LAN worked with the City of Waco and the Waco Metropolitan Area Regional Sewerage System (WMARSS) from the inception of this project to relieve flow from the WMARSS Central Plant, which was approaching its treatment capacity. LAN evaluated various site locations for a new plant and interceptor locations. A decision was made in consultation with WMARSS to locate the plant in Lorena, and divert flows from the cities of Hewitt and Lorena in the upper reaches of the sewer collection system.

LAN provided engineering design services for this green-field, 1.5-mgd wastewater treatment plant. All engineering services were provided in-house, including civil, structural, mechanical, electrical, architectural, and instrumentation design. LAN prepared the permit for this plant, which included phosphorus limits. The plant, to be located on a large tract of land in an upper income rural environment, was protested during the permitting process. LAN worked with the City to address the citizens’ concerns and the permit was granted. Other design components included an influent lift station, headworks structure equipped with an automated fine screen, washer compactor, manual bar screen, grit removal system and grit classifier, secondary clarifiers, RAS pump station, WAS/scum pump station, tertiary cloth media filtration, and UV disinfection. One of the concessions made during permit negotiations to address clients’ concerns was that no solids treatment occurs at the plant. The design called for biosolids generated by the plant to be thickened to approximately six percent through the use of a Rotary Drum Thickener (RDT) and subsequently hauled to the WMARSS Central Wastewater Treatment Plant for digestion and dewatering. LAN selected high-speed turbo blowers and multi-stage DO control to provide energy efficient aeration. Blowers were installed adjacent to the above ground concrete aeration basins, which acted as sound-reducing walls to reduce noise impact. In addition to reducing noise, special attention was placed on minimizing lighting and odors. The plant was designed with a reduced profile and includes a berm to minimize visual impacts.

LAN also designed the plant’s interceptor to convey wastewater generated from the cities of Hewitt and Lorena to the plant. The interceptor includes 11,725 LF of 24-inch and 5,235 LF of 18-inch wastewater lines, with 45, 60-inch manholes and more than 1,000 LF of bore and encasement.