hydrograhic surveys the key to surface water planning and ... · hydrographic surveys presented by...

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Presented by Trent Lewis, FPCFor the 2017 TFMA Conference

Need more help? [email protected] direct

Hydrographic Surveys

The Key to Surface Water Planning and

Management



Over 1000 INLANDHydrographic Surveys

Completed



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Hydrographic Surveys



True or False?Marine and freshwater hydrographic surveys implement the same instruments, techniques and knowledge base?

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Find the bottom



Why Survey?



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Why Survey?



Why Survey?



Why Survey?

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Why Survey?



Why Survey?



Why Survey?

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Why Survey?



Why Survey?



Why Survey?

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Why worry about siltation?

• Increased flow• Constricted flow• Impeded flow• Storm Water Encroachment• Flooding/Safety• Erosion• Trash/debris collection• Water quality degredation• Invasive aquatic plant growth• Decreased storage capacity• Increased nutrient and toxin

concentration

• Decreased Aesthetic Appeal• Wildlife/Aquatic Life• Recreation• Property value degredation• Permitting• Government Intervention• Health/safety/welfare of people





How Do We Survey?

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Presented by Trent Lewis, FPCFor the San Antonio Branch | ASCE


4 Components of Accuracy

• Survey Crew

• GPS Instruments (x,y)

• Sonar Instruments (z)

• Data processing protocol

Missing component(s) = decreased accuracy



Accuracy #1 - Survey Crew

EXPERIENCE AND SKILL in HYDROGRAPHIC SURVEYING is

MANDATORY

• Execute to meet client expectations

• Establish tide, setup and calibration

• Ground truthing

• Evaluate environmental factors that affect survey

• Transect establishment and tracking



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Accuracy #2 - GPS• Real Time Kinematic (RTK

or RTK with VRS) – 0.10 ftaccuracy

• Differential GPS – 0.5-1.0 ft accuracy

• Location accuracy (x,y) can affect end product



Accuracy #3 - Sonar

Recreational | Survey-grade



Accuracy #4 – Post Processing

Survey-grade data – reviewed point for point

Recreational data – generalized and averaged

Check out the maps to see the difference……….

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Accuracy #4 – Post Processing



Hydrographic Survey Applications for Engineers, Public Works and Agency

• Planning, permitting and modeling

• Dredging planning, EOC and verification

• River-crossing utilities

• Renovation planning and execution

• Sedimentation monitoring (over time)

• Land use planning

• Construction and excavation

• Water volume calculations (strapping tables, capacity curves)



Hydrographic Survey General Applications

• Aquatic vegetation mapping/control

• Safety, rescue and emergency use

• Fisheries management

• Boating and fishing

• Fisheries/wildlife habitat development

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Hydrographic Survey Projects• Urban storm water systems – cities, developers,

existing communities, dam safety

• Drinking water suppliers – intakes, lagoons, sediment basins

• Safety and rescue operations – fire/police

• Environmental consulting – wetlands, lakes, wildlife

• Reserve studies – projecting dredging needs

• Dredging verification

• In-house – modeling, planning, permitting



Potable Water Intakes



Power Plant Lakes

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Potable Water / Utilities





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Pre/Post Dredge Analysis

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Water Utilities | Irrigation Planning



Dredging Planning | Verification



Sedimentation Tracking

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River and Stream Systems



Watershed & Wetland Delineation



More Specialized Hydrographic Surveys

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Post Dredge Analysis



Post Dredge Analysis



Dredging Progress Report

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River Pipeline Crossing



Case StudyIowa DNR

Client: Iowa DNR PROJECT: DNR lake dredging

Scope: $6.5M – based on studies performed before the project started

Engineering company created a bathymetric map, but no one measured sediment

RESULT: Calculations by the engineering firm were 1.5M CY short and the client,Iowa DNR had to settle with the dredging company and file a claimwith the engineering firm’s professional/E&O insurance company.



Case StudyLake Association

Client: Hidden Cove Lake Association PROJECT: Lake Dredging

Scope: POA hired an engineering firm to develop a 5, 10 and 15 year phaseddredging plan based on theoretical/modeled sediment accumulation.

RESULT: POA purchased their own dredge, mobilized it, started dredging anddiscovered the sediment was not what the engineer modeled it as.

We performed a hydrographic survey and learned that the estimated 100,000 CYof sediment was only 8,000 CY and could have been performed by a dredgingcontractor for $300,000. The POA had already spent $850,000 on engineeringand a dredge.

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Case StudyPower Plant Ash Pond



Case StudyPrecision Dredging/Excavation



Plan the work, work the plan

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Monitor, project and plan







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Would you spend $3,000To Save

$30,000?



Would you spend $20,000To Save

$200,000?



First Step?

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There are no substitutes or short cuts in hydrographics





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Trent Lewis, FPCSenior Consultant

Engineered Storm Water Solutions

[email protected]

hydrograhic surveys the key to surface water planning and ... · hydrographic surveys presented by...

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