Little Rock Water Reclamation Authority
Little Rock Water Reclamation Authority has both an Administrative and Maintenance Complex in addition to three water reclamation facilities and our peak flow attenuation facility, all to manage your service and informational needs.
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The Adams Field Water Reclamation Facility has been in operation since 1961 and was Little Rock's first wastewater water reclamation facility. From 1961 until 1972, the facility was equipped with only primary treatment. Secondary treatment facilities were added in 1972 and the facility is now rated as a 36 million gallons per day complete-mix activated sludge facility, serving approximately 70% of the City of Little Rock.
The facility is a two-stage "secondary" water reclamation facility, designed to reduce the pollutant load by approximately 90%. A combination of physical and biological processes are utilized to reduce this pollutant load in wastewater. Wastewater from Little Rock enters the facility via three 60-inch diameter gravity sewer lines at an average depth of 30 feet below ground and requires the pumping or lifting of the sewage in order for the treatment process to take place.
Wastewater is then sampled, flow measured, and is then screened to remove large particles. The flow then passes through three parallel primary clarifiers where solid materials settle to the bottom or float to the top to be skimmed off. Solids and floatables are then sent to a Preliminary building where grit, gravel, and scum are removed. Each circular clarifier is 11 feet deep and 115 feet in diameter. Wastewater is held in these basins for about two hours.
Following primary treatment, the flow enters the activated sludge secondary process. Each of the six rectangular activated sludge aeration tanks are 15 feet deep, 40 feet wide, and 160 feet long. A biological microorganism population, which utilizes the incoming dissolved organic material in the wastewater as food, is maintained in the tanks.
Following the aeration tanks, the wastewater passes through a final clarifier section to capture the biological organisms that settle in the final clarifiers. These biological organisms that settle are returned to the activated sludge aeration tanks. These circular clarifiers are 15 feet deep and 145 feet in diameter. The overflow then passes to the Disinfection Building where four channels of ultraviolet lights are utilized to sterilize the bacteria remaining after treatment.
Treated wastewater, which meets or exceeds all State and Federal requirements, is then piped to the Arkansas River through a six-foot diameter pipeline and discharged seven times cleaner than what occurs there naturally. Solids captured during the treatment process are re-circulated in the aeration tanks to maintain a viable microorganism population, while some solids are wasted from the facility process daily via pumping through a five-mile, 12-inch force main to the Fourche Creek Water Reclamation Facility for further processing.
Arkansas's most innovative wastewater water reclamation facility, Fourche Creek is a secondary treatment plant with step-feed activated sludge process and an installed capacity of 16 million gallons of wastewater per day.
A combination of physical and biological processes is utilized to reduce the pollutant load by approximately 90% at the facility. Wastewater from southwest Little Rock enters the facility via a pressure line from a pump station located in College Station. The biological treatment process is comprised of three sets of aeration basins and three sets of final clarifiers. Its aeration system has three fine bubble ceramic diffuser basins with diffused air supplied by four sets of blowers, each of which has the capability of 6,350 standard cubic feet of air.
The sludge from both Adams Field and Fourche Creek is thickened, digested and stored at the Fourche Creek facility. This digested sludge produces methane gas that is utilized in the engine/generator building to produce electricity, which operates the facility.
The Little Maumelle Water Reclamation Facility is a two stage secondary treatment process which utilizes an extended air sludge configuration. Extended aeration is an aerobic (air enriched environment) process where there is a lengthy detention time afforded to the microorganisms in order to oxidize the incoming wastewater. Extended aeration treatment is very thorough with nearly complete oxidation of the organic material taking place. This is critical at the Little Maumelle facility in order to reduce the amount of solid production given the limitations and requirements of the solid transfer ultimately to the Fourche Creek WWTF for further processing and pathogen reduction.
