Leveraging Hydraulic Sewer Modeling

and Pipe Condition Data for a Robust and Sustainable GIS

April 7, 2011

NELSON ESQUIVEL AND MAZEN KAWASMI

Agenda

• GIS Perspective on the Wastewater Master Plan Process and Development of Hydraulic Sewer Model

• GIS Perspective on the Risk Base Assessment (RBA) and Condition Data

• Case Study: City of Irving Wastewater Master Plan and RBA Condition Assessment

2

What is a ? “A tracking parameter that is tied to an asset

and does not change over time.”

What is a ? “An application or software package that

performs tasks independently and is not

seamlessly linked to other systems.”

What is ? “Linkage of critical data residing in different sources providing users with enhanced information.”

What is a ? “A collection of activities that defines roles and responsibilities and provide sustainable work flow.”

3

Terminology

Basic Definitions:

A GIS Perspective: Wastewater Master Plan

Process and Development of Hydraulic Sewer Model

5

Why is a Master Plan needed?

Why Do It?

• Experiencing Serious Operational Problems

– To Identify System Deficiencies

• Experiencing Rapid Growth

– Provide Adequate Capacity Expansion

– Make Growth Self-Supporting (Impact Fee Study)

• A Tool for Developing Annual Budgets

– Phased Capital Improvement Plans

Typical Wastewater Master Plan Process

Population & Wastewater Flow

Projections

Field Testing and Calibration

Wastewater Collection Planning

Model Development

Strategic Planning

Wastewater Facilities Planning

6

CAPITAL IMPROVEMENT

PLAN

RBA Asset Management Prioritization

Model Selection

GIS Coordination

Features Infoworks CS

Bentley SewerGems

H2OMap SWMM

Info SWMM Hydra

Dynamic Model Yes Yes Yes No

Backwater Calculations Yes Yes Yes No

Inference Tools Yes Yes Yes No

Data Flagging Yes No Yes No

GIS Editing Yes Yes Yes Yes

Background GIS Layers Yes Yes Yes Yes

Rain Gauge Inputs Yes Yes Yes No

Can Define RDII Yes No Yes Yes

Validation Tools Yes No Yes No

Special Structures Yes Yes Yes Yes

3D View Yes No No No

EPA SWMM5 Import/Export Yes Yes Yes No

• Host Workshop to Demo Real Life Industry Examples

• Leverage Data Silos Available:

– CMMS, GIS, CCTV Data and Condition Scoring Database

• Select Software that Meet City’s Existing and Future Needs

• Work with City Staff to Determine In-House Applications Going Forward

Wastewater Model Selection Process

SOFTWARE EVALUATION CRITERIA

7

Data Sources for Model Development

Contours to determine manhole elevations

and areas with low elevations.

Water Billing Meter data by parcel to determine

usage for wastewater load allocation.

Using Existing GIS

• Identify or Establish a common link between GIS and the Model - Unique Identifier

• Use GIS Topology and Aerial Imagery to check for connectivity issues and to resolve alignment issues.

• Identify sewer selection sets for model development

• Develop large sewer line profile maps of data input for quality control review by both Consultant and City staff

Existing Models

• Compare existing model data with GIS data for selection set facilities.

• Review data flagging and update GIS where model data warrants.

• Review model data for special structures – weirs, convergent and divergent manholes, lift stations, etc. for input into updated model.

As-Builts Drawing Research

• Placing a person in City’s office to research and record critical missing attribute data

• Obtain digital electronic files (i.e. PDF, TIFF, etc) • Utilize design plans to populate missing attribute data for

ongoing projects.

• Collect lift station as-builts and pump performance data for input into model.

Surveying

• Conduct GPS and conventional surveying where necessary to collect accurate manhole location data.

• Conduct measure downs for field verification and use in determining missing invert elevations.

– Option 1

• Minimum of every 3rd manhole for each selection set line, divergent and convergent manholes, major PI’s, weirs, and junction boxes.

