IV. Record of Storm Events
    A. Introduction
    B. Data
    C. Analysis/Observations
        1. Comparison Between Normal and Actual Monthly Rainfall
        2. Comparison Between Typical and Actual Number of Storm Events
        3. Comparison Between Design and Actual Events
    D. Basement Flooding Problems

19
19
19
20
20
22
25
26

V. CSO Flow Characterization
    A. Introduction
        1. Influent Flow
        2. Effluent Flow
        3. Basin Dewatering Flow
        4. Wet Well Dewatering Flow
    B. Data
    C. Analysis/Observations
        1. General
        2. Minimum Rainfall for Influent/Treated Effluent Flow
        3. Relationship between Rainfall and CSO Volume
        4. Relationship between Rainfall and Peak Influent Flow Rate
        5. River Level at Time of Discharge
        6. Comparison with EPA Policy
        7. Impact of Interceptor/Regulators on CSO Influent Volume
            a. Background
            b. Up to the Design of the Interceptor System
            c. Beyond the Design of the Interceptor System

28
28
28
30
31
31
33
33
35
35
36
41
42
42
46
46
48
49

VI. Pollutant Characterization
    A. Introduction
        1. Sample Location
        2. Frequency of Sample Collection
        3. Modifications to Evaluation Work Plan
            a. Definition of Wet Weather Event
            b. Influent Composite Sample Collection
            c. Effluent Discrete and Composite Sample Collection
        4. Quality Assurance/Quality Control
        5. Laboratory Analytical Analysis
    B. Data
    C. Analysis
        1. Completeness of Sampling
        3. First Flush
        4. Effluent Average Pollutant Concentration
            a. Event Mean Concentration
            b. Pollutant Concentration Temporal Distribution
        5. Effluent Oil and Grease Sample Results
        6. UCBOD/CBOD5 Ratio
    F. Observations

52
52
52
53
54
54
55
56
57
59
59
59
60
62
63
63
63
63
64
64

VII. Pollutant Load Characterization
    A. Introduction
    B. Data
    C. Analysis
        1. Comparison with Primary Sedimentation
        2. Comparison with USEPA CSO Control Policy
        3. Comparison with MDEQ Adequate Treatment Definition
    D. Observations

66
66
66
67
67
67
68
68

VIII. Basin Performance in Meeting Phase II Goals
    A. Introduction
    B. Protection of Public Health
        1. Description of Disinfection System
        2. Data/Analysis
            a. Event Geometric Mean
            b. Monthly Geometric Mean
        3. Observations
        4. Event Explanation
            a. 08-Jan-98 Storm Event
            b. 17/20-Feb-98 Storm Event
            c. 09/10-Mar-98 Storm Event
    B. Elimination of Raw Sewage
        1. Visual Observation of Outfall
        2. Effluent Nets
    C. Conclusions

69
69
69
69
72
72
75
76
77
77
79
81
82
83
83
84

X. Facility Design - Innovative Features
    A. Introduction
    B. Data/Analysis
    C. Observations

86
86
86
86

XI. Basin Operation Experience
    A. Influent Flow Meter
    B. Sodium Hypochlorite Feed System
    C. Facility Design Considerations
    D. Facility Operations
    E. Sampling/Evaluation

87
87
88
89
90
91

Appendices
    A. MDEQ/RPO Draft CSO Retention Basin Evalaution Guidelines
    B. CSO Basin Evalaution Work Plan - Dearborn Heights CSO Retention Basin
    C. MDEQ Comment Letter
    D. MDEQ Goal Chart
    E. Technical Memorandum / Simplified Sampling Guide
    F. MDEQ Communications During Evaluation
    G. Wayne County Rain Gauge Network Data
    H. CSO Basin Evaluation Event Summary Sheets
    I. Sample Calculations for Influent Flow
    J. Sample Calculations for Influent Load
    K. July 1999 CSO Basin Floatables Evaluation Update