Johnston Construction Co.

Owner:

City of Aberdeen, Maryland

General Contractor:

Johnston Construction Company

Scope Of Work

Johnston Construction Company provided engineering, construction, and commissioning services for the $5,918,000 lump sum contract on this major BNR upgrade.

This was a major project for a 6.0 MGD BNR upgrade to the Aberdeen Area Wastewater Treatment Plant. The project included headworks distribution chamber modifications, a primary clarifier by-pass with parshall flume structure, primary clarifier modifications, lift pumping station pumps and piping replacement, existing shallow trickling filters conversion into tall aeration tanks with a fine bubble diffused aeration system, a blower building with sound attenuated blowers, instrumentation, insulated piping, a filter building with inground poured-in-place concrete denitrification filters, submersible lift pumps, ultraviolet disinfection, chemical feed system with instrumentation, sludge digester roof demolition, and yard piping.

Major equipment on the project is as follows: two 82 foot diameter 665,000 gallon stainless steel aeration tanks were field erected with walkways and stairways; the aeration equipment manufactured by Enviroquip Symbio provided process treatment for nitrification and denitrification in the aeration tanks; the aeration supply was provided via five centrifugal blowers manufactured by Roots each with 60 HP motors rated at 950 SCFM; a total of four poured-in-place concrete denitrifying sand filters were constructed; and a Trojan four bank ultraviolet disinfection system rated for a 6.0 MGD flow was constructed.

The project was started in July 2004. Final design, construction, and performance testing was completed in January 2006 to meet the Owner’s schedule and regulatory deadlines.