Look below to find out more about our proposed final design!
The team considered 2 - 3 alternatives for each step in the treatment process. The existing infrastructure at the facility was considered as an alternative.
These alternatives were scored in a decision matrix to choose the best possible treatment processes for the facilities needs.
Each decision matrix was assigned criteria that was deemed pertinent to the specific treatment process. Each criteria was given a weight in the decision matrix and a higher weight was assigned to the criteria that was thought to be the most important for each step in the treatment process. Each alternative was scored 1 - 3, 3 being the best and 1 being the worst.
The existing screening at the facility comprises of 2 static screens. These screens have been deemed inadequate and need to be updated in the redesign.
The existing facility does not have a grit chamber but the team decided to implement one to decrease the grit and larger solids in the system to protect the processes downstream.
The existing facility does not have an equalization basin but the team wanted to implement one in the design to stabilize the flow throughout the day. The facility experiences high peak flows in the morning and afternoon so the equalization basin would hold extra flow during those peak hours and release the influent into the processes downstream at a constant rate throughout the day.
The existing facility does not have a primary clarifier but the team wanted to implement one to decrease the suspended solids in the processes downstream.
The team was required to consider three treatment alternatives for secondary treatment: Conventional Activated Sludge, Membrane Bioreactors, and a third alternative of our choice. We decided to consider Moving Bed Bioreactors as our third alternative. The existing facility uses conventional activated sludge.
The existing facility utilizes disc filters as their advanced treatment following the activated sludge process.
The existing facility utilizes a chlorine contact basin as their disinfection.
The existing facility utilizes a centrifuge as their solids management to dewater the sludge produced during the treatment process.
The purpose of this equalization basin is to stabilize the flow throughout the facility to protect the units downstream from high surges of water that occur during peak hours. The equalization basin will have blowers to agitate the water which will prevent solids from settling in the basin while waiting to be discharged throughout the facility. The basin had to be large enough to hold the peak hour flow which was estimated to be 10.64 MGD.
The aeration basin is the first step in the activated sludge process. This is where the microorganisms will be introduced which will focus on decreasing the biochemical oxygen demand in the influent. The aeration basins will have blowers that will provide oxygen to the microorganisms which will allow them to thrive in the basin. The basin has a return activated sludge rate of 85% which means that 85% of the sludge that is produced in the basin will be cycled back through the treatment process so the amount of microorganism in the water is constantly replenished.
The secondary clarifier will follow the aeration basins in the activated sludge process. The purpose of the clarifier is to allow any remaining solids to be settled out before the water goes to the advanced filtration systems downstream. The detention time of this clarifier is much longer than the primary clarifier to allow for as many solids to settle as possible.
The proposed final design recommendations can be seen below. The team created a proposed site layout, hydraulic profile, and flow diagram.
To create the proposed site layout, the existing facility was expanded 150' in the north and east direction.
For the flow diagram, the team denoted where splitter boxes will be installed to evenly split the flow throughout the facility. There will be valves installed at the pipe entrance to each system so the flow can be turned off for maintenance purposes. The flow diagrams shows where all flow and waste will come from and where it will be sent to.
Dirt was excavated in the northwest corner of the facility and moved to the southeast because that is where the beginning of the process will be. The influent pump station is required to pump the water 45' up in elevation to the preliminary treatment. There is a slight decrease in elevation between each treatment process to maximize gravity flow throughout the facility.
An engineers opinion of probable cost was created after the design process was finished. The costs include earthwork costs, capital and instillation costs of the new equipment, pipes and pumps, odor control, and splitter boxes.
Total EOPC: $31,617,180.63
An operation and maintenance cost analysis was completed for the first year of operation. The operation costs included the energy consumption of each system and the labor costs of operating the facility. The maintenance costs included inspecting the equipment, replacement of any necessary parts, oil changes, and anything else that is required by the manufacturers.
Total O & M: $4,731,950.61
Project Impact Analysis
A project impact analysis was completed for this project. Two alternatives were considered: Alternative 1 - Completing the Project
Alternative 2 - Not Completing the project
After comparing the social, environmental, and economic impacts of each alternative, the sustainability index was calculated. The sustainability index (SI) determines which alternative is the one that should be chosen. A higher SI indicates that the alternative has more positive impacts than negative whereas a lower SI indicates that an alternative has more negative impacts than positive impacts.
Alternatvie 1 - Completing the project had a much higher sustainability index (180) than Alternative 2 (110).
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