The City of Sedalia, Missouri, is a community of approximately 20,000 people, and it operates a collection system and three wastewater treatment plants (WWTP). In 2009, Under violation of the Missouri Clean Water Law, the city was served with an administrative order by the Missouri Department of Natural Resources (MDNR) to correct major inflow/infiltration problems with its sewer collection system. Citations included inadequate facilities to address wet weather flows throughout the city’s system, which resulted in overflows and backups in the collection system and bypasses at the city’s three WWTPs. At the same time, the MDNR added disinfection requirements to two of the three treatment plants.
Olsson completed an Inflow and Infiltration Reduction Plan that indicated the immediate need for $26 million in collection system improvements. The disinfection requirements also added $4 million for a total of $30 million in wastewater system improvements. Olsson also completed a sewer rate study to identify the user charges required to cover the cost of these improvements, and proposed a fair and equitable rate structure that would be acceptable to the conservative population of the community.
In order to take advantage of some “Buy America Bonding,” the rate study was completed in 90 days, and the rate design was generally accepted by the community. The rates were implemented in December of 2011 and the bonds were sold before the end of the year.
Olsson is providing numerous pre-design, bidding, and construction phase services for this project, which will be complete the spring of 2016. Construction will require a combination of conventional and “trenchless” rehabilitation and replacement techniques to address surface and underground conditions and increase value for construction dollars.
In addition to the many innovative services Olsson provided for this multi-million dollar project, this project also accomplished major objectives of providing an acceptable rate to the community and developing adequate revenue to make the improvements to the wastewater treatment system.