2023 09 19 City Council Packet

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bservations or measurements. Limited adjustments may be made to model inputs 
to better approximate real-world observations. 
 
4.5 – Identification of Issues to be Addressed  
In this task, the validated models will be simulated for the selected wet weather 
events to evaluate system flows contributing to water quality issues. This analysis 
may be staggered for different drainage subsys tems as needed to expedite the 
evaluation of priority areas identified by Owner.  
 
Hydraulic results from design storms will be reviewed at the drainage issue 
locations identified by Owner with field observations to assess potential factors and 
flow characteristics contributing to water quality issues. A broader review of model 
results will then be performed to identify similar factors  that could lead to similar 
issues at other locations.  
 
Engineer will meet with Owner to discuss identified issues and potential 
contributing factors . A key  goal of the discussion will be to select which issues 
should be prioritized for the development of conceptual solutions. Considerations 
include the severit y of the issue , its proximity to nearby issues, and the potential 
impacts on MS4 compliance  and public safety . The discussion will also include 
potential types of solutions to be evaluated . Examples include detention  or green 
infrastructure within upstream urbanized areas to reduce flows to stream channels, 
stream bank stabilization or erosion control improvements, and gray infrastructure 
improvements.  
 
4.6 – Hydraulic Analysis of Stormwater Improvements  
Engineer will utilize the hydraulic models as a tool for evaluating conceptual 
solutions to the issues selected  in the previous task. Upstream solutions such as 
detention or green infrastructure will be evaluated within the closed system model. 
Additional in-stream improvements may be incorporated into the stream system 
model. Alternatives will initially be sized based on a high -level review of site 
constraints (such as maximizing detention within space available) and then 
finetuned in the model to hit defined goals or thresholds such as reduced flows and 
velocities. After accounting for upstream and in-stream improvements, the stream 
 
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