CPAC Meeting 12-15-03

Water Quality Update Presented to CPAC January 12, 2003

Objectives of Presentation
How tasks fit together to support the Long Term Control Plan
What has been accomplished

Tools to Understand CSO Impacts
Flow Characterization
System Characterization and Flow Metering
Hydraulic Sewer Model
Water Quality Study
Water Quality Model
Long Term Control Plan

Consent Decree Requirements
All study efforts required by consent decree
CD included specific items each study must include
Study work plans were approved April 7, 2003
Reports for Flow Characterization and Water Quality Study are due in April 2004.
Long Term Control Plan Report due October 2005.

System Characterization

Flow Metering

Hydraulic Sewer Modeling

Water Quality Study

Water Quality Model

Long Term Control Plan

How Monitoring/ Models Are Used in Long Term Control Planning
Monitoring
Shows current conditions
Helps identify unusual operating conditions
Provide data to make sure models make sense
Models
Fill in the gaps where we can’t monitor
Predicts what will happen with different rainfall conditions
Allows evaluation of changes to the system

2003 Flow Metering Locations

2003 Flow Metering Program
Meter Installation
Meters Installed May through August
Site Visits – Site Check/Data Download weekly

Metering Locations – data set

Data Set
1999 City-wide Flow Monitoring Study – 48 meters
SCADA data – 47 data collection locations
2003 Data – 36 metering locations
Point Place - __ metering locations
Overall – 130+ metering locations with consistent data analysis techniques

2003 Metering Period Rain Events
Several Rain Events Greater than One Inch
88% 1.07 May 31, 2003 91% 3.57 September 1, 2003 73% 2.66 August 3, 2003 97% 1.58 July 7, 2003 97% 1.36 June 11, 2003 42% 2.01 May 9, 2003 Percentage of Meters Recording Data Amount of Rain (inches) Date of Wet Weather Event

Sanitary Area Flow Contributions
Percent Capture – 1999 and 2003

Peaking Factor – 1999 and 2003

Separated portions of the sewer system will contribute significant flow in wet weather.
There are a number of very wet areas of the system where flow reduction work is encouraged
The sanitary flow rates during wet weather are important to consider in evaluating CSO control alternatives and the overall impact on the plant

Combined Area Flow Contributions
Combined Area Flow (Hydrologic) Response
This is a critical parameter for modeling.
Values fall within typical ranges
73% of Combined Area Monitored

Estimated Capture Rates 2003

Combined Flow Summary
Data collected to calibrate model
Ability of flow to be delivered to the interceptor varies significantly by regulator
Variability in frequency of discharge
Overloading of interceptor system

Windermere Pump Station 9/1/03 Response

System Hydraulics - observations
The system backs up during wet weather events
The majority of the back up seems to start at the WWTP
Because of the backups, flow reverses direction in the sewers. More overflow to the waterways also occurs.

System Hydraulics - consequences
Once the WWTP can process more flow
System backup should be reduced
Less CSO discharge to the waterways
Less risk of basement backup

Water Quality Study
Instream (CSO Area)
Dry weather sampling (2 events)
Wet weather sampling (2 events)
Upstream Boundary (Watershed)
Dry/wet, 17 weekly sampling events
Intensive DO
Monitoring
Two 2-week periods

2003 Sampling Locations

Wet Weather Event Monitoring
May 1, 2003:
Fast-moving spring storm (shown)
0.6” at Toledo Express
CSO duration ~ 2 hours
September 1, 2003
Slower-moving late summer storm
2.6” at Toledo Express
CSO duration ~ 14 hours

WW Monitoring Results - Bacteria
Ottawa River:
WW1 – low concentrations, dominated by upstream
WW2 – high upstream + significant in-stream contribution
Decreased concentrations downstream due to Maumee Bay mixing
Primary Contact Recreational Standard Primary Contact Recreational Standard

WW Monitoring Results – Dissolved Oxygen
Maumee River
WW1 – Aeration elevates DO
WW2 – CSOs also reduce downstream DO

Consent Decree Requirements – Hydraulic Sewer Model
Workplan, approved April 7, 2003
Develop sewer model to predict:
Flows
Hydraulic grade lines and capacities
CSO frequencies and volumes
Use in conjunction with WQ model to support Long Term Control Plan

Hydraulic Model Coverage

Status of Hydraulic Model
East Side model is operational
Calibrated to 2003 metering data
Calibration is preliminary, pending:
West Side and 10-Mile Creek calibrations - consistency
Runs with complete model - reasonableness
West Side calibration not far behind
10-Mile Creek to be calibrated in December

East Side Hydraulic Submodel

Calibration to 2003 Metering Data
Also important to accurately estimate flows to interceptor (example: Eastside Interceptor)

Consent Decree Requirements – WQ Model
Workplan, approved April 7, 2003
Model shall be capable of:
Accurately modeling WQ in the 3 streams
Under wide range of conditions
Assessing impacts of CSOs on WQ
Assessing changes in CSO impact due to Long Term Control measures under evaluation

Summary
Flow Characterization Study - close to completion
Water Quality Study - on schedule
Hydraulic Model - on schedule about ready to use
Water Quality Model – will build off of hydraulic model
Long Term Control Plan – will use the models as tools to develop alternatives

Next Steps
Long Term Control Plan – begin evaluation of alternatives
Gather input from stakeholders and the general public

CPAC Meeting 12-15-03

by HartTWI on Aug 05, 2010

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CPAC Meeting 12-15-03 — Presentation Transcript