The Elizabethton WWTP is a 3.5 MGD average/7.5 MGD peak wastewater treatment plant. The project constructed by W. Rogers Company consisted of both on-site and off-site improvements. Off-site improvements included two (2) cast-in-place pump stations with 35 and 60 HP VFD driven pumps, odor control equipment and SCADA controls. Force mains were constructed on each pump station to the wastewater treatment plant site with both force mains crossing an environmentally sensitive portion of the Watauga River. Improvements of the wastewater treatment plant site consisted of constructing a new headworks with a mechanically clean curved barscreen suitable for flows up to 8.0 MGD and a combination aerated grit and grease separator unit with grit classifier. To facilitate process flows, many portions of the headworks facility were built on support piers from 8 to 18 feet above grade. Two oxidation ditches measuring approximately 230' x 63' x 19'-6" side wall depth were constructed and one was equipped with two (2) 50 HP rotor aerators. Each oxidation ditch was provided with two 9 HP submersible mixers immediately upstream of the rotor aerators. Motor operated influent and effluent weir gates were installed on both ditches to facilitate automatic operation during high flow periods. Two (2) 100' diameter by 15' sidewall depth circular clarifiers were installed downstream with the oxidation ditch. Other structures included in the project were a new RAF/WAS pump station, a plant drain pump station, a new operations building, and numerous manholes, valve vaults and splitter boxes.
Site improvements included new asphalt paving; a 120' by 200' asphalt compost pad to support existing plant operations; site drainge, grading and seeding. Renovations to the existing plant included modifications to the existing chlorine contact chamber and relocation of the plant compost operations. Plant control provided under the contract included a supervisory control and data acquisition system (SCADA) and remote radio telemetry for the offsite pump stations.
W. Rogers Company (WRC) self-performed 75% of the work on the project. WRC drilled, shot, excavated and disposed of approximately 7,000 CY of rock; excavated, placed, redistributed or otherwise disposed of approximately 125,000 CY of earth; installed and tested 10,000' of exterior ductile iron pipe with fittings in sizes 4" to 36"; installed and tested 13,600' of 14" and 16" forcemain from the remote influent pump stations to the plant site. WRC also installed and tested more than 2,000' of small diameter PVC water piping and placed and cured more than 7,500 CY of structural concrete. This required the construction, placement and removal of more than 150,000 SF of forming surface and finishing of approximately the same quantity.