City of Morgan Hill Sewer System Master Plan 2017

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City of Morgan Hill

Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study

12-0248 AEG CofMorganHill FM Rpt.docx

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TABLE OF CONTENTS

ABBREVIATIONS, TERMS AND DEFINITIONS ...................................................................................iii

EXECUTIVE SUMMARY........................................................................................................................ 1 Scope and Purpose ............................................................................................................................ 1 Site Flow Monitoring and Capacity Results ........................................................................................ 1 Basin Inflow and Infiltration Analysis Results ..................................................................................... 4 Recommendations .............................................................................................................................. 9 INTRODUCTION .................................................................................................................................. 10 Scope and Purpose .......................................................................................................................... 10 Flow Monitoring Sites........................................................................................................................ 10 Flow Monitoring Basins..................................................................................................................... 10 Harding Flow Meter........................................................................................................................... 10 METHODS AND PROCEDURES......................................................................................................... 14 Confined Space Entry ....................................................................................................................... 14 Flow Meter Installation ...................................................................................................................... 15 Flow Calculation................................................................................................................................ 15 RESULTS AND ANALYSIS.................................................................................................................. 16 Rainfall: Rain Gauge Data ................................................................................................................ 16 Rain Gauge Triangulation Distribution.............................................................................................. 17 Rainfall: Storm Event Classification .................................................................................................. 19 Flow Monitoring: Average Dry Weather Flows ................................................................................. 21 Flow Monitoring: Peak Measured Flows and Pipeline Capacity Analysis ........................................ 23 Inflow / Infiltration Analysis: Definitions and Identification ................................................................ 26 Inflow ............................................................................................................................................. 26 Infiltration ....................................................................................................................................... 26 Infiltration Components ................................................................................................................. 27

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nflow / Infiltration: Analysis Methods................................................................................................ 29

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nflow / Infiltration: Results ................................................................................................................ 31 Inflow Results Summary................................................................................................................ 31 Rainfall-Dependent Infiltration Results Summary ......................................................................... 34 Groundwater Infiltration Results Summary ................................................................................... 37 Combined I/I Results Summary .................................................................................................... 40

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nflow / Infiltration: Synthetic Hydrographs ....................................................................................... 43 Design Storm Development .......................................................................................................... 44 Design Storm Response Summary............................................................................................... 45

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COMMENDATIONS ........................................................................................................................ 46

TABLES

Table 1. Capacity Analysis Summary..................................................................................................... 1

Table 2. I/I Analysis Summary................................................................................................................ 4

Table 3. List of Flow Monitoring Sites................................................................................................... 11 Table 4. Flow Monitoring Basin Information ......................................................................................... 11 Table 5. Rainfall Events Used for I/I Analysis ...................................................................................... 16 Table 6. Rain Gauge Distribution by Basin .......................................................................................... 18

Table 7. Classification of Rainfall Events ............................................................................................. 20