– Option 2

• Major junctions, Diameter Changes, Lift Stations, Every 5th manhole

– Option 3

• Minimum of every 3rd manhole for larger interceptors, Major PI’s, and Lift Stations

What the model checks for…

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Nodes in Close Proximity

Pipe Split Candidates

Intersecting Pipes

Disconnected Nodes

Parallel Pipes

Orphan Pipes

N 1 N

2 N

3

N 4

N 1 N

2 (only)

N 3

P 1

P 2

P 1

P 2

P 3

P 1

P 2

P 1

P 2

P 3

P 4

P 1

(over)

P 2

(under) P

1

P 2

What the model will find…

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Below is an example of a sewer profile showing inaccurate attribute data within the GIS.

The sewer profile above represents correctly attributed data that has been verified and updated in the model.

Man

ho

le

Man

ho

le

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Data Sources Inside the Model

• Implementing a Process to track data sources.

– Model development

– Model calibration

– Hydraulic analysis

• Color Scheme in flagging represents data confidence level and is tracked through the modeling process.

Develop Process to Flag Various Data Sources in the Model

Model / GIS Business Process

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Step 1: Obtains Latest GIS Database

Step 2 : Import Changes Into

Model

Step 3: Check for Connectivity

and Other Inconstancies in

the Data

Step 4 : FNI Submits Attribute

Updates and Connectivity / Data Issues to

city’s GIS

Step 5 : GIS Researches

Connectivity / Data Issues

through Multiple Sources

Step 6 : Update GIS Database Changes and

Additional Parameters

Step 7 : Confirm that changes have

been updated in the GIS

Model

Software

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GIS

17

Wastewater Model Initial Benefits

GIS

GIS Benefits of Master Plan

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• Patterns are often more clearly observed when viewing mapped data.

• A Master Plan can help you organize and centralize your data.

• Field Collected GPS Data from the Master Plan Can Enhance Your GIS Database along with your wastewater model.

• Making better business decisions

A GIS Perspective: Risk Base Assessment (RBA)

and Condition Data

• Desire to graphically track sewer condition over time in a similar manner as a pavement management systems provides for roadways

• Desire to identify areas of highest risk and exposure

• Need to maximize value of rehabilitation dollars with increasingly limited resources

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Why is a Risk Base Assessment Plan needed?

Risk Based Assessment Flow Chart

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Low Impact

Medium Impact

High Impact

Very High Impact

Low Medium High Very High

Very Good

Good

Fair

Poor

Very Poor

Very High

High Medium

Low

Pipe Age

Pipe Material

SSOs & Stoppages

Infiltration/Inflow

Pipe Corrosion

Condition Scores

Very High

Impact

High Impact

Medium Impact

Low Impact

Capacity Scores Criticality Scores

Condition Risk

Matrix

Capacity Risk

Rating

Low Impact

Medium Impact

High Impact

Very High

Impact

Very Good

Good Fair Poor Very Poor

Condition Risk

Rating

Capacity Risk

Matrix

High Risk = Short Term CIP

Medium Risk = Long Term CIP

Condition of the Wastewater Assets

What is the Likelihood of an Asset Failing? • Develop a grading system that scores each asset by its

condition.

• Condition parameters to consider:

22

Pipe Diameter (GIS)

Material (GIS)

Age (GIS)

Level of infiltration/inflow

Soil conditions (GIS)

What parameters have data available and are applicable and how should they be weighted?

SSO, sewer stop & work order history (CMMS)

CCTV condition assessment data

Pipeline corrosion

Very Good

Good

Fair

Poor

Very Poor

Condition Scores

Criticality of the Wastewater Assets

• What is the Consequence of a Sewer Line or Lift Station Failing?

• Criticality parameters to consider: – Number of Upstream Wastewater Connections

– Line Size and Line Access Issues

– Proximity to: • Environmentally Sensitive Areas

• Schools / Hospitals

• Major Road Crossings

• High Density Commercial Developments

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Very High

Impact

High Impact

Medium Impact

Low Impact

Criticality Scores

Capacity of the Wastewater Assets

Capacity parameters to consider:

• When does an overflow occur?

