In Maryland, the Carroll County Bureau of Utilities needed a 4-mgd expansion added onto their existing 3-mgd water treatment plant in order to adequately serve the county’s 31,000 residents. The bureau also needed to design and construct a new 24-inch water transmission main, as well ancillary equipment, structures and facilities.
These activities needed to be undertaken on an accelerated schedule while continuing to operate the existing water treatment facility, while modifying the existing solids-handling operations. Carroll County officials chose progressive design-build project delivery to meet these objectives.
AECOM was chosen through a competitively-bid procurement process. They were required to provide a fixed price for engineering and a not-to-exceed cost for construction. The design was advanced to 60 percent, on which a guaranteed maximum price was established for the construction portion of the project.
Carroll County asked AECOM to develop an alternative facility layout to reduce construction time and save significant capital and operational costs. The alternate design, developed by AECOM during the procurement process, consolidated the facility’s primary components into one streamlined, compact structure. Design and construction cost totaled $27.5 million.
The tight site constraints and accelerated schedule necessitated innovative planning and partnering with the county and its consultant. The AECOM team developed an environmentally-friendly, multi-level compact footprint that housed all treatment features, administrative spaces, chemical areas and clearwell under a single roof.
AECOM’s design also reduced construction time by three months and saved Carroll County approximately $3 million. In addition, the new facility employed a state-of-the-art, highly-automated computer system designed to aid operations staff in the day-to-day management tasks of the new plant, such as chemical addition, dissolved-air flotation and membrane filtration.
The expanded plant will be large enough to meet the drinking water supply needs of the residents of Carroll County, Maryland, for years to come.