Grit Load Out System for the RM Clayton WRC Atlanta, GA

General Description

The R. M. Clayton WRC is located in northwest Atlanta and provides wastewater treatment for a service area that encompasses the City of Atlanta primarily north of I-20, a small portion of north Fulton County adjacent to Sandy Springs, and most of north DeKalb County. The facility is designed to treat an average daily maximum month flow of 122 million gallons per day (MGD) of wastewater. The R.M. Clayton WRC was originally constructed in 1935.

The plant’s treatment process removes biological and chemical impurities from the wastewater making it suitable for discharge to the Chattahoochee River in three phases: primary treatment, secondary treatment, and tertiary treatment. The primary treatment process begins with the removal of floatable and settleable solids from the main wastewater infeed. The purpose of the plant’s most recent upgrade project was to improve existing screening and grit removal units for additional capacity and better reliability. The grit consists of coarse sand, gravel and other large inert materials. The grit is then pumped to six grit classifiers, which wash the grit to reduce odor and settle it to reduce liquid. KWS provided a slide gate and hopper after each classifier to store and unload removed solids. Finally, the removed solids are hauled to a landfill for disposal.

Design Parameters

1. Product Type: Dewatered Grit
2. Material Density: 120 Lbs. per Cubic Foot
3. Capacity: 30 Cubic Feet per Hopper
4. Duty: 7 Days a Week, 24 Hours per Day

KWS Advantages

The supply of hoppers and slide gates was required on a quick timeline due to a sourcing error. The Rossum Group contacted KWS Environmental to help them solve this problem. KWS, with its highly trained engineers and shop personnel along with its lean manufacturing processes, was up to the challenge. The KWS sales and design team analyzed the project’s requirements and provided an accurate submittal within a week. Materials procurement and manufacturing were expedited to meet the delivery requirements of the project. The KWS engineering team helped the contractor with a smooth install and then traveled to site on short notice to provide successful startup and operator training. KWS’s team was able to solve any problems seamlessly by clearly communicating with the structural, mechanical, controls, electrical, and operations staff at the jobsite.

The rectangular hopper/chute KWS supplied after the classifiers was designed to store accumulated grit during container changeout. The slide gate was designed with a 2-foot by 2-foot opening to eliminate bridging in the chute and ensure full loadout of product. The KWS design was approved and stamped by a registered professional engineer.

Special Features

KWS Environmental designed each of the six electric slide gates to open and close with over 3,000 lbs. of weight on the gate. Each slide gate blade was 3/4-inch thick to reduce deflection under load and supported by stainless steel rollers with graphite-impregnated bronze bushings. The grit hoppers and slide gates were designed and manufactured from 316 stainless steel to provide long-lasting protection against corrosion.

The gates have an isolating sump to direct excess liquid above the blade to a drain so it can be piped away. The gates feature multi-turn electric actuators along with local control panels and disconnect switches to ensure high torque, accurate, and easy operation.