Aberdeen Advanced Wastewater Treatment Plant Digester Gas Flare Improvements

Key Accomplishments

Johnston Construction Company

• JCC cleaned, dewatered, and removed accumulated sludge, grit, grease, scum, and other materials from Digester Nos. 1 and 2 while maintaining continued operation of the plant’s anaerobic digestion process.
• The work was carefully sequenced so that only one digester was removed from service at a time, allowing the remaining digester to continue supporting wastewater-treatment operations.
• JCC furnished and installed a Varec Biogas waste gas burner system, condensate and sediment traps, electrically actuated drip traps, pressure regulation, flame-protection equipment, instrumentation, and automatic controls.
• The project included new aboveground and underground digester gas piping, stainless-steel swivel joints, pipe supports, condensate drainage, precast flare and drip-trap chambers, concrete foundations, and related site improvements.
• JCC constructed a separate exterior access room for the digester gas condensate equipment and completed the associated architectural, plumbing, heating, ventilation, electrical, lighting, and control work.
• JCC coordinated digester cleaning, nitrogen purging, confined-space entry, temporary ventilation, inspection, repairs, testing, startup, operator training, and final turnover while the wastewater treatment plant remained operational.
• Johnston Construction Company completed the Aberdeen Advanced Wastewater Treatment Plant Digester Gas Flare Improvements project in Aberdeen, Maryland. The project was performed for the City of Aberdeen Department of Public Works and designed by GHD Inc.
• The project consisted of improvements to the existing anaerobic digester gas collection, safety, condensate-management, and flare systems at the Aberdeen Advanced Wastewater Treatment Plant.
• The work included demolition of the existing digester gas piping and gas-safety equipment, removal and disposal of material from the two digesters, cleaning and repair of the existing digesters, installation of new gas piping and safety equipment, construction of new equipment chambers, and installation of a new waste gas burner and control system.
• JCC coordinated the overall construction effort, including mobilization, project scheduling, submittals, temporary facilities, digester shutdowns, demolition, dewatering, sludge removal, confined-space operations, mechanical piping, concrete construction, precast structures, masonry, architectural work, HVAC, plumbing, electrical work, instrumentation, controls, equipment startup, operator training, and project closeout.
• A major part of the project involved cleaning Digester Nos. 1 and 2. The digester contents included liquid, sludge, grit, grease, scum, sediment, and other accumulated materials.
• JCC removed each digester from service in coordination with the City, pumped and dewatered the contents, transported the dewatered material for approved off-site disposal, and cleaned the interior surfaces using high-pressure washing.

B & R Electrical Contractors

• B & R Electrical Contractors completed the electrical work associated with the Aberdeen Advanced Wastewater Treatment Plant Digester Gas Flare Improvements project.
• BRE’s scope included electrical demolition, conduit, wiring, boxes, devices, switchgear, heat tracing, instrumentation connections, underground ductbank work, inspection, testing, startup, and project closeout.
• The work included eight explosion-proof light fixtures, two explosion-proof disconnects, three motor-control-center buckets, Lighting Panel LP-1, a 30 kVA transformer, and multiple explosion-proof control switches.
• BRE installed heat tracing for Digester Nos. 1 and 2 and for the digester gas flare piping located within the vault.
• Electrical work was coordinated with the new waste gas flare, condensate-removal equipment, gas-safety systems, mechanical piping, precast chambers, HVAC systems, and active wastewater-treatment operations.
• BRE completed the electrical demolition and made existing equipment safe for removal before JCC and the other trades proceeded with the mechanical and structural work.
• Under Change Order No. 1, BRE relocated an existing methane gas sensor from the storage room to the new gas piping room and extended the associated conduit, shielded signal cable, and terminations.
• B & R Electrical Contractors completed the electrical portion of the Aberdeen Advanced Wastewater Treatment Plant Digester Gas Flare Improvements project in Aberdeen, Maryland. The project was performed as a subcontract to Johnston Construction Company for the City of Aberdeen and was designed by GHD Inc.
• The overall project included replacement and improvement of the existing anaerobic digester gas piping, condensate-removal, gas-safety, and waste gas flare systems at the Aberdeen Advanced Wastewater Treatment Plant.
• BRE furnished the labor, materials, tools, equipment, and supervision required to complete the electrical and designated instrumentation work shown on the project’s electrical and control drawings.
• The electrical scope included demolition and disconnection of existing electrical equipment associated with the old digester gas system.
• BRE identified, isolated, disconnected, and made the affected equipment safe so that the existing gas piping, safety devices, flare components, and associated systems could be removed by the responsible trades.
• The new electrical installation included conduit, conductors, boxes, devices, supports, terminations, and field connections serving the waste gas flare, digester gas equipment, condensate systems, gas-safety equipment, lighting, heat tracing, and related mechanical systems.
• BRE installed approximately the electrical infrastructure required by the project drawings, including power and control wiring routed between the existing plant electrical systems, new equipment, and designated instrumentation devices.