The Little Maumelle Facility began effluent discharge to the Arkansas River on August 8, 2011. The facility was designed by Camp Dresser and McKee, Inc. (CDM). The service area of the facility is a 51,465 acre area known as the Little Maumelle Service Basin of which approximately 15% is within the current city corporate limits. The facility is rated to treat 4 Million Gallons per Day (MGD) of predominately residential generated wastewater with a peak hydraulic loading capacity of 14 MGD. Sufficient land is available for future expansion with an ultimate build-out capacity of 12 MGD biologically and 28 MGD hydrologically.
The Little Maumelle Water Reclamation Facility incorporates cutting edge treatment processes and state of the art technologies to minimize odor, noise, artificial light, and vehicle traffic impacts to the surrounding community. Aesthetic design factors have been utilized in an effort to blend in with natural scenic beauty of the surrounding property and nearby Pinnacle State Park. The plant is tied and controlled by the Supervisory Control and Data Acquisition (SCADA) system that allows monitoring of the facility from remote locations and other Little Rock Water Reclamation Authority Treatment Facilities.
The Little Maumelle facility is fortunate to have exceptional effluent quality and state-of-art Ultraviolet Radiation disinfection systems. Ultraviolet disinfection of wastewater consists of a purely physical, chemical-free process, where UV radiation attacks the vital DNA of the bacteria directly. The bacteria lose their reproductive capability and are destroyed.
This facility is required by the State of Arkansas to reduce Total Suspended Solids (TSS) and Carbonaceous Biological Demand (CBOD) by 85% and has weekly and monthly effluent concentrations limitations on the TSS, CBOD, and Ammonia Nitrogen (NH3-N). This marvel of technology is another classic example of Little Rock Water Reclamation Authority’s commitment to Little Rock residence future and the environment.
The Clearwater Operations/Maintenance Complex sits on a 36.59-acre tract conveniently located at 5300 South Shackleford Road, with easy access to Interstates 30, 430, and 630. The building was constructed in 1989 to replace the LRWRA's old Central and West End maintenance shops on Arch Street and Asher Avenue.
LRWRA jointly owns the building with Central Arkansas Water (formerly known as Little Rock Municipal Water Works) and the LRWRA portion of construction cost about $2 million. Additionally, the two utilities operate a Fleet Maintenance Department at the Clearwater facility for the maintenance and repair of vehicles and equipment.
About 100 LRWRA employees in the Division of Maintenance work from the Clearwater facility, making it the home base for the majority of LRWRA work force.
LRWRA is required to reduce sanitary sewer overflows in Little Rock because of the settlement agreement between the utility and the Sierra Club. The Peak Flow Attenuation Facility project is designed to handle a storm where five inches of rain would fall within 48 hours, which is also referred to as a ‘peak flow event.’ The purpose of this project is to improve the hydraulic capacity of the collection system during heavy rain and address wet weather sanitary sewer overflows in the western end of the Fourche Bottoms.
At a cost of nearly $33 million, the project consisted of constructing a 50 MGD pump station near Mabelvale Pike, 11,500 linear feet of force main pipe, two diversion structures and a 30 million gallon storage facility (a 10 million gallon and a 20 million gallon concrete structure). The detention basins store water generated by rain fall and then discharge into the collection system when flows return to normal. The Arch Street Pump Station rehabilitation and hydraulic upgrade project was also constructed simultaneously with the Peak Flow Attenuation Facility project. These projects complement each other in that they both enhance the hydraulic conveyance capacity of the sanitary sewer system through the Fourche Creek Bottoms, thereby reducing sanitary sewer overflows during wet weather events.
In an effort to further reduce overflows in the system, the Peak Flow Attenuation Facility was expanded, bringing the total storage capacity to 61 million gallons. This project consisted of adding a 31 million gallon basin adjacent to the existing basins, with the addition of a fourth pump at the Peak Flow Pump Station. The project was $13.7 million and was completed in late 2018.
LRWRA engineers estimate that the Peak Flow Attenuation Facility will only be utilized 10 to 15 times annually.