::Cosmopolitan Engineering Group::

Shelton Area Regional Sewer Facilities Plan

Cosmopolitan Engineering Group was responsible for preparing the Regional Sewer Facilities Plan to expand the City system to serve the Port of Shelton, Washington Corrections Center, Washington State Patrol Academy, and the currently unsewered portions of the City of Shelton UGA. The plan included analysis of the existing conveyance system, existing WWTP, plus existing outfall and shellfish closure zone in Oakland Bay. Based on these analyses, a satellite treatment plant was recommended for treating the wastewater generated from the expansion area.

Additionally, this satellite plant will be designed to produce Class A Reclaimed Water for reuse by the various Regional Plan participants, in addition to groundwater recharge. Cosmopolitan is currently working with the Regional Participants and Ecology to establish final requirements for Plan submittal and approval.

Shelton Wastewater Treatment Plant Modifications

Cosmopolitan Engineering Group was retained by the City of Shelton to design major modifications to the city's existing wastewater treatment plant. An amendment to the existing Facilities Plan for the plant was prepared to evaluate and modify previous recommendations to selection options that are more cost-effective and provide greater capacity.

Cosmopolitan designed a UV disinfection system to replace the existing gaseous chlorination system that presents a safety hazard to the surrounding community and treatment plant staff. The UV system is flow-paced to conserve power. Additional project elements involved designing an expansion and upgrade to the aerobic digester system at the plant to provide 20 years of solids handling capacity and reduce the number of loads of biosolids hauled for disposal by installing a gravity thickener. New sludge pumping, piping, and controls were designed to automate sludge wasting and transfer operations that previously required at least two hours of operator time each day. Electrical improvements included the installation of a larger emergency generator to provide power for the UV system. New secondary clarifier mechanisms were also installed.

Project elements:
	Evaluation of disinfection and sludge handling alternatives
	Amendment to existing Facilities Plan and project cost estimates
	Design of UV disinfection system; aerobic digester expansion; sludge pumping, piping, and controls; and secondary clarifier rehabilitation