Port-Wide Sewer System Management Plan(SSMP) - Port of Oakland

9.2.3 Hydraulic Model Development and Calibration
A wastewater collection system model is a simplified representation of the real sewer
system. Sewer system models can assess the conveyance capacity for a collection system.
Also, sewer system models can perform “what if” scenarios to assess the impacts of
additional flows or modifications to the collection system.
The Port’s hydraulic model combines information on the physical and operational
characteristics of the wastewater system, and performs calculations to solve a series of
mathematical equations to simulate flows in pipes. The hydraulic model was developed
based on available data collected from the Port’s, City of Oakland’s (City’s), and East Bay
Municipal Utility District’s (EBMUD’s) utility maps, design drawings, lift station summaries,
field surveys, and appropriate assumptions.
Model calibration is a crucial component of the hydraulic modeling effort. Calibrating the
model to match data collected during the flow-monitoring program ensures the most
accurate results possible. The calibration process consists of calibrating to both dry and wet
weather conditions. For this project, both dry and wet weather flow monitoring were
conducted. Dry weather flow (DWF) calibration ensures an accurate depiction of base
wastewater flow generated within the study area. The wet weather flow (WWF) calibration
consists of calibrating the hydraulic model to a specific storm event to quantify the peak and
volume of I/I into the sewer system. The amount of I/I is essentially the difference between
the WWF and DWF components.
A detailed summary of the model calibration process, including the results of the model
calibration, is included in Appendix M for reference.
9.2.4 Evaluation
Following the dry and wet weather flow calibration, a capacity analysis of the Port collection
system was performed. The capacity analysis entailed identifying areas in the sewer
system where flow restrictions occur or where pipe capacity is insufficient to convey design
flows. Sewers that lack sufficient capacity to convey design flows could produce backwater
effects in the collection system and potentially cause SSOs. The sewer system was
evaluated based on planning criteria presented in Section 9.2.1 and Appendix M.
For existing conditions, the capacity analysis consisted of applying the 10-year, 24-hour
design storm to the existing average day flow (ADF) to simulate the peak wet weather, or
design, flow condition. This is the maximum hourly flow that is expected to occur in the
collection system. Sewers with flows exceeding the maximum d/D under design flow
conditions were identified and improvement projects to mitigate existing capacity
deficiencies were developed. This process was then repeated for the anticipated flow
conditions at year 2030.
May 2010 9-5
pw://Carollo/Documents/Client/CA/Port of Oakland/8239A00/Deliverables/Ch09 (FinalA)