Road wetland here, have enhanced bird habitat in the area.

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CCWA's wetlands system is a model of efficiency and environmental sustainability that can serve as an example for other communities around the world that are facing similar water challenges.

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A Great Blue Heron is at home in one of Clayton County's constructed wetlands that make up the region's sustainable water supply system.


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