-Ground elevation vs. Rim elevation

• Ratio of flow depth to pipe diameter, d/D

-d = depth of water ÷ D = Pipe Diameter

• Ratio of flow to pipe capacity, q/Q

-q = flow in pipe ÷ Q = designed flow

• What level of surcharge is acceptable?

-Define a distance below the rim

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Very High

High Medium

Low

Capacity Scores

Risk Based Prioritization Screening

Risk Rating for each pipeline:

• Condition Risk =

(Condition Assessment Score)

x

(Criticality Assessment Score)

• Capacity Risk =

(Capacity Assessment Score)

x

(Criticality Assessment Score)

• Review Scoring to Identify CIP Candidates

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Low Impact

Medium Impact

High Impact

Very High

Impact

Very Good

Good Fair Poor Very Poor

Low Impact

Medium Impact

High Impact

Very High Impact

Low Medium High Very High

Case Study: Irving Wastewater Master Plan

and Condition Assessment Study

Background on Irving’s Collection System

• 2008 Population – 214,073

• Wholesale Customer of TRA

• Major Interceptors up to 54” in diameter

• 3.8 Million Linear Feet of Sewer Pipe

• 12 Major Basins

• History of Failures on Concrete Pipes

27

GIS Update for Larger WW Infrastructure

Wastewater Model

Development

Wastewater Flow Projections & TRA Coordination

Flow Monitoring

& Model Calibration

RISK BASED PRIORITIZED CAPITAL IMPROVEMENT PLAN

Wastewater System Master Planning Process: City of Irving

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Condition Analysis

Criticality Analysis

Hydraulic Capacity Analysis

TxDOT/ Development

Conflict Analysis

GIS vs. Original Hydroworks Model

Original Hydroworks

City’s GIS

29

Updating the Current GIS to Match Exiting Sewer Model

• Old Model Lines did not match current GIS

• Old model utilized Unique ID needed in the GIS

• Unique ID was populated in sequential order by upstream line

• Some connectivity issues were discovered by new sewer model

• As-Build research and Survey was needed in some areas

• Model and GIS needed to have a one-to one relationship.

Identified GPS Survey Point

GIS vs. Original Hydroworks Model

GIS vs. new H2OMap SWMM model

Utilized the previous Infoworks Model, GIS data, as-builts and survey data to update & complete

the wastewater model. Original

Hydroworks City’s GIS

Identified GPS Survey Point

City’s GIS

New H20Map SWMM

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Updating the Current GIS to Match Exiting Sewer Model

GIS Update: Data Used

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• Existing GIS Database

• As Built Data

• Survey Data

• Mark-Ups from City’s Field Operations

GIS Updates: The Process

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• Researched sewer lines that were critical to the Model and were either fragmented or required connection clarification.

• Created an exact duplicate of the City of Irving SDE in order to facilitate the data exchange between FNI and Irving's GIS Department.

• Linked the As-Builts to GIS in order to streamline the research process.

• Field Operations were involved in areas where no As-Builts were located.

• Surveyed critical areas with manhole x,y,z and invert elevation where field clarification was needed.

• Populated and flagged critical attribute data inside the GIS

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GIS Update: Critical Lines Research

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GIS Update: Critical Lines Research

GIS Update: Attribute Updates

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• Tracked by person who last updated the GIS

• Provided the source of the attribute data

• Provided location of the source of the attribute data

• Identified if the sewer line was modeled

GIS Updates: The Benefits

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• Developed confidence in the GIS by flagging attribute data by source.

• Business process developed for sustainable Model to GIS Linkage and vice versa.

• GIS is still the primary source for attributed and spatial Data

• City of Irving used FNI Database to update their GIS on verified Lines.

• Better Data in the GIS makes for better decisions in RBA process.

QUESTIONS?...

37