A04_SOW_for_RFQ_2.docx

STATEMENT OF WORK FOR

Development and Testing of a Pressure-Difference Bedload Sampler Attachment to Mitigate Scooping

I. GENERAL INFORMATION

A. INTRODUCTION: This statement of work is for the development and testing of an improved pressure-difference bedload sampler to prevent bias introduced by scooping. Specifically, the improvement is an attachment to the nozzle of bedload sampler. This attachment has an operable door that prevents sediment from entering the sampler except when the door is open. Development and testing of this improvement is expected to lead to a standardized, calibrated piece of Federal Interagency Sedimentation Project (FISP)-maintained equipment that will facilitate more-consistent and more-accurate measurements of bedload transport.

B. BACKGROUND: In FY 2016, the FISP funded testing of the influence of sampler bag mesh size and type on the hydraulic efficiency of pressure-difference bedload samplers (Bunte et al. 2017), results of which identified, in part, that scooping a few gravel particles into a sampler may well introduce more error than bag mesh size and type. Practitioners regularly encounter challenges in bedload sampling driven by uncertainty in knowing whether scooping of the bed surface has biased a bedload measurement collected using a pressure-difference sampler. This uncertainty has been compounded when working from raft-based platforms, and in flows too deep or too turbid to visually confirm (either directly or from underwater photos or videos) if the sampler scooped the bed.

The lack of a solution is problematic because pressure-difference bedload samplers are so widely-used for measuring bedload transport in streams and rivers. Bedload measurements using pressure-difference samplers have historically been, and continue to be, collected as a component of operational monitoring programs. Consequently, eliminating bias introduced by scooping would provide near-universal benefit to these monitoring programs, as well as to any other bedload measurements collected using pressure-difference samplers.

Reference: Bunte, K., Klema, M., Hogan, T., and C. Thornton. 2017. Testing the Hydraulic Efficiency of Pressure Difference Samplers While Varying Mesh Size and Type. Submitted to the Technical Committee of the Federal Interagency Sedimentation Project. Colorado State University, Engineering Research Center, Fort Collins, CO. 75 p., plus appendix.

C. PURPOSE AND SCOPE: The goal of the work is for the vendor to develop and test an attachment to pressure-difference bedload samplers that will lead to a standardized, calibrated piece of equipment that will facilitate more-consistent and more-accurate measurements of bedload transport by preventing bias introduced by scooping. To achieve this goal, the purpose of the work is to carry out the initial development and testing of the proposed attachment. The vendor will fabricate an attachment for testing, and the testing can be carried out in a flume. The results of the development and testing will be documented in a report.

II. WORK REQUIREMENTS

A. TECHNICAL REQUIREMENTS

The key technical requirement is the development (design and fabrication) of a prototype attachment for testing. With the prototype in hand, the hydraulic efficiency of the sampler with the attachment needs to be compared to the hydraulic efficiency of the sampler without the attachment (ideally, using data from the FISP’s FY 2016 funding testing (Bunte et al. 2017)).

B. DELIVERABLES

The prototype attachment, design plans for the attachment, and testing results in a report

III. SUPPORTING INFORMATION

Period of performance is from October 1, 2019 through September 30, 2020.