Levee Monitoring with Distributed Strain Sensing, Black Hawk, LA | W81EWF 20 SOI 0029

Frequently Asked Questions (FAQs)

What is the "Levee Monitoring with Distributed Strain Sensing, Black Hawk, LA" opportunity?

It is a U.S. Army Corps of Engineers (Department of the Army) research and development cooperative agreement focused on improving levee monitoring for early signs of failure, specifically at the Black Hawk, Louisiana site.

What problem is this project trying to solve?

The project aims to improve early detection of levee distress during high water and flood events by identifying two dangerous mechanisms: seepage and sand boil formation. These issues can develop in the foundation and may not be obvious at the surface until conditions worsen.

What is the main goal of the project?

The central goal is to test whether distributed fiber optic sensing can reliably detect and track seepage and sand boil formation so potential problems can be identified earlier than with traditional approaches.

How is this approach different from using traditional point sensors?

Instead of relying on point sensors placed at a limited number of locations, the concept uses fiber optic cable as a long, continuous sensor. This allows monitoring of large stretches of a levee at once, with spatial detail on the order of meters and total monitored lengths that can extend for many kilometers.

What fiber optic methods are considered in this opportunity?

Two distributed fiber optic methods are considered: distributed strain sensing (DSS) and distributed acoustic sensing (DAS). The emphasis in this opportunity is clearly on DSS.

What is distributed strain sensing (DSS)?

DSS is a method where a specialized instrument (an interrogator) is connected to a fiber optic cable. The interrogator sends laser pulses down the fiber and measures the light scattered back from microscopic imperfections in the glass. Using Brillouin scattering, the frequency shift in the returned light is related to strain along the fiber, allowing strain estimates at many points along the cable rather than at a single sensor location.

What does it mean for the fiber to be a "continuous strain sensor"?

It means the cable can provide strain measurements along its length at many closely spaced locations. In practical terms, the fiber can reveal subtle deformation patterns across a large area, rather than only reporting conditions at a few discrete instrument points.

Where will the field implementation take place?

The field implementation will be installed as a test bed at the Black Hawk, Louisiana site.

What is a key design feature of the test bed described in the opportunity?

A key design feature is the use of vertical fiber sections that pass through the upper clay blanket and extend into the underlying sand layer. This configuration is intended to capture vertical strain.

Why does the project focus on vertical strain measurements?

The opportunity describes a hypothesis that, during a flood, seepage can raise pore pressure in the sand substratum. That increase in pore pressure can exert upward force on the clay blanket, producing uplift or deformation that should induce measurable strain in the vertically oriented fiber segments.

How would DSS provide early warning for seepage-related issues?

By tracking strain changes over time in the vertical fiber segments, the project will evaluate whether DSS can produce a meaningful early warning signal related to seepage pathways, uplift pressures, or developing instability before issues become visible at the surface or escalate.

What types of partners or collaborators is the opportunity looking for?

The opportunity calls for collaboration in two main areas: (1) contributing to the design of the fiber optic test bed (layout, installation approach, sensor configuration), and (2) analyzing and interpreting DSS data produced by the interrogator over the life of the project.

What kinds of work are expected under the test bed design collaboration area?

Partners can help ensure the layout, installation approach, and sensor configuration are suited to capturing the right deformation signals in the levee foundation and clay blanket, including the vertical fiber configuration described.

What kinds of work are expected under the data analysis and interpretation collaboration area?

Partners are expected to help analyze and interpret DSS data, including developing practical algorithms and workflows to record data continuously, process it for operational monitoring, and present results in a decision-support format.

Why is algorithm development highlighted as a major expected contribution?

Strain signals can be influenced by multiple factors such as hydraulic loading, temperature effects, installation conditions, and normal background changes. The opportunity anticipates the need for algorithms that can distinguish meaningful event signatures from noise, track changes over time, and display those changes in an accessible monitoring format.

What other instrumentation may be used to validate or corroborate DSS interpretations?

The opportunity anticipates using corroborating instrumentation such as piezometers and resistivity probes to help validate interpretations and connect measured strain patterns to real seepage or boil-related events.

What is the funding agency and program context for this opportunity?

This is a discretionary funding opportunity offered by the Department of the Army, U.S. Army Corps of Engineers, under Funding Opportunity Number W81EWF 20 SOI 0029 and CFDA 12.630.

What type of award is being offered?

The instrument type is a cooperative agreement, which typically implies active involvement and coordination with the government team rather than a hands-off grant.

What is the award ceiling for this opportunity?

The listed award ceiling is $90,000.

What was the closing date for the opportunity?

The original closing date was 2020-08-14.

Who is eligible to apply?

Eligibility is restricted to non-federal partners of the Californian Cooperative Ecosystems Studies Unit (CESU). Only organizations within that CESU framework can apply.

Does the opportunity indicate a preference between DSS and DAS?

Yes. While both distributed strain sensing (DSS) and distributed acoustic sensing (DAS) are recognized approaches and are mentioned, the opportunity places clear emphasis on DSS.

What is the role of the interrogator in DSS?

The interrogator is the specialized instrument connected to the fiber optic cable. It sends laser pulses through the fiber and measures backscattered light, using Brillouin scattering to relate frequency shift to strain along the cable.

What monitoring outcomes is the project aiming to deliver?

The project aims to determine whether DSS can be used operationally to detect and track seepage and sand boil development, supported by continuous data recording, processing workflows, and outputs presented in a way that supports levee monitoring decisions.